University of Nigeria of Malt...University of Nigeria Research Publications Author OKPALANMA, Emeka...
Transcript of University of Nigeria of Malt...University of Nigeria Research Publications Author OKPALANMA, Emeka...
University of Nigeria Research Publications
OKPALANMA, Emeka Felix
Aut
hor
PG/M.Sc/88/6772
Title
Production of Malt-Based Syrups from Sorghum (Sorghum Bicolor) and Millet (Pennisetum
Typhoiodes) Grains
Facu
lty
Agriculture
Dep
artm
ent
Food Science & Technology
Dat
e
May, 1991
Sign
atur
e
I ~ ~ U C T I O N OF MALT-BASED SYRUPS FROM SORGHUM(SORGHUM BICOLOR) AND MILLET (PENNISEWM TYPHOJDES ) GRAINS
OKPALANMA, EMEKA FELIX PG/M .sc./88/6772 '
DEPARTMENT OF FOOD SCIENCE AND TECHNOLOGY FACULTY OF AGRICULTURE, UNIVERSITY OF NIGERIA,
iJSL'KKA.
I N PARTIAL FULFUS/1ENT OF THE REQUIREMENTS FOR THE AWARD OF MASTER OF SCIENCE DEGREE (M,SC,) I N
FOOD SCIENCE AND TECHN'OLOGY, UNIVERSITY OF NIGERIA, NSUKKA
MAY, 1991 .
Mr. Okpalamm, Emeka F e l i x , a postgraduate student i n
t h e Department of ~ ' o o d Science and Technology, and with
r e g i s t r a t i o n Number PG/M,~o/88/6772 has s a t i s f a c t o r i l y
completed t h e requirements f o r course and research w r k
f o r t h e degree of master of science i n Food Science and
Technology, The work embodied i n t h i s t h e s i s i s o r f g i n d
and has not been submitted i n part o r f u l l f o r any o t h e r
diploma o r degree of t h i s o r any other unive~sity,
t
Dr. C.C.1 OlQUOHA /&JkhM DR. A e L . IIGXDRONYE
SUPERVISOR.
DEDICATION
his thssis Is dedicated to all widours
who could muster enough courage, patience
to stay and train their children properly
as my mother did.
i r"
iii.
ACKNOWLEDGEMENTS
I want t o express sincere grat i tude and ' d e e p s t appreci~lt ion to
m. A. I. Ihekoronye, my S~p@JXisor, f o r the many hours hg spent i n
b l p i n g m e plan, canplete and evaluate this research project. I also
extend my th&s t o all my lectu~cers i n the department of Food Science
tind Technology. i
I grateful ly acknowledge t h assistance of the departmental
technologists .: Onuchukwu, Onyebuashi , Kalu and Nwokedi of ~ iochemis t ry
department.
I express my personal thanks to Rev. Fr. Eutabasfl i , M., M r . Obadiegu,
M., Dr . Chinyere, P. and Kene Oranu for many things. Also to M r . J. Nwabue
f o r h i s patience and for t i tude i n typing the. manuscript.
Fihally, I owe a special debt of grat i tude to a l l my lec ture rs i n
the University of I f e , during my f i r s t degree programme.
V.
Page TABLE OF CONTENTS
TITLE PAGE
CERTIFICATION
iii DEDICATION . .
ACKNOWLEDGEMENT
TIlBLE OF CONTENTS
LIST OF TABLES
v i i LIST OF FIGURES
v i i i ABSTRACT
INTRODUCTION
LITERATURE REVIEW
Production of Sorghum and Millet; Grains
sorghum grain . . Millet grain . . C h e m i c a l and Biochemical studies on Sorghum and Millet grains . . sorghun grain . . Millet grain . .
' i Malting' Character is t ics of Nigerian Sorghum and Millet VazLeties . . sorghum malt . . ~ i l l e t malt . . ~ l u c o s e syrups . . k f i n i t i ons . . ~e-s of Production of Glucose Syrups
~ c i d conversion . . Acid-enzyme conversion .. Enzymeenzyme conversion 2 2
Refining . . 25 ,
Properties and Functional uses of Glucose @..-..-\a ' C ) C )
Malt Based Syrupm . . Mtuihing method . . Preparation of m a l t syrups
MATERIALS AND METHODS . Materials . . Source of cereal grains .. Methods . . Determination of Malting Characteristics of the Cereal G r a i n s , Sorghum and Mil le t
Determination of moisture content
Determination of percentage foreign seeds and braken kernels , Determination of thousand corn weight
Determination of getminative energy
Determination of germinative capacity
Det@rmination of Optimum Malting conditions of the Cereal Grains ,,
Moisture Content as a function of s teep time
Determination of Optimum steep time
Determination of Optimum g e d n a t i o n period
Effects of ki lning a t 4s0c and varying periods of time on moisture con t e n t of the ma1 t.
Determination of malting losses as a function of gemination periods .. Production of Sorghum, M i l l e t Malts.
Evaluation of M a l t ' s qual i ty charac te r i s t i cs
Determination of Cold Water ex t r ac t
Determination of d i a s t a t i c power
Dekermhation of ~ o t water ex t rac t
Determination of malting l o s s
Studies on Malt's Amylases
Extraction of m a l t anylase
Preparation of 1% buffered s ta rch substra te
. vi i .
3.5.3 Preparatioh of Maltose Calibration curve 43
3.5.4 Datemination of optimum p~ f o r amylase ac t iv i ty . 44
3.5.5 Oetenninationof Optimum temperature fo r amylase ac t i v i t y .. 44 .
3.5-6 s ta rch Extraction £ran the Cereal grains 44
3 7 ~ r o x h a t e / ~ h e m i c a l Analysis. of grains, m a l t t i and starches f ran sorghum and m i l l e t . 47
3.7- 1 Crude Protein determination 47
3.7.2 Fat determination 48
3,.7.3 Crude fibre determination ' 49
3 ..7.4 ~ s h Determination
3.7.5 Total Carbohydratedetennination
3,'7,6 ~ e l s t i n L z a t i o n temperature determination 5 1
3.7.7 Starch determination in s ta rch concantrate by hydrolytic method. 5 3
3.8 Production of M a l t Based Syrups 5 4
3.8.1. wort Preparation by three stage'dacoction mashing method from sorghum malt 54
Effect of varying mash concentrations and aaccharification periods on reducing sugar contents of worts i n a three stage decoction mashing, .. I 54
Effect of varying concentrations of glucomylase and saccharification periods on the reducing sugar content of malt hydrolysates 5 5
M a l t Based Syrup Production 55 .
Glucose Syrup Production 5 6
Determination of some properties of syrups 57
~e t enn ina t ion of spec i f ic gravi ty/l)egtee baume' 57
Percentage reducing sugar content/ Dextrose equivalent(IX1 value determination 58
Determination of Colour 60
CHAPTER 4.
4.1
CHAPTER 5.
RESULTS AND DISCUSSION 6 1
Malting charac te r i s t i cs of the cereal grains, sorghum and millet. . . 61
Optimum malting conditions of ths cereal grains, sorghum and mi l l e t 62
Evaluation of m a l t 1 s qual i ty charac te r i s t i cs 68 Determination of optimum pH and temperature condi t iom f o r malt's amylase act ivi ty . 70 ~roximate/chemical analysis of the sorghum/ m i l l e t gra ins and malts. , . 74
Chemical analyses of starches extracted from millet and sorghum grains. 76 Effects of varying mash, glucoamylase concantra- t tons and sacchar i f icat ion periods on redwing sugar contents of the wort syrup. 7 7
Properties of malt based eyrups and acid enzyme converted glucose syrups. 81 . SUMMARY AND CONaUSICbJS 84
REFERENCES
APPENDIX
LIST OF TABLES
TABLE 1 - Proximete analyses o f .Pear l m i l l i t ( ~ W I 3 ) (meman with . ranges i n Parenthesis where available) $0
1, 2 - Sorghum m a l t proximate analysis a f t e r four days gemination . As
n 3 Checklist of properties and funct ional 'uses of corn syrupta In spec i f ic food products. 30
t* 4 Malting charac te r i s t i cs of the cereal grains, Sorghum and millet . 62
5 valuation of malt * s qual i ty [email protected] 70
@ 6 ~roximate/chemical analysis of grains and malts 75
n 7 Analyses of starches from millet and sorghum grains 77
8 Properties of m a l t based syrups 83 -
" 9 Properties of acid-cenzyme converted glucose 83 syrups. . . 4
LIST OF FIGURES
A General manufacturing procedure f o r corn syrups 25
Properties and functional uses of corn syrups 3 1
Flow char t of w e t mill ing operations i n s ta rch production from cereal grains .. 46
Flow char t of acid-enzyme converted glucose syrups production e m 56
Flowchart of malt based syrup production 57 ~t'
Plo t of moisture contents(%) against steeping time(hours) . . 63
Plo t of d i a s t a t i c power(o~) against steeping time (hours) a f t e r 4 days of germination 64
Plo t of d i a s t a t i c power (OL) against gurmination periods(days1 a f t e r Sohours of steeping . 6 6 .
Plo t of malting loss(%) against gemination periods(days) . 6 7
Plo t of moisture cogtent(%) against kilning period(hours) a t 45 C. . , 69
p l o t of mg maltose against p~ . 72 . .
Plo t of maltose ca l ib ra t ion curve 7
p l o t of mg ma1 tose against t e m p e r a t ~ r e ( ~ ~ ) \.73
p l o t of glucose standard curve 7 8
Plo t of mg dextrose against mash concentration(%) and time(hours1 . . 79
Plo t of mg dextrose against ~ 1 ~ = c s - i - ~ ~ L ~ c concentration(%) and time (hours)
xi. ABSTRACT
he s u i t a b i l i t y of two cereals(sorghum and millet) f o r the production
of malt-based slyrup w a s determined.
i'roximate analys is waa c a r r i e d on the grains. The g ra ins were steeped
f o r SO hours, germinated for 5 days a t room temperature and k i lned f o r 48hrs
a t 4s0c. Ma1 t i n g c h a r a c t e r i s t i c s of t h e g ra ins determined include: t h e
germinative energy, germinative capaci ty , 'Hot water e x t r a c t and d i a s t a t i c
power. Starch w a s ex t rac ted from the two g ra ins and used f o r syrup production
Optimum condit ions f o r the ac t ion of m a l t amylases in syrup production were
a l s o determined,
The ma1 tg s qua l i ty c h a r a c t e r i s t i c s analysed showed t h a t sorghum gra in
generated b e t t e r malt. Malted gains contained higher amounts of p ro te in and
crude f i b r e , and lower amounts of f a t , ash, and t o t a l carbohydrates than tha
h a l t e d gains. 1000 g r a i n s of m i l l e t and sorghum weighed 6-8 and 33,3g
respectively. Malting l o s s values w e r e 16-20% f o r m i l l e t and 12016% f o r
sorghum. Germinative capaci ty of the millet g ra ins was 85% while sorghum
gra ins had a germinative capaci ty of 90%. Hot water e x t r a c t values were
1 8 0 . 1 ~ ~ / k ~ f o r m i l l e t and 2 0 3 ~ ~ ~ ~ f o r sorghum, O~timum d i a s t a t i c power of
2 7 O ~ and 3 2 O ~ were obtained f o r m i l l e t and sorghum reepect ive ly , Sorghum
s t a r c h yielded syrup of a b e t t e r quality than millet s tarch . Sorghum s t a r c h
a l s o has a lower g e l a t i n i z a t i o n temperature and lower ash content than
millet s tarch . Optimum pH range f o r alpha amylwe a c t i v i t y i n both m a l t
e x t r a c t s was 6-7, Optimum tempera- range f o r anylase a c t i v i t y was
found t o be 40-50°c f o r m i l l e t and 60-70°c f o r sorghum.
CHAPTER 1
INTRODUCTION
The development of ma1 t based syrup involves th ree fundamental stages:
'(1) Production of m a l t by a process c a l l e d malting.
(ill Preparat ion of wort from t h e malt by d e m t i d n mashing process.
(iii) Further sacchar i f i ca t ion o f the w a r t to malt based ~ y r u p using
external microbial amylases. ,
Glucose syrup i s t r a d i t i o n a l l y produced from corn s t k c h , hence
its name 'Corn syrupr. I t is t h e pur i f ied 'concentra ted aqueous so lu t ion
of n u t r i t i v e saccharides o f Dextrose equivalent(DE) 20 o r more obtained .
by hydrolysis of e d i b l e s t a rches !Whistl.er a t ' al,, 1984). The hydro ly t i c , -1
agents include ac id , microbial amylases, malt amylases and combinations of
these. Fur ia (1968) has described the technology of glucose syrup
production, while M ~ C ;U&istgr(1979) has described t h e ac t ion p a t t e r n s of
enzymes used i n t h e commercial corn syrup production.
Malting is e s s e n t i a l l y a b io log ica l process in which t h e germination
of cereal g ra in i s c a r r i e d o u t in a con t ro l l ed environment. The t echn ica l ly
intportant f e a t u r e s of gemina t ion are t h e synth.gies of hydrolyt ic enzymes
and t h e degradation of t h e g r a i n structure. When both processes have
reached the des i red s tage , t h e germination is in te r rup ted by drying o r
k i ln ing,
Malting s tud ies have been done by severa l workers; Aisien(l983)
invest igated t h e u t i l i z a t i o n of soluble carbohydrates during sorghum
yern~indtion. . Novellie (1960) es tab l i shed t h a t sorghum ma1 t do not posses
t h e b - c u n ~ l c i s e ,protease, c e l l u l a s a and hemi$ellulase a c t i v i t i e s of e i g h t
c u l t i v a r s of process millets.
Decoction mashing t r a d i t i o n a l l y employs malt which is less modified . -. . L
thm t h a t used i n infusion mashing and is only l i g h t l y kilned(Briggs.5: &,
w r i n g t h e k i ln ing process, an optimum temperature is chosen t h a t
s t r i k e s a balance between t h e development.of the c h a r a c t e r i s t i c m a l t
f lavour, colour and the sustenance of high ma1 t d i a s t a t i c power. The 1
colour i s produced dur ing 'k i ln ing through mai l lard reac t ions between the
prote ins and sugars present i n t h e m a l t , (a na tu ra l browning reac t ion) ,
Malt based syrups are used widely i n the food industr ies:
(i) Brewing industry: D i a s t a t i c syrup contr ibutes t o converting o t b r
s tarchy adjuncts to simpler sugars while non-diastat ic mal t syrup
contr ibutes towards t o t a l fermentables.
(11) Malt syrups .are increas ingly being used as na tu ra l food colourants
thereby replacing caramels,
(iii) I n the baking industry, D i a s t a t i c malt syrups may be used i n breads
a s a yedst food t o r e l eas ing sugars n a t u r a l l y and con t r ibu te t o loa f volume
irnd texture. Malt syrup is a l s o used i n brown bread and dark cake manufacture,
breakfas t ce rea l ,and b i s c u i t manufacture . ( i v ) I n thcphannaceut ica l industry, m a l t syrup could be incorporated i n t o
i n f a n t l i q u i d drug mixtures a s sweetening, colouring and f lavour carriers. -
G ~ U C O S ~ syrup is widely used i n confectlonary and baking indus t r i e s ,
i n canning of f r u i t s and vegetables, s o f t drink indus t ry , i n beverages, and
other products requi r ing sweetness. Hoover(1963) has i l l u s t r a t e d t h e
functional p roper t i e s of corn syrups a s they r e l a t e b > t h e type of conversion,
f i g u r e '2 Hoover(1964) has a l s o prepared a c h e c k l i s t of p roper t i e s and
funct ional uses of corn syrups in a wide va r i e ty o f foods, (Table 9)
The value of Niger ia ' s annual consumption of glucose syrup was
estimated atsN80.625 mi l l ion and t h a t of c r y s t a l l i n e glucose In form of
dextrose monohydrate was est imated a t about W60 mil l ion(Federa1 I n s t i t u t e
of I n d u s t r i a l Research, Technical memorandum No, 25, 1970)- These d a t a
derived from the l imi ted market surveys conducted were more l i k e l y to be
an under es t imates than over-estimates.
I n Nigeria, t h e r e l a t i v e abundance o f Sorghum and millet crop8 w i t h
an average m u a l production f i g u r e of 4,8 metric tonnqr and 2.4 metric
t o m e s respectively(Sumraru* miscellanous paper 90, 1979), has prompted
the current research e f f o r t s towards cos t reduction. I n 1982 alone,
Nigeria's import value f o r m a l t was p u t a t about M40 mill ion i n foreign
exchmge. Both wheat and corn are today in Nigeria ,Golden cereals': EF!A, i
hence the quest f o r subs t i tu te and/or blends.
Malting of t h e loca l cereals , sorghum and millet, generate endogenous
malt amylases which augment the imported microbial amylaae used i n the .
sclccharification process of malt symp pr=2utticn, thereby saving cost.
A i m s and Objectives of the Study:
The study was carr ied o u t to prepare malt-based syrups from loca l ly
avail able cereal grains. The spec i f ic objectives were:
1. t o determine which of the two cereals , sorghum and m i l l e t has a higher
ma1 t ing potential .
2. to determine the malting conditions necessary f o r optimizing the ,
sorghum/ m i l l e t malts' d i a s t a t i c power.
3. to determine the leve ls of microbial ainylase and conditions su i tab le
f o r the production o f r e l a t i ve ly cheap malt based syrup.
CIWTER 2
2. LITERATURE REVIEW
2.1 Production of Sorghwn and M i l l e t grains:
2 . 1 Sorghum qrain:
h l though vorghum rank8 f o b # mong c e r e a l s in c u l t i v a t e d area world
wide following wheat, r i c e , and maize, i t i s the most important cereal i n
Nigeria occupying about 46% of t h e total land area devoted t o the growing
of ceredls. The a rea devoted t o sorghum has increased by about 25% over
the l a s t two decades growing from 4.6 mi l l ion hectares i n 1959 t o qin
e ~ t i m a t e d 6.1 mi l l ion hectares i n 1979. Sorghum present ly accounts f o r
about 50% of t h e t o t a l c e r e a l production i n the country. Production has \
gone from 2.5 mi l l ion metric tonnes i n 1960 to 4.8 mi l l ion metric t o i a s
i n 1978(Samaru miscellaneous paper No. 90, 1979). I n 1981/82, production
was 16,192 tonnes and y i e l d per hectare was 841 kilograms (Federal o f f i c e i
of s t a t i s t i c s , Lagos, 1983. Survey of modern Holdings of Agriculture
1981/82, p. 20).
The o r i g i n of t h e crop was traced to o the r regions of Africa, from
Ethiopia across the Sudan (Damon, 1962). . A survey of the indigenous
sorghum v a r i e t i e s reveal four economically important varieties name:ii, I
Guinea, kaura, Farafara , and Chad races (Buntung and C u r t i s , 1970).
2.1.2 ~ i l l e t grain:
Millet although n o t as important a s some of the o the r cereals when
t o t a l world production figures are considered >it is nevertheless t h e 6
6.
bas ic d a i l y d i e t ' o f severa l mi l l ion people i n Africa and I n d i a ( ~ a r t i n e t G., -
There is an average annual production of 2.4 mi l l ion metric t o m e s and
d nat ional average y ie ld of 75Okg/hd (Sanaru miscellanous paper, 90; 1979). - 1n'1981/82 production w a s 9,862 t o m e s , and y i e l d per hectare , 566 kilogram
( ~ e d e r a l Office of s t a t i s t i c s , Lagos, 1983). There are two main types of
millet grown i n Nigeria. These are the Gero and Maiwa types. The Gero
m i l l e t s are of s h o r t e r dura t ion taJcing 75-100days t o mature. Maiwa on the
o the r hand takes between 120-150 days t o mature. T k Gero type, because
of i t s g r e a t e r adap tab i l i ty , is favoured over maiwa and over 8C% of a l l
millet grown i n Nigeria is of the Gero type(Samaru miscellanous paper,
NO', 90, 1979'). Rachie (1974 l i s t e d the canmon and corresponding s c i e n t i f i c
names of t e n v a r i e t i e s of millets grown world over.
2,2 chemical and Biochemical s t u d i e s on Sorghum and Millet grains:
2,2,1 Sorghum grain:
'Neucere and sumrell (19801, s tudied the proximate analys is , f a t t y
dcid composition, f r e e sugars, mineral content and the i id is t r ibut ion of
tannins i n f i v e v a r i e t i e s of sorghum biccdor(L). Moench, They showed t h a t
the va r i e ty wi th predanlnantly f loury endosperm (NSA 740) has t h e h ighes t
prote in content , . Some d i f fe rences i n f a t , ash, carbohydrate, and , f i b r e -
contents w e r e a l s o noted among t h e f i v e v a r i e t i e s . The content of neu t ra l
l i p i d s i n the f i v e lines of g ra in sorghum ranged from 2.66 t o 3.49%. They
a l s o noted s u b s t a n t i a l d i f f e rences in t he mineral uptake of the f i v e
v a r i e t i e s and according to t h e r e s u l t of comparative m a l y s i s of f i v e
sugars i n theee v a r i e t i e s s tudied , nmely; f ruc tose , glucose., sucrose,
m d l toae a d raf f h o s e , f ruc tose and glucose comprised the h ighes t contents
of f r e e sugdrs. m
Rooney a d s u l l i n s (1970) i n t h e i r study, compared the g ra in produced
on d ip lo id ( 2 ~ ) and t e t r a p l o i d (4x1 l i n e s of t h e sorghum, Sorghum b ico lo r
(L) moench, c u l t i v a r T
propert ies . ~ c c o r d i n g
yredter i n kernel size
x 403 f o r physical , morphological and chemical
t o their r e s u l t s , g ra in f r an t e t r a p l o i d was
and p ro te in content and was lower i n s t a r c h content
and test ?eight than g ra in from the d ip lo ids . Mean values of d ip lo id and
t e t r ap lo ids were 12.8 and 15.x prote in , 72.3 and 68.8% s ta rch , 26.8 and
41.4 g/1000 kernels , and 74.3 and 70.0kg/hl respectively. The . resu l t
a l s o showed t h a t endosperm cells of t h e t e t r a p l o i d were l a r g e r than those
of the diploid. Kernel dens i ty and amino acid composition were similar.
Hoseney et &. , (1974 ) examined the s t r u c t u r e of sorghum gra in
samples by scanning e l e c t r o n microscopy. They observed t h a t t h e s o f t o r
opeque endosperm is charac ter ized by r e l a t h e l y l a r g e in te rg ranu la r air
spaces, and showed t h a t its s t a r c h was e s s e n t i a l l y round and covered with
a t h i n sheet of protein. Furthermore, they discovered t h a t t h e hard
endosperm resu l t ed from s t rong adhesion between prote in and s t a r c h and
a lso when t h e hard endosperm was f rac tured , many a ta rch granules were
broken r a t h e r t h k t h e s t a r c h p ro te in i n t e r f a c e being broken. Resul ts
a l s o revealed t h a t a dwarf v'ariety from Sudan. had r e l a t i v e l y few pro te in
bodies i n the endospenn
va r i e ty contained 3.019
and t h a t amino acid analys is confirmed
l y s i n e pe r 1009 prote in , s i g n i f i c a n t l y
t h a t this
more than
normal i n sorghum grain. 1
S u l l i n s and ROOney (1974') compared sorghum gra ins t h a t d i f f e r i n
endospenn t ex tu re and endospenn type i n order to evaluate the usefulness
of microscopy t o account f o r d i f f e rences observed i n the feeding p roper t i e s
of these grains. They observed t h a t t h e waxy.aorghum kernel sec t ions . . .
hdd the smdllevt proportion of per iphera l endospenn a rea of the four
g ra ins excrmined. The waxy sec t ions were a l s o more r a p i d l y so lub i l i zed by
pronase and alpha- amylase enzymes and by buffered .rumen f l u i d than, the
non w a x y sect ions. According t o them, the f indings 'might account f o r
observcltions of feeding trias in which steers fed non-waxy sorghum gra in
d i e t s r equ i re 8 t o 20X more feed t o produce a pound of g ra in than steer
fed waxy sorghum gra in d i e t .
Deyo et &., (1990) determined t h e proximate and amino ac id composition
of mature and immature samples of sorghum grain. Thei r d a t a i n d i c a t e
marked d i f fe rences in amino acid content. ~ h e i observed t h a t crude
p ro te in content of immature and mature sorghum gra in was shilar. The
feeding s t u d i e s which they c a r r i e d o u t showed less ava i l ab le energy fram
immature than mature sorghum grain.
Haikerual and ca hie son( 1971) determined total p ro te in and amino i
acid composition of a number ofsorghum sample including those from two
f i e l d experiments. They showed t h a t t h e germ contained ' t he h ighes t proportion
of prote in , followed by the whole kerzel, the endosperm and the per icarp
a l s o t h a t the amino ,acid c a p o s i t i o n of those p a r t s was d i f f e r e n t , with
higher proportion of lys ine , h i s t i d i n e , arginine, glycine, a sp&t ic acid,
threonine, and val ine i n the g e m , than t h e whole kernel.
2.2.2 Mi l l e t grain;
Bcrdi et_ &.,(I9761 i n their work, found t h a t pea r l millet s t a r c h
ranged i n diarneter from 8 - 12 11, somewhat smaller than corn o r sorghum
atarch. They observed t h a t pas t ing p roper t i e s of m i l l e t s t a r c h were
e h i l a r to those of sorghum s t a r c h , except during the 1 hour holding period
a t 95O~. They showed t h a t m i l l e t s t a r c h contained 1% amylose compared
with 23% i n sorghum s tarch . Arnylograms of m i l l e t f l o u r a l s o gave low peak
v i s c o s i t i e s compared to sorghum f l o u r ind ica t jng an ac t ive alpha-anylase 4)
sys tern.
proximate ana lys i s of millet g ra in has been c a r r i e d out. Shepherd
e t , dl., (1972) reported from E a s t Afr ica the proximate composit ionof - - m i l l e t g ra in ( ~ r y weight bas i s ) . P ro te in ranged between 11.5 and 13.8%
l i p i d ranged f r m 4.8 - 9.2%, f i b r e 1.0 - 3.8% and ash, 1.1 - 2.4%.
Table 2.1, shows t h e proximate ana lys i s a s reported by some authors,
general ly, p ro te in (%I vary from 8.4 - 21.8, l i p i d ( % ) from 2.9 - 7.5,
carbohydrate (%) ' f r a n 53.9 - 83.8, Fibre(%) from 1.2 - 10.7, ash ('961, from
Badi - e t ' -- aL., (1976) showed t h a t pea r l millet &aln endospenn was
composed of both hard( t rans lucent1 and soft(opeque) par ts . . The hard p a r t
h s t i g h t l y packed, polygonal shaped s t a rch - granules and a ma t r ix , p ro te in
containing r e l a t i v e l y l a rge , embedded p ro te in bodies. The s o f t endospenn
Fetu
ga
(19
77
) A
frica
Ga
dr
y and B
ideau
(19
74
) A
frica
nagbail( 1
97
7-~
erso
nd
l comnunication to Hulse
Afric
a
et
al.(1
98
0)
- -
Po
pli and
Sin
gh
(l97
2)
Ind
ia
L'p
rety and A
us
tin (1
97
2)
Range o
f means
Range o
f ra
ng
es
Nig
eria
hds lose ly packed, spher ica l s t a r c h granules c ~ v e r e d with a t h i n shee t
of proteih. The s o f t endosperm conta ins many a i r spaces, and no p ro te in
bodies.
Lorenz a d liinze ( 1976 determined a d c&npared t h e functi&nal
c h u a c t e r i s t i c s of p r o s and fcrxtai l millet s tarches with those of wheat
and rye starches. The m i l l e t starches showed higher water binding
c a p c i t y values and g e l a t b i z a t i o n temperatures than t h e wheat s tarch.
with two exceptions, the millet s t a rches produced swelling power values
d t 90°c which were similar t o those of the wheat s tarch . They observed I
t h a t the s o l u b i l i t i e s of t h e millet s t a rches were lower than those of t h e
wheat s t a r c h , except f o r t h e s t a r c h from one va r i e ty of m i l l e t ; and t h a t
the amylograph v i s c o s i t i e s of m i l l e t s t a rches were higher than those of
the wheat s t a r c h a t a l l re ference points.
l tasule~(1977) - - s tudied t h e weight and composition of m i l l e t parts . He
found t h a t the seed coa t s contained r e l a t i v e l y high percentage of prote ins ,
sugars, and f a t s . The seed c o a t s had high contents of pentosans,
ht?raicelluloses, and f i b r e which are s i g n s o'f low n u t r i t i v e value. Removal . of seed c o a t s from m i l l e t s l e d to a higher n u t r i t i v e value.
Ramachandra - e t ' &.,(1977), found t h a t the t g t a l phenol and tannin
l e v e l s of f i n g e r millet v a r i e t i e s i n d i c a t e wide va r i a t ions i n phenolic
contents. T-hey showed thatqwhite g ra in v a r i e t i e s had lower phenolic
content than, the brown-grain varieties. I n v i t r o p ro te in d i g e s t i b i l i t y
values of low tannin samples were higher than those of t h e high tannin
simples. Dehulling had e f f e c t of removing most o f . t h e phenolics from
f inger , rnille t gra ln w i t h .concomitant increase i n i n v i t r o p ro te in
d i g e s t i b i l i t y .
A U ~ U S t - et A. , ( 1979) , analysed f o r p r a k h , SZL~Z acid c = p ~ s i t i W ,
and mineral assay of 14 inbreed l i n e s of pea r l millet(Pennisetum americanum
(L) ~ e a k e ) from the p lan t ,b reed ing . proyrdn a t Ti f ton , Georgia. T k i i r
d a t a shared t h a t p ro te in con ten t varied 'from 10.7 - 17.1%. Chemical
scores on the amino ac ids showed l y s i n e t o be the l imi t ing amino acid.
hey es tab l i shed t h a t mineral content var ied considerably among the
d i f f e r e n t hybrids. The predominant elements were phosphorus and potassium.
p r u t h i and ~ h a t i a ( l 9 7 0 ) s tudied two improved strains4 of Pennisetmm - i
t ypho ideun(@baj ra@) and were found t o have a l i p i d content of about 5.0%
and bound l i p i d content of about 0.5%. They observed t h a t i n the non-polar
f r a c t i o n , s t e r o l esters, hydrocarbons, xd t r ig lyce r ides , are t he p r inc ipa l
cons t i tuents . They separated polar l i p i d s by twodimentional tNn- layer
chromdtography and l e c i t h i n was found to be t h e major component.
Dorisova et s . , ( 1 9 8 2 ) inves t iga ted the e f f e c t of various s t ages of
t h e tecthology of process m i l l e t on t h e amino acid con ten t of m i l l e t
protein. They s t a t e d t h a t t h e l e v e l s of methionine and ty ros ine in
husked m i l l e t increased by about 1196, whereas those of l y s i n e and g lycine
decreased by 1% and 11% canpared to unhusked millet. Polishing of
husked m i l l e t decreased t h e l e v e l of g lycine by 22.- and t h e l e v e l s of
threonine, tyros ine by 7.1% to 13.8% compared to unpolished husked m i l l e t .
Cooking of polished husked m i l l e t decreased to ta l amino acid content by
2.3 ~ d . t ing chdrac teristics of Nigerian sorghum and Millet var ie t ies :
2.3.1 Sorghum malk
Aisian G,, g., (1978) in a study of the germination behaviour of
Guinea corn, (Sorghum vulgare) inves t iga ted its percentage germination
(germination energy) and length of the ascrospi re ranged between 2-2.5cm,
1 he r e s u l t a l s o showed t h a t the optimum moisture con ten i f o r rapid .
gemina t ion was between 35 and 40%, a t opkhum temperat ire of 22Oc. he
r e s u l t s f o r the rest of t h e germinative capci ty , percentage germination a t
d i f f e r e n t times of gemina t ion are tabulated.
Daiber and ~ o v e l l i e ( 1 9 6 8 ) found t h a t g i b b e r a l l i c acid had l i t t l e e f f e c t
on amylase development in normal k a f f i r corn. They observed t h a t only
immature seeds and very l a r g e g ra ins produced more amylase when t r e a t e d with
g i b b e r a l l i c a c i d , - b u t this e f f e c t was much smaller than t h a t found with
barley. They concluded on f u r t h e r inves t iga t ion t h a t amylase ,formation i n
sorghum appears t o be preponderantly' a function ' , of the embryo.
~ o v e l l i e ( l 9 6 0 ) e s t ab l i shed t h a t sorghum malts are poor i n betzi-amylase
compared with ba r l ey malts( b u t s i m i l a r t o Oat and r a g i ) and do not possess i
high d i a s t a t i c power, H e showed t h a t sorghum malts contained beta-ainylase
i n considerable quan t i t i e s , 18-39% of Ule sdcchslri-k'ying r lct ivi ty being due
t o the beta-amylase. H e found t h a t t h e alpha-and b e t a - amylases developed
a t approximately t h e same r a t e during germination since t h e i r ra t io(which
vAries from 0.22:l to 0.64:1) was p r a c t i c a l l y cons tant throughout the
ma1 t i n g process.
~ i s i e n ( 1 9 8 2 ) i n h i s s t u d i e s found t h a t modification i n t h e sorghum
gra in endosperm during seedling growth and malting was associa ted mainly
w i t h increased a c t i v i t i e s of alphsmylas4endo-b)-4lucanase, l i m i t
dextrincise and endoprotease. H e found t h a t t h e major s t a r c h - degrading
enzyme was alpha-amylase and also observed t h a t t h e a c t i v i t i e s of endo-
/+gluccmase, l i m i t dext r inase a d endoprotease were comparatively higher, in
t h e endosperm than in the embryo during seedling growth.
~ d y l o r ( l Y 8 3 ) i n h i s study, observed t h a t when sorghum i s malted, much
of t h e ni trogen i n the kernel i s t ransfered to the roo t s and shoots. H i s
exanination of Osborn p ro te in f r a c t i o n s ex t rac ted from t h e kernel r evea l s
t t ~ t ds i n the case of ba r l ey t h e prolamins are t h e major source of t h e
ni trogen t ransfer red . E'urthennore, he fouhd t h a t t h e 'two most important
f r e e ac ids of sorghum m a l t appear t o b e asparagine and glutamine, as i n
germinated wheat and maize.
w i l l i a m ( 1983) s tudied t h e e f f e c t s of tannin on malting a s we1 . l a s the
change i n polyphenols during malting of b i rd - res i s t an t and non bird-
r e s i s t a n t c u l t i v a r s , H e observed t h a t no d i f fe rence could be found i n
the percent germination nor in the r o o t and shoot production of t h e m a l t s
of the two c u l t i v a r s , H e found t h a t t h e r e was an. increase i n the antho-
cyanidin content of the r o o t s and shoots during malting.
~waifotl983),9ma-irradi~~dtw0 Nigerian species of sorghum - Sorghum acaUdatum(sk. 5912) and sorghum guineense(HP 3 ) p r i o r t o malting - 9' on a c o b a l t i r r a d i a t o r . H e exposed t h e spec ies to t h e following doses;
0.22, 0.44, 1.76, and 4.95 krd - I n t h e assays f o r d i a s t a t i c power,
/+amylase, and a lpbany l - . W h i l e i n t h e assays f o r germinative energy
and lengths of r o o t l e t s and acrospire,, they were exposed t o a dose of
0-5 krd. H e found t h a t a dose of 1.76 krd ra i sed the d i a s t a t i c 'power,
6-mylase ,g(- dmylclse, germinative energy, and lenghts of roo t l e t s and
crcrospire ~n(utimcrlly r e l a t i ve to those of the unirradiated sorghun is' t%
species studied. H e observed t h a t the e f f ec t of 1.76krd was, however,
higher i n Sk 5912 species than i n HP3 species.
irnfchie( 1982) studied f i ve Nigerian sorghum 'var ie t ies B.E.S., F.F.B.L.
~ ~ 2 1 , ~ ~ 1 4 9 9 , and LRV, and came c u t with results of the proximate analysis i
a f t e r four days of geminat ion as shown on tab le 2.2 below,
TABLE , 2 .
SORGHUM MALT PROXIMATE ANALYSIS (ANICHIE 1982)
-- - -- -- - - -
Ma1 t ing l o s s (%) 25,OO 24.00 22-00 22.50 17-82
log f i l t r a t i o n time 1.2b 2 .01 1.62 1.78 1.52
Ma1 t Nitrogen (%I 1, 70 1.68 1-61 1-54 1- 74
Aisien (1982) investigated the u t i l i z a t i o n of soluble carbohydrates
during sorghum germination and seedling growth, He determined sucrose,
raff inose and fructose leve ls in the scutellvn of i n t a c t and excised
sorghum seedling during growth, H e found t h a t i n the scutellum of the
i n t a c t grain embryo, sucrose and ra f f inose l eve l s declined sharply over
the germination phase but increased a t post-germination ( i e roo t enwgence)
a s hexose sugars from the modifying endosperm passed into t he scutellum.
tie observed t h a t maltose, maltotxiose and glucose were the main products
of t he enzymic modification of t h e endospem during seedling development,
which is a post-germination event atxi therefore concluded t h a t the growing
. -.---z --! cf the embryo, with its higher inver tase a c t i v i t y showed grea te r
cdpdcity f o r sucrose metabolism than t h e scutellum.
2.3.2 Millet Malt: I
opoku et &.,(1981) geminated m i l l e t g ra ins f o r 84h and kilned a t
45Oc to obta in a m a l t product. They conducted analys is of vitamins,
phytate, oxillate, tannins, total phenols, and calcium t o determine t h e
nu t r ' i t iona l value of t h e g ra ins and the malt. hey found t h a t the., . levels
of vitamins were higher i n t h e malt than i n t h e grains. Also t h a t s l i g h t
increases i n p ro te in and tote$ phenol w e x e observed in the m a l t , while
l i p i d , phytase, and oxala te l e v e l s decreased during malting. The r e s u l t
of the proximate analys is w a s given i n a table. . '
Skovron and Lorenz (1979) determined t h e - a?ylase, protease,
ce l lu lase , and hemicullulase a c t i v i t i e s of e i g h t c u l t i v a r of proso
(~anicum miliaceum) m i l l e t s . They found t h a t a l l t h e c u l t i v a r s showed
b-my1 ase, pro tease , c e l l u l a s e and hemicellul ase a c t i v i t i e s with the
exception of one sample that sllowed no hemicellulase ac t iv i ty . The
optimum pH f o r b-amylase a c t i v i t y was found t o be approximately 5.0, and
production of maltose per in'illilitre of e x t r a c t ranged from 0.73 t o 1.93 f i a f t e r l h of incubation a t pH 5.25. Also t h e pH optimum f o r protease
6
a c t i v i t y was near 3.0 and 5.0, production of tyros ine per m i l l i l i t r e of
e x t r a c t ranged f r m 12.5 to 75.5 Yj aftez ii! of h~&i i i io i i ai pH 4.8.
Opokus 3 d., (1983) s tudied the quan t i td t ive and q u c l l i t ~ t i v e changes
i n cdbohydra tes , prote ins , and l i p i d ma te r i a l s during t h e germination of - mil le t . They found t h a t a two-stage metabolism was exhibi ted during
ycrmin~i t i o n a d t h ~ t Y t a c h content d e c r e a o d during germination which
coincided with cir~ increacja i n so lub le carbohydrate and p r t e ins . . They
f u r t h e r observed t h a t tho high l i p i d content of the g r a i n was reduced t o
Ueleia culd arts son-Varriano(198Ib) s tudied the e f f e c t of pea r l millet
dnylases on i n t a c t s t a r c h granules and heated s t a r c h suspensions, Amylases
i n crude m i l l e t e x t r a c t s showed higher amylolytic a c t i v i t y on wheat s t a r c h
than on m i l l e t s t a r c h , both in amylograph determination and s t u d i e s on
hydrolysii of raw starches. According to the r e s u l t s , t he a c t i v i t y p a t t e r n
of m i l l e t alpha amylase was similar t o t h a t of o t h e r cereal alpha amylases
' . with t h e r a t e of appearances of hydrolysis products being dependent on the
p a r t i c u l a r s t a r c h subs t ra t e s ,
Gudisevd e t ' &., ( 1981) screened twelve v a r i e t i e s of sorghum( Sotghwn - b i c o l o r ) , 14 v a r i e t i e s of pea r l millet(Pennisetwn typhoidem), 12 v a r i e t i e s
of s e t a r i a ( s e t a r i a italics), four v a r i e t i e s of ragi(E1eucine coracana),
11 v i d e t i e s o f echinocloa m i l l e t (Echinocloa colona) , 13 v a r i e t i e s of
proso (Panicium meliacem), 11 varieties of kodo ;, (Paspalum scorbiculatum),
did 11 v a r i e t i e s of miliare(Pani.ciwn mi l i a re ) f o r inh ib i to ry a c t i v i t y
aga ins t human s a l i v a r y amylase, Echinocloa, proso, kodo and miliare had
no de tec tab le a c t i v i t y . Two s t r a i n s of sorghum and one s tra ip of pear l
millet d id n o t show .&-anylase i n h i b i t o r y ac t iv i ty . ~ l l o t h e r seeds had
6
ac t iv i ty , the highest being observed i n sorghum. According t o the r e su l t s ,
the inh ib i to rs were non-dialysable and were inactivated by pepsin treatment.
Also s e t a r i a and 8orghum inh ib i to rs vere r o l a u v e i y t inenoiab i le compared
to r a g i and p e u l m i l l e t inhibitors.
Maileshi and Desikacha (1979) evaluated the malting potent ia l of high
yielding var ie t ies of ragi(E1eusine coracana). Three were found t o be of
good malting var ie t ies as they possessed good germinative energy, high
amylase ac t iv i ty , with good y ie lds of malted flour. Gemination conditions
were 24h .teeping and 72h germination a t 25-26O~.
s k o r a i n and ~ag le (1973) in evaluating the use of ba j ra o r pearl
mi l le t fo r malting purposes, compared the beta amylase ac t i v i t y of ba j ra
and barley malts. They found t h a t beta amylase ac t i v i t y of germinated
bajra increased up to 30h and decreased up t o 72h., while t h a t of barley ?
increased continuously up to 72h. They therefore concluded t h a t i f ba j r a
i s t o be used f o r m a l t production, then sho r t malting i s radvocated.
Abdul-Hassan and Varriano-Martson(1982) -s tudied the amylolysis of .
pearl m i l l e t s t a rch and its f rac t ions by pear l m i l l e t alpha amylase.
Gemination resul ted in a 120 fo ld increase i n spec i f ic ac t i v i t y of the
enzyme over t h a t of the alpha amylase f ran mature grain. Results showed
t h a t raw m i l l e t s t a rch w a s r e s i s t a n t to attack by alpha amylase. Fran
germinated mi l l e t , a lso amylase was readi ly hydrolysed by pur i f ied millet
alpha my1 ase, while sane portions of m i l l e t anylopectin were hydrolysed
slowly by alpha amylase.
t ' d et A., ( lgVl6 ) found t h a t decreasing germination temperatures .
fruu 35 t o 2 5 O ~ i n b a j r a and from 25 to 1 5 O ~ i n bar ley , =esul ted i n a '
s i g n i f i c a n t increase in t o t a l amylolytic a c t i v i t y a s w e l l as p r o t e o l y t i c
a c t i v i t y of green malts prepared fram the two cereals.. They observed
t h d t t o t a l m y l o l y t i c a c t i v i t y was mainly due to b e t a amylase i n both
m d l t k 4 , more s o i n b a j r a malt. They suggested t h a t the germination a t low
temperdture l eads t o b e t t e r y i e l d s a s w e l l a s qua l i ty of malt.
Pokhryal e t a l . , (1977) s tudied hybrids of pear l m i l l e t g r a i n s - - (Pennisetum typhoides Linn(Brum) stapt .dnd tiubb), They examined hybrids
f o r t o t a l p ro te in content and amino acid spectra. They found t h a t p ro te in
values ranged from 11.0 - 14.7X. Lysine and threonine which are l i m i t i n g
amino ac ids according t o chemical score showed range of 2 .S6 - 3.46 and
1.99 - 2.44 g / 1 6 g ~ , respectively. ,
L'dl a d., ( 1973) compared various p roper t i e s of m a 1 t from b a j r a with
t h a t of bar ley malt. They observed t h a t proximate analys is r e s u l t s of the
two mal ts showed l i t t i e d i f fe rence i n t h e i r canposition. Both b a j r a and '
8
bar ley malts had comparable amylolytic a s w e l l as p r o t e o l y t i c a c t i v i t i e s .
According t o t h e r e s u l t , there w e r e very few d i f fe rences i n enzymatic
physical p roper t i e s of a good malt though it developed a b i t t e r t a s t e
a f t e r a s h o r t t i m e .
2.4 Glucose Syrups:
Contdolled hydrolysis of s t a r c h with ac id , enzymes, o r combinations
of these y i e l d s severa l s t a r c h hydrolysates which include: glucose syrup,
rnaltodextrinu, high maltose syrup and high fructose corn syrups and the i r
sol ids respectively . s t a c h from corn, sorghum, mi l l e t , potato, tapioca and other p lan t
sources are used i n producing those hydrolysates.
2.4.1 ~ e f initions:
Gl~.~cose syrup(Corn syrup). Is the pur i f ied concentrated aqueous
solution of nu t r i t i ve saccharides of DE 20 o r more'obtained by hydrolysis
of edible starch.
Maltodextrin: Is a mixture of purified nu t r i t i ve saccharides obtained
by hydrolysis of s tarch having a DE of l e s s than 20. r /
~ i g h Maltose syrup: as t h e name implies has a higher than normal
maltose content when compared t o other enzymatically produced sykps.
High fructose corn S~~UE(H.F.C,S): Is corn syrup
additional s tep of enzymic conversion of a portion of
fructose .
produced with the
P.glucose t o D-
Dextrose Equivalent(DE): Is an indication of t o t a l reducing sugars
calculated as D-glucose on a dry-weight basis. The DE value is inversely
re la ted t o the degree of polymerisation,(DP).
~non,(1979) c l a s s i f i ed corn sywps according to method o t conversion;
acid conversion, acid-enzyme conversions and enzyme-enzyme conversion.
2.5 ~ e t h o d s of production of ~ ~ U C O S ~ Syrups:
2.5-1 Acid Conversion: Acid conversion process i s carr ied out i n d: pressure
vessel termed a I c ~ n v e r t e r * ~ # t a r c h is mixed with water t o form a suspension
o r s lurry , containing 3040% dry starch. The required amount of d i l u t e acid,
usually about 0.12%, based on the weight of s tarch, is added and the
tt.rnper*tu~.e rdised by l i v e stem to 140-1600~. The heating continues f o r
12-20 minutes, The cooked o r ge la t in ized s t a r c h i s converted f i r s t t o the
higher polysdccharides. As t h e process proceeds, o the r sugars are produced;
~ c c o r d i n g B e M i l l ~ ( 1 9 6 7 1 , tlle #- D -(1 4 4) l inkages undergo
hydrolysis more e a s i l y than do the 4 - U - (1 3 6 ) linkages. Furthermore,
l inkages nearer the non-reducing end of t h e s t a r c h polymer are hydrolysed
more rapid ly than bonds located in the polymer i n t e r i o r , r e s u l t i n g therefore
i n a random hydrolysis.
H a r ~ e y ~ ( 1 9 8 3 ) observed t h a t acid hydrolysis of g ra in products is
considered t o modify f a t t y and p ro te in cons t i tuen t s , r e s u l t i n g i n off- ,
flavoured materials . According t o . h i m , acid hydrolysis con t r ibu tes to
the }\reduction of miscellaneous sugar products t h a t in t u r n can con t r ibu te
t o va r i ab le f lavour and fennentabi l i ty .
w i t t and Blythe (1976) inves t iga ted the fermentabi l i ty of m a l t worts
s u p & n e n t e d with 35% acid - thinned and 35% enzyna thinned corn syrup
s o l i d s , respectively. Under p i l o t brewing condit ions, t h e worts containing
the acid-thinned syrup showed a slower fermentation r a t e ,
2.5.2 Acid-enzyme conversion:
~cid-enzyme converted corn syrups are produced by m e a n s of a two-
s t age hydrolysis. The f i r s t s t a g e ( l ique fac t ion) is accomplished wi th
ac id , a s described above, and i ts e x t e n t i s determined by the des i red DE
value and carbohydrate cornposition of tine f in i shed syrup. The second
s t age (sacchar i f ic i l t ion) i s c a r r i e d o u t by means of s t a r c h hydrolysing
enzymes, usual ly O(-my l a s e , P-amylase and glucoamylase depending on
t h e required type of corn syrups and its composition. he ac t ion p a t t e r n s
22.
of enzymes used i n canmercial corn aymp manufacture have been described
by Mac All ioter (1979).
he scid-enzyme process according to Ough (1962) tends t o eliminate
carbohydrates degradation products and b-linked reversion products such
as gentiobiose. Hurst and Turner(1964) have described a patented process
for production of highly fermentable, non -~~~~ t&! , I i z i ; ; g corn syrdps with
high leve ls of glucose and maltose contents, w1th.a mixture of gluco-
cirnyldse and fungal d-amylasg . Different r a t i o s of P.glucose to maltose
can be obtained by a l t e r i ng the proportdo& of th. two enzymes, then
concentrations and conversion time.
Alternatively, when high maltose syrups are desired, barley &amylase
i s added and the hydrolysis proceeded u n t i l the required leve l of maltose
i s produced. Maeda and Tsao( 1979) reported the use of microbial 8-amylase *
i n Japan i r rdus t r i d ly ra ther than the p lan t enzyme. Mltsushashi e t al.,
(1974) developed a patent which employs simultaneously, maltorgenic enyme
and pullulanase ( o(-l,6-glucosidasei irr tie prepuration of high maltose
syrups from acid l i qu i f i ed starch.
2.5.3 Enzyme-enzyme conversionr
High conversion hydrolysates are prepared almost exclusively by the
use of eniymes. Mac ~ l l i s t e r ( 1 9 7 9 ) observed t h a t acid-catalyzed
hydrolysis of s ta rch is not capable of giving pract ical hydrolysates with
more than about 90% Pglucose, owing t o acid catalyzed reversion and
dehydration react ions resu l t ing in a s izeable l o s s of D-glucose.
The objective of t h e l i q u e f a ~ t i o n process is to convert a concentrabd
auepenoion of s tarch granules i n t o a solut ion of soluble dextr ins of low
viscosi ty f o r convenient handling in ordinary equipment and f o r easy
converoion to glucose by gluco-amylase. Mac Allister(1979) described the
process. According t o his process, a suspension of s ta rch in water i s
treated with calcium hydroxide (slaked lime) to pH 6-7,q optimal f o r 0( -amylase.
Lime is used, because it serves a s a source of calcium ion needed by most
O( -amylase as act ivator and s tab i l i ze r . A solut ion of bac te r ia l M-amylase
is then added, and the suspension i s pumped i n t o a steam jet where the
temperature is raised inf&antaneoualy to 80-115~~. The s ta rch is immediately
gela t inized a d i n the presence of the amylase, is depolymerised rapidly to
- ilzld ;ass. I r The sacchar i f icat ion process t h a t follows ensures the conversion of I
I I
s ta rch t o D-glucose i n yie lds as high a s possible using glucoamylase. Once
the l iquefaction s tage has'been completed, the resu l t ing solution, containing
a mixture of maltose-oligosaccharides, is transformed to a high conwersion
syrup by holding it f o r 36dOh in a stored tank a t appr6ximately SSOC and
pH 4.3 w i t h glucoamylase.
The amylt.r.se and amylopectin portions of s tarch are converted by
4-anyldse during l iquefaction to a col lect ion of l i n e a r and branched
dextrins. The l i nea r dextr ins are rapidly and almost . to ta l ly converted
to D-glucose by glucoamylase. The branched dextr ins are much less
susceptible t o hydrolysis. Abdul lahe t &.,(1963) observed t h a t t h i s was
due t o the lower r a t e a t which glucoamylase cleaves the o ( - ( l j 6 ) D - glucosidic linkage, as campared to cleavage of theO(-~-(l+41 linkdge.
Tkirpk &.,(1976), using a s ing le enzyme system, produced glucose
syrup md dextrosd fran maize g r i t s . H e found ou t t h a t glucose syrup
production in. a s ing le enzyme e y s w with bac te r ia l 4-amylase a t pH 6.0
and 85 '~ eliminate many disadvantages of tkie d o a l e enzyme system eg.
microbial infection, pH adjustment during the reaction, high enzyme costs ,
proteolysio. The syrup produced has a DE value of 38%. 0.3% ash and 0.03%
nitrogen.
Yoshizawaet &.,(1980) in their s tud ies found t h a t s tarch heated a t
1 2 0 ~ ~ f o r 20 minutes was e a s i l y digested by o(-mylase a t p~ 6.0, while
raw s t a r ch was only p a r t i a l l y digested, Also they discovered that
d i & s t i b i l i t y of l iquef ied corn s ta rch was higher than t h a t of rice.
H i l r s t s &.,(1971) produced s ta rch conversion syrups having a minimum
fermentable ex t rac t s (F.E) value of 7%, a minimum dextrose e q u i v a l e n t ( ~ ~ 1
value of 47% and a max.dextrose content of 47% by sacchar i f icat ion of a
s tarch hydrolysate with an enzyme composition comprising a dias tase ,
glucoamylase and amylo -1,6- glucosidase.
Mandels et &,,(1975) reviewed the enzymic conversion of waste - cel lulose material t o glucose syrups f o r use in the food industry. They
discussed the production of a canplete ce l lu lase complex from Trichodenna
Viride Qu 9414 and pretreatment of substra tes by b a l l mill ing t o produce - maximum saccharification. Ac.cording to the review, sane prunising substra tes
f o r conversion a re listed: milled bagasse gave 42% sacchar i f icat ion in 4h,
milled m i l k cartons 81% saccharification i n 24h a t 50% pH 4.8.
Figure 2.1 shows a general manufacturing.procedure f o r glucose syrups.
Process Ytee
& /znzylne sacchar i f ica t ionf
I
Carbon r e f i n i n 47
Fig. 1. A general manufacturing
2.6 Refininq:
Modern systems are continuous conver ters
F a t and protinaceous impur i t ies p rec ip i t a t e .
Removes major por t ion of insoluble impuri t ies .
x
~emain ing insoluble impur i t ies removed
s o l i d s increased t o 55%
For acid-enzyme hydrolysed syrups enzyme treatment applied a t this stage. .
Powdered o r ac t iva ted granular carbon used.
ion-exchange treatment is opt ional used when ash free, very colour s t a b l e syrup are desired.
Sol ids increases t o 82%
procedure f o r corn syrups.
I n the r e f in ing processes, high qua l i ty corn syrups and s o l i d s o r
c r y s t a l l i n e dextrose demands the removal of:
( a! coloured compounds (b) meta l l i c ions.
( C) Hydroxymethyl fu r fura l
(dl nitrogen containing canpounds introduced with the o r ig ina l s ta rch
or with t h e enzyme preparations used i n the process
( a ) .Orgwic acids which can impart undesirable flavours o r colours to
the various products and
( f : sol-like pa r t i c l e s of unhydrolysed or degraded starch,
Carbon treatment removes most of t he soluble proteinaceous material&
present and subs tan t ia l ly a l l t h e 5-(hydroxy-methyl),- 2 - furaldehyde *
formed during the acid treatment, Also, many. commercidl-ly activated carbon
are ef fec t ive i n removal of heavy metals such as i ron and copper,. t h a t
can a c t a s ca t a ly s t s f o r developing colour, - Most new ' i n s t a l l a t i on observed
Conlee(l971) use counter current applicatiok of iactlvated granular arba an
in cy l indr ica l column because it can be conveniently re-activated,
yielding more favourable economics,
A typical ion-exchange deionization system cons i s t s of s i x fixed bed
columns (three pa i r s of cat ion and anion axcircuiyrt i.tz3in 03 aervice r'or
regeneration), The cat ion exchange r e s i n s used are strong acid exchangers
(sulfonated resins i n the hydrogen fonn) and the anion exchangers uaually
are weak base res ins (tertiary m i n e i n the free base form), The anion
exchange r e s in s removes acids generated by reaction of the , s a l t s i n the
syrup l iquor with the cation-exchange resins.
Bezhal - c t &, (1981) discussed an experimental equipnent used f o r
e l ec t ro - f i l t r a t i on of glucose syrups which achieves separation of various i
foreign substeinces eg. micro-ozganims,pmteinls and other macromolecular
cornpoundrr, fu r the r colouring mat ters , c o l l o i d s etc. The syrup pass
through a l aye r of granulated mater ia l , under the ac t ion of d i r e c t
elecuical current . The undesirable p a r t i c l e s are coagulated and trapped
on the granules.
~ a l d a s s a r i ( 19 71 ) described a process whereby concentrated solLtLons
of sugar are t r ea ted with resins to remove impur i t ies such a s amino acids,
mineral ac ids and salts, organic bases and ac ids etc. by passage through
e s e r i e s of four ion-exchange r e s i n f i l t e r s . The r e s i n s are r edmera ted
with 10-15% H2S04 o r 44% NaOH. I n c o n t r a s t with o the r processes, th is
only needs 2 4 opera t ives , cuts i n d u s t r i a l costs by 80% and gives an
improved pr@uc t.
Hersiczky (1972) constructed a f i l t r a t i o n u n i t f o r continous operat ion,
maximum capaci ty 10,0001/h and s u i t a b l e f o r all types of r e a c t o r and
hydrolysis. With s i n g l e passage operat ion, t h i s p u r i f i c a t i o n u n i t removed
94% of suspended matter f r a n upper, middle and lower regions of the
hydrolysate and increased output of the f i l t e r s t a t i o n by 50%.
2.7 P roper t i e s and Functional u s e s of Glucose syrups. '1
There are severa l types of corn syrups each of which has i t s own sa t
of propert ies . These p roper t i e s are the sun of the c h a r a c t e r i s t i c s of the
components which make up each syrup. These include: Dextrose equivalent
(DE), carbohydrate canposi t ion, a c i d i t y and pH, sulphur dioxide, fermentable
e x t r a c t , Baume
Humectancy and
and s p e c i f i c g rav i ty , Ash, Prote in , colour, v i scos i ty ,
hygroscopicity 'etc.
~ u d v i g et &.,(1975), studied the fac tors responsible f o r the browning
of glucose syrups during storage. They suggested t h a t i n i t i a l s ta rch
materials must not contain 0,6 - Om% protein, with only small mounter
of o i l and fibres. Also after f i l t r a t i o n , a pre-concentration t o 28-32
t3dume' degrees is necessary, followed by a second f i l t r a t i o n . Further more,
the optimal temperature f o r c rys ta l l i za t ion i s important.
Keaslay ( 1978) studied the ca t a ly t i c hydrogenation of glucose syrups
as a means of controll ing hygroscopicity and suscep t ib i l i ty of browning
a d fermentation reactions without changing properties such a s viscosi ty 9
osmotic pressure or sweetness. According to the resu l t s , hydrogenation
s ign i f ican t ly decreased (P 0.05) moisture uptake of syrups a t 100% RHO
Browning decreased with DE before hydrogenation of syrups, and hydrogenation' .
(eg reduction i n DE from 100-76) of a syrup reduced colour development when . the syrup was heated with amino acids. Furthermore, hydrogenation of
syrups decreased % fermentable sugars.
Hoover(1963) has i l l u s t r a t e d the functional properties
as they r e l a t e t o tha type of conversion. This is shown i n
he arrows of increasing s i z e point t o the di rec t ion of the
of ,Corn Syrups
f igure 2.2.
most desi rable
corn syrup t o use f o r a par t i cu la r property, a l l o ther fac tors being the
same. I n select ing the most su i t ab l e corn syrup, the greater the number
of arrows t h a t go in the desired direct ion, the b e t t e r is t h a t corn syrup
for the intended application. For example, i n choosing a corn syrup f o r f I
use i n i c e cream production, the lower coriversion syrups are preferred.
These syrups.increaae the bodying and cohesive e f fec t s , viscosity, and
prevent excessive growth of ice c rys t a l s during freezing.
29.
~oover (1964) has a l s o prepared a c h & l i s t of p roper t i e s and
functional uses of corn syrups i n a wide va r i e ty of foods. Table 3 shows
these data. This table may b e used advantageously by f i r s t determining
the property o r p roper t i e s of a food which may be improved w i t h the use
o f corn syrup and then s e l e c t i n g the most s u i t a b l e syrup. For example, in
bakery products higher conversion corn syrups are prefer red where browning,
f ermen t a b i l i t y , sweetness, and f lavour enhancement are desired. '
2.8 Malt based Syrups.
2.8.1 Mashing Method.
~ a l t is converted t o wort by b a s i c a l l y two methods of mashing; the
decoction mashing method and the single-temperature mashing system c a l l e d
infusion method(Briggs e t a1 1981). I n infus ion muhing process, no p a r t ' '
of the mash i s boi led and returned to t h e main mash, r a t h e r the whole mash
i s gradually heated f r a n mashing-in t o rnashing-off. When the mashing-in
temperature ( 35-SOOC is progressively r a i s e d to mashing-of f temperature
( 75-80°C through the sacchar i f i ca t ion temperature range of 65-70°c, thet
mashing process is c a l l e d upward infus ion, while the downward infus ion
process resrllts when the f i n a l temperature of t h e marsh(65-70°C) is lower
than the i n i t i a l temperature of t h e mash(75-80°c). ~ n f u s i o n mashing is
s u i t a b l e f o r ttie highly modified m a l t . (r"
I n decoctl-on mashing, ' a por t ion of the mash is boi led and returned
to the rest of the mash in t he mash tun. Tradi t ional decoction mashing
employs malt which is less modified than t h a t used i n infus ion mashing
and i s only l i g h t l y k i lned(8r iggs -- e t a1 1981). There are three d i f f e r e n t
kinds of decoction methods. '
IYPF OF CORN SYRUP' PROPFRIY OR IIItJC1IC)NAI L J S F
(ALPllAnEllCAILY) - LOW.CONV. REG.-CONV. IN1ER.-CONV. IiIOII-CONV.
BODYING AGEN.1
BROWNING REACTION
CONFSIVENESS
FERMENTABII.ITY
FLAVOR ENIIAFICEMENT
FlAVOR TRANSFER MEDIUM
FOAM STARILIZFR
)tVMECTANCY
blYGROSCOrlCITY
NUTRlllVE SOLIDS
OSMOTIC TRFSSURE
PRFVENTION 01: COARSE I C E CRYSIALS DURING FRtEZING
5HEEN PRODUCER
Checklist of propert ies
and funclional uses o f corn syrups
in specific food producls
- - -. - -. . - -- -. - - - - . - - - -. -- -. .- - Baby loods - - - - -- -- -- - -- - -- - . - - Bakery producls .. - ....... - -. -. .............. - .. - - .- - ..... Beverages, brewed - - ..... - . ..... - ......-... - .. - . Bcveragcs, carbonated - lion alcoliulic - .- . - -- -- - - - -- - - - - - -. - Breakfast loods --------.--- Catsup, chili sauce, ton~dlo raucr --- -- - .- ... Cereals, prepared - 0--- ---- Cheese spreads and Irluds - - Chewing gunr -- - ------ Chocolate p~oducls -. -- - ... .......
Cilrus juices, dried -..-, -, .. - ............ - ... ---- . '
~ondcnsed milk
Cunlrctionr - - --- Cordials and liqueu~s . - ..... .............................. Eggs, lruzer~ or dried
.---- Extracts and llavors
-----------. -- Frostings and icings - ------ - ----- - Fwi l bullers
Fruit juicer and fruil jirice drinks
(i) The one mash method'
( i l l The double mash method
(iii) The th ree mash methud.
K a r e l (1967) described and i l l u s t r a t e d the production, on a continuous
baaie a 'complete mash' containing almost a l l the so lub le mal t substances
and moat of t h e enzymes. I n h i s study, f i n e l y ground malt was mashed a t 5
65O~(1 1 5) by s t i r r i n g f o r 30 seconds. The mash was then subjected t o a
pressure shock of 294 p.s.i and immediately converted by passing through a .
pressure r e l i e f valve i n t o a s a c c h a r i f i e r , where the temperature was increased
by IOC per minute from '65O t o 70-71°c. This temperature was maintained
u n t i l the iodine test gave a yellow colour. The t o t a l conversion period
w a s 10-20 minutes,
.Barre t and G r i f f i t h s (1966) s tud ied s h e e f f e c t s of malt k i l n i n g on
wort proper t ies , The r e s u l t s s h o w that as colour increased and moisture
decreased the e x t r a c t value of the malts remained e s s e n t i a l l y cons tant I
while t h e d i a s t a t i c power decreased subs tan t i a l ly . ~ h l s i n tu rn was
pa ra l l e l ed by a reduction of fermentabi l i ty in the derived worts. Measurement
of the individual sugars p resen t i n the worts showed t h a t the decrease i n
fermentabi l i ty was associated with a diminution in the percentage of maltose
and an increase 10 the dex t r in content , while the values f o r o the r sugars
were r e l a t i v e l y unaffected.
Desrousseaux and Montreuil(l966) s t u d i e s on commercial mashing showed
tha t , /+amylase ac t ion occured optimally a t about 6 3 O ~ , it slowed down as
the temperature reached 70°c, and w a s i n h i b i t e d a t higher temperatures. The -
optimum f o r 1 hit dextr inase a c t i v i t y w a s 50-63O~, higher t e m p e r a w e s
destroying the enzyme. Alpha-amylase action began above 63Oc, a t ta ined a
maximum around 72Oc and diminished a t higher temperature.
Narzisa and L i tzenburger (1977) , inves'tigated the mashing conditions
and gum contents and thus concluded t h a t it was possible to regulate gum
contents t o some extent by var ie t lon of mashing method but the s t a t e of
modlficetion of the malt plays a much more decisive pa r t than mashing
conditions. Also they added t h a t the a l te ra t ion of the pH of mashing t o
5.5 effected advantageous degradation of ti-glucan only a t high mashing
temperatures.
2.8.2 Preparation of m a l t syrups.
The three mash mmthod involves usshing a i n a t about 35-40°c. After I I
sometime about one th i rd of the mash, the f i r s t mash, is taken l n t o a k e t t l e I and boiled and brought back to the mash tun where the temperature of t he
1 i i
whole mash is ra ised t o 5 0 - 5 5 ~ ~ , t h i s i s kept f o r a period of t h e , about I I
15-30 minutes. Boiling destroys the enzyme i n the boiled portion as i
w e l l as ge la t in izes the starch. Diasta t ic action is thus f a c i l i t a t e d by 1
t h i s process. Then a second mash (again one th i rd portion of the e n t i r e
mash) is boiled and returned to the main mash. T h i s brings the temperature j
t o 6 0 - 6 5 ~ ~ , t he saccharification temperature. It is allowed a t t h i s
temperature fo r 30-60 minutes. Lastly a th i rd is t reated i n the same manner,
and i t r a i s e s tho temperature of the whole mash t o 70-75O~, the mashing-off
3 temperature. This is a l so kept f o r 30-60 minutes.
The resul t ing wort is c l a r i f i e d , theapH adjusted t o 4-5 and appropriate
amount of glycoamylases added. The saccharification is allowed to c o n t h u e
f o r several hours (12-72h) depending on the extent of conversion desired
r~ld th i s i s determined by i t s dextrose equivalent value(DE).
he melt syrup which contains a mixture of saccharides is neutralised
and concentrated by evaporation in multi-effect evaporaba or for
laboratory works, on a boil ing water-bath to about 80% slolids so aa t o I
inhibit microbial spoilage.
CHAPTER 3
MATERIAIS AND METHODS
3.1 MATERIALS
3.1,1 Mi l l e t g r d n s (Pennisetun~ ~ y p h o i d e s ) and sorghum grains(s0rghwn
h lcol o r ) were purchased f ran Orba market , NsulEka.
3.1.2 ~myloglucosidase(AMG), from ~ s p e r g i l l u s n ige r was purchased from
Nove ~ n d u s t t i a l Enzymes Division, Novo Alle DK - 2880 Bagsvaerd, Denmark. I I I
3.2.3 Other Chemicals and reagents were of the pures t ana ly t i ca l grades.
3.2 METHODS - 3 9 2 Determination of malt ing ~ h ~ w a c t e r i s t i c s of t h e c e r e a l qra lns ;
I
Sorqhum and m i l l e b ,
-j 2 .I Determination of moisture content:
The moisture contents of the g r a i n s and malts w e r e determined I i I
&cording to the I n s t i t u t e of Brewery, I,O.B.(1977) method of analys is , i !
dS ~ O ~ ~ O W S :
About 209 sample of g r a i n s were f i n e l y ground in a Thanas Wiley M i l l
Model ED-5, and thoroughly mixed. 5g of the ground sample was placed
in a moisture d i s h which was closed and weighed immediately to 0.001g. i The cover of t h e d i s h w a s removed and placed in a pre-heated oven f o r 1 .
I
exact ly 3h a t I O S ~ C , The l i d was replaced and removed 'from the oven,
then allowed t o cool i n a d e s i c a t o r f o r a t l e a s t 20 minutes t o ,room
temperature. The d i s h was then re-weighed t o 0.001g.
Calculation: %
The moisture percentage(M) of the sample
Wkre W1 - weight of sample before drying
w2 - weight of sample a f t e r drying
3.2r2'. ~ e t e r m i n a t i o n of Percentage Foreign Seeds and broken kernels .
The percentage of fore ign seeds and broken ke rne l s of the ce rea l
g ra ins were determined according t o t h e method of Association of O f f i c i a l
Analytical Chemists, A.OoA.Cm(1980) a s follows:
509 of each of t h e g ra ins was weighed and the fo re ign seeds and broken
kernels were counted out. he g r a i n s were reweighed and the d i f fe rence i n
weight recorded a s a percentage of the o r i g i n a l weight.
3 . 2 . 3 ~ e t e r m i n a t i o n of thousand Corn weight:
A thousand corn weight of t h e g ra in samples were determined according to
the method of l.O.B(l977) a s follows:
20g samples were weighed o u t a f t e r removal of fore ign matter and half
corns. The number of corns i n each sample counted and moisture content
determined. 4;
Calculation:
-The weight of 1000 corns of d r y corns i n gram(g)
Where W - t o t a l weight of c e r e a l g r a i n s taken
DM a D r y matter percentage of t h e g ra ins
N = Tota l number of corns counted.
3.204 a~ The objec t ive of t h i s test was to measure the. p
I
iercen tage of g ra ins .
which cm be expected to germinate f u l l y i f the sample is malted normally s
d t the time of t h i s test. The I,O,Ei.(1977) method of analys is was adopted
as follows:
100 corns f r a n the samples w e r e placed i n a p e t r i d i s h l i n e d with two
f i l t e r pcrpers i n t h e bottom to which 4 m l of water had been added, The
p e t r i d i s h was covered and the g r a i n s allowed t o g e m i n a t e i n a cupboard,
The c h i t t e d corns w e r e removed a t 24, 48, and 72h from the beginning of
steeping,
Percentage of corns chii2ted a s the g e q l n a t i v e energy were ca lcu la ted
thus:
Germinative energy = GE(%)
3.2 , 5 Determination of germinative Capacf t .
The ob jec t ive of tNs test w a s t o measure the percentage of l i v i n g
corns i n the sample. The germinative cap'acity of the g r a i n s was determined
using the hydrogen peroxide method a s described by H o u g h s , &,,(1981)
a s follows:
200 corns were steeped i n 2OOml of 0.75% hydrogen p e r o x i d e ( ~ ~ 0 ~ f o r
48h a t room temperature, The s t e e p l i q u o r w a s replaced with f r e s h hydrogen
peroxide ' so lu t ion and was l e f t f o r f u r t h e r 24h. Gernlinat im capaci ty was
then ca lcu la ted as f o l l w s :
Where n I number of corns t h a t d i d no t g e h i n a t e ,
3 . 3 ~kterminsCiotr of Optinrun Malting Conditions of the Cereal Grains:
? ? .I . . . A i~iois t u r e Content as a function of s teep time:
Eight pe t r id i shes l ined w i t h filter papers a t t h e i r boktoms were ,
provided and f i l l e d with equal volumes of tap water. 20g of the g ra ins were
cledned m d steeped u t roOm temperature i n each of the pe t r id i shes f o r
v x i o n s t i m e s , 10-80h, with e i g h t hourly change of s t eep l iquor . .
A t the end of edch s t eep period, the g ra ins were drained, surface
wdter b lo t t ed with f i l t e r paper, then t h e moisture content determined, as
i n sec t ion 3 - 2 ' 1
3 . 3 . 2 ~ e t e r m i n a t i o n of Opbhum Steep t i m e :
ha gra ins (209) were steeped a t various times, 10-80h as described
d o v e . Each of the e i g h t sets w a s allowed t o gemind ie f o r 4 days i n a
deck cupboard and then k i lned f o r 48h a t 55Oc, after which the mal t ' s
d i a s t a t i c power was determined as i n sec t ion 3.2 -4
3 . 3 . 3 Determination of opthum germination period:
The g ra ins (20g) were steeped f o r 50h and germinated f o r various
periods, 1-7 days i n a dark cupboard, l a t e r ki lned f o r 48h a t 5 5 ' ~ and
the ma1 tm s d i a s t a t i c power determined.
3.3 .4 Effec t s of k i ln ing a t 4 5 ' ~ and varying periods of time on moisture - content of the m a l t : %
Samples of malted g r a i n s a t optimum malting conditions(50h steeping,
and 5 days germination) were Kilned a t various periods(l2h, 24h, 36h, 48h,
60h) a t 45'~. and moisture content determined.
3.3.5 Determination of Maltinq losses a s a function of germination periodr
The g ra ins (209) were steeped f o r 50h and germinated f o r yarious
periods, 1-7 days, then tho r e s u l t i n g malting losses per n t h day o f t -
germination determined as i n sec t ion 3 -4 -4 .
Production of swghwn, Millet Malts:
I k g of each of t h e g ra ins was cleaned and steeped i n ordinary t a p
water f o r 50 hours a t room temperature with 8 hourly change of s t eep
l iquor t o both minimize t h e growth of microbes and provision of more
oxygen t o t h e embryo of the grains. A t t he end of t h i s s teeping period,
t h e g r a i n s were drained and spread on a cleaned f l o o r of a dark cupboard.
Wdter W ~ S sprinkled on the corns when they were v i s i b l y d r i ed , t o ensure
adequate moisture supply throughout the 5 day genningtion period.
Germin.ation was terminated by k i ln ing a t 4 5 O ~ f o r 48h in a hot-air
oven. A t t he exp i ra t ion of t h i s time, the malt became f r i a b l e and the
. , k i ln ing was stopped. .. .
30 4 - Evaluation o f Ma1 t@ s q u a l i t y cha rac te r i s t i c s :
~ e t e r m i n a t i o n of Cqld Water Extract(CwE) 3.4-1
cold water e x t r a c t s of t h e m a l t s were determined according t o t h e
I.O.B.(1977) methods of analys is as follows:
10y ground mal t was d iges ted with 200ml of d i s t i l l e d water containing
121111 of 0 . l ~ ammonia f o r 3h a t 20°c, s t i r r i n g d t ha l f Hourly in te rva l s .
The r e s u l t i n g so lu t ion was f i l t e r e d and the s p e c i f i c g r a v i t y o f . t h e
0 f i l t r a t e measured a t 20 CO
water e x t r a c t (CWE) %
x 20
Cdcu la t ion ;
The Cold
where G r tha excess degrees of g rav i ty of the f i l t r a t e taking water a t
?oOc ds 1000.
i e G = 1000(SG - 1). 3 . 4 . 2 Determindtion of d i a s t a t i c Power (Using F e h l h q ' s T i t r a t i o n ) .
Dias ta t i c Power determination w a s c a r r i e d in accordance with t h e
~ n s t i t u t e of Brewery, I.O.B. (1977) methods of analys is a s follows:
iul u u f i l t e r e d cold water extract of a m a l t in fus ion was prepared and
allowed t o ' s e t t l e . 3ml a l i q u o t o r s u i t a b l e volume of t h e supernatant
l i q u i d was p ipe t t ed into 3 100ml of 2% buffered s t a r c h so lu t ion attemperated
d t 20°c, and contained in 2 0 h l f lask. The f l a s k was shaken and maintained
d t t h i s temperature f o r e m c t l y 1 hour from when the al.iquot was added.
30ml of 0 . l N NaOH so lu t ion was added .to s top the r eac t ion , and made
up t o 2001111 a t 20°c wi th d i s t i l l e d w a t e r . 5ml of mixed Fehlings so lu t ion
was p ipet ted I n t o a 1501111 narrow-necked bo i l ing f lask . The ,digested
s t a r c h so lu t ion was added from a b u r e t t e t o t h e cold Fehlings t o within
l r n l of the f i n a l end point. T@ f l a s k contents was mixed and boi led with
moderate e b u l l i t i o n f o r 2 minutes. The bo i l ing was continued and wi th in
1 minute, 3 drops ,of methylene b lue ind ica to r was added and the t i t r a t i o n
completed.
The end po in t was indica ted by decolor iza t ion ' of tho hethylene b lue
and the r eac t ion l iqu id j u s t becoming' red.
C d c u l atlon:
Dias t a t i c power( DP) expressed i n degree ~ in tne r (O~)
Where X = no of m l of malt e x t r a c t
y I no of m l of converted s t a r c h to reduce 5ml o f Fehlingee.
S = t i t r e f o r s t a r c h blank.
Determination of t i t re f o r s t a r c h blank:
The undiluted 2% s t a r c h so lu t ion was t i t r a t e d aga ins t a mixture of
l m l of mixed Fehlinges so lu t ion and 2ml of F e N i n g e s so lu t ion B, using
t h e technique described under method, with methylene b lue indica tor .
(The blank may be neglected i f i t i s less than 3% of t h e measured
d i a s t a t i c value of the m a l t ) .
3-4.3 ~ e t e r m i n a t i o n of Hot Water Extrac t (Hw~)r
The hot water Extract of t h e mal t w a s determined by the procedure
described i n tho method of I n s t i t u t e o r Brewery I.O.B(l977) as follows:
50g of ground m a l t was mixed with 360ml of d i s t i l l e d water previously
0 heated t o about 68 C s o as t o ensure an i n i t i a l mash mix temperature of
6 5 O ~ with c o n t i n o u s ' s t i r r i n g f o r 10 minutes. The mixture was l e f t a t
6s0c ' f o r 1 hour. The mixture was then quickly cooled t o 20°c(with ice
chips) and t h e volume m d e up t o 515ml with d i s t i l l e d water, The mixture
was f i l t e r e d and t h e s p e c i f i c g r a v i t y of 'the f i l t r a t e was determined a t
20°c with s p e c i f i c g rav i ty k o t t l e within one hour of c o l l e c t i n g t h e sample.
Calculation of Hot Wabr Extract.
~ h t i ~ x t r a c t ( E ) as-is' expressed as l i t r e degrees/kg I G x 10.13.
0 Where (i - excess degrees of gravi ty of the f i l t r a t e taking water a t 20 C
3 .4 -4 ~e te rmina t ion of Malting Loss(%):
The percentage malting l o s s of the malted samples was determined
according to the method described by ~ove l l i e (1962) q$ follows:
A thousand kernel weight of the or ig ina l (unmal.kd) grain was
determined on a dry weight bas i s before malting. After malting,. the
thousand kernel weight of the r 1 1 ~ 1 i ; e c i sanple was a lso determined after
removal of the roots and shoots by hand-threshing and moisture by heating
( d r y weight basis) .
Calculations:
Malting l o s s (%) = 100(Co - Cn) co
where, Co - 1000-kernel weight of the m a l t e d grain.
cn P 1000 - kernel w t , of the m a l t on the nth day of germination.
. .5 s tudies on Malt's amylase:
3.5 ~ x t r a c t i o n of malt amylase: ,
Malt anyrase w a s extracted according t o the mthod of Shanbe 'et. - 2..
(1988) a s follows;
The malted grains (5.0g) (under optimum conditions) were ground
separately i n a morter, and quant i ta t ively transfered i n t o 100ml standard
volumetric f l ask by washhg with d i s t i l l e d water, then made up t o 100ml.
~t was incubated a t 3 7 ' ~ f o r 3h i n 250ml conica l f l a s k and 2.01111 samples
withdrdwn, centr ifuged (8000g, 0.5h) and the supernatant s tored i n a
r e f r i g e r &or.
3.5.2 Preparat ion of 1;Yo buffered s t a r c h substrate:
59 s t a r c h (dry b a s i s ) were made i n t o a pas te with a l i t t l e cold
w a t e r and then poured i n t o 400ml of bo i l ing water, The mixture w a s boiled
f o r 2 minutes and then cooled. Adequate quantity of each of t h e buffer
so lu t ions prepared ealier $see appendix) w a s added and each of the mixtures
was made up t o 500m1 r e s u l t i n g t o 1% buffered s t a r c h s u b s t r a t e so lu t ion of
pH 4, 5 , 6 , 7 and 8 respectively.
3.5 - 3 erepclration of m a 1 tom cal . ibrat ion curve:
A series of maltose so lu t ions were prepared, so t h a t 2ml conta in
0.4 - 2,Omg anhydrous maltose as follows:
I n t o each of the t e n test tubes were added 0.4 - 2.0ml of stock
standard maltose so lu t ion containing 2mg/2ml respect ive ly . The so lu t ions
were respec t ive ly made up to 2ml each by addi t ion of appropriate amount of
d i s t i l l e d water. 1 m l of t h e 1% s t a r c h so lu t ion and 2ml of DNS reagent
were added.
The test- tubes were t r ans fe r red t o a rack i n a bo i l ing water ba th
and heated f o r fi;e minutes and then cooled t o room temperature a f t e r
which t h s content of each tube w a s d i l u t e d t3 2 0 m l with d i s t i l l e d water.
., s u i t a b l e amount of each sample was poured i n t o a 'color imeter cuve.tte f o r
o p t i c a l dens i ty determindtion a t 505 n'!n a g h a s t a reference blank which
.-contain only 2 m l water, Iml s t a r c h and 2ml DNS reagent.
'i'
3 5 .A ~ e t e r m i n a t i o n of optimum p~ f o r amylase a c t i v i t s
2ml of the d i l u t e d amylase e x t r a c t (2ml e x t r a c t i n 2001111 d i s t i l l e d
water) was added to test tubes i n a rack-containing lml each of the 1%
buffered s t a r c h s u b s t r a t e s o l u t i o n a t the pH 4, 5 , 6 , 7, 8 previously
prepared. The tubes were shaken f o r 5 minutes to mix it properly and
incubated i n a thermosta t ica l ly con t ro l l ed water ba th a t 37Oc f o r 10 minutes.
The d i a s t d t i c r eac t ion was stopped by the addi t ion of 2ml D N S colour .
reagent. ~ l l the tubes were heated i n a boi l ing water ba th f o r 5 minutes
and then cooled t o room temperature a f t e r which the .con ten t s of t h e tubes
were d i l u t e d t o 20ml with d i s t i l l e d water, The absorbance was read a t i
505 run agains t a reference blank. The blank was prepared by bo i l ing the
arnylase e x t r a c t f o r 5 minutes before adding to t h e 1% buffered s t a r c h
s u b s t r a t e so lu t ions , The concentrat ion of t h e reducing sugars a s maltose
i n the s t a r c h h ~ d r o l y s a t e was ca lcu la ted by ext rapola t ing i t s absorbance
value from the maltose c a l i b r a t i o n curve.
3.5.5 la terminat ion of optimum temperature f o r amylase a c t i v i t g
2ml of t h e d i l u t e amylase e x t r a c t was added t o 1 m l of 1% s t a r c h
( s u b s t r a t e ) so lu t ion buffered a t optimum p~ range 6-7, and incubated f o r
30 minutes a t various temperatures, 30, 40, 50, 60, 70 and 80Oc.
;!ml of (D*) colour reagent was added(and o the r procedures repeated)
and the concentrat ion of reducing sugars a s maltose calculated.
3.5.6 s t a r c h ex t rac t ion from t h e c e r e a l mains:
The w e t mi l l ing method of Watson(l97Q) was adopted i n t h i s work. The
I process involves cleaning, s teeping, coarse mi l l ing , deyerrning f i n e
~ r d l l i n y , separa t ion of f i b r e , s t a r c h separa t ion f r a n g lu ten , and drying of
3tdrch as shown in the flow char t (Fig . 3.1).
Two kilograms of cleaned g r a i n was placed i n a troqgh, and covered ' t with 3 litres of 0.45% sodium metabisulphite solut ion. The trough was kept
i n a water ba th maintained a t 4 5 O ~ f o r 40h. A t the end of t h e 40h, t h e
g ra ins were drained and washed wi th c l ean water. The g ra in was coarse ly
ground with a manually operated corona handmill, cons i s t ing of two s tud
p l a t e s of wtdch one p l a t e r o t a t e s while the o the r i s s t a t i c . The adjacent
f ~ e ; iif tl-ii plates are studded 'with t ee th , which are s o arranged t h a t the
g ra ins pass i n between the s t a t i o n a r y and moving plates. By adjus t ing the
p l a t e s , it was poss ib le to vary t h e d is tance between t h e t e e t h so a s to :
obta in a des i red p a r t i c l e size. The purpose of this mil l ing s t e p is t o
t e a r the ke rne l s a p a r t i n order t o l i b e r a t e the gems. .Some:endosperm
s td rch was however l i b e r a t e d during degenning. \
The s l u r r y of coarsely ground g r i s t w a s degenned by f l o a t a t i o n i n a
b ig bas in of water. The f l o a w d g e m was scooped with a guaze while the
rest of t h e ma te r i a l s s e t t l e d . The opera t ion was repeated many times by
swir l ing t h e c o n t e n t of the bas in u n t i l a l l the geqn w a s v i r t u a l l y removed.
The d e g e m d g r i s t was next screened on nylon bo l t ing c l o t h of 100 mesh to
remove the bulk of the f r e e , s t a r c h and gluten. The screen t a i l i n g f r a c t i o n
composed l a rge ly of p ieces of honey endosperm and f ib re .
The screen t a i l i n g f r a c t i o n was f i n e l y ground to achieve maximuril
s t a r c h l ibe ra t ion . The f i b m w a s separated from the s t a r c h and glu ten on
, \
screenin I--$
~ i g . 3. Flow chas t of w e t mi l l ing opera t ions i n s t a r c h production from ce rea l grains. . &/"
t h e nylon bol t ing c lo th . .The starch and-gluten f r a c t i o n s obtained from
both coarse mi l l ing and f i n e mi l l ing were mixed. The separa t ion of s t a r c h
. - from gluten was achieved by sedimentation. The s t a r c h with a dens i ty of . -.
1.5 s e t t l e d i n the aquaous s l u r r y a t a f a s t e r r a t e than t h e g lu ten p a r t i c l e s
\
of dens i ty 1.1 (Kent, 1975)., Tim s e t t l e d gluten and s t a r c h were made to
flow down a slop1)ed tray. The g lu ten flowed out f i r s t . The . s t a r c h
f rdc t lon wds fu r the r washed with water and the remaining glugen separated.
h f 'a ir ly gluten-free s t a r c h was obtained.
The s t ixch concentrate was placed between f o l d s of f i l t e r paper a d
0 dried i n an oven kept a t 50 C f o r 48h.
G
3*7 - ~ ~ r o a i m a t e / ~ h e m i c a l ana lys i s of gra ins , ma1 ts and s t a rches from Sorghum and ~ i l l e t :
3.7,1 Crude p ro te in determination:
Crude prote in of the samples was determined i n accordance with t h e
procedure of Association of O f f i c i a l Analyt ical Chemists A.O.A.C.(1980)
as follows:
bout 0.29 of t h e s a p l e w a s weighed o u t accura te ly i n t o a 50ml
k je ldah l f l a sk . The following were then added i n t o t h e f lask . 59
&hydrous sodium sulphate, 1g hydrated cupr ic su lphate and l O m l concentrated
sulphur ic acid. The d iges t ion w a s c a r r i e d o u t by heat ing the f l a s k on an
e l e c t r i c c o i l u n t i l i ts contents becane clear. Heating however was
continued f o r a t l e a s t one hour after the so lu t ion had cleared. ~ f t e r
kwating,the con ten t s was t ransfer red with severa l washing i n t o 25Oml
volun~et r ic f l a s k , and was made up t o the mdrk a f t e r cooling.
D i s t i l l a t i o n apparatuswas set up, and steam was passed through it
f o r 10 minutes. 5rnl of bor i c acid i n d i c a t o r was placed i n 25Qml conica l
f ldsk . The conidal f l a sk was placed under the condenser such t h a t t h e
condenser t i p was placed i n the d i s t i l l a t i o n apparatus and was r insed
'i" down with d i s t i l l e d water.' The cup was closed with t h e rod, and 5ml of
60% N&H was pu t in; t h i s was le t In c a r e f u l l y , leaving 'behind a l i t t l e
to prevent ammonia escaping.Steam w a s then let through f o r about 5 minutes . -
( u n t i l t he amount of l i q u i d in the conica l f l a sk was about twice what it w a s i n
i n the beginning of d i s t i l l a t i o n ) . Then the bor ic acid ind ica to r was t i t r a t e d
wi th 0.0W H c l t o the end point. The t i t re was the number of m l s of 0,OlM
[icl trhdt changes the ind ica to r from green t o pinkish colour.
Calcul &ions: -- -- -
L e t w represent weight of sample
I ,u t T represent ~ n l s of titre 0.0l.M ~ c l
1 l i t r e o f M H C 1 a 14.01gN
1 l i t r e of 0.0lM H c l = 0.4401 g~
Tml of 0.01M H c ~ = 0.0001401 x T g N
250 ---1 of d i g e s t = 0.0001401 x T x 250gN
5 - 5
% crude p ro te in = 0.0001401 x T x 250 x 6.25 x 100 ,w x 5
3,7,2 F a t Determination:
F a t w a s determined according t o the A.O.A.C.(1980) method of a r d y s i s
as follows:
0 A n ex t rac t ion f l a s k was cleaned, d r i ed i n an oven a t 100 C and its
weight determined. 29 of the sample was accura te ly weighed and t r ans fe r red I
i n t o t h e e x t r a c t o r thimble. The thimble with the sample was then pu t into
t h e Soxhlet ex t r ac to r . About three q u a r t e r s of, t h e con ta ine r w a s f i l l e d
with petroleum e the r .
allowed to run f o r about 3h.
~t t h e end of the e x t r a c t i o n , t h e thimble w a s removed and t h e e t h e r
The
to it and
condenser
f l a s k was placed on t h e hea t e r , t h e Soxhle t e x t r a c t o r connected
condenser i n t u r n connected to t h e Soxhlet. The t a p to t h e
was turned on and t h e hea t e r switched on. The e x t r a c t i o n was
e x t r a c t e d o i l weighed.
~ a l c u l a t i o m -
% f a t L W t of o i l x W t . o f sample
recovered. F i n d l y , t h e o i l w i l s dried a t 1 0 0 ~ ~ i n an oven and t h e
3.7 , 3 Crude F i b r e determination:
The A m e r i c a n Assoc ia t ion o f C e r e a l c h e n i s t s , A.~.C.c.,(1976) method
o f a n a l y s i s wds employed i n the determina t ion of c rude f i b r e i n t h e samples
a s follows: ti'
The r e s i d u e s from e'ther e x t r a c t de te rmina t ion or de- fa t ted samples
were t r a n s f e r r e d t o a d i g e s t i o n f l a s k . 200ml of b o i l i n g 1.5% su lphur i c
ac id was added. The d i g e s t i o n f l a s k was t hen connected to a condenser and
heated, The f l a s k was f r equen t ly r o t a t e d u n t i l t h e sanple w a s thoroughly
w e t . The f l a s k was removed after 30 minutes, f i l t e r e d through l i n e n i n
a funnel and washed wi th b o i l i n g water u n t i l the f i l t ra te was no longer
ac id ic . The i n s o l u b l e matter was washed back i n t o the d i g e s t i o n f l a s k
conta in ing b o i l i n g 15% NaOH so lu t ion . The f l a s k was connected to a
r e f l u x condenser and b o i l e d f o r 30 minutes, a f t e r which t h e mixture was
SO.
dlowed t o s t m d f o r b o n e minute. f he contents were then f i l t e r e d through
a cheese c l o t h i n a funnel and residue thoroughly washed with bo i l ing water II
and then with 1% hydrochloric acid, and again with bo i l ing water u n t i l
no lonyer acidic. Then i t w a s wcrshed twice with 95% ethanol , three times
with d i e t h y l e the r , and f i n a l l y t r an fe r red to a crucible. The c ruc ib le
and contents w e r e d r i ed to a constant weight a t 1 0 0 ~ ~ . The content was
then heated over a flame a t red hea t f o r 20 minutes. The c r u c i b l e was
cooled i n d des lcdtor m d weighed. The percentage of crude f i b r e was
ca lcula ted ds follows:
Crude f i b r e (%) 5 l o s s i n w t . x 100 - I w t , o f sanple 1
3.7.4 ~et t : rminat ion of A s t r - --- --
The A.O.A.C.(1980) method of ana lys i s was used f o r ash content
determinations.
About 5g of the stunple was weighed and heated i n a 50ml p e t r i d i s h
a t 1 0 0 ~ ~ u n t i l water was expelled. Few drops of pure o l i v e o i l w a s added
and the mixture heated over flame u n t i l swelling stopped. The d i s h was
then placed on a furnace a t 525Oc and l e f t the re un t i l white ash was
obtained. ,The ash was moistened.with water, d r i ed on a steam ba th and
then on a ho t p l a t e , t h e r e a f t e r re-ashed a t 525 '~ t o cons tant weight.
The ash content w a s ca lcu la ted a s a percentage of t h e o r i g i n a l
weight of the sample as follows: . .
Ash I w t . of ash x 100 w t . of sarnple
3-7.5 Tota l Carbohydrate determination:
0,2g of ground sample w a s mixed wi th 50ml of d i s t i l l e d water i n a
boil ing beaker. 3ml of concentrated .. . I l c l . w d s added and the mixture boi led
u n t i l complete hydrolysis. The content of t h e f l a s k was cooled &::d i
neut rd l i sed with 5N NaO1.I solut ion. The hydrolysate was then t r ans fe r red
i n t o a 100rnl volumetric f l a s k and the volume rnade up t o 100ml wi th
d i s t i l l e d water. 0.2ml of this s o l u t i o n w a s p ipe t t ed and mdde up t o 2ml
(10 fo ld d i l u t i o n ) with water f o r the dctemir?at,ion.
G ~ U C O S ~ was determined using t h e anthrone reagent (Deriaz, 1961). A
stock glucose so lu t ion of O.8mg/ml was prepared. Glucose standards were
prepared by ddding O m l , 5m1, 10m1, 15m1, 20ml, and 25ml of the stock
so lu t ion i n t o s i x d i f f e r e n t l O O m l volumetric f lasks . The volumes were
made ui) t o the mark with d i s t i l l e d wd te r .
l m l of each of the standard so lu t ions and test simples were
respect ive ly p ipe t t ed i n t o test tubes. To each of t h e test tubes, 5ml
of dnthrone r e g e n t wcjs added and properly mi,xed. These were covered ond
inunedidtely p u t i n a bo i l ing water ba th f o r 20 minutes f o r t h e colour to
develop. They were cooled and t h e i r absorbance measured a t 620nm. From
t he standard glucose c a l i b r a t i o n curve plot ted , the concentrat ion of
glucose i n the test sample was read off.
Calculdtion:
% total. carcohydrate P mg of glucose equivalent t o sample absorbance
from graph x conversion fackor(25) x d i l u t i o n fac tor(10) .
3.7.6 Gele t in iza t ion temperature determination:
Ttm g e l e t i n i z a t i o n temperature determination was c a r r i e d o u t in
accordance with t h e rnethod of Novellie ilnd ~ c & t e :(1961).
29 of ground sample w a s pu t i n 40ml of water i n a l a r g e test- tube, and
quickly brought t o the desired tunpera ture with good s t i r r i n g f o r a t l e a s t
5 minutes heating. ~ f t e r g e l e t i n i z a t i o n , * e mixture was cooled t o 30°c
md placed i n a cons tant temperature water bath. Malt e x t r a c t (40rnl) was
added and a f t e r a thorough i n i t i a l mixing, the mixture was s t i r r e d hal f
hourly f o r 3h. A s m p l e 20ml was withdrawn and added t o 30ml of 0,SN '
NaOH so lu t ion i n a 250ml ' v o l u m e t r i ~ f lask . The mixture was made t o volune
asld t he s u g a content detennincd by Benedict 's quan t i t a t ive method(Plummer,
1977). For the blank, equal weight of sample was p u t i n t o 40ml of
w d t e r and e x t r a c t (40ml) added to the ungelat inized s t a r c h a t 30°c f o r 3h,
The reducing sugar w d s s i m i l a r l y determined a f t e r stopping the enzyme act ion
with 30ml of 0.5N NaOH solut ion.
25ml of ~ e n e d i c t l s q u a n t i t a t i v e reagent was measured i n t o a l O O m l
conical f lask . To t h i s was added 3g of anhydrous Na--CU3 and a few pieces
of anti-bumping granules. The mixture was heated over a bunsen flame and
when i t boi led vigorousl.y, the sugar so lu t ion was run i n slowly from a
tiurt:tte. When ~i bulky white p r e c i p i t d t e w d s formed, the s u g a so lu t ion was run
in more slowly u n t i l t h e l a s t t r a c e s of blue had disappeared. The t i k e
which was the volume of sugar requi red was noted.
The concentrdt ion of the sugar was cdlcula ted from the following
fdctors ; 25ml of Benedictcs reagent i s equivalent t o 50mg of glucose, 53mg 8
of f ruc tose , 68.8mg of l ac tose , 74 mg of maltose o r 49mg of hydrolysed
sucrose.
mg s u q a per 100ml
where f P. sugar fdc to r
3 7.7 s t a r c h deterinination i n s t a r c h concentrate by hydrolyt ic method:
A typica l method employing acid hydrolysis f o r the determination of
sterrch i n f-lours is t h a t of Radley(1976) employed i n t h i s s tudy as follows:
2-59 of d ry s t a r c h concentra te w a s mixed with 50ml of cold water and
dllowed t o stand f o r lh. 2011-11 of H c l and 150ml of water were added t o the
suspension. his w a s p u t i n t o a round bottomed f l a s k and r e f l u e d f o r 2h.
The content of the f l a sk was cooled and neut ra l i sed with 5N NaOH. The volume j I
w a s l a t e r mdde up to 2SOml. lml was p ipe t t ed into a 100ml volumetric f l a s k 1
m d the volume made up to the mark with d i s t i l l e d wat . Glucose was t;Jr determined using t h e anthrone reagent(Deria2, 1961). A series of glucose
so lu t ions were prepiired, s o t h a t l m l c o n t d n s 0.04 - 0.2mg, and. these
were used t o c a l i b r a t e the glucose standard curve. I .. ,
I m l
pipe t t r d
-.7,7nC.."l ' - --r -* -y
ba th f o r
of each of the standard so lu t ion and the test sample was respect ive ly
i n t o test- t*&es. To each, 5ml o f anthrone reagent was added and I !
mixed. These were covered and immediately p u t i n a bo i l ing water 1
20 minutes f o r the colour t o develop. They were cooled and t h e i r
absorbance measured a t 620m aga ins t a blank which contained only I m l o f ,
water and 5ml of anthrone reagent. The concentcation of t h e test sample . . .
wcls obtained f r a n t h e & s o r b a x e by e x t r i r p o i a i i a ~ . The mass of glucose d
wclv o b t d n e d by c d c u l d t i o n s involving the concentrat ions and d i l u t i o n s
mdde. The mclss of s t a r c h was con:eq!ently obtained from t h e mass of
j lucosc using t h e r e l a t i o q
~ , i s s of glucose x 0.9 = Mass of s tarch .
production of Malt based Syrups:
3 , ~ . 1 *wort preparat ion by th ree s t age decoction Mashing Method from Sorghum malt.
The method, cu r ren t ly adopted f o r masl~ing bar ley m a l t a s described
by ~ o u g h e t , &.,(1981) was used i n t h i s work as follows: - Sixty grams of Sorghum malt mil led t o 1-2mm p a r t i c l e s i z e ( i n a Thomas
illy ill Model'ED 5 ) was mixed with 32Gml of t ap water, t o give 18.4%
mash. This !as held a t 40°c f o r 30 minutes. One t h i r d por t ion o f mash
was withdrawn, boi led f o r 5 minutes, and qeturned t o the main mash. The
temperature of the mash rose to SOOC and was maintained a t t h i s temperature
f o r 15 minutes a t a pH 6.5. (This was adjusted wi th 2~ Ca(OHI2 ~ 0 1 ~ t i 0 n ) ~
One t h i r d por t ion of the mash was again removed, boi led f o r 5 minutes and
returned t o the main mash. The temperature of the mash was ra i sed t o 60°c,
and t h i s was maintained a t a temperature range of 60-65O~ f o r 30 minutes. .
A f u r t h e r one t h i r d por t ion of the mash was removed, boi led f o r
5 .minutes and returned to the main mash. The temperature rose, and was
maintained a t 70-75O~ ( the m;shing o f f temperature) f o r 30 minutes.
3 w 8 2 Effec t s of varying mash concentrat ions and S x c h a r i f i c a t i o n periods on reducing sugar contents of worts in a t h r e e s t age decoction mashing.
I n the mashing method discussed above, p ro teo lys i s was dllowed a t
4uDc and 50°c. sacchar i f i ca t ion by t h e malt amylases was encouraged by
holding t h e mash a t 60 - 6 5 O ~ rvld 70 - 7s0c temperatures respect ive ly . Mash
concentrat ions of 25%, 35%, and 45%, and t o t a l sacchar i f i ca t ion periods of
Ih , 2h, and 3h were employed i n t h e production of warts. The r e s u l t i n g '
reducing s u g d con ten t s (as glucose) determined a s described under sec t ion "
3 .9 .4 .
3 - 8 - 3 E f f e c t of v x y i n g concentr~tt. jons of a lucomylase and uaccharif i c a t i o n - , -
periods on the reducing sugar contents of wort.
Wort W ~ Y p r e p d e d from a 25% mash. Its pH was adjusted t o 4.3 with a
0 3~ ~ c l so lu t ion , and temperature maintained a t 55 C. Varying concentrat ions
of glucoamyl~sc; 0.09%, 0.10X and 0,15X (dry weight b a s i s of the mash) were
ddded respect ive ly , then sacchar i f i ca t ion c a r r i e d ou t f o r 12h, 24h, and
The r e s u l t i n g hydrolysates were neu t ra l i sed , f i l t e r e d and malysed f o r
reducing sugar content ( as glucose) , as described under sec t ion 3.9.4 '
3.8 -4 Ma1 t bdsed- Syrup production:
50y of sorghum malt mi l led t o 1-2mm p a r t i c l e s i z e ( i n a Thomas wiley
M i l l , Model ED-5) was mixed wi th 2 0 h l of tap water t o g ive 25% mash. The
ptf of the r e s u l t i n g wort w a s adjusted t o 4.3. X t r temperature was maintained
a t 5 5 ' ~ using a thennos ta t i ca l ly con t ro l l ed water bath. 0.15%- glucoamylase
(D.W.B of the mash) was added and incubated f o r 24-72h (with cons tant
shaking) unt i l t h e des i red DE value was at tained.
The m a l t hydrolysate s o l u t i o n produced was neu t ra l i sed with 2M Na2C03
solut ion. A t e n f o l d d i l u t i o n of it was made, f i l t e r e d (wi th f i l t e r paper)
and. f i n a l l y concentrated to a syrupy consistency by evaporation on a
bo i l ing water bath.
/ ~ h r e e s t age decoction mashinq/
1
J /~nzyme sacchar i f i c a t i o n l
1
JI . . h i n i s h e d product ( ~ a l t syrup)/
~ i g . 5. Flow c h a r t of malt based syrup production. . \
3.9 Glucose Symp Production:
The acid-enzyme(dua1-stage) conversion method w a s used i n the glucose
syrup production. I n the f i r s t s tage , which w a s acid l ique fac t ion , s t a r c h
w d s mixed w i t h water t o form a suspension of s i u r r y , conicaininy 25% d r y
s tarch . his was poured i n t o a pyrex f l a s k and i t s pH adjusted to 1.8
with 3M H c l so lu t ion , The f l a s k and its con ten t w a s autoclaved f o r 20 minutes,
The r e s u l t i n g hydrolysate w a s cooled, and neu t ra l i sed t o pH 6.0. T h i s
was l a t e r f i l t e r e d i n t o a flask, and t h e second s t age of the conversion,
enzyme sacchar i f l ca t ion e f fec ted by addi t ion of 0.15% g l u c o a m y l a s e ( 9 ~ ~ o f
s t a r c h ) , and holding i t i n a w a t e r bath(with cons tant a g i t a t i o n ) a t
was determined by the des i red DL level . The r e s u l t i n g s t a r c h hydrolykite
was concentrated by evaporat ion on a boi l ing .water bath,
4 h o n - exchange deionized/
I
Fig. 4. Flow c h a r t of Acid-enzyme converted glucose syrup production.
3.9 Determination of some Proper t i e s of Syrups:
3.9.2 Determination of Spec i f i c q r a v i t y / ~ e g r e e baume of the Syrups.
The s p e c i f i c g r a v i t y of the syrups were determined according t o t h e
procedure described in ~.O,A.C.(1980) method of analysis .
A 50ml s p e c i f i c g r a v i t y b o t t l e was f i l l e d with d i s t i l l e d water,
0 stoppered irnd immersed i n water ba th a t 20 C. Af ter 30 minutes-, t he
s p e c i f i c g rav i ty b o t t l e was removed, d r i ed with f i l t e r paper and weighed.
The sme procedure was repaated with the s m p l e s . The s p e c i f i c g r a v i t y
of the samples were ca lculdted as follows:
SG P weight of l i q u i d held i n SG b o t t l e weight of water held i n SG b o t t l e .
Uegree baurne ( ' Me' 1
This is r e l a t e d t o Speci f ic grdvi ty b y , t h e following fonnula(Corn
r e f i n e r s Assacidtion, 1965) .
3 ,go 3 " Determkidtion of percentage t o t a l s o l i d s of t h e Syrups.
A sample of the syrup w a s t r ans fe r red i n t o a previously d r i ed and
weighed s t a i n l e s s steel dish. The d i s h and content was l a t e r placed on a
boiling water ba th and evaporated to dryness, This was weighed and then
placed i n .an oven and d r i ed f o r 3h a t 1 0 5 ~ ~ . The d i s h was returned t o the
oven and weight checked a t thirty minute i n t e r v a l s u n t i l no f u r t h e r l o s s
i n weight could be detected. The d i s h was cooled i n a d e s i c a t o r f o r
20 minutes and the weight taken. ti'
The percentage t o t a l s o l i d s , was ca lcu la ted thus:- .
% t o t a l s o l i d s = W t of sample a f t = drying x 100 W t of sample bekore 'drying
! ' 3.9.4 J Percentage reducing sugar conten t / ~ e x t r o s e equivalent ( DE.) value determination.
Reducing sugar content (as glucose)/Dextrose eqUivalent(DE) values of
thesyrup s m p l e s were detenninfid &cording t o the I n s t i t u t e of Brewery
I.O.U.(1977) method of analysis as follows:
It% w/v solu t ion was ,prepared by weighing.25,OOg of the syrup i n a . . .
gldss d i sh and dissolving same by.gradua1 s t i r r i n g i n warm water. his
w d s t r a s f e r r e d quan t i t a t ive ly to a 2501111 graduated f l a s k , and a f t e r
0 adjus t ing the temperature t o 20 C, it was mdde up to the mark a t t h a t
temperature. 251111 of t h i s so lu t ion was p ipe t t ed i n t o a 250ml graduated
f l a s k and d i l u t e d t o mark a t .20°c. This was mixed w e l l and f i l t e r e d . I t
wr i s used as the "di lu ted solution".
25ml of mixed Fehlings' so lu t ion was pipetted i n t o a 250rnl S a i l i n g
f lask; and m almost sufficient of the d i l u t e d so lu t ion was added from the
b u r e t t e t o the cold fehl ings ' so lu t ion t o e f f e c t reduction, s o t h a t , i f
poss ib le , n o t more than l m l was required l a t e r to complete the t i t r a t i o n .
The contents of t h e f l a s k was mixed, and heated over a w i r e gauze, k e p t i n
moderate e b u l l i t i o n f o r 2 minutes and th ree drops of methylene b lue ind ica to r
added without removal of the flame, then the t i t r a t i o n completed i n one
minute with continuous e b u l l i t i o n . I
The end point (decolor iza t ion of the methylene blue) was taken as the
volume ' d t which the r eac t ion mixture turned red. The t i t r e was recorded.
Calculations:
The r e s u l t s were,ccilculated a s the most appropriate sugar (glucose o r
maltose) using the appropr ia te f a c t o r from t h e l ane & Eynon table . For the
d i l u t i o n given, the percentage reducing sugar i n the sample ' a s isg
% ~ e d k i n ~ sugar = Lane & Eynon f a c t o r x 100 T i t r e .
Dextrose Z q u i v a l e n t ( ~ ~ ) r % reduclnq sugar (as glucose) x 100 % t o t a l s o l i d s
3 m9.5 . - Deterrnl-nation o f colour of the syrups:
The colour of the syrups were determined by the procedure described
i n A.O.A.C(l980) method of apdysis as follows:-
59 ce l - i t e was added t o 100rnl f i l t e r e d syrup, mixed and f i l t e r e d
through f i l t e r pclper. The f i r s t 40ml f i l t r a t e was returned t o the f i l t e r .
Absorbmce of c l e a r t o t a l f i l t r a t e was determined a t 430m using a
spectrophotorner. Syrup colour was ca lcula ted a s . follows:
colour = 1 0 . x x correc t ion t o 4' cell s i z e . c ~ l o u r was reported to t h e
nea res t 0.05 uni ts .
CHAPTER 4
4. RESULTS AND DISCUSSIONS
4.1 ~ a l t i n g c h a r a c t e r i s t i c s of t h e ce rea l p;rains, sorghum and millet:
Table i shows the malting c h a r a c t e r i s t i c s of the c e r e a l g ra ins
used. The values of 33.30g and 6.8g 1000-kernel weight obtained respect ive ly
f o r sorghum and millet g r a i n s were smaller compared t o 50.9g f o r b u l e y
reported by s ingh and ~ a u r o ( 1 9 7 7 ) . However, s ince these g ra ins are
smaller i n s2ze, it is expected t h a t the weight would be smaller. his
agrees wi th the suggestion made by Nout and Davis(1982) t h a t i n l a r g e
s c a l e malting, modification i n p l a n t cm be ef fec ted t o take care of the
d i f fe rences i n s i z e of the grains.
The percentage fore ign seeds and broken kernels gave 0.32% and 0.56%
re3;)ectively f o r Sorghum and m i l l e t grains. These r e s u l t s show t h a t
broken kernels and foreign seeds are r e l a t i v e l y low from t h e bulk g ra in
samples.
tiough et &., ( 1981) repor ted t h a t f o r good malting q u a l i t y of barley,
minimum germinative energy (G.E) requi red is 96%. However, i n t h i s study,
G.E. of 82% and 76% were obtained respect ive ly f o r sorghum and ' m i l l e t
grains. Aniche(l302) obtained 60%
(G.C. ) f o r L 181 sorghum var ie ty ;
7% germinative energy f o r millet.
C.E. and 98.5% germinative 'capacity
while Singh and Tauro(1977) reported
Germhative capaci ty (G.C.) of 90%
and 85% were obtained f o r sorghum and m i l l e t respect ive ly in t h i s study,
iind s ince G.C is a measure of percentage of l i v i n g corns under aided
condi t ions , i t i s therefore suggested t h a t hydrogen peroxide be used
62.
durlriy 111dlthg of sorghum iuld m i l l e t g r a i n s to enhance germindtivt: cclpacity.
MAIJTING CKARACTERISTICS OF l l i E CERAL GRAINS: SORGHUM AND MILLET
~ h a r a c t e r i s t i c s Sorghum Millet
1000 - kernel weight(g) 33.30 6 .8
% Foreign seeds and broken kernels ' 0.32 0.56
Germinative energy (% ) 82 76
O p t h u m mj l t ing condit ions of the Cereal grains: Sorghum and Millet:
Figures 6 t o 10 present t h e optimumgmalting condi t ions of the
ce red l grains. The v a r i a t i o n o f moisture content(%) aga ins t s t e e p time(hours1
i.s shown i n f i g u r e 6 , The r e s u l t i n d i c a t e a sharp rise i n water uptake
during the f i r s t 1'0 hours. Fur the r s teeping above 20 hours showed marginal
increases. I t i s evident from the r e s u l t s t h a t sorghum gra ins absorbed
moisture fclster than m i l l e t gra ins , t h i s may be due t o i t s r e l a t i v e l a r g e
corn s ize . Dahlstron e t g . , ( 1 9 6 3 ) observed t h a t l a r g e r corns absorb water - - more rap id ly than smaller ones i n i t i a l l y , and the d i f fe rence i n water
absorption a f t e r 24 hours is marginalised. Also Hartong and Kretschmer
(1961) found t h a t samples of g r a i n s t h a t absorbed w a t e r f a s t e r gave b e t t e r
malts than g r a i n s t h a t absorb water more slowly.
0 The r e s u l t obtained from t h e p l o t of d i a s t a t i c power( L) agains t
steep t i m e (hours) f i g u r e ' 3 , showed t h a t the opthum s teep t i m e Was
1 1 I 1 1 I I \ I
10 20 30 40 50 . 60 70 80 Steeplng t i me (hours )
Fig. 6 : Moisture content (%) against s t e e p i n g t i m e ( h o u r s ) . Sorghum grain
i M i l l e t g r a i n
20 ' 30 S t s e p i n g
Fig. 7 : Diastotic power (%) against st;esping tima (hours) a f ter 4 days o.f ge rmina t ion . - .. b-d 8 Sorghum, o-o 8 Mil let '
50 kwurs. A t t h i s time, the d i a s t a t i c powers of the two cerea l s were
mdx.i.mum a f t e r the grains w e r e allowed to germinate f o r four days. Furthermore,
extrapolating the 50 hours optimum steep t h e t o r e s u l t s of the p lo t of
moisture content(%) against time(hours) f igure fj, gave variously 38%
and 33% optimum moisture contents f o r sorghum and m i l l e t grains respectively. I
out and Davis (1982) obtained 45% moisture c o n b n t a f t e r 35 hours and
20 hours of steeping sorghum QAndivo' and sorghum 'igumba, respectively.
The optimum gemination period of 5 days was obtained after steeping '
I the grains fo r 50 hours. This r e s u l t was deducted from the p l o t of
d i a s t a t i c power (OL) against germination periods(days), f igure 8 The
0 r e s u l t a l so indicate t h a t rnJxknum d i a s t a t i c pX!=rs of 32O~ and 27 L were
'
obtained respectively f o r sarghum and m i l l e t malts under the same st ipulated , I
malting conditions. The r e s u l t shows t h a t there was no d i a s t a t i c power I
measurable in ungerminated grain but rises sharply fran 1-3 days reaching
i ts peak a f t e r 5 days of gemination. This suggests t h a t d i a s t a t i c enzymes
absent i n ungerminated grain develops with germination. I t has been established
tha t alpha anylase was not present i n the ungerminated sorghum grain and t h a t
the ac t i v i t y was only measurable a f t e r germination(Aisien et z., 1983). i I
Figure 9 -shows the r e s u l t of malting loss (%I measurements during
the various periods of germination(days). The r e s u l t showed t h a t the
malting l o s s of grains increased with increase i n the period of germinatim.
Signif icant increases i n malting l o s s were recorded between 2-4 days of
germination, which correspond ta t h e periods of s i gn i f i can t drops in
1000 - kernel weights during gemination. The ranges of 12 - 16% and 16.20%
G e r m i n a t i o n p e r i o d ( d a y , ) F i g . 8 : Diastolic power (%I a g a i n s t germination p e r i o d s ( d a y s )
a f t e r 50 hours of steeping. I
H '= Sorghum, M = Mill8 t
I 1 I 1 1 1
2 3 4 5 6 7 Germinat ion pkr iod ( doyo )
9 : Molting loss (%I against perminotion per iod ( d a y s ) . 04 a Millet molt
M Sorghum ma I t
malting losses were obtained respectively f o r sorghum and m i l l e t m a l t s
covering 4 to 7 days of gemination. The malting l o s s f o r barley have
been given by Hough et: ( 1981) ae 6~12%. The high malting l o s s of
the millet grains could be due t o excessive aeration during sixaping
leading t o grains growing uncontrollably dullng germination according to
H o u g h e , &., (1981). Malting l o s s could also r e s u l t from long steeping
period a s materials trend to be leached i n t o the s teep water. .To reduce
malting l o s s , it, i s suggested t h a t the f i l t e r paper8 used should no t be
saturated with water, o r I n the a l te rna t ive , malting f loors should be wed.
Relault of kilning s tudies , ( f igure 10 ) shows t h a t moisture re lease is . ;
reciprocally re la ted to moisture absorption. Signif icant l o s s i n moisture
w a s recorded after 12 hours of ki lning a t 4s0c. With regards to moisture
level i n r e l a t i on to storage qua l i t i e s of malta, optimum ki lning can be
carr ied out a t 45O~ f o r 24-48 hours depending ~n the moist- l eve l of
t h e green malt and the moisture content of the m a l t required. The e f f e c t
of temperature on the m a l t characters was no t investigated, however,
other workers; Nout and Davis (1982) and Novellie,(1962) showed t h a t only
kilning a t .70°c resul ted in a s ign i f ican t l o s s i n d i a s t a t i c ac t iv i ty ,
kilning in the range of 4 0 - 6 0 ~ ~ caused only negligible destruction.
4.3 Evaluation of ma1t;l'squality characterist ics:
The malts* qual i ty charac te r i s t i cs were evaluated and the results
presented on tab le 5 .. Generally, low Cold Water Extract(C.U.E), high
Hot Water ~ x t r a c t ( ~ . W . ~ . ) and la static Pow~(DP). are indicat ive of good
m a l t character is t ics . Hough et; %,(1981) reported ~ a l u e s of 307 ~ O h g
Ki ln ing p e r i o d ( h o u r s ) ig . 1 0 : Moisture content (%) agoins* kilning per iod( hours) at 45OC.
o-a 8 M i l l e t malt, - k + - ? 8 $ o t r g h u m m a l t ,
(HUE , 18.6% (CWE) and 63 '~ (DP ) f o r barley malt!. Tha corresponding values
obtained i n this atudy f o r sorghum and m i l l e t malts( t @ l e f , .' were I
r e l a t i ve ly inadequate to pass fo r good malts. The high C.W.E obtained
may be due t o malting a t high temperature of around 2 8 ' ~ ~ aa against t h a t
0 f o r barley which is usually a t 15 C o r less (Preece, 1954). as w e l l ao a
higher moisture content achieved by sprinkling of water. Improvements In
the malting conditions f o r the grains could considerably reduce the high
C-9-E- , and increase the H.W.E. and D.P. values obtained. However, the
values obtained f o r Sorghum malt i n ' the three, qual i ty charac te r i s t i cs arc
comparatively more encouraging than those of m i l l e t malt.
THE MALT'S C\UALITY CHARACTERISTICS
Character is t ics Sorghum m a l t M i l l e t malt
Cold Water Extract , CWE(%)
~ o t water ex t rac t , HWE ( ~ O / k g )
4.A Determination of Optimum pH and Temperature conditions f o r malt's . - .
amylase act ivi ty .
The r e s u l t s of the optimum conditions (pH and tempersture) f o r mylase
ac t i v i t y of the malts were as pretsentsd i n f igures 12 ' and -13 respectively.
Figure 12 shows t h a t a t optimum pH range of 6-7, the amylase ac t i v i t i=e I
of both sorghum and mi l l e t malts were maximum. Also f igure 13 reveals
t h a t amylase ac t i v i t y of sorghun m a l t peaked a t optimum temperature range
- mg Maltose in 3 m l so lu t ion
Fig . I 1 : .Maltose cal ibrat ion c u r v e . '
40 50 60 70 80 90 T e m p e r a t u r e ( O C )
.IFi g 8 : Optimum ternperoture determination far ornylo~e activity in both millet, ond sotghum ma l t $. I t b
of 60-7o0cI while t h a t of m i l l e t malt b e c q e m a x i m u m a t 40-50°c. The
optimum p~ value rmge of 6-7 obtained i n t h i s etudy agrees with thQ
values reported by ahembe &-,(1988). S i l l s and Stewart(l984) reported
optimum pH range of 5.5-6.5 f o r purified barley alpha amylase. ~ o u g h
e t &.,(1981) points out t h a t pH value of 6.0 is quite su i tab le f o r - 0
anylase ac t iv i ty a t 65 C. The r e s u l t i s also in agreement with the pH
optima of 5.2 (Preeoe, 19541, f o r /3-amylase, and 7.O(Worthington, 1979)
f o r alpha amylase enzymes in barley.
shembe 6 &. , (1988) reported 35-45O~ temperature optima f o r m i l l e t
and 50-75Oc $or sorghum m a l t s @ amylase ac t iv i t i es . Also S i l l s and Stewarts
(1984) reported values of 3 5 - 4 0 ~ ~ f o r pur i f ied barley alpha amylase. A
Chandraskhara and swminikhan ( 1958) showed optimum d P e r a t u r e f o r both
alpha and b-anylases in pearl m i l l e t t o be 60°c. The &mporature optima in
both cases are below gelat inizat ion temperature ranges of millet(70-80°c)
and sorghum (68-80°c) obtained i n t h i s study; a necessary prerequis i te fo r
e f fec t ive degradation of s ta rch by amylases. T h general poor malting
qual i ty of sorghum and m i l l e t ! gra ins as a lso reported by other authors is
thus
4.5
f a t ,
pa r t ly due to this fact .
~roxim&/~hemica~. analyses of the sorghum/millet grains and maltst
The r e s u l t s of proximate analyses (moisture content, crude protein,
crude f i b r e , and Ash) t o t a l carbohydrate. and 'gel a t l n i zation temperature
ranges of the grains and m a l t s used i n producing the syrup8 are
i n . t a b l e 6 , , he proximata cmposi t ion values obtained f o r mi l le t grains
and its malt w e r e c lose to those reported by Opdrtu et . , 1 9 8 1 Also
Aniche (1982) proximate composition values reported f o r Sorghum malts
( t ab le 2 ) caipclred f avourably with the values obtained i n t h i s work.
The Sorghum values f o r protein, 10.40%, c l o s e l y agree with 10.9% reported
by Hough et . , 1 9 8 1 . The r e s u l t show t h a t sorghum has lower values
of f a t , and higher values of carbohydrate and protein than mille t . Grains
used f o r syrup production should be low i n fat and protein but r i c h i n
to tdl carbohydrate especially starch. Cereals with higher f a u p r o t e i n
contents are considered unsuitable f o r glucose syrup manufacture since
they have detrimental e f f ec t s on flavour ar\d contribute t o colour v i a maillard
reaction. I n malt based syrup production, where colour is r a the r required,
the high protein content f ac to r i s no more necessary, therefore sorghum
grain is bes t su i ted f o r the malt syrup production.
TARLE 6.
CHEMICAL/PROXIMATE ANALYSES OF SORGHUM/MLLLET GRAINS AND MALTS
~ i l l e t Sorghum
Grain Malt Grain Malt
Moisture content(%) 9-10 ' 6.50 10.12 7.50
Crude protein (%I 8.30 10.50 10.40 11.30
4.6 Chemical analyses of starches extracted from mi l l e t and sorghum, grains:
Starches were extracted from mi l l e t and sorghum grains and subsequently
subjected t o chemical analyses. The r e su l t s obtained are presented on
t51e 7. The lower s ta rch contents of 76*40(millet) and 83.40(sorghum)
d-.-.P.-.. r e l a t i ve to values obtained by Brenner - et - & . , \ L Y Q O ~ and nuisr &, &.,
(1980) may be due t o the unsophisticated equipment which was used during
the s ta rch extract ion process. The pr incipal parameter i n the refined
s ta rch concentrate which a f fec t s both the qual i ty and volume of glucose
syrup is the s ta rch content. The higher the s tarch content, the greater
the reducing sugars obtained on hydrolysis., The comparatively higher protein
values of 2.1% ( m i l l e t s t a rch) and 2.4%(sorghum starch) a s against 0.2016
reported by Hulse & &.,(1980) may equally be due to inadequate separation i
of gluten from starch. The leve ls of f a t 0.83% ( m i l l e t s t a rch) and 0.66%
(sorghum s ta rch) are also higher than 0.003% reported by B r e n n e r c 2.. (1968). Therefore, a more sophisticaited equipment than tk one used i n
t h i s work is suggested f o r s ta rch extract ion i f glucose syrup with a near
water-white colour i s desired.
Table 7 shows t h a t the gelat inizat ion temperature ranges of the
extracted' refined starches are lower than t h a t of the corresponding grains
( t ab l e 6 ) thereby rendering the refined s ta rch more susceptible t o
amylalytic degradation. However, sorghum starch, having a lower gela t inizat ion
temperature range, lwer f a t and ash contents than m i l l e t s t a rch is preferred
i n glucose syrup production.
TAJ3LE. 7.
CtiEMlCAL ANALYSES OF STARCIIES FROM MILLET AND SORGHUM GRAINS
Millet s ta rch Sorghum s ta rch
~ o i s ture content (%I 9.2 8.6 b ;'
Crude protein (76) ' 2.1 2 .4
Fat (%)
Crude f i b r e (%I 0.71 0.27
Ash (%I 0.60 0.40
Starch content (%) 76.40 83 .40
4.7 Effects of varying mash, glucoamylase concentrations and saccharificc~tion - periods on reducing sugar contents of the wort syrup:
Figures 15 and 16 show respectively the r e s u l t s of the e f f ec t s of
varying mash concentrations and time; glucoamylase concentrations and time;
on t h e reducing sugar content of mort syrup. Results show t h a t makimum
conversion was a t ta ined a t the lowest substra te concentration, 25% mash;
highest enzyme-substrate r a t i o , 0.15% glucoamylase and a t a longer
sacchar i f icat ion time. However, there are feas ib le ranges of in teract ing
variables during the sacchar i f icat ion process of syrup production. The
25-35s subs t ra te concentra$lon range struck a b a l e e b e t w e e n the cos t of
removing excess water from hydrolysates against higher conversfon t o glucose
a t ta inable a t low substra te concentration, Also, 0.10 - O,f i .% enzyme-
subs t ra te r a t i o is reasonable s ince cos t of enzyme balanced against
sacchar i f icat ion and equipment required f o r long saccharification. The
0 ~08 0.1 2 0.16 G l u c o s e conc. (mq/ml )
F i g . 1 4 Glucose s tandard c u r v e . .. .
T i m e < h o u r s ) . Fig . I5 Effect o f vary ing mash concenirot.ion and t ime on
reducing sugar .;content of the wort a
= 45% mash, H = 3S0/, mash , )++( 25'10 mash
Fig. 16 : E f f e c t of w r y i n g concentrat ions of g l u c o a m y l a r e , . ~ n d time on the reducing sugar content o f the wort syrup.
5 0 0 -
480-
460-
% 440- 0 0 L Q,
a 420- Q) Ln 2 C
M
g400- u' E
380-
360
= 0.05 % of glucoarnylase M = 0 10 % of giucoamylase w, = 0.15 O k of glucoamylase
,
J
0 12 Ti me ( hours 24 36
sacchar i f icat ion range of 12-72 hours chosen f o r the experiment w a s based
on enzyme-substrate r a t i o used and extent of corrverlion cle,aircd, The
optimum temperature range of glucoarnylase ac t i v i t y is S O - ~ ~ O C , where the
upper l im i t i s dependent on glycoamylasestability, and lower l i m i t on neid
t o i nh ib i t microbial contamination during long saccherrification periods.
Furthennore, the pH 4-5-0 is dependent on aource of glucoanylase, and a l so
eug& are most s t ab l e a t this pH range.
4.8 Properties of malt based syrups and acid-enzyme converted glucose syrups: !
Tables 8 and g show the r e s u l t s of analyses i n some properties of i I
malt based syrups and glucose syrups produced i n this study. The r e s u l t s !
show, three c lasses of syrups; Regular ( 4 2 ~ ~ ) , intermediate ( 5 2 ~ ~ 1 ,
and High (69~~j. Conversion syrups were produced f o r malt and glucose
syrups respectively.
The values of 4 3 ' ~ ~ and 42OF3ef density ware obtainad f o r m a l t syrups
and glucose syrups respectively, The higher value f o r malt syrup may be
due t o its r e l a t i ve ly higher content of cellulosfic materials.
The r e s u l t a l so show t h a t the ash content of m a l t syrup was 0,4% while
that of glucose syrup was 0,65%. Junk and Pancoast,(l973) noted t ha t the
normal concentration range of ash i n corn syrup was from 0.1 - 0.3%. The
higher ash content of glucose syrup obtained may be as a r e s u l t of sod im
chloride, which is derived primarily fran the neutra l izat ion of hydrochloric
acid w i t h sodium carbonate during the acid l iquefaction process. '
Colour values of 5.1 un i t s and 2.2 un i t s were obtained f o r m a l t ant!
glucose syrups respectively. Junk and Pancoast(l973) a l so noted t h a t the
colour of newly refined'corn syr-p is usually @water-whlte( and has a
value of 0.25 units. The higher value of malt syrup colour i s a t t r ibu ted
t o the colour developed during the ki lning process of malting. However,
the colour of the glucose syrup could be reduced through carbon &d ion-
exchang~ ref ining processes.
he carbohydrate composition as glucose(%) and maltose(%) r e s u l t s
show a s imilar trend on both tables. Generally, the values increase
proportionately across the three c lasses of syrups, Also, mare g l u c o s ~
are i n each case produced than maltose, this is expected since the
glucoamylase preparation from fermentations of Aspergillus niger contain
r e l a t i ve ly l e s s amounts of 8-amylase.
The lower glucose yie ld i n m a l t syrup r e l a t i v e t o glucose syrup i n
the three c lasses of syrups may be due to poor d i a s t a s i s of the m a l t s
0 amylases whose temperature optima, 60-70 C, is lower than the m a l t ' s
s t a rch gela t inizat ion temperature range of 68-F30°c; Consequently, generating 8
more l i m i t branched dextrins which are less susceptible t o glucoamylase
than the l i nea r dextrins(Abdul1ah A., 1963)
Results .also indicate t h a t maltose contents of malt based syrups are
s l i g h t l y higher than thoge of glucose syrups{ this trend might be traced
to the r e l a t i ve . quanti ty of p-anylase which is a major component of malt
amylases and a minor consti tuent of glucoamylase enzyme preparations from
Aspergillus niger. -
TABLE. 8.
PROPERTIES OF MALT BASED SYRUPS
Property Regular Intermediate High
Dextrose equivalent (DE ) 42 52 69
0 Commercial Bauma( B e ) 43O 43O 43O
~ l u c o s e (961 2 0 28 4 1 I
Maltose (96) 15 19 2 2
TABLE, 9.
PROPERTIES OF ACID ENZYME CONVERTED GLUCOSE SYRUP
Dextrose equivalent (DE) 42 5 2 69
0 Canmercial Baume ( Be' 42 42 42
Solids (%) 80 . 82.2 80
. ~ s ' h ( % I 0.65 0.65 0.65
Glucose (%) 23 3 1 45
Maltose (%) 13 13 2 0
CHAPTER 5
5. SUMMARY AND CONCLUSIONS
ConvenUonally, malt syrups used by food industr ies are produced fran
b u l e y . he broad objective of the present investigation was t o produce
rnalt Byrups pr ic ipa l ly fran sorghum and millet grains which would be used
by food industries. The Nigerian ecosystan does not 8upj$?rt th0 a g r i c u l t w a l
production of barley grains, thus jus t i fying thL8 objective. The r e s u l t s
prcrduced fran the invesaga t ion are summarized as follows:
1. Both the malting and m a l t ' s qual i ty charac te r i s t i cs of the grains
studied indicate t h a t aarghum generates be t t e r m a l t than millet .
2. 50 hours of steeping and 5 days of gemination a t room temperature gave,
A*&.- - - L a --.... ,.., YYLY16U111 d i a s t a t i c power development i n sorghum and m i l l e t grains. b
3. Feasible ranges of 25-35% substra te and 0.10-0.15% enzyme concentrations
are bes t sui ted f o r syrup production.
4. Sorghum s ta rch is more adequate f o r glucose syrup prodyction. High
colour value of the syrup obtained could be reduded when it is fur ther
refined with carbon and ion-exchange de-ionized processes.
One would therefore suggest fu r the r research in comection with,theae
r e su l t s as follows:
. More malting 'study is advocated in order t o f ind b e t t e r favourable Y
malting conditions f o r mi l le t ' e spec ia l ly i n the area of malting loss reduction.
b. The control and measurement of colour/flsvol.~,r acquired by sorghum m d l b
during the ki lning process.
c. Isola t ion, pur i f icat ion ,and characterization of sorghum malts alpha
. 85,
amylase and i ts t iultabil i ty i n starch liquefaction process of glucose syrup
production comparad with that o f a microbial alpha amylase.
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APPENDIX
Preparation of Analytical reagents, Dini t rosal icyl ic acid(DNS) reagent .
I g of 3 ' , 58 - d in i t ro sa l i cy l i c acid w a s disolved In 20ml ob 2N NaOH, T h i s was made up to 50ml with d i s t i l l e d water. 3 0 9 of potassium sodiumtartarate (Rochelle S a l t ) was then dissolved i n the resu l t ing solut ion, and made up t o 10Oml with d i s t i l l e d water and i s ca l led DNS reagent.
Anthrone Reayen t.
7601111 of sulphuric acid (98% W/W H2SC4) Y" &d=d ', 336n1 of w ~ t e r . with s t i r r i n g a f t e r cooling, 1g of thiourea and l g of anthroha were added and s t i r r e d u n t i l dissolved. The resu l t ing solut ion was s tored i n a refr igerator .
Hydrogen ~ e r o x i d e ( H ~ S O ~ ) , - 0.75% Solution:
A f resh solut ion was prepared each time by d i lu t ing S m l of 30% 4 0 2 (100 vol) to 200 m l with d i s t i l l e d water, The resul t ing solution was- stored i n a refr igerator .
Methylene blue, 1%
1g of the pure.dye was dissolved i n l O O m l of d i s t i l l e d water.
Ihver t sugar standard s o l u t i o ~
To 9.50g of pure sucrose was added 5ml of hydrochloric acid and di luted with d i s t i l l e d water to 100ml. This w a s s tored a t room temperature f a r several days, and then made up to 2501111. When required, 25ml of the stock solution was neutralised with ocdi-at hydroxide and made up to 200ml t o give a 0.5% inve r t solution.
Fehlinaos Solution A and Br
Commercial Fehling's solutions A and B for laboratory analysis were purchased from BDH company. Before each analysis an equal mixture of the two were made up to 5ml f o r d i a s t a t i c power determination and 25ml f o r reducing/~extrose equivalent determination.
Benedictc s reagent
1739 of sodium c i t r a t e and lOOg of sodium carbonate were'dissolved i n 8001111 of w m water, f i l t e r e d and made up to 850ml with water. ~eanwhi le , 17,3g of Copper Sulphate was dissolved in about l O O m l of water and made up t o 150ml. The f i r s t solut ion was poured i n t o a 2- l i t re beaker and the Copper Sulphate solut ion added slowly with stlrrlng.
Acetic acid 1 .ON:
28.65m1 g l ac i a l acetic acid a t 20O~ was di luted t o 5001nl with d i s t i l l e d water.
Acctate buffer s o l u t i ~ n , pH 4.6;
689 odium acetat. (CH CalNa.3H20) was dissolved i n 3 0 h l s f L O N ace t ic acid and made up to ane l i t r a with d i s t i l l e d water a t 20 C.
Sodium hydroxide, 0. Wt
4-09 of N ~ O H was dissolved i n one litre of d i s t i l l e d water. oy"
2% s ta rch solution, buffered a t pH 4.6:
A 109 cieam of soluble s t a r ch was made with d i s t i l l e d water.and poured i n t o about, 400ml of boi l ing d i s t i l l e d water s t i r r e d constantly, he solution was boiled fo r 2 minutes and cooled under cover, t o avoid skin formation t o 20'~. l O m l of aceta te buffer w a s then added and the volume made up to 500ml. This w a s prepared daily.
0. W ammonia solution:
6.7 m l of the concentrat& ammonia was di luted to l l i tre with d i s t i l l e d water.
Buffer Preparations:
Buffer were prepared according to the method described by Sidney and '
Nathan( 1955 ) as follows:
From the stock solutions of A t 0.l.M ace t ic acid (5.76m1 i n l Q O O m l water) and 8: 0.1M sodium aceta te 8.2g In l O O O m l water). Acetate buffer were prepared thus: pH 4 t 41.0ml A + 901111 B di luted to l O O m l
pH 5 t 14.8ml A + 35.2m1 B d i lu ted to l O O m l i
Also fran the stock solut ion of A : O.lM monobasic sodium phosphate (13.99 i n l O O O m l water) and B, 0.lM d ibas ic sod im phosphate 27.83g i n 1000ml water). Phosphate buffers were prepared thus:
pH 6 s 87.Tml A + 12.3ml B d i lu ted to l O O m l
pH 7 : 39.01111 A + 61.0ml B di luted to l O 0 m l . ,* pH 8 t 5.3ml A + 94.7ml B di luted to 100ml. !,- . --+
, ' "
,- ! . I : > * \ + b