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University of Nigeria Research Publications
MAZI, Emmanuel Alfred
Aut
hor
PG/M. Sc/86/4527
Title
LABORATORY Studies on Beer Production from Maize (Zea Mays)
Facu
lty
Agriculture
Dep
artm
ent
Food Science and Technology
Dat
e December, 1988
Sign
atur
e
A. . I .., ... ..h 42.J- --. , r Was ~ c c k ~ t c d i n ?art ~~FP!rnent C.1 1
The E equiremr-t For 'ornln Degree Of 1
LABORATORY S T U D I E S ON BEER PRODUCTION FROM MAIZE ( ~ e a m a y s ) AS A
SUBSTITUTE FOR BARLEY
'A T H E S I S SUBMITTED TO THE DEPARTMENT O F FOOD SCIENCE AND TECHNOLOGY, FACULTY O F AGRICULTURE, UNIVERSITY O F N I G E R I A NSUKKA, I N PARTIAL FULFILMENT O F THE REQUIREMENT FOR THE DEGREE O F MASTER O F SCIENCE DEGREE I N FOOD SCIENCE
MAZI, EMMANUEL ALFRED PG/M. sc/86/4527
DECEMBER, 1988
- \
CERTIFICATION
M r . Bnmanuel Alfred Mazi, a postgraduate s tudent i n the
Department of Food Science and Technology 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 work f o r the degree of Master
of Science (M.SC) i n Food Science. The work embodied i n t h i s t h e s i s
is o r i g i n a l and has not been submitted i n p a r t o r f u l l f o r any o the r
diploma o r degree of t h i s o r any o ther univers i ty .
(supervisor ) Head, Departrnept of Food Science and Technology Universi ty of Nigeria Nsukka ,
DECEMBER, 1988
DEDICATION
T h i s work i s d e d i c a t e d t o m y uncle Engr . Enwerem, O t a h
Frank .
ACKNOWLEDGEMENT
I wish t o express my profound g r a t i t d k t o my supe rv i so r ,
Professor Z.A. Obanu, Head, Department of kood Science and Technology,
Univers i ty of Niger ia , Nsukka f o r h i s i nva luab le guidance, encouragement
ancl f a t h e r l y advice throughout t h e du ra t i on of t h i s work. H i s a s s i s t a n c e
helped improve t h e q u a l i t y of t h i s work.
My s i n c e r e thanks a l s o go t o a l l t h e academic s t a f f and
postgraduate s tuden t s of t h e Department of Food Science and Technology,
Univers i ty of Niger ia , Nsukka f o r t h e i r c r i t i c a l and c o n s t r u c t i v e cornments
on t h i s work.
I a m g r a t e f u l t o t h e brew mas te rs of Diamond Breweries ~ i h i t e d ,
Enugu and Premier Breweries Limitad, Onitsha who supp l i ed me with moat
of t h e m a t e r i a l s r equ i r ed i n t h i s work.
I a l s o record my app rec i a t i on t o Messrs. U. Inyang, E. Oliwuosa,
P. Ukoha; C. Nnanna and M i s s Chinyere Okparaocha f o r t h e i r f r i e n d l y
advice and meaningful cont r ib i t ion t o t h i s work. ,
TO t h e members of Chief Alfred Mazi 's family, I am indebted.
E.A. MAZI.
ABSTRACT
The present s t u d i e s were c a r r i e d out t o determine t h e
malting and brewing p o t e n t i a l of "TZSR-YIt v a r i e t y of maize. One
hundred per cent s u b s t i t u t i o n of TZSR-Y maize f o r bar ley malt
yielded a beer with acceptable charac ters . For malting maximum,
0 steeping period was 40 hr. and germination was a t 28-30 C over a
0 4-day period. 'The r e s u l t i n g green malts were k i lned a t 45 C f o r
24 h r with a malting l o s s of 14.14 + 0.1%. Optimum d i a s t a t i c - 0
power of 28 + 3 I.O.B. was obtained a t 4-days of germination. - Nitrogen and p ro te in mean values of 1.89 + 0.07 and 11.81, -
b
r e spec t ive ly , were obtained. Analysis of the wort gave colour,
pH, s p e c i f i c g rav i ty and reducing sugars (96 maltose) mean
values of 9.72 EBC, 5.40, 1032 and 7.6% respectively. The a lcoho l i c
content (3.11 w/v), colour (18.6 EBC) and pH (4.13) of t h e beer
produced from TZSR-Y maize malt were s l i g h t l y lower than t h e
corresponding values f o r bar ley malt beer. However, organoleptic
assessment of the beer showed t h a t 94.17%, 63.2996, 50.77% and
41.00% of t h e judges accepted t h e beer i n terms of colour, foam
s t a b i l i t y , b i t t e r n e s s and f lavour , respect ive ly .
TABLE OF CONTENTS
CHAPTER ONE Page
INTRODUCTION . b . b 1.1 EQUIPMENT MODIFICATION AND PROCESS METHODS
1.1.1 Milling: Operations and Equipment .. 1.1.2 Mashing And Lautering .. . . 1.2 TYPES OF BREWERY RAW MATERIALS . . 1.3 AIMS AND OBJECTIVES OF THE PRESENT STUDY
CHAPTER TWO
2.0 LITERATURE REVIEW . . . . 2.1 TECHNOLOGY OF BREWING .. . . 2.1.1 Milling . . . . 2.1.2 Mashing . . . . 2.1.3 Boiling the Mash . . . 2.1.4 Fermentation . . .d 2.1.5 Maturation b b . . 2.1.6 Packaging . . . .
ORGANOLEPTIC TEST 2.2 * * . . 2.3 MAIZE - AN INTRODUCTION 2.4 MAIZE - BIOCHEMICAL CHARACTERISTICS 2.5 MAIZE IN THE BREWING INDUSTRY . . . . 3 2 CHAPTER THREE
MATERIALS AND METHODS . r . . . . 40 3-1 MATERIALS AND SAMPLE PREPARATION a + . . 40 3 2 PREPARATION OF MEDIA a + . . . . 40 3.2.1 Yeast Extract Peptone Dextrose (YEPD) Broth . . 40
Page
3.2.2 Preparation of Maize Grits . . 3.2.3 Maize Grain Analysis .. . . 3.2.3.1 Moisture Content of Maize ( ~ e a ma=)
3.2.3.2 Germination test and watep relations
3.2.3.3 Water sensitivity . . . . 3.2.3.4 Germination energy . . . . 3.2.3.5 Steeping characteristics . . 3.2.3.6 Malting . of Zea mays . . . . 3.2.3.7 Kilning of Zea mays .. . .
MAIZE MALT ANALYSIS . 4 . Moisture Content of cea mays . . Modification Tests . . . . Malting Loss Determination . . Extract Determination .. . . Cold Water Extract . . . . Diastatic Power Determination . . Total Nitrogen Determination . . Total Fat Determination . . MASHING AND WORT ANALYSIS . . Total Soluble Nitrogen Determination
Permanent Soluble Nitrogen Determination
Index of Modification .. . . Wort Specific Gravity .. . . Wort pH . . . . Wort Colour . . . . Wort Attenuation Limit . . Reducing Sugar Determination . . FERMENTAT ION $ 4 . . Yeast Culturing 4 . . .
Viability Test
Pitching
Lagering
Pasteurization . . . . . . 61 BEER ANALYSIS . . . 62 Beer Colour. pH. and Specific Gravity . . 6 2 Determination of 1% Alcohol By Weight (A.0.A.C. 1980) 62
~etermination of Beer Acidity as 1% Lactic Acid .. 63 Beer Bitterness . . . . . A. 64 Organoleptic Analysis .. . . . . 65 Triangle Test . . . . . . 65
b CHAPTER FOUR
RESULTS AND DISCUSSIONS . 66 MALTING CHARACTERISTICS OF MAIZE .. . . 66 Moisture Control of Unmalted And Malted "TZSR-Ytl Maize 66
Germination Energy And Water Sensitivity . . 6 7 Steeping Characteristics . . . . 68 Malting Loss . . . . . . 68 Extract Determination .. . . . . 71 Cold Water Extract . . . . . . 73 Diastatic Power . . . . . . 73 Total Nitrogen And Crude Protein .. . . 77 Lipid Content . A . . . . 79 WORT CHARACTERISTICS 0. . 80 Total Soluble Nitrogen . . . 80 Permanent Soluble Nitrogen . . . . 80 Index of Modification . r . . . . 81 Wort Specific Gravity . r . i L . 81
Page
Wort pH . . Wort Colour . . Wort Attenuation Limit
Reducing Sugar Determination
BEER ANALYSIS . a Beer Colour . . . L . . Specific Gravity And Alcohol Determination . . Beer Bitterness . . C . . . Beer Acidity . . . b . . SENSORY EVALUATION OF MAIZE BEER . . Triangle Test . . . . Ranking Test . - 4
CHAPTER FIVE
5-0 SUMMARY, RECOMMENDATIONS AND CONCLUSIONS . . 5.1 SUMMARY . . . . . . 5 - 2 RECOMMENDATIONS AND CONCLUSIONS . . . .
REFERENCES
APPENDIX
LIST OF TABLES Page
TABLES
1.
2.
Production of cereal grains in Nigeria .. Composition of common cereal grains on - . percentage dry weight basis . . Characteristics of normal barley malt worts
Characteristics of worts from millet grits and sorghum grits used as malt adjuncts . . Representative range analyses of American lager beer . . . . Characteristics of beer from millet grit and sorghum grits used as malt adjuncts . . Characteristics of beer from sorghum grits and corn grits used as malt adjuncts . . Chemical composition of four varieties of Nigerian maize . . . . Germination energy and water sensitivity of TZSR-Y Variety (% grains germinated) . . Variables tested for and the scores given by the judges for the all maize ("~llma") beer .. Variables tested for and the scores given by the judges for Masters beer . . Variables tested for and the scores given by the judges for Rex beer . . . .
LIST OF FIGURES
FIGURE
Sequence of opera t ions i n beer product ion
Moisture absorpt ion curve f o r TZSR-Y maize a t 28 + ~ O C - . . . . Malting l o s s (%) during days of malting .. Percentage e x t r a c t y i e l d of TZSR-Y maize during malt ing . . . . Cold water e x t r a c t y i e l d of TZSR-Y maize - during malt ing . . . . Changes i n d i a s t a t i c power of TZSR-Y maize during malting . . . Changes i n t h e n i t rogen and crude p r o t e i n content of TZSR-Y maize during malting .. Changes i n temperature of wort during fermentat ion . . . .
0 Changes i n p l a t o of wort during fermentat ion
( x i
Page
CHAPTER ONE
INTRODUCTION
The beer i ndus t ry is one of t h e most important and v i a b l e
i n d u s t r i e s i n Nigeria. I n d u s t r i a l l y , beer i s manufactured from
ba r l ey m a l t which is not produced i n Nigeria and consequently
Nigeria imports a l l t h e ba r l ey m a l t f o r t h e product ion of beer and
r e l a t e d products. The importat ion of t h i s raw ma te r i a l f o r t h e
brewing indus t ry c o n s t i t u t e s a s i z e a b l e d r a i n of Nigerian fore ign
exchange and t h e impor ta t ion is on t h e inc rease following t h e
number and capac i ty of breweries i n t h e country. From theb f igu res
a v a i l a b l e a s a t 15th June, 1987 from t h e Manufacturers Associat ion
of Niger ia (MAN) Beer Sec to ra l Group, t h e t o t a l cu r r en t t h e o r e t i c a l
capac i ty of t h e t h i r t y (30) brewer i e s tkenope ra t ing i n Niger ia is
of t h e o rde r of 18,OO0,OOO ~ ~ / p . a . Although t h e cu r r en t output is
wel l below t h i s f i g u r e , i n o rde r t o meet t he ' huge r a w ma te r i a l demand i n t h e face of t h e c u r r e n t ban on ba r l ey m a l t impor ta t ion ,
e f f o r t s must be made towards s u b s t i t u t i n g wholly o r p a r t i a l l y t h e
imported brewing raw m a t e r i a l s w i th l o c a l l y a v a i l a b l e ones.
m The Federal M i l i t a r y Government has banned t h e impor ta t ion
of malted bar ley i n t o t h e country wi th e f f e c t from January, 1988
and t h e breweries have been d i r e c t e d t o produce and use t h e l o c a l l y
a v a i l a b l e r a w m a t e r i a l s i n t h e i r beer production. One of t h e
reasons f o r t h e ban is t o g ive a s t imulus t o l o c a l a g r i c u l t u r e and
l o c a l i n d u s t r i e s (such as t h e c r e a t i o n of malt ing and enzyme
f a c t o r i e s ) , bo th of which can make a s i g n i f i c a n t con t r ibu t ion
towards reducing unemployment and absorbing su rp luses of manpower
resources throughout t h e federa t ion . The government has been
c o n s i s t e n t l y encouraging breweries t o s t e p up t h e needed backward
i n t e g r a t i o n programme by inves t ing i n l a r g e r s c a l e farms f o r t h e
product ion of g r a i n s , mainly maize and sorghum, which can be used
a s raw m a t e r i a l s i n brewing. Some of t h e breweries have gone (
i n t o d i r e c t product ion of t h e i r r a w ma te r i a l requirements, o t h e r s
have commissioned independent organiza t ions t o f u l f i l t h e s e r o l e s ,
b while a few o t h e r s have do~ne nothing and hope t h a t t h e government
w i l l r eve r se t h i s decis ion. A l l t h e breweries have s tockp i l ed
malted ba r l ey which can l a s t a t t h e b e s t f o r t h e year , but a good
p e r c e n t a ~ e of t h i s s t o r e d malt w i l l be ea t en up by weevi ls con- ., .,
s t i t u t i n g a resource drain. I f maize should succeed as a s u i t a b l e
s u b s t i t u t e f o r ba r l ey , t h e beer i ndus t ry w i l l have a major p a r t
01 i t s problems solved s i n c e maize i s l o c a l l y produced i n commercial
' , q u a n t i t i e s . Comparing t h e 1987 product ion r a t e of ce rea l g r a i n s i n
Nigeria , t h e expected product ion r a t e of maize come 1990 is es t ima ted . a t 7.5 m i l l i o n tonnes able 1). The a v a i l a b i l i t y of maize as
l o c a l r a w ma te r i a l i n brewing may t h e r e f o r e not be a problem.
Beer produced from maike should no t be expected t o have t h e
exac t q u a l i t i e s of bee r from ba r l ey i n terms of co lour , f l avour
and t a s t e f o r a number of reasons. I n pkac t i ca l terms, t h e r e i s
TABLE 1: Production of Cereal Grains i n Nigeria
Cereal Production (mi l l ion tonnea)
1987 - 1990 - .Sorghum 5 945 9.41 Maize 3 043 7.5 M i 1 l e t lk.15 4.82 Rice 1.18 1.75 Wheat 0.057 0.068
Source: Anon, 1986. Proposed programme f o r g ra in and tuber production i n Nigeria b
t o meet human and i n d u s t r i a l uses. Federal Ministry of Agricul ture and Natural Resources, Lagos.
o f t e n a d i f ference between what can be achieved i n iabora tory
o r p i l o t p l an t condit ions and a l a r g e s c a l e commercially
operat ing brewery. Laboratory s c a l e inves t iga t ions of t h e
brewing p o t e n t i a l of maize a r e mostly i n glassware, whose
thermal conduct iv i ty d i f f e r s tremendously from those of t h e
s t a i n l e s s s t e e l o r copper equipment used i n breweries.
Nevertheless, explora tory s t u d i e s such as t h i s have t o commence
a t t h e labora tory inves t iga to ry level .
1:l EQUIPMENT MODIFICATION AND PRUCESS METHODS
The i s s u e of equipnent modif icat ion is r e l a t i v e from one
p l a n t t o another depending on t h e na ture of t h e o r i g i n a l p l an t
installed. The cost of changing equipment may be so tre-
mendous that breweries may be discouraged from changing to
another cereal. For the equipment modification, whether it
is partial or full replacement of barley malt, three main
operations are affected by this exercise: Milling, Mashing
and Lautering .
This involves size reduction and particle size control
b or screening to produce ground malt. For dry milling opera-
tion, rollor mills are conventionally used. The roller mills
provide a combination of compressive and shear forces for
size reduction. The mills are designed to:
(a) breakdown the grits to an intermediate
sCze so that the solubles can be rapidly
extracted;
( b ) prevent colloidal or cloudy solutions
durin~ mashing ;
( c ) oper~te at economic cost.
Generally, all grinding machines use one or more
cornmunition forces to reduce the size of the materials. Such
forces are compression, impact, attrition and shear forces.
1.1.2 Mashing And Lauter ing
The sepa ra t ion of t h e l i q u i d e x t r a c t from t h e in so lub le
p o r t i o n (spent g r a i n ) o f t h e brewing mash h a s been a d i f f i c u l t
and expensive s t e p i n t h e brewing process. Many types o f #
equipments have been used t o achieve t h i s . These inc lude
mash f i l t e r s , l a u t e r t u r n s , c e n t r i f u g e s of many types and
t h e s t r a i n m a s t e r . Njoku (1987) p o i n t s ou t t h a t mash f i l t r a -
t i o n ie t h e sum of two d i r e c t l y opposed func t ions . On t h e
one hand, t h e r a t e of f i l t r a t i o n i a d i r e c t l y r e l a t e d t o t h e
square of the p a r t i c l e size and is inve ree ly p ropor t io rh l t o
t h e depth of t h e mash bed, On t h e o t h e r hand, leaching
e f f i c i e n c y inc reases wi th bed depth but is inve r se ly r e l a t e d
t o t h e p a r t i c l e size. The mash f i l t e r a l lows t h e use of more
f i n e l y ground m a t e r i a l s than any o t h e r e s t a b l i s h e d system such
as t h e mash tun , 1auke r . t un and s t r a i n master. Thus, f o r
breweries t h a t have dry r o l l e r m i l l s , a mash f i l t e r might be
r equ i r ed i n s t e a d of a convent ional l a u t e r t un t o permit t h e
use o f much f i n e r g r i t s .
1.2 TYPES OF BREWERY RAW MATERIALS
The primary raw m a t e r i a l s f o r t h e brewing indus t ry a r e
h r l e y m a l t , hops, y e a s t , and w a t e r , whi le t h e a u x i l i a r y raw
m a t e r i a l s a r e ad junc t s , enzymes, chemicals and packaging
ma te r i a l s . Barley m a l t , is produced by a r t i j i c i a l s t e e p l ~ ~ g
and germination of ba r l ey g r a i n , followed by drying ( k i l n i n g ) .
A l l t h e primary r a w mater'ials have h i t h e r t o been imported f r e e l y
i n t o t h e country with t h e r e s u l t t h a t t h e brewery set-up i n t h e #
country is t a i l o r e d t o t h e use of such r a w mater ia l s .
The brewing water ( l i q u o r ) i s very important. Since t h e a v a i l -
a b i l i t y of a s u i t a b l e brewing water holds a high p r i o r i t y i n t h e
list of f a c t o r s considered i n s i t i n g a brewing industry. A good
q u a l i t y water supply out-ranks t h e importance of a v a i l a b i l i t y of
e l e c t r i c power. The water should meet t h e s t a n d a r d s f o r potablb
water >which inc lude t h e types of i o n s ;
and t o x i c i o n s must be kept o u t ; t h e hardness which may be temporary
o r permanent. Water with a high permanent hardness i s a s soc ia t ed
with f f b i t t e r l beer while water with low calcium sulphate and high
calcium bicarbonate is used i n brewing sweeter darker beers. Thus,
t h e des i r ed hardness of water f o r brewing depends on t h e type of
beer t h e brewer in t ends t o produce.
The p r i n c i p a l biochemical process i n t h e product ion of
, a l coho l i cbeve rages i s t h e catabolism by s t r a i n s of Saccharomyces
ce rev i s i ae a n d S . ca r l sba rgens i s of simple sugars t o y i e l d a mixture
of ethanol and carbon dioxide. I n the case of beer product ion, t h e
polyaaccharides such a s s t a r c h and c e l l u l o s e cannot be fermented
d i r e c t l y by yeas t and must be hydrolysed t o y i e l d fermentable sugars
during mashing through enzymic reac t ions . Yeasts used f o r brewing
have been d i f f e r e n t i a t e d i n t o t op and bottom yeas t s . Top y e a s t s
are vigorous fe rmenters a c t i n g b e s t a t r e l a t i v e l y h igh tempera-
t u r e s , ( 2 0 ~ ~ 1 . They are used i n brewing heavy b e e r s of high
a l c o h o l i c conten t . I n c o n t r a s t , bottom y e a s t s a r e slow fe rmenters
0 0 a c t i n g b e s t a t about 12 C t o 15 C. They produce l i g h t e r bee r s
of low a l c o h o l i c conten t .
D i f f e r e n t c e r e a l m a l t s produce d i f f e r e n t t ypes of high
molecular weight po lypept ides which a r e t h e major a c t i v e components . r e spons ib l e f o r beer p r o p e r t i e s . Whole maize o r r i c e con ta in s
b r e l a t i v e l y l a r g e r amounts o f l i p i d s which reduce foam s t a b i l i t y
and produce r a n c i d o f f - f l avour i n beer . Tas te t e s t s o f samples
of beer us ing cassava products as 50-7@$~ of t h e g r i t s wi th malt
revea led t h a t t h e samples had c h a r a c t e r i s t i c o f f - f l avour and a l s o
h igh d i a c e t y l c o n t e n t s and a very h igh co lour (Hug and
Pfenninger , 1980)- From t h e foregoing , it becomes obvious t h a t
t h e o rgano lep t i c q u a l i t i e s , namely, aroma and f l avour o f beer vary
from one r a w m a t e r i a l t o t h e o the r . The problem, t h e r e f o r e , i s
t h a t o f b i a s a g a i n s t p roducts made from l o c a l r a w ma te r i a l s .
A s every brewery produces t o sell , it w i l l r e q u i r e a massive
investment on sales promotion and educa t ion o f t h e customers t o
be a b l e t o e f f e c t i v e l y push t h e non-barley m a l t beer i n t o t h e
market. The degree o f success i n so lv ing a l l t he se problems w i l l
be an indicator of whether the brewing and bottling industries
will continue to survive in this country. However, it is believed
that with time, the products from research on local sourcing of
raw materials for the breweries will fit into the system and beer
produced from it consumed as the normal beer from barley.
The predominant factors in selecting a cereal for use in a
particular brewery are availability, cost and behaviour of the
starch, proteins, lipids and mineral fractions. A cereal like maize
(~ea mays), grown extensively in all the twenty-one states of $he
federation, certainly provides a cheaper form of brewing fermentables.
Hough -- et al. (1981) reported the percentage composition of maize and other cereals on dry weight basis as shown in Table 2.
Maize, sorghum and rice are grown in commercial quantity in
Nigeria. Rice has the greatest potential for use as a brewing material
but the volume of production of rice falls short of its demand as
foodstuff. Sorghum ranks higher than maize for use as a brewing
material because of its low lipid and protein contents.
Okafor and Aniche ( 1980) amongst others have successfully
brewed lager beer from sorghum malt using already established mashing
conditions for barley malt, namely, the three state decoction
method.
TABLE 2: $omgosition of Common Cereal Grains on Percentage Dry Weight Bas is
Source: Hough, J.S., Rriggs, D.E., Stevens, R. and Young, T. (1981). Malting and Brewing Science vol.1. Chapman and Hall, London p.225
Cereal
Barley Sorghum Maize Rice Wheat Rye
Considering t h e r e l a t i o n s h i p between sorghum and maize, it
i s p o s s i b l e t h a t with t h e same t rea tments as f o r ba r l ey o r
sorghum, beer can be s u c c e s s f u l l y brewed wi th maize and t h e
CellulOse f i b r e
5 -7 2-3 4.2
2-3 2 - 9 2.4
bee r acceptab le .
Carbohydrate
71.0 70.7 70.0 81.0
7 6- 0 74 .O
AIMS AND ODJECTIVES OF THE PRESENT STUDY
Ash
3.1 2.1 1.2 0.4 2.2 2.4
b
Pro te in
11.80 10.7 11.6 9.0 14.5 13.5
The purpose o f t h i s s tudy i s t o eva lua t e t h e s u i t a b i l i t y
Fa t
2.50
3 -0 5 8 0.5 2.0 2.0
of maize - a prominent Nigerian c e r e a l - a s a s u b s t i t u t e f o r imported ba r l ey on which Nigeria beer product ion depends. It
is convenient ly grown twice a year which, wi th proper handl ing,
would ensure good s G p p l y and a v a i l a b i l i t y wi th reduct ion i n
bulk storage c o s t s . T h i s work e n t a i l s production of a s a t i s -
factory beer from maize and comparative analysis o f the product
with beer brewed from barley m a l t .
CHAPTER TWO
2.0 LITERATURE REVIEW
2.1 TECHNOLOGY OF BREWING
The opera t ions involved i n brewing include Malting,
Kilning, Mil l ing , Mashing, Wort boi l ing and cooling, f e r -
mentation, Maturation and Packaging.
Bass and Cayle (1975) gave a schematic representa t ion
of a t y p i c a l beer production a s shown i n Figure 1. There i s
f i r s t a con t ro l l ed germination of t h e bar ley grain. This b
general ly i s not operated a s p a r t of t h e brewery. The main
ob jec t ive is t o produce enzymes which a c t e i t h e r during malting
o r l a t e r , t o hydrolyse polymerized reserve mate r i a l s of t h e
gra in and so allow t h e ex t rac t ion of fermentable sugars and
amino acids. There a r e a l s o changes i n g ra in t e x t u r e which
accompany malting. The enzyme a c t i o n i s a r r e s t e d by k i l n
drying. The a c t i v i t y of hydro ly t i c enzymes continues during
t h e e a r l y s t ages of k i ln ing so long a s t h e g ra in i s moist,
with t h e production of amino a c i d s and reducing sugars which
can condense t o y i e l d an assortment of colonised compounds of
c h a r a c t e r i s t i c aroma.
Figure 1: Sequence of Operat ions i n Beer Product ion
Malt Bin
M a 1 t Grinding
Malt Mash
1 F i l t r a t i o n
Cerea l Bin
Cerea l Cooker
Vessel
( l a u t e r t u n o r mash f i l t e r )
Wort b o i l i n g ( k e t t l e )
Wort cool ing
Brewer's y e a s t
Fermentation
1 S t o r a t e ( l age r ing )
Fin ish ing ope ra t i ons ( c h i l l -p roof i n g )
F i n a l f i l t r a t i o n
Packaging (kegs, b o t t l e s o r cans)
Source: Bass, E.J. and Cayle, T. (1975). "The brewing process". Food Science and Technology (A series of monographs) Academic p r e s s p.455-4581
2.1.1 Mi l l ing
Malted ba r l ey is c a r e f u l l y ground i n a m i l l i n such a
way t h a t t h e husk of t h e g r a i n is l e f t s u b s t a n t i a l l y i n t a c t
while t h e r e s t becomes a coarse powder. hef finer t h e g r ind
t h e more r a p i d enzymic d iges t ion and e x t r a c t i o n with hot
water during mashing. I n wet mi l l i ng , designed t o inc rease
t h e e x t r a c t p o t e n t i a l and wort drainage p r o p e r t i e s of m a l t s ,
t h e m a l t s may be condit ioned wi th steam t o reduce s h a t t e r i n g
of t h e husk and endosperm during mi l l i ng o r malt ing may be b
soaked i n water t o r a i s e i ts moisture t o about 25-304/a. The
m a l t is then mi l l ed wi th s p e c i a l l y pa t t e rned r o l l e r s a t high
speed. Lauter ing problems a r e o f t e n envisaged wi th f i n e
g r inds where l a u t e r t ubs a r e used, bu t t h e in t roduc t ion of
mash f i l t e r s has given a s a t i s f a c t o r y f i l t r a t i o n with maximum
e x t r a c t r e a l i s a t i o n i n l imi t ed run-off time.
2.1.2 Mashing
Mashing involves t h e mixing of ground m a l t wi th w a r m
0 water a t 38-50 C and t h i s enables many i n t e r r e l a t e d chemical
and phys ica l changes t o begin and proceed simultaneously.
Several methods of mashing a r e known and these include in fus ion
mashing, decoct ion mashing, double mashing and temperature
programme mashing. Whatever method adopted, t h e ob jec t ives
of mashing remain t h e same; t h a t is, t o d i s so lve t h e substances
and t h e ingred ien t s t h a t a r e immediately so luble which c o n s t i t u t e
only about 10-15% of t h e t o t a l weight of t h e ingred ien t s ( ~ o u ~ h e r t y ,
1979); t o render so luble through enzymic a c t i o n polymers such a s
p ro te ins , nucle ic a c i d s and carbohydrates which a r e insoluble i n
I .
the i rnat t i rFl s t a t e ; t o change t h e chemical s t r u c t u r e , through
enzymic ac t ion , of some of t h e cons t i tuen t substances i n planned and
p red ic tab le manner. The mashing method adopted by any brewery i s
d i c t a t e d by t h e opportunity t o u t i l i z e t h e advantages afforded by
a p a r t i c u l a r ingredient material . The product of t h e mashing is
c a l l e d wort. B
Several workers, Pierce and Woof (1966); Anderson (1966) and
Harr is et & (1955) have shown wort t o conta in simple sugars, more
complex polysaccharides, amino ac ids , pept ides , p ro te ins , o the r
nitrogenous mate r i a l s , vitamins, organic and inorganic phosphates,
mineral s a l t s , polyphenols, precursors and tannins , small q u a n t i t i e s
of l i p i d s and many other minor components many of which have not
y e t been i d e n t i f i e d . Harr is (1962) and Hopkins and Krause (1947)
observed t h a t t h e enzyme complement c o n t r i b ~ t e d t o t h e mash by t h e
malt ; and v a r i a t i o n s i n t h e mashing temperature, durat ion of mashing,
and t h e pH of t h e mash, a l l a l t e r t h e composition of the f i n a l
wort: t he main enzymes involved during mashing a r e phosphatases,
carbohydrases, and proteases.
Infus ion mashing, r equ i res t h i c k mashes - a r a t i o of 2.7 l i t r e s 0 of l iquor pe r kg of t h e g r i t ; a mashing i n temperature of about 63 C
\ \
(optimum f o r /-amylase a c t i v i t y ) and r a i s e d through 6 8 O ~ t o 70°c
( ~ o u ~ h e t al , , 1981)- A pH range of the in fus ion method uses
t h e enzymes of the m a l t a lone f o r t h e d i s so lu t ion and degradation
of s t a r c h and prote ins . This method is inexpensive, but very
dependent on t h e q u a l i t y of t h e r a w ma te r i a l s ; only t h e bes t r a w
ma te r i a l s can be used f o r t h i s process and i ts y i e l d is lower than
t h a t of t h e decoction process'
I n decoction mashing l i g h t l y k i lned and high d i a s t a t i c malts
a r e used t o ensure p r o t e o l y t i c a c t i v i t y and t h e amylolyt ic degra-
da t ion of s t a r c h ad junc t s o f t e n mixed with the m a > t g r i s t . T ~ C
g r i s t . t o l i quor r a t i o of 4 l i t r e s per kg and mashing-in temperature
of 35-40°c ensure a b e t t e r degradation of -glucans. The
0 0 temperature i s r a i s e d by decoction through 50 C t o 63 C @-amylase
0 a c t i v i t y ) and then f i n a l l y t o 70 C H-amylase a c t i v i t y ) . Hough
0 eta, (1981) repor ted t h a t s t a r c h degradat ion i s optimal a t 50 C
with pH range 4.9 - 5.3; a t 60°c with pH range of ) 5 . l t o 5.5 and 0
a t 65 C with pH range 0 f ~ 5 . 5 t o 5.9.
The double mash system is the s i n g l e most widely used
mashing method i n North America. This system u t i l i z e s the ce rea l
cooker i n which t h e s t a rchy adjuncts a r e ge la t in i zed by boi l ing .
The ge la t in i zed s t a rchy adjunct is then pumped i n t o a mash mixer
( t u b o r tun) i n which t h e malt mash is prepared then t h e two mashes 9
0 0 a r e in t ima te ly mixed. Mashing-in temperature is 38 C t o 50 C
( ~ e p t o n i z i n g r e s t ) t o ensure t h a t t h e m a l t i s thoroughly soaked
t o l i b e r a t e and a c t i v a t e the malt enzymes. Dougherty (1979)
recommended a liquor/malt r a t i o of 3.866 l i t r e s per kg. The
0 0 temperature i s r a i s e d through 65 C t o 70 C with r e s t i n g time of
30 minutes at each temperature.
The sweet wort obtained a f t e r mashing i s b io log ica l ly and
biochemically unstable. Harr is (1962) and Hopkins and Krauss (1947)
observed t h a t nitrogenous mate r i a l s account f o r 5.6% of t h e wort
s o l i d s , and t h a t they a r e equiYalent t o some 30-40% of t h e t o t a l
nitrogenous mater ia l found i n t h e malt. Ninety-four per cent of
b t h e t o t a l so luble ni trogen (T.S.N) i s taken t o be permanently
so luble (P.s.N), t h a t i s , i t i s not coagulated and p rec ip i t a t ed
when wort i s boiled. The t o t a l so luble n i t rogen f r a c t i o n of wort
contains the bas ic ma te r i a l s choline and ammonia, together with
amino ac ids , p ro l ine , pept ides of varying complexity, p r o t e i n s ,
vitamins, purine and pyrimidine bases and t h e i r nucleosides and
deoxynucleosides. The higher molecular weight f r a c t i o n s , p ro te ins ,
polypeptides have been var ious ly separated by f r a c t i o n a l prec i -
p i t a t i o n s with tannin and inorganic s a l t s . The presence of l a r g e r
q u a n t i t i e s of high molecular weight mater ia ls , r e f l e c t i n g inadequate
p ro teo lys i s i n t h e mash, may contr ibute t o haze formation i n the
beer. In t h i s respect , p ro te ins and pept ides , together with
polyphenols a r e t h e major c o n s t i t u e n t s of the most important s o r t
of beer - haze, pept ides and p ro te ins have been implicated i n producing " p a l a t e f u l n e s ~ ~ ~ and improving head re tent ion . They
- 17- probably bring about these e f f e c t s by lowering surface tens ion,
increasing v i scos i ty and forming f i lm on the surfaces of gas
bubbles, thus s t a b i l i z i n g foam. Various a c i d i c ma te r i a l s , of non-
phenolic na ture including f r e e 5 a t t y a c i d s a r e leached i n t o wort.
Ayrapa e t a l . (19613 have shown malt wort t o contain f r e e
f a t t y ac ids , mainly pa lmi t i c ac id , and a l s o t h e unsaturated a c i d s ,
o l e i c , l i n o l e i c and a l i t t l e lonolenic. Grouped according t o
t h e i r chain-lengths, t h e q u a n t i t i e s of f a t t y a c i d s have (C -C 1, 4 10
Edward and Thompson (1968) and Rinke (1965) have shown t h a t
wort conta ins minor proport ions of l i p i d s usual ly l e s s than 2%
of the t o t a l o r i g i n a l l y present i n the g r i s t . The ac tua l q u a n t i t i e s
ex t rac ted vary with the means of f i l t r a t i o n and sparging. Rapid
l au te r ing techniques y i e l d worts with enhanced l i p i d content.
F i l t e r i n g through Kieselghur reduces the l e v e l s of f a t s . Centr i-
fugation of sweet wort has been used experimentally t o separa te
malt f a t , e s p e c i a l l y t r i g l y c e r i d e s about 0.7 mg/l i t re . The beer
brewed from the ttdefattedtt wort had improved head c h a r a c t e r i s t i c s .
Conversely, the add i t ion of e x t r a m a l t l i p i d s t o wort reduced
the foaming q u a l i t y of beer. Lipids present i n unhopped worts
(mg/l i t re) a r e t r i g l y c e r i d e s 5-8; d ig lycer ides , 0.2-0.5; mono-
glycerides, 1.6 -1.8; s t e r o l e s t e r s , 0.1-0.2 and f r e e s t e r o l s ,
0.2-0.4. Some of these compounds may have organoleptic proper t ies
of importance t o beer character .
2.1.3 Boiling t h e Mash
The wort is then boi led with hop i n order t o destroy
and i n a c t i v a t e any enzyme which survives t h e sparging of
t h e mash; p r a c t i c a l l y s t e r i l i z e t h e wort; concentrate t h e
wort; coagulate and p r e c i p i t a t e p ro te ins ; isomerize t h e hop
alpha ac ids ; and v o l a t a l i z e and remove unwanted f lavour
components ( ~ a c l e o d , 1977). Hopping r a t e may d i f f e r from
one brewery t o t h e other . The recommendations of t h e
American Society of Brewing Chemists i s 0.65% of t h e t o t a l b
weight of malt (A.s.B.c., 19581, while a hopping r a t e of
140 - 210 g pe r h e c t o l i t r e of wort i s recommended by Hough e t a 1 (1981). A boi l ing per iod of two hours is most adequate -- ( ~ u d s t o n , 1979). The substances ex t rac ted from hops include
b i t t e r a c i d s and r e s i n s , e s s e n t i a l o i l , and tannin. Dhamijah
and Singh (1978) on a laboratory s c a l e b a s i s autoclaved t h e
hopped wort a t 516 pressure f o r 30 min t o obta in a c l e a r wort.
The composition of t h e wort determines t h e p roper t i e s of
t h e f in i shed beer. The wort must contain t h e r i g h t amount of
fermentable sugars, yeas t n u t r i e n t s , and f lavour compounds.
The f in i shed wort i s o f t en analysed t o ensure t h a t t h e beer
w i l l have the des i red s t r eng th , colour, f lavour , and foam
head. Some of t h e parameters rou t ine ly determined i n a
brewery wort and t h e i r range of values have been ou t l ined
by Meclgoard (1976) as i n Table 3.
-19-
Table 3. Characteristics of Normal Barlet Malt Worts
Physicochemical characters
Uni t s
Extract (op)
pH
Colour
Total protein
Source: Maclgoard, M. (1976): Wort composition with b
special reference to the use of adjuncts. M.B.A.A., Tech. Quart a, 78-79.
Dhamijah and Singh (1978) in their brewing studies with
millet and sorghum grits as adjuncts in lager beer production
gave the wort composition as in Table 4. The malt/adjunct ratio
for sorghum was 65:35 while that of millet was 75:25.
Table 4: Charac te r i s t i c s of Worts from Mi l l e t G r i t s and Sorghum G r i t s Used a s Malt .Adjuncts
Barley malt Barley Malt Physicochemical Mi l l e t G r i t s Sorghum g r i t s charac ters
(75:25) (65:35)
Extrac t (op) 7 93 8d36
Reducing Sugars ( a s maltose %) 6.16 74 66
Prote in (% by weight) 0.38 0.37 I '
Tota l a c i d i t y 0.08 0.09
4
Source: Dhamijah, S.S., and Singh, D.P. (1978). Adjuncts i n brewing 1. Bajra and Sorghum. J. Food Sc. Techno1 197-201.
2.1.4 Fermentation
The yeas t s t r a i n employed i n any brewery fermentation
d i c t a t e s t h e type of beer. A l l l age r beers a r e produced with
the use of bottom yeas t - Saccharomvces ca r l sbe raens i s while a l e i s obtained wi th a top yeas t - Saccharomyces cerevis iae .
0 The bottom yeas t s ferment worts a t temperatures between 9 C
0 and 12 C while t h e top yeas t s ferment a t higher temperatures
between 1 5 O ~ and 20°c ( ~ n u d s e n , 1979). Dhami jah and Singh ( 1978)
0 fermented t h e i r worts a t 17 C f o r 12 - 15 days. The p i tching
r a t e s of 3 g f r e s h weight of yeas t pe r l i t re of wort i s
-21-
recommended by Hough et &. (1982). A s t h e fermentation proceeds,
various substances accumulate on the surface of t h e medium,
including hop r e s i n s , yeas t c e l l s , and proteinaceous mater ia l .
This scum may be removed a f t e r t h e fermentation starts t o
recede, i n order t o improve the q u a l i t y of t h e beer. Cer ta in
very d e f i n i t e changes take p lace i n t h e wort during fermentation.
A t a p a r t i c u l a r point near the end of t h e fermentation t h e
yeast f l o c c u l a t e s and commences t o s e t t l e . A l a rge proport ion ,
of the fermentable s u g a r s ! i s 1 transformed t o e t h y l alcohol , 0
carbon dioxide, g lyce ro l , and a c e t i c acid.
2.1.5 Maturation
The product which comes from t h e fermentors, now known
as I1beerfI conta ins undesirable substances i n suspension. It
0 is s to red at a temperature of about 0 C f o r 30 days i n order
t o permit t h e uns table p ro te ins , yeas t , r e s i n , and o the r
undesirable ma te r i a l s t o p r e c i p i t a t e . During t h e s torage per iod ,
t h e beer matures, e s t e r s a r e formed, and t h e harshness of the
green product disappears. The malt beverage is usual ly
chi l lproofed by t h e use of spec ia l enzymes. This procedure
removes those p ro te ins which would tend t o ' p r e c i p i t a t e out a t
t h e lower temperatures and cause a haze,
i 2.1.6 Packaging
The matured beer is carbonated under pressure , using
carbon dioxide t h a t is at l e a s t 99.5% pure, u n t i l a f i n a l
carbon dioxide content of 0.45 t o 0.52% is obtaiiied. The
dissolved gas adds t o the q u a l i t y of the beer , a i d s i n t h e
production and r e t e n t i o n of foam, and helps t o preserve t h e
beer. Bo t t l e s a r e washed, automatical ly f i l l e d , capped,
0 r insed with potable water, and pasteurized at 60 C f o r 30
min. B o t t l e s a r e inspected f o r defec ts , sometimes by
b e lec t ron ic devices, l a b e l l e d , . and packed i n shipping cases.
The fermented and matured beer composition has been
repor ted by many workers. Hough e t al. (1981) gave t h e range
of r ep resen ta t ive analyses of American l age r beer as i n Table 5.
Table 5: Representative Range Analyses of American Lager Beer
Physico,chemical Units
cha rac te r s
Original e x t r a c t (op) 7.5 - 11.2 Apparent e x t r a c t % 1.5 - 3.3 Apparent a t t enua t ion % 68 - 82 Alcohol (% v/v) 2.8 - 4.4 Reducing sugars (% maltose) 0.8 - 145 Colour (E.B.C u n i t s ) 5 3 Prote in (N x 6.25%) 0.25 - 0.4
Source: Hough, S.S., Briggs, D.E., Stevens, R. and Young, T.W. ( 1981) : Malting and Brewing Science vol.1, Chapman and H a l l , London.
In their work on the use of sorghum and millet grits as
adjuncts in brewing, Dhamijah and Singh (1978) gave the analyses
of beer produced from 65% malt and 35% sorghum; and that from 75%
malt and 25% millet (~ajra) as in Table 6. The beer samples
obtained were reported to have compared favourably with all malt.
Table 6: Characteristics of Beer from Millet Grits and Sorghum Grits Used as Malt Adjuncts
Physicochemical characters
Barley malt Barley malt b
Millet grits sorghum grits (75:25) (65:35)
Apparent extract ( op ) l,9l 2.19
Colour (E.B.c) 8608 4.86
Reducing sugars (% maltose) 0.93 0.94
Protein % 0.31 0.19 Alcohol % by weight 2.17 2.47
Source: Dhami jah, S.S., and Singh, D.P. (1978). Adjuncts in brewing I. Bajra and Sorghum* J. Food Sc. Techno1 I& 197-210.
Stewart and Hahn (1965) on their work on sorghum Brewers
grits in the brewing of lager beer recorded the composition of the 1
beer produced from 6096 malt and 4096 sorghum and corn grits as
in Table 7. The beers were found to be both chemically and
analytically compadable to their control.
Table 7: Characteristics of Beer From Sorghum Grits and Corn Grits Used as Malt Adjuncts
Physicochemical characters
Barlet malt Barley malt Sorghum grits Corn grits (60:40) (60:40)
Apparent extract (op) 2.12 2.1
Real extract 96 3 76 4.0 ~lcohol (96 by weight) 3-65 4.22 Acidity (as 96 lactic acid) 0.14 0.14
Source: Stewart, E.D. and Hahn, R.H. (1965). Sorghum brewers grit in brewing of lager beer. American Brewer July, 21-26.
2.2 ORGANOLEI'TIC TEST
Sensory t e s t i n g is concerned wi th measuring physical p r o p e r t i e s
by phys io logica l techniques. It encompasses t h e eva lua t ion of
appearance, odour (aroma), t a s t e and t e x t u r e of food n ja te r ia l s by
human subjec ts . I n t h e beer indus t ry , f l avour is without douht, t h e
most important a t t r i b u t e and t h e r e is an abso lu te need f o r
respons ib le t a s t e t e s t i n g . Comption(l979) i n h i s work on Beer
q u a l i t y and t a s t a methodology pointed ou t t h a t t h e consumers
r e a c t i o n t o t h e brewers product is t h e f i n a l cour t of appeal,. A
good sensory eva lua t ion of brewery product is therofore p i v o t a l
i n t h e product ion and marketzng of beer i n t h e l i g h t of t he f a c t
t h a t a wrong sensory assessment of any batch of beer may t a r n i s h
t h e q u a l i t y image of t h e company t o Lhe e x t e n t t h a t much revenue
and time w i l l be expended before t h e image is redeemed.
Sensory t e s t i n g is divided i n t o two general ca tegor ies : -
ob jec t ive t e s t s and s u b j e c t i v e t e s t s . Object ive t e s t s include:
( i ) Difference t e s t i n g - This kind of t e s t is reqyi red when i t is e s s e n t i a l t o determine whether o r not t h e
sample is d i f f e r e n t from e i t h e r a con t ro l o r another
sample. This method can be app l i ed when t h e r e i s
ing red ien t change, i ng red ien t s u b s t i t u t i o n , sub-
s t i t u t i o n imi t a t ion product f o r n a t u r a l products
(Statil and E ins t e in , 1973). Difference t e s t i n g is
most frequently conducted using t r i a n g l e o r pa i r ed
comparison techniques.
( i i ) Descript ive t e s t i n g - This i s used t o analyse samples once they a r e shown t o be d i f f e ren t .
( i i i ) I n t e n s i t y t e s t - This compares t h e r e l a t i v e s t r eng th (aroma o r t a s t e ) , hea t l e v e l s o r ol;iirr a t t r i b u t e s
of two o r more samples which a r e known t o be
d i f f e r e n t . Rating and Ranking techniques a r e
genera l ly used i n t h i s t e s t i n g .
b Subject ive o r a f f e c t i v e t e s t i n g involves t h e evalua t ion of
preference o r accep tab i l i ty . Here, personal l i k e s and d i s l i k e s of
t h e sub jec t s f o r t h e product under t e s t a r e measured. Preference
o r a c c e p t a b i l i t y t e s t s a r e usua l ly conducted by Hedonic Scale
technique (A.S.T.M., 1969).
2 - 3 MAIZE - AN INTRODUCTION
Maize ( ~ e a mays), one of t h e most important food crops i n
Nigeria , i s widely grown i n t h e southern p a r t s of t h e country.
However, the t o t a l hectarage devoted t o t h e production of t h i s crop
annually i n t h e northern s t a t e s i s f a s t becoming s i g n i f i c a n t . I t
i l l t he t h i r d most widely c u l t i v a t e d c e r e a l crop i n Nigeria.
It accounts f o r about 13% of c e r e a l harves t and between 80
and 900b of t h e t o t a l c e r e a l consumed i n Nigeria and some o the r <
t r o p i c a l coun t r i e s ( ~ l a t u n j i & g., 1980; Ekpeyong , 1980).
Consumption is i n various processed forms such a s roas t ing ,
boi l ing , o r fermentation ( ~ a n i g o and Muller, 1972). A common
form of consumption of maize i n Nigeria i s a s ogi - a Nigerian
fermented cereal porridge.
Oyabiodun e t al. (1982) reported t h a t maize has long been
recognised a s a good source of u t i l i z a b l e carbohydrates i n human
d i e t s and i s a l s o an important energy contributing ingredient
i n d i e t s f o r p igs and poultry. B
2.4 MAIZE - BIOCHEMICAL CHARACTERISTICS
A t y p i c a l proximate ana lys i s of dr ied maize gave dry
matter , carbohydrate, prote in , e t h e r e x t r a c t , crude f i b r e , ash
and food energy values of 90.38, 82.55, 9.5, 4.3, 1.32, 1.2
and 410 c a l o r i e s , respect ively ( ~ k e , 1967).
Ihekoronye and Ngoddy ( 1985 compared t h e chemical composition
of four v a r i e t i e s of Nigerian maize and reported t h a t the prote in ,
ash and o i l contents of t h e . d i f f e r e n t v a r i e t i e s were s imi lar . The
t a b l e below shows the proximate analyses.
TABLE 8 ; Chemical Composition of Four V a r i e t i e s of Nigerian Maize
V a r i e t i e s
White, l o c a l farmers v a r i e t y
Yellow, farmers v a r i e t y
FARZ-24 Var ie ty
c e r e a l s . Cereal Chem 42, 299-302
O i l ( e t h e r e x t r a c t )
(%
Bressani and Rios (1962) e s t a b l i s h e d t h a t t h e chemical compositit n
of maize can be inf luenced g e n e t i c a l l y o r by v a r i a t i o n s i n s o i l
n u t r i e n t l eve l s . Maize has a lower n u t r i t i v e va lue than wheat, and
is d e f i c i e n t i n t h e vi tamin n i a c i n ( n i c o t i n i c a c i d ) and having a
r e l a t i v e l y low content of , p ro t e in ( ~ e i n ) which i s d e f i c i e n t i n 1.ysine
and tryptophan. However, maize g l u t e l i n , a n o t h e r f r a c t i o n of maize
p r o t e i n i s complete i n e s s e n t i a l amino ac ids . The d i sease
Pe l l ag ra i s p reva len t among peoples who r e l y on maize f o r longer
propor t ion of t h e i r d a i l y food. I n o rde r t o make maize products
s a t i s f a c t o r y a s a main d i e t a r y item, t h e a d d i t i o n of l y s i n e ,
t ryptophan, vi tamin B, n i a c i n and r i b o f l a v i n would be des i r ab l e .
Maize seeds con ta in a u se fu l concent ra t ion of vi tamin B o r thiamin
and yellow maize con ta ins p - c a r o t e n e , a precursor of vi tamin A
(Kent, 1976).
Bressaniand Mertz (1975) s t u d i e d t h e e f f e c t of geminat ion on t h e
protein ~ o n t a n t of maize and found out t h a t during t h e g e m i n a t i o n
of normal maize, i nc reases i n t h e concent ra t ion of l y s i n e and t ryptophan
and decreases i n t h e p r o t e i n z e i n occur. And they su6gested t h a t
g e m i n a t i o n may thus o f f e r a method f o r convert ing n u t r i t i o n a l l y
poor q u a l i t y p l a n t p r o t e i n t o a h igher q u a l i t y f o r human and animal
w e .
Waber (1978) e x t r a c t e d t h e l i p i d components of maize wi th
chloroform-methanol. H e f r a c t i o n a t e a t h e e x t r a c t on a s i l i l i c a c i d b
column and i d e n t i f i e d t h e components by t h i n l a y e r and gas l i q l ~ i c l
chromatography. They found t h a t t h e maize o i l i s a high q u a l i t y
food o i l conta in ing 6CY)lo of polyunsaturated f a t t y ac ids . Maize o i l
t y p i c a l l y con ta ins about 8VA t r i g l y c e r i d e s , 4% monoglycerides and
d ig lyce r ides , /&I s t e r o l s , 3% ,hydrocarbons - s t e r o l esters, l"/ofre
f a t t y a c i d s and 9$1 po la r l i p i d s , mainly phospholipids and glyco-
l i p i d s . Phosphat idyl chol ine forms over 600/o of t h e t o t a l phospho-
l i p i d s . The l i p i d composition p a r t i c u l a r l y wi th regard t o t h e
g lyce r ides and phospholipids appears t o be s t rong ly va r i e ty -
dependent w h i l s t t h e germ has by f a r t h e h igher concent ra t ion of
o i l of any p a r t of t h e maize p lan t . The next r i c h e s t p a r t is t h e
leaves.
Hug and Pfenninger (1976) compared t h e b a s i c compositions of m a i ze ,
ba r l ey and r i c e , and found out t h a t maizc con ta ins rrlore s t a r c h and
l i p i d than ba r l ey but l e s s pro te in . The p r o t e i n d i s t r i b u t i o n was
a l s o found t o be d i f f e r e n t with cons iderably more prolamine and
g l u t e l i n but l e s s albumin and g lobu l in being present i n maize.
Twice as much l i p i d was found i n maize a s i n ba r l ey with t h e *
unsa tura ted f a t t y a c i d s , l i n o l e i c and o l e i c a c i d s being t h e major
cons t i t uen t s . Over 80q/o of t h e l i p i d i s loca t ed i n t h e enibryo of
f r e s h l y harves ted maize but during tora age, migrat ion t a k e s p lace
t o t h e endoupuirn which a f t e r 18 months is found t o con ta in 3-4 times
a s much l i p i d as t h e embryo.
b Hug and Pfenninger (1976) suggested t h a t s i n c e l i p i d s can have a
de t r imenta l e f f e c t on beer p r o p e r t i e s (aroma, t a s t e , foam s t a b i l i t y ,
gush ing ) , t h a t it would be good i f maize should be d e f a t t e d t o a
l i p i d content of less than 1% before being used i n brewing. IIowever,
it has now been examined i f t h i s d e f a t t i n g , i s necessary s ince , i t
r e s u l t s i n a r e l a t i v e l y expensive product. From many brewing trials,
both p i l o t - and f u l l - s c a l e , with maize of varying l i p i d con ten t s
(0.7 - 4.3%), i t was concluded t h a t t h e negat ive e f f e c t s of high l i p i d content i n maize, e s p e c i a l l y on foam s t a b i l i t y and orgnnolept ic
, p r o p e r t i e s w e r e g r e a t l y overestiiaated.
Oke (1965) s tud ied t h e mineral con ten t s of some Nigerian
c e r e a l s and repor ted t h a t t he Ca:P r a t i o f o r maize, sorghum and r i c e
were 1:4; 1:9 and 1:3, r e spec t ive ly . The s a t i s f a c t o r y r a t i o f o r
t h e balanced foods tu f f s i s 1:2. He a l s o found t h a t maize and sorghum
showed s i m i l a r p r o t e i n , phosphorus and magnesium contents . hW:e
maize i s h igher i n a s h , calcium and e the r - ex t r ac t ab le substances,
sorghum has a crude f i b r e content nea r ly twice t h a t of maize.
It is gene ra l ly agreed t h a t t h e presence of oxa la t e s i n food
impai rs t h e absorp t ion of calcium. Qke (1967) rcport$d t h a t t h e
amount of oxa la t e found i n maize i s smal l , and s o could not be
harmful. ~ a i z e only con ta ins t r a c e s of hydrocyanic a c i d (1.0 mg % )
which ~ o u l d poss ib ly be reaardsd as an impurity. About j f l of t h e
phosphorus i n maize occurs a s phy t i c ac id .
Bressani and Rios (1962) and Bressani and Mertz (1958) showed / b
t h a t t h e l e v e l s of t h e e s s e n t i a l amino a c i d s o f maize and sorghum
a r e very s i m i l a r , and t h a t they a r e both d e f i c i e n t i n l y s i n e and
tryptophan. The s i m i l a r i t y i n chemical composition of maize t o
sorghum ~ h o w s t h a t maize could rep lace sorghum (and v i c e versa)
without s i g n i f i c a n t l y changing t h e n u t r i t i v e value of t h e d i e t .
Kamath and Bel~ovady (1980) determined t h e unavai lab le carbo-
hydra tes i n Indian ce rea l s . They found t h a t unavai lab le carbo-
hydrate was lowest i n r i c e (8.3%) and h ighes t i n p e a r l n l i l l e t
(20.3%) with sorghum, wheat, nlaize, and Ragi having in te rmedia te
values.
Weckerbaur e t al. (1983) s tud ied the e f f e c t of mashing,
l a u t e r i n g and bo i l i ng procedures on t h e t o t a l f a t t y a c i d content
and ind iv idua l f a t t y a c i d s i n worts. Decoction mashing gave h igher
)(,
f r e e f a t t y a c i d concent ra t ion than in fus ion mashiny. The hot-
A 50010 maize mash gave a 45% lower f r e e f a t t y a c i d s concent ra t ion
than an a l l malt mash. In t ens ive a g i t a t i o n dul-ing l a u t e r i n g con-
s ide rab ly inc reases f r e e f a t t y a c i d concent ra t ion i n wort. Turbid
worts had higher f r e e f a t t y a c i d content than c l e a r w o r t s . There
i s a reduct ion of free f a t t y a c i d concent ra t ion during wort
bo i l ing . Long chain unsa tura ted f a t t y a c i d which makes up about
4% of t h e t o t a l f r e e f a t t y a c i d s f e l l t o 20% of i t s o r i g i n a l v a l w
a f t e r wort bo i l ing . The C -C f o r f a t t y a c i d s showed an inc rease i 6
a t t h e s t a r t o f bo i l i ng then increased as a r e s u l t of adsorp t ion on b
p r e c i p i t a t e d s o l i d s .
2 5 MAIZE I N THE BREWING INDUSTRY
I n r ecen t yea r s , malting of c e r e a l s o t h e r than hu l l ed ba r l ey
has a t t r a c t e d a t t e n t i o n (Singh and Bains, 1984; Singh and Sosulsk i ,
1985). This i s bBcause of economic cons ide ra t ion .and l o c a l a v a i l -
a b i l i t i e s . The non-malt brewing m a t e r i a l s used 111 g r e a t e s t
q u a n t i t y today a r e der ived from t h e c e r e a l g r a i n s - maize, sorghum, m i l l e t , ba r l ey , wheat and r i c e . Other m a t e r i a l s i n t h e form of
sugar syrups may be added t o t h e copper k e t t l e during wort bo i l ing .
Pfenninger & s. (1972) r epo r t ed t h e product ion of beer using maize a s ad junc t up t o 15% s u b s t i t u t i o n f o r bar ley malt. Maize g r i t s ,
corn syrups and maize flalccs a r e popular ly used a s s t a r chy
ad junc t s i n brewing. Maize grits fru.>l yellow dent corn a r e the rriost
commonly w e d s t a r chy ad junc t s i n t h e U.S.A. ( ~ a n n a l e s , l 9 7 9 ) .
Olatunj i (1977) produced brewers g r i t s from two Nigerian maize
v a r i e t i e s , l o c a l white farmer ' s and loca l yellow farmer 's .
Mashing t r i a l s with combinations of white o r yellow g r i t s and
barley malt Qave r e s u l t @ f o r hot water e x t r a c t (HWE) i n brewerv L
~ b / s t a n d a r d qua r t e r of m a l t (152.7 kg) of 88.5 f o r 20 g of ybllow
g r i t s p lus 30 g of malt versus 99.2 f o r 50 g malt only. s p e c i f i c
g rav i ty ranged from 1025.9 f o r 25 g malt only and 1027.2 f o r 50 g
malt only. It was concluded t h a t i t is poss ib le t o p a r t i a l l y
replace brewing malt with loca l v a r i e t i e s of maize.
* Hough e t a l . (1981) i n repor t ing t h e works of Cannales and
S i e r r a (19761, Coors (1976) and Cannales (1979) have shown t h e
a n a l y s i s of various brewing adjuncts . The percentage e x t r a c t s were
I-eported a s maize g r i t s = 79.3, Rice g r i t s = 81.7, Sorghum ~ r i t s =
81.3, r e f ined maize s t a r c h = 92.9, r e f ined wheat s t a r c h = 95.2,
t o r r i f i e d wheat = 74.4 and t o r r i f i e d bar ley = 67.9. S imi lar ly ,
t h e percentage p ro te in values were Maize g r i t s = 8.5, Rice
grits = 5.4, Sorghum g r i t s = 8.7, r e f ined maize s t a r c h = 0.4,
r e f ined wheat s t a r c h = 0.2, t o r r i f i e d wheat = 12.2, and t o r r i f i e d
' barley = 13.5. The e x t r a c t s of r e f ined s t a rches show mmarkably
higher var lues than those of the g ra in g r i t s and t o r r i f i e d g r i t s .
Refined s t a rches conta in comparatively l i t t l e nitrogenous mat c r i u l
< J
hence w i l l enhance beer s t a b i l i t y . The f a t contents of ce rea l
d i f f e r and because high f a t l e v e l s a r e deJe te r ious t o beer q u a l i t y ,
, . o a t s a r e r a r e l y used i n brewing. Lipid l e v e l s of 6.1% and 3.N
have been repor ted f o r o a t and sorghum g r a i n s r e s p e c t i v e l y ( ~ o u ~ h
e t a l . , 1981). Maize, sorghum and r i c e g ra ins a r e i nva r i ab ly - processed t o remove t h e o i l - r i c h germs and bran before being usea
i n t h e p repa ra t ion of ad junc ts . #
The use of maize as adjunct i s a s soc i a t ed with b e t t e r s h e l f
l i f e presumably a s a consequence of i ts lower l e v e l s of high mole-
c u l a r weight ni t rogenous compounds i n bee r , and wheat f l o u r poss ib ly
due t o i t s content of g lycopro te in has b e n e f i c i a l e f f e c t s on head
r e t en t ion .
b Canales and S i e r r a (1976) descr ibed t h e use of sorghum a s a
brewing g r a i n which i s popular i n Mexico. Analysis of commercial
beer* produced by using sorghum g r i t s and maize ~ r i t s re spec t ive ly
d i c t a t e d l i t t l e o r no d i f f e r ence between beers . They pos tu l a t ed
t h a t sorghum may confer a d d i t i o n a l ox ida t ive s t a b i l i t y t o beer due
t o i t s lower content of unsa tura ted f a t t y ac ids . And recommended
t h a t t h e types of sorghum most adequate f o r brewing should have
white k e r n e l , low t ann in con ten t , bland f lavour , aud probably imprclved
mi l l ing p rope r t i e s .
Dharnijah and Singh (1978) eva lua ted t h e use of sorghum
(sorghum vulgare) and b a j r a (Pennisetum typhoides) a s ad junc t s f o r
brewing. They found t h a t t h e s t a r c h , p r o t e i n and f a t content i n
b a j r a and sorghum w e r e adequate f o r l,l.ewiny. Wort ex t r a l . t decreased
when t h e concent ra t ion of b a j r a increased but w i t $ sorghum wort,
t h e e x t r a c t s were comparable t o ba r l ey wort. Analysis of wo1.t~
prepared sugges ts t h e p o s s i b i l i t y of using sorghum t a t h e e x t e n t
of 50% and b a j r a up t o 35% only. Beers prepared using 35% sorghum
and 25% b a j r a compared both a n a l y t i c a l l y and o rgano lep t i ca l ly t o
commercial Ind ian beers. #
S h r i g a r t et a l . (1972) compared fou r sorghum v a r i e t i e s wi th
maize g r i t s used f o r brewing i n South Afr ica and found t h a t Lech-
no log ica l ly t h e pea r l ed sorghum g r i t s behaved t h e same way a.> maize
g r i t s . The sorghum v a r i e t i e s had lower o i l y i e l d and a h igher
n i a c i n content than t h e maize beer. b
Skinner (1976) descr ibed t h e product ion of t r o p i c a l l a g e r
beer wi th sorlyhum malt. I n trials c a r r i e d ou t i n Botswana, r e s u l t s J
i nd i ca t ed t h a t acceptab le l a g e r could be brewed from sorghua
malt using a very p r i m i t i v e equipment. A s teeping t i m e of about
16 hours was most s u i t a b l e . The s teeped g r a i n s were spread on a
concre te f l o o r , tu rned and sp r ink led 3 t imes a day f o r 4 days,
0 temperatures being maintained d t 25 - 35 OC. The green malt obtained was d r i e d i n t h e sun f o r 2 - 3 days. Sorghum malt con-
t a i n s an adequate amount of alpha-amylase but only t r a c e s of
'/-amylase and l i m i t d ex t r in i a se . I n o rde r t o achieve t h e necessary
l e v e l of conversion, i n t e n s i v e mashing w a s t h e r e f o r e necessary ,
a 3-stayc decoct ion system was used. Wort w a s run d i r e c t l y from
copper a t near b o i l i n g temperature t o t h e fermentat ibn ves se l alld
t h e beer run ci i rect ly i n t o b o t t l e s , wheu*the r equ i r ed l e v e l of
carbonat ion w a s achieved, t h e b o t t l e s were pas teur ized . Yeast
s e t t l e d o u t a t t h e bottom of t h e b o t t l e . The f i n i s h e d product
proved acceptab le t o a number of t a s t e r s .
S t a t (1973) suggested t h a t completely so lub le m a t e r i a l s w i l l
be t h e u l t ima te forms of brewing iny red ien t s . Hop and maize pro-
cess ing (hop e x t r a c t and maize syrup s o l i d s ) which r e q u i r e l i t t l e
o r no prefermentat ion processing and i n f u t u r e p r o t e i n content i n
brewing may be provided v i a a combination of processed ba r l ey , mn1.t
and non-malt enzymes and s e l e c t i v e e x t r a c t i o n procedures.
B Swain (1976) gave t h e advantages of l i q u i d ing red ien t s which
inc lude increased beer product ion, high q u a l i t y s t a b l e products and
savings i n processing cos t s .
Pol luck and Wur (1976) discussed t h e p o s s i b i l i t y of irnprejved
p roduc t iv i ty a r i s i n g from t h e use of a process i n a malt wort and a
so lub le ad junc t s o l u t i o n are fermented s e p a r a t e l y , a n d blended a f t e r
co ld s to rage for i11al.t.
Moll and Duteur t re (1976) c a r r i e d out p i l o t t r i a l s of a
process i n which a m a l t wort and a so lub le ad junc t s o l u t i o n were
* fermented s e p a r a t e l y and blended a f t e r co ld s to rage f o r m a l t only
on a 10 h e c t o l i t r e sca le . Maize g r i t s were rep laced by a s t a r c h
derived syrup which was fermented s e p a r a t e l y and then blended wi th
a pure m a l t beer p r i o r t o f i l t r a t i o n . The m a l t beer w a s laggered
i n t h e usual way and t h e fermented syrup'was not laggered, The
0 r e s u l t i n g beer which had an o r i g i n a l g r a v i t y of 10 p l a t o , w a s
compared wi th u bee r of
vec t iona l method from a
s i m i l a r s t r e n g t h prepared by t h e con-
g r i t conta in ing 704'o malt d i d 3@& maize
g r i t s . The fermentat ion of t h e syrup s o l u t i o n r equ i r ed between
* and 72 hours according t o i t s g r a v i t y and f i v e t i m e s t h e normal
p i t ch ing r a t e o f yeas t w a s used. The r e s u l t i n g product had
a n a l y t i c a l c h a r a c t e r i s t i c s s i m i l a r t o those o f ~ ~ n ~ e n t i ~ n a l beer
and t a s t i n g r e s u l t s w a r e encouraging.
Venlcatan~rayan et A. ( 1977) found t h a t Ragi (El eus ine
cora lana) could be used as an ad junct i n brewing. Microbiai
enzymes l i k e amylases and p ro t eases were necessary t o produce a
wort and beer wi th d e s i r a b l e c h a r a c t e r i s t i c s . When mashed without
microbial enzymes, t h e a lpha amino content o f wort was 120 n i g / l i t i t
and t h e degree of fermentat ion of t h e w o ~ t was less than i n con t ro l .
With t h e use of microbial enzynres, t h e a lpha amino n i t rogen l e v e l
was increased t o 175 mg/l and marked improvement i n t h e degree o i
fermentat ion was observed. The wort fermented smoothly and t h e
foam o f t h e bee r appeared t o he b e t t e r .
Caripa and Mostek (1974a) rep laced n a t u r a l malt.enzymes by
analogous enzyme p repa ra t ions owing t o t h e high c o s t of malt .
B a c t e r i a l amylase decreased s i g n i f i c a n t l y t h e d e x t r i n content and
increased t h e amount of reducing sugars i n comparison with con t ro l
wort. Wort conta in ing fungal a lpha amylase had t h e h ighes t ferIlien-
t a t i o n rate but low auount of a lpha a ~ i ~ i ~ i o ~ ~ i t r o ~ , . l i and reducing
suga~,s. P r o t e o l y t i c enzymes increased most sigr1i.f i c a n t l y the t o t a l
1,clm i 1 a~?tl (;ubcbi c .wsk i ( 1')7(, l o u ~ l t l t h a l '1 I ' o l i:,h t ) a c L < \ i - i a l
myla law rx-cparai.j on i :? equiva 1 c.11 1 I o N o v i l < ~ N - 3 / 1 0 (a r o n ~ r n c ~ r ~ i a 1 I
cn;.ynAc pr@parntj on) . C r PI-otco l y tic: c:nxyrnc,L-. arc atl t l ( , t l , Lowcr K I I ~ t o r x l a I I P V ( > I -7 o(' '1 I pha a i t ~ 110 11i t I O!J (>I I ; ~ l i ( l L o t ,i 1 p r - o t C > ~ I I ~ ( % r p
f utlt~tl i ~.t:su I 1 i ~ ~ g w o r t s and tw(?~.s.
using b a c t e r i a l , fungal and p l a n t enzymes, making it poss ib l e t o
rep lace 7PA of m a l t g r i s t by cheaper s u b s t i t u t e s .
Kieninger (1973) c a r r i e d out mashing trials which showed that 0
a d d i t i o n oi' 0.01t50/u of an enzyme mixture (alpha amylase, amylo-
g lucos idases and p ro t ease ) t o t h e g r i s t permi t ted a reduct ion of
t h e mashing't ime from 153 minutes t o 110 minutes o r less without
adverse e f f e c t s on e x t r a c t y i e l d , so lub le n i t rogen , a t t e n u a t i o n
l i m i t , v i s c o s i t y o r a lpha amino n i t rogen concentrat ion. Addition
of.same concent ra t ion of enzyme mixture t o malt germinated f o r b
only 4 days permi t ted t h e product ion of wort of ccmparable
qua]- i ty t o t h a t produced from malt germinated f o r 6 days. Use of
added enzymes d id n o t , however, permit product ion of wor ts of
equal q u a l i t y t o those produced from 8-day germinated m a l t .
Weig (1973) made c o m ~ a r i s o n s between two s e r i e s of brews made
from mashes conta in ing 85% malt and 15% maize and mashes i n which 1 -
7& of t h e m a l t was rep laced by barley. Composition o f m a l t g r i s t
w a s va r i ed and mashing procedure was var ied . U s e o f 75% (6@h ba r l ey
and 17% maize o r 75% ba r l ey ) ad junc t wi th 25% bar ley .mal t and
added enzymes r equ i r ed no g r e a t e r mashing o r l a u t e r i n g time than
c o n t r o l brews. Primary and secondary fermentat ion o f worts from
ba r l ey mashes were e n t i r e l y normal. The most important concluvions
,, reached were t h a t ba r l ey brews produced beers t h a t had lower
co lour , b e t t e r foam-head r e t e n t i o n and g r e a t e r c h i l l s t a b i l i t y than
con t ro l beers . U s e of ba r l ey as an ad junct a! io s i g n i f i c a n t l y
improved u ~ i l i z a t i o n of hop b i t t e r substances.
CHAPTER THREE
3 00 MATERIALS AND METHODS
3.1 MATERIALS AND SAMPLE PREPARATION
IfTZSR-Yl1 v a r i e t y of maize g r a i n s w e r e ob ta ined from I n t e r n a t i o n a l
I n s t i t u t e of Tropica l Agr icu l ture (IITA), Ibadan. Yeast (Saccharomvces
c a r l ~ b e r ~ e n s i s ) , hops and i n d u s t r i a l enzymes were obta ined from
Diamond Breweries Limited, Ninth milo Corner, Enugu. Yeast was
0 s t o r e d on Sabourand Dextrose Agar S l a n t s a t 4 C.
b
3.2 PREPARATION OF MEDIA (Sabouraud dext rose aga r s l a n t s )
6.5 g of Sabouraud dext rose a g a r w a s suspended i n 100 m l of
d i s t i l l e d w a t e r . The mixture w a s brought t o b o i l t o d i s so lve com-
0 p l e t e ly . It w a s s t e r i l i z e d by au toc lav ing a t 121 C f o r 15 minutes.
The s t e r i l i z e d s o l u t i o n w a s poured i n t o s t e r i l e t e s t t ubes and
covered wi th c o t t o n wool under a s c e p t i c condi t ions . The test tubes
were l e f t i n a s l a n t p o s i t i o n f o r t h e s o l u t i o n t o ge l . They were
s t o r e d f o r 24 hours before use i n o rde r t o check f o r any microbio-
. l o g i c a l contamination.
3.2.1 Yeast Ex t r ac t Peptone Dextrose (YEPD) Broth
Yeast e x t r a c t peptone dext rose (YEPD) b ro th w a s prepared
accord in^ t o t h e following composition: ,
Yeast e x t r a c t 1.0 g
Peptone 2.0 g
Dextrose 2.0 g
D i s t i l l e d water 100 m l
0 The mixture was autoclaved a t 121 C f o r 15 minukes.
3.2.2 Preparat ion Of Maize G r i t s
G r i t s production involved crushing c lean dry maize g ra ins
t o 1 - 2 mm p a r t i c l e s i z e with Thomas Wiley mi l l ing machine b
and separa t ing t h e crushed endosperm with a loca l s ieve. The
f r a c t i o n containing mainly t h e embryo was discarded.
3.2.3 Maize Grain Analysis
The sample, TZSR-Y maize was analysed based on t h e
following parameters: moisture content , germination t e s t ,
malting and k i ln ing .
3 .2 .3 .1 Moisture content of TZSR-Y maize *
The Thomas-Wiley mi l l ing machine w a s set t o gr ind f ine ly .
The machine was f i r s t r i m e d with the sample. About 7 g of
t l i e sample was t r ans fe r red i n t o a f l a t dish and h i s was
shake-level. T t was closed irnrnediately with the l i d and
weighed. The l i d w a s r enloved and tt;e sample t r a n s f e r r e d t o
0 t h e oven a t 100 C f o r exddtly 4 hrs . The l i d w d s t !~en replaced
and t h e whole ma te r i a l t r a n s f e r r e d t o t he des i cca to r f o r
cool ing. This w a s then weighed again. The moisture was
c a l c u l a t e d as fo l lows:
where, M = Moisture content (%) of maize
W1 = Weight of sample before drying
W = Weight of sample a f t e r drying. 2
It should be noted t h a t g r a i n cannot be d r i e d t o ~or i s tan t .
weight a s cont inued hea t ing merely causes increased removal
of vo l .a t i les o t h e r than water vapour.
3 .2 .3 .2 Germination t e s t and water re la t ion . ,
The object of this test 18 Lo measure t h e percentayo
of l i v i n g dorns i n t h e sample. They a r e determined as b r i e f l y
s t a t e d below:
3.2.3.3 Water s e n s i t i v i t y
I n t o two 9 cm p e t r i d i shes were put whatman No. 1 f i l t e r
paper soaked i n water. 4 m l and 8 m l of water were added
i n t o t h e p e t r i d i shes r e spec t ive ly and 100 maize turns ~ d d e d
i n each p e t r i dish. They were covered w.i th l i d s and allowed
0 t o germinate a t room temperature (3 C) t u r 72 hr . !he
number of corns i n each p e t r i d i sh t h a t germinated were
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counted a t 24 h r i n t e r v a l s .
3 -2 .3 .4 Germination eneray
The ob jec t of t h i s t e s t i s t o measure t h e gercentage
of g r a i n s which can be expected t o germinate f u l l y i f t h e
sample is malted normally a t t h e t i m e o f t h e test. The
BIRF method was used with s l i g h t modif icat ions.
Two f i l t e r papers w e r e p laced i n t h e bottom of t h e
p e t r i d i sh and 4 m l of d i s t i l l e d water was a c c u r a t e l y pdded
t o w e t t h e f i l t e r papers evenly. 100 corns were counted
and placed oil t h e papers s o t h a t each corn makes goot! con tac t
with t h e moist paper. The p e t r i d i s h w a s covered with t h e
l i d . This w a s examined a f t e r 2 4 , 48 and 7 2 hr . removing
c h i t t e d corns on each occasion. The corns which have not
c h i t t e d a f t k r 72 h r were counted. The percentage t h a t
germinated w a s c a l cu l a t ed .
3.2.3.5 Steeping c h a r a c t e r i s t i c s . 200 g of maize g r a i n s were s teeped i n water a f t e r washi
i n running t a p water and then i n d i s t i l l e d water. Samples
of maize g r a i n s were retnoved a t 0 hour, 8 h r , 16 hl , 211 h r ,
32 h r , ~ L Q h r , 48 h r and 56 h r of s teeping , The w e t g r a i n s
were su r f ace d r i e d by dry f i l t e r paper and weighed and t l c
moistule absorbed by the g r a i n s di~termined.
3.2.3.6 Malting of a mavs The method described below i s a s l i g h t modffication of
the s tandard method employed i n t h e malting of ba r l ey g ra ins
described by Hough et &. (1981). w One kilogram ( 1 kg) of maize g ra ins w a s s teeped i n
0 ordinary t a p water f o r 40 h r a t room temperature (28 c ) .
The si.eeping water was changed every 2 h r f o r t h e f i r s t
s ix t een hours of s teeping and afterwards a t e i g h t hourly
i n t e r v a l s u n t i l sprouting g ra ins were seen. A t t he end of b
s teeping, the maize g ra ins were drained out and then spread
on a c lean t r a y lined with moist towel and covered with
polythene t o prevent evaporation and t o provide warmth. The
build-up of heat acce le ra t e s the uptake of the f i lm oi
surface moisture and the onset of germination. The g ra in
t tp iecem turned and ~ u x e d twice a day t o equal izc t h e tem-
pera ture and t o prevent growing r o o t s malting together . This
was done f o r the dura t ion of the germination. The germination
was terminated by k k l n i n ~ . For the purpose of t h i s work,
por t ions of t h e germinated maize g ra ins were removed and
k i lned a f t e r each day of germination. This r e s u l t e d i n t h e
production of malt f o r var ious days of germination froill 1 - 5 days.
3.2.3.7
The germinated maize g r a i n s w e r e t r a n s f e r r e d i n t o t h e
p l a t e on d a i l y b a s i s and placed i n t o a the rmos ta t i ca l ly
0 con t ro l l ed oven a t 45 C. The k i l n i n g l a s t e d fo: 24 h r u n t i l
t he g r a i n s became hand dry and ' f l i n t y ' such t h a t t h e
plumule and r a d i c l e could be removed by rubbing wi th hand.
A t t h e e x p i r a t i o n o f t h i s t i m e t h e malt became l t f r i ab l e t l .
The s ~ m p l e s were t h e n removed for some phys ica l and chemical
ana lys i s . b
3.3 MAIZE MALT ANALYSIS
1 Moisture Content of Zea mays
The procedure i s a s descr ibed e a r l i e r i n s e c t i o n 3.2.3.1.
3 . 3 . 2 Modificat ion T e s t s
Modif icat ion is the convenient term t o desct,ibc the
sum t o t a l of t he phys ica l and chemical changes which take
p lace during malt ing, transforming t h e tough maize corn i n t b
f r i a b l e malt.
3.3.3 Malting Loss Determination
Malting l o s s is t h e 11:~i ter ia l l o s t a s percentage ~ l r y
weight i n convert ing malze i n t o m, L t - t h e degradat ion of t h e endosperm (ASUC method of Analysis , 1958). Two hundred
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corns were counted and weighed a f t e r t h e r o o t l e t s have been
removed from t h e d r i e d ma te r i a l by p lac ing i t i n a c l o t h bag and
rubbing between palms of t h e hands. Th i s w a s done f o r t h e
malted g r a i n s f o r days 1, 2, 3 , 4 and 5. The l o s d i n weight
was o b t a i m d as t h e d i f f e r ence between t h e unmalted corn
weight and t h e malted corn weight. That i s W1 - W and t h e 2
maltitla l o s s ~ a l c u l a t e d as fol lows:
W1 - W Mal t ing* los s ( t o t a l ) % = 2 x 100
W1
where, W = weight of t h e unmalted maize 1
W2 = weight of t h e malted maize.
3.3.4 Ex t r ac t Determination
This i s a l l t h e ma te r i a l s brought i n t o s o l u t i o n i n water
by enzymic a c t i o n from ground malt . Although t h e Bahler-rnaiy
m i l l i s recommended, Thomas-Wiley m i l l w a s used f o r t h i s
8 \
ana lys i s . The s e t t i n g was 2 mm. The I.O.B. method of a n a l y s i s
1 recommended r o l l e r m i l l d r iven by an e l e c t r i c motor of /3 h.p. w
tu rn ing t h e dr iven r o l l a t 100 - 110 r.p.m. Thomas-Wiley m i l l w a s c leaned wi th brush and f i t t e d with
2 mrn sieve. The m i l l w a s r i n s e d wi th l i t t l e of t h e malt sample.
The malt w a s then ground. Exact ly 10 g of t h e g r i s t was weighed.
72 m l of d i s t i l l e d water w a s -,oured i n t o a 250 m l con ica l
0 flask a t a temperature of 67 C. The weighed g r i s t was s t i r r e d i n t o
the f l a s k and t h e mash temperature l e f t a t 65 - + 0.2O~. The f l a s k w a s 0
'\ ' then covered and l e f t i n t h e bath a t 65 C f o r exac t ly 1 hr. The
content was continuously s t i r r e d a t 10 .min i n t e r v a l s . i t t h e end of
0 1 h r , t h e mash w a s cooled t o 20 + 0.2 C immediately, and allowed t o - s tand f o r exac t ly 25 min. The mash w a s washed through a wide funnel
i n t o a 100 ml volumetric f l a sk . The r i n s i n g s were added t o t h e
volumetric f l a s k and t h e l e v e l f i n a l l y made up t o t h e mark. This w a s
t h e n . f i l t e r e d and the f i r s t 50 m l po r t ion of t h e f i l t r a t e re turned b
f o r f u r t h e r f i l t r a t i o n . The c l e a r f i l t r a t e w a s c o l l e c t e d f o r ~ r a v i t y
of t h e wort.
The s p e c i f i c g r a v i t y b o t t l e was scrupulously cleaned, it w a s
washed out twice with d i s t i l l e d water and with a lcohol ( twice) . It
w a s then kept i n t h e oven t o dry. The b o t t l e and t h e s topper were
cooled i n t h e des icca tor . It was weighed accura te ly . D i s t i l l e d
0 water was prepared a t 15.5 C s o a l s o were the worts f o r t h e days 1,
2 , 3, 4 and 5. The b o t t l e was f i l l e d with d i s t i l l e d water and t h e
s topper in se r t ed . It wan thoroughly cleaned and weighed as soon a s
possible . This process was repeated with t h e worts f o r t h e days 1,
2, 3, 4 and 5. A cor rec t ion f a c t o r f o r t h e l i t t l e r i s e i n temperature
during weighing w a s done. The e x t r a c t t a b l e was used t o ob ta in
the corresponding values from t h e S.G. obtained. Ex t rac t value can
be obtained d i r e c t l y from t h e r e l a t i o n :
E = 3.565 (Excess s p e c i f i c g r a v i t y over 1000) .. 4.8
where, E = Extrac t .
3 .3 .5 Cold Water Ex t r ac t
The co ld water e x t r a c t i s a s o l u t i o n o f pre3formed
so lub le m a t e r i a l s sometimes c a l l e d "Matter Solublef1 or pre-
formed sugars f f which was leached i n t o s o l ~ t i ~ n from ground
m a l t under condi t ions which preclude i n t e r v e n t i o n o f enz3uies
( ~ k a f o r & Aniche, 1980). In preparing co ld water e x t r a c t ,
enzyme a c t i v i t y i s stopped by a d d i t i o n o f ammonia (Hough b
e t al. 1982). The procedure i s a s fol lows:
5 Q of ground g r i e t w a s added t o 100 m l o f d i s t i l l e d water contain-
ing 6 m l of 0 . 1 N ammonia s o l u t i o n i n a con ica l f l a sk . The
0 mash w a s maintained a t 20 + 0.2 C f o r 3 h r with s t i r r i n g - every 3 0 min. The s o l u t i o n 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 o f t h e e x t r a c t w a s determined using s p e c i f i c g rav i ty
b o t t l e . This procedure was c a r r i e d ou t f o r a l l t h e samples
represent ing days 1, 2 , 3 , 4 and 5 malt ing periods. Cold
water e x t r a c t (C.W.E.) w a s c a l c u l a t e d a s fol lows:
S.G. - 1000 C.W.E. = (
39% x 2 0
where, C.W.E. = cold water e x t r a c t
S.G. = t h e excess s p e c i f i c g r a v i t y qf t h e f i l t r a t e over 1000
3.3.6 Determination o f D i a s t a t i c Power
Diastatic power is usua l ly a measure of the j o i n t a c t i o n
of alpha-amylase and beta-amylase.
10 g of coa r se ly ground malt was weighed o u l and mixed
with l i t t l e w a t e r t o make a paste . This was poured i n t o 400 m l
of b o i l i n g d i s t i l l e d water and l e f t t o b o i l f o r 2 ~nin. The
beaker w a s covered wi th c lock g l a s s and cooled t o room
temperature. 10 m l of a c e t a t e b u f f e r w a s added and t h e s o l u t i o n
made up t o 500 m l mark. t
5 g of ground maize malt was e x t r a c t e d with 100 m l of
df s t i l l e d w a t e r conta in ing 6 m l of 0.1N ammonia s o l u t i o n f o r
3 hr a t 20 + 0 . 2 5 ~ ~ . Th i s was s t i r r e d a t 30 min i n t e r v a l s . - The p a r t i c l e s were allowed t o s e t t l e so t h a t t h e superna tan t
can be p