Soya Utilization in Ethiopia

Prelminary Study

ETHIOPIAN NUTRITION INSTITUTE jL^ <2.6/$

SOYA UTILIZATION IN

ETHIOPIA

Preliminary Study

by

TiJLahun Belcele ENI r.osoarch. Officer

Meaza Felcade ENI Officer

P.C. BauchauPood Technologist (FAO)

May 1981

Food and Agricultural Organization ... . . _ TIof the United Nations ministry of Health

acknowledgement

The writers wish to express their sincere thanks to the Director of the Ethiopian Nytrition Institute (ENl) and the Head of the Nutrition Department for their kind assistance and interest in the progress of this work.

Thanks are also due to Mr. Courtois from the Dairy Development Agoncy JTor his cooperation and to the staff members of the E«N,I.

INTRODUCTION

Soybean is a member of the Legui: inosae family with alternatetrlfal jiilat* leave® except at the first nodes. Flowers are usually either purple or white, purple being dominant. Seeds are nearlyspherical with average weight 120-180 mg. Cotyledons turn yellowas seeds mature. Soybean is Asiatic in origin but it includes germplasm adapted to latitudes from 0° to more than 5°° (Allan et al.)

Soybeans can produce over 33 percent more protein per acre than any other known rrops and TWENTY times as much usable protein as could be raised on an acre given over to grazing beef cattle or growing their fodder. (Fig. l)

400—2;H«(H| 300-wm <!CO Do(/)Qs

200—

1 0 0 --

Fig.l Per-acre yields of usableProtein from Different l'ood Sources.

Source:Calculated from USDA per- acre yield statistics (1971-7*0 and WH0/FA0/UNICEF Protein Advisory group Bulletin §6,1 9 7 1.

oybeans (356)

i/;/

VA 0 / /

I

F.ice (26 5)

Ccrn (211)Other legumes (1 9 2)

i

Wheat (138) Milk (82)

I 1rs (78)Meat(45)(all typ

J _ ir (20)Soybeans are also excellent in terms of qualit>; they include

all of the eight essential amino acids. Soybeans food products contain no cholesterol and almost none of the relatively indigestible fat s.

The following table (Fig. 2) gives the composition of some foods commonly used in Ethiopia compared with soybean food products.

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P'ig*2 Composition in Terra of 100 f rams Edibi- ?or, on

■ .....Fo od

1 ... i

--------- {FoodEnergyCalories

Moisture°/°

Protein°/o

!; Fat1 $J. ... ..

Carbohydr­ates c/c

1 Fiber)(t

J ‘JaI

Soybeans 392 12.0 3 4 . 3 17.5 2 6. 7 4 . 5 0 f iTofu(Soy-cheese) 72 84.9 7 . 8 4.3 2.3 C !

0 7 jSoyrailk 42 90. 8 3-6 2.0* 2.9 0.02 0.5 jCorn 380 6.7 <*> r/

v 1 4.6 76.3 2.4" ' IXj- 9 ,Wheat 336 11.0 12 4 2.3 6 9 . 8 2.4

Sorghum 338 12.1 7 l 2.8 74.2 2.3 „ V1 b ;

i

Lenti L 344 10.2 22 . 6 1-0 58.4 4 0 t. 0 , :..oSesame 563 5.4 12.6 49.1 15.3 6 , 3 5.3 ;Milk 76 87 • 6 3 . 4 I 5 3 3 8 0 0 6 j

It Ayib |

135 73-7 1 5 . 2 6 0 4 2.7 0.2 1 . 2

A number of meal products are ma : from soybean. Some are verysimple, like soymLlk rnd Tofu .’a kin: cottage cheese)» others quitelaborate, made from protein isolate, chat can bo transformed into processed meats.

Soybean was introduced in Sthiop. * only 15 years ago., Wollega,Gojau, Kaffa, Awassa, Shashenene and tvash are major sites of soybeanpro-uciton. (the most important bein' "elloga).

A number of varieties (about 2C' iave been introduced, but dataabout the yield and results are not ‘ailable.

The following figures fox- soybo;-;: production in Ethiopia are only J.nformative: (Source: Ministry of .-to Farmers)

Production/tonsYear (E.C.)70-7171-7272-73

Area/i39>2l6CC$?.'

332967

8000

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For 1973-197^ E.C. the Relief and Rehabilitation Commission plans to grow soybeans in 4 low-land stations in the Wollo and Me“tharu areas.

Lack of market and lack of know-how as to local consumption are the main problems in relation to high-scale production in Ethiopia.

The study of soy products started in 1980 at the Ethiopian Nutrition Institute, for various na.jor reasons.- There is a shortage of milk in Ethiopia (of 150,000 litres

a day for Addis Abeba only) and soymilk could be an advantage­ous substitute.Soymilk can be produced at a much lower cost than cow-milk (about one third) and is almost as nutritive.Many Ethiopians fast for as much as 200 days a year and are not allowed to eat any animal products (except fish) during those days. Soymilk, with it3 eight essential amino acids readily usable by the human body, could help solve that diet problem.

- Many soy products can be made at home without any specialequipment.

For a question of conveniencs afor the reader this report is divided in three sections;

I Soy products at home or cottage-level.II Whole soymilk on an industrial scale.III Spray drying of soymilk.

Each section includes conclusions, recommendations and useful information.

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Section X: Soy Products at Home or Cj?ttage-»Level

Various products can be made at home and there are hundreds of reoipes to prepare then. The objective of this study is limited to '"TOFU**—making and includ&s the use of the by-pjxkdufttfl obtained during the processing, and the preparation of cheese.

"TOFU1* a kind of cottage cheese that can be made in a coupleof houra and can be kept for a few days.

Most of the vorlc carried out in the present study and most ofthe comments and data have been inspired by the two books by WilliamShurtleff and Akiko Aoyagis "The book of TOFU, volume I and II."The first part of this report has to be considered as an application of their study to Ethiopian conditions.

Tofu is an excellent food to use in combining proteins since it contains a lot of lysine, which is deficient in many grain products. Most grains, on the other hand, are well endowed with the sulfur<-containing amino acids (methionine and cystine) the limiting amino acids in soybeans (Fig 3)* Thus, soy and grain proteins, having exactly the opposited strengths and weakness, complement each other. By serving tofu and other grains at the same meal and combining them in the correct ratios it is possible to make a "new protein." The net protein utilization of such a combination is much higher than that of either of the individual foods and, therefore, the total usable protein Is considerably greater than if the foods were served at separate meals. Because of its unique amino acid composition, tofu is not only a basic protein source but also a remarkable protein boaster.Fig.3 Amounts of essential Amino Acids and their Percentages with

Minimum Daily Requirement (MDR) in 100 gm of Tofu.(Source: Japanese Scientific Research Council)

Amino Acids MDR(gm)

TofuOgm)

MDR (< )

(Methionine-cystine) 1.10 0. 20 17Tryptothan 0, 25 0.12 47Methionine 0. 20 0.10 52Leucine 1. 10 0 - 59 52Valine 0, CO 0.40 53Isoleucine 0.70 0.U1 59(Phenylalanine-tyrosine) 1 .10 0.75 67Lysine 0.80 0.57 71Threonine o. 50 0 .3 7 72Phenylalanine o. 30 0.48 160Protein usable 4 3.10 5.06 12

~ 3 -

With a digestion rate of 95C/J Tofu is much more digestible than high*protein foods4 such as meats, dairy products and beans; it can be an ej^eilent food for babies, elderly adults, and peoplewith digestive problems.

Tofu has so many qualities that it will take pages to enumerate them. The reader is invited to consult the above-mentioned books by Willian Shvurtlaff and Akilco Aoyagi.

TOFU MAKING: The procedure to make tofu can be summarized in the following flow sheet (Fig.U)

Fig. hi Flow sheet for Tofu.

Percentage of original protein contained in products

SoakingGrinding

CookingCoagulant

Settling

Soybeans

\

\/

-7

N/

n/

Soymilk curdj

V

(100$)

7

(7 H )

OKAPA

VHIBY

(179 )

(9°/o)

Soaking water (0.5‘/o)

(73-5#)TOFU

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The production of "tofu follows two main stages.a) The preparation of soymilkb) The coagulation of this milk to obtain ourds which are then

pressed to form tofu calces.I. Ingredients

Soybeansj water, lemon juice (or another coagulant)II. Utensils Neededsto make tofu at home (fig. No 5)

- An electrical blender, or meat grinder, or handmill- 2 cooking pots with a capacity of 6 to 8 liters- A sauce-pan (l litre)- A wooden spoon- A wooden spatula- A rubber spatula- A sturdy one-liter jar or a potato masher- A measuring cup- A set of measuring spoons- A large, round-bottomed colander (to fit into one of the pots)- A flat-bottomed colander, rectangular or square.("settling

container" see Fig.6)- A fine-.mesh strainer- A coarsely-woven cotton dish cloth '„or a "pressing sack";- A light cotton dishtowel.

!

- 7-

Fig. 5

Utensils for making

—8"

. Fig 6

Fig. No. 6 Two designs for a homemade settling container.

Wooden container 18 by 9 by 9cm the bottom is removable. The bottom and sides of the container are perforated with 0.75 cm. dia-

- meter holes.

Plastic container with the bottom and sides perforatad with 0.50 era. diameter holes.

IV METHOD- 150 gm. soybeans, washed,soaked

in 450 ml. of water for +_ 10 tjours, rinsed and drained.

- 1050 ml. of water, approximately- Solidifier (30 ml. of lemon juic$

Prepare in advance:

Place preosing pot in sink and set colander into pot. Moisten pressing sack lightly and line colander with •ack, getting mouth of sack around rim ' : of colander. Or line colander with a moistened dish towel (Fig. 7a )

Thin cotton dish towel ia moistened and used to line bottom and sides of settling container. Plact container on ria of large bowel or pdn placed in sink.

Fill a one litre sauce pan with 500 ml. of water (Wa) and warm over low heat. After making the above preparation pro­ceed as follows•

1. 550 ml. of water are combined with the beans in a blender and pureed at high speed until very smooth. (If- using a grain mill or a stone mill grind beans without adding water and add the 550 ml. of water to the other 5D0 ml. prepared in advance)

2, Remove 150 ml. water from the 500 ml, water heating in a sauce pan (Wa) for

. later use of repressing and use the remaining water (350 ml.) to cook the puree for 20 minutes by stirring constantly with a wooden spatula to pre-vtat sticking. (Fig. 7b )

7b)

/

- 10-

’. our the contents of pot into pressing sack (Pig. 7c) and twist rhe pressing sack to close it. Using a glass jar or potato masher, press sapk against colander, extracting as much soymilk as possir' ble (Fig. 7d). Open sack, moisten cVara with 150 ml. warm water reser­ved in step 2 and repress again to extract more soymilk. (Fig. 7e). .

Pour soymilk into cooking pot and h ring to a boil over high heat, stirring frequently to prevent sticking. Reduce heat to medium and cook for 5 to 7 minutes.

»Stir soymilk vigorously, sprinkle 1/3 lemon juice (10 ml.) while stirring and again stir 5 to 6 times more. When turbulence ceases sprinkle 1/3 lemon juice (10 ml.) and cover the pot for 3 minutes (7ig. -7f ' t:o form curds. Uncover r>ot, and sprinkle the remaining *olidifier {10 ml.) over surface ■)£ Boymilk.

4

Very slowly stir upper 2 cm. thick layer of curdling soymilk for 15 to 20 seconds, then cover pot and wait 3 minutes. Uncover and stir surface layer again for 20 to 30 seconds, or until all milky liquid curdles.

(If milky liquid persists pour about * 8 additional ml. of lemon juice, directly into uncurdl^dportions and stir gfntly until curdled).

Place cooking pot next to settling container in sink. Gently press finemesh strainer into pot and - allow several cups whey to collect in it. Ladle all of this whey into settling container to re-moisten 'lining cloths (Fig. 7g. ) set •trai-' ner aside.

Ladle curds- and any remaining whey into settling container one layer at a time. Ladle gently so as not to break curds' fragile structure <Fig. 7h). Fold edges of cloth neatly over curds (Fig. 7i), place a lid on top of cloth (a small board or flat plate will do), and set a J to 1 kg. weight on top of lid for 10 to 15 minutes, or until whey no longer drips from settling contai­ner (Fig. 7j).

7h)

Pill pressing pot, a large basin or sink with cold water. Remove weight and lid from atOfrt tofu, then place container holding tofu into baain of water (Fig. '7k ). Slowly invert container, leaving cloth-wrapped tofu in water-lift out container. While it is still under water, carefully unwrap and cut tofu into halves. Allow tofu to remain underwater for 3 to 5 minutes, until firm. To lift out slip a small plate under each piece of tofu; drain briefly (Fig. 7L). Store tofu in a cool place until ready to serve. (If not to be served for 8 or 10 hours, store under cold water).

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VARIATIONSVariating in the method were applied in the experiment to increase the yield, to improve the quality, to facilitate the process or to make the method applicable at hone level.1. The beans were dehulled after soaking.

Result; no improvement in the taste, lower yield.2. The beans were soaked and boiled in a 0.5c/o NaHCO^ solution to

destroy the trypsin inhibitor and improve the flavor.Result; More solidifier was neccssary and the tofu was too soft;

no improvement in the taste.3- Whole soybeans were pressure-cooked for 20 minutes before grind­

ing.Result: No formation of curds,

4. A handmill was used instead of an electrical blender and the yield was then evaluated.Result: see fig.8

Fig. 8Composition Analysis of Dry Bean, Okara & Tofu from Coker Variety Involving Blender & Handmill as a Grinding Elemnnt.

GrinderWt .

c

Moi st

lomposi

Prot.

tion1

Fat

result

C-rb.

wiCrude Fib. Ash

Comment on Tofu

Blender

Dry bean 150 6.8 37 7 1C, 1 2 0 . 4 1 2 . 6 4.4 Very white, soft, mild lemon juice taste.

Okara 238 82.1 5-3 2 . 6 5.5 3.9 0.6

Tofu 360 79-3 11.3 5 . C 2„7 0 . 1 0.8

Hand-mill

Dry bean 150 6 <■ 8 37-7 1C . 1 20 . k 1 2 . 6 4.*4 White,slightly firm, lower tofu yield, stranger lemon juice taste.

Okara 200 8 2 . 1 5-3 2 , I 5.7 4.0 0 .8Tofu

|278 7 6 .6 13*0

!7,3 1 < 9 0 . 1 1 . 1

Fig.8 shows that good resuj.ts- can.be obtained with a handmill.5- Vinegar was used’-as a coagulant instead of lemon juice and

the two products were then compared (Fig.9 )I ')

I\ ,

Fig. 9;1

Composition. Analysis of Drybea^ Okara & Tofu from Coker

Variety Using Lemon Jiice & Vinegar.

Coagu­lant

!« *

1.N Wt. Mois.Cc

Prot.

ResultjmpositFat

$lon I Crude CarL J Fiber Ash

Comment on Tofu

24.6 ml

Vinegar4.5#

iDr^b^an 1^0 6.8 37.7 18 „ 1 20.4 1 2 . 6 4.4 White,very soft,

vinegar taste.~ r 'Oke.ra|

273 83.6 4.9 2.1 6. C 1 2.8 0.6- - ----i

Toifu 315 77.4 11.7 6.5 3.* 0.1 0.7»

Drybean 150 6.8 37.7 18.1ji

20.1 12.6I 4.4 White, slightly firm, lemon juice taste.

30 ml lemon * juice

Okrra 260 84.3 4.7 2.1 5*! 2.8 0.6

Totfu)(

275 7 6 .3 13-3I ”

1. 0.1 1.2'■ ■■!■■■ .—i 1

|Better results are obtained with l<bn juice.6. The ground beans were pressuroooked for five minutes.

Result: White, well textured, od taste.7 . Five varieties of beans were pcessed and evaluated.

The results are summarized in e following table (Fig.10)

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Fig. 10Composition of 5 Varieties of Soybeans in Tofu Processing with 20 ml Lemon Juice Coagulant and 100 gm of Dry Beans.

Variety Moi sture consent.dryb.can.

Weight of t

soaked be^h

he proc

Okara

ucts (gn

Sovmilk

0

TofuComment on Tofu

Kaland 7.6$ 233 122 720 268 Firm,whiter,slight lemon juice taste; gives the highest yield of tofu.

Am soy 8.4$ 228 122 700 222Slightly firm, less white than others, mild lemon juice taste.

Boarder 8. y/0 222 135 720 220Very soft, white mild lemon juice taste

Clark 63 7 • 9 °/c 246 143 700 218Very eoft#white, slight lemon juice taste.

Coker 8 .2 °/o 24 0 120 695 200Firm,white, slight lemon juice taste.

TOFU UTILIZATIONA few recipes were experimented; some are typically Ethiopian, others were suggested by W.Shurtleff and A.Aoyagi in their books. But those recipes are only examples -nd an experienced cook should use his/her experience, art and inmaginatlon to invent new recipes.

TOFU SAUCETofu 150 gmOnions (sliced) 50 "Oil 20 mlTomatoes 100 gmSalt to taste

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1. Cook the onions with a little water ovay low heat, stirring constantly until brown.

2. Add the oil and fry the onions for a few minutes.3- Add the chopped tomato and cook for ten minutes, stirring and

adding water if necessary4. Add the mashed tofu and cook for a few minutes.

Note: According to taste, any spice could be added: pepper, chilies, berberrie et^...This sauce can be served with spaghetti, rice or injera.

TOFU OMELETTofu 300 gni©il 15 gmEggs 3Salt to taste

1) Cut tofu in small cubes and fry in oil for 2 minutes or until golden brown on all sides.

2) Add the beaten eggs to cover the tofu pieces and fry bothe sides.

SCRAMBLED TOFUTofu 300 gmdil 15 "Eggs 3Salt to taste

1) Fry mashed tofu until lightly brown2) Add the eggs and scramble until firm

TOFU CAKETofu Butter Sugar Salt Egg

1000 gm 60 gm 50 gm3 gm 1

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1) Mix all ingredients thoroughly to form a smooth dough. Press the dough into a loaf pan.

2) Bake in a preheated oven (350 -c;

TOFU WOTTofu 100 gmBerberrie 7 "Onions .(chopped) JO u

Oil 15 "Water 85O ml

1) Cook the onions in a little water until golden brown.2) Add the oil and fry the onions for about 5 minutes.3) Add the berberrie and cook for about 10 minutes, stirring

constantly and adding water from time to time.4) Add the mashed tofu and cook for a few minutes more.

TOFU ASA WOT

Tofu 100 gmOnions (chopped) 30 "Oil 20 «Berberrie 12 "Mekelesha 2 wWater 850 mlsalt

1) Cut tofu in small cubes and fry in 10 gm of ail until golden brown.

2) Cook the onions separately with a little water until brown;add the rest of the oil and fry for 5 minutes; add berberrie and cook for 5-10 minutes with norae more water; add mekelesha and salt and continue to simmer, adding water, until well cooked,

3) Immerse the fried tofu pieces in the mixture and cook for 5 moreminutes.

Inu —

TOFU ALLICHATofu IOC gmOnions (minced) 30 "Oil 15 ..Turmeric 2 11Green peppers (without seeds) 20 "water S30 "Salt to taste1) Cook the onions in a little water untdJL golden brown.2) Add the oil and fry for 5-10 minutes.3) Add the mashed tofu, turmeric and green peppers.4) Add the remaining water and simmer until w-ell cooked,

TOFU WITH SPICES

300 gm of mashed tofu ore mixed with:a) 6 gm of salt orb) 6 gm of salt and 7 gm of butter orc) 6 gm of salt, 7 gm of buttor, 2 gm of berberrie.

EVALUATION OF THE DIFFERENT RECIPESThe products were evaluated by a pannel of 8 judges giving a score from 0 to 5 (5 being the best score)The results are summarized in the following table (Fig. 11)

Fig. 11 Tofu recipes evaluation

Tofu recipes

Tofu Sauce Tofu Omelet Scrambled Tofu Tofu Cake

Score out of 100

O 1o JL

52

Comments

Should be firmer

needs more spicestasteless, should be mixed with flour.

- 19

Tofu recipes

Tofu wot Tofu asa -wot Tofu allicha Tofu with salt

Score out of 100

73727166

Tofu with salt,, butter & berberrieTofu with salt and butter Fried tofuFried tofu with saltFried tofu with salt, butter and berberrieFried tofu with salt and butter

80

92< r» Oo

75

63

68

Comments

Flavor to be improved.Needs more onions, too spicy,

The spices could be added in the milk but much of the taste is lost in the whey and the tofu is too soft.

SHELF LIFE OF TOFU

If tofu is kept immersed in cool water and the water is changed every day, the product can be kept for four to six days in a cool place.

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CONCLUSIONS AND RECOMMENDATIONSi•

The study has clearly shown that TOFU can be easily prepared in .Ethiopia at tioma. l«ve 1 and with almost no investment.

Much more work should be done by the Institute in developingadditional recipe.* and in improving the processing, particularly the milk extraction. A small hana-press should bo developed.

In collaboration with I.A.R.as veil, more research should be •arried out to select additional varieties.

Finally, and this is the most important, the Institute, or any other appropriate agency* must circulate information and provide the ne&essary training in the areas where soybeans are cultivated.

UTILIZATION OF OTHBI SOY PRODUCTS Soymilk:

The soymilk can be sweetened and flavored to taste and used after cooling. It must be noted that the milk cannot be kept more than 12 hours at room temperature and has to be dsed fresh.

Meenu Mital (and al. , 1 9 7 6) rei:>orted an improved method in thepreparation of soymilk at home lesrel: Soak beans in water for 3 hours, reserve beansj add sodium metalisulphite (175 mg/350 ml) to soaking water, bring to boiling point, add soaked beans and cook for 10 mm.The seeds were manually dehulled and homogenized in an electric blender using the soaking water from the boiling-dehulling process; the slurry was steamed for 10 minutes. Two extracts were collected by straining the slurry through k folds of muslin, resuspending the residue in hot water (2 minutes) and straining again. The combined extractj strained through 8 foldA of muslin, was gently heated for 30 minutes. Two or three gms of sugar were added for 350 ml of soymilk and the volume was made up to the required extent to give the final ratio of 1 part soybean to 6 parts water.

The study also indicated that while soymilk as such is quited acceptable, its palatability could be further improved by blending with cowmilk at 1;4 propox’tion; the cost of the blend is estimated to be three times lower than that of cow milk.

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Okara;Three- r»<U.P-e£ were developed ,

OKARA POTATO PANCAKES Potatoes (coar&ely gifted) 150 gmOkara 130 gmEggs 3Onions (minced) 10 gmWheat flour 15 gmOil 20 mlSalt to taste

Place the p o ta to g r a t in g s in a cloth and’ extraot as much moisture as pos-sibie. Combine all the ingredients, mix well. Shape into rnall pattiel and fry veil on both side.

OKARA AND WHEAT BREADOkara 150 gmWheat flour 100 "Baking powder 5 "Oil 10 mlBlack eumim 3 gmSalt to taste

Mix the oltara, wheat flour and baking powder (or ersho) with a little water. Knead, add salt and cumim and cover. Le stand at room temperature until it raises. Knead briefly and allow it raise again. Press the dough in a loaf pan and bake for 30 minutes.

OKARA WITH EGGSOkara 1 7C gmMilk or soymilk 130 "Egg 3Oil ’ 12 mlSalt to taste

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Mix eggs, milk salt and okara thoroughly. Scramble the mixture in oil for about 3 minutes.For the evaluation of the okara products see Fig. 12

Fig. 12 Score & Taste Panel’s Comments on Okara Recipes.

Okara recipes Score out of 100

Comment

Okara and wheat bread 68 good flavor^ but breaks too easily in bits.

Okara - potato pancake 7 C good flavor & texture.

Okara with scrambled eggs 6b poor taste & aspect

More experiments should be done to develop additional recipes.

Whey;In the process of making tofu, whey is an inevitable by-product wiiich contains valuable nutrients; 9 percent of the protein originally found in the dry beans, plus much of the B vitamins and some of the natural sugars.The whey can be used as a soap, as a facial wash to remove make-up and, as a shampoo. It can also be used to fatten livestock. It can be used in place of water or milk when making bread, in cooking as a broth or soup stock,. Finally, let us mention that this soap is so mild and delicious that you can drink it as you would any re- f reshment.

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Experiments on Cheese Making with Soymilk and Cov; Milk

Those experiments were conducted with the assistance of a dairy expert from the Dairy Development Agency The aims of the experiments were the following:

- To produce a cheese with a longer shelf life than the tofu

- To produce a cheese cheaper than a ncrnal cheese made from cov; milk

~ To evaluate the acceptability of such cheeses and to determine the optimum ratio soymilk-cow milk..

Preliminary Remarks- The experiments were conducted in an experimental kitchen which was certainly not the ideal place to use. The temperature was continually variable. Objectionable odours were present. The presence of undesirable germs was possible. In spite of those negative factors, promising results wore obtained and will be discussed later on.

- Wooden and plastic settling containers (as shown in Fig. 8) were used-

- The soymilk used was prepared according to the "Illinois Process" described in section II of the present report.

- The cow-milk was partially defatted, down to 3»5?« of fat.

- Tentatives to evaluate various factors were made: coagulation time, draining time, yield, dressing, method of coagulation, etc.

The experiments made are summarized in the following table (Fig. 13)

Fig. 13 Preparation of Cheese Made from Soymilk and Coi/tnilk

No. 1 No. 2 No. 3 No. 4 No. 5 No. 6 No. 7 No. 8 No. 9 No. 10

Soymilk 5 1 10 1 2 1 2 1 1 1 1 1 1 1 1 1 1 1 1 1Cowmilk at 3*5%

fat 5 1 - i 1 * 1 - 1 1 - 1 1 1 1 250gm .Ayib*Temperature 30°c 8j°C 30°C 30° C £5°£ 30°C 31°C 30°C 24° C 30°CRennet 6C drops - 15 drops - - 12 drops C drops 12 drops £ drops -

Lemon Juice - , 2f0 cc - 6C cc 28 cc - - 50 cc 30 cc 30 ccCoagulation time 23 hrs 4 hrs 23 hrs 24 hrs 15 hrs 24 hrs 24 hrs 24 hrs 18 hrsDraining time 24 hrs 1 ly hrs 47 hrs 47 hrs 17 hrs 25 hrs 18 hrs 25 hrs 24 hrsWeight after draining 1980gm 22b7gm ll60gm 1105gm 270gm 685gm 580gm 380gm 360gm

Dressing Brine Brine Salting Salting Salting Salting Brine Salting Salting15 min. (2)

15 min. (2)

(3) (3) + Spic­ing (4)

+ Spic­ing (4)

+ Spic­ing (4)

(3)

(1) Instead of cowmilk, Ayib was used.(2) The preparation of the brine is described below.

Salting: with 2°/: of salt {2% of the weight of the drained cheese'.(4) 2# salt + pepper or berberrie.

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Preparation of the DrineWaterRefined salt Unrefined salt Candidum

1 1.165 gm lC^gm0„825gm.

Discussion of the table (Fig. 13) llo.l :

IIo. 2

ITo. 3 IIo. kITo. 5

IIo. 6

ITo. 7 8

IIo. 8 :

Ho . 9 : No 10 3

Excellent taste, good consistency and homogeneity, but too fat.Good consistency, flavour.

Taste acceptable but not enough

Excellent taste. Very good consistency and homogeneity.Excellent taste, but too soft and too acid.The procedure i3 practically the sane as in experi­ment No.2 except that the coagulation time was re­duced. The dressing was modified and the use of pepper or berberrie considerably improves the accept­ability of the cheese.This experiment is similar to experiment No.l. Dur­ing the dressing, pepper was used and this gives an excellent "Boursin"-type produce though slightly too fat.This cheese was kept in brine for 15 days. This quite acid cheese was appreciated by Ethiopians and tastes like local Ayib.Excellent product very similar to IIo. 6. Apparently, the yield is lower when lemon juice is added.Excellent product but with a lover yield.No coagulation was observed.

General Remarks;- Wooden settling containers give a poor texturej plastic containers should be used for better results.

- The shelf life was relatively short (maximum 3 days) and molding was rapidly observed. TDut when the pro­ducts are placed on a tray allowing an adequate air circulation and when the products are turned upside down 3 times a day, the formation of mold is con­siderably retarded.

- The use of brine instead of salt gives better results and delays the molding.

- A cheese placed in a refrigerator can be kept for 3 weeks or more.

- k coagulation time of 2k hrs. and a draining time of 2k hrs. can be considered as ideal and greatly faci­litate the work.

- It is certain that excellent products can bo made from soymilk and cowmilk (a ratio 4:1 will give a very cheap product).

- Because of the very poor hygienic facilities, the various trials can only give an idea concerning the finished products, particularly as far as the yield is concerned.

Further I’.esearch:To conduct valuable additional research, it would be

p ideal to have four small rooms 'Cm") for the preparation, draining, dressing, and storage. The rooms must bo ahsolutely clean and disinfected.

The experiment should be conducted with at least 10 litres of milk in order to determine and improve the yield, homogeneity, dressing, packing and cost of the products.The study should be completed by a marketing evaluation.

Other I'.esearch on Soya:i'any other products could be made from soya and the

following list is to be considered as a suggestion:- -Yogurt -Ilayonnaise -Uce Cream -Tempeh -Soy sauce -I'.'iso

FAT.T I I - V.rhole So yin i l k

Soya beverages are used as an infant food, as a replace­ment for -./hole milk for those infants who cannot tolerate milk. It can also be used in developing nations as c. single strength beverage to replace milk and provide the necessary high quality protein, sugars and fat that would normally be available in fluid milk. These products nay be sold sterilized or pasteurized

The protein content of these beverages may be IOC', soy or mixtures of soy and milk protein, or other vegetablo proteins.If whole soybeans are used, the natural soy oil will provide the necessary fats.

The loir cost of these beverages should make then competi­tive as a high-protein beverage in developing nations.

Haw soybeans are unpalatably bitter and have a low nutritive efficiency because of the presence of trypsin inhibitors (T.I,), hemoglutenins and other undetermined factors. Traditional soy­milk is accepted only by Asian countries but continuous research efforts are being made to improve these products (llofner, 1 9 6 5?Hand et al, 196^:5 liiller, 1 9 6 5; Smith at al, 19^6' Soybeanhas been used as an important source of protein in the diets of Oriental people for many centuries. However, bevera :e prepara­tion from whole soybeans has been quite limited in other areas, principally because of the undesirable beany or painty off- flavour and odour. The undesirable flavour and odour are prin­cipally caused by an enzyme syster.i, lipoxygenase [\I±21zens etal, 19^7^« The reaction takes places quickly whenever the beans are ground and exposed to moisture at temperatures below instant enzyme inactivation (Nelson et al. , 1971)

Soybean "milks" are conventionally made in the Orient by soaking, grinding in water, filtering to remove sediments and the heating of the extract (Piper and Horse, 1923). Although this process is simple, the resulting beverage has a distinct

- 2? -

off-flavour and oc’our. .Tumorous nod?.c^t;.or.a of this traditional Oriental iroccss h-'.vo boo :. _'c^orted to -partially in-irove those defects (Willcar ot al • , 7; lion ot al ,i:'?C; Al-ICiJiitaini, 1^71? Badonhop ot al , 1?7C). Those modifications iuprovcr’ tho flavour b.-.t go orally resulted in a low protein rccover/

Other attempts v/ere made; (liana et al. , 1964; Mustakas et al. * 1972; Lo, 1971; lliles, 1966. These methods use dehulled soybeans.

A decisive step forwards was probably made by Nelson, Steinberg and Wei (1976). The process named "Illinois Pro­cess" starts with hydration of the whole soybeans and inacti­vation of the lipoxygenase enzyme to completely prevent formation of any painty flavour. Thereafter, the beans are ground to a slurry and processed to the finished beverage without filtration, centrifugation or other loss of protein. The "Illinois Process" is shown in Fig«l4,

1.2.

Fig. l4 - Flow Sheet of Whole Soy'-war. i.ilk PreparationSoybeans Dry whole soybeans are sorted.Soak Soak over-night in tap water solution

of 0.5°/> IIaIiC03 (l;3 5! bean ; solution)3. Drain4. Blanch

5» Drain6. Add water 7• Grind

8, Heat 9- Homogenize 10. Add water

DrainBlanch in fresh tap water solution of0,5/6 IIaHC03 for j.3 minutes (l;3 : : ori­ginal bean : solution]Drain and tap water rinseGrind through hammermill with sufficient water to make 12, bean solids, first through 0 .2 5 inch opening screen, then through 0.028 inch.Heat slurry to 2CG°FHomogenize at 3500 psiMix slurry with tap water to adjust pro­tein content to desired level.

11 Neutralize Neutralize with 6il I-IC1 to pH 6 8 to 7.2

12. Formulate Add 5$ sugar, 0.2)j ITaCl, 0.02 > vanilin 0,007/4 starter distillate.

13. Heat Heat at 180°F14 . Homogenize Homogenize as above at 3500 psi15. Bottle Bottlel6 . Cool and store at 34°F.

In their research, ITelson, Steinberg and Wei have studied the influence of various factors in the preparation of soymilk.

- Tiypsin inhibitor destruction; Effect of soaking and blanching with and without NaHCOo, A 30-minutes blanch in 0.5?4 NaHC03 following an over-night soak would result in a beverage free from trypsin inhibitor.

- Lipoxygenase enzyme destruction: -T,/I:en raw tissue of the soybean cotyledon is damaged, tiie lipoxygenase enzyme as well as the lipid substrate ai'e liberated.When water is added, a reaction tahes place rapidly end produces a highly objectionable beany or oxidised odour and flavour. It was found that sound, whole, raw beans could be soaked for 3-12 hrs. prior to blanching without developing the beany flavour and off-odour. However, it is necessary to handle the soaked beans gently during draining and handling. Alternatively, whole, dry beans could be dropped into boiling water for hydration and blanching in one operation, but longer blanch times would be re­quired

- Sffect of NaHCO^ and over-night soaking; They have a definitively positive effect as regards mouth feel and colloidal stability.

- Effect of homogenization and interaction between first and second homogenization; The results indicated that with double homogenization, an important considera­tion seems to be a summation of the two pressures and should be about 7*300 psi.

- Effect of temperature at time of homogenization; The results indicate that a good product is obtained if the temperature before the first houogeni-zation is 200°F and between 60°F and 180°F before the second homogenization.

It was the "Illinois Process" which served as a guide­line in the present mark, and the general procedure was as follows, (Fig. 15)*

Fig, 13 - Flow Sheet for Whole Soymilk Preparation1. Soybeans

2. Soaking

3 - Drain k „ Blanch

5. Drain6 . Add water

7• Grind

91 0 .

1 1 «1 2.13.14. 13

HeatFormulate?Iotnogenize

FormulateHeatHomogenize3ottleCool

750gm cleaned, intact whole soybeans (Xaland variety) (7 .6/j moisture)Soak overnight in 2,250 ml of 0.5/ NaHC03 solution.Drain and rinseBlanch in 2,250 ml of G.5?-- NaKC03 solution for t-C minutes at 92°C.Drain and rinseAdd about 8 litres of water so as to have a milk containing 12jii solid.Grind through a Colloid I-ill (Fryma Toothed Colloid Hill MZ-3o/lt equipped with coarse toothed grinding elements) and recirculate until the suitable degree of fineness isobtained.Heat slurry to 92°CAdd ^30gm sugar and iCgr.: salt.Homogenize at 500 psi ^second stage) and 3.500 psi (first stage)(Manton Gaulin homogenizer Model 15M-8TA) Add flavouring Heat to 80°C Homogenize as above.BottleCool and store at 6°C.

VariationAfter step No.8, flavouring was added with the sugar and

salt; the product was homogenized only once (second stage

— 31 "■

1 500 psi { first stage 7 „ 000 psiy. The milk was found to be excellent.

Such a procedure saves time, material [storage tank) and energy (to heat the product before the sccond homogenization). Those factors are of great importance for a factory; neverthe­less an homogenization at such a high pressure could produce processing and technical problems

FlavouringA. Natural flavouring;

Various flavouring agents were used.a) Coffees for one litre of milk, extract from lOgm of

coffee.b) Tea ; for one litre of milk, extract from 7gm of tea.c) Orange juice; for one litre of milk, 100 ml of orange

juice.d) Vanilla; for one liti'e of milk, O.C33g® of vanilin.e) Bananas; for one litre of milk, 1ZZ&™ of bananas.f) Plain soymilk was also prepared.

Evaluation; The results are given in the following table (fig. 1 6 )

Fig. 16 - Evaluation of Soymilk 'natural Flavouring)

FlavouringAgents

Score (out of 1 0 0) Comment

Vanilla 63 -good flavour but disappears very quickly -thick, needs little sugar

Coffee 73 -good flavour but it does not last on the tongue

-thick and coffee is strongOrange 67 -too thick and not enough sugar

but good flavour

Tea 58-flavour is medium & disappears very quickly.-thick, needs sugar

Plain 72 -good tasteBanana very palatable but coagulates

after one hour.

- 32 -

The use of natural flavouring agents nearly doubles the cost of the soymilk; for that reason, soymilk was flavoured with artificial flavours, (Givaudan Dubendorf)

3 - Artificial FlavouringNine different flavours were used in the preparation

of soymilk, following the "Illinois Process". The flavour­ing agents were added after the first homogenization.

A first evaluation was made on a snail scale (the re­sults are given in the Table, Fig, 17) As very good re­sults were obtained, 1000 bo.ttles of soynilli (100 for each flavour) were prepared and sold in 3 Kebele with an attached cuestionnaire (see Annex 1.). 826 bottles of of litre weresold at 10 cent each and 52.0 questionnaires were returned (the result of that small marketing evaluation are compiled in the Table, Fig. 17)•

If tables 16 and 17 are compared one can see that thereis no significant preference for natural ci’ artifcial flavours.But the use of artificial flavours makes the process much easier. The use of natural flavcurs requires additionalequipment, and the flavour could change with the season, thevariety and the quality of the raw material.

Last but not least, artificial flavours are much cheaper than natural ones. Table 18 shows the dosage of the variousflavours and their cost per 2^0 cc, of millt. It must bepointed out that for natural flavours, only the cost of raw material is considered, without the additional extraction cost.

Pig. 17; Evaluation of Soymilk. Artificially Flavoured

- 33 -

Flavour

iLarge Sclae Small Scale

Score out of 100

Percentage of People Giv­ing i a core higher than

80

Score out of 100

Percentage of people giving a score higher than

80

Orange 75-6 63.1 76.0 75-*Passionfruit 88.4 85-7 76.0 . 66.0

Vanilla 84.4 73.4 .. 68.0 57. C

Raspberry 87.4 74.2 64.O 38.0

Strawberry 82. 6 70.7 68.0 42.0

Malty 85.4 81. • 62.0 36.*Banana 83.2 77.0 68.0 42.0Mango 80.0 78.0 68.0 56.0

Coffee 85.4 89.1 l 66.0 40.0

Plain 74.0 65.7 f

1

*♦6.0 43.0 i

- 34 -

Ta1»le 18: Dosage and Cost of Flavours in Soymilk

Flavour

Artificial Natural

Dosage Per 100 1

Cost per 250 cc of milk

Dosage per 100 1

Cost per 250 cc of milk

Plain - - - —

Vanilla 100 gi, 1 0.65 cents 3*33 gm about 4 centsBanana 100 " 0.35 " ll.7kg(po0led) " 3 centsOrange 100 » 0.575 " 9.lit (Juice) » 4 "Coffee 50 " 0.9 " 1kg " 2.5 "Tea - - 700 gm 11 2 11

Passionfruit 100 " 1.20 cents - -Strawberry 100 » 0.65 " - -Malty 120 " O.54 " - -Mango 120 » 0.72 " -Raspberry 100 " 0.75 " — —

- 35 -

Comments on Tables l6. 17 and 1 :1. The evaluation of soymilk with natural flavour and of

soymilk with artificial flavour was do::.e by approximately the same pannel.

2. There is no important difference between the organoleptic evaluation of soymilk prepared with artificial or natural flavours.

3. In table 17, the score giver on a large scale is generally much higher than the one gi->. en on a small scale. It is probably due to the fact that on a large scale the milk was sold to people having a lower income and glad to buya good and cheap product. One can assume it is a fair estimation of the acceptability of the products by a large public.

4. Only one discordance is see •. in table 17 J on a large scale, orange flavoui’ receives the lowest score, though the highest on a small scale. In case of production of flavoured soymilk, it is the cost of the flavour that should guide the processor as well as the acceptability.

5. The artificial flavours co: t between C and 2„5 times less than the natural flavours. Consequently, it is recommended to use only artificial flavouring agents

Gome Properties of the V/hole G ryr.iilk1 The chemical analysis for the milk and the raw beans gives

the following results.3ea:i& ililk ( sweetened )

Moisture 7.':% 88.5$Ash 5 1'X' o. 5$Fat 21 0$ 0.8$Protein 34. 3';:; 3 • 4$Crude fiber 1 2 .6$ 2.4 $Carbohydrates IS. 6$ 4. 4$Calox’ies (per lOOgr.'.) 405 kcal 38 4 :

* Calculated by difference.

Those results are not satisfactory and differ considerably from the theoretical results, Additional analysis should be made very carefully In particular, the calculation of carbohydrates content cannot be made by difference.Shelf life and organoleptic properties. Standing times at 4°C for as lone as 7 days had no effect on the organo­leptic properties.

Colloidal stability. The milk remained absolutely stable at U°C for one week.

Protein arid solids recovery; ;!elsor. et al. found that ll°/> of soluble solids v/ere lost during the soaking, blanching and rinsing. But they found that the process did remove bean constituents other than protein, such as oligosacch­arides. Substantial extraction of oligosaccharides during hydration and cooking of the soy beans was also demonstrated (Ku, 1>72).In the present study, the water used for blanching, soak­ing and rinsing was analysed and indicated that about 5% of soluble solids (read by rofractometer) were lost during the processing. It is less than half of the figures in­dicated by ITelson et al.

Modification of the "Illinois Process11In order to avoid a loss of 5a’ or nore of oligosaccharide additional trials were conducted.a) The beans were blanched in the soaking water. The same

blanching water was thei used to continue the process, and to avoid any loss. The obtained product was found too sweet but without any objectionable taste.

b) The procedure was repeated but adding 2 and 3°/° sugar instead of 5 *

- 37 -

' The reading by refractoneter gave the following results:Whole milk with 5$> sugar : 12.5°BrixProcessed milk with bl an- Qching water + 2°/o sugar : 11.0 Brix

Processed milk with blan-ching water 3°o sugar : 11.5 Brix

c) P.emarks sThe processed milk using the blanching water withy/0 of sugar was the best accepted. It also represents a significant reduction in the cost oi the milk.

d) Additional research; Before recommendation for the adoption of the modified Illinois Process can be made, it is necessary to make a complete analysis of the two milks and to compare their organoleptic acceptability, shelf life and stability.It is certain that such a modification brings various advantages:- less equipment, less handling and less sugar. Nevertheless the modified milk is slightly more viscous but well accepted.

D. Preparation of Blended SoymilkThe calories content of the soymilk van found to be low in particular for babies and some trials were conducted to prepare a blended milk„ The soyi.iilk was mixed with Niger seed, Sesame seed and Sunflower seed drinks. Before blending, each beverage was prepared separately as follows;

Soyr.il 11c: Illinois ProcessNiger Seed Drinks 250gm of soeds are finely pounded with 700 cc of water and passed through a sieve.Sunflower Seed Drink: 250gm of seeds are cooked with300 cc of water until tender. The cooked seeds are finely pounded with 1000 cc of water and passed throughsieve.

The soymilk was blended with various amounts of oil­seeds drinks and evaluated. The results are summarized in table 19.

Table 19 : Evaluation of Blended Soymilk TheoreticalCalorie Consent

Discussion of Table 19The scores given in table 19 show that blended milks with

adequate ratios are more accepted than plain soymilk. One can also observe that the calorie content is increased. But as mentioned earlier the analysis of the soymilk is not satis­factory and it is certain that the calorie content of the plain soymilk is higher than 38. 4 ICcal per lOOgm.

To produce a suitable blended drink further trials must be repeated and the following combinations should be investi­gated o

- Soymilk- Soymilk- Soymilk

Niger seeds, ratios- 4 s 1 and 5s1 Sunflower seeds, ratio;- 3:1 and 5s1 Sesame seeds, ratios- 4:1 and 5s1

- 39 -

The soymilk should be prepared following the modified Illinois Process,

Research should be conducted to process the two milks at the sane tine.

The cost of the various blended nilks should be calcu­lated. And most important, the chemical analysis must be improved. It must be realized that the carbohydrates con­tent cannot be given by difference.

12, Cost Evaluation of the Soymilk repared Following the Illinois ProcessThe writers have found it to be important to estimate the cost of whole soymilk.The estimation is based on the production of soymilk by a small factory with a capacity of 5000 litres of milk per hour working 8 hours a day, 30- days a year.

1. Flow Sheet

Operations ifecessary Equipment-Sorting & Clean- Conveyor belt­ing-Soaking

- Blanching

-Psinsing-Grinding

0 concrete tanks (2000 l) 1C basketsGteain generator 3 Cooking tanks(2000 l)1 Concrete tank (3000 l)1 Colloid Mill (coarsed

toothedj1 Mixing recirculating

tank (600C l'1 Colloid Mill ’cross­

wise toothed)3alari.ee C/F

Cost Estimate (Eth. Birr '10,000

2 0 , 0 0 0

50,000 125,000

2 , 0 0 0

35.000

25.000

AZjS S . i__

.202ioog_

- 40 -

Operations

■ Cooking -Homogenization

-Cooling

-Filling (250cc Plastic Bags)-Storing

Cost Estimate Necessary Equipment (Eth.Birr)

Balance B/F ...... 302,0002 Cooking tanks (6C00 l) 130,0001 Homogenizer '!5000 l/hr)with tungsten carbide valve 222,000

1 chillec. water plant 50,0001 Plate cooler 15,0001 Filler-Sealer 350,000

1 Cold Room (for 60,000 1at k°C) 180,000

Hiscella '.eous . 100,0001 ,267,000

3.

Dxpenditures (Estimated;- Equipment (F.O.Z.)- Shipment & Insurance- Installation & Training- Building

1,267,000 Eth.Birr 200,000 " "IOC,000 " "l i nn nnr1 11 11

TOTAL

Cost for 10,000 litrcss Soybeans (350 kg}Sugar (500 kg)Salt (20 kg)FlavouringChemicals

(10 kg) f 1 r\ i ~ '10 kg; Est.

Plastic bags (40,000)Labour charge (30 people) Est„ Equipment depreciation (10 yecirs / Building depreciation (25 years) Fuel (Est.)Maintenance [Sst„,Capital Interest 6}j

_1j.26Zi.92Q—:c Plastic Bags

It

510.00 Eth. Birr500.00 it it

30.00 It 11

250.00 II 1150.00

1 ,000.00 11 11150.00 II 11100.00 11 11

13 .0 0 tl ti50.00 II 1125.00 It it1 0. 00 11 it

2,680.00 tt tt

- Cost of a ?-50cc bag c ..7.2.,cents

4. Remarks- Transport, breakage and profit are not included in the mentioned price.

- If the modified Illinois Process can be followed the cost will be significantly reduced.

Sterilization of Soya MilkBecause the pasteurized soymilk can bo kept only for 24

hours outside a refrigerator, experiments wore conducted to sterilize the product.

a) Sterilization in bottlesThe soymilk was prepared by the "Illinois Process". The milk was bottled cold in 300cc bottles closed with crown corks. No flavour was added. The bottles were processed at 121°C for 15 minutes in a stationary retort gas heated and were completely immersed in water. The following table {table 20) gives the condition of the sterilization.

Table 20s Sterilization of Soymilk in Dottles

Heating Phase Cooling Phase

Time T° Pressure Time T° Pressure(min) (°c) ■ P 3 T't V * ° x 1 (min' (°c) (p.S.1 )

0 25 0 0 121 30.030 55 J * J 5 115 29 .040 65 7.0 Oyj 110 25.050 75 8.0 10 105 23.0Go 85 10 .0 20 96 1 6 .070 95 14.0 23 83 1 3 . 078 105 1 5 . 0 30 70 9.082 110 2 2 . 0 33 60 8.585 115 25 .0 35 50 6.090 121 20. 0 38 40 4 .0

Maintained for 15 minut e s 40 30 0

- h2 -

Discussion of Table £0- Because of the intei'iial pressure, counter-pressure was

applied during the process. It was done with compressed air and the air valve was operated manually.

- Fifteen bottles were processed of which eight were broken at the end of the process. It is believed that the break age was not due to an excessive internal pressure but to a too quick cooling in the beginning of the cooling phase and a bad distribution of the coooling water that entered into the retort through only one inlet (-£" diameter). It is also possible that the kind of bottle used was not appropriate.

- The heating time is too long and a retort with direct steam injection is doubtlessly more suitable,

- The sterilized milk was compared with a pasteurized milk by three judges where only palatability was considered. The sterilized milk had a more bean like flavour and the soya odour was more detectable. The sterilized milk is less homogeneous than the pasteurizod one, this is pro­bably due to precipitation of proteins. Nevertheless the product remains highly acceptable. The flavour and the odour could certainly improved by adding artificial flavours.

- Six bottles have been kept for a periodic evaluation (every 6 weeks). At the same time the milk was to be analized from bacteriological point of view.

- As soon as the retort is modified for steam heating, the experiment will be repeated with a flavoured milk.

- h3 -

b ) Sterilization in 450cc tinsFollowing the "Illinois Process" a soymilk at 12 percentsolid was prepared. The cans were filled hot (about 70 c)and processed in stear.1 in a £.fca.tionary retort.

The temperature in the center of two tins (one in the middle of the retort and the other at the edge) were record­ed during the process (Fig. 2l).

The retort was closed as soon as it is filled with thecans. When the temperature reached 95°C the vent valve was wide open for five minutes to ensure that all air is swept out of the retort so that no pookets of air remain among the cans. An air-steam mixture in the retort will otherwise cause under-processing. The bleeder was open during the entire process.

The same process was followed to sterilize a more concen­trate milk prepared following the "Illinois Process" but adding 50$ less water and twice as much sugar. The tempe­ratures recorded during the process are presented in table 22.

- 44 -

Fig* 21 - Sterilization of Soymilk in Tins

Time (in min.)

T° in the retort(°c)

T°in the center of a tin placed in the middle of the retort

T° in the center of a tin placed at the edge of the retort

0 65 39.5 39.13 78 39.0 38.2

Venting 10 94 50.0 47.815 95 73.0 6 9.O20 102 74.3 COf'-

25 112 85 7 82.730 119 92.7 97.835 124 99-5 96.74o 127 105 7 1 0 3 . 1

45 127-5 110.9 108,450 128. 5 114.7 112.553 1 2 8. 5 1 1 7 . 8 1 1 5 . 86o 129 12 0 .0 118.665 129 1 2 1 . 8 120.8

70 123 123.3 1 2 2 .6

73 120 1 2 3 .8 123.^80 34 98.4 99.8

Cooling 85 24 92.0 9 . 0SO 22 42.0 46.0

Fig. 22 - Sterilization of Concentrated MilLc in Tins

Time (in min,)

1T xn the Retort(°c)

T in the center of a tin placed in the middle of

the retort

T° in the center I of a tin placod at the edge of the retort

0 65 60. 5 61. 35 79 59^1 60. 210 92, 2 Kjl “v* CO 58.9

Venting 15 98 57 -h 58.6

20 9b 6 0, 2 61.4

25 105 66. 3 6 7. 230 114 72.5 73.135 121 79.2 79.6

38 125 m•c-\CO 83.8

hO 125 86.3 86.5

^5 125 93<6 93.650 126 100.0 100. 0

55 126 105.8 105.8

60 127 110.5 110.5

70 127 114. 3 114.275 128 1 1 7 . 2 117.180 128 119.5 119.585 123 121 5 121. 586 122 122 12290 67 115 116

Cooling 100 65 100 100 |105 40 3C GO110 24 55 55

- he -

c) Evaluation of the Sterilized Milks in TinsThe sterilized milks evaluated from the organoleptic point of view gave the following results.

Kind of Milk Score out of 100 Comments

Normal milk 65

Thick milk 49 Unpleasant smell and taste

d) ?.enarks and Further Research- The score given to the normal sterilized milk is practi­cally the same as the pasteurized milk.

- The heat penetration for the thick milk is much slo\ver and for this reason the milk is not acceptable. Never­theless an acceptable thick milk could probably be pro­duced in a rotary retort.

- Much more research should be done preferably in collabora­tion with specialized firms. A (U.H.T. High Temperature) milk could certainly be produced by the system which sterilizes milk at l4o°C for a few seconds. A thick milk could probably also be produced. Nevertheless the container will remain a major problem and this should be studied at the same time. For information the following firms are involved with the U.H.T. milks- Alfa-Laval,A.P V,, Stork, Laguilhorre, Sordi, Rossi-Catelli, Cherry Burrel, Actini; but this list is not exhaustive.

- Shelf lifes The processed sterilized milk will have to be evaluated every six weeks from an organoleptic and microbiological point of view.

PART III: SPRAY DRYI1IG 0? SOYMIL

Principles of Spray DryingIn this process the liquid to he dried is ejected from

a nossle as a fine spray into a crying chamber. ither pre­ssure nozzles or centrifugal ator.izers can be used for develop­ing the spray. The surfacc of the liquid is thereby enlarged enormously, up to 1,000 square meters per litre. Consequently, the drying process is extended to a much larger cui'face and can be completed in a very short time.

Hot air (heated by steam, burner, or electricity) is led into the drying chamber, where it converts the droplets into a fine powder in approximately o.ie second and tal.es the liquid from the droplets as water vapour. The heat content of the drying air is thus utilized for evaporation, and subsequently the temperature of the air decreases towards the saturation temperature.

A mechanism for separating the powder from the air is essential, and the separation is usually done in a dynamic cyclone filter from the bottom of which the powder is collected while the moist air is passed out of the top of the cyclone.

It is generally assumed that the product temperature will remain close to the wet bulb temperature of the r. grounding air until most of the moisture has been removed because of the rapid evaporation of water,

Factors Influencing the Atomiz- tionIn brief the following fictors influence the atomizations- Increased viscosity gives increased particle size.- Reduced surface tension give3 smaller dx’oplets.- Drop size increases with the density of the solution.- Smaller orifices of the nozzles give smaller particlcs.- Greater pressure give smaller drops.

- Increased tangential velocities give more uniform particles. Tangential velocities are more effective in liquid break-up than axial velocities.

- Lesser viscosities give more uniform particle size distribution and finer average particles.

- Reduced pressures give poorer film break-up.- Spray driers that are larger in height and diameter

allow atomization and drying of larger particle sizes.

A review of spray drying has been written by Seltzer and Settelmeyer.

3<■ Description of the Equipment Used in the Experiment 'Fig. 23)The equipment used was an Anhydro Laboratory Spray Drier

with the following characteristics;Chamber diameter 1 meterAtomizer speeds maximum $0,000 r.p.m.Air heater 3 to 9Evaporation rate at inlet-out let temperature 300°/90°C 7 . 51cg/hr. (Fig. 24 )

2Compressed air pressure 4ltg/cmThe drying chamber is cylindrical with curved top and

conical bottom. All inner surfaces are entirely of stainless acid-resistant steel. The drying air is heated by electricity. The heater can gradually heat the air to temperature between 125°C and 300°C.

The spraying in the chamber can be developed by pressure nozzle or by centrifugal atomizer.

i ) Centrifu<.;al ator.:izcr; In this case the liquid is led to the top of the atomizer from where it passes through the atomizer wheel. The revolving speed of the wheel can be regu­lated according to the viscosity of the feed and to the particle size desired.

The flow of the liquid is adjusted in order to main­tain the desired temperature of the exhaust air.

- 48 -

Fig. 23

-49 -

1. Air outlet2. Air outlet thermometer3. Feed bowl4. Centrifugal atomizer5. Air inlet thermometer6. Fan7. Air inlet8. Compressed air inlet9. Nozzle ator ''er

10. Powder c o l le c t o rV

Water Evaporation ( K G / H ) as Function of

the Inlet Temperature (C ) Outlet Temperature 90

/

- j — r

2 0 0 2 50T "

300

- 51 -

ii) Pressure nozzles ’//lien using the nozzle atomizer, the liquid is dispensed as a mist by means of compressed air. The nozzle is situated in the middle of the drying chamber, spraying upwards, thus giving the particles tho longest tra­jectory obtainable in the compact :>lant and permitting the production of coarser particles. The air pressure is chosen according to the viscosity of the liquid and the quantity of water to be evaporated (fig, 25)°

4r Pesearch on Soymilk Spray DryingA process for preparing a soluble dried soymilk pov/der

is highly desirable because the dried product potentially has both a longer shelf life and lower transportation costs than the pasteurized soymilk. Spray crying has been successfully used to dry soymillcs (Mustakas et al. , 1971$ Van 3uren et al , 1964). However, reconstitution of powders is often poor because of physical and chemical changes that occur during the drying process. A high fat beverage, such as whole milk or full-fat soymilk, is often difficult to spray dry and reconsti­tute and may have limited storagi life because of lipid deter­ioration or other undesirable changes in the spray drier or dui'ing storage (Lampert, 1970? Jbb et al. , 197 1 ) •

Nevertheless it is important to process whole soybeans ’instead of a defatted product) since many areas in the worlddo not have facilities for expel.i ing or extracting oil.

Hand et al, (1964) have st .idied the problem in Indonesiaat the plant equipped by UNICEF. The best result was obtained with water extracted soymilk, but the process requires an important equipment including dosintegrator, filter press, heat exchanger, evaporator. The spray drying temperatures inlet- outlet were 204°/93°C.

The Protein Dispersibility Index (P.D.l) of the spray dried powder is altered during spray drying. Aninlari et al, (1977) have studied the effect of various factors changing ths

-52- Fig. 25

QUANTITY OF LIQUID AS FUNCTION OF

TH E V ISC O SIT Y AT DIFFERENT PRESSURES

.P GAUGE PRESSURE !N KG/CM^ V ISCOSITY IN E

- 53 -

P.D.I. The soymilk base was prepared using the Illinois Process described by Nelson et al, (1976). The procedure was modified by deiiulling the beans as described by Spata (1973) « The NECRO- ITIEO spray drier was used to spraj dry full-fat soy beverage base. The powder could be reconstituted without elaborate mix­ing. The inlet temperature was lc 3°C and the outlet temperature 90°C. The P.D.I. of the original untreated spray-dried soymilk base was 50. It was increased to 60 when the base was homogen­ized at 5.500 p.s.i. instead of 3 300 p.s.i. Treating the base (pH 7-2) with Sodium bisulfite instead of sodium bicarbonate increased the P.D.I. from 50 to 70. The P.D.I. increased fror.i 47 to 60 when the pH of the soymilk was increased from 6.5 to C. 5. The effect of the above factors was not e.dditive and PDI was 7 1 * 7 - 1.3 when all favourable factors were combined.

5• Experiments ConductedThe millc to be spray dried ./as prepared following the

''Illinois Process" already mentioned in part II and with colcer variety. The equipment used was described in part III. Only centrifugal atomization was used in this study and a constant speed of 50.000 r.p.m. was applied.

a) Factors influencing the Protein Dispersibility Index(P.D.I.)g Various factors that could influence theP.D.I. were considered in the present study.- Influence on the temperature.- Influence on the horn genization pressure- Influence on the chc licals used for soaking onblanching.

- Influence on the soe.ium bisulfite.That was added immediately before the spray drying.

- Influence on the pH that was adjusted with NaOH 5N.All the results are summarized in table P.6.

Fig. 26 Spray Drying Conditions

SampleNumber

Homogeniza­tion Pres­sure (p.s.i t

Chemical Used for Soaking and _ IZlanch-*?*» rr-is

pHInlet/Outlet Temperature °C P.D. I

Hoisture Content of the Po'-der

1 5500 Na co„ 7.4 205/90 84.95 0.28^

2 5500 Na H CC^ 7.4 225/90 79.54 1.69?6

3 5500 Na H CO^ 7.4 160/90 56.91 c.83?6

4 3500 Na :: CO 7.4 205/90 91.77 c: f'fl/ •s> « J} 07J

3 7000 11a i-: CO., 7-4 225/90 8 6 .8 1 1 c4i.'-a. 0 r / -

5 3500 IIH4 :: cc3 7.4 205/90 51.77 - J>/-

7 5500 IE4 :: CC3

:-7.5 nili-Mole UsI-SO J

7 . 0 205/9C 85.63 1 li. x, ~0/-v

8 7000 iie co0 7 • 4 205/SO 77-75 1.1256

1 5500 1-4 3 C03 7.5 205/90 8 1.02 2. 24f610 5500 IIHi H C0„ 8.0 205/90 81.33 0.27f;S11 5500 in-:,. co3 9.0 205/90 79.88 c. 2796

RawBeans 75.26

- 55 -

b) Determination of the Protein Dispersibility Index (PDI).References; l) Official Methods of Analysis (A0AC)l971.

2) Smith and Circle "Soybeans: Chemistryand Technology", 1571, Avi Publishing Co.

The method is applicable to ground soybeans, full-fatsoy flours and grits.The procedure is as folljwss-1. Weigh 20 - O.lgm of soy product.2. Fill a 300 ml volumetric flask with, distilled water

at 25° + 1°C. Pour about 50 ml of the water intoa Blender cup, 'Water-dispersible protein is re­lated to tcnpei’ature so that the Blender cup should be at room tenperati re) Transfer the weighed sample quantitatively to the Blender cup. Stir with a spatula, as f''r a paste. Add remainder of water in increments, with stirring, to form a smooth slurry. Use last of water to rinse spatula and Blender Cup walls.

3. Turn Blender on wit 1 switch in high position, and gradually adjust ths variable transformer to the point indicated by the water standard tit 8^500 rpn. Blend at this speec for 10 minutes.

k „ Remove the Blender cup, and pour the slurry into a 600 ml beaker. After the slurry has separated, decaout or pipet a portion into a 50 ml centrifuge tube, and centrifuge fox’ 10 min. at 2,700 rpra.

5. Pipet 15 ml of supernatant liquid into Kjeldahl flask, and determine protein using the Kjeldahl method.

- S ) x N x 0.014 x 100 x **.25

Height of samplewhere 3 = ml of alkali back titration of blank.

5 = ml of alkali back titration of sample.N = Normality of alkali.

Protein Dispersibility Index =% water dispersible protein x If'J

70 Total protein

Reconstitution of the MilkA proper amount of water was added to the powder to obtain a milk containing 12°/o solid

The water was added in small amount at a tine. Cold water and hot water were used but no difference in the recon­stituted milk was observed- In each case the product dis­solved relatively well but some particles still remainedin suspension or precipitated.

The organoleptic qua.lit.ies of the reconstituted milk are acceptable and very similar to the fresh soymilk but with a detectable powdery taste.

6. Calculation of results;. (B°/o water Dispersible protein = —

Discussion ol' Table 2o- The P.D.I. is much higher than expected and the analysis

should be repeated by a specialized laboratory.- Experiments 1, 2 and 35 as expected, a better P.D.I.

is obtained with an inlet temperature of £05°C.- Experiments 3, h and 5; in contradiction with the

literature, the highest P.D.I. was obtained for an homogenizing pressure of 3500 p.s.i.

- Experiment 6,7s The addition of IJaHSO increase the P.D.I.

- 57 -

- The utilization of HH^HCO^ instead of HaliCO did not seem to increase the P.Bo I. (experiment h and 6).

- Experiments 3, 9, 10 & 11; the influence of the pH was negligable.

Ghelf LifeThe samples were sealed in aluminium bags under vacuum and are to be analysed every 3 months.

BIBLIOGRAPHYAL—KISHTAINI, S.F, 1971» Methods of Preparation and

Properties of Water Extracts of Goybeans. Ph.D. thesis, University of Illinois, Urbana, 111.

ALLAN K. SMITH, Ph.D., SIDNEY ... CIRCLE, Ph.D., Soybeans: Chemistry and Technology Vol.I, Avi Publishing Company Inc., 1972.

AimiLAP.I, M., PERRIER, L.K., ar d NELSON, A.I., 1977.Protein Dispersibility of Spray Dried i/hole Soybean Milk 3ase: Efiect of Processing Variable.J. of Food Science Vol. 42, No.4.

BADEIHiOP, A.F. and HACKLER, L.i . 1970. Effects of Soaking Soybeans in Sodium Hydroxide Solution as Pretreat- rnent for Soymilk Production. Cereal Scf.. Today 15s34.

HAFHEF, F.I-I. 1965. No more milk.Soybean Dig. 25(3}: 22.

HAND, D.B, , STEINKRAUS, K.H. , VANBUREN, J.P., IIACKLER,L.n. el RAW I, I. and PALLESEN, II.F. 196 . Pilot Plant Studies on Soymilk Production, Food Technol. 10; 139.

JOHNSON, K.W. and SNYDER, II.E. , 1978. Soymilk: A Com­parison of Processing 1 athods on Yield and Compos­ition. Journal of Food Science 43:349-

ICON, S , , WAGNER, J. R. , GUADAGNI, D.G. and HORVAT, F. J . 19 7 0. pH Adjustment Control of Oxidative Off-flavours During Grinding of Raw Legumes Seeds. J. Food Science 35(4):3^3.

ICU, S. 1972. Extraction of Oligosaccharides in Processing Whole Soybeans. Ph.D. thesis, University of Illinois, Urbana, 111.

LAMPERT, L.M. 1970 "Modern Dairy Products," p.255* Chemical Publishing Co., Inc. New York.

LO, X.S. 1971. Process for Preoaring a Soybean Beverage. U.S. Patent 3,563,76-2.

MARSHALL, W.R. and SELTLER, E. 1950. Principles of Spray Drying Fundamentals of Spray-Dryer Operation.Chen;. Eng. Progr. 46, 501-508. II. 46, 575-584

1'IAP SHALL, 17.R. , J. 1954. Atomization and Spray DryingNew Yorks Am. Inst. Chera. Eng. Monograph Series 50, Mo.2.

- 59 -MEENU MITAL, M.A. QUADRI, H,S. KISHAWAH and I.C. DATTA,

Studios on Preparation, Standardization and Organo­leptic Scoring of Soymilk, Journal of Food Science and Technology, Vol. 13 > 1976.

MILES, C.P. 1966. Process of Producing Milk from Soybeans. U.S. Patent 3,28S,6l4

KILLER, H.W. 1 9 6 5. Meeting the World1s Nutritional Heeds with Soymilk. Soybean Dig. 2 5(8);19.

KUSTAICAS, G.C., ALBRECHT, V.J., BOOKWALTER, G.N., SOHNS,V.S. and GRIFFIN, S.I. 1971. New Proxoss for Low-cost, High-Protein Beverage Base. Food Techno1. 25: 535

MUSTAICAS, G.C., ALBRECHT, 17, J. and BOOKWALTER, G.N. 1972. Production of Vegetable Protein Beverage Base.U.S. Patent 3,639,129

NELSON, A.I., STEINBERG, M.I. and WEI, L.S., 1976. Illinois Process for Preparation of Soymilk. Journal of Food Science. 4ls57

NELSON, A.I., WEI, L.W. and STEINBERG, M.P. 1971. FoodProducts from Whole Soybeans, Soybean Dig.3 1 (3 )02

PIPER, C,V. and MORSE, W.J. 1923. "The Soybean." McGraw- IIill Co., Inc. New York.

RANZ, W.E. and MARSHALL* W.R. 1>52. Evaporation fox' Drops.I Chen. Eng. Progr. 48, l4l-l46. II 43, 173-130

SELTCER, E. , and SETTELMEYE ', J.T. 1944. Spray Drying of Foods, Advance in. Food Research 2,399-520

S7ATA, J.M. 1973 • Development of a Dry, Stable Soybean dal for India. Ph.D. thesis. Department of Food Science, Univ. of Illinois at Urbana Champaign.

SMITH, A.K. and 3ECKEL, A.C. 1946. Soy or Vegetable Milk. Soybean Dig. 6(7 )518

VANBUREN, J.A , STEINKAUS , K.H. and IIACKLER, L.R. 1964.Indices of Protein Quality in Dried Soymilk. Journal of Agr. Chem. 12:524

WEBB, B.H., JOHNSON, A.H. and ALFORD, J.A.(ed) 1974."Fundamentals of Dairy Chemistry," p.650. Avi Publishing Co., Inc., Westport, CT.

WILKENS, W.F„, MATTICK, L.R. and HAND, D.D. 1 9 6 7. Effect of Processing Method on Oxidative Off-Flavours oJ Soybean milk Food Technol. 21;l630

WILLIAM SHURTLEFF and AKIKO AOYAGI: The Book of Tofu Vol. I,1975, Vol. II 1979, New-Age Foods Study Center, Lafayette, CA 945^9.

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