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

-46-

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