ABSTRACT
Locally brewed beer (sorghum beer) is an indigenous alcohol average. It is produced mainly from sorghum grain (Sorghum vulgare ) and
the process of brewing involves malting, mashing, souring, fermentation
and packaging. Locally brewed beer without hops has a short shelf-life.
The aqueous extract of a tropical plant, bitter-leaf was used as the
hop .Two type of drink were produced, one with hops and another without
hops. Chemical analyses were carried out on both drinks, which gave a
significant (p?0.05) difference. Sorghum beer with hops has a total
acidity of 0.562±0.03, fixed acidity of 0.203±0.001, Volatile acidity
0.360±0.02, PH 3.93, specific gravity 1.042±0.003, total dissolved
solids 1.12×105ppm, total suspended solids 1.65×105ppm, ethanol content
of 3.43±0.03 respectively. While sorghum beer without hops has a total
acidity of 0.652 ±0.002, fixed acidity of 0.176±0.002, volatile acidity
of 0.476±0.03, PH of 3.50 specific gravity of 1.021±0.003, total
dissolved solid of 1.15×105ppm, total suspended solids of 1.5×105ppm and
an ethanol content of 3.65±0.02. The microbial count for sorghum beer
with hop had no growth of E.coli, streptococcus and staphylococcus but
aspergillus was present from the 4th day and heaviest on the 8th day.
While the drink without hop had growth of staphylococcus and aspergillus
which was seen from the 2nd day and heaviest on the 4th day but E.coli
and streptococcus was absent. From the results, the drink with hops
could keep for a longer period of time than the other drink without
hops. Thus, the aqueous extract of Vernonia amygdalina could extend the shelf-life of locally brewed sorghum beer. TABLE OF CONTENT
CHAPTER ONE
1.0 INTRODUCTION
1.1 AIMS AND OBJECTIVES
CHAPTER TWO
2.0 LITERATURE REVIEW
2.1 GENERAL DESCRIPTION OF CEREALS
2.1.1 GENERAL CHARACTERISTICS OF CEREALS
2.2 SORGHUM
2.2.1 GENERAL DESCRIPTION OF SORGHUM
2.2.2 SCIENTIFIC CLASSIFICATION OF SORGHUM
2.2.3 GRAIN COMPOSITION AND NUTRITIVE VALUE
2.2.4 CULTIVATION AND USES
2.3 MILLET
2.3.1 GENERAL DESCRIPTION OF MILLET
2.3.2 BOTANICAL CLASSIFICATION OF MILLET
2.3.3 PEST AND DISEASES OF MILLET
2.3.4 USES OF MILLET
2.4 BREWING
2.4.1 HISTORY OF BREWING
2.4.2 BREWING PROCESSES
2.4.2.1 EUROPEAN BREWING PROCESS
2.4.2.2 INDIGENOUS AFRICAN BREWING PROCESS
2.5 RAW MATERIALS FOR BREWING
2.5.1 STARCH SOURCE
2.5.2 ADJUNCTS
2.5.3 WATER
2.5.4 HOPS
2.5.4.1 CHARACTERISTICS OF HOPS
2.5.4.2 TROPICAL HOP SUBTITUTES FOR BEER BREWING
2.5.5 YEAST
2.5.5.1 BAKER’S YEAST
2.5.5.2 BREWER’S YEAST
2.6 BIOCHEMISTRY OF BREWING PROCESSES
2.6.1 MALTING AND KILNING
2.6.2 MILLING
2.6.3 MASHING
2.6.4 SOURING
2.6.5 WORT BOILING
2.6.6 FERMENTATION
2.6.6.1 ALCOHOL FERMENTATION
2.6.6.2 TOP FERMENTATION
2.6.6.3 BOTTOM FERMENTATION
2.6.7 PACKAGING
2.7 SPOILAGE
2.7.1 MICROORGANISM THAT DETERIORATE BEER
2.8 TYPES OF BEER
2.8.1 EUROPEAN BEERS
2.8.2 INDIGENOUS AFRICAN BEERS
2.9 EFFECTS OF ALCOHOL ON MAN
2.9.1 ALCOHOL AND HEALTH
CHAPTER THREE
3.0 MATERIALS AND METHODS
3.1 MATERIALS
3.1.1 CHEMICALS AND REAGENTS
3.1.2 GLASSWARES AND EQUIPMENT
3.1.3 PREPARATION OF SAMPLES
3.2 METHODS
3.2.1 METHOD OF PREPARATION OF SORGHUM BEER
3.2.2 ACTIVATION OF YEAST
3.2.3 PREPARATION OF BITTERLEAF EXTRACT
3.2.4 PREPARATION OF REAGENT
3.2.4.11% PHENOLPHTHALEIN
3.2.4.2 0.1M NaOH SOLUTION
3.3 METHOD OF CHEMICAL ANALYSIS
3.3.1 TOTAL ACIDITY
3.3.2 FIXED ACIDITY
3.3.3 VOLATILE ACIDITY
3.3.4 PH DETERMINATION
3.3.5 SPECIFIC GRAVITY
3.3.6 TOTAL DISSOLVED SOLID
3.3.7 TOTAL SUSPENDED SOLIDS
3.3.8 ETHANOL CONTENT
3.3.9 MICROBIAL COUNT
3.3.9.1 PROCEDURES FOR THE PREPARATION OF MEDIA
3.3.9.2 PROCEDURE FOR CULTURING PLATES
3.3.9.3 PROCEDURE FOR IDENTIFICATION OF ORGANISMS
CHAPTER FOUR
4.0 RESULTS
4.1 RESULTS FOR TOTAL ACIDITY, FXED ACIDITY, VOLATILE ACIDITY AND PH OF SORGHUM BEER
4.2THE GRAPHICAL REPRESENTATION OF TOTAL ACIDITY, FIXED ACIDITY, VOLATILE-ACIDITY AND PH RESULT
4.3 RESULTS FOR ETHANOL CONTENT, SPECIFIC GRAVITY, TDS AND TSS FOR SORGHUM BEER
4.4 GRAPHICAL REPRESENTATION OF ETHANOL CONTENT, SPECIFIC GRAVITY,
TOTAL DISSOLVED SOLIDS (TDS) AND TOTAL SUSPENDED SOLID (TDS) RESULTS
4.5 AVERAGE MEAN PARAMETERS GENERATED FROM HOPPED AND UNHOPPED SORGHUM BEER
4.6 GRAPHICAL REPRESENTATION OF THE AVERAGE PARAMETERS GENERATED FROM SORGHUM BEER WITH AND WITHOUT HOPS
4.7 MICROBIAL COUNT FOR BENCH STORED SORGHUM BEER WITH AND WITHOUT HOP
CHAPTER FIVE
5.0 DISCUSSION
5.1 CONCLUSION
5.2 RECOMMENDATION
REFERENCES
APPENDIX A
APPENDIX B
APPENDIX C
LIST OF TABLES
Table 1: Alcoholic beverage produced from cereals in Africa
Table 2: Average kaffir beer analysis
Table 3: Total acidity, Fixed acidity, Volatile acidity and PH values of sorghum beer with and without hop substitute
Table 4: Ethanol content, Specific gravity (day 1-day 5) and Total
Dissolved Solids and Total Suspended Solids (day I and day 5)
values of sorghum beer with and without hop substitute
Table 5: Specific gravity, Total acidity, Fixed acidity, Volatile
acidity, TDS, TSS and pH values for with and without hop
sorghum beers
Table 6: Frequency of distribution of isolates in Sorghum beer with hops
Table 7: Table 7: Frequency of distribution of isolates in Sorghum beer without hops
LIST OF FIGURES
Fig 1: Sorghum bicolor
Fig 2: Pearl millet
Fig 3: Hop cone
Fig 4 Vernonia amygdalina
Fig 5: A schematic representation of glucose degradation under aerobic and anaerobic condition
Fig 6: The Glycolytic pathway
Fig 7: Some important fates of glycolysis
Fig 8: Flowchart for the traditional process of kunu-zaki
Fig 9: Total Acidity, Fixed Acidity and Volatile Acidity values of Sorghum beer with and without hop substitute
Fig 10: Ethanol content, Specific Gravity, Total Dissolved and
Suspended Solids value of Sorghum beer with and without
hop substitutes
Fig 11: S.G= specific gravity, T.A= Total acidity (g/100ml), F.A=
Fixed acidity (g/100ml), V.A= Volatile acidity (g/100ml), TDS=
Total dissolved solids (×105ppm), TSS= Total suspended solids
(×105ppm), PH, E.C= Ethanol content (%v/v)
CHAPTER ONE
1.0 INTRODUCTION
The word beer derives from the Latin word bibere meaning to
drink (Okafor, 2007). Beer is the world’s oldest and most widely
consumed alcoholic beverage and the third most popular drink overall
after water and tea. Grossman (1995) defined beer as a general name
given to beverages resulting from the germination of a malt or cereal
grain. The process of brewing beer is called brewing. It is produced by
the brewing and fermentation of starches mainly derived from cereal
grains most commonly malted barley, although wheat, maize (corn), and
rice are widely used (Gutcho, 1976). In Nigeria today, barley has been
replaced by some locally grown cereals such as sorghum or guinea corn,
millet and maize as the principal raw materials. The tropical beers
(African local beers) are known by different names in different part of
the world; burukutu, otika and pito in Nigeria, maujek among the Nandi’s
in Kenya, mowa in Malawi, kaffir beer in South Africa, merisa in Sudan,
bouza in Ethiopia and pombe in some parts of East Africa (Okafor,
2007).
Burukutu is an indigenous alcoholic beverage. Burukutu, a popular
alcoholic drink among indigenes of the middle belt region of Nigeria, is
a local brew made from fermented sorghum and other protein enriched
grains (Ekundayo, 1969). The age long drink, also known as BKT, serves
as a source of alcohol for those who lack the financial means to
patronize refined brew like beer and other foreign or imported drinks it
is produced mainly from the grains of guinea corn (Sorghum vulgare and
Sorghum bicolor). The process of production of burukutu involves
malting, mashing, fermentation and maturation as described by Ekundayo
(1969).The production process of these indigineous drinks involves
fermentation at its initial production stage and comes out as an
alcoholic drink. The microorganisms associated with fermentation
include Saccharomyces cerevisiae, Saccharomyces chavelieria and Leuconostocmesteroides (Faparusi et al., 1973).
Sorghum is a large variable genus with many cultivars (Ettasoe,
1972). The method employed in brewing sorghum beer here involves,
malting, mashing, wort boiling with hops, fermentation, (using brewer’s
yeast and bakers yeast) and packaging. The tropical sourced hop extracts
used here is Vernonia amygdalina (Bitter leaf) which have been
found to contain an anti bactericidal agent which is capable of
extending the useful life of these indigenous beers (Okoh et al., 1999).
Chemical analysis on the prepared sorghum beer such as; ethanol
content, PH value, specific gravity, fixed acidity, total acidity, total
dissolved solids (TDS), total suspended solids(TSS) were analysed
quantitatively, using different methods.
1.1 AIMS AND OBJECTIVES
The aim of the project is itemized into the following objectives;
1. To determine the shelf-life of locally brewed sorghum beer.
2. To check the effect of bitterleaf (Vernonia amygdalina) extract on the locally brewed sorghum beer.
3. To compare the results from the chemical analyses of locally
brewed sorghum beer with bitterleaf extract and sorghum beer brewed
without bitterleaf.