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 In Nigeria today, barley has been replaced by some locally grown cereals such as sorghum or guinea corn, millet and maize as the principal raw materials.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.