Sorghum Beer Essay

An experiment was performed in order to produce South African beer (Umqombothi) using maize as a main cereal and cereal as an adjunct. About half a kilogram of maize was mashed in 5 litres of water and commercial sorghum malt adjunct was added to the mixture to provide extra enzymes for the saccharification and proteolysis of starch stored. The resulting wort was cooled down and fermented with commercial yeast for a minimum of 96 hours. Various test such as acidity, viable microbial count degree of brix were done before and after fermentation. It was found that the degree of brix increased and this was unexpected, but it was rationalised by the fact that sorghum beer contains of non-fermentable sugars from its raw materials that probably contributed to the dissolved solid content leading to the higher degree of brix. The viable microbial count and acidity increased after fermentation and was largely attributed to the symbiotic relationship between the yeast and lactic acid producing bacteria in the beer. Sorghum was found to be a best adjunct when compared to other cereals because of its high starch content. The sorghum beer produced had similar sensory properties as the typical home-made commercialised beer such as the faded brownish colour, sour taste and fruity aroma.

Key words: Sorghum, umqombothi, saccharification, fermentation, brix.

Introduction

For many years, sorghum beer has been produced and consumed in South Africa. Usually it is a beer made from sorghum malt, maize meal or millet, yeast, and water. It is a traditional African beer, and is often consumed at traditional ceremonies, weddings, births, baptism, and various other African social gatherings and festivals. African people initially produced sorghum beer in o...

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...ce the brewing costs (Hahn, 1966). Sorghum also produces a higher content of α-amino nitrogen than other adjunct. This α-amino nitrogen is a requirement for yeast during fermentation so that it can grow and produce the sour taste and the aroma which is characteristic of Umqobothi (Hahn, 1966).

The high microbial count of sorghum means that the beer will probably have a lower shelf life as the microorganisms contained can cause spoilage. Further decrease in the shelf life is that the beer is not filtered of the yeast so the beer is consumed while it is still fermenting and other microorganism still flourish in the medium (Lyumugabe, et al., 2012). The acidity of the beer was higher than the one published in literature, but this was expected as the production varies according to geographical location. This high acidity also contributed to the sour taste of the beer.