Microbiological and chemical processes associated with the production of burukutu a traditional beer in Ghana

Abstract

Burukutu is the lesser known of two types of traditional sorghum beers produced in Ghana, pito being more common. Burukutu production involves malting, mashing, souring and alcoholic fermentation. Microbiological and chemical changes which occur during souring and alcoholic fermentations were investigated through analysis of samples obtained from production sites. Lactic acid bacteria (LAB) responsible for the souring were Lb. fermentum (33.3%), Lb. plantarum (25%), Lb. acidopilus (16.7%), Lc. lactis subsp. lactis (16.7%) and Lb. brevis (8.3%). Their activities resulted in a reduction in pH from 4.64 to 4.05 during a 6-7 h holding period. Souring also occurred concurrently with the alcoholic fermentation reducing the pH further to 2.88 and a final titratable acidity content of 0.82 %. Saccharomyces cerevisiae was responsible for the final alcoholic fermentation which resulted in an alcohol yield of 4.47% in 120 h. When burukutu was challenged with about 105 CFU/ml of some enteric pathogens at the start of the alcoholic fermentation, Salmonella typhimurium could no longer be detected at 16 h, E. coli at 20 h, Staphylococcus aureus at 36 h and Streptococcus faecalis at 40 h. All isolates of the dominant LAB, Lb. fermentum, also demonstrated antimicrobial activity against S. aureus, E. coli and Salmonella typhimurium. This is the first detailed study of burukutu production in Ghana