A Comparative Study on Microbiological and Physico-chemical Properties of Three Local Alcoholic Beverages Produced and Consumed in Mombasa County, Kenya

Abstract

Physico-chemical properties and micobial contamination of three local brews (Mnazi, Mchuchula and M’bangara) consumed in Mombasa County were assessed. The bacteria concentration enumeration was determined by incubation of each sample for two days at 35°C to 37°C on plates containing colony forming units (CFUs) on Aerobic plate count (APC) agar and Lactic acid bacteria (LAB) on Rogosa agar plates. Growth on plates were positive for heterotrophic and LAB bacteria with high levels recorded in 10-2 aliquots of each sample. M’bagara recorded higher levels of LAB (201.0±24.79), with Mnazi and Mchuchula having slightly low levels of LAB of 182.0±26.96 and 129.0±5.20 respectively despite some of the plates not being used for enumeration since they had above 250 CFUs. Yeast detection and enumeration was also determined. Low numbers of yeast cells were recorded in M’bangara (30.0±5.72), with Mchuchula recording the highest number of yeast cells (66.30±3.07). Physico-chemical properties determined included colour, acidity, pH and alcohol in terms of volume i.e Alcohol by Volume (ABV). M’bangara recorded the highest titratable acidity (0.9±0.04), and lowest pH (2.7±0.07) whereas the highest ABV levels were recorded in M’bangara (4.6±0.12). Confirmatory results for total coliforms, feacal coliforms and E. coli indicate the absence of contamination from sewage material. There were significant variation (p>0.05) in terms of physico-chemical properties and microbial contamination in the three analyzed local brews. In this study, local brews consumed in Mombasa County contain non-miocrobial and microbial contaminants which may be related to effects of consumption of these brews.