Njemani is a type of traditional palm wine produced in the Shangaan tribe of Zimbabwe and plays an important role in many traditional functions and ceremonies. The wine is consumed in a variety of flavors from sweet to sweet-sour and vinegary. The main aim of the research work was to identify, analyze the biochemical and microbial changes that occur during production and documenting the whole procedure of Njemani production in an attempt to upgrade the traditional processing to a commercial scale. During fermentation microbial population increased with fermentation time. The most dominant Lactic acid bacteria were Bacillus, Lactobacillus spp. and Leuconostic species that were responsible for production of inorganic acids and lactic acid during lactic fermentation. Glucobacter and Acetobacter were the dominant Acetic acid bacteria identified and were responsible for acetic acid fermentation using alcohol as a substrate. The yeast species identified were Saccharomyces cerevisiae, Saccharomyces pombe, Saccharomyces uvarum and Candida spp, however the most dominant was Saccharomyces cerevisiae and were responsible for the conversion of sweet palm sap to an alcoholic beverage. The biochemical parameters varied as fermentation progressed: Ethanol 0.8%-16.3%, acetic acid 2.8%-7.1%, lactic acid 3.8%-6.9% resulting in Total Titratable Acidity ranging from 0.05% to 0.8% and pH from 6.36 to 3.09. The initial sugar content was 15.7% and dropped to 0.7% after fermentation. If biotechnological techniques are applied to the production of Njemani a number of benefits will be harnessed. The palm sap fermentation involves alcoholic–lactic–acetic acid fermentation, due to the presence mainly of yeasts and lactic acid bacteria. Further research will be needed to isolate and identify all the microbial isolates in Njemani.
Keywords: Njemani, biochemical changes, microbial changes, palm wine, lactic acid, alcoholic fermentation, yeasts