BIOCHEMICAL AND MICROBIOLOGICAL CHANGES DURING THE FERMENTATION OF PALM WINE

Abstract

The microbial succession and biochemical parameters (pH, ethanol, organic acids, vitamins and sugar concentrations) in fresh palm sap and also the effect of spontaneous fermentation on these aforementioned parameters were studied. The palm sap sample was analysed immediately after tapping for over 5 days to determine the pH and percentage concentrations of sugars, ethanol, organic acids, and vitamin content using biochemical and microbiological tools and highperformance liquid chromatography (HPLC). Test samples were withdrawn at 24-hour hours over fermentation to conduct these analyses. The microbial load and possible microbial populations over the period were also studied. Results obtained showed that the pH of the palm sap at zero (O hour) was slightly acidic (4.9), and the pH dropped consistently till after the third day (72 hours); then, a constant pH of 3.1 was observed till the end of the study. The results also showed a consistent decrease in the sugar content of the palm sap after 24 hours. A consistent increase in organic acids (lactic and acetic acid) was observed after 24 hours. The results also showed a consistent increase in the ethanol concentration until it peaked after 72 hours, then a slight decrease in the ethanol concentration. There was an initial increase in microbial load; however, after 48 hours, the yeast biomass decreased while the bacteria biomass increased. Some basic identification test was carried out on the isolates obtained from the palm wine, and the result showed that 70% of the yeast obtained were saccharomyces cerevisiae. At the same time, lactic acid and acetic acid bacteria were the predominant bacteria obtained from the sample. These microbial activities greatly affect the shelf life and taste of palm wine. The result also showed that spontaneous fermentation in palm sap affected the organoleptic properties of the palm sap and other nutritional values.