BACTERIOLOGICAL EXAMINATION OF PALM WINE

ABSTRACT

The assessment of the presence, growth and survival of bacteria and yeasts in fresh raffia palm wine sample gave rise to the isolation of eight bacteria: Staphylococcus aureus, Escherichia coli, Lactobacillus spp, Micrococcus luteus, Serratia marcessens, Acetobacter spp, Bacillus and Streptococcus spp and four yeasts: Candida spp, Saccharomyces uvarum, Saccharomyces cerevisiae and Schizosaccharomyces pombe. The total bacterial count was in the range 6.08 x 103-3.48 x 103CFU/ml and the bacterial counts between 24-120 hrs of fermentation were not significantly different from the bacterial count in 0hr (fresh; P<0.05). Total coliform count was in the range 4.60 x 103  0 CFU/ml. There was an initial rise in total yeasts counts after 24hrs (7.38  x 103- 8.22 x 103CFU/ml) and then a gradual decrease to 4.10 x 103 CFU/ml. The yeast count after 120 hrs of fermentation was significantly different (P<0.05) from counts between 0-72hrs. The growth and survival pattern of the bacteria isolates from 0- 120hrs showed that S. aureus was eliminated from the samples after 24hrs of growth while E. coli, M. luteus, Lactobacillus spp and Streptococcus spp were eliminated after 48hrs of growth. Serratia marcesens did not survive beyond 72hrs of fermentation while Bacillus and Acetobacter spp were present till the end of the fermentation. S. cerevisiae, S. uvarum and S. pombe survived from 0-120hrs of fermentation while Candida spp was eliminated after 48hrs of growth. All the physicochemical  parameters tested varied with respect to time. The pH values decreased from 6.8 -3.8. Fermentation temperature dropped from 25oC to 21.5oC after 24hrs and then fluctuated between 21.4oC-21.5oC till the end of the fermentation. The alcohol values of the palm wine samples increased steadily (1.6% v/v-15.10% v/v) from 0-120hrs of fermentation. There was a gradual increase in the moisture level (96.49% - 97.55%) as fermentation progressed. Bacterial and fungal pathogens which were present from the beginning of the fermentation as handling and processing contaminants were eliminated after some hours as fermentation progressed.