Quality evaluation of naturally fermented alcoholic beverages, microbiological examination of source of fermentation and ethanol productivity of the isolates

The naturally fermented alcoholic (NFA) beverages collected from tribal are as contained higher quantity of methanol, with wide variations in ethanol, pH and volatile acidity. The NFA beverages were also found to be contaminat ed with Brettanomyces spp. and coliform bacteria indicating a potential dan ger of their consumption. The examination of natural sources of fermentatio n (NSF), frequently used in such fermentations, revealed the presence of fu ngi viz., Aspergillus flavus, Aspergillus oryzae, Mucor spp., Rhizopus spp. : the yeast included Saccharomyces spp., Scytalidium thermophilus (Torula) and Rhodotorula and bacteria viz., Pediococcus, Leuconostoc and Pseudomonas . Except for a few, the general ethanol productivity of the isolates from N SF was low. Saccharomyces spp. had higher population and was predominant am ong the yeasts isolated from NSF. The abnormal characteristics of the NFA b everages could be correlated with the raw materials, source and method of f ermentation and distillation. Use of pure yeast and proper distillation met hod could improve the quality of such beverages.