Monitoring microbiological and biochemical changes in fermented yam

Abstract

The microbiological and biochemical changes occurring in yam (Dioscorea rotundata L.) tissues fermented in 2% brine under anaerobic conditions at ambient temperature were studied. The ash. fibre and fat contents of the yam tissues were reduced at an average rate of 1.98, 1.72 and 0.42 mg g(-1) d(-1), respectively.Lactobacillus andLeuconostoc spp., as well as other fermentative microorganisms, showed a tendency to increased growth. The decrease in the total aerobic count after a 4-d fermentation was due to depletion of available nutrients, increased acidity of the medium and complete anaerobiosis of the environment. The fermenting microbes showed a higher amylolytic activity, releasing between 52 and 73 mg glucose per mL, than proteolytic activity, where between 120 and 250 microg amino acids per mL was released.