Survival and growth fo foodborne bacterial pathogens in fermenting batter of dhokla.

摘要

Dhokla is a lactic acid fermented steamed cake having a soft and spongy texture, consumed widely in India. Dhokla batter may be contaminated with common foodborne pathogenic bacteria during processing of its substrates, raw rice and Bengal gram. Dhokla batter prepared in the laboratory remained contaminated during 15 h of fermentation with Bacillus cereus, Staphylococcus aureus and Escherichia coli. At the time of fermentation, the rise in vol. of dhokla batter remained negatively correlated with its decline in pH. When dhokla batter was intentionally inoculated at the start of fermentation with these bacteria in order to simulate an unwanted contamination incident, all 3 organisms survived. While steaming the batter for 15 min to prepare dhokla cakes, counts of S. aureus and E. coli decreased to below the detection limit (2.0 log cfu/g cake), but B. cereus survived. Hence, it can be concluded that although fermentation is capable of holding the growth of common pathogenic bacteria in check, steaming is critical to produce microbiologically safe dhokla.