Predicting the behavior of Escherichia coli introduced as a postprocessingcontaminant in Shrikhand, a traditional sweetened lactic fermented milk product

The increasing popularity of traditional milk-based foods has placed emphas is on the need for microbial safety in food-chain establishments, as there are ample possibilities for foodborne pathogens to occur as postprocessing contaminants. The behavioral pattern of an enterotoxigenic strain of Escher ichia coli D 21 introduced as a postprocessing contaminant in shrikhand, a traditional sweetened lactic fermented milk product, was studied with varia bles of initial inoculum (4.3, 5.3, and 6.3 log(10) CFU/g), storage tempera ture (4, 10, and 16 degreesC), and storage period (4, 9, and 14 days). Duri ng storage of shrikhand prepared individually with Lactobacillus delbruecki ssp. bulgaricus CFR 2028 and Lactococcus lactis ssp. cremoris B-634, there was a steady decrease in the viable count of E. coli that was proportional to the initial inoculum of E. coli introduced into shrikhand. The data wer e subjected to multivariate analysis, and equations were derived to predict the behavior of E. coli in shrikhand. The predicted values for the probabl e survival of E. coil showed good agreement with the experimental values wi th a majority of these predictions being fail-safe. The values of statistic al indices showed that the model fits ranged between extremely good and sat isfactory. Response surface plots were generated to describe the behavioral pattern of E. coli. The derived models and response surface plots enabled prediction of the survival of E. coli in shrikhand as a function of initial inoculum levels, storage temperatures, and storage periods of shrikhand. T hese predictions were valid within the limits of the experimental variables used to develop the model.