SURVIVAL AND GROWTH OF SELECTED MICROORGANISMS IN KHOA DURING PREPARATION AND STORAGE

The survival of Escherichia coli and Staphylococcus aureus during the production of khoa, a heat concentrated Indian milk-based product, was investigated. Heat processing of milk containing from 3.6 to 6.5% fat at either 63 or 73C eliminated all E.coli. Under similar processing c onditions, S. aureus was recovered, but only when heated in milk at 63 C containing 6.5% fat. Potassium sorbate (3000 ppm) appeared more effe ctive in inhibiting the growth of selected yeast and molds in khoa at 7C, compared to ascorbic acid (3000 ppm). Reducing the water activity (a(w)) of khoa from 0.97 to 0.93 did not appear to enhance the preserv ative effect. The reduction of E.coli or S. aureus in khoa during prol onged storage at 6-7C, was less than one log cycle, regardless of a(w) or preservative type. Survival of S. aureus in khoa appeared to be en hanced with a decrease in a(w). The potential for pathogens to survive in khoa during processing should be taken into consideration when for mulating heating protocols.