Growth and Survival of Escherichia coli O157:H7 During Manufacture and Storage of Indian Cheese (Paneer)

Abstract

The growth and survival of Escherichia coli O157:H7 during manufacture and storage of Indian cheese or paneer was investigated. Pasteurized and raw milk that had been inoculated with 10⁴ CFU/mL of E. coli O157:H7 cultures were used for manufacturing paneer samples which were vacuum-packaged and stored at 4°C, 8°C, and 28°C. Survival and growth of E. coli O157:H7 in paneer samples was determined after every 4 h for up to 48 h. Escherichia coli O157:H7 could survive the manufacturing process of paneer and were present at the end of the storage period(at 28°C) in significantly (p < 0.05) greater numbers than the initial inoculum. No significant difference in survival and growth were noticeable in paneer samples manufactured from raw milk. Though refrigeration (4°C or 8°C) effectively inhibited the growth of E. coli O157:H7, this pathogen could survive over a period of 48 h. Our observations suggest that unpasteurized or improperly pasteurized milk could be an important source for transmission of E. coli O157:H7 through paneer, and appropriate steps must be taken by government agencies to ensure consumer safety for this dairy product.