STUDIES ON DETECTION, ENUMERATION AND SURVIVAL OF E. COLI IN "READY TO EAT" PROCESSED CEREAL FOOD PRODUCTUSHA RANI, M. FARHANA AYESHA, PREMA VISWANATH AND J.S. SANDHUAbstract Protein-calorie rich "ready to eat" processed cereal food of low moisture content has often been reported to contain aerobic mesophiles and coliforms. Codex Alimentarius Commission (1981) has laid down maximum limits of 10,000/g of aerobic mesophilic count, 20/g coliform count and zero tolerance of Salmonella for these products. Out of 225 samples analyzed, ten samples showed a high coliform count. E. coli was also detected in these samples. The identification of the E. coli was confirmed by biochemical tests. Three out of ten isolates were found to be atypical for fermentation of the sugar rhamnose. Antibiotic sensitivity tests showed increased resistance to the antibiotics Ampicillin, tetracycline, kanamycin and Amikacin in isolates, when compared to the standard E. coli/1610 (IMTECH, Chandigarh) isolate. Serotyping of the isolates showed that many of them belonged to the pathogenic group. Studies on the survival of E. coh in this food showed that a temperature of 25°C was more conducive than that at 35°C for survival. An initial count of 3 loglo/g was reduced to <3 in 107 days (as determined by the Most Probable Number Completed Test Method) when samples were incubated at 35°C. However, a count of 93 logio/g was recorded in the samples incubated at 25°C even on the 120th day of storage. It was observed that storage of such samples at higher temperature led to a safer product. Of the two E. coli enumeration methods used, the Most Probable Number (MPN) Completed test method was found to be more reliable than the b- Glucuronidase based method as the latter method could not detect E. coli which did not possess the enzyme glucuronidase.
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