D VALUES OF ESCHERICHIA COLI IN TILAPIA MEAT

ABSTRACT

In this study, the decimal reduction times (D values) of the reference strain Escherichia coli (ATCC 25922) were established in tilapia (Oreochromis niloticus) meat homogenate. Known numbers of cells were inoculated to irradiated meat homogenate prior to heat treatments at 65, 70 and 75C. In all heating temperatures, inactivation rates significantly increased with increasing exposure times. The D values calculated from the E. coli survivor curves ranged from 0.50 to 1.13 min. The thermal resistance constant (Z value) calculated from the established D values was 28.5C. The established D and Z values of the reference strain may be used in calculating adequate thermal process schedules for tilapia meat, and possibly, other similar products.

PRACTICAL APPLICATIONS

This study established the heat resistance characteristics of the bacterium Escherichia coli (ATCC 25922) in a tilapia meat medium. The results of this study may be applied in food manufacturing and food service industries where tilapia meat is used as a raw material or an ingredient. The thermal resistance parameters determined in this study can be used in establishing adequate thermal process or cooking schedules to ensure the inactivation of the target microorganism.