THERMAL-PROCESSING CANNED MEAT WITH SUB-FREEZING INITIAL TEMPERATURES - THERMAL AND MICROBIAL VALIDATION

Retorting from the frozen state is attractive with respect to product quality and economy and was investigated in canned bentonite and flaked ham. A two dimensional finite difference model was written in which thermal diffusivity varied with temperature. Heat penetrations were completed with initial temperatures of 0, -5 degrees, -10 degrees, -15 degrees and -20 degrees C. In ham, decreasing initial temperatures resulted in increased lag factors (j(h)) but did not affect heating rate index (f(h)). In bentonite, f(h) but not j(h) increased. D and Z of Clostridium sporogenes PA 3679 spores were not affected by previous freezing. Sub-freezing initial temperatures were judged to be consistent with safe processes if validated with heat penetration studies.