Infectivity of Trichinella spiralis from Frozen Pork.

This research was carried out to determine the time/temperature exposure of Trichinella spiralis to freezing conditions necessary to destroy the infectivity of the trichinae. Experimentally infected pork was subjected to temperatures of -1 to -193°C for one sec to 182 d and the treated pork samples, which contained about 1000 larvae per gram of tissue, were subjected to rat bioassay to determine infectivity of the larvae. A linear regression equation, logt = 5.98 + 0.40T where t = required inactivation time in hours and T = temperature in degrees Celsius, described the exposure necessary to destroy the trichinae. The correlation for that relationship was r = 0.942. The predicted thermal death times (+7 min) at -20, -15, and -10°C were 8 min, 64 min, and 4.0 d, respectively. The predicted upper confidence limits (99%) for the thermal death times (+7 min) for exposure at -20, -15, and - 10°C, were 48 min, 63 h, and 266 d, respectively. These data provide a continuum of definitive times and temperatures necessary to destroy T. spiralis by freezing and are of value to the meat industry and the regulatory agencies.