Survival of Campylobacter spp. in poultry meat preparations subjected to freezing, refrigeration, minor salt concentration, and heat treatment

Abstract

The survival of Campylobacter spp. under defined conditions of freezing (-22 degrees C) was studied in naturally contaminated chicken skin and minced chicken meat. A decline of approximately one log(10) cfu/g was observed after 1 day of freezing. No further significant reduction was achieved by prolonged storage in the freezer, although a tendency for further gradual reduction of the numbers of Campylobacter spp. present was noted. Campylobacter spp. could still be detected qualitatively (per 0.1g) after 84 days. In a second part of this study, the survival of Campylobacter spp. in a typical minced meat preparation (minced meat supplemented with 1.5% salt (NaCl)) stored at refrigeration (4 degrees C) or frozen (-22 degrees C) was studied. No significant reduction of the pathogen was observed if the minced chicken meat was kept at 4 degrees C for 14 days, opposite to approximately one log(10) cfu/g reduction after 1 day when the minced meat preparation was stored in the freezer (-22 degrees C) for 14 days. The latter reduction is imputed to the effect of freezing as mentioned above and not due to the supplementation of NaCl to minced meat or the combination of NaCl and freezing, because similar reductions of Campylobacter spp. were noticed when minced meat (without addition of NaCl) was frozen. Finally, in a third part of the study, the survival of Campylobacter spp. subjected to a heat treatment, conform to consumer-based pan-frying, in inoculated (4.5+/-0.2 cfu/g) as well as naturally contaminated chicken burgers (2.1+/-0.1 cfu/g) was studied. The Campylobacter spp. numbers declined after 2 min (internal temperature reached circa 38 degrees C), where after 4 min (internal temperature reached circa 57.5 degrees C) they dropped below detectable levels (<10 cfu/g).