Application of heat in postcook meat chillers reduces Listeria

Electrical air-blowing heaters were used to heat and dry out holding chillers used for postcook commercial processed meats in an attempt to control the presence of Listeria. A baseline study of the prevalence of Listeria in holding chillers in seven facilities was undertaken. Listeria was detected in four of the seven chillers, and swab samples showed Listeria prevalence ranging from 7 (7.8 ) of 90 to 6 (20 ) of 30, depending on the facility. Two of the facilities with established Listeria contamination (A and E) were chosen for further studies. The heating trials consisted of three individual heating interventions at each of the two facilities, with 2 weeks of postintervention sampling after each treatment. The initial Listeria prevalence in chiller A was 19(10.6 ) of 180, and treatment at 37 degrees C for 36 h reduced prevalence to 3 (1.7 ) of 180. The initial Listeria prevalence in chiller E was 7 (7.8 ) of 90, and treatment at 50 degrees C for 2 h reduced prevalence to 0 of 90. Both reductions were statistically significant at P <0.01. The incorporation of these two simple chiller heating protocols into these facilities good manufacturing practices has effectively reduced prevalence of Listeria in chillers.