Application of heat in post cook chillers as a means for Listeria Reduction in processed meat

Summary

​A two week baseline survey of GMP sanitation protocols and Listeria prevalence in high risk processed meat chillers was performed across three large and four medium to small processed meat facilities in Queensland, Australia.
Listeria was detected in four of the seven chillers during the initial surveillance testing, with prevalence ranging from 7.8 to 20%. The final Listeria prevalence for large chiller A and small chiller B was calculated over a total of six weeks, as these chillers were chosen and available to participate in the heating intervention.
The heating trials consisted of three individual heating interventions followed by two weeks of post intervention sampling to a total of six weeks.
The treatment used for small chiller B and large chiller A was 50ºC over 2h and 37ºC over 36h, respectively.
Listeria prevalence in small chiller B and large chiller A was reduced to nil (0 /90) from a pre-heating 7.8% (7/90), and to 1.7% (3 /180) from a preheating 10.6% (19/180), respectively. Both reductions were statistically significant at P <0.01.>
The incorporation of these two simple chiller heating protocols into facility GMP has effected significant reductions in chiller Listeria prevalence.
Adoption of these regimes by industry may disrupt the chiller mediated contamination of cooked smallgoods with Listeria monocytogenes,and improve the overall safety of processed meat products.