Comparison of Peroxyacetic Acid Treatment and Standard Hot Water Treatment for the Inactivation of Non-O157 STECs on Meat Cutting Tools

Introduction: The practice of hot water sanitization of meat cutting tools is an internationally recognized standard. A temperature of no less than 82 °C is used to prevent cross contamination between carcasses in meat processing facilities although equivalent alternative procedures are also available. The three main disadvantages of hot water treatment are: scalds and burns to workers, entrapment of pathogenic bacteria on tools due to heat agglutination of meat proteins, and high energy costs associated with heating and maintaining water temperature.

Purpose:  The purpose of this study was to determine the effectiveness of an alternative knife sanitization method using peroxyacetic acid (POA) at two temperatures.

Methods:  Sterile knives were inoculated with a cocktail of five strains of nalidixic acid resistant non-O175 STEC suspended in a raw meat soil. The knives were air-dried and individually treated with a standard hot water treatment (82 °C), 220 ppm of POA at room temperature and POA at 40 °C for 1, 5, 10 and 15 s. Surviving STECs were enumerated on tryptic soy agar supplemented with nalidixic acid (TSA-NA).

Results:  Hot water treatments at 82 °C for 1 and 5 s reduced non-O157:H7 STECs by 3.64 and 5.47 log CFU/knife, respectively.  POA treatment at room temperature reduced these bacteria by 4.30 log CFU/knife and by 4.74 log CFU/knife. When temperature of the POA was elevated to 40 °C reductions of 5.08 and 5.47 log CFU/knife were observed. Reductions of < 0.5 log CFU/knife were observed for water at room temperature and water at 40 °C.

Significance: The results of this study indicate that a peroxyacetic acid-based knife treatment (at 40 °C) is an alternative equivalent method to the standard hot water treatment and can reduce the cross contamination of non-O157 STECs with added advantages of lower energy costs and enhanced worker safety.