Efficacy of knife disinfection techniques in meat processing

•Knife disinfection in hot water (82 °C) is mandatory - alternatives are permitted.•Different time-temperature combinations were tested.•Pure water with/without lactic acid (2%) and with/without ultrasound was used.•Effectiveness with short impact time (10 s) is attainable such as using 40 °C water + lactic acid.

EU Regulation 853/2004 requires that knives used in meat processing be disinfected by submerging them in hot water (+ 82 °C). Alternative procedures are permitted if the efficacy is proved to be equivalent. In the present study, various time-temperature combinations together with pure water, water with lactic acid (2 %), and the use of ultrasound with and without lactic acid (2%) were investigated. Steel plates were covered with fat and protein and then inoculated with a standardized bacterial contamination assembled according to the composition of bacterial contamination found in a previous field trial conducted with regard to the slaughter of pigs. Several combinations with diverse temperatures and time intervals were tested until no microbial load was detectable by using a wet-dry-swab technique that had previously been tested to ensure maximum bacterial recovery. The following were effective in bringing the tested bacterial flora below the detection limit:•70 °C water bath for 10 s•60 °C water bath + ultrasound for 5 s•40 °C water bath + lactic acid (2%) for 10 s•40 °C water bath + ultrasound + lactic acid (2%) for 5 sIn particular, the use of lactic acid permitted a relevant reduction of the temperature, while providing effective sterilization. The use of such non-hazardous food-safe additives is particularly suitable for successful disinfection at lower temperatures.