Validation of an alternative procedure for knife cleaning on the slaughter floor

Summary

​Knife and equipment sterilisers that operate at not less than 82°C use large volumes of hot water, creating water supply and disposal problems, high-energy costs and operator safety concerns for Australian meat processors.
Neither the need for nor the superiority of 82°C water is supported by published scientific information.
This report reviews regulatory requirements, the historical reasons for using 82°C water, and relevant scientific literature on 82°C water and water at lower temperatures for cleaning and sanitising knives and equipment during processing operations.
The reason why 82°C became the prescribed minimum temperature for treating knives and equipment is unclear.
Food microbiology texts provide various long-used temperatures and corresponding minimum contact times for the internationally validated processes of cooking, pasteurisation and sterilisation, none of which make reference to 82°C.
The containers of 82°C water for treating knives have long been termed ‘sterilisers’ but immersion of knives for brief periods - one second or less - even up to some minutes, clearly does not comply with the scientific meaning of sterilisation.The available evidence suggests that washing knives makes a greater contribution to maintaining the knives and equipment in a clean and sanitary condition during processing than does their brief immersion in 82°C water.
Two regimes were compared:the current regime where the knives were washed in hand-wash at 20-40°C followed by momentary dipping in water at 82°Can alternative regime where the system employed was a two knife one where the operator exchanged knives between carcases, the knives were washed in hand-wash water then immersed in water at 60°C for the time it took the operator to complete the specific operation with the other knife
On the beef floor the mean log Total Viable Count on 230 knives, 10 from each of 23 task stations, was2.20 after the current regime1.78 after the alternative regimeE. coli was detected on 20 and 21, of the 230 in each treatment group, knives respectively
On the mutton floor the mean log Total Viable Count on 130 knives, 10 from each of 13 task stations, was1.87 after the current regime1.69 after the alternative oneE. coli was detected on 24 and 29, of the 130 in each treatment group, knives respectively
Based on the results from that investigation, it may be concluded that the proposed regime will maintain knives in sanitary condition and will not compromise the safety of the carcase and meat parts on which they are used, thereby meeting the requirement of AS 4696-2002 and the Export Control (Meat and Meat Products) Orders.
The proposed regime is also consistent with the requirements of the Food Standards Code.