PSVII-24 - Effectiveness of hot water knife sanitation practices during beef dressing processes

Abstract: Our objective was to assess whether the harvest processing equipment sanitation practices in beef processing plants is sufficient to mitigate pathogen transfer. Multiple regulatory agencies across the globe require that harvest equipment be sanitized using hot water at a minimum of 82°C, with a momentary dip when a time is specified. Consequently, hot water sanitizers have been widely implemented at meat processing facilities, in particular for knife sanitation throughout the dressing process. However, there is no standard time requirement for hot water immersion and as such the effectiveness of hot water sanitization is uncertain. The practice for knife sanitation at a large beef processing facility was audited and the microbial reduction that simulated the audited practice was assessed along with a momentary dip at 82°C. A five-strain cocktail of Escherichia coli and 11 knives of differing degree of usage obtained from the beef plant were used in the study. An area of 50 cm² of the upper surface of each knife was spread-inoculated with the five-strain E. coli cocktail and the knife was subsequently submerged in a water bath coupled to a water circulator for immersion at 82°C. Exposures times tested were those derived from the in-plant audit for each knife type. A knife that was similarly inoculated, but was not treated with hot water served as a positive control. E. coli surviving the treatment were enumerated by plating. In addition, two knives that had most and least reduction of E. coli were artificially contaminated with meat prior to inoculation, by passing the knife through meat multiple times. For each condition, three independent trials were conducted. Least-squares means for log counts were separated by a post-hoc Tukey test.

Mean immersion times for different knives audited ranged from 1 to 9.8 s. Immersing knives in water at 82°C significantly reduced the number of E. coli (P < 0.05; Table 1), ranging from 2.3 (air knife)-5.5 (skinning knife 2) log units. Variation among the same knife type was observed. Momentary dip at 82°C reduced E. coli on de-boning, hook, air knife and wizard knife by 1-1.2 log (P < 0.05) and < 1 log for the other six knives (P >= 0.05). Treatment at 82°C for the duration of average exposure time observed during the in-plant audit of knives that had been contaminated with meat debris showed lower reductions of E. coli, compared to clean knives. Those reductions ( >1.5 log units) were significant (P < 0.05). In conclusion, the duration for hot water sanitation of knives at beef processing plants achieve significant reduction of E. coli if temperature is maintained at 82°C and a momentary dip at the same temperature would be less likely to be effective.