Decontamination of Knives Used in the Meat Industry: Effect of Different Water Temperature and Treatment Time Combinations on the Reduction of Bacterial Numbers on Knife Surfaces

Abstract

Previous regulations in Australia and internationally required that knives used during the slaughter and dressing of carcasses be sanitized by brief submersion in water at 82 degrees C. Many current international regulations allow science-based equivalent alternative procedures to be used. However, limited time-temperature data are available on the response of bacteria to hot-water treatment on knives. The present study was undertaken to determine the effect of combinations of time and temperature ranging from 1 to 60 s and 60 to 82 degrees C on the disinfection of knives artificially contaminated with Escherichia coli and Listeria monocytogenes. In addition, the effect of a prerinse at 40 degrees C on the disinfection of artificially contaminated knives treated under the same controlled conditions as above was established. The experiments, which were carried out with knives in a meat matrix at each of 42 time and temperature combinations, with and without the prerinse, were performed in a laboratory water bath. Bacterial reductions were established by plate counts from the knife blade before and after immersion. Mean log reductions were subjected to statistical analysis, and basic models were generated from the results. The results demonstrated that dipping knives in water for shorter times at higher temperatures, for example, 82 degrees C for 1 s, or longer times at lower temperatures can produce equivalent inactivation of bacteria. Prerinsing knives at 40 degrees C increases the performance of the subsequent dipping step. Models produced from the data in this study can be used to predict suitable combinations of time and temperature to achieve a desired bacterial reduction.

Combined Steam-Ultrasound Treatment of 2 Seconds Achieves Significant High Aerobic Count and Enterobacteriaceae Reduction on Naturally Contaminated Food Boxes, Crates, Conveyor Belts, and Meat Knives

“…Fastoperating meat processing plants may frequently experience difficulty in disinfecting meat knives with conventional cleaning techniques, where knives are hand washed in water at 20 to 40°C followed by brief immersion (less than 10 s) in 82°C water baths, termed " sterilizers." Immersions imple mented in some processing plants have been observed to be approximately 1 s, which did not have significant impact on bacterial reductions (9,25,26). On the other hand, longer immersions (10 s) of heavily contaminated knives in hot water baths often result in protein coagulations on the surface of the knives, which entrap surviving bacteria, leading to unsatisfactory bacterial reductions (26).…”

“…An optimized disinfection process has to reduce microorganisms to levels considered safe from a public health of view and to reduce the count of quality damaging microorganisms (16,17). General types of disinfection methods may include thermal disinfection, using a hot water or/and steam treatment at a specific treatment time and temperature, or a chemical disinfection with a specific concentration and surface contact time (2,7,9,16,17,20,28,30). Chlorine is among the most common food industry disinfection agents that target many types of bacteria and molds.…”

A hygienically designed force gripper for flexible handling of variable and easily damaged natural food products

“…These data indicate that it would be sufficient with a 0.05 s treatment in 95°C water to reach complete inactivation (6 log unit reduction). In a study by Goulter, butcher knifes smeared with a meat-culture were shown to require at least 20 s at 82°C for a 5 log unit reduction (Goulter, Dykes, & Small, 2008). Taking the temperature into consideration this would indicate treatment times of 0.37 s at 95°C.…”

Reduction of Escherichia coli O157:H7 and Salmonella after Application of Various Sanitizing Treatments to Harvesting Knives

“…Because international regulations require harvest sanitation, knives are typically sanitized with short-term immersion (1 to 5 s) in a ''knife sterilizer'' containing hot water (.82uC) (8). Previous studies aiming to validate different knife sanitations have shown promising alternatives to standard thermal sanitation.…”

“…Similarly, Salmonella Typhimurium DT104 was reduced by 2.39, 1.49, and 1.66 log CFU/cm 2 after a 15-s treatment with hot water (82.2uC), 440 ppm of 4-alkyl QAC, and 440 ppm of 4-alkyl acid QAC, respectively (18). Goulter et al (8) evaluated E. coli O157:H7 and Listeria monocytogenes reductions on knives dipped in water for 42 time-temperature treatment combinations. The authors concluded that short dips in hightemperature water (i.e., 82uC water for 1 s) reduce pathogen populations equivalent to a dip in lower temperature water for a longer time.…”