The Effect of Temperature, Pressure and Chlorine Concentration of Spray Washing Water on Numbers of Bacteria on Lamb Carcases

Abstract

Combined analysis of three experiments showed that when lamb carcases with initial bacterial numbers of between logi 10 3.29 and 4.22/cm 2 were spray washed, statistically significant reductions in bacterial numbers of log 10 O.5 were obtained when the spray wash water temperature was > 57°C, and reductions of log 10 1.0 were obtained when the temperature was ≥ 80°C. Reductions at all temperatures were enhanced by log 10 0.66 when the water contained 30 µg/ml chlorine, but increasing the concentration to 450 µg/ml reduced bacterial numbers only by a further log 10 0–29. At highly contaminated sites increasing the duration of spraying from 30 to 120 s significantly increased the reductions obtained when water containing added chlorine was used. Reductions in bacterial numbers after spray washing with pressures of 3.5, 5.6. 7.7 kg/cm 2 were not significantly different.