EVALUATION OF THE BACTERIOLOGICAL CONSEQUENCES OF THE TEMPERATURE REGIMES EXPERIENCED BY FRESH CHILLED MEAT DURING RETAIL DISPLAY

Temperature histories were recorded from the surfaces of chilled steaks in a commercial retail case. Steaks were placed at the rear, centre or front of the case, and at 17 or 13 cm below, or 4 cm above the load line. The coldest average temperatures (1.7-4.5-degrees-C) were recorded at the rear, and the warmest (6.1-10-degrees-C) at the centre of the case. Average temperatures increased with upward location of the steaks, from between 1.7 and 6.1-degrees-C at 17 cm below to between 4.5 and 10-degrees-C at 4 cm above the load line. The meat surface temperatures did not correlate with the air temperatures at the rack level. The average temperatures for steak surfaces and case air in the vicinity of steaks differed by up to 1-degrees-C, but the surface and deep temperatures of steaks were similar. Calculated values for the proliferations of psychrotrophic pseudomonads and Escherichia coli correlated well with the average surface temperatures of the steaks. Apparently, E. coli growth would be negligible with average surface temperatures of less-than-or-equal-to 4-degrees-C. However, a survey of air temperatures in four commercial retail cases indicated that temperatures of less-than-or-equal-to 4-degrees-C cannot be maintained throughout existing retail cabinets. To assure food safety, some means of identifying the maximum average temperature experienced by a product in individual display cases is required, with a specification of the maximum residence time that can be tolerated at any maximum temperature.