Food Preservation Performance of Residential Refrigerators: Pasteurized Milk and Ground Beef as Animal Food Models

Abstract

This review focuses on the microbial food presservation performance of residential refrigerators which was evaluated using dynamic temperature values for pasteurized milk and ground beef stored in an experimental unit carefully replicating home use conditions. Milk and ground beef were respectively stored in the middle door shelf of a refrigerator set at 5 °C and in its bottom drawer equipped with independent temperature control set at 0 °C. Room temperature, refrigerator load, door openings, and variable/single speed compressor technology were evaluated for their effect on ground beef and milk temperature. During door openings, half of the milk samples were removed and temporally kept at room temperature to simulate consumer use. Temperature profiles collected illustrated the need to move away from food preservation assessments at constant temperature. Deterministic and probabilistic values of 48 h exponential growth (ΔlogN48 h), used as a food preservation indicator (PI), showed the need to improve the temperature control strategy for refrigerators using variable speed compressors to benefit from their energy efficiency and operation flexibility. Large PI values for refrigerators with single and variable speed compressor technology indicated that product temperatures must be lowered, particularly for milk stored in door shelves. The ratio of PI values at the recommended constant refrigerated temperature for each product and values under the experimental temperatures collected in this study were used to define a relative preservation index (RPI) to facilitate the establishment of a food preservation performance standard reflecting the ability of refrigerators to ensure food safety and extend shelf life.