Microbial Preservation Performance of Cold Storage Units Assessed by Modeling of Time–Temperature Data.

Globally, regulations focus on the energy use of cold chain units and not on their food preservation performance. Our hypothesis is that this reflects a lack of practical/science-based assessment protocols which is addressed in this work. About 3 million time–temperature values for fish fillets stored in the bottom drawer independently set at 0.0 °C and a peer-reviewed predictive model were used to assess the microbial preservation performance of a residential refrigerator operating at 5.0 °C. The temperature effect on the exponential growth rate of Pseudomonas spp. on fish fillets was used to generate a refrigerator preservation indicator (RPI) with values < 1, ~ 1, and > 1 describing excellent, acceptable, or poor microbial preservation performance, respectively. Experimental effects evaluated were refrigerator technology (single/variable speed compressor, SS/VS), ambient temperature (21.1/32.2 °C, LT/HT), refrigerator load (22.5/39 kg, RL/HL), and emulation of door openings during meal preparation. Deterministic RPI estimations for the VS compressor ranged from 1.28 to 1.71, while those for SS ranged from 1.13 to 1.24. Probabilistic estimations yielded confidence intervals also exceeding the desirable 1.0 value. Mean comparisons through Tukey's HSD identified p-values < 0.05 for all main effects; nonetheless, compressor technology was the most influential factor since the compressor × ambient temperature interaction was significant for both compressors and the compressor × food load interaction was significant for VS compressors. It is concluded that users of cold chain units would benefit from regulations covering energy use and preservation performance with the latter assessed by RPI determinations. [ABSTRACT FROM AUTHOR]