Novel refrigerated preservation performance indicator based on predictive microbiology and product time-temperature data, an essential tool to reach zero food waste

ABSTRACTThis study evaluates the performance of residential refrigerators, the worst cold chain point. Cooked ham temperature was used to quantify their performance as affected by compressor technology (single speed, SS/variable speed, VS), ambient temperature (21.1°C, LT/32.2°C, HT), load (22.5 kg, RL/39.0 kg, HL), sample type (F = fixed, M = moved to emulate consumption during meals), and door openings emulating consumer practices. Cumulative growth for each 48 h test period (LAB APIT(t)) was estimated deterministically and probabilistically, i.e. considering only means and including variability, respectively. APIT(t) at the 5°C recommended for ham yielded 0.6157 log CFU/g. The ratio APIT(t)/API5°C defined a refrigerator performance indicator (RPI) with values above and below 1 indicating poor and superior performance, respectively. While deterministic RPI values ranged from 0.99 to 1.72 (SS/LT/RL/F and VS/HT/HL/M conditions, respectively), probabilistic 95% RPI percentiles exceeded 1 suggesting poor preservation performance of the residential refrigerator tested under realistic conditions.