Absolute preservation indicator for the assessment of refrigeration performance based on dynamic temperature measurements and predictive microbiology

• Published in: Food control Vol. 136; p. 108891
• Main Authors: García-Cortés, Andrés, Martínez-Martínez, Enrique, Fernández-Villanueva, Gerardo, Torres-Valdez, Alejandro Yamaguchi, Fagotti, Fabian, García-García, Rebeca, de la Cruz Quiroz, Reynaldo, Torres, J. Antonio
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.06.2022
• Subjects: Absolute preservation indicator (API); Refrigerated storage preservation performance; Salmonella spp; Absolute preservation indicator (API); Salmonella spp; Refrigerated storage preservation performance
• ISSN: 0956-7135; 1873-7129
• DOI: 10.1016/j.foodcont.2022.108891

National and international norms have been established to assess the energy use of refrigerated food storage including compliance with the maximum allowed for residential refrigerators. However, norms on how to assess refrigerated food storage from a preservation point of view have not been developed. A published predictive microbiology model and ∼3 million time-temperature values collected for pasteurized egg white stored in the top door shelf of a customized refrigerator were used to estimate an absolute performance indicator (API) of refrigerated storage. Deterministic (only using mean values) and probabilistic (using 1000 normally distributed values) estimates of 48h-temperature-dependent cumulative exponential growth for Salmonella spp. were defined as API (log10 CFU/mL). APIs were used to assess the effects of low and high ambient temperature (21.1 °C [LT], 32.2 °C [HT]), regular and high refrigerator load (22.5 [RL], 39.0 kg [HL]), and single or variable speed (SS or VS) compressor technology. Also included were samples temporarily exposed to room temperature [M] simulating consumer use, or always kept refrigerated [F]. The severe variable speed compressor, high ambient temperature, and high load condition (VS/HT/HL) yielded the highest deterministic API values, i.e., API = 0.138 ± 0.033 and 0.211 ± 0.091 for F and M samples, respectively. The probabilistic analysis yielded 5/95% percentiles of 0.08/0.22 and 0.02/0.13 for F and M samples, respectively. The lowest API values were observed for VS/LT/HL reaching 5/95% percentiles of 0.00/0.05 and 0.01/0.05 for F and M samples, respectively. Compressor speed control modifications lowering product temperature and shortening temperature recovery time after door openings and product exposure to room temperature are necessary, particularly for refrigerators operating under high ambient temperature. Units offering low API values while meeting energy use guidelines would be preferred by consumers. •High variability illustrated constant temperature microbial assessment limitations.•Dynamic temperature data generated an effective refrigeration performance indicator.•Indicator confirmed the temperature risk of 70% or more of consumer refrigerators.•Cold chain optimization must consider energy use and preservation requirements.