Studying the Effect of Ambient Temperature Exposure on Refrigerated Food Quality and Safety for Sustainable Food Cold Chains

Abstract

The temperature of chilled or frozen foods can be easily lost and the quality of them appears worse with frequent opening and closing of insulation compartment doors of vehicles while products are distributed to storage, retail places or households. It is particularly detrimental to food quality when foods are located in an environment having temperature between 7 and 60 °C because this could trigger most microorganisms to proliferate. With proper cold chain logistics, we can maintain food quality of refrigerated foods and protect public health from food contamination. It also could protect a lot of food waste because one third of food waste is resulted from improper food cold chains. By reducing food waste amount, the CO2 emissions for producing the food waste could be saved. The purpose of this study was to study how the quality and safety of refrigerated food are affected when the food is exposed to ambient temperatures. We designed several experiments to examine the microorganism Counts (8 kinds), water activity (WA), moisture and total volatile basic nitrogen (TVBN) of food samples—fresh (18 °C), chilled and frozen—placed at appropriate and non-compliant temperatures for different periods of time. The test results of foods stored at 25 °C show that there is no change on the test items when foods are stored at non-compliant temperatures for 3 h. The other experiment of foods stored at 25 and 37 °C both show that when foods are exposed to a longer period of time, say 12 h, many test results would go beyond the allowable range. The experimental results show that the central temperature of food does not change significantly within 3 h and thus as refrigerated foods are handled at the operational interfaces, a short period of time exposure, say 30 min, to ambient temperature, say below 15 °C, does not apparently affect food safety. However, at some extreme cases, it could affect food quality as the appearance temperature rises to −4 °C that original small ice crystals begin to thaw. Moreover, repeat exposure could also have accelerated accumulation effects on food quality.