Thermal analysis of a low-tech passive sensor for the assessment of food cooling rate in refrigerators and freezers

摘要

Slow cooling of cooked foods for storage has been linked to many foodborne illness outbreaks over the past 40 years. The Food Code of the United States Food and Drug Administration gives a target cooling rate, but no quantitative means of achieving it. In this article, a thermal analysis is used to show how cooling of a consistently defined mass in an in-use cooler leads to improved cooling in pans, a common means of food storage. The mass acts as a low-tech sensor from which temperatures are obtained from simple in-cooler tests. The analysis converts those temperatures to a pan food height that achieves adequate cooling. This sensor, composed of a standard coffee cup filled with ketchup with 5% added salt and covered with plastic wrap, is aimed at food service facilities, where budget and work time considerations limit options such as new equipment or extensive monitoring to improve cooling.