Many food packaging materials used by the refrigerated food industry are hydroscopic and adsorb or desorb water depending on the conditions they experience as they pass through the cold chain. Packaging moisture sorption can have a significant effect on the air relative humidity (RH), the sensible heat ratio and therefore processes such as product weight loss, coil frosting and defrost, and condensation or frosting on other surfaces. The objective of this project was to provide refrigeration engineers with the methodology and data to estimate the heat load contribution due to moisture sorption to/from food packaging materials in refrigerated facilities.

The overall aim of this research was to provide refrigeration engineers with the methodology and data to estimate the latent heat load contribution resulting from moisture adsorption/desorption from food packaging materials in refrigerated facilities. The specific objectives were to:

• Conduct a review of scientific and technical literature to understand the mechanisms and theory related to moisture sorption by packaging in refrigerated facilities and to collate and compare previously published data on the moisture sorption behavior of packaging materials.
• Conduct a survey of North American packaging manufacturers and packaging users in the food industry to create a database of the amounts and types of packaging materials used within the North American chilled/frozen food industry.
• Review reference sources to obtain and confirm ranges of temperature and humidity representative of North American food storage conditions and climatic conditions.
• Measure the moisture sorption isotherms for important food packaging materials for which data over the appropriate ranges of RH and temperature do not exist. .
• Measure the moisture sorption rates for representative food packages and loads under conditions likely to be experienced in the cold chain.
• Develop and validate a general methodology for the prediction of moisture sorption rates for any specified package configuration and set of environmental conditions.
• Present the methodology to predict refrigeration loads due to water sorption by packaging in a form suitable for use by refrigeration design practitioners.