The relationship of dielectric response and water activity in food

Renshaw, Ryan C.; Dimitrakis, Georgios A.; Robinson, John P.; Kingman, Samuel W.

Abstract

This study has deduced a correlation between points of inflection of water activity and loss factor with respect to moisture content. A point of inflection in loss factor with respect to moisture content was found to coincide with the sorption isotherm point of inflection that defines the transition from multilayer to solution in every instance analysed, with an average difference of just 0.01kg.kg-1. Food can support microbial growth and chemical reactions in water activity levels above this critical transition. This correlation was discovered using published dielectric and sorption data for specific foods at similar temperatures. It was found that low sugar foods containing high levels of hydrocolloids generally exhibited different behaviour from fruits. This shows that microwave heating behaviour will be different in fruits compared to low sugar foods with high hydrocolloid content when drying to achieve a certain water activity and therefore shelf life.

Citation

Renshaw, R. C., Dimitrakis, G. A., Robinson, J. P., & Kingman, S. W. (2019). The relationship of dielectric response and water activity in food. Journal of Food Engineering, 244, 80-90. https://doi.org/10.1016/j.jfoodeng.2018.08.037

• Journal Article Type: Article
• Acceptance Date: Aug 31, 2018
• Online Publication Date: Sep 6, 2018
• Publication Date: 2019-03
• Deposit Date: Sep 17, 2018
• Publicly Available Date: Sep 7, 2019
• Journal: Journal of Food Engineering
• Print ISSN: 0260-8774
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 244
• Pages: 80-90
• DOI: https://doi.org/10.1016/j.jfoodeng.2018.08.037
• Keywords: Dielectric; sorption; water activity; multilayer; monolayer; food
• Public URL: https://nottingham-repository.worktribe.com/output/1077089
• Publisher URL: https://www.sciencedirect.com/science/article/pii/S0260877418303881