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The relationship of dielectric response and water activity in food

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


Ryan C. Renshaw

Georgios A. Dimitrakis

John P. Robinson

Samuel W. Kingman


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 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.

Journal Article Type Article
Publication Date 2019-03
Journal Journal of Food Engineering
Print ISSN 0260-8774
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 244
Pages 80-90
APA6 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). doi:10.1016/j.jfoodeng.2018.08.037. ISSN 0260-8774
Keywords Dielectric; sorption; water activity; multilayer; monolayer; food
Publisher URL


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