REHYDRATION KINETICS OF MICROWAVE-DRIED OKRAS AS AFFECTED BY DRYING CONDITIONS

• Published in: Journal of food processing and preservation 2009-10, Vol.33 (5), p.618-634
• Main Authors: APAR, DILEK KILIÇ, DEMIRHAN, ELÇIN, ÖZBEK, BELMA, DADALI, GÖKÇE
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Food engineering; Food industries; Fundamental and applied biological sciences. Psychology; General aspects
• ISSN: 0145-8892; 1745-4549
• DOI: 10.1111/j.1745-4549.2008.00277.x

The aim of the present work was to understand the effect of drying conditions (microwave output powers and sample amounts) and rehydration temperature on rehydration kinetics of microwave-dried okras. Four different models, Peleg's, Weibull, first order and exponential association, were applied to experimental data, and the corresponding parameters of the models were obtained. In addition, the kinetic parameters of the models were correlated with the ratio of microwave output power to sample amount and temperature. Although all the models applied provided a good agreement with the experimental data with high values of the coefficient of determination of R², the first-order kinetic model was chosen as the appropriate model because of its simplicity. By using the kinetic parameters of this model, the activation energy for rehydration kinetics was estimated as 1.15 kJ/mol. Drying, in general, is a means of removal of water from the material. The purpose of drying food products is to allow longer periods of storage with minimized packaging requirements, reduce shipping weights, and preserve seasonal plants and make them available to consumers during the whole year. Besides these advantages, some important changes take place, as structural and physicochemical modifications, which affect the final product quality during dehydration. Rehydration is a complex process aimed at the restoration of raw material properties when dried material contacted with water, and can be considered as a measure of the injury to the material caused by drying. The objective of rehydration study is to attain as many products in their original characteristics as fast as possible. An improved knowledge of rehydration kinetics would significantly enhance the feasibility of this process.