EFFECT OF PRETREATMENT ON COLOR OF DEHYDRATED PRODUCTS |
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Authors: | M K Krokida CT Kiranoudis Z B Maroulis D Marinos-Kouris |
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Affiliation: | Department of Chemical Engineering , National Technical University of Athens , Zografou Campus, Athens, 15780, Greece E-mail: email: marinos@chemeng.ntua.gr. |
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Abstract: | ABSTRACT The effect of pretreatment on color of convective dried products (namely apple, banana, potato and carrot) was investigated. Five different types of pretreatment were taken into consideration; microwave, osmotic, sulfite, water blanching and steam blanching. Color characteristics were identified by measuring the color parameters (namely, Lightness (L), Redness (a) and Yellowness (b)) using a Hunter Lab chromatometer. The type of pretreatment was found to significantly affect the three color parameters. In addition, Redness (a) and Yellowness (b) were found to follow a first order kinetic model. Untreated dried materials showed an extensive browning, indicated by a significant drop of the L parameter and a corresponding increase of a, b parameters. Osmotically and microwave pretreated samples supressed browning compared to the untreated samples. In this case, lightness decreased slightly, while a, b increased slightly. Sulfite pretreatment prevented significantly color deterioration, while water and steam blanching also prevented enzymatic browning during convective drying. |
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Keywords: | Apple banana carrot microwave pretreatment osmotic pretreatment potato sulfite pretreatment steam blanching water blanching |
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