New methods to assess water diffusion in amorphous matrices during storage and drying |
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Authors: | A. Gianfrancesco G. Vuataz X. Mesnier V. Meunier |
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Affiliation: | 1. Nestlé Research Center, Food Science and Technology Department, Vers-Chez-Les-Blanc, CH-1000 Lausanne 26, Switzerland;2. Sheffield University, Sheffield S10 2TN, UK |
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Abstract: | Water diffusion coefficient is an important parameter for food processing and stability, strongly influenced by the composition and the physical state of the matrix (amorphous glassy or rubbery/crystalline). In this study, two different methods to assess water diffusion in amorphous matrices were compared. First, an automatic sorption device was used to measure the water sorption kinetics of powders of maltodextrin DE21 and DE47 with defined shapes when equilibrating at different air relative humidity (0–60% at 25 °C). Calculation of water diffusion coefficients was done according to Crank’s and Weibull’s models, and it was not possible when powders undergo glass transition. In the second part of the study a thin film dryer was used to assess the drying kinetics of aqueous solutions of maltodextrin (DE 6-12-29-40). The Yamamoto’s model allowed calculating water diffusion as a function of water content and temperature, above and below glass transition temperature. |
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Keywords: | Water diffusion Glass transition temperature Drying kinetics Sorption Powders Maltodextrin |
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