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Effective Moisture Diffusivity in Porous Materials as a Function of Temperature and Moisture Content
Author(s) -
Tong C. H.,
Lund D. B.
Publication year - 1990
Publication title -
biotechnology progress
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.572
H-Index - 129
eISSN - 1520-6033
pISSN - 8756-7938
DOI - 10.1021/bp00001a011
Subject(s) - thermal diffusivity , moisture , water content , materials science , porosity , shrinkage , arrhenius equation , desorption , volume (thermodynamics) , composite material , thermodynamics , chemistry , analytical chemistry (journal) , activation energy , chromatography , adsorption , physics , geology , organic chemistry , geotechnical engineering
Regular regime theory was used to evaluate the effective moisture diffusivity of a commercial white bread, plain sheet muffin, and baking powder biscuit as a function of moisture content based on desorption experiments. Volume shrinkage during drying was also monitored. The existence of regular regime periods in desorption processes for porous baked products was experimentally verified. Effective moisture diffusivity at temperatures between 20 and 100°C ranged from 2.5×10 −5 to 5.5×10 −3 cm 2 /s in the moisture range of 0.1–0.7 g of H 2 0/g of solid for bread, 9.35×10 −6 to 9.7×10 −4 cm 2 /s in the moisture range of 0.1–0.65 g of H 2 0/g of solid for biscuit, and 8.4×10 −6 to 1.54×10 −3 cm 2 /s in the moisture range of 0.1–0.9 g of H 2 0/g of solid for muffin. The effect of temperature on effective moisture diffusivity was adequately modeled by the Arrhenius relationship. Activation energies for bread, biscuit, and muffin were found to be independent of moisture content and were 51, 51, and 55 kJ/mol, respectively. Mathematical models to relate the effective moisture diffusivity to temperature and moisture content were developed.