Moisture Transfer Properties of Dry and Semimoist Foods

Abstract

ABSTRACTEquilibrium moisture content, mass diffusion coefficients, and densities were collected for wheat flour, shredded wheat, raisins, nonfat dry milk, and freeze‐dried apple, turnip, and ground beef at 25 ± 1°C. Flour adsorbing to 0.75 aw had the largest mass diffusion co‐efficient, 1.15 × 10−7 m2/hr and raisins had the smallest value of 0.015 × 10‐7 m2/hr. Two of the food uroducts. flour desorbing to 0.11 aw, and the freeze‐dried turnip, exhibited diffusion coeffcients which were dependent on the moisture content. Most of the foods reached equilibrium within 1 wk based on an objective criterion of no more than a 0.5% dry basis moisture difference over three successive readings at 1 wk interval.