Characteristic innovation of a food drying process revealed by the physicochemical analysis of dehydration dynamics

A typical food drying process was characteristically innovated by using a water tank model derived from the physicochemical analysis of dehydration dynamics. A fish paste sausage was effectively used, as a model food, to evaluate five characteristic parameters for water movement; effective diffusion coefficient (De), diffusion activation energy (E-D), void fraction of dried sausage (V-f), and proportion of weakly restricted water (f(w)), and strongly restricted water (f(s)). The dehydration curves obtained were clearly classified into two regions that were divided at a 100%-d.b. of water content (W-0); region I (W-0 larger than 100%-d.b.) and II (W-0 smaller than 100%-d.b.). The molecular states of moisture in the sausage structure were characterized, using the Temperature Programmed Desorption (TPD) and proton-NMR methods, as liquid water in region I and as gaseous water in region II. A mathematical model based on the water tank model was developed as a function of E-D, V-f, f(w) and f(s). Using a computer simulation technique, a significant enhancement of the drying process, 2.0-3.5 times acceleration of drying rate and 1.18-1.11 times shortening of drying time, was proposed by use of the poultice up operation in region II rather than in region I. Published by Elsevier Science Ltd.