Dynamic evaluation of the dehydration response curves of foods characterized by a poultice-up process using a fish-paste sausage. 1. Determination ofthe mechanisms for moisture transfer

In order to discern the mechanism for the transfer of moisture in foods as they are drying, the pore structure of food and the distribution of moistur e in food matrices were studied in detail by using a fish-paste sausage tha t was prepared with various contents of moisture (W-0). A uniform distribut ion of moisture was achieved with a poultice-up process. The void fractions (V-f) that occurred as a result of changes in the pore structure of the fo od were evaluated from a graphical analysis of SEM photographs on a cross-s ectional observation of the sausage. The V-f-values obtained changed drasti cally depending on the W-0) and were classified into two regions: I (W-0 > 100%-d.b.), which gave V-f =0.10 +/-0.08, and II (W-0 < 100%-d.b.), which g ave V-f =0.24 +/-0.05 at a drying temperature of 35 degreesC. For the analy sis of moisture state. the tempera ture-programmed desorption (TPD) profile s and the correlation time of water protons evaluated from nuclear magnetic resonance (NMR) were effectively used. The results produced three states o f moisture: weakly and strongly restricted water at Region I and gaseous wa ter at Region II.