Dehydration of Scallop by Far-infrared Radiation Vacuum Drying

Abstract

Among the various drying methods, vacuum freeze drying offers the advantages of a minimum level of quality deterioration and a very high degree of rehydration. However, vacuum freeze drying is rarely used industrially on thick and bulky sea foods such as the scallop, because dehydration by ice sublimation is very energy-inefficient and it takes long time to dehydrate foods. Solar drying and hot air drying bring about significant differences in food color and texture. Thus the present study aimed to develop a drying method that is capable of preserving a food's original properties as much as possible. This report discusses our investigation of a novel method of vacuum drying using FIR. Using this method, food preprocessed by boiling or other processes is not frozen, but is immediately transferred to a drying stage, and food is dehydrated under conditions which do not freeze the product until it is completely processed. The samples used in the present study were the adductor muscles of scallop, which is too thick and bulky for vacuum freeze drying. The quality of the product obtained by FIR vacuum drying was almost the same as that obtained by vacuum freeze drying with respect to color, shrinkage, hardness, rehydration efficiency, and sensory tests.