Application of brief hot water soaking as a pre-treatment in kiwifruit drying

Abstract

Fresh kiwifruit slices were pre-treated (brief hot water soaking) before drying, and the effects of pre-treatment on the hot air drying characteristics were evaluated. Change in color, volume, surface area, mass, temperature and surface hardness of kiwifruit samples during hot air drying were measured at 40, 50, 60 and 80?. The pre-treatment inhibited color change by inactivating enzymes, and the color difference (ΔE) during the drying process was expressed according to an equation describing the reaction kinetics. The volume ratio and surface area ratio were best described as a linear function of moisture content. The pre-treated samples had shorter drying times and higher drying rate than control samples. In addition, a constant-rate drying period was found in the pre-treated samples in the initial period of the drying process. Brief hot water pre-treatment increased the drying rate because it inhibited the surface hardness of the sample. Copyright © 2014, Japanese Society for Food Science and Technology.