Abstract
The purpose of this work was to study the effects of hydrostatic pressure treatment on sterilization, viscosity and browning of grated yam (Dioscorea. cv. Nagaimo) named "Tororo". Most of fungi and gram-negative bacteria in "Tororo" were sterilized by pressure treatment more than 500MPa at 20°C for 10min. However, gram-positive bacteria still survived even by the above-mentioned pressurization at 60°C. Granule size, degradation (by hog pancreatin) and viscosity of "Nagaimo" starch were almost unaffected by pressurization less than 600MPa, being different from the results by heat treatment at 60°C and 70°C. Decrease in viscosity of water extracts from "Tororo"treated at 500 MPa or higher was suppressed as compared with that of non-pressurized ones. Browning of "Tororo" treated at 300MPa or higher was suppressed. It was supposed that polyphenol oxidase in "Tororo" was inactivated by the pressure treatment.
