Effects of High Pressure on Softening of Japanese Radish and Decomposition of Pectin during Thermal Process

Abstract

The softening of Japanese radishes and the decomposition of pectin (0.5% pectin solution in 1/10 M phosphate buffer, pH 6.5) during the thermal process (100°C-110°C) under atmospheric and high pressures (100 MPa-400 MPa) were investigated. High pressure decreased the rates of softening for Japanese radishes and the decomposition of pectin during the thermal process. The activation volumes for the softening of Japanese radishes were 4.3 cm³/mol at 100°C and 3.1 cm³/mol at 110°C, and those for the decomposition of pectin were 10.4 cm³/mol (100°C) and 8.1 cm³/mol (110°C). Though the values indicated that the pressure lowered the pectin decomposition more than the softening of the radish, the ratios of the activation volume at 110°C to that at 100°C for both phenomena were nearly the same. These results suggested that the resistance to softening of the radish by pressure is closely related to the inhibition of the pectin decomposition in the radish by pressure.