1999 Volume 50 Issue 3 Pages 251-257
The role of cell wall components such as metal ions, pectins, hemicellulose and cellulose in the pressure-induced hardening of Japanese radish was investigated. The samples were treated by the application of a pressure of 400 MPa for 10 min and then left at atmospheric pressure for 0-24 h. As a result, the hardness increased by 1.3 times after pressurization and continued to increase with standing time for up to 2 h after the pressure had been released. The hardness of a sample which had been cooked at 99.5°C for 10 min after the pressure treatment increased by 2 times and continued to increase with standing time up to 11 h. When the hardness was increased, a decrease was observed in the concentrations of the calcium and potassium ions of hemicelluloses I and II contained in the cell walls. There were no significant changes in the polysaccharide fractions of the cell wall components with pressurization or standing. A small decrease in hemicellulose I, which is weakly hydrogen bonded to cellulose, and a small increase in hemicellulose II, which is more strongly hydrogen bonded, were observed with increasing standing time. The tissue pH value was decreased and alkali-insoluble proteins were increased by the pressure treatment as well as by the standing time after pressure had been released.
