Role of Calcium and Magnesium Ions in the Hardening of Pressure-treated Root Vegetables

Abstract

The hardness of Japanese radish was increased by pressurization and standing after the release of pressure. We measured the variations of pectin fractions with time after pressure release. Only the hexametaphosphate-soluble pectin, which is bound to divalent metal ions, increased slightly after standing. Calcium ion content in water-soluble pectin was decreased by pressurization. Water-soluble calcium ions decreased with pressure treatment and standing. However, sodium chloride-soluble calcium ions, which are bound to tissue components, increased. The hardening is considered to be brought about by changes in the interactions among tissue components. It is also suggested that calcium ions play an important role in pressure-induced hardening. © 1998, The Japan Society of High Pressure Science and Technology. All rights reserved.