Effects of Calcium Treatment on Calcium Forms, Pectin Content and Related Enzyme Activities in Harvested Pear Fruits
采后钙处理对梨果实钙的形态和果胶及相关代谢酶类影响的研究

Harvested pear (Pyrus pyrifolia) fruits were dipped in calcium solution to investigate the effects ofcalcium chloride solution treatment on the content of pectin, the contents of different soluble calcium, the changes in activities of pectinesterase (PME) and polygalacturonase (PG) and on the fruit firmness. The results showed that calcium solution treatment significantly increased total calcium content in fruits, improved fruit firmness and maintained permeability of cell membrane significantly. The content of NaCl soluble calcium was highest intreated fruits, followed by water-soluble calcium, calcium acerate and HCl-soluble calcium. An increasee inwater-soluble calcium was observed on the 21st day in treated fruits, while NaCl soluble calcium decreased. The contents of water-, NaCl- and HCl-soluble calcium increased significantly after calcium treatment except for acetic acid soluble calcium. Calcium treatment delayed degradation process of pectin and inhibited PG activity, but had no obviously inhibitory effect on PME activity. Effect of calcium treatment on fruit firmness was probably related with the inhibitory effect of PG activity.