The Relationship Between Pulp-Soaking Symptom in Pummelos (Citrus grandis L. Osbeck) and Their Struture, Calcium Content, Pectin Methylesterase Activity and Internal Gas Composition

Abstract

Steuturally, Juice-sacs of Khao-thongdee cultivar contained epidermal cells which have thicker outer wall than Khao-pan, and also contained fewer layers of subepidermal cells. No change was found in the outer wall of epidermal cells but the side walls of both epidermal and subepidermal cells were weaken after storage. Calcium content in Khao-thongdee was about double the amount in Khao-pan. Pectin-methylesterase activity was also significantly higher in Khao-thongdee. The relationship between calcium content. Pectin-methylesterase activity and pulp-soaking sympyom, however, could not be clearly explained. Difference in internal concentrations of carbon dioxide and ethylene between the two cultivars were small and were not likely to be the factors involving the development of the symptom.