Quality of pectin in pears, with special reference to the changes during maturation and subsequent after-ripening in Bartlett pears

Abstract

Changes of quality in the pectic substances of Bartlett pears produced in the different growing areas during maturation and after-ripening, of canned products of ripened Bartlett pears, and of Japanese pears of optimum ripeness were investigated. Preparation and extraction of pectic substances from pears: The fruits were peeled, halved, cored and grinded. They were extracted with boiling 70% ethylalcohol to remove sugars. Extraction of pectin from sugar-free dried samples was performed successively with three agents in the order; cold water, cold 0.4% sodium hexametaphosphate, and 0.05N hydrochloric acid at 85°C. Water soluble pectinate and pectate (WSP) were extracted with cold water, water insoluble pectinate and pectate (PSP) with hexametaphosphate solution, and protopectin (HSP) with hydrochloric acid solution. Total pectin is the sum of these three fractions. Pectin content (Capectate), inherent viscosity and pectin unit were determined for each extracted pectin solution.