Changes in the pectic substances of stored Elberta peaches

Abstract

Total and soluble pectic substances were determined in Elberta peaches ripened for 7 days at 70°F following storage at 30°F and 34°F for 7, 14, 19, 24 and 29 days. Some samples were gassed with ethylene (1000 p.p.m.) prior to storage. All fruit was mature-green when harvested.
A considerable loss of total pectic substances occurred in fruit which ripened normally following storage. Abnormal ripening of overstored fruit was associated with little or no loss in total pectic substances during ripening. A possible inactivation of the enzyme pectin methylesterhase is discussed in relation to this abnormal ripening.
A detailed account is given of an accurate and rapid method for the determination of total pectic substances in small quantities of mare prepared from fruit tissue. In this method, an infra-red gas analyser and a potentiometric recorder were used to measure the carbon dioxide evolved from fruit mare decarboxylated with hydrochloric acid.