EFFECT OF ETHYLENE ON CERTAIN CHEMICAL CHANGES ASSOCIATED WITH THE RIPENING OF PEARS

Abstract

Bartlett pears were picked at 5 stages of maturity during the growing season and divided intoo 2 lots[long dash]one treated with ethylene in a concentration.of''U1.0p(^by volume, the other provided with. constant aeration to prevent any accumulation of ethylene produced by the fruit. Samples for chem. analysis were taken at regular intervals during the course of ripening and detns. of total and reducing sugars, starch, pectin, protopectin and acid were made. The fruit ripened in the presence of ethylene contained more total and reducing sugars, sucrose, and pectin, but less starch and protopectin than that ripened in the absence of ethylene. No differences in titratable acidity were found. The increase in rate of softening in the ethylene-treated fruit was found to be correlated with an increase in the rate of pectic changes. The greatest effects from ethylene treatment were obtained from fruit picked early in the season. The ripening of Bartlett pears which had been held at 31[degree] F for 3 weeks was not hastened by use of ethylene treatment, and no significant differences in chem. composition of treated and untreated fruit were found. Beurrq d'' Anjou pears treated for 12 days at time of storage contained more total and reducing sugars, and soluble pectin but less protopectin and starch than the untreated samples. Similar fruit treated after 3 weeks'' storage showed no increase in sugars or in rate of starch hydrolysis over that found in untreated fruit. Pectic changes and rate of respiration, however, continued to be affected by ethylene even after 8-10 weeks of storage.