Carbohydrate Concentrations of Apples and Pears as Influenced by Irradiation as a Quarantine Treatment

Commercially packed Fuji and Granny Smith apples and Anjou and Bosc pears were exposed to irradiation treatments using a gamma beam 650 source containing cobalt-60 at doses of 150, 300, 600 and 900 Gy. After irradiation, apples were stored for 30, 60 and 90 days, while pears were stored for 30 and 90 days in ambient atmosphere at 1C. Analysis of carbohydrate concentrations of the fruit flesh were conducted during and after each storage period. Irradiation treatment did not influence the total carbohydrate or individual sucrose, glucose, fructose, or sorbitol concentrations in either apples or pears, regardless of the cultivar. Carbohydrate concentrations changed in both apples and pears as storage time progressed and these changes were cultivar dependent. Total carbohydrates and glucose, fructose and sorbitol concentrations increased, and sucrose decreased in apples as storage progressed. Total carbohydrates and fructose increased; whereas, sucrose, glucose and sorbitol concentrations decreased in Anjou pears as storage progressed. Total and individual carbohydrate concentrations decreased in Bosc pears as storage progressed from 30 to 90 days.