356 Leatheriness and Mealiness of Peaches, Their Biochemical Characteristics Related to Fruit Maturity and Storage Temperature

Abstract

`Huangjin' peaches were harvested at immature, mature, and over-mature stages according to ground color and firmness evaluations, and were stored at 0, 5, and 10 °C, respectively. After 4 weeks of cold storage, immature fruit developed a higher percentage of leatheriness but a lower level of mealiness than mature fruit. Over-mature fruit did not develop leatheriness, but developed a higher percentage of mealiness than mature fruit. Fruit stored at 5 °C developed more mealiness than fruit stored at 0 °C for the same period of storage, while fruit stored at 0 °C developed more leatheriness than fruit stored at 5 °C. When stored at 10 °C, fruit did not develop any leatheriness or mealiness regardless of maturity. Compared with juicy and mealy fruit after the same period of cold storage, fruit with leathery symptoms were significantly firmer following 4 days at 20 °C. 1-Aminocyclopropane-1-carboxylate oxidase (ACO) activity, 1-amino-cyclopropane-1-carboxylic acid (ACC) content, and polygalacturonase (PG) and β-galactosidase (GAL) activity were lower, and insoluble pectin content was higher, in leathery fruit than that in juicy and mealy fruit. Mealy fruit were as soft as juicy fruit after ripening at 20 °C for 4 days. Their ACO, PG, and GAL activity; ACC; and insoluble pectin content were similar. Results indicated that leatheriness is a typical chilling injury but mealiness is not.