PHYSIOLOGICAL CHANGES IN DIPHENYLAMINE-TREATED ‘GRANNY SMITH’ APPLES

Abstract

ABSTRACT ‘Granny Smith’ apples were subjected to a postharvest dip of 3000 ppm diphenylamine (DPA) for 30 s and placed in 0°C regular air storage for 3 or 6 months. Firmness and acidity of DPA-treated apples were greater than those of the control fruit after 6 months of storage plus 1 week at 20°C. After 3 months of storage, ethylene production in DPA-treated apples was lower than in control apples, while after 6 months the opposite was true. Respiration of DPA-treated apples was lower than that of control fruit after both storage periods. DPA prevented the development of superficial scald during storage and subsequent shelf life, while untreated apples developed severe scald. The concentration of α-farnesene in apple cuticles was two to three times higher and the levels of conjugated trienes were four to seven times lower in DPA-treated apples than in control fruit. The activities of polyphenoloxidase (PPO), peroxidase, and lipoxygenase were lower in the peel of DPA-treated apples than in untreated fruit...