OXYGEN STRESS OF GRANNY SMITH APPLES IN RELATION TO SUPERFICIAL SCALD, ETHANOL, ALPHA-FARNESENE, AND CONJUGATED TRIENES

Granny Smith apples were exposed to 2 levels of oxygen stress, <1% O-2 at 0 degrees C or <0.01% O-2 at 20 degrees C before storage at 0 degr ees C. Stress duration was 2-16 weeks at 0 degrees C and 1-10 days at 20 degrees C. The severity of superficial scald decreased as the perio d of O-2 stress was increased. The amount of ethanol in the juice incr eased as the period of O-2 stress increased. The accumulation of alpha -farnesene and conjugated trienes in the wax proceeded in all treatmen ts but the amount of increase become less as the period of O-2 stress was extended. Superficial scald was eliminated with an 8-day period of O-2 stress at 20 degrees C before cold storage or with 16 weeks O-2 s tress at 0 degrees C. It is suggested that control of scald by O-2 str ess may be due to increased production of ethanol and consequent reduc tion of alpha-farnesene and conjugated trienes accumulation.