Effects of Initial Oxygen Stress Treatments in Low Oxygen Modified Atmosphere Storage of ‘Granny Smith’ Apples1

Abstract

Abstract ‘Granny Smith’ apples ( Malus domestica Borkh.) harvested over 7 weeks were not affected by alcoholic taints and were firmer, greener and less susceptible to scald and core flush following storage in 1.0% CO 2 and 1.5% O 2 (1.0:1.5) at −0.5°C as compared to present commercial modified atmosphere (MA) storage at 3.5% CO 2 :3.5% O 2 . Storage response was optimized by harvesting fruit with a starch-iodine maturity index of 5 to 6. With lower starch-iodine indices the incidence of core flush was increased, and at higher indices the potential for scald development increased substantially. Exposure of fruit to an initial O 2 stress at or below 0.5% for 9 days gave additional benefits in scald control, fruit firmness and color over continuous storage at 1.0:1.5. If O 2 was totally excluded by a 14-day treatment with continuous flow-through of O 2 -free nitrogen, core flush and alcoholic tainting increased, but scald decreased. Core flush following initial flow-through nitrogen treatments was also significantly increased by the effect of postharvest diphenylamine calcium chloride treatment or by an increase in storage temperature from 0° to 4°.