Ethylene production of 'Hayward' kiwi fruit after ultralow oxygen or controlled atmosphere storage

The ethylene biosynthetic pathway of 'Hayward' kiwifruit at harvest and after storage in controlled atmosphere (CA) or ultra low oxygen (ULO) were studied. Fruit were stored for 60, 120 and 180 days at 0 degrees C in ULO (0.7 % O-2 + 0.7% CO2 and 1% O-2 + 1% CO2), CA (2% O-2 + 5% CO2) and air. Fruit placed at 20 degrees C in air (free of ethylene) at harvest, were not able to produce ethylene unless treated with propylene. The propylene treated fruit showed autocatalysis of ethylene production with concomitant changes in 1-aminocyclopropane-1-carboxylic acid (ACC) content and the activities of ACC synthase and ACC oxidase also named ethylene-forming enzyme (EFE). After 60, 120 and 180 days storage, there was an induction of ethylene production by chilling in CA and air stored fruit. However, with storage period the fruit showed a diminished capacity to produce ethylene. Fruit removed from ULO storage showed drastically reduced capacity to produce ethylene mostly due to low EFE activity than reduced ACC production or ACC synthase activity.