Fermentative Metabolism in 'Jonagold' Apples under Controlled Atmosphere Storage

摘要

The fermentative metabolism was studied in cv. 'Jonagold' apples stored at 0 °C in the following controlled atmosphere (CA) conditions: 6 kPa CO_2 + 0.5 kPa O_2; 3 kPa CO_2 + 1 kPa O_2; 1 kPa CO_2 + 2 kPa O_2, and also in regular air (RA) as a control. Apples in RA storage showed very low pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH) activity, and low concentrations of acetaldehyde and ethanol. The production of lactate, and the activity of lactate dehydrogenase (LDH) in apple fruit were inhibited during storage, but a slight increase was observed during subsequent 8 days shelf-life at 20 °C. During CA-storage, cv. 'Jonagold' apples both the activity of PDC and ADH in-creased with a corresponding accumulation of acetaldehyde and ethanol, mainly in fruits stored at high CO_2 and/or low O_2 partial pressures. Both enzymes, and their products, decreased to low levels during the 8 days shelf-life at 20 °C after CA-storage. Lactate content and activity of LDH in CA-stored fruit showeda similar behaviour to the RA-stored fruit, however, the reduction of the enzyme activity was greater under CA-conditions. Overall, it is concluded that cv. 'Jonagold' apple fruit synthesize minute amounts of lactate and LDH and play a minor / negligiblerole in the fermentative metabolism of cv. 'Jonagold' and possibly other apple fruit.