Ethylene biosynthesis of ‘Golden Delicious’ apples stored in different mixtures of carbon dioxide and oxygen

Abstract

Changes of 1-aminocylcopropane-1-carboxylic acid (ACC) synthase activity, ACC content, ACC conjugate content, and internal ethylene concentration were studied in ‘Golden Delicious’ apples ( Malus domestica Borkh.) stored for 64 days at 1°C in air or in mixtures of 1 or 3% O 2 with 0, 3 or 6% CO 2. Increases in ACC synthase activity, ACC content and internal ethylene concentration were generally slower in apples stored in the 1% O 2 mixtures than in the 3% O 2 mixtures; the inhibitory effects from both O 2 concentrations were magnified by increasing CO 2 concentrations. Apples stored in 0% CO 2 + 1% O 2 proved to be an exception, as they accumulated a relatively high amount of ACC. The Michaelis constant (K m) O 2 of the conversion of ACC to ethylene in peel tissue of ripe apples was estimated to be 1.3%. ACC conjugate accumulated during the storage period in apples stored in air or in the 3% O 2 mixtures, whereas no significant accumulation of ACC conjugate occurred in apples stored in the 1% O 2 mixtures.