Temperature of hypoxic treatment alters volatile composition of juice from 'Fuji' and 'Royal Gala' apples

Exposure of apples to hypoxia induces changes in volatile concentrations in extracted juice, potentially affecting aroma quality, but there is little information on how the temperature of hypoxic treatment may affect volatile concentration. 'Fuji' (FU) and 'Royal Gala' (RG) apples were exposed to hypoxia, 100% CO(2) for 24 h, at 10 degreesC, 15, 20 or 25 degreesC and maintained at treatment temperature for up to 14 days. CO(2) and ethylene production and firmness of intact fruit were proportional to temperature but were unaffected by exposure to hypoxia. Ethyl esters from extracted juice were enhanced at all temperatures at differential rates according to cultivar. Four patterns of total Volatile concentration change with temperature after exposure to hypoxia were identified which may be related to changes in rates of volatilisation and Volatile production. Apples treated and maintained at 10 degreesC had the greatest overall enhancement of ethyl esters and least decrease in other esters in juice compared to apples treated and maintained at 15, 20 and 25 degreesC. This enhancement in volatiles persisted for up to 10 days after removal from hypoxia. Maintenance of apple quality after treatment with hypoxia was better at low temperatures suggesting that apples treated with hypoxia and maintained below 15 degreesC would have enhanced volatile concentrations compared with untreated apples and apples maintained above 15 degreesC. (C) 2001 Elsevier Science B.V. All rights reserved.