THE EFFECT OF HARVEST DATE ON AROMA COMPOUND PRODUCTION FROM GOLDEN-DELICIOUS APPLE FRUIT AND RELATIONSHIP TO RESPIRATION AND ETHYLENE PRODUCTION

The maturity of apple fruit at harvest was examined as a factor affect ing later flavour development. Respiration, ethylene production and ar oma compound emanation at 20 degrees C from ripening 'Golden Delicious ' apple fruit harvested at different stages of maturity and their chan ges during ripening were studied. Volatile compound production was hig hly maturity-dependent and closely related to the changes in the respi ratory rate and ethylene production. Earlier-harvested fruit (4 weeks ahead of the climacteric rise) had reduced respiration, and ethylene p roduction, with lower and later total aroma synthesis than that for op timal-harvested fruit. Among the 36 aroma compounds identified by GC-M S, four flavour and character impact compounds were examined in detail . The onset of production and rates of synthesis of butylacetate, hexy lacetate, 2-methylbutylacetate and ethyl-2-methylbutanoate during matu ration and ripening were determined. The production trends of straight -chain (butylacetate and hexylacetate) and branched-chain (2-methylbut ylacetate and ethyl-2-methylbutanoate) volatile compounds were similar to that of total aromas, except for a later increase in ethyl-2-methy lbutanoate. As fruit development approached optimal harvest date for f ruit quality, respiration, ethylene- and aroma production occurred wit h less of a delay reaching greater maximum levels, It is suggested tha t fundamental physiological processes such as respiration and ethylene production may be limiting factors for volatile production in earlier -harvested fruit.