CHANGES IN HEADSPACE VOLATILES DURING PHYSIOLOGICAL DEVELOPMENT OF BISBEE DELICIOUS APPLE FRUIT

Volatile compounds produced by Delicious apple fruit during the 8-week transition period from pre- to postclimacteric were identified using headspace sampling of intact fruit and GC-MS. As apple development progressed, concentrations of butanal, pentanal, (E)-2-hexenal, and heptanal declined. Concentrations of most alcohols were variable throughout the same period, but 2-methyl-1-butanol was present only in samples from the late harvests. Ketones lacked a discernible pattern, while some esters, most notably 2-methylbutyl acetate, appeared in samples before the onset of ethylene production. Acetic acid was present in the samples throughout the harvest period, indicating alcohol substrate availability may be the limiting factor in ester formation. Production of several acetate esters preceded the increased ethylene levels associated with the onset of apple ripening.