Characterization of changes in 'Gala' apple aroma during storage using osme analysis, a gas chromatography-olfactometry technique

Changes in the odor-active volatile compounds produced by 'Gala' apples [Ma lus >sylvestris (L.) Mill. var. domestica (Borkh.) Mansf, 'Gala'] were meas ured after 4, 10, and 20 weeks storage at I UC in regular atmosphere (RA) o r controlled atmosphere (CA), and 16 weeks in CA followed by 4 weeks in RA, Aroma was evaluated using the gas chromatography-olfactometry method Osme. Production of volatile esters decreased along with corresponding fruity ar omas during CA storage. Hexyl acetate, butyl acetate, and 2-methylbutyl ace tate were emitted in the largest amounts and perceived with the strongest i ntensities from RA-stored fruit. While hexyl acetate and butyl acetate conc entrations and aroma intensities decreased during CA storage, 2-methylbutyl acetate remained at the RA concentration until apples had been stored 16 w eeks in CA. Perception intensities of methylbutyrate esters with apple or b errylike odors decreased less than straight chain esters in CA-stored fruit . 4-Allylanisole, beta -damascenone, and 1-octen-3-ol, as well as an unknow n compound with a watermelon descriptor, were perceived more in RA-stored f ruit than in CA-stored apples. Factor analysis indicated the importance of these compounds in 'Gala' apples stored 4 weeks in RA. Even though these co mpounds do not have an apple odor, they contribute to fresh 'Gala' aroma.