Effect of Anaerobic Atomosphere on Acetate Ester Biosynthesis and Alcohol Acyltransferase Activity in Bananas

Aroma is an important contributor to the quality of fruits. The effects of anaerobic condition on the production of volatile compounds including acetate esters, and the activity of alcohol acyltransferase (AAT) in bananas were investigated. Incubation of the pulp in less than 1% O2 resulted in a significant reduction in the formation of acetate esters. Regardless of the presence of a higher level of endogenous and exogenous alcohols in the pulp under anaeorobic conditions, the production of acetate esters decreased. When pyruvate, isobutyl alcohol, and methyl hexanoate were added to the pulp, lower acetate ester production was detected under anaerobic conditions than in aerobic storage. When yellow ripened bananas were exposed to short-term anaerobic conditions (12, 24, and 48h), higher levels of ethanol and acetaldehyde were detected. Immediately after releasing the fruit from the anaerobic atmosphere, isobutyl acetate and isoamyl acetate were decreased but recovered later. The increase in AAT activity was slightly lower under anaerobically treated fruits than untreated fruit. However, the lower activity in treated samples was suffiient ofr the ester production in bananas. The results suggest that acetate esters cannot be produced without oxygen due to inhibition of production of acetyl CoA derived from pyruvate via mitochondria and beta-oxidation of long-chain fatty acids.