Aroma Volatile Production in Preharvest AVG-treated `Golden Delicious' Apple Fruit and the Effect of Poststorage Ethylene Treatment

Abstract

Changes in the profile of aroma volatiles during ripening and after ethylene treatment in apple fruit have revealed a close relationship exists between ethylene production and the timing and magnitude of volatile synthesis. Therefore, AVG (ethylene biosynthesis inhibitor) was used to study the relationship between volatile biosynthesis and metabolic processes affected by ethylene in apple fruits. AVG-treated fruit were stored either for 1 month at 2C in air or 5 months in ULO condition. During the post-storage ripening, the fruits were exposed to 50 μl·liter–1 of ethylene at least 12 h/day. Aroma production was determined at 20C. Total volatile compound production by AVG-treated fruit was much lower than that of untreated fruit. A significant increase in the production of most aroma volatile after 1 month storage in air was induced by ethylene treatment to AVG-treated fruits. I was noted that branched-chain volatile, such as 2-methylbutylacetate, which originates from branched-chain amino acids, has increased prior to butylacetate and hexylacetate, which are derived from fatty acids. Ethylene treatment was unable to stimulate the production of straight-chain volatile compounds following the 5 months of ULO storage. These results are consistent with observations suggesting apple fruit lose their sensitivity to ethylene after long ULO storage.