Comparative Analysis of Aroma Emission in ‘Gala’ Apples Stored in Ethanol and Hexanal-Enriched Controlled Atmosphere

The objectives of this study were to investigate extended exposure of ‘Gala’ apples to con-stant presence of ethanol and hexanal on the production of aroma compounds after long-term CA storage. 'Gala' apples were stored in CA under 2 kPa O2 and 98 kPa N2 at 1.0 ± 0.1 °C with a constant ethanol (CA-et) or hexanal (CA-he) concentration maintained at 50 µgL-1 throughout six month storage period. A total of 25 volatile compounds (VOCs) were identified. The Odor Activity Value (OAV) results showed that 9 VOCs were the key aroma compounds. Among them, hexyl acetate, 2-metyhbutyl acetate, and 1-butanol were the highest. Hexanal increased the production of hexyl acetate, while ethanol increased the production of 2-metyhlbutyl acetate and ethyl 2-methylbutanoate. Both precursors promoted the production of 1-butanol after two months of storage and 1 day of shelf life. Overall, the impact of the precursors on aroma production was more pronounced after two months than after six months of storage. Different storage atmosphere significantly influenced VOCs correlations, suggesting that ethanol and hexanal addition altered aro-ma biosynthesis pathways in ‘Gala’ apples. For varieties like ‘Gala’ that rapidly lose aroma during CA storage, CA-et and CA-he treatments may be beneficial for short-term storage, enhancing key aroma compounds and improving sensory quality.