Production of acetaldehyde and ethanol during maturation and modified atmosphere storage of litchi fruit

The emission of the metabolites, acetaldehyde (AA) and ethanol, from litchi fruit was monitored during maturation and storage. Juice extracted from the arils at various stages (green, breaker, pink and red pericarp) during the season, contained increasing amounts of AA and ethanol. These increases, in mature fruit, were accompanied by a pronounced decrease in the soluble solids content (SSC) and an increase in titratable acidity of the juice. In parallel to juice analysis at harvest, red pericarp fruit were packed in laminated films, creating modified atmosphere packaging (MAP). Late-harvested whole fruit in MAP produced more AA and ethanol than early-harvested ones. Intensified production of AA and ethanol was found in later-harvested litchi, during cold storage and shelf life in MAP, and late-harvested fruit also showed increased decay after cold storage. These results suggest that mature litchi fruit deteriorated when kept longer on the tree during the harvesting season. This may be ascribed to a fermentation process that began on the tree and caused deterioration during MAP storage.