Postharvest changes in the phenolic and free volatile compound contents in Shine Muscat grapes at room temperature

Herein, we studied changes in the contents of phenolic and free volatile compounds in Shine Muscat grapes stored at room temperature. Berry quality was maintained up to 11 d after harvest, and the levels of 35 phenolic compounds were observed to increase during storage. This increase is attributed to the upregulation of genes, including phenylalanine ammonia-lyases, 4-coumarate-CoA ligases, and stilbene synthases, in the phenylpropanoid pathway. The concentrations of total and rose-flavored volatiles, including terpenes and particularly monoterpenes, decreased in postharvest berries, which was attributed to the downregulation of genes in the mevalonate and 2-C-methyl-D-erythritol 4-phosphate pathways. By contrast, the C₆ compound content increased during storage, which might have played a role in the upregulation of lipoxygenase and hydroperoxide. Additionally, the marker compounds rutin and 1-hexanol were identified during storage. Therefore, this study suggested that the health benefits and C₆ compound-derived flavor increased, whereas the rose flavor decreased in postharvest berries.