Effects of different color paper bags on aroma development of Kyoho grape berries

This study investigated the influence of red, green, blue, and white paper bags on the free volatile compound development of Kyoho grape berries from green to harvest. Seven functional groups of volatiles were identified during the development of Kyoho grape berries including esters, aldehydes, alcohols, terpenes, ketones, acids, and hydrocarbons. Esters and aldehydes were abundant in Kyoho grape berries, mainly represented by ethyl acetate, ethyl butyrate, and (E)-2-hexenal. They accumulated quickly after veraison and slightly decreased toward maturation. Red, green, blue, and white paper bags promoted the accumulation of esters and inhibited the accumulation of aldehydes, also inhibited the accumulation of alcohols, tepenes, ketones, and acids. Their effect from strong to weak was green, blue, red, and white paper bags. The expression profiles of genes in the lipoxygenase-hydroperoxide lyase (LOX-HPL) pathway were also analyzed and the results indicated that the regulation of red, green, blue, and white paper bags on aldehydes, alcohols, and esters volatile aromas was at transcriptional level. The results expanded our comprehension in grape aroma biosynthesis and berry bagging technique in table grape cultivation.