Effects of fruit bagging on anthocyanins, sugars, organic acids, and color properties of 'Granny Smith' and 'Golden Delicious' during fruit maturation

The effects of fruit bagging on anthocyanins, sugars, organic acids, and color properties of 'Granny Smith' and 'Golden Delicious' were investigated in this study. Young fruits were bagged 40 days after flowering (DAF) with paper bags. The bagged fruits of 'Golden Delicious' were uncovered and exposed to light 120 DAF, while those of 'Granny Smith' 160 DAF. The fruits were harvested after 0, 2, 4, 6, 8, 10, and 15 day of bag removal, respectively. The development of anthocyanins, sugars, organic acids, and color properties in the flesh of 'Granny Smith' and 'Golden Delicious' was determined. After bag removal, the 'Granny Smith' and 'Golden Delicious' turn red, a* was consequently augmented, while L*, b*, C*, and h(0) reduced. Cyanidin 3-galactoside and cyaniding 3-arabinoside were identified in 'Granny Smith' and 'Golden Delicious' as the two constituents responsible for red color of apple peel, and with cyanidin 3-galactoside being the most abundant anthocyanin in these non-red cultivars. Fructose, sucrose, and sorbitol were the major sugars and sugar alcohol, and malic acid was the major organic acid. Concentrations of most sugars and all organic acids quickly increased during 0-4 DABR, suggesting that synthesis of these sugars and organic acids was inhibited by fruit bagging. Furthermore, the cy3-gal and cy3-ara accumulation of all tested cultivars was significantly correlated with sucrose, indicating that sucrose may be the more important factors in the biosynthesis of anthocyanin.