Effect of Debagging Time on Pigment Patterns in the Peel and Sugar and Organic Acid Contents in the Pulp of ‘Golden Delicious’ and ‘Qinguan’ Apple Fruit at Mid and Late Stages of Development

This study examined the effect of debagging time on color and flavor / taste compounds in the non-red apple cultivar 'Golden Delicious' and red cultivar 'Qinguan' at mid and late stages of fruit development. Debagging briefly improved the red color in both cultivars, the peel of 'Golden Delicious' presenting pale-pink hue. However, rapid anthocyanin accumulation occurred in apple peel at a specific time (after 179 days after flowering (DAF) in 'Qinguan') and was unaltered by debagging time in the red cultivar 'Qinguan'. Furthermore, untimely debagging had a detrimental effect on the content of anthocyanin. All sugars increased and organic acids decreased in apple pulp at mid to late stages of development. Bagging treatment reduced the content of most sugars and organic acids, as well as, the overall total. However, glucose and citric acid contents were higher in bagged fruit than non-bagged fruit; the maximum occurred in T7 treatment that was no-debagging at DAF 159 / 196 ('Golden delicious' / 'Qinguan'), i.e., 24.35 and 0.07 mg g-1 FW in 'Golden delicious', and 38.86 and 0.06 mg g-1 FW in 'Qinguan', respectively. In a word, bagging treatment can alter the pattern of peel color development in apple fruit; however, it remains difficult to alter the timing of rapid anthocyanin accumulation as it is regulated solely by development. Moreover, bagging treatment reduced the total accumulation of sugars and organic acids, and even the over total in pulp, but increased the glucose and citric acid contents in apple pulp.