Effects of position on canopy and harvest time on fruit physico-chemical and antioxidant properties in different apple cultivars

Fruit from Granny Smith, Fyriki, Fuji Kiku 8, and Imperial Double Red Delicious apple (Malus domestica Borkh.) trees planted in single or double rows, were harvested from different positions in the canopy, during the last month before commercial harvest. Fruit physico-chemical and antioxidant capacity, using the radical DPPH, were measured, in skin and flesh tissue. Greater total phenol content and total antioxidant capacity per fresh weight and serving portion of skin and flesh tissue, were found in Imperial Double Red Delicious and Fyriki apples, compared to Granny Smith and Fuji Kiku 8. The variation among cultivars in antioxidant contents was greater in peeled, compared with unpeeled fruit, highlighting the importance of eating unpeeled fruit. During the last two weeks before commercial harvest the total phenol content and total antioxidant capacity per fresh weight increased in skin of Granny Smith (by 24% and 42%, respectively) and Fuji Kiku 8 (by 19% and 27%, respectively). Fruit from the more sun—exposed parts of canopy had usually better red coloration and the effect was more pronounced in Fuji Kiku 8 and Fyriki, followed by Imperial Double Red Delicious and a lower effect was found in Granny Smith. Greater total soluble solid content, but not flesh firmness, were also found in fruit from the more sun—exposed parts of canopy, in all cultivars. The skin of fruit from the upper positions in the canopy had greater total phenol content and total antioxidant capacity, in all cultivars, apart from Fyriki. Antioxidant contents in flesh tissue were also greater in the upper positions of canopy in Fuji Kiku 8 and Imperial Double Red Delicious, and to our knowledge this is the first report on plant canopy effects on apple flesh antioxidant compounds.

► The cultivar, fruit position on canopy and harvesting time have a significant role in determining the antioxidant contents in apple fruit. Cultivars Imperial D.R.D. and Fyriki contain relative greater TPh content and AEAC in fruit skin and flesh tissues. The variations among cultivars in the antioxidant contents per serving portion were reduced when calculating the antioxidant contents in unpeeled, compared with peeled, fruit.
► Good light conditions are particularly important for producing apples with healthy compounds in skin and flesh tissue, although there were cultivar depended changes.
► The natural maturation changes in physico-chemical characteristics, during the last weeks before harvest, were combined with changes in the TPh and AEAC in skin and flesh tissue in Granny Smith and Fuji Kiku 8, but not in Fyriki, and these changes were not influenced by the position of fruit on canopy.