Effect of size and canopy position on physicochemical properties, carbohydrate, and bioactive compounds of Thomson Navel orange (Citrus sinensis cv. Thomson Navel)

Abstract

Citrus fruits contain numerous beneficial bioactive compounds including vitamin C, phenolic compounds, flavonoids, carotenoids, and sugars which have high nutritional and antioxidant value. Some factors such as the canopy position of the fruit and fruit size affect the quality and quantity of these compounds. The aim of this study was to investigate the effect of canopy position and fruit size on morphophysiological and biochemical properties of Thomson orange fruit. In the first experiment, fruits with medium and uniform size were harvested from inside and outside canopy positions of the tree. In the second experiment, after harvest the fruits were grouped into three sizes of small, medium, and large. Traits such as weight, volume, length, and width of fruit, skin color, skin thickness, extract content, dry matter percentage, TA, TSS, TSS/TA, total chlorophyll and total carotenoids, antioxidant capacity, phenolic acid content, vitamin C, total sugars, and reducing sugars were evaluated on the peel and pulp of fruit along with a panel test. Results revealed that fruit volume, peel thickness, TSS/TA, a* value, CCI value, peel antioxidant capacity, and peel total sugars were higher in the fruits from the external canopy position while TA, L*, C*, h°, and b* in the fruits from internal canopies were significantly higher. Fruit size had a significant effect on physical parameters of fruit, CCI, h°, juice, and dry matter while it did not affect the quality and chemical traits of fruit. The results of this study showed that orange fruit with a position outside the crown and a large size has a significant increase in extract content, actual volume, average fruit diameter, aroma, taste, and sweetness compared to the position inside the crown with a small size.

Keywords

• antioxidant capacity
• canopy position
• carbohydrate
• orange
• rind pigment