Effect of hot air drying process on color and antioxidant attributes of the flavedo of bitter orange (Citrus aurantium L.)

This research investigated the effects of different drying temperatures (40, 50, and 60°C) on changes in color, total phenolic, total flavonoid, ascorbic acid, and antioxidant activity of bitter orange flavedo. In comparison to the fresh sample, the L* and a* values increased, while b* and h° values decreased at all air drying temperatures. The lowest total color change (TCC) values were achieved at drying temperatures of 40 and 60°C. Drying temperatures induced an increment in total phenolic and antioxidant activity, the highest total phenolic content (16.35±0.54 mg GAE g-1) and DPPH radical scavenging activity (IC50: 14.61±0.53 mg mg-1) were determined in flavedo dried at 40°C, and the highest FRAP value (52.19±1.49 mmol TE g-1) was achieved in flavedo dried at 50°C. However, the applied drying temperatures resulted in a decline in the flavedo's total flavonoid content (52.79–64.75%) and ascorbic acid content (36.63–45.54%). Based on the results obtained from this work, bitter orange flavedos can be dried at lower temperatures (40-50°C) to minimize color changes and enhance phenolic and antioxidative activity.