Effects of drying methods on phytochemical compounds and antioxidant activity of physiologically dropped un-matured citrus fruits

• Freeze-drying is good for retaining phenolic compounds, synephrine.
• Freeze-drying is good for retaining antioxidant activity.
• Hot air-drying is good for retaining flavonoids.
• All three methods can be used for retaining limonoids.

Physiologically dropped un-matured citrus fruits have good potential as sources of different bioactive compounds and antioxidants. Drying is a good method to preserve the materials. The effects of three different drying methods (sun-drying, hot air-drying and freeze-drying) on phytochemical compounds and antioxidant activity of physiologically dropped un-matured citrus fruits were investigated. The results showed freeze-drying is good for retaining phenolic compounds, synephrine and antioxidants; hot air-drying is good for retaining flavonoids; and all three methods can be used for retaining limonoids. The results should serve as a guide for the industrial production of high-quality extraction materials for bioactive compounds.