Abstract: This study aimed to clarity the drying characteristics of ‘Xiushui Huahong’ sweet orange peel and determine a suitable drying temperature for its quality control during hot air drying. A kinetic model to describe the relationship between moisture ratio and drying time at different hot air temperatures (50, 60, 70, 80 and 90 ℃). Meanwhile, the effect of different drying temperatures on the dried product quality in terms of appearance, antioxidant capacity and the contents of flavonoids and contents of volatile flavor compounds was evaluated. The drying process involved three stages, acceleration, maintenance and deceleration. The drying rate distinctly increased as the drying temperature increased, and the data fitting result showed that the Page model could accurately describe the drying process at different hot air temperatures. Sweet orange peel dried at 50 ℃ maintained the original color and shape to the greatest extent. The contents of total flavonoids and hesperidin were the highest in the sample dried at 60 ℃, while the product dried at 90 ℃ showed stronger antioxidant capacity. Moreover, 24 volatile flavor compounds were detected in the five dried samples, 11 of which were found in each of the samples dried at 50, 60 and 70 ℃, 15 for 80 ℃, and 19 for 90 ℃. D-limonene was the most abundant volatile flavor compound in all five samples. These samples differed in their quality. Hence, drying temperature should be chosen according to actual requirements, and drying at 60 and 90 ℃ are suitable for higher contents of flavonoids and volatile flavor compounds, respectively.

Key words: ‘Xiushui Huahong’ sweet orange peel, hot air drying, drying kinetics, flavonoids, antioxidant capacity, volatile flavor compounds