Effects of drying temperature on the drying characteristics and volatile profiles of Citrus reticulata Blanco peels under two stages of maturity

Abstract

Citrus peels are considered as an agricultural waste with negative environmental impacts. In the present study, yellow (ripe) and green (unripe) Citrus reticulata peels were dried in a hot air impingement dryer and the effect of drying temperatures (40, 50, 60, and 70 °C) on the drying characteristics, volatile compounds, and antioxidant capacity were explored. The results showed that the drying time of samples was reduced by more than 50% when the drying temperature was increased from 40 to 70 °C. A total of 56 peaks and 29 volatile components were identified by headspace-gas chromatography-ion mobility spectrometry. Drying caused an obvious reduction in the concentration of linalool oxide, benzaldehyde, (E)-2-heptenal, and 1-pentanol, and an increment in the concentration of pentanal, decanal, linalool, and (E)-2-hexenol. Principal component analysis showed that samples under different treatments were clearly distinguished. Drying resulted in a significant reduction of 2,2‐diphenyl‐1‐picrylhydrazyl and ferric reducing antioxidant power. These findings will contribute to a better understanding of citrus peel drying as well as their volatile profiles and antioxidant capacity changes during drying.