Abstract: The chemical components of edible sweet-scented osmanthus flowers (Osmanthus fragrans (Thunb.) Lour.) vary at different heat treatment temperatures, so it is extremely necessary to explore the effect of different heating temperatures on the eating quality of sweet-scented osmanthus. In this work, changes in the bioactive ingredients, antioxidant property, color and flavor substances of unheated (control) and heated (at 80, 100 or 120 °C for 20 min) flowers of Osmanthus fragrans ‘Boyejingui’, ‘Echengdangui’ and ‘Wanyingui’ were determined. The results showed that with an increase in heating temperature, the content of bioactive ingredients decreased significantly (P < 0.05), and the loss rates of flavonoids, polyphenols and anthocyanins were up to 37.44%, 28.74% and 49.10%, respectively. The antioxidant capacity decreased initially and then increased, and the radical scavenging capacity of the sample heated at 120 ℃ increased by 6.52% compared with that of the sample heated at 100 ℃. The color difference significantly increased (P < 0.05), the bitterness increased, and the astringency decreased first and then increased. Compared with the control group, furans, nitrogen-containing heterocycles and phenols were exclusively found in the sample heated at 120 ℃ at a level of 6.21%. The number of species of characteristic aroma components progressively decreased but a caramel-like aroma was formed. Therefore, medium and low temperature processing is suitable for the production of sweet-scented osmanthus products with health benefits, and high-temperature processing is suitable for the production of sweet-scented osmanthus-based snacks. ‘Boyejingui’ is suitable for low temperature processing, ‘Echengdangui’ is suitable for high temperature processing, and the quality of ‘Wanyingui’ is poor after heat treatment. Processing temperature and varieties should be reasonably selected according to practical demands. This study can provide a theoretical basis for the development of thermally processed products of sweet-scented osmanthus.

Key words: Osmanthus fragrans varieties; heating temperature; active ingredients; antioxidant property; color; flavor