Effects of Drying Methods on the Active Components, Antioxidant Properties and Volatile Flavor of Chrysanthemum morifolium

As a traditional medicinal and edible dual-use resource, the drying process of Chrysanthemum morifolium directly affects the retention of active ingredients and product quality. In this paper, the effects of six drying methods, including the steam de-enzyming and hot air drying (50 °C), steam de-enzyming and drying in the shade, steam de-enzyming and freeze-drying, hot air drying, drying in the shade, and freeze-drying, on the color, active ingredients (total phenols, total flavonoids), antioxidant capacity (DPPH, FRAP, ABTS), and volatile flavor of Chrysanthemum morifolium were compared. The results showed that: the combination of E-nose and principal component analysis (PCA) showed that the comprehensive response value of volatile substances in the shade-dried treatment group was significantly higher than that in other groups (P＜0.05), while the volatile components in the steam de-enzyming and hot air-drying group as well as freeze-drying group were significantly lost due to the high temperature or vacuum environment. The total flavonoid content in the shade-dried and frozen-dried treatment groups was the highest (86.46 and 84.37 mg·g⁻¹), which was significantly better than that in the fixing and drying group (46.19 mg·g⁻¹) (P＜0.05). The steam de-enzyming pretreatment significantly reduced the retention rate of flavonoids, with an average loss rate of 26.3%. The antioxidant activity showed a method-dependent manner. The shade-dried and hot air-dried samples showed the best DPPH (213.81 and 212.10 μmol·g⁻¹) and ABTS (84.44 and 82.83 μmol·g⁻¹) free radical scavenging ability, while the FRAP reducing ability was the highest in the hot air-dried group (356.02 μmol·g⁻¹). It was suggested that drying in the shade or freeze-drying should be prioritized for the functional products, while the industrial production could consider the multi-stage hot air drying to balance the quality and efficiency.