Optimization and Component Identification of Ultrasound-Assisted Extraction of Polyphenols from Coriander (Coriandrum sativum L.) and Evaluation of Polyphenol Content Changes and Antioxidant Activity During Storage

Coriander (Coriandrum sativum L.) has significant value in the food industry due to its unique flavor and health benefits. However, its polyphenol content and antioxidant activity have not been systematically analyzed during storage. This study optimized the extraction process of coriander polyphenols using ultrasound-assisted extraction combined with response surface methodology. The polyphenol composition was systematically identified, and changes in polyphenol content and antioxidant activity during storage were investigated. The optimal process conditions for extracting coriander polyphenols were determined as 40% ethanol concentration, 1:121 g/mL material-to-liquid ratio, 81 °C extraction temperature, and 10 min extraction time. This optimized protocol yielded 16.231 mg GAE/g, a 119.28% increase over conventional methods using the same raw material. Fifty polyphenolic compounds were identified using high-resolution mass spectrometry. The main types of polyphenols identified were quercetin, kaempferol, and hydroxycinnamic acid derivatives. Notably, 41 of these compounds were reported in coriander for the first time. In vitro tests revealed that coriander polyphenols exhibit potent antioxidant properties, with IC50 values of 73.43 μg/mL for DPPH and 82.15 μg/mL for ABTS. Furthermore, the polyphenol content and antioxidant capacity of coriander increased significantly during storage, with total phenolic content rising by 40.5%, DPPH activity by 32.5%, and ABTS activity by 56.5%. Key individual polyphenols showed differential changes: rutin continuously accumulated, while chlorogenic acid and ferulic acid exhibited an initial increase followed by a decrease. This study provides strong technical support for the use of coriander polyphenols in functional foods and medicines.