Effects of ultrasound-assisted extraction (UAE), high voltage electric field (HVEF), high pressure processing (HPP), and combined methods (HVEF plus UAE and HPP plus UAE) on Gac leaves extraction

Emerging processing technologies and their combinations might be promising approaches to overcome the limitations of the conventional extraction method (CEM). In this study, ultrasonic-assisted extraction (UAE, 150 W, 20 min), high voltage electric field (HVEF, 4000 kV m(-1) min), and high-pressure processing (HPP, 300 MPa, 3 min) were used in comparison with the CEM to extract Gac leaves (Momordica cochinchinensis Spreng). Besides, two innovative combined methods, i.e., HVU (HVEF+UAE) and HPU (HPP+UAE), were proposed and investigated. Total phenolic content (TPC), total flavonoid content (TFC), total chlorophyll content (TCC), SOD-like capacity, and carbohydrate-hydrolyzing enzyme inhibition of the extracts were measured. Also, polyphenolic compounds were identified by HPLC and the most contributors in the dataset were assessed by principal component analysis (PCA). Gac leaves extract was found to be a source of valuable bioactive compounds with antioxidant activity and hypoglycemic effects that can help with postprandial hyperglycemia management. Vanillic acid and myricetin had the most contributions to alpha-glucosidase and alpha-amylase inhibition ability. Combined emerging technologies (HVU and HPU) were superior to other methods due to the highest values of TPC (5200 mg GAE/100 g DW), TFC (620 mg QE/100 g DW), SOD-like activity (12,100 U/g DW), and inhibitory effects of alpha-glucosidase (38%, IC50 value of 20.5 mg/mL) and alpha-amylase (42%, IC50 value of 16.5 mg/mL).