Abstract:Lotus seed processing by-product-lotus seed epicarp residue was collected as experimental materials. Based on the results of single factor experiment, response surface methodology (RSM) was used to optimize the ultrasonic-assisted extraction of bioactive compounds from lotus seed epicarp residue, and total phenolic content (TPC), total proanthocyanidin content and DPPH·+ scavenging capacity were set as response values. Experimental data were fitted to three quadratic polynomial models and the regression equations were significant with good fitting degree. The optimal extraction conditions were as follows: Acetone concentration of 70%, liquid to solid ratio of 1:25.5 g/ mL, extraction temperature as 50 ℃ and sonication time as1.6 hour. Under these conditions, the practical values of responses were 194.54±3.63 mg GAE/g DW, 243.15±2.88 mg CE/g DW, 238.53±3.07 mg AAE/g DW, respectively, which were consistent with the predicted values. So the established models could accurately predict the results of total phenolic content, total proanthocyanidin content and DPPH·+ scavenging capacity in lotus seed epicarp residue. We determined the phytochemical content and in vitro antioxidant activities of diverse lotus seed epicarp residue and found that they are rich in bioactive compounds including polyphenols, flavonoids, proanthocyanidins, triterpenes, and with high antioxidant activity. The study suggested that lotus seed epicarp residue contains high amount of bioactive chemicals and is of great potential for research and development.
