LAUSR

In this study, we investigated impact of single factor: solvent concentration ethanol, solvent pH, ultrasound time, solvent ratio: raw material and ultrasound temperature on the total flavonoid extraction from lotus seeds. Based on survey on factors affecting extraction conditions by the ultrasound bath method, all five surveyed factors were found to have strong influences on total flavonoid extraction process. From factorial design of experimental planning using surface response methodology (RSM), optimal conditions for extraction of total flavonoid from lotus seeds were found in extraction time (98.005 min); solvent concentration ethanol (86.160 %), pH solvent ethanol (4.546), bath ultrasound temperature (22.210°C) and solvent/material ratio (8.376 (v/w)). Under above optimum conditions, total extracted flavonoids was 0.812 (mg Catechin/g extract). Experimental results showed a high compatibility with estimated RSM model. Total flavonoid content obtained in the original liquid extract was 0.797 ± 0.011 (mg Catechin/g extract). The highest antioxidant activity was found to be from ethanol extract with IC50 value (0.058 ± 0.004 (µg/mL), in comparison with IC50 of ascorbic acid, 0.002 ± 0.001 (µg/mL). Moreover, 50 % of DPPH scavenging ability of liquid and condensed extract differed from each other.