Abstract: A process for extracting procyanidins from lotus seed pods consisting of simultaneous double-enzymatic hydrolysis with pectinase and cellulose and subsequent extraction with 65% aqueous ethanol solution was proposed in this study. Central composite design (CCD) coupled with response surface methodology (RSM) was used to investigate the optimization of the double-enzymatic hydrolysis of lotus seed pods for improved procyanidin extraction. A mathematical predictive model for the extraction yield of procyanidins was established based on the experimental data from CCD design, and analyzed using SAS software. The results showed that the optimal technological conditions for the hydrolysis of lotus seed pods were as follows: hydrolysis temperature, 53 ℃; hydrolysis time, 1.6 h; initial hydrolysis pH, 4.8; and the ratio of pectinase to cellulose, 1: 1.1, and the yield of procyanidins was 5.20% after hydrolysis under these conditions followed by 120 min extraction at 55 ℃with 65% aqueous ethanol solution, 35.7% higher than that of single ethanol extraction. In addition, procyanidins extracted by the method had stronger ability to scavenge DPPH radicals than those derived from single ethanol extraction.

Key words: lotus seed pod, procyanidins, enzymatic hydrolysis, extraction rate, central composite design, response surface methodology