Flavonoids from Peony Seed Meal by Nanofiltration Membrane Separation

Flavonoids are polyphenolic compounds with a wide range of biological activities (antioxidation, antitumor, and immunomodulatory). The membrane separation method of flavonoids has a high recovery and biological activity, overcoming the shortcomings of traditional methods for the separation of bioactive molecules. In this study, ethanol-water ( $v/v$ ) solution was used to extract peony seed meal. The extraction rate of total flavonoids from peony seed meal was 35.28%. Five microfiltration membranes, polypropylene (PP), polyvinylidene fluoride (PVDF), cellulose acetate (CA), polyether sulfone (PES), and polyamide (PA), were selected to pretreat the extracts, and their separation performance was investigated. A new PA-supported silicone film was prepared by sol-gel method using 1,2-bis(TRIMETHOXYSILYL)ETHANE (BTESE) as a carrier. The synthesized BTESE/PA composite membrane was applied to the purification of organic silica PSMF solution by nanofiltration process. The optimal pressure of nanofiltration operation is 0.8 MPa, and the membrane flux can reach 2.06 kg·m-2·h-1. The mass concentration of flavonoids in the retention solution was decreased to 860.56 mg·L-1, and the permeable components of PSMF were effectively separated. The total flavonoid content of the purified lyophilized powder was 146.12 mg·g-1, which was 2.4 times that before purification. The results show that PSMF can be effectively separated by BTESE/PA membrane, and the membrane solution has good antioxidant activity.