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Protein from peony seed meal was extracted by alkali dissolution and acid precipitation. The extraction process was optimized by single factor and orthogonal experiments, and the physical and chemical properties and functional properties including isoelectric point, molecular weight, secondary structure, foaming property and foaming stability of the protein were determined. The results showed that the influencing factors on protein yield were: pH>extraction time>extraction temperature>solid-liquid ratio. The optimal extraction conditions were under the optimum conditions of material liquid ratio 1:20 g/mL, extraction temperature 70 ℃, pH9 and extraction time 45 min, the yield of protein from peony seed meal was 79.83%±1.22%. SDS-PAGE showed that there were five kinds of protein with molecular weight, two of which were between 15~25 kDa, two of which were between 35~40 kDa, and one of which was between 55~70 kDa. Fourier infrared spectroscopy showed that the protein in peony seed meal was mainly α-helix and β-folding, containing intermolecular hydrogen bonds and a small amount of carbohydrate. The scanning electron microscope showed that the protein in peony seed meal was mainly composed of β-folding composition. Compared with soybean protein, peanut protein and pea protein, peony seed meal protein had a good oil holding capacity of 4.5 g/g, which was similar to soybean protein in foaming and emulsification. This study can provide a reference for the application of peony seed meal protein in the food industry.

In this study, the flavonoids in peony seed meal were separated and purified by microfiltration-nanofiltration secondary membrane separation method. The effects of material-liquid ratio, extraction temperature, ethanol volume fraction and extraction time on the extraction amount of total flavonoids were investigated by single-factor experiments, and the extraction process was optimized and validated by response surface methodology on the basis of single factors. Eight types of microfiltration membranes, including polyvinylidene fluoride (PVDF), polyethersulfone (PES), polytetrafluoroethylene (PTFE), polypropylene (PP), mixed cellulose (MCE), polyacrylonitrile (PAN), aqueous acetate (CA) and polyamide (PA), were selected for the primary separation of PSMF extracts. The nanofiltration membranes were homemade organosilicon/PA composite membranes in the laboratory. The results showed that the optimum extraction conditions for PSMF were 1:15 g/mL, 50 ℃, 70% ethanol volume fraction, 30 min, (240.28±2.25) μg/mL of PSMF extraction amount. The PA membrane had a better separation effect, and the composite membrane had a better purification effect on PSMF, and the water solubility of flavonoids was increased to more than 90% after separation. After calcination at 800 ℃, the residual mass of the raw material solution was 1.43% and that of the PA membrane separation was 0.76%, and the BTESE/PA composite membrane was reduced to 0.26%, with fewer impurities and higher purity. Comparing its antioxidant activity before and after separation, the ·OH, DPPH· scavenging rate and reducing power were improved after separation, and the O2−· scavenging rate decreased from 79.94% to 64.82%. In this study, the active components in peony seed meal were analyzed. PSMF would be a novel phytoflavonoid resource with rich composition and certain research space.

In this study, an alkali solution and acid precipitation method were used to extract protein from peony seed meal. Solid-liquid ratio, pH, time, and temperature were selected to carry out a single-factor study and combined with the response surface method to optimize the optimal extraction process. The optimum process conditions were determined: The protein yield reached 23.81%±0.04% when the ratio of solid to liquid was 1:25 g/mL, pH10.6, the temperature was 55 ℃, and time was 130 min. The peony seed meal protein obtained under these conditions contained 18 kinds of amino acids. The water and oil retention of peony seed meal protein was 3.72 g/g and 3.67 g/g, respectively. Foamability and foam stability decreased significantly at pH2~4, and the lowest was at pH4. Between pH6 and 10, foamability continued to increase, while foam stability increased significantly and then decreased slightly. With the increase in pH, the emulsification and emulsification stability increased. The results were consistent with the variation trend of particle size and Zeta potential. This study provided a theoretical basis for the industrial production and comprehensive utilization of peony seed meal protein.