Optimization of Extraction Process and Properties of Protein from Peony Seed Meal

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.