Physicochemical characteristics and functionality of tree peony (Paeonia suffruticosa Andr.) seed protein

The physicochemical and functional properties of tree peony seed protein were investigated. Tree peony seed protein with a favourable amino acid profile was composed of a 60 kDa protein with two subunits of 38 and 23 kDa. The isoelectric points of the two subunits were 3.6 and 9.0. Moreover, acid-Schiff staining indicated both of them were glycoproteins. Diagonal and 2-D electrophoresis data indicated the 38 kDa subunit included three types, which two types had inter-disulphide bonds and one type had no-disulphide bonds. So did the 23 kDa subunit. Circular dichroism spectra indicated the tree peony seed protein had predominantly a β-sheet structure. Differential scanning calorimetry analysis indicated the denaturation temperatures of the tree peony seed protein at pH 5.0, 7.0 and 9.0 were 92.0, 97.1 and 95.2 °C, respectively. Tree peony seed protein could be a food ingredient in the food industry due to its desirable physicochemical and functional properties.