Characteristics of alkali-extracted peanut polysaccharide-protein complexes and their ability as Pickering emulsifiers.

An alkaline isolation method was applied to extract polysaccharide from residues of peanut oil processing while retaining high protein content, in order to enhance the emulsifying ability of these materials. The obtained complexes (PECs) containing protein (13-18%, dry basis) were named as PEC8.0, PEC10.0 and PEC12.0 according to extraction pH values. The protein content of PECs increased with increasing extraction pH value, thereby the hydrophobicity was improved. Additionally, as extraction pH value increased to 10.0, the protein of PECs covalently bonded to polysaccharide and polysaccharide conformation unfolded simultaneously, thus particle size was enlarged. Furthermore, the increasing concentration of PECs further induced the formation of large complex particles. Then, they were used to stabilize the Pickering emulsions with oil fractions (φ) of 0.4-0.7. The emulsions stability especially the gel structure was maintained by the interactions of large particles adsorbed in the interface and those in the continuous phase. Stability analysis indicated the emulsifying capacity of PEC10.0 and PEC12.0 was superior to that of PEC8.0, due to difference of their particle properties. This suggested the promoting effect of alkali in preparation of polysaccharide-protein complex as good Pickering stabilizer.

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