Effects of reducing agents and NaCl synergistic alkaline pH shift treatment on the emulsifying properties of peanut protein

To improve the emulsifying properties of peanut protein, different reducing agents (GSH, Cys, TCEP, Na₂SO₃) and NaCl were introduced during the alkaline pH shift treatment process, and the effects of multi-factor synergistic treatment on the emulsifying properties of peanut protein and its components were systematically investigated. The results showed that under pH 12 shift conditions, the simultaneous addition of 0.05% Na₂SO₃ and 62.5 mmol/L NaCl achieved the best modifying effect on peanut protein and its components. Compared with the sample only treated with 0.05% Na₂SO₃, the emulsifying activity index (EAI) and emulsifying stability index (ESI) of peanut protein increased by 18.5% and 137.1%, respectively, and significantly enhancing the storage stability and freeze-thaw stability of the emulsion. Unlike arachin, the emulsifying property of conarachin significantly decreased during pH shift treatment alone, indicating that under the same treatment conditions, there were differences in the response behavior of arachin and conarachin. The rheological results of interfacial dilatational rheology showed that the interfacial pressure increased and the viscoelasticity of the interfacial film was enhanced after the combined modification of the two peanut protein components. The improvement in the stability of arachin emulsion after combined modification was not only attributed to the increase in interfacial film strength but also possibly related to the formation of a weak gel structure in the system. Alkaline pH shift combined with reducing agents and NaCl treatment can effectively improve the emulsifying properties of peanut protein, expanding its potential applications in the food industry.