Effect of corona discharge cold plasma on the structure and emulsification properties of soybean protein isolate

Abstract

As a non-thermal treatment technology, cold plasma (CP) is widely used in food macromolecule modification, sterilization, etc. However, the effect of different CP source treatments on protein structure has yet to be elucidated. This research studied the effects of corona discharge CP treatment at different voltages and treatment times on the structure, physicochemical properties and emulsion properties of soybean protein isolate (SPI). When the CP was treated at 14 kV for 90 min, the SPI structure was disordered and unfolded, leading to increased surface hydrophobicity and sulfhydryl contents. The solubility of SPI increased by 31.75 ± 1.41%. When the voltage was increased to 18 kV, the content of α-helix and β-sheet structures of SPI increased, indicating the formation of protein aggregates. In this case, the average particle size of SPI increases and the intermolecular electrostatic repulsion decreases. The results show that moderate corona discharge CP treatment can enhance the binding ability of protein particles to oil droplets by unfolding the SPI structure and exposing hydrophobic groups in the hydrophobic core of the protein structure. Simultaneously, the accumulation of negatively charged products on the protein surface hinders the flocculation and coalescence of droplets. Collectively, this study provides a new understanding of the effects of different CP treatments on SPI structure and O/W emulsion properties.