Effect of heat treatment on the structure and emulsifying properties of peanut protein

In order to improve the emulsifying properties of peanut protein, peanut protein was heattreated at different temperatures (80~120 ℃), and the effects of heat treatment on the structure and emulsifying properties of peanut protein were analyzed. The results showed that the heat treatment at ≥90 ℃ promoted the formation of some high molecular weight aggregates of peanut protein, and the absolute potential decreased significantly (ζ_min=(18.87±0.32)mV). The results of small angle X-ray scattering showed that the natural globular structure of peanut protein was missing after heat treatment at all temperatures; the radius of gyration (R_g) increased (R_{g max}=(5.19±0.01)nm) and the fractal dimension decreased (D_{m min}=1.83±0.09). After heat treatment, the maximum wavelength of fluorescence emission of peanut protein was significantly red-shifted (Δλ_max=10 nm), and the surface hydrophobicity and molecular flexibility were significantly improved, which indicated the unfolding of protein molecular structure. The emulsifying activity of peanut protein was significantly increased only at 100 ℃ and 120 ℃, and the centrifugal stability and salt tolerance stability of peanut protein-stabilized emulsions were significantly increased after heat treatment at all temperatures. Heat treatment improves the emulsifying properties of peanut protein by changing its molecular structure, thus broadening the application range of peanut protein.