Effects of electron beam irradiation (EBI) on structure characteristics and thermal properties of walnut protein flour

•The EBI could lead to puncture pores on microcosmic surface of protein by SEM.•The EBI increased denaturation temperature of protein by LF-NMR.•The EBI increased the particle size of protein hydrolysates.•The EBI enhanced thermal stability of protein by TG analysis.

The effects of electron beam irradiation (EBI) on structure characteristics and thermal properties of walnut protein flour (WPF) were evaluated. The WPF was irradiated by 0-15.0 kGy of the EBI. Scanning electron microscopy and X-ray diffraction analysis revealed that the EBI irradiation could not change the amorphous structure of WPF but resulted in puncture pores and fragmentation on microcosmic surface of WPF. Besides, low-field nuclear magnetic resonance results showed the EBI irradiation had effects on increasing denaturation temperature of WPF to 70 °C, and the particle size of WPF hydrolysates (WPFHs) irradiated by EBI at dose of 5.0 kGy significantly (P < 0.05) increased to 753.8 ± 21.0 nm. The molecular weight of WPFHs at dose of 5.0 kGy increased compared with that of non-irradiated sample. These revealed that EBI irradiation led to aggregation or cross-linking of the walnut protein. In addition, thermogravimetric analysis and zeta potential values indicated that the EBI enhanced thermal stability of WPF and didn't affect the physical stability of the WPFHs. Therefore, these results provided a theoretical foundation that the EBI applies on improving the properties of protein in the future.

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