Abstract:Low-field nuclear magnetic resonance (LF-NMR) was used to determine water distribution in soybean protein concentrate powder treated by different doses of electron beam irradiation (EBI). Additionally, a thermal denaturation experiment and Fourier transform infrared (FT-IR) spectroscopy were used to explore the effect of EBI on changes in water components of soybean protein concentrate powder and to determine its mechanism. The results showed that bound water (T21, 97.0%±0.7%) was the main water component of soybean protein concentrate powder. Both bound and total water contents initially increased and then decreased with increasing dose of EBI, with the maximum content reached at 5.40 kGy. The thermal denaturation experiment and FTIR spectra showed that the EBI treatment did not alter the denaturation temperature of soybean protein concentrate powder; however, it enhanced the vibration of intramolecular and intermolecular hydrogen bonds, which were formed by O-H and C=O groups in bound water and amino acids, respectively. These results suggested that the EBI treatment affected the water distribution and content of soy protein by altering the intramolecular and intermolecular hydrogen bond interactions in soybean protein molecules. The study provides a theoretical basis for further studies on the mechanism of moisture transfer in protein foods treated by EBI.
