NMR and FTIR studies of hydrated pea proteins

The effects of increasing D₂O hydration on the plasticization of vicilin, legumin and albumin fractions from peas were investigated using solid state ¹H-NMR transverse relaxation techniques. Measurements showed increases on hydration in the T₂ and intensity of the exponential component of the relaxation decay. However, a Gaussian (more rigid) component remained throughout the sample composition range. This behaviour contrasted with that observed in barley storage proteins and would indicate considerably less plasticization in legume proteins. In ²H-NMR transverse relaxation measurements of a highly D₂O hydrated sample over a large temperature range, vicilin was shown to be hydrophilic in nature. However, the observed absorption of water by vicilin was less than in the HMW subunits of wheat. FTIR spectra show little structural change in vicilin and legumin on hydration, in contrast to changes occurring in the cereal proteins. These differences in behaviour may be ascribed to differences between the globular structure of the legume proteins and the more linear structure of the cereal proteins.