Structure Changes of Soybean Protein Isolates by Pulsed Electric Fields

Effects of pulsed electric sfields (PEF) on the structure of soybean protein isolates (SPI) were studied by Raman spectra (RS). The secondary structure of SPI mainly consisted of α-helix and β-sheet. The changes of Raman characteristic peaks of amide I and amide III indicated that PEF induced the content of β-sheet and random coil to increase. The decrease of peak 921cm-1 showed the lower of α-helix content. The changes of S-S and C-C vibrational peaks indicated that PEF influenced the sulfhydryls and disulfide bonds. PEF influenced hydrophobicity by changes in tyrosine vibration frequency of RP and caused more hydrophobic groups and regions inside the molecules to expose outside. Too strong PEF conditions made hydrophobic groups interactions form and bury inside again.