Effect of salts combined with high hydrostatic pressure on structure and gelation properties of sweet potato protein

The effects of monovalent (NaCl) and divalent (CaCl2 and MgCl2) salts combined with high hydrostatic pressure (HHP) on structure and gelation properties of sweet potato protein (SPP) were investigated. Surface hydrophobicity and zeta potential of SPP significantly decreased as salts concentration increased. The total amount of sulfhydryl (-SH-) groups in SPP decreased with addition of NaCl, CaCl2 and MgCl2 under HHP, whereas the disulfide bonds (-S-S-) increased from 0.59 to 0.80 and 0.74 μmol/g with addition of 0.1 and 0.2 moL/L of CaCl2 combined with HHP, respectively. The α-helical content of SPP was increased by all three salts, but decreased as salts combined with HHP, while β-sheet content was increased at high ionic strength with HHP, especially in presence of CaCl2 and MgCl2, being increased from 30.40 to 33.45 and 33.55 g/100 g, respectively. The storage modulus (G′) of SPP was enhanced by salts and HHP, even though it decreased at high ionic strength. Textural properties and water holding capacity of SPP gels were improved with salt ions by HHP, being attributed to more bound water.