Chemical Forces, Structure, and Gelation Properties of Sweet Potato Protein as Affected by pH and High Hydrostatic Pressure
Sweet potato is one of cheap sources for starch industries worldwide, and exploiting starch wastewater as an alternative protein source is mainly environmental and economic concerns. In this study, the effects of high hydrostatic pressure (HHP; 250, 400, and 550 MPa) on chemical forces, structure, and gelation properties of sweet potato protein (SPP) at pH 3.0, 6.0, and 9.0 were investigated. The values of surface hydrophobicity (Ho) and absolute value of zeta potential of SPP significantly increased from 250 to 550 MPa (p 0.05) at all three pH conditions. The total amount of sulfhydryl SH groups in SPP decreased after HHP at pH 9.0, whereas the amount of free SH increased. High molecular mass aggregates 180 kDa) were observed in SPP after HHP at pH 6.0 and 9.0 by SDS PAGE. Regarding elastic rheological behaviors, storage modulus (G' values of SPP were significantly strengthened after HHP treatment. In addition, textural properties and water holding capacity of gels made from SPP after 250 and 400 MPa at pH 9.0 were significantly improved, and the gels showed a compact and uniform gel network with the contribution of immobilized water fractions. The gel properties exhibited by SPP after HHP treatment at different pH levels, in particular after 400 MPa at pH 9.0, suggested that it could be potential protein resources as new gelling reagent in the food system.
Food and Bioprocess Technology