title: Adsorption and dilatational rheology of heat-treated soy protein at the oil-water interface: relationship to structural properties.
abstract: We evaluated the influence of heat treatment on interfacial properties (adsorption at the oil-water interface and dilatational rheology of interfacial layers) of soy protein isolate. The related structural properties of protein affecting these interfacial behaviors, including protein unfolding and aggregation, surface hydrophobicity, and the state of sulfhydryl group, were also investigated. The structural and interfacial properties of soy protein depended strongly on heating temperature (90 and 120 °C). Heat treatment at 90 °C induced an increase in surface hydrophobicity due to partial unfolding of protein, accompanied by the formation of aggregates linked by disulfide bond, and lower surface pressure at long-term adsorption and similar dynamic interfacial rheology were observed as compared to native protein. Contrastingly, heat treatment at 120 °C led to a higher surface activity of the protein and rapid development of intermolecular interactions in the adsorbed layer, as evidenced by a faster increase of surface pressure and dilatational modulus. The interfacial behaviors of this heated protein may be mainly associated with more flexible conformation and high free sulfhydryl group, even if some exposed hydrophobic groups are involved in the formation of aggregates. These results would be useful to better understand the structure dependence of protein interfacial behaviors and to expand utilization of heat-treated protein in the formulation and production of emulsions.
authors.affiliation: Department of Food Science and Technology, South China University of Technology, Guangzhou 510640, People's Republic of China.
authors.forename: Jin-Mei
authors.initials: JM
authors.lastname: Wang
authors.forename: Ning
authors.initials: N
authors.lastname: Xia
authors.forename: Xiao-Quan
authors.initials: XQ
authors.lastname: Yang
authors.forename: Shou-Wei
authors.initials: SW
authors.lastname: Yin
authors.forename: Jun-Ru
authors.initials: JR
authors.lastname: Qi
authors.forename: Xiu-Ting
authors.initials: XT
authors.lastname: He
authors.forename: De-Bao
authors.initials: DB
authors.lastname: Yuan
authors.forename: Li-Juan
authors.initials: LJ
authors.lastname: Wang
mesh_terms: D000327:Adsorption; D004548:Elasticity; D004655:Emulsions / Q000737:chemistry*; D006358:Hot Temperature; D057927:Hydrophobic and Hydrophilic Interactions; D009821:Oils / Q000737:chemistry*; D058767:Protein Unfolding; D012212:Rheology; D030262:Soybean Proteins / Q000737:chemistry*; D014783:Viscosity; D014867:Water / Q000737:chemistry*
chemical_list: D004655:Emulsions; D009821:Oils; D030262:Soybean Proteins; D014867:Water