title: Nonlinear Surface Dilatational Rheology and Foaming Behavior of Protein and Protein Fibrillar Aggregates in the Presence of Natural Surfactant.
abstract: The surface and foaming properties of native soy glycinin (11S) and its heat-induced fibrillar aggregates, in the presence of natural surfactant steviol glycoside (STE), were investigated and compared at pH 7.0 to determine the impact of protein structure modification on protein-surfactant interfacial interactions. The adsorption at, and nonlinear dilatational rheological behavior of, the air-water interface were studied by combining drop shape analysis tensiometry, ellipsometry, and large-amplitude oscillatory dilatational rheology. Lissajous plots of surface pressure versus deformation were used to analyze the surface rheological response in terms of interfacial microstructure. The heat treatment generates a mixture of long fibrils and unconverted peptides. The presence of small peptides in 11S fibril samples resulted in a faster adsorption kinetics than that of native 11S. The addition of STE affected the adsorption of 11S significantly, whereas no apparent effect on the adsorption of the 11S fibril-peptide system was observed. The rheological response of interfaces stabilized by 11S-STE mixtures also differed significantly from the response for 11S fibril-peptide-STE mixtures. For 11S, the STE reduces the degree of strain hardening in extension and increases strain hardening in compression, suggesting the interfacial structure may change from a surface gel to a mixed phase of protein patches and STE domains. The foams generated from the mixtures displayed comparable foam stability to that of pure 11S. For 11S fibril-peptide mixtures STE only significantly affects the response in extension, where the degree of strain softening is decreased compared to the pure fibril-peptide system. The foam stability of the fibril-peptide system was significantly reduced by STE. These findings indicate that fibrillization of globular proteins could be a potential strategy to modify the complex surface and foaming behaviors of protein-surfactant mixtures.
authors.affiliation: Research and Development Center of Food Proteins, Department of Food Science and Technology, South China University of Technology , Guangzhou 510640, People's Republic of China.|Laboratory of Physics and Physical Chemistry of Foods, Wageningen University , Bornse Weilanden 9, 6708WG Wageningen, The Netherlands.
authors.forename: Zhili
authors.initials: Z
authors.lastname: Wan
authors.affiliation: Research and Development Center of Food Proteins, Department of Food Science and Technology, South China University of Technology , Guangzhou 510640, People's Republic of China.
authors.forename: Xiaoquan
authors.initials: X
authors.lastname: Yang
authors.affiliation: Laboratory of Physics and Physical Chemistry of Foods, Wageningen University , Bornse Weilanden 9, 6708WG Wageningen, The Netherlands.|Department of Materials, Polymer Physics, ETH Zürich , Leopold-Ruzicka-Weg 4, 8093 Zurich, Switzerland.
authors.forename: Leonard M C
authors.initials: LM
authors.lastname: Sagis
mesh_terms: D045786:Diterpenes, Kaurane / Q000737:chemistry*; D004548:Elasticity; D005916:Globulins / Q000737:chemistry*; D005960:Glucosides / Q000737:chemistry*; D066329:Protein Aggregates; D012212:Rheology; D030262:Soybean Proteins / Q000737:chemistry*; D013025:Glycine max; D013500:Surface Tension; D013501:Surface-Active Agents / Q000737:chemistry*; D014783:Viscosity
chemical_list: D045786:Diterpenes, Kaurane; D005916:Globulins; D005960:Glucosides; D066329:Protein Aggregates; D030262:Soybean Proteins; D013501:Surface-Active Agents; C012043:stevioside; C011474:glycinin; C025474:rebaudioside A