title: Gluten gel and film properties in the presence of cysteine and sodium alginate.
abstract: Wheat flour has an ability of forming dough by mixing with water, which exhibits a rheological property required for making bread. The major protein is gluten, which is a valuable protein material for food industry. In this study, gluten protein gels and films were formed with cysteine and sodium alginate. Adding cysteine improved gel and film properties (stress relaxation behavior, bending strength). The gel containing 0.01 M cysteine had a longer relaxation time and was more rigid than the gel without cysteine. Although adding sodium alginate to the gluten suspension containing cysteine improved the water-holding ability and homogeneity of the gel network, the film from this gel was more brittle than the gluten film with cysteine alone. Microstructural observations of the gels and films with scanning electron microscopy suggested that water evaporation was more heterogeneous from the gel containing sodium alginate than from the gel with cysteine alone. Fourier transform-infrared (FT-IR) analysis during film formation suggested that the presence of cysteine encourages interaction between gluten molecules and results in intermolecular beta-sheet formation in earlier stages than in the no additive condition. FT-IR results also suggested that the combined effect of sodium alginate and cysteine on the protein secondary structure was remarkably different from that of cysteine alone. Our results suggest that addition of a suitable amount of cysteine (0.01 M) and heat treatment to 80 degrees C during gluten gel and film formation induces a homogenous network in the gel and film by regulating disulfide-sulfide interactions.
authors.affiliation: Junior College at Mishima, Nihon Univ., Mishima City, Shizuoka, 411-8555 Japan. naokoohta@bitcat.net
authors.forename: Naoko
authors.initials: N
authors.lastname: Yuno-Ohta
authors.forename: Mariko
authors.initials: M
authors.lastname: Yamada
authors.forename: Masako
authors.initials: M
authors.lastname: Inomata
authors.forename: Hiromi
authors.initials: H
authors.lastname: Konagai
authors.forename: Tomomi
authors.initials: T
authors.lastname: Kataoka
mesh_terms: D000464:Alginates / Q000737:chemistry*; D003545:Cysteine / Q000737:chemistry*; D004548:Elasticity; D005524:Food Technology / Q000379:methods; D005782:Gels / Q000138:chemical synthesis / Q000737:chemistry*; D020723:Glucuronic Acid / Q000737:chemistry; D005983:Glutens / Q000737:chemistry* / Q000648:ultrastructure; D006603:Hexuronic Acids / Q000737:chemistry; D006358:Hot Temperature; D008567:Membranes, Artificial; D008855:Microscopy, Electron, Scanning; D018583:Pliability; D017433:Protein Structure, Secondary; D012212:Rheology; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D014783:Viscosity
chemical_list: D000464:Alginates; D005782:Gels; D006603:Hexuronic Acids; D008567:Membranes, Artificial; D005983:Glutens; D020723:Glucuronic Acid; D003545:Cysteine