Mechanical and Biochemical Characterisation of Wheat Gluten Films as a Function of pH and Co-solvent

• Published in: Die Stärke Vol. 53; no. 8; pp. 381 - 386
• Main Authors: Kayserilioğlu, Betül Ş., Stevels, Wim M., Mulder, Wim J., Akkaş, Nuri
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag GmbH 01-08-2001; WILEY‐VCH Verlag GmbH; Wiley-VCH
• Subjects: Agrotechnological Research Institute; Applied sciences; Biological and medical sciences; Exact sciences and technology; Food industries; Forms of application and semi-finished materials; Fundamental and applied biological sciences. Psychology; General aspects; Handling, storage, packaging, transport; Instituut voor Agrotechnologisch Onderzoek; Lysinoalanine; Polymer industry, paints, wood; Sheets and films; Technology of polymers; Wheat gluten film; Characterization; Lysinoalanine; Cosolvent; Ethanol; Film; Plant protein; Mechanical properties; pH; Cereal; Wheat; Gluten; Physicochemical properties
• ISSN: 0038-9056; 1521-379X
• DOI: 10.1002/1521-379X(200108)53:8<381::AID-STAR381>3.0.CO;2-F

Dispersions of wheat gluten were prepared at different pHs (4, 6 and 11) in the presence or absence of ethanol. Films were obtained after casting suspensions followed by evaporation of the solvent. Films prepared at pH 11 were significantly stronger than the films prepared at pH 4 and 6 with tensile strengths of approximately 7 vs. 2 MPa. With increasing strength, the elongation at break was moderately reduced from approximately 300% to 190%. No significant variations of water vapour transfer rate properties were observed among the films. The solubility of gluten films in aqueous and 1.5% sodium dodecyl sulfate (SDS) solution decreased with increasing pH of films. Tricine sodium dodecyl sulfate‐polyacrylamide gel (SDS‐PAGE) patterns of wheat gluten and film showed the formation of high molecular weight fractions. The amount of free amino groups in the wheat gluten decreased during film formation. Amino acid analysis showed the presence of lysinoalanine (LAL). All these results indicate the formation of irreversible intermolecular cross‐linking upon film formation at pH 11.