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Wheat Gluten Polymer Structures: The Impact of Genotype, Environment, and Processing on Their Functionality in Various Applications

¹Department of Agrosystems, The Swedish University of Agricultural Sciences, Box 104, SE-23053 Alnarp, Sweden. ²Corresponding author. E-mail: eva.johansson@slu.se ³Present address: Department of Plant Breeding, The Swedish University of Agricultural Sciences, Box 101, SE-23053 Alnarp, Sweden. ⁴Present address: Syngenta Seeds AB, Box 302, 26123 Landskrona, Sweden. ⁵Present address: Department of Biosciences, COMSATS Institute of Information Technology, Sahiwal Campus, COMSATS Road, P. Code 57000 Sahiwal, Pakistan. ⁶MAX-lab, Lund University, SE-221 00 Lund, Sweden. ⁷Department of Fibre and Polymer Technology, KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden. ⁸Innventia, Box 5604, SE-11486 Stockholm, Sweden.

For a number of applications, gluten protein polymer structures are of the highest importance in determining end-use properties. The present article focuses on gluten protein structures in the wheat grain, genotype- and environment-related changes, protein structures in various applications, and their impact on quality. Protein structures in mature wheat grain or flour are strongly related to end-use properties, although influenced by genetic and environment interactions. Nitrogen availability during wheat development and genetically determined plant development rhythm are the most important parameters determining the gluten protein polymer structure, although temperature during plant development interacts with the impact of the mentioned parameters. Glutenin subunits are the main proteins incorporated in the gluten protein polymer in extracted wheat flour. During dough mixing, gliadins are also incorporated through disulfide-sulfhydryl exchange reactions. Gluten protein polymer size and complexity in the mature grain and changes during dough formation are important for breadmaking quality. When using the gluten proteins to produce plastics, additional proteins are incorporated in the polymer through disulfide-sulfhydryl exchange, sulfhydryl oxidation, β-eliminations with lanthionine formation, and isopeptide formation. In promising materials, the protein polymer structure is changed toward β-sheet structures of both intermolecular and extended type and a hexagonal close-packed structure is found. Increased understanding of gluten protein polymer structures is extremely important to improve functionality and end-use quality of wheat- and gluten-based products.