Evolution of wheat gliadins conformation during film formation: a fourier transform infrared study.
The secondary structures of wheat gliadins (a major storage protein fraction from gluten) in film-forming solutions and their evolution during film formation were investigated by Fourier transform infrared spectroscopy. In the film-forming solution, wheat gliadins presented a mixture of different secondary structures, with an important contribution of beta-turns induced by proline residues. The presence of plasticizer did not have any influence on protein secondary structure in the film-forming solution. The evolution of protein conformation was followed during drying; the major feature of this evolution was a clear growing of the infrared band at 1622 cm(-1), characteristic of intermolecular hydrogen-bonded beta-sheets. This revealed the formation of protein aggregates during film drying. The influence of the drying temperature on film properties and gliadin secondary structures was also investigated. Higher drying temperatures induced an increase of both the tensile strength of the films and the amount of beta-sheets aggregates. Although the appearance of heat-induced disulfide bridge cross-links has already been described, there is clear evidence that hydrogen-bonded beta-sheets aggregates are also induced by thermal treatment. It was not possible, however, to determine whether there is a direct relationship between the occurrence of these aggregates and the increase of the tensile strength of the films.
Institut National de la Recherche Agronomique, Unité de Biochimie et Technologie des Protéines, Rue de la Géraudière, BP 71627, 44316 Nantes Cedex 03, France. mangavel@nantes.inra.fr
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Mangavel
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Barbot
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Popineau
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Guéguen
D005903:Gliadin / Q000737:chemistry*; D010968:Plasticizers; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D014908:Triticum
D010968:Plasticizers; D005903:Gliadin