Properties and microstructure of thermo-pressed wheat gluten films: a comparison with cast films.
Wheat gluten films were prepared by thermo-pressing, and their mechanical properties were compared to those of cast films. The stress-strain relationship was established for films with various amounts of glycerol. Both relationships were quite different, revealing a different network organization. Thermo-pressed films presented higher stress values than cast films, but the effect of the glycerol amount was similar in both cases, an increase of the glycerol amount leading to a decrease of both films stress. The glycerol influence on the strain at break of thermo-pressed films was very limited, with strain values reaching a maximum around 200%. The role of disulfide bridges on themomoulded films mechanical properties was investigated, and it was shown that some rearrangements and a significative protein insolubilization occurred during the process. The effective flow porosity of the protein network for thermo-pressed films was estimated by water capillary rise measurements to about 7%. Scanning electron microscopy was used to obtain some information about the microstructure of both cast and thermo-pressed films.
Mangavel
C
C
Institut National de la Recherche Agronomique, Unité de Recherche sur les Protéines Végétales et leurs Interactions, Rue de la Géraudière, BP 71627, 44316 Nantes Cedex 03, France. mangavel@nantes.inra.fr
Rossignol
N
N
Perronnet
A
A
Barbot
J
J
Popineau
Y
Y
Guéguen
J
J
D004220:Disulfides / Q000737:chemistry; D005983:Glutens / Q000737:chemistry* / Q000648:ultrastructure*; D008567:Membranes, Artificial; D010316:Particle Size; D011108:Polymers / Q000737:chemistry; D013696:Temperature; D013997:Time Factors; D014908:Triticum / Q000737:chemistry*
D004220:Disulfides; D008567:Membranes, Artificial; D011108:Polymers; D005983:Glutens