| Abstract
| - Films were prepared at neutral pH from deamidated gluten by casting with or without enzymatictreatment by transglutaminase in the presence of various concentrations of diamines added to thefilm-forming solution. Variation in the glycerol/deamidated gluten ratio from 0.2 to 0.5 had a majoreffect on the film mechanical properties, which is characteristic of a plasticizing effect. A ratio of0.35, producing a tensile strength of 1.14 ± 0.12 MPa and an elongation at break of 376 ± 62%, waschosen for most of the enzymatic modifications. The action of transglutaminase with or without theaddition of external diamines induced a simultaneous increase in tensile strength and elongationat break of the films but tended to decrease the contact angle between the film surface and a waterdroplet. The presence of diamines in the film solution affected the elongation at break more thanthe tensile strength of the films. These diamines, able to react at their two extremities, probablyacted as spacers between gluten proteins. The decrease in solubility was related to the formation ofhigh molecular weight polymers in the film. The film properties were unaffected by the type ofdiamine added as secondary substrate in the transglutaminase reaction. Keywords: Wheat; gluten; deamidation; transglutaminase; protein films; mechanical properties
|
