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Les modifications chimiques des protéines alimentaires sont réalisées dans le but d’ améliorer leurs propriétés fonctionnelles. Elles sont également pratiquées pour des études fondamentales des relations structure/fonction des protéines. Les principales modifications chimiques des protéines alimentaires sont présentées ainsi que leurs incidences sur les propriétés fonctionnelles telles les propriétés émulsifiantes, moussantes, visqueuses, d’hydratation et de gélification.

The antimicrobial potential of CO 2 applied under 5 MPa pressure during heat treatment was investigated against Bacillus subtilis spores, Byssochlamys fulva ascospores and Aspergillus niger conidia. The rates of thermal inactivation were increased in the presence of pressurized CO 2 when treatment was carried out at a temperature higher than a threshold value depending on the tested microorganism (80 °C for B. subtilis and B. fulva , 50 °C for A. niger ). The antimicrobial effectiveness of CO 2 varied with the microorganisms, the temperature and the a w of the suspension medium. However, the increase in the destruction rate was relatively more extensive when the temperature was sublethal or low lethal. At elevated lethal temperatures, the antimicrobial effect of pressurized CO 2 disappeared. Moreover, a low a w antagonized the lethal effect of CO 2 under pressure.

Fish myofibrillar protein-based films formulated with saccharose as a plasticizing agent were stored for several weeks under regulated temperatures and relative humidities. Solubility in water, water vapour permeability and mechanical properties remained constant for 8 weeks at 20°C and 58.7% relative humidity. A slight yellow colour was the only modification observed. This colour modification, which could be associated with nonenzymatic browning reactions, was characterized as a function of time, temperature, relative humidity and plasticizer type. A regression model correlating the pertinent parameters was defined.

Summary Various formulations and methods of fabricating edible bilayer films consisting of wheat gluten as a structural layer and a thin lipid layer as a moisture barrier were investigated and examined for water vapour permeability. Solid lipids such as beeswax or paraffin wax deposited in a molten state onto the base film were the most effective water vapour barriers. A film consisting of wheat gluten, glycerol and diacetyl tartaric ester of monoglyceride as one layer, and beeswax as the other yielded a water vapour permeability of 0.0048 g mm m−2 mmHg−1 24h−1, which was less than that obtained with low density polyethylene.