Chemically modified gliadins as sustained release systems for lysozyme

The aim of this work has been to study the effectiveness of gliadin films cross-linked with cinnamaldehyde as systems for the release of the natural antimicrobial compound lysozyme. Prior to the incorporation of lysozyme, the gliadin film-forming solution was treated with different percentages of cinnamaldehyde as cross-linker, and glycerol was added as plasticizer. The effect of the concentration of the cross-linker on the swelling capacity and kinetics of release of the antimicrobial agent from the protein matrix was evaluated at pH 6.2. The antimicrobial activity of the films was assayed against Listeria innocua. The gliadin films cross-linked with cinnamaldehyde incorporating lysozyme preserved their integrity in water. The release rate of the antimicrobial agent was controlled by the reticulation of the protein matrix, thus a greater degree of cross-linking led to slower release of the active agent. Films with a loosely cross-linked structure released a greater amount of lysozyme, exhibiting greater antimicrobial activity.