Retail display of beef steaks coated with monolayer and bilayer chitosan-gelatin composites.

The effects of edible monolayer and bilayer chitosan-gelatin coatings on the weight loss, lipid oxidation, color preservation (display-life), and shelf-life of beef steaks during 10 days of retail display (at 4 °C; 12 h light/day) were evaluated. The edible coatings had a homogeneous crack-free surface, with the bilayer films being two times thicker than the monolayer coatings. During storage, the control samples had higher pH values and more weight loss (P < .05) than the coated ones. The coatings effectively retarded (P < .05) lipid oxidation and microbial growth (psychrotrophic bacteria, molds, and yeast), extending the shelf-life from 6 to 10 days. The coatings also significantly prevented metmyoglobin accumulation on the beef surface, as reflected in the maintenance of the CIE color indices and sensorial redness perception throughout storage. These effects were similar for both the monolayer and bilayer films, suggesting that chitosan-gelatin coatings could improve the shelf-life and display-life of beef during retail storage.