Ethyl cellulose/gelatin-carboxymethyl chitosan bilayer films doped with Euryale ferox seed shell polyphenol for cooked meat preservation

This study evaluated the effects of an edible bilayer containing polyphenols from the Euryale ferox seed shell on ready-to-eat cooked beef products, including the physical, mechanical, antioxidant, and antibacterial capabilities. Here, the bilayer films were prepared by layer-by-layer solution pouring using hydrophobic ethyl cellulose (EC) as the outer layer, and hydrophilic gelatin/carboxymethyl chitosan (GC) as the inner layer. By adjusting the proportion of gelatin to carboxymethyl chitosan, the optical, mechanical, and barrier characteristics of bilayer films were markedly enhanced. Extracted polyphenol (EP) from shell of the Euryale ferox seed performed potent antibacterial property against Listeria monocytogenes (L. monocytogenes). The addition of EP to the inner layer of the optimized bilayer film further improved the mechanical and barrier properties of films, and as expected, the film exhibited antioxidant and antibacterial abilities. Additionally, cooked beef and cooked chicken preservation tests indicated that the active bilayer film showed good inhibition of L. monocytogenes and delayed lipid oxidation in ready-to-eat meat products, and significantly delayed the pH, moisture loss, color and texture changes. This study developed multifunctional bilayer active edible films, which has a great potential in the preservation ready-to-eat cooked meat products.