Application of an alginate-based edible coating with bacteriocin-producing Lactococcus strains in fresh cheese preservation

Edible coatings incorporated with bacteriocin-producing lactic acid bacteria (LAB) can provide an alternative natural preservation method as they can offer an additional microbiological protection to food products. The bacteriocin-producing strains Lactococcus lactis L3A21M1 and Lc. garvieae SJM17 isolated from artisanal Azorean cheeses were incorporated into an edible fresh-cheese coating composed of alginate, maltodextrin and glycerol. The immobilization of Lactococcus cells into the coating had no negative effect on their viability and antibacterial activity throughout 10 days storage at 4 degrees C and 10 degrees C. The application of coating with immobilized Lactococcus cells on cheeses reduced significantly (p < 0.05) the contamination by Listeria monocytogenes on surface and prevented the growth of mesophilic bacteria by the 6th and 8th day of storage at 4 degrees C. Moreover, the coating reduced moisture and weight losses of fresh cheeses during storage, without affecting the pH and titratable acidity. The coating also prevented the migration of L. monocytogenes from the surface into the cheeses. These findings indicate that alginate-maltodextrin-glycerol formulation provided an excellent matrix to support Lactococcus cells viability and bacteriocin production. This bioactive coating can act as protective antimicrobial barrier in fresh cheeses by reducing bacterial contamination after processing.