Anti-Listeria monocytogenes activity of enterocins microencapsulated by ionic gelation

Abstract

The encapsulation of enterocins synthesized by Enterococcus faecium CRL1385 through ionic gelation with calcium ions was analyzed. Different enterocins samples were lyophilised and encapsulated using low-methoxyl pectin as the coating material. Lipids present in milk butter were also added to control the release of antimicrobial peptides from the capsules. The morphology of fresh and freeze-dried capsules was examined using light microscopy and scanning electron microscopy, respectively. Antimicrobial activity of encapsulated bacteriocins was assessed against Listeria monocytogenes 01/155 using the agar diffusion technique and direct contact in microplates. The capsules with higher lipid content showed a more spherical and uniform shape. Pathogen inhibition was observed for capsules prepared with different bacteriocin solutions both on solid (halo diameter ¼ 8.5e13.5 mm) and in an aqueous medium (ca. 2 log orders decline in L. monocytogenes viability). The outcomes suggest that bacteriocin encapsulation through ionic gelation can be a potential alternative for the application of these antimicrobial peptides as biopreservatives in food.