A Novel Functional Wrapping Design by Complexation of ε-Polylysine with Liposomes Entrapping Bioactive Peptides

An innovative edible wrapping with potential use for designing functional foods with antimicrobial capacity was developed by complexation of e-polylysine with peptide-loaded liposomes. Unmarketable long-term frozen cooked shrimp (Litopenaeus vannamei) muscle was used as a source of both bioactive peptides and complex liposomal suspension carrier, producing a sustainable value-added protein wrapping material with desirable sensory properties. A <10-kDa peptide fraction (SH) with antioxidant and angiotensin-converting enzyme inhibitory capacity was encapsulated in partially purified phosphatidylcholine (PC) liposomes (LSH) with an entrapment efficiency of 85 %. The average size and zeta potential of LSH were 164 ± 2 nm and –37.0 ± 1.7 mV, respectively. The LSH surface changed from electronegative to electropositive upon adsorption of e-polylysine (PL) with an optimal concentration of 0.5 %. The average diameter and zeta potential of the resulting complex e-polylysine-adsorbed liposomes containing the peptide hydrolysate (PL-LSH) were 216 ± 5 nm and +51.1 ± 1.1 mV, respectively. The e-PL proved to be effective as liposome stabilizing and antimicrobial agent. The PL-LSH suspension was incorporated in the formulation of the protein wrapping to provide it with both bioactive and antimicrobial properties. The wrapping showed low water solubility (≈30 %) and low mechanical resistance (tensile strength = 0.23 ± 0.06 MPa; elongation at break = 0.91 ± 0.19 %) properties that allowed it to be very versatile for varied food design and was effective against Listeria monocytogenes, Escherichia coli, Staphylococcus aureus and Yersinia enterocolitica.