Effect of lactoferrin and its derivatives against gram-positive bacteria in vitro and, combined with high pressure, in chicken breast fillets

The bactericidal activity of lactoferrin (LF), amidated lactoferrin (AMILF), pepsin digested lactoferrin (PDLF), and its activated (ALF) commercial form, against six strains of three gram-positive bacterial species was investigated. Listeria monocytogenes was most sensitive in vitro, Staphylococcus aureus showed a moderate resistance, and Enterococus faecalis was highly resistant to antimicrobials. When chicken breast fillets were inoculated with L. monocytogenes CECT5725 and treated with antimicrobials, reductions were below 0.5 log CFU/ml in all cases. In combination with high pressure (HHP) treatment at 400 MPa for 10 min, antimicrobials showed a slight additional bactericidal effect, always below 1 log CFU/g. Incorporation of antimicrobials 18 h before or 1 h after HHP treatment generally yielded better results than incorporation 1 h before HHP treatment, although reductions remained below 1.5 log CFU/g in all cases. LF and its derivatives showed a limited potential for pathogen control in meat.

► L. monocytogenes was the most sensitive species in vitro, and E. faecalis the most resistant, to lactoferrin and derivatives. ► Lactoferrin and derivatives lowered counts of L. monocytogenes in chicken breast fillets by less than 0.5 log units. ► Antimicrobials combined with HHP treatment at 400 MPa showed a slight additional bactericidal effect, below 1 log unit. ► Antimicrobial addition 18 h before or 1 h after HHP treatment achieved higher efficacy, which did not exceed 1.5 log units.