| The prolonged efficacy of antimicrobial peptides is important for reducing the risk of pathogen contamination and thus improving food safety. In this work, nisin and epsilon-poly-L-lysine (EPL) were used as the peptide models, Listeria monocytogenes and E. coli O157:H7 were selected as pathogen models. Phytoglycogen (PG), a dendrimer-like carbohydrate polymer from maize mutant was used to prepare phytoglycogen octenyl succinate (PG-OS), an amphiphilic, negatively charged nanoparticle to deliver antimicrobial peptides. Two types of delivery system were designed and tested: nanoparticle dispersion and nanoparticle-stabilized emulsion. The result showed that PG-OS nanoparticles were effective to prolong the efficacy of nisin against Listeria, and PG-OS-stabilized emulsion was superior to prolong the efficacies of both nisin and EPL against Listeria and E. coli, respectively. For example, PG-OS emulsion retained an effective inhibitory activity of nisin against Listeria after 50 days storage, compared with only 5 days for nisin only. In addition, PG-OS emulsion retained an effective inhibition of EPL against E. coli for over 20 days, compared with 10 days of EPL-only solution. To understand the retention of peptides with delivery systems, the adsorption and availability of peptides was also studied using other approaches. In general, this work demonstrated a novel strategy to enhance food safety and may also benefit other application areas. |
