The application of pectin and chitooligosaccharides for the preparation of nisin-loaded nanoparticles with different surface charges

The application of nisin is growing due to the demand of consumers for safe and healthy food. New delivery systems of nisin are being developed and based on its encapsulation. Biopolymers having high stability and low toxicity are largely used for that purpose. The study is aimed to fabricate nisin-loaded nanoparticles with different surface charges, i.e. positive and negative. First, nisin-loaded pectin nanoparticles were prepared by the complexation method, and subsequently, they were coated with chitooligosaccharides in the concentration range of 0.025–0.5 mg/mL. The interaction of components was demonstrated by FT-IR spectroscopy. For further analysis, nisin-loaded pectin nanoparticles coated with chitooligosaccharides at a concentration of 0.025 and 0.3 mg/mL were chosen. They were soluble complexes with negative and positive surface charge, respectively. Nanoparticles were characterized in terms of size, dispersity, zeta-potential, radical scavenging activity, and proteolytic stability. The nanoparticles demonstrated long-term stability at 4 °C. Encapsulation increased the proteolytic stability of nisin. High methoxyl, low methoxyl pectin, and pectic acid were used for nanoparticle preparation. Only high methoxyl pectin and low methoxyl pectin, but not pectic acid, allow the fabrication of nanoparticles having positive and negative surface charge and the same amount of encapsulated nisin. Those nanoparticles could be useful for the investigation of the effect of their surface charge on the interaction with microorganisms and the release of antimicrobial peptides. Graphical abstract