Nisin is a cationic antimicrobial peptide, used in the food industry against gram-positive bacteria. The efficiency of this peptide could be reduced by environmental stresses, proteolysis, and undesirable interactions with food components. To overcome this problem, nisin can be encapsulated using lipids, proteins, or carbohydrates. Encapsulation also provides controlled release which plays a key role in improving the shelf life of foods [1]. It is important to research controlled antimicrobial peptide release from the particles to predict how long its antimicrobial effect will last. In this work, for the synthesis of particles fucoidan was used.
Fucoidan – anionic, sulfated polysaccharide produced by brown seaweed such as Macrocystis pyrifera, Laminaria japonica, and Fucus vesiculosus. It also has antitumor, antithrombotic, anti-inflammatory, anticoagulant, and antioxidant activity, which could also provide additional beneficial properties for food products [2].
This study researched in vitro release of nisin from nisin-loaded fucoidan particles. Release of the antimicrobial peptide was monitored using dialysis against 25 mM phosphate buffer solution at different pH (2, 6, and 8), temperatures (20 and 37 °C), and ionic strength (0; 0.1; 0.2 and 0.5 M of NaCl). As a control, the diffusion of non-encapsulated nisin through a membrane against phosphate buffer without NaCl was used. The greater influence of ionic strength was only observed at pH 2 at both temperatures. In this case, more nisin is released from the particles when the concentration of NaCl increases. At pH 6, the amount of released nisin increases with increasing ionic strength up to 0.2 M. However, further increasing the ionic strength slows down the release of nisin.
When investigating the influence of pH on the release, it was observed that more nisin is released at pH 6 (60–80% after 96 hours) at 20 °C. A similar amount of released peptide (10–40%) was observed at higher temperatures regardless of pH. Enhanced hydrophobic interactions could be a reason why higher temperatures did not induce the release of nisin.