Nisin, which is produced by the lactic acid bacteria, Lactococcus lactis subsp. lactis, is a small 3510 Da cationic peptide composed of 34 amino acid residues. It is a broad-spectrum antimicrobial agent against Gram-positive bacteria. Nisin is widely used in the food sector for improving food safety, for example, dairy and canned food products [1]. However, nisin antimicrobial efficacy is influenced by many factors, i.e. interactions with food components or conditions used for food production. To ensure nisin stability, nisin is coating with the wall materials, e.g. proteins, polysaccharides, or lipids [2]. In this work, for particles preparation ulvan was used. Ulvan is a water-soluble anionic sulphated polysaccharide, which is derived from green algae, Ulvales. Ulvan polysaccharide is inexpensive, biocompatible, biodegradable, and nontoxic [3]. Due to numerous advantages, ulvan can be used as a coating material that forms complexes with an oppositely charged molecule.
The aim of this work was to prepare nisin-loaded ulvan particles using the complexation method and observe the effect of storage time on the loading efficiency. Nisin-loaded ulvan particles at a different pH range of 4.0-7.0 were prepared and stored at 4 °C. The final concentration of ulvan was 0.4 mg/mL, and the nisin concentration was in the range of 0.1-1 mg/mL. The loading efficiency was determined by the capillary zone electrophoresis method using 7100 Capillary Electrophoresis unit (Agilent Technologies).
The loading efficiency was evaluated after two and four weeks and was compared with the initial loading efficiency. It didn't change at all pH values with nisin concentration up to 0.3 mg/mL. The loading efficiency has decreased very slightly over time when nisin concentration was in the range from 0.4 to 1 mg/mL.