Preparation and antimicrobial activity of pectin-chitosan embedding nisin microcapsules

Nisin is food preservative with good food safety and is widely used around the world. However, nisin degrades during food processing and storage, seriously affecting its antibacterial function. In order to improve the stability of nisin, nisin microcapsules were prepared by complex embedding nisin with pectin and chitosan. By selecting the mass ratio of pectin to nisin and chitosan, the microcapsules of nisin loading 200 mg with 81.15% encapsulation efficiency were prepared in aqueous solution of pH 4.0. The results of zeta potential of pectin, chitosan, nisin and microcapsules, infrared spectra and X-Ray diffraction spectra confirmed the embedding of nisin by pectin-chitosan. The adsorption isotherm of pectin and chitosan showed that chitosan and pectin mainly adsorbed by monolayer to form microcapsules. Compared with the same amount of free nisin, bactericidal efficiency decreased within 24 h, which showed there is a release process in microcapsules. However, after treated with 121 °C for 10 min, the sterilization activity loss of nisin was significantly lower than that of free nisin, which showed the thermal stability of nisin pectin microcapsules was greatly increased. The nisin microcapsules with good thermal stability and sustained-release effect can be better applied in future.