Preparation of extra-small nisin nanoparticles for enhanced antibacterial activity after autoclave treatment

Nisin is applied broadly in the food industry as an antimicrobial peptide. The objective of this study is to prepare nisin nanoparticles using free nisin by a facile nanoprecipitation technique and to investigate their antimicrobial activity after high-temperature processing. Transmission electron microscopic images showed that the size of extra-small nisin nanoparticles with different initial concentrations of nisin (0.1%, 0.3% and 0.5%) was 5, 10 and 15 nm, respectively. The nisin nanoparticles were stable at pH 5.0 with the smallest size. Moreover, nisin nanoparticles exhibited a higher antimicrobial activity than free nisin at a concentration below 2.0 mg/ml after autoclave treatment. These results suggested that nisin nanoparticles could serve as a potential food preservative.