Evaluation of nisin using high performance liquid chromatography - mass spectrometry

Abstract

Nisin is a low molecular weight antimicrobial polypeptide or bacteriocin produced by certain strains of Lactococcus lactis subsp, lactis. It has been used as a food preservative. The earliest use of nisin in food was as a preservative in processed cheese products. The objective of this research was to study parameters for concentrating nisin from 2.5 % preparation using 100 % acetonitrile. To concentrate and clean nisin a solid phase extraction (SPE) CI8 cartridge was used. To assess nisin composition and determine the salt content in the sample after SPE purification the capillary electrophoresis with conductivity detection was applied. High-pressure liquid chromatography - electrospray ionization mass spectrometry (HPLC-ESI-MS) method was applied and optimized for qualitative and quantitative analysis of bacteriocins. Validation steps have been performed, namely repeatability, linearity, limits of detection and determination using nisin standard. This method enables determination of nisin in the biological and food samples.