Challenge of nisin and its nanoparticles in eliminating Listeria monocytogenes inoculated in chilled minced meat

Abstract

Nisin, a bacteriocin produced by Lactococcus lactis subsp. lactis, has shown significant potential as a food preservative, particularly in inhibiting the growth of Listeria monocytogenes. This study aimed to characterize nisin nanoparticles (NNP) and evaluate their antibacterial activity in minced beef meat during refrigerated storage at 4 °C.  Fourier- transform infrared spectroscopy (FTIR) analysis revealed shifts in peaks, indicating increased hydrogen bonding in nisin nanoparticles compared to free nisin.  Transmission electron microscopy (TEM) images showed spherical particles with an average size of 10.34 ± 3.98 nm, exhibiting excellent stability. In antibacterial activity tests, minced meat treated with nisin nanoparticles at concentrations of 0.6 and 1.2 ml/100g showed a significant reduction in L. monocytogenes counts compared to the control (p < 0.01) on the 6^th and 3^rd days, respectively. However, samples treated with nisin at 1.2 ml/100g spoiled on the 6^th day. Sensory evaluation revealed that nisin nanoparticles effectively maintained the sensory quality of minced meat throughout the storage period, with enhanced acceptability on the 6^th day. The pH of treated samples remained lower than the control throughout storage, with no significant difference between nisin nanoparticle treatments on the 6^th day. TBA values showed that nisin nanoparticles at 0.6 and 1.2 ml/100g inhibited lipid oxidation, with values below 0.78 mg/kg on the 6^th day. Overall, nisin nanoparticles showed promising antibacterial and preservative effects in minced beef meat, highlighting their potential as a safe and effective food preservative.Top of Form