Nisin-loaded chitosan-monomethyl fumaric acid (CM-N) nanoparticles were evaluated as a novel, direct food additive. Chitosan (CS) was modified with monomethyl fumaric acid (MFA) in the presence of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC). CS-loaded nisin (CS-N) and CM-N nanoparticles were produced through ionic interactions between the positive amino group of CS and CS-MFA and negative tripolyphosphate ions. The resultant materials were characterized by TNBS assay, X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, and zeta potential analysis. CS-MFA was successfully synthesized with 8.38 ± 0.02% substitution of the amino groups, as confirmed by TNBS assay. The percentage yield of CS-N and CM-N nanoparticles was 81.64 and 76.83% and nisin encapsulation efficiency was 71.48 ± 0.48 and 60.32 ± 0.63%, respectively. The average particle size of CS-N and CM-N nanoparticles was 134.3 and 207.9 nm, while the zeta potential of CS-N and CM-N nanoparticles was +39.4 mV and +31.5 mV, respectively. Upon antibacterial activity against foodborne pathogens, CM-N significantly reduced bacterial counts compared to the other tested samples in orange juice after 48 h of incubation. Based on the preliminarily results, CM-N nanoparticles have shown impressive properties and can be used in the food industry as carriers and direct antimicrobial agents.
Keywords: Antibacterial activity; Chitosan derivative; Foodborne pathogen; Monomethyl fumaric acid; Nisin; Orange juice.
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