Designing soluble soybean polysaccharides-based nanoparticles to improve sustained antimicrobial activity of nisin

Nisin is a natural antimicrobial agent and food-grade material, while the poor stability and short duration of antimicrobial activity limit its widespread use in the food industry. In the present work, soluble soybean polysaccharide (SSPS)-based nanoparticles have been developed to improve the stability and sustained antimicrobial activity of nisin. The encapsulation efficiency (EE) of nisin-loaded SSPS nanoparticles (Nisin-SSPSNPs) prepared under the optimized conditions can be up to 99.8%, and the particle size is about 112 nm. The formation of Nisin-SSPS-NPs was mainly mediated by the electrostatic interactions and hydrogen bonding, which was evidenced by the results of zeta potential and Fourier Transform infrared spectroscopy (FTIR). Agar diffusion assay exhibited that Nisin-SSPS-NPs had confirmed antimicrobial activity against Gram-positive bacteria, such as Listeria monocytogenes, Bacillus subtilis, and Staphylococcus aureus. The sustained release of nisin in Nisin-SSPS-NPs endows nisin with a long-lasting antimicrobial activity, which increases the shelf-life of the fresh tomato juice.