Structured silica materials as innovative delivery systems for the bacteriocin nisin.

Nisin was encapsulated in silica through sol-gel process by acid-catalyzed routes. The silica xerogels were characterized through nitrogen adsorption isotherms, small-angle X-ray scattering (SAXS), zeta potential, X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectance spectroscopy (DRS), and Fourier transform infrared spectroscopy (FTIR). SAXS results showed that the particle diameters in a second level of aggregation varied from 4.78 to 5.86 nm. Zeta potential of silica particles were from -9.6 to -25.3 mV, while the surface area and pore diameters ranged from 216 to 598 m2 g-1 and 2.53 to 2.90 nm, respectively, indicating the formation of mesoporous nanostructures. Nisin retained the antimicrobial activity against all microorganisms tested after encapsulation in silica materials. These novel silica-based structures can be valuable carriers for nisin delivery in food systems.