Abstract:Tannic acid-loaded zein nanoparticles (TZP) were fabricated by the anti-solvent method, and the TZP dispersion was dispersed into a polysaccharide solution with a pH of 4.0 at a volume ratio of 1:2. The effects of different anion-charged polysaccharides (propylene glycol alginate, PGA; gum Arabic, GA; high-methoxyl pectin, HMP; low-methoxyl pectin, LMP) on the stability of TZP were investigated. The results showed that the polysaccharide at a low concentration decreased the surface charge of particles, causing the precipitation of nanoparticles, with the minimum concentration required to stabilize the particles being 0.055% (m/V) for PGA, GA and HMP, and 0.022% (m/V) for LMP. The changes in the stability of TZP/polysaccharide composite nanoparticles with pH or NaCl were associated with the ζ-potential of anionic polysaccharides. GA with a lower potential led to the precipitation of nanoparticles at pH 2.0, 6.0 or 6.5 and a low NaCl concentration, whereas, LMP with the highest potential stabilized the nanoparticles in the pH range of 2.0~8.0, with the particles precipitating at a sodium chloride concentration of 30 mmol/L. After freeze-drying, the yield of TZP/LMP nanoparticles reached 95.10% with the tannic acid loading rate as 88.97% and tannic acid content as 5.39%. The research showed that zein/LMP nanoparticles could be used for encapsulating and delivering hydrophilic bioactive compounds, which are expected to be used in the functional food or pharmaceutical industries.
