Modulation of interfacial phenolic antioxidant distribution in Pickering emulsions via interactions between zein nanoparticles and gallic acid.

The impacts of protein nanoparticles on the interfacial distribution of antioxidants and the oxidative stability in Pickering emulsions are attracting increasing research interests. In the present work, the distribution of gallic acid (GA) in zein nanoparticles-stabilized Pickering emulsions (ZPE) was determined by employing a pseudophase kinetic model. The interfacial distribution of GA was found to be favored in ZPEs with higher zein nanoparticle concentration (Czein). Upon increasing Czein, the interfacial loading of nanoparticles (Γ) dominated the modulation of %GAI via hydrogen bonding between zein nanoparticles and GA. The interfacial percentage of GA (%GAI) increased from 28% to 39% as Γ increased from 0.48 to 1.12 mg/m2. In the presence of GA, a direct correlation between Czein or Γ and oxidation stability was recognized, whereas the oxidative stability showed a non-linear dependence on either Czein or Γ in the absence of GA. By excluding antioxidant effects of zein nanoparticles, we found that the %GAI, which was regulated by Γ, took the leading role over the physical barrier effect on the oxidative stability of emulsions. The present work extends our current knowledge on how protein based nanoparticles manipulate the interfacial distribution of antioxidant and then affect the oxidative stability of emulsions.