Advancing the assessment of oxidative stability in co-stabilized zein nanoparticles and xanthan gum Pickering emulsions using isothermal calorimetry

This study aims to apply isothermal calorimetry to investigate the oxidative stability of Pickering emulsions made with zein nanoparticles (ZNPs) and xanthan gum. The ZNPs were fabricated using an anti-solvent precipitation method, resulting in nanoparticles with a particle size of 168.4 ± 38.9 nm and a zeta potential of +27.8 ± 7.3 mV. Xanthan gum was incorporated to enhance the physical stability by increasing the viscosity of the continuous phase. The emulsions oil phase consisted of different plant-based oils such as sunflower, corn, olive, and soy. Pickering emulsions physical stability was characterized using a multiple light scattering technique. Kinetic parameters of emulsions oxidative stability, including induction time (τ), rates of inhibited (R_inh) and uninhibited (R_uni) periods, and oxidizability index (O.I.) were determined by isothermal calorimetry. Pickering emulsions exhibited a different oxidative stability depending on the oils used, with olive oil-based emulsions showing the longest induction time, highest antioxidant efficiency (A.E. = 9.35 ± 0.07), and lowest oxidizability index (2.25 ± 0.02 (M·h)^-0.5). The results correlated with the total phenolic content and antioxidant activity of the oils. The findings provide valuable insights into designing emulsion-based formulations, emphasizing the role of oil type in enhancing Pickering emulsion oxidative stability.