Microencapsulation of Pickering nanoemulsions containing walnut oil stabilized using soy protein-curcumin composite nanoparticles: Fabrication and evaluation of a novel plant-based milk substitute.

Plant protein-stabilized Pickering nanoemulsions show potential as plant-based milk substitutes; however, their stability is challenged by mechanical stress during transportation and oxidative deterioration during storage. Herein, soybean isolate protein-curcumin composite nanoparticle (SPI-Cur-NPs)-stabilized Pickering nanoemulsions were converted into microcapsule powders via spray-drying with maltodextrin (MD), trehalose anhydrous (TA), and inulin (IN) as wall materials. Robust intermolecular hydrogen bonds and an amorphous structure were formed using composite wall materials, reducing microcapsule surface fissures while improving encapsulation rate (92.7 %) and solubility (>95 %). Moisture sorption isotherms indicated that the composite wall microcapsules demonstrated moisture resistance at a low-water activity (a < 0.43) and superior hygroscopicity at a high-water activity (a > 0.67). Accelerated oxidation tests revealed that the presence of curcumin and composite wall materials enhanced oxidative stability, demonstrating a low peroxide value (2.21 mmol/kg [34.4 %]) and TBARS content (97.8 μg/g [18.7 %]). Consequently, microencapsulated powders prepared with SPI-Cur-NPs and MD-TA-IN could potentially improve the limitation of plant-based milk substitutes.