Stability Analysis of Pickering Nanoemulsion Covered by Dual-protein Natural Symbiotic Particles

Pickering nanoemulsions were prepared using dual-protein natural symbiotic particles and their physicochemical stability was analyzed to broaden their potential application in the food industry. This study employed alkali extraction-isoelectric point precipitation (AE) and salt extraction-dialysis (SE) to enrich soy protein and flaxseed protein from soybean-flaxseed mixed meal for fabricating dual-protein symbiotic natural particles (SFNPs). First, two dual-protein symbiotic particles were characterized using appearance observation, AFM, circular dichroism, and Raman spectroscopy. Then, Pickering nanoemulsions were prepared with them as particle stabilizers and characterized for their physical and chemical stability. Results demonstrated that AE-SFNPs had a higher uniformity of size and better dispersibility. AE-SFNPs also showed a higher proportion (as high as 51.25%) of β-sheet in its secondary structure, endowing it a more tightly ordered and flexible structure compared with SE-SFNPs. Moreover, both AE-SFNPs and SE-SFNPs could be used to generate Pickering nanoemulsion. During 28 days of storage, the particle size of the stabilized emulsion of AE-SFNPs increased only about 14 nm and its ζ-potential was stabilized at about -34 mV. In contrast, the particle size of the stabilized emulsion of SE-SFNPs increased about 12 fold, and its ζ-potential was decreased 1.32 fold. The stability index (TSI, 5.83) of the AE-SFNPs was much smaller than the TSI value (55.13) of the SE-SFNPs when stored until the 28th day. Notably, the Pickering nanoemulsion stabilized by AE-SFNPs exhibited higher physical and chemical stability than that prepared by sodium caseinate (a common emulsifier used in food processing). Therefore, AE-SFNPs can serve as a natural and efficient plant protein-based particle stabilizer to prepare Pickering nanoemulsion. This work provides a new strategy to enhance the industrial application of nanoemulsions.