Boosting emulsion properties: The role of β-sheet content and fibril length in soy protein isolate emulsions

This study aimed to research the effects of beta-sheet content and fibril length in three categories ((low, medium, and high beta-sheet) and (short, medium, and long fibrils)) on soy protein isolate (SPI) emulsions. The highest surface hydrophobicity (H0) (27,600 +/- 100) was detected in the sample with the highest beta-sheet content and the longest fibril length. The interfacial tension presented that the sample with the highest beta-sheet content and longest fibril length could adsorb quickly at the oil (O)/water (W) interface. The emulsion stabilized by high beta-sheet content and long fibril length had a lower droplet size (202 +/- 4.35 nm) with more homogenous distri-bution and higher viscosity (8.75 +/- 0.13 cP) due to more entanglement. According to the environmental stresses results (i.e., various ionic strengths (0-400 mM), pH changes (2-9.5), thermal treatment, and 30 days of storage), the emulsion prepared by the sample with the highest beta-sheet content and the longest fibril length was more stable than other emulsions. Moreover, all emulsions were unstable against freeze-thaw treatment. Finally, it could be concluded that higher content of beta-sheet and longer fibril led to the stability of emulsion through higher initial absorption at the O/W interface, formation of a continuous and thicker membrane coating at the O/W interfaces, viscosity improvement, and H0 enhancement.