The structural and functional properties of soybean protein-polyglutamic acid complex effected the stability of W/O/W emulsion encapsulated Nattokinase

Nattokinase (NK) derived from food is a sustainable thrombolytic agent. In this study, to protect vulnerable biological activity of NK, the targeted modified W/O/W emulsions were fabricated from complexes of soybean isolate protein (SPI) and polyglutamic acid (PGA). The results showed that the SPI-PGA complex formed a tighter internal structure through non-covalent bonds. The secondary structure, alpha-helix and beta-sheet content of the 1:3 (v/v) ratio complex of SPI to PGA increased by 6.14% and 8.62%, respectively. The emulsification and stability of the complexes were improved by refining structural properties as against SPI. The W/O/W emulsions coated by complexes formed the stronger network structure with higher encapsulation efficiency, better interfacial features, and better storage stability. Moreover, the highest bioavailability was achieved by W/O/W emulsions coated with 1:3 ratio complex at 80.69%. This study provided a new strategy towards tailoring ideal emulsion vehicles and expanded the NK application in food formulations.

Automated summary

In this study, targeted modified W/O/W emulsions were fabricated from complexes of soybean isolate protein (SPI) and polyglutamic acid (PGA) to protect the vulnerable biological activity of Nattokinase (NK). The SPI-PGA complex formed a tighter internal structure through non-covalent bonds, resulting in improved emulsification and stability. The emulsions coated by complexes formed a stronger network structure and achieved higher bioavailability, expanding the application of NK in food formulations.