Salt-tolerant nanoemulsions stabilized by the complex of starch sodium octenyl succinate and tannic acid

Inorganic salts frequently influence the stability of nanoemulsions, thereby restricting their potential applications. Herein, calcium salt-tolerant nanoemulsions were prepared using a complex of starch sodium octenyl succinate (SSOS) and tannic acid (S-TA). The nanoemulsions stabilized by the S-TA complex demonstrated significant advantages when compared to those stabilized solely by SSOS or by other SSOS complexes. Specifically, the nanoemulsions stabilized by the S-TA complex preserved a slight change in the droplet size 346.24 ± 7.65 nm for over 4 weeks at 2.0 wt% calcium chloride. Furthermore, they exhibited exceptional centrifugal stability at 5000 rpm for 10 min over 5 cycles, as well as notable antioxidant properties. The primary and secondary oxidation products of the nanoemulsions stabilized by the S-TA complex after 14 days were 131.69 μg/mL and 19.34 μg/mL, respectively. Analyses including FT-IR, XRD, and hydrophobicity fluorescence confirmed that non-covalent interactions (such as hydrogen bonding and hydrophobic interactions) endowed the S-TA complex with enhanced interfacial activity and salt resistance. The research improves the salt resistance of starch emulsifiers, offering a strategy for nanoemulsions to maintain stability in environments with inorganic salts, especially calcium salts, thereby broadening their potential applications.