Structure and physicochemical properties of amphiphilic agar modified with octenyl succinic anhydride

A novel amphiphilic agar with high transparency and freeze-thaw stability was prepared using octenyl succinic anhydride (OSA). Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy confirmed that the hydrophobic OS groups were successfully introduced in OSA-modified agar (OSAR) backbone. The OSAR showed higher emulsion stability and oil loading capacity than the native agar (NA). Compared with gel transparency (47.1 %), syneresis (42.1 %) of NA, OSAR exhibited high gel transparency (80 %) and low syneresis (3.3 %) when the degree of substitution (DS) was 0.06 and 0.12, respectively. Meanwhile, the OSAR showed a decreased interface tension and average molecular weight after modification. Thermogravimetric analysis indicated the thermal stability of OSAR was decreased, while texture profile analysis showed the springiness of the OSAR gel was enhanced. Dynamic rheology measurements revealed the OSAR with low gel strength displayed more liquid-like properties. Moreover, the OSAR exhibited lower turbidity and melting temperatures than the NA.

Automated summary

The novel amphiphilic agar modified with octenyl succinic anhydride (OSAR) showed higher transparency and freeze-thaw stability, as well as improved emulsion stability and oil loading capacity compared to native agar (NA). With DS values of 0.06 and 0.12, OSAR exhibited increased gel transparency and decreased syneresis, lower interface tension and average molecular weight, decreased thermal stability, enhanced gel springiness, more liquid-like properties with low gel strength, and lower turbidity and melting temperatures than NA.