Effect of Macromolecular Crowding Agents on the Thermal Stability of Molten Globule-state Soybean 11S Globulin

This study aimed to investigate the effects of different concentrations of macromolecular crowding agent Ficoll 70 on the thermal stability and functional properties of fused globular soybean 11S globulin in a 100 ℃ water bath heated for 20 min. The results showed that low concentrations of Ficoll 70 (2~40 mg/mL) maintained the secondary structure of fused globular 11S globulin, and the intrinsic fluorescence intensity and surface hydrophobicity were reduced, compared with those without Ficoll 70 treatment. The structure of fused globulin after heat treatment was the most similar to that of untreated fused globular 11S globulin at 40 mg/mL Ficoll 70. Meanwhile, the addition of Ficoll 70 reduced molecular aggregation, enhanced molecular flexibility, and significantly improved its emulsifying and foaming properties. When the concentration of Ficoll 70 was 40 mg/mL, the average particle size of fused globular 11S globulin decreased, EAI and ESI increased to 12.35±0.01 m2/g and 199.95%±0.29%, FC and FS increased from 54.29%±0.58% to 63.71%±1.89%, 57.81%±0.51% to 86.53%±0.46%, respectively. However, when the concentration of Ficoll 70 reached 50 mg/mL, it had a negative impact on the stability and functional properties of the protein, resulting in molecular aggregation and a decline in functional properties. The above results showed that the addition of an appropriate concentration of Ficoll 70 could adjust the structure of fused globular soybean 11S globulin by eliminating the volume effect, thus affecting the functional properties of fused globular soybean 11S globulin. This study provides a theoretical basis for improving the thermal stability and functional properties of fused globular soybean 11S globulin by using a macromolecular crowding agent.