Ultrasound-Driven Conformational Rearrangement of Coilia ectenes taihuensis Myofibrillar Protein Enhances Emulsion Stability

Myofibrillar protein (MP) from Coilia ectenes taihuensis (CMP) has potential as a natural emulsifier; however, its relatively compact native structure may restrict its functional performance. This study evaluated the effects of ultrasound treatment (0–600 W) on CMP conformational characteristics and the stability of CMP-based emulsions. Ultrasound-induced power-dependent structural and oxidative modifications in CMP, as evidenced by increased carbonyl content, decreased sulfhydryl content, secondary structure rearrangement, and altered surface hydrophobicity. Under the conditions tested, CMP treated at 450 W exhibited the highest surface hydrophobicity and enhanced solubility, which were associated with improved emulsifying properties. The emulsifying activity index increased from 39.93 m2/g to 82.17 m2/g, accompanied by reduced droplet size, higher absolute ζ-potential values, enhanced viscoelastic properties, and a reduced creaming index. However, at 600 W, further structural modification and possible protein association may have contributed to the decline in emulsifying performance. These findings suggest that appropriate ultrasound treatment can improve the emulsifying performance of CMP under the conditions investigated, providing insights into its potential application in protein-based emulsion systems.