Modification of functionalities and in vitro digestibility of clam Mactra chinensis powder upon ultrasound treatment

Abstract Background Abundant protein and amino acids have been found in clam Mactra chinensis powder (MCp), while the functionalities and in vitro digestibility of MCp are not clear. Meanwhile, ultrasound treatment is wildly used in modification of proteins. In this study, ultrasound was used to modify MCp at amplitudes from 30% to 90%, and the functionalities and in vitro digestibility of MCp upon ultrasound treatment were evaluated. Results After ultrasound treatment, the solubility and water‐holding capacity of MCp increased by 25.0% and 120%, respectively, reflecting the enhanced interaction between protein and water. The oil‐holding capacity and emulsification activity indexes of MCp were significantly increased by 85.8% and 36.6% at 60% and 30% ultrasound amplitudes, respectively. Moreover, MCp suspensions with ultrasound treatment had high G′ value and apparent viscosity, with increases of 6.8‐fold and 16.7‐fold at 60% ultrasound amplitude, respectively, which corresponded to a homogeneous and dense network structure. In addition, amide I and II bands of MCp underwent a pronounced shift, and the maximum fluorescence emission wavelength increased in intensity with increasing ultrasound amplitudes, indicating unfolding of the protein structure and exposure of the chromophore. The significant increase in digestibility of ultrasound‐treated MCp was related to the unfolding structure and the exposure of binding sites to digestive enzymes. Conclusion Treatment with ultrasound at different amplitudes resulted in a modification of functionalities and in vitro digestibility of MCp, thereby providing a theoretical basis for the development of marine protein foods. © 2025 Society of Chemical Industry.