Abstract

Mantis shrimp represents a promising protein source, yet its functional properties are strongly influenced by processing conditions such as pH. This study examined how the pH-driven extraction routes influence the structural and functional properties of mantis shrimp protein isolates (MPI). Extraction at pH 1.0 and pH 12.0 yielded two types of MPI: acid-aided (Ac-MPI) and alkaline-aided (Al-MPI), which were then precipitated at pH 4.0. The pH of both final MPI ingredients was adjusted to levels ranging from 4.0 to 8.0. Zeta potential values shifted from +0.12 to –21.30 mV in Ac-MPI and from –10.11 to –27.00 mV in Al-MPI, accompanied by reduced turbidity, hydrophobicity, and free sulfhydryl group content as pH increased, indicating protein unfolding and molecular rearrangements. These structural modifications enhanced solubility and electrostatic repulsion, which facilitated protein flexibility and interfacial adsorption, thereby improving the foaming and emulsifying properties of MPI, with Al-MPI exhibiting superior performance compared to Ac-MPI. Oscillatory rheological temperature sweeps at up to 90 °C revealed that both MPI types had larger storage modulus (G') values than loss modulus (G''), indicating an ability to form elastic gels. The G' and G'' values increased significantly at pH 7.0 and 8.0, especially in Al-MPI, but NaCl addition had detrimental effects on the gel formation. The findings highlighted the significance of pH treatment in recovering MPI and its impact on enhancing the functional properties of MPI.