Unraveling the phase behavior of cricket protein isolate and alginate in aqueous solution

• The interaction of cricket protein isolate (CPI) with alginate (AL) was studied as a function of pH, biopolymer ratio, total concentration, and ionic strength. • CPI and AL formed complex coacervates and precipitates by associative interactions. • Ionic bonding, as well as hydrogen bonding and hydrophobic interactions, are critical in CPI-AL insoluble complex formation. • Increasing the concentration of total biopolymer and monovalent salts (NaCl/KCl) aided in the development of insoluble complexes. The associative phase behavior of cricket protein isolate (CPI) and sodium alginate (AL) in aqueous solutions was explored using turbidimetry, methylene blue spectroscopy, zeta potentiometry, dynamic light scattering, and confocal microscopy as a function of pH, biopolymer ratio, total biopolymer concentration (C T ), and ionic strength. When both biopolymers had net-negative charges, soluble complexes formed between pH 6.0 and 8.0, however when both biopolymers had opposing net charges, insoluble complexes formed as complex coacervates below pH 5.5, defined as pH φ1 , followed by precipitates below another critical pH 3.0 (pH p ). Increasing the CPI:AL weight ratio or C T facilitated complex formation, and the addition of salts (NaCl/KCl) had a salt-enhancement and salt-reduction impact at low and high salt concentrations, respectively. Ionic interactions between oppositely charged CPI and AL were mainly responsible for the formation of their insoluble complexes, while hydrogen bonding and hydrophobic interactions also played significant roles.