Tuning Gelation of Insect Proteins: Effect of Ionic Strength on Acheta domesticus Protein Extracts

Protein gelation is a key mechanism for structuring food systems, as it determines texture, water retention, and overall product stability. Therefore, understanding how processing factors influence gelation is critical for designing functional protein-based matrices. This study investigates the effect of ionic strength on the gelation and techno-functional properties of Acheta domesticus (house cricket) protein extract. Gels were prepared with increasing NaCl concentrations (0-0.5 M) and characterized by rheological analysis. Additionally, solubility, emulsifying properties and water/oil holding capacity of the protein extract were assessed. Small-amplitude oscillatory shear tests revealed that G' increased from ~150 Pa at 0 M to over 1300 Pa at 0.5 M, indicating salt-induced network reinforcement. The loss factor (tan δ) reached its minimum (0.19) at high ionic strength, reflecting the formation of stronger, more elastic protein networks. These rheological trends aligned with the techno-functional responses: solubility peaked at 79.5% at 0.1 M NaCl before decreasing at higher salt levels, while emulsifying activity reached a maximum of 59.1 m² g^-1 at 0.3 M before dropping sharply. Collectively, these findings highlight ionic strength as a tunable parameter linking molecular interactions to bulk viscoelasticity and textural attributes. By adjusting salt concentration, elasticity, hydration, and interfacial stability can be strategically modulated, enabling the rational design of insect-based food gels for different applications, from emulsified systems to fibrous meat analogs.