Effect of Ratio and Freeze–Thaw Cycles on Hydrogel Physochemical Properties Derived from Spirulina (Arthrospira platensis) Protein Concentrate and Carrageenan for Sausage Application

Spirulina protein concentrate (SPC) (76 protein content) offers promising techno-functional properties for hydrogel applications in animal (meat/fish) products. The aim of this study was to characterize hydrogel with different ratios of SPC and carrageenan (Carr) (4:4, 5:3, and 6:2) and evaluate the effect of freeze–thaw method cycle on the properties of texturized spirulina hydrogel (TSH). Results indicated that a higher Carr proportion compared to SPC enhanced the physical properties, including larger G′ and G″, hardness (58.35 N), cohesiveness (0.56), gumminess (32.86 N), chewiness (25.81 N), springiness (0.78), and water-holding capacity (97.40) of the hydrogel. Freeze–thaw cycles influenced the properties of the TSH. However, TSH produced with two and three freeze–thaw cycles had comparable properties. TSH with 2 cycles of freeze–thaw resulted in porous structures, with a hardness value of 69.06 N, cohesiveness of 0.49, gumminess of 32.65 N, chewiness of 32.65 N, springiness of 0.73, and swelling ratio of 241.07. Substituting fish with 50 TSH in sausages reduced fat content while increasing moisture and ash content (8.98). The substitution also significantly influenced the texture of sausages. Substituting fish with TSH could broaden the application of protein-based spirulina and reduce the overall cost. Overall, preparing hydrogels using the freeze–thaw method is a simple and convenient approach for texturizing protein concentrate for use in meat or fish derivative products. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2026.