Construction of sea bass (Lateolabrax japonicus) powder/κ-carrageenan composite gels: Nonlinear rheological properties, IDDSI classification, and gelation mechanisms.

The effect of κ-carrageenan (κ-C, 2-6 mg/mL) on the gelling properties of sea bass powder (SBP) were investigated. Adding κ-C increased storage modulus of SBP by 10- to 61-folds and raised the sol-gel transition temperature. Nonlinear rheological analysis characterized the SBP/κ-C gels by weak strain overshoot and intracycle shear thinning behavior. According to the International Dysphagia Diet Standardization Initiative (IDDSI) framework, the SBP/κ-C gels were classified as level 4-6 foods. Moreover, the T23 relaxation time of the SBP/κ-C gels migrated from 666.99 ms to 554.27 ms. Correspondingly, the network structures of SBP became denser and uniform after adding κ-C. In addition, a blue shift in hydroxyl bands confirmed the formation of hydrogen bonds between SBP and κ-C. Adding κ-C increased the proportions of β-sheets and random coil, but sacrificed the α-helix part of SBP. These results provided a theoretical basis for the development of marine-derived soft gel-based foods.