Texture, Meltability, and Rheology of Faba Bean Protein/Kappa‐Carrageenan Emulsion Gels: Impact of Protein Concentration, pH , Ionic Strength, and Storage

Abstract

This study investigates the texture, meltability, and rheology of faba bean protein concentrate (FPC)/kappa-carrageenan (KC) emulsion gels, focusing on the impact of protein concentration (1%–4% w/w), pH (4–7), ionic strength (0 and 0.171 M NaCl), and storage time (1 and 15 days). At pH 4, FPC aggregated near its isoelectric point (ζ-potential≈0 mV), while KC maintained a strongly negative charge (≈−50 mV). Maximum turbidity was observed at pH 4, indicating protein-polysaccharide complex formation. Texture analysis revealed non-linear behavior, with 4% FPC gels exhibiting the highest hardness (34.13 ± 3.95 N at pH 7), while NaCl addition reduced hardness (e.g., 18.05 ± 1.58 N to 2.24 ± 0.09 N at pH 6) and water holding capacity (86.80% ± 0.72% to 69.14% ± 1.28% at pH 5). Meltability peaked at 2% FPC (51.56 ± 3.30 mm at pH 6), correlating with reduced cohesiveness. Rheological analysis confirmed strong elastic behavior (G′ > G″), with phase transition temperatures decreasing from 81.85°C ± 1.17°C (pH 5) to 73.11°C ± 0.35°C (pH 7). These results offer a framework for optimizing the texture and stability of FPC/KC-based gels, addressing challenges in plant-based food formulations.