Relationship between gel properties and water holding of ovalbumin-carboxymethylcellulose electrostatic complex hydrogels.

The relationship between the water holding (WH) and gel properties of protein-based hydrogels is important for designing and regulating the texture and sensory properties of foods. Herein, the relation among WH and heat-set gel properties of ovalbumin (OVA)-carboxymethylcellulose (CMC) electrostatic complexes was explored. The results showed that the gels exhibited homogeneous and dense structure and good WH compared with pure OVA at pH 4.6, while Young's modulus decreased significantly (P < 0.05). This was closely related to the inhibition of the electrostatic interaction on the formation of large protein aggregates during heat treatment (90 °C, 30 min). Specially, the CMC1.2 (the degree of substitution was 1.2) with higher charge density showed stronger interference than CMC0.7 (the degree of substitution was 0.7) for the gel network structure and properties. Moreover, the addition of salt ions could enhance the gel strength. Meanwhile, the coarseness and microstructure pore size were also increased with enhancing of ionic strength, resulting in a significant decrease in the WH. The effective permeability coefficient (k1) and water flux coefficient (k2) of gels have a significant positive correlation with their network pore size, indicated that the regulation of WH of hydrogel mainly depended on controlling the pore size of its microstructure.