Effect of γ-polyglutamate on the rheological properties and microstructure of tofu

The effects of γ-polyglutamates with different concentrations (0.1%, 0.15%, 0.2%) and molecular weights (high, medium, low) addition on the rheological properties, microstructure, and syneresis of tofu were studied. The addition of γ-polyglutamate increased the gelation time, and decreased the storage modulus (G′) and the loss modulus (G″) of tofu. The molecular weight and concentration of γ-polyglutamate effectively changed the rheological properties of tofu. The network of tofu without γ-polyglutamate addition was constructed by fine strands in a dense arrangement as seen by using scanning electron microscope. However, the addition of γ-polyglutamate reduced the thickness of the strands in tofu network. Tofu syneresis was also reduced by the addition of γ-polyglutamate. Increase the concentration of γ-polyglutamate significantly decreased the syneresis of tofu. This trend was more evident on the tofu with high molecular weight γ-polyglutamate.