Structural changes and stress relaxation behavior of κ-carrageenan cold-processed gels: Effects of ultrasonication time and power.

Ultrasound has been used for cold gelation of κ-carrageenan hydrocolloid. In this work, the effect of ultrasound conditions such as power (50-150 W) and time (20-240 s) of sonication has been investigated. The application of ultrasound to hydrocolloid dispersion caused an increase in water solubility. The texture profile analysis test was used in order to evaluate the mechanical properties of gels. Textural parameters of κ-carrageenan gels, enhanced with increasing sonication time and power up to a certain level (usually 2.5 min) and longer sonication times had negative effects. In addition, intrinsic viscosities of sonicated specimens were measured to investigate the molecular characteristics of all samples. An increase in the process time and power reduced the intrinsic viscosity. The microstructural observation by scanning electron microscope determined that applying power ultrasound on κ-carrageenan dispersions influenced the formation of gel networks significantly.