Swelling behaviour of agar/κ-carrageenan-based gels in neutral salt solution

Abstract Understanding the effect of neutral salt solutions on the swelling behaviour of agar/κ-carrageenan gels is essential for developing novel semi-solid food products. In this study, hydrogels were prepared with different agar/κ- carrageenan ratios (1:1 and 1:2 g/g) and polymer concentrations (2.0, 2.5, and 3.0% w/v). Their swelling capacity was evaluated in NaCl and KCl solutions across a concentration range of 0.0001 to 0.1 M. Swelling was measured gravimetrically by recording the weight change of gels before and after immersion in salt solutions at set time intervals. Results showed that swelling behaviour depended on salt type, salinity, polymer ratio, and hydrocolloid concentration. Gels with higher κ- carrageenan fractions exhibited increased swelling, while higher total polymer content reduced swelling. At constant salt concentrations, NaCl induced greater swelling than KCl. Gels in low-salt conditions showed the most significant weight gain. However, higher swelling often correlated with reduced gel strength. These findings highlight the potential of agar/κ-carrageenan hydrogels for use in texture-modified and salt-sensitive food applications.