Determination of critical gelation conditions of κ-carrageenan by viscosimetric and FT-IR analyses

In this study, spectroscopic results, which were obtained from FT-IR at solid state, have been used for the direct determination of critical physical gelation conditions of κ-carrageenan and compared with the results obtained from viscosimetric studies. Effect of some parameters such as polymer concentration, added salt concentration and temperature on the gelation behavior of κ-carrageenan (KC) was also investigated. Influence of all these parameters on the critical gelation conditions of κ-carrageenan was followed by viscosimetric and FT-IR techniques. After a critical polymer concentration (0.7 g/dl), κ-carrageenan exhibited a complete wall-to-wall gel structure. The effect of potassium chloride (KCl) on the gelation of κ-carrageenan is discussed for non-salt and salt added systems based on the results obtained from viscosimetric measurements. It has been observed that addition of only minute amount of KCl was increased the viscosity approximately twenty fold. FT-IR results proved that critical physical gelation concentration could be determined by analyzing spectrum obtained at solid state in very short time and using only minute amount of substances.