Carrageenan, polysaccharides samples

In the present work we have studied the dynamics of formation and structure of the air-water interface in the presence of (3-lg - - PS at 20°C and at pH 7 in a drop tensiometer. As PS with interfacial activity we have used propylene glycol alginates (PGA). To evaluate the effect of the degree of PGA esterification and viscosity, different commercial samples were studied. Xanthan gum (X) and X-carrageenan (X-c) were studied as nonsurface active polysaccharides. 

NMR is the most powerful technique available to identify the type of carrageenan, but it requires the purification of the samples, preferably under the sodium salt form, to be sure that the polymer is in the coiled conformation in dilute solution, even at ambient temperature. This technique also gives rapid access to the quantitative determination of the different substituents, if any, and to get information on the purity of the sample tested. This point is important because the chemical structure directly controls the physical propariies of the polysaccharide. 

---