Composition of carrageenan blends inferred from C-NMR and infrared spectroscopic analysis

Carrageenan blends mainly composed of kappa, iota and lambda carrageenan were investigated by ¹³C-NMR and infrared (IR) spectroscopy. ¹³C-NMR was shown to be a powerful tool for quantifying the kappa-iota ratio in a carrageenan blend. The technique, however, was not helpful for identifying lambda carrageenan. Consequently, IR spectroscopy was used to achieve a semi-quantitative determination of lambda carrageenan. By combining both techniques, the carrageenan composition of several commercial samples was established.