4.2.3. Chemical Composition and FT-IR Analysis of Polysaccharide Fractions

Total carbohydrate levels in polysaccharide fractions were determined with a phenol-sulfuric acid assay. The contents of phenolic compounds and protein in all fractions were quantitatively determined using the Folin–Ciocalteu assay [92] and the Bradford protein assay [93], respectively.

The functional groups present in purified fractions were analyzed with Fourier transformed infrared spectroscopy (FT-IR, CREVM/QM03-010, Perkin-Elmer Corp., Waltham, MA, USA). Totals of 10 mg of each polysaccharide fraction and 200 mg of potassium bromide (KBr) were ground and dried under the baking lamp, and then pressed into a 1 mm pellet. KBr was used as a blank for infrared scanning in the range of 4000 cm⁻¹ to 500 cm⁻¹ (Perkin Elmer, Waltham, MA, USA).