Preparation and Structural Characterization of Water-soluble Polysaccharide from Garlic Skin

A water-soluble polysaccharide from garlic skin (GSWSP) was extracted and purified by sequential water extraction and alcohol precipitation, DEAE-52 cellulose chromatography and Sephadex G-100 gel chromatography, and its primary, spatial, and mesoscopic structure of GSWSP were analyzed using chromatography, spectroscopy, and scanning electron microscopy (SEM). The results showed that the molecular mass of GSWSP was 2969 Da, which was composed of fructose, glucose, galacturonic acid, galactose, mannose, arabinose and rhamnose with a molar ratio of 81.8:17.6:15.6:14.5:6.5:4.2:1. Six sugar residues, →1)-β-D-Fruf-(2→; →1,6)-β-D-Fruf-(2→; →6)-β-D-Fruf-(2→; β-D-Fruf-(2→; α-D-Glc-(1→; and β-D-Gal-(1→, and three groups, β-D-GalA, α-D-Man and α-D-Ara, were found in GSWSP. GSWSP exhibited a three-strand helical structure in solution. Its solid powder existed in a crystalline state. Spherical conformation of GSWSP was observed under atomic force microscope, and it showed an irregular broken lumpy structure as observed under SEM. In summary, GSWSP can be used as a homogeneous polyfructan in foods and cosmetics.