FRACTIONATION, STRUCTURAL-ANALYSIS, AND RHEOLOGICAL PROPERTIES OF WATER-SOLUBLE YELLOW MUSTARD (SINAPIS-ALBA L) POLYSACCHARIDES

The water-soluble yellow mustard (Sinapis alba L.) Polysaccharides were separated into CTAB-precipitated and CTAB-soluble polysaccharide fractions by precipitation with 5% CTAB. Each of these materials was subsequently fractionated into five fractions by an ion-exchange (DEAE-cellulose) column eluted with a stepwise gradient of NaCl (0.1-1.0 M) in NaAc buffer (pH 5, 25 mM). Of the 10 subfractions obtained, 2 neutral polysaccharide fractions (WSCP-I, WSCS-I) and an acidic fraction (WSCP-III) were identified as the major components responsible for the pronounced shear thinning behavior of yellow mustard mucilage solutions. The WSCP-I and WSCS-I fractions were mainly composed of a 1,4-linked beta-D-glucan, although WSCP-1 appeared to be more heterogeneous than WSCS-I. The WSCP-III fraction consisted of nonreducing end glucuronic acid (13.3%), 1,4-linked galacturonic acid (13.6%), 1,6-linked galactose (22.9%), and 1,2-linked (11%) and 1,2,4-linked (17%) rhamnose. Gel filtration chromatography revealed differences in the molecular size of the constituent polysaccharides among the fractions.