Structural and Water-Holding Characteristics of Untreated and Ensiled Chicory Root Pulp

Cell wall polysaccharides (CWPs) from chicory root pulp (CRP) and the effect of ensiling on CWP structure to reduce the water-holding capacity (WHC) were studied. Sequential extractions of CRP showed that hot water extraction solubilized arabinan-rich pectin and inulin, each representing 6% of all CRP sugars. A significant amount of pectic sugars (46%) rich in uronic acid from CRP was solubilized by chelating agents. Both dilute alkali extraction, which solubilized branched pectin (14% from CRP), and concentrated alkali extraction, which solubilized hemicellulose dominant in xyloglucans (2.5%) mostly of the XXXG type and mannan (0.9%), from CRP CWPs seemed to influence the WHC of CRP. Alkali-insoluble residue (39% of CRP sugars) mainly comprised cellulose and some branched pectin (17% from CRP). Ensiling reduced the methyl esterification of pectin, caused degradation of homogalacturonan and rhamnogalacturonan, and possibly modified the xyloglucan, mannan, and glucan network, reducing the WHC from 6 mL/g to 3.4 mL/g.