Abstract:The modification of extractant type on the structure and morphology of sugar beet pectin was studied in this study. Sugar beet pectin showed a compact texture and the appearance was made up of irregularly folding architecture. After treatment with the oxalate ammonia (80 ℃, pH 5.2, twice), the calcium content in the sugar beet pulp decreased from 1.28% to 0.81%; the morphology of the sugar beet pulp changed into a highly loose and polyporous texture., while the major functional groups and the crystallinity of the sugar beet pulp did not change. After the heat-acid treatment (80 ℃, pH 1.5), the protopectin located in the pulp was gradually converted into soluble pectin. Meanwhile, the spectroscopic characteristics of FTIR and XRD changed accordingly; the absorption band of FTIR at 2930 cm-1 became stronger and the relative crystallinity increased to a higher level. The Yield of the pectins solubilized in oxalate ammonia was 2.6%, while that of the acid-soluble pectin reached to 13.1%. All pectin extracts were predominantly comprised of galacturonic acid and neutral sugars. The results obtained in this work showed that oxalate ammonia liberated some pectins from the cell wall by chelating intrinsic calcium ions, and decreased the compactness of the sugar beet pulp. The dilute acid leaded to a significant modification effect on the pulp because it not only solubilized both sugar beet pectins and calcium ions presented in the cell wall, but also improved significantly the relative crystallinity of the sugar beet pulp.
