Apple Pectin Behavior Separated by Ultrafiltration

Separation conditions of ultrafiltration for apple pectin, and relations between apple pectin with different relative molecular weights and their structures and properties are studied. Five kinds of ultrafiltration membranes with different molecular weight cut-offs are used to separate apple pectin. FT-IR and HPGC are used individually to determine the structures and monosaccharide composition of apple pectin with different relative molecular weights. In the case of transmembrane pressure difference of 0.08 MPa, material concentration of 1 g L−1, and temperature of 50°C, 6 kinds of apple pectins with different molecular weights have been obtained. Molecular weight of apple pectin is correspondingly related to its physicochemical properties. The galacturonic acid contents and esterification and gelatination degrees increase relatively with an increase in molecular weight, and the monosaccharide composition relatively increase much more. And at the same time, the ultrafiltration has a better role to play in decoloring apple pectin solution. Accordingly, this research can be used as a new method for in-depth exploration of apple pectin.