Optimized Isolation and Characterization of the Major Polysaccharide from Grape Pomace

Grape pomace is the major component in grape fruits and is mostly wasted after wine and juice making processes. To recycle the residual biomass in grape pomace, extraction conditions of polysaccharides from grape pomace (GPP) were investigated. Three parameters affecting the crude GPP extraction, material to solvent ratio, extraction time, and extraction temperature were determined through single parameter optimization and then further optimized by orthogonal test. Results showed that the optimum extraction conditions were material to solvent ratio of 1:25, extraction temperature of 75 °C, and extraction time of 40 min, with extraction time as the most significant factor among them. Crude GPP was purified by gel column chromatography and chemically characterized. UV-Vis spectra analysis indicated that the GPP fraction did not contain any proteins or nucleic acids. FT-IR analysis implied that GPP consisted of α- and β-pyranose with carboxyl groups. Monosaccharide composition analysis indicated that GPP was composed of arabinose, glucose, galactose, and mannose with a molar ratio of 18.4:14.1:10.8:3.0. These results provide a theoretic basis for the production and utilization of GPP.