Optimization of a method to extract polysaccharides from white grape pomace by-products.

The aim of this paper is to optimize a method to recover polysaccharides from white grape pomace (non-fermented), the main waste by-product of the food industry. Different conditions are tested and the polysaccharides extracted are analyzed by high performance size exclusion chromatography with refractive index detector (HPSEC-RID) and gas chromatography with mass detector (GC-MS). The extraction solvent did not show a significant effect on the polysaccharide extraction, acid pH yielded to higher efficiencies, and longer extraction times extracted more smaller polysaccharides (≤5.4 kg mol-1). The highest efficiencies were obtained with both solvents at pH 1 and 1:4 solid to liquid ratio. The optimum conditions selected (TA as solvent of extraction, 2.5 g L-1 solvent concentration, pH = 1, 1:4 solid to liquid ratio, and 18 h of extraction time) allow the extraction of polysaccharides rich in arabinose and galactose, rhamnogalacturonans, homogalacturonans and glucosyl polysaccharides, under efficient and food-safe conditions.