Improved size-exclusion high-performance liquid chromatographic method for the simple analysis of grape juice and wine polysaccharides

A size-exclusion HPLC method was developed for the separation and quantification of grape juice and wine polysaccharides. Polysaccharide extraction was carried out by precipitation and two chromatographic procedures were tested with the polysaccharide precipitate solution: direct injection, and fractionation of non-negatively charged (NCPS) and negatively charged (CPS) polysaccharides using an anion-exchange cartridge, before injection. The direct procedure (injection of the precipitate solution on two GPC columns and RI detection) was chosen, because the sum of areas of NCPS fractions represented 1.42% of the total area (sum of areas of NCPSs plus sum of areas of CPSs). The precision, linearity, sensitivity and accuracy of this method were established. Identification was performed by pectins and polyacrylic acids. The concentration of each polysaccharide identified according to the molecular mass was obtained by considering that the whole area (100%) contains the total number of polysaccharides determined by colorimetric method. Three polysaccharides were separated in grape juice (19 000; 2000 and 1000, approximately), whereas seven polysaccharides were obtained in wine (45 000; 19 000; 12 000; 7000; 4000; 2000 and 1000, approximately). (C) 1998 Elsevier Science B.V. All rights reserved.