Hydrolysis Process Of Procyanidolic Polymers

This paper has introduced the knowledge of proanthocyanidins from grape seeds about the structure, physicochemical properties, pharmacological effects, various kinds of analytical methods and the technology of the extraction and the purification. By hydrolyzing of the procyanidolic polymers produced in the purification process from grape seeds, the hydrolysis process was established. There kinds of acids were chosen and three hydrolysis conditions were studied: volume ratio, temperature and hydrolysis time. With the average degree of polymerization and the peroxide value as parameters, the optimal hydrolysis conditions are as followed: resin â…  is the best medium for hydrolyzing, volume ratio of polymers aqueous solution and resin â…  is 1:1, temperature 70℃, hydrolysis time is 120min. Under this condition, the average degree of polymerization was reduced to 2.30 from 6.26.A modified vanillin assay was developed for estimation of the average degree of polymerization (DP) of proanthocyanidins from grape seeds. For the conventional vanillin assay, methanol is the solvent of choice for determination of proanthocyanidins content. On the other hand, when the reaction is carried out in glacial acetic acid, only the terminal flvan-3-ol unit reacts with vanillin and thus measures the concentration of proanthocyanidins mole. By using of these two reactions, the DP of proanthocyanidins can be determined. The liner range of determining the mole is 0.028-0.345 μmol/mL and the detection limit is 2.97 × 10^-4 μmol/mL, respectively. The recovery is 95.2-99.6% and the relative standard deviation is 0.78%-0.98%. The method is easy, fast, sensitive and has been applied to the samples and the results agree well with literature values.Another method has been established for the identification of oligomers in grape seeds using HPLC-MS. The purified proanthocyanidins, which were extracted from grape seeds by 60% ethanol in water, were eluted by gradient CH₃CN-1%CH₃COOH in H₂O from ZORBAX SB-C₁₈ column. Mass detection was performed in the negative ion mode. According to the mass of charged quasi-molecular ion [M-H]^-, three monomers, eight dimers, four monogalloylated dimers and four trimers were identified.