Studies On Separation & Purification Of The Proanthocyanidins In Grape Seed Extract And Their Antioxidation

This thesis studied with the extraction crafts of the Oligomeric Proanthocyanidins(OPC's) from the red grape seeds in the XingTian wine factory of xingjiang. In this work, feasible qualitative and quantitative methods were established, and the procyanidins were fractionated according to their degree of polymerization(DP). The main results of this dissertation were described as following:The contents of OPC's were evaluated by spectrophotometric determination of the vanillin-vitriol acid methodIn The assay was then used to determine the procyanidin content of several kinds of grape seeds from different district and different fermentation process.Results showed that the procyanidin content of grape seed was affected by wine-making methods. Procyanidins should be extracted from unfermented grape seeds.The separation of OPC's by TLC was analyzed. Composing of each fraction and criterion product are identical.Adopt linoleic acid and pyrogallol autooxidation system were used for comparing the antioxidant activity of fractions with different DP obtained by fractionation. for comparing the antioxidant activity .As a whole, procyanidins exhibits higher antioxidant activity than Vc and VE in linoleic acid system. For O₂^-·radical,the strong scavenging ability of procyanidinsThe stability of proanthocyanidins was studied The results showed that proanthocyanidins were likely stable at low temperature and low pH. Among different mineral ions,Sn²⁺. Fe²⁺ and Cu²⁺ have significant influence on the stability of proanthocyanidins. The amount would decrease under the sunlight.The extraction and isolation of grape seed procyanidins were studied. By use of 70% ethanol as solvent with a flour-solvent ratio of 1:7(w/v) and extracted 3times at 40℃for 30 minutes, 40.21%of total procyanidins can be extracted from grape seeds. For isolation of grape seed procyanidins with ADS-8 resin. A product with procyanidin content above 95% can be obtained by isolation on ADS-8 resin. Furthermore, fractionation of procyanidins according to DP can also be performed on ADS-8 resin. By elution with increasing ethanol concentration, procyanidins were recovered according to increasing DP in sequence, fractions with relatively higher content of oligomeric procyanidins can be obtained from elute of low ethanol concentration. This procedure can be further applied to large-scale preparation.