Study On Procyanidins Adsorption And Polymer Hydrolysis

Proanthocyanidins are a large type of natural polyphenol compound existing in plant kingdom widely.Proanthocyanidins considered as the most effective natural antioxidant with potent free radical scavenging activity have been widely used in medicine,health products,food,cosmetic and other fields.The antioxidant activity of proanthocyanidins largely depends on the degree of polymerization.Monomer antioxidant activity is inferior to dimer and polymer antioxidant activity reduces with the rise of degree of polymerization.Proanthocyanidins polymer(PPC)is difficult to be absorbed by human body.In this paper feasible methods to mensurate antioxidant activity of proanthocyanidins were determined.Theoretical model for the macroporous resin to adsorb procyanidins was studied.Proanthocyanidins were fractionated according to the degree of polymerization.PPC was hydrolysed to preparate proanthocyanidins oligomer(OPC)with high biological activity.The prussian blue method and salicylic acid method were the optimum ways superior to pyrogallol phenol method to mensurate the antioxidant activity of proanthocyanidins of different degree of polymerization because of their simple operation,fast,good repeatability and stability.Phase equilibrium equation and dynamic adsorption model of AB-8 macroporous resin adsorbing procyanidins were established.Overall mass transfer coefficient,mass transfer zone length and penetration time were calculated under different flow rate and feed concentration.The calculated value agreed with the experiment results.The proanthocyanidins adsorbed in the AB-8 resin were eluted gradiently by11%~41%and 60%ethanol and the eluting recovery achieved 98.63%.According to the average degree of polymerization and antioxidant activity of proanthocyanidins in each ethanol eluent,only monomer exists in 0~11%ethanol eluent,11%~31%eluent contained mainly OPC,31%~60%eluent contained PPC.The antioxidation activity of25%eluent was highest that its free radical scavenging rate was about 45%and V_C equivalent concentration was about 19%.The average degree of polymerization of procyanidins was reduced significantly and the antioxidant activity was improved after the proanthocyanidins polymer in eluent of33%,35%,37%,39%and 41%ethanol were hydrolysed.No byproduct was found in the hydrolysis products analyzed with spectrophotometry.The hydrolysis products were mainly OPC illustrated through fractionation.