Ultrasonically Assisted Extraction Of Proanthocyanidins From Grape Seeds

The extraction of proanthocyanidins from defatted grape seeds was studied using ultrasound as the assisted method at room temperature. The contents of proanthocyanidins were evaluated by spectrophotometric determination at 280 nm,550nm,respectively. It was found that sonication can enhance both solvent penetration into plant materials and the soluble constituents' release by disrupting cell walls. Hence extraction time was reduced and the process can be accomplished at a relatively lower temperature. By comparing the results from the products' high performance liquid chromatography and Infrared spectra with the control standard's,it was found that ultrasound had no visible influence on proanthocyanidins' structures and composition under the conditions of the experiment.The factors related to the extraction of proanthocyanidins at room temperature were discussed. During the extraction of grape seeds with moisture content of 14.1%,two extraction systems were investigated and the optimum solvent consentrations were 70% (v/v) for acetone-water mixture and 60% (v/v) for ethanol-water mixture. The extraction systems' selectivities on proanthocyanidins were compared and the acetone-water ( 70 :30 ) mixture has a higher ability over the ethanol-water ( 60 :40 ) mixture. The purity of four crude products was represented by the extraction ways as follows:( acetone-water system + ultrasound ) > ( acetone-water system ) > (ethanol-water system + ultrasound ) > ( ethanol-water system) and the purities were 43.32%,38.04%,35.16%,31.65% respectively. Ultrasonically assisted extraction of proanthocyanidins was proved a better way to improve the yield and purity of proanthocyanidins.