Purification,Depolymerization And Identification Of Proanthocyanidin From Grape Seed

China is a big grape producing country with abundant grape resources.90% of the grape production is used for making wine and juice.As a result,2,500 tons of by-product grape seed is produced every year.Grape seeds are only used as fertilizer or waste and cannot be fully utilized,resulting in waste resources and environmental pollution.Grape seeds contain about 4% proanthocyanidins,which can be turned waste into treasure if fully utilized.The activity of antioxidant and anti-glycation of proanthocyanidins decrease with the increase of polymerization degree.Unfortunately,the proportion of oligomers in natural proanthocyanidins is very low,so the degradation of oligomers into oligomers has great economic and social benefits.At present,the research on acid degradation and hydrogenation cata lytic degradation is relatively mature.On the contrary,there are few studies on the two fields of alkali degradation and microbial degradation.Based on the research background mentioned above,the grap e seed proanthocyanidins were used as the research object,and the crude extracts were purified by macroporous adsorption resin AB-8 and Sephadex LH-20 to improve the purity greatly.The standard substance and crude extract of procyanidins were qualitatively analyzed by liquid chromatography.The degradation of high polymer was carried out by two methods: alkali degradation and microbial degradation.Finally,the antioxidant activity of the samples was analyzed.The main contents are as follows:Firstly,the extraction conditions were optimized: when 60% ethanol extractant,extraction time was 90 min,temperature was 70 °C,and material ratio was 1:3,the extraction rate of proanthocyanidins was 9.2%.The use of macroporous adsorption resin AB-8 to remove some impurities such as sugar and protein,resulting in a rise in purity from 41.62% to 77.34%.Then after further purification with Sephadex LH-20,the concentration of the eluent reached 90.52%,that is,the purity was greatly improved.When it comes to degradation,Li OH is selected as a degradation reagent according to the principle of alkali degradation.And its degradation conditions were optimized: 1.5 M lye concentration,degradation time was 30 min,and temperature was 70 °C.After scanning the Li OH degradation products by Fourier transform infrared spectroscopy,it is found that the characteristic peaks in the figure correspond very closely to the oligomers.It shows that the chemical bonds and some functional groups have not changed significantly,and the intramolecular structure has not been destroyed.It shows that the degradation with Li OH works we ll.Three strains of domesticated strains were domesticated by cultivating larch topsoil and grape mildew.It was identified as Aspergillus niger by molecular biological identification and morphological observation.The average degree of polymerization and HPLC results showed significant degradation,when XT-7 was selected for degradation.Anti-oxidation activity was detected by DPPH method and ABTS method,and the results showed that proanthocyanidins were stronger than ascorbic acid.Analysis of the Li OH degradation product showed that the antioxidant activity increased as the degree of polymerization decreased.