Study On The Extraction,Purification,Stability And Antioxidant Activity Of Anthocyanin From Zijuan Tea

Using Zijuan tea as raw material in this paper.In order to provide a reference for the further development and comprehensive utilization of anthocyanins from Zijuan tea,the extraction process,separation and purification,component structure,stability and antioxidant activity of anthocyanins were studied.The results of the study were summarized as follows:1.On the basis of the results of the single factor test,optimizing the ultrasound assisted extraction parameters of anthocyanins from Zijuan tea by using L₁₆(4⁵)orthogonal array design.The results showed that all the effects of various factors on anthocyanins extraction reached extremely significant level.The effect order:solid-liquid ratio>extraction temperature>extraction time>ethanol concentration>hydrochloric acid concentration.The largest contribution rate on the extraction of anthocyanin was hydrochloric acid concentration,followed by solid-liquid ratio,extraction time,temperature,ethanol concentration.The best extraction process was as follows:90%ethanol solution with 2%hydrochloric acid,1:30(g/m L)of the ratio of solid-liquid,60?of extraction temperature,and extracting for 40 min,and the yield of anthocyanins was 997.72 mg/100 g.2.The crude extract of anthocyanins(anthocyanins I)from Zijuan tea was separated and purified,and the structure of its fractions was preliminary studied.The results of static adsorption and desorption of AB-8 macroporous adsorption resin showed that:the saturated adsorption capacity of AB-8 macroporous adsorption resin on the anthocyanins from Zijuan tea was 4.018 mg/g,the optimum adsorption temperature was 30?,the saturated adsorption time was 10 h;the best desorption solution was 80%ethanol solution with 4%hydrochloric acid,desorption complete time was 10 h.The crude extract of anthocyanins from Zijuan tea was extracted by chloroform and ethyl acetate to remove the impurity,then adsorbed by macroporous adsorption resin on the basis of static adsorption and desorption test,successively,30%,50%and 80%ethanol containing 4%hydrochloric acid were used as eluent for dynamic elution,and the elution fractions of 50%ethanol containing 4%hydrochloric acid were further purified by Sephadex LH-20 column chromatography to obtain anthocyanin II.The structure of the anthocyanin II fraction was preliminarily speculated by HPLC-MS,and the fraction may be Cyanidin with acetic acid and Peonidin with ferulic acid.3.The stability of anthocyanins before and after purification from Zijuan tea was studied.The results indicated that the p H value had significant affects on the color and absorption spectra of anthocyanin solution before and after purification;with the increase of temperature and prolongation of storing time prolonged,the preservation rate of anthocyanins I and II gradually decreased.The light,oxidant,reductant and metal ions(Fe³⁺,Cu²⁺,Mg²⁺,Ca²⁺,Al³⁺)also significantly affected the stability of anthocyanins,and the longer light time,the higher the concentration of H₂O₂and Na₂SO₃and the longer storing time,the lower the preservation rate of anthocyanins I and II;in addition,the oxidation resistance of anthocyanin II was slightly stronger than anthocyanin I in short time,but its stability was weaker than anthocyanin I under other same treatments.The stability of anthocyanins I and II from Zijuan tea were poor,and they should be preserved at acid condition and low temperature without light,and avoid contacting the oxidizing and reducing substances and iron or copper utensils.4.The antioxidant activity of anthocyanins before and after purification from Zijuan Tea was studied.The results showed that the total antioxidant capacity,ABTS⁺·radical scavenging capacity and DPPH·radical scavenging capacity of anthocyanins II were stronger than those of anthocyanins I,it indicated that purification can improve the antioxidant activity of anthocyanins,and the antioxidant activities of them were both significantly stronger than those of Vc.The DPPH·radical scavenging capacity of anthocyanins II was stronger than TP(Purity of more than 98%),but the ABTS⁺·radical scavenging capacity of it was weaker than TP.When the concentration was higher than20.3 g/m L,the total antioxidant capacity of anthocyanins II was stronger than TP,it illustrated that the anthocyanins II solution has strong antioxidant activity at relatively high concentration,and it can be comparable to the high purity TP solution.Compared with four varieties of tea,the total antioxidant capacity,ABTS⁺·radical scavenging capacity and DPPH·radical scavenging capacity of Zijuan tea soup were significantly stronger than Fu Yun 6,Fu Ding variety,Tie Guanyin tea and so on,the content of anthocyanin and TP in Zijuan tea were significantly higher than those of other four varieties,the results indicated that anthocyanins and TP were the main components of antioxidant activities of tea.