Study On Extraction And Separation Of Anthocyanins From "Zijuai" Tea And Their Antioxidant Activity

“Zijuan” is one of the specific tea germplasm in Yunnan Province, with the purple bud,purple leaves and purple stems, and the dried Hongqing green tea and the tea soup are purple. Inaddition, it is also found that “Zijuan” tea has a significant blood pressure lowering andanti-allergy effect. The existing studies have shown that anthocyanins are the main characteristicscomponents of “Zijuan” tea, which have strong research significance and development value.Therefore, how to exploit the anthocyanins in “Zijuan” tea has caused great concern.In this study, the total amount and composition of the anthocyaninis in “Zijuan” tea havebeen analysed,the extraction process of anthocyanins with acidic methanol and distilled waterwere optimized by using response surface method, and the orthogonal experimental method,respectively; Finally, the anthocyanins were preliminary separated and purified by using theXAD-7column chromatography, and their antioxidant activity were determined. The mainfindings are as follows:1. The total amount of anthocyanins in Hongqing green tea of “Zijuan” was22.0mg/g, about10times that of ordinary green tea. The main composition anthocyanins in “Zijuan” tea werePelargonidin3,5-diglucoside, Cyanidin3-O-galactoside, Pelargonidin and Malvidin. Theircontent was227,83.5,46.3,70.5μg/g, respectively.2. By using the single factor and orthogonal experiments, effects of the extractiontemperature, extraction time and material-liquid on the water extraction of anthocyanins from“Zijuan” tea were investigated; On this basis, the relationship between the concentration of theextracts and color were analysed. The result showed that among the three factors, the temperaturehad the highest effect on the extraction of anthocyanin from “Zijuan” tea, while the extractiontime had the lowest effect. The optimum conditions were reaction temperature80℃, reactiontime20min, the material-liquid ratio1:15in water. The product was purple powder after dryness,and the tea soup showed the best color effects when its concentration was24mg/ml (L=70.32，a=7.31，b=8.52).3. Process extraction of anthocyanins from “Zijuan” tea was optimized by response surfacemethodology (RSM). Selected test factors and levels on the base of the single-factor test, analysisof the significance of each factor and their interaction by using three factors and three levels ofresponse surface analysis according to central composite (Box-Behnken) experimental designprinciples.The results showed that the optimum conditions for the extraction Zijuan teaanthocyanin were reaction temperature29℃, reaction time132min, the material-liquid ratio1:26in acidic methanol, under these conditions the concentration of anthocyanins in the extract can beachieved5.94mg/mL.4. The total antioxidant capacity (T-AOC) incapacity, scavenging rate of OH.and O2-,of thedifferent anthocyanin extracts from “Zijuan” tea were investigated. The results showed that theanthocyanins extracts and their column separation components have a high biological activity, their total antioxidant capacity were column separation components1> ethanol extract> waterextract> column separation components2>98%Tea Polyphenol (TP), their hydroxyl radicalscavenging rate were column separation components1> water extract> ethanol extract> columnseparation components2>98%TP, their superoxide anion radical scavenging rate were98%TP>water extract> column separation components1> column separation components2> ethanolextract.