Studies On Extraction, Purification, Separation And Antioxidant Activity Of Tannin From Cinnamon

In this thesis, we have studied the analysis methods, extraction, purification, separation and the antioxidant activity of cinnamon tannin with cinnamon as raw materials. The main research contents and results were as follows:(1) The quantitative analysis method of cinnamon total phenols with the Folin-Denis method was improved, and the quantitative analysis method of cinnamon tannins with the vanillin-sulfuric acid method were built.The proper reaction conditions of Folin-Denis method were as the following:lmL of the Folin-Denis reagent,2.0mL of the0.01mol·L-1EDTA solution and2.5mL of the1mol·L-1NaOH solution were successively added into2mL sample solution. Then, added distilled water into the system until25mL, mixed the solution and placed20minutes. Finally, measured the absorbance at720nm, with tannic acid as the standard sample, the absorbance had good linear relationship with the concentration of tannic acid, the regression equation was A=22.0571c+0.0094(R2=0.9978). The results of stability and precision and accuracy were respectively as following:RSD=0.82%(20～40min)、RSD=1.12%、RSD=2.31%(the average recovery was101.05%).The proper reaction conditions of the vanillin-sulfuric acid method were: 2.5mL of30g·L-1vanillin solution in methanol, and2.5mL of30%H2SO4solution in methanol were successively added into0.5mL sample solution, and the reaction was carried out at30℃for20min. Then measured the absorbance of the system at500nm, with catechins as the standard sample, the absorbance had good linear relationship with the concentration of catechins, the regression equation was,A=3.0153c+0.0050(R2=0.9997). The results of stability and precision and accuracy respectively were as following:RSD=0.68%(15～50min)、RSD=0.58%、RSD=1.40%(the average recovery was101.95%).(2) The extraction process of cinnamon tannins were studied respectively with the methods of ultrasonic-assistant extraction and solvent extraction. By the single factor and the orthogonal experiments, we optimized the extraction conditions of tannins. The optimal conditions of tannin that extracted from cinnamon by using solvent extraction were as follows:material/liquid ratio1:30(g·mL-1), ethanol concentration60%, extraction temperature70℃and extraction time2.5h. With the optimal conditions, the yield of tannin from cinnamon reached42.35mg·g-1. By using ultrasonic-assistant extraction, the optimal conditions of tannin that extracted from cinnamon were as follows: material/liquid ratio1:20(g·mL-1), extraction temperature40℃, extraction time40min, ultrasonic power360w and ethanol concentration50%. Under the optimal conditions, the yield of tannin from cinnamon reached41.28mg·g-1. Ultrasonic-Assisted extraction was more suitable for the industrial production of cinnamon tannins, for its efficient and energy saving. (3) The methods of solvent extraction and macroreticular resins were used to separate and purify the crude extract of cinnamon tannins. The tannins contents in the samples that be separated and purified with the solvent extraction method respectively were:crude extract151.0mg·g-1, preliminary removed impurities sample148.9mg·g-1, ethyl acetate extraction169.8mg·g-1and residual water sample127.4mg·g-1. The static adsorption and desorption of four kinds of macroporous adsorption resin were investigated, of which, the adsorption and desorption effects of AB-8was better, and the static adsorption and desorption balance time of it were6h and2h. The optimal adsorption and desorption conditions were as follows:pH value of sample solution4.0, concentration of sample solution1.2mg·mL-1, feeding speed of sample solution1.0mL·min-1, eluent ethanol concentration80%, eluent feeding speed2.0mL·min-1, after purification, the purity of cinnamon tannins was from15.1%rise to29.65%.(4) The antioxidant activity of cinnamon tannins crude extract, ethyl acetate extraction and resin purification were studied. Results showed that the samples represented strong scavenging capacities towards hydroxyl radical and1,1-Diphenyl-2-picrylhy-drazyl (DPPH) radical, and within a certain concentration range, these scavenging effects enhanced with the increasing of concentration beyond this range, the scavenging rate remain unchanged. In general, the cinnamon tannins samples showed excellent DPPH radical scavenging activity. The scavenging rates of the cinnamon tannins samples were about90%when the cocentration reached to0.04mg·mL-1, and the scavenging activity of cinnamon tannins samples were stronger than ascorbic acid, especially, when the cocentration was less than or equal to0.03mg·mL-1, the antioxidant activities were more than2times more effective than that of ascorbic acid. In addition, within the test concentration(0.1mg·mL-1～0.6mg·mL-1), the maximum scavenging rates of the cinnamon tannins samples had reached to morethan60%,which were slightly lower than ascorbic acid(83.21%). The orders that the cinnamon tannins samples scavenged the DPPH and hydroxyl radical activity were no difference, was:ethyl acetate extraction> resin purification> crude extractings.