Study On Extraction, Purification And Characteristic Of Anthocyanin From Black Radish

Black radish, belonging to the Cruciferous plants, is one of the radish varities and has along cultivation history, whose skin is black or purple and rich in nutrients includingcarotenoids, anthocyanins. It is one of the important resource of natural red pigment, whichhas high nutrional value and economic value. Recently, black radish is used as a traditionalcrop to plant in Turkey, Pakistan, India and other countries, which mainly processed intoanthocyanins or beverages sold in Europe and America and has a broad market. Althoughblack radish has a long cultivation history and a broad market, it is rarely known and seldomreported in China. In this research, the extraction technology and purification technology ofblack radish anthocyanins were studied. The components and characteristic of anthocyaninswere analysized. Hope this can provide theoretical basis and technical support for thedevelopment and utilization of black radish. The results as follows:Firstly, the effect of different extraction methods on yields of black radish anthocyaninwere analyzed and compared. Single factor tests and orthogonal design were conducted tooptimize the technique of dilute hydrochloric acid solution extraction method. The optimalextraction conditions were extraction temperature60℃, extraction time2.5h, liquid-solidratio4:1, pH2.0, and the yield of anthocyanin was1.704mg/g. The technique of ultrasonicassisted extraction method was optimized by using response surface methodology. Theoptimal process parameters were ultrasonic temperature58℃, pH2.4, liquid-solid ratio5:1,ultrasonic time30min, ultrasonic power373W, and the yield of anthocyanin was2.067mg/g.The anthocyanin yield of ultrasonic assisted extraction method is higher.Secondly, the effect of five macroporous resin varities on purification of black radishanthocyanin were analyzed and compared. The optimal static process parameters wereobtained by static adsorption and desorption tests, which included adsorption resin of LSA-10,adsorption time of21h and liquid-solid ratio of8:1. Under these conditions, the adsorptionrate and desorption rate were91.91%and95.66%, respectively. The optimal dynamic processparameters were obtained by dynamic adsorption and desorption tests, which included sample concentration of3.350g/L, flow rate for sample of2BV/h, an ethanol desorption solutionconcentration of70%(v/v) and flow rate for elution of1BV/h. The color value, anthocyanincontent, polyphenol content and flavonoids content of the purified anthocyanin product are108,258.2mg/g (Delphinidin Equivalent, DE),565.1mg/g (Gallic Acid Equivalent, GAE)and352.8mg/g (Rutin Equivalent, RE), respectively. The product contains five majorcompounds analyzed by high performance liquid chromatography (HPLC). Compared toother previous studies, we speculated that the compounds may be cyaniding-3-galactoside-xyloside-glucoside (Cyd-3-gal-xyl-glc), cyaniding-3-galactoside-xyloside (Cyd-3-gal-xyl),cyaniding-3-galactoside-xyloside-glucoside-sinapic acid (Cyd-3-gal-xyl-glc-sin), cyaniding-3-galactoside-xyloside-glucoside-ferulic acid (Cyd-3-gal-xyl-glc-fer) and cyaniding-3-galactoside-xyloside-glucoside-coumaric acid (Cyd-3-gal-xyl-glc-coum), respectively.Thirdly, the antioxidant capacity of black radish anthocyanin was determined by usingFRAP, DPPH and hydroxyl radical assay, which blueberry anthocyanin, BHT and Vc used aspositive control. Effects of some environmental factors and additives on the stability of blackradish anthocyanin also were determined. The result shows that the antioxidant capacity ofblack radish anthocyanin is stronger than blueberry anthocyanin and BHT with higher FRAPvalue (1178.63mmol Fe2+/100g product) and lower IC50value of scavenging DPPH andhydroxyl radicals (61.45mg/L and170.61mg/L). The conditions of lower temperature, darkand acidity (pH1-4) were helpful for the stable storage of black radish anthocyanin; Thedestructive effects of oxidant (H2O2) and reducing agent (ascorbic acid) to the stability ofBlack radish anthocyanins were enhanced with the increasing of time. The destructive effectsto the stability of black radish anthocyanins were enhanced with the increasing ofconcentrations of oxidant (H2O2) or reducing agent (ascorbic acid). The solution of Zn2+、Al3+、Ba2+、K+、Na+and Ca2+play smaller role in the degradation of Black radish anthocyanin,but Fe2+play greater role in this process.