Extraction,Purification And Monomer Preparation Of Anthocyanins From Daucus Carota Var. L

Black carrot contains a large number of anthocyanins.Extraction,resin purification,enhancing thermal stability methods and preparation of anthocyanin monomers were systematically studied.Firstly,black carrots were used as raw materials to compare the optimization conditions of different extraction methods for different enterprises.Then,based on the preliminary purification of crude extracts from 12 kinds of macroporous resins,three kinds of resins with better properties were pre-selected.Experimental study on adsorption isotherms and static adsorption/desorption kinetics was conducted.The thermal stability of black carrot pigment under sugar and acid additives was explored.Finally,monomer anthocyanin was prepared by combined column chromatography.The main research contents and results are as follows:In the research of black carrot extraction process,it is found that the optimum extraction pH of black carrot is 2.0;in the selection of extraction methods,it is recommended for enterprises with high processing capacity and high environmental protection requirement to choose citric acid press pressing method.To value-added products and environmentally-conscious companies,it was recommended accepting citric acid extraction method,and to small-scale enterprises that pay special attention to economics,it was recommended acid pickling method;in the continuous extraction of pigments,it is recommended to use industrial counter-extraction for multiple extractions.Moreover,the pressed twice can be adopted;in the exploration of the citric acid pressing conditions,according to the actual production economic considerations,it is recommended to use the aqueous solution as the extraction solution,the solid-liquid ratio is 1:1,added citric acid content was 3.0%.From twelve kinds of macroporous resins(BM2,HP-20,LS-305 A,LS-610 B,LS-305,LSA-5B,LSA-800,LSA-7,D101,LSA-40,BM3,AB-8),three macroporous resins(BM2,LS-610 B,BM3)were preselected for static adsorption/desorption experiments.The results show that the optimum pH of the crude solution was 2.0 for the adsorption by the three macroporous resin;the adsorption isotherms of BM2 and BM3 resin could fit the Langmuir model well,and the correlation coefficient was 0.9878 and 0.9662,respectively,which belonged to the monolayer adsorption mechanism.LS-610 B resin is well fitted to both the Langmuir model and the Freundlich model.The correlation coefficients were 0.9799 and 0.9740,respectively.The adsorption kinetics process of the three macroporous resins can be well described by the internal diffusion model of the first-order dynamic particles.The best conditions for the three macroporous resins in the desorption of pigments were 65% ethanol aqueous solution(containing 0.3% citric acid).In the study of the thermal stability of the additive to the black carrot pigment solution,it was found that the oxalic acid maintains the best stability of the color in the acidic additive,while the ascorbic acid has the worst effect and the heat of the color solution in the acid additive.Stability change data is suitable for expression by polynomial equation;the black carrot pigment solution has poor stability for a long time in the four sugar additives,but the stability of the pigment can be enhanced within 30 min before the addition of dextrin,and the effect is better than oxalic acid.Within 30 min,the thermal degradation kinetics of the pigment solution in the saccharide additive is suitable for both zero-order and first-order kinetics.The crude black carrot extract was subjected to ethyl acetate extraction,and then an anthocyanin monomer was prepared by a combination column chromatography.The crude black carrot extract had a purity of 9.34%,and after extraction,it became 14.10%,and the yield was 98.56%.After XAD-7HP resin,the anthocyanin purity increased to 42.27%,and the yield was 59.55%.After amide chromatography,the purity of anthocyanin was further increased to 77.69%,and the yield was 22.97%.Finally,two components were obtained by two ODS-AQ-HG columns.HPLC analysis showsthat component I was anthocyanin monomer,the yield was 96.25%.