Preparation, Separation Of Monascus Pigments And Structural Characterization Of Monascus Yellow Pigment

This research established the best extraction technology of monascus pigments by orthononal test, in which red yeast rice(powder) was used as the raw material and ethanol was used as the extractant. The best extraction technology is using the water solution of ethanol as solvent at the concentration of 60% to extract for 120min at 50℃and repeat it once. On this basis, tertiary countercurrent extraction technology of monascus pigments is established, by which monascus pigment with good stability is obtained. Color value of the monascus pigment powder is 10000u/g and the extraction rate could reach 66%. The solubility, coloring stability, stability to chemical reagent and common vector, thermal stability, photostability and antibacterial activity of the prepared monascus pigments podwer are researched by chemical experiment. We find the heat resistence of the monascus pigment is poor, as the temperature growing and the heating time extended the stability of the monascus pigment prone to be decreased, so we should make the monascus pigment avoid heating during storage, transportation and appliance. Indoor natural light can hardly effect the pigment, but the pigment would decrease color value severely when it is exposed in outdoor natural light, therefore the product should not be exposed in the direct natural light during package and storage for fear that it would decrease color value. Fe³⁺ and Ca²⁺ have a greater influence on the stability of pigment than other metal ion, therefore, the pigment should be prevented from contacting ironwork, Fe³⁺ and Ca²⁺ during storage, package and appliance.Silica column chromatography separation technology was used to elute and separate the prepared pigment powder, and petroleum ether: ethyl acetate(1:1,v/v) mixture, ethyl acetate, anhydrous methanol and distilled water are used as eluent, monascus yellow pigment, Monacolin K, alcohol-soluble monascus red pigment and water-soluble monascus red pigment were obtained. Yellow crystal, colorless needle -like crystal, alcohol-soluble red powder and water-soluble red powder are prepared by further purification of the above four components.Maximum absorption wavelength of the four components are determined by UV-VIS scanning.Maximum absorption peaks of monascus yellow pigment are in 366.0nm, 377.9nm and 388.0nm, maximum absorption peak of monacolin K is in 237nm, maximum absorption peaks of alcohlo-soluble monascus red pigment are in 506.1nm, 516.0nm and maximum absorption peak of water-soluble monascus red pigment is in 486.0nm.On the basis, color value of three kinds of pigment are determined, in which the result are respectively 8300 u/g, 10020 u/g and 8200 u/g。Subsequently monacolin K,the beneficial ingredient of monascus pigment extract and the other three components are quantitative detected by high performance liquid chromatograph, the result show the content of monacolin K in monascus pigment extract, monascus yellow pigment and alcohol-soluble monascus red pigment are respectively 11.38mg/Kg, 0.89mg/Kg, 0.06mg/Kg. And monacolin K is hardly found in water-soluble monascus pigment. Light color component is proved to be monacolin K by qualitative detection on the second light color component. Citrininin in four components are quantitative detected by high performance liquid chromatograph, the result show that trace citrininin existe in monascus pigment extract and monascus yellow pigment, there is no citrininin be found in the alcohol-soluble monascus red pigment and the water-soluble monascus red pigment.The monascus yellow pigment which is separated in silica gel column is further separated by high performance liquid chromatograph and four components are found. Retention time of the four components are respectively 0.97min,2.59min,3.17min,4.12min。The retention time interval is larger, collecting four components respectively. Molecular weight, molecular formula and structural formula of the four components are determined by HPLC-MS and MS and reference, in which the result are respectively C₂₃H₃₀O₅( 386),C₂₁H₂₆O₅( 358)and C₂₄H₃₆O₅( 405). Based on literatures reported, we confirm that the three components are respectively Ankaflavine, Monascine and Monacolin K。...