Preparation Of Liposoluble Cochineal Dye And The Research Of Its Physicochemical Property

Cochineal dye was usually used as a superior natural colorant,and it had superior colorability and higher capacity to eliminate free radicals,so it was widely applied in food,pharmaceuticals and so on.However,cochineal dye was disadvantaged by some physicochemical characteristics,such as its poor liposolubility limits its application in liposoluble cosmetic and food additive and so on.At present,the study on cochineal dye were mainly focused on efficient extraction,refine and purification,analysis and determine,funtional application.Systematic reports on solubility problems of Cochineal dye in oil substances had not been seen yet.Therefore,modifying Cochineal dye by chemical method to improve its lipsolubility was of great significance in improving its development and usages.The main composition of Cochineal dye was carminic acid,of which each molecular of carminic acid contain eight hydroxy and one carboxyl.In this report,lauroyl chloride was used as modified reagent of molecular structure to react with the hydroxy of the molecular of carminic acid,the liposolubly long-chain alkyl group was introduced,producing the easter of cochineal laurate,which not merely maintain the superior colorability of cochineal dye,but also improve its liposolubility.In order to understand the physicochemical characteristics of liposoluble cochineal dye,the spectrum,pH,solubleness and color value of the easter of cochineal laurate were also tested,as well as the influence of light,temperature,acidity and alkalinity,peroxide and reductor,common metals ions,usual food additives on its stability,which provide theoretical basis for objectively estimating the practical applicability of liposoluble cochineal dye.What's more,system of lipid and free radical were adapted to estimate the antioxidation and the free radical scavenging capacity of Liposoluble cochineal dye,providing essential data for the further development and utilization of liposoluble cochineal dye.Results indicated that:?1?Through single factor and optimization and verification experiments,the optimum manufacturing conditions for preperating liposoluble cochineal dye were determined as follows:the reaction time 1 h;the temperature 42?;lauroyl chloride/DMF/cochineal dye 4.5g:15.3mL:1.00g.Under such circumstance,the recovery of cochineal dye was 59.35%.The structure of liposoluble cochineal dye was characterized by FITR,UV-Vis.Results indicated that the esterification were taken place between cochineal dye ang lauroyl chloride,cochineal laurate was obtained.It was soluble in edible corn oil and its stability was well,its solubility was 15.06g?20??,and its clarity and transparency were well.?2?The pH and color value of liposoluble cochineal dye was 5.5 and 19.15 respectively,,when its concentration was 1?g/mL.And it was soluble well in ethanol,ethyl acetate,diethyl ether,acetone,acetic acid;and it was sparing soluble in chloroform,toluene,benzene;but it was undissolved in water,petroluem ether,normal hexane,glycerol.It was found that liposoluble cochineal dye was stable to not only light,temperature,but also acid and oxidizing agent,while its preservation was reduced under alkalinity condition and its preservation rate declines slightly due to reducer.Except Fe²⁺?Cu²⁺?Mn²⁺and Zn²⁺,the stability of liposoluble cochineal dye was not interrupeted by other metal ions.To a certain extent,common food additives had grace color effects on liposoluble cochineal dye.?3?Liposoluble cochineal dye had an certain oxidation resistents effect to lipid,and at the pigment concentration of liposoluble cochineal was 0.03%and 0.01%exhibits to the greatest antioxidant effect for lard and edible corn oil.Ascorbic acid,citric acid,tartaric acid had coordination oxidation resistents effect to the inoxidizability of liposoluble cochineal dye,but the oil oxidation resistents of liposoluble cochineal dye was inferior to TBHQ,BHT,BHA.?4?Liposoluble cochineal dye could scaveng DPPH·,ABTS⁺·and O₂^-radical to a certain extent,and it had better capacity to remove DPPH·,ABTS⁺·than O₂^-.