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2009届硕士学位论文摘要红曲色素(Monascuspigments)是红曲菌发酵生产的天然色素,为红、黄色调的多种单一色素的混合物,在肉品中代替硝酸盐类的应用研究日益受到关注。红曲色素对光照、高温、酸碱、重金属敏感,特别是在肉制品加工中经常因为高温杀菌处理而导致添加红曲色素的产品出现变色现象而影响产品质量。本文以红曲色素为研究对象,研究了光照、温度、pH、金属离子、加热时间以及贮藏方式等对红曲色素保存率和溶液色度的影响,建立了其热降解的动力学模型方程,通过薄层层析对红曲色素的主要组分进行分离,研究了红曲色素中红色组分RP3和黄色组分YPl的热降解特性,并建立了红曲色素热稳定性的评价体系。主要研究结果如下:l、研究了光照、温度、pH值、盐浓度和重金属离子等理化因素对红曲色素的稳定性的影响。在3种光照条件下,连续光照可显著降低红曲色素的保存率,而避光贮藏则可有效保护红曲色素。红曲色素在pH310范围内比较稳定,高于或低于该pH值范围其稳定性显著下降。重金属离子对色素溶液的呈色有影响,Cu2+、Fe3+会使色素溶液由亮红色变为褐色并产生沉淀。随着盐浓度的增大,红曲色素溶液的色度值下降。红曲色素在100以下较为稳定,在100以上时则随着加热温度的升高、加热时间的延长,色素保存率明显降低。红曲色素的热降解符合一级反应动力学方程。在加热过程中,红曲色素溶液的明度L随加热时间的延长而呈现下降趋势,且加热温度越高,下降越明显,而红曲色素溶液的红度则随着加热时间的延长逐渐下降、黄度增加,且加热温度越高这种变化趋势越明显。2、在红曲色素的贮藏过程中,不同温度加热后的红曲色素溶液在不同贮藏方式下的保存率和色度的变化趋势不同,避光组的保存率下降较慢,贮藏90天后保存率都高于85,而光照组的保存率降低较快,贮藏90天后保存率只有10左右。色素溶液的亮度随贮藏时间的延长而增大,红度、黄度和彩度随贮藏时间的延长而减小,光照贮藏比避光贮藏变化更快。3、对红曲色素各组分进行分离并研究了纯度较高的红色组分RP3、黄色组分YPl的热降解特性。用薄层层析法,以甲苯:乙酸乙酯:甲酸=7:3:1(vv)、正己烷:乙酸乙酯:石油醚=30:17:5(vv)为展开剂,从红曲色素中分离得到4种红色组分和3种黄色组分,经高效液相色谱鉴定,红色组分RP3、黄色组分YPl的纯度较高。经热降解特性研究表明,RP3比YPl的热稳定性差,121加热40min后,YPl的色素保存率为713,而RP3的保存率只有452,两种红曲色素热稳定性的研究组分的热降解符合一级反应动力学模型,其中红色组分RP3的活化能为773826KJmol,黄色组分YPl的活化能为875049KJmol。4、。维研究红曲色素浓度、加热温度、加热时间对特征吸收峰和吸光值的影响的基础上,建立了红曲色素热稳定性的评价方法。在热稳定性的测定中,选择初始吸光度为O45105,加热温度120,加热时间40min,可以客观反映出不同红曲色素在热处理过程中的稳定性差别。关键字:红曲色素稳定性保存率薄层层析分离热降解动力学II2009届硕士学位论文AbstractMonascuspigmentsarenaturalpigmentsfermentatedbyMonascussppTheyaremixtureofkindsofredandyellowsinglepigment,ApplicationofMonascuspigmentstoreplacenitratesinmeatisconcernedparticularlynowMonascuspigmentsissensitivetolighthightemperature,acid-baseandheavymetalions,especiallyinmanufacturingofmeatproducts,discolorationofmeatproductswhichaddedtoMonascmpigmentsinheatingprocesshavebadeffectoftheproductBasedonstudiesofthebasicphysicalandchemicaleffectsontheabsorbanceandcllromaofmonascnspigments,redpigmentsandyellowpigmentswereseparatedandpreparedbyTLCAfterpurityanalysisandpreliminarystructureidentificationthermaldegradationcharacteristicswerestudiedbetweenredpigmentsandyellowpigmentuationofmonascuspigmentsthermalstabilityWasestablished,thermalstabilityofredpigmentsRP3andyellowpigmentsYP1weredeterminedbythisThemainresearchresultswereasfollows1,Effectoflight,hightemperature,acidbase,saltconcentrationandheavymetalionsonstabilityofMonascnspigmentswerestudiedContinuousilluminationhadsignificanteffectsonstabilityofmonascuspigments,preservingratedecreasedsignificantlyincontinuousilluminationMonascuspigmentsWasstableinavoidlightsto略eUndertheconditionofpH3-10,thestabilityofthepigmentcouldmaintainHeavymetalionshadignificanteffectsonstabilityofmonascuspigments,PrecipitationappearedwhenthemonascuspigmentswerecoexistencedwiththeseheavymetalionssuchasCu2+,Fe3+CIlromadecreasedwiththeincreaseofsaltconcentrationmonascuspigmentshadagoodstabilityunder100C,whileaboveofthistemperature,stabilityofmonascuspigmentswereobviouslydecreasedwitlltheincreaseofheatingtemperatureandtimeThermaldegradationdynamicmodelofmonascuspigmentsWasestablishedItWasprovedthatitWasinaccordencewithfirstorderreactionkineticsInheatingprocess,LightnessofmonascuspigmentsWasincreased嘶mtheprolongationofheatingtime,andthehighertheheatingtemperatureWas,theloweroftheIII红曲色素热稳定性的研究decreasingAtthesametime,reddishnessofmonascuspigmentsWasalsodecreasedwiththeprolongationofheatingtime,andtheyellownesswereincreasedwiththeincreaseofheatingtemperature2、ChangingtrendofmonascmpigmentschromainstorageafterdifferenttemperatureheatingWasdifferentPreservingrateofmonascuspigmentsdecreasedrelativelyslowinavoidlightstorage,thepreservingratewasmorethan85percentsafter90daysstoragewhilethepreservingrateoflightstorageWasnomorethan10percentsLightnesswasincreasedwiththeprolongationofstoragetimeReddishnessandyellownessweredecreasedwiththeprolongationofstoragetimeStorageofilluminationhasapoorerstabilitythanavoidlightstorage3、TLCwasestablishedtoseparatefourredcomponentsandthreeyellowcomponentsfrommonascuspigments,toluene,ethylacetateandicacid(73:1,vv)wasusedtoseparateredcomponentswhilen-hexane,ethylacetateandpetroleumether(30:17:5,vv)WasusedtoseparateyellowcomponentsfrommonascuspigmentsRP3ofredcomponentsandYP1ofyellowcomponentswerepuritiedprovedbyHPLCAfterstudiedonthethermaldegradationcharacteristics,YP1SthermalstabilityWasbetterthanthatofRP37S,afterheating40minutesof121,preservingrateofYPlWas713,whilethatofRP3Wasonly452Thethermaldegradationkineticsofthesetwocomponentsaccordwithfirstorderreactionkineticsmodel,theactivationenemyofRP3andYPlwere773826KJmoland875049KJm014、Basedontheeffectofcharacteristicabsorptionpeakandabsorptionvalueinheatingtime、heatingtemperatureandconcentrationofmonascuspigments,uationofmonascuspigmentsthermalstabilitywasestablishedThetestingconditionWasrecommendedasabsorptionO46-105,heatingtemperature120,heatingtime40min,differenceofmonascuspigmentsthermalstabilitycouldbemeasuredbythisKeywords:Monascuspigments,Stability,Preservingrate,TLC,Separation,ThermaldegradationkineticsIV华中农业大学学位论文独创性声明及使用授权书学位论文元如需保密,解密时间年月日是否保密日独创性声明本人声明所呈交的论文是我个
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