利用醇析法制備柚子果膠Preparationofpomelopectinbyalcoholprecipitation利用醇析法制備柚子果膠課程導(dǎo)入柚子是我國重要的水果，主要產(chǎn)于我國長江以南，2019年我國柚子產(chǎn)量為480萬噸，其中柚子皮占總重的30％-50％利用醇析法從柚子皮中制備果膠PreparationofpomelopectinbyalcoholprecipitationCourseimportGrapefruitisanimportantfruitinChina,mainlyproducedinthesouthoftheYangtzeRiver.In2019,theoutputofgrapefruitinChinawas4.8milliontons,ofwhichthegrapefruitpeelaccountedfor30%-50%ofthetotalweight.Pectinwaspreparedfromgrapefruitpeelbyalcoholprecipitationmethod目錄/CONTENTS1原料與試劑準(zhǔn)備

Preparationofrawmaterialsandreagents

操作方法

Operationmethod23注意事項Mattersneedingattention4設(shè)備與用具準(zhǔn)備

Preparationofequipmentandappliances

PART01原料與試劑準(zhǔn)備Preparationofrawmaterialsandreagents

一、原料與試劑準(zhǔn)備原料新鮮柚子皮或干柚子皮。試劑95%乙醇無水乙醇0.2mol/L鹽酸溶液6mol/L氨水活性炭1、PreparationofrawmaterialsandreagentsrawmaterialFreshordriedpomelopeel.reagent95%ethanolAbsoluteethanol0.2mol/lhydrochloricacidsolution6mol/lammoniawateractivatedcarbonPART02設(shè)備與用具準(zhǔn)備Preparationofequipmentandappliances

二、設(shè)備與用具準(zhǔn)備設(shè)備與用具準(zhǔn)備恒溫水浴鍋、玻璃棒、紗布、表面皿、精密pH試紙、燒杯、電子天平等。2、PreparationofequipmentandappliancesPreparationofequipmentandappliancesThermostaticwaterbath,glassrod,yarnCloth,surfacedish,precisionpHtestpaperBeaker,electronicbalance,etc.PART03操作方法Operationmethod三、操作方法（一）操作流程（二）操作要點稱取新鮮果皮50g（干品為20g），清水漂洗干凈（以去除泥土雜質(zhì)和農(nóng)藥化肥），放于250mL燒杯中，加水200mL，水浴加熱至90℃保溫5~10min，去除色素和酶。1.殺酶

乙醇沉析法制備柑橘果膠操作流程3、Operationmethod（1）Operationprocess（2）KeypointsofoperationWeigh50goffreshpeel(20gofdryproduct),rinseitwithcleanwater(toremovesoilimpuritiesandpesticidesandfertilizers),putitina250mlbeaker,add200mlofwater,heatitinawaterbathto90℃andkeepitwarmfor5~10mintoremovepigmentsandenzymes.1.enzymekillingPreparationofcitruspectinbyethanolprecipitationprocess2

.漂洗用水沖洗后切成1cm尺寸小塊于250mL燒杯，用50℃左右的熱水漂洗，大約10次左右直至水為無色，果皮無異味為止。每次漂洗都要把果皮用尼龍布擠干，再進行下一次漂洗。3.酸法萃取4.脫色濾液中加入0.5%~1%的活性炭，加熱至80℃，脫色20min，趁熱抽濾（如橘皮漂洗干凈，濾液清澈，可不脫色）。將處理過的果皮塊放入燒杯中，加入酸化水（約50mL0.2mol/L鹽酸加入250mL水，pH為2.0）恰好浸沒果皮為度，再次用鹽酸調(diào)節(jié)溶液在pH2.0~2.5之間。80～85℃恒溫水浴，保溫40min，保溫期間需不斷地攪動，趁熱過濾，若果皮渣過濾困難，可先用四層紗布粗濾一次，再用墊有尼龍布（100目）的布氏漏斗抽濾，收集濾液。2.rinsingAfterwashingwithwater,cutinto1cmsmallpiecesina250mlbeaker,rinsewithhotwateratabout50℃forabout10timesuntilthewateriscolorlessandthepeelhasnoodor.Thepeelshouldbesqueezeddrywithnylonclothforeachrinsing,andthenthenextrinsing.3.acidextraction4.decolorizationAdd0.5%~1%activatedcarbontothefiltrate,heatitto80℃,decolorizeitfor20min,andpumpitwhileitishot(iftheorangepeelisrinsedclean,thefiltrateisclear,butitcannotbedecolorized).Putthetreatedpeelintoabeaker,addacidifiedwater(about50mlof0.2mol/lhydrochloricacidinto250mlofwater,pH2.0)tojustsubmergethepeel,andthenadjustthesolutiontopH2.0~2.5withhydrochloricacid.Aconstanttemperaturewaterbathat80～85℃for40min.duringtheinsulationperiod,itneedstobeconstantlystirredandfilteredwhilehot.Ifitisdifficulttofilterthepeelresidue,itcanberoughlyfilteredoncewithfourlayersofgauze,andthenfilteredwithaBuchnerfunnelpaddedwithnyloncloth(100mesh)tocollectthefiltrate.5.醇析濾液冷卻后，用6mol/L氨水調(diào)至pH3~4，在不斷攪拌下緩緩地加入95%乙醇溶液，加入乙醇的量為原濾液體積的1.5倍（使其中乙醇的質(zhì)量分數(shù)達60%左右）。加入乙醇過程中可看到絮狀果膠物質(zhì)析出，靜置20min后讓果膠沉淀完全，用尼龍布（100目）過濾制得濕果膠。6.干燥將濕果膠轉(zhuǎn)移于100mL燒杯中，加入30~50mL無水乙醇洗滌濕果膠，再用尼龍布過濾、擠壓。將脫水的果膠置于已稱中的表面皿中攤開，水浴加熱或在烘箱40~50℃烘干。將烘干的果膠磨碎過篩，制得干果膠。5.alcoholprecipitationAfterthefiltrateiscooled,adjustittopH3~4with6mol/lammoniawater,slowlyadd95%ethanolsolutionunderconstantstirring,andtheamountofethanoladdedis1.5timesthevolumeoftheoriginalfiltrate(makingthemassfractionofethanolreachabout60%).Duringtheprocessofaddingethanol,theflocculentpectinmaterialcanbeseentoprecipitate.Afterstandingfor20min,letthepectinprecipitatecompletely,andfilterwithnyloncloth(100mesh)toobtainwetpectin.6.dryingTransferthewetpectinintoa100mlbeaker,add30~50mlabsoluteethanoltowashthewetpectin,andthenfilterandextrudeitwithnyloncloth.Thedehydratedpectinisspreadoutinaweighedsurfacedish,heatedinawaterbathordriedinanovenat40~50℃.Thedriedpectinisgrindedandsievedtoobtaindrypectin.課程小結(jié)0102殺酶步驟中水浴溫度必須為90℃，以將果皮中果膠酶滅活，防止果膠發(fā)生酶解。漂洗的目的是去除色素，以免影響果膠的色澤和質(zhì)量，因此漂洗必須徹底。03在實際生產(chǎn)中，提取溫度、時間和pH等條件應(yīng)控制好，以提高果膠收率和質(zhì)量。利用醇析法制備柚子果膠Coursesummary0102Intheenzymekillingstep,thewaterbathtemperaturemustbe90℃inordertoinactivatepectinaseinthepeelandpreventenzymatichydrolysisofpectin.Thepurposeofrinsingistoremovethepigmentsoasnottoaffectthecolorandqu