2008-Optimisation of ultrasound-assisted extraction from wh

FoodChemistry

FoodChemistry106(2008)804–810

http://doc.guandang.net/locate/foodchem

Analytical,NutritionalandClinicalMethods

Optimisationofultrasound-assistedextractionofphenolic

compoundsfromwheatbran

JingWanga,*,BaoguoSuna,YanpingCaoa,YuanTiana,XuehongLib

a

CollegeofChemistryandEnvironmentEngineering,BeijingTechnologyandBusinessUniversity,11FuchengRoad,Beijing100037,PRChina

b

DepartmentofFoodandBioengineering,ZhengzhouUniversityofLightIndustry,5DongfengRoad,Zhengzhou450002,PRChina

Received18March2007;receivedinrevisedform2May2007;accepted27June2007

Abstract

Wheatbran,animportantby-productofthecerealindustry,isrichinpotentiallyhealth-promotingphenoliccompounds.Inthispaper,thephenolic

compoundsfromwheatbranwereextractedbyultrasound-assistedextractiontechnology.Theexperimentswerecar-riedoutaccordingtoa velevel,threevariablecentralcompositerotatabledesign(CCRD),andthebestpossiblecombinationofsolventconcentration,extractiontemperatureandextractiontimewiththeapplicationofultrasound,formaximumextractionofphenoliccom-poundsfromwheatbran,wasobtained,throughresponsesurfacemethodology(RSM).Theoptimumextractionconditionswereasfol-lows:ethanolconcentration,64%;extractiontemperature,60°C;andextractiontime,25min;andtheextractiontimewasthemostsigni cantparameterfortheprocess.Undertheabove-mentionedconditions,theexperimentaltotalphenoliccontentwas3.12mggallicacidequivalents/gofwheatbrantested,whichiswellmatchedwiththepredictedcontent.Ó2007ElsevierLtd.Allrightsreserved.

Keywords:Centralcompositerotatabledesign;Phenoliccompounds;Ultrasoundextraction;Wheatbran

1.Introduction

Grainscontainuniquephytochemicals.Epidemiologicalstudieshavestronglysuggestedthatdietsrichincerealsplayacrucialroleinthepreventionofchronicdiseases,suchascardiovasculardiseaseandcertaintypesofcancers(Aruoma,2003;Slavin,2000).Thebene cialhealthe ectsderivedfromtheintakeofdietsrichincerealshavemainlybeenascribedtodietary bre,ortosomeofthecompo-nentsassociatedwiththe bre,includingphenolicacids(Andreasen,Landbo,Christensen,Hansen,&Meyer,2001;Zhao,Egashira,&Sanada,2003).Itiswidelyacceptedthatphenoliccompounds,includingferulic,vanil-lic,p-coumaric,ca eic,andchlorogenicacids,arerichinthebranportionofcerealkernelsandmaycontributetothetotalantioxidantactivitiesofgrain(Baublis,Clydes-*

Correspondingauthor.Tel.:+861068985378;fax:+861068985456.E-mailaddress:jingw810@http://doc.guandang.net(J.Wang).

´nez-Tome´etal.,2004;Yudale,&Decker,2000;Mart

etal.,2002).Thesephenoliccompoundsexhibitinvitrochemoprotectiveandantioxidantproperties,andaresug-gestedtobemainlyresponsibleforthebene ciale ectsofadietrichincerealbran(Andreasen,Kroon,William-son,&Garcia-Conesa,2001).

Wheatbranisproducedworldwideinenormousquanti-ties,asanimportantby-productofthecerealindustry.Sev-eralinvestigationshavebeenconductedtoevaluatetheantioxidantpropertiesofwheatandwheat-basedcerealextracts(Yuetal.,2002).However,tothebestofourknowledge,thereislimitedliteratureone cientextractionofphenoliccompoundsfromwheatbran.Inordertoseekmoreenvironmentallyfriendlymethods,decreasethesol-ventconsumption,shortentheextractiontime,increasetheextractionyield,andenhancethequalityofextracts,variousnovelextractiontechniqueshavebeendevelopedfortheextractionofnutraceuticalsfromplants,includingultrasound-assistedextraction,supercritical uid

0308-8146/$-seefrontmatterÓ2007ElsevierLtd.Allrightsreserved.doi:10.1016/j.foodchem.2007.06.062

J.Wangetal./FoodChemistry106(2008)804–810805

extraction,microwave-assistedextraction,andacceleratedsolventextraction(Wang&Weller,2006).Amongthese,ultrasound-assistedextractionisaninexpensive,simpleande cientalternativetoconventionalextractiontech-niques.Theenhancementinextractionobtainedbyusingultrasoundismainlyattributedtothee ectsofacousticcavitationsproducedinthesolventbythepassageofanultrasonicwave.Ultrasoundalsoexertsamechanicale ect,allowinggreaterpenetrationofsolventintothesamplematrix,increasingthecontactsurfaceareabetweensolidandliquidphase;asaresultthesolutequicklydi usesfromsolidphasetothesolvent(Rostagno,Palma,&Barroso,2003).Inaddition,thereisnochemicalinvolvementintheultrasound-assistedextraction,whichcouldpreventpossiblechemicaldegradationoftargetedcompounds(Wang&Weller,2006).

Inthepresentstudy,ultrasound-assistedextractionparameterssuchasthesolvent,extractiontemperatureandextractiontimewereoptimisedusingresponsesurfacemethodology(RSM),byemployinga ve-level,three-vari-ablecentralcompositerotatabledesign(CCRD),inordertoobtaintheoptimalconditionsfortheextractionofphe-noliccompoundsfromwheatbran.2.Materialsandmethods2.1.Materials

WheatbranwasobtainedfromamillingplantinBei-jing,China.Thebranwasmilledandpassedthrougha0.5mmsieve.Thewheatbranwaskeptinasealedplasticbagandstoredat4°Cuntiluse.Allchemicalsandsolventsusedwereofanalyticalgrade.

2.2.Ultrasound-assistedextractionofphenoliccompoundsfromwheatbran

Ultrasound-assistedextractionwasperformedinanultrasoniccleaningbath(SB-5200Dtype,40kHz,250W,NingboScientzBiotechnologyCo.Ltd.,China)withause-fulvolumeof10l(internaldimensions:300Â240Â150mm).Workingfrequencywas xedat40kHz.Sampleswereplacedintoavolumetric ask(100ml),madeuptovolumewiththeextractingsolventandsonicatedfordi er-enttimesattherequiredtemperature.Thetemperaturewascontrolledbycirculatingexternalwaterfromathermostat-tedwaterbath.Aftertheextraction,the askwasremovedfromthebathandcooledtoroomtemperaturebycoolingwater.Thewheatbranextractswere lteredthroughWhat-manNo.1paperundervacuum,andthesolutionwascol-lectedinavolumetric ask,andusedforthedeterminationofthetotalphenoliccontent.2.3.Selectionofextractionsolvent

Fivegramsofaccuratelyweighedwheatbranwereextractedwith100mlof70%(v/v)methanol,70%(v/v)

ethanoland70%(v/v)acetone,respectively,inavolumetric ask(100ml)andkeptforsonicationat50°C.After20min,thesupernatan …… 此处隐藏：21426字，全部文档内容请下载后查看。喜欢就下载吧 ……