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英文原文AbilityofaverylowcostextrudertoproduceinstantinfantfloursatasmallscaleinVietnamC.Mouqueta,,B.Salvignolb,N.VanHoanb,J.Monvoisc,S.TrechedaUR106,Nutrition,limentationSocie′tes,IRD,BP182,Ouagadougou01,BurkinaFasobGRET,269KimMaStreet,Hanoi,VietNamcGRET,213rueLaFayette,75010Paris,FrancedUR106,IRD,BP64501,F34394MontpelliercedexFranceReceived25July2002receivedinrevisedform18November2002accepted21November2002AbstractExtrusioncookingisausefulprocessfortheproductionofinstantinfantflours,asitallowsgelatinisationandpartialdextrinisationofstarch,aswellasreductionoftheactivityofsomeantinutritionalfactors.Butexistingextrusionequipmentisnotsuitedtothecontextofdevelopingcountriesasitrequiresconsiderablefinancialinvestmentandtheproductioncapacityminimum300kg/histoohigh.Theaimofourstudywastoimprovetraditionalextruderswithlowproductioncapacityabout30kg/hmanufacturedinVietnamandtotesttheirperformanceintheproductionofinfantflours.Severalblendsmadewithrice,sesameand/orsoybeanhavebeenextrudedwiththemodifiedequipmentthatwenameverylowcostextruder.Inthecaseofblendscontainingsoybean,starchgelatinisationwasnotcomplete,anddecreasedwithanincreaseinthelipidcontentoftheblend.Therateoftrypsininhibitordestructionevolvedinasimilarway.Addingwaterbeforeextrusion,orextrudingtheblendstwicewasnoteffectiveinincreasingtheratesofstarchgelatinisationortrypsininhibitordestruction.However,theverylowcostextruderproveditsabilitytoprocesstherice–sesameblendthathadalipidcontentoflessthan6g/100gDM,andlowinitialwatercontentaround10,wetbasiswb.Inthiscase,extrusionledtototalstarchgelatinisationandtheextentofstarchdextrinisation,whichwasmeasuredbycomparingtheviscosityofgruelspreparedfromcrudeandcorrespondingextrudedblends,wassufficienttopreparegruelswithsubstantiallyincreasedenergydensity.Withtheadditionofroastedsoybeanflour,sugar,milkpowder,vitaminsandminerals,thisblendcouldprovideanutritiousinstantflourusableascomplementaryfoodforinfantsandyoungchildren.2003ElsevierScienceLtd.Allrightsreserved.KeywordsExtrusioncookingInstantflourComplementaryfoodGelatinisationDextrinisationTrypsininhibitordestruction1.IntroductionExtrusioncookingisoneofseveraldifferentprocessesusedtoproduceinfantflours.ThisparticularprocesshasmanyadvantagesthathavebeenextensivelyreviewedBjo¨rckAsp,1983Camire,Camire,Krumhar,1990HarperJansen,1985.Fromanutritionalpointofview,extrusioncookingallowsinactivationofcertainantinutritionalfactorsliketrypsininhibitorfactorsthusincreasingproteindigestibility.Thehightemperaturegeneratedduringprocessingensuressatisfactoryhygienicquality,andingeneralresultsinstarchgelatinisation,thusleadingtoaninstantflour.Ifnottrulyinstant,theflourisatleastprecooked,andthesubsequenttimerequiredtocookthegruelisconsiderablyreduced.Duringextrusioncooking,rawmaterialsalsoundergohighshear,thusallowingpartialstarchhydrolysisColonna,Doublier,Melcion,DeMonredon,Mercier,1984.Theextentofhydrolysisdeterminestheenergydensityatwhichitwillbepossibletoprepareagruelofsemiliquidconsistencythatisacceptabletoinfants.Atagivenconsistency,themoreimportantthestarchishydrolyzed,thehigherthegruelenergydensitywillbe.Inspiteoftheseadvantages,theadoptionofextrusioncookingprocessingfortheproductionofinfantflourindevelopingcountriesisstilllimited.Onlyafewindustrialunitsproduceextrudedflouratalargescalemainlyinresponsetotheneedofinternationalornongovern03088146/03/seefrontmatter2003ElsevierScienceLtd.Allrightsreserved.doi10.1016/S0308814602005459FoodChemistry822003249–255www.elsevier.com/locate/foodchemTel.226306737fax226310385.Emailaddressclaire.mouquetird.bfC.Mouquet.mentalorganisationsforemergencysupplies.Themainreasonforthisisthatmostextrudersaredesignedforlargescaleproduction,thusrequiringveryhighinvestmentandtechnicalknowledge.Eventhesocalledlowcostextruders,ordryextrudersthatweredevelopedfortheproductionofcomplementaryfoodsatthebeginningofthe1980sbytheuniversityofColoradoHarper,1995HarperJansen,1985Said,2000,aretoocostlyandtheirproductioncapacityistoohighabout55,000dollarsforamachinewithaproductioncapacityof1tonperhour,andarethusnotaffordablefordevelopingcountries.Thedevelopmentofasmallsimplemachine,withasmallproductioncapacityabout30kg/histhereforeofgreatpotentialinterest.TheVietnamesecontextisparticularlywellsuitedforthedevelopmentoftheproductionofinfantflourbyextrusioncookingforseveralreasons.1.Inruralareasandparticularlyintheplains,mothersprepareathermosofboiledhotwatereachmorninginordertohaveasupplyofsafedrinkingwateravailableduringtheday,andthiswatercouldeasilybeusedforthepreparationofagruelwithaninstantflour2.Arudimentaryextrusioncookingprocesshasbeenusedformanyyearsinthecountrysidesimpleextruderswithverysmallproductioncapacityalreadyexistandareusedfortheproductionofsnacksorcassavanoodlessoldinthestreet.ThesemachineswereprobablyoriginallydesignedintheUnitedStatesattheendofthenineteenthcenturyfortheextrusionofplastic.3.Thesesmallextrudersarenowmanufacturedlocallyinsmallmechanicalworkshops,anditisalsoeasyandcheaptoconstructsparepartslocallyforthemaintenanceofthemachines.Occasionalattemptshavebeenmadetoproduceinstantinfantfloursusingtheserudimentarylocalextrudersbuttheseeffortshavenotcontinued,firstlybecausetheirimpactonnutritionalqualityofinfantflourswasnotsatisfactory,andsecondlybecausethemachineswerenotsturdyandoftenbrokedownduringproduction.Takingthefeaturesofthisspecificcontextintoaccount,wemodifiedtherudimentarytypeoflocalextrudertoimprovetheirabilitytoproduceinfantflour,aswellastheirsturdiness.TheseimprovedextruderswithlimitedproductioncapacitywerenamedverylowcostextrudersinreferencetothelowcostextrudersthatHarperandJansenalreadydevelopedfortheproductionofnutritiousprecookedfoodsfordevelopingcountriesHarperJansen,1985.Theobjectiveofthisstudywastotesttheperformanceoftheseimprovedverylowcostextrudersand,inparticular,toevaluatetheinstantcharacteroftheflour,theextentofstarchdextrinisationandtheresidualtrypsininhibitoractivityofextrudedblends.2.Materialsandmethods2.1.ExtrusioncookingequipmentTheverylowcostextruderweusedisasimplesinglescrewautogenousextrudermanufacturedinVietnambyasmallenterprisenamedMechanicalWorkshopno.14700,PhanChuTrinhStreet,DanangCityaccordingplansthatwefurnishedseephotoinFig.1.Thedrivemotorhasapowerof10.5kW.Thebarrellengthis200mmwithalength/diameterratioof5andhasacentralcylindricaldieof5mmindiameterand9mminlength.Therotatingspeedofthescrewishigh500rpm,thusallowinghighshear.Thedesignofthescrewwasmodifiedconstantpitchandgradualdecreaseintheflightdepth,toallowaprogressiveincreaseinfrictionforcesandconsequentlyinthetemperatureinsidethebarrel.Thescrewdiameteris40mmandtherootdiameterincreasesgraduallyfrom33to38mmseephotoinFig.2Theextruderbarrelwallhasreversehelicalgroovestoenhanceforwardconveyanceoftheproduct.Toensurearegularfeedingrate,theextruderisequippedwithamotorisedfeedingscrewthatallowsfeedingratesfrom5to39kg/h.Residencetimeisbetween4and20s,whichisveryshortincomparisontootherextrudersbutlongerthantheresidencetimeobservedinrudimentaryVietnameseextruders.2.2.RawmaterialsTherawmaterialsusedtopreparecompositeflourswerethecheapestandthemosteasilyavailableontheVietnamesemarket.Thebasiccerealwaspolishedrice.Soybeanandsesamewereaddedtoincreaselipidandproteincontents.Allrawmaterialswereboughtlocally.Soybeanwasdriedinanoventoreachadrymattercontentabove92,wetbasiswb,beforebeingdehulledinanabrasivediskhullerequippedwithacyclonetoremovehullsandstraws.Afterdehulling,theabrasivediskswerebroughtcloserandthesoybeanpassedasecondtimeinthemachinetoberoughlygroundtoasizeofabout2mm.DifferentinfantflourformulasfloursA,B,CandDwerecalculatedtoachievetheminimumproteinandlipidcontentsofrespectively,12and8g/100gDMrequiredforcomplementaryfoods,afteradditionofapremixtotheextrudedblendsTable1.ThepremixC.Mouquetetal./FoodChemistry822003249–255Fig.1.TheverylowcostextrusioncookerusedforexperimentsdesignedandmanufacturedinVietnam.1.Feedinghopper2.screwandbarrel3.centralcylindricaldie4.controlpanelamperage,temperature,feedingscrewOn/Off,extruderOn/Off5.feedingscrewspeedvariator.Fig.2.Mainsparepartsoftheverylowcostextrusioncooker.1.Barrel2.screwwithgradualdecreaseintheflightdepthandconstantpitch3.cylindricaldieof5mmindiameterand9mminlength.Table1FormulasandcalculatedproteinandlipidcontentsoffinalcompositefloursCompositiong/100gdrymatterNutrientcontentaoffinalflourg/100gDMIngredientsblendedIngredientsaddedLipidProteincbeforeextrusionafterextrusionRiceSoybeanSesameRoastedsoybeanPremixbFlourA49.921.75.70.022.710.0315.45FlourB50.227.10.00.022.78.0516.63FlourC50.224.72.30.022.78.8216.70FlourD52.40.04.920.022.710.1216.33aCalculatedfromSoucietal.2000.bPremixpreparedbyblendingsugar66,milkpowder22,salt4,vitaminsandminerals7andvanillaaroma1.cTotalNcontentmultipliedby5.80,5.30,5.71and6.38forrice,soybean,sesameandmilkpowder,respectively.
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