英文原文Abilityofaverylow-costextrudertoproduceinstantinfantfloursatasmallscaleinVietnamC.Mouqueta,*,B.Salvignolb,N.VanHoanb,J.Monvoisc,S.TrechedaUR106,Nutrition,limentationSocietes,IRD,BP182,Ouagadougou01,BurkinaFasobGRET,269KimMaStreet,Hanoi,VietNamcGRET,213rueLaFayette,75010Paris,FrancedUR106,IRD,BP64501,F34394MontpelliercedexFranceReceived25July2002；receivedinrevisedform18November2002；accepted21November2002AbstractExtrusioncookingisausefulprocessfortheproductionofinstantinfantflours,asitallowsgelatinisationandpartialdextrinisationofstarch,aswellasreductionoftheactivityofsomeantinutritionalfactors.Butexistingextrusionequipmentisnotsuitedtothecontextofdevelopingcountriesasitrequiresconsiderablefinancialinvestmentandtheproductioncapacity(minimum300kg/h)istoohigh.Theaimofourstudywastoimprovetraditionalextruderswithlowproductioncapacity(about30kg/h)manufacturedinVietnamandtotesttheirperformanceintheproductionofinfantflours.Severalblendsmadewithrice,sesameand/orsoybeanhavebeenextrudedwiththemodifiedequipmentthatwenameverylow-costextruder.Inthecaseofblendscontainingsoybean,starchgelatinisationwasnotcomplete,anddecreasedwithanincreaseinthelipidcontentoftheblend.Therateoftrypsininhibitordestructionevolvedinasimilarway.Addingwaterbeforeextrusion,orextrudingtheblendstwicewasnoteffectiveinincreasingtheratesofstarchgelatinisationortrypsininhibitordestruction.However,theverylow-costextruderproveditsabilitytoprocessthericesesameblendthathadalipidcontentoflessthan6g/100gDM,andlowinitialwatercontentaround10%,wetbasis(wb).Inthiscase,extrusionledtototalstarchgelatinisationandtheextentofstarchdextrinisation,whichwasmeasuredbycomparingtheviscosityofgruelspreparedfromcrudeandcorrespondingextrudedblends,wassufficienttopreparegruelswithsubstantiallyincreasedenergydensity.Withtheadditionofroastedsoybeanflour,sugar,milkpowder,vitaminsandminerals,thisblendcouldprovideanutritiousinstantflourusableascomplementaryfoodforinfantsandyoungchildren.#2003ElsevierScienceLtd.Allrightsreserved.Keywords:Extrusioncooking；Instantflour；Complementaryfood；Gelatinisation；Dextrinisation；Trypsininhibitordestruction1.IntroductionExtrusioncookingisoneofseveraldifferentprocessesusedtoproduceinfantflours.Thisparticularprocesshasmanyadvantagesthathavebeenextensivelyreviewed(Bjorck&Asp,1983；Camire,Camire,&Krumhar,1990；Harper&Jansen,1985).Fromanutritionalpointofview,extrusioncookingallowsinactivationofcertainantinutritionalfactorsliketrypsininhibitorfactorsthusincreasingproteindigestibility.Thehightemperaturegeneratedduringprocessingensuressatisfactoryhygienicquality,andingeneralresultsinstarchgelatinisation,thusleadingtoaninstantflour.Ifnottrulyinstant,theflourisatleastpre-cooked,andthesubsequenttimerequiredtocookthegruelisconsiderablyreduced.Duringextrusioncooking,rawmaterialsalsoundergohighshear,thusallowingpartialstarchhydrolysis(Colonna,Doublier,Melcion,DeMonredon,&Mercier,1984).Theextentofhydrolysisdeterminestheenergydensityatwhichitwillbepossibletoprepareagruelofsemi-liquidconsistencythatisacceptabletoinfants.Atagivenconsistency,themoreimportantthestarchishydrolyzed,thehigherthegruelenergydensitywillbe.Inspiteoftheseadvantages,theadoptionofextrusioncookingprocessingfortheproductionofinfantflourindevelopingcountriesisstilllimited.Onlyafewindustrialunitsproduceextrudedflouratalargescalemainlyinresponsetotheneedofinternationalornon-govern-0308-8146/03/$-seefrontmatter#2003ElsevierScienceLtd.Allrightsreserved.doi:10.1016/S0308-8146(02)00545-9FoodChemistry82(2003)249255/locate/foodchem*Tel.:+226-30-67-37；fax:+226-31-03-85.E-mailaddress:claire.mouquetird.bf(C.Mouquet).mentalorganisationsforemergencysupplies.Themainreasonforthisisthatmostextrudersaredesignedforlarge-scaleproduction,thusrequiringveryhighinvestmentandtechnicalknowledge.Eventheso-calledlow-costextruders,ordryextrudersthatweredevelopedfortheproductionofcomplementaryfoodsatthebeginningofthe1980sbytheuniversityofColorado(Harper,1995；Harper&Jansen,1985；Said,2000),aretoocostlyandtheirproductioncapacityistoohigh(about55,000dollarsforamachinewithaproductioncapacityof1tonperhour),andarethusnotaffordablefordevelopingcountries.Thedevelopmentofasmallsimplemachine,withasmallproductioncapacity(about30kg/h)isthereforeofgreatpotentialinterest.TheVietnamesecontextisparticularlywellsuitedforthedevelopmentoftheproductionofinfantflourbyextrusioncookingforseveralreasons.1.Inruralareasandparticularlyintheplains,mothersprepareathermosofboiledhotwatereachmorninginordertohaveasupplyofsafedrinkingwateravailableduringtheday,andthiswatercouldeasilybeusedforthepreparationofagruelwithaninstantflour2.Arudimentaryextrusioncookingprocesshasbeenusedformanyyearsinthecountryside；simpleextruderswithverysmallproductioncapacityalreadyexistandareusedfortheproductionofsnacksorcassavanoodlessoldinthestreet.ThesemachineswereprobablyoriginallydesignedintheUnitedStatesattheendofthenineteenthcenturyfortheextrusionofplastic.3.Thesesmallextrudersarenowmanufacturedlocallyinsmallmechanicalworkshops,anditisalsoeasyandcheaptoconstructsparepartslocallyforthemaintenanceofthemachines.Occasionalattemptshavebeenmadetoproduceinstantinfantfloursusingtheserudimentarylocalextrudersbuttheseeffortshavenotcontinued,firstlybecausetheirimpactonnutritionalqualityofinfantflourswasnotsatisfactory,andsecondlybecausethemachineswerenotsturdyandoftenbrokedownduringproduction.Takingthefeaturesofthisspecificcontextintoaccount,wemodifiedtherudimentarytypeoflocalextrudertoimprovetheirabilitytoproduceinfantflour,aswellastheirsturdiness.Theseimprovedextruderswithlimitedproductioncapacitywerenamedverylow-costextrudersinreferencetothelow-costextrudersthatHarperandJansenalreadydevelopedfortheproductionofnutritiousprecookedfoodsfordevelopingcountries(Harper&Jansen,1985).Theobjectiveofthisstudywastotesttheperformanceoftheseimprovedverylow-costextrudersand,inparticular,toevaluatetheinstantcharacteroftheflour,theextentofstarchdextrinisationandtheresidualtrypsininhibitoractivityofextrudedblends.2.Materialsandmethods2.1.ExtrusioncookingequipmentTheverylow-costextruderweusedisasimplesingle-screwautogenousextrudermanufacturedinVietnambyasmallenterprisenamedMechanicalWorkshopno.14700,(PhanChuTrinhStreet,DanangCity)accordingplansthatwefurnished(seephotoinFig.1).Thedrivemotorhasapowerof10.5kW.Thebarrellengthis200mmwithalength/diameterratioof5andhasacentralcylindricaldieof5mmindiameterand9mminlength.Therotatingspeedofthescrewishigh(500rpm),thusallowinghighshear.Thedesignofthescrewwasmodified(constantpitchandgradualdecreaseintheflightdepth),toallowaprogressiveincreaseinfrictionforcesandconsequentlyinthetemperatureinsidethebarrel.Thescrewdiameteris40mmandtherootdiameterincreasesgraduallyfrom33to38mm(seephotoinFig.2)Theextruderbarrelwallhasreversehelicalgroovestoenhanceforwardconveyanceoftheproduct.Toensurearegularfeedingrate,theextruderisequippedwithamotorisedfeedingscrewthatallowsfeedingratesfrom5to39kg/h.Residencetimeisbetween4and20s,whichisveryshortincomparisontootherextrudersbutlongerthantheresidencetimeobservedinrudimentaryVietnameseextruders.2.2.RawmaterialsTherawmaterialsusedtopreparecompositeflourswerethecheapestandthemosteasilyavailableontheVietnamesemarket.Thebasiccerealwaspolishedrice.Soybeanandsesamewereaddedtoincreaselipidandproteincontents.Allrawmaterialswereboughtlocally.Soybeanwasdriedinanoventoreachadrymattercontentabove92%,wetbasis(wb),beforebeingdehulledinanabrasivediskhullerequippedwithacyclonetoremovehullsandstraws.Afterdehulling,theabrasivediskswerebroughtcloserandthesoybeanpassedasecondtimeinthemachinetoberoughlygroundtoasizeofabout2mm.Differentinfantflourformulas(floursA,B,CandD)werecalculatedtoachievetheminimumproteinandlipidcontentsofrespectively,12and8g/100gDMrequiredforcomplementaryfoods,afteradditionofapremixtotheextrudedblends(Table1).ThepremixC.Mouquetetal./FoodChemistry82(2003)249255Fig.1.Theverylow-costextrusion-cookerusedforexperiments(designedandmanufacturedinVietnam).1.Feedinghopper；2.screwandbarrel；3.centralcylindricaldie；4.c