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Agricultural and Biosystems EngineeringConference Proceedings and Presentations Agricultural and Biosystems Engineering
7-2014
Extrusion processing of amaranth and quinoaCaitlin M. GearhartIowa State University, [email protected]
Kurt A. RosentraterIowa State University, [email protected]
Follow this and additional works at: http://lib.dr.iastate.edu/abe_eng_conf
Part of the Agriculture Commons, and the Bioresource and Agricultural Engineering Commons
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Extrusion processing of amaranth and quinoa
AbstractBecause of the growing epidemic of gluten intolerance, there is growing interest in gluten-free foods. Beyondjust being gluten-free, such foods can have other positive nutritional benefits to human health. Extrusionprocessing is commonly used to produce a wide variety of human food products. Gluten-free grains can be aprocessing challenge, however, due to lack of proper binding, which can lead to poor quality food products.This research explores how extrusion parameters impacted the quality of amaranth- and quinoa-basedextrudates. The specific objectives of this project included extruding each of the grains, then measuringextrudate properties, such as color, unit density, expansion ratio, and durability. Both the quinoa and amaranthwere extruded as raw grain, as well as ground to 2mm and 1mm particle sizes. Other experimental conditionsincluded moisture contents of 20% and 40% (d.b.), and extruder screw speeds of 50 rpm and 100 rpm. Alltreatments were successfully extruded, and all extrudates had high quality attributes, making this the first timeeither quinoa or amaranth was extruded without any binding ingredients.
KeywordsExtrusion, grains, amaranth, quinoa, gluten-free
DisciplinesAgriculture | Bioresource and Agricultural Engineering
This conference proceeding is available at Iowa State University Digital Repository: http://lib.dr.iastate.edu/abe_eng_conf/388
An ASABE – CSBE/ASABE Joint Meeting Presentation
Paper Number: 141912019
Extrusion processing of amaranth and quinoa
Caitlin Gearhart and Kurt A. Rosentrater Iowa State University, Dept. of Agricultural and Biological Systems Engineering, ISU, Ames, IA
Written for presentation at the
2014 ASABE and CSBE/SCGAB Annual International Meeting
Sponsored by ASABE
Montreal, Quebec Canada
July 13 – 16, 2014
Abstract. Becauseofthegrowingepidemicofglutenintolerance,thereisgrowinginterestingluten‐freefoods.Beyondjustbeinggluten‐free,suchfoodscanhaveotherpositivenutritionalbenefitstohumanhealth.Extrusionprocessingiscommonlyusedtoproduceawidevarietyofhumanfoodproducts.Gluten‐freegrainscanbeaprocessingchallenge,however,duetolackofproperbinding,whichcanleadtopoorqualityfoodproducts.Thisresearchexploreshowextrusionparametersimpactedthequalityofamaranth‐andquinoa‐basedextrudates.Thespecificobjectivesofthisprojectincludedextrudingeachofthegrains,thenmeasuringextrudateproperties,suchascolor,unitdensity,expansionratio,anddurability.Boththequinoaandamaranthwereextrudedasrawgrain,aswellasgroundto2mmand1mmparticlesizes.Otherexperimentalconditionsincludedmoisturecontentsof20%and40%(d.b.),andextruderscrewspeedsof50rpmand100rpm.Alltreatmentsweresuccessfullyextruded,andallextrudateshadhighqualityattributes,makingthisthefirsttimeeitherquinoaoramaranthwasextrudedwithoutanybindingingredients.Keywords.Extrusion,grains,amaranth,quinoa,gluten‐free.
The authors are solely responsible for the content of this meeting presentation. The presentation does not necessarily reflect the official position of the American Society of Agricultural and Biological Engineers (ASABE), and its printing and distribution does not constitute an endorsement of views which may be expressed. Meeting presentations are not subject to the formal peer review process by ASABE editorial committees; therefore, they are not to be presented as refereed publications. Citation of this work should state that it is from an ASABE meeting paper. EXAMPLE: Author’s Last Name, Initials. 2014. Title of Presentation. ASABE Paper No. ---. St. Joseph, Mich.: ASABE. For information about securing permission to reprint or reproduce a meeting presentation, please contact ASABE at [email protected] or 269-932-7004 (2950 Niles Road, St. Joseph, MI 49085-9659 USA).
INTRODUCTION
Extrusionisaprocessthatproducesavarietyoffoodsfromfundamental
ingredients.Thisprocessutilizesanextrudertoproducefoodssuchasready‐to‐eatcereal,
pasta,candy,croutons,flour,andpetfood.Thereareseveraltypesofextrudersforfood
production,includingsingle‐screwandtwin‐screw.However,theyallusuallyservethe
samepurpose:toproducevariousfoodsfromcertainstartingmaterialsandunderspecific
extrusionconditions.Extrusionismostoftenusedtocook,texturize,expand,andshapethe
desiredfood.Duringthisprocess,rawingredientsareinsertedintotheextruder,
customarilythroughafeedbin.Themainscrewinsidetheextruderisoperatedbythe
powersupplyandmixesthesubstancewhileitisbeingheated.Asthishappenstheproduct
ismovingtowardthedie,whereitexitsthemachine.Uponleavingthemachine,the
productusuallyincreasesinsizeduetothereleaseofsteam.
Numerousstudieshaveshownthatextrusionhasadefinitepositivenutritional
effectonfood.AccordingtoastudybySinghetal.(2007),theseadvantageousresults
includethedestructionofanti‐nutritionalfactors,increasedsolubledietaryfiber,reduction
oflipidoxidation,andthegelatinizationofstarch.Thereare,however,veryspecific
extrusionconditionsnecessarytoproduceaproductthatpossessestheseproperties.These
conditionsvarydependingonwhatisbeingextruded,butthereappeartobesome
commonnecessaryelementsamongthedifferentfoods.Weknow,forexamplethatifthe
extrusiontemperatureistoohigh,burningandjammingofthemachineresults.Onthe
otherhand,iftemperatureistoolow,thenecessarypelletsmaynotform.Moisturecontent
alsoplaysaverysignificantroleintheprocess.Ifthemoisturecontentistoohighthe
extruderwillbecomejammed.However,ifthereisnotenoughmoistureinthemix,the
productwillnotstaybound.ThestudiesthatSinghconductedshowedthatthebest
overarchingextrusionconditionsforhighnutritionalqualitywerehighmoisturecontent,
lowresidencetime,andlowtemperatures.
Whilethemarketforextrudedcerealsandsnacksisquitelarge,itseemstobe
shrinkingeveryday,asmorepeoplebeginglutenfreediets.Agluten–freelifestyleisan
increasinglypopulardietaryoptionthaturgespeopletogiveupallproductscontaining
glutenintheirdiets.Alargeportionofsocietyischoosingthisdietaryoptionforavariety
ofhealthreasonssuchastheprogressivelycommonceliacdisease.Whileglutenisalsoone
ofthemostcommonfoodintolerances,manypeoplealsochoosetoparticipateingluten
freedietsfornon‐medicalreasons.Forallofthesereasons,theglutenfreemarketis
rapidlygrowing.Ifwewereabletoutilizethetechnologyofextrusiontoproducegluten‐
freesnacks,thiswouldgreatlyexpandthemarketforextrudedproducts.Theproduction
ofglutenfreesnacksbywayofextrusionwouldbeahugestepforwardforthesnack
producingindustry.
Thegrainsthatarecommonlyusedtotakeadvantageofthenutritiousbenefitsof
extrusionarecornandrice.Thereis,however,thepossibilityofproducingextremely
healthyfoodsfromlesscommongrainssuchasquinoa,andamaranth.Bothofthesegrains
aregluten‐free.Thegrowinggluten–freemarketprovidesahugepotentialopportunityfor
extrudedgluten‐freeproducts.
Quinoaisoneofthegrainsthatfallsintotheglutenfreecategory.Thelargest
producersofthisgrainareBoliviaandPeruwith88%oftheworld’squinoa.Thenext
largestproduceristheUnitedStateswithonlyashearfractionofitsproduction,6%.Thisis
anidealseedtogrowbecauseitisdroughtandfrostresistant,growsinpoorsoil,and
growsathighaltitudes.Likechia,quinoaisidealforuseintheextrusionofsnackfoods
becauseofitshealthbenefits.AccordingtoastudybyVilcheetal.(2003),theseseeds
contain10%to18%protein,4.5%to8.75%crudefat,54.1%to64.2%carbohydrates,
2.4%to3.64%crudefiber,andafirstlimitingaminoacidoflysine,whichisreadily
availableintheseseeds.Thisaloneshowsquinoatobenutritionallysuperiortowheat.
Anotherstudy,byAhamedetal.(1998),hadverysimilarresultstotheseforthechemical
compositionofquinoa.TheresultsofthisstudyareshowninTable6.Thehighprotein
contentofquinoamakesitagreatalternativetoflourforglutenfreegoods.Also,thefact
thatitislowinfatmakesquinoaapromisinggraintoendupwithacohesiveextrudate.A
studydonebyDoganandKarwe(2003)discussesthepropertiesofthisgrainafter
extrusion.Itwasfoundthattheproteinisrichinlysine,methionine,andcysteine.This
extrudatealsohasmorethandoubletheproteinofcornandrice.Forallofthesereasons,
quinoaisanidealgraintoextrudeforthepurposeofproducingglutenfreesnacks.
Amaranthisyetanotherglutenfreegrain.ItismostcommoninPeru,Bolivia,and
Mexico.Itsyieldschangesignificantlydependingonthegrowingseason,location,andsoil
moisture.Similartotheothertwograins,Amaranthisanidealgraintouseintheextrusion
ofglutenfreesnackfoods.Ithasdefinitehealthbenefitsaswell.AstudybyAbaloneetal.
(2004)showsthattheseseedshave16%to18%protein,andhighlysineandtryptophan
content.AstudydonebyAhamedetal.(1998)showedamaranthtohave13‐18%protein,
6‐8%fat,63%carbohydrates,and4‐14%crudefiber.Similartoquinoa,amaranthhashigh
proteincontent,makingitidealtouseinglutenfreegoods.Thelowfatcontentofamaranth
makesitanidealgraintoextrudewithoutjammingthemachine.Anotherstudy,conducted
byIloetal.(1999),discussedtheextrusionofamaranth.Thestudyfoundthatextruding
thisgrainhelpedtoincreasetheavailabilityofproteinandnutrients.Duetothepositive
nutritionalqualitiesofamaranthandthefactthatitisglutenfree,itisanidealgrainto
extrudeintoglutenfreesnackfoods.
Bothofthegrainsdiscussedhavenutritionalqualitiesofvaluetothehumanbody.
Severalstudieshaveshownthatextrudingthesegrainshasfurtherincreasedtheir
nutritionalvalue.Thepurposeofthisprojectistoutilizethegrainsquinoaandamaranthto
produceglutenfreesnacks.
MATERIALSANDMETHODS
RawIngredients
WhitequinoaseedswereobtainedfromRoland.Amaranthwasobtainedfrom
Angelina’sGourmet.Twokilogramsofeachoftherawingredientsweregroundusinga
Wileylaboratorymill(model4,ThomasScientific,Swedesboro,NJ)toanaverageparticle
sizeof2mm,twokilogramsweregroundusinga1mmscreen,andtwokilogramswereleft
raw.Moisturecontentofeachwasdeterminedusingadryingovenat135°Cfortwohours.
Enoughwaterwasaddedtoonekilogramofeachsampletoachieve20%dbmoistureand
totheotherkilogramtoreach40%dbmoisture.Theproductsweredividedintothe
followingcategories:rawgrainat20%and40%moisturecontent,1mmparticlesizeat
20%and40%moisturecontent,and2mmparticlesizeat20%and40%moisturecontent.
ExtrusionProcessing
Theextrusionofeachoftheblendswascarriedoutusingasingle‐screwextruder
(modelPL2000Plasti‐Corder,BrabenderSouthHackensack,NJ)withascrewcompression
ratioof1:1,ascrewlength‐to‐diameterratioof20:1,andabarrellengthof317.5mm
(Figure1).Thediehadadiameterof3.0mm.Eachblendwasextrudedatscrewspeedsof
50rpmand100rpm.Therawblendsweremanuallyscoopedintothebarrelofthe
extruderandforcedthroughwithawoodenrodtoensurenojammingwouldtakeplace.
Temperaturesweremonitoredatthefeed,transition,anddiezones.
RawIngredientProperties
Aftertheingredientsweremixedtotheirnecessarymoisturecontents,theblends
wereanalyzedintermsofcolor.Todeterminethecolorofthemixtures,aspectrometer
(LabScanXE,HunterLab,Reston,VA)wasused.TheLvaluemeasuredthe
lightness/darkness,thea*valuequantifiedtheredness/greenness,andtheb*value
signifiedtheyellowness/blueness.Themoisturecontentoftherawingredientmixeswere
alsotestedformoisturecontentafterextrusiontoensurethevaluesmatchedtheexpected
moisturecontents.
ExtrudateProperties
Afterextrusion,theproductsweredriedinalaboratoryovenat50°Cfor24hours.
Theextrudateswerethenanalyzedforcolor,unitdensity(kg/cm3),expansionratio,and
pelletdurabilityindex(%).Theextrudatecolorwasmeasuredusingthesameprocessas
therawingredientcolorwasmeasured.Aspectrometer(LabScanXE,HunterLab,Reston,
VA)wasusedtodeterminetheLvalue(measuringlightness/darkness),thea*value
(measuringredness/greenness),andtheb*value(measuringyellowness/blueness).To
measureunitdensity,eachextrudatewascuttosectionsoflength20mm.Theywerethen
weighedonabalanceandmeasuredwithacalipertoconcludetheirdiameters.Theunit
densitywasdeterminedbydividingthemass(kg)bythevolume(cm3)becauseofthe
extrudates’cylindricalshape.Tocalculatetheexpansionratio,theactualdiameterofthe
extrudates(mm)wasdividedbythediameterofthedie(3mm).Tomeasurepellet
durabilityindex,100gofeachextrudatewastumbledinapelletdurabilitytester(model
PDT‐110,SeedburoEquipment,Chicago,IL)for10min.Then,productsweresievedfor15
sec,andagainweighedonanelectronicbalance.Thefinalweightwasdividedbytheinitial
weight(100g)andmultipliedby100,resultinginapercentage.Theresultsofthese
analysesareshowninTable3andTable5forquinoaandamaranth,respectively.Figure2
andFigure4showtheblendsbeforeandafterextrusionforcomparison.
ExperimentalDesign
Theexperimentaldesignwasbasedona3x2x2matrixwithvaryingdependent
variablesofparticlesize,moisturecontent,andscrewspeed,respectively(asshownin
Table1).Particlesizewasdividedinto3groupsofrawgrain,2mmaverageparticlesize,
and1mmaverageparticlesize.Moisturecontentwassplitinto2categoriesof20%dband
40%db.All6blendswereextrudedatscrewspeeds50rpmand100rpm,resultingin12
differenttreatmentoptions.
DataAnalysis
Foreachextrudate,allphysicalpropertiesweremeasured3separatetimesexcept
durabilitywhereonemeasurementwastaken.Allmeasurementswereusedtocalculate
theaverageandstandarddeviationofeachproperty.Measuredpropertiesincludedboth
measurementsfromrawgrain(moisturecontent,andL*,a*,andb*color)andthe
extrudates(L*,a*,b*,unitdensity,expansionratio,andpelletdurability).
RESULTSANDDISCUSSION
RawIngredientProperties
MoistureContent:Notonlyismoisturecontentoftheextrudatesimportant,butmoisture
contentoftherawgrainsisaswell.Thisisalargeindicatorastohoweasilytheblendwill
extrude.Ifmoisturecontentistoolow,thefinalproductwillnotstaybound.However,if
themoisturecontentoftheblendistoohigh,theblendwilljamtheextruderandnot
produceaproduct.Table3andTable5show,incolumn3,theactualmoisturecontentof
blendsforquinoaandamaranth,respectively.Theaveragemoisturecontentofthe20%db
quinoawas23.67%db,andtheaveragemoisturecontentforthe40%dbquinoawas
41.11%db.Foramaranth,theaveragemoisturecontentofthe20%dbgrainwas24.29%
db,andtheaveragemoisturecontentforthe40%grainwas42.17%db.Thevariancewas
lowforthemoisturecontentofbothgrainsandthemixtureswereutilizedforthe
extrusion.
Color:Colorwasmeasuredforeachblendbeforeextrusionandthequinoaresultsarealso
seeninTable3.Forquinoa,theL*valuedecreasedforeachgrainsizeasmoisturecontent
increasedfrom20to40%.Therewasnocorrelationbetweenmoisturecontentandparticle
sizeandeithera*orb*.TheamaranthdataisshowninTable5.Neithermoisturecontent
orparticlesizehaveanimpactontheL*value.However,a*decreasesasgrainsize
decreases.B*decreasesasbothmoisturecontentandparticlesizedecrease.
ExtrudateProperties
Table3displaysthequinoaextrudateproperties.Itshowswhateffectsmoisturecontent,
grainparticlesize,andextruderscrewspeedhadoncolor(L*,a*,b*),unitdensity,
expansionratio,andpelletdurabilityindex.Thevaluesincludedinthistablearethe
averageof3trialsandthestandarddeviationforeachextrudateproperty.Table5shows
thesameextrudatepropertiesforamaranth.Italsoprovidestheeffectsofthesamecontrol
variablesstatedaboveonthepropertiesofcolor(L*,a*,b*),unitdensity,expansionratio,
andpelletdurabilityindex.
Color:Extrudatecolorisveryimportantwhenitcomestocustomerapproval,especially
whendealingwithhumanfoods.Iftheextrudatedoesn’tvisuallyappealtotheconsumers,
itisaproblem.ThethreecategoriesbywhichcolorismeasuredareL*,a*,andb*.
AccordingtothequinoadatainTable3,Treatment4hadthehighestL*valueof69.14and
Treatment12hadthelowestwithavalueof56.4.Asthescrewspeedincreased,L*
decreased.Thelowesta*valueof3.22camefromTreatment9.Thehighestvalueof6.55
camefromTreatment3,whichwassignificantlyhigherthanalloftheothertreatments.
Dataanalysisshowedthatasthemoisturecontentincreased,thea*valueoftheextrudates
increased,butastheparticlesizedecreased,thea*valuesdecreased.Thelowestb*value
camefromTreatment9,andwasmeasuredtobe18.44,whichwasconsiderablylowerthan
theothervalues.Thehighestb*valueof27.81wasmeasuredfromTreatment4.
Treatments1,2,3,and4,whichwereallblendsmadewithrawgrain,hadhigherb*values
thantherestofthetreatments.Astheparticlesizedecreased,b*valuesdecreased.Asthe
screwspeedincreased,theb*valueincreasedaswell.Accordingtotheamaranthdatain
Table5,thelowestL*value,fromTreatment8,of49.75,wassignificantlylowerthanany
otherL*value.ThehighestL*valuewas67.02,fromtreatment11.Asthescrewspeed
increased,theL*valueincreasedaswell.Thelowestmeasureda*valuewasfrom
Treatment10andwasmeasuredas6.19.Otherlowa*valueswerefromTreatments8,11,
and12.Thehighestvaluewas9.64,fromTreatment3.Astheparticlesizedecreased,there
wasadecreaseina*.Amaranthappearedtohavehighera*valuesthanquinoadid,
meaningitwasmoreredthangreenonthecolorscale.Significantlylowerthantherest,
Treatment’11’sb*valuewas19.23.ThehighestvaluecamefromTreatment2at29.09.
Othertreatmentswithhighb*valueswereTreatments4and6.Asthegrainsizedecreased,
b*decreased.However,asthescrewspeedincreased,sodidb*.Themoremoistureagrain
contains,thedarkerittendstobe.ThismeansthattheL*valuewouldbelower.Since
amaranthhadthelowestL*value,itislikelylesswaterevaporatedfromtheamaranth
blendsthanitdidfromthequinoablends.
AccordingtoastudybyTavernaetal.(2012),inanextrusionofquinoaflourandindustrial
sourcassavablends,afterextrusion,theblends’Lvaluesvariedfrom53.05to74.69,which
aresimilartothevaluesfoundinTable3.ThesamestudyalsoshowsthattheLvalue
decreasedafterextrusion,whichisconsistentwithTable3aswell.Thestudywiththe
blendsofquinoaandindustrialsourcassavahada*valuesrangingfrom4.64to6.43
(Taverna,2012).Thesea*valuesarealsosimilartothoseinTable3.Theamaranthand
sourcassavablendshadbvaluesfrom10.88to20.86(Taverna,2012).Thesevaluesforb*
aresignificantlylowerthanthosefoundinTable3.
61.9159.6
UnitDensity:Duetotheneedtocontrolnutrientsinextrudedfoods,unitdensityisan
importantpropertytomeasure.Table3showsthatTreatment3hadthelowestunit
densityofquinoa,withavalueof1.1g/cm3.Treatments1,2,5,8,and10alsohadverylow
unitdensityvalues.ThehighestvalueofmassperunitdensitycamefromTreatment4,
whichwassignificantlyhigherthananyoftheothertreatments.Treatment4hadaunit
densityof1.51g/cm3.Therewasnocorrelationbetweenunitdensityandmoisture
content,particlesize,orscrewspeed.AccordingtoTable5,theamaranthblendwiththe
lowestunitdensitywasTreatment2,withavalueof0.9g/cm3.Thisisconsiderablylower
thananyothertreatments.Treatment3hadthehighestunitdensitywithavalueof1.43
g/cm3.Treatments3and4hadsubstantiallylargerunitdensityvaluesthantherestofthe
treatments.Asthemoisturecontentintheamaranthblendsincreased,theextrudates’unit
densityincreased.Thetwograinslikelyhadsimilarunitdensitiesbecausetheywereboth
testedatthesamemoisturecontentlevels.Ourresultsshowthatamaranthhad
significantlylowervaluesforunitdensitythandidquinoa.AccordingtoTable6,quinoa
wasmuchhigherinthepercentagesofcarbohydratesthanamaranth,sothismayexplain
thehigherunitdensity.
ExpansionRatio:Theexpansionratioistheamountthattheproductpuffsuponexitingthe
extruderandisaveryimportantpropertywhenitcomestoextrusionofhumansnack
foods.AccordingtoTable3,Treatments4and11werethequinoablendswiththelowest
expansionratiosof0.92and0.99,respectively.Theseweretheonlytwotreatmentswith
expansionratiosbelow1,meaningtheyshrunkinsizeuponexitingtheextruder.The
largestvalueofexpansionratiocamefromTreatments5and10,bothwithvaluesof1.13.
Asmoisturecontentoftheblendsincreased,therewasadecreaseintheexpansionratioof
theextrudates.AccordingtoTable5,theamaranthblendwiththelowestunitdensitywas
Treatment2,withavalueof0.9.Thiswastheonlytreatmentwithanexpansionratioless
than1.Treatment9hadthehighestvalueof1.34,whichwasconsiderablylargerthanthe
othertreatments.Astheblends’moisturecontentincreased,theextrudates’expansion
ratiodecreased.Bothgrainshadsimilarexpansionratios.Thismaybeduetothefactthat
theywerebothextrudedatthesamemoisturecontents,whichusuallyhasthebiggest
affectonexpansion.However,proteincontentmayhavelargeeffectsonexpansionratioas
well.ThisisalsoconsistentwiththeresultsinTables3,5,and6.AccordingtoTable6,the
proteincontentinbothquinoaandamaranthwerebetween12and19%.Tables3and5
showthattheexpansionratiosinbothgrainswereverysimilar.Quinoahadanaverage
expansionratioof1.06,andamaranthof1.1.Theblends’similarmoistureandprotein
contentslikelyledtothecomparableexpansionratios.
PelletDurabilityIndex:Pelletdurabilityindex(PDI)measuresthebreakagetheextrudate
isabletoendure,andhasgreatimportanceinthestorageoffoods.Thehigherthe
percentage,thestrongerandlesslikelytheproductistobreak.AccordingtoTable3,the
quinoablendwiththelowestpelletdurabilityindexwasTreatment2,withaPDIvalueof
68.6%,whichwassignificantlylowerthantheothertreatments.Treatments1and9were
similarinPDIvaluesat81.9and88.2%,respectively.Thehighestpelletdurabilityindex
valuecamefromTreatment11,with99.6%.OtherhighPDIvalueswerefromTreatments
5,7,and10withvaluesof97.1,98.4,and98.5%,respectively.AccordingtoTable5,the
amaranthblendswiththelowestpelletdurabilityindexwereTreatments1and9with
valuesof80and80.2%,respectively.ThetreatmentswiththehighestPDIswere
Treatments7and8at98.3and98.4%,respectively.Proteincontentusuallyhasaneffect
ondurabilityofextrudates.However,itislikelythataquinoatreatmenthadthelowestPDI
becauseaccordingtoTable6,itmaycontainmorefatthanamaranth.Themorefatthe
graincontains,thelesscohesivetheextrudatestendtobe.
CONCLUSONS
Itispossibletoproduceextrudedproductsfromthepuregrainsofquinoaand
amaranth,mixedwithonlywater.Thesegrainscanbothbeextrudedatparticlesizesof
rawgrain,2mm,and1mm,andatmoisturecontentsof20%dband40%db.Allextrusion
wascarriedoutonasinglescrewextruderwithscrewspeedsof50rpmand100rpm.
Temperaturewasnotregulatedthroughouttheprocess,anddoesvaryasshowninTable2
andTable4forquinoaandamaranth,respectively.Figure3andFigure5plotthe
temperatureagainsteachmeasuredpropertytodeterminewhatrelationshipsthe
changingtemperatureshavewiththeresultsforquinoaandamaranth,respectively.
PhysicalpropertiesofbothrawblendsandextrudatesareshowninTable3andTable5for
quinoaandamaranth,respectively.Analysisshowedthatasthemoisturecontent
increased,thea*valueoftheextrudatesincreased,andtherewasadecreaseinthe
extrudates’expansionratio.Asthequinoaparticlesizedecreased,thea*andb*values
decreasedintheextrudates.Asthescrewspeedoftheextruderincreased,theextrudates’
L*valuedecreased,andtheb*valueincreased.Foramaranth,dataanalysisshowedthatas
themoisturecontentincreased,theexpansionratiooftheextrudatesdecreasedandtheir
unitdensityanddurabilityincreased.Astheparticlesizedecreased,therewasadecrease
intheextrudates’a*andb*values.Astheextruder’sscrewspeedincreased,theL*andb*
valuesoftheextrudatesincreased.
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Table1:Experimentalprotocolincludingtreatmentnumbersanddependentvariables.
Table2:Temperaturesmeasuredatthedie,transition,andfeedzonesfortheextrusionofquinoa.
Table3:Meanpropertiesofquinoaextrudates(standarddeviationinparentheses).
Table4:Temperaturesmeasuredatthedie,transition,andfeedzonesfortheextrusionofamaranth.
Table5:Meanpropertiesofamaranthextrudates(standarddeviationinparentheses).
Table6:Typicalchemicalpropertiesofquinoaandamaranthseeds.
Figure1:Brabendersingle‐screwextruderusedtoextrudeblends.Conditionsincludeda3mmdieandascrewcompressionratioof1:1.
Figure2:Rawquinoa(above)andextrudates(below)fortreatments2,6,and10,respectively.
Figure3:Relationshipsamongalldependentvariables.Someclusteringwasevidentduetothedifferentmoisturecontents.
Quinoa
Figure4:Rawamaranth(above)andextrudates(below)fortreatments2,6,and10,respectively.
Figure5:Relationshipsamongalldependentvariables.Someclusteringwasevidentduetothedifferentmoisturecontents.
Amaranth