Agricultural and Biosystems EngineeringConference Proceedings and Presentations Agricultural and Biosystems Engineering

7-2014

Extrusion processing of amaranth and quinoaCaitlin M. GearhartIowa State University, cmg@iastate.edu

Kurt A. RosentraterIowa State University, karosent@iastate.edu

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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 rutter@asabe.org 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.

REFERENCES

Abalone,R.,Cassinera,A.,Gastón,A.,andLara,M.A.2004.SomePhysicalPropertiesofAmaranthSeeds.BiosystemsEngineering89(1):109‐117.

Ahamed,N.Thoufeel,Singhal,RekhaS.,Kulkarni,PushpaR.,andPal,Mohinder.1998.A

lesser‐knowngrain,Chenopodiumquinoa:Reviewofthechemicalcompositionofitsedibleparts.Food&NutritionBulletin19(1):61‐70.

Becker,R.,Wheeler,E.L.,Lorenz,K.,Stafford,A.E.,Grosjean,O.K.,Betschart,A.A.,and

Saunders,R.M.1981.AcompositionalStudyofAmaranthGrain.JournalofFoodScience46:1175‐1180.

Bushway,A.A.,Belyea,P.R.andBushway,R.J.1981.ChiaSeedasaSourceofOil,

Polysaccharide,andProtein.JournalofFoodScience46:1349–1350.

Cheng,H.,Friis,A.2010.Modellingextrudateexpansioninatwin‐screwfoodextrusion

cookingprocessthroughdimensionalanalysismethodology.FoodandBioproductsProcessing88:188‐194.

Dogan,H.,andKarwe,M.V.2003.PhysicochemicalPropertiesofQuinoaExtrudates.Food

ScienceandTechnologyInternational9(2):101‐114.Ilo,S.,Liu,Y.,andBerghofer,E.1999.ExtrusionCookingofRiceFlourandAmaranth

Blends.LWT‐FoodScienceandTechnology32:79‐88.Omary,M.B.,Fong,C.,Rothschild,J.,Finney,P.2012.EffectsofGerminationonthe

NutritionalProfileofGluten‐FreeCerealsandPseudocereals:AReview.CerealChem.89(1):1‐14.

Riaz,M.N.2012.Cerealextrusiontechnologyforsmallfoodprocessingenterprises.Quality

AssuranceandSafetyofCropsandFoods4:136‐158.Singh,S.,Gamlath,S.,Wakeling,L.2007.Nutritionalaspectsoffoodextrusion:areview.

InternationalJournalofFoodScienceandTechnology42:916‐929.Taverna,L.G.,Leonel,M.,andMischan,M.M.2012.Changesinphysicalpropertiesof

extrudedsourcassavastarchandquinoaflourblendsnacks.CienciaETecnologiadeAlimentos32(4):826‐834.

Vilche,C.,Gely,M.,Santalla,E.2003.PhysicalPropertiesofQuinoaSeeds.Biosystems

Engineering86(1):59‐65.Weber,CharlesW.,Gentry,HowardS.,Kohlhepp,EdwinA.,andMcCrohan,PeterR.1991.

ThenutritionalandchemicalevaluationofChiaseeds.EcologyofFoodandNutrition26(2):119‐125.

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