Selection of Suitable Test Procedure

8/8/2019 Selection of Suitable Test Procedure

1/27

Selection of Suitable Test Selection of Suitable Test

Procedure for Texture AnalysisProcedure for Texture Analysis

Manpreet SinghManpreet SinghPhD Student PhD Student

Department of Processing & Food Engineering,Department of Processing & Food Engineering,PAU, Ludhiana.PAU, Ludhiana.


2/27

A A scientist scientist cancan easilyeasily get get bewilderedbewildered whilewhilefacingfacing thethe problemproblem of of developingdeveloping aa

suitablesuitable procedureprocedure forfor measuringmeasuring thethetexturaltextural propertiesproperties of of aa particularparticular foodfood..

Where should one start from ..?Where should one start from ..?


3/27

N umberN umber of of factorsfactors shouldshould bebe consideredconsidered beforebefore

settingsetting upup aa newnew test test procedure,procedure, otherwiseotherwise aagoodgood dealdeal of of moneymoney andand timetime willwill bebe wastedwasted. .

TheseThese factorsfactors cancan bebe usedused toto select select aa suitablesuitableinstrument instrument. . If If oneone alreadyalready hashas aa UTMUTM thethe samesameprocedureprocedure cancan bebe usedused toto select select whichwhich test test principleprinciple isis most most appropriateappropriate forfor that that particularparticularfoodfood andand whichwhich attachmentsattachments areare usedused toto performperformthethe test test..


4/27

Factors to be consideredFactors to be considered

Instrument or SensoryInstrument or SensoryN ature of Product N ature of Product

Purpose of Test Purpose of Test Accuracy Required Accuracy RequiredDestructive or N ondestructiveDestructive or N ondestructiveCostsCostsTimeTimeLocationLocation


5/27

Instrument or SensoryInstrument or Sensory

InstrumentsInstruments areare generallygenerally preferredpreferredbecausebecause theythey areare believedbelieved toto bebe

more reproducible,more reproducible,Use less timeUse less timeUtilize a minimum of laborUtilize a minimum of labor

ThereThere areare timestimes whenwhen sensorysensory methodsmethodsareare thethe onlyonly wayway inin whichwhich adequateadequateinformationinformation cancan bebe obtainedobtained


6/27

N ature of Product N ature of Product

KindKind of of materialmaterial affectsaffects whichwhich typetype of of instrument instrument toto bebe usedusedLiquid,Liquid,Solid,Solid,Brittle,Brittle,Plastic,Plastic,Homogeneous,Homogeneous,Heterogenous,etc.Heterogenous,etc.

Most tests on solid or near solid foods use some form of Most tests on solid or near solid foods use some form of uniaxial compressionuniaxial compression

SophisticatedSophisticated teststests onon viscosityviscosity useuse somesome formform of of

rotationalrotational motionmotion


7/27

Purpose of Test Purpose of Test

WhetherWhether thethe test test isis toto bebe usedused forfor qualityquality control,control, forforsettingsetting legallylegally bindingbinding officialofficial standards,standards, forfor product product development development oror forfor basicbasic research?research?

EssentialEssential featurefeature of of thethe selectionselection processprocess

InIn somesome casescases aa singlesingle point point measurement measurement is is adequateadequatewherewhere oneone isis usuallyusually preparedprepared toto sacrificesacrifice sophisticationsophistication forforthethe sakesake of of rapidityrapidity likelike forfor routineroutine qualityquality controlcontrolpurposespurposes. .

InIn otherother casescases multimulti point point measurement measurement is is neededneeded wherewheredifficult difficult problemsproblems areare handledhandled inin researchresearch laboratorylaboratory oror ininnewnew product product development development whichwhich requirerequire sophisticatedsophisticated

instrumentationinstrumentation. .


8/27

Accuracy required Accuracy requiredGreaterGreater accuracyaccuracy isis obtainedobtained asas thethe numbernumber of of replicationsreplications isis increasedincreased. .

LargerLarger samplesample sizesize givesgives aa result result closercloser toto thethetruetrue meanmean thanthan aa smallsmall samplesample size,size, hencehencefewerfewer replicatereplicate teststests areare neededneeded toto obtainobtain aagivengiven degreedegree of of accuracyaccuracy. . But But aa largerlarger samplesamplesizesize usuallyusually meansmeans that that higherhigher forcesforces areareneeded,needed, andand thethe forceforce capacitycapacity of of thethe instrument instrument maymay bebe exceededexceeded. .

WhenWhen thethe spreadspread of of valuesvalues betweenbetween individualindividualunitsunits isis needed,needed, it it isis preferablepreferable toto useuse aa smallsmallsamplesample sizesize andand runrun aa largelarge numbernumber of of

replicatesreplicates. .


9/27

SometimesSometimes therethere isis largelarge inherent inherent variabilityvariability (even(even 2020%% oror higher)higher) fromfrom unit unit toto unit unit inin thethe samesame samplesample lot lot..

WhenWhen workingworking withwith aa newnew commodity,commodity, it it isisadvisableadvisable toto runrun aa preliminarypreliminary test test totoascertainascertain thethe degreedegree of of inherent inherent variabilityvariability

andand toto establishestablish howhow largelarge aa samplesample sizesizeandand replicationsreplications areare requiredrequired dodo givegivedesireddesired confidenceconfidence inin thethe datadata..


10/27

SinceSince inherent inherent variabilityvariability isis normalnormal forfor most most foods,foods, thethe primaryprimary considerationconsideration isis toto looklook forfor

thethe instrument instrument that that cancan performperform teststests rapidlyrapidly..

A A higherhigher degreedegree of of precisionprecision isis aa secondarysecondaryconsiderationconsideration becausebecause therethere isis aa littlelittle point point inin

attemptingattempting toto measuremeasure somesome texturaltextural parameterparametertoto aa precisionprecision of of 11%% whenwhen replicatereplicate samplessamplesmaymay varyvary byby 2020%% oror more,more, especiallyespecially whenwhenextraextra timetime isis requiredrequired toto obtainobtain thethe highhigh degreedegreeof of precisionprecision..

It It isis usuallyusually preferablepreferable toto replicatereplicate aa 11 minmin test test fivefive timestimes that that toto runrun aa moremore preciseprecise 55 minmin test test


11/27

Destructive or N ondestructiveDestructive or N ondestructive

DestructiveDestructive teststests ruinruin thethe structurestructure andandorganizationorganization of of thethe sample,sample, renderingrendering it it unsuitableunsuitable forfor repeatingrepeating thethe test test..

N ondestructiveN ondestructive teststests leavesleaves hehe foodfood ininconditioncondition soso closeclose toto itsits originaloriginal statestate that that thethe test test cancan bebe repeatedrepeated andand givegive thethe

result result asas thethe first first timetime..

BothBoth techniquestechniques havehave hadhad theirtheir successessuccessesandand failuresfailures..


12/27

MajorityMajority of of thethe texturaltextural parametersparameters of of foodfood areare

sensedsensed inin thethe mouthmouth andand masticationmastication isis aadestructivedestructive process,process, it it seemsseems logicallogical that that destructivedestructive teststests shouldshould bebe thethe predominant predominant typetype toto bebe usedused onon foodsfoods..

N ondestructiveN ondestructive teststests areare sometimessometimes effective,effective,andand theythey offeroffer thethe advantageadvantage that that thethe samesamepiecepiece of of foodfood maymay bebe repeatedlyrepeatedly tested,tested, thusthuseliminatingeliminating variationsvariations inin geometrygeometry fromfrom piecepiece totopiecepiece..


13/27

CostsCostsHowHow muchmuch moneymoney cancan bebe spent spent onon thethe test?test?

ThisThis includesincludes thethe initialinitial cost cost of of instrument,instrument, andandmaintenancemaintenance andand operatingoperating costscosts..

TheThe instrument instrument that that usesuses thethe chart chart paperpaper hashas ananoperatingoperating cost cost whichwhich isis not not foundfound inin thetheinstrument instrument inin whichwhich thethe dialdial readingreading isis takentaken..

DoesDoes thethe instrument instrument needneed sparespare partsparts andand what what isis theirtheir availabilityavailability andand cost?cost?

IsIs thethe instrument instrument usedused occasionallyoccasionally ororfrequently?frequently?


14/27

LabourLabour cost?cost?

A A simplesimple instrument instrument cancan bebe operatedoperated bybyunskilledunskilled oror semisemi--skilledskilled personnelpersonnelwhereaswhereas sophisticatedsophisticated instrumentsinstruments needneed totobebe operatedoperated byby aa qualifiedqualified personperson. .

FixedFixed cost cost of of automaticautomatic instrument instrument isis moremore

asas comparedcompared toto aa simplesimple instrument instrument but but maymay cost cost lessless perper test test becausebecause of of reducedreducedlabourlabour requirement requirement andand lessless chancechance of of makingmaking errorserrors..


15/27

TimeTime

How much time can be spent on the test?How much time can be spent on the test?

RoutineRoutine qualityquality controlcontrol teststests needneed anan instrument instrument that that givesgives resultsresults rapidlyrapidly..

InIn contrast,contrast, somesome teststests inin thethe researchresearchlaboratorylaboratory maymay bebe soso sophisticatedsophisticated that that thetheamount amount of of timetime requiredrequired toto obtainobtain reliablereliable datadata

isis not not of of great great consequenceconsequence. .

ResearchResearch needsneeds maymay requirerequire measuringmeasuring a anumbernumber of of texturaltextural parameters,parameters, whichwhich willwill taketake

moremore timetime thanthan aa oneone--point point measurement measurement. .


16/27

LocationLocationWhere will the instrument be operated?Where will the instrument be operated?

Any Any instrument instrument cancan bebe usedused inin aa cleanclean drydrylaboratorylaboratory. .

InstrumentsInstruments usedused inin plantsplants maymay needneed totowithstandwithstand steam,steam, water,water, dust,dust, vibration,vibration, andandotherother hazardshazards that that renderrender somesome instrumentsinstrumentsunsuitableunsuitable. .

InstrumentsInstruments usingusing chart,chart, complexcomplex electronicelectronicsystemssystems oror computerscomputers areare likelylikely toto suffersufferdamagedamage inin steamysteamy atmosphereatmosphere of of aa processingprocessingplant plant unlessunless speciallyspecially designeddesigned toto withstandwithstand poorpoor

environment environment. .


17/27

Eliminate Unsuitable TestsEliminate Unsuitable TestsSomeSome test test principlesprinciples areare obviouslyobviously unsuitableunsuitable forforthethe commoditycommodity that that needsneeds toto bebe testedtested andandshouldshould bebe eliminatedeliminated fromfrom considerationconsideration. .

ForFor exampleexample: : extrusionextrusion test test isis unsuitedunsuited forforcrackerscrackers andand bread,bread, puncturepuncture test test worksworks poorlypoorlyonon most most brittlebrittle foods,foods, conecone penetrometerpenetrometer test test isisunsuitableunsuitable forfor fibrousfibrous materialsmaterials suchsuch asas meat meat ororrawraw vegetables,vegetables, a a snappingsnapping test test willwill not not bebe

effectiveeffective forfor flexibleflexible oror fluidfluid materialsmaterials. .

SometimesSometimes geometrygeometry of of thethe samplesample maymay imposeimposelimitationslimitations


18/27

Preliminary SelectionPreliminary SelectionTheThe next next stepstep willwill narrownarrow thethe fieldfield toto thethe most most promisingpromising twotwo oror threethree test test principlesprinciples..

It It isis advisableadvisable toto observeobserve what what typetype of of test test principleprinciple peoplepeople useuse inin sensorysensoryevaluationevaluation of of texturaltextural qualityquality byby thisthis oneone cancan get get goodgood cluesclues forfor thethe typetype of of objectiveobjective test test..

TheThe test test principlesprinciples that that shouldshould bebe consideredconsidered arearePuncturePuncture

DeformationDeformationExtrusionExtrusionPenetrationPenetrationCuttingCutting--shearshearSnappingSnappingTorsionTorsion

TryTry out out thethe instrument instrument andand continuecontinue useuse if if it it givesgives satisfactorysatisfactory results,results, if if it it failsfails toto givegive satisfactionsatisfaction itsits useuse shouldshould bebe abandonedabandoned. .

SometimesSometimes nonenone of of thethe establishedestablished proceduresprocedures givegive satisfactorysatisfactory results,results, ininthat that casecase researcherresearcher shouldshould havehave thethe confidenceconfidence toto developdevelop aa newnew test test procedureprocedure oror instrument instrument that that isis suitablesuitable forfor thethe purposepurpose. .


19/27

Final SelectionFinal SelectionByBy thisthis timetime thethe numbernumber of of principlesprinciples shouldshouldhavehave beenbeen reducedreduced toto aa smallsmall numbernumber. .

N owN ow oneone shouldshould test test eacheach of of thethe remainingremaining

principlesprinciples overover thethe fullfull rangerange of of texturestextures that that willwillnormallynormally bebe encounteredencountered. .

If If anyany principleprinciple provesproves toto bebe ineffective,ineffective,abandonabandon it it.. InIn thisthis casecase refiningrefining thethe test test isis not not goinggoing toto helphelp becausebecause anan inappropriateinappropriate test test principleprinciple isis beingbeing usedused..


20/27

Refine Test ConditionsRefine Test Conditions

TheThe finalfinal stepstep isis toto standardizestandardize thethe test test conditionsconditions suchsuch asas samplesample size,size, test test cellcelldimensions,dimensions, forceforce range,range, speedspeed of of traveltravel of of movingmoving parts,parts, chart chart speed,speed, temperature,temperature,

etcetc..SeveralSeveral variationsvariations of of test test conditionsconditions shouldshouldbebe testedtested toto findfind out out whichwhich givesgives thethe best best resolutionresolution betweenbetween different different samplessamples. .

ee..gg.. aa smallsmall deformingdeforming forceforce generallygenerally givesgives aabetterbetter resolutionresolution inin deformationdeformation teststests thanthan aahighhigh forceforce..


21/27

Some of the questions that should be addressedSome of the questions that should be addressed

Does sample size affect the test result?Does sample size affect the test result?DoesDoes thethe texturaltextural propertyproperty changechange slightlyslightly ororgreatlygreatly asas thethe temperaturetemperature changes?changes?DoesDoes thethe raterate of of compressioncompression affect affect thethe result,result,ii..ee.. isis thethe product product strainstrain raterate sensitive?sensitive?Is the product anisotropic?Is the product anisotropic?

If the product is anisotropic then it must always beIf the product is anisotropic then it must always bepresented in the same direction.presented in the same direction.

HowHow uniformuniform isis thethe product?product?A A largerlarger samplesample sizesize oror moremore replicatereplicate teststests areareneededneeded if if thethe product product isis not not uniformuniform..If If thethe texturetexture varyvary consistentlyconsistently acrossacross thethe length,length,

alwaysalways taketake thethe samplesample fromfrom samesame locationlocation..


22/27

Preparation of the samplePreparation of the sample Adequate Adequate samplesample preparationpreparation isis ananimportant important element element inin foodfood texturetexturemeasurementsmeasurements. .

ProblemsProblems withwith samplesample preparationpreparationsometimessometimes impelimpel thethe researcherresearcher toto useuse aaparticularparticular test test principleprinciple oror instrument instrument. .

TheThe samplesample selectedselected shouldshould beberepresentativerepresentative of of thethe lot lot fromfrom whichwhich it it hashas

beenbeen drawndrawn..


23/27

Some useful tips .Some useful tips .A A corkcork borerborer isis suitablesuitable forfor cuttingcutting out out cylinderscylinders.. MakeMake suresure thetheborerborer isis kept kept sharpsharp. . Apply Apply aa light light uniformuniform pressurepressure whenwhen cuttingcutting

becausebecause anan unevenuneven diameterdiameter isis obtainedobtained if if thethe pressurepressure isis not not steadysteady. .

A A sharpsharp knifeknife isis usefuluseful forfor cuttingcutting manymany foodsfoods.. A A backback andand forthforthsawingsawing motionmotion underunder gentlegentle pressurepressure givesgives betterbetter controlcontrol of of dimensionsdimensions. .

A A smallsmall sawsaw withwith veryvery finefine teethteeth isis usefuluseful forfor cuttingcutting hardhard fracturablefracturablematerialsmaterials toto sizesize.. UseUse sawsaw bladeblade 66 longlong withwith 3232 teethteeth perper inchinch..

A A wirewire cuttercutter isis goodgood forfor shapingshaping adhesiveadhesive foodsfoods suchsuch asas soft soft cheesecheese. .

A A circularcircular cookiecookie cuttercutter isis helpfulhelpful forfor cuttingcutting dumbbelldumbbell shapesshapessuitablesuitable forfor aa tensiletensile test test..

A A boxbox inin conjunctionconjunction withwith sharpsharp knife,knife, aa smallsmall sawsaw oror aa wirewire cuttercutterhelpshelps inin cuttingcutting samplessamples toto aa standardstandard lengthlength andand cuttingcutting uniformuniform

cubescubes..


24/27

Some foods cannot be shaped .Some foods cannot be shaped .

It It isis impossibleimpossible toto cut cut thethe headhead of of lettuce,lettuce, aapeanut,peanut, oror aa potatopotato chipchip toto aa standardstandard geometrygeometrywithout without destroyingdestroying thethe integrityintegrity of of thethe samplesample asasaa wholewhole..

InIn thesethese cases,cases, oneone shouldshould select select unitsunits of of asasuniformuniform shapeshape andand sizesize asas possiblepossible..

If If possiblepossible aa nonnon--destructivedestructive test test shouldshould bebe usedusedforfor thesethese foodsfoods becausebecause thethe samesame unit unit cancan beberepeatedlyrepeatedly testedtested asas it it undregoesundregoes thetheexperimentalexperimental treatmentstreatments whilewhile thethe geometrygeometryfactorfactor remainsremains constant constant. .


25/27

CalibrationCalibrationInIn thethe past,past, texturetexture measurement measurement waswas oftenoften consideredconsidered

toto bebe satisfactorysatisfactory soso longlong asas it it gavegave consistent consistent resultsresults at at oneone locationlocation but but thisthis attitudeattitude isis nono longerlonger adequateadequate. .

CalibrationCalibration isis becomingbecoming aa mattermatter of of increasingincreasingimportanceimportance toto ensureensure that that thethe samesame qualityquality product product receivesreceives exactlyexactly thethe samesame measurementsmeasurements nono mattermatterwherewhere it it isis beingbeing testedtested. .

A A strongstrong effort effort shouldshould bebe mademade toto standardizestandardize everyeveryaspect aspect of of test test toto ensureensure that that resultsresults areare comparablecomparablebetweenbetween laboratorieslaboratories. .

A A writtenwritten protocolprotocol shouldshould bebe developeddeveloped givinggiving everyeverydetaildetail..


26/27

TheThe mainmain problemproblem inin standardizingstandardizing manymany instrumentsinstruments isishehe frictionfriction betweenbetween thethe movingmoving partsparts of of thethe test test cellscellsandand thethe slipslip inin thethe rotationalrotational viscometersviscometers. .

InIn aa singlesingle instrument,instrument, thethe frictionfriction maymay varyvary fromfrom test test tototest test forfor severalseveral reasonsreasons: :

WorkingWorking partsparts maymay bebe bent,bent, twisted,twisted, dented,dented, oror otherwiseotherwisemisalignedmisaligned duringduring thethe test test..FrictionalFrictional forceforce isis not not constant constant throughout throughout thethe workingworking strokestroke..ParticlesParticles of of food,food, especiallyespecially skinskin andand fibers,fibers, maymay jam jam betweenbetweenthethe movingmoving partsparts causingcausing aa temporarytemporary increaseincrease inin frictionfriction..LiquidLiquid comingcoming fromfrom thethe foodfood maymay act act asas aa lubricant,lubricant, causingcausing aatemporarytemporary decreasedecrease inin frictionfriction..FoodFood materialmaterial cancan buildbuild upup onon thethe workingworking partsparts andand increaseincreasethethe frictionfriction if if thesethese areare not not thoroughlythoroughly cleanedcleaned afterafter eacheach test test..

DegreeDegree of of errorerror causedcaused byby frictionfriction cannot cannot bebestandardizedstandardized. . ThisThis isis compellingcompelling reasonreason toto givegivepreferencepreference toto thethe test test cellcell geometriesgeometries inin whichwhich therethere cancanbebe nono frictionfriction betweenbetween thethe partsparts of of thethe test test cellcell..


27/27

ThanksThanks

Selection of Suitable Test Procedure

Documents

Transcript of Selection of Suitable Test Procedure