Brookfield LFRA Texture Analyzer Instrukcja Użytkownika Pobierz pdf (Strona 17)

Brookeld Engineering Labs., Inc. Page 17 Manual No. M/05-370-B0507

IV. TEST METHOD DEVELOPMENT

ThemeasurementresultsprovidedbytheLFRATextureAnalyzerwillbedependentonsev-

eral factors relating to the sample, the test probe, and the test parameters. A variation on any of

these elements may result in a change in measurement results. For good test repeatability it is

suggested that a clear and complete test method be developed. The following sections describe

theseelements.Itisnotpossibleforallpossibilitiestobecoveredinthisdocument;Brookeld

suggests that your method development include some trial and error testing to determine the best

test method for your sample material.

IV.1 Sample Preparation

ThemeasurementoftextureusingtheLFRATextureAnalyzerrequirescontactbetweenthetest

probe and the sample. The shape and surface of the sample may affect the measurement results.

Considerforexampleanorange:thetestofapeeledorangewilllikelygiveadifferentresult

from the test of a single wedge from the same fruit. This is likely the same for any bulk mate-

rial when compared to a neatly prepared cube of material. Consideration should be given to the

preparation of the sample to facilitate repeatability of the test. For example a material that has a

atsurfaceoffersaconsistentinterfacewiththeprobeevenifthematerialisnotcenteredinthe

testxture.Ifyourtestsampleisuneven,partofthetestmethodcouldbetocut/shape/modify

thesamplesuchthatthesampleisat;considerthedifferencebetweenaloafofbreadversusa

slice of bread.

IV.2 Test Probe / Fixture

TheLFRATextureAnalyzermaybeusedwithawidevarietyofprobesandxtures.Brookeld

offers a set of standard items while also providing special design services. Each type of probe

offersbenetsforcertainsampletypes.Thefollowingtableprovidessomebasicguidelines.

Although this table represents our general experience, it is important to note that there are no

xedrulesfortexturemeasurement.Themainobjectiveistoquantifyyourmaterialinthebest

way. This table only represents suggestions.

Probe Type Typical Application

Cylinder well dened samples with uniform surfaces,

general purpose, TPA (texture prole analysis)

Sphere samples with small scale variations on surface,

general purpose

Cone samples with rigid outer layer, often used for

penetrometry

Wire required for cutting samples

Magness Taylor required for puncturing, often used for determining

ripeness of fruit/vegetables

Extrusion Cell samples that can be made to ow, general purpose

Table V.1

1 2 ... 12 13 14 15 16 17 18 19 20 21 22 ... 45 46

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