Brookfield LFRA Texture Analyzer User Manual

BROOKFIELD LFRA

TEXTURE ANALYZER

Operating Instructions

Manual No. M/05-370-B0507

SPECIALISTS IN THE

MEASUREMENT AND

CONTROL OF VISCOSITY

with offices in: Boston • Chicago • London • Stuttgart • Guangzhou

BROOKFIELD ENGINEERING LABORATORIES, INC.

11 Commerce Boulevard, Middleboro, MA 02346 USA

TEL [phone]	or 800-628-8139 (USA		excluding MA)
FAX [phone]	INTERNET http://www.brookfieldengineering.com
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	TABLE OF CONTENTS
I. INTRODUCTION....................................................................................................................................................................................		3
I.1	Components..................................................................................................................	3
I.2	Utilities.........................................................................................................................	4
I.3	Units.............................................................................................................................	4
I.4	Specifications...............................................................................................................	4
I.5	Installation....................................................................................................................	5
I.6	Safety Symbols and Precautions..................................................................................	6
I.7	Key Functions..............................................................................................................	7
I.8	Cleaning.......................................................................................................................	7
II.QUICK START.........................................................................................................................................................................................		8
III. OPERATION.........................................................................................................................................................................................		9
III.1	Principle..........................................................................................................................	9
III.2	Emergency Stop..............................................................................................................	9
III.3	Base Table.....................................................................................................................	10
III.4	Probes...........................................................................................................................	11
III.5	Fixtures / Jigs................................................................................................................	11
III.6	Operating Menu............................................................................................................	11
III.7	Running A Test.............................................................................................................	13
III.8	Results..........................................................................................................................	14
III.9	Checking Calibration....................................................................................................	14
IV. TEST METHOD DEVELOPMENT...............................................................................................................................................		17
IV.1	Sample Preparation.......................................................................................................	17
IV.2	Test Probe / Fixture.......................................................................................................	17
IV.3	Test Parameters.............................................................................................................	18
IV.4 Recommendations.........................................................................................................		18
V. APPLICATIONS................................................................................................................................................................................		19
V.1	Comparison of Low Fat and Virtually Fat Free Yogurt Consistencies...........................	19
V.2 A Comparison of the Textural Characteristics of Biscuits (Cookies).............................		22
V.3 Review of Solid Chocolate Tablet at Ambient Temperature .........................................		24
Appendix A - Probes and Fixtures...............................................................................................		27
Appendix B - Troubleshooting....................................................................................................		29
Appendix C - Use with TexturePro Lite Software......................................................................		30
Appendix D - Warranty and Repair Service................................................................................		46

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I.INTRODUCTION

The Brookfield LFRA Texture Analyzer measures the resistance of a material to an applied force.

The force is applied through a vertical compression of the sample and the resistance is measured through a load cell. This resistance can be interpreted to provide a measure of the texture or other physical characteristics of the material.

The LFRA Texture Analyzer is the most recent development of the original Boucher Jelly Tester.

This original product was created as the Stevens Texturemeter evolving into the CNS Farnell LFRA

TA (Leatherhead Food Research Association Texture Analyzer). Brookfield’s enhanced design maintains the characteristics of the original equipment while expanding the measurement capabilities and ease of use by incorporating modern digital technology.

The principle of operation of the LFRA Texture Analyzer is to drive a probe into a material. The resistance of the material to this compression is measured by a calibrated load cell and reported in units of grams on the instrument display. The measured load will be a function of the probe geometry, speed of compression, test method, and sample preparation.

There are four load cell ranges available for the LFRATexture Analyzer offered by Brookfield:

Model	Load Cell Range (grams)
LFRA-100	100g
LFRA-1000	1000g
LFRA-1500	1500g
LFRA-4500	4500g

Higher load cell ranges are used for testing materials with a stronger structure.

I.1Components

Please check to be sure that you have received all components, and that there is no damage. If you are missing any parts, please notify Brookfield Engineering or your local Brookfield agent

immediately. Any shipping damage must be reported to the carrier.
Part Number		Quantity
	Component		Part Number	Quantity
	LFRATexture Analyzer		varies	1
Probe			varies	per order
Operating Manual			M05-370	1
Power Cord				1
	115 Volt or		DVP-65	1
	230 Volt		DVP-66
	Optional
	Bloom Strip		TA-CS-100 or	1
			TA-CS-1000
Calibration Weight Set (1)			TA-CW-100C, -1000C, -1500C, -4500C	1
Standard Probe kit			TA-P-KIT2	1
TexturePro Lite Software			TA-T-PRO	1

Note: 1. Optional components may include probes or fixtures. See Appendix A for details.

2. See III.9 for Calibration Checking (pg. 14).

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I.2

Utilities

Input Voltage:

115 VAC or 230 VAC

Input Frequency:

50/60 Hz

Power Consumption:

150 VA

Fuse:

Two 4 amp, 5 x 20mm, Time-lag

Power Cord Color Code:

United States

Outside United States

Hot (live)

Black

Brown

Neutral

White

Blue

Ground (earth)

Green

Green/Yellow

Main supply voltage fluctuations are not to exceed ±10% of the nominal supply voltage.

I.3Units

The LFRATexture Analyzer uses the SI system of units for all parameters.

Parameter

Unit

Abbreviation

Load

Grams

g

Distance

Millimeter

mm

Time

Seconds

s

Speed

Millimeter per second

mm/s

Specifications

I.4

Load:

Range

Resolution

Model

Grams

Grams

Accuracy*

LFRA-100

0-100

0.01

±0.5%FSR

LFRA-1000

0-1000

0.10

±0.5%FSR

LFRA-1500

0-1500

0.20

±0.5%FSR

LFRA-4500

0-4500

0.50

±0.5%FSR

FSR = Full Scale Range

*This value applies to the complete range of operating temperatures as defined in Section I.4

(Environmental Conditions). This value will be improved if the environment is held to a stable temperature.

Trigger Point:	Range	Resolution
Model	Grams	Grams
LFRA-100	0.1-10	0.01
LFRA-1000	0.2-100	0.10
LFRA-1500	0.2-150	0.10
LFRA-4500	0.6-500	0.10

Speed: 0.1 to 1.0 mm/s in increments of 0.1 mm/s

1 to 10 mm/s in increments of 1 mm/s

Accuracy: ±0.1% of setpoint

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Position:	Range: 0-75 mm
	Resolution: 0.1mm
	Accuracy: 0.1mm
Output:	Computer: RS232 Compatible Serial Port
Environmental	0°C to 40°C temperature range (32°F to 104°F)
Conditions:	20% - 80% relative humidity, non-condensing atmosphere

I.5Installation

1) Prepare a clean, level surface.

NOTE: This instrument is a sensitive load measuring device. It should be installed on a clean, solid and level bench surface which is free from external vibrations.

2) Unpack and remove the LFRATexture Analyzer from the shipping container.

The LFRATexture Analyzer weighs 15 kg (33 pounds). Use caution when lifting the unit out of the packaging.

3)Place the LFRA Texture Analyzer on a sturdy, level surface. Adjust the four feet to ensure that the instrument is stable.

4)Remove any additional components from the shipping package. Save the shipping container and packaging for future use.

5)Make sure that theAC power switch at the rear of the LFRATextureAnalyzer is in the OFF position. Connect the power cord to the socket on the back panel of the instrument and plug it into the appropriate AC line. Position instrument so that the power cord can be removed easily.

The AC input voltage and frequency must be within the appropriate range as shown on the model and serial tag of the instrument (located on the back of the LFRA).

The LFRATexture Analyzer must be earth grounded to ensure against electronic failure!

6)If appropriate, connect interconnecting cable which is supplied withTexturePro Lite software to the serial port for connection to a computer.

7)Turn the power switch to the ON position. The startup screen will indicate the firmware version and load range of the LFRA (Figure II.1).

LFRA VERSION X.X TEXTURE ANALYZER 1000 GRAM UNIT INITIALIZING

Figure I.1

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8)Allow the instrument to warm up for 10 minutes. Check calibration according to Section III.8.

I.6SafetySymbols and Precautions

Safety Symbols

The following explains safety symbols which may be found in this operating manual.

Indicates hazardous voltages may be present.

Refer to the manual for specific warning or caution information to avoid personal injury or damage to the instrument.

Precautions

If this instrument is used in a manner not specified by the manufacturer, the protection provided by the instrument may be impaired.

This instrument is not intended for use in a potentially hazardous environment.

In case of emergency, turn off the instrument and then disconnect the electrical cord from the wall outlet.

The user should ensure that the substances placed under test do not release poisonous, toxic or flammable gases or liquids at the temperatures which they are subjected to during the testing.

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I.7Key Functions

The LFRATexture Analyzer is operated through two keys and a knob located on the keypad.

Additionally, there is an emergency stop button located on the base.

RESET / STOP

This key is used to stop a test in progress.

START

This key is used to start the test. During the descent of the probe, prior to the trigger point, this key can be used to accelerate the rate of descent.

SELECT / SCROLL

This knob has multiple functions:

1.The knob is pressed to select the option currently displayed.

2.The knob is rotated to vary the value of the parameter being selected.

3.During a test, pressing this knob will display test parameters.

EMERGENCY STOP

This button is used to abort a test in case of an emergency condition.

I.8Cleaning

Display

Keypad

Base Table

Emergency Stop

Figure I.2

Instrument and Keypad:	Clean with a dry, nonabrasive cloth. Do not use solvents
	or cleaners.
Probes and Fixtures:	Probes and fixtures are made from a variety of materials
	from metals (stainless steel, aluminum) to plastics (acetate,
	Perspex, Nylon). Clean with a nonabrasive cloth using
	solvents that are appropriate for both the sample material
	and the material of the probe and/or fixture.

Do not apply excessive upward, downward or sideways force to probe while fixed to

LFRA. Damage may occur to the load cell.

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II.QUICK START

1.Unpack the instrument according to Section I.5.

2.Attach the selected probe. See Section IV.2 for more information.

3.Place the sample on the base table. Adjust the table height so that the surface of the sample is within 5 mm of the probe (see Section III.3).

4.Set the test mode to Normal See Section III.6 for more information.

5.Set the trigger value to 0.5% of the load cell range. For example, use 5g for a 1000g load cell instrument.

6.Set the test speed and distance. See Section IV.3 for more information.

7.Press the START button.

8.Record the Peak Load and/or Final Load in grams.

9.Clean the probe and remove sample.

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III. OPERATION

III.1Principle

The Brookfield LFRATexture Analyzer drives a probe through a set distance at a set speed into a sample material that is placed (or fixed) on the base table. The LFRA offers a variety of probes, fixtures, and test parameters to provide the user with a range of options for evaluating the texture of a sample material. The following section describes the use of the LFRA.

III.2Emergency Stop

The LFRATexture Analyzer can operate with up to 4500g (4.5 kg) of force dependent on load cell. Be sure to place only the sample for test under the probe. Keep body parts and clothing away from the probe during the test.

The LFRATexture Analyzer uses a compression force to evaluate a material. The user must take care not to place any body part or clothing in the compression zone. The LFRATexture Analyzer is provided with an Emergency Stop Button for use in case of an operational problem.

Pressing the Emergency Stop Button will cause three immediate actions: 1) Stop the test in progress. 2) Return the probe to the top most position. 3) Reset the LFRA to the Emergency Stop display, Figure III.1.

EMERGENCY STOP

RESET EMERGENCY STOP

Figure III.1

The Emergency Stop condition can be canceled by rotating the Emergency Stop Button clockwise. This will reset the LFRA firmware to the power up condition.

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III.3Base Table

The Base Table is designed to provide quick adjustment of the sample height. There are two methods of adjustment; the Locking Knob and the Locking Nut, see Figure III.2.

Base Table

Locking Nut

Base Table Post

Locking Knob

Figure III.2

The Locking Knob is used to fix the Base Table in position. To loosen the knob, turn counterclockwise. When the knob is loose, the table may be moved vertically. To tighten the knob, turn clockwise (tighten the knob only finger tight). The height of the table may be varied by 49mm through the Locking Knob.

The Fine Adjust Nut is used to secure the rotational adjustment of the Base Table. The height of the table may be varied by 70mm when the nut is loose. To raise the table, turn the Base Table counter clockwise (when looking down on to the table); to lower the table, turn the Base Table clockwise. To secure the height of the Base Table, turn the Fine Adjust Nut clockwise until it is tight against the Base Table post.

Prior to a test the Base Table should be adjusted so that the sample material is within 5 mm of the probe. When this height is established, tighten the Fine Adjust Nut. Use the Locking Knob to move the Base Table up and down to allow for the sample to be introduced prior to test and removed upon completion of test (tighten the knob only finger tight).

Always hold the Base Table with one hand while loosening the Locking Knob. This will prevent the Base Table from falling abruptly to the LFRA housing.

Keep fingers away from the Fine Adjust Nut when lowering the Base Table to prevent a pinch injury.

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III.4Probes

There are a range of probes available for use with the LFRATexture Analyzer (see Appendix A). All probes are configured with a right hand thread to attach to the LFRA. Attach the probe with care to prevent damage to the threads. Do not overtighten!

The probes may be cleaned while attached to the LFRA. Follow recommendations in Section I.8.

Do not apply excessive upward, downward or sideways force. Damage may occur to the load cell.

III.5Fixtures / Jigs

There are a range of fixtures / jigs available for use with the LFRATexture Analyzer (see Appendix A). These devices are designed to hold a sample in place during measurement. Each fixture / jig is designed to attach to the Base Table. Refer to the instructions provided with the fixture / jig for proper installation.

Note: Brookfield can design custom fixtures/jigs to meet your application. Contact Brookfield or our authorized dealer for details.

III.6Operating Menu

The LFRATexture Analyzer offers four (4) test modes and one (1) calibration mode. Each test mode requires parameters to be set. These parameters, once set, will be maintained by the LFRA during a power down to facilitate repetitive testing. The test mode used prior to a power down will be presented on the screen at the next power up.

All test mode selection and parameter setting is done using the Select/Scroll knob (see Figure I.2). This knob is both rotated and pressed during normal operation.

The first line of the instrument display identifies the test mode: Normal, Hold Time, Cycle Count, Bloom; or calibration mode: Static Load (Figure III.3). The user may scroll through these choices by rotating the Select / Scroll knob (either clockwise or counter clockwise). A test mode is selected by pressing the Select / Scroll knob.

TEST:	NORMAL
TRIGGER:		5.0 (g)
DISTANCE:		3.0 (mm)
SPEED		6.0 (mm/s)

Figure III.3

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Once the test mode is selected the test parameters must be set.

•Normal requires:	Trigger, Distance, Speed.
•Hold Time requires:	Time, Trigger, Distance, Speed.

•Cycle Count requires: Count, Trigger, Distance, Speed. •Bloom is a fixed test with preset parameters.

•Static Load is for verifying calibration and does not require any parameters.

The test parameters are defined as follows:

Trigger: The load, in grams, measured by the LFRA to indicate that the probe is in contact with the sample. Once the trigger value is reached, the test will begin at the defined speed. Brookfield recommends a trigger value of 0.5% of the load cell range. For example, use 5g trigger with a 1000g load cell instrument.

Distance: The total downward distance the probe will travel once the trigger value is reached.

Speed: The speed at which the probe will travel the specified distance.

Time: The number of seconds that the probe will be held at the defined distance during a Hold Time test.

Count: The number of cycles (Speed and Distance) that will be applied to the sample during a Cycle Count test.

The parameters must be set within the ranges shown in Table III.1.

Parameter

100g

1000g

1500g

4500g

Trigger

0.1

– 10g

0.2

– 100g

0.2

– 150g

0.6

– 500g

Distance

0.1

– 75mm

0.1– 75mm

0.1

– 75mm

0.1

– 75mm

Speed

0.1

– 10 mm/s

0.1

– 10 mm/s

0.1

– 10 mm/s

0.1

– 10 mm/s

Hold Time

0

– 9999 s

0

–

9999 s

0

– 9999 s

0

– 9999 s

Cycle Count

0

– 99

0

–

99

0

– 99

0

– 99

Table III.1

Define a test by first selecting a test mode. Rotate the Select / Scroll knob until the required test mode is displayed, then press the Select / Scroll knob to confirm your choice. As the test modes are displayed, the parameters specific to that mode will be shown with the previously selected parameters.

Once a test mode is selected, the cursor will move to the first parameter. You may either select that parameter to enter new values by pressing the Select / Scroll knob or you may scroll to the next parameter by rotating the Select / Scroll knob.

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Data entry is accomplished by setting each digit individually. For example: to set a value of 57.0 as the target distance, rotate the Select / Scroll Knob until the “D” in “Distance” is blinking. Depress the Select / Scroll knob to get to the tens digit, then rotate the knob to the value 5. Depress the Select / Scroll knob again to get to the ones digit, then rotate the knob to the value 7. Depress the Select / Scroll knob to get to the tenths digit, and depress it again to leave the value at 0.

A data entry of zero in all columns for any parameter will result in that parameter being reset to the previous value. Pressing the Select / Scroll knob without first rotating it during the data entry process will result in a zero being placed in that column. This can expedite the entry of Trigger values since in most cases the first columns will be zero (004.0 grams).

III.7Running A Test

A test is initiated by depressing the Start button. The operator is reminded to attach a probe, then press Start again to zero the probe weight and begin the test. The display of test results will depend upon the type of test performed (see Figures III.4 – III.7 below).

TEST:	NORMAL
PEAK LOAD:		126.9g
FINAL LOAD:		126.9G
	Figure III.4
TEST:	HOLD TO TIME
TIME:		1s
PEAK LOAD:		67.3g
FINAL LOAD:		30.0g
	Figure III.5
TEST:	CYCLE TO COUNT
CYCLE: 5
PEAK LOAD:		46.3g
FINAL LOAD:		0.0g
	Figure III.6
TEST:	BLOOM
PEAK LOAD:		624.4g
FINAL LOAD:		624.4g

Figure III.7

Depressing the Select / Scroll knob at any time during the test will display the current test parameters. At the completion of the test, the final results will be displayed until the Start button or

Reset button is pressed. The Reset button will return the instrument to the Default Display where test mode may be selected. The Start button will begin the same test again.

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Hanger

A test may be repeated by simply pressing the Start button while viewing the results.

The test may be stopped at any time by using the Stop / Reset button or by pressing Emergency Stop. We recommend that the Stop / Reset button be used for normal operation. The Emergency Stop is intended for emergency use only.

III.8Results

Two parameters will be displayed at the conclusion of a test: Peak Load and Final Load. Both

Peak and Final Load are displayed in units of grams (g). The Peak Load is the highest load value recorded during the test. The Final Load is the last load value recorded during the downward travel of the probe. It is possible for the Peak Load to be higher than the Final Load; for example, a material with an outer skin such as an apple will show a very high value when the probe penetrates the skin and a lower value during the remainder of the test.

You may choose to record either Peak Load or Final Load or both. The determination of what data to record should be based on the nature of the sample and the ability to relate the data to the material behavior being investigated. For example, if you are interested in the hardness of the skin of the apple, then you may choose the Peak Load value. If you are interested in the ripeness of the flesh of the apple, you may choose the Final Load value.

III.9Checking Calibration

The load calibration of the LFRATexture Analyzer can be verified using the Static Load mode. We recommend that you use the Brookfield weight set appropriate for your LFRA load range:

BEL Part No.	Load Range
•TA-CW-100C	100 gram
•TA-CW-1000C	1000 gram
•TA-CW-1500C	1500 gram
•TA-CW-4500C	4500 gram	Hanger Mount

The frequency of the calibration verification should be set in accordance to your company procedures.

Start the calibration verification process by using the Select / Scroll knob to set the test mode to Static Load and then press the Start button. The display will request that you attach the Hanger Mount to the Probe Shaft (see Figure

III.8); then press Start. The LFRA must

now be zeroed by pressing the Start Figure III.8 button.

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