BROOKFIELD LFRA TEXTURE ANALYZER Operating Instructions Manual No. M/05-370-A1205 SPECIALISTS IN THE MEASUREMENT AND CONTROL OF VISCOSITY BROOKFIELD ENGINEERING LABORATORIES, INC. 11 Commerce Boulevard, Middleboro, MA 02346-1031 USA TEL 508-946-6200 or 800-628-8139 (USA only) FAX 508-946-6262 INTERNET www.brookfieldengineering.com Brookfield Engineering Labs., Inc. Page 1 Manual No.
TABLE OF CONTENTS I. INTRODUCTION ................................................................................................................................. 3 I.1 I.2 I.3 I.4 I.5 I.6 I.7 I.8 Components ................................................................................................................ 3 Utilities ....................................................................................................................... 4 Units ...............................................
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.
I.2 Utilities Input Voltage: Input Frequency: Power Consumption: Fuse: 115 VAC or 230 VAC 50/60 Hz 150 VA Two 4 amp, 5 x 20mm, Time-lag Power Cord Color Code: United States Hot (live) Neutral Ground (earth) Outside United States Black White Green Brown Blue Green/Yellow Main supply voltage fluctuations are not to exceed ±10% of the nominal supply voltage. I.3 Units The LFRA Texture Analyzer uses the SI system of units for all parameters.
Position: Range: 0-75 mm Resolution: 0.1mm Accuracy: 0.1mm Output: Computer: RS232 Compatible Serial Port Environmental Conditions: 0°C to 40°C temperature range (32°F to 104°F) 20% - 80% relative humidity, non-condensing atmosphere I.5 Installation 1) Prepare a clean, level surface. 2) Unpack and remove the LFRA Texture Analyzer from the shipping container. The LFRA Texture Analyzer weighs 15 kg (33 pounds). Use caution when lifting the unit out of the packaging.
I.6 Safety Symbols 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.
I.7 Key Functions The LFRA Texture 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. Display START Keypad 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.
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.
III. OPERATION III.1 Principle The Brookfield LFRA Texture 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 to conduct a test. III.2 Emergency Stop The LFRA Texture Analyzer can operate with up to 4500g (4.
III.3 Base 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 Fine Adjust Nut, see Figure III.2. Base Table Fine Adjust 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).
III.4 Probes There are a range of probes available for use with the LFRA Texture 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.
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.
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.
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. A test may be repeated by simply pressing the Start button while viewing the results.
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 button. Note: The Start button may be used to zero the LFRA at any time during the Static Load test. If you remove the weights and Hanger and the display does not return to zero, press Start to zero.
Example of Calibration Verification 1000 gram LFRA Texture Analyzer, accuracy according to Table III.2, ±5 grams, 1500 gram calibrated weight set Weight Hanger 150 500 Calibrated Value 100g 150g 495g Brookfield Engineering Labs., Inc. Total Weight 100g 250g 745g Page 16 Measured Value -100.0g -249.5g -744.0g Result pass pass pass Manual No.
IV. TEST METHOD DEVELOPMENT The measurement results provided by the LFRA Texture Analyzer will be dependent on several 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.
Within a probe category, variations of geometry can be significant. It may require a larger force to drive a cone of shallow angle as compared to a cone of steep angle. Similarly, a cylinder of large diameter may require a larger force than a cylinder of small diameter. The selection of the probe (type and size) will affect the test result. IV.3 Test Parameters The LFRA Texture Analyzer will require the setting of several parameters depending upon the test method selected (see Table III.1).
V. APPLICATIONS This applications section should be used as a guide to the development of techniques specific to your own application and requirement. These notes are empirical in nature. Deviation from the described test configurations (parameter settings, sample size, shape, formulation, etc.) will result in deviations from the observations discussed in each application. V.1 Comparison of Low Fat and Virtually Fat Free Yogurt Consistencies PRODUCT: Low fat (1%) and virtually fat free (0.
was left between the sample surface and the base of the probe. This was left to ensure that a break between probe:sample interface was made and that true adhesiveness characteristics could be calculated. NOTE: Samples were tested with original containers as supplied. Use of different dimension holding vessels will change results obtained, therefore, operators must be consistent with test configuration imposed.
PARAMETER COLLECTION: All parameters were automatically calculated within the Analyze a test with tables window. It is therefore necessary to calculate parameters for each curve individually and record results.
Sample conditions which will effect results generated: 1. Fat content 2. Protein content 3. pH 4. Set/Stirred product 5. Syneresis and surface characteristics 6. Presence of inclusions e.g. fruit RELATED TESTS: 45° cone penetrometer test utilizing hold until time function to determine relaxation. BIBLIOGRAPHY AND REFERENCES: Anon. 1988. Facts About Yogurt. National Dairy Council, London. Anon. 1996. Yogurt: A Technical Profile. National Dairy Council, Education Department. Bylund, G. 1995.
PROBE REF: 2mm stainless steel cylinder probe (REF: TA39) METHOD: Biscuits approximately 6mm thick were located beneath the probe and clamped to the analyzer bed using low pressure clips. The probe then penetrated sample to target distance and the profile of characteristics was recorded through the interface package.
PARAMETERS: HARDNESS Force necessary to attain a given deformation CONSISTENCY Internal strength of bonds within a product CRISPINESS Internal ruptures and fracture of sample as structure is broken Indicative of sample hardness and internal bond strength RESULTS: Chocolate Plain 736 633.9 2460.2 1.16 973 657.5 3917 1.
LFRA SETTINGS: MODE: PLOT: SPEED: DISTANCE: OPTION: TRIGGER: Measure force in compression Final 0.1mm/s-1 2; 4; 6mm Normal Auto 4g pre-set PROBE REF: Stainless steel needle probe 10° Taper (Ref: TA9) Confectionery holding rig METHOD: Samples were removed from wrappers and broken into individual chunks. The individual chocolate piece was then held within jaws of confectionery holder clamped to adjustable bed of LFRA approximately 2mm below surface probe.
RESULTS: PARAMETER HARDNESS CONSISTENCY ADHESION FORCE ADHESIVENESS UNIT 2mm 4mm 6mm (g) (gs) (g) 334 3192.3 -18 722 1278.6 -60 1159 23878.9 -15.1 (gs) -0.4 -4.1 -180 where: gs = work NOTE: Adhesion forces give greatest differentiation. CONCLUSIONS: This empirical procedure generates key information related to the parameters of chocolate hardness and consistency, while additional information relating to adhesion is also formed.
Appendix A - Probes and Fixtures Probes Standard Probe kit comes complete with the following probes: Cylindrical TA4/1000 TA5 TA10 TA11/1000 General TA25/1000 TA39 TA41 TA44 Spherical TA18 TA43 Special Purpose TA26 TA7 TA9 Conical TA2/1000 TA15/1000 TA17 Figure A-1: Part No. A-P-KIT2, Standard Probe Kit. Includes: Cylinder, Conical, Spherical, and General Probes with Carrying Case Cylinder Probes TA3/100 25.4 mm D, 35 mm L, Clear Perspex (low mass) TA3/1000 25.
Conical Probes TA2/100 60°, 30 mm D, Clear Perspex (low mass) TA2/1000* 60°, 30 mm D, Clear Perspex TA15/100 45°, 30 mm D, Clear Perspex (low mass) TA15/1000* 45°, 30 mm D, Clear Perspex TA16 40°, 28 mm D, Clear Perspex TA17* 30°, 25 mm D, Clear Perspex TA27 20°, 12 mm D, Clear Perspex TA29 15°, 8 mm D, Stainless Steel TA32/100 90°, 30 mm D, Clear Perspex (low mass) TA32/1000 90°, 30 mm D, Clear Perspex Spherical Probes TA8 6.35 mm D, Stainless Steel TA18* 12.
Appendix B - Troubleshooting If no power to the instrument: Check: • User replaceable fuses: two (2) fuses, 4 amp, 5 x 20mm, time-lag • Fuses located within power entry module on the rear of the instrument. • If fuses blow continually, serious damage to the instrument could result. Contact repair services immediately.
Appendix C - Warranty and Repair Service Warranty Brookfield Texture Analyzers are guaranteed for one year from date of purchase against defects in materials and workmanship. The Texture Analyzer must be returned to Brookfield Engineering Laboratories, Inc. or the Brookfield dealer from whom it was purchased for no charge warranty service. Transportation is at the purchaser’s expense. For repair or service in the United States, return to: Brookfield Engineering Laboratories, Inc.
