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Decagon Devices AquaLab 4TE Operator's Manual

Water activity meter
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AquaLab
Water Activity Meter
Operator's Manual
For Series 4TE, 4TEV, DUO
Version 7
Decagon Devices, Inc.

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Summary of Contents for Decagon Devices AquaLab 4TE

  • Page 1 AquaLab Water Activity Meter Operator’s Manual For Series 4TE, 4TEV, DUO Version 7 Decagon Devices, Inc.
  • Page 2 Decagon Devices, Inc 2365 NE Hopkins Court Pullman WA 99163 (509)332-2756 fax: (509)332-5158 www.aqualab.com support@decagon.com sales@decagon.com Trademarks AquaLab is a registered trademark of Decagon Devices, Inc. ©2008-2012 Decagon Devices, Inc.

  • Page 3: Table Of Contents

    Contents 1. Introduction .........1 About this Manual ........1 Customer Support ........1 Warranty ...........2 Seller’s Liability ..........2 2. About AquaLab ......4 AquaLab Model and Options ....4 AquaLab 4 Instrument Specifi cations ..4 AquaLab 4 DUO Specifi cations ....5 How AquaLab Works ........6 AquaLab and Temperature ......6 Chilled Mirror Dewpoint Limitations ..8 3.
  • Page 4 Confi guration Tab ........19 Admin Settings ........25 Data Tab ..........30 6. Cleaning and Maintenance ..32 Cleaning the Block and Sensors ....33 Cleaning a Series 4TEV: .......34 Cleaning Procedure: .......34 Verifi cation of Calibration .......36 7. Verifi cation and Calibration ..37 Water Activity Verifi cation .......37 Verifi cation of Calibration .......39 8.
  • Page 5 How to Delete Models ......66 11. Computer Interface ....68 AquaLink RG ..........68 Using Windows Hyperterminal .....68 12. Troubleshooting ....... 70 13. Support and Repair ....83 Repair Costs ..........84 Loaner Service .........84 14. Further Reading ....... 85 Water Activity Th eory & Measurement ...85 Food Safety and Microbiology ....89 Appendix A ........

  • Page 7: Introduction

    AquaLab 1. Introduction 1. I NTRODUCTION Welcome to Decagon’s AquaLab Series 4, 4TE, 4TEV, and DUO, the industry standard for measuring water activity (a ). AquaLab is the quickest, most accurate, and most reliable instrument available for measuring water activity. Whether you are researching or work- ing on the production line, AquaLab will suit your needs.

  • Page 8: Warranty

    AquaLab 1. Introduction Phone 1-800-755-2751 (USA and Canada Only) 1-509-332-2756 International Our Customer Support and Sales Representatives are available Monday thru Friday. 1-509-332-5158 Warranty AquaLab has a 30-day satisfaction guarantee and a three-year war- ranty on parts and labor. Your warranty is automatically validated upon receipt of the instrument.
  • Page 9 AquaLab 1. Introduction operation, use, misuse, nonuse, repair, or replacement of said ma- terial and equipment, or out of the use of any method or process for which the same may be employed. Th e use of this equipment constitutes Buyer’s acceptance of the terms set forth in this warranty. Th ere are no understandings, representations, or warranties of any kind, express, implied, statutory or otherwise (including, but with- out limitation, the implied warranties of merchantability and fi tness...

  • Page 10: About Aqualab

    AquaLab 2. About AquaLab 2. About AquaLab AquaLab is the fastest and most accurate instrument for measuring water activity, giving readings in fi ve minutes or less. Its readings are reliable, providing ±0.003 a accuracy. Th e instrument is easy to clean and checking calibration is simple.

  • Page 11: Aqualab 4 Duo Specifi Cations

    AquaLab 2. About AquaLab Read Time : ≤5 min. Sample Temperature Range: 15 to 50° C Sample Temperature Accuracy: ±0.2° C Sample Temperature Resolution: 0.01° C Sample Dish Capacity: 15ml Full Operating Environment: 5 to 50° C 20 to 80% Humidity Case Dimensions: 26.7 x 17.8 x 12.7cm Weight: 3.1 Kg Case Material: Lustran 433 (ABS) with fi re retardant...

  • Page 12: How Aqualab Works

    AquaLab 2. About AquaLab How AquaLab Works AquaLab uses the chilled-mirror dewpoint technique to measure the water activity of a sample. In an instrument that uses the dewpoint technique, the sample is equilibrated with the head-space of a sealed chamber that contains a mirror and a means of detecting condensa- tion on the mirror.
  • Page 13 AquaLab 2. About AquaLab Th ere are several advantages in having a temperature-controlled wa- ter activity meter. A few major reasons are: 1. Research purposes. Temperature control can be used to study the eff ects of temperature on the water activity of a sample, make a comparison of the water activity of diff erent samples independent of temperature, and conduct accelerated shelf-life studies or other water activity studies where temperature control is critical.

  • Page 14: Chilled Mirror Dewpoint Limitations

    AquaLab 2. About AquaLab Chilled Mirror Dewpoint Limitations AquaLab’s limitation is its ability to accurately measure samples with high concentrations (typically >1%) of certain volatiles such as etha- nol or propylene glycol, which can condense on the surface of the chilled mirror.

  • Page 15: Water Activity Th Eory

    AquaLab 3. Water Activity Th eory 3. Water Activity Th eory Water is a major component of foods, pharmaceuticals, and cosmet- ics. Water infl uences the texture, appearance, taste and spoilage of these products. Th ere are two basic types of water analysis: moisture content and water activity.
  • Page 16 AquaLab 3. Water Activity Th eory Fig. 1: Water Activity Diagram—adapted from Labuza Water activity of a system is measured by equilibrating the liquid phase water in the sample with the vapor phase water in the head- space and measuring the relative humidity of the head-space. In the AquaLab, a sample is placed in a sample cup which is sealed inside a sample chamber.
  • Page 17 AquaLab 3. Water Activity Th eory In addition to equilibrium between the liquid phase water in the sample and the vapor phase, the internal equilibrium of the sample is important. If a system is not at internal equilibrium, one might measure a steady vapor pressure (over the period of measurement) which is not the true water activity of the system.

  • Page 18: Water Potential

    AquaLab 3. Water Activity Th eory cause condensation. Th e AquaLab warns the user if a sample is more than 4°C above the chamber temperature, but for high water activity samples the operator needs to be aware that condensation can occur if a sample that is warmer than the block is put in the AquaLab.

  • Page 19: Sorption Isotherms

    AquaLab 3. Water Activity Th eory separated from pure water by a semi-permeable membrane, water tends to move from the pure water side through the membrane to the side with the added solute. If suffi cient pressure is applied to the solute-water mixture to just stop the fl ow, this pressure is a measure of the osmotic potential of the solution.
  • Page 20 AquaLab 3. Water Activity Th eory called the sorption isotherm, and is unique for each product. Besides being unique to each product, the isotherm changes depending on whether it was obtained by drying or wetting the sample. Th ese fac- tors need to be kept in mind if one tries to use water content to infer the stability or safety of a product.

  • Page 21: Getting Started

    AquaLab 4. Getting Started 4. Getting Started Components of your AquaLab Your AquaLab should have been shipped with the following items: • AquaLab water activity meter • Calibration Certifi cate • Power cord • RS-232 interface cable • 100 disposable sample cups •...

  • Page 22: Preparing Aqualab For Operation

    AquaLab 4. Getting Started Preparing AquaLab for Operation After fi nding a good location for your AquaLab, plug the power cord into the back of the unit. Th e ON/OFF switch is located on the lower left corner of the AquaLab’s back panel. When the AquaLab is turned on, you should see a model name/number screen and then the main screen as shown below.
  • Page 23 AquaLab 4. Getting Started If users have been setup on the instrument, the following screen will appear instead of the main screen. (See Chapter 5 for more informa- tion on administrative settings and user setup). Select the appropriate user and login to begin.

  • Page 24: Menus

    AquaLab 5. Menus 5. Menus At the top of the display screen there are three tabs: Measurement, Confi guration, and Data. Th ese tabs indicate the three menus you can access. To change between the tabs press the right most button below the document icon.

  • Page 25: Confi Guration Tab

    AquaLab 5. Menus Pushing the right or left arrow keys will change the display to a temperature equilibration screen shown below. Th is screen shows the temperature diff erence between the sample temperature and the lid temperature. Confi guration Tab When at the confi guration screen, pressing the up and down arrow keys moves the cursor through the various confi guration options Press the left and right arrows to page through the options.
  • Page 26 AquaLab 5. Menus Calibration: Pressing the Enter button when Calibration is highlighted starts the verifi cation process. For more details on the water activity verifi ca- tion procedure refer to Chapter 7. Refer to Chapter 10 for moisture content verifi cation information (Duo model only). You may also reset the calibration to the factory defaults by highlighting the De- faults option and pressing Enter.
  • Page 27 AquaLab 5. Menus Temp Eq: Th e Temperature Equilibration option allows you to set the level of temperature equilibration desired before the water activity measure- ment begins. Th e range is 0.5 to 4.0°C. A setting of 4.0°C begins the measurement immediately (assuming the sample is not >4.0°C above or below the block temperature).
  • Page 28 AquaLab 5. Menus Mode: Users may choose between single, continuous, or custom mode by pushing the save button. Single Mode Single mode reads the sample once, after which the instrument noti- fi es you that it is fi nished and the water activity and temperature are displayed on the screen.
  • Page 29 AquaLab 5. Menus ments memory, but only the fi nal reading will appear on the main measurement screen. If AquaLab is connected to a computer using AquaLink RG (See Chapter 11), all readings taken during a cus- tom mode test will be downloaded to the AquaLink RG software. On the mode screen, at the top of the page, will appear the current mode settings with the number of tests appearing fi rst, followed by the stability value (Δa...
  • Page 30 AquaLab 5. Menus To change the stability setting, use the right/left arrow buttons to highlight the number under Δa , and then use the up and down but- tons to change to any value between 0.0005 and 0.0200. To save the settings and fi nish, press the save button (to exit without updating, press the cancel button).

  • Page 31: Admin Settings

    AquaLab 5. Menus Regional Formatting: Allows you to confi gure how all Series 4 models will display infor- mation. You may choose the temperature scale (Celsius vs Fahren- heit), the date display (mm/dd/yy vs. dd/mm/yy), the hour format (12 vs 24 hour) and the language. Admin Settings Allows you to create an administrator password as well as create, edit and delete additional users.
  • Page 32 AquaLab 5. Menus Th e admin option allows the administrator to grant or block access to some or all of the confi guration options in all Series 4 models. For example: If the administrator wanted to make sure that all samples were read at 25°C the administrator would set their temperature to 25°C and then would lock all other users out of that confi guration screen.
  • Page 33 AquaLab 5. Menus User Setup: Users can be added, edited or deleted from this screen. An alphabet screen will appear where a name can be entered using lower case, upper case and accents. NOTE: User setup is not required for instrument operation. It is in place for users wanting to be compliant with 21 CFR Part 11 or who want to maintain the settings they have selected.
  • Page 34 AquaLab 5. Menus ing the arrow buttons to highlight the letter and then pressing the “Check” icon button. Press the save icon to save this data record with the name you have specifi ed. NOTE: Pressing the save icon button without giving it a name will save the reading without a name.
  • Page 35 AquaLab 5. Menus For the capacitance sensor (TEV Models only) it provides you lid, base, and sample temperatures, relative humidity, as well as the ca- pacitive sensor calibration. About: Th is screen provides important information including the serial number and code version of your instrument.

  • Page 36: Data Tab

    AquaLab 5. Menus Data Tab View: Th is selection will allow you to view your stored measurements. Th e up/down arrows will move you through the stored data with the most recent measurements at the top of the table. You may also press the left and right arrows to page quickly through the data.
  • Page 37 AquaLab 5. Menus Th e information shown is the water activity of the sample, the tem- perature, the test time, the user who ran the test (if setup), the date of the reading, the sensor used (4TEV only), the time the reading was taken, and the sequence number of the stored reading.

  • Page 38: Cleaning And Maintenance

    AquaLab 6. Cleaning and Maintenance 6. Cleaning and Maintenance Keeping your AquaLab clean is vital to maintaining the accuracy of your instrument. Dust and sampling debris can contaminate the sampling chamber and must therefore be regularly cleaned out. To clean your instrument, carefully follow these instructions and refer to the labeled diagram below.

  • Page 39: Cleaning The Block And Sensors

    AquaLab 6. Cleaning and Maintenance Purpose Th e purpose for the cleaning procedure is to remove grease, dirt and other soluble substances which can absorb/release water during veri- fi cation, calibration, and/or sample testing. For a smooth and even dew formation, it requires the mirror to be perfectly clean. If there are any contaminants (e.g.

  • Page 40: Cleaning A Series 4Tev

    AquaLab 6. Cleaning and Maintenance sample chamber and sensors. Th e sample chamber consists of all surfaces inside the red o-ring when the lid is closed. Cleaning a Series 4TEV: If cleaning an AquaLab Series 4TEV, follow the cleaning procedures listed below being careful not to get cleaning solution or alcohol on the capacitance sensor fi lter (see illustration on previous page).
  • Page 41 AquaLab 6. Cleaning and Maintenance wipe if it becomes too dirty during this process. d. Clean lower block with a fresh Kimwipe. Be sure to clean the entire block surface. e. RINSE—Repeat steps b-d using new Kimwipes with distilled water. f.

  • Page 42: Verifi Cation Of Calibration

    AquaLab 6. Cleaning and Maintenance e. Visually inspect the thermopile and optical sensor for cleanli- ness. Re-clean if necessary. 4. Additional Drying Time a. Visually inspect the sample chamber and sensors for contami- nants, including moisture. If necessary, repeat the cleaning process using new Kimwipes.

  • Page 43: Verifi Cation And Calibration

    AquaLab 7. Verifi cation and Calibration 7. Verifi cation and Calibration It is important to verify AquaLab’s water activity calibration against known standards to guarantee optimal performance and accuracy. Decagon recommends verifi cation daily, once per shift or before each use. Water Activity Verifi cation AquaLab uses the chilled-mirror dewpoint technique to determine water activity.
  • Page 44 AquaLab 7. Verifi cation and Calibration produced under a strict quality assurance regime. Please contact Decagon Devices to order additional standards via sales@decagon. com or 1-800-755-2751. Verifi cation Standard Water Activity @ 25°C 13.41m LiCl 0.250 ±0.003 8.57m LiCl 0.500 ±0.003 6.0m NaCl...

  • Page 45: Verifi Cation Of Calibration

    AquaLab 7. Verifi cation and Calibration Verifi cation of Calibration When to Verify for Linear Off set Linear off set should be checked against two known verifi cation standards daily, either once per shift or before each use. Linear off set should never be verifi ed solely against distilled water, since it does not give an accurate representation of the linear off set.
  • Page 46 AquaLab 7. Verifi cation and Calibration 3. Carefully close the lid and move the lever to the READ position. 4. Take two readings. Th e water activity readings should be within ± 0.003 a of the given value for the verifi cation standard. See Ap- pendix B for the correct water activity value of Decagon’s standards at temperatures other than 25°C.
  • Page 47 AquaLab 7. Verifi cation and Calibration Repeat Process Measure Verification Standard Correct Clean Sample Not Correct Chamber Clean Sample Chamber Next Correct Re-Read Correct Measure 2nd Standard Standard Correct Not Correct Go to Linear Go to Sampling Offset Procedure Procedure Th is fl owchart is a graphical representation of the directions given above for checking for linear off set.
  • Page 48 AquaLab 7. Verifi cation and Calibration Adjust for Linear Off set 1. Once you are certain a linear off set has occurred, toggle to the Confi guration tab by pressing the Menu icon button. Calibration is the fi rst option highlighted in the confi guration tab. Press the Enter icon button to begin the verifi cation process.
  • Page 49 AquaLab 7. Verifi cation and Calibration 3. Empty the whole vial of solution into a sample cup. We recom- mend using the 6.0 NaCl (0.76a ). Do not adjust for the off set us- ing distilled water. Ensure the rim and outside of the cup are clean. Place the sample cup in the AquaLab’s sample chamber.
  • Page 50 AquaLab 7. Verifi cation and Calibration 7. Re-measure the verifi cation standard again in normal sampling mode. It should read the proper value (within ±0.003 a ) at a given temperature for your particular standard (see Appendix B for tem- peratures other than 25°C ).
  • Page 51 AquaLab 7. Verifi cation and Calibration 2. Scroll down to Defaults and press the Enter icon button to access the Restore Factory Defaults routine. To cancel and return to the main menu, press the Cancel icon button. After pushing the Enter icon button, the following screen will appear: NOTE: For TEV models make sure you have the correct sensor selected.

  • Page 52: Sample Preparation

    AquaLab 8. Sample Preparation 8. Sample Preparation Proper sample preparation is an important step in keeping your AquaLab clean and achieving repeatable results. Careful preparation and loading of samples will lengthen time between cleanings and help you avoid downtime. Preparing the Sample 1.

  • Page 53: Samples Needing Special Preparation

    AquaLab 8. Sample Preparation change the moisture content of the sample. Covering the bottom of the sample cup provides enough sample to get an accurate reading. 4. Make sure the rim and outside of the sample cup are clean. Wipe any excess sample material from the rim of the cup with a clean Kimwipe.

  • Page 54: Slow Water-Emitting Samples

    AquaLab 8. Sample Preparation Coated and Dried Samples Samples with high sugar or fat coatings often require multiple read- ings, because it takes longer for them to equilibrate. If this is the case for your samples, it is not a problem with your instrument; it simply means that your particular sample takes longer than most to equilibrate.

  • Page 55: Volatile Samples

    AquaLab 8. Sample Preparation For faster reading, it is important to have the water activity of the chamber at or below the water activity of these type of samples. Th is causes the sample to release water to the vapor phase and equilibrate with the chamber.

  • Page 56: Low Water Activity

    AquaLab 8. Sample Preparation Low Water Activity When a sample’s water activity value is below the cooling capacity of the Series 4, your AquaLab will display an error message indicating the lowest reading it attained on that particular sample. See Chapter 12’s troubleshooting problem #5 for possible solutions.
  • Page 57 AquaLab 8. Sample Preparation NOTE: Powdery substances can be blown by the fan so be sure not to overfi ll the sample cup and verify the cleanliness of the sample chamber before reading a new sample.

  • Page 58: Taking A Reading

    AquaLab 9. Taking a Reading 9. Taking a Reading Measurement Steps Once you have verifi ed for cleanliness, calibration and prepared your sample, you are ready to take readings. Th e process is simple: • Move the chamber lever to the Open position and lift the cham- ber lid.
  • Page 59 AquaLab 9. Taking a Reading librium and the accuracy of readings. When the instrument has fi n- ished its read cycle, the water activity is displayed, the read time is displayed, the spinning measurement icon is replaced by the Store icon and, if enabled, you will hear a series of beeps.
  • Page 60 AquaLab 9. Taking a Reading chamber if they have a high water activity. It is best to remove the sample from the instrument, place a lid on the cup and allow the sample to cool before reading. • The physical temperature of the instrument should be between 15 - 50°C.

  • Page 61: Duo Operation (Optional)

    AquaLab 10. Duo Operation (Optional) 10. Duo Operation (Optional) Previously, measuring moisture content and water activity required diff erent instruments. Now it is possible to determine both moisture content and water activity with one machine. Th e Series 4TE can be upgraded to Series 4TE DUO which can display moisture content simultaneously with water activity.

  • Page 62: Obtaining Product Isotherm Models

    AquaLab 10. Duo Operation (Optional) Obtaining Product Isotherm Models Since the isotherm relationship for each product is unique, each product’s isotherm model must be determined ex- perimentally. Th is only needs to be done once, but must be done prior to testing moisture content with the DUO. Th ere are several strategies that can be used to generate models.
  • Page 63 AquaLab 10. Duo Operation (Optional) Measuring Moisture Content With the product models loaded into the instrument, the Series 4TE DUO can generate moisture content and water activity simul- taneously. Selecting a Product for Analysis • With the Series 4TE DUO turned on, toggle to the configura- tion screen by pressing the menu button.
  • Page 64 AquaLab 10. Duo Operation (Optional) • A list of available models will be listed by name. • Select the model for the product to be analyzed. Selecting “None” will not select any model. Taking a Reading • Readings are taken with the DUO the same as outlined in Chap- ter 9.
  • Page 65 AquaLab 10. Duo Operation (Optional) the need to return to the configuration screen to change products. When the tab at the top shows “Measurement”, no model is se- lected and only water activity will be displayed on the screen. • Place a sample in the chamber and begin testing by sliding the lever left to the read position.

  • Page 66: Moisture Content Adjustment

    AquaLab 10. Duo Operation (Optional) • The test can be saved to the instrument’s memory by pressing the button under the save icon. An annotation can be added if desired. If autosave has been selected, the data will already be saved but without any annotation.
  • Page 67 AquaLab 10. Duo Operation (Optional) When to Adjust for Linear Off set Reference methods can diff er between labs, so it is a good idea to check for a linear off set upon receipt of a new isotherm model from Decagon. In addition, the linear off set should be adjusted if moisture contents being calculated by the AquaLab Duo instru- ment are consistently higher or lower for a product than your refer- ence method values over several samples.
  • Page 68 AquaLab 10. Duo Operation (Optional) tion instead of replacing the existing model. Pressing Enter opens a model screen listing all models currently loaded on the instrument. 5. Scroll down to fi nd the model for the product to be off set and press Enter.
  • Page 69 AquaLab 10. Duo Operation (Optional) 8. Once the reading is complete, a screen will display the water activity measured as well as the moisture content based on the target model. Adjust the moisture content reading using the up and down arrows until it matches the moisture content value obtained from your reference method and click Save.

  • Page 70: Restore Original Moisture Content Model Settings

    AquaLab 10. Duo Operation (Optional) Restore Original Moisture Content Model Settings To restore the original model settings, do the following: 1. Navigate to the calibration screen in the Confi guration menu of the AquaLab Duo Moisture Analyzer and select %Moisture from the list of calibration types.
  • Page 71 AquaLab 10. Duo Operation (Optional) 4. Scroll down to Defaults and press the Enter icon button to restore to defaults. To cancel and return to the main menu, press the Cancel icon button. After pushing the Enter icon button, the following screen will appear: 5.

  • Page 72: How To Delete Models

    AquaLab 10. Duo Operation (Optional) 6. To return to the main menu screen, press the Check icon button. How to Delete Models If you fi nd that a model is no longer needed, you have the option of deleting the model directly from the instrument. If the model is deleted, other users will no longer be able to use it.
  • Page 73 AquaLab 10. Duo Operation (Optional) Scroll down to Delete and press the Enter Button. 2. Select the model you would like to delete and press the Enter icon button to continue or the Cancel icon button to cancel. 3. Upon pressing Enter, the following screen should appear indi- cating the model to be deleted.

  • Page 74: Computer Interface

    If you are interested in purchasing the full version of AquaLink RG, contact Decagon or your local distributor. If you have purchased the AquaLab 4TE DUO you will automatically receive the full version of AquaLink RG with your manual.
  • Page 75 AquaLab 11. Computer Interface • At the prompt, choose a name for this program (AquaLab is a good one) and choose an arbitrary icon above to represent it. In future downloads, you will be able to click on this icon in have it already set up for you to download.

  • Page 76: Troubleshooting

    AquaLab 12. Troubleshooting 12. Troubleshooting AquaLab is a high performance, low maintenance instrument, de- signed to have few problems if used with care. Unfortunately, some- times even the best operators using the best instruments encounter technical diffi culties. Below is quick reference guide that will direct you to detailed solutions of some problems that may occur.

  • Page 77: If This Problem Occurs: Refer To

    AquaLab 12. Troubleshooting Troubleshooting Quick Guide (Continued) If this problem occurs: Refer to: Screen displays “Crystal failure”........Problem #8 Screen displays “Contaminated Mirror” ...... Problem #9 Screen displays “Firmware is corrupted” ....Problem #10 Screen displays “Readings are disabled” ..... Problem #11 How do I activate my Demo? ........

  • Page 78: Readings Are Slow Or Inconsistent

    AquaLab 12. Troubleshooting b. Locate the panel where the power cord plugs in. Th e fuse box is on the right side of that panel. Press in on the release tab and pull the fuse-holder out. Pull the broken fuse(s) out and replace with a 1.25 Amp 250V fuse.
  • Page 79 AquaLab 12. Troubleshooting be done to speed up the process. Refer to Chapter 8 for fur- ther explanation. 4) Your sample may contain volatiles. Volatiles are known to cause unstable readings, because they condense on the sur- face of the chilled mirror and alter readings. Please refer to the volatiles section in Chapter 8 for hints on reducing diffi - culties with measuring samples with propylene glycol.
  • Page 80 AquaLab 12. Troubleshooting SOLUTION: Your sample’s temperature is too high for the instrument to equili- brate with it in a reasonable amount of time. Th e instrument and sample need to be in temperature equilibrium before accurate measurements can be made. Th erefore, very cold samples will take a very long time to measure for the same reason.

  • Page 81: Dew Point Sensor Failure

    AquaLab 12. Troubleshooting SOLUTIONS: 1) Th e sample is too dry for the instrument to read accurately. If your sample has a water activity that is less than below the detection limits of the instrument, this message will come up. Essentially, it means that there is not enough sample mois- ture to condense on the mirror and provide a reading.

  • Page 82: Verifi Cation Is Not Correct

    AquaLab 12. Troubleshooting 7. PROBLEM Verifi cation is not correct. SOLUTIONS: 1) Th e sample chamber and mirror need to be cleaned. See Chapter 6 for detailed cleaning instructions. If verifi cation is still not correct, then linear off set has occurred. 2) Verify and Adjust for Linear Off set.
  • Page 83 AquaLab 12. Troubleshooting 9. PROBLEM: Message on screen displays the following: SOLUTION: Th e mirror used for dewpoint measurements requires cleaning. Fol- low the instructions outlined in Chapter 6: Cleaning and Main- tenance before trying to run your sample again. If this message continues to appear, contact Decagon for further options.
  • Page 84 AquaLab 12. Troubleshooting SOLUTION: Th e fi rmware on the instrument is corrupted and needs to be re- loaded. To download new fi rmware to the Series 4 models, the in- strument must be serviced by Decagon. 11. PROBLEM: Message on screen displays the following: SOLUTION: Th e trial period for your Demo Unit has expired.
  • Page 85 12. Troubleshooting SOLUTION: In order to begin your trial period for your AquaLab Series 4 instru- ment, you will need to contact Decagon Devices for instructions on how to activate your demo. 13. DUO PROBLEM: Test was run with wrong model.
  • Page 86 If no models appear in moisture content screen, models will need to be reloaded using AquaLink RG software. b. If moisture content is not an active selection, the DUO fea- ture may not be active. Content Decagon Devices to learn how to activate the DUO feature.
  • Page 87 AquaLab 12. Troubleshooting 16. DUO PROBLEM: Message on the screen displays the following: SOLUTION: 1) When a moisture content reading is not shown, the water ac- tivity or temperature for that reading is beyond the scope of the moisture sorption isotherm. Th is can happen under the following conditions: a.
  • Page 88 AquaLab 12. Troubleshooting Diagnostic Screen If, after cleaning your instrument and reading the other trouble- shooting hints, you have reason to believe that one of the compo- nents of your AquaLab may be causing measurement error, you may access a screen that will display values for component perfor- mance.

  • Page 89: Support And Repair

    AquaLab 13. Support and Repair 13. Support and Repair NOTE: If you purchased your AquaLab from one of our international distributors, please contact them. Th ey will be able to provide you with local support and service. When encountering problems with your AquaLab (that can’t be re- solved with the help of this manual), please contact Decagon Cus- tomer Support at support@decagon.com, 800-755-2751 (US and Canada), 509-332-2756 (International) or fax us at (509) 332-5158.

  • Page 90: Repair Costs

    6) Tape the box in both directions for added support. 7) Include the RMA number in the attention line on the ship- ping label. Ship to: Decagon Devices Inc. ATTN: RMA (insert your RMA #) 2365 NE Hopkins Court Pullman, WA 99163 Repair Costs Manufacturer’s defects and instruments within the three-year warran-...

  • Page 91: Further Reading

    AquaLab 14. Further Reading 14. Further Reading Water Activity Th eory & Measurement Bousquet-Ricard, M., G. Qualyle, T. Pharm, and J. C. Cheftel. 1980. Comparative study of three methods of determining water activity in intermediate moisture foods. Lebensm Wiss Technol 13:169-173.
  • Page 92 AquaLab 14. Further Reading abuza, T.P., and R. Contreras-Medellin. 1981. Prediction of moisture protection requirements for foods. Cereal Foods World 26:335-343. Labuza, T.P., K. Acott, S.R.Tatini, R.Y. Lee, J. Flink, and W. Mc- Call. 1976. Water activity determination: A collaborative study of diff erent methods.
  • Page 93 AquaLab 14. Further Reading Reid, D.S. 1976. Water activity concepts in intermediate moisture foods. p. 54-65. In R.Davies, G.G.Birch, and K.J.Parker (ed.) Inter- mediate Moisture Foods. Applied Science Publishers, London. Richard, J., and T.P. Labuza. 1990. Rapid determination of the wa- ter activity of some reference solutions, culture media and cheese using a dew point method.
  • Page 94 AquaLab 14. Further Reading Stoloff , L. 1978. Calibration of water activity measuring instru- ments and devices: Collaborative study. Journal of the Association of Offi cial Analytical Chemists 61:1166-1178. Troller, J.A. 1983. Methods to measure water activity. Journal of Food Protection 46:129-134. Troller, J.A., and J.H.B Christian.

  • Page 95: Food Safety And Microbiology

    AquaLab 14. Further Reading Vega-Mercado, H., B. Romanach, and G.V. Barbosa-Canovas. 1994. Prediction of water activity in food systems: A computer pro- gram for predicting water activity in multicomponent foods. Revista Espanola De Ciencia Y Tecnologia De Alimentos 34:427-440. Vos, P.T., andT.P. Labuza. 1974. Technique for measurements of wa- ter activity in the high aw range.
  • Page 96 AquaLab 14. Further Reading of foods in the microbiological growth range. Journal of Food Engi- neering 25:531-552. Chirife, J., andM.P. Buera. 1996. Water activity, water glass dynam- ics, and the control of microbiological growth in foods. Critical Rev. in Food Sci. Nutr. 36:465-513. Farberm, J.M., F.
  • Page 97 AquaLab 14. Further Reading Hocking, A.D., B.F. Miscamble, and J.I. Pitt. 1994. Water relations of Alternaria alternata, Cladosporium cladosporioides, Cladospori- um sphaerospermum, Curvulario lunata and Curvulario pallescens. Mycological Research 98:91-94. Houtsma, P.C., A. Heuvelink, J. Dufrenne, and S. Notermans. 1994. Eff ect of sodium lactate on toxin production, spore germination and heat resistance of proteolytic Clostridium botulinum strains.
  • Page 98 AquaLab 14. Further Reading M. Bekers. 1996. Infl uence of water activity and medium osmolal- ity on the growth and acid production of Lactobacillus casei var. alactosus. Proceedings of the Latvian Academy of Sciences Section B Natural Exact and Applied Sciences 50:144-146. Masana, M.O., and J.
  • Page 99 AquaLab 14. Further Reading Nakajo, M., and Y. Moriyama. 1993. Eff ect of pH and water activ- ity on heat resistance of spores of Bacillus coagulans. Journal of the Japanese Society for Food Science and Technology 40:268-271. Nelson, K.A., and T.P. Labuza. 1994. Water activity and food poly- mer science: Implications of state on arrhenius and WLF models in predicting shelf life.
  • Page 100 AquaLab 14. Further Reading Pitt, J.I., and B.F. Miscamble. 1995. Water relations of Aspergillus fl avus and closely related species. Journal of Food Protection 58:86-90. Plaza, P., J. Usall, N. Teixido, and I. Vinas. 2003 Eff ect of water activity and temperature on germination and growth of Penicillium digitatum, P.
  • Page 101 AquaLab 14. Further Reading Sautour, M., A. Rouget, P. Dantigny, C. Divies, and M. Bennsous- san. 2001. Prediction of conidial germination of Penicillium chrys- ogenum as infl uenced by temperature, water activity and pH. Lett Appl Microbiol 32:131-134. Seow, C.C., T.T. Teng, and C.H. Quah. 1988. Food preservation by moisture control.
  • Page 102 AquaLab 14. Further Reading Wijtzes, T., P.J. Mcclure, M.H. Zwietering, and T.A. Roberts. 1993. Modelling bacterial growth of Listeria monocytogenes as a function of water activity, pH and temperature. International Journal of Food Microbiology 18:139-149. Zwietering, M.H., T. Wijtzes, J.C. de Wit, and K.Van’T Riet. 1992. A decision support system for prediction of the microbial spoilage in foods.
  • Page 103 AquaLab 14. Further Reading Gómez, R., andJ. Fernandez-Salguero. 1993. Note: Water activity of Spanish intermediate moisture fi sh products. Revista Espanola De Ciencia Y Tecnologia De Alimentos 33:651-656. Hand, L. 1994. Controlling water activity and pH in snack sticks. Meat Marketing and Technology May:55-56. Lee, M.B., and S.
  • Page 104 AquaLab 14. Further Reading Sabadini, E., M.D. Hubinger, P.-J.d.Sobral, and B.C. Carvalho, Jr. 2001. Change of water activity and meat colour in the elaboration process of dehydrated salted meat. Ciencia e Tecnologia de Alimen- tos 21(1):14-19. Shimasaki, T., K. Miake, Y. Tsukamasa, M.A. Sugiyama, Y. Minegi- shi, and H.
  • Page 105 AquaLab 14. Further Reading Duff y, L.L., P.B.Vanderlinde, and F.H. Grau. 1994. Growth of Lis- teria monocytogenes on vacuum-packed cooked meats: Eff ects of pH, aw, nitrite and ascorbate. International Journal of Food Micro- biology 23:377-390. Gómez, R., and J. Fernandez-Salguero. 1993. Note: Water activity of Spanish intermediate moisture fi sh products.
  • Page 106 AquaLab 14. Further Reading Shah, N.P., and R.R. Ravula. 2000. Infl uence of water activity on fermentation, organic acids production and viability of yoghurt and probiotic bacteria. Australian Journal of Dairy Technology 55(3):127-131. Shimasaki, T., K. Miake, Y. Tsukamasa, M.A. Sugiyama, Y. Minegi- shi, and H.
  • Page 107 AquaLab 14. Further Reading 2000. Infl uence of water activity and storage conditions on survival and growth of proteolytic Clostridium botulinum in peanut spread. Food Microbiology 17(1):53-61. Fouskaki, M., K. Karametsi, and N.A. Chaniotakis. 2003. Method for the determination of water content in sultana raisins using a wa- ter activity probe.
  • Page 108 AquaLab 14. Further Reading Makower, B., and S. Myers. 1943. A new method for the determina- tion of moisture in dehydrated vegetables. Proceedings of Institute of Food Technologists, 4th Conference 156. Maltini, E., D. Torreggiani, B.R. Brovetto, and G. Bertolo. 1993. Functional properties of reduced moisture fruits as ingredients in food systems.
  • Page 109 AquaLab 14. Further Reading Zeb, A., R. Khan, A. Khan, M. Saeed, and S.A. Manan. 1994. In- fl uence of crystalline sucrose and chemical preservatives on the wa- ter activity and shelf stability of intermediate banana chips. Sarhad Journal of Agriculture 10:721-726. Zhang, X.W., X.
  • Page 110 AquaLab 14. Further Reading Gómez, R., J. Fernandez-Salguero, M.A. Carmona, and D. Sanchez. 1993. Water activity in foods with intermediate moisture levels: Bak- ery and confectionery products: Miscellany. Alimentaria 30:55-57. Guynot, M.E., A.J. Ramos, L. Seto, P. Purroy, V. Sanchis, and S. Marin.
  • Page 111 AquaLab 14. Further Reading Roessler, P.F., and M.C. Ballenger. 1996. Contamination of an un- preserved semisoft baked cookie with a Xerophilic Aspergillus spe- cies. Journal of Food Protection 59:1055-1060. Schebor, C., and J. Chirife. 2000. A survey of water activity and pH values in fresh pasta packed under modifi ed atmosphere manufactured in Argentina and Uruguay.
  • Page 112 AquaLab 14. Further Reading Cavia, M.M., M.A. Fernáandez-Muiño, J.F. Huidobro, and M.T. San- cho. 2004. Correlation between Moisture and Water Activity of Honeys Harvested in Diff erent Years. Journal of Food Science 69:C-368-370. Durrani, M.J., R. Khan, M. Saeed, and A. Khan. 1992. Develop- ment of concentrated beverages from Anna apples with or without added preservatives by controlling activity of water for shelf stability.
  • Page 113 AquaLab 14. Further Reading Perera, C.O. 2005. Selected quality attributes of dried foods. Drying Technology 23:717-730. Sa, M.M., and A.M. Sereno. 1993. Eff ect of temperature on sorp- tion isotherms and heats of sorption of quince jam. International Journal of Food Science & Technology 28:241-248. Shafi ur-Rahman, M.
  • Page 114 AquaLab 14. Further Reading ing Formulas. p. 45-73. In J.J. Kabara, and D.S. Orth (ed.) Preser- vative-Free and Self-Preserving Cosmetics and Drugs: Principles and Practice. Marcel Dekker, Hageman, M.J. 1988. Th e Role of Moisture in Protein Stability. Drug Dev. Ind. Pharm. 14:2047-2070. Heidemann, D.R., and P.J.
  • Page 115 AquaLab 14. Further Reading Bell, L.N., and T.P. Labuza. 1992. Compositional infl uence on the pH of reduced-moisture solutions. Journal of Food Science 57:732-734. Bell, L.N., and T.P. Labuza. 1994. Infl uence of the low-moisture state on pH and its implication for reaction kinetics. Journal of Food Engineering 22:291-312.
  • Page 116 AquaLab 14. Further Reading Lomauro, C.J., A.S. Bakshi, and T.P.Labuza. 1985a. Evaluation of food moisture sorption isotherm equations. Part II: Milk, coff ee, tea, nuts, oilseeds, spices and starchy foods. Lebensm Wiss Technol 18:118-124. Lomauro, C.J., A.S. Bakshi, and T.P. Labuza. 1985b. Evaluation of food moisture sorption isotherm equations.

  • Page 117: Preparing Salt Solution

    AquaLab Appendix A Appendix A Preparing Salt Solution If you choose to mix a saturated salt solution for use as a verifi cation standard, we recommend that you use the approved AOAC method. Th is method is as follows: 1. Select a reagent-grade salt and place it in a test container to a depth of about 4cm for more soluble salts (lower a ), to a depth of about 1.5 cm for less soluble salts (high a...
  • Page 118 AquaLab Appendix A Table 2: Water Activity of Selected Salt Solutions Saturated at 20° C at 25° C Solution Lithium 0.113 ± 0.003 0.113 ± 0.003 Chloride Magnesium 0.331 ± 0.002 0.328 ± 0.002 Chloride Potassium 0.432 ± 0.003 0.432 ± 0.004 Carbonate Magnesium 0.544 ±...

  • Page 119: Temperature Correction

    AquaLab Appendix B Appendix B Temperature Correction of Decagon’s Verifi cation Standards Temp. 0.5m 6.0m 8.57m 13.4m (°C) NaCl LiCl LiCl 15.0 1.000 0.984 0.761 0.492 0.238 20.0 1.000 0.984 0.760 0.496 0.245 25.0 1.000 0.984 0.760 0.500 0.250 30.0 1.000 0.984 0.760...

  • Page 120: Aqualab Verifi Cation Standards

    AquaLab Appendix C Appendix C AquaLab Verifi cation Standards Application Note Using AquaLab is easier then ever. Pre-packaged standard salt solu- tions are immediately available for performance verifi cation, saving you time and money. Validation and documentation for GMP and GLP has also become easier.
  • Page 121 AquaLab Appendix C verifi ed by an independent third party and are shelf stable for one year. Order your calibrtion salt standard of similar water activity today. Uncertainties Using Saturated Salt Solutions Th e water activity values listed in our operator’s manual for satu- rated salts were reprinted from Greenspan (1977).
  • Page 122 AquaLab Appendix C better standards than saturated salts. Robinson and Stokes (1965) give activity coeffi cient for various salt solutions. Th ese can be used to compute the water potential, or partial specifi c Gibbs free energy, of the water in the solution using; ...
  • Page 123 AquaLab Appendix C other terms have any temperature dependence. A further advantage of unsaturated salts is that there is no solid phase present to aff ect the water activity of the solution. Salt in saturated solutions can exist in diff erent states and result in uncertainty in the water activity values.
  • Page 124 AquaLab Appendix C tion in the drawer for testing. It should read the value ±0.003 listed in the table above. If the readings are within the expected values your verifi cation is complete. 2. If the fi rst solution does not read within ±0.003 of the expected value, then you need to adjust the linear off set so that the solution reads correctly (see Chapter 7).

  • Page 125: Declaration Of Conformity

    2008 Th is is to certify that the AquaLab water activity meter, manufac- tured by Decagon Devices, Inc., a corporation based in Pullman, Washington, USA meets or exceeds the standards for CE compli- ance as per the Council Directives noted above. All instruments are built at the factory at Decagon and pertinent testing documenta- tion is freely available for verifi cation.

  • Page 126: Certifi Cate Of Traceability

    AquaLab Certifi cate of Traceability Certifi cate of Traceability Decagon Devices, Inc 2365 NE Hopkins Court Pullman WA 99163 Tel: (509) 332-2756 Fax: (509) 332-5158 support@decagon.com Th is is to certify that AquaLab water Activity Meters are manufac- tured utilizing temperature standards with calibration traceable to...
  • Page 127 AquaLab Certifi cate of Traceability Index About 1, 29 Accuracy 53 Admin 26 Administrator password 25 AquaLab and water activity 4, 5 AquaLab models 4 AquaLink RG 68 Auto save 27 Barrier 48 Beeps 28 Binding 12 Calibration 20, 39 Capillaries 13 Cautions 53 Certifi...
  • Page 128 AquaLab Certifi cate of Traceability Custom mode 22 Data 18 Declaration of Conformity 119 Dehydrated 48 Delete 31 Diagnostics 28, 82 DUO 14, 55 Equilibrate 48, 50 Equilibrium 6 Error message 50 Fax 2 Fuse 71 Gibbs 12 Homogeneous 46 Hyperterminal 68 Infrared thermometer 10 Isotherm...
  • Page 129 AquaLab Certifi cate of Traceability Matrix 13 Measurement 18 Menus 18 Microbial 13 Microbial growth 14 Model 4TEV 8 Moisture content 55 measure 57 Moisture sorption isotherm 55 Multi-component 11 Notifi cation 28 Operation 16 Original calibration 44 Osmotic 12 Performance 36, 37 Perishability 9 Pharmaceuticals 9...
  • Page 130 AquaLab Certifi cate of Traceability Salt standard 38 Sample preparation 46 Saturation 10 Seller’s liability 2 Serial number 29 Sorption isotherm 14 Specifi cations 4 Spreadsheet 69 Technical diffi culties 70 Temperature 6, 20 Temperature effects 11 Temperature fl uctuations 7 Thermodynamic property 12 Time 24 Troubleshooting 18...

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