AquaLab 4 Series Operator's Manual
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AquaLab 4 Series Operator's Manual

Water activity meter
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Water Activity Meter
Operator's Manual
For Series 4, 4TE, 4TEV, DUO, and TEV DUO
Decagon Devices, Inc.
Version: August 2, 2016 — 09:05:15

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Summary of Contents for AquaLab 4 Series

  • Page 1 Water Activity Meter Operator’s Manual For Series 4, 4TE, 4TEV, DUO, and TEV DUO Decagon Devices, Inc. Version: August 2, 2016 — 09:05:15...
  • Page 2 AquaLab Decagon Devices, Inc. 2365 NE Hopkins Court Pullman WA 99163 Phone: 509-332-5601 Fax: 509-332-5158 Website: www.aqualab.com Email: support@aqualab.com or sales@aqualab.com Trademarks AquaLab is a registered trademark of Decagon Devices, Inc. c 2008-2015 Decagon Devices, Inc.

  • Page 3: Table Of Contents

    2.3 AquaLab Model and Options ....2.4 How AquaLab Works ....
  • Page 4 9.1 Measurement Steps ....54 9.2 How AquaLab Takes Readings ... . . 54 10 DUO Operation (Optional) 10.1 Obtaining Product Isotherm Models .
  • Page 5 AquaLab CONTENTS 14.1 Water Activity Theory & Measurement ..84 15 Appendix A 15.1 Preparing Salt Solutions ....106...

  • Page 6: Introduction

    AquaLab is the quickest, most accurate, and most reliable instrument available for measuring water activity. Whether you are researching or working on the production line, AquaLab suits your needs. It is easy to use and provides accurate and timely results.

  • Page 7: Warranty

    Your warranty is automatically validated upon receipt of the instrument. We contact our customers within the first 90 days of your purchase to see how the AquaLab is working for you. Seller’s Liability Seller warrants new equipment of its own manufacture against de- fective workmanship and materials for a period of one year from the date of receipt of equipment.

  • Page 8: General Safety Information

    AquaLab 1 INTRODUCTION General Safety Information Please read through this documentation carefully before putting the instrument into operation. The documentation contains information and warnings which the user must follow in order to ensure safe op- eration. This instrument may only be operated in accordance with the specifications in this documentation.

  • Page 9: About Aqualab

    2 ABOUT AQUALAB AquaLab About AquaLab AquaLab is the fastest and most accurate instrument for measuring water activity, giving readings in five minutes or less. Its readings are reliable, providing 0.003 a accuracy. The instrument is easy to clean and checking calibration is simple.

  • Page 10: Aqualab 4 Duo Specifications

    Data Communications: USB & RS 232 A serial, 9600 to 115200 baud Power: 110 to 220 VAC, 50/60 Hz Warranty: One year parts and labor AquaLab 4 DUO Specifications Moisture Content Repeatability: 0.02% Accuracy to Moisture Content Ref.: 0.1% to 0.5% AquaLab Model and Options Series 4: Uses a chilled-mirror dew point sensor, but lacks the tem- perature control features found in our premium models.

  • Page 11: How Aqualab Works

    Since AquaLab measures both dew point and sam- ple surface temperatures simultaneously, it eliminates the need for complete thermal equilibrium, thereby reducing measurement times to less than five minutes for most samples. The AquaLab 4TEV and 4TEV DUO both use a capacitance humidity sensor to measure the...

  • Page 12: Aqualab And Temperature

    AquaLab and Temperature Samples not read at room temperature during the read cycle equili- brate with the AquaLab temperature before the water activity dis- plays. Large temperature differences cause longer reading times, since the Series 4 does not make a complete and accurate reading un- til the sample and the instrument equilibrate to 4 C of each other.

  • Page 13: Chilled Mirror Dew Point Limitations

    Series 4TE models. Chilled Mirror Dew Point Limitations AquaLab limitation is its ability to accurately measure samples with high concentrations (typically > 1%) of certain volatiles such as ethanol or propylene glycol, which can condense on the surface of the chilled mirror.

  • Page 14: Water Activity Theory

    In the AquaLab, you place a sample in a sam- ple cup that seals inside the sample chamber. Inside the sample chamber is a fan, a dew point sensor, a temperature sensor, and an infrared thermometer.
  • Page 15 3 WATER ACTIVITY THEORY AquaLab Figure 1: Water Activity Diagram adapted from Labuza temperature of the air in the chamber, and the infrared thermome- ter measures the sample temperature. From these measurements, the relative humidity of the head-space is computed as the ratio of dew point temperature saturation vapor pressure to saturation vapor pressure at the sample temperature.

  • Page 16: Water Potential

    A sample at 0.75 a needs to be approximately 4 C above the chamber temperature to cause condensation. The AquaLab warns the user if a sample is more than 4 C above the chamber temperature, but for high water...
  • Page 17 3 WATER ACTIVITY THEORY AquaLab por phase and use that to determine the water potential of the liquid phase. Gradients in (µ) are driving forces for moisture movement. Thus, in an isothermal system, water tends to move from regions of high water potential (high a ) to regions of low water potential (low a ).

  • Page 18: Sorption Isotherms

    Isotherm Generator called the AquaLab Vapor Sorption An- alyzer (VSA) or you can also have Decagon run the isotherm for a fee. For example, if you were using the AquaLab to monitor the water content of dried potato flakes, you would measure the water activity and water content of potato flakes dried to varying degrees using the...
  • Page 19 3 WATER ACTIVITY THEORY AquaLab determine moisture content and water activity simultaneously. This instrument is called the Series 4TE DUO. We cannot overemphasize the importance of the concept of water activity for foods, pharmaceuticals, and cosmetics. Water activity is a measure of the energy status of the water in a system. More...

  • Page 20: Getting Started

    This location should be well away from air conditioner and heater vents, open windows, etc. Place the AquaLab in a location where cleanliness can be maintained to prevent contamination of the sample chamber.

  • Page 21: Preparing Aqualab For Operation

    Measurement screen. Warning: Only use the supplied power cord or one rated for your AquaLab 4 and certified for the country of use. The cord must be minimum of 18 AWG and have a rating for 10 Amps or greater.
  • Page 22 AquaLab 4 GETTING STARTED...

  • Page 23: Menus

    Measurement Tab The Measurement tab, as seen above, is the main screen which dis- plays each time you turn on your AquaLab. If this screen does not appear, refer to Section 12 for troubleshooting instructions. As men- tioned earlier, the water activity and sample temperature are dis- played on the screen.

  • Page 24: Configuration Tab

    AquaLab 5 MENUS Configuration Tab When at the configuration screen, pressing the up and down arrow keys moves the cursor through the various configuration options. Press the left and right arrows to page through the options. The Enter button allows you to change the highlighted setting.
  • Page 25 The AquaLab Series 4TE models may be set between 15 and 50 C by 0.1 C intervals. Using the up and down arrows, set the AquaLab to your desired temperature and press the save button. Temp Eq...
  • Page 26 All readings taken during continuous mode are saved on the instrument memory if the autosave feature is selected (see Auto Save below). If the AquaLab is connected to a computer using AquaLink 4 (see...
  • Page 27 final test. If autosave is turned on, all test readings save to the instrument memory, but only the final reading appears on the main measurement screen. If the AquaLab is connected to a computer us- ing AquaLink 4 (see Section 11), AquaLink 4 downloads all readings taken during a custom mode test.
  • Page 28 (To exit without updating, press the cancel but- ton). Date AquaLab Series 4 models now have an internal calendar and clock. The time and date are recorded with each water activity reading. Pressing Enter when the Date option is highlighted allows you to set the date in the instrument.

  • Page 29: Admin Settings

    5 MENUS AquaLab Time Pressing Enter with the Time option highlighted allows you to set the current local time. Press the up or down arrows to change any of the individual values. Press the left or right buttons to change between hour and minutes.
  • Page 30 AquaLab 5 MENUS The admin settings allow the administrator to grant or block access to some or all of the configuration 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 lock all other users out of that configuration screen.
  • Page 31 Auto Save AquaLab Series 4 models have the ability to store water activity readings within the instrument. By selecting Auto Save On, the instrument automatically stores every water activity reading in the internal memory.
  • Page 32 AquaLab 5 MENUS reading, and the reading is autosaved, it is not possible to give an annotation later. Beeps Allows you to set the reading finished notification from 4 beeps to continuous beeps. You may also turn the audible notification off.

  • Page 33: Data Tab

    5 MENUS AquaLab About This screen provides important information including the serial num- ber and code version of your instrument. Data Tab View...
  • Page 34 AquaLab 5 MENUS This selection allows you to view your stored measurements. The up/down arrows 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. See Section 11: Computer Interface for information about downloading these readings to a computer.
  • Page 35 5 MENUS AquaLab Delete Selecting this option deletes all of the information currently stored in the instrument. If you have not backed up this information with AquaLink 4, the Delete window issues a reminder. Note: You cannot recover deleted data.

  • Page 36: Cleaning And Maintenance

    AquaLab 6 CLEANING AND MAINTENANCE 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, so you must regularly clean your instrument. To clean your instrument, carefully follow these instructions and refer to the labeled diagram in Figure 2.

  • Page 37: Cleaning The Block Sensors

    Cleaning the Block Sensors Accessing the Sample Chamber Turn the power off on your AquaLab. If latched, move the lever over to the open position. Lift the chamber cover to expose the sam- ple chamber and sensors. The sample chamber consists of all surfaces...

  • Page 38: Cleaning A Series 4Tev

    6 CLEANING AND MAINTENANCE Cleaning a Series 4TEV When cleaning an AquaLab Series 4TEV, follow the cleaning proce- dures listed below being careful not to get cleaning solution on the capacitance sensor filter (see illustration on previous page). If you run out of Decagon Cleaning Solution, you can use isopropyl alcohol (IPA) instead.
  • Page 39 6 CLEANING AND MAINTENANCE AquaLab the Kimwipe 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 through d using new Kimwipes with deionized water.

  • Page 40: Verification Of Calibration

    Verification of Calibration After you have cleaned the chamber and other parts of your AquaLab, it is important to check the instrument performance in order to cor- rect for any linear offset that may have occurred during the cleaning process.

  • Page 41: Verification And Calibration

    7 VERIFICATION AND CALIBRATION AquaLab Verification and Calibration It is important to verify the AquaLab water activity calibration against known standards to guarantee optimal performance and ac- curacy. Decagon recommends verification daily, once per shift or before each use. Decagon also recommends annual factory calibra- tion to maintain optimal performance.

  • Page 42: Verification Of Calibration

    To use a verification standard, remove the twist top and pour the contents into an AquaLab sample cup. Information about the stan- dard value and molality can be found printed on the outside of the plastic vial. If for some reason you cannot obtain Decagon’s ver- ification standards and need to make a saturated salt solution for...
  • Page 43 Follow steps 1 through 8 to verify for linear offset of your AquaLab. (Refer to Figure 3: the Verification Standard Flowchart for a quick overview.)
  • Page 44 AquaLab 7 VERIFICATION AND CALIBRATION water activity you plan to test. For example, if you plan to test for water activity readings ranging between 0.713 and 0.621 you should use the 8.57 mol/kg LiCl (0.50 a ) standard for your first verification and the 6.00 mol/kg, NaCl (0.76 a ) for the...
  • Page 45 7 VERIFICATION AND CALIBRATION AquaLab Figure 3: Verification Standard Flowchart Note: The Measure Verification Standard flowchart is a graphical representation of the Verification of Calibration directions. Adjust for Linear Offset 1. Once you are certain a linear offset has occurred, toggle to the Configuration tab by pressing the Menu icon button.
  • Page 46 6.00 NaCl (0.76 a ). Do not adjust for the offset using USP Purified water. Ensure the rim and outside of the cup are clean. Place the sample cup in the AquaLab sample chamber. Note: You may use the same verification standard to verify and adjust the linear offset.
  • Page 47 Decagon by e-mail at support@aqualab.com or by phone at 509-332-5601 for further in- structions. If you purchased your Decagon instrument from one of our international distributors, please contact them for local service...

  • Page 48: Multi-Point Calibration

    (TEV Models, capacitance sensor only) 1. The capacitance sensor used for measuring the water activity of materials with volatiles (AquaLab 4TEV models only) is a sec- ondary method for measuring water activity and consequently may require a slope change to the calibration in addition to a linear offset.
  • Page 49 7. Carefully close the lid and move the lever to the Read position. Press the Check icon button to begin testing. 8. After your AquaLab has finished measuring the verification standard, a new screen appears requesting that a 0.50 a stan- dard be placed in the chamber.
  • Page 50 AquaLab 7 VERIFICATION AND CALIBRATION 10. Press the Cancel button to cancel the calibration process while selecting the Check Mark brings up the optimize prompt. You can toggle the audio icon to turn beeping on and off. 11. To make adjustments to the calibration, select the check mark.
  • Page 51 7 VERIFICATION AND CALIBRATION AquaLab 13. To save the new calibration changes, select the Save icon and the Calibration screen to verify that the AquaLab saved your new multi-point calibration. 14. To discard the calibration changes and exit without saving, press the Cancel button and the system returns a calibration canceled message.

  • Page 52: How To Restore Factory Defaults

    AquaLab 7 VERIFICATION AND CALIBRATION offset, and applying a multi-point calibration, contact Decagon by email at support@aqualab.com or by phone at 509-332-5601 for further instructions. If you purchased your Decagon instru- ment from one of our international distributors, please contact them for local service and support.
  • Page 53 7 VERIFICATION AND CALIBRATION AquaLab 3. To restore the factory calibration values, select the Check icon. To cancel and return to the main menu, choose the Cancel button. After pressing the Check icon, the Calibration screen verifies that you have restored the factory calibration.

  • Page 54: Sample Preparation

    (like deep-fried, breaded foods) can be measured, but may take longer to equilibrate. For samples like these, the AquaLab may take more than five minutes to give an accurate reading, or may require multiple readings of the same sample.

  • Page 55: Samples Needing Special Preparation

    Samples Needing Special Preparation The AquaLab reads most materials in five minutes or less. However, the nature of some samples necessitates longer reading times. These materials need additional preparation to ensure quick, accurate read- ings.

  • Page 56: Slow Water-Emitting Samples

    The most effective way to test these types of samples is to run them in the AquaLab using the continuous or custom mode and wait for the water activity read- ings to stabilize.

  • Page 57: Low Water Activity

    Low Water Activity When a sample water activity value is below the cooling capacity of the Series 4, the AquaLab displays an error message indicating the lowest reading it attained on that particular sample. See the trou- bleshooting problem number five in Section 12 for possible solutions.
  • Page 58 AquaLab 8 SAMPLE PREPARATION High-water activity samples that are warmer than the chamber tem- perature can cause condensation inside the measuring chamber, which adversely affect subsequent readings. A warning message appears (Sample too hot) if the sample temperature is more than 4 C above chamber temperature.

  • Page 59: Taking A Reading

    How AquaLab Takes Readings The AquaLab reading cycle continues until the rate of change of three consecutive readings are less than 0.0005 a of each other.
  • Page 60 9 TAKING A READING you hear a series of beeps. Cautions Never leave a sample in your AquaLab after a reading has been taken. The sample may spill and contaminate the instrument chamber if the instrument is acciden- tally moved or jolted.
  • Page 61 50 C. If a sample has a water activity lower than about 0.03, the AquaLab displays the < symbol in the Measurement window to notify you that your sample is too dry to be accurately measured by the AquaLab.

  • Page 62: Duo Operation (Optional)

    AquaLab 10 DUO OPERATION (OPTIONAL) DUO Operation (Optional) Previously, measuring moisture content and water activity required different instruments. Now it is possible to determine both moisture content and water activity with one machine. The Series 4TE and 4TEV can be upgraded to Series 4TE DUO and 4TEV to a 4TEV DUO, both of which display moisture content simultaneously with water activity.

  • Page 63: Obtaining Product Isotherm Models

    10 DUO OPERATION (OPTIONAL) AquaLab 10.1 Obtaining Product Isotherm Models Since the isotherm relationship for each product is unique, each prod- uct isotherm model must be determined experimentally. This only needs to be done once, but must be done prior to testing moisture content with the DUO.

  • Page 64: Measuring Moisture Content

    DUO can generate moisture content and water activity simultane- ously. Selecting a Product for Analysis 1. With the AquaLab turned on, use the up and down arrows in the Measurement tab to scroll through models or toggle to the configuration tab, select %Moisture, and select the model of choice.
  • Page 65 10 DUO OPERATION (OPTIONAL) AquaLab 4. Select the model for the product to be analyzed. Select None to not select any model. Taking a Reading 1. Readings are taken with the DUO the same as outlined in Sec- tion 9. First, return to the main screen.
  • Page 66 AquaLab 10 DUO OPERATION (OPTIONAL) 5. When the test is complete, the screen displays the water activ- ity and moisture content for the product selected. If you have the wrong model selected, use the up and down buttons to tog- gle to the correct model.

  • Page 67: Moisture Content Adjustment

    Therefore, if moisture contents calcu- lated with the AquaLab DUO instrument are not agreeing with your reference method, the problem can likely be addressed by adjusting a linear offset.
  • Page 68 AquaLab 10 DUO OPERATION (OPTIONAL) AquaLab DUO and select %Moisture from the list of calibra- tion types. 4. Select Edit to edit and replace an existing model. Select New if you would like to create a new offset model with this cali- bration instead of replacing the existing model.
  • Page 69 Place the third subsample from step 1 in a sample cup, then put the sample cup in the testing chamber of the AquaLab DUO instrument and close the lid. 7. Press Enter to begin a reading. 8. Once the reading is complete, a screen displays the water ac- tivity measured as well as the moisture content based on the target model.

  • Page 70: Restore Moisture Content Settings

    To restore the original model settings, do the following: 1. Navigate to the calibration screen in the Configuration tab of the AquaLab DUO and select %Moisture from the list of cali- bration types. Note: If you do not see %Moisture as an option you may not have a DUO model or you may not have any models installed.
  • Page 71 10 DUO OPERATION (OPTIONAL) AquaLab 3. Select the model that you would like to reset to its original setting and press the Enter button. 4. Scroll down to Defaults and press the Enter icon button to restore to defaults. To cancel and return to the Calibration tab, select the Cancel icon.

  • Page 72: How To Delete Models

    1. Navigate to the calibration screen in the Configuration tab of the AquaLab DUO and select %Moisture from the list of cali- bration types. Note: If you do not see %Moisture as an option you may not...
  • Page 73 10 DUO OPERATION (OPTIONAL) AquaLab 2. Scroll down to Delete and press the Enter button. 3. Select the model you would like to delete and press the Enter icon button to continue or the X button to cancel. 4. Upon pressing Enter, the following screen should appear indi- cating the model to be deleted.

  • Page 74: Computer Interface

    AquaLink 4 also has sample identification and comment fields that you can use to help annotate the data your AquaLab is gathering. Figure 5 shows a screen shot of the AquaLink 4 program.

  • Page 75: Aqualink 4 Part 11 Compatible Software

    Windows 7. To use any of these terminal programs with your AquaLab, follow the instructions for the program with the following settings. Be sure to power on the AquaLab prior to connecting the USB interface cable to your computer.
  • Page 76 No parity 1 stop bit Flow control set to none After successfully connecting the AquaLab to your computer and upon completion of a water activity reading, the data displays in the terminal program in the format as follows: measurement time (minutes), sample temperature, and water activity.

  • Page 77: Troubleshooting

    12 TROUBLESHOOTING AquaLab Troubleshooting The AquaLab is a high performance, low maintenance instrument, designed to have few problems if used with care. Unfortunately, sometimes even the best operators using the best instruments en- counter technical difficulties. Below is quick reference guide that directs you to detailed solutions of some problems that may occur.
  • Page 78 AquaLab 12 TROUBLESHOOTING SOLUTIONS: 1. Check to make sure your power cord is securely attached to the back of the instrument and it is plugged into the power outlet. 2. A power surge may have caused a fuse to blow. To change the fuses, follow instructions a through d.
  • Page 79 12 TROUBLESHOOTING AquaLab 3. Some products absorb or desorb moisture very slowly, causing measurements to take longer than usual, and nothing can be done to speed up the process. Refer to Section 8 for further explanation. 4. Your sample may contain volatiles. Volatiles are known to cause unstable readings, because they condense on the surface of the chilled mirror and alter readings.
  • Page 80 AquaLab 12 TROUBLESHOOTING SOLUTION: Your sample temperature is too high for the instrument to equili- brate with it in a reasonable amount of time. The instrument and sample need to be in temperature equilibrium before accurate mea- surements can be made. Therefore, cold samples take a long time to measure for the same reason.
  • Page 81 12 TROUBLESHOOTING AquaLab SOLUTIONS: 1. The sample is too dry for the instrument to read accurately. If your sample has a water activity that is less than the detection limits of the instrument, this message appears. Essentially, it means that there is not enough sample moisture to condense on the mirror and provide a reading.
  • Page 82 AquaLab 12 TROUBLESHOOTING SOLUTION: The crystal that runs the firmware is having trouble starting. Occa- sionally, cycling the power solves the problem. If this message con- tinues to appear, the instrument needs to be serviced by Decagon. See Section 13 for detailed instructions.
  • Page 83 12 TROUBLESHOOTING AquaLab SOLUTION: The mirror used for dew point measurements requires cleaning. Fol- low the instructions outlined in Section 6: Cleaning and Maintenance before trying to run your sample again. If this message continues to appear, contact Decagon for further options.
  • Page 84 3. If the correct model is not available, load the appropriate model using AquaLink 4 Software. The AquaLab DUO can hold a to- tal of 100 models at any one time. You may need to remove a model using the Software or use the delete option in the %Moisture Calibration menu before you can add a new one.
  • Page 85 12 TROUBLESHOOTING AquaLab Moisture content has not been activated. 1. Toggle to menu tab, select moisture content, and select the appropriate model. (a) If no models appear in moisture content screen, reload models using AquaLink 4. (b) If moisture content is not an active selection, the DUO feature may not be active.
  • Page 86 If, after cleaning your instrument and reading the other troubleshoot- ing hints, you have reason to believe that one of the components of your AquaLab may be causing measurement error, you may access a screen that displays values for component performance. Operators can access this Diagnostics screen by navigating to the Configura-...

  • Page 87: Support And Repair

    If this is not possible, use a box that has at least four inches of space between your instrument and each wall of the box. 2. Place the AquaLab in a plastic bag to avoid disfiguring marks from the packaging. 3. Do not ship the power cord or serial cable.

  • Page 88: Repair Costs

    Loaner Service Decagon has loaner instruments to keep you measuring water ac- tivity while your instrument is being serviced. If your AquaLab is still under calibration warranty or you have a service plan with your instrument, there is no charge for the loaner service.

  • Page 89: Further Reading

    14 FURTHER READING AquaLab Further Reading 14.1 Water Activity Theory & 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 90 AquaLab 14 FURTHER READING different methods. Journal of Food Science 41:910-917. Marcolli, C., and Th . Peter. 2005. Water activity in polyol/water systems: new UNIFAC parameterization. Atmospheric Chemistry and Physics 5:1545-1555. Ninni, L., M.S. Camargo, and A.J.A. Meirelles. 2000. Water ac- tivity in polyol systems.
  • Page 91 14 FURTHER READING AquaLab Wiss Technol 24:208-213. Rodel, W. 2001. Water activity and its measurement in food. P. 453-483. In E. Kress-Rogers, and C.B. Brimelow (ed.) Instrumenta- tion and sensors for the food industry. CRC Press LLC, Boca Raton, Roos, K.D. 1975. Estimation of water activity in intermediate mois- ture foods.
  • Page 92 J. Agric. Food Chem. 22:326- 327. Voysey, P. 1993. An evaluation of the AquaLab CX-2 system for measuring water activity. F. M. B. R. A. Digest No. 124 24-25. Food Safety and Microbiology Bei, Z.H., and R.-M.J.
  • Page 93 14 FURTHER READING AquaLab Cereal Foods World 26:345-349. Brandt, L. 1996. Bound for success. Controlling water activity gives technologists the edge in developing safe, shelf-stable foods. Food Formulating 2:41-48. Chirife, J., and M.P. Buera. 1994. Water activity, glass transi- tion and microbial stability in concentrated/semimoist food systems.
  • Page 94 AquaLab 14 FURTHER READING in surface agar culture. Appl Environ Microbiol 63:1048-1053. Hardman, T.M. 1988. Water and food quality. Elseiver Press, Lon- don. Hocking, A.D., and B.F. Miscamble. 1995. Water relations of some Zygomycetes isolated from food. Mycological Research 99:1113-1118.
  • Page 95 14 FURTHER READING AquaLab Marauska, M., A. Vigants, A. Klincare, D. Upite, E. Kaminska, and M. Bekers. 1996. Influence of water activity and medium osmolality on the growth and acid production of Lactobacillus casei var. alac- tosus. Proceedings of the Latvian Academy of Sciences Section B Natural Exact and Applied Sciences 50:144-146.
  • Page 96 AquaLab 14 FURTHER READING 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. Journal of Food Engineering 22:271-289. Nesci, A., M. Rodrigues, and M. Etcheverry. 2003. Control of Aspergillus growth and aflatoxin production using antioxidants at...
  • Page 97 14 FURTHER READING AquaLab activity and pH on the growth of Bacillus cells and spore: A response surface methodology study. International Journal of Food Microbi- ology 19:207-216. Rockland, L.B., and G.F. Stewart. 1981. Water activity: Influ- ences on food quality. Academic Press, New York.
  • Page 98 AquaLab 14 FURTHER READING Tapia de Daza, M.S., Y. Villegas, and A. Martinez. 1991. Mini- mal water activity for growth of Listeria monocytogenes as affected by solute and temperature. International Journal of Food Microbi- ology 14:333-337. Tokuoka, K., and T. Ishitani. 1991. Minimum water activities for the growth of yeasts isolated from high-sugar foods.
  • Page 99 14 FURTHER READING AquaLab coli O157:H7 in broth and processed salami as influenced by pH, wa- ter activity, and temperature and suitability of media for its recovery. Appl Environ Microbiol 62:2735-2740. Duffy, L.L., P.B. Vanderlinde, and F.H. Grau. 1994. Growth of Listeria monocytogenes on vacuum-packed cooked meats: Effects of...
  • Page 100 AquaLab 14 FURTHER READING determing water activity. Ciencia y Tecnologia Alimentaria 3(4):229- 235. Rocha-Garza, A.E., and J.F. Zayas. 1996. Quality of broiled beef patties supplemented with wheat germ protein flour. Journal of Food Science 61:418-421 Sabadini, E., M.D. Hubinger, P.-J.d.Sobral, and B.C. Carvalho, Jr.
  • Page 101 14 FURTHER READING AquaLab Duffy, L.L., P.B.Vanderlinde, and F.H. Grau. 1994. Growth of Lis- teria monocytogenes on vacuum-packed cooked meats: Effects of pH, a , nitrite and ascorbate. International Journal of Food Microbiol- ogy 23:377-390. Gmez, R., and J. Fernandez-Salguero. 1993. Note: Water activity of Spanish intermediate moisture fish products.
  • Page 102 AquaLab 14 FURTHER READING probiotic bacteria. Australian Journal of Dairy Technology 55(3):127- 131. Shimasaki, T., K. Miake, Y. Tsukamasa, M.A. Sugiyama, Y. Minegishi, and H. Shinano. 1994. Effect of water activity and storage tempera- ture on the quality and microflora of smoked salmon. Nippon Suisan Gakkaishi 60:569-576.
  • Page 103 14 FURTHER READING AquaLab Gogus, F., C. Cuzdemir, and S. Eren. 2000. Effects of some hydro- colloids and water activity on nonenzymic browning of concentrated orange juice. Nahrung 44(6):438-442. Hubinger, M., F.C. Menegalli, R.J. Aguerre, and C. Suarez. 1992. Water vapor adsorption isotherms of guava, mango and pineapple.
  • Page 104 AquaLab 14 FURTHER READING Marin, S., V. Sanchis, I. Vinas, R. Canela, and N. Magan. 1995. Effect of water activity and temperature on growth and fumonisin B-1 and B-2 production by Fusarium proliferatum and F. monili- forme on maize grain. Lett Appl Microbiol 21:298-301.
  • Page 105 14 FURTHER READING AquaLab quick breads. Journal of Food Protection 57:882-886. Cahagnier, B., L. Lesage, and D. Richard-Molard. 1993. Mould growth and conidiation in cereal grains as affected by water activity and temperature. Lett Appl Microbiol 17:7-13. Clawson, A.R., and A.J.Taylor. 1993. Chemical changes during cooking of wheat.
  • Page 106 AquaLab 14 FURTHER READING canos de Mutricion. 50(2):183-186. Phoungchandang, S., and J.L. Woods. 2000. Moisture diffusion and desorption isotherms for banana. Journal of Food Science 65:651-657. Ramanathan, S., and S. Cenkowski. 1995. Sorption isotherms of flour and flow behaviour of dough as influenced by flour compaction.
  • Page 107 14 FURTHER READING AquaLab Analysis to the determination of shelf life of roasted and ground cof- fee. Lebensm Wiss Technol 34:273-278. Carson, K.J., J.L. Collins, and M.P. Penfield. 1994. Unrefined, dried apple pomace as a potential food ingredient. Journal of Food Science 59:1213-1215.
  • Page 108 AquaLab 14 FURTHER READING dition of sodium citrate on the pasteurizing conditions in “Tuyu,” Japanese noodle soup. Journal of the Japanese Society for Food Sci- ence and Technology 43:740-747. Perera, C.O. 2005. Selected quality attributes of dried foods. Drying Technology 23:717-730.
  • Page 109 14 FURTHER READING AquaLab tice. Marcel Dekker. Hageman, M.J. 1988. The Role of Moisture in Protein Stability. Drug Dev. Ind. Pharm. 14:2047-2070. Heidemann, D.R., and P.J. Jarosz. 1991. Preformulation Studies Involving Moisture Uptake in Solid Dosage Forms. Pharmaceutical Research 8:292-297.
  • Page 110 AquaLab 14 FURTHER READING Bhandari, B., and I. Bareyre, 2003. Estimarion of crystalline phase present in glucose crystal-solution mixture by water activity mea- surement. Lebensm Wiss Technol 36:729-733(5). Brake, N.C., and O.R. Fennema. 1993. Edible coatings to inhibit lipid migration in a confectionery product. Journal of Food Science 58:1422-1425.
  • Page 111 Greenspan’s standard error for each salt solution, not the AquaLab accuracy in measuring the salt. The AquaLab measures all samples with an accuracy of 0.003 a using the dew point sensor and 0.015 a using the capacitance sensor.
  • Page 112 AquaLab 15 APPENDIX A Table 4: Water Activity of Selected Salt Solutions Saturated Solution a at 20 C a at 25 C Lithium Chloride 0.113 0.003 0.113 0.003 Magnesium Chloride 0.331 0.002 0.328 0.002 Potassium Carbonate 0.432 0.003 0.432 0.004 Magnesium Nitrate 0.544...

  • Page 113: Appendix B

    0.984 0.920 0.760 0.508 0.261 40.0 1.000 0.984 0.921 0.760 0.512 0.266 50.0 1.000 0.984 0.894 0.740 0.517 0.275 Note: The AquaLab measures these verification standards to 0.003 with the dew point sensor and 0.015 a with the capacitance sensor.

  • Page 114: Appendix C

    Avoid solution handling and mixing errors. Save technician time. The AquaLab should be verified against a known salt standard daily. For high use or batch processing, the instrument should be checked regularly against a known salt standard of similar water activity.
  • Page 115 Practices (GLP), a saturated salt solution must read within reasonable analytical error of the accepted published value for a given temperature. Why AquaLab Verification Standards are Superior Our research indicates that unsaturated salt solutions make much better standards than saturated salts. Robinson and Stokes (1965) give activity coefficient for various salt solutions.
  • Page 116 Instructions for Using Decagon’s Verification Standards Simply empty one vial of standard solution into a sample dish and place the dish immediately into the AquaLab for measurement. Each vial should fill a sample dish to just less than half full. Table 6 shows the expected values.
  • Page 117 0.003 0.250 0.015 Verify the AquaLab is functioning properly with any two of these solutions. We recommended that you choose a standard from the range in which you are measuring and steam distilled water (or an- other solution from the table).
  • Page 118 AquaLab 17 APPENDIX C Chem. 81A:89-96. Lang, A.R.G. 1967. Osmotic coefficients and water potentials of sodium chloride solutions from 0 to 40 C. Aust. J. Chem. 20:2017- 2023. Robinson, R.A. and R.H. Stokes. 1965. Electrolyte Solutions. But- terworths, London.

  • Page 119: Declaration Of Conformity

    EN 50581:2012 Manufacturer’s Name: Decagon Devices, Inc 2365 NE Hopkins Ct. Pullman, WA 99163 Type of Equipment: AquaLab Water Activity Meter. Model Number: Series 4, Series 4TE, Series 4TEV, Series 4TE DUO, and Se- ries 4TEV DUO Year of First Manufacture: 2008 The undersigned hereby declares on behalf of Decagon Devices, Inc.

  • Page 120: Certificate Of Traceability

    19 CERTIFICATE OF TRACEABILITY Certificate of Traceability Decagon Devices, Inc. 2365 NE Hopkins Court Pullman WA 99163 USA Tel: 509-332-5601 Fax: 509-332-5158 support@Aqualab.com Decagon Devices Inc. manufactures all AquaLab water activity me- ters according to accepted international temperature standards with traceable calibration.
  • Page 121 Administrator Password, 25 Email, 1, 42, 47, 65, 82, 115 Annual Calibration Service, 32, Equilibrate, 50, 52 35, 36, 82 Equilibrium, 6, 10 AquaLab and Water Activity, 5 Error Message, 52 AquaLab Models, 5 Auto Save, 26 Fuse, 73 Barrier, 50...
  • Page 122 AquaLab INDEX Osmotic, 12 Verification, 35 Verification Standards, 35, 36 Part 11 Compliance, 70 View, 28 Performance, 36 Volatile Samples, 51 Perishability, 9 Voltage, 27 Pharmaceuticals, 9, 14 Phone, 36, 42 Warranty, 2, 83 Photo Detector, 6 Water Activity, 5, 9...

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