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METER AquaLab TDL Operator's Manual

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Operator's Manual
METER Group, Inc.
Version: July 18, 2017 — 14:18:47

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  • Page 1 Operator’s Manual METER Group, Inc. Version: July 18, 2017 — 14:18:47...
  • Page 2 AquaLab TDL METER Group, Inc. 2365 NE Hopkins Court Pullman WA 99163 Phone: 509-332-5601 Fax: 509-332-5158 Website: www.metergroup.com Email: support.food@metergroup.com or sales.food@metergroup.com Trademarks AquaLab is a registered trademark of METER Group, Inc. c 2017 METER Group, Inc.

  • Page 3: Table Of Contents

    6.1 Cleaning the Block Sensors ....30 6.2 Cleaning an AquaLab TDL ....31 6.3 Cleaning Procedure: .
  • Page 4 CONTENTS AquaLab TDL 7.2 Verification of Calibration ....35 8 Sample Preparation 8.1 Preparing the Sample ....47 8.2 Samples Needing Special Preparation .

  • Page 5: Introduction

    Customer Support If you ever need assistance with your AquaLab, have any questions or feedback, there are several ways to contact us. METER has Cus- tomer Service Representatives available to speak with you Monday through Friday, between 7 am and 5 pm Pacific time.

  • Page 6: Warranty

    1 INTRODUCTION AquaLab TDL before operating AquaLab to ensure that the instrument performs to its full potential. Warranty AquaLab has a 30-day satisfaction guarantee and a one year warranty on parts and labor. Your warranty is automatically validated upon receipt of the instrument. We contact you within the first 90 days of your purchase to see how the TDL is working for you.

  • Page 7: General Safety Information

    1. Only personnel qualified by METER are authorized to carry out service work on the electrical components. When work is required a Certificate of Calibration will be issued upon com- pletion of the work.

  • Page 8: About Aqualab

    The instrument is easy to clean and checking calibration is simple. Note: UL has listed this product to applicable UL Standards and Requirements. AquaLab TDL Instrument Specifications Sensor Type: Tunable Diode Laser and Infrared Temperature ◦ Water Activity Accuracy: ±0.005 @ 25 Water Activity Resolution: 0.0001 a...

  • Page 9: Aqualab And Water Activity

    AquaLab TDL 2 ABOUT AQUALAB Data Communications: USB Power: 110 to 220 VAC, 50/60 Hz Warranty: One year parts and labor AquaLab and Water Activity Water activity (a ) is a measurement of the energy status of the water in a system. The value indicates how tightly water is bound, structurally or chemically, within a substance.

  • Page 10: Aqualab And Temperature

    ±4 C. There are several advantages in having a temperature-controlled water activity meter. A few major reasons are: 1. Research purposes. Researchers can use temperature con- trol to study the effects of temperature on the water activity of a sample, make a comparison of the water activity of different...

  • Page 11: Water Activity Theory

    AquaLab TDL 3 WATER ACTIVITY THEORY Water Activity Theory Water is a major component of foods, pharmaceuticals, and cosmet- ics. Water influences the texture, appearance, taste and spoilage of these products. There are two basic types of water analysis: moisture content and water activity.
  • Page 12 3 WATER ACTIVITY THEORY AquaLab TDL Figure 1: Water Activity Diagram adapted from Labuza measures the sample temperature. From these measurements, the relative humidity of the head-space is computed as the ratio of the partial pressure measured by TDL to saturation vapor pressure at the sample temperature.

  • Page 13: Water Potential

    AquaLab TDL 3 WATER ACTIVITY THEORY Temperature Effects Temperature plays a critical role in water activity determination. The AquaLab infrared thermometer measures the difference in tem- perature between the sample and the block. It is carefully calibrated to minimize temperature errors, but when temperature differences are large water activity can change during testing.
  • Page 14 3 WATER ACTIVITY THEORY AquaLab TDL...
  • Page 15 AquaLab TDL 3 WATER ACTIVITY THEORY Factors In Determining Water Activity The water activity of the water in a system is influenced by factors that effect the binding of water. They include osmotic, matric, and pressure effects. Typically water activity is measured at atmospheric pressure, so only the osmotic and matric effects are important.

  • Page 16: Sorption Isotherms

    METER sells an Isotherm Generator called the AquaLab Vapor Sorption Ana- lyzer (VSA) or you can also have METER 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...

  • Page 17: Getting Started

    AquaLab TDL 4 GETTING STARTED Getting Started Components of your AquaLab Your AquaLab should have been shipped with the following items: • AquaLab water activity meter • Calibration certificate • Power cord • USB interface cable • 50 disposable sample cups •...

  • Page 18: Preparing Aqualab For Operation

    4 GETTING STARTED AquaLab TDL Preparing AquaLab for Operation After finding a good location for your AquaLab, plug the power cord into the back of the unit. The ON/OFF switch is located on the lower left corner of the AquaLab back panel. When the AquaLab is turned on, you should see a model name/number screen and then the main Measurement screen.
  • Page 19 AquaLab TDL 4 GETTING STARTED...

  • Page 20: Menus

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

  • Page 21: Configuration Tab

    AquaLab TDL 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 22 5 MENUS AquaLab TDL Temperature ◦ The default temperature is 25 C. Press the Enter button to change the temperature setting. The AquaLab may be set between 15 and ◦ ◦ C by 1.0 C intervals. Using the up and down arrows, set the AquaLab to your desired temperature and press the save button.
  • Page 23 AquaLab TDL 5 MENUS Mode Users may choose between single, continuous, custom, or low emit- ting mode by pushing the save button. Single Mode: Single mode reads the sample once, after which the instrument notifies you that it is finished and the water activity and temperature display on the screen.
  • Page 24 5 MENUS AquaLab TDL If you turn auto save on, all test readings save to the instruments memory, but only the final reading appears on the main Measure- ment screen. If you keep the TDL connected to a computer using AquaLink 4 (See Section 11: Computer Interface), all readings taken during a custom mode test download to the AquaLink 4 software.
  • Page 25 Date AquaLab TDL models have an internal calendar and clock. The time and date are recorded with each water activity reading. Press- ing Enter when the Date option is highlighted allows you to set the...
  • Page 26 The hour setting automatically changes between AM and PM. Regional Formatting Allows you to configure how AquaLab TDL displays information. You may choose the temperature scale (Celsius vs Fahrenheit), the date display (mm/dd/yy vs. dd/mm/yy), the hour format (12 vs 24...

  • Page 27: Admin Settings

    The Admin settings allow the administrator to grant or block ac- cess to some or all of the configuration options for all AquaLab TDL models. For example: If the administrator wanted to make sure that ◦...
  • Page 28 21 CFR Part 11 or who want to maintain the settings they have selected. Auto Save AquaLab TDL models have the ability to store water activity read- ings within the instrument. By selecting Auto Save “On,” the instru-...
  • Page 29 5 MENUS ment automatically stores every water activity reading in the inter- nal memory. AquaLab TDL can store up to 8,000 records before the memory is full. If you turn Auto Save “off” then the instrument does not store data automatically, although you may store any individual reading manually right after completing the test and before starting the next test.
  • Page 30 5 MENUS AquaLab TDL About This screen provides important information including the serial num- ber and code version of your instrument.

  • Page 31: Data Tab

    AquaLab TDL 5 MENUS Data Tab View 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.
  • Page 32 5 MENUS AquaLab TDL The 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 time the reading was taken, and the sequence num- ber of the stored reading.

  • Page 33: Cleaning And Maintenance

    To clean your instrument, carefully follow these instructions and refer to the labeled diagram in Figure 2. METER also recommends you send your TDL in for annual factory calibration. Figure 2: AquaLab Instrument Diagram...

  • Page 34: Cleaning The Block Sensors

    6 CLEANING AND MAINTENANCE AquaLab TDL Purpose The purpose for the cleaning procedure is to remove grease, dirt and other soluble substances which can absorb or release water dur- ing verification, calibration, and/or sample testing. For the TDL and the IR sensor to perform well, they must be clean and free from contaminants (e.g.

  • Page 35: Cleaning An Aqualab Tdl

    The sample chamber consists of all surfaces inside the orange o-ring when the lid is closed. Cleaning an AquaLab TDL Follow the cleaning procedures listed below. If you run out of solu- tion, you can use isopropyl alcohol (IPA) instead.
  • Page 36 6 CLEANING AND MAINTENANCE AquaLab TDL 2. Clean the TDL (a) Wrap a NEW Kimwipe around the end of the spatula and moisten it with cleaning solution. (b) WASH — Swipe the moistened Kimwipe across the TDL emitter and detector lense once. (A single swipe is usually sufficient to remove contaminants.)

  • Page 37: Verification Of Calibration

    AquaLab TDL 6 CLEANING AND MAINTENANCE 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 38: Verification And Calibration

    It is important to verify AquaLab water activity calibration against known standards to guarantee optimal performance and accuracy. METER recommends verification daily, once per shift or before each use. METER also recommends annual factory calibration to main- tain optimal performance.

  • Page 39: Verification Of Calibration

    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 METER’s ver- ification standards and need to make a saturated salt solution for verification, refer to Appendix A.
  • Page 40 See Appendix B for the correct water activity value of ◦ METER’s standards at temperatures other than 25 5. If your AquaLab is reading within ±0.005 a of the verification standard, choose a second verification standard that would bor- der the range of water activity you plan to test.
  • Page 41 AquaLab TDL 7 VERIFICATION AND CALIBRATION instructions, see Section 6. After cleaning, repeat verification from step two. 8. If you are consistently getting readings outside the water ac- tivity of your first verification standard by more than ±0.005 , a linear offset has probably occurred. In this case, adjust the reading to match the correct verification standard value as...
  • Page 42 7 VERIFICATION AND CALIBRATION AquaLab TDL ibration is the first option highlighted in the Configuration tab. Press the Enter icon button to begin the verification process. The on screen commands guide you through the linear offset routine. The Calibration screen prompts you to start.
  • Page 43 If you still have incorrect verification standard readings after cleaning the chamber and adjusting for linear offset, contact METER by email at support.food@metergroup.com or by phone at 509-332-5601 for further instructions. If you purchased your METER...
  • Page 44 Multi-Point Calibration for New Temperatures 1. The AquaLab TDL is optimized for performance at specific temperatures. If testing is to be conducted at new tempera- tures, an updated calibration will be needed. If a temperature...
  • Page 45 AquaLab TDL 7 VERIFICATION AND CALIBRATION calibration. 4. To perform a multi-point calibration, select Calibration from the Configuration tab. The Calibration screen will prompt you with options. 5. Highlight Type and select Enter to toggle to multi-point. You will be guided through the multi-point calibration routine through on screen commands.
  • Page 46 7 VERIFICATION AND CALIBRATION AquaLab TDL 9. After your AquaLab has finished measuring the verification standard, a new screen will appear requesting that a 0.50 a standard be placed in the chamber. Repeat steps 6 through 7 for 0.50, 0.76, and 1.00 a standards.
  • Page 47 AquaLab TDL 7 VERIFICATION AND CALIBRATION 12. To make adjustments to the calibration, select the check mark or select the X button to cancel without adjusting the calibra- tion. 13. After optimizing the new calibration, the Calibration Complete screen will appear.
  • Page 48 METER email support.food@metergroup.com or by phone at 509-332-5601 for further instructions. If you purchased your METER instru- ment from one of our international distributors, please contact them for local service and support. How to Restore Factory Defaults To restore original calibration settings, do the following: 1.
  • Page 49 AquaLab TDL 7 VERIFICATION 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 Default screen prompts you to reset defaults.
  • Page 50 7 VERIFICATION AND CALIBRATION AquaLab TDL 4. To return to the Main menu screen, select the Check icon.

  • Page 51: Sample Preparation

    AquaLab TDL 8 SAMPLE PREPARATION Sample Preparation Proper sample preparation is an important step in keeping your AquaLab clean and achieving repeatable results. Careful prepara- tion and loading of samples lengthens time between cleanings and helps you avoid downtime. Preparing the Sample 1.

  • Page 52: Samples Needing Special Preparation

    8 SAMPLE PREPARATION AquaLab TDL 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. Material left on the rim or the outside of the cup can contaminate the sensor chamber and be transferred to subsequent samples.

  • Page 53: Slow Water-Emitting Samples

    AquaLab TDL 8 SAMPLE PREPARATION This increases the surface area of the sample, thus decreasing read- ing times. However, keep in mind that modifying some samples may alter their water activity readings. For example, a candy may have a soft chocolate center and a hard outer coating.
  • Page 54 8 SAMPLE PREPARATION AquaLab TDL to rise or fall until the temperature stabilizes. When the tempera- ture stabilizes within an optimal one or two degrees of the chamber temperature, you can proceed with normal measurements. High-water activity samples that are warmer than the chamber tem- perature can cause condensation inside the measuring chamber, which adversely affect subsequent readings.

  • Page 55: Taking A Reading

    AquaLab TDL 9 TAKING A READING Taking a Reading Measurement Steps Once you have verified for cleanliness, calibration, and prepared your sample, you are ready to take readings. Follow steps 1 through 4. 1. Move the chamber lever to the Open position and lift the cham- ber lid.
  • Page 56 9 TAKING A READING AquaLab TDL and, if enabled, 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 57 50 C. The TDL can measure samples between these ambient temperatures quickly and accurately. The AquaLab TDL has tem- perature control capabilities that enable it to read samples at tem- peratures different from ambient temperature, but no higher than...

  • Page 58: Moisture Content Measurement

    10 MOISTURE CONTENT MEASUREMENT AquaLab TDL Moisture Content Measurement 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. To calculate moisture content using water activity requires an un- derstanding of the relationship between the two parameters.

  • Page 59: Computer Interface

    AquaLab TDL 11 COMPUTER INTERFACE Computer Interface Your AquaLab may connect to your computer using USB or RS232. Your AquaLab was shipped to you with a standard USB cable. Using this cable, you can send water activity data to a computer for further analysis and storage.

  • Page 60: Aqualink 4 Part 11 Compatible Software

    Part 11 compliance system. 11.3 Using a Communication Program There are several terminal program options. METER has its own terminal program (DecaTerm) which can be downloaded from http://software.metergroup.com/DecaTerm.zip. Two other options are TeraTerm, which is a free program that can be found on the In- ternet and Hyperterminal which came standard with Microsoft Win- dows prior to Windows 7.
  • Page 61 AquaLab TDL 11 COMPUTER INTERFACE • Choose correct Com port • Set/Verify Com Properties Bits per second 9600 8 Databits 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 62: Troubleshooting

    Below is quick reference guide that directs you to detailed solutions of some problems that may occur. If these reme- dies still do not resolve your problem, then please contact METER for help (see Customer Support in Section 1). Here is a list of some problems that may occur.
  • Page 63 (d) Connect the power cord and turn your instrument on. If the fuse blows again, a failed component may be causing the problem. Contact METER to make arrangements for repairs. (See Section 13) 2. PROBLEM: Readings are slow or inconsistent.
  • Page 64 12 TROUBLESHOOTING AquaLab TDL explanation. 3. PROBLEM: Water activity readings on verification standards are too high/low and a linear offset adjustment cannot be made any higher/lower. SOLUTIONS: 1. The IR Sensor in your chamber, which measures sample tem- perature, may have become contaminated. Refer to Section 6 for directions on cleaning.
  • Page 65 SOLUTION: The crystal that runs the firmware is having trouble starting. Oc- casionally, cycling the power solves the problem. If this message continues to appear, METER needs to service the instrument. See Section 13 for detailed instructions. 7. PROBLEM: Message on screen displays the following:...
  • Page 66 Message on screen displays the error “Firmware is corrupted.” SOLUTION: The firmware on the instrument is corrupted and needs to be reloaded. To download new firmware to the AquaLab TDL, the instrument must be serviced by METER. 11. PROBLEM: Ran test with wrong model.
  • Page 67 3. If the correct model is not available, load the appropriate model using AquaLink 4 Software. The AquaLab TDL can hold a total of 100 models at any one time. You may need to re- move a model using the Software or use the delete option in the %Moisture Calibration menu before you can add a new one.
  • Page 68 (a) If no models appear in moisture content screen, reload them using AquaLink 4 software. (b) If moisture content is not an active selection, the model feature may not be active. Content METER to learn how to activate the model feature. 14. PROBLEM: Message on the screen displays no moisture content reading.
  • Page 69 AquaLab TDL 12 TROUBLESHOOTING are within the scope of the selected moisture sorption isotherm model. Diagnostic Screen 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.

  • Page 70: Support And Repair

    When encountering problems with your AquaLab (that you unable to resolve with the help of this manual), please contact METER Customer Support at support.food@metergroup.com, 509-332-5601 or fax us at 509-332-5158. Please have the serial number and model of the instrument ready.

  • Page 71: Repair Costs

    METER repairs manufacturer defects and instruments within the one year warranty at no charge. We bill non-warranty repair charges for parts, labor and shipping to you and may charge an extra fee for rush work. METER can provide an estimated repair cost, if requested. 13.2...

  • Page 72: Further Reading

    14 FURTHER READING AquaLab TDL 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 73 Richard, J., and T.P. Labuza. 1990. Rapid determination of the water activity of some reference solutions, culture media and cheese using a dew point method. Sci. des Aliments 10:57-64. Roa,V., and M.S.Tapia de Daza. 1991. Evaluation of water activity measurements with a dew point electronic humidity meter. Lebensm...
  • Page 74 14 FURTHER READING AquaLab TDL 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.
  • Page 75 AquaLab TDL 14 FURTHER READING Van den Berg, C. 1986. Water activity. p. 11-36. In D. MacCarthy (ed.) Concentration and drying of foods. Elsevier Applied Science Publishers, London. Van den Berg, C. 1991. Food-water relations: Progress and inte- gration, comments and thoughts. In H. Levine, and L. Slade (ed.) Water Relationships in Foods.
  • Page 76 14 FURTHER READING AquaLab TDL 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 77 AquaLab TDL 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 78 14 FURTHER READING AquaLab TDL 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 79 AquaLab TDL 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 80 14 FURTHER READING AquaLab TDL 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 81 AquaLab TDL 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 82 14 FURTHER READING AquaLab TDL 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 83 AquaLab TDL 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 84 14 FURTHER READING AquaLab TDL Duffy, L.L., P.B.Vanderlinde, and F.H. Grau. 1994. Growth of Lis- teria monocytogenes on vacuum-packed cooked meats: Effects of pH, , 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 85 AquaLab TDL 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 86 14 FURTHER READING AquaLab TDL 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.
  • Page 87 AquaLab TDL 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 88 14 FURTHER READING AquaLab TDL 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 89 AquaLab TDL 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 90 14 FURTHER READING AquaLab TDL 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 91 AquaLab TDL 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 92 14 FURTHER READING AquaLab TDL 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 93 AquaLab TDL 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 94: Preparing Salt Solution

    15 APPENDIX A AquaLab TDL Appendix A 15.1 Preparing Salt Solution If you choose to mix a saturated salt solution for use as a verification standard, we recommend that you use the approved AOAC method. Steps 1 through 4 detail the AOAC method.
  • Page 95 AquaLab TDL 15 APPENDIX A Table 4: Water Activity of Selected Salt Solutions ◦ ◦ Saturated Solution at 20 at 25 0.113 ±0.003 0.113 ±0.003 Lithium Chloride 0.331 ±0.002 0.328 ±0.002 Magnesium Chloride 0.432 ±0.003 0.432 ±0.004 Potassium Carbonate 0.544 ±0.002 0.529 ±0.002...
  • Page 96 1.000 0.984 0.920 0.760 0.504 0.255 0.155 35.0 1.000 0.984 0.920 0.760 0.508 0.261 0.160 40.0 1.000 0.984 0.921 0.760 0.512 0.266 0.165 50.0 1.000 0.984 0.894 0.740 0.517 0.275 0.172 Note: AquaLab TDL measures these verification standards to ±0.005...
  • Page 97 AquaLab TDL 17 APPENDIX C Appendix C AquaLab Verification Standards Application Note Using AquaLab is easier then ever. Pre-packaged standard salt solu- tions are immediately available for performance verification, saving you time and money. Validation and documentation for GMP and GLP has also become easier.
  • Page 98 17 APPENDIX C AquaLab TDL his own. The uncertainty he published is due to variation among the results from the different methods. There are, therefore, limitations to the accuracy of these values. The instrumentation available for making water activity measurements is much better now than it was in 1977, so improved standards are needed.
  • Page 99 Instructions for Using METER’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 fills a sample dish to just less than half full.
  • Page 100 17 APPENDIX C AquaLab TDL Table 6: Verification Standard Expected Values Verification Standard Distilled H 1.000 ±0.005 Water Activity 0.984 ±0.005 0.50 mol/kg KCl 0.920 ±0.005 2.33 mol/kg NaCl 0.760 ±0.005 6 mol/kg NaCl 0.500 ±0.005 8.5 mol/kg LiCl 0.250 ±0.005 13.4 mol/kg LiCl...
  • Page 101 AquaLab TDL 17 APPENDIX C ous solutions. J. Res. National Bureau of Stds. A. Physics and 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.
  • Page 102 (e.g. telescope or microscope).) The undersigned hereby declares on behalf of METER Group, Inc. that the above referenced products, to which this declaration relates, fully conform to the provisions of the Council Directives and stan- dards referenced above.
  • Page 103 19 CERTIFICATE OF TRACEABILITY Certificate of Traceability METER Group, Inc. 2365 NE Hopkins Court Pullman WA 99163 USA Tel: 509-332-5601 Fax: 509-332-5158 support.food@metergroup.com METER Group, Inc. manufactures all AquaLab water activity me- ters according to accepted international temperature standards with traceable calibration.
  • Page 104 Index Accuracy, 52 Equilibrate, 48, 49 Activated Charcoal Pellets, 33 Equilibrium, 8 Admin Settings, 23 Fuse, 59 Administrator Password, 23 Annual Calibration Service, 30, Gibbs Free Energy, 9, 94 33, 34, 66 Auto Save, 24 Homogeneous, 9, 47 Barrier, 48 Infrared Thermometer, 8 Beeps, 23, 25, 52 Isotherm Model, 54...
  • Page 105 AquaLab TDL INDEX Physical Temperature, 52 Pressure Effects, 11 Quantitative Analysis, 7 Regulations, 6, 7 Research, 94 Research Purposes, 6 RS232, 55 Salt Standard, 35 Sample Preparation, 47 Saturation, 8 Seller’s Liability, 2 Single Mode, 19 Sorption Isotherm, 12 Specifications, 4 Technical Difficulties, 58...

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