Frequently Asked Questions about Water Activity
Information on Bound Water or Hurdle Technology.
1) Why measure water activity?
Water activity is a critical factor in determining product safety and quality. It affects the microbial
action, shelf life, safety, texture, flavor, and smell of foods and other products. When you know the water
activity of your product, you can maximize safety, quality, and profit.
Water activity is part of the FDA Definition of Potentially Hazardous Food, the USDA FSIS safety regulation,
and a Critical Control Point for HACCP programs. Many food product manufacturers require water activity data
from their ingredient suppliers.
2) What's the difference between water activity and water content?
Water content is only a measure of how much water is in a product. Water activity measures what the water
will do: susceptibility to microbial growth, clumping, texture issues, moisture migration, and more.
3) Why should I buy an AquaLab?
AquaLab is the industry standard in water activity measurement for several reasons:
- Unparalleled speed & accuracy. If our instrument doesn't perform as promised, you can send it back within 30 days for a full refund.
- Quality. At a recent trade show we met a government researcher who referred to his 15-year-old AquaLab as an "old warhorse." He made a suggestion−"You'd sell more instruments if the things ever wore out!" AquaLab is built to last.
- Excellent customer service. Decagon's 3-year warranty on the Series 3 and Series 3TE is the best in the industry. Should you experience difficulties with your instrument, Decagon offers unlimited over-the-phone support from knowledgeable technicians.
- Water Activity Experts. Decagon's industry-leading application engineers give water activity seminars worldwide. Can't make it to a seminar? Our database of water activity articles, application notes, and white papers are available online.
4) Does the AquaLab have any measurement limitations?
AquaLab water activity meters can measure virtually any product, from very dry to liquid.
The AquaLab Series 3 and Series 3TE do have difficulty measuring samples containing high concentrations of
propylene glycol (PG). When samples contain a large amount of PG, the propylene glycol tends to vaporize on the
surface of the chilled mirror, altering the reading. Because of this, we offer a "volatiles block" option with
the AquaLab that allows you to measure samples with high levels of PG and ethanol without problems. See our
volatiles block page for more details.
5) What is the range of water activity that the AquaLab can measure?
The AquaLab can measure products that have water activities between 1.0 (pure water) and 0.03 (very dry).
Virtually any product can be accurately measured by the AquaLab.
6) What is the exact size of the sample cups?
The sample cup is 40 mm in diameter and 11.5 mm tall. The volume is 15 ml, but we recommend filling it no more
than half-full (7ml).
7) What's the difference between a standard-model AquaLab (Series 3) and a temperature-controlled model
(Series 3TE)?
The Series 3TE uses thermoelectric components to control the chamber temperature internally. Internal
temperature control is ideal for R&D studies (e.g. accelerated shelf-life), for researching how temperature
changes affect water activity, or if you have significant temperature fluctuations in the room where the
AquaLab will be operating.
8) Is everything I need included when I purchase my AquaLab?
Everything you need for water activity measurement is included with your initial shipment, including 12
Verification Standards and 100 Disposable Sample Cups. After unpacking your AquaLab, you should allow a half
hour for warm-up followed by a 15-minute operational check.
Additional Disposable Sample Cups and Verification Standards are available for purchase from Decagon.
9) Can I connect the AquaLab to my computer?
The Series 3 and Series 3TE come with a standard RS-232 cable for computer connection.
Your computer's terminal program will display the water activity, sample temperature, and time/date for each
AquaLab reading. Decagon's AquaLink software provides that same data with the addition of real-time graphing
and fields for comments and sample names.
Older AquaLab models (CX-1 and CX-2) can also be used with AquaLink, however they use a custom interface cable
that must be procured from Decagon.
10) Do you make a portable water activity meter?
Yes! We offer a battery-powered palm-sized water activity meter called the Pawkit that is designed for quick
checks and inspections. It is accurate to ±0.02aw, so it can only be used where a higher accuracy is not
critical.
11) How do I purchase an AquaLab or a Pawkit?
You can contact us via phone, fax, or email to place an order. If you would like a quotation first, we can
provide you one.
12) Do you have a representative in my country, or do I purchase directly from Decagon?
If you live in the U.S., you can contact us directly for quotations and purchases.
Outside the U.S., we have representatives from whom you can purchase
instruments. They can help you with your specific application and provide you with local service if you need a
repair.
13) How can I get answers to my technical questions?
Phone: 1(800)755-2751 (U.S. & Canada)
1(509)332-2756 (Outside U.S. & Canada)
Fax: (509)-332-5158
E-mail: aqualab@decagon.com
Our working hours are M-F, 8:00am to 5:00pm (Pacific Time).