Water Activity Meters | Water Activity Testing & Measurement

Water Activity Meters & Measurement

Lab Touch – Water Activity Meter

Rated 4.75 out of 5

Water Activity Meters & Measurement

Lab Swift – Water Activity Meter

Rated 4.33 out of 5

What Is Water Activity Measurement?

Water activity indicates the energy of water, which determines if it is biologically available to these microorganisms. As it relates to manufacturing, water activity content also affects a product’s texture, taste, color, nutritional value, and its shelf life. Every species of microorganism, such as bacteria, yeast, or mold, has a minimum water activity value at which they will grow. If the water activity of their environment should drop, their growth is no longer possible.

Why Measuring Water Activity Matters

Measuring the water activity of the energy of water in any product affects both the product quality and its shelf-life. This factor is particularly critical in highly regulated industries such as pharmaceuticals, food, and cosmetics. If the energy of the water in a product is too high, for example, there is a risk of its contamination by microbial growth. In addition, if the storage humidity for a product is too high, it can increase the water activity and lead to clumping, changes in consistency or taste, diminution of nutrients which affect the product’s value, as well as markedly reducing its storage and shelf-life.

Well-documented and scientifically established data guidelines that are also supported by FDA regulations outline these thresholds of microbial limits using a water activity (aw) range or scale. This water activity (aw) range provides the lowest rating for inhibition of microorganisms. In addition, identifying the ideal water activity for any product will provide data to support minimizing the risk of other degradative chemical and physical reactions that, for example, affect shelf life in foods and industrial products.

Pure water has significant, measurable energy and is classified as having a water activity of 1.00. As water in a product interacts with other polar materials in the product, the water’s energy, and hence the water activity (aw) decreases. The degree to which the energy of the water is reduced depends on the type and nature of the other ingredients. The lower end of the water activity measurement scale is zero, but this value is only theoretical and cannot be achieved.

How Water Activity Affects Manufacturing

Understanding and documenting how water activity is affected by different material substances provides valuable information. Using this information provides a way for researchers/manufacturers to take proactive measures to lower a products’ water activity content as they seek to improve the microbial, chemical and structure stability of foods, pharmaceuticals, and other materials.

Using an analyzer to test water activity makes it possible to monitor, control, and optimize product manufacturing and preservation processes, thereby ensuring physical, chemical, and microbiological stability of moisture-sensitive products. Therefore, measuring water activity is a key tool for numerous industries to remain regulation compliant.

In addition, manufacturers of foods and pharmaceutical products must, for example, show to the FDA that the water activity of a product has declined to such an extent that bacteria can no longer grow. This metric can be determined by using devices that measure water activity which gauge the water vapor pressure generated by the water molecules in foods and other products not bound to water-binding sites and are a key parameter in the quality control of all shelf-stable materials.

Tools for Accurate Water Activity Measurement

You already know that measuring water activity is important to maintaining the high product quality and product shelf life you strive for. Whether you are measuring water activity in foods or in other applications, the power, quality, accuracy, precision, and excellence of your water activity testing equipment is of the utmost importance to you. That’s why we’d like to introduce you to a brand that can guarantee the highest quality and innovation – the Novasina Swiss line of water activity meters.

Novasina Water Activity Meters

The Novasina brand developed a unique electrolytic measuring sensor that enables highly accurate measurement of water activity (aw-value). Novasina’s precise water activity equipment is used around the world in many industries from food and pharmaceuticals to oil and chemicals. The water activity testing devices can be used for measuring the water activity in processing and quality control on the production line, or for laboratory content analysis and product development.

SAL T standards savings 10.27

Compare Novasina Models

We offer three incomparable Novasina Models to provide the volume, speed, and accuracy required by the various industries that perform water activity measurements: The Lab Swift, economical water activity meter, The Lab Touch, a mid-range choice in water activity equipment, and The LabMaster Neo, widely acknowledged as the new global standard in water activity measurement for its power, quick and highly accurate readings, and its precision.

In addition, Neutec highly recommends that you to use a filter with the sensor to protect it and to prolong its life span – to choose the filter that works best for your sample- click here

Maintenance and Support Services

Our in-house team of specialists and highly trained engineers will take care of servicing, maintaining, software installation, and calibrating your water activity equipment for you. Let us know if you need any assistance in selecting or maintaining these devices!

What solution is best for my application?

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Water Activity Meter Resources

Watch our video about devices for measuring water activity and how they can improve your product.

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How does the measurement of water activity in my products implicate their shelf life?

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Which water activity measuring device will work best with my application?

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Water Activity Meters Buying Guide

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Pharmaceutical Trends: Water Activity Measurement and USP <922> Water Activity Content Method

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Are you a water activity expert?

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FREQUENTLY ASKED QUESTIONS

How do you measure water activity?

This action is performed by comparing a product’s vapor pressure against pure water under the same conditions. The most accurate way to measure water activity is by using a water activity meter.

Why is it important to measure water activity?

Why is water activity measurement important? Water activity is a critical component in determining the quality and safety of foods, pharmaceuticals, and cosmetics. It gauges microbial growth to enable manufacturers to make adjustments to inhibit spoilage and to maintain a consistent product.

How do you calculate the activity of water?

The formula for calculating water activity is aw = p/ps, where p represents water vapor pressure above the product, and ps is the water vapor pressure above pure water. Additionally, accurate water activity is influenced by temperature, as this affects how water interacts with products being tested.

What is a good water activity?

According to the Food and Drug Administration (FDA), a product’s equilibrium relative humidity (ERH) must be lower than 0.95 to reduce the amount of moisture required to support the growth of bacteria, yeast, and mold to extend a product’s shelf life.

Why is water activity standardized at 25°C temperature condition?

Water activity is greatly affected by temperature, thus its standardized at 25°C and that is the temperature used by regulatory agencies.

Why do I need temperature control?

Temperature control assures higher accuracy results, provides a constant equilibrated environment for repeatable testing and complies with regulatory testing that is carried out at 25°C.

The Novasina water activity meters come with calibration standards, what exactly are they used for?

The calibration standard salts that come with the unit are used in two ways. They are used for calibration, so there is always an accurate curve to compare your samples to. They are also meant to provide you with a means for verification daily. This way you can identify any drift in your readings and correct it or call us for support,

Can I use the calibration standards multiple times?

Yes, you can certainly use the standards multiple times. These salts are NOT disposable. They have a shelf life of 2–4 years depending on factors such as storage conditions (storage container must be well closed), frequency of use, exposure to light and the value of the standard.

How often should I calibrate my unit?

Calibration frequency is based on your internal SOP but a good rule of thumb is to carry out a calibration at least once per month and to carry out a verification at the start of each day.

Our samples contain alcohol and other volatiles, could we measure our samples with Novasina units?

Yes, the Novasina units in conjunction with special protective filters can be used to measure samples that contain volatiles. We strongly recommend the use of filters if there is any doubt to protect and prolong the life of the sensor.

Do the units require extraordinary maintenance?

No, Novasina units are very simple to use and do not require much maintenance. We suggest keeping the units clean and wiping them down at the end of each day with a cloth and keeping the measuring chamber clean and free of debris. Also, we recommend having a PM (Preventative Maintenance) completed once a year to keep the unit running in top condition.

Our lab requires our instruments to have certified calibrations completed on a regular basis, does Neutec provide these services?

Yes, Neutec provides 3 different services for the water activity units. A PM (Preventative Maintenance) service, a VC (Verification Calibration) service and a CC (Certified Calibration) service. All three of the services come with completion documents and the Certified Calibration is also 21 CFR Part 11 compliant from a government certified laboratory.

I see the PM service mentioned a few times, what exactly is that and why should I consider it?

A PM (preventative maintenance) is a proactive measure taken to ensure that your unit does not suffer any damage due to preventable issues caused by wear and tear and that it continues to run like new for years to come. A PM is completed by performing a full “tune up” of the unit, which includes full diagnostics, calibration, replacement of pre-filters, internal sterilization, cleaning and certification.

We need results fast. How long does the water activity test take?

It will mainly depend on the sample itself, as different materials release water at different rates. Our units report the AW value once the equilibrium point has been reached. Yet you can stop the unit at any time and take a reading. Waiting to reach stability is the most accurate method. Speeding this process may result in inaccurate results generated and recorded.

What are the sensor filters used for and how do I choose the right one for my application?

These specially designed filters shall be mounted in front of the sensor and used to provide protection against chemical contamination and degradation of the resistive electrolytic sensor element. As the inner part of the sensor consists of a liquid, volatiles which dissolve and dissociate are extremely dangerous and harm the sensor in a very short time. Be aware that sensor failure due to chemical contamination by NOT using an appropriate chemical filter is not covered by warranty and replacement goes 100% on the user's account. For that reason, it is inevitable to check sample composition for volatiles PRIOR to order the instrument. We will ask you those questions and will hand you this document for signing. We fully understand if sample compositions and/or recipes cannot be shared with us but somehow we must gather the information, respectively ensure, that we can offer the best possible solution for a reliable, accurate and repeatable water activity measurement of your samples. Many questions about changing interval were and are brought to our attention. Unfortunately, there is no precise guideline but a rule of thumb:  If you do less or equal than 10 measurements a week, change filter every 6-12 months  If you do more than 10 measurements a week, change filter every 3-6 months  If instrument is in use, day and night, change filter every 2 months Please read the operating instruction manual of the water activity meter as well to learn about the procedure how to find out the optimal chemical filter changing interval. It is important that the filter is changed from time to time as it is of saturation type. Once saturated, volatiles will pass through and harm the sensor. Be aware that sometimes filter combinations must be used to get highest protection efficiency. As soon as ethanol is involved, our alcohol-resilient sensor (CM-3 or awSens-ELS) must be used. If ethanol is present in conjunction with other volatiles, select the alcohol-resilient sensor plus the respective filter(s) from the selection list. Note that chemical filters will extend the measurement time as the water vapor has to pass through the filter but it will not affect the measurement value. If you have doubts about the procedure or feel unsure how to work that out, please do not hesitate to contact us. Download the Filter Selection Guide PDF from any water activity meter product page.