In the following article, we will answer the most common questions surrounding Water Activity Meters and their use within the food production industry.
Water Activity Meters are used throughout the food production industry to drive standards of food safety and product quality.
To help you understand more about this popular instrument, we have created an essential FAQ Guide, covering the following areas of interest:
What is a Water Activity Meter and how does it work?
A Water Activity Meter measures the amount of unbound (or free) moisture in a product. It measures the ratio between the vapour pressure of water in a test sample and the vapour pressure of pure water at the same temperature. This ratio is also known as the aw value.
Below is a video tutorial that will guide you through the process of using a Water Activity Meter:
What are Water Activity Meters used for?
Most commonly, food factories will use a Water Activity Meter to determine a product’s shelf life and to establish the most suitable storage conditions.
The amount of free water in a food item also relates to quality – impacting the taste, texture, and colour of a product.
Water activity levels even reveal crucial information about the nutritional value of a food item, in some cases helping sites to determine the content of proteins and vitamins.
What types of food products can be measured with a water activity meter?
A Water Activity Meter can be used to measure a wide variety of food products, both raw and processed. It is suited to dry food products like flour, biscuits, and spices. However, it is just as compatible with high-moisture food products like cheese, butter, and mushrooms.
It is also common for meat factories to use this instrument to determine if a piece of meat is under or over cooked. Raw meat is also frequently tested, as it has incredibly high levels of water activity, making it susceptible to the growth and survival of harmful microorganisms.
What products are unsuited to measurement using a Water Activity Meter?
A Water Activity Meter should not be used to measure juices (syrup). It is also incompatible with food and beverages containing alcohol, along with highly acidic food items such as vinegar.
How does a Water Activity Meter support food safety?
The readings produced by a Water Activity Meter relate to how a product is going to react with harmful microorganisms such as bacteria, yeast, and mould.
High levels of water activity suggest these microorganisms will grow at a rapid rate. But, if the levels fall below a certain point, this indicates that only non-harmful microorganisms are likely to develop. Or, if the reading is extremely low, this suggests that barely any microorganisms will grow at all.
Understanding the risk levels of harmful microorganisms will help your site to put the relevant food safety measures in place, preventing spoilage and improving product stability.
Every microorganism requires a minimum level of water activity for growth. Below you will find a list of examples, featuring some of the most common threats to food safety:
| Microorganism | Typical Water Activity Level for Growth (AW) |
|---|---|
| Bacteria | 0.91 - 0.95 |
| Yeast | 0.88 |
| Mould | 0.80 |
| Halophilic bacteria | 0.75 |
| Osmophilic | 0.70 |
| Xerophilic mould | 0.65 |
What is the difference between a Water Activity Meter and a Moisture Analyser?
A Moisture Analyser detects the overall moisture content of an item. It weighs a sample, evaporates the moisture, then re-weighs the sample. The second reading is then automatically subtracted from the first – revealing how much moisture has been lost.
Food factories will typically use Moisture Analysers to check their recipes and drive standards of consistency.
The readings generated by a Moisture Analyser relate to a combination of bound and unbound moisture. However, a Water Activity Meter targets unbound (or free) moisture, which is the parameter you need to understand if you want to find out how a product is going to react with harmful microorganisms. Because of this, Water Activity Meters are used to determine the storage requirements and estimated lifespan of products.
The distinctions explored above help to explain why so many food production sites use both Moisture Analysers and Water Activity Meters, instead of just the one instrument – recognising the different functions of both pieces of equipment.
What is an ampoule?
A Water Activity Meter ampoule is the chamber that holds your sample. It can be sealed, helping to create the necessary conditions for accurate measurement. To ensure your Water Activity Meter is driving standards of efficiency, you will need to ensure it has a generous ampoule that is capable of holding a large sample volume.
That is why the Klipspringer Water Activity Meter is compatible with both 186ml and 245ml measuring chambers.
How do I record and share my results?
Although some food production sites still rely on manual records, a growing number of factories are moving towards a paperless approach. This is because a digital set-up helps to drive standards of efficiency, whilst eliminating human error.
The Klipspringer Water Activity Meter offers Bluetooth connectivity, allowing you to transfer your results over to your devices. There is even the option to transfer results directly to a printer.
In addition to this, you can auto-save measurements at specified intervals for future reference and set the device to manually record results.
You now have the answers to the most common questions surrounding Water Activity Meters and the role they could play at your food production site.
If you require any further guidance, we would be happy to help. Our in-house team of experts will provide support and relevant resources.
You can also contact us on 01473 461800 or sales@klipspringer.com. Alternatively, you can use the form below to arrange a consultation.
If you would like further guidance relating to Water Activity Meters, the Klipspringer team would be happy to help. Share your details below and we will be in touch.
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