Water Activity Meters in Action: Food Industry Applications

A practical guide to Water Activity Meters (aw meters), used throughout the food production industry to drive standards of product safety and quality.

Water Activity Meters, commonly known as aw meters, are essential tools across food production, offering a fast and reliable way to measure the amount of free water in products – a key indicator of microbial risk. From biscuits and cheeses to ready-to-eat meals and spices, aw meters support consistent quality across a wide range of food types.

This practical guide explains how aw meters are used in daily operations, highlights their benefits, and offers expert advice on choosing the right model for your site.

Learn more about the Klipspringer Water Activity Meter Kit

Help Guide: Water Activity Meters vs. Moisture Analysers

What is a Water Activity Meter?

A Water Activity Meter (also known as a aw meter) is a precision instrument that gauges the amount of free or unbound water in a product – specifically, the water that’s available to react biologically or chemically.

Unlike total moisture, which includes water held tightly by ingredients, this free water can fuel the microbial growth of bacteria, yeast, and mould – posing a significant food safety risk.

aw Meters: Applications in Food Production

Water Activity Meters (aw Meters) are used throughout the food production industry for a wide variety of applications. Below are five of the most common examples:

Bakery and Snack Products

Baked goods, such as biscuits and crisps, typically require low aw levels to maintain their distinct texture, something that is vital for product quality and consistency.

Water activity also impacts the rate at which mould grows, so is essential for determining the shelf life of these products.

Confectionery and Chocolate

Products that contain a high amount of sugar are highly sensitive to changes in water activity. Even slight increases can lead to stickiness, spoilage, or sugar bloom (a white/grey coating forms on the surface of the product).

The use of a Water Activity Meter helps to safeguard against this.

Dairy and Meat Processing

Cheese, cured meats, and dried dairy powders are at serious risk of microbial spoilage if aw levels are left to rise too high.

Using a Water Activity Meter to obtain accurate and reliable measurements helps manufactures to balance shelf life with safety, particularly for ready-to-eat and high-risk products.

Powders, Spices, and Dry Ingredients

Low-moisture ingredients, such as protein powders, spices, and seasonings, can still pose food safety risks if water activity levels creep above safe thresholds.

They are also prone to clumping, something that could seriously impact the final texture and taste of a product.

Ready-to-eat Products

From sandwiches and salads to pasta pots and sushi, ready-to-eat products often combine components with high and low levels of moisture.

If aw levels are too high in one component, microbial growth will occur at a faster rate, putting consumers at risk.

NOTE: Water Activity Meters are unsuitable for juices (syrup), food and beverages containing alcohol, and acidic products like vinegar.

The Key Benefits of a Water Activity Meter

Water Activity Meters are best known for ensuring product safety, maintaining product quality, and determining shelf life. However, there are additional benefits to consider:

Food Safety

The aw levels of a product directly impacts the rate at which it spoils, but careful monitoring can help to slow down the growth of mould and bacteria.

Shelf Life

An accurate and reliable understanding of aw levels will often give teams the opportunity to increase the shelf life of a product, without compromising on food safety.

Product Quality

Moisture content has a significant impact on the taste and texture of a product. Water Activity Meters are used throughout the industry to ensure consistent results.

Packaging

Water Activity Meters (aw Meters) can also help to inform packaging choices, with elements such as barrier films validated against aw readings to ensure stability.

Waste Reduction

Microbial spoilage or a reduction in product quality often results in customer complaints, product recalls, and wasted stock – all at significant cost to a business.

On-Site Efficiency

Rapid readings allow Quality Assurance Teams to test multiple batches quickly and easily, without compromising on accuracy. This helps to avoid production bottlenecks.

What to Look for When Purchasing a Water Activity Meter

Choosing the right Water Activity Meter (aw meter) is all about finding a model that complements your workflow, ensures accurate results, and supports compliance. Below are five key features to look out for when purchasing a Water Activity Meter for your food production site:

Feature	Key Benefits
Generous sample capacity	A larger measuring chamber will allow you to test more representative material in one go. This will speed up the sampling process and reduce the risk of batch variability.
Automatic data logging	An automatic data logging function will enhance compliance, ensure audit-readiness, and reduce the risk of human error. Try to find a system that complements your site’s workflow, with enough space for a significant number of measurement logs.
Fast, accurate readings	If your Water Activity Meter can generate fast and accurate readings, this will prevent bottlenecks from forming. It will also speed up the process of taking preventative action if there is anything wrong with the aw levels of your samples.
Option for advanced analytics	If your process would benefit from PC connectivity and the transfer of data, consider a Water Activity Meter with a USB Data Interface and Memory Software. This will make it easier to analyse data and track trends.
Multiple parameters in one device	Save space, time, and cost with a device that measures multiple parameters. Some Water Activity Meters will also measure parameters like humidity, dew point, and equilibrium moisture content.

The Klipspringer Water Activity Meter

Measure relative humidity, absolute humidity, dew point, equilibrium moisture content, and aw
Automatic datalog (up to 10,000 logs)
Integrated fan ensures rapid conditioning
USB Data Interface and Memory Software
UKAS calibration included

That brings us to the end of our practical guide to Water Activity Meters and their applications.