Moisture Testing: Why Do it, and How Does it Work?

The moisture content in food influences how it looks and how it tastes. Different food materials, including grains, have different moisture content standards they need to meet.  

Where moisture contents deviate from these standards, there can be a detrimental effect to the overall quality and consistency of the product.  

Therefore, it is important to test food and food ingredients for moisture. There are various tools for doing this including:  

• Moisture ovens 

• UGMA Moisture Meters 

• Hand Held Moisture Analysers 

• Near Infra-red (NIR) Analysers 

• Diode Array (DA) Analysers  

Near infrared analysis (NIR) is an effective food-testing technique, which can detect moisture content in wide range of foodstuffs.  

Why Test for Moisture?  

Moisture content in food can affect how it tastes, what it looks like, and how long it lasts.  

Reducing moisture content can extend the shelf-life of some foodstuffs, which therefore has environmental benefits. 

Moisture testing also helps food producers meet their legal obligations for correct food labelling. 

 It helps establish the dry weight of food, and helps determine yields. It is also a useful indicator of when certain production processes such as drying are complete.  

Too much or too little moisture can have detrimental effects on food, food production and profits.  

Moisture in food can be useful, for example, it is an inexpensive way of adding weight.  

Excess moisture can increase the rate of microbial growth, shortening shelf-life or creating spoiled batches. It can also impact on food processing systems, trapping food in pipework during production processes.  

It is a question of balance, depending on the particular type of food involved.  

How is Water Present in Food? 

There are different ways that water is present in food.  

Free water in food is water that is surrounded by other water molecules. You find free water on surface particles, in narrow capillaries, and in pore systems.  

These water molecules are less likely to evaporate at high temperatures. They bind to certain proteins and are difficult to measure accurately as part of moisture content in some foods.  

This type of moisture content is adsorbed water. It is present in the complex cellular patterns of meat and dried fruit.  

Cereal grains absorb hygroscopic moisture from the air, but effective storage requires getting their moisture content correct. They will later be hydrated, but optimum storage will require controlled moisture conditions.  

Moisture Content for Grain Storage  

The ideal wheat moisture content at harvest would be around 13-14% however this is not always possible so harvesting at higher moisture contents is necessary.  

Moisture needs to be at an optimum level when being stored and sold in the marketplace.  

Therefore, grain producers need to reduce moisture content to a suitable level, but not so low that it will affect the overall yield or quality when it comes to selling it.  

Extending the Shelf-life of Food  

If you control the moisture content of food you can make it last longer.  

The shelf-life periods for different foodstuffs are the times within which they are safe for purchase and consumption. Within its shelf-life, any food must maintain its look, feel, smell and taste, along with other chemical properties. Once past its shelf-life, food is then unsafe for consumption.  

Water is essential for growth and metabolism, and supports chemical reactions in food products, therefore, reducing water activity in food can minimise its rate of deterioration.  

During this shelf-life period, the food in question must be able to maintain its look, smell, feel and taste, along with other chemical and physical properties. After this period, it is officially unsafe for consumption and fit only for disposal.  

Controlling moisture content will reduce the growth of bacteria and extend food preservation times.  

This has the potential to reduce food waste by making products last longer.  

However, to control moisture in food, you must be able to measure, monitor and manage it correctly.  

Methods for Moisture Testing  

Depending on the type of food product, moisture testing can occur at various stages of production, including harvesting, storage, processing, and manufacturing.  

The Perten AM5200 grain moisture analyser is a high-frequency UGMA moisture meter that tests for temperature, weight and moisture in grains, oil seeds, pulses and other foodstuffs.  

A key method for rapid moisture testing in food is NIR analysis. This spectroscopic technique is the basis for various moisture-testing instruments.  

For above-line moisture testing, the Perten DA7440 is designed to provide real-time moisture measurements in production environments. This is an ideal testing method for process control.  

For added convenience in on-farm and other location-based moisture testing, there is the GrainSense handheld NIR Analyser, which can provide rapid analysis of moistures, proteins and oil contents.  

NIR analysers can also test for moisture in meat. The Perkin Elmer DA6200 is a portable meat analyser, which tests raw meats and final meat products for moisture along with other properties such as fat and protein content.   

As with all NIR analysers, they offer the benefits of convenience, accuracy, and speed, providing real-time results.  

Testing for moisture in foodstuffs is critical, for business, food safety and environmental reasons. It is a vital aspect of quality and process control, and can help farmers, growers, producers, and manufacturers optimise their products.  

For more details about moisture testing instruments, please call us on +44 (0) 1925 860 401, email info@calibrecontrol.com, or fill in our online contact form.