Quality control procedures across a broad spectrum of manufacturing, packaging and similar operations frequently include checks on the amount of moisture contained in a product.  Moisture content in many instances is strongly regulated by federal and professional organizations and has direct applicability to important criteria.  Among products where moisture content plays an important role are pharmaceuticals, plastics, wood chips, fabrics, paint, body lotion, seeds, tobacco, potting soil, dried fruits and vegetables, catsup, and detergents. In this blog section we will discuss the role of various testing instruments utilized for moisture analyses, including Moisture Analyser and Hot Air Oven.

Why is the Moisture Content Important?

Some of the common household experiences with improper moisture content include soggy chips and popcorn, clogged salt shakers, and mortar solidified in the bag.  These unfortunate results generally occur during storage in the home or garage; it’s the manufacturer’s job to be certain that these and similar products exhibit the correct moisture content prior to packaging and shipment. 

From another viewpoint, too much moisture in a product means the buyer is paying for water rather than the expected measure; too little means the manufacturer is delivering more product than being paid for

Determination of accurate Moisture Content

Two activities apply here; controlling and confirming moisture content.

Bulk methods of controlling moisture content are usually accomplished in drying ovens where recommended time and temperature criteria are applied.  Quality control steps and confirmation that criteria are met are accomplished by sampling the product, typically just prior to packaging.

Moisture content confirmation is accomplished under controlled conditions where small samples (usually weighed in grams) of the product are subjected to laboratory moisture analyser. 

Moisture Analyser

Thermogravimetric moisture analysis calculates moisture content based on loss of weight on drying (LOD).  As one example, halogen heaters are paired with an analytical balance that can be programmed to conduct measurements of small samples (in grams) under various scenarios including time, temperature and how heat is applied also called the drying profile.  The samples are dried until their weight is constant; the difference between starting and ending weight representing moisture content.

Some laboratory moisture balances use infrared heaters although these can take slightly longer to reach the operating temperature necessary to conduct the analysis.

Hot air ovens

Drying ovens use circulating hot air, sometimes under vacuum, to establish reference moisture content.  They can process large samples and multiple samples at a time but can take hours to produce the data and are labour intensive.  This method is frequently cited in laws governing determining moisture content in food.

Moisture analysis is an exacting process requiring precision equipment operated by trained personnel.   A major advantage of laboratory moisture analysers is that once the method is programmed into the instrument, the technician needs minimal training and expertise to test samples and obtain relatively reproducible results.  This is quite different from most of the other methods discussed here. 

For more information about testing instruments kindly contact our team.