Measuring Moisture Contents in the Snack Food and Baking Industries

With the steady rise and success of chips, corn curls, cookies, breads etc., the snack food and baking industries have now become more competitive then ever. The most powerful and destructive natural force on earth has taken a stand in the industry as one of the most commonly measured properties in food materials - WATER.

Why is Moisture Content Important?

Almost daily, we are asked two very important questions: "why is moisture content important?", and "how can we test for moisture?". Knowing the moisture content of the materials used throughout the snack food and baking process has become one of the most important concepts in the industry. The process begins with the arrival of raw ingredients. At this time, a Certificate of Analysis is presented to the purchasing plant to verify the validity of the raw materials, which includes the moisture content.

Caveat Emptor - Buyer Beware. The cost of many raw materials is based upon weight. Water is an inexpensive ingredient, and manufacturers often try to incorporate as much water as possible, without exceeding the legal maximum. A simple moisture test on incoming raw ingredients could save the purchasing plant thousands of dollars. Are you paying for free water?

In-Process Moisture Issues

Carpe Diem - Seize the Day. It is at this critical stage of the manufacturing process that moisture content can make or break the product. Excess moisture in mixes can cause clumping and the moisture content will continue to increase during storage, causing the product to deteriorate. A simple moisture test in this area will allow easy adjustments to be made to conditioners and throughout the blending process to keep moisture low and under control.During the food manufacturing process, an understanding and knowledge of the moisture content is necessary to fully comprehend the behavior of foods during processing, mixing, and drying. The mixing, and the certainty of the correct addition of the initial ingredients, optimizes high quality and consistent finished products. 

Moisture Affects Taste and Shelf-Life

Ad Extremum - At Last. The final product is the apple of the eye for the manufacturer; the pride and joy of the job: a successful finished product. The texture, taste, appearance, stability and the shelf life of your final product depend on the amount of water it contains. Don’t waste the taste and have finished products returned because of molding or customer complaints. Knowing the appropriate moisture content will allow your product to be successfully manufactured and sold in one of the worlds leading industries. Checking the moisture content on the finished product will allow verification that your product is the cream of the crop.

Determining Moisture

Because moisture is such an important component of all snack food and baking products, the critical question is brought to our attention..."so, now what?". The moisture content of all samples are determined by measuring the mass of the material before and after the water is removed by evaporation:

% Moisture = (Initial Sample Weight - Final Sample Weight) / Initial Sample Weight

Temperature and time are standardized in loss-on-drying methods to obtain both accurate and repeatable results. However, a standard drying condition or time for all materials does not exist. The optimum drying conditions must be individually determined for each product. Convection, Vacuum and Infrared Drying Moisture Analyzers are the most common methods for moisture analysis.

In a convection oven, the original sample is placed in the oven at a specified temperature and time. Once the product has finished drying, the above equation is used to determine the moisture content. ASTM recognizes the oven method as the standard for testing moisture. However, samples that contain large amounts of carbohydrates have a risk of undergoing chemical changes, and therefore should not be dried in a convection oven. This method can also take up to 24 hours for accurate and reliable results.

Similarly, with the vacuum oven a random sample is taken, pre-weighed, and placed in the oven. However, vacuum ovens use reduced pressure, typically 25-100 mm Hg, which allows for faster drying times when compared to the convection ovens. An air inlet and outlet carries the moisture lost from the material out of the oven, which prohibits the accumulation of moisture in the oven. Because the boiling point of water in a vacuum oven is reduced, drying can be completed faster than a convection oven and problems with degradation of heat sensitive substances can be reduced. This method does not satisfy the urgency of rapid moisture results and will take between 3-6 hours in length and can be quite costly.

With heightened interest in improving quality control, an oven test would not ideally satisfy the necessity of quick results needed to check incoming raw materials, baking mixes, and final products prior to be being packaged. If the end product was taken from the final production line and tested for 24 hours in the oven, and an incorrect moisture content was read, thousands of pounds of bad product would have been produced and distributed. Is one bad test worth the risk of loosing thousands of dollars and, more importantly, the risk of losing loyal customers?

Determined as a well-suited instrument for quick weight loss by the American Institute of Baking (see below chart), the Infrared Moisture Balance offers a high quality and a fast-paced method of drying using inexpensive equipment. The chart below clearly indicates that the Infrared Moisture Balance produces repeatable and accurate results when compared with the standard oven method. Infrared Moisture Balances not only test samples significantly faster, they save floor and counter space, reduce heat in the work area and significantly boost production rates. Also, this saves energy and reduces costs in product manufacturing. Infrared Moisture Balances are easily integrated into existing production lines and QC testing areas.

Moisture Testing Standards

Table IX
Taken from AIB Technical Bulletin
Volume XV, Issue 6

Moisture Content of Yellow Layer Cake

Method	Time	Temp.	Lamp	PS	1-Day Pre-Drying	2-Day Pre-Drying
Oven Method
AACC 44-40	5 hour	100 C	-	-	33.4 +/- 0.1	29.2 +/- 0.00
AACC 44-15A	1 hour	130 C	-	-	33.2 +/- 0.1	29.1 +/- 0.0
Moisture Balance
Digital	6 min	-	125 C	80	33	28.9
Digital	5 (6) min	-	125 C	90	33	29.1
Digital	5 (6) min	-	125 C	100	33.2	29.2
Digital	7 min	-	250 R	60	33.5	29.1
Digital	7 (6) min	-	250 R	70	33.5	29.1
Digital	7 (6) min	-	250 R	80	33.7	29.2

- Values within ( ) refer to 2-day pre-drying
- 125 Watt clear lamp or 250 Watt red lamp
- (PS) Power setting

With an Infrared Moisture Balance, a small, random 5-10 gram sample of material is taken and placed in the heating chamber of the instrument. The beginning weight of the sample is recorded. The water molecules in the material evaporate because the heat from the infrared heat source is absorbed by the sample. With results in as fast as 3-20 minutes, percent moisture or percent solids can easily be determined once the sample is dried. Results are easily reproducible and accurate with the infrared moisture balances because the distance between the heat source and sample remain the same between tests.

Conclusion

With easy access to Infrared Moisture Analyzers throughout production and laboratories, moisture results can be performed numerous times in a single hour! When compared with the 24-hour oven method, the quick results can help manufacturers to create leading products in this competitive industry. With infrared testing, the mystery can be taken out of moisture testing.

For more information, please contact:
CSC Scientific Co., Inc
800-458-2558 or 703-876-4030
Fax: 703-280-5142
Email: testsolution@cscscientific.com

** A special thank you to the American Institute of Baking Technical Bulletin, Volume XV, Issue 6 Determination of Moisture in Bakery Foods for the technical information. **