Why Is Food Moisture Content Important

The US Food and Drug Administration (FDA) Food Safety Management Act (FSMA) contains regulations for the US food processing industry, focusing on regulations that prevent food related illnesses. Moisture content analysis in food is the cornerstone of prevention. Water is found in all food products. Too little or too much can alter food properties. Moisture content can affect the physical and chemical properties of food, which directly correlate to the freshness and stability of food products for consumers


When is moisture analysis important?

  • Food quality measurements
  • Determination of food shelf life
  • Legal and labeling requirements
  • Establishing dry weight of food
  • Determining yield
  • Confirming the end of a drying process

  • How is moisture measured?

    The moisture content in food varies greatly. Being that water makes up a large percent of most food products, knowing the expected content can help determine the appropriate analysis method. There are multiple ways that moisture can be measured, and depending on physical and chemical properties of the bound water, moisture analysis can be very challenging. The most common techniques used in moisture analysis include:

    Distillation

    This technique involves mixing the food sample with an immiscible, high-boiling point solvent and distilling off and measuring this volume of water. Distillation methods can sometimes cause adverse chemical reactions. These can be reduced by using lower boiling point solvents, but this will increase analysis time.

    Dielectric Method

    The electrical properties of water can also be used to determine moisture content in some foods. This is done by measuring the change in resistance to an electrical current which is passed through the sample. This method is only useful in process control measuring where the moisture content is already known. It is also only useful for samples with a maximum moisture content of up to 35 percent.

    Hydrometry

    Hydrometry measures the density or specific gravity of the food sample. This method seems to work best with samples that contain only one solute in a medium of water. For this reason, it has limited applications and works best with beverages, salt brines, and sugar solutions.

    Refractometry

    This method can determine the moisture content by measuring the refractive index in foods. The results are more qualitative. Knowing that the refractive index increases with concentration, makes this method commonly used to determine sugar concentration in foods, although is only accurate for pure sucrose solutions.

    Infrared Spectroscopy

    Infrared (IR) spectroscopy measures the absorption of radiation by molecules in foods. The concentration can be determined by the amount of energy that is reflected or absorbed. This method is useful in determining the total solids in a liquid sample.

    Chemical Analysis

    Chemical analysis typically involves using a Karl Fischer titrator. This method is especially useful in determining moisture in foods with low moisture content. It is fast, accurate and does not use heat. The downside is that chemicals are needed, and the terrible odors of the pyridine used can make this method unpleasant.

    Oven Drying Methods

    This method works by measuring the weight of the food sample before and after the drying procedure, allowing a percent moisture to be calculated. Depending on the sample type, this can take anywhere from 1-18 hrs. Since the period for analysis is long, this method is typically used to establish a reference point.

    Moisture Analyzers

    Moisture analyzers can quickly measure moisture on virtually any substance. This method uses the same principles as the oven drying method. The main difference is the heat source that is used. Typically, moisture analyzers use infrared or halogen heating elements. Samples are heated more quickly and user error is eliminated with an integrated balance. This allows for percent moisture to be calculated in a reasonable amount of time, allowing for profitability.

    cole-parmer symmetry mb-t touch-screen moisture balancesThe Cole-Parmer® Symmetry® Touch-Screen MB-T Series Moisture Balance is gaining popularity in the food testing and quality markets as it can produce both reliable and consistent results in as little as 3-10 minutes depending on sample. The touch-screen display and intuitive menu designed for easy operation. The home screen is customizable to meet your individual needs. An IR Emitter heating element allows for consistent and controlled temperatures that prevent sample burning.

    Other innovative features include advanced communications with USB, RS-232, Ethernet, and Wi-Fi; hands-free operation utilizing IR proximity sensors; various heating modes with preset temperature for testing moisture content of different samples; a database capable of storing large amounts of sample data; dynamic temperature controls allowing faster drying times; statistical analysis; drying process visualization, and more.

    If you need timely results from a user-friendly and powerful analysis system, the Cole-Parmer Symmetry Touch-Screen MB-T Series Moisture Balance is an ideal choice.

    For more information go to ColeParmer.com/Symmetry or call our technical product experts at 1-800-323-4340.