The reason water activity is important to test for, is that it is one of the most critical factors in determining quality and safety of the goods you consume every day. Water activity affects the shelf life, safety, texture, flavor, and smell of foods. It is also important to the stability of pharmaceuticals and cosmetics. While temperature, pH and several other factors can influence if and how fast organisms will grow in a product, water activity may be the most important factor in controlling spoilage.
Most bacteria, for example, do not grow at water activities below 0.91, and most molds cease to grow at water activities below 0.80. By measuring water activity, it is possible to predict which microorganisms will and will not be potential sources of spoilage. Water activity--not water content--determines the lower limit of available water for microbial growth. In addition to influencing microbial spoilage, water activity can play a significant role in determining the activity of enzymes and vitamins in foods and can have a major impact their color, taste, and aroma. It can also significantly impact the potency and consistency of pharmaceuticals.
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Water activity, by definition, is the measurement of water vapor pressure generated by the free, or non-chemically bound water, in foods and other products. The bound water and moisture content cannot be measured directly with this method. The Aw value (range: 0.00...1.00 aw) is an important indicator for the shelf life of foods, pharmaceutical and cosmetic products and it strongly influences the occurrence and growth of microorganisms.
If green coffee is dried too quickly, it can result in higher than .6 water activity, which results in shorter shelf life, and less desirable flavor qualities.
Aw Quick functionality for very fast and precise results
Regular Aw measurement takes about an hour to determine exact Aw value. The ROTRONIC Aw Quick function allows Aw measurement results in 5 minutes or less. The function is nearly as precise as the regular measurement method. It requires an environment with stable temperatures variations which is mostly given in laboratory and indoor applications.
This USB measurement head can be connected directly to a PC and comes in a set, including software
for use as a single instrument or for addition to a system.
The set HC2-AW-USB-SW contains the HW4 software with AW Quick function, thereby opening up all the possibilities of water activity measurement. It can be extended into a multi-station application with up to 64 measurement heads used with a powered USB hub.
• Measurement range: 0…1.00 aw (0…100 %RH), -40…85 °C