| Water Activity |
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Information AboutWater Activity |
| CATEGORIES ABOUT WATER ACTIVITY | |
| food science | |
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As the temperature increases, aw typically decreases, except in some Salt and Sugar solutions. Higher aw substances tend to support more Microorganisms . Bacteria usually require at least 0.91, and Fungi at least 0.7. See Fermentation . Water tends to migrate from high aw substances to low aw substances. For example, when Honey (aw ≈ 0.6) is exposed to humid air (aw ≈ 0.7) the honey will absorb water from the air. FORMULAE Definition of aw: : where p is the vapor pressure of water in the substance, and p₀ is the vapor pressure of pure water at the same temperature. Alternate definition: : where lw is the Activity Coefficient of water and xw is the mole fraction of water in the aqueous fraction. Relative Humidity : : Estimated mold-free shelf life in days at 21° C: : SELECTED A<SUB>W</SUB> VALUES EXTERNAL LINKS |
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