Food Engineering
Relative humidity RH
The ratio of the partial pressure of water vapour in air to its saturation pressure at the same temperature, as a percentage.
Real-life application
What a food warehouse or spice storage room controls to stop products absorbing moisture and clumping or growing mould.
Related terms
Water activity
Food ChemistryThe ratio of the vapour pressure of water in a food to the vapour pressure of pure water at the same temperature. It measures how much water is available for microbial growth and chemical reactions — not how much water is present.
Psychrometric chart
Food EngineeringA chart relating dry bulb temperature, wet bulb temperature, humidity ratio, relative humidity and enthalpy of moist air.
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