Food Engineering
Glass transition temperature Tg
The temperature at which an amorphous solid changes between a rigid glassy state and a rubbery state.
Real-life application
Why crackers and papad turn soft and lose their snap when left open in humid weather.
Related terms
Freeze drying
Processing & PreservationDehydration by freezing the food and subliming the ice under vacuum below the triple point of water, followed by desorption of bound water.
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.
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