FOOD 2400 Lecture Notes - Lecture 1: Water Activity, Sorption, Desorption
10 Aug 2018
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Unit 1 learning outcomes: list some unique chemical and physical properties of water and ice. Physical properties: water has relatively high melting and boiling temperatures. Chemical properties: describe some interaction of water with other molecules. Water activity is the water available to participate in reactions and for microbial growth: explain the 3 regions represented in a sorption isotherm. Table in notes: explain the importance of sorption isotherms to food stability, define what is meant by hysteresis. Is the water that remains unfrozen at some prescribed temperature below 0 c, usually at -20 c. Is the amount of water in a system that is unavailable as a solvent. It exhibits reduced molecular mobility and possesses other significantly altered properties as compared with bulk water in the same system. It cannot act as a solvent and does not freeze at -40 c.
