Water activity Water activity (aw )is defined as the ratio of the vapor pressure of water measured at the food surface (Pw )to the saturation vapor pressure of pure water at the same temperature (Pw º) o w w w P P a =
Water activity Water activity (aw )is defined as the ratio of the vapor pressure of water measured at the food surface (Pw )to the saturation vapor pressure of pure water at the same temperature (Pw º) o w w w P P a =
Water activity For a cup of water, the vapor pressure over the surface is measured as the saturation vapor pressure, and aw is 1. When there are solutes in the water such as sugars, salts, etc. the vapor pressure over the water surface is lower than the saturation vapor pressure, and aw is reduced to some value less than 1. The reduction in water activity depends on the type of solutes present and their levels
Water activity For a cup of water, the vapor pressure over the surface is measured as the saturation vapor pressure, and aw is 1. When there are solutes in the water such as sugars, salts, etc. the vapor pressure over the water surface is lower than the saturation vapor pressure, and aw is reduced to some value less than 1. The reduction in water activity depends on the type of solutes present and their levels
Water Activity For food products, the water activity is generally less than 1. aw is related to the moisture content of the food, the types and concentrations of different solutes, and the structure or physical characteristics of the food
Water Activity For food products, the water activity is generally less than 1. aw is related to the moisture content of the food, the types and concentrations of different solutes, and the structure or physical characteristics of the food
8.3 table Water Activities and Water Contents of Some Confections Food Water Water Content (%wb) Activity Hard candy 1-2 0.10-0.20 English toffee 2-3 0.20-0.30 Caramel 5-10 0.40-0.55 Fudge 12-20 0.65-0.75 Marshmallow 10-20 0.60-0.75 Fondant 20-30 0.75-0.85 "Water content of solution phase
