Unbound water, defined

BOUND AND UNBOUND WATER. If an equilibrium curve like those in Fig. 24.3 is continued to its intersection with the axis for 100 percent humidity, the moisture content so defined is the minimum moisture this material can carry and still exert... 

Water activity a ) is another critical factor. It is defined as the accessible or available water for the growth of the microorganism. It gives the amount of unbounded water available in the immediate surroundings of the microorganism. It is closely related, but not equal to, the water content. It is represented as... 

The volume of distribution may be defined with respect to blood, plasma, or water (unbound drug), depending on the concentration used in equation (1) (C = Cb, Cp, or Cu). 

If this occurs it takes place in the first solvation shell. These are water molecules with which the ion interacts strongly and are coordinated to the ion. They thus move with the ion and could be termed bound water. Often all of the first solvation shell water molecules can be considered to be primary solvation, but some workers feel that this need not necessarily be the case. Some water molecules may be in the first solvation shell but are not bound, and do not move with the ion. It becomes necessary to define a criterion for distinguishing bound from unbound molecules, i.e. primary solvation or not. The criterion used will be determined by the experimental technique which is being used to measure it. Unfortunately, different experiments may actually measure different properties. 

Chang et al. (1991) have studied the dehydration process in relation to IM meats. They stated that if the unbound moisture in meats is defined as that which exerts water vapor pressure like that of pure water, all unbound moisture must evaporate before equilibrium can be achieved with air that is less than saturated. In other words, the water will evaporate until the water vapor pressure of the meat is equal to the partial water vapor pressure in the air. Data on the equilibrium moisture content-relative humidity (i.e., isotherms) of meat or meat mixtures are needed over a wide range of temperatures for dehydration applications. For example, isotherms for meat/meat mixtures below ambient temperature are needed for salami and raw ham, and isotherms above steam temperatures are needed for high-temperature finished dried IM meats (Chang et al, 1991). 

Despite its simplicity, the interaction matrix captures the central interactions and relations. The matrix clearly illustrates how external impact and events propagate through the system via internal processes defined in the interaction boxes. The exposure to water and atmosphere govern the development of the aqueous chemistry in the imboimd layers. The effect of the three significant ways for water, and two different ways for gas, to enter the unbound layers were demonstrated and the following conclusion is made. 

Evaporation. Evaporation from liquid spills onto land and water has received substantial attention. Land spills are better defined as many spills occur into a dike or other retention system that allows the pool size to be well estimated. Spills onto water are unbounded and calculations are more empirical. 

The amount of water in a porous body such as the textiles at the EMC is defined as bound water and it is absorbed by the textile fibers. When the textile is unable to absorb more water, all excess water is defined as unbound moisture. The unbound moisture is often found as a continuous liquid within the porous material. 

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