Sensory perception, principles

Adsorption. Several kinds of molecules can adsorb onto various surfaces or bind onto macromolecules, thereby lowering their activity coefficients. Binding should not be interpreted here as forming a covalent or an ionic bond, for in such a case the concentration of the substance is indeed decreased. It is well known that for many flavor components the threshold concentration for sensory perception is far higher in a particular food than in water. This means that the activity coefficient is smaller in the food than in water, and a decrease by a factor of 103 is no exception. It may be recalled that many flavor components are fairly hydrophobic molecules, which readily adsorb onto proteins. Because of this, the so-called head space analysis for flavor components makes good sense, since the concentrations of the various components in the gas phase (which is, in principle, in equilibrium with the food) are indeed expected to be proportional to the activities in the food. 

The way an individual occupant of a building will behave to a fire danger is complex. The psychological response of each person is based on their perception of the situation they find themselves in. In order to understand how people perceive the danger of fire it is necessary to consider the principles of sensory perception. 

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