The absolute taste threshold refers to the minimum amount of taste needed to detect its presence in sensory perception, according to the University of Calgary. These thresholds vary due to different factors, such as type of stimuli, how they are measured, viscosity, temperature, presence of other taste stimuli and the area of the tongue where the taste is detected.
Absolute taste thresholds also change with exposure. One example deals with salting food. When someone salts and then re-salts food throughout a meal, more of the substance is needed to maintain the same taste intensity because the tongue's sensitivity to salt declines with more exposure. The way to avoid this over-exposure is to taste non-salty foods in between bites.
There are three basic methods to measure the absolute taste threshold. Stanford University reveals that the concentration of tastes can be determined by giving a subject two or three samples, one of which contains the tastant and the other water. The subject is then asked to identify the taste. Concentrations of the taste are altered throughout the experiment to determine the minimum threshold. A similar method measures the recognition threshold, which is the smallest concentration a subject reports having a specific taste. A third type of experiment, known as the supra-threshold measure, attempts to quantify taste stimulus intensity. The difficulty with this method is that qualitative taste varies within a wide spectrum of individuals.