Perception of taste.: Physiochemical and psychophysical aspects

Flavor is perceived through two human senses simultaneously: the sense of taste, operating in the mouth, mainly in the tongue, and the sense of smell in the nostrils, where aromas are detected. The stimuli responsible for aroma perception are volatile compounds; their nature and properties as well as the mechanisms of perception have been widely studied. This is not the case for the taste stimuli, consisting of non-volatile compounds responsible for the accepted four basic taste sensations: sweet, sour, salty and bitter. The available information on taste perception is almost exclusively dedicated to sweet taste for obvious economic and nutritional reasons. In this paper, the present knowledge on the nature of the taste stimuli, on the mechanisms of their perception and on the interactions among them is reviewed. The effects of interactions with other sensory attributes (aroma, color, texture) are also reviewed. Interactions may be due to different causes: physical and chemical interactions among food components, competition at the receptor sire, changes in the neurophysiological signal, and changes in the psychological response. Food aromas, as part of the flavor sensation, exert their influence on taste perception, as taste compounds affect aroma perception. Color may also modify the perception of a particular taste, but very few studies have been dedicated to this effect. On the ether hand, the influence of texture (viscosity, consistency, hardness) mainly on the sweet taste has been extensively studied. Some contradictory results on how texture affects sweet or other tastes are still not satisfactorily explained. The study of these effects has been intensified in the last years, mainly because they are an important aspect of the flavor release phenomenon, so decisive for optimization of formulated foods.