Perception of taste. Physiochemical and psychophysical aspects

Flavor is perceived through two human senses simultaneously: the sense of t aste, operating in the mouth, mainly in the tongue, and the sense of smell in the nostrils, where aromas are detected. The stimuli responsible for aro ma perception are volatile compounds; their nature and properties as well a s the mechanisms of perception have been widely studied. This is not the ca se 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 dedic ated to sweet taste for obvious economic and nutritional reasons. In this p aper, the present knowledge on the nature of the taste stimuli, on the mech anisms of their perception and on the interactions among them is reviewed. The effects of interactions with other sensory attributes (aroma, color, te xture) are also reviewed. Interactions may be due to different causes: phys ical and chemical interactions among food components, competition at the re ceptor sire, changes in the neurophysiological signal, and changes in the p sychological response. Food aromas, as part of the flavor sensation, exert their influence on taste perception, as taste compounds affect aroma percep tion. 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 infl uence of texture (viscosity, consistency, hardness) mainly on the sweet tas te has been extensively studied. Some contradictory results on how texture affects sweet or other tastes are still not satisfactorily explained. The s tudy of these effects has been intensified in the last years, mainly becaus e they are an important aspect of the flavor release phenomenon, so decisiv e for optimization of formulated foods.