Taste transduction: Linkage between molecular mechanisms and psychophysics

How Chemical and Sensorial Markers Reflect Gentian Geographic Origin in Chardonnay Wine Macerated with Gentiana lutea Roots?

A Burgundian Chardonnay wine was enriched with Gentiana lutea root powders originating from two French mountain sites (Massif Central and Jura) in order to prepare semi-dry gentian aromatized Chardonnay wine-based drinks. These novel alcoholic beverages were chemically and sensorially characterized for evaluating if the gentian geographic origin influenced bitter and elemental and volatile composition and sensory profiles in the final products. For that, the chemical fingerprint of gentian powders and wines were carried by headspace solid phase microextraction gas chromatography coupled to mass spectrometry (HS-SPME-GC), liquid chromatography coupled to diode array detector (LC-DAD) and inductive coupled plasma optical emission spectroscopy (ICP-OES). The mineral and volatile analysis show that the geographic distinction is more obvious in gentian powders compared to gentian macerated wines. Interestingly the maceration process in Chardonnay wine involves extraction processes revealing statistical distinctions in other chemical markers of gentian origin, like for amarogentin and loganic acid or some mineral elements such as barium and aluminum that affect undoubtedly bitterness perception and sensory properties in macerated wines compared to unmacerated wine. Additionally, the gentian volatile 2-methoxy-3-sec-butylpyrazine and the Chardonnay wine volatile ethyl-9-decenoate differentiated, respectively by extraction and powder adsorption mechanisms could be responsible of more subtle sensory differentiations between macerated wines from two distinct gentian origins.

Tannins in Food: Insights into the Molecular Perception of Astringency and Bitter Taste

Astringency and bitterness are organoleptic properties widely linked to tannin compounds. Due to their significance to food chemistry, the food industry, and to human nutrition and health, these tannins' taste properties have been a line of worldwide research. In recent years, significant advances have been made in understanding the molecular perception of astringency pointing to the contribution of different oral key players. Regarding bitterness, several polyphenols have been identified has new agonists of these receptors. This review summarizes the last data about the knowledge of these taste properties perceived by tannins. Ultimately, tannins' astringency and bitterness are hand-in-hand taste properties, and future studies should be adapted to understand how the proper perception of one taste could affect the perception of the other one.

Revision: Percepción del gusto. Aspectos fisicoquímicos y psicofísicos / Review: 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 site, changes in the neurophysiological signal, and changes in the psychological response. Food aromas, as part of the flavor sensation, exert their influ ence 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 other 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.

Sensor arrays for liquid sensing--electronic tongue systems

Electronic tongue systems are multisensor devices dedicated to automatic analysis of complicated composition samples and to the recognition of their characteristic properties. Recently, the number of publications covering this topic has significantly increased. Many possible architectures of such devices were proposed: potentiometric, voltammetric, as well as approaches embracing mass- and optical-sensors. For the analysis of sensor array data, various pattern recognition systems were proposed. All of these topics are summarized in this review. Moreover, additional problems are considered: miniaturization of electronic tongues and hybrid systems for liquid sensing.

Polyphenols: factors influencing their sensory properties and their effects on food and beverage preferences

Bitterness and astringency are found in a variety of foods, including nuts, fruits, chocolate, tea, wine, and soymilk. In fruits and beverages, the taste of bitterness and the tactile sensation of astringency are elicited primarily by flavanol polymers (proanthocyanidins or condensed tannins). Variations in proanthocyanidin composition, such as polymer size, extent of galloylation, and formation of derivatives, affect both bitterness and astringency. In beverages, other factors also influence these sensations, including the pH and the levels of ethanol, sweetness, and viscosity. Similarly, foods eaten with beverages can influence astringency. For example, eating dark chocolate increases the astringency of red wine more than does milk chocolate. Individuals perceive astringency differently because of variations in salivary flow rates, and preferences for and acceptance of a product may vary tremendously among individuals; decreasing bitterness and/or astringency may not increase preference. Factors influencing bitterness, astringency, and individual preference decisions are discussed.

Anion size of sodium salts and simple taste reaction times

Simple taste reaction times (RT) and taste intensities were measured in adult humans for 100-mM aqueous solutions of sodium chloride, acetate, glutamate, ascorbate, and gluconate flowed over the anterodorsal tongue with a closed liquid delivery system. Results from 12 subjects showed a significant increase in RT with molecular weight of the tastant, and a correlation of 0.941 between RT and the square roots of anionic weights. A multiple regression analysis controlling for perceived taste intensity indicated that RT increased linearly with the square root of the anionic weight. These findings support a model that includes both the permeability of ions through the tight junctions between the taste receptor cells of fungiform papillae taste buds and the effects of ions at apical portions of the receptor cells. They also suggest that gustatory transduction of sodium salts in humans normally involves intercellular spaces of taste buds as part of the functional sensory structures, in addition to individual taste receptor cells.

Amiloride and vertebrate gustatory responses to NaCl

Amiloride at < or = 1 microM may block epithelial Na+ channels without affecting other cellular mechanisms, and attenuates gustatory responses to lingual NaCl from the chorda tympani nerves (CT) of gerbil, hamster, rhesus monkey, and several strains of laboratory rat and mouse, and from glossopharyngeally innervated frog taste-receptor cells; at 5 microM to 50 microM, also from Wistar rat and mongrel dog CT. Affected units responded more to NaCl than to KCl. Suppression of CT responses to KCl, HCl, NH4Cl, or saccharides also occurred in some mammals, but amiloride did not elicit responses. Taste-dependent behaviors towards NaCl or KCl were altered. DBA and 129/J laboratory mice, and mudpuppy, were unaffected by amiloride. In humans, 10 microM amiloride both produced taste reports and reduced total intensity of NaCl and LiCl by 15-20%. NaCl and LiCl sourness, and KCl and QHCl bitterness declined, but saltiness generally did not change. Effects on sweetness were inconsistent. Amiloride-sensitive gustatory mechanisms were prominent in some mammals, were not necessary for responses to NaCl, and were of minor importance for human taste.