Sensation astringent

Black tea taste is primarily a function of the polyphenols, caffeine, and aroma components. Astringency, an important characteristic of the organoleptic sensation, has been described as consisting of a tangy and a nontangy component.95... 

Even higher proline contents have been reported in salivary PRPs these can contain 40-45 mol% proline and also have a substantial amount of glutamine. This protein binds ingested polyphenols, which precipitates the PRPs and removes the lubrication these normally provide. The result is the sensation of astringency (Green, 1993 Haslam and Lilley, 1988). 

Siebert, K. J. and Chassy, A. W. (2003). An alternate mechanism for the astringent sensation of acids. Food Qual. Pref. 15, 13-18. 

Assessment of taste is achieved by sensory analysis, from very simple experiments such as triangular tests aiming at determining detection thresholds to complex descriptive analysis approaches. A method referred to as time-intensity that consists in recording continuously the intensity of a given sensation over time under standardized conditions has been applied to study flavonoid bitterness and astringency properties. 

Breslin, P.A. et ak. Psychophysical evidence that oral astringency is a tactile sensation. Chem. Senses 18, 405, 1993. 

Astringency is an important sensation in most of the alcoholic beverages. Time-intensity measurements have been particularly useful in assessing this phenomenon (Lee and Lawless, 1991), as well as the bitterness of... 

The sensation of astringency is felt differently by tasters [86] probably due to differences in individuals saliva in terms of its protein composition [11, 47]. Astringency is also affected by the structure of the phenolic compounds [88], pH [89], the presence of other substances [90-92], and viscosity [11]. In fact it is believed that complex beverages such as wine and beer have subtle sub-qualities of sensorial descriptors related to astringency (soft, grainy, harsh, green, chalky, etc.), that are not perceived in tannin model solutions, which could be due to the presence of other molecules [87]. 

As described above, astringency is a very complex sensation that occurs in several foodstuff and beverages, involving different kinds of compounds (phenolic compounds, proteins), and that is affected by medium conditions (pH, alcohol, presence of other molecules in solution, etc.). This sensation constitutes one of the main organoleptic properties of red wine and has been a matter of research over the years for wine chemists. Winemakers believe that polysaccharides contribute to the mouthfeel volume of a wine, but this is a rather empirical observation. 

The results obtained directly from compounds isolated from wine and directly involved in the astringency sensation (tannins, polysaccharides, and human sali-... 

The lactic acid bacteria may cause polysaccharides to be released in a wine (Dols-Lafalgue et al. 2007). These compounds can increase the sensation of volume or body of wines, and can also be polymerized with the grape or wood tannins, reducing sensations of roughness or astringency, and producing more complex flavours. 

Gawel et al. (2000) have proposed an interesting hierarchically structured vocabulary of mouth-feel sensations, presented as a Mouth-feel Wheel , to assist tasters in their interpretation of wine astringency. Nevertheless, this new vocabulary seems to be too extensive, which hampers their implementation in a common language. 

The astringency sensation is felt differently by different tasters (Gawel et al. 2001) probably due to differences in individuals saliva, namely its protein composition (Lesschaeve and Noble 2005 Horne et al. 2002). Recently, a study concerning the characterization of basic PRPs in thirteen normal adults has demonstrated that the protein IB9 was only detected in nine adults saliva, while IB7 was not detected at all (Messana et al. 2004). The salivary flow rate was also described as a factor that varies between subjects and can affect astringency perception (Lesschaeve... 

Astringency is a tactile sensation, which is often described as a puckering, rough or drying mouthfeel. The mechanism of its perception is unknown, although it is probably mediated by touch or mechanoreceptors 4). Chemically, astringents have been defined as compounds which precipitate proteins. For water soluble phenols, this has been reported to require molecular weights between 500 and 3000 daltons (5). 

Mouth feel factors are critical in flavor perception. Examples include astringency, pepper bite, menthol cooling, and texture (e.g., softness or hardness as in candy). Sensations, such as crunch after biting into a crisp stick of celery or an apple, contribute to the overall flavor of foods. These mouth feel factors are also... 

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