Sweet tastant

Sugars (= Saccharides) Universal key figures in Sweet tastants ... 

Striem, B.J., Pace, U., Zehavi, U., Naim, M., and Lancet, D. (1989) Sweet tastants stimulate adenylate cyclase coupled to GTP-binding protein in rat tongue membranes. Biochem. J. 260, 121-6. 

In order to study the influence of the pH value on the sweetness enhancing effect of the novel Maillard reaction product, binary mixtures of the tasteless alapyridaine and the sweet tasting compounds glucose, saccharose, or L-alanine were sensorially evaluated in a triangle test using water with pH 5.0, 7.0 and 9.0, and the sweet detection thresholds determined were compared to the threshold concentrations of aqueous solutions containing the sweet tastants alone (Table I). 

The taste threshold concentrations were determined by a triangle test using tap water (pH 5.0, 7.0, 9.0) as the solvent. Factor by which the threshold of the sweet tastant was decreased in the presence of alapyridaine. 

After the saliva has carried the tastants into the taste bud, they interact with the taste receptors on the surface of the cells, or with ion channels, which are pore-like proteins. Salty and sour tastants act through ion channels, and sweet and bitter sensations are mediated by surface receptors. The different taste submodalities rely on specific mechanisms Na+ flux through Na+... 

Odorants and tastants in foods interact in complicated ways. For instance, strawberry odor enhances the sweetness of whipped cream, while peanut butter odor does not, and strawberry odor did not enhance the saltiness of sodium chloride (Frank and Byram, 1988). 

The simplest tastant, the hydrogen ion, is perceived as sour. Other simple ions, particularly sodium ion, are perceived as salty. The taste called umami is evoked by the amino acid glutamate, often encountered as the flavor enhancer monosodium glutamate (MSG). In contrast, tastants perceived as bitter or sweet are extremely diverse. Many bitter compounds are alkaloids or other plant products of which many are toxic. However, they do not have any common structural elements or other common properties. Carbohydrates such as glucose and sucrose are perceived as sweet, as are other compounds including some simple peptide derivatives, such as aspartame, and even some proteins. 

Figure 32.11. Examples of Tastant Molecules. Tastants fall into five groups sweet, salty, umami, bitter, and sour.

Bottle choice. A widely used method for quantitatively monitoring rodent behavior with regard to taste is the bottle-choice assay. An animal is placed in a cage with two water bottles, one of which contains a potential tastant. After a fixed period of time (24-48 hours), the amount of water remaining in each bottle is measured. Suppose that much less water remains in the bottle with the tastant after 48 hours. Do you suspect the tastant to be sweet or bitter ... 

The sweetness inhibitory activity of plant terpenoids is evaluated by placing 5 mL of 0.5 or 1 mM solution of the compound in the mouth for 2-3 minutes. On expectorating, the mouth is then washed with distilled water. Then, different concentrations of sucrose (0.1-1 mM) are tasted. The maximum concentration of sucrose at which complete supression of sweetness is perceived may then be recorded for each tastant [133]. In practice, antisweet compounds of plant origin have tended to be ranked in terms of sweetness inhibitory potency by comparison with gymnemic acid I (90) [19]. 

In sum, the contrasting evolutionary modes between T1R and T2R gene families suggest the relative constancy in the number and type of sweet and umami tastants encountered by various vertebrates or low binding specificities of TIRs but a large variation in the number and type of bitter compounds detected by different species. 

Spadaccini R, Trabucco F, Saviano G, Picone D, Crescenzi O, Tancredi T, Temussi PA (2003) The mechanism of interaction of sweet proteins with the T1R2-T1R3 receptor evidence from the solution structure of G16A-MNEI. J Mol Biol 328 683-692 Spillane WJ, Kelly DP, Curran PJ, Feeney BG (2006) Structure-taste relationships for disubsti-tuted phenylsulfamate tastants using classification and regression tree (CART) analysis. J Agric Food Chem 54 5996-6004... 

Oquendo P, Hundt E, Lawler J, Seed B (1989) CD36 directly mediates cytoadherence of Plasmodium falciparum parasitized erythrocytes. Cell 58 95-101 Pittman DW, Labban CE, Anderson AA, O Connor HE (2006) Linoleic and oleic acids alter the licking responses to sweet, salt, sour, and bitter tastants in rats. Chem Senses 31 835-843 Pittman D, Crawley ME, Corbin CH, Smith KR (2007) Chorda tympani nerve transection impairs the gustatory detection of free fatty acids in male and female rats. Brain Res 1151 74-83... 

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