Thaumatin

E957 Talin taumatin thalin thaumatine thaumatins thau-matins protein. 

Thaumatin is stable in aqueous solutions at pH 2-8. It is also heat-stable at less than pH 5.5 (e.g., during baking, canning, pasteurizing, or UHT processes). 

Thaumatin is a mixture of five thaumatin proteins thaumatins I, II, III, and a and b where thaumatins I and II predominate. Thaumatins I and II consist of almost identical sequences of amino acids. There are no unusual side-chains or peptide linkages, and there are no end-group substitutions. 

Thaumatin occurs as a pale-brown colored, odorless, hygroscopic powder with an intensely sweet taste. 

Thaumatin is a naturally occurring intense sweetener isolated from the fruit of the African plant Thaumatococcus daniellii (Benth). Commercially, thaumatin is produced by aqueous extraction under reduced pH conditions followed by other physical processes such as reverse osmosis. 

---

Thaumatin. Thaumatin [53850-34-3] is a mixture of proteins extracted from the fmit of a West African plant, Thaumatococcus daniellii (Beimett) Benth. Work at Unilever showed that the aqueous extract contains two principal proteins thaumatin I and thaumatin II. Thaumatin I, mol wt 22,209, contains 207 amino acids in a single chain that is cross-linked with eight disulfide bridges. Thaumatin II has the same number of amino acids, but there are five sequence differences. Production of thaumatins via genetic engineering technology has been reported (99). 

Thaumatin (trade name Talin) is a very potent sweetener (ca 2000X, 10% sucrose solution sweetness equivalence). However, its potency is overshadowed by inferior taste quaUties. The onset of sweetness is very slow, and after reaching the maximum sweetness, a very long-lingering sweetness combined with an unpleasant aftertaste follows. Primarily owing to this poor taste quaUty, thaumatin is not considered a practically useflil sweetener. It is, however, used as a flavor enhancer, especially in products such as chewing gum. Thaumatin and thaumatin B-recombinant were affirmed GRAS flavors (EEMA no. 3732 and 3814, respectively). They are not approved as sweeteners in the United States. 

As a protein, thaumatin is remarkably water-soluble (up to 60%) and is stable to heat at low pH. It has been reported that a thaumatin solution at pH less than 5.5 can be heated at 100°C for several hours without loss of sweetness. Comprehensive reviews on thaumatin as sweetener are available (100,101). 

Singh, N.K., Bracket, C.A.S., Hasegawa, P.M., Handa, A.K., Bruckel, S., Hermondson, M.A., Pfankoch, E., Regnier, F.E. Bressan, R.A. (1987o). Characterisation of osmotin. A Thaumatin-like protein associated with osmotic adaptation in plant cells. Plant Physiology, 85, 528-36. 

That the initial event of taste stimulation takes place on the cell surface of the taste receptor is now universally accepted. In addition, accumulated evidence strongly suggests that taste-bud stimulation is extracellular in nature. For example, (1) the sweet-taste response is both rapid and reversible, (2) the intensely sweet proteins monellin" and thaumatin could not possibly penetrate the cell, because of their size, and (3) miraculin, the taste-modifying glycoprotein, having a molecular weight of 44,000 would also be too large to penetrate the taste cell. ... 

Molar ratios of each substance required to give equivalent displacement of l-labeled thaumatin from antibody in coated tubes. 

In a study of the three-dimensional structure of thaumatin, it was reported that, not only do antibodies raised against thaumatin cross-react with monellin,but antibodies raised against monellin also cross-react with thaumatin, suggesting that there is some structural similarity between portions of the two sweet-protein molecules. Earlier studies " had shown that there is a limited homology in the amino acid sequence in the two proteins. Five tripeptides in monellin have their counterparts in thaumatin. 

It is interesting that the stimulus compounds used in the study differ widely in their molecular structures, and yet they all interact with antibodies to thaumatin. It is, therefore, probable that a single receptor-structure responds to all sweet stimuli,there being a variation in the relative effectiveness of sweet stimuli across individual nerve-fibers, and the characteristics of all receptor sites do not appear to be identical. Earlier elec-trophysiological studies of single primary, afferent taste-neurons uniformly agreed that individual fibers very often have multiple sensitivities, and that individual, gustatory receptors are part of the receptive field of more than one afferent fiber. " We have yet to learn how these interact, and the nature of their excitatory, or possible inhibitory, relations, or both. 

Birch and coworkers studied the time-intensity interrelationships for the sweetness of sucrose and thaumatin, and proposed three thematically different processes (see Fig. 47). In mechanism (1), the sweet stimuli approach the ion-channel, triggering site on the taste-cell membrane, where they bind, open the ion-channel (ionophore), and cause a flow of sodium and potassium ions into, or out of, the cell. Such a mechanism would correspond to a single molecular event, and would thus account for both time and intensity of response, the intensity of response being dependent on the ion flux achieved while the stimulus molecule binds to the ionophore. 

Thallium metal, 24 627—629 Thallium nitrates, 24 633 Thallium organometallics, 24 633—635 Thallium oxides, 24 632—633 Thallium poisonings, 24 637, 638-639 Thallium stress test, 24 629 Thallium sulfates, 24 628, 633 Thaumatin, 72 43, 24 241-242 Thaumatin II, 24 242 Theaspiranes, 24 572 Thebaine, 2 89 Thenardite, 22 863, 5 785t Thenoyltrifluoroacetone molecular formula, 5 712t Theobroma cacao, 6 350 Theobromine, 2 105-106... 

Sweeteners can be roughly divided into two groups bulk and intense sweeteners. Prodolliet (1996) and Gloria (2000) reviewed thoroughly the analysis and properties of intense sweeteners acesulfame-K, alitame, cyclamate, aspartame, glycyrrhizin, neohesperidin DC, saccharin, stevioside, sucralose and thaumatin. They are generally used in low calorie products such as diet... 

Other than the sweeteners discussed so far thaumatin is a polypeptide consisting of amino acids commonly found in food proteins. It is quickly and completely digested like proteins and did, after demonstration of its metabolic characteristics, only require a rather limited set of safety data. In contrast to the other intense sweeteners the ADI of thaumatin is not specified , as for substances of similar composition.27 It is approved in many countries but, owing to its flavour enhancing properties, is often used as a flavour enhancer rather than a sweetener. 

Acesulfame K Aspartame Cyclamate Neohesperidin DC Saccharin Thaumatin... 

Intense and bulk sweeteners are endorsed by international agencies and approved in a large number of countries. Acesulfame K, aspartame and saccharin are available as sweeteners in the EU and Europe while sucralose is approved in the USA and due for approval in Europe and cyclamate, neohesperidin dihydrochalcone and thaumatin are available in Europe. As bulk sweeteners isomalt, lactitol, maltitol, mannitol, sorbitol and xylitol are commonly available. 

Thaumatin-like proteins provide a sweet taste in food. They may display antifungal activity and are treated as potential allergens. These proteins are found in strawberries, apples, bell peppers, and cherries (Scheurer et al., 1999 Aalberse et al., 2001). 

The design of safe sweeteners is very important for people who are afiected by diabetes, hyperlipemia, caries and other diseases that are linked to sugar consumption. Sweet proteins, which are found in several tropical plants, are many times (100-100,000) sweeter than sucrose on a molar basis. Only a few sweet proteins are known miraculin, monellin, thaumatin, curculin, mabinlin. 

Brazzein is another small sweet-tasting protein whose solution structure has been recently solved by NMR. Brazzein tastes 2000 times sweeter than sucrose on a weight basis and is exceptionally thermostable. As indicated by NMR, the structure of this 54 residue, single-chain polypeptide does not change between 32 and 82 °C and retains its sweetness after incubation at 98 °C for two hours.Brazzein contains one a-helix and three strands of antiparallel jd-sheet stabilized by four intramolecular disulphide bonds. It has been proposed that the disulphide bonds could be responsible for the thermostability of brazzein by forming a compact structure at the tertiary level.The structure of brazzein does not resemble that of the other two sweet proteins with known structures, monellin and thaumatin, whereas sequence alignment and structural prediction indicate that brazzein shares the fold of a newly identified family of serine proteinase inhibitors. 

There are seven known sweet and taste-modifying proteins, namely (1) monellin and (2) thaumatin (3) mabinlin. and (4) curculin (5) pentadin, (6) brazzein and (7) miraculin.The properties and characteristics of these proteins are illustrated in Table 2. There are several recent reviews relating to sweet proteins. Apart from curculin and... 

Table 2. Comparison of Thaumatin, Monellin, Mabinlin, Pentadin, Brazzein, Curculin and Miraculin... 

Thaumatin Monellin Mabinlin Pentadin Brazzein Curculin Miraculin... 

Source Adapted from Kurihara. " At least five different forms of thaumatin and four different forms of mabinlin have been identified. A chromatographic fraction containing a 12 kDa protein was sweet. This same fraction, when subjected to electrophoresis under nonreducing conditions showed bands in the region between 22 kDa and 41 kDa, su esting the presence of subunits. 

---