Tagatose

The solubility and hygroscopicity of tagatose are similar to those of sucrose, but the viscosity of solutions is lower. As a reducing sugar it is less stable in acid conditions and liable to take part in Maillard reactions. 

It has been reported to be synergistic with intense sweeteners such as aspartame and acesulfame K and, when used at low levels (0.2%), improves certain flavour profiles (Eriknauer, 2003 LFRA, 2001). The relative sweetness of tagatose is 0.92. On ingestion, 20% of tagatose is absorbed in the small intestine and the rest is metabolised by the microflora of the colon. Dose-response studies indicate a prebiotic effect at 10 g/day (Eriknauer, 2003). 

Consumption of tagatose does not lead to sharp rises in blood glucose or insulin levels and it is, therefore, suitable for diabetic or low glycaemic index foods and drinks. The calorie level is 1.5 g/day and it is also non-cariogenic (oral bacteria only veiy slowly metabolise tagatose). Despite the fact that it is a sugar, and, therefore, should fall outside the FDA definition of tooth-friendly ingredients, the FDA somewhat controversially approved it for use in tooth-friendly products (FDA, 2003). 

The year 2003 saw a couple of relatively minor launches of tagatose-containing frozen Slurpee type products in the United States. 

JECFA has set a temporary ADI of 125 mg/kg bw (Eriknauer, 2003). This is scheduled for review by JECFA in June 2004 (Eriknauer, 2003). 

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The four kelohexoses are fructose, sorbose, allulose and tagatose. See glucose for example of isomerization between open chain and cyclic structures in a typical hexose molecule. 

Tafel equation Tafel kinetics Tafel slope Taffy process Taft s SV function Tagamet [51481-61-9] d-Tagatose... 

Table sugar, sec Sucrose Tagatose, structure of, 975 Talose. configuration of, 982 Tamiflu, molecular model of, 130 Tamoxifen, synthesis of, 744 Till] DNA polymerase, PCR and, 1117 Tartaric acid, stereoisomers of, 305-306... 

Four DHAP converting aldolases are known, these can synthesize different diastereomers with complementary configurations D-fructose (FruA EC 4.1.2.13) and D-tagatose 1,6-bisphos-phate (TagA, F.C 4.1.2.-), L-fuculose (FucA EC 4.1.2.17) and L-rhamnulose 1-phosphate aldolase (RhuA EC 4.1.2.19)3. The synthetic application of the first (class 1 or 2) and the latter two types (class 2) has been examined. 

Figure 10.15 Enzymatic one-pot synthesis of D-tagatose 1,6-bisphosphate based on the stereoselective TagA m coli.

Tagatose ( ) a-D-Glucose minus a-D-Xylose (-) -o-Glucose minus/3-D-Xylose(-... 

The taste properties of various other ketoses, including 2-pentuloses, 2-hexuloses, and 2-octuloses, have also been studied (see Table XV) to determine the significance of the 2-hydroxyl-2-hydroxymethyl arrangement of 2-ketopyranoses. Some of these, for example, a-D-tagatose (25), -d-g/uco-2-heptulose (26), a-D-mnMno-2-heptulose (27), a-D-fa/o-2-heptulose (28), a-D-a/tro-2-heptulose (29), and D-g/ycero-a-D-g/ co-2-octulose (30),... 

An interesting contrast has been observed between the respective actions of acid and alkali on 3,4-anhydro-l,2-isopropylidene-D-tagatose (XXIVo). The anhydro ring of this compound shows considerable resistance to both mineral acids and alkali. Cleavage by sodium meth-... 

Anhydroderivate der Tagatose- bezw. Sorbose-phenyl-osazone und -phenylosotria-zole, by E. Schreier, G. Stohr, and E. Hardegger, Helv. Chim. Acta, 37 (1954) 35-41. 

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