Tannins structure

The information in Table I reveals differences between sane of the inportant types of tannin. Tannic acid is unique for its occurrence in all reports of diet-induced gut lesion and gastrointestinal damage (vertebrate or invertebrate) it is also the only tannin for which metabolism and excretion are reported. By contrast condensed tannins are not thought to leave the gut lumen. Thus,in comparison with tannic acid condensed tannins would not be espected to drain 1-carbon metalx>lism, notably methionine resources. However, the reports by Elkin (] ) and Ford ( ) of corrective methionine treatment for chicks fed a condensed-tannin diet, indicate that sane condensed tannin may enter the body or that methionine can react with tannin in the gut, so perhaps the position is once again not clear cut on tannin structure and its impact on methionine levels. The conclusion can, however, be made that despite its hydrolyzability, tannic acid does exert an allelochemical effect which is not abolished by hydrolysis. 

Bavage, A.D. et al.. Expression of an Antirrhinum dihydroflavonol reductase gene results in changes in condensed tannin structure and accumulation in root cultures of Lotus corniculatus (bird s foot trefoil). Plant Mol Biol, 35, 443, 1997. 

Tangerine oil. see Citrus Orange Tannins, structure of. see also Polyphenolics Taste, see Flavor analysis TBA. see 2-Thiobarbituric acid TBARS. see 2-Thiobarbituric acid reactive substances... 

In fact, it seems that both type of interactions are present, strengthening each other, depending on the protein and tannin structure and medium conditions [17, 26, 27]. 

The chemical basis for these apparent changes is unknown but is likely to involve yeast mediated changes to tannin structure. 

Addition of catechin or epicatechin onto vescalagin yield complex tannin structures called acutissimin and epiacutissimin (Quideau et al. 2003) that have been isolated earlier from Quercus acutissirm. It is worth noting that the isomer of vescalagin (i.e. castalagin) fails to undergo this reaction. 

Poncet-Legrand, C., Gautier, C., Cheynier, V, Imberty, A. (2007). Interactions between flavan-3-ols and poly(L-prohne) studied by isothermal titration calorimetry Effect of the tannin structure./. Agric. Food Chem., 55, 9235-9240. 

D.3.3 Tannin Structures and Their Influence in Wine Astringency.554... 

Mateus, N., Carvalho, E., Luis, C., de Freitas, V. A. P. (2004a). Influence of the tannin structure towards the disruption effect of carbohydrates on protein-tannin aggregates. Anal Chim. Acta, 513, 135-140. 

Table 10.1.1. Typical compounds identified in the pyrolysate depending on R and R in the tannin structure.

The presence of ethanal in a mixture of procyanidins and anthocyanins also results in orange-colored complex pyranoanthocyanin-tannin structures (Figure 6.29) (where R = procyanidin dimer) (Francia-Aricha et al.,... 

The phenol composition of wine is considerably modified by barrel aging, thanks to controlled oxidation. Color is intensified due to reactions between tannins and anthocyanins, as well as others involving ethanal. The free anthocyanin concentration decreases and the tannin structure evolves, as does its reactivity to gelatin. After ten months of barrel aging, wines have better color than those aged in the vat (Table 13.8 Section... 

Betts, M.J., B.R. Brown, PE. Brown, and W.T. Pike Degradation of Condensed Tannins Structure of the Tannin from Common Heather. Chem. Commun., 1110 (1967). 

The following three-unit fragment illustrates two typical tannin structures ... 

Plant polyphenols, which have the ability to precipitate protein, collectively, are called tannins. These compounds have been used for millenia to convert raw animal hides into leather. In this process, tannin molecules cross-link the protein and make it more resistant to bacterial and fungal attack. Molecules in the molecular weight range of 500-2000 (3000) are most effective, but the ability to bind effectively varies with different tannin structures. Today, however, many substances considered to be tannins by virtue of their structure and bios5mthetic origin have limited, if any, ability to make leather (Hagerman and Butler, 1981). 

Margalit (2004) proposed that optimal harvest sugar concentrations be 19°Brix to 23°Brix (white cultivars) and 21°Brix to 24°Brix (red cultivars). However, winemakers in the United States will frequently require more mature fruit optimal to maximize flavor development associated with physiological maturity (i.e., desired tannin structure). In the case of late harvest or Botrytis-infected fruit, the concentration of fermentable sugars can be much higher, ranging upward to 40% w/w. 

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