Tannins description

Some of the early descriptions of the effect of MOX on red wine included an interesting cycling effect where certain organoleptic aspects of wine quality appear to get worse before the continued application of MOX leads to the desired improvements (Dykes and Kilmartin, 2007 Parish et al., 2000 Vinovation, 2009). In the first "structuring" phase (for several days to weeks), the wine tannins are said to become more aggressive and the varietal aromas decrease, after which the tannins soften and... 

A statement of the problems relative to red wine color should include a description of the compounds involved which belong to plant phenolics. These compounds include the anthocyanins of grapes and the tannins which are important in the color of wines, especially old wines. 

Note "Tanning Chemicals, Dye, Paint, Putty Inks" refers to "tanning or dyeing extracts tannins and their derivatives dyes, pigments and other coloring matter paints and varnishes putty and other mastics inks," HS (Harmonized Commodity Description and Coding System) Code 32. 

A true tannin is operationally defined as a substance that will precipitate proteins from aqueous solutions. The pentagallate will not fit this description but a nonagallate will. 

After a brief historical introduction and the distinction between hydrolysable and condensed tannins, a description of their chemistry and a short historical review on their use in leather tanning, the more recent developments in tannins for adhesives with and without the use of any aldehyde-yielding compounds, even without the use of any hardeners, are described. Examples of the use of tannins for other industrial, nonleather, applications are reported. In particular, this chapter focuses briefly on their new intended use in the medical and pharmaceutical fields. New data on their antiviral effectiveness against a great number of different viruses compared to their higher, lower or absent cytotoxicity are also presented. 

So far as is known, the catechins are never glycosylated, and the leuco-anthocyanins seem also to occur, as a rule, uncombined with sugars. Johnson et al. (1951) report, however, that the main component of peach tannin (which from the description they give resembles in every respect a leuco-anthocyanin) is associated with carbohydrate, since glucose appears on hydrolysis with HCl. 

The taste and mouthfeel properties of three different types of tannin-like polyphenolic compounds, representative of some of the tannin-like polyphenolic compounds found in red wines, were determined using descriptive sensory analysis [50]. Ethyl-bridged fiavan-3-ols were produced by reaction of (+)-catechin with acetaldehyde under acidic conditions. Red-colored tannin-like polyphenolic compounds from wine and from wine pomace were isolated by multilayer coil countercurrent chromatography (MLCCC). Mouthfeel attributes and bitterness of the fractions dissolved in a model wine (MW) medium were rated while the fractions were held in the mouth and after expectoration. The sensory properties... 

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