Talk:Tannin/Archive 1

Acacia Tree produces Tannin and starves the Kudu Antelopt
The thorny acacia tree is not the usual food of the Kudu antelope. But because of overcrowding on game farms, the antelope began eating the leaves of this tree. Eventually, the kudu starved to death, even though there were plenty of acacia leaves to eat. Scientists learned that when antelope feed on the acacia, the tree begins to produce a chemical called tannin k. The tannin combines with other chemicals to give the leaves a bad taste. But worse for the antelope, the tannin impairs their ability to digest food, and eventually they starve to death. Scientists found that while tannin is not normally found in high concentrations in acacia leaves, within 15 minutes of leaf damage, the tannin levels in the leaves nearly double. They also found that the trees warn other trees about browsing animals in the area. When a leaf is chewed, it releases a scent that causes neighboring acacia trees to begin to produce tannin! 74.0.72.210 (talk) 13:10, 9 October 2008 (UTC) Form article Creation Moments, Inc

Tea?
A local tea manufacturer (Douwe Egberts) claims on their web sites that tea does NOT contain tannin (looizuur), but related chemicals, flavonoids (lit. from Dutch), which are polyfenols (again, lit. from Dutch). See http://www.pickwick.nl/faq/faq_rechts.asp?VraagID=16 (Dutch).


 * Tannin is a polyphenol, if that helps.

Can anyone confirm or deny this? branko


 * "Tannin" is very broad term, as I understand it. It's used to refer to a whole stack of related organic chemicals, and rather poorly defined. Many of them appear in bark rather than in leaves. I looked this stuff up a while ago, and have forgotten the details, alas. I guess I have a pretty good reason to refresh my memory and update the entry accordingly. :) Tannin


 * I *thought* it should read tannins (plural) too, but wasn't completely sure so I decided not to rock the boat. You'll notice that under tea, I did use only the plural. Mkweise 07:39 Jan 28, 2003 (UTC)


 * It is possible that the Japanese cultivars of sencha green tea plants contain significantly more/less tannin than cultivars of green tea plants grown in China. But it's commonly known that even a cup of sencha tea can taste undesirably tart if it is steeped in water hotter than 160°F longer than 2 minutes. That is why mainland Japanse are very careful about their tea brewing. So isn't that proof that an oversteeped infusion of green tea leaves contains tannins? Well, that is only evidence; not positive proof. Remember that oversteeped tea contains excessive amounts of oxalic acid, which is another tart component. As of this writing no published literature has been found that reports a reasonably complete chemical assay of a standardized green tea infusion. However, here are a few publications that mention green tea's content of tannin. The articles imply a description of the beverage, not the leaf.

http://www.pdrhealth.com/drug_info/nmdrugprofiles/herbaldrugs/101320.shtml http://www.o-cha.com/green-tea-benefits.htm http://www.myfineequine.com/greenteamfe.htm Zymatik


 * With regards to tea's sedative effect, that is not attributed to tannins, but instead to an amino acid alkaloid named theanine.

http://www.itmonline.org/arts/theanine.htm http://www.green-tea-benefit.com/health_benefits.html#difference http://www.o-cha.com/green-tea-benefits.htm http://www.greenteacomplex.com/benefits.html http://www.raysahelian.com/theanine.html Zymatik

Reference showing that green tea contains tannic acid 'Start the Day Right' by Dr. Sarah Brewer, Nov 2004 http://www.healthspan.co.uk/articles/article.aspx?Id=128 Zymatik

Reference showing that tea contains phenolic acid groups including gallic acid (type of tannin) 'The Chemistry of Tea' by Chung S. Yang, Zhi-Yuan Wang http://www.teatalk.com/science/chemistry.htm Zymatik


 * This article states The term "tannins" has been used by many to describe certain tea constituents. In industrial and botanic literatures, tannins are characterized as plant materials that give a blue color with ferric salts and produce leather from hides. Thus, tannins are a group of chemicals usually with large molecular weights and diverse structures. Monomeric flavanols, the major components in green tea, are precursors of condensed tannins. It would be more appropriate to use the term "tea polyphenols" or "tea flavanols" because they are quite distinct from commercial tannins and tannic acid., so this article should be convincing evidence that the term "tannin" is considered incorrect. MatthewEHarbowy 22:43, 3 January 2007 (UTC) Also, gallic acid cannot be a tannin based upon the definition as a molecular weight between 500 and 20000, since it has a molecular weight of 170- see gallic acid MatthewEHarbowy 04:55, 4 January 2007 (UTC)

Green tea contains catechin-based flavonoids, including catechin and epicatechin, and their gallic acid esters. These and other flavonoids make up approximately 30% of the weight of dried tea leaves. Epigallocatechin gallate is the flavonoid in the highest proportion in green tea. Black tea contains more free gallic acid, which is a strong antioxidant; however, the gallic acid esters of catechins, which are found in greater quantity in green tea, are more potent free radical scavengers. Ho CT, Chen Q, Shi H, et al. Antioxidative effect of polyphenol extract prepared from various Chinese teas. Prev Med 1992;21:520-525. Zymatik

Reference showing that prodelphinidin is in green tea leaves Cheng HY, Lin CC, Lin TC. Antiviral properties of prodelphinidin B-2 3'-O-gallate from green tea leaf. Antivir Chem Chemother. 2002 Jul;13(4):223-9. Zymatik


 * if you look at the article, it says the method of isolation from tea is to extract the leaves with acetone. There are a few trace proanthocyanidins in tea, but they are not easily extracted into aqueous soulution and not in significant quantity, so the research cited is not relevant to tea as a food source, unless the person is using nail-polish remover to brew their tea. MatthewEHarbowy 07:49, 4 January 2007 (UTC)

Reference showing that prodelphinidin is present in green tea leaves and that prodelphinidin is a proanthocyanidin type of flavanol (which therefore fits the description of tannin) http://www.acu-cell.com/bio.html Zymatik

EGCG can bined protein and therefor is a tannin. Therefor tea has tannins. Jasoninkid 23:21, 31 May 2007 (UTC)

Tea revisited...
Wikipedian MatthewEHarbowy removed the entire tea reference with the edit summary of tea does not contain tannins- it contains polyphenols. I thought this was previously settled (see discussion above). In short, Tannins are plant polyphenols. The article states this, and numerous (almost all) references on the web support this. Further, the same references make no distinction between the polyphenols in tea and tannins; they all refer to the polyphenols in tea as tannins. I suggest we leave the tea reference in the article unless someone can provide an authorative explanation for why the polyphenols in tea are not really tannins. Gregmg 21:54, 15 December 2006 (UTC)


 * I have worked directly in this field (Balentine DA, Harbowy ME and Graham HN, Tea: the Plant and its Manufacture; Chemistry and Consumption of the Beverage in Caffeine (1998), ed. G Spiller and others) and while the term tannin is a term used to describe the taste of tea, there are only trace quantities of true "tannins" such as procyanidins and hydrolysable tannins such as esters of gallic acid. Tea does contain gallic acid, but it is not typically considered a tannin (and does not precipitate protein- see here) even though many tannins contain esterified gallic acid. I have re-edited to be more conservative in my statement this time, however, the statement "tea does not contain tannins" has been published many times, in both peer reviewed articles and books published like the one I cite above. MatthewEHarbowy 22:38, 3 January 2007 (UTC)


 * More info, from here: Tannins are phenolic compounds that precipitate proteins. They are composed of a very diverse group of oligomers and polymers. There is some confusion about the terminology used to identify or classify a substance as a tannin, In fact, not only tannins bind and precipitate proteins (other phenolics such as pyrogallol and resorcinol also have this property), not all polyphenols precipitate proteins or complex with polysaccharides.


 * One of the most satisfactory definition of tannins was given by Horvath: "Any phenolic compound of sufficiently high molecular weight containing sufficient hydroxyls and other suitable groups (i.e. carboxyls) to form effectively strong complexes with protein and other macromolecules under the particular environmental conditions being studied".


 * Simple phenolics, such as gallic acid, pyrogallol, catechin, and catechol, even though sometimes they are able to precipitate protein (depends on the concentration and the protein), are not polymers and are not commercially useful as tanning agents the way tannic acid is used.


 * Even the article on tannic acid as well as many websites (including one used to justify the argument that tea contains tannins, see this for example) state that tea does not contain tannic acid/does not tan leather. Articles such as this one say "tannic acid", not tannin, even though one could make the argument that tea does contain trace amounts of novel tannins (see Crit. Rev. Plant Sci 16 (5) 433-434 (1997)) and therefore "tannin" is margianlly an ok word to use. When an article uses the word "tannic acid" with tea it's usually a sign that the author doesn't understand the chemistry and is repeating some hearsay that they had heard, which would make it unsuitable for inclusion in Wikipedia. Tannin is a broad word which could mean any polyphenolic- if the two aren't different, then the definition is not useful and tannin should just redirect to polyphenol. If the two are slightly different, then a source better than the ones at my disposal needs to be cited.


 * Tannic redirects here, and tannic is meant to mean tasting like tannin or tannic acid, that is, astringent. It is a useful term in wine, because oak wood is used to ferment the wine and tannin from the wood can leach into the wine giving a tannic character, in addition to tannins coming from the skins or the seeds of the grapes. It's a term to describe organoleptic properties, not chemistry, and that distinction should be made. This is missing from this article, and as soon as I can figure out how to word that nicely, I'll add it. MatthewEHarbowy 03:09, 4 January 2007 (UTC)

By your deffinishion tannins do not need to be polymers, EGCG is quit capable of precipitating protein and is in abundance in tea. Additionally form the Hagerman lab's tannin hand book"For example, consumption of large quantities of tea or other tannin-rich foods..." Jasoninkid 23:56, 31 May 2007 (UTC)

Tea does have tannins, but not "tannic acid" in sensu stricto
I didn't manage to make out if the issue was resolved above. I have always wondered about the common knowledge why tea becomes bitter and darker if over-boiled or stands long especially with the leaves.. so whatever the final chemical explanation be, there has got to be some sort of poorly soluble organic compound similar to tannins that slowly dissolve into the aqueous phase on standing.. Then I found the reference mentioned in the main article (ref 12 at present) and managed to access the original 1979 Science article through jstor. The article is fact a letter. let me quote, since it is a brief letter:

Tea and Tannins; Author(s): Steven R. Wheeler Source: Science, New Series, Vol. 204, No. 4388 (Apr. 6, 1979), pp. 6+8; Published by: American Association for the Advancement of Science; Stable URL: http://www.jstor.org/stable/1747943

Tea and Tannins " Eliot Marshall's statement (News and Comment, 23 Feb., p. 731) that tea con- tains more tannic acid than beer is in er- ror. In fact, tea contains no tannic acid. Tannic acid is a hydrolyzable tannin that yields on hydrolysis gallic acid and glu- cose (1). It is most commonly described as a pentadigalloyl glucoside with the empirical formula of C76H52046 (2). This material has never been reported as a component of tea in any serious work dealing with analysis of the product (3). Careful review of the "Federation of American Sciences [sic] for Experimen- tal Biology" report (4) referred to by Marshall indicates that tannins are wide- ly distributed in many foods, including tea, but that tannic acid is a more nar- rowly defined substance. The authors of this report were careful to distinguish the tannic acid under evaluation as a food additive from the tannins that are ubiqui- tous in plants. Since Marshall's unreferenced state- ment is not unique, this "fact" appears to have entered into the domain of com- mon, albeit erroneous, knowledge. When one considers the existing climate surrounding the safety and use of food additives, it is particularly important that what is or is not contained in a food is accurately reported. STEVEN R. WHEELER Product Safety and Nutrition, Thomas J. Lipton, Inc., Englewood Cliffs, New Jersey 07632 SCIENCE, VOL. 204 "

Note that the author works in a famous tea company that may have some conflict of interest.. Obviously they will want to preventreaders from being discouraged from drinking tea, when they would know tea contains a lot of tannins (probably they didnt need to worry that much, I am myself a tea addict and knowing these facts wont stop me from drinking it)!.. indeed the letter is nitpicking about using a specific jergon.. ''It never states tea doesnt have tannins.. it merely says "tannic acid" ie pentadigalloyl glucoside is a specific hydrolyzable tannin is absent in tea''.. in fact from the previous discussions in this wikipedia page it is amply clear that there are many other gallic acid derivatives in tea which must be one of the reasons for the astringency in tea.. so tea does contains tannins, and when people try to mention it the only mistake they make is call it tannic acid instead of tannin.. an excellent example is: http://chestofbooks.com/health/materia-medica-drugs/Pharmacology-Therapeutics-Prescription-Writing/Theobromine-And-Caffeine-Beverages.html

This site states " The tea should not be boiled, as this hastens the solution of the tannic acid and drives off the flavoring oil. As the tannic acid and coloring-matter dissolve but slowly in water that is not boiling, a fair percentage of these may be left behind if the tea is soon poured off the leaves. If it is allowed to steep too long, the beverage becomes more deeply colored and richer in tannic acid. The tea which stands all day long in the tea-pot and is drunk cold by the inveterate tea-drinker is essentially a solution of tannic acid which would effectively tan hides into leather." The explanation seems pretty logical, and I think replacing tannic acid with tannins would make it fairly correct. Please correct me if I am wrong. --Dr.saptarshi (talk) 00:29, 5 December 2009 (UTC)

Sediment
Is the sediment bit right? I thought the sediment was mostly salts of tartaric acid, as investigated by Louis Pasteur


 * Pretty sure about it. Having trouble finding a good cite of an overview of wine chemistry, but basically the anthocyanins (pigment molecules) and tannins polymerize very slowly and gradually get so big they fall out of solution, leaving a less red and less tannic wine. talks about the process during fermentation, but doesn't really discuss aging. Tartaric acid is what makes sediment gritty, and is also a major contributor. Wnissen 19:30 6 Jun 2003 (UTC)

Article name
If no one objects, I would like to move this page to Tannin, since most of the incoming pages link to there. &mdash; Pekinensis 14:58, 12 May 2005 (UTC)

Done. &mdash; Pekinensis 14:40, 15 May 2005 (UTC)

Weight of tannins
I would direct your attention to the first paragraph where the molecular weight of tannins is provided. Doesn't there seem like there is something a little fishy about those numbers? :P Flying Hamster 17:17, 9 November 2006 (UTC)


 * I'm not a chemist nor do I play one on TV, however, the 500 to 20,000 molecular weight range comes from the Cornell link in the External links section. If this is in error, we should correct the article, add a correct link to replace the Cornell University link, and notify the University their page is in error. Gregmg 21:30, 9 November 2006 (UTC)

No this is right EGCG is ~490Da and other tannins can be quit large. Jasoninkid 23:25, 31 May 2007 (UTC)


 * See Tannic acid for a picture of Gallic acid polymer. --Shjacks45 (talk) 11:52, 9 November 2009 (UTC)

Cranberry
The article mostly claims the "cranberry tannins" are responsible for reducing bacteriuria, pyuria, and cavities. Yet, here, it calls the material for dental health a 'non-dialyzable material (NDM)' and here it refers to phenolics and flavonoids, which are not necessarily tannins. Furthermore, the studies cited tested cranberry juice, which may contain other components that cause the effect. Scientific articles should identify the molecular agent responsible and give its chemical identity as a tannin, otherwise this is speculation. —The preceding unsigned comment was added by MatthewEHarbowy (talk • contribs) 04:51, 4 January 2007 (UTC).

Just a thought
The article seems to have a bias towards producers in certain areas, and seems to give its information about wine-pressing in a biased way. — Preceding unsigned comment added by 65.95.130.211 (talk) 13:07, 27th February 2007 (UTC)

This article completely failsto mention the biological relevence of tannins - namely that of plant defence against herbivores. A new section should be created with links to other plant defences such as protease inhibitors. — Preceding unsigned comment added by 129.234.4.76 (talk) 17:51, 5th May 2007 (UTC)

Just another thought
Hey you above me, if your so smart why don' tyou post it lol..that is the way of the Wiki :) —Preceding unsigned comment added by 71.181.32.97 (talk) 14:56, 26 December 2007 (UTC)

Scope of subject
I came to this page in order to find information regarding interactions between tannins and polysaccharides and i find that, rather startlingly, it is considered to be an article about wine. This is a very narrow view and doesn't cover areas such as leather production, dyeing and the preparation of ink. I have a little knowledge in these areas, but not enough, and there is also very little chemistry in this article. To consider tannins primarily in terms of tea and wine is very limited. I am interested in making some changes, but i'm not a chemist, a textile technologist or a historian, so i'm not going to be able to add much useful information. I just wanted to comment on that in case anyone else knows more or has more expertise and reads this. —Preceding unsigned comment added by Nineteenthly (talk • contribs) 10:42, 7 March 2008 (UTC)

Is this true?
Are cranberries legumes? The article says nothing about that.

Lu na  ke  et  13:18, 18 May 2008 (UTC)


 * Cranberries are not legumes. DuncanHill (talk) 14:31, 18 May 2008 (UTC)
 * The statement implying that cranberries are legumes was introduce in this edit, the only edit ever made by the account which made it. I am going to remove the offending sentence. DuncanHill (talk) 14:44, 18 May 2008 (UTC)

Need article about Shibuol
Need article about the tannin Shibuol. Badagnani (talk) 08:20, 24 May 2008 (UTC)

WikiProject Food and drink Tagging
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Image?
I take pics around and about and thought some folks here would be interested in this one. This is the natural color gradient along the banks of the Suwannee River in Florida. It naturally appears black because of the tannins in the water. --Moni3 (talk) 00:43, 19 May 2009 (UTC)

Interesting observation but probably unconnected. See .91.153.115.15 (talk) 09:00, 21 February 2010 (UTC)

Tannin in heartwood of conifers
"They are also found in the heartwood of conifers and may play a role in inhibiting microbial activity, thus resulting in the natural durability of the wood."

There is a reference to this but I very much doubt the truth in this statement. As far as I know tannin has never been detected in conifer wood. They might have confused stilbene compounds for tannins. The stilbenes are the principal components inhibiting microbial activity.91.153.115.15 (talk) 08:51, 21 February 2010 (UTC)


 * There are plenty of tannins in conifers. Google the two words together. http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VR7-4R70HGF-1&_user=10&_coverDate=02%2F29%2F2008&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1215268195&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=6400b0eb23a1c6acc7a7f1180c665b4c   S  B Harris 10:11, 21 February 2010 (UTC)


 * Partly true. Needles say nothing about the composition in the wood. The following genus do not contain tannin in heartwood; Spruce (Picea), Pine(Pinus), Fir (Abies), (Larch), Douglas-Fir (Pseudotsuga). The only one which definitely does contain plenty of tannin in the heartwood(!) is Sequoia.130.232.214.10 (talk) 12:26, 22 February 2010 (UTC)
 * Addition: The barks and needles of most (possibly all?) conifers do contain tannins.130.232.214.10 (talk) 12:32, 22 February 2010 (UTC)
 * Just checked out the following review; "Tannin signatures in barks, needles, leaves, cones, and wood at the molecular level"(2004) . 0,01% tannin in Spruce and Douglas fir. The problem is a some of the detected tannins are in fact polyphenols unrelated to tannins. The method of using phloroglucinol+HCl is not selective enough but even with this method the result is negative.130.232.214.10 (talk) 13:06, 22 February 2010 (UTC)

I found this inaccurate and it should be replaced with some thing like "Conifer barks contain tannins." The same author (Hemingway) states that conifer wood contain no tannins but does contain other polyphenols that can be used for tanning.

They are also found in the heartwood of conifers and may play a role in inhibiting microbial activity, thus resulting in the natural durability of the wood. 130.232.214.10 (talk) 10:42, 23 February 2010 (UTC)

Contradiction
Don't the following two statements contradict each other?

"If ingested in excessive quantities, tannins inhibit the absorption of minerals such as iron which may, if prolonged, lead to anemia."

"Tannic acid does not affect absorption of other trace minerals such as zinc, copper, and manganese in rats."

Obviously iron absorption is inhibited, but the first sentence says "minerals such as iron", then the second sentence says "no other trace minerals" are affects. Could someone clarify the meaning? Factsontheground (talk) 18:53, 3 March 2010 (UTC)

Medicinal Use??
Er...is anyone paying attention to this medicinal use section? I see that it has been flagged for cleaning but it seems like an egregious deviation from reality, lacks references and unless you want to change the article name to "snake oil", it seems like the whole section should be removed. I makes me lack faith in the whole article's integrity. Seems like it's been in this mode for awhile too.

Ooops. Sorry, posted at the top not the bottom first. Rookie mistake. --Billibill (talk) 02:31, 12 July 2010 (UTC)

I removed the dubious claims that portrayed tannin as some form of miracle drug (i.e it's alleged ability to reverse tumor growth, treat gangrenous tissue, treat an extraordinary amount digestive dysfunctions, etc) as none had citations, they were written poorly, and after extensive searching, I couldn't find any source providing evidence for the claims, let alone a credible source. LiamSP (talk) 20:36, 16 December 2010 (UTC)

What about bananas?
66.108.223.179 (talk) 11:04, 6 June 2011 (UTC)

Nonsense regarding coffee
"Coffee has not been found to contain a low to vanishing amount of tannins.[35]" — Preceding unsigned comment added by 213.21.73.248 (talk) 23:08, 6 March 2013 (UTC)
 * fixed.Jytdog (talk) 00:23, 7 March 2013 (UTC)

Assessment comment
Substituted at 15:54, 1 May 2016 (UTC)

Tannosome
This is too recent, and needs comment from someone who has read the full article, but may a candidate for future addition. RDBrown (talk) 03:12, 16 September 2013 (UTC)