Tannins
From Wikipedia, the free encyclopediaTannins are
astringent, bitter plant
polyphenols that either bind and
precipitate or shrink
proteins. The astringency from the tannins is what causes the dry and puckery
feeling in the mouth following the consumption of red wine, strong tea, or an unripened fruit. The term tannin refers to the use of tannins in
tanning animal
hides into
leather; however, the term is widely applied to any large
polyphenolic compound containing sufficient
hydroxyls and other suitable groups (such as
carboxyls) to form strong complexes with proteins and other
macromolecules. Tannins have
molecular weights ranging from 500 to over 3,000. Tannins are incompatible with alkalis, gelatin, heavy metals, iron, lime water, metallic salts, strong oxidizing agents and zinc sulfate.
Tannins are distributed all over the
plant kingdom. They are commonly found in both
gymnosperms as well as
angiosperms. In terms of location of the tannins in a plant, they are mainly located in the vacuoles or surface wax of the plants. These sites are where tannins do not interfere with plant metabolism, and it is only after cell breakdown and death that the tannins are active in metabolic effects. Tannins are found in leaf tissues, bud tissues, seed tissues, root tissues and stem tissues. An example of the location of the tannins in the stem tissue is that they are often found in the growth areas of trees, such as the secondary phloem and xylem and the layer between the cortex and epidermis. Tannins may help regulate the growth of these tissues. 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. However, there may be a loss in the bioavailability of tannins in plants due to birds, pests, and other pathogens. The leaching of tannins from the decaying leaves of vegetation adjoining a stream may produce what is known as a
blackwater river.
Tea
The
tea plant (
Camellia sinensis) is an example of a plant said to have a naturally high tannin content. When any type of tea leaf is steeped in hot water it brews a "tart" (
astringent) flavor that is characteristic of tannins. This is due to the
catechins and other
flavonoids. Tea "tannins" are chemically distinct from other types of plant tannins such as tannic acid and tea extracts have been reported to contain no tannic acid. Black tea and peppermint tea are more inhibitory of iron than herb teas like chamomile, vervain, lime flower and pennyroyal.
Wine
Tannins (mainly condensed tannins) are also found in
wine, particularly red wine. Tannins in wine can come from many sources and the tactile properties differ depending on the source. Tannins in
grape skins and
seeds (the latter being especially harsh) tend to be more noticeable in red wines, which are
fermented while in contact with the skins and seeds to extract the colour from the skins. The stems of the grape bunches also contain tannins, and will contribute tannins if the bunches are not de-stemmed before pressing and fermentation. Tannins extracted from grapes are condensed tannins, which are polymers of
proanthocyanidin monomers. Hydrolysable tannins are extracted from the oak wood the wine is aged in. Hydrolysable tannins are more easily oxidised than condensed tannins.
Modern
winemakers take great care to minimize undesirable tannins from seeds by crushing grapes gently when extracting their juice, to avoid crushing the seeds. Pressing the grapes further results in
press wine which is more tannic and might be kept separately. De-stemming is also widely practiced. Wines can also take on tannins if matured in oak or wood
casks with a high tannin content. Tannins play an important role in preventing
oxidation in aging wine and appear to
polymerize and make up a major portion of the sediment in wine.
Recently, a study in wine production and consumption has shown that tannins, in the form of
proanthocyanidins, have a beneficial effect on vascular health. The study showed that tannins suppressed production of the peptide responsible for hardening arteries. To support their findings, the study also points out that wines from the regions of southwest France and Sardinia are particularly rich in proanthocyanidins, and that these regions also produce populations with longer life spans. Effects of tannins on the drinkability and aging potential of wine
Tannins in wine have been described, particularly by novice drinkers, as having the effect of making wine difficult to drink compared to a wine with a lower level of tannins. Tannins can be described as leaving a dry and puckered feeling with a "furriness" in the mouth that can be compared to a stewed tea, which is also very tannic. This effect is particularly profound when drinking tannic wines without the benefit of food.
Many
oenophiles see natural tannins (found particularly in varietals such as
Cabernet Sauvignon and often accentuated by heavy
oak barrel aging) as a sign of potential longevity and
ageability. As tannic wines age, the tannins begin to decompose and the wine mellows and improves with age, with the tannic "backbone" helping the wine survive for as long as 40 years or more. A strongly tannic wine is also well-matched to very fatty food courses, in particular steaks; the tannins help break down the fat[
citation needed], with a salutary impact on both the wine and the steak. In many regions (such as in
Bordeaux), tannic grapes such as Cabernet Sauvignon are blended with lower-tannin grapes such as Merlot or Cabernet Franc, diluting the tannic characteristics. Wines that are vinified to be drunk young typically have lower tannin levels.
we got together with our good friends Jim & Taffina and headed up to the Third Floor Fish Café to kick-back and enjoy some good food and wine. Jim brought a bottle of Matthews Petit Verdot, 2002, from the Ciel Du Cheval Vinyard in the prestigious Red Mountain Appellation of the Columbia Valley. In the glass this is a very dark red wine that is nearly opaque with a black hue. The bouquet is overwhelmingly rich with a flamboyant mix of ripe black fruit intermixed with flowers and some salty minerality. On the palate there is ripe black fruit, crème de cassis, licorice, violets and meat. This is a full throttled, multilayer palate that is both delicious and impressive. It is a full bodied wine with considerable tannins and ample acidity giving it excellent balance, depth and length. After just a few sips of this massive wine, I knew ordering fish would not work so I decided to order Grilled Pork Tenderloin. This is another outstanding wine from Matthews Cellars that we will talk about for years to come.
