Tannins astringent

House sparrow Passer Sorghum unripe seeds Tannins, astringents Tipton eta/., 1970... 

Tannins astringent compoimds which have the ability to tan the skin and to combine with proteins. 

Tannins Astringent compounds in plants that protect the plant from yeasts, being eaten, and bacterial decay. 

The anthocyanins (colored pigments) and tannins (astringent substances) in wines have greater antiviral effects than unfermented grape juice. However, these experiments were conducted in laboratory vessels, rather than in animal or human subjects. 

Tannins Astringent condensed polyphenolic compounds present in some cereals such as bird-resistant sorghums that are antinutritional because they bind digestive enzymes and dietary proteins lowering feed efficiency. Tannins are also antimicrobial and prevent grain from sprouting in the field. Today, tannins are viewed as potent antioxidants and nutraceuticals. The tannins associated with hops bind proteins, decreasing beer haze and, upon oxidation, form colored compounds necessary in beer. 

The natural moisture of the cocoa bean combined with the heat of roasting cause many chemical reactions other than flavor changes. Some of these reactions remove unpleasant volatile acids and astringent compounds, partially break down sugars, modify tannins and other nonvolatile compounds with a reduction in bitterness, and convert proteins to amino acids that react with sugars to form flavor compounds, particularly pyrazines (4). To date, over 300 different compounds, many of them formed during roasting, have been identified in the chocolate flavor (5). 

The family Hamamelidaceae consists of 26 genera and about 100 species of shrubs or tress known to contain tannins and iridoids. The leaves are alternate, simple, and often palmately lobed. The flowers are small and appear in spikes. The fruits are woody, capsular, and scepticidal. In Western medicine, the dried leaves of Hamamelis virginiana (hamamelis, British Pharmaceutical Codex, 1963), yielding not less that 20% of alcohol (45%)-soluble extractive, have been used as astringents for the treatment of hemorrhoids. Hamamelis water (British Pharmaceutical Codex, 1969) made from the stems has been used as a cooling application to sprains and bruises and as a styptic remedy. It is also used in cosmetics and as active ingredient of eye lotions. 

B Astringent (tannin-containing) plant parts tend not to be eaten. 

Very little information exists on the phenolic protein-conplexing resins, except for that on creosote bush and sane arctic plants. In contrast to condensed tannins and hydrolyzable tannins, these are typically ether-soluble compounds this may allow their entry into the body across cell membranes, and thios give them the potential for action outside the gut lumen. Reports for animals consuming seaweed indicate that astringent protein-precipitating substances (presumably phlorotannins), are potentially important in marine plant-herbivore interactions. 

The astringency of wine tannin fractions appears to be correlated to the content of flavanol units released after thiolysis regardless of their environment in the original mol-ecules. Anthocyanins contributed neither bitterness nor astringency. Whether incorporation of anthocyanin moieties in tannin-derived structures affects their interactions with proteins and taste properties remains to be investigated. 

Tanaka, T. et al., Chemical evidence for the de-astringency (insolubilisation of tannins) of persimmon fruit. J. Chem. Soc. Perkin Trans. /3013, 1994. 

Bate-Smith, E.C., Haemanalysis of tannins the concept of relative astringency. Phytochemistry 12, 907, 1973. 

Naish, M., Clifford, M.N., and Birch, G.G., Sensory astringency of 5-O-caffeoylquinic acid, tannic acid and grape seed tannin by a time-intensity procedure. J. Sci. Food Agric. 61, 57, 1993. 

Vidal, S. et al., Effect of tannin composition and wine carbohydrates on astringency and bitterness. In 5th Pangborn Sensory Science Symposium, Boston, 2003. 

Matsuo, T. and Itoo, S., A model experiment for de-astringency of persimmon fruit with high carbon dioxide treatment in vitro gelation of kaki-tannin by reacting with acetaldehyde. Agric. Biol Chem. 46, 683, 1982. 

Taira, S., Ono, M., and Matsumoto, N., Reduction of persimmon astringency by complex formation between pectin and tannins. Postharvest Biol Technol 12, 265, 1998. 

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