High-tannin

Rhus coriaria L. is a shrab, which reaches 3M p in high in the wild. Its powdered leaves were used as a tanning agent for its high tannin content [10]. Tannins are found in the leaves, fmit, barks, roots and wood of trees. They can be classified into two groups condensed tannins and hydroly sable tannins [11]. The co-occurrence of both kinds of tannins in the same plant or plant tissue is often observed [12]. The main compounds present mRhus coriaria L. are hydrolysable gallatonnins. 

Mehansho, H., Hagerman, A., Clements, S., etal. (1983). Modulation of proline-rich protein biosynthesis in rat parotid glands by sorghums with high tannin levels. Proceedings ofthe National Academy of Sciences USA 80, 3948-3952. 

There is a useful amount of information relating fecal nitrogen to dietary tannin consumption with, in all nine cases (3,6,10,16,17,18,21,25,27), fecal nitrogen increasing with high-tannin diets. Where authors have expressed a view on the cause of this (16,18, see also 21) they have indicated an increased loss of endogenous rather tlian dietary nitrogen. On this evidence there is no conclusive support for the idea that tannins act to inhibit... 

Despite their very short sequence (7 to 38 amino acid residues for the 12 histatins identified so far), the histidine-rich salivary protein histatins have also been reported to precipitate tannins, eventually more efficiently than proline-rich proteins, especially at neutral pH and high tannin concentration. A detailed NMR analysis of the binding between EGCG and histatin 5, a 24-mer that is very rich in basic His, Lys, and Arg residues ( 60%) and devoid of secondary structure, has revealed noncooperative binding of six to seven flavanol molecules with a dissociation constant of 1 mM (pH 3.0, 25°C). ... 

Feeny (13) attempted to resolve this dilemma by proposing that forest trees may have developed a particularly recalcitrant defense, one which even insects could not overcome in hundreds of generations. His suggestion was that protein-complexing polyphenols, or tannins, could provide such protection. However, there are many insects which feed preferentially on high-tannin content tissues (14, ), and specific adaptations exist which can nullify or reduce the digestion inhibition effects of tannins (16). ... 

Schuster et al. (21) identified cotton plant resistance to the two-spotted spider mite (Tetranycus urtlca Koch) by mass screening seedlings. Later Schuster and Lane (22) were able to show that high tannin lines, particularly TX-1055, showed resistance to this arachnid and the bollworm. 

Mitaru, B.N., Reichert, R.D. and Blair, R. (1983) Improvement of the nutritive value of high tannin sorghums for broiler chickens by high moisture storage (reconstitution). Poultry Science 62, 2065-2072. 

Tests for mycotoxins may be required if harvesting conditions or clinical signs are indicative of possible mycotoxin contamination. Regular tannin analyses are advised in countries that use high-tannin sorghums. 

Many of the Washington red wines tend to have a high tannin content subsequent to fermentation. Total phenol content in new red wines in excess of3000 mg/L, as gallic acid, is not uncommon. Table V lists flavonoid and total phenol content for V. vinifera cultivar Cabernet Sauvignon from 1969 to 1977 produce by one Washington winery. 

Feeny and Bostock (37) have found a relationship between timing of an insect life cycle and plant palatability. Larvae of the winter moth Operophtera brumata feed in spring on young leaves of the deciduous oak Quercus robur. The larvae are apparently intolerant of high tannin content in leaves, and the authors found that tannin content was minimal... 

Continuous operation possible high output few breakdowns high tannin and suspended solids content severe oxidation... 

In the fining of juices with a low tannin content, the silica sol is added before the gelatin, but in the case of juices with a high tannin content the gelatin is added first (in powder form) and then silica gel (30%), with about 5-7 times as much silica sol as gelatin being used. The amount of silica sol used is determined by the amount of gelatin used. 

Used for centuries in Asian traditional practices, Indian gooseberry is a sour, bitter fruit that is often steeped in salt water and turmeric to make a tart tea. The fruit is reputed to have exceptional vitamin C content. One report shows that there is 0.45 gram of vitamin C per 100 grams of pulp (about 75 times more than an orange), but this measurement may be obscured by high tannin density. The fruit contains several other polyphenols as well. 

Chibber, B. A. K., Mertz, E. T., and Axtell, J. D. (1980). In vitro digestibility of high-tannin sorghum at different stages of dehulling. /. Agric. Food Chem. 26,160-161. 

To avoid overfining, it is recommended not to nse gelatin, or to use only doses of 1-3 g/hl in those relatively rare white wines with high tannin contents (100-200 mg/1). Adding tannins (100 mg/1) to white wine before fining could be a solution, but it has the disadvantage (Section 10.7.8) of making the wines harder and... 

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