Significance of the Condensed Tannins

Bate-Smith and Swain (19) were the first to recognize the widespread occurrence of proanthocyanidins and related phenolics in foods and to appreciate their possi- 

The proanthocyanidins of Sorghum spp. and Hordeum spp. have been studied in some detail. In particular. Sorghum species have been shown to contain a polymer based largely on epicatechin-4 units with a catechin terminal unit (26, 74), but some cultivars also contain epigallocatechin-4 units (26). Certain other cultivars contain significant concentrations of a novel proluteolinidin based on 5-O-glucosylated flavan units (73). The proanthocyanidins of Hordeum spp. will be considered later. 

They also point out that tannin content may be lowered by selective breeding. This trend may be observed for most domesticated food crops where evidence that 

The tannins of fodder legumes have also been studied in some detail by Foo et al. (63), who determined the structures of the proanthocyanidins from 13 species in the genera Coronilla, Lotus, Onobrychis, Robinia, Trifolium, and Vida. All were mixed procyanidin-prodelphinidin polymers except Trifolium repens (a prodelphinidin) and Vida (a procyanidin). 

In contrast to the findings reported earlier, there is now clear evidence that tannins, particularly proanthocyanidins, are a beneficial and perhaps essential feature of the bovine diet. They have been shown to be a powerful anti-bloat factor and to improve the efficiency of leaf-to-meat protein conversion in cows both effects operate through pre-digestion complex formation in the first gut (132). 

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Laks, P.E. 1989. Chemistry of the condensed tannin B-ring. In Chemistry and Significance of Condensed Tannins (R.W. Hemingway and J.J. Karchesy, eds.) pp. 249-263. Plenum Press, New York. 

Polyphenols are significant constituents in the IDF of the samples analyzed, accounting for 1.4% to 4.7% (average, 2.5%). PPs are therefore an important constituent of DF in fruits and vegetables they are mainly condensed tannins (proanthocyanidins) and hydrolyzable tannins. 

Hermingway RW (1989) Reactions at the interflavanoid bond of proanthocyanidins. In Hermingway RW, Karchesy JJ (eds) Chemistry and significance of condensed tannins. Plenum Press, New York, NY... 

Stafford HA. 1989. The cnzymology of proanthocyanidin biosynthesis. In Hemingway RW, Karchesy JJ, Eds. Chemistry and Significance of Condensed Tannins. New York Plenum Press, pp. 345-368. 

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