Minerals, phytic acid, tannin and rutin in buckwheat seed milling fractions

The composition of common buckwheat (Fagopyrum esculentum Moench) seed mill ing fractions depends upon the relative abundance of various seed tissues i n each. Fancy (light) flour contains mainly central endosperm, while the br an milling fraction has seed coat and some embryo tissues. Phytate, found i n protein bodies of embryo and aleurone cells, is the major storage form of phosphorus, potassium, magnesium and some microelements in seeds. Phytic a cid (35-38 g kg(-1)) and minerals are concentrated in bran, a milling fract ion with high concentrations of phytate-rich tissues. Polyphenolics, includ ing condensed tannins (proanthocyanidins), are also concentrated in bran (1 1-15 g kg(-1)). Rutin is concentrated in the hull of common buckwheat (0.8- 4.4 g kg(-1)). Rutin concentration is low (0.2-0.3 g kg(-1)) in groats of c ommon buckwheat but higher (0.7-0.8 g kg(-1)) in bran containing hull fragm ents. Rutin is 300-fold more concentrated (81 g kg(-1)) in groats of tartar y buckwheat (Fagopyrum tataricum (L) Gaertn) than in groats of common buckw heat. Only small amounts of quercetin were detected. Bran is a concentrated source of phytic acid and tannins, a consideration in consumption of large amounts of buckwheat bran for nutritional or medicinal purposes. (C) 2001 Society of Chemical Industry.