Thursday, January 16, 2014

about Thiamine(Vitamin B1)



Thiamine(Vitamin B1) is a colorless organosulfur compound with a chemical formula C12H17N4OS. Its structure consists of aminopyrimidine and a thiazole ring linked by a methylene bridge. The thiazole is substituted with methyl and hydroxyethyl side chains. Thiamine is soluble in water, methanol, and glycerol and practically insoluble in less polar organic solvents. It is stable at acidic pH, but is unstable in alkaline solutions. Thiamine, which is a N-heterocyclic carbene, can be used in place of cyanide as a catalyst for benzoin condensation.Thiamine is unstable to heat, but stable during frozen storage. It is unstable when exposed to ultraviolet light and gamma irradiation. Thiamine reacts strongly in Maillard-type reactions.Thiamine(Vitamin B1)is found in a wide variety of foods at low concentrations. Yeast, yeast extract, and pork are the most highly concentrated sources of thiamine. In general, cereal grains are the most important dietary sources of thiamine, by virtue of their ubiquity. Of these, whole grains contain more thiamine than refined grains, as thiamine is found mostly in the outer layers of the grain and in the germ (which are removed during the refining process). For example, 100 g of whole-wheat flour contains 0.55 mg of thiamine, while 100 g of white flour contains only 0.06 mg of thiamine. In the US, processed flour must be enriched with thiamine mononitrate (along with niacin, ferrous iron, riboflavin, and folic acid) to replace that lost in processing. In Australia, thiamine, folic acid, and iodised salt are added for the same reason. A whole foods diet is therefore recommended for deficiency.
Some other foods rich in thiamine are oatmeal, flax, and sunflower seeds, brown rice, whole grain rye, asparagus, kale, cauliflower, potatoes, oranges, liver (beef, pork, and chicken), and eggs.
Thiamine hydrochloride (Betaxin) is a (when by itself) white, crystalline hygroscopic food-additive used to add a brothy/meaty flavor to gravies or soups. It is a natural intermediary resulting from a thiamine-HCl reaction, which precedes hydrolysis and phosphorylation, before it is finally employed (in the form of TPP) in a number of enzymatic amino, fatty acid, and carbohydrate reactions.

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