Vitamin of ultraviolet light present in sunlight. Humans can produce some vitamins from precursors they consume: for example, vitamin A is synthesized from beta carotene; and niacin is synthesized from the amino acid tryptophan. The Food Fortification Initiative lists countries which have mandatory fortification programs for vitamins folic acid, niacin, vitamin A and vitamins B1, B2 and B12. Vitamins are classified as either water-soluble or fat-soluble. In humans there are 13 vitamins: 4 fat-soluble (A, D, E, and K) and 9 water-soluble (8 B vitamins and vitamin C). Water-soluble vitamins dissolve easily in water and, in general, are readily excreted from
Chemistry of ascorbic acid acid. American and Chinese researchers are competing to engineer a mutant that can carry out a one-pot fermentation directly from glucose to 2-KGA, bypassing both the need for a second fermentation and the need to reduce glucose to sorbitol. There exists a -ascorbic acid, which does not occur in nature but can be synthesized artificially. To be specific, -ascorbate is known to participate in many specific enzyme reactions that require the correct enantiomer (-ascorbate and not -ascorbate). -Ascorbic acid has a specific rotation of [α] = +23°. The traditional way to analyze the ascorbic acid content is the process of