Biochemistry

At the first stage, when hydrogen is eliminated, dehydroascorbic acid (DAC) is formed, which, upon reduction, turns into ascorbic acid. This process occurs in the small intestine, liver and other tissues. However, DAC even less resistant than ascorbic acid, and outside the body even without oxygen irreversibly collapses, becoming oxalic acid, water and CO 2 . Therefore, the formation of DAC leads to a loss of C-vitamin activity in products, if they are not immediately consumed after the formation of oxidized ascorbic acid. Plant products contain the enzyme ascorbate oxidase, which catalyzes the formation of DAC. This enzyme is released in violation of the cells integrity (for example, when chopping cabbage, when chewing). The DAC formed during chewing of plant products is used by the body, since it immediately enters the intestine, where it is restored to ascorbic acid. Ascorbate oxidase is inactive in an acidic environment, therefore, when chopping cabbage, the knife must be lubricated with citric acid or vegetable oil to isolate it from oxygen. When cooking vegetables, they must be immersed in boiling water, which has less oxygen than cold. Vitamin C protects from starch destruction. Ascorbic acid is synthesized from glucose in the body of all animals except guinea pigs, pigs, monkeys and humans. Biological role. Vitamin C takes part in redox processes and in tissue respiration, improves the metabolism of amino acids and carbohydrates, ensures the oxidation of proline to hydroxyproline and the synthesis of collagen - a protein that strengthens the gums, blood vessel walls, bone tissue, which promotes wound healing. Vitamin C has a positive effect on the liver activity, central nervous system, endocrine glands (especially the thyroid gland and adrenal glands), participates in the exchange of iron and cholesterol, normalizes blood formation, improves the metabolism of many vitamins in the body, and increases the body's resistance to infections, intoxications, overheating, hypothermia, oxygen starvation. Ascorbic acid deficiency. Long-term deficiency (3-6 months) of vitamin C in food leads to the development of scurvy. Its main signs are dysfunctions of the central nervous system, joint damage, bleeding gums, loosening and loss of teeth, hemorrhages on the skin, weight loss, decreased body resistance to colds and working capacity. Currently, C-vitamin deficiency practically does not occur. Hypovitaminosis is often observed, especially in winter and early spring, due to the low content of vitamin C in foods. Ascorbic acid is a deficient vitamin. Due to its easy oxidizability, violations in cooking technology can lead to the complete destruction of ascorbic acid in the cooked dish. 260