Ascorbic acid antioxidant properties

Industrial uses of L-ascorbic acid relate to its antioxidant and reducing properties. It is used as an antioxidant in the commercial preparation of beer, fmit juices, cereals, and caimed and frozen foods, etc. 

In apphcations where vitamin C activity is unimportant, often D-erythorbic acid (D-araboascorbic acid) can also be used, providing the same antioxidant and reducing properties as L-ascorbic acid. 

An isomer (molecule with the same number and type of atoms but in a different formation) of ascorbic acid called erythorbic acid is often used as a less expensive antioxidant than ascorbic acid. It has little or no effect as a vitamin, but it has the same antioxidant properties. 

Cort, W.M. (1982). Antioxidant properties of ascorbic acid in foods. In Ascorbic Acid Chemisty, Metabolism and Uses (eds. P.A. Seib and B.M. Tolbert) Advanced Chemical Series No. 200, p. 531. American Chemical Society, Washington, DC. 

Yen YH, Shih CH and Chang CH. 2008. Effect of adding ascorbic acid and glucose on the antioxidative properties during storage of dried carrot. Food Chem 107(1) 265—272. 

Vitamin C (ascorbic acid) is probably the most known vitamin in the world. Its legendary fame is based on the two events its exceptionally important role in the treatment of scurvy and Linus Pauling s proposal to use the huge doses of ascorbic acid for the prevention of common cold. The latter proposal, based obviously on the antioxidant properties of ascorbic acid, generated numerous studies and was frequently disputed, but many people (me including) successfully apply ascorbic acid for the treatment of starting stage of common cold. 

In vitro antioxidant and prooxidant properties of ascorbic acid have been clearly demonstrated. It is understandable that the competition between antioxidant and prooxidant activities of ascorbic acid depends on the rates of Reactions (11) and (12). 

The absence of substituents with free radical scavenging properties in most of the (3-blockers makes doubtful their efficacy as powerful antioxidants. Arouma et al. [293] tested the antioxidative properties of several 3-blockers in reactions with superoxide, hydroxyl radicals, hydrogen peroxide, and hypochlorous acid. It was demonstrated that most of the compounds tested were inactive in these experiments. Nonetheless, propranolol, verapamil, and flunarizine effectively inhibited iron ascorbate-stimulated microsomal lipid peroxidation and all drugs (excluding flunarizine) were effective scavengers of hydroxyl radicals. Contrary to Janero et al. [292], these authors did not find the inhibition of xanthine oxidase by propranolol. It was concluded that 3-blockers are not the effective in vivo antioxidants. 

Ascorbic acid (Vitamin C H A) has been widely used in pharmaceutical, chemical, cosmetic and food industry because of its bioactive and antioxidant properties [1]. Cu (II) ion is important nutrients found in many food and pharmaceutical products. Traces of transition metal ions like as Cu(II) ion also acts as catalyst in the oxidation... 

Many people, inclnding myself, take substantial amonnts of ascorbic acid, since it is cheap and qnite safe below the UL level, in the hope, nnsnpported by mnch scientihc evidence, that its antioxidant properties will contribnte to health and longevity. 

Acetamido-2-deoxy-D-glucose is a component of a mucopolysaccharide hyaluronic acid. It has been demonstrated, by PET imaging with the corresponding F labeled compound, that this glucose derivative is incorporated into the connective tissue at the interface of a tumor and healthy tissue. Thus, it can be used as a tumor label. 6-[ F]-6-Deoxy-L-ascorbic acid also deserves attention, as it maintains the antioxidant properties of ascorbic acid. Thus, it can be useful to smdy the biochemical... 

The use of acidulants is an essential part of beverage formulation, with the acid component usually third in order of concentration. Acidulants performs a variety of functions in addition to their primary thirst-quenching properties, which are the result of stimulation of the flow of saliva in the mouth. Because it reduces pH, an acidulant can act as a mild preservative and in some respects as a flavour enhancer, depending on the other components present. In addition, by functioning as a synergist to antioxidants such as butylated hydroxy anisole (BHA), butylated hydroxy toluene (BHT) and ascorbic acid, acidulants can indirectly prevent discolouration and ranciditye. 

Ascorbic acid, known more familiarly as vitamin C, is used not only as on acidulant but also as a stabiliser within the soft drinks system, and its antioxidant properties serve to improve the shelf-fife stability of flavour components. Many of the ingredients used in flavourings are susceptible to oxidation, particularly aldehydes, ketones and keto-esters. Ascorbic acid shields these from attack by being preferentially oxidised and lost, leaving the flavour component unaffected. 

Although many in vitro studies on the antioxidative property of food constituents have been reported, little is known about the biological functions of dietary antioxidants in vivo, except for several well-known antioxidants such as tocopherols, (i-carotene, and ascorbic acid. Because the bioavailability of food constituents is limited by their digestibility and metabolic fate, an oral administration trial of a dietary antioxidant is favored to evaluate its biological function. 

In connection with the antioxidant properties of L-ascorbic acid and its stability, many kinetic and mechanistic studies have been performed. For instance, it has been shown a role as a radical scavenger in the autooxidation of methyl linoleate, and its synergistic effect when used with vitamin E.362 The photooxidation,363 superoxide-mediated oxidations,364 reactions with radicals,365 and the influence of other agents, including ultrasound and y-rays,366 have been reported. 

Partial silylation of the highly disperse silica surface enhances the adsorption of vitamin E from ethanol solution, and provides the ability to obtain water-soluble nanocomposites containing vitamin E. Immobilization of vitamin C on the silica surface prevents its oxidation. Its interaction with the adsorbent surface leads to a decrease in proton-donor ability of the OH-groups involved in the oxidation of ascorbic acid. Elydrophobized silica nanocomposites are characterized by a prolonged desorption of immobilized vitamins. It has been shown that vitamin C does not lose its antioxidant properties after desorption. 

Studies on the antioxidant properties of anthocyanins on human low-density lipoprotein (LDL) and lecithin liposome systems in vitro showed that the inhibition of oxidation increased dose-dependently with antioxidant concentration. The oxidation was catalyzed by copper in the LDL system and the effects of the anthocyanins were explained by several antioxidant mechanisms including hydrogen donation, metal chelation and protein binding [33]. Anthocyanins also prevented the oxidation of ascorbic acid (vitamin C), through chelate formation with the metal ions, and finally by the formation of an ascorbic (copigment)-metal-anthocyanin complex [49]. 

The concentration of an antioxidant in a food fat is important for reasons of cost, safety, sensory properties, and functionality, and generally they are allowed in food products at 0.01 percent level. Substances such as citric acid, isopropyl acid, phosphoric acid, ascorbic acid, and tartaric acid are sometimes added as S5mergists to enhance the effectiveness of antioxidants. 

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