Erythorbic acid

Araboascorbic acid d-araboascorbic acid D-2,3-didehydro-eryt ro-hexono-l,4-lactone E315 erycorbin d-erythorbic acid D-eryt ro-hex-2-enoic acid D-eryt ro-3-ketohexonic acid lactone glucosaccharonic acid D-isoascorbic acid isovitamin C y-lactone saccharosonic acid. 

Erythorbic acid is a stereoisomer of L-ascorbic acid, and is used as an antioxidant in foods and oral pharmaceutical formulations. It has approximately 5% of the vitamin C activity of L-ascorbic acid. 

Erythorbic acid occurs as a white or slightly yellow-colored crystals or powder. It gradually darkens in color upon exposure to light. 

Melting point 164-171°C with decomposition at 184°C Solubility see Table I. 

Erythorbic acid should be stored in an airtight container, protected from light, in a cool, dry place. 

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Another group of compounds called oxygen scavengers retard oxidation by reducing the available molecular oxygen. Products in this group are water soluble and include erythorbic acid [89-65-6] C HgO, and its salt sodium erythorbate [6381-77-7] C HgO Na, ascorbyl pahnitate [137-66-6] 22 38 7 ascorbic acid [50-81-7] C HgO, glucose oxidase [9001-37-0] and sulfites (23). 

As a result of having two chiral centers, four stereoisomers of ascorbic acid are possible (Table 1) (Fig. 2). Besides L-ascorbic acid (Activity = 1), only D-araboascorbic acid (erythorbic acid (9)) shows vitamin C activity (Activity = 0.025-0.05). The L-ascorbic acid stmcture (1) in solution and the soHd state are almost identical. Ascorbic acid crystallizes in the space group P2 with four molecules in the unit cell. The crystal data are summarized in Table 2. 

D-Araboascorbic acid (erythorbic acid) (10) L-Araboascorbic acid... 

Chromatographic methods, notably hplc, are available for the simultaneous deterrnination of ascorbic acid as weU as dehydroascorbic acid. Some of these methods result in the separation of ascorbic acid from its isomers, eg, erythorbic acid and oxidation products such as diketogulonic acid. Detection has been by fluorescence, uv absorption, or electrochemical methods (83—85). Polarographic methods have been used because of their accuracy and their ease of operation. Ion exclusion (86) and ion suppression (87) chromatography methods have recently been reported. Other methods for ascorbic acid deterrnination include enzymatic, spectroscopic, paper, thin layer, and gas chromatographic methods. ExceUent reviews of these methods have been pubHshed (73,88,89). 

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. 

NOTE Where MU requirements exceed 5 to 10% ofLTHW system volume per month, or 5% of the steam output ofLP steam boilers, a separate oxygen scavenger is required. This usually is tannin, diethylhydroxylamine (DEHA), or erythorbic acid (isoascorbic acid). 

NOTE Cupric copper (Cu2+) is a catalyst for the hydrazine-oxygen reaction, as well as a catalyst for sulfite, DEHA, erythorbic acid, and hydroquinone. Cuprous copper (Cu+) acts as a complexing agent in the desirable formation of protective, pasivated copper oxide films. 

Erythorbic acid is supplied as white granular crystals or a powder of sodium erythorbate monohydrate C6H706Na H20, having a fivesided ring and a very reactive ene-diol structure (-COH=COH—) it is a sterioisomer of sodium ascorbate, with a MW of 216.1. It is approved under 21CFR 182.304, GRAS. 

Erythorbic acid is available as a 98+% Food Chemical Codex product (as per Pfizer sodium erythorbate FCC, although as Pfizer is now a pharmaceuticals company, much of the world s erythorbate is now supplied from China and other Asian countries) and in many diluted or blended forms, such as Nalco Sur-Gard . The ONDEO Nalco material is typical of products used within the industry, being based on erythorbic acid buffered with amine. A 1% solution of the product has a pH level of 6.3. 

Erythorbic acid and sodium erythorbate are very safe products, widely used in the food industry as antioxidants and alternatives to vitamin C. In the water treatment industry, they are strong reducing agents that reduce metal oxides and hydroxides to their more soluble ferrous forms and promote the passivation of boiler waterside surfaces (magnetite formation). 

Formulated products tend to use a 10 to 20% neutralized erythorbate, buffered to pH of 5 to 6 with ammonia, morpholine, cyclohexy-lamine, diethanolamine (DEA), or triethanolamine (TEA) to reduce the acidity of erythorbic acid. Similarly, amines are used with sodium erythorbate to improve the reaction rate. 

One excellent UV protector for foods is PABA, a B vitamin. Likewise, many of the same antioxidants we ingest as health supplements—such as vitamin C and a similar chemical, erythorbic acid vitamin E and lecithin, a source of the important nutrients choline and inositol—occur naturally in food. 

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. 

Iron control chemicals are used during acid stimulation to prevent the precipitation of iron-containing compounds. The precipitation of these compounds in the critical near-wellbore area can decrease well productivity or injectivity. Acetic acid, citric acid, NTA, EDTA, and erythorbic acid are applied [1726,1727]. A time dependence of iron (IQ) hydroxide precipitation... 

Oxidation of the lipid structure in foods containing oils and fats produces carbonyl compounds which are responsible for the flavor and odor associated with rancidity (B-81MI11508) the use of a suitable antioxidant can delay this process. Several heterocyclic compounds are among the antioxidants suitable for use in food ascorbic acid (69) and certain of its derivatives and erythorbic acid. The quinoline derivative (70) is mainly used as an antioxidant in animal feed, but it can also be used to preserve the color of paprika, chili powder and ground chili. 

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