Mineral ascorbates and uses

Mineral ascorbates are a group of ascorbates (vitamin C).They consist of mineral cations bonded to ascorbic acid (the anion of ascorbic acid).

Make 

Mineral ascorbate is a powder prepared by reacting ascorbic acid with mineral carbonate in aqueous solution, expelling carbon dioxide, drying the reaction product, and then grinding the dried product to the desired particle size.Choice of mineral carbonates can be calcium carbonate, potassium carbonate, sodium bicarbonate, magnesium carbonate or many other mineral forms.

Uses

• The mineral ascorbate is used as a dietary supplement and food additive.

• Ascorbate may be better tolerated by the body than the corresponding weakly acidic ascorbic acid.

• Ascorbate is a highly reactive antioxidant used as a food preservative.

• Examples of mineral ascorbates are:

• Sodium Ascorbate (E301)

• Calcium Ascorbate (E302)

• Potassium ascorbate (E303)

Magnesium ascorbate 

Sodium ascorbate

Sodium ascorbate is one of many mineral salts of ascorbic acid (vitamin C).The molecular formula of this compound is C6H7NaO6. As the sodium salt of ascorbic acid, it is known as mineral ascorbate. It has not been shown to be more bioavailable than any other form of vitamin C supplementation.Sodium ascorbate typically provides 131 mg of sodium per 1,000 mg of ascorbic acid (1,000 mg of sodium ascorbate contains 889 mg of ascorbic acid and 111 mg of sodium).As a food additive, the E number is E301, which is used as an antioxidant and acidity regulator. It is approved as a food additive in the European Union,United States,Australia and New Zealand.In in vitro studies, sodium ascorbate has been found to produce cytotoxic effects in various malignant cell lines, including particularly susceptible melanoma cells.

Production

Sodium ascorbate is prepared by dissolving ascorbic acid in water and adding an equal amount of sodium bicarbonate.After bubbling ceased, isopropanol was added to precipitate sodium ascorbate.

Calcium ascorbate

Calcium ascorbate is a compound with the molecular formula CaC12H14O12.It is the calcium salt of ascorbic acid, one of the ascorbic acid minerals.It contains approximately 10% calcium (by mass).As a food additive, it has the E number E 302.It is approved for use as food in the European Union,the United States,and Australia and New Zealand.

Potassium ascorbate

Potassium ascorbate is a compound with the molecular formula KC6H7O6.It is the potassium salt of ascorbic acid (vitamin C) and the mineral ascorbate.As a food additive, its E number is E303 and its INS number is 303.Although it is not permitted as a food additive in the UK, US and EU it has been approved for use in Australia and New Zealand.According to some studies, it shows strong antioxidant activity and antitumor properties.

Industrial preparation

Eighty percent of the world's ascorbic acid supply is produced in China.Ascorbic acid is prepared industrially from glucose by a method based on the historic Reichstein process. In the first step of the five-step process, glucose is catalytically hydrogenated to sorbitol, which is then oxidized to sorbose by the microorganism Acetobacter suboxydans.Only one of the six hydroxyl groups is oxidized by this enzymatic reaction.From this point, there are two routes to choose from.Treatment of the product with acetone in the presence of an acid catalyst converts four of the remaining hydroxyl groups to acetals.Unprotected hydroxyl groups are oxidized to carboxylic acids by reaction with the catalytic oxidant TEMPO (regenerated by sodium hypochlorite-bleach solution).Historically, industrial preparation by the Reichstein process used potassium permanganate as the bleaching solution.The acid-catalyzed hydrolysis of this product has the dual function of removal of two acetal groups and ring-closing lactonization.This step produces ascorbic acid.The yield of each of the five steps is greater than 90%.A more biotechnological process first developed in China in the 1960s but further developed in the 1990s, bypassing the use of the acetone protecting group.A second genetically modified microbial species, such as Erwinia mutans, oxidizes sorbose to 2-ketogluconic acid (2-KGA), followed by ring-closing lactonization by dehydration.This method is used in the main process of the ascorbic acid industry in China,which supplies 80% of the world's ascorbic acid.Researchers in the US and China are racing to design a mutant that can undergo direct one-pot fermentation from glucose to 2-KGA, bypassing the need for a second fermentation and reduction of glucose to sorbitol.There is a type of D-ascorbic acid, which does not exist in nature, but can be synthesized artificially.Specifically, L-ascorbic acid is known to be involved in many specific enzymatic reactions that require the correct enantiomer (L-ascorbic acid instead of D-ascorbic acid).The optical rotation of L-ascorbic acid.D = +23°.Determination.The traditional method for analyzing ascorbic acid content is titration with oxidizing agents, and various methods have been developed.The popular iodometric method uses iodine in the presence of a starch indicator. Iodine is reduced by ascorbic acid, and when all the ascorbic acid has reacted, iodine is in excess, forming a blue-black complex with the starch indicator.This indicates the endpoint of the titration.

As an alternative, ascorbic acid can be treated with an excess of iodine and then back-titrated with sodium thiosulfate using starch as an indicator.This iodometric method has been modified to take advantage of the reaction of ascorbic acid with iodate and iodide in acid solution.Electrolysis of potassium iodide solution produces iodine, which reacts with ascorbic acid.The end of the process is determined by potentiometric titration in a manner similar to Karl Fischer titration.The amount of ascorbic acid can be calculated by Faraday's law.Another alternative is to use N-bromosuccinimide (NBS) as an oxidizing agent in the presence of potassium iodide and starch.NBS first oxidizes ascorbic acid; when the latter is depleted, NBS releases iodine from potassium iodide, which then forms a blue-black complex with starch.