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vitamin C

INTRODUCTION Vitamin C is a product that is usually found in many foods and produced by an abundance of chemical companies as dietary supplements. This vitamin is essential to the scurvy patients and used abundantly in cosmetic company due to its antioxidant properties. In the terms of its production, the fact that vitamin C has two totally and distinctly separate sides is still unknown to many people even doctors. The two sides consist of "L"-Ascorbic Acid, which is the (-) side, and DAscorbic Acid, which is the (+) side. The L side of Vitamin C is the active side, and is the side which is beneficial to mankind. The D-side of Vitamin C is designated as useless and discarded by the body, as most research shows. People ingesting Vitamin C would only benefit from the "L" side of Vitamin C for example, in an orange, the Vitamin C is primarily the L side [1]. Therefore, during the whole process of the production of vitamin c, the desired end product is Lascorbic acid.

THE PRODUCTION OF VITAMIN C

Vitamin C has been industrially produced for around 70 years. Over these years, many methods has been invented and proposed to produce vitamin C efficiently such as Reichstein Process, TwoStep Fermentation Process and Single Step Fermentation Process. The most common methods used are Reichstein Process and Two-Step Fermentation Process. The first method used is the classical Reichstein process back in the 30s. This process was introduced by Tadeus Reichstein and his collegues in 1935 [1]. The Reichstein process uses a single pre-fermentation process followed by a purely chemical route which involves five steps.

REICHSTEIN PROCESS

This process commonly use glucose or sugar as its raw material. Sugars can be derived from any sugar bearing plants such as corn, wheat, and many more. However, for the production of vitamin C, D-glucose is used as its raw material [1][2].

The first step is the hydrogenation of D-glucose to D-sorbitol, an organic reaction with nickel as a catalyst. In this step, D-glucose is reduced to sorbitol under high temperature (140-150°C) and high pressure (80-125 atm ). This is done by putting it in a big boiler[3].

The next step is the microbial oxidation of sorbitol to L-sorbose at pH 4 to pH 6 and temperature of 30 °C by using a bacteria. A bacteria called Acetobacter suboxydans is added to eat some hydrogens so that oxygen double bond is formed.

In the protection step, acetone is used as catalyst. The four remaining hydroxyl group in sorbose are protected by acetal linkages. The product of this step is Diacetone-L-sorbose.

The forth step will be the organic oxidation with potassium permanganate followed by heating with water at temperature over 100°C[3]. The unprotected hydroxyl group is chemically oxidized to carboxylic acid. The most complicating part of this step is to make sure the right part is oxidized. At the end of this step, 2-keto-L-glucanic acid is produced [4].

The only thing left to do is to join the acid with alcohol and removes the water. This step is called Gamma Lactonisation. Hydrochloric acid and ethanol were added. Hydrolysis with the acid removes the two acetal groups and the acid will joined to the alcohol forming a circle. The end result is Vitamin C in crystals [4].

Chemical reaction of each steps in Reichstein process :

D-glucose

D-sorbitol

L-sorbose

L-ascorbic acid (vitamin c)

2-keto-L-glucanic acid
Diagram 1[5].

DiacetoneL-sorbose

However, Reichstein process has many disadvantages. The process needs to go through six working procedures and is difficult to operate continuously. Therefore, many researchers are eager to find out several different processes to improve the traditional Reichstein process. One of the most successful routes is the “two-step fermentation” process, which was already applied in industrial scale for more than 40 years [6]. Along with the development of biotechnology industry, there are further...
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