Vitamin C products

Most current industrial vitamin C production is based on the efficient second synthesis developed by Reichstein and Grbssner in 1934 (15). Various attempts to develop a superior, more economical L-ascorbic acid process have been reported since 1934. These approaches, which have met with htde success, ate summarized in Crawford s comprehensive review (46). Currently, all chemical syntheses of vitamin C involve modifications of the Reichstein and Grbssner approach (Fig. 5). In the first step, D-glucose (4) is catalytically (Ni-catalyst) hydrogenated to D-sorbitol (20). Oxidation to L-sotbose (21) occurs microhiologicaRy with The isolated L-sotbose is reacted with acetone and sulfuric acid to yield 2,3 4,6 diacetone-L-sorbose,... 

Reichsteia and Grbssner s second L-ascorbic acid synthesis became the basis for the iadustrial vitamin C production. Many chemical and technical modifications have improved the efficiency of each step, enabling this multistep synthesis to remain the principal, most economical process up to the present (ca 1997) (46). L-Ascorbic acid is produced ia large, iategrated, automated faciUties, involving both continuous and batch operations. The process steps are outlined ia Figure 7. Procedures require ca 1.7-kg L-sorbose/kg of L-ascorbic acid with ca 66% overall yield ia 1977 (55). Siace 1977, further continuous improvement of each vitamin C production step has taken place. Today s overall ascorbic acid yield from L-sorbose is ca 75%. In the mid-1930s, the overall yield from L-sorbose was ca 30%. 

It is stable for oxygen evolution and very interesting for selective oxidation reactions ([21] see Chapters 6,15), an industrial application is one step of the vitamin C production [22]). 

Swiss Roll Cell This cell has been developed in Switzerland [89]. A commercial application is one oxidation step at a NiOOH anode in alkaline solution for the vitamin C production [22]. Mesh electrodes of stainless steel (cathode 1) and nickel (anode 3) are rolled up together with spacers of polypropylene mesh (2,4) on the central current feeder (5) and mounted in a cylinder (cells up to 1 m diameter, 200 m active area). The electrolyte streams axially through the cell. 

Swiss-roll cell — This cell was developed in Switzerland in 1982, and it is used on industrial-scale in case of the NiOOH electrode for the oxidation of primary alcohols to carboxylic acids, as, e.g., in vitamin C production. The electrolyte solution flows axially through the cell (see Figure), which is made up of rolled meshes of the nickel net anode and steel net cathode, separated from each other by polypropylene spacers, around the central current feeder rod. 

A nickel anode is in alkaline solution protected against corrosion by a layer of nickel oxides. oxide (NiOOH) is capable of oxidizing a number of functional groups primary alcohols may be oxidized to carboxylic acids [158-161], which is of interest for the technical production of an intermediate for vitamin C production [162]. NiOOH chemically oxidizes the substrate and is regenerated electrochemically a large anode surface, which is realized in the Swiss-roll cell (Chap. 31), is thus advantageous. NiOOH electrodes in form of nickel foam electrodes has been found to be useful for the oxidation of diacetone L-sorbose to diacetone 2-keto-L-gulonic acid in the vitamin C synthesis [163]. 

Sorbitol to L-sorbose oxidation (in vitamin C production) Gluconobacter suboxydans... 

The first one that was recognized as being effective was retinoic acid. This was a prescription ointment drug until the over-the-counter product was approved in the mid-nineties, and proved efFective. Another is glycolic acid, which is available in makeup products or in more concentrated forms from physicians. There is also Kojic acid, alpha hydroxy acid, beta hydroxy acid, and the newest vitamin C products. Hydroquinone is another chemical that is used because it has a bleaching effect on the skin. 

Anode A nickel anode forms in aqueous alkaline solutions a layer of Nickel(IIll-oxide NiOOH. Owing to its application in nickel cadmium and nickel metal hydride accumulators, it is much investigated [20]. It is stable for oxygen evolution and very interesting for selective oxidation reactions ([21] see Chapters 6,15), an industrial application is one step of the vitamin C production [22]). 

Significant inverse association with vitamin C production... 

According to the production process, vitamin C production by biotechnology can now be divided into two-step fermentation and one-step fermentation. The two-step fermentation including tandem fermentation process that uses glucose as substrate and the fermentation process that uses D-sorbitol as substrate (Fig. 12.2). For the... 

Fig. 12.1 Reichstein process for vitamin C production. The D-glucose was hydrogenated to form D-sorbitol. The D-sorbitol was converted into L-sorbose by acetic bacteria. The L-sorbose was further oxidized with protection to form 2-KLG. The 2-KLG was then esterified and lactonized to form vitamin C...

Effects of the Relationship Between Two Bacteria in Mixed Culture on Vitamin C Production... 

The classical two-step fermentation process is the most successful route for vitamin C production for its high yield of 2-KLG on D-sorbitol. Though there are two fermentation process, the yield of L-sorbose on D-sorbitol and the yield of 2-KLG on L-sorbose could achieve to more than 99.5 and 97%, respectively. Few of the industrial process could achieve this level. Therefore, the metabolic engineering on the classical two-step fermentation process is always undergoing. 

Previously, researchers from both industry and academia have invariably noted the inherent disadvantages of the two-step fermentation vitamin C production process, such as long period fermentation, additional sterilizing, control of the mix-culture... 

However, after the report of the innovative two-step fermentation process, the research on the classical two-step based one-step fermentation process seems to be suspended. Few literatures about metabolic engineering of G. oxydans for one-step vitamin C production could be found after then. 

Rose hips are not eaten as such rather, they are concentrated as a powder, made into jams, jellies, and syrups, or brewed as a tea. Rose hips are used as an ingredient of many vitamin C products, often in combination with ascorbic acid. 

Vitamin C (L-ascorbic acid, l-AA), is an essential nutrient for humans and some animal species [9] (Figure 10.1). l-AA is a cofactor of at least eight enzymatic reactions, which are crucial for collagen synthesis. Deficiency in L-AA could cause the most severe symptoms of scurvy in humans [10]. L-AA can also act as an antioxidant [11], and is required for a range of essential metabolic reactions in all animals and plants [9,12]. It is produced internally by almost all organisms with the exception of some species of birds and fish [12, 13]. All species that do not synthesize ascorbate require it in their diet. L-AA is also widely used as a food additive to prevent the oxidation of other nutrients or some food dyes [14]. The global vitamin C production is currently estimated at about 11000 tons annually. The main producers include DSM (Scotland) and other four producers in China (Northeast Pharmaceutical Co. Ltd., North China Pharmaceutical Co. Ltd.,... 

Fioshin and coworkers also proposed the electrochemical synthesis of calcium gluconate [85] and diacetone-2-keto-L-gulonic acid (intermediate product in vitamin C synthesis [86, 87], see Sect. 9.2.7, Electrosynthesis of Diacetone-2-Keto-L-Gulonic Acid in the Vitamin C Production ). In collaboration with electrochemists in Khar kov (the group of Dr. Vasiliy Danilovich Bezuglyy, Sect. 9.1.6), they developed the technology for the production of salicylaldehyde [88]. M.Ya. Fioshin lectured applied electrochemistry to students, and a large number of specialists trained in his department continued to work in EKhOS. 

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