Economic significance Vitamin

The use of electrodialysis in food, drug, and chemical industries has been studied quite extensively in recent years. Several applications have considerable economic significance and are already well established today. One is the demineralization of cheese whey [46]. Normal cheese whey contains between 5.5 and 6.5 % of dissolved solids in water. The primary constituents in whey are lactose, protein, minerals, fat and lactic acid. Whey provides an excellent source of protein, lactose, vitamins, and minerals, but in its normal form it is not considered a proper food material because of its high salt content. With the ionized salts substantially removed, whey provides an excellent source for the production of babyfood. The partial demineralization of whey can be carried out quite efficiently by electrodialysis. 

An important raw material for the partial synthesis of steroid hormones (and Vitamin D) is cholesterol, which (prior to the BSE crisis) was isolated from the spinal cord of cattle. Another important source is the fat in sheep s wool (lanolin), which contains around 15 % of cholesterol. Among the plant sterols, stigmasterol is of great economic significance as the starting material for the partial synthesis of steroids. It is contained from 12 to 25 % in the non-hydrolysable... 

The i j -configuration of the 6,7-double bond in pre-vitamin D is critical to its subsequent thermal rearrangement to the active vitamin. A photochemical isomerization of pre-vitamin D to yield the inactive trans-isoTnen occurs under conditions of synthesis, and is especially detrimental if there is a significant short wavelength component, eg, 254 nm, to the radiation continuum used to effect the synthesis. This side reaction reduces overall yield of the process and limits conversion yields to ca 60% (71). Photochemical reconversion of the inactive side product, tachysterol, to pre-vitamin D allows recovery of the product which would otherwise be lost, and improves economics of the overall process (70). 

Although the industrial synthesis of vitamin remains largely unchanged from its early beginnings, significant effort has been devoted to improvements in the condensation step, the oxidation of dihydrovitarnin to vitamin K, and in economical approaches to vitamin (vide infra). Also, several chemical and biochemical alternatives to vitamin have been developed. 

With these reactions, a vitamin A synthesis based on acetylene was developed in the 50s, but this synthesis gained no industrial significance since the individual synthesis steps were not economically practicable. It was not possible to realise the concept aimed at, namely to link a C15 unit with a C5 building block, in the last stage. For this purpose, a reaction was required in which C—C linkage takes place with the formation of an olefmic double bond. The other double bonds are also possible linking points for the synthesis of the vitamin A molecule (2) ... 

The process has been applied to strip oil-soluble vitamins, sterols, and fatty acids from fats and oils. Cholesterol has been successfully removed from anhydrous milkfat in the range of 70-90% (44, 45). Extensive smdies were performed and various temperatures and pressures were used to fractionate milkfat (46). Unfortunately, the process has not proved to be economically feasible due to the low butter fat yield when significant cholesterol was removed (Land O Lakes research). 

An experiment of supplementary feeding in pregnancy on a large scale was reported by Balfour (154). The material was well selected and classified as to parity, age and economic conditions. There were 11,618 women who received supplements and 8095 who did not. Both classes received milk in some form. The supplemented group received vitamins A, D, and B-complex, calcium, phosphorus, and iron. There was a significant reduction in the stillbirth and neonatal mortality rates of the fed group as compared with the controls. 

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