Manufacture of Vegetable Ghee.
Liquid vegetable Ghee are largely triglycerides of unsaturated fatty acids (oleic, linoleic). On hydrogenation in the presence of nickel and low pressures, some of the carbon-carbon double bonds (C=C) are saturated to give a solid fat.
In actual practice, the degree of hardening is carefully controlled to produce a fat of the desired consistency. The partially hydrogenated vegetable oil thus formed is deodorized by treatment with steam in vacuum and decolorized by agitation with Fullers earth and carbon. The product is mixed with vitamins and antioxidants and is sold as Banaspati or Vegetable ghee for kitchen use. Vegetable ghee is preferred over oils for convenience, better appearance and taste, as also its stability to turn rancid.
Margarine is a substitute of butter which is prepared by hydrogenation of groundnut oil (peanut oil) or cottonseed oil. The resulting product is often churned with milk and artificially coloured to give it flavor and consistency resembling that of butter.
In India, the main oil stock used for making vegetable ghee is groundnut oil, or cottonseed oil for better quality product.