Hydrogenation unit iii

hydrogenation

1. Hydrogenation

2. Need of Hydrogenation Number of double bonds in oils and fats affects physical property such as melting point, crystallinity Generally, double bonds reduce the oil’s melting point

3. Definition Hydrogenation is a chemical process where hydrogen add to double bonds of unsaturated fatty acids produces saturated fats It convert alkenes to alkanes and carried out by H2 gas through the heat , in the presence of a metal catalyst (such as nickel or platinum)

4. For example complete hydrogenation of linoleic acid generates stearic acid which used in cosmetics and in pharmaceuticals

5. Hydrogenation of Unsaturated Oils Unsaturated oils are usually only partially hydrogenated, so that the product is not completely saturated, giving a soft semisolid fat such as margarine This forms a new type of fatty acid called trans-fatty acid, (“man-made” fat). Trans-fatty acids have many of the same properties asSATURATED fats.

6. Cis and Trans Unsaturated Fatty Acids Natural unsaturated fatty acids have cis double bonds. When unsaturated vegetable oils are hydrogenated to form more saturated oils (as in margarine), some of the cis fatty acids are isomerized to trans fatty acids. Trans fatty acids are much more linear than cis fatty acids

7. Cis and Trans Unsaturated Fatty Acids Their melting points are higher. S tudies have shown that trans fats may act similarly to saturated fats and could contribute to heart disease and some cancers. Due to new requirements for including amounts of trans fats on food labels, many companies are developing hydrogenation methods that do not produce trans fats

8. Cis and Trans Unsaturated Fatty Acids

9. Main purposes of hydrogenation oils to solid or semi-solid fats They are a cheap substitute of saturated fats from animal origins, such as lard or butter Hydrogenated oils are more stable than unsaturated oils. The process of hydrogenation transforms fatty acids that are prone to oxidative rancidity, especially in high temperatures during cooking;

10. Vegetable oils used in hydrogenation are usually more uniform in length with medium to long chains and after saturation are more stable . point , are easily manipulated by changing the degree of saturation. For instance, the final product may be hardened or softened by adjusting how much hydrogen is added during the process;