Hydrogenation is the process of adding hydrogen to an edible vegetable oil using a catalyst to produce a fat with semi-solid consistency. For the hydrogenation process the catalyst that is most often used is powered nickel compound. To carry out hydrogenation the oil is “sparged” at a high temperature and pressure with hydrogen in the presence of a catalyst. This means that hydrogen atoms are added to the double bonds in vegetable oils. As each double-bond is broken, the two hydrogen atoms each form single bonds with the two carbon atoms.
This elimination of double bonds by adding hydrogen atoms is called saturation. Depending on the degree of saturation the oil is partially or fully hydrogenated. If the degree of saturation increases, the oil moves towards becoming fully hydrogenated. In this way unsaturated vegetable fats and oils can be transformed through partial or complete hydrogenation into fats and oils of higher melting point and thickness.
Oil that is completely hydrogenated becomes solid at room temperature. These oils contain more trans fatty acids as the bonds have changed after hydrogenation. Moderately hydrogenated oils remain liquid at room temperature but they contain more saturated fatty acids than were present in the original oil before hydrogenation but the trans fatty content is lower than fully hydrogenated oils. Margarines are often a mixture of both hydrogenated fats and unhydrogenated vegetable oils. A margarine made from naturally more saturated oils will be easier to spread than margarine made from, say, hydrogenated soya oil.
Oil is hydrogenated to increase its resistance to rancidity (oxidation) or to change its physical appearance. Since hydrogenated fats are not rancid they tend to have a longer shelf life. This is why hydrogenated fats are used in food products like snacks, crackers and biscuits as they provide a longer shelf life. However, trans fatty acids are considered a health hazard as they can raise LDL (bad) cholesterol level and if the intake is high they can also lower HDL (good cholesterol) levels.
Oil that is partially hydrogenated is soyabean oil and this is obtained by light or “brush” hydrogenation. Vanaspati is usually fully hydrogenated and is permitted to be made only from those oils that are listed in the regulations. Additives like colouring, flavouring or other additives harmful to health are not permitted to be added to these oils and nothing that will make it taste or resemble ghee can be added to hydrogenated oils.
List of Ingredients:
For the classes of Edible Vegetable Oil/ Edible Vegetable Fat; the class titles Edible Vegetable Oil/Edible Vegetable Fat or Both, Hydrogenated or Partially Hydrogenated Oil can be used for the list of ingredients.
Food Business Operators have to mention the use of hydrogenated oils and partially hydrogenated oils in their food products like; ‘hydrogenated vegetable fats used – contains trans fats’.
FBOs can claim ‘trans fat free’ where the trans fat is less than 0.2 gm per serving of food and a health claim ‘saturated fat free’ may be made in cases wherein the saturated fat does not exceed 0.1 gm per 100 gm or 100 ml of food.