Vegetable oils which have been partially hydrogenated, are now partially saturated so the melting point increases to the point where a solid is present at room temperature.
The degree of hydrogenation of unsaturated oils controls the final consistency of the product. What has happened to the healthfulness of the product which has been converted from unsaturated to saturated fats? A major health concern during the hydrogenation process is the production of trans fats. Trans fats are the result of a side reaction with the catalyst of the hydrogenation process. This is the result of an unsaturated fat which is normally found as a cis isomer converts to a trans isomer of the unsaturated fat.
Isomers are molecules that have the same molecular formula but are bonded together differently. Focusing on the sp 2 double bonded carbons, a cis isomer has the hydrogens on the same side.
Due to the added energy from the hydrogenation process, the activation energy is reached to convert the cis isomers of the unsaturated fat to a trans isomer of the unsaturated fat. Your email address will not be published. Notice: It seems you have Javascript disabled in your Browser. In order to submit a comment to this post, please write this code along with your comment: deaac2edfc6e9e.
Home About Recipes Spend Smart. Eat Smart. Jody Gatewood Jody Gatewood is a Registered Dietitian who enjoys spending time in the kitchen baking and preparing meals for her family. July 6, Leave a Reply Cancel reply Your email address will not be published. Join Our Mailing List Enter your email address:.
As a result the molecules cannot pack closely together. Fat molecules do not have the same degree of distortion and can pack closely together. This increases their melting point. The poorer packing in oils makes London dispersion forces between the oil molecules weaker than between fat molecules. Less heat energy is needed to separate oil molecules, so oils have lower melting points than fats.
To increase the melting point of an oil, addition reactions between the double bonds and hydrogen can take place. These latter are usually found in plants, but fish also store liquid forms of triglycerides fish oils. Solid fats usually consist of saturated fatty acids, whereas liquid oils are made largely of unsaturated acids, however this can be artificially manipulated to produce triglycerides with other desirable properties.
Natural lard a fat from animal sources melts at 30 o C above average room temperature , whereas natural olive oil becomes a solid only below -6 o C. This latter is typical for valuable vegetable oils in general, but these oils can me made into semi-solids by partial hydrogenation of some of the double bonds found in the hydrocarbon chains. This conversion is not without its problems, however.
0コメント