Fat (Study Notes)

Fat One of the organic compounds in the ester group which is found in many plants, animals or humans and is very useful for human life is fat. Fats are carboxylate derivatives of glycerol esters called glycerides in the form of triglycerides and triacylglycerols113 . An example of fat is the wax produced by bees. In human body at can found in the subcutaneous tissue around the stomach, fat tissue around the kidneys. Liquid fats are liquid at room temperature are called oils while the term fat is usually used for those that are solid. Fats produced by animals while oils come from plants. Structure and Nomenclature of Fats Fat here is an ester of fatty acids with glycerol114. Glycerol consisting of three carbon atoms where each carbon atom has an –OH group. Monoglycerides form can binded by one glycerol. In fat, one glycerol molecule binds three fatty acid molecules, therefore, fat is a triglyceride.Fats formed by glycerol with high levels of carboxylic acids and this acid that make up fat are called fatty acids. In fat, one glycerol molecule binds three fatty acid molecules, therefore fat is a triglyceride. In the fat structural formula R1–COOH, R2– COOH, and R3–COOH are fatty acid molecules bound to glycerol. The three fatty acid molecules may be the same (called simple fatty acids) or different (called mixed fats). But in general, fat molecules are formed from two or more types of fatty acids. Properties of Fats 1) Physical Properties of Fat Animal fats are generally solid at room temperature, while fats from plants are liquid115 . Fats that have a high melting point contain saturated fatty acids, while liquid fats (oil) contain unsaturated fatty acids. Animal and plant fats have different fatty acid compositions.To determine the degree of unsaturation of the fatty acids contained in it, it is measured using the iodine number. Iodine can react with double bonds in fatty acids. Each iodine molecule carries out an addition reaction at a double bond. Therefore, the more double bonds there are, the more iodine bonds that can react.Fat can cause an unpleasant smell and taste when it left in the air for a long time beacuse this condition caused by the hydrolysis process which produces free fatty acids. Apart from that, there can also be an oxidation process of unsaturated fatty acids the result of which will increase the odor and unpleasant taste. Oxidation of unsaturated fatty acids will produce peroxides and then aldehydes will be formed. 2) Chemical Properties of Fats Saponification or Saponification Reaction (Latin, sapo = soap) Fats and oils can become rancid because they can hydrolyze and oxidize if left in contact with air for too long117 . The most common hydrolysis is with alkali or lipase enzymes. Hydrolysis with alkali is called saponification because one of the results is a fatty acid salt called soap118 . The hydrolysis reaction is useful for determining the saponification number. Saponification number is a number that states the number of milligrams of KOH needed to soap one gram of fat or oil. The large or small saponification number depends depends on the mass of the fat molecule. Halogenation Unsaturated fatty acids, both free and bound as esters in fats or oils add halogens (I2 or Br2) to their double bonds Because the degree of absorption of a fat or oil is proportional to the number of double bonds in the fatty acid, the amount of halogen that can react with the fat used to determine the degree of unsaturation. To determine the degree of unsaturation of fatty acids contained in fat, it is measured using the iodine number. The iodine number is a number that states the number of grams of iodine that can react with 100 grams of fat. Iodine can react with double bonds in fatty acids. Each iodine molecule carries out an addition reaction at a double bond. Therefore, the more double bonds there are, the bigger the number. Hydrogenation A large number of industries have been developed to convert plant oils into solid fats by means of catalytic hydrogenation (a reduction reaction). The process of converting oil into fat by hydrogenation is sometimes better known as the hardening process. Fat Function The general function of fat is as an energy source, raw material for hormones, helping transport fatsoluble vitamins, as an insulating material against temperature changes, and protecting internal body organs. A study once reported that experimental animals that did not get sufficient amounts of fat in their food experienced stunted growth, some even stopped growing and eventually died. Fats and oils will stay in the stomach longer than carbohydrates and proteins as well as the process of fat absorption being slower than other elements. Energy can supplied by the fats because one gram of fat contains 9 calories while 1 gram of carbohydrates only contains 4 calories. Another function of fat is to help the absorption of fat-soluble vitamins .