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  1. 1. LIPIDS Classification, Functions, and Properties
  2. 2. DEFINITION • Lipids are organic substances made up of fatty acids and their naturally-existing compounds and derivatives • In nutrition, lipids provide the much needed CALORIES to “burn” as fuel for ENERGY, secondary to carbohydrates • Some micronutrients function well only in the presence of fats or lipids
  3. 3. • Lipids yield fatty acids upon hydrolysis • They combine with fatty acids to form esters • They contain C, H,O,N sometimes K • Relatively INSOLUBLE IN WATER and ordinary solvents • Soluble in nonpolar/organic solvents like ether, chloroform, acetone, benzene
  4. 4. CLASSIFICATION OF LIPIDS A.SIMPLE LIPIDS  Esters of fatty acids with various alcohols 1. Neutral fats (glycerol esters) 2. Waxes (esters of higher alcohols) ex: Cholesterol esters,Vitamin A,D esters
  5. 5. B. COMPOUND LIPIDS 1. Lipids that contain other radicals such as Phosphoric acids,or a nitrogenous base Ex: lecithin, Cephalin, Lipositol 2. Glycolipids- contain Carbohydrate and Nitrogenous base 3. Ill-defined lipids  amino lipids(Have NH2)  sulfo lipids (have SO4)
  6. 6. C. DERIVED LIPIDS - Lipids that are products of hydrolysis of simple and compound lipids 1. Saturated and Unsaturated Fatty acids 2. Mono and Di glycerides 3. Alcohols( sterols and cholesterol) 4. Miscellaneous (ex Squalene, Carotenoids, Vitamins D, E, K)
  7. 7. FATS • Are esters of fatty acids with GLYCEROL • EXAMPLES: 1. Animal fats- Oleic, palmitic, stearic acid 2. Mutton fat- more stearic and less oleic than pork 3. Butter fat- mainly palmitic and oleic, with small amounts of butyric acid and caproic acids 4. Human Fat- mostly oleic acid, yellowish tinge is due to carotene and xanthrophyl pigments
  8. 8. CHEMICAL PROPERTIES 1.Hydrogenation(introduction of highly pressurized Hydrogen) 2. Oxidation( exposure to Oxygen) 3. Hydrolysis (breaks down into simpler forms) 4.Saponification ( process of soap making)
  9. 9. APPLICATION OF ITS CHEMICAL PROPERTIES A. HYDROGENATION Hydrogenation converts liquid vegetable oils into solid or semi-solid fats, such as those present in margarine. Changing the degree of saturation of the fat changes some important physical properties such as the melting range, which is why liquid oils become semi-solid. Other advantages: longer shelf life, oxidative stability, cheaper
  10. 10. B. OXIDATION Oxidative rancidity is associated with the degradation by oxygen in the air. Via a free radical process, the double bonds of an unsaturated fatty acid can undergo change, releasing volatile aldehydes and ketones. This process can be suppressed by the exclusion of oxygen or by the addition of antioxidants. Oxidation primarily occurs with unsaturated fats.
  11. 11. • When these processes occur in food, undesirable odors and flavors can result. In some cases, however, the flavors can be desirable (as in aged cheeses). In processed meats, these flavors are collectively known as warmed over flavor. Rancidification can also detract from the nutritional value of the food. Some vitamins are highly sensitive to degradation.
  12. 12. 3. HYDROLYSIS Hydrolytic Rancidity • Hydrolytic rancidity occurs when water splits fatty acid chains away from the glycerol backbone in triglycerides (fats). The chemical term is ester hydrolysis. Usually this hydrolysis process goes unnoticed, since most fatty acids are odorless and tasteless. When, however, the triglyceride is derived from short chain fatty acids, the released carboxylic acid can confer strong flavors and odors. A particular problem arises with butter, which contains triglycerides with a high content of butyric acid derivatives.
  13. 13. 4.SAPONIFICATION This is a process that produces soap, usually from fats and lye. In technical terms, saponification involves base (usually caustic soda NaOH) hydrolysis of triglycerides, which are esters of fatty acids, to form the sodium salt of a carboxylate. In addition to soap, such traditional saponification processes produces glycerol. "Saponifiable substances" are those that can be converted into soap.
  14. 14. Saponification reaction
  15. 15. FATTY ACIDS A. SATURATED  fatty acids composed of single bonds and are usually solid at room temperature  These are fats from animal sources  Butter, lard
  16. 16. B .UNSATURATED FATTY ACIDS  fatty acids that are composed of one or more double bonds  They are usually liquid at room temperature  “OILS” are mostly from plant sources Olive oil, corn oil, linseed oil, palm oil
  17. 17. OTHER IMPORTANT FATTY ACIDS 1. Omega Fatty acids (polyunsaturated) Main source: Fish and Fish oil 2. Linoleic,Linolenic, Arachidonic Acid Sources: Nuts, Plant oils ** These are not readily produced by the body, defficiency may lead to impaired growth and reproduction, eczema,dermatitis,excessive thirst, kidney damage
  18. 18. FUNCTIONS OF FATS IN THE BODY 1.Vitamins A, D, E, and K are fat-soluble, meaning they can only be digested, absorbed, and transported in conjunction with fats. Fats are also sources of essential fatty acids, an important dietary requirement.
  19. 19. 2. Fats play a vital role in maintaining healthy skin and hair, insulating body organs against shock, maintaining body temperature, and promoting healthy cell function.
  20. 20. 3. Fats also serve as energy stores for the body, containing about 37.8 kilojoules (9 calories) per gram of fat. They are broken down in the body to release glycerol and free fatty acids. The glycerol can be converted to glucose by the liver and thus used as a source of energy.
  21. 21. 4. Fat also serves as a useful buffer towards a host of diseases. When a particular substance, whether chemical or biotic—reaches unsafe levels in the bloodstream, the body can effectively dilute—or at least maintain equilibrium of—the offending substances by storing it in new fat tissue. This helps to protect vital organs, until such time as the offending substances can be metabolized and/or removed from the body by such means as excretion, urination, accidental or intentional bloodletting, sebum excretion, and hair growth.
  22. 22. ***While it is nearly impossible to remove fat completely from the diet, it would also be unhealthy to do so. Some fatty acids are essential nutrients, meaning that they can't be produced in the body from other compounds and need to be consumed in small amounts. All other fats required by the body are non- essential and can be produced in the body from other compounds
  23. 23. Thank you!