Lipids part 1.ppt oils and fats description
- 1. The Lipids: Triglycerides, Phospholipids and Sterols
- 2. Lipids Objectives • 1. Understand the chemical composition and differences between fats • 2. Explain the structural and functional processes of triglycerides, phospholipids, and sterols • 3. Describe the process of fat digestion and absorption • 4. Discuss the different types of lipoproteins in the body • 5. Clarify the recommended intakes of fat and essential fatty acid requirements to meet daily nutritive needs • 6. Describe the health-risk factors with over consumption of lipids in the diet
- 3. Fatty Acids • The Length of the Carbon Chain – long-chain, medium-chain, short-chain • The Degree of Unsaturation – saturated, unsaturated, monounsaturated, polyunsaturated • The Location of Double Bonds – omega-3 fatty acid, omega-6 fatty acid
- 4. The Length of the Carbon Chain Short-chain Fatty Acid (less than 6 carbons) Medium-chain Fatty Acid (6-10 carbons) Long-chain Fatty Acid (12 or more carbons)
- 5. Fatty Acids are Key Building Blocks • Saturated Fatty Acid • All single bonds between carbons
- 6. Monounsaturated Fatty Acid (MUFA) One carbon-carbon double bond
- 7. Polyunsaturated Fatty Acid (PUFA) More than one carbon-carbon double bond
- 8. Location of Double Bonds • PUFA are identified by position of the double bond nearest the methyl end (CH3) of the carbon chain; this is described as a omega number; • If PUFA has first double bond 3 carbons away from the methyl end=omega 3 FA • 6 carbons from methyl end=omega 6 FA
- 9. Degree of Unsaturation • Firmness – saturated vs. unsaturated • Stability – oxidation, antioxidants • Hydrogenation – advantages, disadvantages • Trans-Fatty Acids – from hydrogenation
- 10. Hydrogenation
- 11. Cis-fatty acid: H’s on same side of the double bond; fold into a U-like formation; naturally occurring; Trans-fatty acid: H’s on opposite side of double bond; more linear; occur in partially hydrogenated foods;
- 14. 1. Shortening 2. Cube margarine: vegetable oil blend (partially hydrogenated soybean oil and liquid soybean oil), water, whey, etc 1 Tbsp: 9 g fat; 2 g SFA; 2 g PUFA; 2.5 g MUFA; 3. Light Tub Margarine: water, liquid and partially hydro- genated soybean oil, maltodextrin, etc. 1 Tbsp: 6 g fat; 1 g SFA;
- 18. But, is all Trans Fat Bad? CLA Conjugated Linoleic Acid
- 19. Essential Fatty Acids (EFA) • Omega-3: –Eicosopentaenoic acid (EPA) –Docosahexaenoic acid (DHA) –Alpha-linolenic acid (ALA) • flaxseed--most, canola (rapeseed), soybean, walnut, wheat germ • body can make some EPA and DHA from ALA • Omega-6 – corn, safflower, cottonseed, sesame, sunflower – Linoleic acid FISH
- 20. Omega-3 Omega-6
- 21. Omega-3 Fatty Acids • Associated with: – anti-inflammatory, antithrombotic, antiarrhythmic, hypolipidemic, vasodilatory properties • Inflammatory conditions • Ulcerative colitis, Crohn’s • Cardiovascular disease • Type 2 diabetes * Mental function • Renal disease * Growth and development
- 22. Essential Fatty Acid Deficiency • Classical symptoms include: – growth retardation, reproductive failure, skin lesions, kidney and liver disorders, subtle neurological and visual problems • People with chronic intestinal diseases • Depression--omega-3 – ?inadequate intake alters brain activity or depression alters fatty acid metabolism? • Attention Deficit Hyperactivity Disorder – lower levels of omega-3--more behavioral problems
- 23. Eicosanoids: made from EFA --derivatives of 20-carbon fatty acids; --affect cells where they are made; --have different effects in different cells --cause muscles to contract and muscles to relax; --help regulate blood pressure, blood clot formation, blood lipids, and immune response; --participate in immune response to injury and infection, producing fever, inflammation, and pain; --include:prostaglandins, thromboxanes, leukotrienes
- 24. Triglycerides • Structure – Glycerol + 3 fatty acids • Functions – Energy source • 9 kcals per gram • Form of stored energy in adipose tissue – Insulation and protection – Carrier of fat-soluble vitamins – Sensory properties in food
- 25. Triglycerides: lipids composed of three fatty acids attached to a glycerol
- 26. Triglycerides • Food sources – fats and oils • butter, margarine, meat, baked goods, snack foods, salad dressings, dairy products, nuts, seeds – Sources of omega-3 fatty acids • Soybean, canola, walnut, flaxseed oils • Salmon, tuna, mackerel – Sources of omega-6 fatty acids • Vegetable oils
- 27. Fatty Acids in Common Food Fats
- 29. Phospholipids • Structure – Glycerol + 2 fatty acids + phosphate group • Functions – Component of cell membranes – Lipid transport as part of lipoproteins – Emulsifiers – Phosphatidylcholine • Food sources – Egg yolks, liver, soybeans, peanuts
- 30. Cell membranes are phospholipid bilayers
- 31. Sterols: Cholesterol • Functions – Component of cell membranes – Precursor to other substances • Sterol hormones • Vitamin D • Bile acids • Synthesis – Made mainly in the liver • Food sources – Found only in animal foods
- 32. Lipid Digestion • In the Mouth – hard fats begin to melt; lingual lipase • In the Stomach – gastric lipase--SCFA • In the Small Intestine – release of CCK; bile-emulsifier; fat drawn into surrounding watery fluids; intestinal lipases; remove each TG fatty acid; leave glycerol; • Bile Routes – reabsorbed or trapped by dietary fiber
- 34. Olestra • Sucrose + fatty acids • Indigestible – provides zero kcals • Reduces absorption of fat- soluble vitamins • So many fatty acid chains are crowded around the core, the digestive enzymes cannot find a breaking point Orlistat (Xenical) * binds to active site of GI lipase and blocks its activity; thus, lipase can’t break TG down to component parts; TG remains undigested and unabsorbed