The Lipids Triglycerides Phospholipids and Sterols Chapter 5 Lecture 1 Dr Alisha Rovner University of Delaware Nutrition Concepts NTDT200 Fall 2013 Introduction Macronutrient 9kcal gram Fats are important component in the diet Only when too much or too little fat is consumed does poor health develop ADMR 20 35 kcalories from fat Fats are composed of carbon C hydrogen H and oxygen O but compared to carbohydrates they have more C H in proportion to O Lipid Definitions Family of compounds that include Triglycerides Phospholipids Sterols Characterized by their insolubility in water Fats and Oils Fats Lipids that are solid at room temperature Oils Lipids that are liquid at room temperature Healthy Fats Well balanced healthy meals provide some fat with an emphasis on monounsaturated and polyunsaturated fats p149 Healthy Fats People who eat nuts as part of a hearthealthy diet can lower the LDL low density lipoprotein or bad cholesterol level in their blood High LDL is one of the primary causes of heart disease Qualified Health Claim Nuts Scientific evidence suggests but does not prove that eating 1 5 ounces per day of most nuts as part of a diet low in saturated fat and cholesterol may reduce the risk of heart disease Healthy Fats p160 Qualified Health Claim Olive oil Limited and not conclusive scientific evidence suggests that eating about 2 tablespoons 23 grams of olive oil daily may reduce the risk of coronary heart disease due to the monounsaturated fat in olive oil To achieve this possible benefit olive oil is to replace a similar amount of saturated fat and not increase the total number of calories you eat in a day Healthy Fats Unhealthy Fats A double bacon cheeseburger fries and milkshake has 1600 kcalories 90 grams of fat and more than 30 grams of saturated fat far exceeding dietary fat guidelines for the entire day Saturated fats tend to raise bad LDL cholesterol levels in the blood which in turn increases the risk for heart disease p150 Lipid Family Lipd ami Table 5 2 p138 Chemist s View of Fatty Acids and Triglycerides Fatty acids Chain of carbon atoms with hydrogens attached methyl group CH3 at one end and acid group COOH at other end Usually even number of carbons 18 carbon fatty acids abundant in food Saturations Saturated full of hydrogens Unsaturated missing hydrogens Glycerol When glycerol is free an Oh group is attached to each carbon When glycerol is part of a triglyceride each carbon is attached to a fatty acid Figure 5 2 p133 Condensation of Glycerol and Fatty Acids to Form a Triglyceride Figure 5 3a p133 18 Carbon Fatty Acids Methyl end Acid end A saturated fatty acid carries the maximum of H p130 18 Carbon Fatty Acids Omega 3 and Omega 6 Fatty Acids Compared Polyunsaturated Fatty Acid Composition of Common Food Fats Hydrogenation Chemical process by which hydrogens are added to mono or polyunsaturated fatty acids to reduce the of double bonds making the fats more saturated solid Two advantages Protects against oxidation prolonging shelf life Improves texture of foods ie makes margarines spreadable Hydrogenation Cis and Trans Fatty Acids Compared Chemist s View of Phospholipids and Sterols Phospholipids Solubility in fat and water Emulsifiers in food industry Lecithin Food sources Roles Part of cell membranes Emulsifiers Lecithin Chemist s View of Phospholipids and Sterols Sterols Food sources Cholesterol Plant sterols Roles of sterols Body compounds made from cholesterol
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