Chapter 5 Lipids: Fats and Oils

The Art of Nutritional Cooking, 3 rd edition Baskette/Painter © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. 2 Key Concepts Fat varies in function and structure. Saturated fat comes largely from animal sources; unsaturated fat from plants. Saturated fat increases and poly- and monounsaturated fat decrease low-density lipoprotein (LDL) cholesterol. Omega-3 and omega-6 fatty acids require balanced consumption. Fat is an necessary component of the diet. Consuming excess saturated fat is a risk factor for certain diseases. When partially hydrogenating unsaturated fat, trans-fats are formed. A diet low in saturated fat, free from trans-fat and moderate in total fat is desirable. Cholesterol serves a vital function in body processes and in health.

The Art of Nutritional Cooking, 3 rd edition Baskette/Painter © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. 3 Lipids Lipid is the umbrella term for the group of substances in foods that are insoluble in water Dietary lipids are composed of: cholesterol, fats, oils phospholipids

The Art of Nutritional Cooking, 3 rd edition Baskette/Painter © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. 4 Fats Fat is a broad term that has many meanings Butter and lard are fat, Nuts are high in fat, Some meats are fatty, Avocados and olives are high in fat Not all dietary fats are of equal nutritional value

The Art of Nutritional Cooking, 3 rd edition Baskette/Painter © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. 5 Fat or Oil If a lipid is solid at room temperature it is normally called a fat; If liquid at room temperature it is called an oil

The Art of Nutritional Cooking, 3 rd edition Baskette/Painter © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. 6 Triglyeride Most dietary fats and oils are consumed in the form of triglyceride, a glycerol with three fatty acid chains of various lengths

The Art of Nutritional Cooking, 3 rd edition Baskette/Painter © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. 7 Fat Saturations Fatty acid chains can be saturated, monounsaturated, or polyunsaturated the degree of saturation is determined by the amount of hydrogen on the carbon chain

The Art of Nutritional Cooking, 3 rd edition Baskette/Painter © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. 8 Saturated Fats Saturated fat has all of the hydrogen it can possibly hold it is saturated, or full, with hydrogen for cooking purposes this increases the melting point; making the fat solid at room temperature

The Art of Nutritional Cooking, 3 rd edition Baskette/Painter © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. 9 Monounsaturated Fats Monounsaturated fat is missing one hydrogen pair, its carbon chain is not saturated indicated by a double bond in its chemical structure Liquid at room temperature

The Art of Nutritional Cooking, 3 rd edition Baskette/Painter © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. 10 Polyunsaturated Fats Polyunsaturated fatty acids are also not saturated and have more than one double bond higher numbers of double bonds equals a greater degree of polyunsaturation Further classified by where the first double bond is located if the first double bond is on the third carbon from the omega end it is called an omega-3 fat; if the first bond is on the sixth carbon it is an omega-6 fat

The Art of Nutritional Cooking, 3 rd edition Baskette/Painter © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. 11 Omega-6 Omega-6 fatty acids are linoleic acid and arachidonic acid found in plant oils, such as corn, safflower and sunflower

The Art of Nutritional Cooking, 3 rd edition Baskette/Painter © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. 12 Omega-3 Omega-3 fatty acids are typically found in fish as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) also found in plants in the form of alpha-linolenic acid (ALA) found in abundance in flax seed oil and in lesser amounts in walnuts, soy and canola oil

The Art of Nutritional Cooking, 3 rd edition Baskette/Painter © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. 13 Saturated Fats in the Diet Most saturated fat in the diet comes from animal products and processed foods vary in structure and function vary in length and exhibit different properties lauric and myristic acids are shorter chain saturated fats that produce the greatest rise in LDL cholesterol in the blood Not all saturated fats elevate blood cholesterol to the same extent

The Art of Nutritional Cooking, 3 rd edition Baskette/Painter © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. 14 Plant Based Saturated Fats Tropical oils such as coconut, palm and palm kernel oils are highly saturated

The Art of Nutritional Cooking, 3 rd edition Baskette/Painter © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. 15 Healthy Fats Polyunsaturated fatty acids, such as linoleic acid, lower LDL cholesterol levels and are essential in the diet The US national nutrition policy has focused on substituting some of the saturated fat in the diet with polyunsaturated fat consuming a healthy balance of the omega-6 and omega-3 fatty acids is important

The Art of Nutritional Cooking, 3 rd edition Baskette/Painter © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. 16 Healthy Omega-3 Researchers first found that omega-3 fatty acids might decrease the risk of cardiovascular disease (CVD) in 1971 when the rate of CVD in a Danish population was compared to a group of Eskimos the Eskimos had a very low incidence of cardiovascular disease yet their diet was very high in animal fat the fat in the diet was mainly coming from fish, whales and seals, all high in omega-3 fatty acids

The Art of Nutritional Cooking, 3 rd edition Baskette/Painter © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. 17 Plant Sources of Omega-3 Flax seed oil is the most abundant plant source with omega-3 totaling about two-thirds of its total oil content Canola oil, which is made from rapeseed (a relative of the mustard family grown in Canada and the northwestern United States, with oil-rich seeds), contains 60% oleic, 24% linoleic, and 10% alpha- linolenic fatty acid Walnuts are a good source of alpha-linolenic fatty acid Soybean oil also contains alpha-linolenic fatty acid, in addition to generous amounts of linoleic acid

The Art of Nutritional Cooking, 3 rd edition Baskette/Painter © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. 18 Monounsaturated Fats The main monounsaturated fatty acid is oleic acid, found in many fats the body produces oleic from acetic acid animal fats vary in oleic acid content from 20 to 40% vegetable oils range from 12 to 75% oleic the richest source of oleic acid is olive oil, followed by canola oil and then peanut oil

The Art of Nutritional Cooking, 3 rd edition Baskette/Painter © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. 19 Cholesterol One of the substances found in plaque that produces atherosclerosis A fat-like, waxy substance that yields few calories compared to fats Classified as a sterol and made by the liver Obtaining it from the diet is unnecessary

The Art of Nutritional Cooking, 3 rd edition Baskette/Painter © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. 20 Foods High in Dietary Cholesterol Fish eggs (such as caviar and shad roe), Brains, Liver, Egg yolks, Shrimp Sardines Milk contains a small amount of cholesterol, most of it in butterfat Foods made with large amounts of fat from dairy, such as cheeses and ice cream All meats, poultry, and fish regardless of how lean they may be No plants

The Art of Nutritional Cooking, 3 rd edition Baskette/Painter © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. 21 Cholesterol is Made in the Body The liver makes much more cholesterol (approximately 1000 milligrams per day) than the body gets from food

The Art of Nutritional Cooking, 3 rd edition Baskette/Painter © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. 22 Benefits of Cholesterol Necessary for hormone production, For vitamin D synthesis, For making bile the liver produces about 700 milligrams of cholesterol daily for this purpose alone bile functions as an emulsifier in fat digestion Also found in human breast milk demonstrating cholesterol’s importance in infant development

The Art of Nutritional Cooking, 3 rd edition Baskette/Painter © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. 23 Lecithin A phospholipid similar to triglycerides but one of the fatty acids has been replaced by a phosphate group The most important phospholipid is Lecithin used in food products as an emulsifier

The Art of Nutritional Cooking, 3 rd edition Baskette/Painter © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. 24 Digestion of Fat Begins in the mouth by chewing and mechanically breaking down food a slight amount enzymatic digestion happens in the mouth by the action of lingual lipase and in the stomach via gastric lipase Most fat digestion takes place in the small intestine

The Art of Nutritional Cooking, 3 rd edition Baskette/Painter © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. 25 Metabolism of Lipids After processing by the liver, individual dietary fats enter a distribution system in the body our bodies are water based, which normally does not mix with fats Triglycerides and cholesterol are then packaged by the liver into lipoproteins that carry them throughout the body As they are transferred to the body cells lipoprotein shrinks and becomes low density lipoprotein (LDL)

The Art of Nutritional Cooking, 3 rd edition Baskette/Painter © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. 26 Cholesterol: Good or Bad There is only one type of cholesterol When cholesterol is found in food it is neither good nor bad where it is found in the human body determines if it is good or bad

The Art of Nutritional Cooking, 3 rd edition Baskette/Painter © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. 27 Fats Needed for Health Provides energy while excess finds itself stored as body fat Necessary for transporting fat soluble vitamins Necessary for insulating the body against the cold Adds taste and a feeling of fullness

The Art of Nutritional Cooking, 3 rd edition Baskette/Painter © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. 28 Dietary Recommendations Dietary Reference Intakes (DRI) recommend that 20 to 35 percent of calories come from fat in a ratio of about 10 to 1 omega-6 to omega-3 Adequate Intake (AI) for healthy men is: 17 g omega-6 [linoleic acid (LA)] and 1.6 g omega-3 [alpha linolenic acid (ALA)] per day; 12 g LA, and 1.1 g ALA per day for women the Western diet contains a ratio of omega-6 to omega-3 closer to to 1

The Art of Nutritional Cooking, 3 rd edition Baskette/Painter © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. 29 Hydrogenation of Oils The process of adding hydrogen to the double bonds of unsaturated fats by using heat and metal catalysts Changes the cooking and baking qualities margarine, which is partially hydrogenated to allow vegetable oil to gain the spreading consistency of butter shortening where liquid oil is changed into a semisolid giving the product a higher melting point Enhances storage qualities making them last longer on the shelf Causes some health concern

The Art of Nutritional Cooking, 3 rd edition Baskette/Painter © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. 30 The Problem with Hydrogenation The process of hydrogenation forms trans-fats, a byproduct that does not act in the same manner as normal fatty acids, which occur in the cis form if the hydrogen atoms are on the same side of the carbon chain at the double bond, the arrangement is called cis and the fat molecule is bent with the trans-fat the hydrogen molecules are on the opposite side of the double bond and the molecule is straightened out and looks like saturated fat The body perceives the new trans-fat more like saturated fat than unsaturated fat, and thus, it also raises LDL cholesterol levels in the blood

The Art of Nutritional Cooking, 3 rd edition Baskette/Painter © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. 31 Oxidation of Fats Fats may spoil in the presence of oxygen rancidity is the technical term to what happens to fat when oxidation occurs

The Art of Nutritional Cooking, 3 rd edition Baskette/Painter © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. 32 Commercial Fat Replacers Simplese contains 1 to 2 calories per gram compared to 9 calories per gram for regular fat Simplese is made from microparticulated protein and is derived from egg whites or skim milk useful in salad dressings and ice cream inappropriate for cooking Olestra has no calories made with sugar and a chemically altered fat that passes unabsorbed through the digestive system also carries out the fat soluble vitamins A, E, D, and K and enhances their likelihood of excretion ingestion of too much Olestra can cause diarrhea lends itself to frying and is used in potato chip production The brand name Olean on food packaging signifies the product was made with salatrin, a third substitute for fat Salatrin contains 5 calories per gram and is only partially absorbed used in commercial baked goods Z-trim is one of the most recent fat substitute to hit the market

The Art of Nutritional Cooking, 3 rd edition Baskette/Painter © 2009 Pearson Education, Upper Saddle River, NJ All Rights Reserved. 33 END