Chapter 10 Notes Lipids Lipids are organic compounds that are insoluble in water and have a greasy feel There are three types of lipids in foods and the human body 1. Glycerides 2. Phospholipids 3. Sterols

Lipids Lipids have two main parts, a glycerol molecule and a fatty acid Glycerol has three hydroxyl groups that easily react with other compounds Fatty acids are organic molecules that have a carbon chain with a carboxyl group at one end All organic acids have a carboxyl group- COOH

Glycerides Glycerides are molecules that have a glycerol base Monoglyceride- has one fatty acid attached at a hydroxyl group Diglyceride- has two fatty acids attached at a hydroxyl group Triglyceride- has three fatty acids attached at a hydroxyl group, contribute flavor, satiety, and tenderness to food

Glycerides Essential Fatty Acids- These are fatty acids that are not produced by the body Linoleic acid and linolenic acid are the only two essential fatty acids They are found in most plant and fish oils

Phospholipids Phospholipid- A glycerol base with two fatty acids and a phosphorus-containing acid attached. The fatty acids are soluble in fats while the phosphorus-containing acid is soluble in water They help keep foods like mayonnaise from separating

Sterols Sterols- complicated molecules derived or made from lipids Examples include cholesterol, vitamin D, steriods

Saturated vs. Unsaturated Fats Saturated- When fatty acids have the maximum number of hydrogen atoms This means that there are no double bonds in the carbon chain structure Unsaturated- When a fatty acid does not contain all the hydrogen atoms it could contain This means that there is at least one double bond in the carbon chain

Saturated Fats Examples- butyric acid in butter, stearic acid in beef fat, coconut oil, palm kernel oil, palm oil

Unsaturated Fats Monounsaturated- Fatty acids that have one double bond in the carbon chain Examples- olive oil, almonds, walnuts, canola oil, margarine Polyunsaturated- Fatty acids that have two or more double bonds in the carbon chain Examples- Safflower oil, sunflower oil, corn oil

Melting Point and Solidification Point of Fat Melting Point- The temperature at which a lipid is completely liquid Solidification Point- The temperature at which all lipids in a mixture are in a solid state (they have regained their original firmness)

Fats vs. Oils Lipids that are solid at room temperature are called fats Fats at room temperature are usually saturated Lipids that are liquid at room temperature are called oils Oils at room temperature are usually unsaturated

Hydrogenation The process of adding hydrogen atoms to an unsaturated lipid to increase its saturation level This process is used at a commercial level to make some oils into a solid (shortening) at room temperature An example of a product made from hydrogenation is vegetable shortening

Rancidity Rancidity is a form of food spoilage that causes unpleasant flavor and color changes in fats and results from the oxidation of fats Unsaturated oils are more susceptible than saturated fats because their double bonds are weaker than single bonds Antioxidants help prevent rancidity by reacting with oxygen before the lipids do

Functions of Lipids in the Body 1. Lipids are a concentrated source of energy and provide 9 Calories per gram 2. Cell production- Cell walls are made from lipids and proteins. Fatty tissue is deposited around vital organs to help protect them from injury 3.Temperature regulation- Lipids act as insulators and hold in body warmth 4. Transport of vitamins- vitamins that are fat-soluble need to combine with fat to be transported throughout the body