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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
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