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