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 groupCOOH
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 fatsoluble need to combine with fat to be
transported throughout the body