The Lipids

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The Lipids

• Chapter 5

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Fats in Food

• Provide essential fatty acids (EFA)
• Provide concentrated food energy
• Carry fat soluble vitamins
• Provide raw materials for synthesis
• Stimulate appetite, provide satiety

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The Lipids

• There are three classes of lipids
• Triglyceride
• Phospholipid
• Sterol

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1. Triglycerides

• 3 Fatty acids 1 glycerol
• Combined together via a condensation reaction.

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Fatty Acids

• A component part of the triglyceride.
• A chain of Carbon atoms with Hydrogen attached
• Has an Acid Group (COOH) at one end
• Has a Methyl Group (CH3) at the other end
• Found in most lipids in the body and in food.

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Saturated Fatty Acids

• Bonds between the Carbon atoms are single bonds.
• In other words All of the Carbon atoms are
  Saturated with Hydrogen atoms.
• Sources Animal fats. Usually solid at room
  temperature butter, lard, etc.

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Unsaturated Fatty Acids

• Has at least one double bond between carbons.
• Are usually liquid at room temperature.
• Polyunsaturated (many saturated)
• TWO or MORE carbon-carbon double bonds.
• Ex Corn, soybean, safflower oils
• Monounsaturated has ONE carbon-carbon double
  bond
• Ex Canola oil, olive oil

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Essential Fatty Acids

• Must be supplied by the diet.
• Examples
• (alpha-linolenic) Omega-3 fatty acid
• (linolenic) Omega-6 fatty acids
• Important for immune response, vision, cell
  structure, etc.

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Fatty Acids
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Saturation

• Adds firmness-
• Saturated fats are more firm solid at room
  temperature.
• Influences stability-
• polyunsaturated FAs will go rancid (oxidation)
  more readily.

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Saturation Hydrogenation

• Hydrogenation- Saturating a compound by adding
  Hydrogen atoms.
• Conversion of a polyunsaturated oil into solid
  margarine or shortening.
• Prolongs shelf-life, alters texture.
• Produces trans-fatty acids.
• Example Margarine

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Saturation Trans-fatty acids

• Trans-fatty acids-
• A result of hydrogenation.
• A change in shape from the cis form to the
  trans form.
• Behave more like saturated fats in the body
• A diet high in trans-fats has been linked to
  heart disease.

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• Cis fatty acids
• Most commonly found in nature.
• The hydrogens next to the double bonds are on the
  same side of the carbon chain.
• Trans fatty acids
• The hydrogens are on opposite sides of the double
  bonds. This is a result of hydrogenation

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Functions of Triglyceride

• Energy 9kcal/gram
• Main stored from of energy stored in adipose
  cells.
• Protects the organs and insulates the body.

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2. Phospholipids

• Definition A glycerol backbone with one or two
  fatty acids, a phosphate group and a hydroxyl
  group.
• Uniqueness Soluble in fat and dissolves in
  water.
• Ex. Lecithin
• Used as an emulsifier in food.
• What allows the phospholipid to be soluble in
  water? ____________

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3. The Sterols

• Contain a multi-ring structure and a hydroxyl
  group (-OH).
• Are derived from both plants and animals.
• Cholesterol comes from animal sources.
• The group of sterols includes bile acids,
  testosterone, vitamin D, cortisol, etc.

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Digestion of Fat

• Ligual Lipase- released by the salivary glands
  begins fat digestion in the mouth.
• Gastric lipase- hydrolyzes fat in the stomach.
• Bile- released into the small intestine
  emulsifies fat.
• Pancreatic lipase- digests fat in the small
  intestine.

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Absorption of Fat

• Glycerol and short chain fatty acids go directly
  into the circulatory system.
• Larger lipids need help Once in the intestinal
  cell, large lipids are converted to chylomicrons.
• Chylomicrons- lipid packages with protein escorts
  are released into the lymphatic system.
• From the lymphatic system chylomicrons are taken
  all over the body.

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Chylomicron travels via the Lymphatic System
Hydrophilic head
Hydrophobic tail
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Lipoproteins

• Transport vehicles for fat in the lymph and
  blood systems.
• Chylomicrons
• Very Low Density Lipoprotein (VLDL)
• Low Density Lipoprotein (LDL)
• High Density Lipoprotein (HDL)

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Fat Recommended intakes

• 30 or less of your daily calories from total
  fat.
• Diets low in saturated (less than 10 of
  calories) and trans-fats.
• Reduce cholesterol intake (lt300mg/day)
• Consume foods rich in Omega-3 and Omega-6
  fatty-acids 2 times per week.
• Read the food label.

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Fat Replacers

• Simplesse- A texturizing agent made from egg
  protein
• Olestra- sucrose polyester

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Fat Replacer Olestra
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Frito-Lay WOW Chips
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