Lipids: Also called Fats and Oils

Lipid Facts

•  Fat:  Solid at room temperature
• Oil:  Liquid at room temperature
• Contribute 30-50% of calories for Americans
• Soluble in organic solvents, i.e., not soluble in water
• Lipids are primarily consumed for energy

• Triglycerides - most prevalent
• Glycerol + 3 fatty acids
• Monoglyceride
• Glycerol + 1 F.A.
• Diglyceride
• Glycerol + 2 F.A.

Fatty Acid Classification
(Nomenclature)

• Based on:

• Number of carbons
• 4C butyric acid
• 16C palmitic acid
• 18C stearic acid
 
        
         Stearic Acid
 
• Number of double bonds
• Saturated
• Unsaturated

• Saturated
• No double bonds
• Solid at room temperature
• Implicated in coronary heart disease (CHD)
• Meats, dairy, tropical
• Unsaturated
• Has double bonds
• Fluid at room temperature
• Less stable to off flavor development
• Vegetables, legumes, fish

• 18:1 Oleic Acid
• 18:2 Linoleic Acid  *Essential
• 18:3 Linolenic Acid  *Essential
• 20:4 Arachidonic Acid *Essential
 
        
        Oleic Acid with the Hydrogens shown
 
        
        Oleic Acid showing bonds between Carbons (numbers)
 

• Polyunsaturated:  2-5 double bonds
• Highly Unsaturated:  >5 double bonds
• Omega 3 Fatty Acids
• Good for reducing CHD
• High in fish
 
      
      Linolenic Acid, an Omega 3 Fatty Acid

•  Definition:  Off flavors and odors from breakdown of fats
• Two types
• Hydrolytic - enzymatic
• Resulting in short chain fatty acids (Lipase - butter)
• Control:  Heat Deactivation, handling and storage
• Oxidative - addition of oxygen to fat
• Resulting in small chain compounds
• Factors
• Unsaturation
• Heat
• Light
• Metals

• Additives
• BHA
• BHT
• Hydrogenation
• Remove unsaturation
• Control functionality (shortening)
• CIS vs. TRANS fatty acids
 
        

• Contain additional elements besides C, H, O

• Phospholipid:  contains phosphorous (P)
• Lecithin - important phospholipid
• Found in eggs and soybeans
• Functions in foods
• Emulsifiers
• Releasing agent (PAM)
 
        

• Waxes:  Combination of long chain fatty acids and long chain alcohols
• Used for protective, texture, and appearance purposes
• Not digestible
• Sterols
• Important sterol:  cholesterol
• Get 400 to 700 mg from diet
• Body produces 2-3 times as much
 
     

      Cholesterol structure

• Why is cholesterol important in the body?
• Hormone production
• Membranes
• Vitamin D
• Absorption of fats
• Foods high in cholesterol
• Organ meats
• Eggs
• Shellfish
 
        

• Flavor
• Fried Foods
• Popcorn
• Texture
• Shortening (Flakiness)
• Moistness
• Stabilizers (emulfsifiers)
• Lecithin
• Mono and diglycerides
• Process Additives
• Release agent

• CHD is No. 1 killer of Americans
• Approximately1 million deaths/year
• General Agreement
• Cholesterol and tryglycerides build up in arteries and reduce blood flow to heart.
• Hypothesis
• Reduce cholesterol and fat in diet and reduce CHD
 
        
 

Issues w/ Fat and CHD

•  Cholesterol not only Factor in CHD
• Heredity
• Stress
• Smoking
• Saturated fat and high blood cholesterol correlation questioned
• HDL vs. LDL rationale
• Not all saturated fats may raise blood cholesterol levels
• Trans-Fatty Acids

Industry Response

• Initially discounted research as inconclusive
• Industry now has created new “lowfat” products
• New evidence
• Consumer demand

Fat Substitutes

• Why are fat substitutes important?
• Weight loss
• 4 cal/g vs. 8-9 cal/g
• Medical concerns
• CHD
• Colon cancer
• NOTE:  Customers are willing to pay a premium for these products!

Issues when Replacing Fats

•  Functional Properties (see fat uses in foods notes)
• Nutritional Properties
• Essential Fatty Acids
• Energy Source
• Fat Soluble Vitamins
• Two classes of fat replacers
• Structural analogues of fats and oils
• Biopolymers

• Theory:  Produce fat-like substance that has reduced metabolism
• Examples
• Olestra - sucrose polymer
• Expected for use in all types of foods
• Issues:  Anal leakage and vitamin loss
 
        
 
• Caprenin - glycerol w/ C:8, C:10, and C:22 FA’s, 5 cal/g
• Approval in Milky Way II as cocoa butter sub.

• Theory:  Use substance that cannot be broken down or, if broken down, has fewer calories
• Binding of water to produce the mouthfeel of fat
• Protein based
• Simplesse - small whey protein particles.
• Can be used in many heat processes, but not deep fat frying
• Trailblazer - like Simplesse
• Carbohydrate based:  most widely used
• Stellar -Crystalline starch
• 1 cal/g
• Polydextrose - Polymer of dextrose that is an excellent bulking agent
• Gums
• Maltodextrins - Processed from hydrolysis of starch.

• EXPERTS SAY...
• Lower fat intake to 30% of daily calories
• Consume “proper amount” of fatty acids in diet
• Have approximately 1:1.5:1 ratio of saturated, monounsaturated and polyunsaturated fats
• Dietary fiber may be of some benefit
• Some suggest increase intake of Omega 3 Fatty Acids
• May reduce blood cholesterol