Lecture 11: Lipids Flashcards
General uses of lipids
foods soaps candles paints lubricants biofuel
What is the most common form of lipid?
Triglycerides
What is the caloric value of Carbohydrates, proteins and fats?
Carbs: 4 kcal/gram
Proteins: 4 kcal/gram
Fats: 9 kcal/gram
Calorie
Amount of energy it takes to raise water 1 degree C
What does the USDA recommend for fat intake?
Eat less than 35% of total calories from fats and oils (keep it between 20-35% of total calories
Trigycerides
3 fatty acids attached to glycerol
Triglyceride hydrolysis
During digestion we need to hydrolyze the fatty acids off the glycerol
Lipids break down lipases
What is the importance of triglyceride hydrolysis?
Only free fatty acids are absorbed
Vegetable oil
Is triglyceride extracted from a plant
Been used for millennia
Edible oil is extracted primarily from seeds
What is the largest quantity of all vegetable oils
Palm oil
What is the largest in quantity of all edible vegetables oils
Soybean
Mechanical extraction of oil
“crushing” or “pressing”
Solvent extraction
the most common solvent is petroleum-derived hexane
This technique is used for most of the “newer” industrial oils such as soybean and corn oils
How is olive oil made?
After crushing of the fruit, water and oil can also be easily separated by centrifugation
What does virgin mean in virgin olive oil?
“That the oil has been extracted from the olives using purely mechanical means”
What is the difference between Fats and Oils
Fats are (semi)-solid at room temperature Oils are liquid at room temperature
How are fat percentages defined?
Food industry labels fat% by weight and they like to tell you how fat isn’t there
ex: 95% Fat Free means 5% fat
What is the recommended fat % in your daily diet?
<30% (+/-) by calories
What happens to the fat % when we add water?
when diluting a food with water, the % fat by weight will go down
But by diluting with water does not change the % of calories from fat
Simplesse
low fat types made from dairy and egg proteins can be formulated as a powder may have problems with heating 1 calorie vs. 9 calories "dairy protein"
Olestre
low-fat types
chemically bond fatty acids onto sugar molecules
so large, they are indigectible
Saturated acids melting point
high melting points
~65 degree C (fat)
Mono-unsaturated fatty acids melting point
low melting point
~10 degree C (oil)
Poly-unsaturated fatty acids melting point
even lower Melting point
~ -10 degree C (oil)
Triglycerides from plants vs. animals?
Chocolate??
Beef: 50% sat, 50% unsat
Cocoa: 60% sat, 40% unsat
Polymorphism
there are six essential polymorphic forms. The polymorphic transformation theory is based on the fact that bloomed chocolates are always found to contain the most stable VI polymorph of cocoa butter. According to this theory, bloom occurs through the uncontrolled polymorphic transformation of cocoa butter from a less stable form (form IV or V) to the most stable form (form VI)
Cocoa butter forms how many crystals?
6
which is the most stable
Temepering
controlled crystal formation in chocolate
Beta crystals
what allows chocolate to stay solid in our hands
You get to type 5 chocolate by…
heating and cooling
type 5 crystals is the best
What are the roles of fats?
-energy source
-texture
-adipose
-essential fatty acids
Fat soluble vitamins: A, D, E, K
Flavor
heat transfer
fatty acid isomers (trans fat)
Prostaglandins
most common essential fatty acid
Flavor roles of fat
- storage of flavor compounds
- Specific for a product
- without fat there is little flavor
Roles of Fat: Heat transfer
the large molecules do not evaporate
- can be heated to very high tempetures
- frying
Marbling
distribution of fat throughout meat tissue
What meat grade has the greatest amount of marbling
choice
What causes the formation of “chunky butter”
different forms of fat crystals
How many double bonds does a saturated fat have?
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