chapter 11 Flashcards
define lipid
non-polar
water soluble
composed of CHO
define fats
solid at room temp
define oils
lipid at room temp
define triglycerides
composed of glycerol and 3 fatty acids
define glycerol
3 carbon molecules with 3 hydroxyl groups can be esterified
define fatty acids
chain of carbons with characteristics of carbonyl groups
can be esterified to carboxyl group
define short-chain fatty acids
6 carbons or less
medium- chain fatty acids
8-10 carbons
long chain fatty acids
12+ Carbons
define saturated fatty acids
no double bonds (Stearic acid)
define monounsaturated
has 1 double bond (oleic acid)
define polyunsaturated
2 double bonds (linoleic acid)
define non-conjugated PUFA
there is a CH2 group between the double bonds
Define conjugated PUFA
no CH2 group between the double bonds
list the omega 3 fatty acids
- Alpha-linolenic acid
- Eicosapentanoic acid
- Docosahexaenoic acid
list the sources of Omega 6 fatty acids
- Linoleic acid
- gamma- linolenic acid
- arachidonic acid
Describe cis fatty acids
h’s are on same sides of the double bond
Describe trans fatty acids
H’s are on different sides of the double bond
Describe conjugated linoleic acid
has both cis and trans double bonds
melting point
temperature at which the crystals of a solid fat melt
simple fats
contain glycerol and fatty acids
monoglycerides
1 glycerol + 1 fatty acid
diglycerides
1 glycerol +2 fatty acids
triglycerides
1 glycerol +3 fatty acids
Alpha crystals
very fine, extremely unstable, melt quickly, recrystallize into B’ crystals
Beta’ crystals
moderately stable, extremely smooth, *desired form for baking–> fine texture
intermediate crystals
grainy
*NOT RECOMMENDES for baking
can form B’ crystals (melt and recrystallize)
beta crystals
coarsest crystals, extremely stable, formed when fat melts completely and recrystallize WITHOUT being disturbed
fat becomes OPAQUE
oxidative rancidity
degradation of a fat by oxygen in the air (double bonds cleaved in unsaturated fats by free radicals)
oxidative rancidity
degradation of a fat by oxygen in the air (double bonds cleaved in unsaturated fats by free radicals)
hydrolytic rancidity
lipolysis (hydrolysis) of lipids to free fatty acids and glycerol
antioxidants
provide a hydrogen atom to react with a free radical of a fatty acids or with a peroxide that has already formed (MAJOR IMPACT)
lipolysis
hydrolysis
Reversion
oxidation of linoleic acids
Smoke point
temp at which fat or oil will emit smoke 600
acrolein:
compound make from the break down of glycerol when oil is over heated, irritant -sharp offensive odor
polymerization
process in which free fatty acids link together
especially when over heated–> gummy dark residue +oil becomes more viscous and prone to foaming
flash point
temp at which tiny wisps of fire streaj to the surface of a heated substance
fire point
temperature at which a heated substance (oil) burst into flames and burns for at least 5 seconds
which portion of a glycerol molecule can be esterified?
hydroxyl
which portion of a fatty acid attaches to glycerol during esterification?
carboxyl
what is esterification?
the removal of H2O to form a triglyceride
what is lipolysis?
hydrolysis
what is added and removed during these process (esterification)
added: a bond
removal: is a water molecule
know how to name /Interpret the name of a fatty acid using simple chemical short hand
shorthand: Palmitic acid (16:0)
first number is the # of carbons
second # is the number of double bonds
what are 3 characteristics by which fatty acids can vary?
determine the melting point, stability solubility physical properties
- chain length
- presence/ # of double bonds
- cis-trans
• What two types of fatty acids are essential nutrients and why?
Omega 3&6= double bonds before the 9th carbon
What are the food sources of omega-3 and omega-6 fats? (extra credit only 😊)
3: oil fish and flaxseed
6: nuts, wheat germ, oils
How do fatty acid chain shapes vary between cis, trans, and saturated fatty acids?
because it varies depending on the hydrogen location around the double bond (CHEMICAL DIFFERENCES)
What are the general structural characteristics of naturally-occurring fatty acids?
Cis- bent structure at the double bond
What factors increase and decrease melting point?
Increase melting point= longer chain length, saturation (no double bonds), trans double bonds
Decrease melting point= shorter carbon chains, higher degree of unsaturated, Cis double bonds
What types of fats are more likely to be solid vs. liquid? Why?
Fats found as solid and why? Palmitic acid highly saturated
which types of fatty acids/ are not soluble in water?
what is the exception
short/ medium/ long chain fatty acids are not very soluble
Butyric acid is soluble in water
• Do all 3 fatty acids esterified to a glycerol molecule in a triglyceride have to be the same?
yes
what types of fat crystals are most desirable? How are they formed?
Beta’
formed by agitating during cooling
What are the steps involved in oxidative rancidity? what products are formed from oxidative rancidity
Initiation- radical formation
Progression- radicals react and transfer their unpaired electron to other compounds
Termination- 2 radicals combine to stop the reaction
How is oxidative rancidity facilitated or prevented?
facilitated by:
- certain metals
- light
- oxygen
- warm temperature
prevented by:
- proper storage
- antioxidants (major impact)
What can cause hydrolytic rancidity?
high temp
catalysis of lipases
what product is made from hydrolytic rancidity?
free fatty acids and glycerol by water
What is the result of reversion? Which fatty acids does it pertain to?
Produce: fishy or beany smelling oil
Linolenic acid
