Fatty acids Flashcards
T or F : Fatty acids are not generally found in their free form in living biological systems
T
T or F : C4-C8 fatty acids are slightly miscible with water
T
What is the structure of a soap (salt form of a fatty acid)
T or F : Branched FA with odd number of carbon atoms are not very common in food
T
How many carbon is there is butyric acid?
4
How many carbon is there is stearic acid?
18
How many carbon is there is palmitic acid?
16
What is the systematic name of butyric acic?
Butanoic acid
What is the systematic name of lauric acic?
dodecanoic acid
What is the systematic name of mystiric acic?
Tetradecanoic acid
What is the systematic name of palmitic acic?
hexadecanoic acid
What is the systematic name of stearic acic?
octadecanoic acid
What is the systematic name of palmitic acic?
hexadecanoic acid
What is the systematic name of arachidonic acic?
eicosanoic acid
What would be the systematic naming of :
C18:1
C18:2
C18:3
C18:1 : octadecenoic acid
C18:2 : octadecadienoic acid
C18:3 : octadecatrienoic acid
T or F: linolenic acid is different than octadecatrienoic acid
F, naming is different but it is the same FA if the double bonds are at 9,12,15
What does the number represent in the parentheses of the shorthand system –> C18:2(9,12)
the position of the double bonds.
all-cis-docosa-4,7,10,13,16,19-hexa-enoic acid is a FA that contains:
A. 26 Carbon atoms with six cis double bounds B. 22 Carbon atoms with six cis double bounds C. 26 Carbon atoms with six trans double bounds
B
What is the common name of trans-oleic acid
elaidic acid
The melting point of fatty acids is affected by:
A. The chain length
B. The number of double bonds
C. The double bond configuration, cis or trans
D. All of the above
E. None of the above
All of the above
What is the shorthand name of linoleic acid?
C18:2(cis9-cis12)
T or F : CLA is a positional isomers of linoleic acid
True, it si the conjugated linoleic acid
What is the difference between a positional and geometric isomer
What is a conjugated FA?
At least one double bond alternate with single bonds C=C-C=C
What are conjugated FA?
FA in which the double bond are separated by a methly group C=C-CH2-C=C
What is a mixed bonding system?
The mixed bonding system leads to formation of an ACTIVE METHYLENE group (*), which is positioned between a conjugated and unconjugated double bonds
What is reversion?
phenomenon associated with soybean and fish oils, which is defined as the appearance of objectionable flavor from less oxidation than is required to produce true rancidity
What is the bonding configuration responsible for the reversion phenomenon?
Mixed bonding system
Long chained polyunsaturated cis fatty acids:
A. Give better packed, more stable crystalline lattice that requires high temperature to melt
B. Give less stable crystalline lattice than their trans isomers thus the melting point is less C. Have no effect on the stability of the crystalline lattice
B
Oleic acid 18:1 cis-9 is considered:
A. n3 fatty acid
B. n6 fatty acid
C. n9 fatty acid
D. Not an omega acid
C
What are acetylenic fatty acids
less common type of fatty acid with a tipple bond
Octadeca 9,12,15-trienoic acid is a fatty acid with:
A. 18 C atoms and 3 double bonds
B. 9 C atoms with 3 double bonds
C. 18 C atoms with no double bonds
A
Double bonds that are next to each other and not interrupted by a methylene (CH2) group are called:
Conjugated
When the first double bound is located on the third C atom starting the count from the CH3 end, this fatty acid is labelled as:
omega-3
T or F : Cis-to-trans conversion is often the main mechanism for oils becoming plastic fats during hydrogenation, rather than the desired reduction in the degree of unsaturation
T
Complete : The cis‐configuration in oleic acid causes a bending of about ____
40˚
T or F : the odd number carbon chains will have a lower melting point
true – > Odd‐numbered as well as unsaturated fatty acids cannot be uniformly packed into a crystalline lattice as can the saturated and even‐numbered
T or F : The molecular arrangement in the crystalline lattice of unsaturated fatty acids is not strongly influenced by trans double bonds
True because the trans double bonds doesn’t create a kink in the structure
T or F : The omega nomenclature system is based on the assumption that all natural fatty acids are in the cis form and the double bonds will be always be unconjugated
True
What is the most common CLA
rumeric acid (C18:2)
Which one would have a lower melting point : oleic or omega-9?
omega-9 because it is automatically cis and oleic might be a trans because it is not specified
Which one has a lower melting point, the omega-6 or omega-3 family?
omega-3 because it means that more double bonds since the first one is at carbon 3 from the methyl end
Which one has a lower melting point : gamma-linoleic or linoleic
gamma linoleic (C18:3) has a lower melting point than linoleic (C18:2)
True or False : linoleic systematic name means that there is always 2 doubles bonds.
false, the gamma-linoleic has 3. linoleic means it will be 18 carbons but doesn’t specifiy the number of double bonds. However, the most common one is C18:2(9,12)
Which one has the highest melting point : elaidic or stearic
elaidic (C18:1 (tr9)) has a lower melting point than stearic (C18:0)
Which one would have a lower melting point : oleic acid or cis-2-octadecenoic aicd
oleic acid since it is C18:1(9) and the cis-2-octadecenoic acid double bond is at the end of the chain.
