2-FA

Question 1

what is the chemical structure of carboxyl group in fatty acid?

Answer 1

CH3-(CH2)n-COOH

Question 2

aliphatic chain meaning?

Answer 2

FA part of the compound

Question 3

which is the simplest and least reactive FA, SFA or UFA?

Answer 3

SFA. they are unbranched naturally.

Question 4

how many numbers of FA are found naturally?

Answer 4

4-28, even numbers.

Question 5

what are the 2 FA present in milk?

Answer 5

pentadecanoic (15C) and heptadecanoic (17C) FA

Question 6

Rule of melting point of FA vs. number of double bond?

Answer 6

melting point decreases as number of DB increases ( = the more unsaturated the FA, lower the MP)

Question 7

Rule of solubility of FA vs. chain length

Answer 7

shorter the length, bigger and solubility (due to less hydrophobicity)

Question 8

Can FA dissolve in water? any example?

Answer 8

Yes, C4-C8 FA. miscible in water

Question 9

What is soap?

Answer 9

salt form of a FA, water soluble + has strong surface tension reducing properties.

Question 10

What is the name of reaction for FA to become trans from cis?

Answer 10

hydrogenation

Question 11

how does hydrogenation do to oil conversion?

Answer 11

oil becomes plastic fats.

Question 12

which food product naturally contain trans FA? How does this happen?

Answer 12

butter

by rumen microorganisms

Question 13

What does conjugated DB and unconjugated DB mean?

Answer 13

Conjugated DB = DB are right next to each other (happens in oil processing); uncon— DB are seperated by methylene group [natural state of most FA]

Question 14

which is more stable: con and uncon DB?

Answer 14

Conjugated DB is more stable but more susceptible to autoxidation.

Question 15

give an example of FA that contains all unconjugated DB?

Answer 15

Linolenic acid (omega 3)

Question 16

what kind of bond system does linolenic acid has?

Answer 16

mixed bonding system

Question 17

What does mixed bonding system create for the double bond?

Answer 17

It creates active methylene group btw conju and uncon DB.

Question 18

what are advantages and disadvantage of mixed bonding system?

Answer 18

good: is preferred thermodynamically
bad: very susceptible to autoxidation

Question 19

explain Reversion phenomenon; which system is responsible for this?

Answer 19

appearance of bad flavor of soybean + fish oils due to less oxidation than required which produces true rancidity;
this is brought by mixed bonding system

Question 20

The lattice crystalline structure of acyl residues is stabilized by which chemical interaction?

Answer 20

By hydrophobic interactions

Question 21

which structure of FA can be packed into a crystalline lattice?

Answer 21

even-numbered + saturated FA

Question 22

how does melting point change with increasing number of cis DB?

Answer 22

T decreases

Question 23

what is an omega FA? what is the assumption?

Answer 23

omega carbon counted from CH3 end.

assumption: all natural FA are in cis form & DB will be always unconjugated.

Question 24

example of omega FA?

Answer 24

linoleic acid; arachidonic acid (omega 6)

Question 25

which omega 6 FA can't be synthesized by human body?

Answer 25

linoleic acid

Question 26

which omega 3 FA is synthesized only by plants?

Answer 26

gama-linolenic acid

Question 27

which group of FA has anticarcinogenic effects?

Answer 27

conjugated linoleic acid (CLA) | ex. most common Rumenic acid

Question 28

What are food source of CLA?

Answer 28

milk, meat, butter

Question 29

what are branched chain FA?

Answer 29

have a hydrocarbon branch in the chain

Question 30

Which FA is found in cottonseed oil? what is special about this FA?

Answer 30

Malvalic acid. | it contains a cyclopropanic ring ----cause egg color problem

Question 31

Give a food source of Hydroxy acid?

Answer 31

castor bean tree (蓖麻油)

Question 32

Give an example of hydroxy acid.

Answer 32

ricinoleic acid ----and makes up 80% of castor oil.

Question 33

what is acetylenic FA, how is it being used?

Answer 33

contain a triple bond, used as antifungal

Question 34

is there a simple analytical method for separating, isolating and identifying individual TAG?

Answer 34

NO

Question 35

4 steps to determine FA composition of TAG

Answer 35

1. extract 2. saponify (+NaOH) 3. methylate ----convert it to FAME (FA methyl ester) and seperate FAME using GC 4. identify + quantify

Question 36

Give example of plants that produces oil ?

Answer 36

soybean, canola, peanut, olive, coconut, cocao, palm, corn, cottonseed

Question 37

give an example of animal that is important source of milk fat?

Answer 37

water buffalo

Question 38

Which tool is always used to characterize fat and oil?

Answer 38

GC - gas chromatography

Question 39

what are characteristic of milkfat in terms of its chemical structure?

Answer 39

high levels of LCSFA; unique: a lot SCFA (<12C), ex. butyric acid (C<4)

Question 40

Which FA of milkfat is responsible for rancid like odor?

Answer 40

SCFA by lipolysis

Question 41

what good aspect of flavor does SCFA of milkfat has in food?

Answer 41

it is responsible for desirable flavor of aged cheese.

Question 42

is butter water in oil / oil in water emulsion?

Answer 42

water in oil

Question 43

what food is lauric acid (C12) derived from?

Answer 43

Palm

Question 44

what is the difference between palm oil and palm kernel oil?

Answer 44

Palm kernel oil: extracted from palm oilseed; | palm oil: extracted from palm fruit

Question 45

Is palm kernel oil part of the lauric acid group? is it SFA or USFA?

Answer 45

NO, since it is extracted from palm oilseed' | it is USFA

Question 46

Is lauric acid oil / fat in room T with large level of saturation?

Answer 46

Oil. due to C12

Question 47

Is lauric acid susceptible to oxidation?why

Answer 47

No, due to low degree of unsaturation.

Question 48

which group of FA does sottonseed, olive, peanut and corn oil belong to?

Answer 48

oleic-linoleic acid

Question 49

what are the major FA contained in oleic-linoleic acid group? which FA is in low proportion (<20%)?

Answer 49

predominate: long chain: oleic (18:1) + linoleic (18:2) SFA is in low proportion; C18:3 in trace amount

Question 50

is olive, peanut and corn oil relative stable? To which phenomenon?

Answer 50

Yes, they don't suffer from Reversion; and May be turned into plastic edible fats by partial hydrogenation

Question 51

which FA is used in conjunction with oleic and linoleic acid`?

Answer 51

linolenic (C18:3)

Question 52

what are disadvantages of linolenic acid?

Answer 52

reactive + readily oxidized

Question 53

Which group of FA is referred as "drying oils" ?

Answer 53

Linolenic acid. because of their ability to polymerize into a hard film if applied as a thin layer on surfaces

Question 54

which group of FA does soybean, linseed, casto, hempseed and perilla oil belong to? which is used originally an industrial drying oil?

Answer 54

linolenic acid | Soybean.

Question 55

how does Reversion change soybean oil?

Answer 55

rapid transition from a bland, tasteless oil shortly after processing to grassy, hay‐like and then fishy flavor

Question 56

how to overcome Reversion of soybean?

Answer 56

by hydrogenation to convert a substantial portion of linolenic ---->oleic + linoleic acid

Question 57

which animal are lard and tallow from?

Answer 57

lard-pig | tallow-sheep + cattle

Question 58

does animal fat depot group contain high or low melting point?

Answer 58

high.

Question 59

is lard and tallow fat / oil? why ?

Answer 59

they are fat. bc animal fat depot group has a higher ratio of di‐saturated (gs2u) and tri‐saturated (gs3) glycerides than oleic‐linoleic acid group

Question 60

can GS3 or GS2 change lipid system? how does it change?

Answer 60

GS3 | change from an oil to a fat

Question 61

What are characteristics of fish oils？

Answer 61

- Contain low levels of saturated fatty acids | - High in long‐chain unsaturated fatty acids [very high degree of saturation]

Question 62

is marine oil susceptible to autoxidation? why?

Answer 62

yes due to VERY HIGH degree of unsaturation.

Question 63

Give example of erucic acid (C22)?

Answer 63

rapeseed oil 油菜籽; mustard oil 芥末油

Question 64

What is rapeseed oil originally used for?

Answer 64

marine motor oil----excellent lubricating property due to erucic acid.

Question 65

Why rapeseed oil a health hazard? how does it become edible today?

Answer 65

bc 40-50% erucic acid; | it is changed into low erucic acid ----"canola oil"