Lipids II

Question 1

What is a simple triglyceride? Give examples.

Answer 1

• Triglyceride that only has one type of fatty acid attached to the three positions on the glycerol molecule
• ex: tristearin, triolein

Question 2

What are mixed triglycerides? How are the names of the fatty acid?

Answer 2

• More than one type of fatty acids
• Names of fatty acid are run together
• ex: stearodilinolein, dipalmitolinolenin, palmitostearolinolein

Question 3

There are no simple, analytical methods for separating, isolating and identifying individual _________.

Answer 3

triglycerides

Question 4

If you can’t determine the triglyceride composition, what can you quantify?

Answer 4

Determine the overall fatty acid composition of a fat and quantify the relative amounts of the individual fatty acids fairly easily

Question 5

How can you determine the overall fatty acid composition?

Answer 5

Through saponification

Question 6

What are FAMEs?

Answer 6

Fatty acid methyl esters

Question 7

What is GC analysis? What has it demonstrated?

Answer 7

• Gas chromatography

- Demonstrated that each natural fat source tends to have a relatively consistent fatty acid composition

Question 8

Fats from plant and fish sources tend to be ______

Answer 8

Oils

Question 9

What parts of plants are exceptionally good sources of lipids?

Answer 9

Seeds and fruits

Question 10

In plant seeds, what kind of lipids are used as a source of energy for germination?

Answer 10

Triglycerides

Question 11

What are common primary plant sources of edible oils in North America? What are common regional sources?

Answer 11

• Soybean, rapeseed (canola) and peanut

- Olive, coconut, cacao, and palm

Question 12

Lipids are also obtained as by-products from crops, such as what?

Answer 12

Corn and cotton seeds

Question 13

What are non-edible oils obtained from plant sources? What are they used for?

Answer 13

• Castor oil, linseed (flax) oil

- Industrial paint/chemical (plasticizer) purposes

Question 14

How has biotechnology changed linseed oil?

Answer 14

Linseed (flax) oil has been transformed to edible Linola

Question 15

Can oilseeds be consumed?

Answer 15

Yes, can be consumed directly

Question 16

What kind of fats and oils are much more valuable and useful commercially for margarine manufacture, and for the preparation of salad dressings?

Answer 16

Extracted and processed fats and oils

Question 17

How are animal sources of fat obtained?

Answer 17

Fat rendered as a by-product of meat production, produced from the trimmings and the carcasses of cattle, hogs, and sheep

Question 18

How is cream obtained?

Answer 18

• Fat separated from the milk of ruminants, especially cows

- In other parts of the world, other ruminants are important sources of milk fat (water buffalo)

Question 19

What are good sources of fish fat? Where are fish oils used in the world?

Answer 19

• Fatty fish (sardines, herring, menhaden)

- Used extensively in Europe, less so in North America

Question 20

What technique determines the fatty acid composition/distribution? How can its characterization be used?

Answer 20

• Gas chromatography
• Characterizing fats and oils to classify them into various characteristic groups (classifying major sources, has limitations)

Question 21

What are the seven classifications of fats by group characteristics determined by GC?

Answer 21

1) Milkfat
2) Lauric Acid
3) Oleic-linoleic
4) Linolenic
5) Animal fat depot
6) Marine oil
7) Erucic acid

Question 22

What type of fat does the milkfat group contain?

Answer 22

Includes fats from the milk of lactating ruminants (cow, goat, yak, sheep, water buffalo)

Question 23

What are the distinguishing features of the milkfat group?

Answer 23

• High levels of long-chain saturated fatty acids

- Unique and substantial portion of short chain (< C12) fatty acids, butyric acid (C4:0)

Question 24

What kind of lipids are responsible for a bad “rancid-like” odor when released from the triglyceride by lipolysis?

Answer 24

Short-chain fatty acids

Question 25

What is the general fatty acid composition for cows' milk fat?

Answer 25

- 25-32% palmitic acid, C16 - 10-12% stearic acid, C18 - 30-40% oleic acid, C18:1 - 4-15% butyric acid and other short-chain fatty acids (up to C10)

Question 26

Do cows' milk fat contain trans forms of their unsaturated fatty acids? If so, why?

Answer 26

- Yes | - Due to (bio)hydrogenation in the rumen by microorganisms

Question 27

What lipid is responsible in part for the desirable flavour of aged cheese?

Answer 27

Short-chain fatty acids

Question 28

What does biotechnology use to speed up the maturation of cheese and enhance cheese flavour?

Answer 28

Microbial lipases

Question 29

What are the major uses of the milkfat group?

Answer 29

Production of butter (water-in-oil without emulsion) as a spread and as a cooking fat (ghee)

Question 30

How many carbons does the lauric acid group contain?

Answer 30

12

Question 31

What are the sources of the lauric acid group?

Answer 31

- Oil palm (tropical oils) | - Palm kernal oil, coconut and babasu

Question 32

How does palm kernal oil differ from palm oil?

Answer 32

- Palm kernal oil (extracted from palm oilseeds) | - Palm oil (from palm fruit), which is much more highly unsaturated and is not part of the lauric acid group

Question 33

Is palm oil a part of the lauric acid group?

Answer 33

No

Question 34

What are the distinguishing characteristics of the lauric acid group?

Answer 34

- High content of lauric acid (C12) | - Which can account for 40-50% of the total fatty acid content

Question 35

Are most of the fatty acids in lauric acids unsaturated or saturated?

Answer 35

- Most are saturated | - Only small amounts of unsaturated fatty acids are present

Question 36

Are lauric acids solid or liquid at room temperature?

Answer 36

- Although largely saturated | - They are oils owing to the high proportion of C12 fatty acids in their triglycerides

Question 37

What kind of fatty acids are resistant to oxidative rancidity? Which group is an example of this?

Answer 37

- Low degree of unsaturation | - Lauric acid

Question 38

How can lauric acids produce distinct fat and oil fractions?

Answer 38

Can be fractionally crystallized (fractionated)

Question 39

Palm and palm kernal oils are highly valued oils. How are they mostly used?

Answer 39

Oil or fat in baked gods which need a long oxidative shelf life

Question 40

The bulk of our common oils fall into which group? Give examples.

Answer 40

- Oleic-linoleic acid | - Cottonseed, sunflower, safflower, olive, peanut, corn oil

Question 41

Saturated fatty acids make up ______% of the total fatty acid composition in the oleic-linoleic group.

Answer 41

<20%

Question 42

What are the predominant fatty acids in the oleic-inoleic group?

Answer 42

- Long chains - Oleic (C18:1) - Linoleic (C18:2)

Question 43

Oleic-Linoleic acids have negligible amounts of C18:3. What is the consequence?

Answer 43

The oils in this category do not suffer from reversion and are relatively stable

Question 44

How can oleic-linoleic acids be turned into plastic edible fats? Give an example.

Answer 44

Partial hydrogenation (shortenings)

Question 45

What fatty acids do the Linolenic acid group contain?

Answer 45

- Significant linolenic acid - C18:3 - In conjunction with oleic and linoleic acids

Question 46

``` The linolenic acid group is high in: A) Saturated fatty acids B) Trans fatty acids C) Monounsaturated fatty acids D) Polyunsaturated fatty acids ```

Answer 46

Polyunsaturated fatty acids

Question 47

Which group is particularly reactive and readily oxidized?

Answer 47

Linolenic acid

Question 48

Most oils in this group tend to be categorized as industrial "drying oils". Which group does this passage refer to?

Answer 48

Linolenic acid

Question 49

Why are linolenic acids sometimes referred as "drying oils"?

Answer 49

Because of their ability to polymerize into a hard film if applied as a thin layer on surfaces (paint)

Question 50

The polymerization capability is present in all _____________ oils, but those containing high levels of _____________ are more reactive

Answer 50

unsaturated oils, linolenic acid

Question 51

What are common examples of the linolenic acid group?

Answer 51

Soybean, linseed, castor, hempseed and perilla oils

Question 52

What was soybean oil used for originally? What is it used for nowadays? What led to this conversion?

Answer 52

- Originally: industrial drying oil - Nowadays: predominantly as an edible oil - Application of food technology and plant breeding

Question 53

Processed soybean oil, if stored after extraction without modification, suffers from a problem commonly termed _______.

Answer 53

Reversion

Question 54

What is reversion?

Answer 54

Relatively rapid transition from a bland, tasteless oil shortly after processing to a grassy, hay-like and then fishy flavour

Question 55

How is reversion overcome? What fats are converted to what?

Answer 55

By hydrogenation to convert a substantial portion of linolenic to oleic and linoleic acids

Question 56

What fat is an essential omega-3 fatty acid?

Answer 56

Linolenic acid

Question 57

What are the sources of the animal fat depot group?

Answer 57

Lard from pigs, tallow from sheep and cattle

Question 58

What are the characteristics of the animal fat depot group? How is their melting point? How do they compare to oleic-linoleic acids?

Answer 58

- Relatively high melting point | - Yet, contain similar levels of unsaturated fatty acids as the oils in the oleic-linoleic acid group

Question 59

What is the animal fat depot group composed of?

Answer 59

- 50-60% oleic and linoleic acid | - 30-40% palmitic and stearic acid

Question 60

Why are animal fat depot lipids fats rather than oils?

Answer 60

Due to a selective fatty acid distribution on the glycerol backbone which influences the overall physical properties on the lipid

Question 61

Animal fat depot group has a higher ratio of what compared to the oleic-linoleic acid group?

Answer 61

Di-saturated (gs2u) and tri-saturated (gs3) glycerides

Question 62

Compare GS2U and GS3 of beef tallow and peanut oil.

Answer 62

Beef tallow: 12% GS3, 44% GS2U | Peanut oil: 0.1% GS3, 10% GS2U

Question 63

The presence of relatively high amounts of ____ can change the physical characteristics of the lipid system from an oil to a fat.

Answer 63

GS3

Question 64

The fatty acid distribution can have a strong influence on the plasticity and predominance of specific ______ forms in a fat; affecting its funcitonality.

Answer 64

crystal forms

Question 65

What are the sources of the marine oil group? What are they a rich source of?

Answer 65

- Fish oils | - Rich source of omega-3 fatty acids

Question 66

What are the characteristics of the marine oil group?

Answer 66

- Contain low levels of saturated fatty acids | - High in long-chain unsaturated fatty acids (C16-C22)

Question 67

Some fish oil fatty acids can be highly unsaturated. Up to how many double bonds do they contain?

Answer 67

Up to 6 double bonds

Question 68

Why do marine oils possess their own particular processing problems? What do they suffer from? What are they susceptible to?

Answer 68

Due to their very high degree of unsaturation | - Suffer from reversion, and are susceptible to autoxidation

Question 69

How are processed fish oils used in Europe?

Answer 69

Extensively for margarine and shortening production

Question 70

What are two examples of the erucic acid group?

Answer 70

Rapeseed oil and mustard oil

Question 71

How was rapeseed oil used originally?

Answer 71

Used extensively as a marine motor oil

Question 72

Why does the erucic acid group have excellent lubricating properties?

Answer 72

Due to its high erucic (C22:1) acid content

Question 73

Natural rapeseed oil contains __%-__% erucic acid, which is considered a health hazard. Why?

Answer 73

- 40-50% | - Infuses into the heart muscle in rats

Question 74

What is canola oil? How is it produced?

Answer 74

Indigenous rapeseed has been converted by plant breeding to a variety which produces a low erucic acid edible oil

Question 75

Canola oil, which is a low erucic acid edible oil, contains similar properties to which oil?

Answer 75

To oleic-linoleic acid oils

Question 76

What are high-erucic oils being used as now?

Answer 76

Biodegradable lubricants

Question 77

What kind of canola oils can now be produced thanks to genetic engineering?

Answer 77

Lauric acid canola oils

Question 78

How will we custom engineer oils in the future?

Answer 78

- Control fatty acid composition and distribution genetically in plants - To custom engineer oils with properties which are desirable