1

Edible oils

World consumption

Used for cooking in China, hair of sumo wrestler0.2Camellia oil

Common cooking oil also used to make biodiesel.8.6Sunflower seed

Major food oil, often used in industrial food processing.3.6Cottonseed

Accounts for about half of worldwide edible oil production.26.0Soybean

From the seed of the African palm tree2.7Palm Kernel

One of the most widely used cooking oils, Canola is a (trademarked) variety (cultivar) of rapeseed.

13.1Rapeseed

Peanut oil mild-flavoured cooking oil.4.2Peanut

The most widely produced tropical oil. Also used to make

biofuel.

23.3Palm

Used in cooking, cosmetics, soaps and as a fuel for traditional oil lamps

2.5Olive

Notesmio tons Oil source

2

Major oils (I)

Coconut oil cooking oil, high in saturated fat, particularly used in

baking and cosmetics.

Corn oil common cooking oil with little odour or taste.

Cottonseed oil used in manufacturing potato chips and other snack

foods. Very low in E-fats.

Olive oil used in cooking, cosmetics, soaps, and as a fuel for

traditional oil lamps.

Palm oil the most widely produced tropical oil. Also used to make

biofuel.

Peanut oil (Ground nut oil) clear oil used for dressing salads and, due to its

high smoke point, especially used for frying.

These oils account for a significant fraction of world-wide edible oil

production. All are also used as fuel oils.

Major oils (II)

• Rapeseed oil including Canola oil, one of the most widely used cooking oils.

• Safflower oil produced for export for over 50 years, first for use in paint industry, now mostly as cooking oil.

• Sesame oil cold pressed as light cooking oil, hot pressed for a darker and stronger flavour.

• Soybean oil produced as a by-product of processing soy meal.

• Sunflower oil common cooking oil, also used to make biodiesel.

3

Nut oils

• Almond oil used as an edible oil, but primarily in the manufacture of pharmaceuticals.

• Cashew oil somewhat comparable to olive oil. May have value for fighting dental cavities.

• Hazelnut oil mainly used for its flavour. Also used in skin care, because of its slight astringent nature.

• Macadamia oil strongly flavoured, contains no E- fatty acids, and a good balance of ω-3 and ω-6.

Nut oils are generally used in cooking, for their flavour. They are also quite costly, because of the difficulty of extracting the oil.

Nut oils

• Mongongo nut oil (or manketti oil) from the seeds of the Schinziophyton rautanenii, a tree which grows in South Africa. High in vitamin E. Also used in skin care.

• Pecan oil valued as food oil, but requiring fresh pecans for good quality oil.

• Pine nut oil usually added to foods as a flavouring agent.

• Pistachio oil strongly flavoured oil, particularly for use in salads.

• Walnut oilused for its flavour, also used by Renaissance painters in oil paints.

4

Drying oils

• Dammar oil from the Canarium strictum, used in paint as a drying agent. Can also be used as in oil lamps.

• Linseed oil used in paints, also suitable for human consumption.

• Poppyseed oil similar in usage to linseed oil but with better colorstability.

• Stillingia oil (also called Chinese vegetable tallow oil), obtained by solvent from the seeds of Sapium sebiferum. Used as a drying agent in paints and varnishes.

• Tung oil used in wood finishing.

• Vernonia oil is produced from the seeds of the Vernoniagalamensis. It is composed of 73 – 80 % vernolicacid, which can be used to make epoxies for manufacturing adhesives, varnishes and paints, and industrial coatings.

Drying oils are vegetable oils that dry to a hard finish at normal room temperature. Such oils are used as the basis of oil paints, and in other paint and wood finishing applications. In addition to the oils listed here, walnut, sunflower and safflower oil are also considered as drying oils.

Fatty acids

HO

O

HO

O

Stearic acidC18:0

Oleic acidC 18:1 (9)

HO

O

Linoleic acidC 18:2 (9,12)

HO

O

Linoleic acidC 18:3 (9, 12, 15)

5

Dominant fatty acids in foods

Saturated fatty acids

In the group of saturated fatty acids the non branched

lipids with an even number of carbon atoms are

dominating. Being part of the triglycerides the low molecular weight fatty acids (< C 14) can be found only in

milk, coconut and palm kernel fat. The free fatty acids and

esterified with low molecular weight alcohols can be found

in low concentrations in foods that are produced with the

help of microorganisms. They are important as aroma active compounds

61,3Maragic acidHeptadecanoic acidCH3(CH

2)

15COOH17:0

52,1Pentadecanoic acidCH3(CH

2)

13COOH15:0

12,4Pelargonic acidNonaonic acidCH3(CH

2)

7COOH9:0

-7,5Enanthic acidHeptanoic acidCH3(CH

2)

5COOH7:0

-34,5Valeric acidPentanoic acidCH3(CH

2)

3COOH5:0

Odd unbranched fatty acids

87,7Cerotic acidHexacosanoic acidCH3(CH

2)

24COOH26:0

84,2Lignoceric acidTetracosanoic acidCH3(CH

2)

23COOH24:0

80,0Behenic acidDocosanoic acidCH3(CH

2)

20COOH22:0

75,4Arachidic acidEicosanoic acidCH3(CH

2)

18COOH20:0

69,6Stearic acidOctadecanoic acidCH3(CH

2)

16COOH18:0

62,9Palmitic acidHexadecanoic acidCH3(CH

2)

14COOH16:0

54,4Myristic acidTetradecanoic acidCH3(CH

2)

12COOH14:0

44,0Laurinic acidDodecanoic acidCH3(CH

2)

10COOH12:0

31,3Caprinic acidDecanoic acidCH3(CH

2)

8COOH10:0

16Caprylic acidOctanoic acidCH3(CH

2)

6COOH8:0

-3,9Capronic acidHexanoic acidCH3(CH

2)

4COOH6:0

-7,9Butyric acidButanoic acidCH3(CH

2)

2COOH4:0

Even unbranched fatty acids

Melting point

(°C)

Trivial nameIUPACStructureAbbreviation

6

Branched fatty acids

HO

O

HO

O

Pristanoic acid

Phytanoic acid

Unsaturated fatty acids

The unsaturated fatty acids that are dominating the Lipids contain 2 or 3 allylic

groups in the acyl moiety.

Derived from the biosynthetic pathway the position of the double bond (counted

from the methyl end of the fatty acid) is denoted as "ω". From this three families

are derived: ω-3, ω-6, ω-9. Higher molecular weight fatty acids that are derived from these families with structural similarities are e.g. erucic acid (C 22:1) which

occurs only in oils of Brassicaceae, arachidonic acid in meat, liver, lard, and

egg; the lipids of the ω-3 familiy (C 20, C 22; 5 and 5 double bonds) occur in fish.

Linoleic acid cannot be synthesized by the humans. This means that the w-6

fatty acids which are derived biosynthetically in mammals from linoleic acid are

essential since these are used for the formation of lipid membranes. a-Linolenic

acid – which is of the w-3 family – can only be synthesized from plants like

linoleic acid. From the a-linolenic acid the very important DHA and EPA are

formed via elongation and desaturation which have many important

physiological functions.

7

Unsaturated fatty acids (II)

Linoleic acid cannot be synthesized by the humans. This means that the ω-6

fatty acids which are derived biosynthetically in mammals from linoleic acid are

essential since these are used for the formation of lipid membranes. αααα-Linolenicacid – which is of the ω-3 family – can only be synthesized from plants like

linoleic acid. From the αααα-linolenic acid the very important DHA and EPA are formed via elongation and desaturation which have many important physiological

functions.

The group of monoenic acids that are counted normally (∆-9 family) from the carboxylic end comprise palmitoleic acid, and myristoleic acid that are found

in low concentrations in plant and animal foods.

Other unsaturated fatty acids are E-double bonds, and/or conjugated double

bonds. These can be formed during the treatment of oils and fats (heating,

hardening). E-Fatty acids are occurring in sheep and cows.

Unsaturated fatty acids emulgated in water taste bitter with a rather low

threshold value (esp. α-linolenic acid). This means that off-flavours are formed when tasteless triglycerides are enzymatically hydrolysed and

the aroma active fatty acids liberated.

Bitter, disgusting aftertaste6 – 8Arachidonic acid

Bitter, burning, pungent, fresh walnuts0,6 – 1,2α-Linolenic acid

Bitter, burning, pungent3 – 6γ-Linolenic acid

Bitter, burning, raspy11 – 15Linolelaidic acid

Bitter, burning, pungent4 – 6Linoleic acid

Weak burning22Eladidic acid

Bitter, burning, pungent9 – 12Oleic acid

QualityThreshold

(mM)

Fatty acid

8

Rapeseed – CanolaErucic acid

– Docosenic acid (22:1)

– HEAR: high erucic acid rapeseed (30 %)

– LEAR: low erucic acid rapeseed ( < 5 %)

– 5 % as limit

– Can affect heart muscle (derived from test animals)

– Raw material for polymer and photo industry. Can be used for

production of synthetic materials, tensides, surfactants, emulsifyer,

softener, paint and pharmaceuticals.

– Some varieties contain up to 56 %

Melting point of fatty acids

-49,5Arachidonic acid20:4 (5,8,11,14)

75,4Arachidic acid20:0

-11α-Linolenic acid18:3 (9,12,15)

28Linolelaidinic acid18:2 (E9, E12)

-5Linoleic acid18:2 (9,12)

13,4Oleic acid18:1 (9)

51Z-2-Octadecenoic acid18:1 (Z2)

46Elaidic acid18:1 (E9)

69Stearic acid18:0

MP (°C)

9

Configuration of double bonds in fatty acids

COOH

COOH

COOH

Substituted fatty acids

Hydroxy fatty acids

The most well known hydroxy fatty acid is the ricinoleic

acid [12 h-18:1(9)]. It is optically active (D(+)-configuration)

OH

OH O

Ricinoleic acid

10

Oxo fatty acids

Ca. 1 % of the milk fatty acids are saturated (C10 – C24) and unsaturated (C14 – C18) oxo fatty acids with even

carbon number with a carbonyl at position 5 – 13.

H3C (CH2)4 CH CH CH2 CH2 C

O

(CH2)7 COOH

Furan fatty acids

In fish liver oils 1 – 6 % of the fatty acids contain a furan ring (in some freshwater fish up to 25 %). Furan fatty acids can also occur in

• some plant oils and in butter• fruits (lemon, strawberry)• vegetables (cabbage, potatoes)

• mushrooms (champignon).

CH3 (CH2)4 (CH2)n COOH

CH3H3C

I: n = 8; II n = 10

11

Furan fatty acids (I and II) in plant oils

24 – 20813 – 139Butter

9 – 138 – 11Corn oil

7 – 206 – 16Rapeseed oil

105 – 150100 – 130Wheat germ oil

130 – 230120 – 170Soy oil

III

Concentration (mg/kg)oil

First chain initiation

-CH2- + OH° → -C°H- + H2O

-CH2- + HO2° → -C°H- + H2O2

Only from e.g. linolenic acid

12

Reaction of conjugated dienes

• >CH° +O2 → >CHO2°

• >CHO2° + >CH2 → >CHO2H + >CH°

• R-C°H-R´ + R-C°H-R´´ → R-CHR´-CHR´´-R

Chain breaking reactions

Autocatalyticfatty acidoxidation

fatty acid with 3 double bonds

-H° (hydrogen abstraction)

molecular rearrangement

O

O

H

O

O

H

conjugated diene withUV absorbance at 234 nm

Peroxy radical: abstracts H° from another fatty acid causing an autocatalytic chain reaction

lipid hydroperoxide

cyclic peroxides

cyclic endoperoxides

fragmentation to aldehydes(incl. malondialedhyde)& polymerization products

13

Rates of autoxidation of unsaturated fatty acids

4.00.080501.991 × 3Trilinolein

5.10.102522:6

2.90.0581957.78320:4

2.10.041983.90218:3

10.020411.63118:2

10.04018:1

Rel.

rates

Oxidizability

M-1/2sec-1/2

Rel.

Rates

Mole O2

per 100 h

Number of

=CH-CH2-CH=

Fatty

esters

Autoxidation of oleic acid

14

Dissociation energy of hydroperoxides

(CH3)3C O OH

(CH3)3C O O C(CH3)3

C

O

O O C

O

HO OH 213 kJ/mol

180 kJ/mol

150 kJ/mol

139 kJ/mol

(resonance stabilization; used aspolymerization katalyst)

Hydroperoxides from autoxidation of methyl oleate

EZEZEZEZ

24.919.55.424.922.02.925.122.52.725.119.06.175

25.717.48.323.521.32.224.722.52.226.117.88.350

26.416.010.123.421.71.723.622.01.626.616.010.640

29.016.013.022.021.01.022.021.01.029.016.013.030

26.612.913.722.821.71.124.223.11.126.412.314.125

11-OOH10-OOH9-OOH8-OOHTemp

°C

15

Mechanism of

linoleate

autoxidation

(I)

HH

9

12

O2O2

-H°

HOO9

11

OOH1012

+

+H° +H°

Hydroperoxides from autoxidation of methyl linoleate

Total

9-OOH

Total

13-OOH

9-OOH

E,E

9-OOH

Z,E

13-OOH

E,E

13-OOH

Z,E

47.952.130.417.533.518.665

52.547.629.622.928.019.550

48.951.219.229.720.131.025

Temp

°C

HOO9

11

HOO

13

OOH1012

OOH9

16

Mechanism of linoleate autoxidation (II)

HH

9

12

-H°

°OO

OO°

O2 O2O2O2

OO° OO°

°OO

OO°

OO° OO°

+ + ++

Oxidation of cholesterol

HO

H H

H

7

25

25-Hydroperoxy-Cholesterol

Initiator-H°

HO7

HO

3O2

H

OO°+ RH

HO H

OOH

7β-Hydroperoxy-Cholesterol

HO OOH

H

7α-Hydroperoxy-Cholesterol

17

Thermal decomposition of allylichydroperoxides to carbonylproducts (Hock cleavage)

C CH

OOH

1 2 3

C CO

C

C CO

C

+

+

H2O

CO

3

CH C

O

1 2

+

Oxidation products of fatty acids

• hydroperoxy epidioxides

• malondialdehyde

Liolenate

• keto-linoleates (with CO on carbons 9 and 13)

• epoxyhydroxy-oleates

• di- and trihydroxy stearates

Linoleate

Small amounts of

• allylic keto-oleates (with CO on carbons 8, 9, 10, and

11)

• epoxy-stearates or epoxy-oleates (8,9-, 9,10-, 10,11-

epoxy)

• dihydroxy-oleates (8,9-, 9,10-, 10,11-diOH)

• dihydroxy-stearates (between 9 and 11)

Oleate

18

Formation of malondialdehyde from hydroperoxy epidioxides and bicyclo-

endoperoxides of methyl linoleate

OO

OO OOH

+O2 LH

H°

OO

Malonaldehyde

Hydroxyperoxy EpidioxidesBicycloendoperoxides

OOH

O

O

+O2LH

H°