Fundamentals of Oils & Fats by Albert J. Dijkstra, PhD

Ignace Debruyne, PhD ignace.debruyne@gmail.com Fundamentals of Edible Oil Processing and Refining Saturday, May 3, 2014

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Topics to be discussed Composition of oils and fats

Triglycerides, fatty acids, phosphatides, tocopherols, tocotrienols, phytosterols, coloring compounds

Properties of oils and fats Physical, melting point Chemical, oxidation

Sources of oils and fats Processing of oils and fats: Refining/modifying

Degumming, neutralization, bleaching, deodorization Hydrogenation, interesterification, fractionation

Composition of oils and fats Saponifiable fraction: around 98% : reacts with alkali under

formation of soaps (alkali salts of FA) Triglycerides: esters of glycerol with 3 fatty acids (FA) Mono- and diglycerides (partial glycerides) Free fatty acids (FFA) Waxes: esters of fatty acids with fatty alcohols Phospholipids (phosphatides, sphingomyelins) Glycolipids Sterol esters

Unsaponifiable fraction: around 2% : Tocopherols Free (non-esterified) sterols Hydrocarbons, carotenoïds, squalene, chlorophyll Vitamins Polyphenols: in olive oil Oxidation products

3

CH2 O C

O

R1

HC

CH2

O

O

C

C

O

O

R2

R3

Nutritional aspects Source of energy (9 kcal/g or 37 kJ/g) Source of essential fatty acids (ω-3, ω-6) Fat soluble vitamins (A, D, E) Functional minor components:

tocopherols, sterols oryzanol (rice bran oil) polyphenols (olive oil)

Sensorial and rheological appreciation Just imagine a salad without dressing or mayonnaise,

fried food without frying taste, chocolate with no ‘bite’

Quality aspects Gourmet oils are appreciated for their

characteristic taste, smell and colour Olive oil, walnut oil, pumpkin seed oil, etc

Refined oils should have: Bland taste: deodorization Low acidity: neutralization Low color: bleaching and thermal breakdown of

coloring compounds during deodorization Transparency: filtration Low cloud point: winterization / dewaxing

Structure of fatty acids Linoleic acid (C18:2)

CO

OH

912

118

For nearly all naturally occurring fatty acids holds: Straight chains with Even number of carbon atoms Unsaturation has cis-configuration Methylene interruption in polyunsaturated fatty acids Elongation at carboxyl end so position of double bond does not

shift with respect to methyl end (ω-6 remains ω-6)

Allylic and bis-allylic methylene

Allylic CH2 positions ↓ ↓ HOOC-(CH2)x-CH2-CH=CH-CH2-CH=CH-CH2-(CH2)y-CH3 ↑ bis–allylic CH2 position

Nomenclature Special fatty acids CH3-CH2-CH=CH-CH2-CH=CH-CH2-CH=CH-(CH2)7-COOH

Systematic name 9,12,15-octadecatrienoic acid Trivial name α-linolenic acid First shorthand C18:3 9c,12c,15c or c9,c12,c15-18:3 Second shorthand C18:3 ω3 or C18:3 n-3

γ-linolenic acid: C18:3 ω6 Occurs in black current seed and evening primrose Precursor of arachidonic acid C20:4 ω6

Stearidonic acid:C18:4 ω3 Precursor of EPA (C20:5 ω3) Now available through SDA soy (biotech product), echium oil

Nomenclature of fatty acids Systematic name Trivial name Notation Octanoic Caprylic (PK, CN) 8:0 Decanoic Capric (PK, CN) 10:0 Dodecanoic Lauric (PK, CN) 12:0 Tetradecanoic Myristic (PK, CN) 14:0 Hexadecanoic Palmitic (PO, PK, CN) 16:0 Octadecanoic Stearic (PO, PK, CN) 18:0 9-cis-octadecenoic acid Oleic (PO, PK, CN) 18:1ω9 9-trans-octadecenoic acid Elaidic (hydrogenation) 18:1ω9 9c-12c-octadecadienoic Linoleic (PO, PK, CN) 18:2ω6 6c-9c-12c-octadecatrienoic γ-Llinolenic 18:3ω6 5c-8c-11c-14c-eicosatetraenoic Arachidonic (meat) 20:4ω6 9c-12c-15c-octadecatrienoic α-Linolenic (soy, rape) 18:3ω3 6c-9c-12c-15c-octadecatetraenoic Stearidonic (soy) 18:4ω3 5c-8c-11c-14c-17c-eicosapentaenoic EPA (fish oil) 20:5ω3 4c-7c-10c-13c-16c-19c-docosahexaenoic DHA (fish oil) 22:6ω3

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Fatty acid composition of various oils

oil 8:0 10:0 12:0 14:0 16:0 18:0 18:1 18:2 18:3 22:1 coconut oil 9.0 6.8 46.6 18.0 9.0 1.0 7.6 1.6 palm kernel oil 2.7 6.0 46.9 14.1 8.8 1.3 18.5 0.7 palm oil 0.2 1.1 44.1 4.4 39.0 10.6 0.3 palm superolein 0.3 1.0 35.4 3.8 45.1 13.4 0.3 palm stearin 0.1 1.1 49.3 4.9 34.5 9.0 0.2 cocoa butter 26.2 34.4 37.3 2.1 olive oil 12.6 2.9 74.6 8.4 0.7 soybean oil 11.0 4.0 23.4 53.2 7.8 rapeseed oil 3.6 1.6 32.9 17.5 9.0 42.4 canola oil 4.8 2.4 58.1 20.8 10.2 sunflower seed oil 6.4 4.7 21.0 67.7 linseed oil 6.0 2.5 19.0 24.1 47.4

N.B. Totals ≤ 100% because minor fatty acids have not been listed

Fatty acid distribution in the triglycerides Vegetable oils (mostly 1,3-random, 2-random)

C16:0 and C18:0 mainly on 1,3-positions Lauric acid has some preference for 2-position Linoleic acid has preference for 2-position Oleic acid fills in vacancies

For cocoa butter this is mainly the 2-position

Animal fats (1-position differs from 3 position) Palmitic acid has preference for 2-position Stearic acid has some preference for 1-position Unsaturated acids on outer, especially 3-position

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Examples of fatty acid distributions Oil pos 12:0 14:0 16:0 16:1 18:0 18:1 18:2 18:3 Palm oil 1,3 62.0 8.0 27.5 2.5 2 11.0 2.0 65.0 22.0 Palm kernel 1,3 47.8 16.4 9.9 3.2 7.9 1.2 2 62.7 15.8 2.9 0.3 11.8 1.3 Coconut oil 1.3 34.8 21.8 10.6 2.7 5.3 1.2 2 80.4 8.6 1.6 0.6 3.5 1.5 Soya bean 1,3 17.7 6.8 21.2 46.1 7.0 2 0.3 0.0 25.1 71.0 6.7 Lard 1 0.7 9.8 1.7 38.8 42.7 6.3 2 3.5 72.4 3.7 3.8 14.0 2.9 3 0.6 5.4 2.1 11.3 65.4 15.2

Sources of oils and fats Animal oils and fats

Lard (porc); tallow (beef and mutton) Butter (oil) Fish oil

Vegetable oils and fats Fruit oils: olive oil, palm oil Seed oils: soybean, rapeseed/canola, sunflower seed ,

cottonseed, palmitic and coconut (lauric oils), …

Specialty oils and fats, incl. gourmet oils Technical applications: e.g. castor oil, jatropha oil Confectionery fats: cocoa, shea, illipe butter Niche products: nut oils, grape seed oil, avocado oil ….. Novel oils: algae oils, microbial oils (in future?) 13

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Production vegetable oil (MT) Seven oil seeds 2008/09 2009/10 2010/11 2011/12

total 396.7 444.1 455.7 441.4

Soybean 211.6 260.2 263.6 238.7

Other 185.1 183.9 192.1 202.7

Nine plant oils Total 133.4 140.8 147.8 155.7

Palm oil 44.0 45.9 47.9 50.7

Soybean oil 35.9 38.8 41.3 42.4

Rapeseed/canola oil 20.6 22.5 23.7 24.3

Sunflower seed oil 11.9 12.1 12.3 15.3

Lauric oils 8.7 9.1 9.4 9.5

Other (CS,GN,OO) 12.3 13.3 13.2 13.5

Sole product, co-product, or by-product Sole product and major source of income (by-products

are not important or even useless) Palm oil, olive oil, sunflower seed oil, rapeseed oil, castor oil,

jatropha oil, wild fats, nut oils Microbial oils?

Co-product (important by-product) Soybean oil is the co-product of soybean meal Palm kernel oil is co-product of palm oil

By-product in true sense, i.e. raw material is harvested or farmed/grown for other reasons Animal fats, fish oil Cotton seed oil, corn germ and grape seed oil

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Chemical structure of phosphatides

C R1

OH2C

CHO

CR2 H2C O P O X

O

HOH2C

H2C N

CH3

CH3

CH3choline

HOH2C

H2C NH2

ethanolamine

OOH

OH

OHOH

OH

inositol, link in 1-position

X = choline (phosphatidyl choline or PC)

X = ethanolamine (phosphatidyl ethanolamine, PE)

X = inositol (phosphatidyl inositol or PI)

X = hydrogen (phosphatidic acid or PA)

O

O

O

D

A1

A2

C

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Chemical structure of tocopherols

O

R1

HO

R2

R3

CH3 CH3 CH3

CH3CH31

2

56 43

7 8 4' 8'

Trivial name R1 R2 R3 α-tocopherol CH3 CH3 CH3 β-tocopherol CH3 H CH3 γ-tocopherol H CH3 CH3 δ-tocopherol H H CH3

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Chemical structure of tocotrienols

O

R1

HO

R2

R3

CH3 CH3 CH3

CH3CH3

Tocopherols occur in vegetable oils (α-tocopherol is vitamin E); soybean oil (900 ppm), corn germ oil (1100 ppm), sesame seed oil (2900 ppm)

Tocotrienols occur mainly in palm oil (530 ppm), rice bran oil (580 ppm) and wheat bran (650 ppm)

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Occurrence of tocols (ppm)

Oil tocopherol tocotrienol

α β γ δ α β

Palm 256 - 316 70 146 3

Rapeseed 210 1 42 - - -

Soybean oil 75 15 797 266 2 -

Sunflower oil 487 - 51 8 - -

Walnut oil 563 - 595 450 - -

Wheatgerm oil 1330 71 260 271 26 18

Chemical structure of plant sterols

Shown is β-sitosterol Other plant sterols

(campesterol, stigmasterol, brassica-sterol, Δ5-avena-sterol, etc) differ with respect to side chains, number and position of double bonds

The free hydroxyl group can be esterified with a fatty acid or ferulic acid, or form an ether with glucose

CH3

CH3

HO

CH3

CH3

CH3

CH3

3 5

1718

19

21

24

26

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Free and esterified phytosterols

0 200 400 600 800 1000

Rapeseed (refined)

Rapeseed (crude)

Corn (refined)

Corn oil (crude)

Frituur (sunflower)

Sunflower (refined)

Cotton (crude)

Cotton (refined)

Soya (refined)

Peanut (refined)

Olive oil (cold pressed)

soybean (crude)

Walnut (refined)

Palm oil (refined)

Olive oil (cold pressed)

Coconut (crude)

Palm oil (crude)

Red palm olein (crude)

sterol content (mg/100g) esterified free

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Chemical structure of (poly)phenols

HO

HO

HOOH

OHO

HOOH

OO

HO

H3C

OH

O

HO OH

O

HO OH

OHO

coumaric acid

gallic acid protocatechuic acid ferulic acid

caffeic acid

HO

HOOH

hydroxytyrosol

Source: fruits, berry seed oil β-carotene Nutritional role: radical scavenger; antioxidant Application: adjuvant in bakery ingredients; additive to oils

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Chemical structure of coloring compounds

CH3 CH3

CH3 CH3CH3

H3CH3C CH3

H3C CH3

NN

N N

CH3

OCH3

O

H2C

H3C

CH3

O

H3C

CHO

OO

CH3

CH3 CH3 CH3 CH3

Mg

ß-carotene

chlorophyll b

Melting points of fatty acids The melting point increases with the number of

carbon atoms in the chain It decreases with the number of double bonds Fatty acids with trans double bonds have a

higher melting point than their cis-isomers In polyunsaturated fatty acids, conjugated

double bonds lead to a higher melting point than the common, methylene interrupted double bond systems

Melting points of triglycerides Substituting a fatty acid in a triglyceride

by a higher melting one raises its melting point

Triglyceride melting points also depend on positional isomerism

Triglycerides exhibit polymorphism and different polymorphs exhibit different melting points

Solubility of lipids Oils and fats are miscible with alkanes, ethers

and ketones n-hexane is common extraction solvent

They dissolve in hot isopropanol but not in cold Isopropanol extraction process cools the miscella

Oils and fats are insoluble in water Soaps are water-soluble Washing oil with water to remove soaps

Phosphatides are not soluble in acetone Lecithin de-oiling by extracting the oil with acetone

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Reactions during storage and processing Hydrolysis

Chemical: catalyzed by alkali and acid; rate depends on temperature, extent, and time

Enzymatic: in presence of lipases (e.g. In palm oil, rice bran oil)

Oxidation Isomerisation of double bonds

Cis/trans isomerisation

CH2 CH2 CH2

CH2

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Reactions (2) Conjugation

The reaction rates of both reactions Increase with an increase in temperature Are affected by catalysts (alkali, bleaching earth)

Linolenic acid is more reactive than linoleic acid Two bis-allylic methylene groups versus only one

Linoleic acid is much more reactive than oleic acid One bis-allylic methylene group versus none

CH2

CH2

H2C CH2

CH

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Reactions (3) Dimerization and polymerization

Promoted by high temperature (deep fat frying) Oxidation and ring opening of tocopherols Dehydration of sterols forming steradienes Condensation of sterols forming di-steryl ethers

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Edible oil processing flow sheet

Preparation Extraction Seed

Refining Bleaching Neutralising

Deodorising

Modification Winterising

Hydrogenation

Interesterification

Fractionation

Salad / Frying oil

Shortening Margarine

Cracking Dehulling Flaking

Mechanical Extraction

Solvent Extraction

Degumming

( Post - refining )

Cleaning / Drying

Meal

Oil

Edible Oil

CRUDE OIL

WATER DEGUMMING or

ENZYMATIC PLC DEGUMMING

ALKALI REFINING

ACID DEGUMMING

SOFT DEGUMMING

ACID REFINING or

ACID REFINING PLUS ENZYMATIC PLA OR

LAT DEGUMMING

BLEACHING

BLEACHING

DRY

DEGUMMING

DEODORISING

FULLY REFINED OIL

PHYSICAL REFINING

Chemical vs. physical refining Chemical refining

Advantages Can process poor quality oil

Disadvantages Lower yield for high acidity oils Effluent problems with soapstock splitting

Physical refining Advantages

Better oil yield Close to zero effluent Eliminates one process step

Disadvantages Gum disposal in stand-alone refineries

Physical refining requirements Wet degumming of vegetable oils Dry degumming of low phosphatide oils (palm oil, lauric

oils, animal fats) with simultaneous bleaching Palm oil has high carotene content and low phosphatide

Therefore, dry degumming is preferred option Treatment with degumming acid followed by bleaching earth

This permits physical refining Two-step process: dry degumming followed by steam

refining Yield advantage over chemical refining No soapstock treatment or effluent disposal problems

Refining steps Degumming and alkali refining

Review of degumming and refining technologies Process automation and remote condition monitoring for

centrifuges and plant

Bleaching Basics and practical optimization Adsorbent solutions for oil and fat processing Highly activated bleaching clays for oil purification Latest developments in filtration Staggered Trisyl® Silica Tri-clear process

Hydrogenation Catalysts for hydrogenation of oils and fats

Refining/modification steps Interesterification

Chemical and Lipozyme TL IM Enzymatic Interesterification How Enzyme Solutions Improved Process Yield and Final

Product Qualities

Vacuum stripping Optimizing continuous deodorization Deodorizer design and optimization

Various Mechanism of oxidation Waste water treatment Recent developments

Purpose of modification processes Change in physical properties

From oil to solid fat by hydrogenation Lowering of melting point by interesterification Lowering cloud point by fractionation

Increase shelf life Lowering iodine value by hydrogenation Avoid ß-polymorph formation by interesterification

Facilitate interchangeability (cost reduction) Partial hydrogenated soybean oil versus palm oil

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