Fundamentals of Oils & Fats by Albert J. Dijkstra, PhD Ignace Debruyne, PhD [email protected] Fundamentals of Edible Oil Processing and Refining Saturday, May 3, 2014
Fundamentals of Oils & Fats by Albert J. Dijkstra, PhD
Ignace Debruyne, PhD [email protected] Fundamentals of Edible Oil Processing and Refining Saturday, May 3, 2014
2
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
10
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
12
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
14
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
16
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
17
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
18
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)
19
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
21
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
22
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
23
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
27
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
28
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
29
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
30
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
THANK YOU Ignace Debruyne & Associates Consultancy [email protected]