Transcript Vegetable Oils

Vegetable Oils
Where is the oil located?
• Plants use stored oil as food for germinating
embryo, caloric content is high so is efficient
storage material. Double that of carbohydrates
and proteins.
• Oil can be stored in endosperm (castor,
coconut), cotyledons (peanut, soybean),
scutellum (corn), fruit pulp (palms and olives).
• Seeds have organelles called as glyxosomes
that convert fatty acids into carbohydrates during
germination.
Oils
• Mainly hydrocarbons made up of
– Glycerol (backbone) with three fatty acids
chemically bonded to it - triglycerides
Cholesterol
Unsaturation
• The number of double bonds determines the
level of saturation.
• Vegetable oils are complex mixtures and
saturation levels cannot be calculated directly
very easily;
• % saturation is determined by Iodine method,
• Iodine breaks ='s and is incorporated. Amount of
Iodine left over is determined. Iodine values
range from 7 to >200. 70 are called fats (solid at
room temperature) and higher values
correspond to more unsaturation.
Unsaturation and Iodine Value
• Drying - >150 thin film will dry into
impervious coating
• Semidrying - 100-150
• Nondrying - 70-100
• Fats 70
http://discovermagazine.com/2001/mar/featchemistry/
Soap making
• Soap is salt of fatty acid
+3NaOH
3 RCOONa+
+
Soap Making
• Water lye (Base)
• Add oil or fat
– Glycerol and fatty acids separate
– Fatty acids will react with base to form salt of
fatty acid
– Head which is soluble in water
– Tail soluble in oil
Oil Paints and Varnishes
• Drying or semidrying oils (linseed & tung oil)
– oil paints are boiled with heavy metal containing
compounds (Mg, Co, Pb) which help oils absorb
oxygen and form a hard film;
– varnishes are produced by mixing boiled oils with
resins or gums;
– enamels are varnishes + pigments;
– paints do not contain gums or resins
• Latex paints - alkyd resins which are
manufactured from fatty acids cleaved from
vegetable oils, water soluble
Linoleum and Jojoba
• Made up of Oils + gums + synthetic resins +
pigments;
– oils are "blown" which thickens them and makes them
soluble in petroleum oils (resins)
– linoleum is not used much in U.S. anymore.
• Jojoba - oils is esters rather than triglycerides,
originally thought to be good substitute for
sperm oil but is not because of high temperature
breakdown; however is useful in medicine and
cosmetics.
Extraction
• Grinding with stones
- cold pressing – high quality
• Steam driven stone press
– hot pressing
• Screw press - continuous feed
• Solvent extraction - follows screw press,
hexane
Refining
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Removal of free fatty acids
Degumming - removes mucilaginous material
Bleaching - removal of pigments
Deodorized - steam heating
Winterize - prevents clouding by chilling oil and
filtering out particles.
• Hydrogenation - yields vegetable lards,
margarine and cheese substitutes
Drying Oils
High in double bonds in FA
• Linseed oil - Linum usitatissimum, seeds, waterrepellent glaze
– mostly non-edible oils
• due to unpleasant flavor
• Cyanogenic glycosidesand
• rapid rancidity due to lots of double bonds.
– also source of flax
• Tung oil - Aleurites (Euphorbiaceae), seeds,
poisonous (not edible), used in paints,
waterproof coverings and caulking. Once grown
in U.S. but most now comes from China.
Semi-drying Oil
Few double bonds in FA
•
Safflower oil - Carthamus tinctorius, thistles, oil is from seeds, used in cooking oils,
salad dressings, margarine, high I value so low in calories but oxidizes readily
–
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Produces dye
Soybean oil – Glycine max already covered, stores well, used in salad and cooking
oils and artificial "fluffy" products.
Sunflower oil - Helianthus annuus - native North American plant but development of
large-headed cultivars is largely credited to Russians; used as salad and cooking oil;
paints, varnishes and resins; added to diesel fuel.
Considered equal to olive oil, used for production of margarines.
Corn oil – Zea mays salad dressing and margarines, stable but smokes at high temp.
Sesame oil - Sesamum indicum, from Ethiopia, highly resistant to oxidation due an
antioxidant compound called sesamolin, most is consumed and produced in Africa,
Middle East, India and China
Cottonseed oil – Gossypium barbedensis byproduct of cotton fiber production, must
remove gossypol (toxic to most animals except cows); Wesson oil, hydrogenation --->
Crisco
Rapeseed oil - Brassica napus, edible oil but possibly toxic, most useful as machine
oil as an lubricant
Non-drying Oil
• Peanut oil - Arachis hypogaea, premium cooking
oil
• Olive oil - Olea europea, obtained from fruit pulp,
– Gentle pressing of the olive – virgin oil
– Further pressing – first, second grade oils
– Has monounsaturated fat – good for health.
• Castor oil - Ricinus communis
– Laxative – ricinoleic acid
– poison - ricine (alkaloid) and ricin (highly toxic
protein); used in soaps, paints, lubricants
Vegetable Fat
• Oil palms - Elaeis guinensis, distinct oils are obtained
from fruit pulp and seeds
– kept separate due to differences in chemical composition; used
in soap, candles, margarine and shortenings
– U.S. diets are avoiding fats and palm oils are taboo.
• Coconut oil - Cocos nucifera, cosmetics and nondairy
"dairy" products
– At 20oC becomes semisolid; at 15oC becomes brittle
– Has free fatty acid – caprylic acid - smell
• Shea butter: Butyrospermum parkit
– 50% saturated fat
Relative effect of fats on Total Cholesterol
Myristic
acid
C14:0
Palmitic
acid
C16:0
Linoleic
acid
C18:2
Alpha
Linolenic
Acid
C18:3
Dietary
Cholesterol
Butterfat
11
27
2
1
273
1788
Canola oil
0
4
22
10
0
-514
18
9
2
0
0
1674
Corn oil
0
11
58
1
0
-870
Grape seed oil
0
8
73
0
0
-1196
Lard
2
26
10
0
77
630
Olive oil
0
13
10
1
0
88.6
Safflower oil*
0
7
78
0
0
-1310
Soybean oil
0
11
54
7
0
-908
Sunflower oil*
0
7
68
1
0
-1142
Oil or Fat
Coconut oil
* Not high-oleic
Delta TC
Change in
cholesterol
level
Wax
• Long chain alcohol and long chain fatty
acid
• Jojoba wax: Simmondsia chinensis
– Seeds contain liquid wax
– Similar to sperm whale oil