Vegetable Oils University of Central Arkansas

							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




                           3 RCOO-
                 +3NaOH              +
                             Na+
               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
• 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, water-
  repellent 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
     –   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


                                                            Alpha                    Delta TC
                      Myristic   Palmitic   Linoleic
                                                          Linolenic    Dietary      Change in
       Oil or Fat      acid        acid       acid
                                                             Acid     Cholesterol   cholesterol
                      C14:0       C16:0      C18:2
                                                           C18:3                       level


Butterfat               11         27          2                 1       273               1788

Canola oil               0          4         22                 10       0                -514

Coconut oil             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



                                              * Not high-oleic
                     Wax
• Long chain alcohol and long chain fatty
  acid
• Jojoba wax: Simmondsia chinensis
  – Seeds contain liquid wax
  – Similar to sperm whale oil