Castor Seed

4 De Smet plants where designed for castor seed.


Origin

Castor belongs to the family of euphorbia and is a ligneous plant.
It origin is in Abyssinia but it has been known for long in all hot and semi-tempered countries.

Its height varies between 0.5 and 0.8 m. following varieties and countries. It reaches its tallest size in hot countries.
The leaves are made of 5 to 11 lobes roughly jagged and are alternates on a support ending with a stalk of 20 to 50 cm long. The cylindrical stalk is hollow and has a colour close to that of the leaf (red, green or purplish-blue).

The fruit is a capsule with 3 shells, self-opening at maturity or not, covered with spurs or smooth according to varieties, and encloses one or more seeds. The seed is of oval shape, slightly flat and smooth and usually of marbled colour. One of the ends often presents a bulge or carbuncle. The nut represents 75% of the seed weight and contains about 60 to 70% of fatty matter.


Process

Castor seed oil is extracted by prepressing followed by solvent extraction.

Composition
It is a non-siccative oil and mainly contains :

• 80-87% of ricinoleic acid
  
• 5-9% of oleic acid
  
• 6-7% of linoleic acid
  
• 1-2% of stearic acid
  
• iodine value : 81-91
  
• saponification value : 167-187
  
• melting point : -10 to -12°C
  
• titer : 2-5°C
  
• unsaponifiables : < 1%
  
• density (high) : 0.95-0.97 at 15°C
  
• viscosity at 20°C : 1000 cps
  
• viscosity at 100°C : 20 cps
  

End uses

Castor seed oil, according to its origin is used as :
- CASTORSEED OIL ‘A’, of first pressing at cold, with an acidity below 0.7%, for medicinal use
- CASTORSEED OIL ‘B’, of hot pressing and with an acidity below 15%, is used for lubricant preparation (multigrade with low viscosity variation), cutting oil, leather industry, parfu-mes, plastics (RILSAN)
- CASTORSEED OIL ‘C’, from solvent extraction, is used, after being dehydrated by sulfuric acid, which makes it very siccative, as replacer of linseed oil or tung oil in varnishes and paints.

The press cake contains ricinine which is a violent poison, acting as energetic binder on red blood corpuscles; it is thus unacceptable for livestock (9.3 mg of ricinine are enough to kill a dog).
The extracted meal may be acceptable for livestock after toasting; it is anyway usually forbidden for any livestock. They all serve as fertilisers.