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Sunflower
Hundreds of De Smet plants are processing sunflower.

Origin

Except Argentina from where the seed originates, it is mainly produced in Eastern Europe but today it is produced in more and more countries.
Eastern Europe is the main producer and that’s why it is there that the researches for the increase of production in quality and quantity were mainly developed.

The sunflower is well known (as suggested by its name) by its heliotropism. The stem is tall, up to 3 to 4 m high, has a diameter of 2 to 8 cm and supports very wide leaves and heavy flowers (15 to 40 cm wide). The flower is surrounded by orange leaves and has an amount of fruits which corresponds to 50-60% of its weight.

The fruit - an aken of a shape laterally compressed and chamfered - with a length of 7 to 19 mm, is covered by a ligneous wrapping called shell, which is very hard, very abrasive and waxy (3% of wax) surrounding the almond, and has a colour either black or dark green.
The undecorticated seed may contain from 35 to 45% of oil. The shells represent 25 to 30% of the total weight. The decorticated seeds may contain up to 60% of oil. The yield in sunflower seeds is about 1800 kg/ha.

100 kg of seeds contain :
- 75% of pure almonds containing 60% of oil, 5.25% of moisture, 57% of proteins (on oil and water free basis) or 19.8% as such
- 25% of pure hulls containing 2% of oil, 8% of moisture, 5% of proteins (on oil and water free basis) or 4.5% as such

After decorticating, we usually have :
- 86% of meats containing 52.5% of oil, 5.6% of water and 13% of remaining hulls
- 14% of hulls used in the boiler, containing maximum 1% of oil more than the botanical oil content of the pure hulls.


Composition

Sunflower oil is semi-siccative and mainly contains
  • 15-40% of oleic acid
  • 45-70% of linoleic acid
  • 4-7% of palmitic acid
  • 1-3% of stearic acid
  • iodine value : 120-137
  • saponification value : 188-194
  • melting point : -16/-18°C
  • titer : 16-20°C
  • viscosity at 20°C : 8.2° Engler


Process

The process of the sunflower seeds in order to extract the oil includes the following steps :

  • drying of the seeds till 7-8% of moisture before ensilage
  • decortication and preparation before preexpelling
  • pre-expelling giving cakes with 18 to 22% of oil
  • solvent extraction of cakes


Direct solvent extraction is however possible but presents the following disadvantages :

  • due to the necessity to keep the hulls for the direct solvent extraction, the wear of the flakers is heavy and the extracted meal is poor in proteins
  • size of the solvent extraction unit
  • a poor final residual oil content
  • meal desolventising rather difficult
  • when necessary to reach a higher protein content, the decorticating of the extracted meal is rather difficult.

The sunflower oil contains approximately 1.5% of lecithin (phosphatides) as main part of the unsaponifiables. Separated before neutralisation, it is re-incorporated into the extracted meal.

In the unsaponifiables of the sunflower oil, the waxes also represent a big amount. Those waxes, at cold temperature, are quite insoluble in the triglycerides and have a tendency to precipitate, which gives the oil a turbidity aspect, which is detrimental to marketing even if waxes are not contrary to the intrinsic value of the oil. As the waxes come from the shells, it points out the importance of the decorticating; the latter is counterbalanced by the fact that a certain amount of shells are necessary for a good prepressing and by the oil loss through the entrained seed.
The waxes can be eliminated from the oil by winterising.

Finally the oil is bleached and deodorised.

End uses

It is mainly used as food oil (salad and cooking) and in the manufacture of margarine; it may be used also in varnish fabrication.

The meal is highly appreciated thanks to its high protein content (45-50%) as animal feed, especially for large breeding. The most delicate point in case of insufficient decorticating is the excessive content of cellulose of the meal, which makes it indigestible for some animals (poultry and pork).
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