The document discusses the production of sunflower oil. It begins by describing that sunflower oil is pressed from sunflower seeds and is commonly used for cooking. It then outlines the key steps in sunflower oil production, which include cleaning and grinding the seeds, pressing or extracting the oil using a screw press or solvents like hexane, removing solvent traces through distillation, and refining the oil by removing impurities and odors. The final product is refined edible sunflower oil, while the main byproduct is sunflower seed cake which is used for animal feed or fertilizer.
2. SUNFLOWER OIL
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Sunflower oil is the non-volatile oil pressed from the seeds of sunflower
(Helianthus annuus).
Sunflower oil is commonly used in food as a frying oil, and in cosmetic
formulations.
The world's total production of sunflower oil in 2014 was nearly 16 million tonnes,
with Ukraine and Russia as the largest producers.
Sunflower oil is primarily composed of linoleic acid, a polyunsaturated fat, and
oleic acid, a monounsaturated fat.
Through selective breeding and manufacturing processes, oils of differing
proportions of the fatty acids are produced. The expressed oil has a neutral taste
profile. The oil contains a large amount of vitamin E.
5. Cleaning the Seeds
The harvested sunflower oil seeds are passed over magnets to removal any metal
traces, and other impurities are being get rid off by cleaning sieve and destoners.
Then the outer covering (hulls) of the seeds are removed to obtain pure seeds.
Grinding the Seeds
The de-hulled seeds are ground into coarse meal to provide a larger surface area
to be pressed. Hammer mills or grooved rollers are used to crush the coarse meal
into uniform fine particles. Then the meal is heated to enable oil extraction,
though impurities are released with oil during this process and such impurities
should be removed before the oil is declared edible.
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6. Pressing
The heated meal is fed into a screw press which progressively increases the
pressure from sixty kilopascals (kps) to 950kps, 206kps, to 850kps as the meal is
passed through a slotted barrel. At the same time, the oil is squeezed out through
the slots in the barrel and recovered.
Extraction of the Additional Oil
Volatile hydrocarbon solvents are used to process the remaining oil cake through
solvent extraction so as to achieve maximum yields. The most commonly used
solvent is hexane which dissolves the oil out of remaining oil cake. The solvent is
then distilled out of the oil, passed through the matter and then collected at the
bottom.
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7. Removal of Solvent Traces
Around 90% of the volatile solvent left in the extracted oil, evaporates and it’s
collected for reuse. Then a stripping column is used to retrieve the remaining
solvent. In this process, the oil is boiled by steam and the solvent evaporates,
condenses and is collected separately.
Refining of the Oil
Sunflower oil refining involves removal of the bitterness, color and odor. First the
oil is heated at temperatures between 40 0C and 85 0C. Then it’s mixed with an
alkaline substance like sodium carbonate or sodium hydroxide. The oils are
degummed by treating them with heated water at temperatures between 85 0C and
95 0C or with acidified water. This precipitates out most of the gums usually
phosphatides. Then centrifugation is done to remove the dregs.
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8. The edible oil used for cooking is obtained by filtering it through activated carbon,
activated clay or through fuller’s earth which adsorbs the pigmented substance
from the oil. However, the oil intended for salad dressing needs refrigeration.
Such oil is obtained through winterizing by rapidly chilling and filtering to
remove waxes. This procedure is applied to prevent solidification of the oil in the
refrigerator.
The final step involves deodorizing the oil by passing the steam over hot oil placed
in a vacuum at temperatures between 225 0C and 250 0C.
This allows the volatile components responsible for the taste and odor to
evaporate from the oil.
One percent citric acid is added to the oil to inactivate any trace metals present,
hence preventing oxidation within the oil, thereby prolonging the shelf life of the
oil.
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9. Sunflower oil seed cake is the most obvious waste product of the sunflower seed oil
production process.
Such oil seed cake is used to manufacture low-grade fertilizer and produce animal
feeds. The unwanted by-products are disposed of.
The most common product of the sunflower seed oil making is the oil seed
cake/meal, which is usually used to make animal feed and low-grade fertilizer or
partly disposed.
Sunflower meal is a successful substitute for soybean meal in equal protein diets
for ruminant animals, as well as for swine and poultry feed.
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10. Meal produced from undehulled seeds, containing around 28% protein and 25%-28%
fiber.
Meal produced from partially de-hulled seeds, containing 35%-37% protein and
18% fiber;
Meal produced from seeds with 2-step de-hulling process, containing 40%-42%
protein and 12%-14% fiber.
The meal composition thus depends on the efficiency of the de-hulling, and the oil
content of sunflower meals ranges from 1.5% to 2.5%, depending on oil extraction
efficiency and raw materials. Fresh sunflower meal must be dried for optimal
storage. It can be ground, broken into small pieces or pelletized for easy handling
and storage by processing under high pressure in an pelletizer or extruder, with
an addition of proper binder such as molasses, fats, etc.
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