Sunflower oil production has the following steps
Cleaning
De-hulling
Grinding
Pressing
CLEANING THE SEEDS:
The harvested sunflower oil seeds are passed over magnets to subtraction any metal traces, and other impurities are getting rid of by cleaning sieve and destoners. Then the outer covering (hulls) of the seeds are removed to get pure seeds.
DE-HULLING:
Sunflower seeds from the oil-type contain about 20% to 30% hulls that are sometimes removed before oil extraction to ensure the quality of both oil and sunflower meal. De-hulling is completed when the seed has a moisture content of 5% after cleaning. The usual procedure consists of cracking the seeds by the mechanical action of centrifugal or pneumatic sheller, which can also be completed by abrasion. Then the resultant mixture is winnowed to separate the hulls from the kernels. Some oil sunflower seeds have thin hulls that are hard to remove, so they can be free from de-hulling to avoid oil loss.
GRINDING THE SEEDS:
The de-hulled seeds are ground into coarse meal to give a larger surface area to be pressed. Hammer mills or grooved rollers are mainly 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 procedure and such impurities should be removed before the oil is declared edible.
PRESSING:
The heated meal is fed into a screw press which progressively increases the pressure from 60 kps to 950kps, to 850kps as the meal is passed through a slotted barrel. At the same time, the oil is squeezed out during the slots in the barrel and recovered.
OIL REFINING AND PROCESSING:
Extracted and desolventized sunflower oil should be further processed to create an edible product. Edible oils are refined to develop the flavour, odour, colour and solidity using processes that degum, neutralize, bleach and deodorize the oil. These oil refining processes eliminate contaminants such as phosphatides, free fatty acids, and pro-oxidants.
The final stage involves deodorizing the oil bypassing the steam over hot oil placed in a vacuum at temperatures between 225 C and 250 C. This allows the volatile components steady for the taste and odour to evaporate from the oil. One percent citric acid is added to the oil to inactivate some trace metals present, thus preventing oxidation within the oil, thereby prolonging the shelf life of the oil.
PACKING THE OIL:
Pure oil is measured or packed in clean containers, for exporting.
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