How vegetable oil is made
Most vegetable oil is washed out of crushed beans with hexane, which is then boiled off.
- stations
- 7
- things upstream
- 8
- raw sources
- 6
- steps from the ground
- 3
The short version
Seeds are cleaned, cracked and flaked, then pressed or soaked in hexane, a petroleum solvent, to pull out the oil. Heat evaporates the solvent. The crude oil is then refined: gums are removed, free fatty acids neutralized, color bleached out, and smells stripped by steam under vacuum.
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Clean and crack the seeds
Soybeans or rapeseed are cleaned of stalks and dirt, then cracked and rolled into thin flakes. Flaking breaks open the oil cells and gives the extractor far more surface to work on.
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Press out the first oil
An expeller, which is a big screw press, squeezes part of the oil out mechanically. Oil from this step is the usual route for traditional oils, and it is preferred by many natural-food buyers.
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Wash with solvent
Most newer industrial oils such as soybean and corn are extracted with hexane. Flakes move through a bath of solvent that dissolves the oil, which gives higher yields faster and more cheaply than pressing.
Goes in -
Boil off the hexane
The oil and solvent mix is heated to around 149 °C so the solvent evaporates. It is condensed and reused, and the defatted flake left behind becomes high-protein animal feed.
about 149 °C
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Degum and neutralize
Crude oil is washed with water and mild alkali to remove gums and free fatty acids. These impurities would smoke when frying and shorten the shelf life.
Goes in -
Bleach out the color
A clay-like bleaching earth adsorbs the pigments, and filtering leaves the pale gold color shoppers expect.
Goes in -
Steam out the smell
The oil is heated under vacuum to roughly 232 °C while steam is bubbled through from the bottom. The steam carries off volatile compounds that would taste or smell like beans. Deodorization is a core step in producing refined oil.
about 232 °C under vacuum
Worth repeating
- Procter and Gamble marketed Crisco, a cottonseed oil product partly hydrogenated until solid, as early as 1911.
- Supercritical carbon dioxide can replace hexane as a non-toxic solvent.
Back to the ground
Follow every input upstream and vegetable oil starts as these 6 raw sources.
Where it goes next
Vegetable oil feeds 29 lines directly and reaches 161 things in total.
Further down the line
Keep walking
Sources
Cite this page: "How vegetable oil is made." Assembly Line, 2026-11-03. https://assemblyline.org/make/vegetable-oil