Key findings
- 1Hexane extraction and multi-step refining are genuine industrial processes, even though the bottle lists a single ingredient
- 2Cold-pressed seed oils are mechanically extracted without chemical solvents
- 3The same seed can produce a simply pressed oil or a heavily refined one, depending entirely on the extraction method used
- 4In our analysis, seed oil products average a Processing Score of 1.6, which is Level 1
Why is Seed Oils Level 1 on average?
The dominant industrial process for seed oils involves crushing seeds, then washing them with hexane (a petrochemical solvent) to extract maximum oil yield. The hexane is evaporated and recovered, but trace residues may remain. The crude oil then undergoes degumming (phosphoric acid removes phospholipids), alkali refining (sodium hydroxide neutralizes free fatty acids), bleaching (activated clay removes pigments), and deodorizing (high-temperature steam strips volatile compounds). Each step removes "impurities" but also removes flavor, color, antioxidants, and minor nutrients. Cold-pressed or expeller-pressed seed oils skip the solvent extraction but are rare and more expensive. Our Processing Score counts ingredients and additives, not refining steps, so a bottle that lists one oil scores low however it was extracted. In our analysis, seed oil products average a Processing Score of 1.6, which is Level 1.
How 946 seed oils products break down
Share of products at each processing level, in our analysis.
Seed Oils brand comparison
From least to most processed in our database.
How to read a seed oils label
- 1
"Refined" seed oils have undergone the full hexane extraction and refining process
- 2
"Cold-pressed" or "expeller-pressed" seed oils skip solvent extraction
- 3
The refining process, not the seed itself, is what separates one bottle from another
- 4
Unrefined seed oils have more flavor and color but shorter shelf life: a trade-off, not a defect
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Frequently asked questions
Are seed oils bad for you?
This question is about nutrition and health claims, not processing classification. From a processing standpoint, refined seed oils go through solvent extraction and industrial refining, while cold-pressed versions are mechanically pressed. Neither description is a health recommendation.
What is hexane extraction?
Hexane is a petrochemical solvent used to dissolve and extract oil from crushed seeds. It is extremely efficient (extracting ~98% of oil vs. ~60-70% from pressing) but is an industrial chemical process. The hexane is evaporated and recaptured after extraction.
Is olive oil a seed oil?
No. Olive oil is a fruit oil pressed from the flesh of olives. Most "seed oils" refer to oils extracted from seeds (soybean, canola, sunflower, corn, safflower). The distinction matters because olive oil is typically cold-pressed, while seed oils are typically solvent-extracted.
Are cold-pressed seed oils less processed?
Yes. Cold-pressed or expeller-pressed seed oils are mechanically extracted without hexane solvent, skipping the chemical refining steps. They cost more because mechanical pressing yields less oil.