Is Olive Oil a Seed Oil? Fruit Oil vs Seed Oil

No — olive oil is not a seed oil. It is pressed from the flesh of a fruit: the olive is a drupe, a stone fruit like the cherry and the plum, and the oil sits in the flesh, not in the stone. Seed oils — sunflower, rapeseed, soybean, grapeseed — are extracted from seeds, in most industrial practice with heat and a solvent, and then refined. The two groups differ in where the oil comes from and in how it is taken out, and both differences are written into law and trade standards rather than left to marketing.

A seed oil is an oil extracted from the seed of a plant. A fruit oil is pressed from the flesh of a fruit. Olive oil is the second, by botany and by statute.

Plate I · IllustrationRecord

Why is olive oil not a seed oil?

Because of where the oil is, and because of what the law permits anyone to do to get it out.

The botany first. An olive is a drupe: skin, oil-rich flesh, and a hard stone with a seed inside. As the fruit ripens through the season — olives are harvested from October into winter — oil accumulates in the flesh, which is where almost all of it stays. A mill crushes the whole fruit, stone included, works the paste slowly, and separates the oil by pressing or centrifuge. Nothing is dissolved out of a seed; the oil is squeezed out of a fruit.

Fig. I · The olive in sectionDiagram

An olive is a drupe — a stone fruit like the cherry and the plum: skin, oil-rich flesh, and a hard stone with a seed inside.

1. 1The skinThe thin outer layer, drawn as the section’s double outline.
2. 2The oil-rich fleshAs the fruit ripens, oil accumulates in the flesh — which is where almost all of it stays. The beads are drawn here and nowhere else.
3. 3The hard stoneCrushed with everything else — a mill crushes the whole fruit, stone included.
4. 4The seed, inside the stoneA seed oil is an oil extracted from the seed of a plant. Not one bead is drawn here: the olive’s oil sits in the flesh, not in the stone.

Oil — solid beads, in the flesh and nowhere elseThe stone’s hard shell — hatched

Nothing is dissolved out of a seed; the oil is squeezed out of a fruit.

The law then fixes that process in place. Under retained Regulation (EU) No 1308/2013, virgin olive oils are oils “obtained from the fruit of the olive tree solely by mechanical or other physical means under conditions that do not lead to alterations in the oil” — permitted treatments run to washing, decantation, centrifugation and filtration, and no further. Oils obtained using solvents, or using adjuvants with a chemical or biochemical action, are excluded from the virgin category by definition. The International Olive Council’s trade standard, which governs the international trade, draws the same line in the same words and grades the category by free acidity — extra virgin at not more than 0.80 g per 100 g.

The classification is even printed on the bottle. Under retained Regulation (EU) No 29/2012, every extra virgin label must carry the words “superior category olive oil obtained directly from olives and solely by mechanical means” — a sentence of mandatory label copy that is, in effect, the answer to this page’s question. What the rest of the label is required to say is set out in how to read an olive oil label.

Which everyday oils are fruit oils, and which are seed oils?

The Codex Alimentarius standard for named vegetable oils (CXS 210-1999) defines each oil it names by its source, and with the olive-oil instruments alongside it the sorting is clean:

• Fruit oils — pressed from the flesh. Olive oil, avocado oil, and palm oil, which Codex defines as “derived from the fleshy mesocarp of the fruit of the oil palm”.
• Seed oils — extracted from seeds or kernels. Sunflower oil (“derived from sunflower seeds”), soybean oil, rapeseed oil, grapeseed oil (“derived from the seeds of the grape”), maize (corn) oil from the germ, plus cottonseed, safflower and the rest of the shelf.

The oil palm makes the point better than any definition: the same fruit yields palm oil from its flesh and palm kernel oil from the seed inside — two oils with sharply different compositions from one crop. The classifier is the part of the plant the oil comes from, not the species.

How are seed oils extracted?

By force and chemistry, described here neutrally, because all of it is ordinary lawful food processing. Oilseeds are dry, hard and protective of their oil, so the industrial route works in stages: the seeds are cleaned, flaked and usually cooked, pressed to take the easy oil, and the press cake is then washed with a solvent — hexane — to recover the rest. The solvent is driven off and recovered; retained Directive 2009/32/EC authorises hexane for the production of fats and oils, with a residue limit of 1 mg/kg in the finished fat or oil.

Crude seed oil then goes through refining: degumming and neutralisation to remove phosphatides and free fatty acids, bleaching to remove pigments, and deodorisation — steam stripping at high temperature under vacuum — to remove the volatile compounds that carry odour and taste. The result is the pale, bland, stable oil the supermarket aisle is built on.

Fig. II · Two routes to an oilDiagram

Oilseeds are dry, hard and protective of their oil, so the industrial route works in stages. The mill’s route is set beside it, stage for stage.

Fruit route · the mill

1. CrushThe whole fruit, stone included.
2. Work the pasteSlowly.
3. SeparateBy pressing or centrifuge.
4. Virgin olive oil“Solely by mechanical or other physical means” — permitted treatments run to washing, decantation, centrifugation and filtration, and no further.

Seed route · industrial practice

1. Clean
2. Flake
3. CookUsually.
4. PressTo take the easy oil.
5. Solvent washThe press cake washed with hexane to recover the rest; the solvent driven off and recovered. Residue limit 1 mg/kg in the finished fat or oil.
6. Degum and neutraliseRemoves phosphatides and free fatty acids.
7. BleachRemoves pigments.
8. DeodoriseSteam stripping at high temperature under vacuum — removes the volatile compounds that carry odour and taste.
9. Refined seed oilPale, bland, stable — the oil the supermarket aisle is built on.

Oils obtained using solvents, or using adjuvants with a chemical or biochemical action, are excluded from the virgin category by definition — and the route is printed on the bottle: every extra virgin label must carry “superior category olive oil obtained directly from olives and solely by mechanical means”.

One honesty note: the seed-oil route is not compulsory. Cold-pressed rapeseed oil, made by mechanical pressing without solvent extraction, is a familiar UK product, and Codex defines cold pressed oils as it defines virgin ones — mechanical procedures, without altering the oil — with the added condition that no heat is applied. What that term is worth on a label is the subject of cold-pressed olive oil. The fruit/seed split is fixed by botany; the process split is a choice.

What does refining remove from an oil?

Mostly the minor constituents — the one or two per cent of an oil that is not triglyceride, and that carries most of its character. These are composition facts, measured in the laboratory:

• Phenolic compounds. The classic survey (Owen and colleagues, 2000) put total phenolics at about 232 mg/kg in extra virgin olive oil against about 62 mg/kg in refined olive oil — its lignan figures fall from about 41.5 mg/kg to about 7.3 mg/kg across the same divide — and reported the seed oils it analysed as devoid of these compounds, on average. What a phenolic number means when a label prints one is covered in high-polyphenol olive oil, and what the research literature says about these compounds is read on its own terms in olive oil polyphenols.
• Tocopherols (vitamin E). Refining takes a substantial share: in a soybean-oil processing study, losses of the individual tocopherols ran to roughly 55–63% between crude and fully deodorised oil, with deodorisation the single most destructive stage. The stripped tocopherols collect in the deodoriser distillate, which is why that distillate is valued as a raw material for natural vitamin E.
• Squalene. Extra virgin olive oil typically carries about 2–12 g/kg of this hydrocarbon; in the same classic survey, the extra virgin olive oils averaged 424 mg per 100 g against 24 mg per 100 g across the seed oils. Refining diminishes it too: bleaching isomerises a portion, and deodorisation strips part of it into the distillate, from which it is commercially recovered.

Notice what this does to the classification. Fruit against seed is one axis; virgin against refined is another, and they are independent. Refined olive oil exists — lampante-grade virgin oil, too defective for the table, is refined into blandness and blended back with virgin oil, and must be labelled accordingly. A virgin fruit oil keeps its minor constituents because nothing in its permitted processing can remove them; a refined oil of any origin has had them deliberately reduced. That, not the fatty acids, is where most of the compositional difference between the categories lives.

How do the fatty-acid profiles compare?

The major fatty acids survive refining almost untouched, and here olive oil does stand apart from the common seed oils — though not from all of them. The reference ranges below are from the International Olive Council’s trade standard for olive oil and from Codex CXS 210-1999, Table 1, for the seed oils, expressed as % of total fatty acids:

Two things follow. First, the caricature — olive oil monounsaturated, seed oils polyunsaturated — is roughly right for sunflower, soybean and grapeseed, which are linoleic-dominant, but wrong for rapeseed, a true seed oil that is nonetheless oleic-dominant. Second, breeding can move the numbers without moving the classification: Codex requires high-oleic sunflower oil to contain not less than 75% oleic acid, an olive-like profile from a seed. Fatty-acid arithmetic does not define a seed oil; source and process do. What the profile means at the hob — heat, stability, smoke point — is a separate question, taken up in cooking with extra virgin olive oil.

Why does everyone suddenly ask this question?

Because of the public argument over whether seed oils are harmful — a debate on which this page takes no position, since its subject is the classification, and the research on olive oil itself is read on its own terms at is olive oil good for you. What the classification question has, unusually for a trending question, is clean answers: fruit or seed is settled by botany, mechanical or solvent-and-refined is settled by process, and for olive oil both answers are printed on the label by force of law.

Where does THYMELIA stand?

THYMELIA is a UK house built on evidence-first sourcing from Greece — Cretan thyme honey first, and now a second line in preparation: extra virgin olive oil from the hills above Kalamata, in the southern Peloponnese. The same rules apply to it that apply to the honey: no shop yet, nothing on sale, and no claim ahead of its evidence — the standard is set out at sourcing and testing. What an oil from that region is, and why the region matters, is the subject of Kalamata olive oil.

This page answers one question at the base of the category. The category from the top, with every guide in it, is at olive oil.