The oil aisle has turned into a battleground of buzzwords, cold-pressed, wood-pressed, expeller, refined, double-refined. It is easy to feel either guilt-tripped or sold to. This is a fair, plain-spoken look at what actually separates wood-pressed oil from refined oil, so you can choose by how you cook rather than by the loudest label.
How oil gets out of a seed
Every cooking oil starts the same way: there is fat locked inside a seed, nut or kernel, and it has to be coaxed out. There are broadly two routes. You can press the seed mechanically and squeeze the oil out, or you can wash the seed with a chemical solvent that dissolves the oil and carries it away. Those two routes lead to very different bottles.
Pressing is the older, simpler method, a physical squeeze, nothing added. Solvent extraction is the modern industrial method built for volume, getting almost every last drop out of the seed. Neither is a secret; both are well documented. The differences in flavour, colour, smoke point and processing all flow from this one fork in the road.
Cold/wood-pressed vs expeller-pressed
Both of these sit on the mechanical, solvent-free side of the fork, but they are not the same thing.
Cold-pressed / wood-pressed (marachekku, chekku, ghani)
This is mechanical pressing with minimal external heat. The seed is crushed and pressed slowly, in the traditional Indian form, inside a wooden press (marachekku) turned at low speed. It is solvent-free and unrefined. The trade-off is honest: the yield is lower, because a slow squeeze leaves some oil behind. In return you get stronger flavour, a fuller aroma and a deeper natural colour, because nothing has been stripped out. The catch worth knowing up front is a lower smoke point than refined oil.
To stay accurate: the wooden press still generates some friction heat. "Slow, low-temperature pressing" is the honest description, not "zero heat" or "never warmed". If you want the full story of the wooden press itself, see our piece on what marachekku oil actually is.
Expeller-pressed
An expeller is a continuous screw press. It is also mechanical and solvent-free, which is its real virtue. But the screw drives the seed harder and faster, and that friction raises the temperature more than a slow chekku does. So expeller-pressed oil is still pressed, still free of solvents, it just runs warmer during extraction than a leisurely wooden press.
- Cold/wood-pressed: slow press, minimal external heat, solvent-free, unrefined, lower yield, more flavour and colour, lower smoke point.
- Expeller-pressed: screw press, mechanical and solvent-free too, but friction raises the temperature more than a slow chekku.
- Refined: seed washed with a solvent for near-total extraction, then refined, neutral, stable at high heat, fewer of the seed's natural micronutrients.
What "refined" really means
Refined oil takes the solvent route. The seed is washed with hexane, a petroleum solvent, which dissolves and extracts roughly 97–99% of the oil. That is far more than any press can manage, which is a big part of why refined oil is cheaper per litre. The crude oil that comes out is then put through refining, typically a sequence of steps: degumming, neutralising, bleaching and deodorising.
The result of all that processing is a deliberately blank canvas, a neutral taste and colour, and a higher smoke point. The flip side is that the refining also removes some of the seed's natural micronutrients along with the colour, smell and any residual solvent. You gain stability and neutrality; you lose the seed's character.
Side-by-side comparison
Here is the whole thing on one page, with no thumb on the scale.
| Wood-pressed (cold-pressed) | Refined | |
|---|---|---|
| Extraction | Mechanical pressing (slow chekku / press), minimal external heat | Solvent extraction, seed washed with hexane for ~97–99% yield |
| Chemicals | Solvent-free; no hexane, no chemical refining | Hexane (a petroleum solvent), then degumming, neutralising, bleaching, deodorising |
| Heat | Slow, low-temperature pressing (some friction heat in the press) | Higher processing temperatures during refining and deodorising |
| Flavour & colour | Stronger flavour and aroma, deeper natural colour | Neutral taste and colour |
| Smoke point | Lower (unrefined) | Higher (refined) |
| Best use | Tempering, sautéing, drizzling and medium-heat cooking where flavour matters | Sustained high-heat cooking where a neutral, stable oil is wanted |
Smoke points, honestly
The smoke point is the temperature at which an oil starts to visibly smoke and break down. It matters because it tells you where an oil stops being pleasant to cook with. Unrefined oils have lower smoke points than their refined counterparts, that is simply true, and worth planning around rather than wishing away.
Approximate smoke points for unrefined oils:
- Coconut oil (unrefined): about 177°C / 350°F.
- Groundnut oil (unrefined): about 160°C / 320°F.
- Sesame oil (unrefined): about 177°C / 350°F.
All three sit lower than their refined versions. In practice that points unrefined oils towards tempering, sautéing and medium-heat cooking, rather than long, hard, high-heat frying. It is not a flaw, it is the consequence of leaving the oil unprocessed.
So which should you choose?
Choose by use, not by slogan. If you are tempering mustard seeds and curry leaves, finishing a dish, dressing a salad or cooking at medium heat where you actually want to taste the oil, a wood-pressed oil earns its place. If you are doing a long session of high-heat frying and want a neutral background flavour, a refined oil is built for exactly that and there is no shame in reaching for it.
Many kitchens, ours included, simply keep both and use each where it shines. If you would like a longer walk-through of matching oil to cooking style, read how to choose a cooking oil, and you can see what we press at our cold-pressed oils.