Walk down any supermarket aisle in India and almost every bottle says something reassuring — "heart healthy", "light", "pure". Very few tell you how the oil was actually made. That process is the whole difference.
What refining actually involves
Commercial refined oil is produced for volume and shelf life. The typical sequence looks like this:
- Solvent extraction. Seeds are washed in a chemical solvent, usually hexane, to pull out the maximum possible oil. This is far more efficient than pressing — it leaves almost nothing behind in the seed cake.
- Degumming and neutralising. Acids and alkalis strip out free fatty acids and phospholipids.
- Bleaching. Clay filters remove the natural colour, so mustard oil loses its deep gold and groundnut oil loses its amber.
- Deodorising. The oil is steamed at 200–250°C to remove smell and taste.
What comes out is neutral, pale, odourless and extremely stable on a shelf. It is also stripped of most of what gave the seed its character.
What cold pressing involves
Cold pressing — called mara chekku or ghani in traditional Indian milling — is a single step. Seeds go into a press and are crushed slowly. The rotation is deliberately slow so friction does not build heat. Temperature typically stays under 50°C.
Nothing is added. Nothing is stripped out. The oil is filtered and bottled.
That is why cold pressed oil looks and smells like the seed it came from. Our cold pressed mustard oil has a sharp bite. Our sesame oil smells nutty and dark. That is not a flaw. That is the seed.
The four differences that matter
1. Vitamin E and antioxidants survive
Vitamin E is heat sensitive. Deodorising at 200°C removes a large share of it, along with sesamol and sesamin in sesame oil and the natural polyphenols in groundnut oil. Cold pressing leaves them in.
2. No solvent residue
Refined oil is required to keep hexane residue within regulated limits, and reputable brands do. Cold pressed oil never encounters a solvent, so the question does not arise.
3. Flavour
This is the difference you notice first. Refined oil is designed to taste like nothing. Cold pressed oil carries the seed forward into the dish — which is exactly why traditional recipes specified a particular oil rather than just "oil".
4. Shelf life
Here refined oil genuinely wins. Stripping out the reactive compounds makes it last far longer. Cold pressed oil should be used within a few months and stored away from heat and sunlight. This is a real trade-off, not a marketing point.
Is cold pressed oil better for cooking at high heat?
It depends on the oil, not on the pressing. Refined oils have higher smoke points because the compounds that smoke have been removed. Among cold pressed oils, coconut and groundnut are the most heat stable and handle deep frying well. Cold pressed sesame and mustard are better suited to tempering, sauteing and finishing.
Frequently asked questions
Is cold pressed oil healthier than refined oil?
Cold pressed oil retains more of the seed's naturally occurring vitamin E and antioxidants because it is never heated or chemically treated. Both are safe to cook with. The nutritional difference comes from what refining removes.
Why is cold pressed oil more expensive?
Yield. Solvent extraction pulls out nearly all the oil from a seed. Pressing leaves a meaningful amount behind in the cake. More seed is needed for the same bottle.
Why does cold pressed oil turn cloudy?
Natural sediment settling, and in the case of coconut oil, solidifying below roughly 24°C. Both are normal in unrefined oil. Refined oil stays clear because those particles were filtered out industrially.
How long does cold pressed oil last?
Use within three to six months of opening. Store in a cool, dark place away from the stove. Do not keep it on a sunny windowsill.
Chennamma Ajji cold pressed oils are made in small batches in Karnataka, FSSAI certified under licence 1122632300006. See the full range.