Walk down the oil shelf in any supermarket — in Mumbai, Sharjah, or London — and you will see two kinds of bottle that share a name. One is “refined.” One is “cold-pressed” or kachi ghani. The price difference is usually two-to-one. The reason is not marketing. It is what each bottle contains, and what each does not.
Cold-pressed: what the seed gives
Cold-pressing is the older method. The seed — mustard, groundnut, sesame, coconut copra — is pressed by mechanical force at temperatures kept below 30–40°C. No solvents touch the seed. The oil that drains is filtered to remove particulate matter and bottled. That is the entire process.
What this leaves in the bottle:
- The natural fatty acid profile, unaltered. Mustard oil retains its erucic acid signature; sesame retains its sesamol; coconut retains its lauric acid balance.
- Volatile aromatic compounds — the smell and flavour that distinguish one oil from another. The pungency of sarson, the nuttiness of til, the sweetness of coconut.
- Natural antioxidants — tocopherols, sesamin, polyphenols — that the seed itself produced to keep its own oil stable.
- Trace nutrients — small amounts of vitamin E, sterols, lecithin.
The colour is variable. The smell is the seed. The taste is unmistakable.
Refining: what gets stripped
The refining process was developed in the 1900s to extend shelf life, neutralise odour, and allow blending. A typical industrial refinery applies six steps:
- Solvent extraction with hexane — the most common solvent in the industry, more efficient than mechanical pressing but it leaves trace residues.
- Degumming to remove phospholipids.
- Neutralisation with sodium hydroxide to remove free fatty acids.
- Bleaching with activated clay or carbon to lighten the colour.
- Deodorisation at 240°C+ to drive off the volatile aromatics.
- Winterisation to remove waxes that would cloud the bottle in cold storage.
Each step is a removal. By the final bottle, what is left is mostly the triglyceride backbone — the fatty acids — with much of the natural sensory and antioxidant profile gone. The oil is pale, neutral, and stable on the shelf for two years.
This is not inherently bad. Refined oil has its uses — deep-frying at industrial scale, neutral-flavour baking, applications where the oil’s character would be a distraction. It is also vastly cheaper to produce.
But it is not the same oil that left the seed.
Three things that change
1. The flavour
The clearest difference. A cold-pressed mustard oil will bite at the first sniff; a refined mustard oil will smell of nothing. Tadka with refined oil is the same tadka without the carrier — the cumin and chilli arrive thin. This is why a refined oil makes the dal taste different even when the recipe is identical.
2. The smoke point
Counter-intuitively, refined oils have higher smoke points than cold-pressed — because the volatile compounds that smoke first have already been stripped. A refined mustard oil smokes at ~270°C; ours at 250°C. For deep-frying at temperature, refined is the engineering choice. For tadka, for finish, for everything the home kitchen actually does, the cold-pressed smoke point is fine and the flavour is the reason.
3. The oxidative stability
Here the relationship reverses. Refined oils have lost their natural antioxidants but gained shelf life through neutralisation and deodorisation. Cold-pressed oils retain antioxidants — sesame’s sesamin, mustard’s natural phenolics — but their shelf life is six to twelve months from press date, and they prefer dark, cool storage. The cold-pressed oil is more alive, in the technical sense, and behaves more like a fresh product than a pantry staple.
What this means for the household
There is no universal answer. There is one principle: buy the oil that does the job you are buying it for.
- For tadka, finish, salad, ritual lamp, traditional pickle: cold-pressed. The flavour and the antioxidant profile are why you are buying the oil at all.
- For deep-fry, neutral-flavour baking, industrial-scale work: refined will perform fine.
The mistake is to buy refined oil for the first job and conclude that mustard oil “doesn’t taste like much.”
What we do
We press cold. We do not blend. We do not refine. We never have, in sixty years. The press in Sangli would not know how.