How Refining Destroys Your Oil Before It Even Reaches the Kitchen
You bought a bottle of "pure" sunflower oil. The label shows a bright yellow flower. The bottle is crystal clear. It smells like nothing. It looks perfect.
That's the problem.
Real oil — oil pressed from a seed or nut the way nature made it — is never perfectly clear, never odourless, and never colourless. What you're looking at in that bottle is not food in its natural form. It is the result of a brutal industrial process that strips away everything useful the seed had to offer, and sometimes adds things that were never meant to be there.
This is what actually happens to your cooking oil before it reaches your kitchen.
Where It Starts: The Seed
A groundnut, a sunflower seed, a coconut — each of these is a living thing. Packed inside is:
- Fat (the oil itself)
- Natural antioxidants — Vitamin E, polyphenols, sesamol (in sesame), tocopherols
- Phospholipids — compounds that support liver health and cell membranes
- Phytosterols — plant compounds that support cholesterol balance
- Flavour compounds — what makes groundnut oil taste like groundnut
- Colour compounds — beta-carotene, chlorophyll, carotenoids
When you cold-press or wood-press this seed, you get all of this. The oil is alive, complex, and nourishing.
Refining takes all of this and methodically destroys it. Step by step.
The 6-Step Destruction Process
Step 1 — Extraction with Hexane (Solvent Extraction)
Most commercial oil production does not begin with pressing. It begins with chemical solvent extraction.
The seeds are bathed in hexane — a petroleum-derived industrial solvent, the same family of chemicals as lighter fluid. Hexane dissolves the oil out of the seed far more efficiently than mechanical pressing, leaving almost nothing behind.
The result: maximum yield, minimum nutrition.
After extraction, the hexane is boiled off. Manufacturers say "most of it" evaporates. Studies have found residual hexane in commercial cooking oils. The exact amount varies. The long-term health effects of low-level hexane exposure from dietary intake are not fully understood.
Cold-pressed oils use zero solvents. The oil is pressed out mechanically, the way it has been done for centuries.
Step 2 — Degumming
The crude extracted oil contains phospholipids — compounds that appear as "gum" or cloudiness. These are actually valuable: phosphatidylcholine, the primary phospholipid in this gum, is the same compound found in egg yolks and is important for liver function and brain health.
Refining removes them because they interfere with the oil's shelf appearance and smoke behaviour.
Method: Hot water or acid (phosphoric acid) is added to the oil, causing the phospholipids to clump and separate. They are then removed entirely.
What's lost: Natural lecithin, phosphatidylcholine, and related compounds.
Step 3 — Neutralisation (Alkali Refining)
The degummed oil still contains free fatty acids — compounds that give oil its natural flavour and aroma, and also indicate freshness. These are removed because they make the oil taste "too strong" for the mass market and reduce shelf stability in the short term.
Method: Sodium hydroxide (caustic soda / lye) is added to the oil. It reacts with the free fatty acids to form soap, which is then separated and washed away.
What's lost: Natural flavour compounds, more antioxidants, some Vitamin E.
What's added: Trace soap residues, sodium compounds.
Step 4 — Bleaching
The neutralised oil is still yellowish or reddish — coloured by carotenoids, chlorophyll, and pigments that are naturally present in the source seed. These pigments are antioxidants.
The colour is considered undesirable for a "clean" commercial product, so it is removed.
Method: The oil is passed through activated bleaching clay or activated carbon at high temperature (80–110°C). The pigments are adsorbed onto the clay and filtered out.
What's lost: Beta-carotene, chlorophyll, remaining carotenoids, more Vitamin E, more antioxidants.
What's added: Traces of polyaromatic hydrocarbons that can leach from the bleaching clay.
Step 5 — Deodourisation
This is the most damaging step.
The bleached oil still has a detectable smell — the natural, characteristic scent of its source. This is removed through steam deodourisation: the oil is heated to between 180°C and 270°C (sometimes higher) under vacuum for several hours, with steam passed through it to strip volatile compounds.
At these temperatures:
- Remaining Vitamin E (tocopherols) is largely destroyed
- Omega-3 and Omega-6 fatty acids, which are sensitive to heat, begin to oxidise and break down
- Trans fatty acids are formed — the same trans fats associated with cardiovascular disease. Industrial deodourisation is one of the main sources of trans fats in vegetable oils, even in oils not subjected to hydrogenation.
- Oxidation by-products (aldehydes, ketones, hydroperoxides) are created and may remain in the oil
The oil emerges odourless, colourless, and flavourless. It is also largely stripped of nutrition and may contain new compounds that were not present in the original seed.
This is why refined oils "last longer." There is nothing left in them to go bad. Antioxidants go rancid. Remove the antioxidants, and the oil appears stable — but it is not nourishing. It is inert.
Step 6 — Winterisation (sometimes)
Some oils undergo a final step where they are chilled to remove waxes and saturated fats that would cause the oil to cloud at refrigerator temperatures. This is cosmetic — it makes the oil look clear and "pure" even when cold.
What's lost: Natural waxes, some saturated fatty acids.
What You End Up With
After all six steps, the oil in that bottle is:
| What was there | What remains |
|---|---|
| Natural antioxidants (Vit E, polyphenols) | Largely destroyed |
| Phospholipids | Removed |
| Phytosterols | Significantly reduced |
| Natural flavour & aroma | Completely removed |
| Carotenoids & colour pigments | Removed |
| Intact fatty acid chains | Partially degraded |
| Trans fatty acids | Newly created during deodourisation |
| Hexane solvent residues | Trace amounts may remain |
The oil is technically safe to consume. It will not immediately harm you. But it has been converted from a complex, living food into a stripped, processed fat with a fraction of its original nutritional value — and some new compounds that weren't there to begin with.
The Foam Question — Answered
One of the most common complaints about cold-pressed oils is that they foam when used for deep frying. Many people assume this means the oil is "impure" or "bad quality."
The opposite is true.
The foam comes from natural phospholipids and trace moisture — the same compounds that the refining process deliberately removes in Step 2. When these phospholipids hit high heat, they create foam at the surface.
Refined oils don't foam because those compounds have been stripped out.
Foam = the oil still has its natural composition intact.
The foam settles within a minute or two and causes no harm to food or health. Skim it if you prefer. But see it for what it is: proof that the oil hasn't been through an industrial stripping process.
What Cold-Pressed / Wood-Pressed Oils Preserve
When oil is extracted mechanically at low temperatures — the traditional chekku method — none of the above steps occur.
The seed is pressed. The oil flows out. It is filtered. That's it.
What you get:
- Full Vitamin E content — acts as a natural antioxidant, extends shelf life naturally
- Natural phospholipids — intact and beneficial
- Phytosterols — supporting cardiovascular health
- Original flavour and aroma — the oil tastes like what it came from
- Zero solvent residues — because no solvents were used
- No trans fats created in processing — because no high-temperature deodourisation occurred
- Natural colour — because the pigments and carotenoids are still there
This is why cold-pressed oils look different, smell different, and taste different. They haven't been processed into uniformity.
The Shelf Life Illusion
Refined oils last two to three years on a shelf. Cold-pressed oils last six to twelve months (less if stored poorly).
This is often used as an argument against cold-pressed oils. It is actually an argument against refined ones.
The reason refined oil lasts so long is that the natural antioxidants — which prevent rancidity — have been removed. Without them, there is very little left in the oil that can oxidise and go bad. The oil is not "stable." It is empty.
Cold-pressed oil contains natural antioxidants that do eventually oxidise. That oxidation is normal. The antioxidants sacrificing themselves to protect the oil are doing their job. They will oxidise before the oil itself does.
Store cold-pressed oil correctly (cool, dark, airtight) and it lasts well within its natural shelf life without any compromise to quality.
How to Use Cold-Pressed Oils Correctly
The one genuine limitation of cold-pressed oils is a lower smoke point than refined versions. Here's how to work around it:
| Cooking Method | Best Cold-Pressed Choice |
|---|---|
| Deep frying | Coconut oil (highest SFA, most stable) |
| Stir frying | Groundnut oil (high MUFA) |
| Tempering / tadka | Sesame (gingelly) oil |
| Medium heat curry | Groundnut or sesame |
| Dressings / finishing | Sesame oil |
| Baking / sweets | Coconut oil |
The key: don't overheat. Cold-pressed oils do not need to smoke to cook. Most traditional South Indian cooking — slow tempering, medium flame curries — is well within the comfortable range of cold-pressed oils.
A Simple Test
Open a bottle of refined sunflower oil. Smell it. Nothing.
Now open a bottle of cold-pressed groundnut oil. You'll smell the groundnut. Open cold-pressed sesame oil. You'll smell the sesame.
That smell is not "impurity." It is the oil telling you it still has something to offer.
When an oil smells like nothing, it has had everything removed.
Final Thought
The refining process was not designed to make oil healthier. It was designed to make oil cheaper to produce, longer to store, and uniform enough to sell at scale. Those are industrial goals, not nutritional ones.
Traditional cold-pressing existed for thousands of years before industrial refining. It produced oils that generations of people cooked with every day without the chronic diseases that dominate modern life.
The process hasn't changed. The oil hasn't changed. Only the industrial alternative has been added — and marketed as an improvement.
At Zhagaram, we press every batch the traditional way. No solvents, no bleaching, no deodourisation. Just seeds, pressure, and time.
Explore our range of wood-pressed oils at zhagaramwellness.com