Mustard oil is the traditional cooking oil across North and East India, and it is also the one buyers ask the most questions about. What does kachi ghani on the label mean? Why is it so sharp? Why does it taste harsh sometimes and not others?
We press, filter and seal mustard oil in our own unit, so here is a plain explanation of all three.
What kachi ghani actually means
Ghani is the traditional wooden or steel expeller used to crush oilseed. Kachi means raw or uncooked. Together, kachi ghani describes oil pressed at low temperature without the seed being heated first.
The distinction matters because heating oilseed before pressing extracts more oil from the same quantity of seed. It is more efficient, and it is what most large-scale extraction does. But heat also drives off the volatile compounds that carry aroma and pungency.
Kachi ghani gives up some yield in exchange for keeping the character. That is the whole trade, and it is why cold-pressed mustard oil is sharper, darker and more aromatic than oil from a heated press.
It is worth knowing that the term is used loosely in the market. It describes a pressing method, not a guaranteed grade, and it is not by itself proof of purity.
Why mustard oil is pungent, and why that is the point
The sharpness that catches at the back of your nose comes from allyl isothiocyanate, a compound released when mustard seed cells break during pressing. It is the same family of compounds that makes wasabi and horseradish bite.
In most edible oils, a strong smell would signal a problem. In mustard oil it is the defining property. A sample that smells flat and bland is the one worth questioning, not the sharp one.
This is also why mustard oil does something no neutral oil can: it carries its character through cooking. In a fish curry, a sarson da saag or a pickle, that pungency is a component of the dish rather than a side effect of the cooking medium.
How to cook with it without the harshness
The most common complaint about mustard oil is that it tastes harsh or raw. Almost always, the cause is the same: the oil was not heated enough before the food went in.
Traditional practice is to heat mustard oil until it just begins to smoke, then let it cool slightly before cooking. That brief heating mellows the raw bite considerably while leaving the aroma intact. Cooks who skip it and add onions to barely-warm mustard oil get the raw sharpness right through the finished dish.
Beyond that it behaves like any cooking oil. It suits shallow frying, tempering, curries and pickling. For pickles it is often used unheated, because there the raw pungency is exactly what is wanted and it also helps the pickle keep.
Storing it properly
Sealed, cool and out of direct light. Heat and light are what turn an edible oil, and a bottle sitting beside the stove will deteriorate far faster than the same oil in a cupboard.
Unopened and stored properly it keeps well for months. Once opened, close it between uses: repeated air exposure is what dulls the pungency you paid for. If mustard oil has lost its sharpness, it has lost the reason it was chosen.
Judging quality as a buyer
Adulteration is a genuine problem in edible oil, and it is difficult to detect by eye. Colour alone tells you little, since it varies with seed and pressing.
Aroma is the most useful quick signal: real mustard oil announces itself. A sample that smells weak or generic deserves questions.
But the dependable answer is not a test, it is provenance. Buy from a supplier who presses or filters and seals under one roof, so the oil in the container is the oil they processed and nothing was opened in between. That is the reason we fill and seal our own, rather than buying finished oil and relabelling it.
Our mustard oil
We supply mustard oil in 500ml, 1L, 2L and 5L bottles and 15L tins, with distributor cartons in 500ml x24, 1L x12, 2L x6 and 5L x3. Filtered, filled and sealed at our unit in Batala, Punjab, and dispatched across India.
If you are weighing mustard against a neutral oil for a commercial kitchen, our guide to choosing a cooking oil covers that comparison in more detail.