For a household this is a matter of taste. For a kitchen going through litres a day it is a cost and consistency decision, and the two oils behave differently enough that picking the wrong one shows up in both the food and the monthly bill.
We currently manufacture mustard oil ourselves; our refined soya oil is out of stock at the moment. Take the comparison below as general guidance rather than a sales pitch either way.
The short answer
Refined oil for high-volume frying. Mustard oil where the dish is supposed to taste of mustard oil. Most kitchens serving North Indian food end up stocking both, using refined for the fryer and mustard for curries, tempering and pickles.
Flavour carry-over, the deciding factor for most kitchens
Refined oil is stripped of colour, odour and flavour by design. Nothing of the oil reaches the plate, which is exactly what you want in a fryer running samosas, pakoras and puris through the same batch of oil all day.
Mustard oil is the opposite. Its pungency survives cooking and is a component of the dish. In a fish curry, a sarson da saag or an achaar that is the whole point. In a fryer handling mixed items it means yesterday’s flavour turning up in today’s.
Smoke point and how long the oil lasts in a fryer
Refined oils sit high, around 220 to 230 degrees, because refining removes the free fatty acids and fine particles that break down first. That is why refined oil survives repeated frying cycles better and needs replacing less often.
Mustard oil has a respectable smoke point for an unrefined oil, which is why it works well for shallow frying and tempering. It is not the right choice for a deep fryer running continuously.
Oil that degrades faster is oil replaced sooner. At volume that difference is usually larger than the difference in purchase price.
Cost per litre
Refined soya is generally the more economical option at volume, which is a large part of why it dominates commercial frying. Mustard oil is bought for its character rather than its cost, and kitchens using it are usually using it in smaller quantities per dish.
Both move with commodity markets, so a rate quoted today is valid for a short window. That is why we quote rather than publish prices.
How kitchens usually split it
- Deep fryer: refined, for smoke point, cost and neutrality.
- Curries and gravies in North Indian menus: mustard, for character.
- Tempering: mustard, where the cuisine calls for it.
- Pickling: mustard, almost always, often unheated.
- Sweets and bakery: refined, or ghee where the recipe demands.
- Mixed or continental menu: refined as the default.
Storage, which matters more at volume
Both keep best sealed, cool and out of direct light. The common mistake in commercial kitchens is storing tins beside the range, where ambient heat shortens the life of the oil considerably.
Mustard oil has the additional consideration that repeated air exposure dulls the pungency it was bought for. Kept closed between uses, it holds.
What we supply
We fill and seal mustard oil in our own unit at Batala, Punjab. Mustard oil runs 500ml to 15L tins with distributor cartons. Our refined soya oil is out of stock at the moment; message us for an update on availability.
If you are choosing across the wider range of oils rather than just these two, our guide to choosing a cooking oil covers the rest.