Yes, once, if it is handled properly and used soon. FSSAI’s household guidance says oil left over from frying can be filtered and used for making curries, and should be consumed within a day or two. It should not be used again for deep frying over and over, and it should be thrown out as soon as it turns dark, thick, foamy, or smoky. For restaurants and food businesses, there is a hard limit: oil whose Total Polar Compounds (TPC) exceed 25 percent must not be used.
Here is what that means in a home kitchen.
Reuse cooking oil: Why frying oil changes
When oil sits in a hot kadhai, three things happen together. Oxygen reacts with the fats, water from the food breaks some fats apart, and high heat links the broken pieces into new compounds. Food crumbs burn and speed all of this up. Chemists group many of these breakdown products under the name Total Polar Compounds, and the percentage of TPC is the most widely used measure of how far a frying oil has deteriorated.
Fresh oil has a low TPC. Every frying session pushes it higher, and reheating already-used oil pushes it higher faster. FSSAI notes that TPC rises quickly once oil has been reused several times, and has set 25 percent as the point beyond which vegetable oil is unfit for use. The ICMR-NIN Dietary Guidelines for Indians (2024) also advise against reheating and reusing oil.
Home cooks cannot measure TPC without a meter, so the practical approach is to limit reuse and watch for the warning signs below.
FSSAI’s household rules, in plain terms
FSSAI’s guidance note on handling used cooking oil sets out a few simple rules for households:
- Avoid repeated use of oil for frying. The ideal is to fry once.
- Filter leftover oil and use it for curry preparation, where it is heated gently, instead of frying with it again.
- Use leftover oil within a day or two. Used oil deteriorates faster than fresh oil, so it should not be stored for long.
- Discard oil that shows warning signs (listed below).
- Never pour discarded oil into drains or sewer lines.
Following these steps gets the value out of your oil without letting it degrade.
Signs your oil should go in the bin
Discard the oil if you notice any of these, which are the signs FSSAI lists:
- Blue-grey smoke at normal frying heat
- A tough foam that forms and will not settle
- The oil has turned dark and murky
- The oil has become noticeably thicker or sticky
- A sharp, stale or “painty” smell
If you are unsure, throw it out. The cost of a little oil is small.
How to save leftover oil for one more use
If the oil looks and smells fine after a single frying session, handle it like this:
- Let it cool completely in the kadhai. Never pour hot oil.
- Strain it through a fine steel strainer lined with muslin or a clean cotton cloth to remove crumbs and batter bits. These particles burn next time and speed up spoilage.
- Store it in a separate, clean, dry container with a tight lid. Keep it apart from your fresh oil bottle, and avoid pouring used oil back into it.
- Label it with what was fried, because oil used for fish will flavour your next dish.
- Keep it away from light and heat, and use it within a day or two for tadka or sabzi.
Which oils hold up better
Oils rich in monounsaturated or saturated fat, such as groundnut, mustard and coconut oil, break down more slowly than oils dominated by polyunsaturated fat, such as regular sunflower oil. Gingelly oil also holds up reasonably well because of its natural antioxidant compounds. A stable oil buys you some margin, and it does not make endless reuse safe. Our guide to the best oil for deep frying compares them, and the smoke points guide has the numbers.
Ways to use less oil in the first place
The easiest way to avoid a reuse problem is to have less leftover oil.
- Use a smaller, deeper kadhai. You need less oil to reach frying depth.
- Fry in batches instead of filling the kadhai, so the temperature stays steady and food absorbs less oil.
- Measure what you need. For four people, a few puris or a plate of pakoras rarely needs a full litre.
- Shallow fry or pan roast where the dish allows it.
Our article on cooking with less oil without losing flavour has more ideas.
How to dispose of used oil
Oil poured down the sink cools, sticks to pipes and blocks drains and sewers. Instead:
- Let it cool, pour it into a sealable bottle or container, and put it in dry waste.
- Small amounts can be soaked up with newspaper or sawdust before disposal.
- Under FSSAI’s RUCO (Repurpose Used Cooking Oil) initiative, registered aggregators collect used oil from food businesses for conversion into biodiesel and soap. Some cities and resident welfare associations run household collection drives too, so check locally.
A note for street food and restaurant oil
Most worry about reused oil comes from food bought outside, where the same oil may be topped up and reused for days. Food businesses that use large quantities of oil are required to monitor TPC and hand used oil to authorised collectors. As a customer, very dark oil, heavy smoke and a bitter aftertaste are signs to choose somewhere else.
Frequently asked questions
How many times can cooking oil be reused?
FSSAI’s guidance is to avoid repeated frying in the same oil. At home, the practical rule is to fry once, then use the filtered leftover gently for curries within a day or two.
Is it safe to reuse oil after frying fish?
It can be reused once for similar dishes, though it will carry the fish flavour. Strain it well and use it soon.
Can I mix used oil with fresh oil?
Avoid it. Used oil contains breakdown products that speed up the deterioration of the fresh oil you add.
Does reusing cold pressed oil work differently?
The same rules apply. Cold-pressed oils contain natural compounds that give flavour and aroma, and they still break down under repeated frying.
What is TPC in cooking oil?
Total Polar Compounds are breakdown products that form when oil is heated, especially repeatedly. FSSAI does not allow oil with more than 25 percent TPC to be used.
Fresh oil makes a difference. Buy the size your kitchen actually uses. Our cold-pressed groundnut oil and cold-pressed mustard oil come in small bottles as well as family packs.
