How to Clean and Reuse Frying Oil
Master the cornstarch slurry technique to bind burnt particles, clarify cloudy deep-frying oil, and safely store it for multiple clean cooking cycles.
This guide shows how to clean and reuse frying oil in 30 minutes. Start with cool and coarsely strain the oil; follow the safety notes and step checkpoints below.
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🧰 Required Tools & Equipment
- ✓ Fine-mesh wire strainer
- ✓ Stainless steel saucepan
- ✓ Heatproof glass jar
- ✓ Whisk
- ✓ Heatproof silicone spatula
- ✓ Funnel
📦 Materials & Supplies
- ✓ Used cooking oil
- ✓ Cornstarch
- ✓ Water
- ✓ Coffee filters
⚠️ Safety Checkpoints & Warnings
- • Allow hot oil to cool below 200°F (93°C) before adding any liquid mixture to prevent violent steam explosions.
- • Maintain low-to-medium heat while simmering the slurry to prevent oil from splattering.
- • Inspect the oil for signs of deterioration like rancid odor, dark sludge, or persistent surface foam, which require disposal.
📋 Step-by-Step Guide (6 Steps)
Cool and Coarsely Strain the Oil
Allow your used cooking oil to cool down from frying temperature until it reaches approximately 180°F to 200°F. Place a fine-mesh strainer over a clean saucepan and pour the warm oil through to catch large fried debris. Discard the collected food chunks in your trash bin rather than rinsing them down the drain.
- • Large crumbs, batter bits, and floating debris are removed from the oil.
- • Oil sits warm and liquid in the saucepan with no large suspended solids.
- • Pouring boiling hot oil through fine mesh, which can warp utensils or cause severe splash burns.
Mix the Cornstarch Slurry
In a small bowl, whisk together equal parts cornstarch and room-temperature water based on your oil volume. Use approximately 1 tablespoon of cornstarch and 1 tablespoon of water for every cup of used oil. Whisk continuously until the starch is completely dissolved with zero dry clumps remaining at the bottom.
- • A smooth, opaque, milk-like slurry with no sediment stuck to the bowl bottom.
- • Using warm water, which causes the cornstarch to clump instantly before mixing.
Whisk Slurry into Warm Oil
Pour the prepared cornstarch slurry directly into the warm oil inside the saucepan. Whisk vigorously for 30 seconds to thoroughly disperse the starch water throughout the oil. The mixture will temporarily look cloudy, milky, and fragmented as the water and oil interact.
- • Milky cornstarch droplets are evenly distributed throughout the pot.
- • Adding the slurry to scalding hot oil, which causes instant splattering.
Simmer to Form the Starch Disc
Place the saucepan over low-to-medium heat and stir slowly using a heatproof silicone spatula. As the mixture heats up, the water will gently evaporate and the cornstarch will gelatinize into a spongy matrix, sweeping up microscopic burned particles. Continue moving the forming mass around the pan until it congeals into a firm, brownish curd and the surrounding oil clears up.
- • A single rubbery gelatinous blob gathers all burnt micro-particles.
- • Surrounding oil turns visibly transparent and bright.
- • Setting heat too high, which burns the starch mass to the bottom of the pan.
Remove Curd and Perform Final Filtration
Lift the congealed starch disc out of the pot using your spatula or a slotted spoon and discard it in the trash. Place a funnel lined with a paper coffee filter inside the neck of a clean, completely dry heatproof glass jar. Slowly pour the clarified oil through the filter to catch any remaining micro-particles.
- • Golden, clear oil filters slowly through the paper into the glass jar.
- • No dark sediment settles at the bottom of the collection jar.
- • Pouring oil into a wet jar, which introduces moisture that causes oil degradation and dangerous popping upon next use.
Seal and Store for Next Use
Let the clarified oil come to complete room temperature before screwing on the airtight lid. Label the jar with the date and the type of food previously cooked in it, such as fish or chicken. Store the sealed jar in a cool, dark cabinet or the refrigerator to prevent oxidation.
- • Lid is tightly sealed on a fully cooled, labeled jar of transparent oil.
- • Storing oil near heat sources like the oven, which speeds up rancidity.
Credit: inspired by an original tutorial by morocooks — watch the original on YouTube.
Don’t have everything?
- No Paper coffee filter? Layer of clean paper towels or cheesecloth set inside a mesh sieve
- No Cornstarch? Tapioca starch or potato starch mixed with water in equal parts
- No Heatproof silicone spatula? Wooden spoon or heat-resistant metal slotted spoon