Reusing cooking oil is a common practice in many kitchens, both domestic and commercial. It can be economical and environmentally friendly if done correctly. However, improper reuse of cooking oil can pose health risks. Here’s how to safely reuse cooking oil and not spoil your food or health while doing so.

Choose the right oil

Different oils have varying smoke points, which is the temperature at which they start to break down and produce harmful compounds. Oils with high smoke points, such as canola, peanut, and sunflower oil, are better suited for reuse as they can withstand higher temperatures without breaking down as quickly.

Strain the oil

After frying, let the oil cool down and then strain it through a fine mesh sieve or cheesecloth to remove food particles. These particles can burn during subsequent uses, affecting the taste and safety of the oil. Straining helps maintain the oil’s quality and extends its usability.

Store properly

Store used oil in a clean, airtight container to prevent exposure to air and light, which can accelerate oxidation and spoilage. Keep the container in a cool, dark place. Refrigeration can further extend the oil’s shelf life by slowing down the oxidation process.

Limit reuse cycles

Even with proper care, cooking oil should not be reused indefinitely. According to a study published in the Journal of Food Science and Technology, repeated heating of oil can lead to the formation of harmful compounds such as acrylamide and polycyclic aromatic hydrocarbons (PAHs), which are linked to cancer and other health issues . It’s generally recommended to reuse oil no more than three to four times, but this can vary depending on the type of oil and the cooking method.

Monitor for signs of spoilage

Before reusing oil, check for signs of spoilage. These include

• A rancid or off smell.
• A change in color to darker shades.
• A thick or sticky texture.
• Excessive smoking or foaming when heated.
• If any of these signs are present, it’s best to discard the oil.

Avoid mixing oils

Mixing different types of oils can lower the smoke point and affect the stability of the oil. Always reuse the same type of oil to maintain its quality and safety.