When oil is overheated, it breaks down into glycerol and free fatty acids and produces bluish smoke. It marks the beginning of degradation of both flavour and nutrition.
“The temperature at which oil gets overheated and starts emitting smoke is called the smoke point.”
The smoke point for each oil varies widely depending on its origin and refinement. Vegetable- based oil have higher smoke points than animal-based fats like butter or ghee. Any oil’s smoke point does not remain constant overtime. The more refined an oil, the higher the smoke point. That’s because refining removes the impurities that can cause the oil to emit smoke. If the smoke point drops, oil smokes faster and toxic chemicals are released at this point. When each time you reuse the oil, the smoke point drops. When you deep fry food, the oil temperature is 190’C. It means that when oil is reheated, it produces some cancer-causing chemicals.
| Smoke point for Different Oils | |
| Canola oil (unrefined) | 107’C |
| Canola oil (semi refined) | 240’C |
| Canola oil (Refined) | 243’C |
| Sunflower oil (unrefined) | 107’C |
| Sunflower oil (Refined) | 232’C |
| Corn oil (unrefined) | 160’C |
| Corn oil (Refined) | 232’C |
| Groundnut oil (unrefined) | 160’C |
| Groundnut oil ( Refined) | 232’C |
| Olive oil (Extra virgin) | 160’C |
| Olive oil (Extra light) | 243’C |
| Butter | 177’C |
