I learned my lesson about overheating oils in grade seven. My mom was in hospital getting surgery, leaving dad to run the kitchen.
My father has always been an ambitious man, so for his cooking debut, he decided to tackle sweet and sour pork. The wok was on the stove top, the pork prepped, the oil heating… and then the phone rang. This was before the advent of the cordless phone, so off he went to answer the phone. The shrill of the smoke detector brought him back to a huge fire on the stove top. Panicking, he took the nearby plastic cutting board and threw it on top of the flames, trying perhaps to smother the flames. Soon, thick black smoke filled our kitchen, which now needed repainting. Needless to say, I am yet to try my dad’s sweet and sour pork.
When choosing cooking oil, it is important to keep a few things in mind. Most oils sold in stores are highly refined. While this decreases nutrition, it does improve their shelf life and smoke point. Smoke point refers to the temperature at which an oil starts to break down. Both smoking and rancid oil have higher free-radical content, thought to damage cells and increase risk of certain diseases and cancers.
Rancid oil had a bad smell and should be discarded. While unrefined oils are more nutritious, they do have a lower smoke point and shelf life. Storing in the refrigerator will prolong them. The smoke point of oil varies, but here are some guidelines: If you plan on bringing oil to a high heat, such as for frying or deep-frying, your best choice are oils with a higher smoke point. These include refined sunflower, peanut, corn, ghee and olive pomace oil.
Oils with a medium-high smoke point, good for sauteing and baking, include grapeseed, canola and virgin olive oil. Cold-pressed extra-virgin olive oil, unrefined sesame oil, unrefined high-oleic sunflower oil and flaxseed oil have lower smoke points, and are more intended for salad dressings and finishing dishes. Their shelf life will be extended by refrigeration.
As I learned from my father, it is best not to let your cooking oil get too hot. Coincidentally, this follows Canada Food Guide recommendations of frying and deep-frying food less often.