Cooking with oils
Heating an oil changes its characteristics. Oils that are healthy at room temperature can become unhealthy when heated above certain temperatures. When choosing a cooking oil, it is important to match the oil’s heat tolerance with the cooking method.
A 2001 parallel review of 20-year dietary fat studies in the United Kingdom, the United States of America, and Spain found that polyunsaturated oils like soya, canola, sunflower, and corn oil degrade easily to toxic compounds when heated. Prolonged consumption of burnt oils led to atherosclerosis, inflammatory joint disease, and development of birth defects. The scientists also questioned global health authorities’ recommendation that large amounts of polyunsaturated fats be incorporated into the human diet without accompanying measures to ensure the protection of these fatty acids against heat- and oxidative-degradation.
Palm oil contains more saturated fats than canola oil, corn oil, linseed oil, soybean oil, safflower oil, and sunflower oil. Therefore, palm oil can withstand the high heat of deep frying and is resistant to oxidation compared to highly unsaturated vegetable oils. Since about 1900, palm oil has been increasingly incorporated into food by the global commercial food industry because it remains stable in deep frying or in baking at very high temperatures and for its high levels of natural antioxidants.
Oils that are suitable for high-temperature frying (above 230 °C/446 °F) because of their high smoke point
Peanut oil (marketed as “groundnut oil” in the UK)
Rice bran oil
Sesame oil (semi-refined)
Oils suitable for medium-temperature frying (above 190 °C/374 °F) include:
Diacylglycerol (DAG) oil
Ghee, Clarified butter
Grape seed oil
Olive oil (Virgin, and refined)
Rapeseed oil (marketed Canola oil or, sometimes, simply “vegetable oil” in the UK)