Cooking oils
Cooking oil is plant, animal, or synthetic fat used in frying, baking, and other types of cooking. It is also used in food preparation and flavouring that doesn't involve heat, such as salad dressings and bread dips, and in this sense might be more accurately termed edible oil.
Cooking oil is typically a liquid, although some oils that contain saturated fat, such as coconut oil, palm oil and palm kernel oil, are solid at room temperature.
Types of cooking oil include:
- olive oil
- palm oil
- soybean oil
- canola oil (rapeseed oil)
- pumpkin seed oil
- corn oil
- sunflower oil
- safflower oil
- peanut oil
- grape seed oil
- sesame oil
- argan oil
- rice bran oil
- and other vegetable oils, as well as animal-based oils like butter and lard
Oil can be flavoured with aromatic foodstuffs such as herbs, chillies or garlic.
Cooking with oil:
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.
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 or 446 °F) because of their high smoke point.
- Avocado oil
- Mustard oil
- Palm oil
- Peanut oil (marketed as "groundnut oil" in the UK and India)
- Rice bran oil
- Safflower oil
- Semirefined Sesame oil
- Semirefined Sunflower Oil
Storing and keeping oil:
Whether refined or not, all oils are sensitive to heat, light, and exposure to oxygen. Rancid oil has an unpleasant aroma and acrid taste, and its nutrient value is greatly diminished. To delay the development of rancid oil, a blanket of an inert gas, usually nitrogen, is applied to the vapor space in the storage container immediately after production. This is referred to as tank blanketing. Vitamin E oil is a natural antioxidant that can also be added to cooking oils to prevent rancidification.
All oils should be kept in a cool, dry place. Oils may thicken, but they will soon return to liquid if they stand at room temperature. To prevent negative effects of heat and light, oils should be removed from cold storage just long enough for use. Refined oils high in monounsaturated fats keep up to a year (olive oil will keep up to a few years), while those high in polyunsaturated fats keep about six months. Extra-virgin and virgin olive oils keep at least 9 months after opening. Other monounsaturated oils keep well up to eight months, while unrefined polyunsaturated oils will keep only about half as long.
In contrast, saturated oils, such as coconut oil and palm oil, have much longer shelf lives and can be safely stored at room temperature. Their lack of polyunsaturated content causes them to be more stable.