Sources of cooking oils
Cooking oils are produced by pressing seeds, beans, fruit or nuts to extract natural vegetable oils. They perform the same function as fat in shallow and deep frying. Oils can also be used in baking, sauces and salad dressings.
Unrefined oils
These have been cold-pressed then left to mellow for a few months before being bottled. They tend to be cloudy but have good colour and flavour. They are often more expensive than refined oils.
Refined oils
These have been extracted under heat. They are then degummed, neutralised, heated, blanched and winterised to keep them from going cloudy and deodorised by an injection of steam. Sometimes artificial preservatives are added to replace those lost in processing.
Kilojoules
All fats and oils have about the same energy potential. One gram fat or oil yields about nine calories
Storage
Store oils in a cool, dark place. Make sure the oil is capped. Salad oils can be stored in the refrigerator. Because oils can become rancid, avoid buying bulk oil unless it is to be used quickly.
Frying
For best results, heat until a faint haze rises from the oil . Never allow it to smoke. When a cube of day-old bread turns golden and crisp in one minute then the temperature is right for frying.
A good oil can last up to five fryings. Strain after use. Do not allow the oil to smoke on re-heating. The smoke point decreases with the age of the oil. If dark or thick, discard. Old, dirty oil will affect the texture and flavour of fried foods.