Edible vegetable oils are derived from olives, canola, safflowers and sunflowers, to name just a few. Cooking oils are mostly liquid at room temperatures and are used in the commercial preparation of food, to fry foods and make salad dressings.
Saturated vs. unsaturated fat
Vegetable oils have been used for thousands of years for cooking purposes. The Chinese and Japanese have been producing soy oil since as 2000 B.C., and the southern Europeans started producing olive oil by 3000 B.C.
Read: Olive oil lowers blood pressure
The difference between vegetable oils and animal fat is that vegetable oil contains mostly polyunsaturated fats while animal fats contain monounsaturated fat and saturated fat. This is the reason why vegetable oils are fluid and animal fats are solid at room temperature.
Because vegetable oils have more polyunsaturated fats they react to oxygen more quickly than saturated fats and go rancid much more quickly than animal fats. This is the main reason why precautionary measures need to be taken to maintain safety and freshness:
- Always store oils closed in a cool, dark place (e.g. at the back of your kitchen cupboard) as oxidation (becoming rancid) may happen faster once opened.
- Frying (especially deep fat frying), changes the stability and quality of cooking oil, irrespective of the type of oil you use.
- Don’t overuse cooking oils (some fast food restaurants re-use oil; another reason to skip unhealthy take-away foods).
- Use oils quickly while they are still fresh.
- Replenish seed oils regularly, as exposure to oxygen and other chemical reactions can cause them to degrade.
- Canola oil is high in both PUFAs and MUFAs. It is suitable for frying, stir-frying, sautéing, salad dressings, salsas and marinades.
- Olive oil is more heat resistant than other types of oil. It’s suitable for cooking, salad dressings and in margarine.
- Use sunflower oil in moderation for cooking, shallow frying, salad dressings and making mayonnaise or marinades.
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