There are many types of cooking oils, typically divided into two broad categories:
Animals oil: Examples are butter and lard which have high content of saturated fatty acids and may have adverse effect on health if taken in large consumption.
Vegetable oil: Examples are olive oil, canola oil, corn oil and peanut oil. They contain unsaturated fatty acids and are a healthier diet choice. Vegetable oils are usually good for health only when the composition of saturated fatty acids is low. Some vegetable oils such as coconut oil and palm oil have a higher saturated fatty acid composition. The same goes with margarine and vegetable shortenings which also have a high trans fatty acids content.
The major difference in cooking oils lies in their fatty acid compositions. There are three main types of fatty acids: trans fatty acids or trans-unsaturated fatty acids, saturated fatty acids and unsaturated fatty acids. Trans fatty acids and saturated fatty acids are called the “bad fatty acid” because it raises the level of low-density lipoprotein (LDL) cholesterol. High levels of LDL cholesterol increase our risk of heart disease and is therefore known as “bad” cholesterol. Unsaturated fatty acids are referred to as “good fatty acid” because it carries “good’ cholesterol, that is high-density lipoprotein (HDL) cholesterol. High levels of HDL help lower LDL cholesterol and reduce the risk of heart disease.
All cooking oil is high in fat and calories. To avoid consuming too many calories and gaining weight, not more than 2 teaspoons of cooking oil for each meal is recommended. Pick a healthy type of cooking oil and also the right way to cook to reduce oil consumption such as steaming, boiling, poaching and baking.
Olive Oils are generally categorised as extra virgin olive oil, virgin olive oil, pure olive oil and light olive oil.
Extra Virgin Olive Oil (EVOO) is extracted from crushing freshly harvested olives within 24 hours in room temperature. The acidity value reflects the quality of the oil and EVOO must have less than 0.8% acidity per 100g which allows it to preserve the natural aroma and flavor of olives. The polyphenols, natural antioxidant of EVOO helps prevent heart disease.
However, EVOO has a low smoking point and is therefore not suitable for high-heat cooking such as pan-frying, deep-frying, oven baking, etc. It can be used in salads and for low-heat cooking.
Like EVOO, virgin olive oil also comes from first pressing. The difference between the two is the level of acidity. Virgin olive oil is over 0.8% acidity per 100g. It has slightly lower flavour intensity but still remains the nutritional benefits.
Pure Olive Oil is refined oil, which is produced after high heat and chemical processing. This process removes much of the colour and flavour as well as antioxidant of olives. The nutritional benefit is lower than EVOO and virgin olive oil. Pure Olive Oil has a light color and mild flavor. However, its higher smoking point allows it to be used for grilling and frying.
“Extra-light” refers to the amount of flavour in the oil and not the calories or fatty contents. As it is refined oil, it has lost a large part of the nutritional values of antioxidants and the natural flavor of olives. Compare to other type of olive oil, the price of extra-light olive oil is lower and can be used in high-heat cooking.
The name of Canola oil originates from “Canadian oil, low acid” and is derived from canola plant which is a hybridized version of the rapeseed. It is however not rapeseed oil. Canola oil has the relatively lowest content of saturated fatty acids among all kinds of cooking oils, and the unsaturated fatty acids level is a little less than olive oil. It is suitable for use in all cooking methods.
Corn oil is a vegetable oil extracted from the germ of corn. It has rich polyunsaturated fatty acids and is suitable for low-heat frying.
Peanut oil is made from peanuts and contains a strong flavour. It is an all-purpose oil suitable for all types of cooking methods.
Tips for buying and storage
With so many cooking oil options, find the ones that suit your family cooking styles.
Be aware of the smoking point of cooking oils as it is an important factor to determine whether they are suitable for high-heat or low-heat cooking.
Compare different brands of oils of the same type and choose the ones with lighter colour, lighter texture and lower viscosity.
Do not repeat the use of oils which have been used for cooking.
Check the label on the cooking oil container for the expiry date. Keep the cooking oil away from heat and sunlight and consume within 3 months after it is opened.