DIFFERENT TYPES of Oils & Fats

Remember that all oils are fats, but not all fats are oils. They are very similar to each other in their chemical makeup, but what makes one an oil and another a fat is the percentage of hydrogenation in the fatty acids of which they are composed.

The fats and oils which are available to us for cooking are actually mixtures of differing fatty acids so for practical purposes saturated fats are solid at room temperature (70 F) and unsaturated fats we call oils are liquid at room temperature.

For dietary and nutrition purposes fats are generally classified as saturated, monounsaturated and polyunsaturated, but this is just a further refinement of the amount of saturation of the particular compositions of fatty acids in the fats.

Olive Oil
Make sure you buy the extra-virgin varieties. Extra virgin means that it is directly pressed from the olives, which means it has not gone through any harsh processing and will contain the highest level of antioxidants and flavor.

Coconut Oil
Coconut oil has been a subject of controversy in the past years. We have found that even though this oil contains a high percentage of saturated fats, it is actually a good choice for an oil. You may ask why? The fats in coconut oil are in the form of medium-chain fatty acids, which are known to increase metabolism and are digested and absorbed better than other fats. In other words, most of the saturated fat in coconut oil is easily digestible and converted into quick energy. These types of fatty acids are less likely to cause obesity because they are immediately used by the body and have no opportunity to be stored. Coconut oil is also great for cooking because it does not degrade as quickly as other oils when heated to high temperatures. But beware – bad forms of coconut oil still exist! Stay away from the processed, hydrogenated coconut oil typically used in processed foods. Use organic and unprocessed coconut oil that you purchase from a reputable source online or at your local health food store.

Canola Oil
Canola oil is made from rapeseed, which is a relative of the mustard seed. Canola oil contains high levels of monounsaturated fat, and has the least amount of saturated fat of the oils besides olive oil. Try to buy organic and expeller pressed varieties. Chemicals are typically used to extract the oil and pesticides are sprayed on the rapeseed, so buy organic!

Butter
Butter can also be used for cooking and is MUCH healthier than margarines which contain chemicals and hydrogenated trans fats. Margarine takes oils and converts them to solids. This process involves changing the chemical structure of the oil, thereby rendering it a "bad fat." Avoid all margarines or imitation butters. Again, buy organic, natural butter.

Grape seed Oil
This oil is great for cooking at really high temperatures, particularly, for example, when stir-frying and sautéing. The only concern for this oil is that it contains more polyunsaturated fat than monounsaturated oils, therefore, use small amounts.

Sesame Oil
Sesame oil is great for cooking Asian or Middle Eastern dishes. Sesame oil all is not an oil that you want to use all of the time because of the polyunsaturated fats, but you can use it moderately for certain dishes. We find that adding a teaspoon for flavor works wonders!

Peanut Oil
This oil has 50 percent monounsaturated fats, but contains 30 percent polyunsaturated fats. Only use this oil occasionally. Buy the expeller-pressed varieties.

Corn Oil
Try to avoid this oil because it is super high in polyunsaturated fats. Do not deep fry with this oil. The corn oil will foam and smoke at high temperatures. These fumes can be toxic!

Soybean Oil, also known as Vegetable Oil
This is probably the most used and cheapest of all oils. Soybean oil is pretty high in polyunsaturated fat for regular consumption. Spend a little extra money on getting the right oil especially if you are cooking a lot.

Nut Oil (hazelnut or Walnut)
These oils are used in seasonings, salads, and cold dishes and can add a lot of flavor. Walnut oil is not a cooking oil; high heat destroys its delicate flavor. Where it does shine is as an ingredient in a salad dressing or a fresh pasta sauce or to give a final zip to a finished dish. These oils also typically go rancid very quickly, so do not purchase them in large quantities.

Speaking of rancidity, let’s take a quick look at buying and storing oils.


Buying & Storing Oils & Fats

Fats and oils go rancid rather quickly, therefore storage becomes an issue. Rancid fats have been implicated in increased rates of heart disease, atherosclerosis and may be carcinogenic (cancer causing) so we want to avoid them if at all possible.

Oxygen is eight times more soluble in fats than in water and it is the oxidation resulting from this exposure that is the primary cause of rancidity. The more polyunsaturated a fat is, the faster it will go rancid. This may not, at first, be obvious to your nose (rancid fats smell terrible) because vegetable oils have to become several times more rancid than animal fats before our noses can detect it. An extreme example of rancidity is flaxseed that we use as a wood finish and a base for oil paints. In just a matter of hours the oil oxidizes into a solid polymer. This is very desirable for wood and paint, very undesirable for food.

Long term storage of fats may be problematic, but it is not impossible. There are some general rules you can follow to get the most life out of your stored cooking oils and fats.

1. Limit exposure to oxygen, light and heat, as these are the greatest factors leading to rancidity. If you can, refrigerate your stored oil, particularly after it's been opened. If possible, buy your oils in opaque, airtight containers. If you purchase them in plastic, particularly clear plastic, then transfer them to a glass container that can be sealed airtight. Transparent glass or plastic containers should be stored in the dark, such as in a closed cupboard or within a box. Regardless of the storage container, it should be stored at as cool a temperature as possible and rotated as fast as is practical. Oils and fats with preservatives added by the manufacturer will have a greater shelf life than those without them, provided they are fresh when purchased. However, we recommend purchasing organic, fresh oils without preservatives.

2. Use your oils! Unless they have been specially treated, unopened cooking oils typically have a shelf life of about a year, depending upon the above conditions. Some specialty oils such as sesame and flax seed have even shorter usable lives. If you don't use a great deal of it, try not to buy your fats in large containers. This way you won't be exposing a large quantity to the air after the bottles have been opened, allowing them to grow old and possibly rancid, before you can use it all up. Once opened, it is an excellent idea to refrigerate cooking fats. If it turns cloudy or solid, the fat is still perfectly usable and will return to its normal liquid, clear state after it has warmed to room temperature. Left at room temperatures, opened bottles of cooking oils can begin to rancid in anywhere from a week to a couple of months, though it may take several more months to reach such a point of rancidity that it can be smelled.