A Primer on Cooking Oils

Oils used for cooking are at the very core of culinary art. They are the foundation upon which many recipes are built and serve as a wonderfully varied palette from which all cooks, beginner or expert, can draw inspiration. They are also essential to health, providing the basic building blocks for metabolism and cell structure. All this, and they add delightful flavor too!

Fats and Your Health

Fats and oils are an integral and essential part of the human diet. For centuries, people all over the world have rendered fat, squeezed olives, collected cream, and savored fish to obtain the necessary fatty acids required by their brains, nervous system, immune system and body cells. Few people realize that our brains are made up mostly of fats, and that fats — including saturated fat — make up the cell membranes that protect the integrity of the cell and its structure. Fats and oils play a crucial role in stabilizing blood sugar levels, providing raw materials for making hormones, and contributing to a healthy immune system. Dietary fats are also notably important for the transport of the fat-soluble vitamins A, D, E and K, and they increase the absorption of other vitamins, minerals and phytonutrients.

Fat consumption varies greatly between cultures. The Inuit diet is high in fat, as is the celebrated Mediterranean diet where the percentage of calories from fat can reach up to 40%. The Japanese, on the other hand, exist perfectly well on a diet that is remarkably low in fat by Western standards. People have different needs for fats in their diet depending on a host of factors, including climate, activity levels, genetic background and age, but the consensus is that up to a third of your daily calories should be from fat. Since all fats, regardless of type, are high in calories, remember to not overindulge, especially if you lead a sedentary lifestyle. Let common sense play a role in determining how much fat you consume. If you are frequently hungry, you may need to add more fat to your diet. If you would like to lose some weight, you may need to cut back.

Low Fat or Right Fat?

Researchers are starting to realize that low fat diets are not a cure-all for disease prevention and weight loss. A significant study published in the Journal of the American Medical Association in early 2006 found that women eating a low fat diet had the same rates of heart disease and cancer as those who had no dietary fat restrictions after eight years. The evidence seems to indicate that instead of controlling or cutting fat, it is smarter to eat the right kinds of fat — primarily monounsaturated fats, along with adequate amounts of omega-3 fatty acids from fish and fish oils — while at the same time eliminating harmful hydrogenated fats and highly processed vegetable oils from your diet. As part of a balanced and varied diet, use a variety of oils, including oils from different sources and oils that contain different kinds of fatty acids. Do not use a single oil to the exclusion of all others-any food in excess is not recommended.

Refined or Unrefined?

Refined oil has been processed to make it more stable and suitable for high temperature cooking. The refining process also removes most of the flavor, color and nutrients. Refined oils are good for baking and other uses where a bland flavor is desirable and their stability and high smoke point makes them essential for high-heat applications like stir-fry.

Unrefined oil is simply pressed and bottled, retaining its original nutrient content, flavor and color. Depending on the oil, filters are sometimes used to remove impurities. The compounds that give unrefined oils their unique flavor and character also shorten their shelf life and limit their cooking applications. Unrefined oils add full-bodied flavor to dishes and are best used for low heat cooking or for sauces, dressings, marinades and dipping.

Expeller Pressed, Cold Pressed or Solvent Extracted?

Expeller pressing is a chemical-free mechanical process in which the oil in a seed or nut is forced out under pressure. This pressure, particularly when used on hard seeds or nuts, can generate heat due to friction. Therefore, some delicate oils are cold pressed, which simply means the expeller pressing is done under controlled temperatures, typically below 120 degrees F. Expeller pressed oils are among the most health-promoting oils available.

Solvent extraction: Many high-volume conventional vegetable oil manufacturers use chemical solvents like hexane along with high heat (500°F) and harsh bleaching methods to remove beneficial nutrients along with the flavor, resulting in an overly bland oil with few, if any, culinary or health attributes. Solvent extracted oils have been in the food supply a relatively short time. They are generally low quality, highly processed oils devoid of nutrients and with an unnaturally long shelf life. The fat equivalent of white sugar, they are not recommended for any kitchen application.

Storing and Utilizing Oils

Oils, unlike wine, do not improve with age. Heat and light are especially harmful, so most oils, particularly polyunsaturated oils, should be kept in the refrigerator. Never store cooking oils by the stove. Highly saturated oils, which include most tropical oils, are quite stable and may be kept at room temperature, though refrigeration certainly won't harm them and will extend their useful life. Some oils, olive oil among them, become cloudy and may solidify when refrigerated but this does not affect quality. Usually, just a few minutes at room temperature will restore oils to their liquid state.

If improperly stored (exposed to excessive heat, light or air) or kept too long, oils eventually become rancid, with a characteristic bad taste and smell. Discard rancid oils immediately, since they are the worst kinds of fat you can consume. Heating oils beyond their smoke point is also undesirable. The smoke point is the temperature at which the oil begins to smoke, generating toxic fumes and harmful free radicals. Always discard oil that has reached its smoke point, along with any food in contact with it. Read the label of a particular oil to determine its smoke point, and never heat the oil higher than this temperature. In general, refined oils will have a higher smoke point than unrefined oils.

Shopping tip: Purchase cooking oils in small quantities, especially the more fragile polyunsaturated oils. A large bottle of oil at a good price is no bargain if you end up throwing most of it away. Alternatively, share bottles of premium specialty oils with friends.

Cooking Oils and WFM Quality Standards

The single most important factor in choosing any cooking oil is quality. If you have a choice, select organic, expeller-pressed oils to ensure maximum purity, flavor and nutrition. Choosing organic oils may minimize your exposure to pesticides, many of which are fat soluble. At Whole Foods Market, all stand-alone cooking oils are expeller pressed with the exception of grapeseed oil, which is not readily available expeller pressed.

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