Culinary uses for oils:
• Deliver flavours to food (especially for stronger tasting nut and seed oils) eg. in dressings and in frying as oil is absorbed by the food; provides aroma
• Provides structure, aeration, creaming and mouthfeel. In baking, oils inhibit starch gelatinization, lubricate the dough and retain moisture and the gases released during baking. This contributes to a well risen loaf with a soft crumb. In emulsions such as creams, fats stabilize air bubbles.
• Avoid sticking and burning of food when sauteing
• Extend shelf life
In addition, from a nutritional health perspective
• Oils and fat provide an energy source, 45 calories per teaspoon regardless of type.
• Provide essentail fatty acids: Omega 3 and Omega 6
• Aid the adsorption of fat-soluble vitamins: vitamin A, D, E and K.
• Provide a sense of satiety after eating a meal.
How to choose an oil
• Expeller pressed vs solvent extracted
• Unrefined vs refined
• Smoke point based on culinary use – cooking vs salad oils
• Fatty acid profile – MUFA, PUFA and SFA
• Omega 3-Omega 6 ratio
But first, some science lessons.
How oil is produced and understanding labels
Expeller or mechnically pressed vs chemically or solvent extracted
Edible oils have been separated from oilseeds and oil-bearing fruits for thousands of years. The oilseeds are processed by one of two main ways: (1) expeller or screw press extraction, (2) solvent extraction.
Expeller-pressed oils are mechanically pressed from the seed without using chemical solvents. This method is normally applied to seeds that are relatively high in extractable oil such as olive, flax, avocado and walnut. They may be labeled as cold-pressed. In Europe, the term “cold pressed” is regulated and oils cannot exceed 90 degrees F or 32 degrees C. But in the US there is no such regulation so it may not guaranteed to be processed at fairly low temperatures.
However expeller pressing is not very efficient. Most typical mass market vegetable oils are extracted with solvents such as hexane, and at high temperatures. A typical process follows solvent extraction, degumming, refining, bleaching, winterisation and de-odourisation steps. This creates a refined and stabilized oil with a longer shelf life and higher smoke point. However, what you lose is the “naturalness” of the oil. Common oils processed this way are the vegetable oils – canola, corn, peanut, soybean, safflower, sunflower and grapeseed.
Unrefined vs Refined
Unrefined oils are filtered only to remove large particles. They may appear cloudy or have visible sediment after sitting. This does not compromise quality. Unrefined oils retain more nutrients and have more pronouned flavors, colors and fragrances than refined oils. Use unrefined oils unheated in cold dressings as their beneficial particles develop unhealthful properties if overheated.
Refined oils have been processed to remove impurities to make them more stable for longer storage, more resistant to smoking and a better choice for high-heat cooking. However the process of refining reduces the nutrient level and flavor. If you require a refined oil, buy a naturally refined oil, meaning that the oil is refined without harsh chemicals or solvents.
Oils decompose when heated to the smoke point and break down into their constituent glycerol and fatty acids. The smoke point refers to the maximum temperature before decomposition occurs. The presence of smoke indicates that glycerol has been hydrolyzed to acrolein, a mucuous membrant irritant and as its name implies, imparts an acrid smell and bitter taste. Acrolein is also found in cigratte smoke and is a carcinogenic agent. In addition to toxic chemical compounds, high temperatures also accelerate thermal oxidation of fatty acids and increases the formation of damaging free radicals. This is a double whammy as it renders the beneficial antioxidants useless after damage from high heat.
Smoke point should be the top priority for consideration if the culinary use is for high heat application, such as frying. Typically I do not fry much but when I do, I like to use avocado oil for sauteing, and macadamia oil or coconut oil for baking.
Smoke Point (°C) Smoke Point (°F) O6:O3 Color and Taste Best Applications
Avocado Oil 271 520 Monounsaturated (70%) – high in O9
High in fat-soluble vitamin E Vibrant green
Soft nutty flavor High heat – searing meat.
Hazelnut Oil 221 430 Monosaturated (75%; 78% O9)
No O3, Light brown
Rich nutty Med-High heat
Almond Oil 216 420 Polyunsaturated; O6 only
High in fat-soluble vitamin E Soft nutty Med-High heat
Macadamia Nut Oil 199 390 Monounsaturated (80%; 83% Omega-9)
1:1 Nutty buttery flavor Med
Sesame Oil 177 350 138:1 Dark
Rich and highly aromatic Small amounts
Coconut Oil 177 350 Saturated (86%; 66% MCTs)
Lauric acid has antibacterial, antioxidant, and antiviral properties Mild coconut flavor Med-High – baking, curries and soups. Potential allergen.
Hemp Seed Oil 165 330 3:1 Dark-Light green Dressings only
Walnut Oil 160 320 5:1 Medium-dark yellow color
Rich nutty Dressings only
Extra Virgin Olive Oil 160 320 73% monounsaturated, high in Omega 9 Wide range of flavors, depending on origin. Low
Dressings, cold dishes
Flaxseed Oil 107 225 1:4 (richest source of plant-based O3) Medium-dark golden color
Nutty Dressings only
Fatty acid profile: MUFA, PUFA and SFA
There are four types of dietary fight: polyunsaturated (PUFA), monounsaturated (MUFA), saturated (sat fat) and trans-fat. The fatty acid profile is my primary source of consideration after smoke point.
PUFAs and MUFAs are considered the healthy and recommended form of fats as they have been shown to decrease inflammation in the body and improve cholesterol levels and lipoprotein profiles. The body easily recognizes and uses these fats. PUFAs are found in vegetable oils, fish and seafood, and MUFAs in vegetable oils, nuts, seeds, olives and avocadoes.
Going a little more into detail on the PUFAs. Our bodies are not able to make PUFAs as thus referred to as essential fatty acids. Two forms are omega 3 (alpha-linolenic acid; ALA) and omega-6.
Omega-3 is found in coldwater fatty fish (tuna, mackerel, salmon) in the form of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), and cold-weather plants, nuts and seeds (flaxseed, walnut) in the form of ALA. ALA has a slightly shorter chain compared to EPA and DHA. What is a better source of Omega 3? Seafood or plant-derived? The popular press have been giving much attention to fatty fish as ALA is converted to a limited extent in humans to EPA. Nevertheless studies have suggested that our bodies can adapt to increase the efficiency of conversion. Non-fish eaters, vegans and vegetarians had approximately the same blood levels of EPA and DHA compared to regular fish eaters. In addition women displayed a higher conversion rate than men. Furthermore fish may have high amounts of heavy metals from water pollution, such as lead and mercury. Flaxseed and chia oil is the food highest in O3 and also one of the best sources of O6. Flax do not have the problem of heavy metals, and no fish have to be slaughtered in order to get the oils.
Omega-6 is found in vegetable oils from warm-weather plants such as corn, canola and sunflower. Omega 6 fats are the predominant type of PUFA fat in the American diet as it is commonly found in processed foods. While omega-6 fatty acids are necessary for a balanced diet, we often consume them in overabundance. Researchers believe that there should be a one-to-one ratio of omega-3s to omega-6s in the human diet. Yet it is estimated that the current ratio is about 20-to-1 O6 to O3! Consuming significantly more omega-6 fatty acids than omega-3 fatty acids, like most American’s do, contributes to an increased risk of chronic diseases and promotes inflammation.
Omega 3 Omega 6
Alpha Linolenic Acid (ALA) Linoleic acid
EPA Gamma-linoleic acid (GLA)
DHA Arachidonic Acid (AA)
Prostaglandins and leukotrienes Prostaglandins and leukotrienes
Saturated fat is found in animal sources and vegetable oils like coconut oil and palm oil. Taken in excess, it raises total and LDL (“ bad”) cholesterol, which can increase risk of heart disease, obeseity and cancer. Recent research, however, has shown that all saturated fat is not equal. The most common type of saturated fat is palmitic acid and myristic acid, which is a long-chain fatty acid found in animal-derived products. The primary type of saturated fat in coconut oil is lauric acid, which is a medium-chain fatty acid, and stearic acid. Lauric and stearic acid is absorbed differently than palmitic acid and is more easily burned off as energy. It also appears to have antimicrobial and antiviral properties.
Trans fat is mostly man-made fat, a hydrogenated form of unsaturated fat. It is used in the industry to make food more solid and increase shelf life. It is highly toxic and inflammatory, and it is very hard for the body to remove them once it is incorporated into the cellular structure, and thus can cause severe chronic disease states.
Is there an ideal oil that embodies the ideal ratio?
The recommended ratio of saturated/MUFA/PUFA is 1:1.5:1. Careful review of numerous reports in the literature has revealed the importance of this balance for generating the best LDL/HDL ratio. Furthermore, it would appear that the S:M:P balance is critical at any level of fat intake if one wishes to avoid adversely affecting the lipoprotein profile.
There are three main parameters to adjudge a healthy cooking oil:
(1) Choose unrefined expeller-extracted, and cold-pressed oils for maximum nutrients and minimum processing. However, limit the use of these oils to unheated applications such as salad dressings.
(2) Consider smoke point if culinary use is for high heat application.
(3) Consider fatty acid profile, the ratio of saturated/MUFA/PUFA. It is not feasible, nor desirable to try to eliminate one type of fatty acid from your diet. Obtain saturated fat from coconut oil, MUFAs from olive or avocado oil and PUFA from flax, chia and fish.
(4) Consider O6:O3 ratio. Again, choose flax seed and chia oil to increase omega-3, and supplement diet with wild caught fish three times a week.
(5) Consider the presence of natural antioxidants. It is recommended to consume polyunsaturated fat should be accompanied by vitamin E, vitamin C or carotene consumption to help prevent lipid peroxidation
(6) Always remember that fat is fat, regardless of the source. Too much fat in any form is not healthy.
Storing and Avoiding Rancidity
Unsaturated fatty acids are unstable and become rancid quickly if not stored carefully. When the oils containing EFAs are exposed to air, they attract oxidation. Keep oils under refrigeration and take them out of the refrigerator prior to using. Let stand at room temperature and they will return to liquid. Refined oils high in monounsaturated fats keep up to a year, while those high in polyunsaturated fats keep about six months. Extra-virgin and virgin olive oils keep about a year after opening. Olive oil and other monounsaturated oils keep well up to eight months; unrefined polyunsaturated oils only about half as long.