Cooking Oils and Fats: A Complete Guide

Oils and Fats

Plant oils and animal fats are a crucial ingredient in many dishes. Some can withstand high-heat cooking methods to promote browning and development of flavorful Maillard reaction compounds, while others can impart their delicious flavors and aromas to your food.

However, lipids* (the class of macronutrients that include oils and fats) each have different physical properties, flavors, health benefits, and nutrient profile. It’s important to know when to add which to your dish, and which ones to avoid.

*From here on, the terms lipids, fats, and oil may be used interchangeably. The most common distinction is that fats are solid at room temperature, while oils are liquid.

Smoke Point

The smoke point is the temperature at which and oil or fat it begins to smoke, causing it darken and develop an unpleasant, burnt taste. High smoke points are desirable when it comes to high heat cooking.

Smoke points vary between oil types, and will lower there is an increase in impurities and free fatty acid composition^[1] (which affected by cooking time and processing methods).

Smoked oils have harmful effects which go beyond just food. First, the oil oxidizes^[2], a process which destroys the antioxidants that protect the oil from degrading. This makes it easier for oil to produce free radicals under heat and light, dangerous compounds that damage DNA and cause oxidative stress^[3] in your body. They can potentially lead to inflammation, heart disease, and even cancer.^[4]

Therefore, oil selection is important when it comes to preparation method.

For high-heat cooking, such as searing, deep-frying, or pan-frying, a fat with a high smoke point is preferable (e.g., avocado oil, grapeseed oil, ghee, tallow, etc). For oils with lower smoke points (e.g., sesame oil, butter, unrefined extra virgin olive oil, etc), it’s best to limit these to low-heat cooking or for dips, dressings, or emulsifying sauces.

Smoke Point Chart

Oil	Smoke Point °F	Smoke Point °C
Refined Avocado Oil	520°F	270°C
Safflower Oil	510°F	265°C
Rice Bran Oil	490°F	254°C
Refined or Light Olive Oil	465°F	240°C
Soybean Oil	450°F	232°C
Peanut Oil	450°F	232°C
Ghee or Clarified Butter	450°F	232°C
Corn Oil	450°F	232°C
Refined Coconut Oil	450°F	232°C
Safflower Oil	440°F	227°C
Refined Sesame Oil	410°F	210°C
Vegetable Oil	400-450°F	204-232°C
Beef Tallow	400°F	204°C
Canola Oil	400°F	204°C
Grapeseed Oil	390°F	199°C
Unrefined or Virgin Avocado Oil	375°F	190°C
Pork Fat or Lard	370°F	188°C
Chicken Fat or Schmaltz	375°F	190°C
Duck Fat	375°F	190°C
Vegetable Shortening	360°F	182°C
Unrefined Sesame Oil	350°F	177°C
Extra Virgin or Unrefined Coconut Oil	350°F	177°C
Extra Virgin Olive Oil	325-375°F	163-190°C
Butter	302°F	150°C

Oil Smoke Points^{^[5]}

Flavor

Oils tend to dissolve fat-soluble compounds, which gives them extra flavor. This distinct quality allows you to either create flavored oils or mask other flavors.

An oil’s flavor profile may ultimately determine how you use it or what recipes work well with it.

Oil Flavors and Commonly Associated Cuisines

Oil	Flavor	Uses
Avocado Oil	Neutral	Versatile
Butter	‘Buttery,’ dairy-like	Versatile
Coconut Oil	Coconut	Desserts, Southeast Asian cuisine
Ghee	Intensely buttery, without dairy	Indian, Middle Eastern, Southeast Asian cuisine
Extra Virgin Olive Oil	Earthy	Mediterranean cuisine
Sesame Oil	Nutty	Asian cuisine

Oil Flavor and Associated Cuisines

You could make a spice-infused oil by lightly toasting the spices with a neutral oil, or cooking them at low heat (e.g., garlic confit).

However, you can just as easily extract unwanted flavor compounds from flavorful oils through emulsification. Emulsification is a process to mix oil and water, like with mayonnaise.

Heat may reduce an oil’s taste if desired, although it may slightly change its nutritional qualities, too. Neutralizing the oil means you can use it in any dish without worrying about clashing flavors.

For example, you may want to deep fry with coconut oil because it holds up well against heat.^[6] But you also won’t have to worry about imparting coconut flavor into your foods after it begins to lose flavor.

Refined vs. Unrefined Oils

Unrefined oils are very different from refined oils. Not only do they differ in the extraction process, but they also have entirely different nutritional qualities.

Unrefined oils usually bear the label ‘cold-pressed’ or ‘expeller-pressed. These oils come from sources which are pressed without heat, as the ‘cold-pressed’ suggests.

Refined oils rely on industrial processing techniques, which may introduce potentially toxic chemicals. Processing includes refining, bleaching, and deodorizing oils.^[7]

Refined oils may contain traces of hexane, which manufacturers heat to extract oils from their source.^[8]Hexane is dangerous at high concentrations, but not necessarily at low concentrations.

However, the human body metabolizes hexane into toxic metabolites like 2-5 hexanedione. Chronic exposure to this chemical may cause peripheral polyneuropathy, a type of damage to the nervous system.^[9]

Processed oils may also contain other potentially dangerous chemicals. Some refined oils contain BHA and TBHQ for their antioxidant-potential.^[10]

Studies demonstrate a link between BHA and cancer in animal studies.^[11] Meanwhile, TBHQ causes T-cell suppression, which suppresses the immune system.^[12] T-cells are the immune cells responsible for fighting off dangerous infections (such as coronavirus) and cancer growth.

Fatty Acid Saturation

Saturation refers to the presence of hydrogen atoms in an oil’s fatty acid chains, which can affect its molecular shape (and whether it’s solid or liquid at room temperature), nutritional properties, and metabolism in the body.

Unsaturated Fats

Unsaturated fats are unsaturated in hydrogen atoms, giving them a non-linear shape that prevents them from solidifying at room temperature. Most unsaturated fats are derived from plants and contain the word “oil” in their name.

Unsaturated Fats:

Avocado oil
Olive oil
Other liquid oils

Saturated Fats

Saturated fats contain fatty acid chains are fully saturated with hydrogen atoms, giving them a linear shape that allows them to solidify at room temperature. Most saturated fats are derived from animal fats, but hydrogenation (a processing technique) can convert an unsaturated fat into a saturated fat.

Saturated Fats:

Butter, Ghee
Coconut oil
Tallow, Lard, other rendered animal fats
Margarine, other hydrogenated plant oils

Trans Fats

Trans fats are a type of unsaturated fat that is linear and solid at room temperature. An overwhelming majority of trans fats were artificially created in a way that’s hard for the human body to metabolize. They were popular at a time when health experts wrongly recommended reducing saturated fats without evidence.

Trans Fats:

Partially Hydrogenated Oils
Naturally occurring in small quantities

Health Concerns

Saturated fats have had a bad reputation for supposedly increasing the risk of cardiac disease and death. However, recent studies find that replacing saturated fat intake with unsaturated fats doesn’t necessarily increase the risk of death from heart disease or any other cause.^[13]

Rather than blaming a single macronutrient like saturated fat, it’s more important to to look at your overall nutrition profile.

For example, eating a vegetable curry with coconut milk (which contains saturated fats) hardly compares to eating heavily processed meats loaded with excess salt and sugar.

But if there’s any fat to avoid at all costs, it’s hydrogenated/partially hydrogenated oils. There is a widespread ban on these artificial trans fats because they lead to increased inflammation, heart disease, and potentially diabetes.^[14]

Omega-3 vs. Omega-6 Fatty Acids

Omega-3 and omega-6 fatty acids are essential fatty acids. Since our bodies do not synthesize these fatty acids, we must acquire them from our diet.

Omega-3 is alpha-linoleic acid, which is an anti-inflammatory fatty acid. Omega-6 is linoleic acid, which is an inflammatory fatty acid.^[15]

Naturally, our bodies require both inflammation to fight off infections and anti-inflammatory compounds to prevent excessive damage from inflammation.^[16]

As with all things, there needs to be a balance to sustain life. Therefore, it’s essential to get the ratio of omega-3 and omega-6 right.

Currently, our bodies today have an average omega-6 to omega-3 ratio of 16:1. However, reducing the omega-6 to omega-3 ratios to the following has produced health benefits for varying health conditions^[17]:

5:1 – Benefit for asthma patients
3:1 – Decreases inflammation in rheumatoid arthritis patients
2.5:1 – Decreases cancer cell growth colorectal cancer

Omega-3 and Omega-6 Content of Oils

To calculate the ratio, divide omega-6 content by omega-3 content. For example, safflower oil has a ratio of 14:1 (14 parts omega-6 to 1 part omega-3).

Vitamin E

Vitamin E is one of the most common vitamins found in oils. However, there are two forms of vitamin E: alpha-tocopherol and gamma-tocopherol.

Research suggests sticking to the alpha-tocopherol, found in olive oil and sunflower oil. Alpha-tocopherol is an antioxidant, which protects your body from oxidative stress and free radicals.

Gamma-tocopherol is also an antioxidant found in canola, corn, and soybean oils. However, it has different consequences on the body.

Studies have linked gamma-tocopherol concentrations in the body with lower vitamin E intake, higher inflammation, and increased oxidative stress.^[18] Another study associates increased gamma-tocopherol consumption with a higher incidence of lung disease and reduced lung function.^[19]

How to Store Oils

Your storage method will affect how long your oil lasts and its nutritional quality. It’s best to minimize your oil’s exposure to open-air, heat, or light.^[20]

These factors can trigger oxidation, causing antioxidants to degrade, which increases free radical concentration and risk of disease.

They may also cause the oil to go rancid. Rancidity refers to the breakdown of fats into free fatty acids. If your oil smells or tastes off (soapy, bitter, metallic), it may be rancid due to the fatty acids.

Therefore, it’s best to store oils in a sealed container in a cool, dark place. Use an opaque or tinted bottle that keeps light and oxygen out.