5 Best Oils To Use for Frying

Most people enjoy fried foods, but the frying process causes chemical changes in the food and oil. The healthiest options for frying are oils that are resistant to high-temperature cooking and have a favorable fatty acid profile.

Oils contain different fatty acids, including saturated, monounsaturated (MUFA), polyunsaturated (PUFA), and trans fatty acids. Consumption of unsaturated fats (MUFA and PUFA) is advised instead of saturated and trans fats.

Oils with higher monounsaturated fatty acid content and lower polyunsaturated fatty acid content are preferable for frying. Frying turns PUFA into trans fats and other harmful compounds, so less PUFA means fewer unhealthy compounds.

The antioxidant content and smoke point are also important when choosing an oil for frying. The smoke point is the temperature at which oil starts smoking, which produces harmful compounds. A high antioxidant profile in oil makes it more resistant to creating those harmful compounds.

1. Olive Oil

Olive oil is the primary cooking oil in the Mediterranean diet. It contains more MUFA than PUFA, making it less likely to produce harmful compounds. Extra virgin olive oil contains 69.2% MUFA, 9.07% PUFA, and 15.4% saturated fats.

Olive oil has a smoking point of 410 degrees Fahrenheit (210 degrees Celsius), while virgin olive oil has a lower smoking point of 320-338 degrees Fahrenheit (160-170 degrees Celsius). Olive oil is rich in antioxidants, increasing the oil's resistance to creating harmful compounds.

Frying increases the oil's free fatty acid content (FFA). FFAs can turn into harmful compounds through a process called oxidation, lowering the oil's quality. In a study of FFA generation in olive, canola, and peanut oils during frying, potato chips were deep-fried at 347 degrees Fahrenheit (175 degrees Celsius) for 28 hours in 30-minute frying cycles. FFAs increased as frying length increased, and the olive oil had the lowest FFA content of the three oils.

2. Avocado Oil

Avocado oil contains 70.6% MUFA, 13.5% PUFA, and 11% saturated fats. It also has a high smoke point above 482 degrees Fahrenheit (250 degrees Celsius). Avocado oil has similar stability to olive oil when exposed to a heat of 356 degrees Fahrenheit (180 degrees Celsius) for nine hours.

In a study comparing potato chips fried with avocado, soybean, sesame seed, and almond oil, the antioxidant capacity in avocado oil remained the highest after five frying cycles.

3. Rice Bran Oil

Rice bran oil is another healthier option for deep-frying foods. It has a high antioxidant capacity and a smoke point of 449 degrees Fahrenheit (232 degrees Celsius). Rice bran oil consists of 39.3% MUFA, 35% PUFA, and 19.7% saturated fats.

Rice bran oil can also be blended with other oils. A study looking at blends of rice bran oil with olive oil, sunflower oil, and palm oil found that the most stable (resistant to deterioration) blends were rice bran oil with olive oil and rice bran oil with palm oil.

4. Peanut Oil

Peanut oil contains 57.1% MUFA, 19.9% PUFA, and 16.2% saturated fats. It also has a high smoke point of about 446 degrees Fahrenheit (230 degrees Celsius). A study comparing the stability of peanut, canola, soybean, and corn oil during heating found that harmful compounds were highest in corn oil and lowest in peanut oil.

Highly refined peanut oil is safe for people with peanut allergies, but cold-pressed, expelled, and extruded peanut oils still contain allergens.

5. Canola Oil

Canola oil contains 63.3% MUFA, 28.1% PUFA, and 7.36% saturated fats, but deep-frying with canola oil may produce an undesirable taste. When buying canola oil for deep-frying, check for labels that state it contains high oleic acid, as canola oil blends with high oleic acid are more heat-resistant. 

A study compared the changes in canola oil, corn oil, peanut oil, palm oil, and sunflower oil during the frying of French fries. The results showed that peanut and canola oil contain the least harmful compounds and have antioxidant stability, while sunflower, corn, and soybean oil exhibited the highest deterioration.

How To Choose a Fry Oil

When you're choosing oil for frying, consider:

• Oil fatty acid profile: Oils with high PUFA cause the production of more harmful compounds when heated, compared to oils with high MUFA or saturated fat. Although saturated fats (such as coconut oil) are stable in heat, it is not recommended to fry with high saturated fats because fried food will absorb the oil.
• Smoke point: The smoke or smoking point is the temperature at which oil begins to evaporate. This process causes chemical changes in the oil, resulting in an undesirable appearance and taste and the formation of harmful compounds. For this reason, a high smoke point is most desirable for frying.
• Processing method: Processing methods affect oil stability by changing antioxidant content. Mechanical processes, as used in producing extra virgin olive oil, preserve the oil's natural antioxidant content. Refined oils (that may be bleached or heated) lose some antioxidants, so they're generally added later as additives.

Deep vs. Shallow Frying

Oxygen is needed to produce lipid oxidation products; therefore, shallow frying causes more lipid oxidation products. These compounds can cause DNA and cell damage, leading to health conditions.

For shallow frying, using MUFA-rich fats is still more suitable. A study compared lipid oxidation products in avocado oil, extra virgin olive oil, corn oil, and soybean oil in cycles of shallow frying. As expected, PUFA-rich oils (corn and soybean oil) resulted in the highest generation of lipid oxidation products compared to avocado and olive oil.

For shallow frying, you can also use oils with high MUFA and low PUFA and saturated fats, such as canola, rice bran, almond, peanut, and olive oil.

Oils To Avoid for Frying

The fatty acid composition of oil changes when exposed to heat. Frying reduces PUFA content and increases saturated and trans fatty acids. Therefore, oils with high PUFA content are not suitable for frying.

High PUFA oils include:

• Corn oil: 52.9% PUFA, 13.4% saturated fats
• Sunflower oil: 62.4% PUFA, 9.4% saturated fats
• Sesame oil: 41.2% PUFA, 16.9% saturated fats
• Soybean oil: 57.6% PUFA, 14.9% saturated fats
• Safflower oil: 79.1% PUFA, 9.3% saturated fats
• Grape seed oil: 74.9% PUFA, 10.4% saturated fats

A study looked at changes in coconut, olive, rapeseed, and sunflower oil composition when heated. The results showed that coconut oil was the most resistant to heat, while sunflower oil was the least resistant. Although saturated fats are stable at high temperatures, frequent consumption is associated with an increased risk of heart disease. Therefore, it's not recommended to use oil with high saturated content regularly.

Oils high in saturated fat include:

• Coconut oil: 18.2% PUFA, 92.1% saturated fats
• Butter: 2.52% PUFA, 45.6% saturated fats

Use these oils in applications requiring little to no heating, such as salad dressings.

A Quick Review

Deep-frying food generates harmful compounds and often lowers the nutritional quality of both the oil and the food. You can use oils high in monounsaturated fatty acids and low in polyunsaturated fatty acids for frying, such as olive, avocado, rice bran, and peanut oil. Regardless of which oil you use, avoid reusing oils to reduce the generation of harmful compounds.