We know from recent research that smoke point is not a good indicator of a cooking oil’s stability when exposed to heat, as it doesn’t accurately represent the point where EVOO begins to break down and form harmful compounds.¹ In previous blogs we have unpacked oil stability tests and answered the question, can you cook with extra virgin olive oil? In this blog we will investigate what smoke point is actually telling us and what this means for our food and health.

What happens at smoke point?

When heat is applied to any cooking oil over time, chemical changes occur which can significantly impact taste, smell, appearance and overall health properties. As smoke point is a very distinctive visual cue, it makes sense why it has been mistakenly utilised as a marker of oil stability prior to studies investigating the chemical properties of cooked edible oils. Whilst this is still an emerging area of research that requires further investigation, chemical analysis has shown us that the molecular changes causing smoke point in cooking oils do not necessarily correlate with the formation of polar compounds and trans fats in EVOO.^1,2

When any cooking oil is heated, triglycerides are broken down into smaller compounds known as glycerol and free fatty acids. Glycerol is then further broken down by heat into a very flammable compound, producing a continuous thin veil of bluish smoke.¹ Whilst some free fatty acids may combust, others can undergo oxidation when exposed to heat, producing harmful polar compounds and trans fats when cooking for a significant period of time.^3,4 Unfortunately both compounds have been linked to increased risk of chronic disease, with polar compounds more strongly associated with neurodegenerative diseases such as Alzheimer’s and Parkinson’s Disease, and trans fats with ischemic heart disease and stroke.^3,4 It takes much longer for harmful molecules to form when cooking with EVOO, as the high concentration on monounsaturated fatty acids and bioactive compounds naturally found in the olive fruit protect the oil from oxidation.¹ Additionally, studies investigating cooking with EVOO and health have shown regular consumption can reduce risk of chronic disease, proving further that it is the ideal oil to use in the kitchen.^5-7 This means when it comes to cooking at home or even in an industrial kitchen, EVOO is safe to cook with despite not having a smoke point as high as some other oils.

When looking at more refined cooking oils that have undergone bleaching, deoderising, degumming and neutralising,⁸ whilst they tend to have relatively higher smoke points, they seem to produce much higher concentrations of polar compounds and trans fats when heated.¹ This is because the processing steps required to make these oils edible strip most of the bioactive compounds present in plant fats, making the oil a lot less resistant to chemical changes caused by heat.⁸ De Alzaa et al (2018) was one of the first papers to debunk the smoke point myth and explore key chemical changes in edible oils under different cooking conditions. In this paper we can see a consistent trend with refined oils that have a higher smoke point and higher concentrations of harmful compounds after heat exposure.¹ Not only does this paper provide concrete evidence supporting the nutritional benefits of bioactive compounds in oil, but it also suggests that in highly refined oils negative chemical changes occur before smoke point is reached.¹ This further highlights the importance of selecting a cooking oil based on its chemical composition when considering stability and health.

What does this mean for your food?

Now that we know EVOO is safe to cook with and beneficial for long term health, let’s discuss how hitting smoke point can sometimes impact taste. EVOO is equipped with many polyphenols and antioxidants which contribute to health and a unique flavour profile, but if your oil is smoking for a long period of time, the taste and aroma can slightly change. Whilst this isn’t always noticeable in a dish and won’t negatively impact health like other cooking oils,¹ we recommend reducing the heat or adding some food to stop your oil from smoking and preserve it’s beautiful flavour!

Conclusion

Whilst smoke point is no longer considered an accurate method of measuring an oil’s stability, there are now more accurate testing methods which investigate both dangerous and beneficial compounds found in edible oils when exposed to heat.¹ Paired with research that looks into rates of chronic disease, it is clear in the literature that you absolutely can and should be cooking with EVOO.

Published 02/12/2024

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