Smoke Point of Oils

 


SMOKE POINT OF OILS


Have you ever heard the smoke point? It sounds like it is about burning something. If you think in this way, that is right! In the simplest term, the smoke point is related with oils and is the temperature at which an oil starts to burn and smoke. At this point, the oil begins to produce bluish smoke. It is essential to know and pay attention to an oil’s smoke point. The reason for this that the burned oil gives an unpleasant flavour to food and free radicals that can harm the body.

 

The smoke point is associated with the volume of oil utilized, the size of the container, the presence of air currents, the heat source and the quality of the oil. Besides, the smoke point is related to the content of free fatty acids (FFA) and depends on the oil’s acidity rather than its fatty acid composition. The smoke points of oils increase and decrease according to FFA they contain. FFA contained in oils is degraded rapidly by heat. The more FFA causes the quicker breaking down and starting to smoke as observing in unrefined oils. In the meanwhile, the low content of FFA causes a higher smoking point as observing in refined oils.

 

Oils appear in almost everything that comes from the kitchen. It derives from seeds and nuts, like sunflowers, olives, avocados, coconuts, etc., and are extracted from them through mechanical crushing and pressing. When we use the method of cold press extraction on the olive seeds at the temperature of up to 50 °C, we get a cold-pressed oil. The cold-pressed oil, also known as virgin oil, tends to retain its natural flavour and colour. They are unrefined oils and contain minerals, enzymes, antioxidants, and essential fatty acids. The higher nutrient content of oil makes them more available to easy burning since they have lower smoke points. Refined oils, however, have a higher smoke point since they are subject to physical processes to remove impurities and FFA that can cause the oil to smoke. Refinement techniques like high-temperature heating, filtering, bleaching, and deodorizing work to remove the colour, flavour, smell and remnant of the seeds. Therefore, the manufactured product has a neutral taste, long shelf life, and high smoke point. The smoke point not only associated with whether the oil is refined or not but also what the percentage is of polyunsaturated vs monounsaturated vs saturated fats. Saturated fats are more stable than unsaturated fats and less likely to oxidize, no matter the temperature. On the other hand, stability varies in unsaturated fats. For instance, monounsaturated fats are more stable than polyunsaturated fats (PUFAs). The stability of the oil can be decided according to its presence at room temperature; for example, fats that are solid or semi-solid at room temperature like observing in coconut oil, animal fats, and butter are more saturated than those that are liquid like observing in vegetable, nut, and olive oils. Recently studies show that there is a correlation between PUFAs and production of a high number of polar compounds when heated; higher PUFAs, higher production of polar compounds. Because of this reason, it is generally recommended to not reuse frying oil more than twice. Reheating oils, especially in oil that is high in PUFAs, at high temperatures beyond their smoke point causes the production of toxic carcinogenic compounds. To avoid this, we should know the smoke point of oils that we will use for the best cooking and should not reuse the oil.

 

 The general smoke point of specific oils;



Note: Adapted from Riches, Keep This Chart Handy to Make Sure Your Oil Doesn't Burn.

 

To sum up, if keeping to heat after passing the smoke point of the oil, fat starts to break down. Free radicals, that are the resultant products of this breaking down, are released and also a substance called acrolein, the chemical that gives burnt foods their acrid flavour and aroma. Moreover, it affects health in a bad way. Thus, it is important to know the smoke point of oil which we use.

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CONTENT: Miray Ertürk

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REFERENCES

1. Begić, M., Nezirević-Nizić, E., Čorbo, S., Podrug, S., Ašimović, Z., & Muminović, Š. (2020). Fatty Acid Composition and Stability of Cold-Pressed Vegetable Oils. In 30TH SCIENTIFIC-EXPERTS CONFERENCE OF AGRICULTURE AND FOOD INDUSTRY: Answers (p. 303). Place of publication not identified: SPRINGER NATURE.

2. Fats and Oils. (n.d.). Retrieved August 30, 2020, from http://www.missionheirloom.com/fats-and-oils

3. Gomes, R., & Eggleton, M. (2002). 6.1.6. Food. In 911080666 717013102 M. Meek (Ed.), ACROLEIN (p. 11). World Health Organization Geneva.

4. Gunstone, F. D. (2011). 5.3.4 Smoke point, flash point and fire point. In Vegetable oils in food technology: Composition, properties and uses (p. 149). Oxford: Wiley-Blackwell.

5. Keller, T. (2019, September 25). Cooking Oils and Smoke Points: What to Know and How to Choose the Right Cooking Oil.

6. Riches, D. (n.d.). Keep This Chart Handy to Make Sure Your Oil Doesn't Burn. Retrieved August 30, 2020, from https://www.thespruceeats.com/smoke-point-chart-334972