Cooking with Olive Oil

Olive oil has been used across the globe for many centuries as a multi-purpose culinary oil. This includes when consumed with cold meals (such as salad dressings) and when used as a medium for pan frying, sautéing and deep frying.

Extra Virgin Olive Oil is the ubiquitous cooking medium of the Mediterranean Diet. It is an extremely healthy oil to use for all types of cooking, and has much existing and emerging research related to the health benefits of the high levels of antioxidants (some of which are unique to Extra Virgin Olive Oil) and the ability of the oil to enhance the health attributes of other ingredients once cooked.1-3

When cooking with any oil, there is an exchange between the food and the oil. For example, most food that is cooked in Extra Virgin Olive Oil will contain a higher proportion of mono-unsaturated fats than the original food.4-6 In addition, antioxidants from the oil will transfer into the cooked food.1,4-6 Fat soluble vitamins, and food components such as glucosinolates (found in broccoli and kale) and carotenoids (found in carrots) are better absorbed by the body when cooked in Extra Virgin Olive Oil.1,7

There is a common misconception that you cannot cook with Extra Virgin Olive Oil, and this has no scientific substantiation.

The smoke point of an oil (the temperature at which the oil produces a thin, continuous stream of bluish smoke) has generally been used to predict an oil’s safety and suitability for cooking at domestic temperatures. New research (2018) has shown that there is a poor correlation between an oil’s smoke point and its performance when heated.8 This research concluded that:

  • Smoke point does not predict an oil’s performance when heated
  • Oxidative stability and UV coefficients are better predictors when combined with total level of polyunsaturated fats
  • Of all the oils tested, EVOO was shown to be the oil that produced the lowest level of harmful polar compounds
  • Production of polar compounds was more pronounced for refined oils
  • EVOO was demonstrated to be the most stable oil when heated, followed closely by other virgin oils

What are polar compounds?
When oil breaks down (e.g. when exposed to heat) there are a variety of degradation by-products produced, such as polar compounds. Evidence shows that polar compounds may be detrimental to health and have been linked to the development of neurodegenerative conditions such as Alzheimer’s and Parkinson’s Disease.9-12 In industrial kitchens, the percentage of polar compounds remaining in cooking oils (after repeated use) is tested to determine when an oil is no longer safe to for human consumption. International legislation in countries including France, Italy, Poland and Spain enforces a limit to the polar compounds in frying oils as no more than 25%.13,14

Extra Virgin Olive Oil is highly stable and resistant to breaking down and forming harmful compounds like polar compounds because it is:

  • Rich in mono-unsaturated fat (e.g. oleic acid). However, many refined oils are higher in poly-unsaturated fat, which is more prone to oxidation and therefore degrades more readily.
  • Moderately high in saturated fats, which remain very stable when the oil is heated.
  • High in natural antioxidants (see Grades of Olive Oil to assess how Olive Oil and Extra Virgin Olive Oil compare) which protect the oil from breakdown when heated.15 In contrast, refined oils (such as Canola Oil, Rice Bran Oil and Grapeseed Oil) are devoid of natural antioxidants and therefore experience higher levels of degradation when heated.
  • Naturally produced via mechanical means only. Refined oils are subject to many processing treatments during production, such as high heat, bleaching and deodorizing. This leaves refined oils with high initial levels of oxidative by-products, and pre-primes them to more readily break down when heated during cooking.16-19

There is also other published literature which demonstrates the safety and suitability of Extra Virgin Olive Oil for cooking.9-12

 

Extra Virgin Olive Oil is suitable for sautéing, pan frying, deep frying and oven baking. Every style of cooking at home. (e.g. drizzle generously over meals, through sauces, whilst marinating meat and for cooking vegetables).

Research reports from the US Davis Olive Center detail the recommended levels of Extra Virgin Olive Oil in the diet to improve clinical risk factors for chronic disease (such as blood lipids and blood pressure). Authors reviewed all relevant human Randomised Control Trials from 1998–2015 and excluded observational studies and review articles. ‘The UC Davis Olive Center is a self-funded university/industry coalition that seeks to do for olives what UC Davis did for wine. The world-renowned center brings together nearly 60 UC faculty members, research specialists and farm advisors who address the research and education needs of California olive growers and processors. The center also collaborates with institutions worldwide.’ The reports can be accessed here.

 

Affordability of Extra Virgin Olive Oil

A plant-based Mediterranean style diet, with Extra Virgin Olive Oil as the principle fat, has been shown to be more affordable than an individual’s usual eating pattern, especially when compared to a highly processed Western Diet.20-22

A 6-week intervention study in the US in 2013 found that individuals who followed a plant-based Mediterranean style eating pattern, with an emphasis on cooking with Extra Virgin Olive Oil, reduced their usual grocery spend by approximately 30 USD each week.20 This was the first study to show a decrease in food insecurity as the result of a dietary intervention. Additional improvements included a reduction in body weight and total grocery purchases including unhealthy products such as carbonated beverages.

A detailed analysis on 20 participants involved in a 2017 Randomised Control Trial in Australia found that following a Mediterranean Diet was more affordable compared with the participants’ baseline diet, and reduced total grocery spend by approximately 26 AUD per week.21

 

 

References

  1. Ramirez-Anaya J, Samaniego-Sanchez C, Castaneda-Saucedo M, Villalon-Mir M, Lopez-Garcia de la Serrana H. Phenols and the antioxidant capacity of Mediterranean vegetables prepared with extra virgin olive oil using different domestic cooking techniques. Food Chem. 2015;188:430–8.)
  2. Perez-Herrara A. et al. 2013 The antioxidants in oils heated at frying temperature, whether natural or added, could protect against oxidative stress in obese people. Food Chem. 138; 2250–2259
  3. Gray S. Cooking with Extra Virgin Olive Oil. ACNEM J. 2015;34(2):8–12
  4. International Olive Oil Council. Frying with olive oil.
    At: http://www.internationaloliveoil.org/estaticos/view/85-frying-with-olive-oil
  5. Verela G, Ruiz-Roso B. “Some effects of frying on dietary fat intake”. Nutr Rev. 1992;50:256–262.
  6. Nieva-Echevarria B, Goicoechea E, Manzanos M et al. The influence of frying technique, cooking oil and fish species on the changes occurring in fish lipids and oil during shallow-frying, studied by 1H NMR. Food Research International. 2016; 84:150–159.
  7. Moreno d, L ́opez-Berenguer c, Garcia-Viguera c. Effects of Stir-Fry Cooking with Different Edible Oils on the Phytochemical Composition of Broccoli. J Food Sci. 2007;72.
  8. de Alzaa F, Guillaume C, Ravetti L. Evaluation of Chemical and Physical Changes in Different Commercial Oils during Heating. Acta Scientific Nutritional Health. 2018;2(6): 02-11.
  9. Matveychuk D, Dursun S, Wood P et al. Reactive Aldehydes and Neurodegenerative Disorders. Bull Clin Psychopharm. 2011;21(4):277–88.
  10. Pizzimenti S, Ciamporcero E, Daga M et al. Interaction of aldehydes from lipid peroxidation and membrane proteins. Front Physiol. 2013;4:242. doi: 10.3389/fphys.2013.00242.
  11. Cruz-Haces M, Tang J, Acosta G et al. Pathological correlations between traumatic brain injury and chronic neurodegenerative diseases. Transl Neurodegener. 2017; 6:20.doi: 10.1186/s40035-017-0088-2.
  12. Jinwei L, Xiaondan L, Wenci C et al. Comparison of different polar compounds-induced cytotoxicity in human hepatocellular carcinoma HepG2 cells. Lipids Health Dis.2016;15:30. doi: 10.1186/s12944-016-0201-z.
  13. Gupta M, Warner K, White P. Frying Technology and Practices. Champaign, IL: AOCS Press; 2004.
  14. Food Safety Helpline. FSSAI Notifies Standards Relating to Total Polar Compounds in Cooking Oil.
    At: http://foodsafetyhelpline.com/2017/11/fssai-notifies-standards-relating-total-polar-compounds-cooking-oil/
  15. Cicerale S, Conlan XA, Barnett NW et al. Influence of heat on biological activity and concentration of oleocanthal, a natural antinflammatory agent in olive oil. J Agric Food Chem.2009;57(4):1326–30.
  16. Allouche Y et al. 2007 How Heating Affects Extra Virgin Olive Oil Quality Indexes and Chemical Composition. J Agric Food Chem. 55: 9646–54.
  17. Casal S et al. 2010 Olive oil stability under deep-frying conditions. Food Chem Toxicol. 48: 2972–7.
  18. Gomez-Alonso S et al. 2003 Changes in Phenolic Composition and Antioxidant Activity of Virgin Olive Oil during Frying. J Agric Food Chem. 51: 667–67.
  19. Jiyeong L, Dong A, Jung K, et al. Influence of extra virgin olive oil on the formation of heterocyclic amines in roasted beef steak. Food Sci. 2011;20(1):159–65.
  20. Flynn MM, Schiff AR. A Six-week Cooking Program of Plant-based Recipes Improves Food Security, Body Weight, and Food Purchases for Food Pantry Clients. J Hunger Environ Nutr. 2013;8(73):73-84.
  21. Opie R, Segal L, Jacka FN, et al. Assessing healthy diet affordability in a cohort with major depressive disorder. J Publ Health Epidemiol. 2015;7(5):159–69.
  22. Flynn MM, Schiff AR. Economical Healthy Diets (2012): Including Lean Animal Protein Costs More Than Using Extra Virgin Olive Oil. J Hunger Environ Nutr. 201;00:1-16.

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