Drizzling extra virgin olive oil on grilled/steamed vegetables or fish, pouring extra virgin olive oil on rustic bread or sliced tomatoes … Well, this may not be the most common ways most of us in Asia prepare our dishes and the typical food we consume.
If extra virgin olive oil is not our typical kitchen staple, how can we reap the health benefits if we don’t use it? If frying is our common cooking method, can we use extra virgin olive oil for everyday cooking?
Cooking Temperature
In a study conducted by Dr. Nurhan Dunford (Ph. D., Oil/Oilseed Chemist) of the Oklahoma State University, it was found that the normal temperature range for food service frying is between 160°C and 190°C. Most foods cook rapidly in this temperature range and develop a golden colour, crisp texture, and good flavour.
In The Joy of Cooking written by Irma Rombauer, one of the world’s most widely read cookbooks, she recommends frying at 185ºC for best results.
As a reference, the following table shows the standard cooking temperatures for various types of food.
| TEMPERATURE | TYPE OF FOOD |
| Medium (130–145ºC) |
High water content: vegetables, potatoes, fruit…
|
| Hot (155– 170ºC) |
Coated in batter,flour or breadcrumbs, forming a crust
|
| Very hot (175–190ºC) |
Small, quickly fried: small fish, croquettes
|
💡 Olive oil is ideal for frying. In proper temperature conditions, without over-heating, it undergoes no substantial structural change and keeps its nutritional value better than other oils.
— From International Olive Oil Council, Frying with Olive Oil.
Factors to Consider
There are two considering factors when a cooking oil is used in cooking.
- Smoke Point.
- Oxidative Stability of the Oil.
A smoke point is defined as the oil begins to smoke and starts to form unhealthy compounds when heated over its tolerable limit. The oil becomes not healthy, in fact, is harmful to our health. It is a standard measure of cooking oil’s thermal stability when heated in contact with air.
💡 Extra Virgin Olive Oil can be heated up to 215°C or 420°F before it reaches the smoke point.
— From Science of Cooking with Olive Oil written by Dr. Mary Flynn (PhD, RD, Associate Professor of Clinical Medicine at Brown University’s Alpert Medical School) and the Australian Olive Association.
Smoke Point
The smoke point of Extra Virgin Olive Oil ranges from 190ºC to 215°C depending on its quality. This smoke point is higher than the normal frying temperature as suggested by the experts.
High quality extra virgin olive oil has a higher smoke point than mass produced ones. The quality of extra virgin olive oil is determined, in part, by the low free fatty acids. The lower the free fatty acid it has, its oxidative stability is better, and in turn the smoke point is higher.
💡 Factors which lead to a high free fatty acidity in extra virgin olive oil include bruised or damaged olives, fruit fly infestation, fungal diseases in the fruit, and delays between harvesting and extraction.
Oxidative Stability
The oxidative stability also depends on the reaction rates of the unsaturated fatty acids (monounsaturated and polyunsaturated fat) with oxygen.
Olive oil is one of the most stable cooking oil in this respect because it has a high percentage (75%) of monounsaturated fat (oleic acid) which has one double bond and hence less susceptible to oxidation as compared with cooking oils that has high polyunsaturated fats, where there are many double bonds.
💡 The double bonds are unstable when heated and they tend to react with oxygen. Saturated fats have zero double bonds and hence very resistant to high heat.
Heat Stability
Extra Virgin Olive Oil is an unrefined/unprocessed oil cold pressed from the olive fruits. The process does not involve heat, chemical, or water in the extraction of oil from the olives. In the West, they call this oil, olive juice.
The cold pressed oil extraction method retains most, if not all, of the phytonutrients, specifically, polyphenols and oleocanthals, as well as its Vitamin E, which are antioxidants that protect the oil from damage during high heat cooking.
💡 When heated, extra virgin olive oil is the most stable fat, which means it stands up well to high frying temperatures. Its high smoke point (210ºC or 410ºF) is substantially higher than the ideal temperature for frying food (180ºC or 356ºF).
— From International Olive Oil Council.
In many studies conducted for domestic frying, it was discovered that extra virgin olive oil was highly resistant to oxidation, heat-stable, and did not form significant amounts of harmful compounds at the end of the lab studies, whereas vegetable oils like sunflower oil did oxidise and form harmful compounds.
These studies were conducted at extreme conditions, namely, under high heat and for a long period of time. Therefore, as consumers, we should not be overly alarmed by the results because under home cooking situation, we are unlikely subject our cooking in such extreme conditions.
💡 In home cooking, we normally do not heat the oil up to the highest temperature range as would in the food services, and we also do not cook for a long period of time. Moreover, in batch frying, the temperature drops 30 to 40°C when product is added to the fryer. The temperature drops can be higher for frozen food.
Weight Control
When we fry our food within the recommended frying temperature, that is below 180°C, it normally absorbs 8 to 25% oil.
By using olive oil for frying, it forms a crust on the surface of the food that impedes the penetration of oil. And hence food fried in olive oil has a lower fat content than food fried in other oils, making olive oil more suitable for weight control.
Other Cooking Oils
The table below shows the smoke point of a few other cooking oils. Keep in mind that the smoke point for a vegetable oil will vary according to the variety and growing conditions, and how the oil was produced (unrefined, refined, semi-refined, or super refined).
| TYPE OF OIL | SMOKE POINT (TEMPERATURE) |
| Sunflower Oil (refined) | 227ºC |
| Grapeseed Oil (refined) | 216-220ºC |
| Canola Oil (refined) | 204ºC |
| Lard (unrefined) | 180-205ºC |
| Extra Virgin Olive Oil (unrefined) | 190-210ºC |
Frying Methods
Extra virgin olive oil is suitable for low to medium temperature frying below 180°C.
We recommend using extra virgin olive oil as cooking oil to cook vegetable or drizzle it over grilled or steamed vegetables to reap the most health benefits offered in both extra virgin olive oil and vegetables.
For deep frying (190°C-200°C), it is advisable to use other cooking oils that have higher smoke point, such as pure olive oil and extra light olive oil. The table below shows other types of cooking oils that are meant for deep frying, sorted in descending order of smoke point.
| TYPE OF OIL | SMOKE POINT (TEMPERATURE) |
| Rice Bran Oil | 254ºC |
| Pure/Extra Light Olive Oil (refined) | 242ºC |
| Olive Pomace Oil (refined) | 238ºC |
| Vegetable Oil (Palm Olein & Soybean) (super refined) | 235ºC |
| Sunflower Oil (refined) | 227ºC |
| Grapeseed Oil (refined) | 216-220ºC |
💡 Tip for using extra virgin olive oil as a cooking oil. Pour oil into pan, raise the temperature gradually, and never put oil into hot pan.
Extra Virgin Olive Oil for Cooking? Yes👍
- Extra virgin olive oil is a healthy oil. It is the “olive juice.”
- If use as cooking oil, extra virgin olive oil can be safely used for low to medium frying temperature.
- The frying temperature of home cooking will usually not exceeding 180oC.
- High-heat cooking above 190oC, regardless of using olive oil or not, will have already destroyed the nutrients in the food.
- Extra virgin olive oil stands up to heat remarkably well, however, it does lose its flavour as it is heated.
- Start using extra virgin olive oil in a small way, in way that will not deviate from our habits – Replace your cooking oil with extra virgin olive oil. Every single little things we do count towards prevention. Prevention is better than having to experience the emotional struggle when things happen.
Hi,
Which olive oil in your product range would u suggest to use to make a simple but nice aglio olio spaghetti?
Thank you very much.
Best regards
JUPE
Hi JUPE. Thanks for asking. Here is our thought.
Our suggestion is to use Mueloliva Clásica.
Clásica is a delicate and mild extra virgin olive oil, and it goes very well with toasted garlic in the preparation of the Aglio Olio spaghetti, as we do not want the garlic flavour nor the olive oil taste overpowering the other – we want to savour both flavour and taste.
Interesting video recipe showing the steps to prepare the Aglio Olio spaghetti, http://foodwishes.blogspot.sg/2010/12/this-spaghetti-aglio-e-olio-recipe.html
Just two notes: the first one is, remember to pour the olive oil in a cold pan first before we heat up the pan.
Second note is, each individual has his/her own preference of taste – It is what he/she likes that is what matters. So, experiment with different intensity of extra virgin olive oil to see what kind of texture and taste your family members like best.
Hope this helps.
Best Regards,
Agus.
I bought a bottle of Mueloliva Picuda at Duke Bakery @ Liang Court. The bottle has been in the refrigerator for about 1 week but the evoo does not become thicker and cloudy like other brands of evoo which I tried previously. Please help to clarify.
Thank you and best regards,
Katherine
Hi Katherine, thank you for sharing your observation.
The purpose of storing olive oil in the fridge is to reduce the rate of oxidation, and hence at best retain or at least not to lose too much of the Polyphenol (antioxidants). However, if we are using our extra virgin olive oil regularly, there is not necessary to store it in the fridge.
There is one issue in storing extra virgin olive oil in the fridge.
Once the bottle is opened, and we constantly take the bottle out and into the fridge, the air that is trapped inside the bottle would likely be condensed inside the bottle, and caused degradation of the olive oil.
Hence premium quality extra virgin olive oil is advisable to be kept in the room temperature in a cool dark place away from light if we are using it on a regular basis, as condensation eventually might affect the “aroma” and “taste” of the olive oil – my own personal experience is: it does.
The other reason people store extra virgin olive oil in the fridge is because they want to test the authenticity of the extra virgin olive oil.
The term used is called “fridge test”.
Fridge test is one of the many misconceptions that we have with extra virgin olive oil – that is, many people believe that authentic extra virgin olive oil, when placed inside a fridge, will become cloudy and solidified.
Fridge test is not a reliable way to determine whether an extra virgin olive oil is real nor whether its quality is good. Very often, adulterated extra virgin olive oils pass the fridge test.
Here are the reasons why.
The solidification of extra virgin olive oil when placed inside a fridge is due to many factors: For the beginning, one is due to (1) the presence of the monounsaturated fat (oleic acid), and the other is (2) the wax content.
(1) MELTING POINT (Freezing temperature) of Monounsaturated Fat
According to a chemistry textbook, the melting point (the temperature at which it changes state) of monounsaturated fat is around 13°C.
However, when the researchers at the University of California at Davis conducted a fridge test with different grades of olive oils and other seed oils at 4°C, high quality extra virgin olive oil only started to show solidification when it was placed in the fridge for five days, but it never fully solidified.
On a separate experiment, Dr. John Deane put several olive oils in the freezer with a thermometer to determine the actual freezing temperature (melting and freezing points are approximately equal. Small differences between these quantities can be observed.)
He found that at 4°C, most of the olive oils had not hardened or formed any crystals. At 1.7°C, most were firm enough that they could not be poured but were as soft as butter at room temperature. He observed that as the temperature lowered, more components of the oil solidified. At -12°C, the olive oils were hard enough that a fork could not penetrate them.
My own experience is this: the temperature of our fridge depends on how empty or full it is at the time of the fridge test is conducted. When the fridge is almost full, the temperature in the fridge may not be as chilled as when it is more empty. As such, the solidification process may take longer to be seen.
One thing to note: The premise behind this fridge test around the melting point (or freezing temperature) is the assumption that extra virgin olive oil is purely (100%) comprised of monounsaturated fats.
The fact is: The percentage of monounsaturated fat in extra virgin olive oil varies according to the type of olives used to extract the oil. The range can be from 65 to 80%.
Hence some authentic extra virgin olive oil needs lower temperature or longer period to be solidified – or be seen thickening and clouding.
Second note is: Other compounds that are present in the olive oil and the processing method also play a part.
The processing method such as “winterised”, i.e. chilled and filtered the wax content out of the olive oil, would cause an authentic extra virgin olive oil fail the fridge test, and would only become slightly thick (but not solid) when frozen.
Finally, in order to achieve and keep a consistent flavour profile, some producers may blend several varieties of extra virgin olive oil. The result of the extra virgin olive oil is commonly called “coupage”. This will also affect the time and the level of cold required to get to the solidification stage.
(2) WAX CONTENT in Extra Virgin Olive Oil
The surface of the olive has a coating of a thin naturally produced wax. When olives are extracted into oil, the wax ends up in the oil.
Different olive varietal produces different amount of wax. The climate, hot or cold, where olives are grown, also play a part – When the weather is hot, more waxes produced than cold.
While the amount of wax in an olive oil is small, the presence of it is a contributing factor or act as a seed for things to solidify in a cold environment.
Many adulterated extra virgin olive oil pass the fridge test because it is a blend of extra virgin olive oil and refined olive oil or olive pomace oil. Since refined olive oil and olive pomace oil have a higher wax content, so it solidifies when placed in the fridge.
For information: The wax content of the extra virgin olive oil, by the International Olive Council’s requirements, should be less than 250 mg/kg. While olive oil is less than 350 mg/kg, and olive pomace oil is more than 350 mg/kg.
Richard Gawel, an experienced olive oil consultant taster, illustrated with two examples why fridge test is not a reliable mean to determine the quality of the extra virgin olive oil.
He first put across his point saying that by putting Canola oil, which contains around 50-60% monounsaturated fat, in a fridge, it will solidify to some extent, but Canola oil is not extra virgin olive oil.
He further illustrated by showing that an adulterated olive oil that contains 90% extra virgin olive oil and 10% Canola oil will still have a high level of monounsaturated fat and will therefore solidify at fridge temperature.
If fridge test is not a reliable mean to determine the authenticity and quality of an extra virgin olive oil, then what is a better way?
The colour of the extra virgin olive oil can be enhanced by adding chlorophyll to make it greener. The solidification of olive oil can be easily duplicated by adding more wax content. Adulterated extra virgin olive oil (mixing with cheaper seed oil or olive pomace oil) can be seen solidified in the fridge.
But it is more difficult to replicate the aroma and taste of a premium quality extra virgin olive oils, which contain “bitterness” and “spiciness” due to the presence of the antioxidants and anti-inflammatory compounds (Polyphenol and Oleocanthal).
How to select and buy a premium quality extra virgin olive oil? Instead of using fridge test or looking at the colour of the olive oil, we should (1) find out the chemical quality parameters – at least read the Acidity level (Free Fatty Acid) – the lower the better, (2) smell and taste the extra virgin olive oil to detect bitterness & spiciness in it besides the natural fragrance of the extra virgin olive oil.
IN SUMMARY: All olive oils will eventually solidified in a fridge because of the presence of the monounsaturated fat and the amount of the wax content in it.
When the fridge is cold enough, the melting point (or freezing temperature) is reached, the olive oil will change its state – from solid to liquid or liquid to solid. It is a matter of time and coldness because our fridge may be more full or more empty.
For all of our extra virgin olive oils, we can find the chemical quality parameters, including the wax content, at http://buyoliveoil.vas.com.sg.
For 8 Tips to Choosing & Buying Premium Quality Extra Virgin Olive Oil, we have written an article at http://onlyoliveoil.vas.com.sg/2015/05/8-tips-to-choosing-buying-premium-quality-extra-virgin-olive-oil/
Hope this explanation helps to clarify.
Best Regards,
Agus.
REFERENCES
Lab Test by the University of California at Davis: http://dateline.ucdavis.edu/dl_detail.lasso?id=14404
Report by the University of California at Davis:
http://olivecenter.ucdavis.edu/research/files/refrigerationisnotreliablefinal.pdf
Melting Point of Monounsaturated Fat (Oleic Acid): http://www.ncbi.nlm.nih.gov/books/NBK22497/
http://chemwiki.ucdavis.edu/Biological_Chemistry/Lipids/Fatty_Acids
The “Home Fridge Test” for Authenticity of Extra Virgin Olive Oil – The Reasons why it doesn’t work by Richard Gawel:
http://www.aromadictionary.com/EVOO_blog/?p=550
Myth – the Extra Virgin Olive Oil Fridge Test by North American Olive Oil Association: http://www.aboutoliveoil.org/FridgeTestMyth.pdf
Cloudy Frozen Olive Oil by Dr. John Deane:
http://www.oliveoilsource.com/article/cloudy-frozen-olive-oil
Fridge Test Does Not Reliably Detect Adulterated Extra Virgin Olive Oil by Only Olive Oil:
https://www.facebook.com/onlyoliveoil/posts/1547673038786561
Which olive oil is good for making sourdough bread which I put in a heated Dutch oven at 250C?
Hi Nancy, in Spain, “Extra Virgin” olive oil is often used in cooking and baking. In this olive oil bread recipe from Spain, the ingredient includes “extra virgin” olive oil and the oven is pre-heated to 250 to 300°C.
Please visit: here, here and here.
In cooking and baking, research studies have suggested that we should be looking at the “Oxidative Stability” of the oil rather than the “Smoke Point”, as those oils with higher smoke points tend to produce higher levels of harmful compounds after heating due to the presence of high amount of polyunsaturated fatty acids which break down during heating (for example, rice bran oil, canola oil, sunflower oil, grapeseed oil).
For a summary of these research findings, you can read this.
Butter has a lower smoke point, around 170°C (clarified butter has a higher smoke point, 230°C) and it is often used in baking (as one of the ingredients) for a long time. “High Quality” extra virgin olive oil has a smoke point of around 210°C, and coupled with its higher “oxidative stability” and the existence of the phytonutrients (antioxidants and Vitamin E), health advocates often suggest to replace butter with extra virgin olive oil in baking for a healthier bake.
Senorio de Vizcantar Normal is a good choice for everyday cooking and baking. Its acidity is low (less than 0.25%). Its Polyphenol is moderately high (around 350 mg/kg). It is value-for-money for everyday use. Another good choice is the Senorio de Vizcantar Organic.
Both have good chemical properties and their taste are not too overpowering. However, taste is really an individual preference; some prefer to use the “complementary” method for food pairing but some prefer the “contrasting” method, i.e. light-to-light and strong-to-strong for the former and light-to-strong and strong-to-light for the latter.
Please read this article.
Hope we have addressed the questions you have raised. In the event that you have any doubt, please follow your heart, and the normal practice you have been following in the past.
Just a note, “pure” and “light” olive oil are “refined” olive oil, which have higher smoke point (around 240ºC) than the “extra virgin” olive oil, but lack the natural phytonutrients (antioxidants, etc) found in the “extra virgin” olive oil as they have been removed during the high-heat refining process. The refined olive oil has also had a bland taste; if there is taste, it is due to the addition of extra virgin olive oil into the refined olive oil, usually in the range of 5%-10%.
Thanks. Agus. Only Olive Oil.