I decided to dig deeper on this topic mainly for one practical reason - I used up my regular olive oil a couple weeks ago while having a few virgin and extra virgin ones sitting in the kitchen. It sounded stupid to left my pricier (and presumably better) extra virgin oil slowly turning stale on the shelf while replenishing the cheaper oil for cooking. And what I found out actually surprised me.
Okay, first and foremost let's hear the most common argument against extra virgin olive oil for cooking - it has a relatively low smoke point than other cooking oil so it's not good at high temperature. In case you are not a science geek, "smoke point" is a term defined as the temperature at which compounds in oil broke down and decompose into smoke. It's said that cooking at a temperature higher than smoke point of the oil you use is bad because it affected flavors, causing volatile polymers to form which may be hazardous to your health, etc etc. (if you want to know more about the exact chemical reaction involves, please read this article: http://onlinelibrary.wiley.com/doi/10.1111/j.1750-3841.2007.00352.x/full)
Different types of oil has different smoking point. Most of the cooking oil were refined (whether that be corn, peanut, sunflower seed etc) which generally has a higher smoke point, at about 230-250C (450-480F). So how about Olive Oil? Well, Bertolli, one of the more common supermarket brand in US and where I live (Hong Kong), listed their "Classico" Olive Oil at 460F (238F) and Extra Virgin Olive Oil at 406F (207C).
So the argument is true right? That because of lower smoke point we should avoid Extra Virgin Olive Oil. Well, not so fast. At least not until you ask the next logical question - what temperature do we usually cook at? Without going too much into details (don't want you to be bored with terms like protein coagulation and Maillard reactions which essentially were the process in which food was "cooked"), let's just take my words that 160C (320F), give or take, is the temperature we usually cook without burning anything. Even at the extreme case - say you want to deep-fry your chicken pieces to a perfect golden brown crust - USDA recommended doing it at 375F, or 190C). Not that I am advocating your start pouring extra virgin olive oil into your deep-fryer, but I am just trying to show in almost all cases, we hardly touch the smoke point of cooking oil so whether it's higher or lower is irrelevant, apart from the argument that the difference in smoke point is relatively small. So, next time if you burn your oil in the pan - whether that be corn oil or extra virgin olive oil, it's the problem with your skills, not the oil itself. You don't need to cook at a temperature above the smoke point in the first place.
Another argument is that Olive Oil "oxidizes" when heated - and oxidant is bad (that's why we keep hearing in commercials anti-oxidant is good to your skin, your body, your everything) That's another silly non-argument. First, all oil (containing different kinds of fatty acids in various proportions) oxidizes when exposed to air and more so at high temperature. Again, without going too much into the details of different types of fatty acids and their chemical reactions with oxygen, let me just say saturated fatty acids is more stable than monounsaturated fatty acids, which in turn is more stable than polyunsaturated fatty acids under heat. (feel free to google if you need to know why - something to do with the quantity of double bonds in fatty acid)
Still with me? Okay. Here's what may surprise you - most vegetable oils contain more polyunsaturated fatty acids than saturated and monounsaturated fat - except palm, coconut and olive oils. So olive oil - extra virgin or not - is actually more stable at high temperature as far as controlling the level of oxidation goes. For example, Crisco Corn Oil, another mainstream brand, has 57% polyunsaturated fat and 43% saturated and monounsaturated fat, while on the other hand, olive oil - extra virgin or not - has over 85% saturated and monounsaturated fat. Not only that, olive oil is rich in polyphenols, a type of anti-oxidant, which in a way could balance out the harmful effects of oxidation, and is healthier.
And don't be fooled into thinking "Refined" is good - it's just another word of saying "Processed", which involved a series of chemical extractions (other than physical or mechanical pressing) and tweaking the flavors and colors. Even worse is the loose food label law in Hong Kong meant "Olive Pomace Oil", which extracted from the leftover of olives including skins, seeds and stems in addition to some pulp, could pass off as "Olive Oil", a practice specifically forbidden in most western countries. Some countries even banned the sale of olive pomace olive oil as cooking oil or warned against its use because of the chemical solvents and heat required for oil extraction. UK's Food Standards Agency even called it "the lowest grade of oil".
With the lack of specific guidelines in Hong Kong, some importers did keep the term Olive Pomace Oil in English, but in Chinese conveniently omitting reference to "Pomace", thus they can continue to claim they were conformed to EU lableing standard. In the process of my little research online, one food distributor even touting the use of olive pomace oil as a proper substitute to olive oil, as if everyone's doing it. Needless to say I was horrified.
|Here are the detailed information of the bottle above - using the traceability label present on every bottle|
So I am resting my case about whether Extra Virgin Olive Oil being inferior in terms of food safety. The fact, as I found out, was the contrary to common belief. But is there any merit at all that Extra Virgin Olive Oil may not be preferred for cooking? Well, I could actually think of two somewhat more reasonable arguments.
|Not all olive oils are created equal - as we found out during our olive oil tasting session in Tuscany a few years ago.|
The second argument is price. Extra Virgin Olive Oil generally costs more than 50% than regular ones, so it's not cost effective to cook with it as compared to the regular ones, given the amount required. That's certainly fair, but it still doesn't make Extra Virgin Olive Oil unsuitable for cooking per se. Same as you probably wouldn't use your bottle of Charteau Latour for Coq au Vin, but that doesn't mean it won't make an excellent dish - I haven't been crazy enough trying to prove this myself but if anyone did, please let me know.
I hope these points helped you in making your own educated judgment of whether you should use Extra Virgin Olive Oil for cooking, instead of relying on hearsay or incomplete information or urban myths. For me, I certainly wouldn't hesitate to cook with my Extra Virgin Olive Oil at home.