About cooking and frying with olive oil
Olive oil 101
A staple of the Mediterranean diet, but still cooking with olive oil has some myths attached to it. Dutch people, in particular, will often ask me: "Is baking and frying with cold-pressed extra virgin olive oil actually safe or do we need refined pomace olive oil for that?" And my short answer to that is: “Yes, it's absolutely safe, but please read more to take your own decision”
The Importance of the Smoke Point
The suitability of your favorite vegetable or animal oil for cooking depends chiefly on its so called “smoke point”. This is the temperature whereby - quite suddenly - a foul smelling blue or black fume of smoke evolves from your frying pan. One or more components of the oil start to burn and even inhaling the resulting soot and smoke is very unhealthy and can cause cancer. Obviously, overheating should be avoided. So oils with the highest smoke point should be the best for cooking.
Here are some smoke points from the Culinary Institute of America as published in 1996 by John Wiley & Sons: Clear Soybean Oil: 257º C. (495º F) Clear Sunflower Oil: 225º C.(440º F) Clear Extra Virgin Olive Oil: 190º C. (375º F) Lard: 190º C. (375º F) Shortening: 165º C. (325º F) Butter: 150º C. (300º F)
In practice, however, smoke points can vary wildly, because of free fatty acid content, but even more so because of the presence of tiny particles in the oil. These particles (coming from fruit pulp or fried food) burn much faster than the oil itself. As a consequence, cloudy oils will have reduced smoke points and you should limit re-using them for extreme cooking (deep frying and wokking) to no more than 3 times. Fresh Can Solivera Extra Virgin Olive Oil is initially slightly cloudy, but will clear up within 3 to 6 months by natural decantation in your container. The tiny particles of fruit pulp which come along and give unfiltered fresh olive oil its cloudy look, add an extra dimension to the original taste, much better appreciated at ambient temperature anyway.
Seed Oils and PAH’s
TRefined and pomace olive oil, on the other hand, are industrial products, which undergo scrupulous filtering at various stages during the process to the point where all color, taste and odor has been removed. Understandably, refineries heavily promote this product for cooking, but is it better? I think not. Not only because of lack of taste, but even more so because olive pomace oil is essentially a seed oil made from the semi-solid cake of crushed seeds, left in the mill after cold extraction. Along with olive pomace oil, all vegetable seed oils like corn, sunflower, peanuts, safflower, cotton, grape, soybean, pumpkin, canola, mustard, avocado and camellia fall in this category. Seed oils cannot be cold extracted, but must be obtained by a technique called “hexane extraction”. The use of this technique involves high temperatures (> 300 º C), which cause the birth of a group of chemical compounds called Polycyclic Aromatic Hydrocarbons (PAH’s) which end up in the oil and produce cancer. These – ironically - are the same PAH’s, which will spontaneously occur in your favorite cooking oil when inadvertently reaching its smoke point in your own kitchen! A heavy PAH called benzene(a)pyrene (BaP) is the biggest offender. Following an I.O.O.C. recommendation, the E.U. has reset recently the legal limit for BaP content in all edible oils and fats at max. 2 g/kg (Resolution 835/2011).
Refined Olive Pomace Oil (lowest quality)
This olive oil is produced in a distillery by means of hexane or heptane extraction at high temperatures. The raw material is not Lamp Olive Oil but rather the semi-solid olive cake called Pomace, which is left in the centrifuge after milling. It mainly consists of crushed olive seeds, but it still contains some oil, which can only be extracted by chemical means. Also spent filter sand, saturated with olive oil, which mills used to instantly remove tiny fruit particles, is a source of raw material for the distilleries. The physical appearance of Pomace Olive Oil is the same as with Refined Olive Oil and the acidity is artificially set at < 0.3%. Also the end users are the same as with Refined Olive Oil with the addition of the cosmetics industry.
A Devil’s Dilemma
There is one problem however: because of the high temperatures applied during the industrial process, a group of totally new chemical compounds is formed, both in Refined Olive Oil and even more so in Refined Olive Pomace Oil, called Polycyclic Aromatic Hydrocarbons (PAH’s), which are potentially carcinogenic. The level of the worst offender, a heavy PAH called benzo(a)pyrene, serves as a marker for the presence of other PAH’s of which fluoranthene, anthracene and chrysene are the most important. Unfortunately, these intruders can only be removed from the oil at high cost. Officials from olive oil producing countries have negotiated for years with the I.O.O.C. and law makers in Brussels to set a “safe” benzo(a)pyrene norm for human consumption of olive oil (presently max. 2 µg/kg in all edible oils). One way of lowering the benzo(a)pyrene content to legal levels is by mixing Pomace Olive Oil and Refined Olive Oil with some Virgin Oli