Slick Extra Virgin

It’s the world’s biggest selling edible fat. It’s cheap and available in a store near you. At around half the price of your cheapest extra virgin olive oil, it’s often what consumers reach for when they need to buy that oil to ply their salad or oil up the pan. But what is it, how is it made and what’s in it? Here’s the rub.

Made from: Soybeans

Commercially known as: “vegetable oil”

% of total world edible oil production: 23% (Rank #1)

Major producers: US, Brazil, Argentina, China, EU

Uses: cooking oil, salad oil, margarine.

Photo: Courtesy USDA

Oil yield: 16-22%, Average: 18-19% – 200 litres/acre.

The Fats in soybean oil: The proportion of fats that make up vegetable oil and extra virgin olive oil are very different (see figure below.) Vegetable oil is high in polyunsaturated fats, linoleic acid and linolenic acid. Both types of fatty acid are much more prone to oxidation than  monounsaturated fats which are predominant in EVOO. In fact, linolenic acid is over 70x less stable than the monunsaturated oleic acid. Soybeans contain a massive 7-10% linolenic and and varieties have been genetically modified to produce only around 1% (around 2x that found in EVOO), in an effort to make the oil more attractive for food service where oils are repeatedly heated and cooled.

How vegetable oil is made:

1. The soybeans are crushed
2. The oil is solvent extraction using hexane
3. The oil is degummed, caustic neutralised, bleached and deodorised (collectively known as refining).
4. Hydrogenation can be used to reduce polyunsaturation.

Preservatives added : Combinations of Butylated hydroxyanisole (BHA), Butylated hydroxytoluene (BHT), propyl gallate, ascorbyl palmitate and tert-butyl hydroxyquinone (TBHQ).

Other interesting bits and pieces – make of it what you want:

90% of US soy production is genetically modified to be either “Round-up resistant” and/or to reduce linolenic acid content.

High 80% and medium 55% oleic version have been bred to mimic the fat structure of olive oil.

Around 0.5kg of the neurotoxin hexane is lost per tonne of oil produced. Based on the annual production of 31 million tonnes, this amounts to up to 15,500 tonnes of hexane being released into the atmosphere each year as a result of vegetable oil production.

A lucrative by-product of soy oil production is high protein soy meal used for animal feeds.

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I give my top 10 myths surrounding Extra Virgin Olive Oil ……

Myth No. 1 – Extra virgin olive oil is made from the first cold pressing of olives.

Can be, but doesn’t have to be!

Extra virgin olive oil (EVOO) is officially defined as the oil extracted from fresh olives using a mechanical process without the use of excessive heat, additives or solvents.

“Mechanical” is the key word here. Most EVOO’s that are made in commercial relevant quantities are not made by pressing but by centrifugation whereby the lighter olive oil is spun away from the heavier components of the olive such as water and pulp. Still mechanical, still EVOO.

A centrifuge used to separate EVOO from olive water and olive flesh, stone and skin.

Myth No. 2 – Refined olive oil such as pure and light olive oil is made from the second pressings of the olive.

If you don’t press, then you can’t second press!

Refined olive oils usually start their lives as very poor quality olives which typically have fermented to some degree prior to being processed. The extraction process that is used to pull the oil out of these poor quality olives is the same as that which is used to produced good quality EVOO. But the end result is an oil that tastes so bad that it needs further radical processing to render it edible. The process is called refining and amongst other things it removes all the flavour from the oil –both the good the bad and the ugly. The final result is a bland product that is sold under the names ‘pure’, ‘light’ and ‘olive oil’.

Myth No. 3 – When making EVOO, the olives are crushed using heavy mill stones.

Very romantic but the days of granite crushing stones powered by donkeys is pretty well gone. Stone milling is very slow and the resulting olive paste is subject to oxidation. Today, most of the olives that are destined to become EVOO are crushed using motor driven means, the most common being the hammer mill. The hammer mill consists of an outer stainless steel screen and an inner rotating arm powered by a high speed electric motor. The olives are squished between the screen and the rotating arm resulting in a relatively oxygen free paste.

Donkey replacement – A hammer mill showing the perforated screen and rotating arm.

Myth No. 4 – Extra virgin olive oil that is made by pressing is better than those made using a centrifuge.

A few years ago some scientific research was published that suggested that this was the case. However, there are two types of centrifuge – the early model (early 1970’s) 3 phase and the late (mid 80’s) model 2 phase. This research compared pressing with oils from 3 phase centrifuges. For a 3 phase to work, water must be added to the olive paste prior to the oil being extracted. The addition of water causes some of the healthy polyphenols and flavour to be lost from the oil. However 2 phase centrifuges work without the need for adding water so EVOO’s made using these systems have the same or more healthful polyphenols and flavour as do oils made using a traditional press.

The big advantage of either centrifugal system over pressing is that it is much easier to keep a centrifuge clean. The mats used in pressing can be quite absorbent (there are a number of different types) and tend to hold oil which can inadvertently taint forthcoming batches of olives. Centrifuges can be more easily maintained to spotless standards. The bottom line is that in general EVOO’s made with centrifuges are more consistent than those that are made using your average press.

Also when you think about it, there is nothing inherently special about a press except that they have been used for a long time – but so has the wheel –and I don’t see too many Model T Fords on the road any more.

Myth No. 5 – Extra virgin olive oil made using a press is healthier for you than those made with a centrifuge.

Quite the contrary. The process of centrifugation is by nature, a rapid and enclosed process that protects the oil from oxygen during the separation process. This means that the naturally occurring antioxidants in the oil are conserved and end up in the bottle. If you expose the health giving antioxidants in olive oil to oxygen before they are bottled, then they by definition are used up. Better to have them in the bottle so they can help you stay healthy.

Myth No. 6 – Extra virgin olive oil that is clear has been filtered.

Well it might be but it probably hasn’t. If you leave a cloudy olive oil in a tank for even a relatively short time, the grungy bits will naturally settle to the bottom under gravity. Decant the clear oil off the grungy bit and whollah… clear oil ready for bottling. How gorgeously natural is that. Filtering oil is a tedious and messy business. Why bother mucking about with filters when you can let gravity do the work.

Myth No. 7 – You can’t refrigerate extra virgin olive oil

Refrigeration is a very effective way of prolonging the shelf life of EVOO. While some oils may partially solidify due to the oil containing naturally occurring levels of saturated fats and/or waxes, they will return to their normal state when they warm to room temperature. The aroma and flavour of the olive oil should not be affected in any way by refrigeration.

One small word of warning. There is some evidence that multiple thaws of oils can slightly shorten its shelf life. So if you use little bits and pieces very frequently then it is a better option to find the coolest dark place where the oil doesn’t solidify (say 10-12C) and leave it there.

Myth No. 8 – You can’t cook with extra virgin olive oil.

Good quality extra virgin olive oil smokes at a higher temperature than poor quality EVOO. In fact the smoke point of good quality EVOO is quite respectable and as such they can be used for shallow frying without any hassles at all. You can even get away with deeper frying with a little care (most foods will deep fry at temperatures below the smoke point of good EVOO), but realistically the economics of deep frying with good quality EVOO is pretty questionable given their premium price compared with other oils.

Myth No. 9 – Cloudy extra virgin olive oil is more healthy for you than clear EVOO.

There is absolutely no evidence for this. Most clear EVOO’s get that way by natural settling under gravity and not by further processing. So why wouldn’t they?

Myth No. 10 – The greener the oil the better it is for you.

For some, green just shouts freshness. But like many things EVOO, it’s not always what it seems.

For some varieties, green oil means that the olives were picked when they were pretty unripe and at a time when they were full of healthy polyphenols – hence the myth.

However, this pretty basic rule doesn’t always hold. Some varieties like Koroneiki and Verdale tend to make greenish oils regardless of their polyphenols level. Cool climates also tend to favour the production of the green pigment chlorophyll, so oils with the same colour but grown under different climatic conditions can have very different compositions.

Look at the oils labeled A-D below. These were sampled from a recent Australian EVOO competition. The oil on the far right, while being nearly an opaque emerald green had only a moderate amount of polyphenols (170mg/kg). It was a Verdale oil from the very cold marginal olive growing climate of Tasmania. The second from the left came in at a massive 620mg/kg of polyphenols. The colour definitely belied what was actually in the oil. Lots of golden coloured EVOO’s have very high polyphenols and are pristinely fresh. So in short don’t get too tied up with the colour of EVOO.

But then again if green is your favourite colour then go for it. I must admit that it always looks great on the plate….

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Just a little something to help you describe the flavour of extra virgin olive oil. Technically if the oil has any of the defect characters listed in the brown part of the table then it shouldn’t be called an extra virgin olive oil. But unfortunately some oils that are labelled as extra virgin grade have these undesirable characters.

Some of the descriptors might seem a bit strange, but most of the weird terms apply to lesser known varieties. For example, if you are a fan of Tuscan or Californian EVOO then you almost certainly would have not experienced the unusual (yet not unpleasant) flavour of crushed ants that is typical of the variety Nevadillo Blanco when it is picked early, or the guava like flavours which are sometimes seen in extra virgin olive oils made from the Spanish variety Picual when it is picked late in the season.

If you are interested in a snazzy list of olive oil tasting terms then you may wish to check out my olive oil tasting wheel at www.aromadictionary.com/oliveoilwheel.html

You can obtain a pdf version of this at: www.aromadictionary.com/oliveoildescriptorlist.pdf

Richard Gawel

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Extra virgin olive oils (and indeed all edible fats) are actually a complex mixture of different fats – saturated, monounsaturated and polyunsaturated. The major fat in olive oil are the monounsaturated type. Other seed and vegetable oils have a different combination of these fats, but with the exception of some carefully created ‘high oleic’ versions of sunflower and rapeseed oils, all contain a lower proportion of monounsaturated fats than does extra virgin olive oil.

From a consumer point of view, oils with higher levels of monounsaturated fats are preferred by the health conscious as they are thought to reduce the damaging LDL and increase the good HDL in the blood. Monounsaturated fats also turn solid at lower temperatures than do saturated fats, so oils with higher levels of monounsaturated fats are less likely to solidify if stored in the refrigerator. Most importantly, monounsaturated fats are more resistant to oxidation than the polyunsaturated fats (like those found in abundance in flaxseed, rice bran and sunflower oils). Olive oils contain a higher proportion of monounsaturated fats which helps them maintain their freshness substantially longer than the poly-mob (which incidentally need lots of artificial preservatives to give them shelf life).

For these reasons, the relative proportion of monounsaturated to the other fats (known as the fatty acid profile) is of great practical importance.

The diagram below shows a ‘typical’ fatty acid profile of Australian extra virgin olive oils. These proportions are the average of over 500 EVOO’s submitted for analysis to one of the major testing laboratories in Australia. Thanks to Dr Rod Mailer from the NSW Department of Agriculture Oil Testing Laboratory for letting me present this data. While these are Australian oils, they are pretty representative of anything you will find throughout the world.

The predominant fat in olive oil is the monounsaturated fatty acid, oleic acid (or C18:1 on the diagram).

While all olive oils are high in monounsaturated fats, some are higher than others. So what determines the low from the high. The major determinants of monounsaturated fat content in EVOO are the variety of olive which the oil is made from, and the climate in which the olive is grown.

Some varieties like Arbequina which is widely grown in California and Catalonia generally have a lower percentage of oleic acid compared with other varieties. Others like Picual which is widely grown in Andalucia and also Australia are high oleic varieties as do the varieties Koroneiki and Coratina. The fatty acid profiles of a large sample of Australian extra virgin olive oils is given below (Figure created from the data of Mailer and Ayrton 2008). An Argentinian study also confirms these differences between the varieties Arbequina, Picual and Barnea (Ceci and Carelli 2007)

Before I get a barrage of comments from my American friends, it’s worth noting that Arbequina has strengths in other areas. It makes delightfully fruity versatile oils with generally low levels of bitterness. Great for those delicately flavoured dishes that don’t need that big hit of bitterness or pepper.

To the climate. Extra virgin olive oils grown in cooler climates generally have higher levels of the monounsaturated oleic acid and lower levels of saturated and polyunsaturated fats than extra virgin olive oils grown in warmer climates. So here in Australia it is not usual for EVOO’s grown in the cold almost English like climates of Tasmania to have oleic acid levels around and above the International Olive Council upper limit of 85% (presumably quite a few New Zealand EVOO’s would be in the same boat). Isn’t it strange that wonderfully pristinely flavoured EVOO’s with massive levels of the healthy fat oleic acid and tons of antioxidants could be denigrated under international convention to the level of ‘fruit oil’ under International Olive Council regulations. Unless you’re adding industrial green pigment chlorophyll to high oleic sunflower and passing it off as EVOO, then you don’t need an upper limit for oleic acid. Mmmm… come to think of it it happened in Italy recently. But still, if they were just a bit smarter they could have added a few percent of normal sunflower oil and they could have come in under the 85% upper limit. So go figure why the IOC would have an upper limit on the fat that everyone buys olive oil for!

So how can you tell what the fatty acid profile of an EVOO is? This is tricky… The labeling laws in many countries specify that the fatty acid profile must be given. Try looking at the back label. You may find the alleged amount of mono, poly and saturated fat in the product. However, the fine print often says that the values given are just an ‘average’. The fatty acid profiles of large supermarket brands vary from batch to batch as they are nearly always blends of oils from different regions and even countries (even if it does say ‘Product of Italy’!). So as the blend changes so does its fatty acid profile. Smaller producers often get their oils analysed by a laboratory just once, and use the result from year to year. The fatty acid profile from oils made from the same place doesn’t change much from year to year, but if the producer blends in oils from a new variety that they have that is coming on stream then its fat profile will almost certainly change. I can’t see the average small producer discarding thousands of labels because of a small change in the profile particularly given that the stated profiles of the larger supermarket brands are just rough estimates of what is actually in the bottle. Finally, many small producers just take the ‘recommended percentages’ off their trade association’s website. So in short, the back label probably isn’t a reliable source of information about the oil’s fatty acid profile. Asking the producer directly is probably the best option.

By the way, all the fatty acids in olive oil are odourless and tasteless, so the fatty acid profile doesn’t tell you anything about what the oil smells or tastes like.

Sources:

Mailer, R.J. and Ayrton, J. (2008) A survey of Australian olive cultivars to determine compliance with international standards. RIRDC Publication No. 08/167.

Ceci L.N. and Carelli, A.A. (2007) Characterization of Monovarietal Argentinian Olive Oils from New Productive Zones J. Am. Oil Chem. Soc. 84:1125–1136.

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Yes you can!     And yes you should….

One of my twitter followers/friends recently asked if extra virgin olive oil can be safely stored in the fridge. They heard somewhere that “the shelf life is reduced, and valuable polyphenols are lost during refrigeration”.

While I have heard this before I couldn’t recall seeing anything solid. However, on face value this seemed rather strange as we generally refrigerate foods so as to slow down oxidation rather than to speed it up.

After a thorough search I found that somewhat surprisingly, that only two scientific papers have reported the effect of refrigerating extra virgin olive oils. One was probably the one that my twitter friend was referring to.  I read both the abstract (the summary which is freely available) and the whole paper (which is not). I’m not surprised that the abstract led many to believe that refrigeration was detrimental to maintaining EVOO quality. However on close inspection the actual results clearly suggested otherwise.

In this work, a single EVOO was stored in the fridge at below its melting point 3C, and at 25, 40 and 60C (Calligaris et al. 2006). The oxidative state of the oils were monitored over a 7 month period using a well known measure called peroxide value.  They found that this EVOO when stored at 3C had almost exactly the same peroxide value over the entire 7 month period as when it was stored at room temperature (25C). Now as scientists this must have seemed a bit unusual as one would expect that the oil stored at the cooler temperature would have a lower peroxide value. Based on this they surmised that: “below the melting point , the oxidation rate was found to be higher than expected”.

‘Higher than expected’ yes, but the oxidation rate of refrigerated oil was still about the same or lower than when stored at room temperature. Unfortunately, this practically important last little bit didn’t make it into the summary. Here are the results read from their paper (Figure 4). You can see for yourself.

So despite what appeared to be reported in the summary, storing oils in the fridge was the best option of all those studied.

Ok some would be thinking… so it appears that storing the oil at room temperature is just as good as stroring in the fridge so I’ll just leave it in my pantry. Well maybe, but then again maybe not. The polyphenol level of the oil used in the study was a massive 772 mg/kg. This is around 3 times the average polyphenol level of your typical EVOO (Gawel and Rogers 2009).  Polyphenols are antioxidants, so in this particular case, the polyphenols are providing a massive amount of protection against oxidation. That particular oil probably could have withstood a nuclear test blast in the Nevada desert in 1952 and still be edible today. Whether an EVOO with a more typical polyphenol level of around 200-250mg/kg would have stood up that well at room temperature is debatable. That’s the risk of doing research using a single oil-particularly an odd one!

The abstract also reported “a decrease in polyphenols in the liquid phase” upon refrigeration. Anyone that read this would naturally think that the polyphenols disappeared as a result of refrigeration. It was an unfortunate use of terminology. What the authors were referring, was not the oil in its entirety after being thawed, but only the little bit that was still liquid at 3C. The polyphenol level of the entire oil after thawing wasn’t reported, but my guess is that it would be pretty similar to or higher than the oil stored at 25C (oils with lower peroxide values tend to keep their polyphenols longer). Ok that low phenolic liquid bit would be more prone to oxidation while sitting in your fridge, but the fact that it only made up around 20% of the volume and is being held at 3C has to be taken into consideration.

The second study on cold storage of EVOO’s showed similar benefits (Prenzler et al. 2007). Here a relatively low polyphenol EVOO was stored in 100ml bottles at room temperature, and the same oil in the fridge at 1^oC. After twelve months, the polyhenol reading of the room temperature oil was 148 mg/kg. The same oil stored in the fridge had a polyphenol level of 185 mg/kg.  Yes that’s right, refrigeration helped retain polyphenols, not destroy them. In addition the free fatty acidity, and all measures of oil oxidation (peroxide value, K232 and K270) were lower for the oil stored in the fridge.  Sure the authors did correctly report that the oil did age somewhat when stored in the fridge i.e. when compared to the oil when new. You wouldn’t expect any different unless the researchers used a cryogenic device like that in the Jupiter II in ‘Lost in Space’. But the important point is that the fridge stored oil did better than the room temperature stored oil on all counts of quality.

There are two relatively small issues in storing oils in the fridge. Firstly, once opened and resealed, the bottle has the potential to trap humidified air which may condense on the inside of the bottle which in turn has the potential to cause the oil to tire. This is probably only an issue if you constantly take the oil out of the fridge over a long period of time, and then again I think that the benefits of slower oxidation outweigh the potential costs. Secondly, very occasionally some oils refuse to thaw completely when taken out of the fridge. This is because some of the natural waxes found in EVOO just refuse to go back into solution. Don’t be concerned. The few chunky bits are harmless and will definitely disappear if you heat up the oil when cooking. I’ve only seen two cases of this in thousands of bottles so I wouldn’t loose any sleep over it.

For good measure here are the papers I’ve mentioned and yes, the blatant yet obligatory self citation.

Calligaris, S., Sovrano, S., Manzocco, L. and Nicoli, M.C. (2006) Influence of crystallization on the oxidative stability of extra virgin olive oil. Journal of Agricultural and Food Chemistry, 54, 529-535.

Gawel, R. and Rogers, D.A.G. (2009) The relationship between the total phenol concentration of virgin olive oil and their style as determined by their producers. Grasas y Aceites, 60, 134-138.

http://grasasyaceites.revistas.csic.es/index.php/grasasyaceites/article/view/560/574

Prenzler, P., Robards, K. and Bedgood, D. (2007) Quality enhancements of Australian extra virgin olive oils. Rural Research and Development Corporation Report.

https://rirdc.infoservices.com.au/downloads/06-135.pdf

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By international convention, all extra virgin olive oils SHOULD be free of any taste defects. However, in reality a number of faulty olive oils do make it onto the market – sometimes intentionally – other times the producer just doesn’t know that their oil has a problem . So if you buy an EVOO and it seems to taste a bit funny, consult the following table. At least you’ll know what the problem is!

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In my previous post I mentioned some of the recent research outcomes concerning the healthful phenolic called oleocanthal which is only found in extra virgin olive oil. Here are my summaries of the research, together with links to the authors summaries (abstracts).  I read all the papers and try to pick up on what I think is relevant to the producers and the users of extra virgin olive oil.  Hopefully I’ve done them justice.

The compound mainly responsible for pepperyness was identified as deacetoxy-ligstroside aglycon (now called oleocanthal). Andrewes et al. (2003) http://www.ncbi.nlm.nih.gov/pubmed/12590491?dopt=Abstract

The pungency producing and anti-inflammatory phenolic Oleocanthal was resistant to degradation during prolonged heating falling by less than 16%. However, its biological activity fell by around a third when heated under the same conditions. Cicerale et al. (2009) http://www.ncbi.nlm.nih.gov/pubmed/19166297

Median a-tocopherol levels of 263 Italian EVO’s reported as 151 mg/kg and the pungent oleocanthal as 85 mg/kg (94mg/litre). Servilli et al. (2009) http://www.ncbi.nlm.nih.gov/pubmed/19234678

Oleocanthal induced pungency was mostly perceived at the back of the throat and was most intense at 15 seconds. Significant variation between individuals was observed. Cicerale et al. (2009) http://chemse.oxfordjournals.org/cgi/content/abstract/bjp006

Compared with oleuropein and hydroxytyrosol the ‘peppery’ phenolic oleocanthal best protected red blood cells from oxidative stress. Paiva-Martins et al. (2010) http://pubs.acs.org/doi/abs/10.1021/jf9031052

Low doses of the major extra virgin olive oil polyphenol oleocanthal modifies amyloid-β_1-42 peptide the neurotoxin implicated in Alzheimers Disease. Leads to less synaptic and neuronal deterioration. Pitt et al. (2009) http://cat.inist.fr/?aModele=afficheN&cpsidt=22114732

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In 2003 something really exciting happened to the world of extra virgin olive oil (EVOO) –but most people missed it. It was buried within a Dutch research paper which tentatively reported the sensory properties of the different types of polyphenols found in EVOO. For years we knew that the total amount of polyphenols in an EVOO strongly correlated with its combined level of bitterness and pepperyness – EVOO’s high in polyphenols were almost always really bitter and/or peppery and vice versa. But there are dozens of different types of polyphenols in EVOO, but with the exception of a couple of them, no one knew what each of the individual types contributed to the overall taste of EVOO.

It was really clever work. The researchers got a bitter and peppery EVOO and extracted the total pool of polyphenols from it. They then pumped this extract through a bed of sticky material specifically designed to grab phenolics. They then removed each of the different phenolics off the bed one by one by washing using stronger and stronger solvents. After the solvents were removed, the different phenolic fractions were tasted and described by a trained taste panel.

They were tasted one by one… the first bitter, the second bitter, then very bitter, a little astringent, ….. peppery as hell…., bitter, bitter… Hang on a minute, go back!… peppery as hell!  A lot of EVOO’s are peppery and throat catching but until that time no one knew what caused it. Here was the first clue.

The phenolic was tentatively identified as deacetoxy-ligstroside aglycone or p-HPEA-EDA, later to be given the more digestible name, “oleocanthal”. The name derives from the latin oleo=olive, “canth”=sting – referring to the peppery throat catching sensation that it causes, and “al” from the fact that the phenolic was in the aldehyde chemical group.

The find was really exciting. While the Mediterranean diet has long been lauded for its healthfulness, I always thought that there was something special about it that we didn’t know. Similar dietary patterns containing lots of monounsaturated fats and polyphenols didn’t seem to confer the same benefits. ‘That’ peppery sensation was unique to EVOO (and by definition to the Mediterranean diet). So I always felt that it was an important marker of the healthy Mediterranean diet (so much so that I tried to find it in myself while working for the University of Adelaide in 2000, but my scientific hunch as to what it might have been was a little astray).

The potential importance of oleocanthal became immediately apparent. Firstly, many EVOO’s were found to have lots and lots of it. Almost every other week some new phenolic is discovered in some food or other. However in most cases, only miniscule amounts of the stuff is found – a few parts per billion here or there. Oleocanthal was different. A survey of over 250 Italian EVOO’s showed that the average amount of oleocanthal in EVOO wes around 100 milligrams per litre (1/10^th of a gram per litre). Ok the oils were Italian, but there is no reason to believe that EVOO’s from other places are any different. EVOO’s from elsewhere were found to contain up to 300 mg/kg (1/3 of a gram per litre) of oleocanthal. This might not sound much, but take it from me, that’s an absolute mozza for a single phenolic in any food. It is the second most abundant phenolic in EVOO and contributes up to around 35% of their total polyphenol content.

One of the first things that scientists noticed was oleocanthal’s similarity to the anti-inflammatory painkiller Ibuprofen. Not surprisingly, Ibuprofen is also a pretty pungent number. In fact its rather unpleasant ‘taste’ tipped off the scientists to look into the similarities between the two.  Their studies on oleocanthal showed that, like Ibuprofen, it too was a powerful anti-inflammatory. So what does this mean? One of the preliminary steps to coronary heart disease is the inflammation of artery walls following blood macrophages attacking oxidised LDL’s. Anti-inflammatories block this all important step to coronary heart disease.

Later work showed that oleocanthal is also one of the most powerful antioxidants in EVOO, making others like the much lauded hydroxytyrosol look pretty lightweight in comparison. Antioxidants such as polyphenols hitchhike on the nasty LDL’s, which increases its resistance to oxidation, which in turn reduces the havoc the LDL can cause on our cardiovascular system. Recently, oleocanthal was also reported to be extremely effective in reducing the oxidative stresses on red blood cells. A fortnight go, it was reported that oleocanthal suppresses the formation of certain proteins which are thought to coat neuronal connections resulting in Alzheimers and other degenerative neural disorders. So health wise, oleocanthal is ticking all the right boxes. I seriously doubt that we have heard the end of it either.

Luckily, oleocanthal is also pretty resistant to degradation by heating, although there is some suggestion that it loses some of its protective abilities after being heated. Logically, this suggests that oleocanthal works in combination with other antioxidants s in protecting us. However this possibility has not been explored to date. It also resists degradation during storage. While all polyphenols decline in the oil over time, oleocanthal holds on better than most, particularly when stored in cool conditions.

Great news on lots of fronts:

It’s easy to get – eat EXTRA VIRGIN olive oil. NO OTHER food has it. (Note that refined olive oils such as “pure”, “light” and “olive oil” do not contain oleocanthal.  It, like other phenolics, is removed during the refining process).

Easy to get lots of it – Use peppery extra virgin olive oil. It’s super rich in the stuff.

So how can you tell which EVOO’s have lots of oleocanthal? Well you won’t find it on back labels any time soon. The method used to analyse the amount of oleocanthal is not in widespread use, primarily because the pure standard of oleocanthal which chemists need to positively identify it (and quantify how much there is) isn’t widely available. But if the EVOO you are using is nice and peppery then almost certainly you are getting a liberal dose of oleocanthal in your everyday diet.

Just a personal opinion, but I believe that oleocanthal will be known as one of the most important anti-oxidants and anti-inflamatories in the western diet. Watch this space. There is a lot more to the oleocanthal story which is yet to unfold.

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What are Polyphenols?

Extra virgin olive oils contain a healthy suite of  naturally occuring antioxidants called polyphenols.  While polyphenols are widely distributed in nature, being found in many fruits and vegetables and in healthy beverages such as green tea and red wine (to name a few), most of the polyphenols found in extra virgin olive oil are unique. I guess this isn’t surprising as the olive oil types have to be fat soluble while the other types need to be water soluble. Read on to find out what role they play in the taste, healthfulness and shelf life of the extra virgin olive oil.

What do Polyphenols Contribute to the Taste of Extra Virgin Olive Oil?

Most of the phenolic compounds found in olive oil are not volatile, so they do not contribute to the aroma or flavour of the oil.  However, they are bitter and pungent (peppery), so they add significantly to the unique taste of many extra virgin olive oils.  It is now known that some types of polyphenols are bitter while other types produce the peppery, or throat catching sensation. The major contributor to pepperyness in extra virgin olive oil was discovered in 2002 and has since been given the name “oleocanthal”. It’s such an important phenolic health wise that I’m reserving a dedicated post to it.

The Role of Polyphenols in Olive Oil Shelf Life?

Polyphenols are powerful antioxidants so by their nature they react very readily with oxygen.  Therefore any oxygen molecule that finds its way into the oil will react with any polyphenol it encounters before reacting with the  fat molecules.  That’s how polyphenols naturally protect the oil from getting tired and (ultimately) rancid. However as each polyphenol can ‘do its thing’ only once, sacrificing itself in the process, they are naturally used up over time. In fact, even under good storage conditions, around 40-60% of the polyphenols of an EV oil are used up in the first 6 months. This protective role of polyphenols also explains why milder oils (which are low in polyphenols) generally have shorter shelf lives than the more bitter and peppery robust styles (which are rich in polyphenols).

The Role of Polyphenols in Health
Free radicals can be thought of as oxygen molecules on steroids! They damage human cells causing aging, but in extreme cases can also result in cell mutation leading to certain cancers.  Polyphenols are strong antioxidants and just love to scavange and mop up the free radicals from our bodies.  Free radicals also oxidise LDL (the proteins that carry the “bad cholesterol” around in the bloodstream), which eventually leads to plaque deposits forming on the walls of our arteries.  Olive oil antioxidants can disrupt this first important oxidative step which ultimately leads to a reduced risk of coronary disease.

In short, the polyphenols found in extra virgin olive oil have the capacity to react with the nasty free radicals before they adversely react with you!

What About Other Edible Fats

Canola oil, vegetable oil and olive oils such as ‘Pure’ , ’Light’ and ‘Olive Oil’ contain essentially no polyphenols, so they do not provide the same potential benefits of extra virgin olive oil. The refining process common to all these oils strips them away. In some cases, artificial antioxidants like ascobyl palmitate are added to the refined oil to improve their shelf life. While this is just a fat soluble version of Vitamin C, it probably doesn’t provide any health benefits.

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Perhaps the most frustrating part of selling extra virgin olive oil is when a potential customer says “why is your oil so damn expensive. I can buy olive oil at my local supermarket for $5″ . Almost certainly they are referring to the stuff sold as “Olive Oil” (or maybe “Pure” or “Light” olive oil) . Of course what they fail to realise is that the oil they are referring to is a refined product. But what does refining involve? Here is the low-down on the refining process.

The end result is a bland oil with:

1)   0% Free fatty acidity

2)   no colour, aroma, flavour

3)   no bitterness or pepperyness

It’s worth noting that despite the pretty radical processes involved in refining there is no solvent extraction at any stage. That’s reserved for pomace olive oil.

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