Yes EVOO contains good fats – but are all EVOO’s the same?
admin | February 27, 2010Extra 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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