Let’s firstly look at why the belief came about in the first place, and then I’ll attempt to explain  explain why the fridge test isn’t a reliable indicator of extra virgin authenticity.

The myth probably arose because of two well known facts surrounding fats:

Fact 1: Extra virgin olive oil naturally consists of mainly monounsaturated fat (the legendary oleic acid).  Between 65% and 85% of olive oil is made up of monounsaturates, the remaining are saturated fats (about 15-20%), with polyunsatured fats making up the last few percent. On the other hand, some seed oils like sunflower are mostly comprised of polyunsaturated fats.

Fact 2: The melting point of monounsaturated fats are much higher than the melting point of polyunsaturated fats.

The predominant monounsaturated fat in olive oil has a melting point around the fridge temperature of 4^oC. That is, below 4^oC monounsaturated fat is a solid, but above 4^oC it is a liquid. In reality 4^oC is more of a transition temperature, whereby the fat is seen as a semisolid coagulated lump. On the other hand, polyunsaturated fats melt around a super-chilly minus 30^oC – as such, there is no domestic fridge that is cold enough to solidify them.

I guess you can see where I’m going with this. The myth arises because if extra virgin olive oil was purely comprised of monounsaturated fat, and if sunflower oil was purely comprised of polyunsaturated fat, and if there was nothing else in the oils which could complicate matters, then the fridge test would work perfectly every time. The extra virgin olive oil would ‘lumpify’ in the fridge and the sunflower oil wouldn’t.

But there lots of if’s there, so as you guessed, there are complications!

I used sunflower oil as the example above, but it is an extreme one as the oil contains one of the highest amounts of polyunsaturated fat. But, many seed oils actually contain quite a lot of monounsaturated fat. Canola oil for example contains around 50-60%, as does peanut oil. Some extra virgin olive oils contain only marginally more than this: 65% is the internationally accepted lower limit for EVOO.  So if you put either canola or peanut oil in the fridge then both of them will solidify to some extent. So for a start, these two oils can’t definitively be distinguished from EVOO on the basis of the fridge test.

And lastly, by definition, any olive oil that has had seed oil or olive pomace oil added to it isn’t extra virgin.  Most adulterated oils typically have relatively low percentages of non-olive oils in them, as the greater the dilution with seed oil, the easier the fraud is to detect.  Clever fraudsters will just add enough ‘other stuff’ so as to just make it difficult for authorities to definitively say that “yes this oil is fraudulent” without having to resort to expensive sophisticated testing and lengthy court cases. 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. Next to the authentic EVOO, it will look exactly the same.

* Here’s the math.

Assume typical values of : 100% extra virgin @ 74% oleic acid  and  100% canola @ 53% oleic acid

A blend of 90% extra virgin and 10% canola will contain = (0.9*0.74+0.1*0.53) = 0.667+0.053%

= 72% Oleic acid …… not much different from the 74% in the 100% EVOO

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• Sensory  - of course.
• Linguistic- for writing useful comments for exhibitors, and
• Interpersonal – as judges work in small teams of 3 or 4.

Every year I concentrate on building a particular skill required by show judges.  Themes have included – Measuring judge consistency, writing effective comments for the benefit of exhibitors, and understanding and dealing with diversity of EVOO styles and characters.

Judge Consistency

One of the most important requirements of a good show judge is the ability score consistently. Agreeing with yourself is a pretty good quality to have. One would hope that a judge that gives an oil a gold medal score when tasted on one occasion would give it another gold medal score if they were asked to score it on another occasion. While it would be nice to think that this could be done by all show judges all the time, I have to say that believing so is a little naïve. A couple of years ago I measured the consistency of over 500 wine show judges (and potential wine show judges) and found that a surprising number found scoring consistently was a tricky business (Gawel and Godden, 2008).  In my opinion, EVOO judging is more difficult than wine judging (I’ve done quite a bit of both) as the difference between an average quality and a high quality EVOO is much smaller than between the average and high quality wine.  So it’s no surprise that consistency scoring EVOO’s for quality isn’t as easy as many people might think.

So with the aim of measuring the consistency of the olive oil judges I presented them with 12 EVOO’s which they scored for quality. Later on that day, they were presented with 15 oils, 12 of which were the same as those scored in the morning – but in a different order of course. The judges were unaware that oils were being presented for a second time as I led them to believe that we were conducting a different exercise (I can be a complete bastard!).  I then correlated the scores given on the first occasion with those given on the second to the same oils. The results of the exercise allowed the judges to benchmark themselves against their peers.

Appreciating Style Differences

Every year I spend a lot of time at these workshops presenting diverse sets of EVOO’s – from different varieties and blends – early and later harvest – from different regions – mild through to very robust . All this is done to impress upon judges that it is bad form to penalise an oil because it either has or doesn’t have, a particularly flavour characteristic. The world of EVOO is wonderfully diverse – different flavour profiles and different levels of bitterness and pungency are necessary. Why? – because despite what some producers might tell you, no single style of EVOO can hope to be perfectly suited for use in every single culinary dish. While some styles might have a limited application compared with other styles, they all have their place ‘out there’ in one way or other. But there are high and low quality examples of each style, and recognising this is the point of the judging exercise.

So here were the results of the 2009 Perth Show which took place two weeks after the workshop.  I’ve given the average score for oils within polyphenols ranges. The higher the polyphenols level, the more bitter and/or peppery the oil (generally speaking), so the polyphenol level is a pretty good indicator of style.  I’ve also turned it around and given the average polyphenols level for each medal ranges, best of class and best of show.

*average of the highest gold medal scoring oil in each class

Lastly, if you’re like me and like seeing things in pictures, here is the plot of awarded score against polyphenol content.

The correlation between polyphenols level and score was a meagre 0.005 which was as close the magical random, ‘no relationship whatsoever’ value of 0 as you would hope to get.  In short on all the measures, the amount of bitterness/pepperyness had no bearing whatsoever on the scores awarded to the oils. This is the way it should be. Good oils should be awarded based on quality not style. Fluke perhaps? – well I just spent some time on the flight back from the 2010 Royal Perth Show and calculated that the correlation between score and polyphenols level again showed that there was no relationship between score and polyphenols level (aka style) – the correlation was 0.001

Writing Descriptions

Unlike EVOO shows elsewhere, the majority of Australian shows provide commentary on each submitted oil via the published show results booklet. The comments are written by the head judges of each panel, and are based on their opinion and those of the other two judges.  However, the comments can get a bit jargonny at times, and while they clearly mean something to the judges who wrote them, they may not mean much at all to the exhibitor. On the other side of the coin, the comments can be so generic that they mean little at all.

So in one workshop I presented a series of comments written by judges in another show (The Australian National), and simultaneously presented the oils to which they referred. The judges attending the workshop were asked to match the comments to the oils after tasting them. We then discussed at length exactly what aspects of the comment made it easy to identify the oil, and what aspects of the comment was confusing or resulted in an incorrect match of description to oil. The logic here was, well if you can identify the oil from its description then the description must be informative. After picking apart the value of the provided descriptions, the judges rewrote the comments in a way which they felt made for the briefest yet most informative comment. While I’d admit that the art of writing brief but useful commentary on oils is a work in progress, it was a good start.

Reference

Gawel, R. and Godden, P.W. (2008) Evaluation of the consistency of wine quality assessments from expert wine tasters. Australian Journal of Grape and Wine Research, 14, 1-9.

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Here is my interpretation and commentary on the statement. The statement verbatim is given in blue, and my comments are in green. Ok it’s long, but the points made in the statement whilst complex deserve to be discussed.

STATEMENT ISSUED BY THE INTERNATIONAL OLIVE COUNCIL ON THE REPORT PRODUCED BY THE UC DAVIS OLIVE CENTRE

A report issued by the UC Davis and Wagga Wagga laboratories concerning anomalies allegedly detected in olive oils imported into the United States has been brought to our notice by various associations and other information sources. Speaking as the Executive Secretariat of the International Olive Council (IOC) we wish to begin by saying that the IOC is recognised to be the leading authority on all aspects of olive oil and table olives. The United States takes part in the work of the Organisation through the IOC quality control scheme and the meetings of the IOC chemists, and is kept permanently informed on these activities.

One of the most significant regulatory tasks of the IOC laid down in article 1(2) of the General Objectives of the International Agreement on Olive Oil and Table Olives, 2005 is to develop the definitions and analytical characteristics of all the grades of olive oils and olivepomace oils included in the trade standards adopted by Members for compulsory application in international trade. The standards drawn up by the IOC are trade standards. They are adopted by consensus of the Members, which pledge to incorporate them into their legislation. According to article 22(1) of the International Agreement, headed Undertakings by Members, the Members of the International Olive Council undertake to apply the designations prescribed in Annexes B and C of the Agreement in their international trade and to encourage their application in their internal trade. In addition, article 22(2) states that the Council of Members will determine quality criteria standards applicable to the international trade of the Members.

None of this (Eurospeak) is relevant to the UC Davis report. The authors appear to be merely suggesting some legal jurisdiction, or at least some natural influence over matters involving olive oil sold in the US. What is not made clear by these opening paragraphs is that the IOC is a body that is funded by the EU, and their role and jurisdiction is defined by EU regulations. Its jurisdiction only extends to nations who are signatories to the international convention on olive oil (which is also a European creation). However they have no legal standing as to what are the ‘appropriate’ testing methods and standards outside of their member nations. The “Council of members” can determine “the quality criteria standards applicable to the international trade of the members” all they like.

But I think they have forgotten something. It’s not about them – nor should it be. Every country should be able to determine what standards should be applied to protect their own consumers.

IOC standards are revised in the light of scientific advances that help to make testing methods more accurate, or of technological and commercial developments. Their aims are to enhance and control quality, as well as to ensure transparency on the international market for olive oils, olive-pomace oils and table olives, and to promote their consumption. Every year the IOC assembles groups of expert chemists and sensory analysts from a range of countries, including the United States (USDA, AOCS), Australia and Germany, who study testing methods and revise them when necessary to determine the quality and control the purity of olive oils and olive-pomace oils. Methods are constantly being improved to adapt them to industry needs and technological developments.

It took nearly a decade for the IOC to do the right thing by consumers and decrease the free fatty acidity allowed in extra virgin olive oil from 1% to 0.8%! So what chance does a new potentially powerful method of say detecting the amount of old in a blend have of being approved in a timely fashion? Remember that some EU producers stockpile oil when prices are low, only to release them years later when prices improve. This practice while legal, dupes consumers as they are not getting a fresh product. It’s not surprising then that some consuming countries have lost patience and have proposed new tests in an attempt to protect their consumers from the dubious practice of others.

Ever since it first started to be involved in the standardisation of olive products, the IOC has cultivated a solid cooperative relationship with a number of international organisations, including the Codex Alimentarius Commission (CAC), the World Customs Organisation (WCO), the International Organisation for Standardisation (ISO) and the European Union. Its aim in doing so is to define the minimum compositional, quality and purity requirements of olive oils and to harmonise the methods of analysis in use. The Codex Alimentarius Commission is responsible for the joint FAO–WHO programme for the development of food standards with an eye to consumer health protection and fair trading.  The World Trade Organisation (WTO) takes into account the standards and recommendations of the CAC in the application of the WTO Agreements on Sanitary and Phytosanitary Measures (SPS Agreement) and Technical Barriers to Trade (TBT Agreement). The CAC standards for olive oils and table olives are currently under revision to bring them into line with the IOC trade standards, and all the producing countries that participate in IOC work are aware of the enormous efforts made to bring about such harmonisation.

While it is true that the Codex standards are under revision, the response doesn’t mention that there has been substantial resistance against bringing the Codex standards in line with some aspects of the IOC standards as they are seen by some as just cynical attempts to set up technical trade barriers.

Beware!! The term “harmonisation” sounds warm and fuzzy, but it really means that ‘it would be much easier if everyone just did it our way’.

The IOC runs a quality recognition scheme for physico–chemical and sensory testing laboratories (tasting panels) aimed at increasing mutual confidence between testing facilities and heightening the confidence of the olive business sector in labs. Recognition is awarded on a yearly basis to labs and panels that fulfil the requirements stipulated by the IOC and which satisfactorily pass the proficiency check tests it holds every year. In 2009/10 a total of 40 tasting panels obtained IOC recognition; 55 panels are currently taking part in the two check tests arranged for 2010/11. In the case of physicochemical testing laboratories, 48 laboratories obtained IOC recognition in 2009/10 and 62 are currently participating in the 2010/11 ring test. The list of recognised laboratories and panels is posted on the IOC website and updated every year. The test certificates issued by recognised panels can carry legal weight in disputes. Each country is responsible for official product control.

As the only international olive oil organisation, they are in the best position to do this. However this paragraph does not add anything to their criticism of the UC Davis report.

The IOC also sponsors a voluntary, self-regulatory scheme currently in place on a number of markets where exporters, importers and distributors of olive oil and olive-pomace oil are required to adhere to IOC standards in order to help achieve orderly market development and fair trading. In the case of North America (USA and Canada), this quality control scheme has been operating since 1991 under an agreement signed by the IOC with associations to undertake product quality control at recognised laboratories using updated methods of analysis and taking into account the designations and quality criteria specified in the IOC standards. Some 200 samples of imported oils sold in the United States are chemically tested every year by the IOC under the quality control scheme and the labelling is also checked to ensure that the product contents tallies with the labelling declarations. According to IOC findings, anomalies are detected in less than 10% of the imported oils analysed (the association concerned is notified the nature of the irregularities with a view to taking action).

The IOC signs agreements with bodies that represent the interests of the importers of  EU oil into the major consuming nations including the US. These agreements bestow the importers with the responsibility of testing and policing the quality and genuineness of the products they import. mmmm.

I was wondering that if 200 samples of olive oil are chemically tested by the IOC as claimed,  where are the results? This statement attempts to discredit one set of data that has been made widely available, yet the results of their testing remains private.

Whether the IOC likes it or not, the UC Davis report is the only one which we can draw conclusions from as it is the only report that has been released for public scrutiny. In my opinion, until the IOC and its importer organisations publish their results (and methods), then criticising the published data of others is a bit below the belt.

I also presume that the 10% of oils which fail their own testing are/were available for consumer sale. If so, is it sufficient to just advise the importer organisation so that “action can be taken”. What action? Were the oils removed from the supermarket shelves as they were falsely represented as EVOO to the consumer? Were the appropriate local food/consumer authorities advised of possible breaches to any local laws? If olive oil consumers were genuinely high on their list of priorites then they should have.

To begin with, the UC Davis study reports results for only 52 samples of 19 brands, which is not statistically significant, and in some cases it does not provide customary details such as the date of collection, best before date, pack type, labelling information, etc. Also, when anomalies are detected in testing of this type, a second check test is usually carried out for confirmation purposes by another recognised laboratory; this has not been done in the UC Davis study.

I’m a university trained statistician and I have worked professionally as a statistician, so I’m pretty qualified to comment on this. The statement that the UC Davis study “lacks  statistical significance” is ludicrous. What easier way of discrediting something than to say that it isn’t statistically significant? It’s a pretty lazy tactic really.

I’ll explain. When it comes to studies involving sampling, the concept of statistical significance is only relevant in the context of when a researcher aims to draw conclusions about the overall population from a sample taken from that population. In the UC Davis report the researchers simply commented on the oils which they tested. They didn’t draw conclusions outside the set of sample oils they tested.

In any case,statisticians know that the precision of any inference made from a sample doesn’t depend on the percentage of the population sampled, but on the actual number in the sample.

The IOC reports that their sampling gives a 10% failure rate. The UCD report gives 17% (if you only include oils that failed the tests they approve). But there is no mention of how and from where the IOC took their samples. If they sampled both supermarket and higher priced specialty oils then you would expect a lower proportion of EVOO ‘failures’ than if you just sampled from supermarket stock.

But heh, lets take a deep breath here…..  10%, 17%….. put your hands up if you think that both are excessive. I do!  If 10% of the milk I bought were off, or 10% of the bread I bought was stale, I’d have good reason to complain. Why not EVOO??

Moreover, it is important to point out that the methods used in the study (DGF and Australian standards) are not official chemical methods cited in international olive oil- specific food or trade standards; they have however been adopted by the International Organisation for Standardisation (ISO). They were in fact presented to the IOC but were rejected after scrutiny because they were not reliable. This lack of reliability is the reason for their failure to be included in either the IOC trade standard or EU regulations, or consequently in the Codex Alimentarius standard.  Before a method of analysis is approved by the IOC it is necessary to conduct numerous ring-tests at laboratories to validate the reproducibility and repeatability of the method and to make sure that it does not give false “positive” or “negative” results which can have detrimental repercussions.

My first impression of the UCD report was that it was imprudent of the researchers to include the results of non-IOC approved tests (regardless of how good the tests are) as it could give vested interests the opportunity to create doubt and confusion in the minds of consumers and the media.

While the IOC has criticised these alternative tests, they do not  provide any information on how the reliability of the tests they haven’t approved was assessed. We apparently just have to take their word for it that they weren’t up to scratch. As a professional scientist I know that It is very bad form to publically discredit something without providing sufficient supporting information. Their results should have been published in a peer reviewed scientific journal. In this way, their methods and conclusions could also be scrutinised by the scientific community.

But this is all a smokescreen anyway. Quite a few off the EU supermarket oils failed tests for EVOO that are approved by the IOC. The UV232 absorbance test for old oil for a start. By my count, 9 of the 52 failed this test (with another slap bang on the limit).This test IS recognised by the IOC and it has been widely used for decades. So even if you only use IOC recognised chemical tests as criteria for failing EVOO status then still 17% of the EU oils sampled by the UC Davis researchers still failed.

The study also points to a correlation between UV absorbance and sensory analysis in some of the samples; however, it would be necessary to ascertain the method used for testing and to corroborate the results obtained.

It should be noted that the UC Davis study follows in the wake of recent reports of mislabelling of imported product in other countries based on similar work by the same team.

At the very least the source of claims such as this should be provided. If you accuse someone of something then the reader should have the right to know the detail. What ‘recent reports’. Where, when and how?

To conclude, owing to the lack of data and the methodology applied, this study does not provide solid evidence that the oils tested do not meet US and international standards.

As I read it, there is plenty of data both from methods recognised by the IOC, (and not recognised by the IOC) to show that there is a problem with the quality of Californian supermarket oils coming from the EU. When viewed in comparison with the locally produced oils, they looked very very ordinary.

We are clearly keen for this matter to be clarified and would be willing to cooperate in carrying out stringent, in-depth testing involving the participation of a large number of laboratories. We believe that the harmonisation and fulfilment of official standards, and the application of official methods, is of key importance in achieving greater transparency and fairer trading. It is important for the authorities of importing countries to harmonise and comply with the official established standards and it is their responsibility to guarantee product quality and protect consumers.

The current IOC systems (all no doubt based on stringent, in-depth testing involving the participation of a large number of laboratories) have resulted in the current state of play regarding the quality of US supermarket oils. Agreeing to ‘harmonise and comply’ will just perpetuate the current situation. Consumers in the US, Australia, Northern Europe and the UK will remain as confused as ever… and Madrid could make decisions for all of us. Consumers of extra virgin olive oil deserve better than this.

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The system has evolved to the point where most of them follow the same or similar protocols. You can read all the detail in this article.

Extra virgin olive oil judges retire to discuss a class of oils at the Royal Canberra Extra Virgin Olive Oil Show.

As Chairman of quite a few shows I get asked a lot of questions about their conduct. So I’ll have a go at them below.

What makes a good show judge? Good judges obviously need good sensory skills. They also need to understand and be receptive to the diversity of flavours and styles that can be encountered when judging. The ability to work constructively with other judges is also an important requirement. Judges must be willing to weigh up the opinions of their colleagues against their own.

If a person enters an oil in a show does that preclude them from being a judge? No it doesn’t.  The organisers invite the most experienced judges whenever possible.

If an exhibitor is present as a judge, then doesn’t that mean that they judge their own oil? Absolutely not. This is how it works. The exhibits are divided into previously published groups called classes. While the classes are in place so that ‘like’ oils are judged together, it also helps when dividing up the oils for judging purposes.

In the event that a judge is also an exhibitor they are always allocated to a class in which their oil is not represented. No exceptions ever! Furthermore, judges are forbidden to communicate with judges from other panels until the judging has concluded and the results have been officially submitted. It’s also worth pointing out that at International shows like the Los Angeles International, judges do not judge oils entered from their country.

Imagine being a judge who has entered an oil in the show. You are sitting down judging a set of oils with a couple of other judges. Over the other side of the room somewhere, and at some point during the day, your oil will come out amongst a set of 20 or 30 others all served up in tasting glasses identified only with random codes. It will be scored by three other judges. Each judging team does their job, talking to no-one until all their results are safely in the hands of the steward.

As an aside…. I calculated the median score given to oils in last year’s Australian National Show which their producer was present as a judge vs when they were not. And the results were….

Judge not present = 14.0 Bronze: Judge present = 14.0 Bronze.

The distributions in scores also didn’t differ*. None of this was surprising as judges don’t have anything to do with their own oils. Someone else judges them.

If a judge is an exhibitor and their oil is a candidate for the best of show, then surely they can influence the outcome? Again, no they can’t. While all the judges are initially invited to assess the oils for best of show, in the event that a judge has an interest in a candidate oil, their entire score sheet is discarded prior to the evaluations being tallied. Yep trashed.

So why bother with allowing them to taste the oils for best of show in the first place if you are just going to discard their evaluation sheet? It’s the fairest way if doing it. Think about it for a moment. If the other judges were made aware that a judge had been precluded  then it  could  potentially bias the opinions of the  eligible judges as they would know that one of the candidate oils was produced by the precluded judge.

Do judges favour one style of oil over another? Any judge that announces that they have a style preference will have a very short judging career! Good judges appreciate and understand the diversity in extra virgin olive oils. Here are the results from last years Australian National Show with the oils grouped based on polyphenols level (i.e. 0-100, 101-200, 201-300 mg/kg etc), with the average scores given in black above each bar. The polyphenols level is a very good indicator of the robustness of an oil. Low polyphenols = mild gentle oil and High polyphenols = bitter/peppery oil. The results speak for themselves. While there are some differences between groups, the differences are not systematic. The most robust oils (> 500 mg/kg) had an almost identical average score to the medio style oils which came in between 200 and 300 mg/kg of polyphenols.

Distribution of polyphenol levels in oils submitted to the 2009 Australian National Extra Virgin Olive Oil Show. The average scores for each group are given in black. First group = 0-100mg/kg polyphenols.

Do Australian judges get paid for judging? No, they don’t. In addition to freely giving their time and skills they also cover their own travel and accommodation costs in most cases. Hopefully this onerous situation will change in the future.

If I wanted to see for myself how a show was conducted, could I? Absolutely. In the shows in which I preside, interested observers are welcome to quietly view proceedings and ask questions of me at any time.

* for the statistical geeks. chi squared = 2.12, p=0.549 not significant.

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You can get the report here,

http://olivecenter.ucdavis.edu/news-events/news/files/olive oil final 071410 .pdf

I’ve taken the liberty of graphically representing the data given in the report based on ‘origin’. I’ve used quotations around the word origin because when it comes to EU oils, what is on the label really doesn’t tell you very much about where the oil came from. Terms like ‘imported from Italy’ just mean that the oil was shipped from an Italian port. It doesn’t necessarily mean that it was made from Italian olives, or made in Italy. I visited the websites of the brands represented in the report, and if they made a big song and dance about being associated with Italy then I’ve put them under “Italy”. You can’t have your cake and eat it too!

If the brand was ‘generic’ or the producer was non-committal when it came to its country of origin then I’ve categorised them as ‘Mediterranean’. The US oils that were sampled were all Californian so their “country” is labeled as CA. Hell, CA’s economy is so big then it may as well be one!

Here’s what the report means to buyers of extra virgin olive oils available in Californian supermarkets..

General Quality – Acidity Level

Acidity is a general indicator of how healthy the olives were at processing and how quickly and carefully the olives were processed into oil. The lower theacidity the better.

The report showed that the extra virgin olive oils coming out of California outshone the EU oils on this very important criteria. The green arrow on the graph above shows a typical acidity for a good quality well made EVOO. With riper oils you can add up to 0.1% to this as they typically have a slightly higher FFA, but anything over 0.35 is stretching the boundaries of high quality EVOO.

All but one of the oils sampled passed the acidity test for EVOO based on the limits set down by the International Olive Council and the USDA. This wasn’t surprising as the 0.8% cut-off for EVOO is so high that just about any oil can pass. I’ve written about this in other blog entries, so I won’t go on another rant here.

How oxidised were the oils?

One of the measures of oxidation given in the report was Peroxide Value (PV). This value is particularly useful in assessing the potential for a young oil to go rancid. So the lower the value the better. However PV doesn’t do a good job in describing the oxidative state of olider oils. The following measure that is discussed (K232) strongly suggests that many of the EU oils were actually quite old at the time of testing. So I think the peroxide doesn’t tell the entire story about oil oxidation. Despite this caveat, the CA supermarket oils generally displayed a lower potential to oxidise than did the  EU oils.

The Check for Old Oil – this one always gets them when it’s done!

Finally the dead give-away! A high value for the measure known as K232 is generally regarded as a good indicator that the oil contains old oil (i.e. oil from previous seasons), so clearly the lower the value of K232 the better. In the world of supermarket oils, back blending using old oil is a pretty common practice. Older oil are cheaper to buy on the bulk market and/or producers have to sell the oil that they made but couldn’t sell in a single season. Now while some brands may not be back blending, others might blend in a small proportion (less than10%) of unsold oil from the previous season, while others might be blending in 50% of three or four year old oil. The K232 measure tells us quite a lot about what is happening in the back blending rooms.

This is where many of the EU oils are caught out. Even by their own standards, a good proportion of EU oils failed this test. All the CA oils were well under the limit suggesting they were much fresher. Incidentally, EU oils tested by independent testing agencies in other countries have also found this (but haven’t published the results).

So what’s the big deal about blending back old oil? Here’s the rub:

• By definition old oil has used up quite a bit of its shelf life outside of your kitchen.
• Generally old oil has a higher acidity and therefore it will smoke at a much lower temperature, making it less useable.
• Old oil has lower health giving polyphenols as they naturally oxidise over time.

But most importantly

• Old oil doesn’t have that fresh lively vibrant wonderful olive flavour which we pay a premium for.

As a footnote, you’ll note that I’ve always referred to the oils in the report as ‘EU oils’, rather than ‘imported oils’. The reason is, that there are many extra virgin olive oils being imported into the US from outside the EU – Australia, Chile and Argentina to name a few. Some of these nations are becoming significant exporters and in general have higher expectations as to what constitutes a quality EVOO.

RG

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Surprisingly sharks and olive oil do have something very special in common. They are the two richest dietary sources of a healthful substance called squalene. Olive oil contains between 0.4-0.7% squalene. That’s a massive 1 to 2 teaspoons in every litre of olive oil. More on the sharks later.

Squalene has been shown to be  a chemopreventive cancer agent, especially effective against breast, pancreatic, and colon cancers (at least in mice). In combination with polyphenols, it also provides protection against coronary heart disease. Squalene also accumulates in high concentrations in the skin where it quenches skin damaging oxygen radicals. For this reason it is believed to protect skin against signs of aging. Squalene and one of its related compounds squalane (which is made from squalene) are easily absorbed by the skin protecting it against harmful UV rays and oxygen. Both are also very effective skin hydrators, and have the interesting physical property that their viscosity doesn’t change much across a very wide temperature range – something that is pretty useful in cosmetic formulations as you don’t want your hand cream to be like lard when cold and have the consistency of watery custard when warm.

Unfortunately, here is where the poor sharks get screwed!

Surprisingly, ¼ of a sharks body weight is made up of its liver – 50% by weight of that is oil – and of that oil, 50 to 80% is pure squalene. If you do the math – a typical deep sea shark that weighs 100kg will yield around 6-10 kgs of pure squalene.

On top the far superior yield compared with olive oil (one shark will yield the same amount of squalene as 200 litres of olive oil), it is easier and cheaper to purify shark liver oil to the 95% purity required. As a result shark derived squalene sells for around 1/3 the price of that obtained from olive oil. Although the EU has banned the use of shark derived squalene in cosmetics and health supplements, this hasn’t stopped an estimated 350,000 sharks being slaughtered each year in the Atlantic and Pacific oceans solely to harvest their livers for squalene production.

Scary, but better here than in a jar of hand lotion

So next time you eat extra virgin olive oil, you at least will know that no defenceless shark was harmed in making you healthy.

And as a post script. Squalene is a pretty stable substance provided that it is not exposed to light or heat – another reason to store your olive oil in a cool dark place or in your refrigerator.

Here’s some useful references:

Reddy, L.H. and Couvreur, P. (2009) Squalene: A natural triterpene for use in disease management and therapy. Advanced Drug Delivery Reviews 61, 1412–1426.

Camin, F. et al. (2010) Stable isotope ratios of carbon and hydrogen to distinguish olive oil from shark squalene-squalane. Rapid Commun. Mass Spectrom. 24, 1810–1816.

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I’ve used a label off an Australian supermarket extra virgin olive oil as an example. Australian oil labels tend to provide lots of detail as to what is in the bottle, so most of the stuff you find on them, you’ll also find on labels elsewhere.

The first figure shows the nutrition panel while the second gives the label in its entirety. Below are the explanatory notes relating to the number codes given on the figures.

1.    Energy values: Better known to most of us as calories. All olive oils including extra virgin and the refined ‘pure’, ‘light’ and ‘olive oil’ have pretty well the same energy (calorific) values. The marketing term ‘light’ refers to the oils colour and taste, NOT its calorific value.

2.    Olive oil does not contain any protein, carbohydrates, sugar or salt (Sodium). This is not surprising really as none of these things are soluble in oil. These things are mentioned on labels either to inform the consumer (fair enough)or because it is a legal labeling requirement (or both). EVOO’s do contain trace amounts of cholesterol but as the levels are so low, they are rarely mentioned on labels.

3.    Total Fat: All olive oils comprise essentially 99.9% fat. 100mls of olive oil weighs about 91.5 grams. But remember that there are good fats and there are bad fats.

4.    Saturated Fat: The lower the better.  All edible fats including olive oil contain some saturated fat. Olive oil has a comparatively low amount ranging from 7.3 to 33.3 gms/100mls with an average value of around 14 gms/100mls (2.1gms/15ml serving).

5.     Monounsaturated Fat: The higher the better. Olive oil is a very rich source of these heart healthy fats. The mono fat content in EVOO ranges from 50.6 to 79.8 gms/100mls with an average value of around 67 gms/100ml (10gms/15ml serving).

6.     Polyunsaturated Fat: The lower the better. Olive oils contain low levels of these fats relative to many other edible oils. While they are pretty healthy fats, they are oxidise easily which means that their presence aids in reducing the shelf life of the oil. So on balance, the lower the polyunsaturated fats the better. Olive oils contain between 3.2 to 20.1 gms/100mls with an average of around 10 gms/100ml (1.5gms/15ml serving).

7.     Trans fats: Extra virgin olive oil naturally contain miniscule (and I stress miniscule) levels of trans fats. But to keep things in perspective, even at the levels reported on labels you would have to eat over 140 litres of EVOO (175 years worth of olive oil for the average American) to get the same amount of trans fat as eating a single serve of fast food French fries. Most oils contain far less than what even the labels say . Labels are pre-printed in their thousands, so producers often err on the conservative side i.e. overestimate things like this. But in many countries producers are allowed to claim zero trans fat if their oil falls below a 0.0buggerall% threshold.

8.   ‘Best by’ date: This is probably the most confusing and in some cases, meaningless of all labeling requirements as it depends on where the oil comes from and where it is being sold. But here goes.

European Union: The stated ‘best by’ date is 2 years after the date the oil was packed/bottled.  This means little as oils are often held in tank for years before they are blended and bottled. So the oil could be well on their way to rancidity even before it hits the supermarket shelf. So the ‘best by’ date is pretty meaningless. It really should change, but it won’t.

Other countries: From what I’ve seen, most of the larger producers outside the EU mostly follow the EU approach. When in Rome, do as the Romans do I suppose.

Australia: Producers that have signed up to the Australian industry code of conduct base their ‘best by’ date on an objective measure of the predicted longevity of the oil called the rancimat test.

An alternative approach to stating ‘best by’ dates is to simply state the year, or year and month that the oil was extracted on the label. This approach is mostly taken by smaller producers. Even if this detailed information is provided, it is still impossible to predict how well the oil inside the bottle will last as the natural variability in the chemistry of EVOO’s determines their shelf life. However, most oils will last the 12 months required before the following seasons oils are released provided they are stored in a cool dark place.

9.     Product of Whatever Country:  Something so simple should be simple, but it isn’t

European Union: From July 2009 (and not about time I must add!!), olive oil originating from just one country will have to be labelled with the country of origin. Blends will be labelled either as “blend of European Community olive oils”, “blend of non-EU olive oils” or “blend of EU and non-EU olive oils”. Up until that date, the country of origin could have simply been where the oil was blended or packed, which allowed zillions of litres of Spanish or North African oil to be labelled as Product of Italy. I must say that even one year after the new law came into effect I haven’t seen a single EU oil on my antipodean local supermarket shelf labelled in accordance with this new law. Old stock perhaps?

Australia (and New Zealand): Oil labeled “Product (or produce) of Australia” must have been made from Australian olives and it must have been produced in an Australian mill. The same applies to oils labeled as Product of New Zealand.

The US: Who knows? I’ve seen Californian maps and references to California splashed all over the front label, but printed in 2pt font on the back is the enlightening “Product of the Mediterranean”. Stuff like this must drive the hard working legitimate local producers insane!! The new USDA olive oil standards do not as popularly assumed address labeling issues – even basic ones like knowing where the oil you are buying actually comes from. So read those back labels carefully. I follow the general rule, that if the statement of origin is even slightly ambiguous I move on to something else.

11.     Contact name and address of the producer: Maybe this appears to be a small thing, but it actually means a lot. It allows a real human being to take responsibility for what is in the bottle you just bought. Too often dodgey EVOO’s have not been able to be traced back to the actual person who is profiting from the fraud. Incidentally under Australian law it is mandatory for all food producers to put the name of a legal entity and a physical address on the label.

Other things you might encounter on an EVOO label sooner or later:

Free fatty acidity or acidity or FFA. The lower the better. Look for EVOO’s with FFA’s less than 0.25%. I’ve raved on incessantly about this in some of my other posts.

Polyphenol level: It is rare to see this stated on a label as they deciline over time. But some producers do give the level at bottling. Polyphenols are antioxidants. They are a healthy part of our diet and help the oil survive its year long journey in your kitchen. However it is worth noting that generally speaking, the higher the polyphenol level the more bitter and peppery the oil.  A polyphenols value of 500 mg/kg +indicates a pretty intense oil and less than 150 a pretty gentle sweet oil. You can read more about what effect polyphenols have on the taste of EVOO in Gawel and Rogers (2008), the authors version can be found here; http://www.aromadictionary.com/articles/oliveoilpolyphenolsandstyle.pdf

Lots of harmless bullshit: But heh, the world wouldn’t be as much fun without it, and it doesn’t hurt anyone most of the time.

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I’m pretty certain that most of the folks who buy one of these types of oil are unaware that the oil has been refined. Not surprising really, as to date, there has been no legal labeling requirement to state how the oil was produced. My feeling is that producers of ‘pure’ and ‘light ‘ olive oils would not want their consumer to know is that most of its flavour, aroma and health giving micronutrients have been stripped away by refining.

This brings me to the much lauded recent olive oil grades determined by the USDA. I first came across the final version while judging at the 2010 Los Angeles International Olive Oil Show. I had a bit of time to look at them while the other judges slaved away at the flavoured oil classes. Even a cursory glance sent alarm bells ringing. Oh no. They’ve fallen in line with the international standards. And as the unpleasant pong of roasted garlic wafted across room, I got the strong ‘what the hell were they thinking’ taste in my mouth.

Let’s start with the U.S. Extra Virgin Grade which incidentally is no different from the International Olive Council definition for EVOO:

U.S. Extra Virgin Olive Oil is virgin olive oil which has excellent flavor and odor (median of defects  equal to zero and median of fruitiness greater than zero) and a free fatty acid content, expressed as oleic acid, of not more than 0.8 grams per 100 grams, and meets additional requirements as outlined.

There’s a major contraction here. “Excellent flavour and aroma”, yet the “median of fruitiness greater than 0” only means that even if ½ the official tasting panel perceived even a hint of aroma and flavour then it will meet the standard. Hardly excellent.

To the chemistry.

Less than 0.8% free fatty acidity. WOW!!

Here is the distribution of FFA’s of Australian olive oils submitted to the Australian National Show half a decade ago.

In over 330 oils, only one was over 0,8% acidity,and the average was around 0.19%. As an Australian I’m not trying to brag here.  I’m just giving the results of a bunch of honest olive growers following good industry practice – good quality olives being quickly processed into oil using clean mills and being stored correctly.

So which oils do get close to the upper FFA limit set down by the USDA? Short answer: imported supermarket oils. The 0.8% level doesn’t guarantee quality in any way or form. It simply allows rubbishy oils to hit the supermarket shelves in the US, Australia and Canada and still be legimately labelled as EVOO. The US consumers are being misled again, simply because the international standards are so lax.

Now to the largely irrelevent grades. The ones you will rarely if ever see, but a lot of thought has gone into defining them nevertheless:

U.S. Virgin Olive Oil is virgin olive oil which has reasonably good flavor and odor (median of defects between zero and 2.5 and median of fruitiness greater than zero) and a free fatty acid content, expressed as oleic acid, of not more than 2.0 grams per 100 grams, and meets additional requirements as appropriate.  Olive oil that falls into this classification shall not be graded above “U.S. Virgin Olive Oil.”

The ambiguously ‘reasonably good flavor’ aside, the 2% acidity = complete and absolute rubbish. You can leave olives on the ground for 5 months and after making oil out of them, pile them up for a couple of weeks so they ferment to a pile of compost before processing and the acidity will still probably be less under 2%. In short, you have to be a complete butcher to produce oils with this chemistry.

U.S. Virgin Olive Oil Not Fit For Human Consumption Without Further Processing (also known as U.S. Lampante Virgin Olive Oil), is virgin olive oil which has poor flavor and odor (median of defects between 2.5 and 6.0 or when the median of defects is less than or equal to 2.5 and the median of fruit is zero), a free fatty acid content, expressed as oleic acid, of more than 2.0 grams per 100 grams, and meets other additional requirements.  Olive oil that falls into this classification shall not be graded above “U.S. Virgin Olive Oil Not Fit for Human Consumption Without Further Processing.”  It is intended for refining or for purposes other than food use.

The tiny amount of this stuff that may occasionally show up is either turned into soap or sent off to a seed oil refinery, eventually ending up in a canola oil near you. But lampante oil is not really the domain of new world producers like the US as they have the expertise and production capacity to avoid making this crap in the first place.

Now to the most important grades volume wise:

U.S. Olive Oil is the oil consisting of a blend of refined olive oil and virgin olive oils fit for consumption without further processing.  It has a free fatty acid content, expressed as oleic acid, of not more than 1.0 gram per 100 grams, has acceptable odor and flavor characteristic of “virgin olive oil,” and meets other additional requirements.  Olive oil that falls into this classification shall not be graded above “U.S. Olive Oil.”  The maximum level permitted of total alpha-tocopherol in the final product is 200 mg/kg.

In my humble opinion, the following two definitions are a bad result for US EVOO producers and consumers.

“A blend of refined and virgin olive oils” is pretty ambiguous. Even a blend of 1% virgin olive oil with 99% refined would qualify.

What does ‘’acceptable” flavour mean? Presumably if it has ‘some’ flavour and it doesn’t make you puke then it would qualify. So under these criteria, a refined olive oil with the slightest flavour can be called olive oil.

What a great result for importers of refined olive oil into the US! The status quo is retained. You can still put a largely refined olive oil into the US market and not admit that it is refined. It’s ‘olive oil’, just like it was before.

U.S. Refined Olive Oil is the olive oil obtained from virgin olive oils by refining methods that do not lead to alterations in the initial glyceridic structure (basic glycerin-fatty acid structure).  It has a free fatty acid content, expressed as oleic acid, of not more than 0.3 grams per 100 grams, is flavorless and odorless and meets other additional requirements.  Olive oil that falls into this classification shall not be graded above “U.S. Refined Olive Oil” (this is a limiting rule).   The addition of alpha-tocopherol is permitted to restore natural tocopherol lost in the refining process.  The maximum level is 200 mg/kg of total alpha-tocopherol in the final product.

In the language of Sienfeld. Yadda, Yadda, Yadda. This is the standard definition of refined olive oil, but lets face it… what right minded producer of refined oil would want “REFINED OLIVE OIL” plastered all over their label when they could easily justify the use of the term “OLIVE OIL”?

My guess is that not a single EU produced refined olive oil sold in the US will have the word refined on the label. Time will tell. Please post a comment on this blog if you find an example of it. I’d love to see it.

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What Determines the Colour of an EVOO?

The colour of an olive oil depends primarily on the ripeness of the olive when picked and also on the olive cultivar/variety. Some varieties such as Verdale, Koroneiki and Bouquettier are commonly (but not always) pretty green regardless of the ripeness of the olive when harvested.  However, most varieties can produce a variety of oil colours depending on olive ripeness. Not surprisingly, greener early harvest olives generally produce greener oils, while riper olives will generally produce more golden coloured oils.

The Pigments in EVOO

The colour of EVOO is primarily due to two natural types of pigments – the green coloured chlorophylls and the yellow coloured carotenoids. In fact, two types of chlorophyll are found in olives. ‘Imaginatively’ called ‘a’ and ‘b’ by the chemists, the former is bluish green while the latter yellowish green in colour. There are other pigments too, most notably the pheophtyins which are coloured brown to olive green. The immense range of colours that you can find in EVOO depends on the relative proportions of these pigments contained within the oil. Imagine a paint palette where you have a few shades of green, a few yellows and the odd duller shade. Start mixing the paints in the various proportions and you’ll be able to create millions of subtly different colours. But you won’t be able to create a blue or red no matter how hard you try! So just in case if you ever wondered why EVOO’s were never red or blue – you have your answer.

So is green good? Depends.

Green oils contain a lot of chlorophyll.  Chemically speaking, chlorophyll is a bit of a strange creature.  When kept in the dark it acts like an antioxidant protecting the oil from oxidation. On the other hand, it becomes a strong pro-oxidant when exposed to light, setting off a devastating chain reaction that destroys EVOO aroma and flavour, and finally results in tired rancid oil. So it’s a bit like an anti-vampire in a way. The form of oxidation triggered by chlorophyll is known as photo-oxidation and it is probably the fastest and most destructive type of oxidation that can befall an EVOO.

The carotenoids are more than just yellow coloured pigments. Actually you’ve seen them before – lots of times. The yellow colour in carrots, egg yolks and fruits like cantaloupe melons, mangoes and apricots (to name only a few) are all due to their carotene content. Our bodies convert carotene into Vitamiin A and it can also be absorbed into our fat (er, that’s why human fat is a bit yellowish by the way). Carotene is also a good antioxidant – soaking up the supercharged forms of oxygen called singlet oxygen that attack EVOO (and us).

Sunburnt EVOO

You may have noticed that if you overheat olive oil its colour dullens and it eventually becomes an unattractive brownish colour. These changes are due to the formation of another set of brownish grey coloured pigmnets called pyropheophytins. Recently German scientists have used the pyropheophytin content of suspect EVOO’s to detect ‘heating events’ – a nice way of saying detected adulteration with refined and pomace which by definition are heated at one point or other of the their manufacture, or when significant quantities of old oil that has been warmed at some point during storage have been added.

Making EVOO Green

While green coloured EVOO’s are usually that way because they have been made from early harvest aka green coloured olives, there are more or less unscrupulous ways of getting that desirable green colour into an EVOO.

Firstly the legal ways.

A small amount of chlorophyll rich leaf material will always be inadvertently mixed in with the olives when olives are harvested. Most of the time, the majority of the leaves are blown off the olives with a leaf blower prior to the olives being crushed. However, it is not uncommon (particularly in some parts of Italy) for a high proportion of olive leaves (up to 20kg/tonne) to be processed together with the olives. The result – a very green oil that is often also very bitter. Why bitter? Just pick an olive leaf off a tree and taste it. You’ll see why.

Dipping olives into hot water (60C) for a minute or so prior to processing also causes chlorophyll to be extracted, with increased greenness the result. However, hot dipping also reduces the healthful polyphenols in the oil. This might not always be a negative result if a slight reduction in the bitterness of the oil is what the producer is looking for.

Lastly the totally illegal way. The addition of an artificial chlorophyll derivative called E141i has been used by the unscrupulous to ‘green up’ seed oils like canola and sunflower to make them look like EVOO.  E141i is almost identical to natural chlorophyll, but it differs in a fundamental way. Chlorophyll has a single atom of an element called Magnesium at its core.  This element makes chlorophyll  pretty unstable (hence green oils tend to lose their greenness with age). E141i on the other hand has a Copper atom at its core. This makes E141i more chemically stable than its natural counterpart. So much so that any oil that has been illegally coloured with E141i will stay green for years, and no amount of heating will budge it! However, thankfully detecting Copper in EVOO (the tell tale sign of E141i) is relatively straightforward and as such can be used to nail the fraudsters.

Back to real EVOO. So why do olive oil tasters use blue tasting glasses to cover up the beautiful colours of EVOO which consumers so admire? Don’t ask me. The ‘official’ justifications don’t make any sense at all – well at least not to me. But that’s for another blog.

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The good old fashioned oxygen that you find in air and that is dissolved in EVOO isn’t by itself very destructive. However, if it is hit by light which is packed with enough of an energetic punch, then it can push the generally harmless oxygen to a new and dangerous psychotic state. This energised oxygen, called triplet oxygen starts a destructive chain reaction, oxidising fat molecules left right and centre. The ultimate result of this reaction is a rancid oil that lacks fresh olive flavours, and worst still, fills your food with aweful flavours of old fish and chip shop or suburban corner grill.

Photo-oxidation can be simply avoided by ensuring that the oil is not exposed to light. To this end, good EVOO producers pack their oils in dark glass bottles or cans, and they implore their customers to store their oils in a dark place. While tin cans are completely impervious to light, dark glass is not. Different coloured glass of different levels of darkness are used to store EVOO. Look carefully: some are a classic green, others more of a “sea green” colour. Others are more olive in colour and yet others are amber.

Many producers think that the darker the glass the better, and that is all there is to it. Well they would be wrong.

Oxygen can only be energized if it is hit by light with a short enough wavelength – particularly light in the ultraviolet part of the spectrum. So, coloured glass that absorbs UV light will best protect the oil from oxidation. Those that let UV light through will not afford any protection to the oil, regardless of how dark or light the bottle appears to the eye.

So how do we measure the effectiveness of different glasses and material in blocking UV light? Scientists use a machine called a spectrophotometer or spectro for this gig. It sends a beam of continuously changing wavelength light through the glass and measures the amount of that light that doesn’t make it through (called the absorbance).

Each type of coloured bottle has a distinct ‘absorbance’ fingerprint. Some colours absorb light better at different wavelengths than others. Indeed, that is the exact reason why they are perceived by our eye as having different colours in the first place. The figure below shows the absorbance fingerprints of a variety of commonly used wine bottle colours (from Skouroumounis et al. 2006).

You’ll notice that there are a number of different types of green represented – classic green, antique green,  emerald green and the like. They’re all green but they clearly absorb different wavelength light to different extents. The glass labeled ‘flint’ is better known to us as clear glass. It doesn’t absorb light at any wavelength. All the light just passes right through. Hence it looks clear and colourless.

But not all wavelengths are born equal when it comes to destroying EVOO. The ‘light’ with wavelength of 400 nanometers (nm) or less is known as ultraviolet radiation. Our eyes can’t see it but the spectro can. Below 315nm it is known as UV-B, and above 315 UV-A. (the dark lines on both figures represent these parts of the spectrum) .Both types have enough energy to excite oxygen and cause eventually cause rancidity. The absorbance at the other longer (visible) wavelengths gives the bottles their distinct colour.

So think about what the consequences would be of storing olive oil in cobalt blue bottles. They’ll look pretty funky (I guess), but cobalt blue glass doesn’t absorb very well in the UV part of the spectrum. So that means that any UV that hits the bottle will pass straight through the glass and attack the oil. And the glass will provide little protection regardless of how dark the blue. Darker blue glass will absorb more in the parts of the spectrum that don’t influence oxidation but will still let pretty well all the damaging UV light through.

So what about olive oil bottles? This morning I intentionally smashed two common types of square bottles that are used to store EVOO. I bought the oils at a local specialty store. One bottle was common dark green and the other an equally common dark olive green/brown colour. I also cut a bit out of a clear PET bottle used to store olive oil that I purchased at a supermarket and measured the absorbance from the visible through to the UV part of the spectrum. Here’s what the glass looked like and below that are the results.

(Yellow=PET, Aqua=green glass, Brown=olive green/brown)

Clearly the olive/brown version is better than green when it comes to blocking UV. But neither is perfect. So store those oils in a dark place regardless of the fact that they are in dark glass. The PET was a bit of surprise. It absorbed very well in the UV-B, but was pretty well a clear window for UV-A. Some PET contains inbuilt UV blockers. This was clearly one of them. Not that you could tell by looking at it!



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