Slick Extra Virgin

This is the second of a short series aimed at explaining the whys, the how and the what (and the what-nots) of analyses that are commonly applied to extra virgin olive oil.

Analysis Name: Total polyphenols

What does it measure?: The combined pool of compounds in olive oil that are in the phenolic chemical group (containing six carbon atoms attached to each other in a ring like formation with one or more oxygen+hydrogen groups attached to the ring). An example of a common olive oil polyphenol is shown in Figure 1.  In laymans terms, ‘total polyphenols’ are a measure of the combined total of the most important group of antioxidants in extra virgin olive oil.

Figure 1: Hydroxytyrosol – An example of a phenolic compound found in extra virgin olive oil.

Does the polyphenol level affect extra virgin olive oil status?: No. Many perfectly grown and made olive oils have low or medium polyphenol levels.

How it works: The polyphenols are extracted from the oil into a water/alcohol mix. A reagent is added which reacts with the polyphenols turning it blue/green. The depth of the blue/green colour is measured, and is directly proportional to the amount of polyphenols in the sample.

Is it a measure of quality?: Depends. Quality is a term that encompasses the general concept of ‘fitness for use’. So if you are ‘I want to live forever’ type of person then yes higher polyphenols which are of the antioxidant family could be perceived to be of higher quality in your eyes.  But conversely if you want to use extra virgin olive oil to make great tasting grilled potato slices on the BBQ for your hungry kids that don’t taste bitter, then a high polyphenol oil (by a consistently applied ‘fitness for use’ criterion), is of lower quality.

Analysis debuted: 1958. Initially developed for wine polyphenol analysis,  It was officially adopted in a modified (but in an incompetely described form) for olive oil by the International Olive Council in 2005.

Unit of Measurement: milligrams/kilogram of oil (1mg=1/1,000 of a gram).

Range in Extra Virgin Olive Oil: 80-2,000 mg/kg (measured as caffeic acid equivalents). Common range 200-400 mg/kg.

Accuracy of method: The first step of the analysis involves extracting the polyphenols out of the oil using a solvent. This step, depending on how carefully it is done, can cause variable end results in the order of +/- 10%. For this reason, it is necessary to repeat the test and take an average.

Use by olive oil producers: Unknown. Probably more so by New World olive producers.

Degree of difficulty: By automated lab standards the method is time and labour intensive, and therefore relatively expensive.

Practical effects of high readings of polyphenols

–  Typically more bitter and/or pungent (peppery).

–  Greater health benefits.

–  Assists in prolonging shelf life.

–  Potential for slightly higher smoke point.

Polyphenol level in extra virgin olive oil is affected by:

Cultivar – some varieties of olives tend to produce naturally higher polyphenol levels than others. For example, the average polyphenol levels in oils made from the cultivar ‘Coratina’ are significantly higher than those made from the cultivar ‘Arbequina’.

Olive maturity at harvest – The greener the olives used to make the oil, the higher the polyphenol levels.

Climate – Cool climates tend to favour higher polyphenol levels.

Tree water status – Excessive water availability reduces polyphenol levels.

Enzymes – The use of enzymes as a processing aid increases polyphenol levels

Water use during processing – Adding water to olive paste before extraction (e.g. 3 phase processing) reduces polyphenol levels.

Post harvest – Delays between harvest and processing reduce polyphenol levels.

Disease/Fruit quality – Incidence of fungal disease, olive fly attack and frost damage decreases polyphenol levels.

Age of the oil – Polyphenols levels decline as the oil ages.

Other comments:

The method only measures the size of the entire pool of the hundreds of polyphenol types that exist in extra virgin olive oil. Information about the amount of a specific polyphenol can only be achieved using highly sophisticated methods called high performance liquid chromatography or HPLC.

The relatively high cost of conducting the official method has led to an alternative rapid method to be developed. Called NIR or Near Infrared Spectroscopy, it is a method that can almost instantly estimate the polyphenol reading from a drop of oil, and it costs around 1/5 that of the official method. However it has its limitations, and its accuracy is laboratory dependent. Something for another blog post.

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This is the first of a short series explaining the common chemical analyses applied to extra virgin olive oil. I’ll start off with the most universal analysis of them all – “Free fatty Acidity” – or known to most of us as ‘Acidity’.

Name: Free Fatty Acidity or FFA

Better known as: ‘Free Acidity’ or simply ‘Acidity’

What does it measure?: The level of breakdown of the fats in extra virgin olive oil.

Analysis debuted: Circa 1890

Use by olive oil producers: Universal

Degree of difficulty: Easy. Can be done using basic lab equipment and little technical expertise. You can see me conducting an FFA analysis here

Official Iimit for extra virgin status: < 0.8%

Unofficial limit strived for by good EVOO producers: <0.2%

Direct effects of high readings of FFA:

• Lower smoke point (the temperature at which the oil starts to smoke when heated)
• Greasy mouth-feel/aftertaste
• Shorter shelf life

Typical indirect effects of high FFA:

• Reduced positive flavours and/or greater defective fermented like flavours.

Common causes of high FFA:

• Delays between harvesting and processing.
• Diseased/damaged olives particularly due to olive fly infestation and anthracnose (fungus).
• Bruising of olives during harvesting followed by processing delays.
• Olives harvested from the ground.
• Frozen/frosted olives.

What is Free Fatty Acidity?

Every fat molecules including that in olive oil is comprises 3 smaller parts called fatty acids that are connected together. Figure 1 is the typical fat molecule found in olive oil – three monounsaturated fatty acids called oleic acid linked together.

Figure 1: Extra Virgin Olive Oil Nirvana. A perfectly formed and intact fat typical of olive oil.

However, having 100% perfectly intact fats like those shown in Figure 1 molecules is “fat Nirvana”. Sort of like that place that the “Watchtower” magazines portray – where humans live in perfect harmony with dopey lions and really small monkeys (both of which are likely to kill you at any given moment, but somehow reassuringly, for different reasons). But, getting back to the point, extra virgin olive oil is a natural product, and therefore is less than perfect. Individual fatty acids can be chopped off the fat molecule if the olives are riddled with fungussy olive pestilence, are being gouged upon by olive fly maggots, bruised and battered during harvesting, or (more typically, and less dramatically) if the olives are left to even slightly decay in the interim between olive harvest and processing.

Figure 2: Formation of free fatty acids. The Pacman represents a lipase enzyme, but if you like, you can think of it as a Pacman.

Nature has devised a few ways of busting up intact fat molecules to form free (aka single) fatty acids. Her chopping utensil of choice are enzymes called lipases. They are found in the olive fruit, but in good fresh undamaged olives the lipases are harmlessly locked up in the olive cell away from the fat molecules that they desperately want to destroy. But when the olive cells are damaged in any way, the enzymes are able to escape from their compartments, and in frenzied attacks dismember the intact fat molecules freeing up fatty acid molecules (Figure 2). The more diseased the olive, or the longer the time gap between olive harvesting and processing, the more enzymatic activity and the higher the free fatty acidity.

Common misinterpretations/misrepresentations of FFA in olive oils.

“FFA is a good indicator of olive oil quality” –  Sort of right.

Free fatty acidity is widely acknowledged as a good index of general olive oil quality. While this is generally true, I have tasted many examples of higher FFA extra virgin olive oils that taste just fine, and conversely I have tasted many low FFA oils that are woefully defective. Take for example what is possibly the worst tasting defect in olive oil called muddy sediment. It has a foul (for olive oil) taste of parmesan cheese, baby vomit, salami, band-aids, horse stable and fetid milk (and combinations of these). An olive oil can pick up these characters from short term exposure to the particulate olive sediment that remains after oil extraction and which later falls to the bottom of a tank. The aroma compounds that contribute to this defect are very potent. Therefore whilst leaving the oil on the sediment may result in only a small break down of the fat (resulting in a small increase in FFA), this small increase in FFA can be accompanied by a large reduction in flavour quality.

“Refined olive oils have high FFA” – Very wrong!

Paradoxically nothing is further from the truth. Refined olive oils (i.e.  those labelled as pure, light and ‘olive oil’ ) have essentially zero FFA. Yep, zero. The confusion probably arises from the fact that badly made olive oils, i.e. oils with very high FFA’s are those destined for refining in the first place. The major purpose of the refining process is to remove the free fatty acids. This is effectively acheived by adding caustic soda which converts the free fatty acids to soap which can then be physically removed from the oil.

“The FFA of an EVOO increases substantially during storage” – Wrong again.

The production of free fatty acids from intact fat molecules is process that mostly involves the action of enzymes found within the olive which act in the presence of water. Once an olive oil has been properly extracted from the olive and most of the water has been removed (<0.1% remaining), further degradation in bottle leading to higher FFA is very unlikely. Typically, a properly processed EVOO with a low FFA of 0.2% at the time of processing, may get up to between 0.22% and 0.25% after 12 months of storage.  Ok, that’s a 10-20% increase, but when you consider that your typical inexpensive supermarket purchased EVOO from the EU typically starts at 0.60-0.80% the 0.02-0.05 increase in FFA due to storage is inconsequential.

“You can’t taste acidity in olive oil” – Got that one right.

The free fatty acids are so weak that they don’t have the ability to bother our otherwise very busy acid taste receptors.

“If the FFA of an olive oil is X% measured as oleic acid , this mean that the olive oil contains X% oleic acid”. – NO it does not mean that.

The “measured as oleic acid” is simply a unit of measurement. For a few anally retentive lipid chemists, it may seem important, but in reality, whichever fatty acid equivalent (pick one, any one), it really has bugger all effect on the final result. So everyone can ignore the “measured as” bit without any loss of meaning. That’s of course unless you are an anally retentive lipid chemist. But to satisfy the inevitable “% bi (oleic acid) curious” readers, I might have a go at explaining it in a forthcoming post.

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At last! A paper reporting the effects of real olive mill based filtration on extra virgin olive oil composition. To date all research on the effects of filtration have been conducted using small lab based simulations.

Bakhouche et al. (2014) Monitoring the moisture reduction and status of bioactive compounds in extra-virgin olive oil over the industrial filtration process. Food Control. 40, 292-299. http://dx.doi.org/10.1016/j.foodcont.2013.12.012

The why?

Filtration is performed to produce perfectly clear oil that most consumers desire. But what are the consequences of filtering?

The how:

45 tonnes of two extra virgin olive oils were filtered through ‘cakes’ of Vitacel_L90 (30 kg, composed of 100% cellulose) and Filtracel_EFC-950 (60 kg, composed of 70% cellulose, 30% lignin) and the change in moisture and polyphenol content was monitored throughout the during the filtration process.

The outcomes:

– Filtering reduced the moisture content by between 20 and 36% depending on how ‘clogged’ the filter was at the time of sampling, and the initial moisture content of the oil.

– (illogically) filtration increased total polyphenols. However most polyphenol types were reduced following filtration particularly the small simple phenolics hydroxytyrosol and tyrosol.

Commentary:

The reduction in moisture content can be attributed to the water binding ability of polysaccharides (of which cellulose is one).

The observation that total polyphenols increased following filtration is ‘bizarre’. Filtration substrates do not contain polyphenols*, so logically, the filter material can either let polyphenols pass through resulting in no change, or adsorb them, which would result in a reduction in polyphenol content. The authors attribute the unexpected increase in polyphenols following filtration to limitations in how the dominant polyphenol class (the secoiridoids) are extracted from the oil prior to being quantified. That is, the illogical increase in polyphenols after filtration is an artifact of the laboratory measurement process.

The other polyphenol classes generally decreased due to filtration. As the filter material became more used, there was a trend for the difference between filtered and non-filtered samples to be reduced. This suggests that the filtration material was absorbing phenolics (because as the filter material has a finite number of binding sites, so as it becomes more used it is less effective in retaining phenolics – so the pass through).

So what can we take out of the study.

1)      Filtration reduces the moisture content of extra virgin olive oil. Practically this is a positive effect as lower moisture means decreased chemical breakdown (hydrolysis) of the fat molecules that make up extra virgin olive oil that lead to free fatty acids (acidity). Lower oil acidity is associated with greater oxidative stability aka shelf life, and higher smoke points.

2)      The effect of filtration on polyphenol content of extra virgin olive oil is still a ‘bit murky’, however there is some evidence that filtration does reduce polyphenols or at least some types of polyphenols.

* The increase in polyphenols was caused mainly by increases in secoiridoid compounds which are found in olive fruit. This rules out the possibility that the filter material inadvertently contained some form of phenolic contaminant which was extracted into the oil during filtration.

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Figure 1: Consolidated results of Choice supermarket EVOO testing 2000, 2003, 2007 and 2010

The vast majority of extra virgin olive oil (EVOO) sold and eaten throughout the world is purchased in a supermarket, so independent reviews of the quality of extra virgin olive oils in this market are invaluable.

The Australian Consumer Association (ACA) does such a thing. The ACA is a respected not for profit and fiercely independent organisation that Australian consumers ‘go to’ when they want reliable and trustworthy advice on what to buy, and what to look for when buying it. Thankfully for Australian extra virgin olive oil consumers, the importance of this product hasn’t slipped by the ACA as they have reviewed EVOO’s sold in Australian supermarkets every four years or so since 2000.

The ACA samples extra virgin olive oils from Australian supermarket shelves and asks a panel of experienced extra virgin olive oil tasters to assess their quality. The selected oils represent most of the major nationally available brands, but also include some that are only available in smaller independent supermarkets. The tastings are conducted totally blind i.e. no information about the oil is revealed to the tasters. The tasters are drawn from a variety of industry sectors (growers, processors, chefs and (mostly) tasters trained using International Olive Council tasting protocols), None of the tasters have any association with the products being evaluated. The results are published in the ACA magazine “Choice”.

I have taken the liberty of trawling through past issues reporting olive oil reports and have summarised the results in the table below. I have not published the brand names of the oils, as this is the domain of the ACA. Interested readers can go here to find the identity of the 2010 oils, and details as to why they were scored as they were. However, in the table that I have provided which summarises the results of 4 ACA tastings since 2000 (Table 1), I have given each brand a unique letter (if it was available nationally across at least 3 of the 4 tastings conducted) These generally represent the major selling brands in Australia.

In the early tastings (2000 and 2003) the oils were only classified into broad categories (very good, above average, ok, poor etc). In later tastings (2007 and 2010) the oils were scored for quality using the 20 point Australian Show judging system, but were not categorised in the same way as had been done previously. In order to create a consistent ‘quality time line’ spanning the 14 years, I logically equated the generally accepted interpretations of the show judging scores to the categories used in earlier tastings

Here is how I did it.

Score/20        Accepted interpretation                                                 Assigned category

less than 10    The oil has a recognized taste defect                          poor/unacceptable

10.0 – 12.5      No defects but is below average (no medal)              marginal/ok

13.0 – 14.5      Above average (bronze medal in AUS competition)   above average

15.0 – 16.5      Very good (silver medal in AUS competition)               very good

The consolidated results of the Choice tastings from 2000-2010 are shown at the top of the blog. Notes: SMG = supermarket generic i.e home or white label brand. Olive oils within the same category (2003 and 2007), or allocated the same score (2007 and 2010) are listed in the table in alphabetical order.

The quality time-line by country of origin goes like this…

The ratings assigned to each of the quality categories which were then used to generate the average quality ratings by country of origin were:

Very Good = 4, Good/Above Average = 3, OK/Average = 2, Borderline/Below Average = 1, Unacceptable/Poor = 0

When averaged, we can create a time line of quality by country of origin …Dah Daaaah…

In case you were wondering, In 2007 and 2010 the oils were given a quality score, so an average quality by country of origin can be calculated directly. They are:

*Greece average 11.9 (5 oils)

So What Do the Results of the Tastings Say?

–  Extra virgin olive oils made in Australia were rated more highly than those labelled as Spanish and (particularly) those labelled as Italian. This was true of all four tastings spanning over a decade.

–  The average quality of Australian olive oils sampled showed an upward trend.

–  The average Australian made supermarket EVOO sampled by Choice and sold in 2010 were of a ‘bronze medal’ standard which In lay-mans terms should be interpreted as “a sound defect free olive oil that has distinct olive characters”.

–  EVOO’s sampled by Choice that were of Spanish origin* were on average ‘marginal’. Scores of around 10 suggest that the oil were marginal when it came to defects but would probably not offend the average supermarket buyer.

–  EVOO’s sampled by Choice that were of Italian origin* were on average of poor quality and on average fell in the scoring range reserved for oils with clear and distinct defects.

Some general points regarding the tastings

In the case where an olive oil was considered to have been of poor/unacceptable quality, a second bottle purchased from another supermarket (sometimes from another State) was re-tasted. The highest of the two ratings were published (and are given here).

A small number of Greek oils were sampled – 2 or 3 in each year. Given the small sample size they have not been included in the tables or figures, but I have provided their assessments in footnotes for completeness.

I was one of the tasters in 2000, 2003 and 2007.

* Extra virgin olive oils imported from the EU into Australia and the US are often labelled as product of the country where they are blended and bottled rather than made. In particular, hundreds of thousands of tonnes of Spanish and North African olive oil is blended and bottled in Italy each year and are sold to the United States and Australia (and probably all other countries outside the EU) as ‘Product of Italy’. Many of the so called Product of Italy oils sold in Australian supermarkets have the distinctive taste and smell of the olive variety Picual…. Picual is not grown in Italy. Transporting olive oil from Spain and Greece and North Africa to Italy and packaging it there allows the ‘Product of Italy’ claim to be made outside the EU. This is a license to print money as on average oils with ‘Product of Italy’ claims attract higher prices than when labelled as product of Spain or Tunisia. So make no mistake. Very few supermarket oils sold outside the EU that are labelled as product of Italy or suggest that they are a product of Italy actually are what they claim. In recent years, some of the brands are more accurately stating on their label that they contain blends of Italian olive oils and those from other countries, blended in Italy. The % breakdown by country is not given, but is very likely that the majority of oils in the blend are not grown in Italy given that Italians consume more olive oil than Italy produces. I recommend that you ring the information line of the producer to find out more about the actual origin of the oils they sell.

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a)      Mechanical processing includes methods that do not use solvents or excessive heat to extract the oil.  These methods include centrifugation and (now, rarely) pressing.

b)      Pomace is the mix of skins and crushed olive seeds left over after most of the olive oil and water have been mechanically extracted from the olive paste.

c)      Usually hexane is the solvent used.

d)     Refining involves a number of steps which involve the addition of strong acids and bases, and the application of processes such as chilling, washing, centrifugation, filtration and deodorisation.

e)      Pure olive oil is no ‘purer’ than any other olive oil. ‘Light’ olive oil does not have fewer calories than any other oil. The term ‘light’ refers to its lighter colour, aroma and flavour – a result of the oil having been refined.

More information on the difference between olive oil types can be found here

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For once I have a theme!

But first, I must rid myself of a burden. There are no polyphenols in extra virgin olive oil. I’ve been resisting saying so for years, but now I must now confess. There is nothing poly(merised) about them. Yes, a couple of them could be a bit binary (depending on how you define it), but poly, errr no. Yes, many have a few optional extras like having attached sugars and esters hanging off them, which most certainly gives them interesting biological and health giving properties, but they are generally comprised of single simple phenolic monomers. They remind me of those troglodytes creatures that ruled the world during the Cambrian Period. There were thousands of different types – all very intricate and ecologically specialised, but in the general scheme of things, they were relatively biologically simple critters. Now I’m rid of the weight of this chemo-trivia, here are a few interesting, and practical research results about the phenolics in EVOO.

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The researchers compared the ability of total phenolics and absorbance at 255nm (K255) to predict the perceived bitterness of EVOO’s. The 35 oils from 4 Italian varieties ranged in bitterness from 1 to 7 on the International Olive Council rating scale which corresponded total phenolics of around 200 to 650 mg/L, and to 0.05 to 0.65 in K255. Total phenolics were found to be a poorer predictor of perceived bitterness (correlation 0.69) compared with the almost perfect, K255 (correlation of 0.98). The bitterness of these oils could be predicted by multiplying the K255 measure by 14 and subtracting 0.6

Comment: The K255 index for bitterness was first proposed in 1992 and has been used quite widely by the international industry. Compared to total phenolics, K255 is a very easy and quick and accurate analysis. I’m not sure that the paper broke any new ground except that it provided a link between the K255 measure and bitterness ratings using the IOC rating scale. But of course the relationship given above is wholly dependent on the panel that provided the ratings. While bitterness is one the attributes on the official IOC rating sheet, to the best of my knowledge, unlike the defects, cross panel comparisons for bitterness is not conducted. Well it wasn’t done when I was a panel leader anyway. Regardless of panel differences, K255 still seems to be a good predictor of relative bitterness amongst samples.

The relatively poor relationship between bitterness and total phenolics was unexpected. I have seen other data sets where the correlation was much stronger than reported here. Interestingly, the method used to determine total phenolics was not given which was a major oversight given that the method of extraction of phenolics from the oil plays a crucial role in the outcome. The method is also notoriously subject to variable results (where a 10% error is accepted by those who do them), so doing triplicate or more replications would be needed to ensure that the poor relationship between total phenol measures and bitterness wasn’t due to measurement error.

Faviti et al. (2013) Extra virgin olive oil bitterness evaluation by sensory and chemical analyses. To appear in: Food Chemistry DOI: http://dx.doi.org/10.1016/j.foodchem.2013.01.098

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Crushing between 1 and 10% leaves with ripe olives resulted in oils with higher free fatty acidity, peroxide value and K232 (measures of primary and secondary oxidation respectively). Adding leaves produced oils with higher chlorophyll aka they were greener. Adding over 5% leaves also increased oxidative stability and tocopherol content.

Comment: Lab scale work. Phenolics were not measured which seemed to be an oversight given that both tocopherols and phenolics contribute to oxidative stability. Also personally, I’d like to think that the oil I buy is made from olive fruit rather than leaves. Call me old fashioned.

Malheiro et al. (2013) Effect of olive leaves addition during the extraction process of overmature fruits on olive oil quality. Food Bioprocessing Technology,6, 509–521.

DOI: http://dx.doi.org 10.1007/s11947-011-0719-z

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Malaxing for 40 minutes at 35C caused a 25% increase in both total phenolics and the pungent phenolic oleocanthal compared with malaxing at 25C (Figure 1), which could be explained by a 50% reduction of the activity of the major enzyme (polyphenol oxidase,  PPO) responsible for oxidative losses of phenolics at the higher temperature. The longer malaxation time, the lower the total phenolics.

Figure 1: Concentrations (mg/kg) of oleocanthal and total phenolics as a function of malaxation temperature (malaxation time = 40 minutes).

Comment: Mill scale work (yay!). The fact that high temperatures can knock out PPO probably also explains why dipping olives into hot water prior to processing results in oils with higher phenolics.

Bitchy comment: If you believe that EVOO is just a polyphenol dietary supplement (rather than a tasty food), then these results suggest that you should insist on HOT pressed olive oils.

Taticchi et al. (2013) The influence of the malaxation temperature on the activity of polyphenol-oxidase and peroxidase and on the phenolic composition of virgin olive oil. Food Chemistry, 136, 975–983.

http://dx.doi.org/10.1016/j.foodchem.2012.08.071

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12 Spanish people were fed a diet that was devoid of polyphenols except for an olive oil fortified with olive oil phenolics i.e.  +250, 500 and 750mg/L. Blood plasma content of the key phenolic substances that had passed from the digestive system increased substantially when the subjects ate the oils with +500mg/L phenolics. Eating oils with +750 mg/L phenolics did not increase blood plasma phenolics over the +500mg/L diet. The authors appeared to recognise that phenolics impact on the taste and therefore the acceptability of EVOO. They stated that “The sensory acceptance is the principal barrier for the acceptance of a functional food”. In the case of EVOO high phenolics relates to high bitterness and/or pepperyness. So they also determined the taste acceptability of the oils with added phenolics. As phenolic content went up, acceptance by the tasters declined. The authors felt that the olive oil with a content of 500 mg/kg of phenolics provided “a good pharmacokinetic response and a good sensory acceptability” (in laymans terms, a good compromise between being healthy and not being overly bitter). The olive oil with 500mg/L was rated on average somewhere between “I like it a bit” and “I neither like nor dislike”. They went on to say that” Moreover, by consuming 30 ml of M-EVOO (+500mg/L) it is easy to reach the 5 mg daily dose of hydroxytyrosol and derivates recommended by the EFSA Panel”

Comment: The authors should be congratulated for recognising that long term consumption of a healthy food is only assured if it has an acceptable taste. EVOO included. But why not consume 60gms of something you really like, rather than 30 gms of something that you only like a bit?

Rubio et al. (2012) Impact of olive oil phenolic concentration on human plasmatic phenolic metabolites. Food Chemistry, 135, 2922–2929.

http://dx.doi.org/10.1016/j.foodchem.2012.07.085

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Olives did not make up a significant area of land in Southern Spain the 20^th century. In the mid 18^th century the land dedicated to olives was around 1/20^th of what it is today. Groves as we know them today were rare. Olive trees were scattered amongst other crops particularly cereals which made up over 50% of the arable area, and were managed more as a forestry enterprise with very few inputs and little management. Olive trees were grown as they provided a wide range of products – pomace and leaves for fuel and livestock feed, oil for lighting and for soap production. Olive wood was used for fuel at twice the rate as forest wood in 1750, and the percentage of olive wood to forestry wood used for fuel increased up until the early 1900’s. Clearly the diversity of outputs was well suited for small subsistence landholders.

However, in 1750 only 8% of the oil produced was eaten, the rest was used for lighting and animal production. 90% of fat intake in Baena (a major olive growing region in Southern Spain) was animal fat, with olive oil making up the remainder. It was only around 1900 when the consumption of olive oil first surpassed that of animal fats,

The final decades of the 20^th century saw olive growing increase significantly. Area to olives in Andalucia increased by 300,000 ha and oil production tripled to current levels. The authors attribute this to increased supply due to industrialisation of agriculture, modernisation of mills (both resulting in significantly higher oil yields per ha), and the introduction of EU subsidies. On the demand side, appreciation of the health benefits of olive oil has stimulated worldwide demand. Finally, olives were not seen as a single crop in the Andalucian landscape on any scale until well into the 20^th century.

InfanteAmate(2012)The Ecology and History of the Mediterranean Olive Grove: The Spanish Great Expansion, 1750 ­ 2000. Rural History. 23: 161­-184 doi:10.1017/S0956793312000052

Comment: Very interesting as this paper presents evidence that suggests that the use of olive oil as a major part of the Med diet may be a relatively recent phenomenon. No doubt the olive tree was an important crop as it provided a number of resources for small scale subsistence farmers. As one of my friends commented. Perhaps in 1750 when people died of TB, diptheria, plague or even minor infections, the concept of eating something healthy to prolong life may have been a bit weird.

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Normally I comment after presenting research results but this time I’ll comment first by saying that this was 20 minutes of my life that I will never get back. This paper compared 2 phase, 3 phase and a traditional press with respect to total polyphenol content and polyphenol type in the oil, waste-water and pomace. The researchers also measured antioxidant activity so they could comment on the healthfulness of the oils produced by the three systems. There was extensive analysis of the types of polyphenols using high performance liquid chromatography.

However when I later read the methods carefully, the researchers had used three different batches of olives, with each batch being a different variety grown in different places, with a different batch being processed using each of the different extraction methods. e.g. Variety X from place A was processed by press, Variety Y from place B was processed by 2 phase and Variety Z from place C was processed by 3 phase. How could they possibly think that they could compare systems when the effect of processing system is totally confounded with the effect of the olive source? I won’t even summarise with what they came up with (although the results seemed in line with expectations).

An example of the danger of just reading the abstract.

Klen and Vodopivec (2012) The fate of olive fruit phenols during commercial olive oil processing: Traditional press versus continuous two- and three-phase centrifuge. LWT – Food Science and Technology 49, 267-274  doi:10.1016/j.lwt.2012.03.029

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Enclosing the vertical centrifuge in a container filled with argon with an oxygen level of 3% reduced dissolved oxygen in the oil by 6.8 mg/L (71%), peroxide values by 3.8 (44%), and K232 by 0.46 (27%) compared with decantation under air. FFA and polyphenol level were unchanged.

Masella et al. (2012) DOI: 10.1002/ejlt. 201100400

Comment: Others have found that vertical decanting is the primary cause of dissolved oxygen in EVOO. The large effects reported here support this. However how this could be put into practice is unclear.

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Olives were stored in plastic bags under high CO2 modified atmosphere and at 5C for up to 21 days prior to being processed. The first sampling day was at day 7. Free fatty acidity increased as expected with storage time, but the increase was lower under the modified atmosphere and at 5C compared with when the olives were stored in a normal atmosphere at room temperature. Over the most realistic storage time used in this study (7 days), total polyphenols and radical scavenging activity fell except when the olives were stored in the modified atmosphere at the lower temperature. The bitterness index increased with storage time.

Ben Yahia et al. (2012) Quality, stability and radical scavenging activity of olive oils after Chétoui olives (Olea europaea L.) storage under modified atmospheres. Food Science and Technology International 18: 353-365. DOI: 10.1177/1082013211428102

Comment: Only a small amount of olives were stored (1.5kg). It would be interesting to see if the same results were observed in a more realistic situation of having bins of olives whereby heat builds up due to fermentation, and that the olives are generally starved of oxygen in these bins due to carbon dioxide production. The realistic storage time comment was in the context of, most producers try to keep the time between harvest and processing to a minimum. However, due to unusual circumstances (e.g. equipment breakdown), sometimes olives have to be stored for a short time. Ok, not 7 days, but this was the first time point of analysis in this study.

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Remember the 1970’s when a person could be convicted of murder on the basis of a strand of hair left at the crime scene. If it was the same colour and was the same thickness to that of the accused, then that would do. We look back on that now and most of us would immediately recognise the huge potential for incorrect prosecution. DNA methods have reduced the potential error rates from 1 in 100 to 1 in hundreds of millions. Trying to convict someone today solely on the basis of the physical characteristics of a hair sample is now unthinkable.

But when it comes to detecting olive fraud, that is exactly what is happening right now.

Here are some examples of the “conviction by hair strand” approach that we currently apply to detecting fraud in olive oil, and how it is supposed to work.

A whole bunch of chemistry standards have been approved by the International Oil Council in an attempt to identify olive oils that have been adulterated with another cheaper seed oil such as sunflower, canola and soybean. However, the problem is that most edible oils are made of most of the same sort of stuff as olive oil. For example, olive oil contains a lot of the fatty acid oleic acid (typically around 70-75%). However, other oils such as canola contain credible amounts of this same fatty acid, and sunflowers have been bred to produce oil that has oleic levels equivalent to or greater than olive oil. So if a fraudster added 30% high oleic sunflower oil or 20% canola oil to a typical EVOO it will create a fraudulent oil with an oleic content that still is well within the range normally expected of real  EVOO (officially 55-83%).

So the answer? Introduce more chemical measures of course! Edible oils contain substances called sterols. Some are found exclusively in one type of oil, but the majority are found in all oils but the amounts vary depending on the type of oil. For example, the sterol Brassicasterol is found only in canola oil in more than trace amounts. Conversely, the sterol campesterol while being the predominant sterol in sunflower oil, is also found in reasonable quantities in olive oil.

So while the oleic acid level of an olive oil will not change significantly when adulterated with canola oil, the resulting fraudulent oil will contain high levels of brassicasterol – a dead sure sign that it had been adulterated. It’s not just a smoking gun, the culprit has been caught standing over the body with the smoking gun in hand, with the act caught on DVD quality CCTV.

On the other hand, if the olive oil was adulterated with sunflower oil it would register an elevated level of campesterol. But elevated compared with what? Real olive oil naturally contains campesterol as well, and being a natural product, that level varies from oil to oil (mostly dependent on the variety of olive). Think about it for a moment. if you added sunflower oil to an olive oil with a low campesterol level, then it may actually have a total campesterol level lower than some 100% olive oils. As the international convention stands, oils with more than 4% campesterol are deemed not to be extra virgin, and I guess by inference they have been deemed to have had sunflower oil added (as campesterol has no negative sensory impact and it is a healthy cholesterol lowering sterol). But make no mistake, there are thousands of legitimately made EVOO’s made each year throughout the world that have more than 4% campesterol. The 4% level has been arbitrarily set by EU olive oil politicians and as such those thousands of oils have (analogously) been convicted on the basis of the width of a hair found at a crime scene.

So what is the solution? Arguments regarding what is an appropriate level of this or that when it comes to catching out fake olive oils will continue forever, but every level that is chosen will necessarily be arbitrary. If the level is lowered, it will be harder to adulterate with sunflower oil and get away with it, but it will also mean that even more hard working legitimate producers of olive oil will be labelled as cheats. If the level is increased, the number of false positives for cheaters will decline but it will be easier to adulterate oils and get away with it. Science has little to do with it, so long as campesterol is found in oils other than olive (i.e. forever).

But there is a solution. DNA testing. And it’s not a pipe dream.

To date, DNA testing has been considered by many (mostly chemists surprisingly) not to be a viable alternative to solving the intractable problem of using chemical markers of adulteration that are found in olive oil itself.

The reason is that very little of the original plant DNA remains in oil once it is refined (as is the case with all oils used for adulteration). But remain it does. Olive oil may contain a lot of things but sunflower, hazelnut or soybean DNA aren’t on the list.

Methods have been developed to extract DNA fragments from edible oils and the efficiency of procedures that are used to amplify these fragments have increased by orders of magnitude in recent years. These improvements have meant that lower volumes of oil need to be extracted in order to obtain a sufficient amount of DNA for accurate identification (Agrimonti et al. 2011). Very recently, Zhang  et al.(2012) detected adulteration of olive oil by sunflower, sesame and soybean oils as low as 10%. I’m not an expert in this area, but their methods seemed orthodox using a couple of commercially available primers and standard amplification techniques. The authors concluded that:

“Despite all the advantages of DNA method, DNA collection from oil turns into a bottleneck for a widespread application in market supervision. Therefore for all DNA methods sample preparation is always a critical point to be improved”.

So there is quite a bit of work to be done. However, consider this. It took over 2,000 man-years of effort and over 6 billion dollars to sequence the human genome using technology available 10-15 years ago. Using soon to be released technology from Oxford University (you can read about it here doi:10.1038/nature.2012.10051), it is estimated that 96% of the human genome could be sequenced for a few thousand dollars over a weekend, and that simpler organisms such as yeasts and bacteria could be sequenced in a few minutes by a smaller one off use $800 device that  connects to a USB slot on a laptop. That is the rate of advancement in this field. So in this context it would appear that the problem of cost efficient ‘sample preparation’ of edible oils before DNA analysis is far from insurmountable.

The advances in this field are extraordinary, and while we continue to spend money on trying to tweek possible chemistry based solutions (and even more time arguing amongst ourselves at international forums as to what is an appropriate level of this or that), a definitive genomic based solution is probably just around the corner.

So surely it’s time to move towards DNA evidence to convict real adulterators and make false convictions by the physical appearances of a hair or two a thing of the past.

Sources: (past the doi number into the search box at www.doi.org)

Agrimonti et al. (2011) doi:10.1016/j.tifs.2011.02.002

Zhang et al. (2012) doi:10.1016/j.foodcont.2012.03.027

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Extra Virgin Olive Oil has three basic commandments.

1.  Thou shalt not store olive oil in the light
2.  Thou shalt not store olive oil in a warm place
and
3.  Thou shalt not store olive oil in plastic

Oxidation reactions in all fats including olive oil are catalysed by light. Once the reaction starts, it is self propagating and unstoppable. The oxidation reaction creates free radicals that oxidise fat molecules – a by product of which is more free radicals that go on to oxidise more fat molecules. The inevitable result is an avalanche of oxidation, and like nearly all chemical reactions in nature, the warmer the conditions the faster it goes. Thus explains the role of heat and light in a junior high chemistry sort of way.

But let’s move onto the purpose of this blog. To investigate the last commandment that ‘Though shalt not store olive oil in plastic’.

In short the story line goes like this: If you store olive oil in plastic containers then it will oxidise faster than if you store it in glass. I presume that the belief stems from the very reasonable tenet that glass is totally impermeable to oxygen but plastics are not. So of course it must be the case. But is it?

My interest in this matter was pricked, or more accurately rekindled by a powerpoint slide presented at a 2011 Australian EVOO conference by Claudia Guillaume from Modern Olives. Her work focussed on the changes during bottle storage of a couple of new chemical indices that had recently become part of the new Australian olive oil standard. But what raised my eyebrows was a rather innocuous figure on one of her slides that it appeared to show that an extra virgin olive oils stored in amber coloured PET plastic bottles outperformed glass with respect to some of the trusted measures of oxidation.

I had been tentatively looking at the scientific literature on the topic for a while but I always left feeling frustrated regarding the types of comparisons that were being made. There were many examples of ‘clear’ examples of one packaging (usually PET) being compared with ‘dark’ examples of another (always glass). Sometimes the oils were being stored seemingly endlessly in full light and under hot conditions presumably just to reinforce that heat and light are the enemies of extra virgin olive oil. Strange as no one was really questioning it.

In one notable instance, glass bottles were filled with extra virgin olive oil to a normal fill height, but the PET bottles were only filled to 1/3^rd volume, the remaining 2/3rds of a bottle being full of apparently inert air. The PET containers were subjected to full light for two months, but those in glass were kept in the dark. The researchers concluded that “the quality loss of extra-virgin olive oil following storage in PET bottles for only 2 months was beyond the acceptable level from both the analytical and sensory points of view” (and incidentally they didn’t conduct any formal sensory trials). I wonder what they were expecting? Unfortunately, early papers in any field have a habit of cementing a collective persistent mind-set, particularly if the conclusions are in line with peoples’ expectations. In another instance (a very recent one I might add) the scientists put one extra virgin olive oil in glass and a different EV in PET. They didn’t mention that in their methods (you would think it an important detail wouldn’t you), but it was clear to see when you inspected the basic analysis of the oils at t=0 that they were different. The oils in PET had higher initial oxidation indices, so the avalanche was half completed in the PET bottles before the experiment had even begun.

The second reason for looking at the question more carefully is that advances in packaging technology have resulted in the wide commercial availability of many new variants of PET. Today, there are dark e.g. amber coloured, and totally opaque versions. They can be moulded with thicker walls and therefore lower oxygen permeability. Other technologies have succeeded in bringing down the oxygen permeability of PET v1.0 by between 2 and 7 fold (Gambacorta et al. 2004). The first called passive barrier technology involves placing additional thin barrier film(s) over the PET in order to make it harder for the oxygen molecules to pass through. The other, called active technology, involves either impregnating UV light blocking or oxygen scavenging substances into the molecular polymer matrix of the plastic. In the latter case, as oxygen permeates the PET, some of it gets chewed up by the impregnated antioxidants before it can damage the oil contained inside. Active and passive technologies have also been combined into a single polymer – sort of a oxygen condom and oxygenicide all in one package if you like.

But before we start. A little about the indices that people have used to measure oxidation and general oil quality in these studies.

Free Fatty Acidity FFA – measures the amount of oil degradation. Most degradation occurs before or at harvest due to enzymatic activity which can only occur in the olive and during processing. After an oil has been bottled enzymatic activity is pretty well zero so increases in FFA are usually small after bottling.

Peroxide Value (PV): is an index of the number of free radicals that are in the oil. As such it is a good measure of an oils potential to oxidise. It is a tricky one to interpret as it is very dynamic. Peroxides are formed by oxidation, but are in turn used up as the oil ages. So as an oil ages they can go up or down depending on what’s happening in the complex world of oxidation and reduction in the oil. So while a high PV is a very bad sign in a young oil, it could be argued that a ‘potential to oxidise’ measure applied to a 12 month old bottled oil is not of great practical importance.

K232: When an oil oxidises it forms compounds called dienes that absorb ultraviolet light strongly at the particular wavelength of 232 nanometres (nm). As it is a measure of how much an oil has oxidised (rather than its potential to do so), it is an important measure in the context of longer term packaging studies such as these.

K270: When an oil oxidises even further it forms compounds called trienes. These absorb strongly at the wavelength of 270 nm. So as per the explanation above, high K270 values mean that an oil is in an advanced stage of oxidation. This is another important measure of the amount of oxidation experienced by an oil at the end of its commercial shelf life.

Polyphenols are naturally occurring antioxidants that sacrifice themselves in a valiant attempts to fight oxidation, and longer and more intense the fight, the greater the reduction in polyphenols over the life of the oil.

In light of some of the less than satisfactory comparisons performed in the past, I scoured the literature to find published papers whereby they demonstrated some semblance of a fair comparison.The studies discussed met the following criteria:

1) the major experimental variables were properly controlled and replicated

and

2) logical and fair comparisons were made i.e.

– The same coloured containers (clear/clear or dark/dark) were compared if stored under lit conditions

– The same or different colours, or levels of light opacity were compared if the oils were stored in the dark.

– The oils were stored at a reasonable (room) temperature for the duration of the study (like it might be stored on a supermarket shelf or a household pantry).

and

3) the time point I chose for discussion was that closest to 12 months, or the latest time point if the study did not extend that long. This was chosen on the basis that 1) EVOO is produced on an annual basis and 2) that if you store bottled EVOO for longer than 12 months you deserve all the rancidity that nature can throw at you (and you probably aren’t reading this blog).

Here is a table that summarises who did what, when, and how.

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

The figure above summarises the recent results of Guillaume and Ravetti (2012). This is the only study that looked at the effect of storing in dark PET under light. The base oil was a good quality, low polyphenol EVOO. Of note was the higher PV in PET (consistent with other studies), but lower measures of secondary oxidation and slightly lower reductions in phenolics compared to dark glass. The dark PET clearly outperformed clear glass on the measures of secondary oxidation. Acidity was largely unchanged by storage in any container type. The red lines show limits for extra virgin status as defined by the International Olive Council (IOC).

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

The figure above is compiled from the data of Mendez and Falque (2007). The effect of storage was more strongly felt by this oil than seen in most other studies. The reason for this is unclear. This study also investigated some different packaging types such as tins and tetrapak. The FFA rose in all packaging to around the same extent. Glass produced the highest PV, and PET covered in foil to exclude all light the lowest PV. Losses in polyphenols were greatest in the clear PET, but tetrapak and tins outperformed glass in this respect.

This paper by Pristouri et al. (2009) logically consisted of two parts – the first is glass v plastics and the second compared the different types of PET. I have discussed them separately.

In the first part, polypropylene which has a high oxygen permeability compared to PET was also included. Of note was that a poor quality extra virgin olive oil was used. At the time of packaging it had an FFA of 0.6%, a peroxide close to 10 and most importantly, high levels of secondary and tertiary oxidation. It had all the chemical parameters of a two year old (or more) EU supermarket oil (see the supermarket oil reviews conducted in this blog).

After 12 months, the oil in all packaging types were all above the IOC limits for EVOO for all the parameters measured. In light of the fact that all of them were stuffed, glass outperformed both standard PET and polypropylene, but it was clearly the case of the best of a very bad lot. Despite this, the authors still concluded that PET only had a shelf life of 3 months, and glass 6 months – a conclusion drawn based on the time taken for the already oxidised oil to go beyond the IOC analytical limits. However this experiment is analogous to  checking in your 98 year old great-grandfather into a nursing home, and then complaining that the home was to blame when he died the following week!

In the second part Pristouri et al. (2009) compared clear PET with foiled covered PET and one containing a UV blocker using the same poor quality oil. Small improvements in performance were seen in the higher tech PET and that covered in foil, but reiterating, this oil was pretty cactus even before it was bottled so I guess it shows that glass is a better container for holding oils on the way to be turned into biodiesel.

Sacchi et al. (2008) looked at PET v 1.0 and those containing various amounts of oxygen scavengers over a relatively short period of 6 months. The oil stored in all forms of PET oxidised to the same level (chemically) or lower compared to the same oil stored in glass.

This is an important study as it is the first to formally consider the amount of dissolved oxygen in the oil at bottling. The amount of dissolved oxygen at bottling is a crucial variable that is rarely measured. Oxygen is very soluble in olive oil.  At saturation, a half litre bottle of olive oil at room temperature will contain 18 milligrams of dissolved oxygen – a level that presumably would not be difficult to achieve if oil is bottled under air (particularly as it has almost half of that level when coming out of the decanter). So what is the relative contribution of PET to oxygen content via transmission during storage? Over 6 months, 3mg of oxygen was transmitted through the walls of a standard 500 mL PET bottle, and 1.5-2.0 mg permeated the walls of PET with oxygen scavengers (di Felice et al. 2008). So based on these figures, the amount of dissolved oxygen that potentially exists in the oil at bottling can far exceed the amount that could potentially be transmitted through through an unopened PET bottle over what is a reasonable amount of time on a shop or pantry shelf. It would also make sense that if an oil has a high level of dissolved oxygen at bottling then the effect of a packaging material with a higher oxygen ingress would have less impact. Other researchers should take note!

Indeed, the authors concluded that “The differences in the shelf life observed between oils bottled in PET and oils bottled in glass are attributable to a difference in the initial content of dissolved oxygen in the oils.”

The tocopherol (a type of Vitamin E which acts as a healthful antioxidant) of the oil was around 190mg/kg at bottling. After 6 months it had dropped to between 25and 40mg/kg with storage in glass experiencing the greatest fall (Figure 2 in their article). These researchers also rated the rancidity of the oils using a sensory panel. The rancidity scores for the oils stored in PET with scavenger were lower (around 1) than when the oil was stored in glass (rancidity score of 3) (Figure 4 in the article).

The researchers also stated the type of capsule that was used to enclose the oil. Glass might be impenetrable to oxygen, but the cap that holds the oil in certainly isn’t, particularly if one uses a polypropylene plastic capsule. No other studies recognised this fact.

Cecchi et al. (2010) compared standard PET with that containing an oxygen scavenger. A glass treatment was not included in this study, but the results show the improvement in performance of PET containing oxygen scavenging material compared with PET v1.0.

In this study by Gambacorta et al. (2005), the different variants of PET were compared with glass bottles. The trend was for glass being a slightly better container than either PET with scavengers, or with a barrier film. However, when the two technologies were incorporated into the same bottle, the performance of the container was very similar to the glass container both in terms of standard oxidation indices, and sensory quality score. Another aspect worth noting in this study was that the researchers used commercially realistic pack sizes (1L) rather than the often used laboratory sample bottle sizes which do not adequately replicate the volume to surface ratio of commercial packaging.

Conclusion

A review of independently conducted shelf life studies published in referred scientific journals failed to reveal any systematic or significant superiority on the part of glass packaging in terms of standard measures of oxidation when the oils stored in a manner whereby they were exposed to similar amounts of light and at room temperature over 13 months or less.

I’d be very happy to hear from you if you think you see any omissions on the oxidation aspects of using different packaging material, or if you would simply like to discuss my interpretation of the data presented.

Sources:

Cecchi et al. (2010) Study of the quality of extra virgin olive oil stored in PET bottles with or without an oxygen scavenger. Food Chemistry 120, 730–735.

DiFelice et al. (2008) Oxygen permeation in PET bottles with passive and active walls. Packaging Technology and Science 21, 405–415.

Gambacorta et al. (2004) Shelf-life of extra virgin olive oil stored in packages with different barrier properties. Italian Journal of Food Science 16, 417-428.

Guillaume and Ravetti (2012) Evaluation of new analytical methods to detect lower quality olive oils. RIRDC Publication No. 12/007.

Mendez and Falque (2007) Effect of storage time and container type on the quality of extra-virgin olive oil. Food Control 18, 521-529.

Pristouri et al. 2010 Effect of packaging material headspace, oxygen and light transmission, temperature and storage time on quality characteristics of extra virgin olive oil. Food Control 21, 412-418.

Sacchi et al. (2008) Shelf life of vegetable oils bottled in different scavenging polyethyleneterephthalate (PET) containers. Packaging Technology and Science 21, 269–277.

This blog is a personal interpretation of data collected and reported by others. It does not constitute professional advice.

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I’ve always found it irritating when people compare the quality of extra virgin olive oils that vary greatly in price. I’ve frequently seen inexpensive high volume $10/L supermarket oils compared with some $150/L oil from a little family owned estate making a couple of hundred litres. It’s not surprising that the boutique oil often come up trumps.  But then again it’s unlikely that the average American, Australian or German family shopper will entertain the idea of forking out $30 or $40 for a few splashes of extra virgin olive oil regardless of how good it is.

So here I’ve stuck to comparing two top selling Australian supermarket oils with equivalent price-tags. One a Spanish oil and the other Australian.

In a boxing parody I’m comparing the oils round by round, firstly using the important chemistry aspects of the oils – free fatty acidity for general quality, oxidation status, and finally the important taste test.

So let the challenge begin:

In the Clear corner and coming in at $12.78 per litre is the Spanish oil Moro.

In the Green corner with a slight price disadvantage at $13.30 per litre is the Cobram Estate Classic.

Here’s the call of the tape:

	Moro (ESP)	Cobram Estate ‘Classic’ (AUS)
Batch	1140-46249	2094
Purchased	Woolworths Mitcham, SA	Woolworths Mitcham, SA
Best Buy Date	None Given!	17-8-2013
Price/L	$12.78	$13.30
Package	500ml clear glass	375ml dark green glass
Source	Spain	Boort and Boundary Bend, Victoria Australia
Date Analysed/Tasted	19/5/2012	19/5/2012

Ding…

Round 1

Proudly sponsored by “Absorbance at 232 – Your measure of primary oxidation”.

The lower the number the better. International Olive Council upper limit for EVOO: 2.50

Cobram Classic: 1.32  def.  Moro : 1.73

First round goes to the Cobram Estate Classic without breaking into too much of a sweat.

Round 2

This round sponsored by “Absorbance at 270 – your measure of secondary oxidation”

The lower the number the better. International Olive Council upper limit for EVOO: 0.20

Cobram Classic: 0.085  def.  Moro: 0.180

Cobram easily takes round 2.

The next round is an important one. The Moro is showing its age compared to the younger Cobram contender. The next round will show more about the overall class of the contenders.

Round 3

The Major Sponsor of the Night…. “Free Fatty Acid – we tell you what you want to know”

FFA is an overall quality measure of the soundness of the olives prior to processing, amount of time between picking and processing into oil, and in the overall care taken in processing.  The lower the percentage the better: The International Olive Oil Council limit for EVOO is an insanely high 0.8%. If you got into the ring with that amount of excess weight you would be pummeled by the contenders that are popping up all over the place from Australia, the US and Chile. However, the world governing body seems blind to the message that fat and old can’t win.

Cobram Classic: 0.25%  def.  Moro: 0.44%

The round was shorter than the 3 minutes that it takes to measure FFA. An easy round win for the Australian. At an incredibly buff 0.25% FFA at this level of competition gave the comparatively flabby European little chance.

The Governing body in the EU should review this policy before anyone else gets hurt!

Round 4

The taste round

Round 1 and 2 saw a relatively tired contender come out against a fresher opponent, and it showed. Round 3 showed the new world contender has had some good preparation coming into the bout. But like in all contests, who ultimately wins gets down to overall class. It’s not the first time that an older flabbier opponent has handed out a knockout punch when it matters. Will it happen in the ‘all important’ final round?

Ding… The Conquistador comes out emblazened in brightly coloured red and yellow shorts and Olive oil of Spain across its back. The Murray Mauler who in a less traditional Mardi Gras inspired purple and gold strip comes out swinging with a burst of good fresh Tomato like Picual aroma. The Spaniard tries to counter-punch with its own version of a riper tropical Picual character, but doesn’t make much of an impression on the fitter opponent. Once again being picked early and fighting while young is making it difficult for the older contender to come up with any scoring punches. The Murray Mauler throws out a few jabs of pungency. I think that surprised the Spaniard. Once again the Spaniard has no answer to the more fiery opponent. A bitter uppercut by Cobram misses the mark, but the Spaniard doesn’t even bother attempting this more technical move. It’s getting close to the end of the round. The Spaniard is looking tired and is not putting up much resistance against what looks to be a much younger opponent. The referee is looking concerned. Yes, he’s waved it away…. The clear corner is incensed. We could go at least another 20 rounds they are shouting. But it’s all over,

The Aussie contender wins all rounds and by a unanimous points decision

The Moro oil was pretty typical of EU imported oils that are found on supermarket shelves in Australia and the US – ripe, sweet fruit flavours and low bitterness and pepperiness. While not being the worst of what I have tasted of EU offerings taken from Australian supermarket shelves, the oil did seem flat and greasy. In comparison, the Cobram oil was fresher and more vital. While the chemistry of the Moro was at the better end of the other EU oils that I have reviewed. For example, at 0.44% acidity, it was at the upper end of the FFA’s of Australian produced supermarket oils, but in this instance it was clearly inferior to its equivalently priced Australian made competitor.

Labelling High-lights and Low-lights

While it was pleasing to see that the Moro oil had its country of origin clearly stated (both as a sticker on the front label and officially on the back label as “Product of Spain”), the lack of any best by date is completely unacceptable. It shows a disregard for consumers. Given that the best by date is the only possible way in which a consumer can even vaguely assess the age of the oil that they are buying, the lack of such information is in my opinion unforgivable. Even though the best by date only tell you when the oil was bottled not when it was actually produced, this total lack of transparency takes fresh food labeling to a new low. The supermarket chain who I purchased this oil from, who calls themselves the “Fresh Food People”, need to appreciate that extra virgin olive oil has no preservatives and is therefore a perishable product. It is best when fresh, so they should mandate a best by date on this and every other extra virgin olive oil they stock.

The Moro oil also prominently stated that it was Extra Virgin Olive Oil, but directly underneath that in smaller font was stated “100% Pure”. Pure olive oil is a marketing term used by EU producers for a refined olive oil with a little virgin oil added to it. For decades, the use of the word ‘Pure’ has caused significant confusion in the marketplace. It doesn’t help when producers/importers of extra virgin olive oil give the terms Extra Virgin and Pure on the same label particularly when one term is given directly below the other. The new Australian standards prohibit the use of the term Pure even in refined oils which suggests a complete disregard for the National standards of the country which they trade in. The Australian standards are voluntary, but significant and open industry consultation occurred with both domestic producers and importers. So apart from the clear country of origin statement, the Moro label was disappointing to say the least.

Packaging High-lights and Low-lights

Once again it was disappointing to once again see an EU extra virgin olive oil packaged in clear glass. It seems incongruous that the back label informs consumers to store the oil in a dark place, yet clear glass is chosen for the packaging material. The dark green Cobram bottle sends a message to consumers that exposure to light should be avoided. So why are so many imported supermarket oils packaged in clear glass? One theory is that oils sell better when in clear glass compared with dark glass. Once again the new Australian standards include provisions that the best by date take into account the packaging material.

The Cobram oil had an inbuilt plastic pourer that popped up once the metal cap was removed. It was a bit of a “Jesus closure” though, as once the metal cap seal was broken and unscrewed, the pop up pourer ‘excitingly’ erected itself, causing the metal cap to launch it partly across the room with simultaneous shouts of “Jesus, where did that go?” But once you found the cap and were aware that the pop up pourer can act as a cap propulsion device as well as a useful pourer, all was well. Overall the pourer is a great consumer innovation, and was (may I say) a pleasantly salubrious one for a product at this price. “I’m excited” is a suggested advertising slogan for this pourer.

Overall

Given that the two oils are within 50c per litre or so in price, the Cobram oil had a much lower FFA, better oxidation indices and had more olive character and tasted fresher. On all counts measured, it was the superior oil.

As with all my reviews, while the chemical indices were measured with care, they are not to be interpreted as official measures.  The sensory assessments represent a personal evaluation and interpretation.

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