Crucial Olive Oil Chemistry Definition Key
Extra virgin olive oil decreases in flavor and health benefits over time. Fresh crushed olive oil is like fresh squeezed fruit juice in that it contains the most flavor and nutrients. Old, poorly made and improperly stored extra virgin olive oil yields fewer if any health benefits and undesirable flavor.
Becoming intimately familiar with a particular extra virgin olive oil's flavor characteristics and chemistry i.e. antioxidant content, oleic acid, FFA, and crush date will help you make an educated decision about which olive oil is right for you.
Oleic Acid: is a monounsaturated omega-9 fatty acid found in olive oil. Olive oil is generally higher in oleic acid than other vegetable fats. The range found in extra virgin olive oil is between 55-85%. Extra virgin olive oil high in oleic acid has greater resistance to oxidation.
FFA: Based on IOOC standards the maximum limit for free fatty acid in extra virgin olive oil is 0.8g per 100g or (.8%). A low FFA is desirable. Free fatty acid speaks to the condition of the fruit at the time of crush. The higher the FFA the greater the indication of poor quality fruit such as damaged, overripe, insect infestation, overheating during production or too much of a delay between harvest and crush. MORE on this.
Peroxide Value: Based on IOOC Standards the maximum peroxide value for extra virgin olive oil is 20. A very low peroxide value is desirable. Unsaturated free fatty acids react with oxygen and form peroxides, which create a series of chain reactions that generate volatile substances responsible for a typical musty/rancid oil smell. These reactions are accelerated by high temperature, light, and oxygen exposure.
Polyphenol Count: Polyphenols are a class of antioxidants found in a variety of foods. Polyphenols such as Oleuropein, Oleocanthal, and hydroxytyrosol impart intensity connected with pepper, bitterness and other desirable flavor characteristics. Recent studies indicate that these potent phenols are responsible for many of the health benefits associated with consuming fresh, high quality extra virgin olive oil. Phenols in olive oil decrease over time or when exposed to heat, oxygen and light. Consuming fresh, well made olive oil with high polyphenol content is crucial when looking to obtain the maximum health benefit commonly associated with consuming extra virgin olive oil.
New Testing Methods Based on Olive Oil Chemistry
DAGs Test/Score: Measures the proportion of two forms of diacylglycerol: 1,2 and 1,3. In oil freshly made from sound olives of good quality, the prevalent form of DAG is the 1,2 form where the fatty acids are bonded to a glycerol molecule in the 1 and 2 positions. The bond on the 2 position is weak and easily broken, leading to the migration of that 2 position fatty acid to the 3 position. This results in the much more stable 1,3 DAG. This makes the ration of 1,2 DAGs to the total DAG’s a good indicator of the quality of the olive fruit and the processing. It is also an indicator of the age of an oil, since the migration from 1,2 to 1,3 DAGs takes place naturally as the oil ages. Warmer storage temperatures, and higher free fatty acid levels will both accelerate this process, but DAGs are not affected by the short exposure to high heat that is characteristic of deodorizing (refining).
PPP Test/Score: This test was developed to measure the degradation of chlorophyll in olive oil. This degradation of chlorophylls to pyropheophytin was found to take place at a predictable pace, making it possible to gain information about the age of an olive oil. The rate at which the degradation occurs can be accelerated by even short periods of high temperatures – such as that which is utilized during the deodorizing or soft column refining process – making it a useful indicator of the presence of deodorized olive oil as well as the age of the oil.
Frying with Olive Oil
Olive Oil Polyphenols explained:
OIL TASTING METHOD
If a picture is worth 1,000 words, then how many words is a taste worth? In order to appreciate the range of flavours in olive oils, one must go beyond reading about oil and be willing to experience the act of tasting it.
Flavours in olive oil are determined by a wide range of factors including the type of olive (varietal), ripeness at harvest, growing conditions (climate, soil type), crop maintenance (irrigation, pest control), handling of fruit from tree to mill, and the milling process itself.
For example, oil made from predominantly unripe (green) olives contain flavours described as grassy, artichoke, or tomato leaf, whereas riper olives tend to yield softer flavours often described as buttery, floral, or tropical.
The above descriptions are associated with good olive oil quality, but trained tasters also learn to identify negative characteristics. Flavour defects in olive oil are associated with problems with the olive fruit (olive fly, frozen conditions), improper handling of olives during harvest (dirt, wet fruit, prolonged storage prior to milling), certain milling conditions (unsanitary equipment, excessive heat), and improper or prolonged storage after milling (oxidation). An oil that is determined to have flavour defects is not of genuine extra virgin quality; according to the International Olive Council extra virgin oils must meet both chemical and organoleptic (flavour) standards that include the absence of flavour defects.
The first step in learning how to taste olive oil is to understand how our senses work. Perception of flavour relies on both our senses of taste and smell. The ability to taste is quite limited; receptors on our tongue can only discern sweet, salt, sour, bitter, and umami (the flavour of protein). All other information that we think of as flavour is actually perceived by smelling food through the back of our nostrils (retro-nasally) while it is in our mouths. To illustrate this fact, think about how little flavour we perceive when we have a cold – this is because one cannot smell food retro-nasally when one’s nose is stuffed up.
When tasting olive oil, much of the oil’s characteristics are perceived through the sense of smell. Though most people enjoy olive oil with other foods, the following steps allow us to focus on the olive oil’s flavour without distraction:
• Pour a small amount of oil (about 1 tablespoon) into a small tapered (wine) glass.
• Hold the glass in one hand and use your other hand to cover the glass while swirling the oil to release its aroma.
• Uncover the glass and inhale deeply from the top of the glass. Think about whether the aroma is mild or strong. You may want to write down descriptions of
the aromas that you detect at this point.
• Next you slurp the oil; this is done by sipping a small amount of oil into your mouth while “sipping” some air as well. (When done correctly, you will make that
impolite noise that would cause you to be scolded when you were a child!) Slurping emulsifies the oil with air that helps to spread it throughout your mouth -
giving you the chance to savor every nuance of flavour with just a small sip of oil.
• Finish by swallowing the oil and noticing if it leaves a stinging sensation in your throat.
Each of the above actions focuses our attention on a specific positive attribute in the oil. First we evaluate the olive fruit aroma (fruitiness) by inhaling from the glass. When the oil is in our mouths we further evaluate the aroma retro-nasally as well as determine amount of bitterness on our tongues. Lastly we determine the intensity of the oil’s pungency in our throats as we swallow it.
Perhaps you noticed that the oil’s color is not addressed during sensory assessment. The reason is that contrary to the common belief that golden oil is mild and dark green oil is robust, color is NOT an indicator of either the oil’s flavour or quality. In fact, in scientific assessments, we sample from specially designed blue glasses that obscure the color of the oil. Tasting from a dark glass prevents us from having preconceptions about the
flavour of the oil before we actually smell or taste it.
TRY THIS EXERCISE
Once you are comfortable with the above tasting method, try the following exercise. Select three oils labeled as extra virgin, including an inexpensive imported brand from the supermarket. In between samples, clean your palate by eating a small piece of tart, green apple (preferably Granny Smith) and then rinsing your mouth with water. Consider the following as you evaluate each sample:
• Is the aroma pleasant or unpleasant?
• Is the aroma mild, strong, or somewhere in the middle (we’ll call that medium)? When assessing the second and third oils, note if the aroma’s intensity is weaker or stronger than the previous sample.
• Note 3 words (or phrases) that describe the aroma.
• Is the oil bitter, which is primarily sensed towards the back of the tongue? Would you describe the bitterness as mild, medium or strong? Is the intensity of the
bitterness in balance with the intensity of the aroma?
• When you swallow the oil, how does it feel in your throat? Did the oil leave a mild impression, or did it sting your throat or make you cough? Is the intensity of the
oil’s pungency in balance with the oil’s aroma and bitterness?
When you have completed the above exercise, take a few moments to review your notes. What were the characteristics that you enjoyed the most? Were there any
characteristics that you didn’t enjoy? How did the supermarket brand compare to the other oils? Even without an experienced taster sharing their thoughts about the oils with you, there is much you can learn by tasting olive oils on your own.
Using this same tasting method, you can sample another set of oils on another day, and still be able to compare your responses to the first set; this is how we build our personal olive oil “vocabulary”. You will begin to recognize flavours and may even discover which varietals produce the flavours you prefer. You will learn to compare the level of intensity for fruity aroma, bitterness and pungency, and will begin to identify oils as mild, medium and robust (intense). It’s a good idea to organize your tasting notes in a binder so you can review your past tasting experiences with new ones.
Worldwide over 1,000 varieties of olives are grown, which should give consumers a wide range of flavour possibilities. Taste is personal, so not everyone will agree on which varietals, and other factors, produce the best oil. However, tasting oils in a methodical fashion will help to educate your palate, and you will be able to select oils with flavour characteristics that you enjoy and enhance your meals.
Olive Oil Tasting Descriptors From world reknown Olive Oil expert, Richard Gawel:
HOSTING YOUR OWN OLIVE OIL TASTING PARTY
Hosting a tasting party adds a fun element to a dinner party. But the key is to know how to dose everything, especially when it comes to food. Tasting between 3 or 4 olive oils is plenty for one night, especially if you are newbies.
Try to mix oils from different countries. You do not need to be an expert to host your own tasting party.
Simply stop by a fine speciality shop with a wide selection (like All Of Oils) and ask them to compose an assortment of olive oils that will allow you to taste the differences. I often ask if I can record their advices with my Flip video camera. Otherwise, write down notes. Then, design cute note cards with the characteristics of each olive oil. (We can provide these for you!) Each guest should receive their own set of cards. Leave some room for them to write down their impressions.
Preparing the Tasting
You start the night with the tasting. They replace the appetizers of a typical dinner party. Then, move to a dinner with Mediterranean cuisine recipes to stay in the theme. (Many recipes available on this site)
Do a test run of the olive oil tasting to practice the technique and see that everything will be properly in place. As a bonus, you will know how filling is the tasting part and know how much food you need to prepare for the dinner part.
Prepare plenty of small glasses (dark blue is best - we can rent you some) since these mask the colour of the oil and eliminate sight sensory bias. This is the way the professionals taste an olive oil. You will see that the technique resembles wine tasting.
• Pour about 1 tablespoon into a small glass
• Like with wine, you swirl your glass while cupping the glass in one hand while holding your other over the top. This warms the oil to help release all its flavours and aromas.
• Then, you inhale and pay attention to the smell
• Next, you slurp the oil until you capture a small amount
• Finish by swallowing the oil. Try to notice if it leaves a stinging sensation in your throat. (This will come about 2 -3 seconds after swallowing) That last part is to determine the intensity of the oil’s pungency. (Determined by the Polyphenol amount)
If your guests are not comfortable drinking Olive Oil straight out of the glass or if they just want to continue enjoying the oils with and accompaniment, set up a dipping bowl for every olive oil. Your guests can then taste the oil with small pieces of your favourite breads.
To make sure you get the full unbiased flavouring experience with each Olive Oil you're tasting, make sure to cut slices of Granny Smith apples and/or serve glasses of lemon water. You eat an apple slice and drink some water between each sample to clean your palate.
Frequently Asked Questions about Extra Virgin Olive Oil
Permission to reproduce this is document is freely granted to those wishing
to promote extra virgin olive oil, provided that original authorship is clearly
acknowledged. © 2009 Richard Gawel
www..aromadictionary.com/oliveoiltasting.html twitter name: oliveoilguy
What is Extra Virgin Olive Oil?
Extra virgin (EV) olive oil is the oil extracted from fresh olives using a mechanical process without the use of excessive heat or any form of additives or solvents.
Provided that the olives are free from disease and they are processed into oil without delay using a clean mill they should produce an olive oil that has an aroma and flavour that is free of taste defects and as such is of extra virgin grade.
It should be noted that EV oils can be legitimately made without using a press. In fact most EV olive oils made in commercial relevant quantities are not made by pressing but instead by centrifugation of the paste made by crushing olives. What pressing and centrifugation have in common is that they are both mechanical processes and neither involves the use of any chemical agents.
The heat bit is more of a technical issue. You can extract more oil out of olive paste if you heat it up. However, the quality of the oil will suffer as a result. The application of some heat is necessary in order to extract commercially viable amounts of oil with good aroma and flavour. 28-30 degrees Celsius is the ideal with 32 degrees Celsius being the upper end of the temperature range used by most producers interested in quality.
What is the difference between Extra virgin olive and those labeled "pure‟ , "light‟ or simply "olive oil‟?
Extra virgin olive oil is essentially the naturally extracted juice from fresh olives. The olives are crushed into a paste, and the oil is physically extracted from this paste without the use of chemicals or excessive heat. Extra virgin olive oil has a distinctive olive fruity aroma and flavour and it contains natural antioxidants. The aroma and flavour, of olive oil adds complementary flavours to a wide variety of dishes.
'Pure' and 'light' and those labeled „olive oil‟ are olive oils that have been refined. Refining is a complex process that involves the use of acids, alkalis, steam and other agents. The refining process removes all of the aroma and flavour substances out of olive including its natural antioxidants. Artificial antioxidants such as butylated hydroxyanisole (BHA) and the related compound butylated hydroxytoluene (BHT) need to be added back to give the refined olive oil a reasonable shelf life. As such, unlike extra virgin olive oil, „Pure‟ and „Lite‟ olive oil lack the aroma, flavour and any form of bitterness and pepperyness. In fact the word „light‟ only refers to the light colour, aroma and flavour of these oils.
So what is pomace olive oil?
Pomace olive oil is the cheapest grade of olive oil available on the market and is the only olive oil that is extracted using solvents. The production of extra virgin olive oil results in the production of a waste material called pomace which consists of the mashed up skins, seeds and pulp of the olive minus most of the water and oil which has been removed. Due to extraction inefficiencies, the pomace contains small, albeit commercially viable amounts of olive oil. The pomace is dried by heating and the remnant oil is dissolved by using the solvent hexane. The solvent is boiled off (and re-used) to leave a crude oil called pomace oil. This oil is then refined using the same process used to produce pure and light oils. The result? A bland characterless olive oil that is low in antioxidants . The positives? Pomace is notoriously difficult to compost down so pomace heaps have the potential to contaminate surface and ground water. So processing pomace can have some environmental advantages. The negatives? The initial heating process has the potential to produce carcinogenic substances called PAH‟s which are not completely removed by refining.
Is it true that "light‟ olive oil contains fewer calories than extra virgin oil?
Absolutely not. All olive oils (and indeed all edible oils) have almost identical energy values. The word „light‟ is made in the context of them having light aroma, flavour and colour.
Should I only buy "first cold pressed" oil?
The question is not particularly relevant in light of the way extra virgin olive oil is made today. The vast majority of extra virgin olive oil produced throughout the world is done so without using a traditional olive oil press. Nearly all extra virgin olive oil is made using high speed centrifuges which spin the lighter olive oil away from the other heavier components of the olive such as water and pulp. As such, the term as it was first coined has little relevance today. Don‟t believe me? 90% of mills in Spain use centrifuges and Spain is easily the worlds largest producer (even of oils labeled as being Italian) and a centrifuge can process many times the amount of paste per hour than can a press. Do the math!
Are olive oils made using the traditional method of mat pressing better than those made using the modern centrifugal process?
Absolutely not. Here is one case where the use of „traditional‟ methods do not guarantee the highest quality. Most olive oil experts would agree that the modern continuous system favoured by most of the world's commercial olive producers result in more consistent defect free oils with as good or better aroma and flavour than what would be achieved by pressing with a mat press.
The reason is simple. By their nature, the mats used in traditional presses are absorbent and therefore retain oil after being used. As cleaning the mats to a near new 'spotless' standard is impractical in most larger scale commercial environments, most mats will eventually contain oil that is either rancid or has a fermented taste character. All subsequent oil produced from those same will also display these undesirable taste defects. Having said that some traditional mat producers do maintain impeccable standards, and as such the oils that they produce have pristine flavours. This is usually the case when a producer is using mat press to exclusively process their own olives. Furthermore, the modern centrifugal methods expose the olive paste and oil to less oxygen. This helps preserve the natural healthful antioxidants found in extra virgin olive oil.
For reasons of oil quality, consistency and mill efficiencies, in most of Europe and in the “new world”, the continuous (centrifuge) method of extracting oil has now become standard practice to extract oils that the majority of consumers will eventually use.
But the label says “cold pressed”. Surely this means that the oil has been made with a press?
Despite what the label says, it probably hasn‟t. Most of the world's commercial oils are made with a centrifuge the EV olive oil you purchase is likely to have been made with a centrifuge. While centrifugation is the best way to make high quality healthy olive oil, the widespread acceptance of the term “cold pressed” by the olive oil buying public means that most producers are very reluctant to discard the term in fear of losing sales. In short, removal of the words „cold pressed‟ from an olive oil bottle is (currently) commercial suicide. A number processors are now using the more correct term „cold extracted‟ to reflect the use of modern processing methods. Ok, I know what you are thinking. Commercial production means large scale. Right? Well no. In both the world's largest producer (with over 1,000,000 tonnes) and Australia (12,000 tonnes) and the US (1,000 tonnes), centrifuges dominate. Over 80% of processing plants in Spain comprise modern 2 phase centrifuges. Even higher in Australia and the US. Yes, Italy is still has a large number of presses but the volumes of oil made from them are very small and they are rarely found outside Italy (or indeed the region where they are made). It‟s almost certain that any Italian olive oil you can purchase in a supermarket is extracted using a centrifuge.
Aren't extra virgin olive oils supposed to be good for my health?
Most extra virgin olive oils naturally contain higher levels of monounsaturated fats and antioxidants such as polyphenols and tocopherol. They also naturally contain plant sterols which are thought to lower cholesterol levels. All these attributes are sought after by the health conscious.
Does centrifugation produce oils that are less beneficial to your health?
No. Quite the contrary. The process of centrifugation is by nature, a rapid and enclosed process which protects the oil from oxygen during the separation process. This means that the naturally occurring antioxidants in the oil are conserved and end up in the olive oil bottle. No rocket science here. If you expose the health giving antioxidants in olive oil to oxygen before they are bottled, i.e. during their making, then they by definition are used up. Better to have them in the bottle so they can help you stay healthy.
Does the term extra virgin necessarily imply that it is an outstanding oil?
You may find this surprising but the answer is no. Throughout the world, the term extra virgin implies that the oil is 100% made from olives, is free of unpleasant flavours and has some degree of fruitiness. That is, the label 'extra virgin' is simply a reasonable guarantee that the oils will add something positive to your food. Obviously within this broad specification there exist rather bland extra virgin oils right through to very complex oils with outstanding aroma and flavour.
Some producers state that their oils are robust or mild or fruity. What does this mean?
They are referring to the style of oil that is in the bottle. Robust oils, have strong bitterness and/or pungency (pepper), and as they are usually made from greener olives, typically display herbaceous aromas and flavours. Mild oils on the other hand by definition have low bitterness and pungency.
Mild oils are best used on delicately flavoured foods such as on white fish and mayonnaise, while robust oils better complement strongly flavoured foods such as roast meats and flavoursome soups. When it comes to bread dipping, either can be used, but most people have a personal preference for one style over another.
The term 'fruity' is more of a marketing rather than style term. That is, an oil can be fruity, but represent either a mild, medium or robust style.
What is the significance of a high monounsaturated fat level in olive oil?
Firstly, olive oils are typified by their high level of monounsaturated fats compared with nearly all other edible oils. Monounsaturates are preferred by the health conscious. Oils high in monounsaturates are also more resistant to oxidation and as such have a longer shelf lives. Incidentally, the major monounsaturated fat in olive oils is oleic acid. Extra virgin olive oils contain between 65% and 85% oleic acid. As a result of selective breeding, some sunflower and canola oils also contain high levels of oleic acid. But these have no aroma, flavour or health giving antioxidants as they are refined oils. EV olive oil is the only high monounsaturated oil that makes your food taste better.
Extra virgin olive oil contains less omega three fats than say flaxseed oil. Is this true?
Yes it is, but….. omega three fatty acids are in the family of polyunsaturated fats. These fats oxidise very rapidly, so oils high in these fats tend to have very short shelf lives unless they are protected with artificial preservatives such as BHA and BHT. Also being refined seed oils they completely lack the aroma, flavour or health giving properties that arise from the polyphenols that are naturally found in extra virgin olive oil.
Does the colour of the olive oil say anything about its quality?
Not quality, but it can tell you other things. The colour of an olive oil is related to the amount of chlorophyll it contains. Olives are picked early in the season tend to make green coloured oil as they contain higher levels of chlorophyll. Olives harvested late in the season will typically produce more golden coloured oils due to a higher level of natural occurring levels of carotene like substances. Both oils may be technically equivalent in quality but very different in style. There are also many examples of green coloured oils that taste remarkably ripe, and golden oils that have strong grassy herbal characters. To make matters more complex, many strongly green coloured oils will turn a more golden colour when stored. So don‟t place too much emphasis on colour. Incidentally if you purchase a very green looking oil make sure that it is stored in a dark bottle in a dark place. The stuff that makes it green (chlorophyll) helps start the reaction that makes oils rancid, but only in the presence of light.
Some labels make a point of saying that the olive oil was made within a short period of time after harvesting. Why would this be important?
One of the most critical factors in making high quality olive oil is the time that elapses between harvesting the olive and extracting its oil. The greater the elapsed time, the greater the probability that the resultant oil will have an off flavour. The defects that can arise from delays in harvesting are called fusty, musty, and winey. Ideally, olives should be processed into oil within 24 hours after harvesting.
Olive oils are packaged in different coloured bottles. Does this make a difference?
A big difference. Light is the enemy of olive oil as it is one of the factors which causes rancidity. You should always purchase oils stored in dark opaque glass. Some producers package their oils in clear bottles. This is mainly to attract the buyer. Storing olive oil in clear bottles is detrimental to its quality.
Some olive oils are cloudy. Are these better for me?
The cloudiness arises from small particles of olive that remain after processing. These particles do not convey any additional health benefits or flavour. Cloudy olive oils generally have shorter shelf lives and if the cloudiness settles into the base of the bottle, the resultant sediment can cause off characters to be formed.
Incidentally, most clear oils get that way not by being filtered but simply by allowing the oil to settle naturally in tank under the force of gravity. The clear oil is removed from the sediment at the bottom of the tank and is bottled.
How are flavoured olive oils made?
The way they are made in part depends on the flavour type. The most commonly encountered flavoured olive oils are of the citrus type. These can be made either by 1) adding citrus skins to the olives and crushing them together before extracting the oil, 2) by adding skins to the oil after it has been extracted and letting the citrus flavours infuse out into the oil or 3) by adding food grade citrus oils to the olive oil. The first method is called agramato and makes the best oils as they have natural flavours that typically meld well with the flavour of the olive oil base. Most other types of flavoured oils are made by the infusion process.
Occasionally one sees bottles of olive oil with fresh herbs or garlic in them. These should not be available for sale as consumption of these oils could cause botulism (which can be fatal). The use of dried herbs and garlic is an acceptable practice.
What do I look for in a retailer of extra virgin olive oil?
A good retailer knows the oils he or she stocks, and most importantly sees the use of olive oil as an important part of the entire European culinary experience. Good merchants should be able to advise you on the right style of extra virgin olive oil for your intended use, can recommend good examples of that style, have a high turnover, and ideally only stock new seasons oils.
There are so many extra virgin olive oils to choose from. What do I look for?
First and foremost, consider purchasing an extra virgin olive oil that is useful for the culinary purposes you have in mind.
Extra virgin olive oils can have intense flavours and can also be strongly bitter and pungent. Many 'early harvest' styles fit in this category. Others can be very fruity with only hints of bitterness and pepper, while 'late harvest' styles are typically mild with very ripe fruity flavours.
As a general rule, oils with a strong flavour suit strongly flavoured dishes, and mild oils are used in dishes which are delicately flavoured. This guide provides descriptions that emphasise oil style, so it should be of help when making your purchase decision. Alternatively, ask your merchant or the producer.
Secondly, choose to buy the current season oils as these will be the freshest. Not all will have the year of harvest clearly marked. However, reputable producers and retailers will direct you to their new season oils.
Finally if in any doubt, either consult this guide or speak to your merchant. Better still, why not contact the oil maker. Most are more than happy to help and answer questions regarding their oils, and olive oil in general.
What is the difference between early and late harvest oils?
They are simply different styles of olive oil. As their name suggests, early harvest oils are made from olives picked earlier in the season. As they are made from greener olives, early harvest styles are usually more grassy/herbaceous in aroma and flavour and have higher levels of bitterness and pepperyness.
Late harvest styles are usually milder oils and display riper fruit flavours. Due to their different taste properties the two styles of oil are used in different ways in the kitchen.
Why are the supermarket European extra virgin olive oils generally cheaper than most Australian and American oils?
Two reasons. Firstly, the European industry has greater economies of scale, but also the production of olive oil in Europe is subsidised by the European Union. Australian and American producers do not receive direct financial assistance from their government to produce olive oil.
The term extra virgin also only implies that the oil is free of defects and has an olive like fruitiness. So within this broad specification there is room for a wide range of qualities. So, a typical imported extra virgin oil bought in a supermarket costing $6 will in all probability be lower in quality than a top $25 Australian or Californian olive oil. This is despite the fact that they both have legitimate extra virgin status.
The bottom line is simple. Just don't assume that all olive oils labeled Extra Virgin are equally good. They aren't. Taste for yourself and focus on freshness and flavour. Then make up your own mind.
What does Free Fatty Acidity (FFA) mean? Is it good or bad?
Free fatty acidity is chemical parameter of the oil which is a very broad indicator of its quality, or at least how sound the olives were and how carefully the olive were processed. For extra virgin olive oils, it ranges from 0 to 0.8%, with the lower the percentage the better. The average FFA of Australian oils in 2008 was around 0.25%, with very few even being over 0.5%.
From a practical point of view, oils with lower FFA's begin to smoke at a higher temperature when heated. This property makes them a little more versatile in the kitchen. Oils with high free fatty acidity also tend to go rancid more rapidly. However, regardless of the acidity of the oil, it can‟t be tasted as the acids in olive oil are very weak acids.
How do I interpret the "best by" date on Australian and European oils?
Australian olive oil producers are now obliged to put a 'best by' date on their olive oils. However, it is left up to the discretion of the producer to specify the date (except where they are participants in the voluntary industry code of practice – see below). Their decision is usually based on historical knowledge of the longevity of oils, as well as on reasonable commercial considerations. It is far better to select oils that clearly state the year, and preferably month, of production. Provided the oil has been properly stored, it should be more than fit for its intended use for at least 12 months.
Incidentally, as European oils are bound the conventions of the International Olive Oil Council, they have different rules regarding 'best by' dates. These oils display 'best by' dates which are a maximum of two years after the date that the oil was packed – not made. Remember, this may or may not mean that the oil was extracted from the olive two years before the 'best by' date, as the oil may have been in tank for some years before it was bottled.
In 2008 the Australian industry introduced a voluntary code of practice whereby oil producers who subscribe to the code base the „best by‟ date on an objective laboratory measure called the rancimat test. The results of this test allows producers to obtain an estimate the lifespan of the oil and advise consumers appropriately. Compare this to the arbitrary nature of the European system!
How can Australian and American oils be as good as the European ones given that the European producers have hundreds of years of experience on their side?
This is an old chestnut. Not many people are aware that the continuous method of olive oil extraction used to produce the vast majority of the world's olive oil today has only been in widespread use since the early 1970's. Furthermore, the new and favoured 'two phase' technology has only been commercially available since 1992. As such, the experience gap between European and other new world producers is not as wide as some would think. Furthermore, the extraction of oil from olives is a relatively straightforward process involving only a couple of critical steps. These are very well known and understood. Most, if not all new world olive oil producers know that if you use undamaged olives, process them quickly after picking, employ the services of a spotlessly clean mill, and don't strive for excessive extraction then sound quality olive oil will result.
Try as many examples of each as you can, preferably without knowing what you are tasting. You can then make up your own mind about the relative qualities of New World and European oils.
Where is the best place to store the extra virgin olive oil?
A general principle applies here. Both light and heat are the enemies of olive oil. As such, olive oils should be stored in a cool dark place. Most also refrigerate well. On the other side of the coin, the worst place to store olive oil is on top of the refrigerator or next to the oven where they may become heated, or even worse on a window sill. Olive oils will rapidly become rancid if stored in a warm, well lit environment. Exposure to light also hastens the loss of the health giving vitamin E like compound tocopherol.
Are extra virgin olive oils harmed by refrigerating them?
No. Quite the contrary, refrigeration is a very effective way of prolonging the shelf life of the oil. Some oils may partially solidify due to the oil containing naturally occurring levels of saturated fats and/or waxes. Even if they solidify, they will return to their normal state when they warm to room temperature. The aroma and flavour of the olive oil should not be affected in any way by refrigeration. However storing in a cool dark place is the best place to store olive oil if you frequently use small amounts of olive oil over a long period of time as there is some recent research suggests that constantly thawing oils marginally reduces their shelf life. However it beats storing on a window sill any time!
How long can I expect my extra virgin olive oil to last?
Extra virgin olive oils are best consumed young as it is at this time when their fresh olive like aromas and flavours, and the health giving polyphenols are at their peak. Unlike wine, olive oils do not get better with age, so the closer to their release date that you purchase and use them, the better. However, the higher levels of natural antioxidants and the higher proportion of monounsaturated fats generally found in extra virgin olive oil mean that they generally remain fresher longer than other edible oils.
Mild styles of oil contain lower levels of polyphenols so they tend to have shorter shelf lives. However as a guide, provided they are stored properly, the majority of current season extra virgin olive oils will retain good flavour, aroma and freshness for at least 12 months.
Can I use extra virgin olive oils for frying?
Yes, but to be honest, refined olive oils (that is those labeled as 'Pure' or 'Light') are probably a more cost effective alternative when more than shallow frying. Refined olive oils also begin to smoke at a higher temperature than most extra virgin olive oils, making them more suited to deep frying. However, extra virgin olive oils are a far better alternative when shallow frying.
It is commonly thought that extra virgin olive oil smokes at a low temperature. However, it is a fact that the lower the free fatty acidity (FFA) i.e. better oils, the higher the temperature at which the oil will begin to smoke. Therefore if you purchase high quality oil with an FFA less than 0.2%, then it will start to smoke at a temperature around 20C higher than your average supermarket EV imported from the EU. That‟s a lot in culinary terms.
Can I reuse olive oil?
Yes, extra virgin olive oils can be reused a few times. However, keep in mind that each time an oil is heated and cooled it will lose some of its aroma, flavour, freshness and health giving polyphenols and tocopherol. Recent research has also shown that olive oils heated by microwaving retain their natural polyphenols to a much greater extent compared with traditional heating methods. However, recent research has shown that the important anti-oxidant called oleocanthal loses its anti-inflammatory activity under even mild short term heating.
Do trans fats form in olive oil when it is heated?
No they don‟t. Trans fats form when any edible oil is subjected to an industrial process called hydrogenation designed to turn liquid oil into an edible fat that is solid at room temperature – that is margarine. The hydrogenation process involves heating up oil under extreme pressure and then bubbling hydrogen gas through it in the presence of a Palladium metal catalyst. For trans fats to form all of these conditions must be in place – heat and pressure and hydrogen gas and an appropriate catalyst. It just can‟t happen in your kitchen. The vast majority of trans-fats in the average persons diet arise from fast foods, cheap margarines, or more commonly commercial baked products and crackers.
A Great Article addressing the on-going debate about the relative health benefits of Coconut Oil compared to Extra Virgin Olive Oil:
And here's another one, too:
Great sources of information on many aspects of Olive Oil: