What Is Extra Virgin Olive Oil?

Open up a recipe book, or turn on a television cooking show, and you’re likely to hear the words “extra virgin olive oil” more than a handful of times.

Olive oil is a universal cooking ingredient — used on its own for flavoring, or as a medium for cooking. Outside the kitchen, olive oil has as many uses as it does inside — it has been used to unstick zippers, polish furniture, and even as a shaving lubricant. This remarkable substance has been around since before 4000 BCE, and olive trees have been cultivated as far back as the 3rd millenium.

What is “extra virgin” olive oil? Why do cooks and recipes always call for this particular substance, and what does “extra virgin” mean?

Production of Olive Oil

To understand the “virgin” designation, you must understand the production of olive oil.

Olive oil is produced by grinding olives and extracting the oil, either by mechanical or chemical means. Green olives produce a generally bitter oil, and olives that are too ripeolives make an oil that is rancid, so for good “extra virgin olive oil”, special care is taken by the producer to make sure the olives are perfectly ripened before they are pressed.

First, te well ripened olives are ground into a paste using either traditional millstones or the more modern steel drum.

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Believe it or not, some modern producers of olive oil do still use millstone pressing. If the olives are ground with mill stones, the olive paste is pressed under the stones for 30 minutes or so. A shorter grinding process makes a more raw paste that produces less oil and a rather tasteless oil at that — but a longer process may increase the oxidation of the paste (its exposure to oxygen) and reduce the flavor as well. After grinding, the olive paste is spread on a series of disks or plates, which are then stacked one on top of the other in a column, then placed into the olive press. After pressure is applied onto the column to separate the liquid from the paste, the liquid still has a large water content. Traditionally the oil was seperated from water using a simple gravity method — after all, everyone knows that oil and water don’t mix. To speed up this process, modern presses use a centrifuge. The centrifuge has one exit for the water part of the oil blend, and one specific exit point for the oil.

Olive oil should not contain significant traces of water — any amount of leftover water will accelerate the spoiling of the oil by microorganisms and bacteria. The separation in smaller oil mills is not always perfect, so it is common that a watery deposit can be found at the bottom of small batch oil bottles. This is just a fact of the small olive press.

In modern steel drum mills the grinding process takes about 20 minutes. After grinding, the olive paste is stirred for an additional 20-30 minutes in a container where the microscopic oil drops form themselves into even larger “blobs” of oil, naturally seperating it from any water present in the mix. Some presses use a secong centrifuge method as described above, to maintain purity of the oil and drive out any remaining water.

The oil produced by only physical means as described above is called “virgin oil”. The name “Extra virgin olive oil” is virgin olive oil that meets a certain criteria in the industry — specific amounts of high chemical content and other criteria, such as low acidity and very little organic defects. In a way, the name “extra virgin olive oil” is simply a way to describe the very best of the best of olive oil produced by a certain press.

An olive oil that is not “virgin” or “extra virgin” is oil that is filtered to eliminate unwanted solid material. Sometime, the remaining oil paste after pressing still contains oil that cannot be extracted by further pressing — to get to this oil, chemical solvents must be used. Any oil that comes from chemical solvents is not “virgin oil” but referred to as “pomace oil”.

There are other forms of olive oil as well — “lampante oil” is oil that is not suitable for eating, and is pretty much an archaic term. This oil was used for lighting lamps — hence the term “lampante”. You may also find a substance in stores called “olive-pomace oil” — this is extremely low grade olive pomace oil that is combined with a tiny bit of virgin oil to improve taste and quality. This is usually reserved for cooking purposes at some restaurants, and is not suitable for consumption on its own.

When Cooking With Olive Oil, There Are a Few Points to Remember

As with cooking with wine, you do not want to cook with an olive oil that you do not like the taste of. Before cooking with an olive oil, taste a bit of it, and appreciate the flavor. This flavor will be imparted onto the food you’re cooking — you wouldn’t want to degrade the flavor of your food with your cooking oil. An inferior oil will leave a bad heavy aftertaste. If you do the taste test and compare the “pure” to the “extra-virgin” and the you’ll understand the difference.

When cooking with olive oil, save your “extra-virgin” expensive oils for salads, dressings, and vinaigrettes. Extra virgin olive oil tastes great on cooked vegetables or brushed onto fish or meat just before serving. You can also drizzle it over slices of crusty bread or onto open-face sandwiches. Use it on a baked potato or add it to mashed potatoes instead of butter. The point is — don’t cook with your extremely expensive extra virgin olive oils — you will be wasting great tasting oil.

When sauteeing or frying, use either a combination olive oil (like a blend of olive oil and extra virgin olive oil) or a straight “olive oil”. Look at the label to determine which type of oil you’re buying. For deep frying, the olive oil grade known simply as “olive oil” is perfect, because it has a higher smoke point (410º F) than virgin or extra virgin oils.

Olive oil tastes great, has many uses around the home besides the kitchen, and has been used for millenia in almost every culture in the world. Understanding the differences between the varying grades of oils will help you choose what olive oil to buy on your next cooking excursion. Remember that “extra virgin olive oils” are the best olive oils in the world, but may not be the best choice for your recipe — depending on how and what you’re cooking. Bon apetit.