Thursday, March 15, 2007

Olive Oil 101 coursebook w/o addendums w/o specific examples

Click here to see all posts on this blog about olive oil

I look at the history of olive oil unromantically. So, don’t expect stories of Greek gods and goddesses and contests between Apollo and Athena. I honestly don’t care about that very much and I certainly don’t believe that many people think about that when they eat or use olive oil. I care about the history of olive oil as a way to better use and appreciate it and to add to your experience.

Understanding the path the olive tree has taken from country to country in its history has some relevance to enjoying olive oil. In seeing its path, one can see the type of environment the olive tree and its products flourish in and thus guess what countries might know a thing or two about high quality olive oil and what other countries might be able to produce olive oil. Evidence found by archaeologists and paleobotanists of the olive tree itself appears earliest in Asia Minor; pinpointing exactly where is more an invitation for argument than a rational discussion because this evidence is coming from 6000 B.C.E.

What is easier to track is how the olive tree moved and when it was cultivated on purpose—when we domesticated it and turned it from a wild tree giving fruits into a member of our garden of edible plants. 3rd millennium B.C.E. in Crete shows the first evidence of cultivation of Olea Europea. At first, the olive tree moved as foreign occupation of other peoples and lands occurred around the Mediterranean. For example, the Venetians and the Turks invading Crete took the olive tree with them as did the Romans when they occupied Spain. The Phoenicians, who occupied colonies in present-day Lebanon and Palestine cultivated it throughout the southern Mediterranean, from Tunisia and Libya up through Morocco and Algeria. The Greeks, and eventually the Romans, cultivated it throughout the northern Mediterranean. Greece brought the first olive trees to France as a token of peace to Gaul. Modern day (i.e. last few hundred years) propagation of the tree has coincided with travel by the rich and intellectual, by university students, politicians, writers, missionaries, and business people who had money and reason to travel abroad and began to live in new places for extended periods of their lives, bringing the olive tree and its oil into butter consuming cultures.

We know much of the early history because the importance of olive oil was so great that trees and oil pots needed to be counted, thus they were part of the bureaucratic writings discovered in the Mycenaean Linear B tablets. Aristotle brought cultivation of the olive tree to a science, while Sonon (639-559 B.C.E.) put into place the first laws in regard to olive trees, stating that no more than two olive trees could be felled per year in one’s olive grove and sentencing to death anyone who purposely felled a cultivated olive tree. Olive oil was used for consumption, for trade, for cleanliness, for sports, for perfumes, and for beauty. The importance of it by religions, both pagan and Christian, can not be minimalized, with its use to anoint for many rituals, including burials. Medicinally, sixty uses of it are mentioned in the Hippokratic code, including contraception, gynecology, and dermatology. “many people outside of olive oil growing regions never saw olive oil unless it was bought from the druggist for softening earwax and other medical uses.” (California Olive Oil News)

“The facts about the nutritional properties of olive oil remain undisputed. It has been

scientifically proven that extensive consumption of olive oil reduces incidences of coronary and cardiovascular disease. It is also widely believed that the antioxidant substances such as vitamins E and K and polyphenols found in olive oil provide a defence mechanism that delays ageing and prevents carcinogenesis, atherosclerosis, liver disorders and inflammations and is well tolerated by the stomach, has a beneficial effect on gastritis and ulcers. Used as a te a, the olive leaves have a relaxing effect. As a cholagogue, it activates the secretion of pancreatic hormones and bile much more naturally than prescribed drugs, which lowers the incidence of cholelithiasis. It has a positive effect on constipation, beneficial effect on the brain and nervous system and its easy digestion promotes the overall absorption of nutrients and mineral salts.” (ELEA: Producing and Consuming Olive Oil, UN conference report, 1999)

But the history of the tree itself is perhaps less important to us culinarily then the history of agriculture and irrigation and proper methods of storage. As we began to take control of more of the 16 factors that determine the taste of an oil, we started to produce better olive oil.

Gross Simplification (though true) of How Olive Oil is Made

  1. Plant or find a tree

  2. Let an olive grow

  3. Pick the olive

  4. Remove the oil from the olive

  5. Tweak the oil (blend, filter, decant, flavor, etc.)

  6. Store the oil

If we take a look at how olive oil is made, we can see that as soon as the first olive tree was found, olive oil could be produced. Pluck enough olives, crush them together into a pulp with some rocks, put the pulp in a bowl and wait long enough and voila, oil, water, and solids will separate to a point that the oil can be used. If we wanted to drift to the most traditional olive oil that existed, we probably wouldn’t enjoy it very much with our modern palates. Culinarily, tradition gives way to industrial improvements when those improvements boost flavor.

“The fruit is technically a drupe with three parts; the epidermis (epicarp) which remains green throughout the growth phase then turns purple and brown when ripe, the fleshy part (mesocarp) which contains the oil and the stone or pit (endocarp) which holds the seed.” (COOC)

16 Factors that play a part in the taste of olive oil.

What the land brings to the picture

  1. The Altitude

  2. The Soil

    1. “The amount of water required by a tree is dependent on climate, that is, how hot and dry and windy the growing season days are to cause the plants to transpire and keep themselves from burning up with drought stress. Olives are trees that are quite drought tolerant, in that they will not die if given little water, however if given insufficient water the trees will grow very slowly (taking 30+ years to reach full size instead of 10) and the fruit will be small (only a problem for table fruit). The rooting depth of your soil is the key factor for dry farmed fruit trees. Just because someplace can be dry farmed does not mean that other sites will also work. Success (growth and production of trees) is highly dependent on how much water is stored in the soil. A good rule of thumb is that most loam soils will hold about 2 inches of water per foot of rooting depth. So if you have a hillside location with 2 feet of rooting depth you will have 4 inches of water available for those trees for the whole season. If you have a deep valley soil with 5 + feet of rooting depth you will have 10 + inches of water for the season. If we get 40 inches of rain that means that all the rest ran off. An olive tree in the coastal climate of NE Santa Rosa, will require about 12 to 18 inches of water per season to be as productive as possible, that is growing well and producing large sized table fruit. For oil the trees might get by with only 10 to 16 inches. Little or no supplemental irrigation would be required to get adequate, but not maximum growth and production, if you have a deep soil. In a shallow soil, the trees would just grow very slowly, have severe alternate bearing, the fruit would be small, there might be fruit shrivel, and the fruit if used for oil, could be quite bitter.

      By the way, the amount of water available for the trees is ONLY if you allow no cover crop or weeds to steal the water first. Excellent weed control is extremely important for dry farming any crop. For 4-5 trees put 6 inches wood chips under the trees out to the drip line (or at least a 6 ft. diameter circle) to smother all the weeds and hold as much moisture in as possible”

  3. The Pests

    1. “If you are in an area where there is olive fly, you should pick the olives and destroy them to prevent over-wintering of the fly.”

    2. See note on grubby taste in olives

What the tree brings to the picture

  1. The shape and size of the tree and the amount of trees per acre

    1. “Olive trees are propagated in California several different ways, including budding or grafting onto seedling rootstocks, leafy semi-hardwood stem cuttings, and hardwood cuttings. Less commonly used techniques locally, but somewhat more common world wide include truncheons, removing rooted suckers from the crown of the tree, and ovuli. (much content courtesy Glenn T. McGourty Plant Science Advisor and County Director UCCE Mendocino County)”

    2. “Typically you get more olives as the tree gets older, not bigger olives. Olive size has more to do with crop size, watering, etc. Thinning will get you bigger olives.”

    3. “Growers were also pruning too soon in the life of the tree. Vegetative growth is important early in the life of a tree to give it a good start. Newer recommendations are for no pruning in the first 4 years of the tree's life. Pruning is one of the most costly parts of any fruit tree operation.”

  2. The variety of olive

    1. “Specific types of olives, such as the Tuscan varieties, will have higher polyphenol values. These oils are valuable in that when blended with a low polyphenol oil they will extend the shelf life by preventing rancidity.” (California Olive Oil Council)

    2. “The type of olives used for oil production may contain as much as 20% of their weight in oil. The larger varieties grown for pickling and brining often have as little as 5% oil”

    3. Specifics of this will be discussed when ads and labels are examined

  3. The age of the tree

“Here is a story of reproduction without the birds and the bees. Technically, olive trees are hermaphrodites and bear both perfect flowers (containing both male and female parts) and imperfect flowers ( with only male parts).

“Some olive varieties are capable of self-pollination while others must depend on cross-pollination with different varieties. Farmers will place "pollinator" trees in an orchard to ensure successful pollination and a good crop when the main variety is self-incompatible. Even self-compatible cultivars fruit better with a "foreign" pollinator.

“Like other life which is propagated sexually, an olive tree will have traits common to both the male and female tress which were its progenitors. If it self-pollinates, then the olive seed produced will be similar to the tree it fell off of. Olive pollen can drift in the wind for miles, so if the olive is the result of cross-pollination from a different varietal, the seed will produce a tree with mixed traits. Simply put, the fruit from your seedlings which sprout all over may be different from each other even though they came off the same tree. They should all bear fruit.

“Because of this uncertainty with seedlings, olives are propagated by cloning cuttings from the same tree.”

What the specific year brings

  1. The amount of rainfall

  2. The amount of sunshine

  3. The temperature of the season

  4. The humidity of the season

What the harvester brings

  1. The method of picking

    1. “Olives are picked by hand by rapidly drawing the fingers or a rake along the branches, quickly stripping the fruit off into nets or a bucket or with pneumatic rakes onto nets. The fruit separates where it will. You cannot possibly expect to pick each olive individually to determine where it might separate from the tree.” (COOC)

  2. The time spent off the tree before pressing

  3. The ripeness of the olives

    1. “Most olives picked earlier in the year will have more polyphenols. Olives picked later in the winter have fewer polyphenols and a more mellow taste. Polyphenol concentrations increase with fruit growth until the olives begin to turn purple then begins to decrease. Years ago farmers valued the more mellow taste and tried to wait to pick their olives but risked freezing or loss to the elements. Now the strong earlier harvest taste has become popular.” (COOC)

What the presser brings

  1. The method of removing the oil

    1. “Much is made of how the type of olive oil machinery will affect the flavor of extra virgin oil but in reality if used properly it has only a small influence. Extra virgin olive oil is made the same way with the same machinery in the US as in Italy. Only a tiny percent of the oil sold in the US is made in the US and is mostly artisanal extra virgin oil which is high in phenols.” (COOC)

    2. “Most of the olive oil consumed in the US comes from Spain and Italy, and is usually refined. These mass market oils are generally refined and low in phenols.” (COOC)

    3. “Refining takes olive oil which has already been made but which is old, rancid, was made from diseased olives or has some other sort of defect and makes it palatable. This is done by filtering, charcoal treatment, heating, and chemical treatment to adjust acidity. Refined oils are lower in tyrosol and other phenols. According to Wayne Emmons at Intertech, Extra Virgin Olive oil typically has 50-80 ppm polyphenols while refined oil has only 5 ppm.”

    4. “Polyphenols and other primarily water soluble components make the olive [fruit] bitter. When the oil is separated from the paste, the bitter substances are left behind in the fruit water and pulp.”

    5. There is about 1 tablespoon of olive oil (and about 120 calories) in: 40 small ripe black olives, 20 jumbo ripe black olives, 7 super colossal ripe black olives. 1 liter = 67 tablespoons so 1 liter of olive oil: 2680 small, 1340 jumbo, 469 super colossal. The average tree produces 33 to 44 pounds of olives per year. Olives weigh an average of 3.51 ± 0.49 grams, so an average tree has about 23,880 olives or 8.91 liters for a small bearing tree, 17.82 liters for a jumbo bearing tree, and 50.92 liters for a super colossal bearing tree, with a lot of leeway from tree to tree.

    6. “When oil was primarily produced with hydraulic presses, the pit fragments were important in keeping the olive paste on the mats. Today most large oil producers use centrifugal machinery and the pit provides no particular advantage or disadvantage to the processing.

      There are olive oil companies which pit the olives before extracting the oil. They claim a better tasting oil but in California these oils have not distinguished themselves in blind competitions such as the L.A. county fair.” (COOC)

What the aftermarket brings

  1. The method of storage (before and after bottling)

    1. “As oil sits in storage tanks or the bottle, the polyphenols will slowly be oxidized and used up. If you want an oil with more polyphenols, buy one that displays a date guaranteeing that it is fresh and that has been stored properly.”

    2. “Like most fruit, olives have waxes on their epidermis (epicarp) to protect them from insects, desiccation and the elements. These natural waxes are what allow an apple to be shined. If an oil is sent to a cold climate or will be used in a product like salad dressing where it will be stored in the refrigerator, it is often "winterized". The oil is chilled and filtered to remove the waxes and stearates. A standard test to determine if olive oil has been sufficiently winterized is to put it in an ice water bath (32 degree F) for 5 hours. No clouding or crystals should occur. Oil which has not been winterized will clump and form needle-like crystals at refrigerator temperatures as the longer chain fats and waxes in the oil congeal, but the oil will not usually harden completely unless chilled further. Some olive varieties form waxes which produce long thin crystals, others form waxes which congeal into rosettes, slimy clumps, clouds, a swirl of egg white like material, or white sediment which the consumer may fear represents spoilage. These visual imperfections may form outside the refrigerator during the winter when oil is exposed to cold temperatures during transport. Chilling or freezing olive oil does no harm and the oil will return to its normal consistency when warmed. The ideal temperature to store olive oil to reduce oxidation but to avoid clouding is around 50 degrees F.”

    3. “It is a source of great irritation to the U.S. olive oil industry that our government does not have much at all in the way of labeling laws concerning olive oil. U.S. producers have come up with our own label - The COOC seal; which follows international olive oil council grading guidelines. Producers are encouraged to also date their oil, although few do and there is no standard dating code. Look on the label for a date. Remember that most olives are picked in the late fall or winter and are sold the next year, so 2002 oil will be the freshest available until early 2004 when 2003 oil will come on the market.

      Shelf life is very variable, depending on the olive variety, ripeness when pressed, care in processing, filtering, etc. It also depends on storage after it has left the producer, something they have no control of, so it is hard to "guarantee" a certain lifespan.

      Lifespan can be as little as 3 months for an unfiltered late harvest olive bottled in clear glass and sold off a supermarket shelf above hot deli foods which is then stored by the consumer in bright light on a hot stovetop with the cap unscrewed. It can be as much as 3-4 years for an early harvest, high polyphenol containing olive variety which has been filtered then packaged in a well sealed tin or dark bottle then stored in a cool dark place by the grocer and consumer.” (COOC)

  2. The age of the oil

    1. “A two year old olive oil may taste rancid to some while others don't mind it. Most people would be put off by the taste of any vegetable oil more than 4-5 years old. Rancid oil has fewer antioxidants but is not poisonous. A good percentage of the world's population routinely eat rancid oil because of lack of proper storage conditions and some actually prefer the taste. In historical times olives which had dropped to the ground or which may have spoiled were made into olive oil which was stored in open-mouthed earthenware vats. Practices like these encouraged rancidity. People have come to expect non-rancid oil in the past 50 years because of chemical refining and better production and storage methods.” (COOC)

Let’s talk labels. We’re going to examine 2 ads and 2 labels, identifying the key points and how they relate to the 16 factors. This is where discussion of a few examples of specific varieties will occur, as well as introduction of PDO and PGI designations.


“Oils labeled as "lite" or "light" refer to flavor, not caloric content, as all vegetable oils have the same amount of calories. Theoretically "light" could refer to an excellent extra virgin oil made from olives picked late in the year but usually it signifies a flavorless low quality (refined) oil from Italy or Spain.” (COOC)


If you want an oil high in polyphenols, pick one that is guaranteed to be extra virgin (has the COOC seal if produced in the US), is from the current harvest season and that has been properly stored. Some varieties have high polyphenols; Frantoio, Lucca, etc.

Cooking and Uses


“You could bake with just about any olive oil. Use a mellow oil for a sweeter taste or try a pungent Tuscan style oil for a bread with more of an Italian character.” (COOC)


“Olive oil is a great oil for cooking. Strong flavored olive oils can be used for frying fish or other strong flavored ingredients. A mellow late harvest Mission variety oil could be used in baking a cake. Olive oil has a high smoke point, 410 degrees F, and doesn't degrade as quickly as many other oils do with repeated high heating. Use a variety of healthy vegetable oils when preparing food and incorporate a good extra virgin olive oil when you want its health benefits and wonderful Mediterranean flavor…. Polyphenols are stubborn substances which do not degrade easily with heat. You cannot refine oil by heating on the stove. ” (Charles Quest-Ritson)

“The conventional wisdom is that soft, gentle oils are best light-flavored foods because stronger flavors can overwhelm the taste of the oil so that only its texture remains perceptible.” “ (Charles Quest-Ritson)


The major tastes of olive oil

“The delicate flavor of quality extra virgin olive oil is related to the presence of a large number of chemical compounds. These flavor compounds comprise aliphatic and aromatic hydrocarbons, aliphatic and triterpenic alcohols, aldehydes, ketones, esters, furan and thiophene derivatives. Over 100 such compounds have been identified which, as a whole, contribute to the distinctive organoleptic characteristics which make extra virgin olive oil so select. These aroma compounds form part of the unsaponifiable fraction, which makes up about 1% of the oil. These tastes and fragrances derive from compounds like hexanal (green, grassy), trans-2-hexenal (green, bitter), 1-hexanol and 3-methylbutan-1-ol, which are the major volatile compounds of olive oil. Many of these flavor compounds decompose if temperatures during milling exceed 30°C. Thus the importance of “cold pressing”. “ (COOC)

“Many studies have been done to try to predict a flavor profile based on an oil's chemistry. In "The Handbook of Olive Oil" by Harwood and Arapicio they cite studies done by the authors which show that aglycons are responsible for the bitter and pungent sensory attribute, as well as tyrosol and possibly alpha-tocopherol. The phenols are related to astringent attributes. It is probably the combination of bitterness and astringency that causes the cough.” (COOC)

The largest determinants of olive oil flavor are variety of olive and time of harvest.

Positive aspects


  1. fresh tasting, like fruits or vegetables. Lively & attractive


  1. Usually felt on the back of the tongue and the throat.

  2. “hydroxytyrosol and tyrosol are some of the many phenol compounds in olive oil that contribute to bitter taste, astringency, and resistance to oxidation.” (COOC)


  1. Hot sensation associated with modern oils pressed from immature olives (may even induce one to cough). Often not sensed immediately, but in the aftertaste of the oil. – “Gary Beauchamp and other chemists published a September 1, 2005 article in Nature which shows that Oleocanthol, the pungent compound in some oils which creates a stinging sensation in the throat, has similar properties to anti-inflammatory compounds such as ibuprofen.” (COOC)

Tactile sensations (e.g. throat-catching, astringent, metallic, peppery)

Simple taste sensations (sweet or bitter (don’t really have salty or sour))

More complex positive tastes (grassy [characteristic of young oils made from semimature olives], artichoke, green apple, green banana, tomato, green tea, beans, avocado, guava, cinnamon, pepper, almond [associated with oils made from fully ripe olives], toasted almond, pine nut [most oils acquire a nutty taste as they age], catty, malt, butter

Direct aroma (floral, perfumed, confectionery)

Negative sensations (rancid [result of oxidation. Put some oil in a glass for a week on a sunny windowsill to recognize this], winey/vinegary [caused by anaerobic fermentation of the olives], musty [caused by bacteria and fungi infecting badly stored olives], muddy [oil will turn putrid when the sediment left in it begins to decay], flat [caused by heating the paste during processing], dirty [oil taken from olives that have fallen to the ground], metallic [from contact with metals], grubby [a dirtiness associated with olives infested with olive-fly larvae, a common failing in badly managed groves]) (from Charles Quest-Ritson)

Exercise for the class: Associate defects in the olive oil to the factors among the 16 that causes them.