Gino Celletti's 36 Truths

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Extracted with Gino’s blessing from his brilliant, landmark book MONOCULTIVAR OLIVE OIL  ‘The Perfect Olive Oil’

In no particular order except the way our mind works, we will drop these ‘truths’ into the website as often as possible. We cannot express strongly enough how important they are to those of us that want the truth about olive oil.


(FOLLOWING TRUTH #2:  green olives and black olives do not exist)

AND IF OLIVES ARE ALLOWED TO TURN BLACK THEY GET ANGRY. And if they could talk, they’d be swearing.

After 6,000 years we still don’t understand a thing. We recognize the colors of traffic lights, the sea and even politics, but still not olives! Green, iridescent, black? They are just olives! Yes, but we extract 2,678,500 tons of oil per year, and if the olives are green, the oil is good; if they are black, it is not!

Lucius Junius Columella also discovered this, and in his book De Re Rustica he wrote “…As for the olive grove, those olives that you can reach with your hands from the ground or with a ladder, it is best to pick them rather than beat them. And from those that are picked by hand, even better are the ones picked with bare fingers.” Understand? He suggested to even pick with fingers rather than with hand tools or by beating the tree. He understood that black olives that had fallen to the ground were not good. Columella, Catone and Pliny at the tie, all wrote that olive color should be used to classify oil for the “differentiated” supply of the Officers of the Republic of Rome.

OLEUM EX ALBIS ULIVIS                                                       High quality oil from light-green olives

OLEUM VIRIDE                                                                       Oil from olives that are turning

OLEUM MATURUM                                                              Oil from ripe and black olives

OLEUM CADUCAM                                                              Oil from olives harvested from the ground

OLEUM CIBARIUM                                                                Bad oil from parasitized olives, for slaves

The first olive oil was for the consuls and senators, the second for the army commanders, the third for nobles, and so on, finally ending with the slaves. While from one side, this irritates me; from the other, it has my admiration. I do not believe that our current heads of state are  interested in quality olive oil. The best positions, yes, easy women as well, but not great olive oil; nevertheless I know that at least our army receives extra-virgin olive oil. Here’s what I admire:  during that period, they were tyrants, but at least they gave value to their natural resources. And I’ll leave it at that.



We all are born virgins, but olive oil, if it’s born as a ‘virgin’ by law, it may have already had sex for 35% of its life. The EU Regulation EC 640/2008, on a scale of 0 to 10, allows for up to 3.5 defects.



There can only be one “press”, and re-grinding the residue pomace is illegal. Have you ever seen “wine from the first press”? No! And it is the same for olive oil. So why do they continue to say “first-pressing olive oil”?


If there was a first press, there must also be the 2nd press, and then maybe even the 3rd. In actual fact, the 2nd press did exist, but it is now banned, and those who do it risk jail time. So there is just a single press. But why would someone still write on the label that the oil is 1st press? Does it mean that today he is honest, but yesterday a bit less because he was re-milling and falsifying the olive oil to make a few extra bucks? No, I believe it is simply a fear of change, fear of leaving the old road, to begin speaking clearly to consumers. It serves those who do it first. Only after the single press of olives and after the analysis (both instrumental and sensory) can it be decided which of the 3 categories of “virgin” we can apply on the label. Therefore there is no second press! All that exists after the single press is the subsequent treatment of the pomace with solvents. And so in honor of knowledge and understanding, the phrase “first press” must be eliminated.



Bitterness is not a defect, but rather a positive characteristic. Olive oil can be sweet or bitter just as wine can be red or white. If you bite a raw olive, you will feel the bitterness. That is the taste of oleuropein, and it is very good for you. Who would say that red wine is defective just because it has more color than white wine? Bitter olive oil is healthy, and we just need to learn how to pair it with dishes.



Healthy olives produce good, spicy olive oil. Here “good” does not mean ‘pleasing to the palate’, but ‘quality’. Of course, I would like that in the North, as in South and Central Italy, that consumers evolved their idea of “good” to “spicy” olive oil. It is not my pride, but a gift. The equation is simple:  the more an oil stings, the more polyphenols it contains, the more antioxidants and health it provides for all.

In Italy, even eating habits have divided the country in two:  there is the Italy of Pig that stretches from the Alps to the Apennines was started by the Celts who bred pigs and used the pork lard to dress absolutely everything. And it was the Etruscans who perfected the butchering craft with their disciples throughout Umbria and Emilia consolidating their very continental diet. After crossing the Apennines, all the way to Pantelleria, we enter the Italy of Olive Oil where Olea Europe was Queen, and olive oil was used to dress everything. Only in the postwar Italy did southern housewives experiment with margarine and butter, but their sunny side-up eggs are still made with olive oil, and spiciness is a must, and the medical community approves. 



If an olive oil isn’t spicy, it means that it hasn’t come from olives or it has been washed. It’s ether a scam or cheap. Olive oil is spicy because of polyphenols. If it is not spicy (again) either it does not come from olives, or it has been washed of its foul smells, just like a car under the washing machine jets. Wash and grease! But why do they wash olive oil? If you don’t pick green olives from the tree by hand, you save money, but they are then left to collect fermented black olives that have fallen to the ground. While on the ground the olives have picked up stinky molecules that are foreign to olive oil and must be eliminated. Fortunately they dissolve in water vapor and nitrogen, but unfortunately also the polyphenols are water-soluble, and are washed away forever.

And so why do they grease it? As you have already learned, in order to sell a washed virgin oil, some olive oil must be added to restore the minimum healthy amount of polyphenols and Vitamin E. Here is the greasing:  the law requires the addition of olive oil to washed oil in order to “fatten it up” with the lost substances. You should know by ‘you get what you pay for.’



It isn’t like making orange juice. If only it was as simple as the ads make it sound.

Unless we crush the olives, at the right temperature, creating contact between the “inside” and the “outside” of the bubbles, which are made of water and enzymes, we won’t get a single drop of olive oil. We need to “mix” everything together. Now a little bit of olive oil chemistry in layman’s terms.

We have to make the cake.

 It’s just like making a cake with flour, eggs, yeast, raisins and fruit. This is the recipe for panettone, an Italian sweet traditionally eaten at Christmas. Just because we have all the ingredients, it doesn’t mean the cake is ready to be eaten. Likewise, we have 230 substances in bubbles, but not olive oil. As with the cake, the ingredients must be “mixed” together, most especially with the yeast. The “yeast” is outside the bubbles dissolved in the vegetation water that surrounds the cells of the fruit pulp. The yeasts, like those for cake, are a set of enzymes. The first part of the word tells us where the enzyme works, the final “ase” tells us that it is an enzyme. Example:  “polyphenol oxidase” is an enzyme that destroys polyphenols. Our body is full of enzymes and has a temperature of 36.5 Centigrade. Why should you remember this? We’ll come back to it when we talk about the COLD PRESS. With regards to oil, there 5 enzymes:  2 “good” ones that create it, and 3 “bad” ones that destroy it.

Good enzymes

Glycosides attack oleuropein (the bitter substance that fills your mouth if you bite into a fresh olive) and degrade it into demethyloleuropein and ligstroside. They are the oil’s gold, the “polyphenols”, or antioxidants that create the “bitter and spicy” sensation. Lipoxygenase instead degrades linoleic acid, one of olive oil’s 3 fatty acids. They form pleasant aromas, like tomato in the monocultivar Tonta Iblea, artichoke in Frantoio or Bosana, and fresh grass in Coratina.

Bad enzymes

Lipase increases the free acidity in olive oil which, by the way, is a useless figure for determining quality. In EVOO the maximum level is 0.8%. It does have a value however, when combined with the polyphenol level. The acidity in oil can be “corrected” through washing or with the addition of soda and talc. Lipase is located in the pit and so it was thought for a period that by removing the pit it was possible to control the free acidity.

Polyphenol oxidase oxidizes polyphenols. This is the most damaging enzyme. It always wins, but the more polyphenols there are, the longer it takes. Imagine that olive oil with polyphenols lives in a castle guarded by 1000 soldiers (the polyphenols) and that the castle is attacked by 1000 assailants. The assailants remain on the ground with the 1000 soldiers. If we call the attackers “oxygen”, it all becomes clear, and if just one of the attackers is still alive, the castle falls.

Peroxidase oxidizes oil’s fatty acids:  oleic acid, with one unsaturated bond, linoleic acid with two, and linolenic acid with three. They form “peroxide” chains because of the oxygen activity. In the periodic table, O is missing two electrons at the last electron level, so it must therefore steal electrons from wherever it can and “oxydize” everything. If it steals from iron the oxidation is rust, from the tannin of an apple and it turns brown, from butter and it turns yellow, from salami that eventually becomes inedible, and from our skin which ages.

Harvesting the olives:  where the trouble starts

Assuming that the season gave us healthy olives, with no hail, no Bactrocera, no drought or other issues, the harvest is the first point in which human intervention can create trouble. Let’s also assume that the collector picks the olives when they are still green, and just beginning to turn black (invalare); the defect that may result from incorrect storage is FUSTY. If I say to someone who is self-taught that their oil is fusty, they might respond that the oil has not been warmed or held too close to the the fire. Ignorance is bliss. (The direct translation for the Italian word for fusty (riscaldo) is ‘heating’.) Olives are “small factories” where little bits are put together to create olive oil. Every time these bits are fused in the factory, while the olive is still on the tree, heat is released into the environment. This heat is called free energy because it is not recoverable; it is a disordered energy that escapes the systems of physics and thermodynamics, increasing the level of entropy. The olives on the tree, however, remain fresh. When we pick them from the tree, the exothermic synthesis reaction does not end there and heat continues to be emitted. If we put the olives into a bag or sack the heat cannot be dissipated into the environment and remains in the bag. After a couple of hours, if you were to put your hand into the olive bag it would be hot enough to burn your skin. The temperature rises to between 70 and 80C and at this temperature undesired fermentation begins. The result are defects such as “fusty”, with its stink of stale meat. So, just perforated crates, and even those should be filled only to 30%.

At the olive mill:  war with stones, knives and hammers.

The old romantic stone olive mills or modern stainless steel? The second. We want perfect oil, not a museum. Stainless steel does not create the defects like the first. A stone mill (which only a few actually know how to use) mixes air with the oil; in other words oxygen and that means rancid oil. The harvest and the work of an entire year ruined.

Extraction:  from the pressing mats to the decanter

In an old-style olive mill, the olive paste is put onto plastic or hemp disks for a process called straining. Stacked and pressed, they squeeze out oil, which is lapped up by the air and oxygenated, again creating rancidity. While in the modern oil mill, where the crushing is performed by hammers, disks or rotating knives, the process is rapid and without contact with the air. The addition of nitrogen or argon, heavier gases, further removes the risk of oxidation.

Malaxation:  here is where Rome is built

With continuous olive mills, there is no more squeezing:  extraction is done by centrifugal force in a decanter spinning between 2500 and 3800 rpm. By density, the oil splits from the water and the pomace is removed from the center. This three-phase system is good, but if the olive miller wants a perfect oil he will use a two-phase which puts oil on one side and water and pomace on the other. As always, better quality means lower yield. If you get an olive oil from a two-phase mill, even if you are not expert, I guarantee that the oil is excellent. Today then, the research gives us a decanter multifunction that makes excellent olive oil and takes care of the environment. The vegetation waters to be disposed become livestock food. Brilliant!

Malaxation:  time and temperature so as not to burn the pizza

It’s a steel spiral that is rotating inside a heated jacket. The time and temperature must be respected just as if you were cooking pizza; it burns if it stays in too long, or is not cooked if it is taken out too soon. Glycosides and lipoxygenase need between 20 and 30 minutes for the fermentation to be completed; any later and other fermentations start. The temperature must be between 22 and 26C; any lower and the enzymes don’t work; any higher and other enzymes will kick in and destroy what has been done.

In summary, malaxation:

— produces polyphenols and aromas

— aggregates oil droplets into larger drops, but if done for too long or under too high temperature:

* destroys polyphenols, aromas and health benefits

* promotes rancidity

The enemy in the bottle

I have had the occasion of tasting a really wonderful olive oil, just out of the centrifuge, fragrant and spicy, but then sampled that same oil just a few months later to find it already rancid. How can that be? It’s very likely that during one of the crushing phases, oxygen mixed with olive oil creating first a single peroxide and then many, many more. This reaction ends when there is none left “to peroxide”. The phenomenon allows me to show millers, especially older ones, that “cutting” old rancid olive oil with fresh oil just allows the reaction to restart. It is a bit like throwing gasoline on a fire that has just gone out. So even bottling should take place in a modified atmosphere because the space between the olive oil surface and cap provides enough air to be dangerous.




We put food in our mouth and think that it is there where we identify aromas and flavors. We have seen instead that the aromas heated by the mouth are sent retro-nasally to the olfactory bulb filaments. We have to take note of this anatomical and physiological aspect, and correct our lexicon. This is retro-smell because sense of smell is responsible for the detection of those signals. The tastes that can be detected by the tongue and the mouth are sweet, sour, bitter, umami, heat, cold and spicy. Everything else is smell.


Tasting is done in three steps, respecting the order as would an expert taster, just as you do, without thinking, in everyday life, for pleasure or survival. Do you remember when you first met your partner? Here’s what happened:


You saw him for the first time and he was given visual approval. The cerebellum produced hormonal stimuli, and you moved to step 2. Imagine for a moment that instead you had seen an 80-year old with a hip replacement. Would you have wanted to get closer? No!


You are at the olfactory stage and you get closer to him, you smell his cologne and you talk to each other. If that person smelled like hay or sweat, would you have ever spoken?


He passed through stage 2 and you know how it ended. Everything you have done and everything you will do depends on a tasting. Now, however, you’ll be conscious of that.




We have an incorrect understanding of taste and smell physiology. What exists are:  coffee aroma, strawberry aroma and mint aroma, and you should say it in that way. Giving back to the nose the functions that have always been assigned to the mouth, will be taken as intellectual complacency. Many authors have written about the wonders of smell. Patrick Suskind with his 1985 bestseller “The Perfume”, now also a film, writes of Grenouille, an odorless being without form that makes perfume to bend humanity at his feet. Daniel Pennac with his 1993 “Barking Tired”, writes of a dog that accuses the mayor of Nice of keeping the city too clean. Smell has always been interesting because of its long memory. If I ask you which tie you put on a week ago, you won’t remember, but if I ask you about the smell of the Sardinian pork you had on holidays… ah, that one, yes. The wrong image “hurts less” than a bad odor because a smell is forever. Reconsidering a sense of smell may prove essential to leading a safer and more enjoyable life.



Unlike grapes, all olives are green at the beginning, and as they ripen they all become black. Olives, fruit of the Olea Europaea tree are drupes. They have an external peel, the epicarp, covered with wax, the pruine, protecting them from rain, humidity and dew which would dilute the juices inside and also from dryness thus preventing dehydration. Have you seen “frosty” black olives? Beneath the cuticle there’s the pulp, or mesocarp, with vacuoles full of ingredients to make olive oil, and the stone, or endocarp, which contains the seed. Plums, peaches and all fruits with a stone are drupes. Green and black olives in jars at the supermarket are not two different varieties like the green and red grapes, but two different photochemical stages of the olives’ lives. All olives, and I mean ALL olives, start green and all of them later turn black. The point in which the color changes is the basis of the concept of the Perfect Olive Oil, and by that I mean ‘monocultivar olive oil’. The picture on the facing page shows the stages of maturation of a single drupe. The color changes from green to black, through shades of pink, lilac, purple, violet, brown, and finally black, the last phase. When olives are black they are no longer good for producing quality oil, but instead are good for the reproduction of the plant. The olive oil molecules and antioxidants have become nutrients for the trees. If we want olive oil, we crush green olives. If we want a new plant, we let the black olives fall to the ground to be sowed.



The pressing process is warm; so warm in fact that if we were at the seaside we could go for a swim, and if it were any less warm, we couldn’t extract even a single drop of olive oil.


Making oil is like making a cake: we need to mix the ingredients with water and enzymes at the right temperature. In the mill, whether it is the modern “continuous cycle”, or traditional, with stones, presses and straining, the olive paste gets warm, and there would be trouble if it didn’t. The mixing with enzymes is called “malaxation”, and during this phase many biochemical reactions take place. What should be clear is that these reactions should not start beforehand when the olives are still on the tree or in boxes. This would be uncontrolled fermentation. Instead, during malaxation, there is total control! As we said earlier, the enzymes in olive oil are similar to those in our body in that they “work” at temperatures between 22 Centigrade (72 Fahrenheit) and 38 Centigrade (100 Fahrenheit). Have you tried to swim in water at this temperature? You’d probably find it a bit too hot. Clearly, the cold-press does not exist. So why is it called cold pressed? Years ago, with stone mills, some millers even had the habit of pouring hot water into the olive pulp to get as much oil out as possible. No one was that picky, and they certainly didn’t look into the quality of fatty acids that the olive oil contained. During that period it was “anything goes”.



Too many shysters sell ‘genuine’ products, not quality products. The consumer is confused by the two concepts, and is deceived.


We’re used to hearing “this is a genuine wine”, it is “direct from the farmer”, and immediately we think that the wine is also of excellent quality. We buy it, we take it home, and after a few days we find that it has formed a white ring on the neck of the bottle and tastes like vinegar. But it wasn’t like this before, so what happened? It’s called “little flowers”, and is due to the yeast-like Mycoderma in some wines, which develops due to low alcohol content. That wine is certainly genuine, but of very poor quality. The wine’s alcohol content was not sufficient enough to protect it from the bacteria that instead fed upon the extra untransformed sugars, and flowered on the the surface. Olive oil also has infinite examples of “genuine but low quality” and they are all oils with defects like rancid, winey, muddy sediment, etc. also many are the cases of non-genuine oils that the anti-fraud police work to thwart — seed oils that become extra virgin olive oils or vegetable oil that become olive oils. Fraudsters are very inventive.




Healthy olives produce good, spicy olive oil. Here, “good” does not mean pleasing to the palate, but quality. Of course I would like that in the North (of Italy) as in South and Central Italy, that consumers evolved their idea of “good” to “spicy” olive oil. It is not my pride, but a gift. The equation is simple: the more an olive oil stings, the more polyphenols it contains, the more antioxidants and health it provides for all.


We’ve learned so much about olives and olive oil from our friend and colleague Gino Celletti that if we share just some of it with the Olive Oil Jones audience, you folks will most assuredly know more about olive oil than any other olive oil ‘expert’ that you ever come across.  

Dr Celletti has formal academic credentials in industrial chemistry and biological sciences as well as several titles within the pharmaceutical industry, specifically its chemistry and technology sides. He hosts scads of conferences across Europe, is often the Chief Judge at all of the competitions, and is a consultant to millers and growers all over the world.

He was born to Umbrian parents, but was raised in Milano. Dr Celletti launched his war on bad olive oil more than 25 years ago with his website http://www.ginocelletti.com. It is dedicated to the 1584 different varieties (cultivars) of Olea Europaea. 

Copyright © 2018 Gino Celleti