Frequently Asked Questions about Olive Oil

Olive Oil Frequently Asked Questions

The following information is excerpted from the Olive Oil Source website.

Collapse all | Expand all

Are olives vegetable or fruit?

While fruit can refer to “any product of plant growth useful to humans or animals”, the more specific definition is the “edible part of a plant developed from a flower, with any accessory tissues”. Using this more specific definition all fruits are considered vegetables but not all vegetables are fruit. Olives, plums, tomatoes, artichokes and cucumbers are fruit. Lettuce, potatoes, celery and beets are not reproductive parts of the plant developed from flowers so are considered vegetables.

How many pounds of olives does it take to make one bottle of olive oil?

Olive oil yields vary by variety and harvest conditions. Our average yield is usually about 35 gallons per ton. This equals approx. 7.6 pounds of olives for a 500 ml bottle (about 17 oz).

What is first, cold-pressed?

These are terms that are a bit outdated, but still used to describe olive oils. Years ago the olive oil was actually “pressed” from the paste and the first pressing was said to be the best. Cold-pressed refers to the temperatures during the extraction process. Today the paste is almost always warmed, but if it is heated too high it can destroy some of the taste quality characteristics.

What is “lite” or “light” olive oil?

In the U.S., low-quality, often refined oil is sold with these designations. It refers to the flavor rather than the caloric content. These olive oils are often tasteless, odorless and colorless and are not healthier than other olive oils.

What attributes should I look for when tasting olive oils?

When tasting olive oil, there are several attributes of which you should be aware, and terms that you can use to describe the details of the taste experience. Some attributes are positive while others are negative. Here is an explanation of each:

Positive Attributes in Olive Oil
Three senses are primarily used to identify olive oils: olfactory, which refers to one's sense of smell; gustatory, one's sense of taste; and tactile, perceptible to the sense of touch. The following positive and negative attributes have been defined by the International Olive Oil Council. It should be noted that what might be defined as a negative characteristic may be a treasured attribute in another region or culture.

Fruity - In general, the fruity attribute refers to the fruity characteristics of the olive. Olive fruitiness is generally a result of the degree of ripeness of the olives when they were milled. Unripe fruitiness will tend to have more of a grassy characteristic while ripe fruitiness will tend to be less aggressive. Smelling the olive oil and exhaling through the nose after tasting the oil will help you perceive an oil's fruitiness.

In addition to olive fruitiness, olive oils can also have flavors reminiscent of almond, citrus fruit (lemon, orange, bergamot, mandarin or grapefruit, exotic fruit (pineapple, banana, passion fruit, mango, papaya, etc.), fig leaves, green pepper herbs, olive leaf, pear, pine nuts, soft fruit (blackberries, raspberries, bilberries, blackcurrants and redcurrants), fresh sweet red or green peppers, tomato leaves, natural dried vanilla powder or pods, or shelled walnuts.

Bitter - Bitterness is not detected by about 30% of people. Essentially it causes a reaction transient on the middle palate and on the sides of the tongue. Bitterness is a characteristic taste of oil obtained from green olives or olives turning color.

Pungent - Biting tactile sensation characteristic of oils produced at the start of the crop year, primarily from olives that are still unripe. Pungency starts in the mouth and had a delayed reaction in the throat. Pungency often causes a cough reaction and highly pungent oils are often referred to a "three cough" or "four cough" olive oils.

Note: When evaluating an olive oil, the positive attributes should be not only present but also balanced.

Negative Attributes in Olive Oil
All negative attributes in olive oil come from either defective fruit, or poor processing techniques. Poor techniques can impart additional negative attributes like In addition to these negative attributes, olive oil can also have the following additional negative attributes : metallic (from contact with metals during processing), heated or burnt (from excessive or prolonged heating of the paste), greasy (due to residual petroleum grease on machinery), and earthy (from soiled or unwashed olives).

Fusty - Fustiness is the characteristic flavor of oil obtained from olives stored in piles which have undergone an advanced stage of anaerobic fermentation. In short, fustiness has a olfactory characteristic similar to dirty socks.

Musty-Humid - Mustiness is the characteristic flavor of olive oils obtained from fruit in which large numbers of fungi and yeasts have developed as a result of its being stored in humid conditions for several days. Olives stored in bins can mold very easily and very quickly. Thus, mustiness is a very common defect.

Muddy sediment - This is the characteristic flavor of olive oil recovered from the decanted sediment in vats and underground tanks.

Rancid - Rancid is the flavor which is imparted in an olive oil after it has undergone the process of oxidation. Since prolonged contact with oxygen is the rot cause of oxidation, rancidity is a common defect.

Winey-vinegary - This defect is essentially reminiscent of wine or vinegar. This flavor is mainly due to a process of fermentation in the olives leading to the formation of acetic acid, ethyl acetate and ethanol. This can result from windfall olives that have sat on the ground for some time of from olives that have been stored too long before milling.

The following information is excerpted from the Olive Oil Source. For more information on the health benefits of olive oil visit the "Ask the Dr." page at: The Olive Oil Source.

Is frying with olive oil high in fat?

All foods can be divided into protein, carbohydrate or fat. All oils are fats and they all have the same amount of calories. It doesn't matter whether it is peanut oil, flax seed oil, canola or olive oil. They all have 120 calories per tablespoon. I think your problem is that you are frying your food instead of grilling, sautéing or steaming. Try lightly sautéing or steaming meats or vegetables and then drizzling on a tiny amount of a flavorful olive oil at the table.

Why does olive oil change color?

Olive oil coming out of the press is sometimes a brilliant emerald green. Chlorophyll and carotenoid pigments create the color. Olive oil undergoes many changes after production. Oxidation from the air in the bottle, auto-oxidation and exposure to heat and light drive these changes. Olive oil usually lightens in color as pigments are used up by oxidation. New olive oil is sometimes too harsh to use; producers will wait months before releasing their new crop to smooth out the bitter and harsh flavors. As the oil in the bottle ages it will lighten in color and the flavor can continue to mellow. In 1 to 3 years the olive oil will eventually become rancid. Heat and light speed this up but unless frozen, these changes inevitably occur even in well stored olive oil.

Must I refrigerate olive oil?

I'm sure that would be a surprise to the ancient Greeks and Romans who traded olive oil throughout the Mediterranean before the age of refrigeration. If properly stored out of the sun and heat, olive oil should last 1 or 2 years. Unfiltered olive oil and oil made from certain varietals with fewer polyphenols may only last 6 months. Keeping these in the fridge would extend their life.

California olive oil producers usually store their oil in large tanks and bottle at the last minute to ship to retail locations. This keeps the oil fresher. Better to buy the proper size container so you are using your oil up frequently and buying new.

What is the shelf life for olive oil?

Shelf life is 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. 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 2006 oil will be the freshest until early 2008 when 2007 oil will come on the market.

Lifespan can be as little as 3 months for an unfiltered, late-harvest olive bottled in clear glass and displayed on 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. Olive oil should be consumed within 18 months of production and within 8 to 10 weeks after opened. The fresher the olive oil, the more polyphenols and nutrients present. It's best to buy small quantities of oil  packaged in dark bottles. Store in a cool dark place.

Any vegetable oil will go rancid with time. The olive oil is still edible but will taste bad.

What is the “Mediterranean Diet” and what are its benefits?

Olive oil is an integral part of the "Mediterranean diet," which is associated with sensible tasty portions and slower, more enjoyable eating. People who eat a "Mediterranean diet" have been shown to have a remarkable variety of health benefits. Olive oil can quickly satisfy hunger and lead to fewer total calories ingested at mealtime. Studies suggest that olive oil decreases rates of cardiovascular disease and cancer.

It is unclear if any single component of olive oil is responsible for these health benefits, or if it is a combination of olive oil and a diet high in vegetables, fruit and fish. Extra virgin olive oil is one of the few oils that can be eaten without chemical processing. (Nearly every other vegetable oil has been detoxified and refined with steam and solvents). Fresh pressed olive oil can be eaten immediately and retains the natural flavors, vitamins, minerals, antioxidants, and other healthy products of the ripe olive fruit. Most doctors advocate lowering total fat and calories in your diet, and substituting butter, margarine and tropical oils with healthy fats like olive oil.

Difference between green olive oil and extra virgin olive oil?

Green olive oil is not a term used in the industry other than to describe the color. Extra virgin olive oil is usually green to yellow to almost clear. The color does not affect the flavor, nutrient value or acidity. When oil is tasted during competitions or for grading, a special blue tasting glass is used so the color is not visible. Oil from the same variety of olive pressed in the same week can vary in color due to the ripeness of olive, climate, whether leaves got into the press with the olives, etc. To keep well on the shelf, most olive oils are bottled in a dark colored glass or tin which makes buying an oil of a certain color difficult.

It is a mystery where the people who write these diet books get their ideas about olive oil. They are certainly not reading the copious amount of research which has been done over the past 50 years. I have been answering questions on the internet about olive oil for 7 years and every 6 months there is a new book with new claims. "Eat for Your Blood Type" is a fun fad as long as you understand that the vast majority of the doctors, dieticians, chemists and other scientists out there don't see any evidence for the claims. However putting aside the diet, patients with colitis often benefit from reasonable experimentation with diet so I would encourage you to try eliminating or adding different things, including green colored olive oil.

Does virgin olive oil & extra virgin olive oil have same omega acids?

All olive oils contains both omega-3 and omega-6 fatty acids. Different varieties and growing conditions may produce different ratios of the omega acids. The method of processing does not; so pure, virgin and extra virgin made from the same olives would have the same omega acids.

Olive oil is about 10% linoleic acid (an omega 6 oil) and about 1% linolenic acid (an omega 3 oil), therefore the ratio is 10:1

Can olive oil prevent heart attacks?

A recent study looked at the basic disease process behind heart attacks; the development of blood clots which block the coronary arteries. Several studies in Mediterranean countries have shown that the incidence of heart disease is lower than would be expected by blood cholesterol levels.

Many feel that this discrepancy can be explained by the high amount of olive oil in the diet in this region. But what is it in olive oil which lowers heart attack risk?

Researchers Larsen LF, Jespersen J, and Marckmann P at the Centre for Advanced Food Studies, The Royal Veterinary and Agricultural University, Frederiksberg, Denmark decided to see if it was due to olive oil affecting the blood's basic ability to form clots. Less effective clotting would mean fewer heart attacks.

The researchers compared the effects of virgin olive oil with those of rapeseed and sunflower oils on blood coagulation factor VII, which is a key factor in blood clot formation. In this study eighteen healthy young men consumed diets enriched with olive oil, sunflower oil, or rapeseed oil for a period of 3 weeks. Levels of Factor VII were significantly lower in those who ate olive oil compared to sunflower or rapeseed (canola) oil.

The study's conclusion was that olive oil may lower the pro coagulant tendency of fatty meals which could explain the low incidence of heart attacks in Mediterranean countries.

What makes olives bitter?

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

Can you eat too much olive oil?

Olive oil is not a drug which mitigates poor eating habits and lack of exercise. Drenching a dinner of hamburgers and fries in olive oil would be frowned upon by most nutritionists and doctors.

In some Mediterranean diets fats constitute up to 30-40 percent of calories. If you ate 2200 calories a day (small woman) and 30% was fat, that would be 660 calories from fat. If all of the fat was added in the form of olive oil (none of the foods contained fat to begin with) then you would be adding about 5 tablespoons of olive oil.

This could vary greatly from meal to meal. Say you ate a breakfast of cereal with milk and nuts; you would be consuming a share of your fat for the day in the form of nuts, dairy and grains. For dinner you ate a fatty cut of beef and avocado and tomato: you have eaten your day's complement of fat without ever adding olive oil.

Another day you might have bread for breakfast that was made with olive oil and for dinner you have salad with olive oil dressing and pasta with olive oil on top. All your fat calories came from olive oil that day; 5 tablespoons may be quite reasonable that day.

Is olive oil healthier than margarine?

What is a person to do about conflicting diet advice on avoiding heart disease? Recent studies suggest margarine is worse than animal fats in its artery clogging potential. Doctors have known for some time that saturated fats, the ones that stay solid at room temperature, are not as good for you as unsaturated fats such as vegetable oils.

Americans like spreading solid fats on their toast and bread rather than using liquid oils as the Mediterranean cultures have done with olive oil for centuries. To produce vegetable oils that stay solid at room temperature, the oils must be hydrogenated, a process whereby hydrogen gas is bubbled through the oil, "saturating" it with hydrogen.

Both saturated animal fats (butter) and plant oils (margarine) have been shown to be unhealthy for the heart. The solution? Well, your best bet is to dip or drizzle unsaturated or monosaturated oils like olive oil on your food instead of spreading margarine.

What are the health benefits of antioxidants and polyphenols?

The antioxidant activity of polyphenols has shown promising results with respect to:

Atherosclerosis (Heart Disease) — Oxidized low-density lipoproteins (LDL) contribute to the progression of human atherosclerosis. Antioxidants have been shown to prevent LDL modification. The beneficial effects of a Mediterranean diet may be defined by the unique antioxidant properties of its phenolic compounds.

Antimicrobial Activity — Olive polyphenols have been demonstrated to inhibit or delay the rate of growth bacteria such as Salmonella, Cholera, Staphylococcus, Pseudomonas, and Influenza in vitro. These data suggest a potential role of olive water polyphenol antioxidants in promoting intestinal and respiratory human and animal wellness, and as an antimicrobial food additive in pest management programs.

Cancer — There is a growing body of evidence that reactive oxygen species are involved in the etiology of fat-related neoplasm, especially in patients suffering from predisposing inflammatory conditions where high quantities of reactive oxygen are produced. Recent studies have shown that the abundant phenolic antioxidant fractions of olive oil have a potent inhibitory ability on reactive oxygen species associated with colon and breast pathologies.

Oxidative Stress from Passive Smoking — Recent studies which involve administration of the phenolic fraction from olive water in rats exposed to oxidative stress from secondary smoke, show a dramatic reduction of stress and protective activity by polyphenols in the diet.

Skin Damage and Photoprotection — The skin damage produced by overexposure to sun rays and environmental stress is related to the destructive activity of free oxygen related radicals produced by skin cells. Polyphenolic components of olive oil have been compared to traditional antioxidants, such as tocopherols, used by the cosmetic and pharmaceutical industry to prevent skin damage. Results show polyphenols as having the highest activity as radical scavengers.