Chemistry of Extra Virgin Olive Oil

Free Fatty Acids – FFA

Indicates the condition of the olives at time of crush! Healthy fruit, processed immediately should produce oil with low FFA!
The lower, the better! An oil with a low (FFA) will have a higher smoke point than an oil with a higher FFA.
The IOC requires that this number be below 0.8 in order for an olive oil to be considered Extra Virgin grade.

High FFA values generally indicate that the olives were overripe and lacking the health benefits of an appropriately harvested olive.

Peroxide Value – PV

This number must be equal to or less than 20. This is the primary measurement of the rancidity of a particular extra virgin olive oil. Peroxide value is affected by procedures used in processing and storing of the oil. Peroxide is responsible for color and aroma changes as the oil oxidizes.

Oleic Acid

The Short
Oleic Acid- A higher level is better! Oleic acid is responsible for some of the health benefits of EVOO, and its high resistance to free radicals helps to slow down the spread of damaging chemical chain-reactions. Because of its high degree of resistance to attack by oxygen free radicals, higher levels of oleic acid in an olive oil help keep it fresher for longer, by preventing the formation of peroxidized (rancid) fats.
The Long
Our bodies absorb any peroxidized fats that we consume and incorporate them into our cells. Oleic acid’s superior resistance to free radical attacks protects our cell membranes, proteins, and DNA from being damaged, as it protects the oil from spoiling.

Substituting oleic acid for saturated fatty acids in animal fats improves cholesterol balance, and research also suggests that oleic acid may have more specific health benefits, such as the ability to help regulate healthy blood pressure by altering cellular signaling. For these and other reasons, the US FDA has approved the health claim that “Limited and not conclusive scientific evidence suggests that eating about 2 tablespoons (23 grams) of olive oil daily may reduce the risk of coronary heart disease due to the monounsaturated fat in olive oil.”


The Short
Phenols are antioxidant like substances that are naturally occurring in Extra Virgin Olive Oils. Phenols extend the shelf-life of extra virgin olive oil & also determine the “style” in terms of bitterness and pungency. Generally, when an oil has a high phenol count (presented in parts per million), it will have more “pepper” or more “bitterness” and we’ll refer to it as ‘more robust’.
The Long
Many consider phenols to be free-radical “scavengers”. Studies show a dose-dependent & significant effect of olive oil Phenol consumption (for 3 weeks) on appropriate markers of LDL peroxidation and the EFSA (European Food Safety Authority) states that “Consumption of olive oil phenols contributes to the protection of blood lipids from oxidative damage.”
Alpha-tocopherols are Pro-Vitamin E compounds that are essential in the control of LDL that generates cholesterol.

There are typically more than 20 different biophenols in extra virgin olive oil. The prevalent classes of hydrophilic phenols found in EVOO are phenolic alcohols and acids (i.e. Hydroxytyrosol and vanillic acid), flavonoids (i.e. luteonin), lignans (i.e. pinoresinol) and secoiridoids. Among these substances the last two classes include the most concentrate phenols of EVOO. Secoiridoids, like aglycone derivatives of oleuropein, demethyloleuropein and ligstroside, are present in olive fruit as most abundant EVOO phenolic antioxidants. Several important biological properties (antioxidant, anti-inflammatory, chemopreventive and anti-cancer) and the characteristic pungent and bitter tasty properties have been attributed to EVOO phenols.

How Phenols Are Measured
As science has developed, we have learned that a significant amount of health attributes related to extra virgin olive oil are not only linked to its profile rich in monounsaturated fatty acids but also to its biophenol content. In the early days, total biophenol content was simply measured by measuring the reaction of this complex group of substances with a colorant (Folin-Ciocalteau).
The darker the blue colour developed from the reaction, the higher the level of biophenols. The actual level of biophenols was determined by a comparative scale measuring how much colour was developed by known quantities of a standard phenol (either caffeic acid or garlic acid). Even when this method provided a reasonable indication, it was far from perfect as all different phenols react to the colorant in different ways. Furthermore, it did not tell us anything about the different groups of biophenols. As we know now, some of those biophenols have very specific health and sensory properties (i.e. Oleocanthal, which has important antinflammatory action and it is responsible for the pungent feeling on the back of the throat).

Even when there are no limit for polyphenols in international standards, they are very effective antioxidants in olive oil and contribute significantly to oxidative stability, shelf life and health claims. Given the growing importance of these antioxidants, a new and more precise measuring method has been developed. This method utilises High Performance Liquid Chromatography (HPLC). High Performance Liquid Chromatography (HPLC) is a form of column chromatography that pumps a sample mixture or analyte (in this case EVOO) in a solvent (known as the mobile phase) at high pressure through a column with chromatographic packing material (stationary phase). The sample is carried by a moving carrier gas stream of helium or nitrogen. HPLC has the ability to separate, and identify compounds that are present in any sample that can be dissolved in a liquid in trace concentrations as low as parts per trillion. Sample retention time (the time that it takes for each biophenol to exit the column) will vary depending on the interaction between the stationary phase, the molecules being analyzed, and the solvent, or solvents used. As the sample passes through the column it interacts between the two phases at different rate, primarily due to different polarities in the analytes. Analytes that have the least amount of interaction with the stationary phase or the most amount of interaction with the mobile phase will exit the column faster. A detector at the point of exit determines when and how much of each biophenol is sensed. The total amount of biophenols in this method is determined by adding the individual quantities of each measured biophenol.

DAGs (Diacylglycerols)

The Short
Fresh Olive Oil made from sound fruit should result in a DAG content of 85% or higher whereas the processing of rotten and or fermented olives will produce fresh oil with low DAGs indicating a very short shelf-life. DAGs typically drop between 20-30% per year depending on storage conditions and FFA. They are highly influenced by heat but not light. DAGs are important shelf-life indicators and can be used to determine the shelf life (or lack thereof) of an oil at any time in its life.
The Long
DAGs are always reported & presented in the 1,2 ratio (as a percentage of total DAGs) as the oil ages, the 1,2 DAGs are transformed to 1,3 DAGs. Recent studies show that many grocery store oils fail DAGs (35% is considered falling in the voluntary Australian standard) which shows a high correlation with sensory defects, more so than any other test.

The degradation of DAGs (rate) are highly predictable over time if initial quality (FFA) and storage conditions are known.

(PPP) Pyropheophytin A

The Short
PPP is a method of measuring chlorophyll degredation in olive oil and is a useful metric in determining condition of EVOOs. A freshly crushed EVOO should have a PPP of near zero, the lower the better!
The Long
An oil with an extremely high PPP is a clear indication that “something” is wrong or amiss. Either the oil is severely aged, deodorized, or has had continuous light exposure (clear packaging!) for extended time periods and/or higher than normal storage temperatures.

Soft column refining is generally used to strip out sensory defects and otherwise neutralize some chemical parameters in old oils or oils made from over-ripe and fermented (late season) olives so that they can pass typical authenticity tests, undetected. Remember, a fresh EVOO sihould have a PPP near zero percent yet recent studies show that many grocery store oils fail PPP (17% is considered falling in the voluntary Australian standard). In ideal storage conditions, olive oil should only see a PPP increase of 6-8% per year!

A-Tocopherals (Vitamin E)

A nutrient that the body needs in small amounts to stay healthy and work the way it should. It is fat-soluble (can dissolve in fats and oils) and is found in seeds, nuts, leafy green vegetables, and vegetable oils. Alpha-tocopherol boosts the immune system and helps keep blood clots from forming. It also helps prevent cell damage caused by free radicals (highly reactive chemicals). Alpha-tocopherol is being studied in the prevention and treatment of some types of cancer. It is a type of antioxidant.


Squalene is a natural organic compound that is part of our tissues. It is a polyunsaturated hydrocarbon, its molecular structure resembles that of vitamin E. However Squalene contains four additional groups of isoprenoids, which are very potent natural antioxidants.