Chemistry of Olive Oil

Extra virgin olive oil decreases in flavor and health benefits over time. Fresh crushed olive oil is like fresh squeezed fruit juice in that it contains the most flavor and nutrients. Old, poorly made and improperly stored extra virgin olive oil yields few if any health benefits and undesirable flavor.
Chemistry of Olive Oil

Becoming intimately familiar with a particular extra virgin olive oil’s flavor characteristics and chemistry, e.g. antioxidant content, oleic acid, FFA, and crush date will help you make an educated decision about which olive oil is right for you.

Crucial Olive Oil Chemistry Definition Key

Oleic Acid: is a monounsaturated omega-9 fatty acid found in olive oil. Olive oil is generally higher in oleic acid than other vegetable fats. The range found in extra virgin olive oil is between 55-85%. Extra virgin olive oil high in oleic acid has greater resistance to oxidation.

FFA: Based on IOOC standards the maximum limit for free fatty acid in extra virgin olive oil is 0.8g per 100g or (.8%). A low FFA is desirable. Free fatty acid speaks to the condition of the fruit at the time of crush. The higher the FFA the greater the indication of poor quality fruit such as damaged, overripe, insect infestation, overheating during production or too much of a delay between harvest and crush.

Peroxide Value: Based on IOOC Standards the maximum peroxide value for extra virgin olive oil is 20. A very low peroxide value is desirable. Unsaturated free fatty acids react with oxygen and form peroxides, which create a series of chain reactions that generate volatile substances responsible for a typical musty/rancid oil smell. These reactions are accelerated by high temperature, light, and oxygen exposure.

Polyphenol Count: Polyphenols are a class of antioxidants found in a variety of foods. Polyphenols such as Oleuropein, Oleocanthal, and hydroxytyrosol impart intensity connected with pepper, bitterness and other desirable flavor characteristics. Recent studies indicate that these potent phenols are responsible for many of the health benefits associated with consuming fresh, high quality extra virgin olive oil. Phenols in olive oil decrease over time or when exposed to heat, oxygen and light. Consuming fresh, well made olive oil with high polyphenol content is crucial when looking to obtain the maximum health benefit commonly associated with consuming extra virgin olive oil.

New Testing Methods Based on Olive Oil Chemistry

DAGs Test/Score: Measures the proportion of two forms of diacylglycerol: 1,2 and 1,3. In oil freshly made from sound olives of good quality, the prevalent form of DAG is the 1,2 form where the fatty acids are bonded to a glycerol molecule in the 1 and 2 positions. The bond on the 2 position is weak and easily broken, leading to the migration of that 2 position fatty acid to the 3 position. This results in the much more stable 1,3 DAG. This makes the ration of 1,2 DAGs to the total DAG’s a good indicator of the quality of the olive fruit and the processing. It is also an indicator of the age of an oil, since the migration from 1,2 to 1,3 DAGs takes place naturally as the oil ages. Warmer storage temperatures, and higher free fatty acid levels will both accelerate this process, but DAGs are not affected by the short exposure to high heat that is characteristic of deodorizing (refining).

PPP Test/Score: This test was developed to measure the degradation of chlorophyll in olive oil. The degradation of chlorophylls to pyropheophytin was found to take place at a predictable pace, making it possible to gain information about the age of an olive oil. The rate at which the degradation occurs can be accelerated by even short periods of high temperatures – such as that which is utilized during the deodorizing or soft column refining process – making it a useful indicator of the presence of deodorized olive oil as well as the age of the oil.