* How to know the difference between Extra Virgin Olive Oil, and an imposter. If you retailer/supplier does not have this information available, you might wonder what it is they are trying to sell you.
Crucial Olive Oil Chemistry
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.
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.
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
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).
Test/Score: This test was
developed to measure the degradation of chlorophyll in olive oil. This 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.