Producing high quality Extra Virgin olive oil requires the producer to reach perfection in
every stage of the process, as well as be fortunate with Mother Nature. This is often much
more expensive for producers to accomplish which is why some excellent extra virgin olive
oils can be so pricey.

At present over 50% of the olive oil produced in the Mediterranean countries has high
acidity and poor organoleptic characteristics, and is unsuitable for human consumption
unless refined. Extra virgin oil accounts for barely 10% of the oil produced in many of
these countries.

The following factors play a role in the quality of olive oil produced:  

   Health of fruit (degree of pest and disease infestation)
   Method and period of post-harvest fruit storage
   Oil extraction system ( including extraction temperatures)
   Method and period of oil storage prior to packing
   Cultivar of olive (type)
   Climate (latitude of production area)
   Cultural techniques (irrigation, drainage, pesticide residues, etc.)
   Soil type
   Harvesting method
   Maturity of fruit (time of harvesting)
   Method of fruit transport
   Type of packaging
   Period of storage in final pack prior to use  


Any weak link in the chain from the fruit on the tree to the oil in the final retail pack will
impact upon the quality of the oil.  

The above factors affect both the quality and keeping quality of olive oils by altering one
or more of the following chemical components or indices of the oil:  

   Free fatty acidity  (the degree of chemical breakdown of the triacylglycerols)
   Peroxide value  (the degree of peroxidation of the oil)
   Antioxidant content (the content of polyphenols and tocopherols)
   Spectrophotometric constants  (mainly UV extinction coefficient at 270nm)
   Fatty acid profile of triacylglycerols  (content of oleic, palmitic, linoleic, etc.)
   Pigment content  (chlorophylls and carotenoids)
   Aroma compounds  (alcohols, aldehydes, ketones, esters,  phenols, terpenes)
   Mono- and diacylglycerol content  (partially formed triacylglycerols)
   Sterol content  (beta-sitosterol, campesterol, stigmasterol, etc.)