An olive tree does not have the same amount of production every year. It happens that one year the harvest is good and the following year there is a pause. This is genetic and lies in the DNA of the tree.
After the harvest the trees are pruned. This is done to keep control of the trees . It is very hard to pick the olives when the tree is too high. It’s also done to prevent the tree from getting sick. Bacteria and other illnesses grow well in dark spaces. So by pruning the tree it gets more light, causing photosynthesis to increase which is better for the production of olives. It also takes care of the stability of the calcium level in the tree, which also advances the maximum production for next year.
The pruned branches are burned. It has been given some thought to use this as fertilizer, but the risk that some branches might hold bacteria is too big and using it as a fertilizer would just bring it back to the trees. Burning it still seems to be the best solution.
The olives are divided into “Extra virgin” and “Virgin olive oil”, which are the best qualities. Then there is the quality that is simply called olive oil and the quality that is called ‘pure olive oil’. This name is very misleading, because there is nothing pure about this oil.
These different groups, also called ‘degrees’ , show the different quality levels of the olive oil. The quality of olive oil is based on the amount of acid. The lower this is, the better the quality of oil. Olive oil is ‘Extra Virgin’ when the level of acid lies between 0.1 and 1% per 100 grams olive oil and this percentage must be obtained naturally. This olive oil is darker and thicker.
In Greece over 75% of the harvest is “Extra Virgin”, which of course is a very high percentage.
The “Virgin olive oil” is natural and has an acid level of no higher then 1.5%.
The ordinary olive oil has been treated to decrease the level of acid, because this oil naturally has less taste and smell. It’s usually very clear and light yellow of colour, therefore it’s often treated with colourants. What happens a lot, especially in other countries like Spain and Italy, is that the lower quality oil is mixed with the “Extra Virgin” quality and is then sold altoghether as quality olive oil.