Raw olives go through three states of maturity, to be processed into table olives. Green ripe, deep purple and finally black.
The harvesting of the olives depends on the region and the variety. During the process of the ripening stages, changes in texture and firmness occur.
The green ripe olives are in a stage that is most desirable for process of green table olives by any method. When the olives reach the yellowish color, they reach their last stage of size and harvesting time.
In the deep purple stage the olives are still firm. This color is called “turning color” and the olives become softer.
The black ripe olives have reached the maximum levels of oil content and harvesting should be done with caution, because if damaged, the final product turns out of poor quality.
The pigments of the black ripe olive get diffused down to the pit. The best black olives are the ones that are harvested when the pigments are about three quarters through the flesh. They are firm and flavorful.
The right stage of maturity and picking are the two most important factors for the final quality of table olives.
Harvesting by machines, bruise and damage the olives and that results in secondary quality olives. Hand picking by experienced pickers, the use of the right containers and the storage in cool dry places, are requirements for a quality table olive and extra virgin olive oil.
Experiments show that mechanically harvested olives, if they are immersed into light lye solution within 25 minutes of harvesting for about one hour, the bruising almost disappears. Green ripe olives treated this way, are suitable for Spanish style green table olives and not table olives produced by natural fermentation.
Hand harvesting is very costly and in places where large amounts of olive trees come into production, mechanical harvesting should be taken into consideration.
As hand picking is resulting in high quality, olive growers should train their olive trees for easier hand picking by pruning them from the first year of planting them.