The olive is a fleshy drupe that turns its green colour into purple or black when it ripens. It's not sweet but clearly bitter; therefore it can't be eaten immediately after being harvested.

Its bitterness must be totally or partially removed before eating the fruit.

There are over 600 Olive varieties worldwide depending on its features. The most common in Spain are the following:

Manzanilla:

Oval-shaped fruit with a light green colour and slightly white dotted

Average size: 200-280 fruits/kg

Has local varieties known as fina, carrasqueña and serrana.

It's mainly used in the production of green olives (Spanish or Seville style) due to the fineness of its pulp and its exceptional organoleptic characteristics.

Queen olive:

Large plump olives with a thin green epicarp subtly white spotted.

Mainly used in the preparation of green olives (Spanish or Seville style).

Hojiblanca and Cacereña:

This fruit, due to its fibrous nature and texture is mainly used to elaborate ripped or cured olive. They are also marketed as pitted or sliced. Once the stage of ripeness is attained they become dark black.

 

We can classify the table olive according to the stage of ripeness when harvested and the colour of the final product:

Green:

Obtained from fruits harvested during the ripening period, when the olive is firm, and a slight pressure can be done by the fingers. Its colour ranges from green to yellow.

Changing colour:

Obtained from rose-coloured fruits, harvested before the stage of complete ripeness is attained.

Black:

Obtained from fruits which, when not fully ripped, have been darkened by oxidation. This alkaline treatment leaches the bitterness out. Then, the olive is packed in brine and needs sterilisation for optimum storage and preservation.

Natural black :

Obtained from fruits harvested at complete stage of ripeness, with a colour range that goes from reddish black to dark chestnut.

 

The bitterness caused by the glucoside "oleuropein" can be removed in two different ways:

Slow and partial:

The fruit is directly cured in salt, without a previous alkaline treatment, therefore, it's naturally fermented. This type of preparation is known as "IN BRINE". This is the process used for the black Aragon olive.

Quick and complete:

Prior to fermenting and curing the olive in salt, it's soaked in diluted sodium hydroxide) with the subsequent hydrolysis of the glucoside that causes the bitterness. This type of preparation is known as "SEASONED".