Methods of processing olives

According to the International Olive Council, which applies to table olives, there are four main commercial types produced internationally today.

1.Natural Olives

Natural olives, also known as Greek-style olives. These are green, blond, but mainly ripe black olives that are placed directly in brine where they ferment, ripen, and gradually lose their bitterness through a natural process. It takes several months for the olives to be ready for consumption.

2. Treated Olives

Treated olives, known as Spanish-type olives. These are mainly green olives and, to a lesser extent, yellow and black olives, which are initially treated by immersion in a dilute solution of caustic soda (NaOH) to remove their bitterness. The concentration of caustic soda in the solution usually ranges from 1.5-2.5% and depends on the variety, stage of ripeness, temperature, and other technological factors. This is followed by washing with water (2-3 times) to remove any remaining caustic soda, and then the olives are placed in brine for fermentation. The entire blanching and fermentation process is relatively short (2-3 months). It goes without saying that processing olives using this method requires experience and specialized technological knowledge and cannot be carried out by individual producers or at a family level.

3. California Type

A type that was originally developed in California is artificially darkened olives (olives darkened by oxidation). These are usually green or yellow olives, fresh or preserved in brine, which are then subjected to a color oxidation process in caustic soda solutions, gradually changing from green to a uniform black. The final product is preserved only when packaged in hermetically sealed containers (boxes or jars) and after undergoing thermal sterilization. It goes without saying that this commercial type cannot be produced at the level of bitter processing.

4. Dehydrated/Shriveled Olives

A final type of lesser commercial importance is dehydrated and/or shriveled olives, i.e., green, yellow, and mainly black olives, which are usually prepared with dry salt, i.e., coarse-grained salt (30-40%) in layers in tanks or containers. Due to the effect of the salt, the olives lose moisture from their flesh, gradually shrivel and become relatively quick to pickle (1-2 months). Olives of this type are relatively salty and cannot be preserved for long periods of time because they are susceptible to the growth of fungi on the surface or inside the flesh.