Green olives and black olives are typically washed thoroughly in water to remove oleuropein, a bitter carbohydrate. Sometimes they are also soaked in a solution of food grade sodium hydroxide in order to accelerate the process.
Green olives are allowed to ferment before being packed in a
brine solution. American black (California olives are not fermented,
which is why they taste milder than green olives.
Freshly picked olive fruit is not palatable because it contains phenolic compounds and oleuropein, a glycoside
which makes the fruit too bitter although not unhealthy. (One exception
is the Thassos Olive, which can be eaten fresh.) There are many ways of
processing olives for eating. Traditional methods use the natural
microflora on the fruit and procedures which select for those flora that
the fruit. This fermentation leads to three important outcomes: the
leaching out and breakdown of oleuropein and phenolic compounds; the
creation of lactic acid,
which is a natural preservative; and a complex of flavoursome
fermentation products. The result is a product which will store with or
One basic fermentation method involves a 10% solution of salt
and vinegar in water. The ratio is 10 kg olives to 7 liters of water,
800 g salt and 300 ml of vinegar. Fresh are often sold at markets.
Olives can be used green, ripe green (a yellower shade of green, or
green with hints of colour), through to full purple black ripeness.
Olives should be selected for general good condition and for firmness if
green. The olives are soaked in water to wash, then drained. 7 litres
(7 kg) of room temperature water is added to a container, plus 800 g of
sea salt and one cup (300 g) of white wine or cider vinegar.
Each olive is slit deeply with a small knife; large fruit (e.g., 60
fruit per kg) should be slit in multiple places. After some weeks, the
salinity drops from 10% to around 5 to 6% once the water in the olives
moves into solution and the salt moves into the olives. The olives are
weighed down with an inert object such as a plate so they are fully
immersed and lightly sealed in their container. The gases of
fermentation should be able to escape. It is possible to use a plastic
bag partially filled with water, and lay this over the top as a venting
lid which also provides a good seal. The exclusion of oxygen is helpful,
but not as critical as when fermenting grapes to produce wine. The
olives are edible within 2 weeks to a month, but can be left to cure for
up to three months. They can be tasted at any time because the bitter
compounds are not poisonous, and oleuropein is a useful antioxidant in the human diet.
Curing can be done by several methods: lye-curing,
salt-curing, brine-curing and fresh water-curing. Lye-curing, an
unnatural method, results in the worst taste as it leeches much of the
fruits flavor. Salt-curing (also known as dry-curing) involves packing
the olives in plain salt for at least a month, which produces a salty
and wrinkled olive. Brine-curing involves placing the olives in a salt
water solution for a few days or more. Fresh-water curing involves
soaking the olives in a succession of baths, of which the water is
changed daily. Green olives are usually firmer than black olives.
Olives can also be flavoured by soaking them in various marinades, or removing the pit and stuffing them. Popular flavourings are herbs, spices, olive oil, feta, capsicum (pimento), chili, lemon zest, lemon juice, garlic cloves, wine, vinegar, juniper berries and anchovies.
Sometimes, the olives are lightly cracked with a hammer or a stone to
trigger fermentation. This method of curing adds a slightly bitter
Best Answer Chosen by Voters
As you may already found
out, there is a species of olive tree that is indeed wild, its the
original species from where all modern varieties were developed. In
portuguese its called zambujeiro. It has small olives that, like the
normal ones, can be picked and prepared for eating, its perfectly
safe, although not something usual.
One other thing,DONT let the olives in brine for a year (!),
these people dont know what they are talking about, Im from Portugal,
one of the major producers of olives and olive oil in the world, and
when preparing olives, usually changing the water with salt every week,
after a month of doing that they are already good