Brined - Mediterranean

Green olives, Spanish style

Name: Green olives, Spanish style
Cuisine: Mediterranean

The one recipe on this site with a caustic step. Sodium hydroxide at two percent is not a seasoning and not optional in this process: the bulletin's point is that the olive contains a compound that stops the fermentation happening at all until it is removed. Read the safety page before you decide whether this is a recipe you want.

6 steps, every one quoted from FAO Bulletin 134 6.2.4. The step labels are this site's; the sentences under them are not.

This recipe uses sodium hydroxide

Lye is caustic. It burns skin and eyes on contact and is not a food ingredient in the way salt is. This site publishes the process because the source publishes it and because an olive genuinely cannot ferment until the compound lye removes is gone. It is not telling you to do this, and it is not a set of handling instructions. If you have not worked with a caustic solution before, read the safety page first and take the sourcing of protective equipment and a neutralising rinse as your own responsibility.

Salt, at a batch you might actually make

1 to 10 % salt in water, of the weight of the finished brine.

Water	Salt at 1%	Salt at 10%
1 kg	10 g	111 g
2 kg	20 g	222 g
5 kg	51 g	556 g

The arithmetic, at 2 kg

Percent by weight of the finished brine.
salt / (salt + water) = percent / 100
salt = water x percent / (100 - percent)
     = 2.000 kg x 1.00% / (100 - 1)
     = 20.2 g

Finished brine: 2.020 kg, of which 1.00% is salt.

This is a percentage by weight of the finished brine, which is what a salinity meter reads and is not the same as grams per 100 mL of water. The calculator gives both.

Every number the source states

Fermentation brine: 1 to 10% salt in water
Optimum fermentation temperature: 24°C
Fermentation period: two to three months
Lye treatment: 2% sodium hydroxide
Lye temperature: 21 to 24°C

Substrate

Olive

Region

Method

Numbered for your place in the list. Every sentence below is the source's own, verified against the page it came from when this table was last built from the sources.

Lye treatment
Green olives are placed in a 2% sodium hydroxide (lye) solution at 21° to 24°C until the lye penetrates the flesh.
Wash the lye out
Cold water is added to the solution, which, dilutes the mixture until the lye is completely removed.
Brine and ferment
After the glucoside has been removed, the olives are placed in barrels with a 1 to 10% brine solution and allowed to undergo a spontaneous fermentation.
Hold the temperature
The optimum fermentation temperature is 24°C.
Wait months, not weeks
The fermentation period usually takes between two and three months.
Pack
Once fermentation is complete, the olives are packed in airtight jars and sterilised which produces a good quality product with a long storage life.

What else the source says

Why the lye step exists at all: The lye treatment is necessary to remove a bitter glucoside compound (oleuropein) from the outer tissues of the olive. Oleuropein is highly toxic to bacteria and therefore needs to be removed in order for a fermentation to take place.

Before you make this

This site is a reference and not a food safety authority. It reports what named sources published and does not certify that any preparation is safe. The safety page sets out what the sources themselves say about acidity, about surface growth and about when to throw something away, and equipment lists the instruments the numbers above cannot be checked without.

The full record for this pickle, including every source consulted and the ones that disagree, is on its tradition page.

Other brined recipes

Method and asides from FAO 134 Battcock, M. and Azam-Ali, S. (1998) Fermented fruits and vegetables: A global perspective. FAO Agricultural Services Bulletin No. 134. Food and Agriculture Organization of the United Nations, Rome. Numbers from the same source, extracted separately and listed on methodology.