Some olive facts

  • The first Olympic flame was a burning olive branch.
  • It is classed as a fruit.
  • It is said that Moses granted olive growers an exemption from military service, so revered was the fruit.
  • Vincent van Gogh painted 19 pictures of olive trees.
  • It takes 5 to 8 years to produce its first fruit, but has an extremely long and productive life – up to 600 years, sometimes more.

Not All Black Olives are Black

We’ve all plucked an olive off a tree, popped it into our mouths and quickly popped it back out again – haven’t we? (Well, I have!).

Oleuropein – Olive Defence System

Green olives are harvested before they’re ripe, black ones ripen on the tree. In their natural state, both contain oleuropein, a bitter compound found in the skin, flesh, seeds and leaves.

It is so bitter that it acts as a sort of olive-defence system and prevents birds and insects from pecking them off the trees.

In order for you to enjoy your olives, the oleuropein must be completely removed or they are inedible.

Clever Romans

It is believed that the Romans discovered the technique that made olives what they are today. Before that, the bitterness was soaked out of them over many months of repeated water changes, followed by fermentation in brine.

The clever Romans discovered the method of supplementing the brine with lye (sodium hydroxide) to produce an edible olive in hours instead of months.

Not All Black Olives Are Black!

Green olives are often processed in this way so they darken to look black. Those perfect black olives that you buy in tins are very pretty and shiny because they are cured in an alkaline solution, and treated with oxygen and an iron compound (ferrous gluconate), which turns their skins black. This affects their flavour of course too.

If you’re looking for healthy and tasty black olives, don’t go for the shiny black ones, (marked ‘confites’ here it France) as they’re the least natural of the lot!

A little bit of vocab

Noyau(x) – stone

Dénoyautées – stoned

Confites – preserved

Olivier – olive tree

Oléiculture – olive growing

Oliveraie – olive grove



  1. There are definitely places that will do that for you Renia – we have some friends who did it – but put they put their olives together with somebody else’s because the minimum quantity was quite large.

  2. Is there anywhere that a reasonable amount, say 50kg+ of olives can be taken to be pressed? It seems a shame to waste all of our olives every year.

  3. David Ingram, lye=sodium hydroxide = caustic soda = drain cleaner (not all)
    Nasty stuff, take care 😳

  4. Where can you buy lye. I have tried brine and soaking without success.

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