Many people live with the impression that there are different species of olive trees for every color of olives. You will be surprised to find out that this is not true. There is only one type of olive tree, and the color of the fruits depends on the time they are cultivated.
The green, brown or black color of the olives is determined by the degree of their ripeness. In other words, the green olives are unripe and the black ones are extra-ripe.
From a nutritional point of view, there are differences between them; the darkest the color, the healthier they are. The green ones are like any raw fruit and the bitter taste is caused by a substance called oleuropein. In order to make them edible, green olives must be treated first. They are kept for 8-72 hours in an alkaline solution of sodium hydroxide that neutralizes oleuropein.
Then, whether green or black, the olives are placed in brine (salt acts as a preservative) or in oil so that they can be stored for a long time.
If the green olive has a bitter taste, consider it normal and enjoy it because oleuropein has antioxidant, anti-inflammatory, antimicrobial and anti-cancer properties.
In contrast, black olives contain 3-4 times more phenolic compounds (hydroxytyrosol), so they have a stronger antioxidant effect than the green ones.