Olives are the fruits of the olive tree (Olea Europaea). There are about 700 varieties of different olives varieties in the world. Nevertheless, buying olives in a store you can usually see just two color type difference: green and black olives.
Black is a symbolic name, because absolutely black olives do not exist in nature. Ripening, the olives darken, getting various shades, from bright brown to deep purple.
If you bought perfectly black olives then most likely they are artificially colored green olives. Such olives are processed with caustic soda (sodium hydroxide, very toxic substance!) and then coloured with artificial color iron gluconate E579. They are less tasty and most of their nutrients are killed by this process.
Right after harvesting, olives are impossible to eat because of their bitterness. In order to get rid of bitterness, olives are kept in brine for several months. The only exceptions are Greek olives Throuba from Thasos island. These olives lose their bitterness during the ripening and by the time of harvesting are already edible.
The cause of bitterness is oleuropein. It is a natural antioxidant that supports the good functioning of the cardiovascular system by reducing bad cholesterol.
Oleuropein also has anti-inflammatory and antibacterial properties and strengthens the immune system.
The pulp of olives is rich in proteins, pectins, vitamins A, E, C and B, as well as iron, potassium, phosphorus and polyphenols. Olives contain more than 70% of oil, which has high levels of polyunsaturated fats.
Green olives are larger and more hard and contain more vitamins and polyphenols than dark ones. Dark olives are always slightly smaller, more gentle and contain more oil than green ones.
In Mediterranean cuisine olives are used both as snacks and as ingredients in many dishes. They are put in salads, soups and stewed with vegetables. Olives are added to meat and fish to spice up the dish, usually along with oregano, rosemary and other herbs. Also, olives are absolutely indispensable for cooking canape, rolls and bruschetta for various stand-up dinner parties. Olives go well with Asian cuisine. For example, you can add them to thin green beans with tomatoes in soy sauce or to wild rice with mango sauce and vegetable salad.