Early harvest olive oil is made from olives that are partially "enveradas", changing its colour from green to purple. You need 7 to 8 kg of olives to make one litre, instead of the 4 to 5 kg/l of full ripe olives.
As the olives mature the color of the outer part (epicarp) changes from bright green, purple-green, purple and finally black. The inner part (pericarp) changes from white-yellow to purple-black. The fat content increases and the chlorophyll decreases.
The olives of the same branch mature at different times, so at the time of harvest we have a percentage of green, green-purple or purple. In the oil of early harvest, the proportion of purple olive is smaller and therefore its lower fat content and higher in chlorophyll. That makes the flavour of the oil more fruity and the acidity somewhat higher.
Early Harvest Oil has a bright green colour because of the higher chlorophyll content, also higher polyphenols and antioxidant. It has a greater herbal and fresh fruit flavours than regular Extra Virgin Olive oil, they are stronger, more piquant (greater oleocanthal content) and more bitter (greater oleuropein content).
Historical curiosity: In ancient Rome they gave different names to the oil according to the degree of ripeness of the olives
- Oleum ex albis ulivis, coming from the green olives harvested by hand.
- Oleum viride, extracted from almost ripe olives.
- Oleum meturum, from ripe olives
- Oleum caducum, the one that was extracted from the olives already fallen from the tree.
- Oleum cibarium, finally, made with chopped or rotten olives. Given to the slaves.