The Harvest

The HarvestNothing gets more discussion among olive growers than when to pick. It can make all the difference as far as yield, organoleptic characteristics, shelf life, and color.


Fruit maturation depends among other things on olive variety, temperature, sunlight, and irrigation. A hot fall can cause fruit to ripen quickly, resulting in a narrow window for optimum picking. A cool fall may result in green fruit hanging on the tree well into winter. Some farmers are forced to pick greener fruit than they want to hedge against frost damage or a big storm. Some varietals will ripen faster than others, and olives may mature later in some parts of the orchard than in others.

This makes the decision on when to pick potentially complicated. Keep in mind that olives are not as sensitive as grapes picked for wine, however. You don’t have to get up in the middle of the night to meet an extremely narrow harvest window and put them on ice. Having said that, good planning is still essential to make sure the picking crew and equipment is ready when needed, and milling capacity is scheduled so that the olives don’t have to wait after being harvested.
Maturity stages
Green (Immature) Fruit

Immature olives are green and quite firm. They produce oil that is bitter and grassy with unripe and vegetative characteristics. These oils are high in polyphenols (anti-oxidants) and other flavor components. As a result, they are quite bitter and pungent and have a long shelf life thanks to these natural preservatives. The chlorophyll content is high so the oils are often quite green. It is more difficult to extract oil from unripe olives because the oil containing vacuoles within the cells are not easily ruptured. The olive paste has to be malaxed longer.

As the olive fruit matures from green to yellow-green, it starts to soften and then the skin turns red-purple in color. This is called veraison. The olives still have a high polyphenol content at this stage, and are starting to develop some ripe-fruity characteristics. Oils produced from fruit harvested at this stage have some bitterness and some pungency. They have close to a maximum amount of oil per dry weight. The olives are often considered to be at their peak for olive oil production.
Black (Mature) Fruit

As the fruit matures further, the skin turns from purple to black (although some varieties never turn completely black), and the flesh darkens all the way to the pit. At this stage, the polyphenol and the chlorophyll contents decline and the carotenoid content increase. Therefore, oils produced from late harvest fruit tend to be more golden in color, less bitter, less pungent, and have a shorter shelf life. They are often described as sweet oils. The oil yield is high.