Production: climate, care of the olive grove and harvest
The climate of the Mediterranean region with its long, warm and dry summers and mild, rainy winters offers ideal conditions for the olive tree. Sun, little rain (or watering) from spring to autumn, a not too deep soil and limestone soil are sufficient for it to thrive.
In addition to a favorable climate, the quality and taste of the oil depend on the olive variety and the optimal care of the olive grove - the spring pruning is particularly important. However, the method and time of harvest, which in Europe is between mid-October and the end of December - depending on the geographical location of the olive grove - have a particularly great influence. The way the olives are processed in the mill is also decisive for the quality.
The first step in obtaining high-quality oil is to scrape the olives with small rakes - either by hand from ladders or with motorized forks that gently shake the olive branches. Thousands of years ago, long sticks were used for harvesting, with which the olives were knocked down from the branches - a method that was criticized by agricultural experts in ancient Rome because branches and olives were badly damaged in the process.
Faster harvesting with jogging machines is just as suitable as the laborious manual picking. Concerns that this could damage the trees have not come true. Huge gripper arms grab the trunk or one of the main branches, vibrate for a few seconds and shake the olives to the ground, which fall onto cloths. With some machines, the cloths roll up automatically and convey the fruit onto a conveyor belt, which gently distributes them into large cassettes. Occasionally, olives are still filled into sacks, where they crush each other. Once injured, they oxidize quickly and rot. Whether hand picking or mechanical harvesting - the olives are immediately brought to the mill and, if possible, processed on the same day.
With these methods, not all olives are ripe; a mixture of green, yellow, purple and blue fruits is deliberately harvested - i.e. unripe to ripe. This colorful mix already offers a certain guarantee of minimum quality, as the oil thus gets a fresh note.
Another traditional type of harvest is used where huge olive trees that are several centuries old or up to 40 meters high make manual harvesting or even the use of vibrating machines impossible. Here you wait for overripe blue-black olives to fall from the branches by themselves, like windfalls. A distinction is made between three harvesting methods: The first is to stretch nets over the ground, which remain under the trees for the entire winter. Advantage: after rain the olives dry faster and do not rot. If, on the other hand, the nets are directly on the ground, the fallen overripe fruits often lie in their damp environment for weeks, oxidize and spoil quickly.
The third type of harvest completely dispenses with nets: the overripe olives fall directly onto a ground that has been mowed, cleared and flattened to make it easier to find and collect the fruit. Unfortunately, the soil is not always plowed up beforehand, but treated with weedkillers and other chemicals. The olives, which are already very soft and dark in this late ripening phase - usually between December and March - burst open on impact and oxidize immediately. The putrefaction is also promoted by the muddy and acidic soil after downpours. The olives stay on it for weeks. Later they are mechanically swept up and piled under the trees. The putrefaction and oxidation process of the leaking amniotic fluid and the olive oil is often announced in the grove by bad smells. Finally, this unsavory mud is loaded onto trucks by shovel excavators and driven into the mill. This harvesting method is often noticeable later in olive oil through unpleasant rancid notes.
For example, olives that fall overripe from the tree can almost never be turned into high-quality "extra virgin olive oil" of the 1st quality class, because the more ripe the fruits are, the higher their oleic acid is. However, only a maximum acid value of 0.8 percent is permitted for top-quality oils. If the oleic acid content is above 0.8 percent but still below 2 percent, then the oil obtained is only a "virgin olive oil" of the 2nd quality class. However, if the acid content is over 2 percent, then it is a so-called lampante oil, which belongs to the 3rd quality class and is not allowed to be sold in the trade.
Until the end of the 19th century, lampante oil was used for lamps throughout the Mediterranean region. If you wanted to market it as a food, it would have to be refined beforehand and thus freed from the high acid content and the unpleasant smell that is often associated with it. But then by law it can only use the simple name “olive oil” in trade.