It is a long way from the fruit to the finished product in a bottle or canister. The production of high-quality olive oil is a fascinating process that involves a great deal of tradition and craftsmanship. But good olive oil takes time and a lot of care. It all starts with the olive trees, which are often tended for decades in order to produce the best fruit. But how do these small fruits become the golden elixir that we love so much in Mediterranean cuisine? In this article, we look at precisely this topic. We shed light on all aspects of olive oil, from cultivation to harvesting and pressing (extraction).
Unfortunately, it is not enough to plant a seed and wait for a large olive tree to grow and bear fruit. The care of olive groves is an elementary component and requires a great deal of knowledge and dedication on the part of olive growers. Although olive trees are long-lived and robust plants, they still have special needs and risks of pests and diseases that need to be minimised through care. The best way to do this is through organic and sustainable practices.
Although the olive tree is quite drought-resistant, it needs sufficient water, especially during the growth phase. And water is unfortunately becoming more and more of a problem and a scarce commodity in some Mediterranean regions. If the winter rains are absent or insufficient, a lack of water can affect the growth of the vegetation, fruit set and fruit development. One method that is not really sustainable is artificial irrigation. This is particularly true of conventional intensive olive groves (similar to artificial orchards) and conventional super-intensive olive groves (where plants are grown in hedgerows rather than trees, allowing purely mechanical harvesting), which are supplied with water and fertiliser via a drip system. Our olive growers (e.g. MANI), on the other hand, focus on sustainable practices. One focus is the promotion of biodiversity in the olive groves. The vegetation of legumes and wild herbs that grows naturally between the olive trees is preserved, keeping the soil fertile and protecting it from drying out. However, this also means that chemical fertilisers and pesticides must be avoided in order to preserve biodiversity. Another trend is the creation of retention basins, which (at best) absorb water in the winter months and serve as a source of water for trees and animals all year round. The more flora and fauna there is in the olive grove, the more resistant the olive tree itself is. Also against pests. This brings us to the next topic, pest control.
The most common pests are the olive fly and the olive weevil. A healthy plant can withstand many of these threats. However, in times of extreme weather fluctuations and extreme temperatures, pests such as the olive fly increase. If the winter is too mild, the population of the olive fly increases and threatens the yield of the olive harvest. In conventional agriculture, this pest is combated with chemicals, i.e. it is ‘sprayed’ until nothing crawls or flies. Our farmers rely on natural methods of pest control, e.g. traps with attractants against olive flies or natural predators that keep the pest populations in check. This is where flora and fauna come into play again. An olive grove with high biodiversity can keep pests at bay. A super-intensive olive grove cannot do this naturally. Even if the conventional cultivation of olive trees promises higher yields, the quality and flavour of the olive oil suffers. Organic cultivation, on the other hand, requires more care, but conserves soil and water. And a healthy environment is also reflected in the flavour.
The trees are pruned depending on the species, location and tradition. There are several reasons for pruning olive trees. For small trees, the aim is to keep the olive tree in shape. Larger trees are pruned on the one hand to maintain the health of the plant and on the other hand to maximise yield and quality. In Mani (Greece) there is a local speciality in this respect. Here, when cultivating olive trees, attention is paid to extremely heavy pruning. This applies in particular to the Koroneiki olive tree for the production of Koroneiki olive oil. Once a year, the trees are pruned to a minimum. As a result, the yield is lower (only 1-3 litres per tree instead of 5-15 litres), but the quality of the olives is higher.
In the autumn months, a healthy olive tree bears plenty of olives that need to be harvested. Depending on the olive variety, location, climatic conditions and intended use - table olives (edible olives) or oil olives - the time of harvest varies.
In the Mani region of the Peloponnese, olives are ready for harvest between November and January. Our olive growers do not use large harvesting machines. Instead, there are many helping hands, large nets and so-called vibrating poles. First, large nets are spread out under the trees in order to remove the olive fruit from the branches as gently as possible. This is usually done by hand or with the help of small electric vibrating poles. The olives then fall gently from the tree into the nets without coming into contact with soil or dirt and can be taken directly to the nearest oil mill. The aim is to press the olives as quickly as possible immediately after harvesting. This is the only way to guarantee an excellent olive oil of the highest quality.
The olive oil production process begins in the oil mill. Care is required here in particular, which determines the quality of the end product. This is because before the oil is pressed or extracted from the fruit, harvest residues such as leaves or twigs must be removed. The olives are then washed and finally crushed into a pulp, a mass of fruit flesh and pits. The liquid gold can now be extracted from this mass.
For centuries, the production of olive oil was a romanticised affair: a donkey ran in circles to drive a huge millstone while the olives were crushed into a fine paste. This paste was then stacked on mats and pressed with a lot of muscle power and sweat. Today, the donkey grazes in the olive grove and ‘cold extraction’ has become established among modern olive growers and oil millers. The olive paste is passed through a centrifuge, which separates the oil from the rest without the hustle and bustle and old mats.
However, cold pressing is also still practised. In ‘modern’ cold pressing, the olive paste is applied to nylon or bast mats, which are then stacked on top of each other. Due to the high weight of several mats stacked on top of each other, the oil-water mixture is automatically pressed out of the pulp.
The great advantage of cold extraction over cold pressing is that it is a closed system. This prevents oxygen from penetrating and impairing the quality of the oil through oxidation. The end product of the first ‘centrifugation’ is a mixture of oil and fruit water. The amniotic fluid is filtered out in a second centrifuge.
Fresh, cold-pressed olive oil usually still contains a lot of suspended matter. A resting phase is necessary so that these can settle and be removed as sediment. In a final step, the olive oil is filtered. This also removes the last deposits. After filtration, the production of the olive oil is considered complete.
High-quality olive oil is not a product of chance, but requires careful care, expertise and the use of sustainable practices. From the cultivation of olive trees to harvesting and processing, every step must be carried out with care and respect for nature and tradition. Sustainable cultivation, gentle methods of harvesting and oil extraction and the avoidance of chemical additives, pesticides or herbicides not only guarantee a high-quality product, but also protect the environment. This is the only way to produce an olive oil that is not only flavourful, but also in harmony with nature.
