Find out what makes the best olive oil

Olive Oil Production Process

The process of manufacturing olive oil begins in the groves, where agriculture has to guarantee a sound and exactly ripened final product. The excellence of the oil is strictly dependent on the quality of the olives, from the care given during the production process (picking, manuring, pruning, and defence) and transformation (olive-extraction and all processes leading to the final product). The olive ripening generally occurs at the end of autumn or the onset of winter, and depends on latitude, climatic state and variety of the olive tree. The picking usually begins when the olives assume a partial or complete dark shade (the external peel colour changes from green to purple). Delaying the picking does not result in a better oil yield, but on the contrary begins degradation processes that negatively affect the oil quality. The olive picking systems are very numerous but can be grouped in two main categories: manual and mechanical picking.

Amongst the manual methods, the best results are obtained with brucatura (browsing) in which the olives are individually picked by hand and placed in a special basket hanging from the harvester’s belt. This method is, however, very slow and labour-intensive. A faster variation uses a special net which is laid on the ground under the tree and as the olives are picked they drop onto this net. A problem with this method is that the softer-pulp olive varieties tend to get damaged as they fall. Other manual methods are the bacchiatura (beating down) and the raccattatura (picking up).

Mechanical harvesting is basically the only option available for very extensive olive groves like Olearia San Giorgio: mechanical arms are clasped to the tree trunk or branches and shaken to make the olives fall on a net. Recently a method that uses combs that pass through the branches and causes the olives to fall on a net laid on the ground was introduced.

After picking, the olives are carried to the oil mill. The transport phase is vital to obtaining a good quality product: if it is done in sacks or containers where the olives are subject to any alteration a disagreeable fermentation process begins which inevitably affects the final product quality. The best way to transport the olives is in crates or well-ventilated boxes. To obtain good oil, the picked olives should not be dropped in heaps or stacked for a long time near the press. It is imperative that they are crushed within 24 hours of the picking. Olearia San Giorgio crushes olives within 6 or 7 hours of being picked. Before the crushing, it is advisable that the olives are thoroughly washed in order to eliminate any possible foreign particles that could negatively affect the oil quality.


The process of olive oil extraction can be divided in three main stages: frangitura, gramolatura, and spremitura. Frangitura is a mechanical process that crushes the olives. Crushing the pulp from which the oil is going to be extracted is a necessary step. There are two technical methods of frangitura: the traditional millstone olive press, and the hammer or disk mechanical press. The traditional method (referred to as ‘a molazze’) is composed of two large granite wheels that turn on a granite base, crushing the olives. The presence of olive stones does not harm the oil in any way, but rather, makes it easier to separate the oil from the solid component during the crushing process. The second method is more time efficient than the first, but requires special care in order to avoid high temperatures. Before being crushed the olive pulp is subject to the process of gramolatura, or kneading. The olive pulp and stones are mixed in order to reduce the volume and to separate the vegetable water from the oil, breaking up the oil and water emulsions created at the milling stage. At controlled temperatures this operation produces a delicate mix of the olive pulp that encourages the oil to coalesce. During this stage, particular attention is paid to both temperature and processing times. Temperature should be low and processing time should not be excessively long. Olearia San Giorgio always keeps the temperature below 24 °C and uses centrifuge as opposed to pressing. This process takes only 20 minutes (vs. several hours required for pressing) and dramatically decreases the oxidization process. It is important to limit any exposure to air and light while at the same time producing a good extraction yield.

Two methods can be used to extract the oil: the traditional vertical pressing method and the continuous centrifugation method. In the latter case manpower savings are guaranteed but particular systems need to be adopted in order to prevent the oil from being subjected to high temperatures that could damage its quality. After further decanting and filtering operations the final product is obtained.

The basic difference between the traditional and the continuous system is that the oil production speed becomes a very important factor when you want to reduce the olives’ processing and storing times to the utmost. We should however point out that the traditional method requires great professional experience in managing the plants and taking care of the state of te fiscoli (disk shaped mats on which the olive paste is spread after being crushed).

These, if not managed appropriately, are the main cause of oil defects. The continuous method gives excellent results, even though the crusher represents the crucial point as it gives more or less satisfactory results according to the raw material. In conclusion, undamaged olive pressing at controlled temperatures and sound olives guarantee the oil’s high quality.

Initially the oil is thick but with the passing of the months it becomes softer and softer in its harmony. Then, after one year, it starts degrading. Once separated from the vegetable water, the oil is evaluated from a sensory, chemical and physical viewpoint in order to determine its correct product class.
The oil is stored in tanks some of which are underground. Steel tanks are specifically recommended, preferably placed in places with controlled temperature and away from light and air. The oil’s preservation should avoid contact with the worst enemies of fats: light and oxygen, so as to maintain its characteristic composition in time and space.

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