The olive oil extraction process has the following steps:
H arvesting The way the olives are harvested is an essential part of the process, as this can significantly affect the quality and the cost of Extra Virgin olive oil. The sensory qualities and chemical composition of the oil depend on the ripeness of the olives and how they are picked: from the tree or from the ground. To make the finest olive oil, the olives need to be picked at exactly the right moment and taken to the mill without delay.
Transport and Storage. The method of transportation can affect the quality of the oil, so as far as possible, we try to avoid moving olives in large containers or in sacks, which can cause them to start fermenting. Ideally, the olives should be pressed as soon as they arrive at the mill: this is not always possible, however, during the busiest months of harvest. To avoid spoiling the best quality olives, we mill them at once, while the lesser-quality fruit gathered from the ground is stored in large hoppers. These olives are turned into lower-grade oil, or “lampante”, and will be sent to the refinery.
C leaning by blowing and washing The freshly picked olives come to the mill mixed with detritus picked up during harvesting. The twigs, stones, leaves and earth have to be removed, to prevent damaging both the quality of the oil and the mill machinery. A powerful blower is used to remove the leaves, twigs and small stones: then the olives are put into a vibrating sieve and washed by a strong jet of water.
Grinding. The olives are ground up using metal milling machinery with an internal crushing mechanism of various types, which mashes them at high speed. The resulting product is olive paste, made up of the stone, the flesh, skin, water and oil.
Mixing.The paste is mixed until it forms an emulsion, encouraging the accumulation of oil. The machinery has three paddles running at a steady rate on a horizontal axis, in semi-cylindrical tanks with an external chamber that allows the circulation of warm water. To achieve maximum quality the process must be controlled by time – about 60 minutes; and temperature – the mixing takes place at a cool temperature. Sometimes the paste shows an excess of colloids, which requires the use of additives such as mineral talcum.
Centrifugation. This takes place in two steps:
First step: the olive paste is centrifuged at high speed, which obtains oil mixed with water, together with some solid matter – which will be eliminated by a vibrating sieve-. The residue contains pomace and water, with some oil not extracted in this first centrifuging. The stones are removed and this olive stones, when dried, are used as fuel for the mill’s boiler.
Second step: The oil is centrifuged again. By this process, we separates any remaining water and particles in suspension after the first centrifugation.
Clarifying. The oil is stored for a brief period in small open stainless steel tanks with a capacity of 700kg, to eliminate any final impurities.
S torage in our cellars. The company has two storage units with a total capacity of 2.7 million kilograms. Both are completely insulated and climate conditioned, to maintain a constant temperature all year round. The individual stainless steel tanks are each capable of holding 25,000 or 50,000kg, and those which store the best quality extra virgin oil contain a cushion of nitrogen – an inert gas very stable under normal conditions, which displaces the oxygen in the tanks and slows down the oxidation of the oil. The three factors which contribute to the deterioration of olive oil are temperature, light, and air: by using stainless steel tanks inertized with nitrogen in a closed storage space at a constant temperature, we are able to preserve the sensorial qualities and physical characteristics of oil produced over a long period of time.
Filtering and bottling.