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The production |
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Production: Like every other oleaginous, the principal problem of the olive oil extraction consist in the breaking of the oleiferous cell to allow the vacuoles to escape and to coalesce in bigger drops. In the olive oil's production this principle assumes some peculiar aspects and presents a certain number of difficulties that comes from the fruit structure and the abundant water that it has. Like other extracting techniques the raw materials, in this case a fruit, must be prepared and conditioned through a series of phases, apparently mechanical but actually for many aspects really complicated. From the correct implementation of them depends the final quality of the olive oil, as long as the raw material is of good quality. The preparation has implications not only qualitative but also quantitative, being directly linked to the return obtainable in the physical way. The washing: This operation is important to eliminate foreign matters, whether coming from the tree (leaves, twigs etc.), from the ground (soil, dirt etc.) or from the treatments of any kind of phytosanitary product. The water quality is obviously important, relative to the eventual presence of contamination. It's inadvisable the use of detergents, even if they could be helpful under some aspects, it could be very difficult to completely eliminate, because of their lipophilic nature. The grinding: In the chemical and physical way, this treatment is very important since it allows to make an intimate contact between the oil, which was before protected inside the oleiferous cell, and the other constituent of the cell and the fruit, with their enzymatic load. In ancient times this operation was conducted with a system of revolving cylinders on a tub with a stone base that served as a container for the olive's dough; a rudimental advancing system made by metallic flaps, allowed the blending and the transportation of the dough toward the exit. The construction material, the stone, was consecutively replaced by metallic structures not always with advantages to the final product, especially for some olive's variety. Mills with hammers are also utilized, but regardless of their convenience and cheapness, sometimes they present disadvantage in terms of the oil quality. During the grinding stage occur important transformations, especially to the more labile components respect to the hydrolytic enzyme. For example some bitter ingredients undergo hydrolysis that improves the olive oil quality if the operation is done in a way to avoid other more intense hydrolytic actions, identifying by trial an error the exact grinding time, which is different for each kind of olives. As it has been reported above, the hydrolysis of the precursor glucosides is a necessary condition to make soluble the complex phenols. These same aspects are present in the next phase of blending, aimed to smooth the dough but mainly to induce the coalescence of the small oil drops, into bigger drops which are obviously less willing to undergo the enzymatic attacks.In both stages, the operational times are decisive for the olive oil quality and they have to be adjusted to the various possible fruit, through experience. The increased temperature, in the blending, through the interchange of heat with hot water, helps the operations and the return; it's indicated as a limit a temperature of about 25-30°C. The extraction by pressure: The separation of the components of the dough could be done in different ways, the most ancient tool, still used, even if mechanical evolved is the press. The preparation of the extraction. The process is discontinuous, made by different preparatory phases of the extraction and by post-extraction phases, and in its totality is very complicated, costly regarding the manpower, open to possible contamination from the environment if not perfectly managed. Basically the modern presses, in anyway designed, operate the pressure on a " package" made of layers of the olive dough and a fabric fit to hold it, once made of vegetable material (coconut or hooded matweed fiber), today made of nylon. The package prepared aside goes afterward in the hydraulic system where the pressure gets gradually applied until it reaches 400-500 Kg/cm2. The olive oil and the water come out from both the edges and the central conduit. After this process it follows the disassembling of the package, and its components, excluding the sansa, return back to the beginning process. The olive oil that came out from the presses can be separated by spontaneous decantation or by centrifugation in vertical centrifuge, from which originate the watery stage (vegetation water) and the oil. Depending on the degree of separation, the olive oil can have different looks, from the perfectly clear to the opalescent, to the turbid, in function of the customer's preference. We must mention the fact that the presence of particles that give the turbid look to the olive oil, is always escorted by an enzymatic charge that makes the olive oil less stable and less preservable. The conservation and storage: The olive oil purified from the vegetation water generally gets conserved for a certain period, especially where the production's center have huge capacities and where the olive oil goes to the wholesaler. When it's virgin olive oil, saleable as such, the conservation assumes an important aspect in the perspective of keeping intact the quality and therefore a higher price. Considering that the olive oil is one of the oil with the longest preservability, because of its acidic composition and of its antioxidant patrimony, still it's not infinite, especially in relation with the organoleptics quality, we need to follow a certain number of rules;
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