BACKGROUND

The present application refers to the field of treatment and conditioning of vegetable oils prior to their packaging or to be placed In storage tanks and after the extraction process has ended.

At many stages during oil extraction, there is incorporation of atmospheric air added to the presence of vegetable water remains of the recently centrifuged oils. It has been demonstrated that the addition of water sequestrants and binders agents during one of said stages produces undesired side effects. An example of these is the large amount of wet sludge in which fermentation occurs which transfers undesirable odors and flavors to the oil, such as vinegar. The present invention aims to promote and accelerate the final decantation by physical actions, without the addition of additives, eliminating the atmospheric air absorbed and emulsified together with the water contained in the oil.

In a typical olive oil production process, olive paste is processed in a decanter (or horizontal centrifugal phase separator) to separate the oil from the alperujo by centrifugal force. Then, the oil mixed with water, air and pulp remains falls into a vibrofilter to separate the larger solids. In order to separate suspended solids and water, the oil is processed in a vertical centrifuge. After this stage, the oil only contains traces of water and finer solids (remains of olive mesocarp). This oil with impurities is deposited in tanks where gravity decantation takes place. This process of natural decantation takes from 12 to 5 days without the addition of additives. With the addition of additives (clarifiers based on silica gel and cellulose), these decantation times are reduced, but the subsequent handling for their elimination from the tanks generates operational problems. In order to perform the decanting in a continuous production plant, it is necessary to have tanks with the capacity to store a volume of at least 12 days of daily production of the plant. This requires exclusive space for these tanks and a considerable investment. Thirty percent of the tank capacity in a piant is usually reserved for the decanting stage. Additionally, the high operating costs of manual debris removal and transfer must be considered.

Both decanters, which centrifuge horizontally at 3500 rpm, and vertical centrifuges, which do so at 6800 rpm, incorporate a large amount of atmospheric air. This incorporation of atmospheric air is explained by the high pressures generated by the centrifugal force of these devices, which increases the collisions between liquid and gaseous molecules since the solubility of gases is directly proportional to the pressure (Henry’s Law).

Filtering these oils without a decanting process would be impossible due to the high moisture content of the oils (between 0.4 and 0.6%), which significantly reduces the lifetime of the filter elements that absorb this moisture and are saturated with water. At the same time, without previous decantation, there is a large amount of suspended vegetable tissue remains that also quickly soil the filters. This causes operational difficulties and increased costs due to the increase in the frequency of replacement of said filter elements. As a consequence, in the usual process of the prior art methods, oils are not filtered without a previous decanting process.

The incorporated atmospheric air is solubilized, absorbed, and emulsified with remains of vegetable water that contains the oil, producing undesirable effects. Some examples of them are: - Oxidation of polyphenols and antioxidants, leading to a reduction in the quality and lifetime of the oils;

- Delays in the precipitation of water and solids: this makes both water and solids remain in suspension for much longer. In general, at a temperature of 28 °C, from 12 to 15 days are required to complete the gravity decantation of an oil. This temperature reduces density, accelerating the precipitation of the water in the oil. Since it contains emulsified air inside, this precipitation is very slow. It also has the disadvantage that such temperature is optimum for the proliferation of the bacteria and yeasts in the suspended water (with sugars in the vegetation water and in the olive pulp), which produces fermentations that introduce unpleasant odors and flavors to the oils to the detriment of their quality. In addition, in an oil production plant of continuous production, a tank structure with a capacity equivalent to 12 to 15 days of oil press production is required. This requires a large investment in both the tanks and the space to place them.

- Another unfavorable aspect is that the vegetable water contains enzymes (such as lipase), which act on the water-oil interface, breaking down the triglycerides and increasing the free acidity.

At the same time, it is emphasized that the incorporated air and vegetable water produce rancidity in the oils. In particular, there are two types of rancidity: hydrolytic and oxidative. The former refers to the hydrolysis reaction of fat triglycerides with the subsequent production of free fatty acids. This reaction can be catalyzed by the lipases present in the olive seeds or pits.

Oxidative rancidity, also called self-oxidation, from the quality point of view, is the factor that most influences oils and fats. In this case, it is the reaction of atmospheric oxygen with the double bonds of unsaturated fatty acids. However, to achieve an efficient reduction of oxygen in oils, it is necessary to act on the oxygen dissolved in the product, which will react with the unsaturated lipids and on the oxygen in the air present in the so-called headspace, replacing it with an inert gas that is incorporated into the fluid, preventing the presence of oxygen. it is known that in the tanks, with the heip of atmospheric pressure, the air is dissolved in the oil, producing the aforementioned problems due to its content of oxygen, bacteria, yeasts, etc.

Currently, the most common practice is the inertization of the heads (upper part) of the decantation tanks using an inert gas heavier than atmospheric air (ozone or carbon dioxide). This method only prevents the upper layer of oil from being in contact with the air, but does not eliminate the oxygen dissolved in the oil.

Another technique usually employed is the entrainment with nitrogen of part of the air. However, this is not effective due to the high viscosity of the product.

Finally, there is also the injection of carbon dioxide. This method forms emulsions that transfer an anomalous flavor to the product.

While prior descriptions specifically speak of olive oil, most fatty products have their own natural antioxidants. These antioxidants are often lost during processing (refining oils, for example), and this loss must be compensated with the addition of antioxidants. This practice is common in the conservation of all the vegetable oils separated through the use of solvents. However, this technique inefficiently delays oxidation since the oils contain dissolved oxygen, thus reducing the lifetime of the oils.

As a result, there is in the oil industry faces a technical problem related with the undesired presence of air and moisture in oils. This is precisely the problem that solves the present invention allowing to obtain higher quality oils, with longer lifetime, in shorter times, and at lower costs.

SUMMARY OF THE INVENTION

The present invention has solved these prior art problems in a novel and inventive manner. A method for processing a vegetable oil is provided, the method comprising the removal of the air and/or moisture contained in the oil by means of a high relative vacuum pressure, thus breaking down the emulsions. This results in advantages from the point of view of the quality of the oils, as well as a reduction in process times and savings in facilities costs.

In an embodiment of the present invention, the method allows to obtain oil able to be filtered few minutes after the extraction process has ended. This time is surprisingly less than in the prior art. In this way, in an oil production plant, it is possible to dispense with the tanks and the space dedicated to decanting, without affecting the quality of the oil.

In another embodiment of the present invention, a method is provided for preventing the reincorporation of air into an oil when introduced into a tank. In this method, contact of the oil with atmospheric air is avoided by first filling the tank with an inert gas. Once the oil is filled into the tank, by the action of atmospheric pressure, the inert gas dissolves into the oil, thus avoiding its contact with oxygen. In other embodiments of the present invention, methods are provided for performing rapid decantations of 2 to 3 days of oils that will not be filtered, which comprise the use of high relative vacuum pressure.

It is also an object of the present invention to provide a method for processing a vegetable oil in order to remove the air and/or moisture contained therein through the application of high relative vacuum pressure.

In another embodiment, a method is provided for direct packaging starting from a centrifuged oil. This oil is dehydrated and de-aerated by means of the application of high relative pressure vacuum, filtering and finally packaging. In the packaging stage, it is advisable to use an inert gas with a higher molecular weight than the air in the bottle, this improving storage. In any case, it is advisable that there is an intermediate tank at the outlet of the filter and before packaging where inert gas is incorporated by atmospheric pressure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a device according to an embodiment of the present invention.

FIG. 2 shows samples taken at the middle level of the tank 5 days after the oils were placed in the respective test tanks.

FIG. 3 shows samples taken at the cone level of the tank 5 days after the oils were placed in the respective test tanks.

FIG. 4 shows samples taken at the middle level of the tank 11 days after the oils were placed in the respective test tanks. FIG. 5 also shows samples taken at the cone level of the tank 11 days after the oils were placed in the respective test tanks.

FIG. 6 shows samples taken at the middle level of the tank 18 days after the oilswere placed In the respective test tanks.

FIG. 7 shows samples taken at the cone level of the tank 18 days after the oils were placed in the respective test tanks.

FIG. 8 compares a sample obtained using a device according to an embodiment of the present invention with a control sample obtained using a typical production process.

DETAILED DESCRIPTION OF THE INVENTION

An object of an embodiment of the present invention is a method for processing a continuous flow of vegetable oil comprising the first step of: processing said oil flow to remove the water contained and/or the air dissolved therein by means of the application of high relative pressure vacuum. Said vacuum is applied to an airtight tank which allows the flow to have, during its passage through the tank, a thin sheet form to achieve greater exposure of the oil to the vacuum applied. In order to achieve the continuity of the flow inside the tank, the system is supplemented with a device capable of extracting the same flow of oil that enters the airtight tank, overcoming the relative vacuum pressure applied. This is achieved through the use of, for example, positive displacement pumps (screw pumps, gears, among others). With the application of this method, an oil is obtained that does not have emulsions, air or humidity, and that is ready to be filtered or deposited in a tank for the particles contained therein to decant (remains of vegetable tissues from the mesocarp).

In one embodiment, the continuous flow of oil obtained in the step described above is filtered and introduced into a storage tank. The storage tank has an inert gas inside, with a molecular weight greater than the molecular weight of ambient air. This tank also has an upper outlet that is in connection with ambient pressure, and by the action of this pressure, said inert gas is incorporated into the stored oil. This prevents the air from being absorbed again by the oil and from producing unwanted effects affecting the quality. The inert gases can be, for example, carbon dioxide (CO2) or argon (Ar).

In said embodiment, the continuous flow of oil without emulsions obtained is introduced into a tank where decanting of the particles still contained in the oil takes place. Since there are no emulsions, humidity and/or dissolved air, the time required by the decantation of said particles is reduced, and the temperature could be within a range of 15 to 30 °C. Preferably, it is carried out at room temperature, below 20 °C,. This method considerably reduces the capacity of the decantation tanks required as compared with a traditional setup. Optionally, the continuous flow of oil without emulsions obtained can be sent directly to the storage tanks. By completely eliminating the moisture present in it, the fermentative and enzymatic activity that deteriorates the quality of the oil is stopped.

In a preferred embodiment, the continuous flow of oil without emulsions, moisture and/or dissolved air is filtered to remove the particles still contained in the oil, thus achieving oil that may be packed or stored for packaging at a later stage. In the method according to this preferred embodiment, the stage of natural decanting is omitted in the total traditional vegetable oil production process. By eliminating this stage of the process, not only a dramatic reduction in production times of at least 12 days is achieved, but also the production plant sector dedicated to this purpose is not needed. In this way, space and investment savings are generated, since it would not be necessary to have decanting tank capacity equivalent to the production of at least 12 days of the production plant.

In another embodiment, a dehydration and/or de-aeration method of a continuous flow of vegetable oil is provided by means of high relative vacuum , through which the solubilized, absorbed and emulsified air and/or moisture is extracted from the oil with a high-suction pump. Then, the oil free from atmospheric air and/or water is introduced into a tank with an inert gas heavier than air (for example, carbon dioxide or argon), which is absorbed by the oil to achieve equilibrium and inertization. In this way, oil preservation is prolonged and the time of gravity decantation is reduced by approximately 75%. Alternatively, an inert gas lighter than air, such as nitrogen, can be bubbled with a diffuser so that the oil absorbs it.

The high vacuum used in the various embodiments of the present invention produces water evaporation, leading to a decrease in temperature, the elimination of dissolved air and consequently the breakdown of oil emulsions. Among other advantages, this allows direct filtering of the oil. Achieving direct oil filtering would eliminate the decanting sector of a vegetable oil production plant, with the advantage of being able to use these tanks as storage tanks, or in the case of new premises, to significantly reduce the total investment required. This is possible due to the absence of water and the reduction of particle size through the elimination of air.

In order to carry out the methods of the present invention, it is necessary that the continuous flow of oil be subjected to relative vacuum pressures within a range of 650 to 700 mm Hg or more. The advantages of the methods of the present invention result from a combination of variables such as:

- thickness of the oil sheet subjected to vacuum;

- oil temperature;

- vacuum application time; and

- vacuum pressure applied;

The thinner the sheet and the greater the other factors, the better the flow to be processed in the de-aerator / dehydrator and the benefits obtained.

The advantages of applying the method according to the present invention comprise:

- allowing direct filtering of the oil flow without requiring decanting, thus avoiding the resting days at high temperatures in a storage tank so that the solids and water may precipitate. This not only shortens the duration of the total process for obtaining a finished product in at least 12 days, but also allows to dispense with these tanks, thus drastically reducing the cost and space needed for a vegetable oil production plant;

- avoiding fermentations of the debris (consisting in plant tissues, vegetation water with sugars (12brix), etc.), which in an anaerobic environment where there are wild-type bacteria and yeasts, produces a highly negative effect on the quality of the oil;

- allowing, in unfiltered oils, to reduce the decantation time and the size and cost of the equipment required to carry out the decanting process; - avoiding reaction of the oxygen contained in the atmospheric air with the double bonds of unsaturated fatty acids, neutralizing oxidative rancidity.

Figure 1 shows that, in one embodiment of the present invention, there is disclosed a device for dehydrating and/or de-aerating a continuous flow of vegetable oii which works under vacuum in an airtight tank. The oii enters it at the top and is homogeneously distributed over a first cone of stainless steel that is part of a series of inverted cones. Said series of cones fulfills the function of extracting most of the humidity and/or atmospheric air retained in the oil, causing it to descend on very thin sheets. Additionally, a screw pump is connected to the bottom of the tank. This pump ensures that the process is continuous, removing from the tank the same flow of oil that enters the upper part, overcoming the vacuum pressure applied inside said tank.

In one embodiment, a dehydrated and/or de-aerated oil is deposited, through the lower inlet, in a tank that has been previously filled with an amount of an inert gas heavier than air. Once the oil has been introduced into the tank, the inert gas will dissolve in the oil under the action of atmospheric pressure. The amount of inert gas must be sufficient so that: (i) the inert gas dissolved in the oil at the atmospheric pressure affecting the upper part of the tank reaches saturation; and (ii) an amount of inert gas remains in the upper part of the tank to function as a separating layer. This avoids contact of atmospheric air with the oil inside the tank. Said inert gas can be selected from argon (Ar) or carbon dioxide (CO2), the latter being the most commonly used due to its availability and price. As a precaution, more inert gas is often added through the top of said tank. In other embodiments, nitrogen is bubbled with a diffuser, since it is lighter than air. Together with the extraction of atmospheric air and/or humidity from the continuous flow of oil to which a high relative pressure vacuum is applied, scents coming therefrom are dragged. In an embodiment of the present invention, these scents can be condensed in a scent condenser. This scent condenser consists in cooling with a liquid coolant at an appropriate temperature to achieve condensation. These scents can be introduced into the oil at a later stage.

Examples:

There follow different tests performed by applying the method of the present invention, which demonstrate their novel and inventive aspects.

Tests were conducted by measuring the moisture content before and after processing a vegetable oil with the method according to the present invention. In all cases, it was carried out in a device according to an embodiment of the present invention, with a continuous flow rate at a working flow rate of 350 liters/hour of oil, and applying a relative vacuum of 700 mm Hg. For the test, olive oils of different olive varieties were used once the extraction process was finished, at the exit of the vertical centrifuge, entering the device at a temperature of 28 °C. Evaporation under these conditions reduced the oil outlet temperature to an average of 24 °C. In all cases, samples were taken at the inlet and outlet of the device, yielding the following laboratory results:

As can be seen, it is confirmed that by applying the method of the present invention most of the moisture contained in the oils is removed.

Additionally, an oil decanting test was carried out, in which four olive oil treatment methods were compared after the extraction process, at the outlet of the vertical centrifuge:

(i) Control (ID 04): oil processed according to the methods of the prior art; the oil coming from the vertical centrifuge is introduced into a decantation tank;

(ii) Commercially Available Clarifier (ID 02): oil processed according to the methods of the prior art; the oil coming from the vertical centrifuge is introduced into a decantation tank with the addition of a commercially available clarifier at a dose of 3.5 g/L;

(iii) Cellulose + Silica Gel (ID 05): oil processed according to the methods of the prior art; the oil coming from the vertical centrifuge is introduced into a decanting tank with the addition of a mixture of 25% silica gel and 75% cellulose at a dose of 3.5 g/L;

(iv) Vacuum (ID 03): oil processed according to the methods of the present invention; the oil coming from the vertical centrifuge is processed in a device to remove air and moisture contained therein, and is introduced into a decantation tank without adding any kind of additives.

The tests were carried out based on an oil extracted from 18,000 kg of Changlot olives and placed in tanks (ID02, ID03, ID04, ID05) with a capacity of 400 liters and a conical bottom. Samples were taken from each tank at 5, 11 , and 18 days after extraction, and at each sampling two samples were taken: one from the cone level of the tank, and one from the middle level of the tank.

References in the Figures:

I: Control (ID04)

V: Vacuum (ID03)

O: Commercially Available Clarifier (ID05)

C + S: Cellulose + Silica Gel (ID02)

FIG. 2 shows the samples taken at the middle level of the tank 5 days after the oils were placed in the respective tanks. As can be seen, the control sample (T) is the most turbid one, followed by the cellulose + silica gel (C + S) sample, and the vacuum (V) and commercially available clarifier (O) samples show a similar turbidity level, but lower than the others.

FIG. 3 shows the samples taken at the level of the cone of the tank 5 days after the oils were placed in the respective tanks. As can be seen, the control sample (T) is the most turbid one, followed by the cellulose + silica gel (C + S) sample, and the vacuum (V) and commercially available clarifier (O) samples show a similar turbidity level, but lower than the others. Sediments were found in the sample bottle with the commercially available clarifier and cellulose + silica gel treatments.

FIG. 4 shows the samples taken at the middle level of the tank 11 days after the oils were placed in the respective tanks. As can be seen, the control sample (T) is the most turbid one, showing fine solids in suspension throughout the volume. The samples of cellulose + silica gel (C + S) and commercially available clarifier (O) show an average cloud of fine solids. And finally the vacuum sample (V) presents a slight cloud of fine solids.

FIG. 5 shows the samples taken at the level of the cone of the tank 11 days after the oils were placed in the respective tanks. As can be seen, the control sample

(T) is the most turbid one, showing fine solids in suspension throughout the volume. The samples of cellulose + siiica gei (C + S) and commercially available clarifier (O) show an average cloud of fine solids. And finally the vacuum sample (V) presents a slight cloud of fine solids.

FIG. 6 shows the samples taken at the middle level of the tank, and FIG. 7 shows the samples taken at the level of the cone of the tank 18 days after the oils were placed in the respective tanks. As can be seen, the vacuum sample (V) shows a remarkable difference in limpidity as compared to the other 3 treatments. The commercially available clarifier sample (O) shows slightly more turbidity than the vacuum sample (V) but with the disadvantage that the decanted debris shows signs of vinegar. The sample of cellulose + silica gel (C + S) has a turbidity similar to the control sample (T), which presents fine solids in suspension throughout the volume. The latter two samples also show signs of vinegar.

Based on this test, it can be concluded that the difference in the decanting process is remarkable when comparing the prior art methods with the methods disclosed by the present invention, achieving lower levels of turbidity in the decanted product, without the use of additives and maintaining or improving the quality of the vegetable oil with respect to the prior art.