Patent Description:
High-pressure processing (HPP) is a technology that, at pressures above <NUM>,<NUM> bar, manages to reduce the microbial load, without altering the characteristics of the processed product.

HPP equipment known for treatment of liquids or other substances through high pressure are based on the processing of the product previously arranged in flexible containers, for example in bottles. The classic form of high-pressure processing is carried out in batches, that is, by means of a discrete and non-continuous process. Initially, the products inside their flexible final containers are loaded into rigid plastic containers that are loaded into a steel vessel, which is then filled with water (the remaining space, since there are unoccupied gaps between the containers). Once filled, it is completely closed and the water starts to be pumped at high pressure (through one or more high-pressure intensifiers) up to <NUM>,<NUM>-<NUM>,<NUM> bar and said pressure is maintained for a time that can vary from a few seconds to several minutes. The pressure reached and the time that it is maintained are the parameters of the process that are defined in each case depending on the product to be processed (this is called "recipe"). For example, in the case of a beverage, the technology is used because of its microorganism inactivation effect and the recipe is defined according to the desired level of microorganism inactivation to be achieved. Finally, the pressure is released, the containers are removed from the interior of the vessel and the processed product is extracted. The product has been sanitized, that is, the microbial load thereof has been reduced.

In an HPP batch process, the pressure is transmitted to the products through the pressurizing fluid, usually water, being a pressure that is transmitted equally and instantaneously to all points of the product. Given that the product is processed when already packaged, the filling coefficient of the vessels (relationship between the product volume to be processed and the useful volume of the vessel) is low, between <NUM>% and <NUM>%, depending on the geometry of the container and the vessel diameter. It can be concluded from all of the above that the main advantage of batch processing is the absence of subsequent contamination of the product, since from the beginning it is in its final packaging. On the other hand, the main disadvantage is that the low filling coefficient that is achieved limits the productivity of the traditional high-pressure processing equipment. Other disadvantages of the batch process are the need to use flexible packaging that can withstand the effect of high pressures (the use of materials such as glass not being possible) as well as handling them for loading and unloading the HPP machine.

Therefore, there is a need to look for an alternative to the current processing mode that can increase the filling coefficient of the vessel and avoid the restrictions on the type of packaging, ensuring that contamination is not produced after the processing of the product, the latter being the most difficult to achieve.

Over time, different solutions have been considered, mainly oriented in two directions: processing liquids directly inside a vessel with a piston that transmits the pressure, or processing liquids inside a bag or flexible membrane located inside the vessel and occupying as much useful space as possible.

In the case of the systems that include a displaceable piston inside the vessel, intended to apply pressure directly, it separates two regions, one that comprises the pumpable product to be treated and another in which the pressure-transmitting fluid (usually water) is found. These systems have the main drawback that the piston requires high-pressure gaskets specially designed to prevent mixing the liquids of the two areas. Said gaskets require constant monitoring and substantial maintenance. Furthermore, this solution is not hygienically optimal, since it is very easy for the product, once processed (and thus "sanitized"), to come into contact with contaminated areas (pressure-transmitting fluid) and to undergo contamination.

During the <NUM>'s, several types of equipment were developed that worked by processing the product in bulk (in a semi-continuous system). All of these operated with a piston and had problems of hygiene (difficult cleaning of the equipment and contamination of the product once processed) and problems of mechanical reliability reason for which they are no longer being manufactured.

An example of a system provided with a membrane is found in <CIT>. However, this system does not have good hygienic conditions, since it does not prevent the contamination of the product that has been processed or that is being processed due to the exposure/passage thereof to a duct that is not correctly sanitized, since the design was not conceived to be easy to clean.

Other solutions that have been proposed for this type of high-pressure processing equipment include very complex systems with a large number of valves, pipes and gaskets subjected to high pressure that, apart from being difficult to clean, are susceptible to having reliability problems due to the complexity thereof. It is known that equipment working at very high pressure require elevated maintenance, so in order to increase productivity and reduce machine downtime, it is essential to have a simple and efficient design in which the number of components, valves, tubes, couplings and gaskets subjected to high pressure is kept as low as possible.

Another relevant publication is <CIT> which discloses a plug according to the preamble of appended claim <NUM>.

The object of the present invention is that of providing a plug for a high-pressure processing machine that resolves the aforementioned drawbacks, which will enable processing pumpable substances in a flexible bag located inside the vessel. In particular, said plug meets the requirements of hygienic design and sealing at very high pressure, enabling the cleaning of its inner ducts, which guarantees the absence of contamination of the processed product that must pass through said ducts at the end of the process. The plug is located at one end of a machine having a high-pressure vessel and enables filling and emptying of a flexible bag (located inside), in which the product of interest is pressurized. It comprises a duct for the passage a pressure-transmitting fluid, another duct for the inlet and outlet of product to be processed in the bag and a seat valve with a male and a female seat in order to enable or prevent the passage of the product to or from the bag. A rod joined to the male seat and usually actuated by an actuator is located inside the filling/emptying duct in order to close and open the valve. The rod has an inner duct joined to a cleaning agent chamber such that while the product is being processed inside the bag, the filling/emptying duct remains under a bath of cleaning agent.

The invention also relates to a high-pressure processing machine (<NUM>,<NUM>-<NUM>,<NUM> bar) including said plug and a pressurization method by means of said machine. The machine thus conceived, which would achieve an elevated filling coefficient of up to <NUM>-<NUM>% would meet the objective of inactivating the microorganisms and/or modifying properties of perishable liquid/pumpable products (such as beverages, food, cosmetic/pharmaceutical products, etc.) maintaining hygiene at all points of the machine and the process.

In order to assist in a better understanding of the characteristics of the invention, this description is accompanied by the following figures, as an integral part thereof, which by way of illustration and not limitation represent the following:.

<FIG> shows the diagram of a machine incorporating the plug of the invention. It comprises a source of a product to be pressurized <NUM>, which is temporarily stored in a tank <NUM> and is transferred through a circuit of pipes and through the product plug 5a to a flexible bag <NUM> situated inside a high-pressure vessel <NUM> provided with two openings at the ends 4a and 4b. Once the flexible bag is filled with product, a pressure transmitting fluid, generally water, is introduced into the vessel, through two plugs 5a and 5b, by means of one or more pumps <NUM> and through the ducts provided for this purpose in both plugs <NUM>. The fluid will exert the pressure defined in the process (around <NUM>,<NUM> bar for most recipes). The pressure will be maintained for a certain amount of time and once the process has ended, one or more discharge valves <NUM> will cause the pressure inside the vessel <NUM> to be reduced to atmospheric pressure. The product plug 5a, which is the invention itself, separates the area in which high-pressure processing takes place from the area that must always be sanitized, since once the product has been "sanitized" (processed and therefore free from microorganisms) it leaves the flexible bag through the same duct through which it entered unprocessed (and therefore possibly initially contaminated with microorganisms) and the absence of contamination must be guaranteed in this phase.

In reference to <FIG>, the plug of the invention 5a has an inner filling and emptying duct <NUM> for the product to be pressurized, in addition to the duct for the pressure transmitting fluid <NUM>. A seat valve <NUM> at the end of the plug in contact with the bag <NUM> prevents the filling and emptying duct <NUM> from being subjected to high pressure during the HPP cycle (all the phases of the high-pressure processing). The existence of this valve means that the filling duct, which is the same duct as for emptying, can be designed with a hygienic design standard and is consequently easy to clean effectively during the phase of maintained pressure of the HPP cycle.

The valve <NUM> consists of a male seat <NUM> and a female seat <NUM>, both of which are manufactured from a corrosion-resistant material with an elastic limit greater than 600MPa, in order to withstand pressures greater than <NUM> bar, such as for example <NUM>-5PH H900 or <NUM>. 8Mo H1000 steel. The angle of the seat is between <NUM>° and <NUM>°. The closing and opening of the valve <NUM> is produced by means of the translation of a rod <NUM> by means of an actuator <NUM>, which may be hydraulic. The rod is directly connected to the male seat <NUM> of the valve. Thus, a simple movement in the direction of the shaft of the plug and the machine produces the closing (<FIG>) or the opening of the valve (<FIG>). As it is a metal-to-metal seal, the use of high-pressure gaskets in contact with the liquid to be treated is avoided because they are very difficult to clean and can be a source of accumulation of organic matter, and therefore microorganisms, if they do not have a hygienic design, something very complicated if they are to withstand high pressure. This valve is easy to clean and is also very reliable and simple from a mechanical point of view. It separates the area that is subjected to high pressure from the one that must have a hygienic design.

In order to fill the bag with a product to be processed, the valve <NUM> of the plug 5a is opened (<FIG>). The product is in a tank <NUM> and is transferred through a three-way valve <NUM> to the inner filling and emptying duct <NUM> of the plug. Optionally, the product is passed through a filter <NUM> in case it is necessary to eliminate seeds, pulp or other particles, which helps to prevent any solid particles from remaining in the valve seats that could damage the sealing capacity, since the filtered product sweeps and cleans said particles. Once the bag <NUM> is full, the actuator moves the rod <NUM> and the valve closes (<FIG>). A tank with cleaning agent <NUM> (peroxide, steam or another compound with disinfecting action) is then opened, located on the outside of the vessel. The cleaning agent enters the plug by means of a pump <NUM> and, through a duct <NUM> in the product plug, reaches a chamber <NUM> and the rod <NUM>. The rod <NUM> has holes and a duct 11a therein such that the cleaning agent enters through the holes and flows through the interior of the rod to the end where the male seat <NUM> is located, exiting through it through other holes. In this way, the inner product filling/emptying duct <NUM> is cleaned and the agent returns towards the outer three-way valve <NUM>, which leads it to a drain <NUM>. The chamber <NUM> at the end of the duct <NUM>, through which the cleaning agent enters, is long enough to maintain the portion of the rod <NUM> that enters the duct <NUM> clean when the valve opens. Thus, the portion of the rod entering into the clean area is kept continuously in a bath of cleaning agent in order to ensure hygiene thereof when the valve is actuated.

The components of the duct <NUM> are preferably manufactured from austenitic stainless steel. These materials have high resistance to corrosion when exposed to certain liquid substances such as juices or other low-pH foods. This duct <NUM> helps to protect the structural material of the plug since it prevents direct contact thereof with the product to be pressurized. The plug is preferably made of stainless steels with an elastic limit greater than <NUM> MPa, preferably greater than 1000MPa, which have lower resistance to corrosion than austenitic steels.

The different portions of the duct <NUM> are joined by means of hygienic gaskets on which it is necessary to maintain a certain tension in order to ensure tightness. Furthermore, the plug undergoes deformations under pressure that cannot be absorbed by the elements <NUM>, <NUM> and <NUM> without the inclusion of an elastic element such as springs or an elastomer. The elastic elements <NUM> positioned at the distal end of the plug (end furthest from the bag) absorb the deformations of the plug due to the pressure and also maintain at all times the hygienic gaskets of the duct <NUM> with the tension necessary to ensure tightness.

At the end of the plug there is a connector <NUM> (<FIG> and <FIG>) adapted to connect the flexible bag <NUM>. This connection enables the filling and emptying of product from the bag <NUM> in a hygienic manner and in turn guarantees that throughout the high-pressure processing, the product to be processed is isolated from the pressure-transmitting fluid. The bag <NUM> is provided with a flexible female connector <NUM> attached thereto. The connector <NUM> joins a male connector <NUM> attached to the plug, by means of a joining flange <NUM> preferably made of plastic material and a fastening part <NUM> to which a hose, pipe or another system can be connected in order to facilitate emptying the bag. The male connector <NUM> in turn is in contact with the female seat <NUM> and the latter, in turn, is in contact with the inner filling/emptying duct <NUM>. The parts <NUM>, <NUM> and <NUM> may in some cases be one single part. Optionally, an elastomeric gasket <NUM> is placed between the male <NUM> and female <NUM> connectors in order to ensure tightness in the phases of the cycle in which there is no high pressure outside the bag, that is, during the product filling phase of the bag and during the extraction phase of the treated product from the bag. This gasket <NUM> receives the sealing pressure necessary in order confer tightness to the connection. As the pressure of the transmitting fluid increases, all the parts that make up the joint start to reduce their volume as a result of the effect thereof. Due to the different module of compressibility between steel and plastic, the connector <NUM> of the bag is increasingly compressed against the male connector <NUM> of the plug which, being metallic, barely reduces its volume, achieving a plastic-metal seal. The elastomeric gasket <NUM> is likewise compressed by recovering its volume in the depressurization and therefore the closing function thereof.

In reference to <FIG> and <FIG>, the method of pressurizing the product to be treated is as follows:
In order to place the bag <NUM> into the vessel <NUM>, the machine is provided with two wedges 21a, 21b that can be displaced laterally in a direction perpendicular to the main axis of the machine. Removing the wedges makes it possible to remove the plugs 5a, 5b and access the vessel. The vessel <NUM> is then moved transversally so that it stays outside the yoke that supports all the elements (not shown in the figure), so that access to it is achieved. Once the bag <NUM> is introduced, the vessel <NUM> is again moved transversally, recovering the alignment thereof with the yoke. The connection between the bag <NUM> and the product plug 5a is then carried out. Subsequently, the plugs 5a, 5b are again introduced into the vessel and the wedges 21a, 21b recover the initial position thereof. The product to be processed is then introduced through the duct <NUM> of the product plug (<FIG>). The air present in the vessel <NUM> exits through the plug on the opposite side 5b through the duct <NUM> through the opening of the aeration valve <NUM> and is expelled into the atmosphere through the valve <NUM>. Then (<FIG>), the pressure-transmitting fluid is introduced into the vessel by means of the pump (or pumps) <NUM> through the ducts <NUM> present in both plugs 5a, 5b. The pressure increases to the chosen recipe pressure, normally between <NUM>,<NUM> and <NUM>,<NUM> bar, and is maintained for a predetermined period of time (<FIG>), which is also defined by the recipe and adapted in each case to the product (liquid) to be processed. During this process (raising and maintenance of pressure) the product plug 5a is cleaned as described in reference to <FIG>. The cleaning agent is in a tank <NUM> and is brought into a chamber <NUM> by means of a pump <NUM> through the duct <NUM>. Once the duct has been cleaned, the cleaning agent is discharged through the duct <NUM> to the three-way valve that empties it into a drainage duct <NUM>. Once the pressure has been maintained for a set period of time and the product has been processed, a portion of the transmitting fluid introduced during the raise in pressure leaves the vessel through ducts <NUM>, due to the actuation of the relief valve or valves <NUM> (<FIG>) until the atmospheric pressure is reached. The actuator <NUM> then opens the valve <NUM> and the bag <NUM> starts to discharge with the help of pressurized air or inert gas, which reaches the vessel, pressing on the outside of the bag, through the duct <NUM> of the aeration plug 5b from a tank <NUM> (<FIG>) upon opening the aeration valve <NUM>. The pressure of the air or inert gas acts on the outside of the flexible bag <NUM>, facilitating the emptying thereof, making the product pass, through the connector <NUM>, through the duct <NUM> of the plug 5a to the processed product tank <NUM> through the valve <NUM>. Finally, the entire processed product remains in the tank <NUM> and the bag empties (<FIG>). Once the transfer of the processed product to the tank <NUM> has been completed, the pressure of the remaining air or gas in the vessel <NUM> is released through the valve <NUM>, leaving the equipment ready to start of a new processing cycle, changing the bag <NUM> if necessary. The new processing cycle would begin by introducing new product to be processed (<FIG>), and it is not necessary to carry out machine movements if the bag <NUM> is not changed, an action that is not carried out in every cycle. Once the product of the tank <NUM> is confirmed as suitable, it is transferred to the filling or storing equipment, propelled by air or inert gas proceeding from the tank <NUM> and filtered through a sterile filter <NUM> to avoid possible contamination of the product.

Thanks to the product plug, the filling/emptying duct with the product to be processed is not subjected to high pressure, so that the cleaning of said duct with a cleaning agent (such as steam or peroxide) is easier, since easily cleaned gaskets and corrosion-resistant materials can be used in the design thereof. Furthermore, it prevents the complicated pipes, couplings and valves in contact with the fluid to be treated from being subjected to fatigue, due to the high pressure and therefore cause cleaning problems due to the growth of microorganisms inside cracks.

The invention, in comparison with other previous solutions, is mechanically simple, such that from a mechanical reliability point of view it is robust, the areas subjected to high pressure being as small as possible. Thanks to the invention, which clearly separates the areas that must have a hygienic design from those that must be designed to withstand high pressure, hygienic and mechanical reliability are high. Furthermore, the two areas are separated by a metal-to-metal seal that is easy to clean and significantly reliable from a mechanical point of view. The liquid to be treated is prevented from being pressurized in the areas with elastomeric gaskets where it is necessary to carry out high-pressure sealing, the high-pressure supporting design of which does not make them easy to clean or suitable from a hygienic point of view. It also prevents the pipes from being subjected to high pressure by means of the fluid to be treated, which could generate fatigue cracks where microorganisms could develop, the cleaning thereof being very complicated and it enables the use of corrosion resistant materials.

Claim 1:
A product plug (5a) for high-pressure processing machines with a bag (<NUM>), wherein the plug comprises a duct for the passage of a pressure-transmitting fluid (<NUM>), another duct (<NUM>) for filling and emptying with a product to be pressurized in the bag (<NUM>) and a seat valve (<NUM>) with a male seat (<NUM>) and a female seat (<NUM>) in order to enable or prevent passage of the product into the bag, the other duct (<NUM>) is a filling and emptying duct (<NUM>) for both filling the bag with product and for the outlet of said already processed product, the plug being provided with a rod (<NUM>) on the inside of the filling and emptying duct (<NUM>) for closing and opening the valve (<NUM>), wherein the rod (<NUM>) is joined to the male seat (<NUM>) and is provided with an inner duct (11a) joined to a cleaning agent chamber (<NUM>), which in turn is joined to an inlet duct of said cleaning agent (<NUM>) and wherein the rod (<NUM>) and the male seat (<NUM>) are provided with holes for the passage of the cleaning agent, characterized by the male seat (<NUM>) forming with the female seat (<NUM>) a metal-to-metal seal without high-pressure gaskets.