WO2011131963A2

WO2011131963A2 - Food or beverage processing system and method

Info

Publication number: WO2011131963A2
Application number: PCT/GB2011/050713
Authority: WO
Inventors: William Timothy Burrow
Original assignee: William Timothy Burrow
Priority date: 2010-04-19
Filing date: 2011-04-11
Publication date: 2011-10-27
Also published as: WO2011131963A3; GB201006490D0

Abstract

A food or beverage processing system (110, 210) is disclosed that may be connected to a clean-in-place system (120) having a recirculation line (130, 230) such that a recirculation loop is formed to recirculate an aqueous disinfectant solution through the food or beverage processing system (110, 210), wherein an electrochemical reactor (140) is placed in the recirculation line (130) to generate the aqueous disinfectant solution by electrolysis of water molecules into oxidizing species. A method of disinfecting such a food or beverage processing system and a clean-in-place system (120) for a food or beverage processing system are also disclosed.

Description

FOOD OR BEVERAGE PROCESSING SYSTEM AND METHOD

FIELD OF THE INVENTION

The present invention relates to a clean-in-place system for disinfecting a food or beverage processing system, the clean-in-place system comprising a recirculation line for forming a recirculation loop with the food or beverage processing system to recirculate an aqueous disinfectant solution through the food or beverage processing system.

The present invention further relates to a food or beverage processing system including such a clean-in-place system.

The present invention further relates to a method of disinfecting such a food or beverage processing system.

BACKGROUND OF THE INVENTION

In the food & beverage processing industry, large volumes of water are used in various cleaning and/or disinfection processes, such as in food & beverage manufacture and food & beverage pasteurization. For instance, in food & beverage manufacture, a manufacturing set-up is typically configured to produce batches of food or beverages, such that following the successful production and packaging of a batch of a food or beverage, the production lines have to be cleaned to ensure that the production lines remain substantially free of contaminations. Such contaminations may include residues of the last produced food or beverage, which require removing for various reasons, for instance because the next food or beverage batch comprises a different formulation, e.g. a different taste and/or odour, or because the residues can cause the build-up of microbial contamination in the system, which is unwanted for obvious reasons.

From a cost-perspective, it is important that the cleaning of the food or beverage processing system is completed as quickly as possible, to limit the amount of down-time of the system. To this end, most food or beverage manufacturing lines are equipped with so-called clean-in-place (CIP) systems, in which a number of wash solutions in separate storage tanks can be connected to the food or beverage manufacturing line via a system of valves, such that dismantling of the manufacturing line is not required. The CIP system typically comprises one or more rinse solutions, a disinfectant solution and a caustic soda solution that are sequentially recirculated through the food or beverage manufacturing lines until these lines are sufficiently clean. As each tank typically contains several thousands of litres of the solution, which may require disposal of following completion of the cleaning cycle, large volumes of contaminated water can enter the waste water stream in this manner. This can add to the cost of the manufacturing process, as the manufacturer may be charged for the disposal of the contaminated water streams on a volume basis, as well as on a contamination level basis.

A similar problem exists in a food or beverage pasteurization line, where bottled or canned food or beverages are pasteurized by showering or immersing them in different showering or immersion bath stages with water containing disinfectant at different temperatures. The presence of chemicals in the water inter alia has the purpose of preventing the build-up of a biological film on the food or beverage containers and on the surfaces of the pasteurizer. The system sometimes incorporates a cooling tower for waste water recovery.

The various shower stages are aligned between an entrance and an exit of the food or beverage pasteurization line, wherein the stages implement a gradual increase followed by gradual decrease in temperature such that the food or beverage in the containers is gradually heated to the appropriate pasteurization temperature, which may be around 70°C, and gradually cooled down again.

Despite the gradual nature of the temperature increase and decrease, occurrences of container breakage cannot be avoided, in particular when using glass bottles. In the event of such a breakage or leakage, the transport medium of the containers through the pasteurization stage, e.g. a conveyer belt, is stopped to allow for a rectification of the problem. However, to avoid the intact containers from becoming overexposed to the pasteurization temperature, which would detrimentally affect the taste and shelf life of the food or beverage, large amounts of cold water are poured over the stationary containers, which are typically fed straight into a waste water stream.

In addition, the breakage and leakage causes the spill of the food or beverage into the aqueous disinfectant solution, which consumes disinfectant in the solution as biological oxygen demand (BOD) and chemical oxygen demand (COD) entered into the solution by the food or beverage spillage, e.g. proteins and carbohydrates in the food or beverage, is neutralized. Hence, the chemicals in the disinfectant comprising solution require regular topping-up, thus adding to the cost of the pasteurization process.

PCT patent application with publication number WO 2009/089599 A2 discloses a system using electrochemically activated water for manufacturing, processing, packaging and dispensing beverages. The electrochemically activated water is used for the neutralization of incompatible residues when transitioning from the production of one beverage to another and in the beverage CIP system to achieve improved microbial control at reduced water consumption levels as well as reduced amounts of chemical detergent and disinfectants. To this end, an electrolyte solution such as a NaCI or KCI solution is electrochemically activated in the reactor, and subsequently transferred into a storage tank in the CIP system, where the electrochemically activated anolyte and catholyte solutions can be used to clean and/or disinfect the beverage production lines.

This system has some notable drawbacks, such as the fact that the electrochemically activated aqueous saline solution has to be generated before it can be used in the CIP system. On the other hand, if the production of the electrochemically activated aqueous saline solution can be performed in parallel with the execution of such a CIP cycle, this adds complexity to the CIP system in the form of additional storage tanks and the necessary software integration and control systems, often across multiple supplier platforms. Furthermore, since the electrochemically activated aqueous saline solution is typically generated in a concentrated form, the CIP system requires a dilution stage to lower the disinfectant (anolyte) and detergent (catholyte) concentration to the appropriate level, thus further adding complexity to the CIP system.

Also, the electrochemically activation of aqueous saline solutions typically results in the formation of hypochlorous acid, hypochlorite and remaining chlorides, which is highly corrosive to stainless steel. For this reason, many existing production lines refuse to apply chlorine-based agents in their CIP system to prevent any damage to the beverage production lines. An on-line document from a company called Gorman Controls Ltd.; ECA Water Treatment Technology of the Wine Industry; http://www.gormancQntrols.com/userfiles/docs/wineindustrv.pdf teaches the generation of electrochemical ly activated solutions (Ecasol) from a diluted salt solution, including an alkaline reductant -(catholyte) and a neutral oxidant - (catholyte) for storage in a tank prior to use as a disinfectant in a wine processing system.

A paper by Carlos Alberto Martinez-Huitle, "Conductive Diamond Electrodes for Water Purification" in Materials Research 2010, Vol. 10 (4), 2007, pages 419-424 discloses that conductive diamond electrodes can be used for chemical-free water treatment, such as water disinfection /purification. This paper further discloses that diamond electrodes can successfully reduce bacteria and sugar content, and furthermore suggests that electrochemical disinfection can be achieved in chlorine-free media when forming strong oxidizing species by electrolyzing water.

US 2006/0261349 A1 discloses an electrochemical cell comprising a conductively doped (e.g. boron-doped) single crystal diamond electrode. The cell is used for water purification in chloride free media and reports the improved stability of single crystal diamond over polycrystalline diamond when used in electrodes requiring high current densities to generate ozone.

WO 03/010094 A1 addresses the problem of micro-organism contamination in fluid supply lines in industrial settings, such as beverage supply lines. It discloses a cleaning system for controlling bacteria growth in beverage lines such as beer lines by water treatment in an electrolytic cell such that the treated water has high levels of dissolved oxygen. The electrolytic cell may be placed in an in-line cartridge that is fitted directly into a beverage line. The electrolytic cell may be used in a single charge mode in which oxidants are generated on-the-fly. The system may further comprise sensing devices for monitoring contamination levels in the water.

It is concluded that although prior art solutions exist that allow for the generation of chloride-free disinfectant, these solutions do not address the problem of waste water volume and its treatment for reuse, which can significantly add to the cleaning cost of a beverage manufacturing set-up as previously explained. SUMMARY OF THE INVENTION

The present invention seeks to provide an improved food or beverage processing system.

The present invention further seeks to provide an improved method of cleaning and disinfecting a food or beverage processing system.

In accordance with an aspect of the present invention, there is provided a clean-in place system for disinfecting a food or beverage processing system, the clean-in place system comprising a recirculation line for forming a recirculation loop with the food or beverage processing system to recirculate an aqueous disinfectant solution through the food or beverage processing system; and an electrochemical reactor placed in the recirculation line for generating the aqueous disinfectant solution by electrolysis of water molecules into oxidizing species.

The present invention has been based on the insight that instead of generating oxidizing moieties from electrolytes such as NaCI and KCI in electrochemically activated water, the water itself can be chemically activated by converting water molecules (and trace mineral salts if present) into oxidizing species such as hydroxide radicals, ozone, peroxicarbonates, peroxodisulphates, and hydrogen peroxide (H2O2). This has far reaching implications, as the electrochemical reactor may be placed in-line in the recirculation flow defined by a recirculation loop when the CIP system is connected to the food or beverage processing system, as opposed to the prior art solution of WO 2009/089599 A2 in which the recirculation flow does not pass through the reactor. More importantly, it has been found that by the placement of such a reactor in a recirculation loop with the food or beverage processing system, the contaminant levels in the cleaning solutions resulting from the cleaning of the food or beverage processing system can be reduced to such an extent by the electrochemical reactor that the cleaning solution can be reused for several additional cleaning cycles of the food or beverage processing system whilst still complying with the relevant quality regulations, thus significantly reducing the volumes of waste water produced in the cleaning of the food or beverage processing system. Also, the top-up of oxidizing moiety precursors such as NaCI or KCI may no longer be required, and the concentration of the oxidant concentration in the aqueous disinfectant solution can be easily controlled by the flow rate through the electrochemical reactor and the operating voltage and/or amperage applied to the electrochemical reactor, such that the need for a dilution stage has been obviated due to the presence of the oxidation species in the electrolyte water.

In a particularly suitable embodiment, the electrochemical reactor comprises an anode and a cathode, each comprising a boron-doped diamond (BDD) surface. Compared to other types of anode and cathode materials, BDD electrodes, which may comprise a substrate coated with a layer of BDD or may comprise electrodes solely formed of BDD wafers or BDD electrodes bonded to a conductive substrate such as Ti or silicon without the substrate being exposed to electrolyte, and have superior properties because they can withstand higher voltages and amperages compared to non-diamond based electrodes. This not only facilitates the electrolysis, i.e. electrochemical cleavage, of water molecules, but furthermore facilitates the combustion of contaminants such as BOD and COD contaminants. Consequently, in most scenarios, not only is there is no need to add oxidant precursors to the aqueous disinfectant solution, but reduced amounts of water for recirculation through the food or beverage handling stage are required due to the self- cleaning nature of the BDD-based electrochemical reactor, which means that a unit water volume may be recirculated through the food or beverage handling stage a significantly increased number of times compared to prior art solutions, thereby reducing the frequency of disposal of the unit volume of water in the form of waste water as previously explained.

Nevertheless, the clean-in-place system of the present invention may comprise a chemicals reservoir connected to the circulation network via a valve for the addition of an oxidant precursor compound to the recirculation line. Such additions may for instance further increase the oxidant content in case the oxidant levels generated by the electrolysis of the water are or become insufficient to reduce the contaminant levels in the food or beverage handling stage at an acceptable rate. Preferably, the recirculation line further comprises a sensor for sensing a value of a chemical parameter in the aqueous disinfectant solution, wherein the valve is responsive to said sensor such that the oxidant precursor can be automatically added to the aqueous disinfectant solution.

In a preferred embodiment, the chemicals reservoir comprises a sodium/potassium-based electrolyte selected from the group consisting of NaOH, Na₂SO₄., K₂SO₄, KHCO₃, and NaHCO₃ such that the formation of the corrosive chlorides can be avoided, thus enabling the use of the aqueous disinfectant solution in stainless steel-comprising food & beverage processing systems.

The recirculation line may further comprise a venting stage for removing hazardous gases from the clean-in-place system.

At this stage, it is noted that BDD electrode-based electrochemical reactors are known per se. Such reactors typically find their use in waste water treatment, in which the purifying properties of the BDD electrodes are used to reduce e.g. BOD, COD, hard TOC, pharmaceutical, hazardous, toxic and microbial, e.g. E-Coli, contamination in waste water. Such electrochemical cells are for instance marketed by Advanced Oxidation Ltd. ^® in the UK and by Condeas GmbH^® in Germany. Examples of BDD-based electrochemical cells can be found on the respective websites of these companies: http://www.advoxi.com and http://condias.de. Also, an overview of the use of BDD technology in contaminated water processing is given in an article by C.A. Martinez-Huitle in Materials Research, 10(4), 2007, pages 419- 424.

However, one of the insights of the present invention is that BDD technology can also be used for disinfecting purposes in the food or beverage industry for the purpose of reducing chemical usage and more importantly waste water volumes by the specific arrangement of such an electrochemical reactor in-line in the circulation network of a food or beverage processing system. Hence, the primary use of the BDD technology is for the purpose of in-situ generation of a disinfectant-containing aqueous solution for disinfecting a food or beverage handling stage in a different location. This is completely different to the purpose of the BDD technology in waste water treatment, where the purpose of the BDD technology is to treat waste water inside the BDD electrochemical reactor. This does not provide any insight that water wastage may be reduced by treatment of a disinfectant solution during recirculation through a remote stage, such that an increased number of recirculation cycles can be achieved before the disinfectant solution has to be disposed of. In particular, in waste water management, there is no reduction in the volume of water to be disposed of, but rather a reduction of the organic or toxic load.

The clean-in-place (CIP) system may further comprise a rinse water container, wherein the circulation line is further adapted to recirculate the rinse water through the recirculation loop when connected to the food or beverage processing stage. This further reduces the amount of waste water that is produced by such a CIP system, as the rinse water is recirculated through the electrochemical reactor, thereby -disinfecting the rinse water.

In accordance with another aspect of the invention, there is provided a food or beverage processing system comprising the clean-in-place system of the present invention. The food or beverage processing system may comprise a food or beverage manufacturing line that is configurably connected to the recirculation line and/or a pasteurizing chamber for pasteurizing filled food or beverage containers, the pasteurizing chamber comprising an entry and an exit; a transport medium for transporting the food or beverage containers from the entry to the exit; a plurality of wetting stages arranged between the entry and exit and over the transport medium, each wetting stage being arranged to wash the food or beverage containers with the aqueous disinfectant solution at a predefined temperature; and a collection reservoir for collecting the aqueous disinfectant solution, the recirculation line connecting the collection reservoir to the plurality of wetting stages, wherein the the wetting stages are shower stages or immersion stages.

This has the advantage that the aqueous disinfectant solution less often requires replacing, and that the amount of chemicals required for maintaining the quality of the aqueous disinfectant solution can be reduced, thereby providing a more cost-efficient implementation of a food or beverage production system including a food or beverage manufacturing stage and/or a pasteurization stage. In accordance with another aspect of the present invention, there is provided a method of disinfecting a food or beverage processing system including the clean in place system of the present invention, the method comprising generating the aqueous disinfectant solution by applying a water- electrolyzing voltage across the electrochemical reactor, whilst feeding a water-based fluid through the electrochemical reactor. In an embodiment, the aqueous disinfectant solution is subsequently recirculated through the recirculation loop. The method of the present invention facilitates a reduction in chemicals used as well as a reduction of the waste water volume generated in such disinfecting procedures.

In an embodiment, the method further comprises monitoring a value of a chemical parameter of the aqueous disinfectant solution; and adding an oxidant precursor to the aqueous disinfectant solution in case said value falls outside a predefined range, such that it is ensured that the aqueous disinfectant solution consistently complies with the quality requirements of the disinfecting procedure.

In the case of an electrochemical cell comprising BDD electrodes, the method may further comprise periodically reversing the polarity of the anode and cathode. This has the advantage that the build-up of deposits such as scale on the electrodes is prevented. This embodiment is particularly suitable for use with electrodes that are formed from a BDD wafer, i.e. that are solid BDD electrodes as opposed to electrodes coated with an anode- or cathode- active material, as coated electrodes can suffer from the delamination of the coated active material when exposed to a polarity reversal. This is particularly the case if the electrode comprises a titanium carrier.

In accordance with another embodiment of the method of the present invention, the recirculation of the aqueous disinfectant solution may be terminated when the contaminant level in the food or beverage handling stage falls below a predefined threshold. This can be monitored by evaluating key parameters, e.g. pH, oxidants such as FAC (Free Available Chlorine) electrical conductivity (EC) and oxidation-reduction potential (ORP) of the aqueous disinfectant solution, as these parameters may provide a reasonably accurate estimation of the amount of microbial contamination in the food or beverage handling system. BRIEF DESCRIPTION OF THE EMBODIMENTS

Embodiments of the invention are described in more detail and by way of non-limiting examples with reference to the accompanying drawings, wherein

FIG. 1 schematically depicts a food or beverage processing system in accordance with an embodiment of the present invention including a CIP system;

FIG. 2 schematically depicts a food or beverage processing system in accordance with another embodiment of the present invention including a pasteurization system;

Fig. 3 depicts the effect of recirculating a first set of contaminated sample solutions through a BDD reactor on the microbial content of these sample solutions; and

Fig. 4 depicts the effect of recirculating a second set of contaminated sample solutions labeled A-D through a BDD reactor on the microbial content of these sample solutions. DETAILED DESCRIPTION OF THE DRAWINGS

It should be understood that the Figures are merely schematic and are not drawn to scale. It should also be understood that the same reference numerals are used throughout the Figures to indicate the same or similar parts.

FIG. 1 shows a food or beverage manufacturing system 100 in accordance with an embodiment of the present invention. The food or beverage manufacturing system 100 comprises a food or beverage processing system 1 10 and a clean-in-place (CIP) system 120. The configuration of the food or beverage processing system 1 10 is not essential to the present invention, as the present invention may be applied in the manufacture of any suitable food or beverage, e.g. non-carbonated soft drinks including water, carbonated soft drinks, beer, wine, spirits, dairy products and so on. To this end, the food or beverage processing system 1 10 may comprise filling lines for transferring the food or beverage into any suitable packaging, e.g. bottles, cans, cartons and so on, syrup tanks, mixing tanks, filtration systems, process tanks and so on.

The food or beverage processing system 1 10 is typically configurably connected to the CIP system 120, here schematically shown by inlet 122 into the CIP system 120 and outlet 124 into the food or beverage manufacturing system 1 10, e.g. by using suitable valves such as solenoid valves. This is schematically represented by valves 161 and 162. The configurable nature of the connection between the food or beverage processing system 1 1 0 and the CIP system 120 is to isolate the CIP system 120 from the food or beverage processing system 1 10 during food or beverage manufacturing and to connect the CIP system 120 to the food or beverage processing system 1 10 for cleaning the food or beverage processing system 1 10. The food or beverage processing system 1 10 typically requires cleaning after completion of the manufacture of one or more batches of a food or beverage, for instance to remove build-up of residue in the food or beverage processing system 1 10 that can cause microbial growth in the system, as well as residue that is incompatible, e.g. because of a different colour, taste or smell, with the next food or beverage to be manufactured. Other reasons for cleaning a food or beverage processing system 1 10 will be apparent to the skilled person.

The cleaning process of a food or beverage processing system 1 1 0 typically comprises a number of sequential treatment cycles. There are many different CIP protocols well-known to the skilled person. For instance, a typical CIP protocol may comprise the following cycles or permutations and combinations thereof:

- a pre-rinse with treated water at ambient temperature;

- a detergent cleaning step at ambient temperature or heated to 50- 80°C;

- an intermediate rinse with treated water at ambient temperature ;

- a disinfectant step at ambient temperature; and

- a final rinse step at ambient temperature.

It is reiterated that this is just one of many possible approaches, with many permutations possible as the most suitable protocol will depend on a large number of process parameters like the nature of the product and associated contamination to be removed, the required sanitation level, size and complexity of products manufactured of the food or beverage processing system 1 10 and so on.

In order to implement such a cleaning protocol, a CIP system typically comprises a number of storage tanks in which the various solutions to be used are stored. The contents of such tanks need frequent replenishing as the aqueous solutions used in some of the CIP cycles are directly disposed of, whilst the lifetime of recirculated solutions is limited due to the build-up of contamination in the solutions that is removed from the food or beverage processing system 1 10. The direct consequence of such replenishing is consumption of water and chemicals, as well as the disposal of end-of-life solutions to waste, for which a handling charge is typically payable, which can depend on the volume and/or contamination levels in the waste product.

In accordance with an embodiment of the present invention, a CIP system 120 is provided that includes a recirculation line 130 for recirculating solutions from and to the food or beverage processing system 1 10. The recirculation line 130 may be configurable, i.e. may comprise a branched network of paths that can be selectively combined to configure the recirculation line 130. When connected to the food or beverage processing system 1 10, the recirculation line 130 and the food or beverage processing system 1 10 form a recirculation loop through which a fluid may be recirculated, such that the fluid can pass through the food or beverage processing system 1 10 several times. The CIP system 120 may include a number of storage tanks 150, 152, 154, (these are pre-existing tanks and are part of a conventional CIP system and should be part of 120), which may be connected to the recirculation line 130 or may be placed in the recirculation line, for instance a storage tank 1 50 comprising a rinse medium, e.g . water, a storage tank 152 comprising a disinfectant solution and a storage tank 154 comprising a detergent, e.g. a caustic soda solution. A pump 132 is also included for recirculating the above solutions through the food or beverage processing system 1 10, e.g. between a selected storage tank if included in the recirculation loop and the food or beverage processing system 1 10. In order to select the appropriate storage tank, a number of valves 164-169 may be provided. Any suitable number of pumps may be included in the recirculation loop, and they may be placed in any suitable location in this loop, e.g. in any suitable location in the recirculation line 130.

The CIP system 120 further comprises an electrochemical reactor 140 in the recirculation line 130 for electrolyzing water. Preferably, the electrochemical reactor 140 comprises an anode and a cathode (not shown) that are either coated with boron-doped diamonds or that are entirely made of boron-doped diamonds. Although a single reactor 140 has been shown it should be understood that multiple reactors either in parallel or in series can also be used. The advantages of using electrodes comprising synthetically manufactured diamonds to which a boron contamination has been added will be explained in more detail below.

The electrochemical reactor 140 may be configured to perform the following half reactions at the cathode and anode: 2H₂O→ 2ΗΟ· + 2H⁺ + 2e^" (anode)

2H⁺ + 2e^"→ H₂ (cathode)

The hydroxyl radical formed in the anode reaction is a powerful oxidizing species, i.e. an oxidant, which can be used for disinfection purposes in the food or beverage manufacturing system 1 10. Hence, the electrochemical reactor 140 may be used for an in-situ disinfection and generation of the aqueous disinfectant solution for the storage tank 152 without requiring the addition of any further chemicals. For instance, during food or beverage manufacturing, the electrochemical reactor 140 may be connected between a water source (not shown) and the storage tank 152 by opening respective valves 171 and 166 such that the storage tank 152 can be filled with the disinfectant solution that is in-situ generated by the inclusion of the electrochemical reactor 140 in the recirculation line 130.

Once the storage tank 152 has received the required volume of aqueous disinfectant solution, valve 171 may be shut. In order to increase the concentration of the radical formed in the anode reaction of the electrochemical reactor 140 in the aqueous disinfectant solution, valve 163 may be opened such that the disinfectant solution is recirculated from and to the storage tank 152 through the electrochemical reactor 140. In an alternative embodiment, the recirculation tank 152 has been omitted from the CIP system 120.

The CIP system 120 may further comprise a venting stage 142 placed directly behind the electrochemical reactor 140 for venting the hydrogen gas generated in cathode reaction of the electrochemical reactor 140. The removal of the hydrogen gas from the system eliminates the risk of explosion caused by excessive build-up of hydrogen gas in the system.

Upon disinfecting the food or beverage processing system 1 10 with the aqueous disinfectant solution, the solution may be recirculated through the recirculation loop formed by the connection of the recirculation line 1 30 to the food or beverage processing system 1 10. The recirculation loop includes the electrochemical reactor 140, the venting stage 142 and, if present, may include the storage tank 152 by opening valves 161 , 166, 167 and 162. This has the advantage that any oxidant consumed in the food or beverage processing system 1 10 is replenished by the water electrolysis in the electrochemical reactor 140. Moreover, as the electrochemical reactor 140, and in particular a BDD-based reactor, is capable of converting contaminants such as sulphates and carbonates into oxidizing species such as peroxodisulphates (S2O8^2") and peroxodicarbonates (C2O6^2") respectively, contaminants collected from the food or beverage processing system 1 10 can be converted into species that can be used to further disinfect the food or beverage processing system 1 10. In an embodiment, upon initiating a CIP cycle through the food or beverage processing system 1 10, a first fraction, e.g. a first few thousand litres, of the solution used, e.g. the aqueous disinfectant solution, may be disposed to waste before recirculating the solution through the recirculation loop formed by the recirculation line 130 and the food or beverage processing system 1 10.

The CIP system 120 may further comprise a flow sensor 134 and a further sensor 136 for monitoring process parameters of the fluid to be processed by the electrochemical reactor 140, such as Brix, which is a measure of sugar content in liquids, pH, EC and ORP. The readings of these sensors may be monitored, and the operation of the CIP system 120 appropriately adjusted based on these sensor readings, for instance by controlling the flow rate through the recirculation loop, which may be controlled by the drive voltage of the circulation pump 132, and/or by controlling the voltage and amperage across the anode and cathode of the electrochemical reactor 140. Other suitable sensors may be included in the CIP system 120 to supplement sensors already existing in the CIP system. Preferably, the sensors are placed in the recirculation line 130.

In a preferred embodiment, the CIP system 120 comprises such sensors before and after the electrochemical reactor 140, such that the effect of the electrochemical reactor 140 on the constitution of the solution passing through the electrochemical reactor 140 can be monitored. This facilitates taking action, e.g. adjusting the operational parameters of the electrochemical reactor 140 in case the sensor readings indicate a deviation from the intended performance of the electrochemical reactor 140.

In an embodiment, the CIP system 120 further comprises a storage tank 156 that is connected to the recirculation line 130 via valve 170. The storage tank 156 may contain an oxidant precursor solution for insertion into the recirculation line 130, for instance when sensor readings indicate that the ORP of the solution pumped through the circulation network 130 has fallen below a predefined threshold, e.g. below 600 mV, as this value is known to be the minimum redox potential at which micro-organisms can be successfully destroyed.

Upon detection of the monitored threshold falling below the predefined threshold, the valve 170 may be opened for a predetermined period of time to increase the oxidant content in the recirculated solution. The storage tank 156 preferably is connected to the recirculation line 130 in front of the electrochemical reactor 140, as the electrochemical reactor 140 will convert the oxidant precursor into the corresponding oxidizing species. The oxidant precursor solution formed in the electrochemical reactor 140 is preferably chloride-free to prevent the presence of corrosive chlorides that are detrimental to stainless steel in the food or beverage manufacturing stage 1 10. Suitable oxidant precursors include Na₂SO , K₂SO , KHCO₃ and NaHCO3. In addition NaOH may be used to create a combined cleaning/disinfectant solution.

At this stage, it is reiterated that a BDD-based electrochemical reactor 140 is particularly suitable for inclusion in a CIP system 120 as it exhibits the following advantageous properties in addition to the already mentioned advantageous properties:

- ammoniacal nitrogen is converted into N₂;

- organic compounds are converted into CO2 without sludge formation;

- hard COD and BOD can be broken down;

- amperages can exceed 5000A meter sq

- voltages of over 200 V can be applied; and

- the anode/cathode polarity can be reversed

This compares favorably to electrochemical reactors using Ti-based electrodes, which are limited to voltages up to 30 V and tend to delaminate the electrode-active materials upon anode/cathode polarity reversal. The lower voltage prohibits the effective breakdown of COD, BOD, organic compounds and so on. As most of the breakdown products produced by the electrochemical reactor 140 are gases, these breakdown products may be easily removed from the CIP system 120 using the vent stage 142.

Because of the cleaning properties of the electrochemical reactor 140, other solutions used in the CIP system 120 may also be recirculated through the electrochemical reactor 140. For instance, the rinse water in storage tank 150 may be recirculated by including the electrochemical reactor 140 in the recirculation path, such that the electrochemical reactor 140 is used to reduce the microbiological and contaminant levels in the rinse water, thus facilitating reuse of the rinse water. This may for instance be achieved by reconfiguring the recirculation line 130 using the valves 161 -167 to bypass the food or beverage processing system 1 10 followed by recirculation of a contaminated batch of disinfectant or rinse solution between a storage tank such as storage tank 150 and the electrochemical reactor 140.

It is equally feasible to exclude the electrochemical reactor 140 from certain recirculation paths. For instance, the detergent solution storage tank 154 can be connected in a recirculation loop with the food or beverage processing system 1 10 without including the electrochemical reactor 140 in this loop. It should be understood that the CIP system 120 in FIG. 1 is shown by way of non-limiting example only. Other configurations are equally feasible, for instance CIP systems that contain further storage tanks in addition to storage tanks 150, 152, 154, that contain separate recirculation loops for at least some of the storage tanks and so on. The CIP system 120 may be fully automated or may require some form of manual intervention. Any suitable CIP configuration may be adopted.

The application of an electrochemical reactor 140 in a food or beverage processing system is not limited to the CIP system 1 20 for cleaning a food or beverage processing system 1 10. An alternative use of the electrochemical reactor 140 is shown in FIG. 2, which depicts a pasteurization stage 210 of a food or beverage processing system 200. The pasteurization stage 210 typically comprises a transport medium 215 such as a conveyer belt to transport filled food or beverage containers 240, e.g. bottles or cans, received from a food or beverage manufacturing stage such as stage 1 10 in FIG. 1 through the pasteurization stage 210.

The pasteurization stage 210 further comprises a number of wetting stages for washing and heating the food or beverage containers 240, which may be shower stages or immersion stages. Five shower stages 221 -225 are shown in FIG. 2 by way of non-limiting example as other numbers of shower or other types of heating and cooling stages, e.g. immersion stages, are equally feasible. The shower stages 221 -225 are arranged to shower an aqueous disinfectant solution onto the packages 240, with the different shower stages being arranged to deliver the aqueous disinfectant solution at different temperatures such that the food or beverage in the packages 240 in gradually heated to the appropriate pasteurization temperature and gradually cooled down again. The aqueous disinfectant is to prevent growth of microbial organisms including biofilm. Gradual heating is required to avoid too rapid thermal expansion of the food or beverage inside the package 240 as the associated stress on the package 240 can cause it to break, thereby spilling the food or beverage into the pasteurization system 210. In order to bring the aqueous disinfectant solution to the appropriate temperature, at least some of the shower stages 221 -225 may comprise a heat exchanger (not shown). Some of the shower stages 221 -225 may share the same heat exchanger. The exact configuration is not essential to the present invention.

The pasteurization system 210 further comprises a collection unit 250 for collecting the aqueous disinfectant solution. The collection unit 250 feeds into a recirculation line 230 including a circulation pump 232 for recirculating the aqueous disinfectant solution between the collection unit 250 and the shower stages 221 -225. This may include a cooling tower. The recirculation line 230 further comprises the electrochemical reactor 140, preferably a BDD- based reactor, and may include a storage tank 260 for the aqueous disinfectant solution.

A disinfectant solution is used in a pasteurizing stage 210 for a number of reasons. For instance, upon spillage of the food or beverage into the pasteurizing stage 210, organic contaminants including BOD and COD enter the recirculation line 230 of the pasteurizing stage 210, which require neutralization to avoid the deposition of these contaminants onto the packages 240 and to avoid the growth of microbial contamination, e.g. biofilms, algae, bacteria, viruses and fungi, inside the recirculation line 230. In known pasteurizing stages, a cocktail of chemicals such as bromine, ozone, peracetic acid, phosphoric acid, sulphuric acid and suitable scale inhibitors may be used to neutralize such contamination. Consequently, such prior art pasteurizing stages require a relatively large number of storage and dilution tanks for the different chemicals, which are typically dosed into the recirculation line 230 at different points.

The complexity of such pasteurizing stages can be greatly reduced by the inclusion of the electrochemical reactor 140 in the recirculation line 230 of the pasteurizing stage 210, as at least some of the aforementioned chemicals may be omitted because of the ability of the electrochemical reactor 140 to generate oxidizing species, e.g. hydroxyl radicals that break down microbial contamination as well as to convert COD and BOD into e.g. CO2. The inclusion of the electrochemical reactor 140 in the recirculation line 230 of the pasteurizing stage 210 further ensures a reduction of the amount of chemicals consumed in the pasteurizing stage 210, as well as a reduction of the amount of waste water produced as the cleaning properties of the electrochemical reactor 140 extend the lifetime of the aqueous disinfectant solution.

In an embodiment, the recirculation line 230 further comprises a loop 270 from the storage tank 260 to the electrochemical reactor 140 to allow exclusion of the pasteurizing stage 210 from the recirculation loop. This may be implemented in any suitable manner, e.g. by using valves 271 and 272. The loopback path 270 may be utilized when the pasteurizing stage 210 is not in use to either generate a fresh batch of aqueous disinfectant solution or to purify the aqueous disinfectant solution stored in the storage tank 260.

It should be understood that the food or beverage processing system 200 has been shown by way of non-limiting example only, and that modifications may be made without departing from the teachings of the present invention. For instance, further storage tanks may be connected to the recirculation line 230 and sensors, e.g. a flow sensor, a pH sensor, a T° sensor, an oxidant sensor, an EC sensor, an ORP sensor and so on may be present. For instance, the CIP system 1 20 shown in FIG. 1 is equally suitable for use with a pasteurization stage 210 as shown in FIG. 2. Further, alternative configurations of the pasteurizing stage 210 and/or the recirculation line 230 are equally feasible.

The suitability of a BDD electrochemical reactor 140 for placement in a recirculation line 130 between the CIP system 120 and the food or beverage processing system 1 10 will now be demonstrated by the following non-limiting examples.

Experimental example 1

Five micro-organism species were selected to represent the aerobically growing yeast and bacteria as well as the anaerobically growing bacteria typically found in a beverage brewing environment. Cultures of Lactobacillus and Pediococcus were grown in MRS (de Man, Rogosa & Sharpe) broth, Acetobacter in WLN (Wallerstein Nutrient) broth and Saccharomyces cerevisiae and Saccharomyces diastaticus in YM (Yeast Malt) broth. These 5 cultures were spiked into 101 of 3 different aqueous solutions - a) sterile Ringers (a saline solution), b) deionised water + 1 g/l sodium bicarbonate, c) tap water - to reach an estimated concentration of 10² cells/ml for each micro- organism, i.e., 5 x 10² cells/ml in total . These solutions containing the mixed cultures were then cycled in a closed loop through the electrochemical reactor at a known volume per minute. As the electrochemical reactor, a Diamox 10c- 02 BDD reactor as available from Advanced Oxidations was used without modification. An aliquot of the solution was kept as an untreated control sample. During the processing samples were taken at specific time points.

The control samples were serially diluted in sterile diluents to 10^~2 and 10ΟμΙ aliquots spread plated onto WLN plates supporting the growth of aerobic bacteria and yeast and onto RakaRay agar plates for the detection of anaerobic lactic acid bacteria. The aerobic plates were incubated at 25°C for 3-5 days and the anaerobic plates in a CO2 enriched environment at 25°C for 5-7 days. The samples collected after passage through the reactor were membrane filtered (100ml). The filters were incubated on the media and under the conditions described above.

The results of these experiments are listed in Table 1 below and shown in FIG. 3. The three untreated control solutions spiked with bacteria and yeast showed cell concentrations of around 1 x 10³ to 5 x 10³ cells/ml which was slightly higher than the expected 5 x 10² cells/ml. Upon electrochemical treatment the microbial aqueous solution containing 1 g/l sodium bicarbonate showed a rapid drop in live cell numbers. All micro-organisms had already been de-activated after 1 min of cycling through the reactor (one pass through the reactor). The spiked tap water solution showed a similar effect although here there was some very limited survival up to 2 minutes of treatment time (two passes through the reactor). However, after 3 minutes (three passes through the reactor) there was no survival. It is likely that the electrolyte concentration in the tap water is lower than in the 1 g/l sodium bicarbonate solution so that the electrochemical effect may be lower. For the microbiologically contaminated saline solution the treatment times were longer, up to 30 minutes. The first sample taken after 12 minutes of circulation through the reactor was completely free of any live contaminants.

Table 1 Concentration o1 F micro-organisms in 3 electrolyte so utions before and after electrochemical treatment

Experimental example 2

The same setup as used in experimental example 1 was used in this example with the difference that a higher cell concentration was used in the test samples. The concentration was estimated at 10⁵ cells/ml per organism, so 5 x 10⁵ cells/ml in total per sample. The addition of the growth media to the aqueous solutions when artificially contaminating these was calculated to increase the concentrations of certain chemical components. The sugar level would have increased by 0.29 g/l, the peptide and amino acid concentration by 0.125 g/l and the salt concentration by 0.019 g/l. These figures are based on the composition of the growth media before culturing the organisms, such that it is likely that a portion of the chemicals would have been assimilated by the organisms while growing in the media.

The testing in this experiment was performed using solutions prepared with different electrolytes and concentrations, namely: deionised water + a) 2g/l sodium sulphate, b) 3g/l sodium sulphate, c) 3g/l sodium carbonate, d) 4g/l sodium bicarbonate. The control sample was serially diluted to 10^"5 but otherwise analysed as in stage 1 . The samples collected after passage through the electrochemical reactor in a closed loop were membrane filtered as before but additionally they were diluted to 10^~2 and 10ΟμΙ spread plated onto the described media.

The results for the experimental example 2 are tabulated in Table 2 and shown in FIG. 4. The concentration of live micro-organisms decreased with increased electrochemical treatment times. However, there were differences in efficiency in the 4 different electrolyte solutions tested. The 2 g/l sodium sulphate solution showed a very low cell concentration after 5 min of treatment. There is no explanation why this should have happened and, considering the other available data points, it is believed to be an outlier. In this solution, although a clear reduction in the microbial load was detected over the treatment regime, there was some limited survival after 30 min of processing (1 .29 x 10⁵ cfu/ml).

When the sodium sulphate concentration was increased to 3 g/l a similar antimicrobial electrochemical effect was seen. But the killing effect was more pronounced with a more rapid decline in live cells and a total kill after 30 min. The best result was obtained with sodium carbonate (3 g/l) as an electrolyte. There was a sharp decrease in live bacteria and yeast and after 25 minutes of passage through the reactor the solution was free of microbial contaminants. Of the 4 tests carried out at this high cell concentration this was the fastest bacteria and yeast de-activation time.

15 3.89 x 10⁶ 1 .61 x 10⁶ 5.30 x 10⁵ 2.62 x 10⁶

25 9.32 x 10⁵ 1 .60 x 10³ < 1 1 .81 x 10⁵

30 1 .29 x 10⁵ < 1 < 1 < 1

Table 2 Concentration of micro-organisms in 4 e ectrolyte solutions before and after electrochemical treatment

Experimental example 3

In this example the electrochemical reactor of experimental example 1 (Diamox 10c-02 BDD reactor) was placed in a closed loop with an in-line waste tank of a carbonated soft drink processing line. The following materials were used in the experiment.

- Plastic waste tank A containing approximately 300 litres of waste syrup that had been accumulated over a number of days from post- mix returns (A1 );

- Plastic waste tank B containing 1000 L of raw water (A2);

- Plastic waste tank C containing 1000 L of raw water + 4 g/l of

Sodium Carbonate (A3)

- Plastic waste tank D containing 1000 L of raw water (A4); and

- Test rig with Diamox 10c-02 BDD reactor. In the experiment, waste tank A was drained of syrup, then filled from waste tank Band subsequently connected to the test rig in a recirculation loop and run for 5 minutes at a 50,000 litres per hour flow rate. Waste tank A was subsequently drained and filled with the solution from waste tank C which had been recirculated through the test rig for 60 minutes to generate secondary oxidants. Waste tank A filled with the solution from waste tank C was subsequently connected to the test rig and the solution was circulated though the test rig for 20 minutes at 50,000 litres per hour flow rate. Waste tank A was subsequently drained and filled with raw water from waste tank D, which solution was circulated through the test rig for 5 minutes at 50,000 litres per hour. None of the waste tanks used in this experiment had been cleaned or disinfected pre-trial. A spray ball could not be used, thus limiting the velocity/turbulence in most parts of the waste tanks apart from the surface closest to the inlet pipe from the test rig. Samples of rinse water and swabs of IBC A surfaces were taken at all stages of the protocol. The results are shown in Table 3.

tank A following

Na₂CO₃ wash

Swab inside waste 0 0 0 tank A after final rinse

Waste tank A outlet 0 0 0 swab after final rinse

Table 3.

The experimental examples 1 -3 clearly demonstrate that the recirculation of contaminated rinse water through a CIP having an electrochemical reactor placed in a recirculation loop can achieve an effective purification of the contaminated water, most notably the eradication of microbial content, thereby facilitating the reuse of the water for further cleaning cycles whilst at the same time enabling a reduction in the chemicals used for the generation of the antioxidant species for the cleaning process of food or beverage processing systems. The use of chloride can be avoided altogether, thus preventing the formation of corrosive oxidants that can damage stainless steel processing lines.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps other than those listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention can be implemented by means of hardware comprising several distinct elements. In the device claim enumerating several means, several of these means can be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

1 . A clean-in place system (120) for disinfecting a food or beverage processing system (1 10), the clean-in place system comprising:

a recirculation line (130) for forming a recirculation loop with the food or beverage processing system (1 10) to recirculate an aqueous disinfectant solution through the food or beverage processing system (1 10); and

an electrochemical reactor (140) placed in the recirculation line (130) for generating the aqueous disinfectant solution by electrolysis of water molecules into oxidizing species.

2. The clean-in-place system (120) of claim 1 , wherein the electrochemical reactor (140) comprises an anode and a cathode, each comprising a boron-doped diamond surface.

3. The clean-in-place system (120) of claim 2, wherein the anode and cathode each are formed from a boron-doped diamond wafer.

4. The clean-in place system (120) of any of claims 1 -3, further comprising a disinfectant reservoir (152, 260) for containing the aqueous disinfectant solution for activation as it passes through the reactor.

5. The clean-in place system (120) of claim 4, wherein the disinfectant reservoir (152, 260) is placed in the recirculation line.

6. The clean-in place system (120) of any of claims 1 -5, wherein the system further comprises a chemicals reservoir (156) connected to the recirculation line (130) via a valve (170).

7. The clean-in place system (120) of claim 4, wherein the recirculation line (130) further comprises a sensor (136) for sensing a value of a chemical parameter in the aqueous disinfectant solution, wherein the valve (170) is responsive to said sensor (136).

8. The clean-in place system (120) of claim 6 or 7, wherein the chemicals reservoir (156) comprises an electrolyte selected from the group consisting of NaOH, X₂SO₄ and XHCO₃, wherein X = Na, K.

9. The clean-in place system (120) of any of claims 186, further comprising a rinse water container (150), wherein the circulation line is further adapted to recirculate the rinse water through the food or beverage processing system.

10. The clean-in place system of claim 9, wherein the recirculation line is reconfigurable to a loop including the rinse water container (150) and the electrochemical reactor (140).

1 1 . The clean-in-place system (120) of any of claims 1 -10, wherein the recirculation line (130) further comprises a venting stage (142) for removing hazardous gases from the clean-in-place system (120, 210).

12. A food or beverage processing system (1 10, 210) comprising the clean-in-place system (120) of any of claims 1 -1 1 .

13. The food or beverage processing system (1 10, 210) of claim 12, comprising a food or beverage manufacturing line configurably included in the recirculation loop.

14. The food or beverage processing system (21 0) of claim 12 or 13, comprising a pasteurizing chamber for pasteurizing filled food or beverage containers (240), the pasteurizing chamber comprising:

an entry and an exit;

a transport medium (215) for transporting the food or beverage containers from the entry to the exit;

a plurality of wetting stages (221 -225) arranged between the entry and exit and over the transport medium, each wetting stage being arranged to wash the food or beverage containers with the aqueous disinfectant solution at a predefined temperature; and a collection reservoir (250) for collecting the aqueous disinfectant solution, the recirculation line (230) connecting the collection reservoir to the plurality of wetting stages.

15. The food or beverage processing system of claim 14, wherein the wetting stages (221 -225) are shower stages or immersion stages.

16. A method for disinfecting a food or beverage processing system (100, 200) comprising the clean-in-place system (120) of any of claims 1 -1 1 , the method comprising:

generating the aqueous disinfectant solution by applying a water- electrolyzing voltage and/or amperage across the electrochemical reactor (140) whilst feeding a water-based fluid through the electrochemical reactor (140); and recirculating the generated aqueous disinfectant solution through the recirculation loop.

17. The method of claim 16, further comprising:

monitoring a value of a chemical parameter of the aqueous disinfectant solution; and

adding an oxidant precursor to the aqueous disinfectant solution in case said value falls outside a predefined range.

18. The method of claim 1 6 or 17, further comprising periodically reversing the polarity of the anode and cathode.

19. The method of any of claims 16-18, further comprising terminating said recirculating when the contaminant level in the food or beverage processing system (1 10, 210) falls below a predefined threshold.