Field of The Invention

This invention relates to a disinfecting device, and more particularly, but not exclusively, to a disinfecting device for disinfecting food products The invention also extends to a method for disinfecting food products

Background To The Invention

Microbial outgrowth is a primary concern amongst the food processing industry and consumers The presence of pathogenic microorganisms on food products can potentially lead to food-borne outbreaks of disease The most prominent pathogenic bacteria are those classified as Enterobacteriaceae and include organisms such as Escherichia coli, Salmonella spp and Enterobacter spp These types of bacteria are considered responsible for intestinal infections such as bacterial dysentery and bacterial food poisoning While efforts are made to control the existence of these types of bacteria in foods and in food processing facilities, large-scale food preparation operations often provide favourable environments for the growth of these organisms

The art teaches of chemical sanitizers, such as chlorine-based chemicals (for instance, sodium hypochlorite, calcium hypochlorite, and sodium dichloroisocyanurate) and quaternary ammonium compounds that are employed for disinfecting food products The effectiveness of these chemicals depends upon maintaining storage conditions and solution characteristics For example, chlorine is effective at a pH of 6 to 8, and becomes less effective outside of this pH range Furthermore, chlorine can produce toxic byproducts that are harmful to human health, such as chloramines and trihalomethanes (THMs)

In recent years, the European Union has imposed a bar against the use of chlorine compounds for disinfecting food produce, as specified by the EU Directive 2092/91 Accordingly, in order to comply with the Directive, there has been concerted effort to improve technology employing non-chlorine based products for the decontamination of food products This has resulted in an increased interest in the process of ozonation, the treatment of water with gaseous ozone (O ₃ ), for disinfecting food products. Moreover, the use of ozone for disinfecting food has been approved by The United States Food and Drug Administration (FDA). Ozone is reported to have 1.5 times the oxidizing potential of chlorine. Furthermore, contact times for anti-microbial action are typically four to five times less than chlorine.

Ozone is typically produced by passing an oxygen-containing gas through ultraviolet light or through an ozone generator. Ozone has shown to be a highly reactive oxidant capable of degrading microorganisms such as bacteria as well as pesticides and herbicides. A further advantage of ozone relates to its natural decomposition into oxygen and thus its use in disinfecting food products is highly beneficial as it decomposes into a non-toxic gas. Furthermore, ozone does not impart odour to or taint food products and no residual compounds or toxic residue is left on the food product or in the rinse water after application. Moreover, rinse water can be discharged to the environment or used for other applications without additional treatment or decontamination.

Various sanitizing processes using ozone are known in the art. In particular, venturi injection systems and bubble diffusers have been used for many years. In the case of venturi injectors, water is forced through a conical body, initiating a pressure differential between the inlet and the outlet of the system. This creates a vacuum inside the body of the injector, thereby initiating ozone suction through the suction port. With respect to bubble diffusers, ozone is emitted through bubbles beneath the surface of the water. Despite the fact that these ozone-sanitizing processes are widely used, they have not proven to be entirely satisfactory. A significant shortcoming associated therewith is that these processes result in a significant amount of ozone gas, namely 10 to 15%, being released into the atmosphere which, in turn, potentially results in serious health and environmental hazards. Accordingly, these systems allow free gaseous ozone, in higher concentrations than is permitted by regulatory standards, to be released into the atmosphere. Moreover, these systems afford undesirably low mass transfer rates of ozone. Furthermore, bubble diffusers suffer from an inherent disadvantage in that the diffuser holes frequently become fouled over time thereby decreasing the efficiency of the system. Object Of The invention

It is an object of the present invention to provide a disinfecting device that overcomes the shortcomings set out above.

Summary Of The Invention

According to a first aspect of the invention there is provided a disinfecting device including: a conduit defining a flow passage between a first inlet for receiving water from a source and an outlet nozzle; the first inlet and the outlet nozzle being in flow communication; a second inlet for receiving a source of gaseous ozone; a mixing chamber for enabling the water introduced from the first inlet to mix with the source of gaseous ozone introduced from the second inlet to produce ozonized water; the ozonized water being emitted from the outlet nozzle as a fine spray of ozonized water droplets such that a maximum of 5% of free gaseous ozone is released into the atmosphere therefrom.

In this specification, ozonized water is understood to refer to water that has been treated with ozone (O ₃ ).

There is provided for the first inlet to be removably securable to a tap. In one embodiment of the invention, the inlet is screw threaded for engagement with the thread of an existing tap fitting.

In an embodiment of the invention, the outlet nozzle is formed from a durable, ozone resistant material. The ozone resistant material may be selected from polyvinyldene fluoride (PVDF), such as Kynar® PVDF, glass filled polypropylene, chlorinated PVC or polycarbonate. Alternatively, the outlet nozzle may comprise a stainless steel outer sheath or may be constructed entirely from stainless steel. It will be appreciated that any type of ozone resistant material may be employed. The invention further provides for the source of gaseous ozone to be produced by an electrically powered ozone generator of the type know in the art In a preferred embodiment of the invention, a Corona Discharge ozone generator is employed It will be appreciated that more than one ozone generator may be utilized, depending on the choice of ozone generator In a preferred embodiment of the invention, two Corona Discharge ozone generators are employed Each ozone generator typically delivers between 125 to 500 mg of gaseous ozone per hour to the first inlet of the disinfecting device Preferably, each ozone generator delivers between 250 to 350 mg of gaseous ozone per hour, most preferably 300 mg of gaseous ozone per hour

According to a preferred embodiment of the invention, a maximum of 3% of free gaseous ozone is emitted into the atmosphere Most preferably, no free gaseous ozone is emitted

The Applicant believes that the ozone introduced into the disinfecting device from the second inlet coats the water droplets introduced from the first inlet In this way, the ozone is incorporated onto the ozonized water droplets such that no more than 5% of gaseous ozone, most preferably, no free gaseous ozone, is released into the atmosphere

The outlet nozzle is configured and dimensioned so as to allow for the ozonized water to be dispersed into ozonized water droplets having a particle size of 0 10 to 1 05 mm as the ozonized water is expelled through the outlet nozzle In a preferred embodiment of the invention, the ozonized water droplets have a particle size of 0 05 to 1 00 mm The Applicant believes that the aforesaid particle sizes afford superior mass transfer rates of ozone in comparison to the prior art systems

The invention further provides for the ozonized water to comprise at least 95 0% dissolved ozone In a preferred embodiment of the invention, the ozonized water comprises between 97 0 % to 100 0 % dissolved ozone More preferably, the ozonized water comprises 100 0 % dissolved ozone

The disinfecting device of the present invention is employed to disinfect food products including, but not limited to, salads, fruit and vegetables Alternatively, the disinfecting device may be employed to disinfect utensils and surfaces upon which food is to be place It will be appreciated that the disinfecting device is not limited to the above and may even be employed to disinfect a user's hands

In one embodiment of the invention, the disinfecting device allows for a spray of ozonized water droplets to be emitted from the outlet nozzle This spray facilitates the removal of the bacteria and pesticides from the food products, utensils and surfaces

The invention provides for a hose to be connected to the ozone generator at a first end thereof and to be removably connected to the second inlet of the disinfecting device at an opposite end thereof, such that the hose defines a flow passage between the ozone generator and the second inlet of the disinfecting device for enabling flow communication between the ozone generator and the second inlet A pump is employed to pump the gaseous ozone produced by the ozone generator through the hose to be delivered to the second inlet of the disinfecting device and into the mixing chamber In an embodiment of the invention, a power supply unit is employed for supplying power to the ozone generator The power supply may be in the form of a battery

The invention yet further provides for the ozone generator and pump to be housed in a housing The housing may be removably mounted to a wall in order to facilitate storage of the housing In one embodiment of the invention, the housing is mounted to a wall by means of screws, cable ties or any other suitable attachment means

In an embodiment of the invention, the housing includes an inlet for allowing air to be introduced into the housing and into the pump A filter is located over the inlet for removing dust and particles from the air entering the pump Preferably, the filter is a mesh filter

The housing is made of ozone-resistant material The ozone resistant material may be selected from polyvinyldene fluoπde (PVDF), such as Kynar® PVDF, glass filled polypropylene, chlorinated PVC or polycarbonate It will be appreciated that any type of ozone resistant material may be employed In a particular embodiment of the invention, the housing includes a sealing member for ensuring that the components housed therein remain dry In one embodiment of the invention, a pressure control mechanism is provided. In a specific embodiment of the invention, the pressure control mechanism is in the form of a pressure sensor of the type described in the art.

There is yet further provided for the disinfecting device to include a pressure measuring port. In an embodiment of the invention, a pipe is connected to the pressure sensor at a first end thereof and is removably connected to the pressure measuring port at an opposite end thereof, the hose defining a flow passage between the pressure sensor and the pressure measuring port for enabling communication between the pressure sensor and the pressure measuring port.

There is provided for the pressure sensor to be activated by an increase in pressure at the pressure measuring port of the disinfecting device that results when water is introduced through the first inlet from the tap into the conduit.

A PC board is further contained in the housing. The PC board may be of the type known and described in the art. In an embodiment of the invention, the PC board is adapted to include a plurality of sensors together with a micro-controller.

The present invention provides for the pressure sensor to be in communication with the PC board, such that when the pressure sensor is activated, the PC board is programmed so as to activate the power supply unit, which provides power to the ozone generator, and the pump. In this way, activation of the pressure sensor causes the pump to deliver gaseous ozone generated by the ozone generator to the second inlet of the disinfecting device and into the mixing chamber.

In a specific embodiment of the invention, the pressure sensor is activated when the pressure at the pressure measuring port reaches between 1.8 to 2.3 bar and is deactivated when the pressure at the pressure measuring port is between 0.8 to 1.2 bar. More preferably, the pressure sensor is activated at a pressure of 2.0 bar and is deactivated at a pressure of 1.0 bar. The Applicant has found that the disinfecting device operates optimally at a contact time of five minutes with respect to the food product to be sanitized.

According to a second embodiment of the invention there is provided a method for disinfecting food products, the method including the steps of: (i) providing a source of gaseous ozone; (ii) contacting the source of gaseous ozone with water to produce ozonized water; and

(iii) spraying the ozonized water onto food products to sanitize said food products such that a maximum of 5% of free gaseous ozone is released into the atmosphere.

The source of gaseous ozone in step (i) is produced as described hereinabove.

These and other features of the invention are described in more detail below.

Brief Description Of The Drawings

One embodiment of the invention is described below, by way of example only, and with reference to the accompanying drawings in which:

Figure 1 is a top perspective view of a disinfecting device according to the invention wherein the disinfecting device is connected to an ozone generator, pump and power supply unit housed within a housing;

Figure 2 is a top perspective view of the disinfecting device and housing of Figure

1 , wherein a PC board is also included within the housing and wherein the disinfecting device is, in operation, connected to a tap;

Figure 3 is a cross sectional front view of the disinfecting device of Figure 1 ;

Figure 4 is an exploded perspective view of the disinfecting device and housing of

Figure 2; and Figure 5 is a perspective view of the disinfecting device and housing of Figure 2, wherein the housing is closed so as to conceal the components contained therein.

Detailed Description Of The Drawings

With reference to the drawings, in which like numerals indicate like features, a disinfecting device is generally indicated by reference number 1.

Figures 1 to 5 depict a disinfecting device 1 which includes a body 3 having a first inlet 2 for receiving water from a tap 4 and an outlet nozzle 5. As shown clearly in Figure 3, the disinfecting device 1 includes a conduit 8 defining a flow passage between the first inlet 2 and the outlet nozzle 5 whereby the first inlet 2 and the outlet nozzle 5 are in fluid flow communication. The disinfecting device 1 further includes a second inlet 6 for receiving gaseous ozone and a pressure measuring port 14 discussed in more detail herein below. A mixing chamber 7 is included in the body 3 of the disinfecting device 1 for enabling the water introduced from the first inlet 2 to mix with the gaseous ozone introduced from the second inlet 6 in order to produce ozonized water. Droplets of ozonized water are emitted from the outlet nozzle 5 such that no free gaseous ozone is released into the atmosphere by virtue of operation of the system.

As shown in Figure 1 , the first inlet 2 is screw threaded to allow the inlet 2 to be screwed onto an existing tap fitting 4.

The gaseous ozone is produced by an electrically powered ozone generator 9 of the type know in the art. Preferably, a Corona Discharge (CD) ozone generator is employed. The generator, together with further components discussed in detail herein under, is housed in a housing 12. As depicted in Figures 1 , 2 and 4, an connecting means 21 , an outlet 22 and a power supply inlet 16 are located on an inside surface of a sidewall of the housing 12. A pipe 15 is connected to the connecting means 21 at a first end thereof and is connected to the pressure port 14 of the disinfecting device 1 at an opposite end thereof. A hose 10 is connected to the outlet 20 at a first end thereof and is connected to the second inlet 6 of the disinfecting device 1 at an opposite end thereof. Figure 5 depicts a power cable 22 which is connected to a 12V step down transformer 23 at one end thereof and to the power supply inlet 16 at its opposite end

A power supply unit 11 , in the form of a battery, an air pump 18, a pressure sensor 13 and a PC board 17 are also contained within the housing 12 (as shown in Figures 1 and 2) It will be appreciated that the air pump 18 and the pressure sensor 13 are of the type known and described in the art The PC board 17 described in this particular embodiment comprises a number of sensors and a micro-controller (not shown) The micro-controller is programmed with firmware, which is installed by means of a 9 pin D type connector on the PC board 17 It will, however, be appreciated that any suitable PC board may be employed Chord 31 is connected to the connecting means 21 in order to enable the pipe 15 to be in communication with the pressure sensor 13 The pressure sensor 13, in turn, is in contact with the PC board 17 Chord 29 delivers power from the power supply inlet 16 to the PC board 17 whilst cords 30 enable the air pump 18 and the battery 11 to be in communication with the PC board 17 Cord 24 connects the ozone generator 9 to the battery 11 , cord 25 connects the air pump 18 to the ozone generator 9 and cord 26 connects the ozone generator 9 to the outlet 20

Figures 1 , 2 and 4 further show a sealing member 19 placed around the edge of the bottom base of the housing 12 for ensuring that the components of the housing 12, discussed above, remain dry

As shown in Figure 2, an LED light 27 and an alarm 28 are also contained within the housing 12 Figure 3 further depicts a filter member 22 located above an inlet (not shown) on the bottom base of the housing 12 for removing dust and particles from the air entering through said inlet and into the air pump 18

A decorative cover 23 is positioned above the removable cover of the housing 12, as shown in Figures 4 and 5 It will be appreciated that the decorative cover 23 may include, inter alia, branding for advertising purposes

In use, the housing 12 containing, inter alia, the ozone generator 9, the battery 11 , the air pump 18, the pressure sensor 13 and the PC board 17, is mounted to a wall (not shown) inside a kitchen or restaurant either with screws, cable ties or any other suitable attachment means. The first inlet 2 of the disinfecting device 1 is to be screwed onto an existing tap fitting 4 and the food products to be disinfected are to be placed beneath the outlet nozzle 5 of the disinfecting device 1 , Thereafter, a user will turn on the tap 4 and the 12V step down transformer 32. When the transformer 32 is switched on, the electricity will pass through the power supply inlet 16 and be introduced into chord 29 thereby supplying the PC board 17 with the requisite power. When the tap is switched on, the water flowing from the tap 4 will enter the disinfecting device 1 through the first inlet 2 and flow through the conduit 8.

The introduction of the water flowing into the conduit 8 will result in an increase in pressure at the pressure port 14. When the pressure at the pressure port reaches 2.0 bar, the pressure sensor 13 will be activated. The activation of the sensor 13 will cause the PC board to turn on the air pump 18, the battery 11 and hence, the ozone generator 9. In this way, the sensor 13 and the PC board act as a control mechanism that is dependent on the flow of fluid through the disinfecting device 1. The features of this control mechanism are described in more detail herein below. Once the battery 11 , the air pump 18 and the ozone generator 9 have been switched on, the ozone generator 9 will produce gaseous ozone and the pump 18 will cause this gaseous ozone to be pumped from the ozone generator 9 through chord 26, out the outlet 20 and though the hose 10 to be delivered to the second inlet 6 of the disinfecting device 1 and into the mixing chamber 7.

As the water enters the mixing chamber 7 from the conduit 8, it will mix with the gaseous ozone introduced from the second inlet 6 to produce ozonized water.

The dimension and configuration of the outlet nozzle 5 allows the ozonized water produced in the mixing chamber 7 to be dispersed into ozonized water droplets having a particle size of 0.10 to 1.05 mm as the ozonized water is expelled through the outlet nozzle 5. This spray of water droplets facilitates the removal of the bacteria and pesticides from the food products while the ozonized water produced in the mixing chamber 7 degrades the bacteria and pesticides present on the food products. Furthermore, the ozonized water droplets are emitted from the outlet nozzle 5 such that no free gaseous ozone is released into the atmosphere. Once the food products have been washed and sanitized, the user will turn off the tap 4. When the tap 4 is turned off, no water will enter the inlet 2, thus resulting in the pressure at the pressure port to decrease. When the pressure has decreased to 1.0 bar, the pressure sensor 13 will be deactivated which will, in turn, cause the PC board to stop the operation of the battery 11 , the air pump 18 and the ozone generator 9, and hence the flow of gaseous ozone through the hose 10 to the disinfecting device 1 will be discontinued.

The control mechanism includes the pressure sensor 13 and the PC board 17, as mentioned herein above. The PC board 17 not only switches on the air pump 18, the battery 11 and the ozone generator 9 when the pressure resulting from the flow of fluid into the disinfecting device 1 activates the pressure sensor 13, but it also controls the ozone/air mixture flow rate and sensors the inlet pressure of the ozone generator 9 and the temperature within the ozone generator 9. When the parameters of these operating conditions fall outside the permitted limits, the LED light 27 and/or the alarm 28 will be activated. According to Table 1 , the LED light 27 will flash green, orange or red in response to the any possible faults associated with the operating conditions of the components contained in the housing 12. The alarm 28 will be activated either together with the LED light 27 or separately. In this way, the LED light 27 and/or the alarm 28 will alert a user of the fault associated with the respective operating condition.

Table 1: Data stipulating possible faults associated with the operating conditions of the components contained in the housing and the corresponding colour of the LED light for purposes of alerting a user of the fault

Examples of the Invention

The invention will now further be described with reference to the following non-limiting comparative example

In order to demonstrate the efficacy of the disinfecting device of the present invention, food products such as tomatoes were inoculated with Coliforms, Escherichia coli (E coli), Salmonella spp, and Staphylococcus aureus

1 Inoculation procedure

1 1 Coliform inoculation

The tomatoes inoculated with Coliforms were plated on chromocult agar growth media and incubated at a temperature of 37°C for a time period of 24 hours

1 2 E coli inoculation

The tomatoes inoculated with E coli were plated on chromocult agar growth media and incubated at a temperature of 37°C for a time period of 24 hours

1 3 Salmonella spp inoculation

The tomatoes inoculated with Salmonella spp were incubated in peptone water at a temperature of 35 ⁰ C for 24 hours Thereafter, 0 1 ml of the peptone water was inoculated into rappaport-vassiliadis soya peptone broth and incubated at a temperature of 32°C for a time period of between 24 to 48 hours The broth mixture was then sub- cultured onto selective XLD agar growth media plates and incubated at a temperature of 35 ⁰ C for a time period of between 18 to 24 hours.

1.4 Staphylococcus aureus inoculation

The tomatoes inoculated with S. aureus were plated on baird parker agar growth media and incubated at a temperature of 37°C for a time period of between 48 to 96 hours.

2. Disinfecting procedure

The inoculated tomatoes were thereafter washed with (i) chlorine gas and (ii) ozonized water produced by the disinfecting device of the present invention for a total time period of 5 minutes.

3. Analysis

Once the tomatoes had been sprayed with the abovementioned disinfecting agents, the surfaces of the tomatoes were swabbed and analyzed under a normal-light dissecting microscope in order to determine the number of bacterial collonies present on the tomatoes after the disinfecting agents had been applied. A comparative analysis was carried out in order to compare the number of collonies present on the tomatoes after disinfecting the tomatoes with the aforesaid disinfecting agents. The presence of the following collonies was analysed:

3.1 Coliforms (SGS 1 TP:003)

3.2 E. coli (SGS 1TP:004)

3.3 Salmonella spp (SGS 1 TP:018)

3.4 Staphylococcus aureus (SGS 1 TP:012)

4. Results

The results obtained from the comparative analysis are tabulated below. Table 2: SGS comparative analysis of bacterial colony count after application of different disinfecting agents used to disinfect inoculated tomatoes

Notes: ND - None Detected in a 1 in 10 dilution (<10 cfu/g)

The above data indicates that bacterial collonies of Coliforms, Escherichia coli, Salmonella spp, and Staphylococcus aureus were detected on the tomatoes after the application of chlorine gas as a disinfecting agent. The above results further indicate that after the application of ozonized water produced by the disinfecting device of the present invention, Coliforms, Escherichia coli, Salmonella spp, and Staphylococcus aureus were not detected on the tomatoes. This indicates that the ozonized water produced in accordance with the present invention is highly effective in degrading the bacteria, including Coliforms, Escherichia coli, Salmonella spp, and Staphylococcus aureus, present on the tomatoes.

Furthermore, examination of the rinse water after disinfecting the tomatoes with the ozonized water showed it to be free of micro-organisms including bacteria, as well as pesticides and herbicides. It was further noted that the levels of ozone used did not affect the quality, colour or surface texture of the tomatoes. Advantages associated with the present invention

The disinfecting device of the present invention affords numerous advantageous when employed to sanitize food products and is thereby beneficial in destroying harmful bacteria and micro-organisms present on food products One such advantage afforded by the disinfecting device is that said device produces ozonized water wherein no free gaseous ozone is emitted into the atmosphere

Yet a further advantage associated with the disinfecting device of the present invention resides in its ability to operate economically Once the first inlet of the disinfecting device has been secured to the tap fitting, the second inlet and the pressure port have been connected to their respective hoses and the housing has been mounted to a wall, the unit comprising the disinfecting device and the housing requires only electricity, to operate the ozone generator, and air, to be fed into the ozone generator to produce the gaseous ozone, as consumables

The present invention is yet further advantageous in that it provides for CT values of between 4 00 and 6 00 The CT value is determined from the concentration (C in mg/l or ppm) and the contact time (T in minutes) of a specific disinfecting agent employed and thus indicates the effectiveness of the disinfecting agent The CT values obtained from the present invention are significantly superior to CT values of between 1 86 and 1 90 obtained by prior art disinfecting processes

In addition to the above-mentioned advantages, the configuration and dimensions of the outlet nozzle provides for a spray of ozonized water droplets to be emitted from the outlet nozzle This spray facilitates the removal of the bacteria and micro-organisms from the food products

The Applicant has further found that superior mass transfer rates of ozone are achieved in accordance with the present invention when compared to prior art systems

Furthermore, the Applicant of the present invention has found that the disinfecting device operates optimally at a contact time of five minutes with respect to the food product to be sanitized This is most beneficial, as the chlorine compounds previously employed to disinfect food produce required a contact time of at least 15 minutes before bacterial degradation would ensue. Furthermore, the use of chlorine compounds potentially resulted in the production of toxic by-products such as chloramines and trihalomethanes (THMs). In contrast, ozone does not leave any toxic residue on the food product or in the rinse water after application, such that the rinse water can be discharged to the environment without additional treatment or purification.

It is envisaged that the disinfecting device according to the present invention will be employed in restaurants where large-scale food preparation operations often require food produce to be sanitized and disinfected before use. It is further envisaged that the disinfecting device may be employed, not only for sanitizing food products, but also for sanitizing users' hands and utensils used during the preparation of food.

It is envisaged that the invention as described above will solve the disadvantages associated with the known art.

The above is only one embodiment of the invention and it will be appreciated that many variations in detail are possible without departing from the spirit and scope of the invention.