Abstract:
Methods of treating and sanitizing foods and other targeted objects, including the use of ozone and a method for providing a liquid dosed with pressurized ozone. The ozonated liquid of the invention is particularly useful for treating food products, food storage, and food transportation devices as well as treating water, or other target objects. Included is a method or pressurizing an ozone-containing stream without destroying the ozone or contaminating the stream with oil or water. The pressurized ozone-containing stream is then used to dose a liquid, which in turn is used to sanitize or treat a target object.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a continuation-in-part of and claims priority to U.S. application Ser. No. 11/145,137, filed Jun. 3, 2005, entitled, “Novel Biological Treating Agent,” which is a continuation-in-part of and claims priority to U.S. application Ser. No. 10/632,232, filed Jul. 31, 2003, which is a non-provisional application claiming priority of U.S. Provisional application 60/404,635, filed Aug. 20, 2002, and U.S. Provisional application 60/459,398, filed Apr. 1, 2003. This application also claims priority to U.S. Provisional application 60/638,020, filed Dec. 21, 2004. The entire contents of these applications are hereby incorporated by reference. 
     
    
     BACKGROUND  
       [0002]     Treating and sanitation of food, equipment, pharmaceutical products, and even water to reduce undesirable biological microorganisms is important to the protection of public health. For example, food can be damaged by microbes, spores, insects, and other similar sources. Each year, economic losses of food and labor due to damage from such sources is more than $100 billion. Currently, food items are preserved using a variety of methods, including refrigeration, fumigation with toxic chemicals, irradiation, biological control, heat exposure, and controlled atmosphere storage (a fruit industry technique that involves modifying the concentration of gases naturally present in the air).  
         [0003]     The primary problem regarding food spoilage in public health is microbial growth. If pathogenic microorganisms are present, then growth can potentially lead to food-borne outbreaks and significant economic losses. Food safety concerns have been brought to the consumers&#39; attention since the early part of the 20 th  century and those concerns have become even stronger today. Outbreaks from  Salmonella  and  E. coli  have increased the focus on food safety, including from a regulatory perspective. A study completed by the Centers for Disease Control and Prevention (CDC) estimated that food-borne diseases cause approximately 76 million illnesses, 325,000 hospitalizations, and 5,000 deaths annually in the US. Those numbers reveal the dramatic need for effective means of handling food products in order to ensure food safety.  
         [0004]     Effective sanitation of food or other items depends on the combination of what is to be sanitized and the sanitation process type. Not all of the currently available technologies can deliver an effective reduction of microorganisms and at the same time prevent product or environmental degradation. It is well known in the art to cool products, such as foods, during processing with some type of refrigerant to slow down the growth of unwanted microbes and enzymatic reactions in foods. For instance, the shelf life and quality of food products are improved by processing, transporting, and storing under refrigerated conditions.  
         [0005]     Cooling agents, such as water ice, dry ice, carbon dioxide, or nitrogen, are liquid or solid agents that can be used as an expendable refrigerant. In food processing applications, liquids, such as nitrogen, are used to cool and inert the atmosphere during food processing or storage.  
         [0006]     While refrigeration can retard microbial growth, such treatment does not necessarily kill bacteria. Accordingly, microorganisms can still survive through refrigeration, and worse, some microorganisms can still grow and produce harmful substances during refrigerated storage. Furthermore, it is possible that the refrigerant used to cool a target item or food product can itself be contaminated with pathogenic microorganisms, thus contaminating the target item or food product.  
         [0007]     Biocidal agents are used to sanitize equipment, provide antiseptic environments, treat water, and sanitize foods. The reaction of biocidal agents with microbial cell structures is often irreversible; therefore the cells either become attenuated or die.  
         [0008]     One biocidal agent commonly used in the industry is ozone. However, ozone is very unstable, and therefore, must be produced at the location of consumption. Production of ozone requires specialized equipment and involves safety issues due to handling of the equipment and feedstock, such as pure oxygen. After the ozone is produced, it must be delivered in some form to the target item as a sanitizer. Ozone is often dissolved or absorbed in water as a mechanism to deliver the unstable ozone to a target item. However, ozone has poor solubility in water. Mixtures of ozone and water typically contain less than about 20 ppm by weight (ppmwt) ozone. As a result, large quantities of water relative to the ozone are required if water is used as a delivery agent. Furthermore, because of the large quantities of water required, the ozone and water cannot be pre-mixed and transported to site. Thus, ozone and water must be mixed on site.  
         [0009]     Another problem with ozone is the difficulty in compressing an ozone-containing stream. There are no commercial processes known to one of ordinary skill in the art that are capable of delivering ozone at high pressures. Ozone generating equipment known in the art typically produces an ozone-containing gas stream at fairly low pressures. These ozone generators are typically limited to producing a stream with a pressure of less than about 25 psig. Conventional mechanical compression cannot be used to compress ozone because the unstable ozone molecule is destroyed in conventional compressors. Oil-lubricated or water ring compression can be used to compress a stream containing ozone up to 150 psig; however, these compressors inherently contaminate the ozone stream with oil or water respectively. Therefore, the prior art fails to provide a method to compress the ozone to pressures above about 25 psig without contaminating the ozone stream with some level of oil or water. Furthermore, the prior art fails to provide any method to successfully compress an ozone stream to pressures of greater than about 150 psig without destroying the ozone.  
         [0010]     It is desirable to pressurize ozone to be used to sanitize equipment or devices and process foods. It is particularly desirable to be able to provide ozone in a pressurized stream at pressures above 150 psig without contaminating the ozone with oil or water. Further yet, it is desirable to pressurize ozone and feed it into a liquid, so that it is absorbed under pressure into the liquid and the liquid can them be used to treat of sanitize devices or food products.  
       SUMMARY  
       [0011]     The current invention fulfills the need to provide a process to pressurize an ozone-containing stream without destroying the ozone or contaminating the ozone-containing stream with oil or water. It is desirable to be able to provide a pressurized ozone-containing stream that is substantially free of oil and moisture. It is also desirable to the ozone-containing stream at pressures above 150 psig. It further desirable to pressurize ozone and feed it into a liquid, so that it is absorbed under pressure into the liquid.  
         [0012]     The current invention pressurizes ozone by feeding an ozone-containing source to an ozone pressurization system to establish a first pressure followed by pressurizing the ozone pressurization system. The ozone pressurization system is pressurized by feeding a pressurization gas to the ozone pressurization system to raise the pressure to the second pressure and form a pressurized ozone-containing gas. The pressurized ozone-containing gas is then withdrawn from the ozone pressurization system. This method pressurizes the ozone-containing stream without contaminating the stream with oil or water.  
         [0013]     In one embodiment, the ozone pressurization system comprises a pressurization vessel, the pressurization gas is fed into the lower portion of the pressurization vessel, and the pressurized ozone-containing gas is withdrawn from the upper portion of the pressurization vessel.  
         [0014]     In another embodiment, the pressurization system comprises a first pressurization vessel and a last pressurization vessel. In this embodiment, the pressurization vessels are fluidly connected in series and the pressurizing gas is fed exclusively to the first pressurization vessel.  
         [0015]     The current inventive method also provides a method to produce an ozonated liquid by feeding an ozone-containing gas from the ozone source to an ozone pressurization system to establish a first pressure, pressurizing the ozone pressurization system by feeding a pressurization gas into the system; thus, raising the pressure of the ozone-containing gas to a second pressure and forming a pressurized ozone-containing gas. This method also places a liquefied dry gas in an expansion vessel, and sparges the pressurized ozone-containing gas through the liquefied dry gas to form an ozonated liquefied dry gas, which is withdrawn from the expansion vessel. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]     For a further understanding of the nature and objects of the present invention, reference should be made to the following detailed description, taken in conjunction with the accompanying drawings, in which like elements are given the same or analogous reference numbers and wherein:  
         [0017]      FIG. 1  is a schematic of an embodiment of the current invention for pressurizing ozone;  
         [0018]      FIG. 2  is a schematic of another embodiment of the current invention for pressurizing ozone;  
         [0019]      FIG. 3  is a schematic of yet another embodiment of the current invention for pressurizing ozone;  
         [0020]      FIG. 4  is a schematic of still another embodiment of the current invention for pressurizing ozone;  
         [0021]      FIG. 5  is a schematic of an embodiment for pressurizing ozone and producing an ozonated liquefied gas according to the current invention; and  
         [0022]      FIG. 6  is a graph showing the concentrations of ozone in a liquefied gas attained by the current method of the current invention. 
     
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0023]     The current invention provides a method of pressurizing an ozone-containing stream without destroying the ozone or contaminating the ozone-containing stream with oil or water. Furthermore, the method forms an ozonated liquefied dry gas by bubbling the pressurized ozone-containing stream through a reservoir of liquefied dry gas.  
         [0024]     The current invention pressurizes ozone by feeding an ozone-containing source to an ozone pressurization system to establish a first pressure followed by pressurizing the ozone pressurization system. The ozone pressurization system is pressurized by feeding a pressurization gas to the ozone pressurization system to raise the pressure to the second pressure and form a pressurized ozone-containing gas. The pressurized ozone-containing gas is then withdrawn from the ozone pressurization system.  
         [0025]     In one preferred method, the pressurization gas is a dry gas. One preferred dry gas is CO 2 . The method pressurizes the ozone-containing stream without contaminating the stream with oil or water. The method preferable pressurizes the ozone-containing stream to a pressure that is greater than about 150 psig. Furthermore, the method can pressurize the ozone-containing stream from a pressure of less than about 50 psig to a pressure that is preferably greater than about 150 psig and even more preferably greater than about 200 psig.  
         [0026]     In one embodiment of the method, the ozone pressurization system comprises a pressurization vessel, the pressurization gas is fed into the lower portion of the pressurization vessel, and the pressurized ozone-containing gas is withdrawn from the upper portion of the pressurization vessel.  
         [0027]     In another embodiment, the pressurization system comprises a first pressurization vessel and a last pressurization vessel. In this embodiment, the pressurization vessels are fluidly connected in series and the pressurizing gas is fed exclusively to the first pressurization vessel. In a preferred embodiment, the pressurized gas mixture is withdrawn from the first pressurization vessel and fed to the last pressurization vessel, while the pressurized ozone-containing gas is withdrawn from the last pressurization vessel. In a further preferred embodiment, the pressurization gas is fed into a lower portion of the first pressurization vessel while the pressurized gas mixture is withdrawn from an upper portion of that first pressurization vessel. The pressurized gas mixture is then fed into a lower portion of the last pressurization vessel and the pressurized ozone-containing gas is finally withdrawn from an upper portion of the last pressurization vessel.  
         [0028]     In yet a further embodiment, the pressurization system comprises a number of pressurization vessels in series and includes the steps of withdrawing a pressurized gas mixture from the first pressurization vessel, feeding the pressurized gas mixture to a successive pressurization vessel, and transferring the pressurized gas mixture from the successive pressurization vessel to the last pressurization vessel. This embodiment, like those above withdraws the pressurized ozone-containing gas from the last pressurization vessel. One further embodiment of this method feeds the pressurization gas into a lower portion of the first pressurization vessel, withdraws the pressurized gas is from an upper portion of the first pressurization vessel, feeds the pressurized gas mixture into a lower portion of the successive pressurization vessel, withdraws that pressurized gas from an upper portion of the successive pressurization vessel, and ultimately transfers the pressurized gas mixture into a lower portion of the last pressurization vessel.  
         [0029]     The current inventive method also provides an ozonated liquid by feeding an ozone-containing gas from the ozone source to an ozone pressurization system to establish a first pressure, pressurizing the ozone pressurization system by feeding a pressurization gas into the system thus raising the pressure of the ozone-containing gas to a second pressure and forming a pressurized ozone-containing gas. The method also places a liquefied dry gas in an expansion vessel, and sparges the pressurized ozone-containing gas through the liquefied dry gas to form an ozonated liquefied dry gas, which is withdrawn from the expansion vessel. This method may further include steps of withdrawing a vent gas from the expansion tank and recycling the vent gas to a liquefied dry gas storage vessel. In some embodiments, the sparging occurs substantially continuously.  
         [0030]     Referring to  FIG. 1 , one embodiment of the current method provides an ozone-containing gas  102  from an ozone source  104 . Ozone can be generated in commercially available ozone generator known to one of ordinary skill in the art. The ozone generation unit preferably uses a pure oxygen feed, to form the ozone-containing gas  102 , which preferably contains about 6 to about 13 wt % ozone in oxygen, and more preferably about 9 to about 11 wt % ozone. The ozone pressurization system  106  is purged with the ozone-containing gas  102  to establish a concentration of ozone in the entire ozone pressurization system  106 . Then, the ozone pressurization system  106  is pressurized with the ozone-containing gas  102  to set an initial pressure, for instance about 5 to about 25 psig, in the entire ozone pressurization system  106 . The higher the initial pressure in the compression system, the higher final pressure that can be achieved. The entire ozone pressurization system  106  is then isolated from the ozone generator. The ozone-containing gas  102  is pressurized in an ozone pressurization system  106  to form a pressurized ozone-containing gas  108 . To form the pressurized ozone-containing gas  108 , the ozone-containing gas  102  is fed to the ozone pressurization system  106  to establish a concentration of ozone-containing gas throughout the ozone pressurization system  106  at first pressure in the ozone pressurization system  106 . The first pressure is preferably less than about 100 psig, more preferably less than about 50 psig and even more preferably less than about 30 psig. Next, a pressurization gas  110  is fed to the ozone pressurization system  106  to raise the pressure in the ozone pressurization system  106  to a second pressure. As the pressurization gas  110  enters the ozone pressurization system  106 , the ozone-containing gas in the ozone pressurization system  106  is compressed. It is believed that if the density of the pressurization gas  110  and the ozone-containing gas  102  is substantially different, the gases stratify in the tanks and mixing is minimal. The final result is a compressed ozone-containing feed mixture typically containing close to, but somewhat lower concentration of ozone in oxygen that the ozone-containing gas  102  in the upper portion of any vessels in the ozone pressurization system  106 . The pressurization gas  110  feed to the ozone pressurization system  106  is stopped when the desired second pressure is reached. The pressurized ozone-containing gas  108  is then withdrawn from the ozone pressurization system  106 . The ozone pressurization system  106  preferably comprises at least one pressurization vessel  112 . Furthermore, the pressurization gas  110  is preferably fed to a lower portion of the pressurization vessel  112  and more preferably fed to the bottom portion of the pressurization vessel  112 . The pressurized ozone-containing gas  108  is preferably removed from an upper portion of the pressurization vessel  112  and more preferably removed from the top of the pressurization vessel  112 . In one preferred embodiment, the pressurization gas  110  is fed at a slow flow rate to the pressurization system  106  in order to minimize the mixing for the ozone-containing gas  102  and the pressurization gas  110 . It is preferable to maintain laminar flow rates in the pressurization vessel  112 .  
         [0031]     Still referring to  FIG. 1 , the pressurization gas  110  is fed to the pressurization vessel to raise the pressure in the ozone pressurization system  106  to a second pressure of greater than about 100 psig, more preferably greater than about 150 psig, and even more preferably greater than about 200 psig. Then, the pressurized ozone-containing gas  108  can be withdrawn from the ozone pressurization system  106 . Using this method, it is feasible to pressurize an ozone-containing stream to pressures of greater than about 500 psig and even greater than about 1,000 psig without destroying the ozone. Furthermore, a substantial portion of the ozone (O 3 ) remains relatively undiluted. Still further, the resulting pressurized ozone-containing gas  108  is substantially free of oil, water, or other undesirable contaminants. In one preferred embodiment, the pressurized ozone-containing gas  108  contains less than about 0.05 wt % water, preferably contains less than about 200 ppm wt water, and more preferably less than about 20 ppm wt water.  
         [0032]     One preferred pressurization gas  110  is a dry gas. The dry gas can be any suitable non-aqueous gas, but is preferably a liquefied gas, particularly a liquefied gas with a high gas density compared to the ozone-containing gas  102 . The dry gas preferably contains less than 0.05 wt % water, and more preferably containing less than 20 ppm wt water. In one preferred embodiment, the pressurization gas  110  is preferably a dry gas that is stored as a liquid, such as CO 2 . The liquefied dry gas is removed from the liquid storage vessel and expanded to form the pressurization gas  110 . One preferred embodiment uses a pressurization gas  110  that has a gas density that is higher that the gas density of the ozone-containing gas  102 . This pressurization gas  110  is preferably cold after expansion to provide a pressurization gas at the highest gas density possible for that gas. In one embodiment, the pressurization gas is preferably less than about 20° C. after expansion, and more preferably less than about 10° C. after expansion. By using a pressurization gas  110  that is higher in gas density than the ozone-containing gas  102 , and by feeding the pressurization gas  110  slowly, dilution of the ozone-containing gas  102  with the pressurization gas  110  is minimized. Without being limited by this theory, it is believed that the higher gas density pressurization gas  110  layers out in the pressurization vessel  112  below the lower density ozone-containing gas  102  already in the vessel. In one embodiment, the concentration of ozone in the pressurized ozone-containing gas  108  is at least about 70% of the concentration of ozone in the ozone-containing gas  102 , more preferably at least 80% of the concentration of ozone in the ozone-containing gas  102 , and even more preferably at least about 90% of the concentration of ozone in the ozone-containing gas  102 .  
         [0033]     In one embodiment, a continuous flow of pressurized ozone gas  110  is supplied by using a plurality of ozone pressurization systems  106  operated in a “round robin” to maximize the use of the ozone generator and minimize the waste of pressurization gas  110  by cross-tying (not shown) the sets of ozone pressurization systems  106 .  
         [0034]     Referring to  FIG. 2 , one embodiment of the current method utilizes an ozone pressurization system  106  that comprises a plurality of pressurization vessels, which comprise at least a first pressurization vessel  202  and a last pressurization vessel  204 . An upper portion of the first pressurization vessel  202  and a lower portion of the last pressurization vessel  204  are connected by a fluid connection means  206 . The fluid connection means can be any type or combination of pipe, conduit, vessel, valve, orifice, chamber, or other flow passage that allows a pressurized gas mixture to flow from one vessel to another. One preferred fluid connection means  206  has at least part of the means that is smaller in diameter than the first pressurization vessel  202  or the last pressurization vessel  204 . In this preferred method, a pressurized gas mixture is withdrawn (or pushed) from the upper portion of the first pressurization vessel  202  and fed into a lower portion of the last pressurization vessel  204  as the pressurization gas  110  is fed into the lower portion of the first pressurization vessel  202 . Eventually, the first pressurization vessel  202  will be completely filled with a gas mixture that primarily comprises the pressurization gas  110 . Having a plurality of pressurization vessels helps prevent the pressurization gas  110  from mixing with the ozone-containing gas  102 . The compressed ozone-containing gas  110  is withdrawn from the last pressurization vessel  204 . The last pressurization vessel  204  is preferably isolated from any upstream pressurization vessels to prevent unwanted dilution of the pressurized ozone mixture. The pressure from the last pressurization vessel  204  is allowed to drop as the ozone-containing gas  110  is fed to the process.  
         [0035]     Referring to  FIG. 3 , one embodiment of the current method uses a plurality of pressurization vessels comprising more than two pressurization vessels fluidly connected in series. The ozone-containing gas  102  is first fed to fill the plurality of pressurization vessels with the ozone-containing gas  102  at a first pressure. Next, the pressurization gas  110  is fed into a first pressurization vessel  202  in the series of pressurization vessels and the pressurized ozone-containing gas  108  flows out of a last pressurization vessel  204  in the series of pressurization vessels. The embodiment of  FIG. 3  uses an ozone pressurization system that comprises a first pressurization vessel  202 , a successive pressurization vessel  303 , and a last pressurization vessel  204 . In this embodiment, a pressurized gas mixture is withdrawn from the first pressurization vessel  202  and fed to the successive pressurization vessel. The pressurized gas mixture then flows from the successive pressurization vessel to the last pressurization vessel  204 . The pressurized ozone-containing gas  108  is then withdrawn from the last pressurization vessel  204  after the ozone pressurization system  106  reaches a second pressure.  
         [0036]     Still referring to  FIG. 3 , in one embodiment, the pressurization gas is fed into a lower portion of the first pressurization vessel  202 . A pressurized gas mixture is withdrawn from an upper portion of the first pressurization vessel  202  and fed into a lower portion of the successive pressurization vessel  302  via a first conduit  304 . The pressurized gas is then withdrawn from an upper portion of the successive pressurization vessel  302  and transferred into a lower portion of the last pressurization vessel  204  via a second conduit  306 . Finally, the pressurized ozone-containing gas  108  is withdrawn from the upper portion of the last pressurization vessel  204  after the ozone pressurization system  106  reaches a second pressure.  
         [0037]     Referring to  FIG. 4 , one embodiment of the current method uses a plurality of pressurization vessels fluidly connected in series. In this embodiment, the ozone pressurization system  106  comprises a first pressurization vessel  202 , at least two successive pressurization vessels  402 ,  404 , and a last pressurization vessel  204 , all fluidly connected in series. The ozone-containing gas  102  is first fed to fill all of the pressurization vessels  202 ,  204 ,  402 ,  404  with the ozone-containing gas  102  at a first pressure. The pressurization gas  110  is fed into a first pressurization vessel  202  and the pressurized ozone-containing gas  108  flows out of a last pressurization vessel  204 . In this embodiment, a pressurized gas mixture is withdrawn from the first pressurization vessel  202  and fed to the successive pressurization vessels  402  and  404  in series via a plurality of gas transfer conduits  406 ,  408 ,  410 . The pressurized gas mixture then flows from the successive pressurization vessels  402  and  404  to the last pressurization vessel  204 . The pressurized ozone-containing gas  108  is then withdrawn from the last pressurization vessel  204  after the ozone pressurization system  106  reaches a second pressure. As described above, in a preferred embodiment, the incoming gases flow into the lower portions of the respective vessels and the outgoing gases exit the upper portions of the respective vessels.  
         [0038]     In one embodiment of the current invention, a continuous supply of pressurized ozone feed is supplied. In the embodiment, the pressurization vessels upstream of the last pressurization vessel  204  are replenished with ozone-containing gas  102 . To accomplish this, the tanks upstream of the last pressurization vessel  204  are vented of their pressure, purged, re-filled with the ozone-containing gas  102 , and re-pressurized as described above. This new batch of pressurized gas may then be released into the last pressurization vessel  204 . This re-filling gives a slightly more dilute ozone mixture. A more efficient arrangement consists of several sets of tanks, operated in a “round robin” to maximize the use of the ozone generator, capture all pressurized ozone that does not reach the last pressurization vessel  204 , and minimize the waste of pressurization gas  110  by allowing the sets of tanks to be cross-tied.  
         [0039]     Now referring to  FIG. 5 , the current inventive method also provides an ozonated liquefied dry gas  502  by transferring a liquefied dry gas  504  to an expansion vessel  506  and sparging the pressurized ozone-containing gas  110  through the liquefied dry gas to form the ozonated liquefied dry gas  502 . In one embodiment of this method, the liquefied dry gas  504  is stored in a liquefied dry gas storage vessel  508  at a pressure suitable to maintain the dry gas in liquid form. The liquefied dry gas  504  is transferred to the expansion vessel  506  where the pressure is somewhat less than the pressure in the liquefied dry gas storage vessel  508 . The ozone pressurization system  106  pressurizes an ozone-containing gas  102  as described in the previous embodiments to form a pressurized ozone-containing gas  110  at a second pressure, which is above the pressure in the expansion vessel  506 . The second pressure is preferably at least about 50 psig above the pressure in the expansion vessel  506 , and more preferably at least about 100 psig above the pressure in the expansion vessel  506 . The pressurized ozone-containing gas  110  is then sparged through the liquefied dry gas in the expansion vessel  506  to form the ozonated liquefied dry gas  502 . The ozonated liquefied dry gas is withdrawn from the expansion vessel  506  after sufficient sparging to assure the liquid contains a desired amount of ozone. In one embodiment, the expansion vessel  506  is substantially filled with the liquefied dry gas  504  and then the pressurized ozone-containing gas  110  is sparged through the liquid on a batch basis. In other embodiments, there is a continuous flow of liquefied dry gas  504  into the expansion vessel  506  and the pressurized ozone-containing gas  110  is sparged continuously through the liquid. This method may further include steps of withdrawing a vent gas  510  from the expansion tank. In some embodiments, the vent gas  510  is fed to a recovery system  512  for recovery and recycling of the vent gas back to the liquefied dry gas storage vessel  
         [0040]     Still referring to  FIG. 5 , one embodiment of the current invention uses CO 2  as the liquefied dry gas. In this embodiment, the pressure in the liquefied dry gas storage vessel  508  is about 200 to about 400 psig. The liquefied dry gas  504  is transferred to the expansion vessel  506  where the pressure is preferably about 100 to about 200 psig, more preferably about 150 to 200 psig, and even more preferably about 200 to about 300 psig. The ozone pressurization system  106  provides the pressurized ozone-containing gas  110  at a second pressure, which is above the pressure in the expansion vessel  506 , preferably at least about 50 psig above the pressure in the expansion vessel  506 , and more preferably at least about 100 psig above the pressure in the expansion vessel  506 . The ozonated liquefied dry gas is withdrawn from the expansion vessel  506  after sufficient sparging to assure the liquid CO 2  contains a desired amount of ozone. By this method, an ozonated liquid CO 2  can be supplied containing at least about 200 ppm wt ozone, and more preferably greater than about 250 ppm wt ozone. As is shown in  FIG. 5 , the current method provides an ozonated liquid with a much higher concentration of ozone that the prior art methods of saturating water with ozone.  
         [0041]     Another embodiment of the dry gas pressurization method described above is used to dose other liquids, including aqueous and dry (non-aqueous) liquids. In one embodiment of the invention, the dry gas compression method is used to ozonate a liquid, where the liquid is at pressures greater than about 150 psig. In this embodiment, a liquid is placed into a pressure vessel where the pressure is greater than about 150 (or is raised to above this pressure), preferably great than about 200 psig, and more preferably greater than about 300 psig. The ozone pressurization system provides the pressurized ozone-containing gas at a second pressure, which is above the pressure in the pressure vessel, preferably at least about 50 psig above the pressure in the expansion vessel, and more preferably at least about 100 psig above the pressure in the expansion vessel. The ozonated liquid is withdrawn from the pressure vessel after sufficient sparging to assure the liquid contains a desired amount of ozone.  
         [0042]     Although the present invention has been described in considerable detail with reference to certain preferred versions and examples thereof, other versions are possible. For instance, any liquid which one skilled in the art wishes to saturate with ozone can be substituted for the liquefied dry gas of the current invention in the method. Furthermore, there is a large variety of configurations of vessels, pipes, and other equipment that can be used as pressurization vessels. Clearly, the current invention may be used in a variety of processes for processing food, or non-food items. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred versions contained herein.  
         [0043]     All the features disclosed in this specification (including any accompanying claims, abstract, and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.