Abstract:
An antimicrobial treatment method for treatment of solid and semisolid foods in industrial food transport systems is provided. For solid and semisolid food applications, the method and related apparatus comprises a conveyor-based transport system in which antimicrobial additives are added to food packaging. The additives are metered into the packages using optical sensors to identify the size of packages, the amount of additive to be administered, and when such packages are in position to receive administration of the additives. The method is capable of realizing greater than 3 log reductions in live microbes in foodstuffs. The technology may also be used to apply any liquid or semi-solid additive or ingredient into packaging, including in nonfood applications such as medical equipment manufacturing.

Description:
CROSS REFERENCES 
       [0001]    None. 
       GOVERNMENTAL RIGHTS 
       [0002]    None. 
       BACKGROUND OF THE INVENTION 
       [0003]    Undercooked or contaminated foodstuff has caused illness since ancient times. Today, a wide variety of food processing techniques are used to reduce the risk of food-borne illness, and these techniques include the time-honored methods of heating, toxic inhibition (smoking, pickling, etc.), dehydration, low temperature inactivation (freezing) in addition to more modern techniques such as oxidation, osmotic inhibition (use of syrups), freeze drying, vacuum packing, canning, bottling, jellying, heat pasteurization, and irradiation. Generally, such processes do not actually sterilize food, as full sterilization adversely affects the taste and quality of final foodstuffs, but instead reduce microbial content and inhibit further microbial growth. Despite the numerous processes available to food manufacturers to reduce microbes in food, the risk of food-borne illness continues and thus remains the focus of continuing research and development. 
         [0004]    Although generally preventable, food-borne illness remains a serious problem to food consumers, government, and industry. Over one-quarter of the population of the United States is affected every year by food-borne illnesses; contaminated food has been estimated by the World Health Organization to cause 76 million illnesses in the U.S. each year, including 325,000 cases resulting in hospitalization and 5,000 deaths. In many cases, microbial contamination occurs during handling when preparing food for retail sale. Although sanitation policies have been improving during recent years, it has proven very difficult to eliminate contamination and pathogens associated with preparing, handling, and processing food at an industrial level. For example,  Listeria monocytogenes  cannot be eliminated from food or food processing environments using present technologies. A survey by USDA-FSIS showed that between 1% and 10% of retail ready-to-eat deli foods were contaminated with  L. monocytogenes . The potential contamination of these and other microbes in foodstuff processing environments presents a serious and continuing food safety threat, which has promoted interest in applying non-heat treatment to foods that kills bacteria and preserves food characteristics. Treating cut fruits and vegetables, seafood, cheese, deli food, meat, poultry, and other foodstuff with non-heat antimicrobial alternatives can reduce or eliminate the presence of microbes. 
         [0005]    It is known that more preventative approaches to food safety can reduce or eliminate physical, chemical, and biological hazards in food. “Hazard Analysis and Critical Control Points” (“HACCP”) is a systematic approach to the handling, preparation, and storage of food that aims to prevent food-borne illness at its source rather than inspecting finished products. HACCP works by identifying the steps at which contamination of food is known to occur, and then controlling the environment surrounding food products during those steps, i.e., preventing the entry of contaminants into the sealed processing environment. HACCP is not a process to treat contaminated product; rather, HACCP is a testing methodology to ensure that each step in the process is free from contaminants as well as a strict recording system to verify the results. It is an object of the invention to reduce or eliminate food-borne microbes at virtually any or all stages of an industrial foodstuff processing or preparation system. 
         [0006]    The prior art in the field of treating industrial foodstuff to minimize or reduce microbes and contaminants varies widely in form and function, but most references report results measured as the reduction of microbial content between two or more assays in units of “logs,” which represents the difference in microbial content between two assays in terms of orders of magnitude. For example, a commonly sought after and reported goal in the prior art is a reduction by 3 log, which means that the microbial content in a particular sample was reduced by 3 orders of magnitude to 0.1% of its original content. It is thus an object of the invention to utilize an industry standard measurement of effectiveness and to likewise provide for at least a 3 log reduction in microbial content. 
         [0007]    Perhaps the oldest approach to eliminating harmful microbes from food is by application of substantial heat. However, the use of heat as an antimicrobial has its drawbacks, including that heat cooks food such that its use is not always appropriate, especially where food is already cooked and is in the process of being packaged. It is an object of the invention to meet or exceed the sanitary achievements surrounding the use of heat while also avoiding the application of heat above that of the ambient temperature at which the food is being processed. 
         [0008]    Other more technological methods of destroying microbes on food have been developed in recent years. For instance, U.S. Pat. No. 5,879,732 issued to Caracciolo et al (the &#39;732 patent) discloses a food processing method where animal carcasses are sprayed with an antimicrobial gas/liquid mixture. Because the antimicrobial treatment is gaseous, the treatment must be performed in a chamber that is at least partially enclosed and that has exhaust gas scrubbers to avoid contamination of the processing environment. Furthermore, the gas/liquid mixture is not precisely metered, as evidenced by the fact that the &#39;732 patent requires a drainage pool to capture excess liquid. These drawbacks mean than the &#39;732 patent cannot be retrofitted to industrial conveyor systems of the prior art. It is an object of the invention to provide an antimicrobial treatment device that uses precisely metered liquid to treat foodstuff and which can be retrofitted to preexisting industrial conveyor systems. 
         [0009]    U.S. Pat. No. 6,964,788 issued to Phebus et al (the &#39;788 patent) uses a liquid treatment to disinfect foodstuffs whereby cooked foodstuff passes through a clean room on a conveyor and is indiscriminately sprayed with disinfectant, which must be collected and recycled. It is an object of the invention to treat cooked foodstuff with an antimicrobial liquid without the need for a clean room, a collection pool, or a recycling mechanism. 
         [0010]    It is a further object of the invention to disclose new methods of non-thermal anti-microbial treatment that hold significant promise for reducing or eliminating microbes from solid and semisolid materials. 
         [0011]    Deficiencies of sterilization techniques plague other industries as well, particularly the medical field. Accordingly, it is a further object of the invention to apply to industries in which sterilized items, whether solid or semisolid materials, are desirable. 
         [0012]    The apparatus in accordance with the invention provides reliable and relatively inexpensive non-thermal pasteurization and anti-microbial treatment of solid and semisolid materials. 
       BRIEF SUMMARY OF THE INVENTION 
       [0013]    This antimicrobial treatment process and related apparatus solves many different problems of microbial contaminations in solid and semisolid materials. The processes and apparatuses of this invention can be used with solid and semisolid materials before, during, or after processing or packaging. Specifically, the invention comprises an inline antimicrobial device (IAMD) designed to apply antimicrobial additives to foodstuffs during processing. 
         [0014]    Generally, inline manufacturing processing of solid and semisolid food involves a series of conveyors that transport foodstuff at a predetermined velocity and inter-spacing to allow for adequate inspection and packaging. Solid and semisolid foodstuff processing continues uninterrupted until such time as it is desirable to treat the foodstuff with an antimicrobial treatment; in prior art applications using heat, for instance, the inline conveyor system was interrupted to apply batch antimicrobial heat treatments in an oven. In contrast to the prior art, the invention is useful for inline solid and semisolid food conveyor systems in that the invention contemplates antimicrobial treatment as a component of the inline conveyor system rather than a separate, batch-type component. 
         [0015]    The invention utilizes an IAMD that applies liquid additives to foodstuffs. As foodstuff moves along a conveyor through the IAMD, an optical sensor detects when foodstuff is moving through the IAMD. The sensor triggers precisely-metered nozzles to spray or drip discrete amounts of antimicrobial additives onto the foodstuff. In contrast, prior art solutions either treated individual packages in a batch process or utilized a continuous spray to treat constantly-moving packages. The former solution wasted time, while the latter wastes antimicrobial additive and also affects the properties of the packaging material and the effectiveness of packaging seals. The invention thus represents an advance in the art due to increased efficiency and improved packaging of industrial food processing systems. 
         [0016]    These and other advantages provided by the invention will become apparent from the following detailed description which, when viewed in light of the accompanying drawings, disclose the embodiments of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a perspective view of the preferred embodiment of the inline antimicrobial device. 
           [0018]      FIG. 2  is a partial top view of the inline antimicrobial device taken along line  2 - 2  of  FIG. 1 . 
           [0019]      FIG. 3  is a partial side view of the inline antimicrobial device taken along line  3 - 3  of  FIG. 2 . 
           [0020]      FIG. 4  is a partial side view of the inline antimicrobial device taken along line  4 - 4  of  FIG. 2 . 
           [0021]      FIG. 5  is a graph showing the movement of packages under the inline antimicrobial device over time. 
       
    
    
     LISTING OF COMPONENTS 
       [0000]    
       
         
           
               101 —inline antimicrobial device (“IAMD”) 
               103 —conveyor 
               105 —foodstuff 
               107 —frame 
               109 —plumbing system 
               111 —applicator system 
               113 —programmable logic controller (“PLC”) 
               115 —storage tanks 
               117 —tubing 
               119 —housing 
               121 —distributor 
               123 —nozzles 
               125 —conduit 
               127 —nozzle cabling 
               129 —PLC cabling 
               131 —optical sensors 
               133 —optical sensor cabling 
               135 —packaging material 
           
         
       
     
       DETAILED DESCRIPTION OF THE INVENTION 
       [0040]    The preferred embodiment of the invention is designed for industrial food processing facilities but may be used in conjunction with standardized processing of materials and products other than foodstuff. The invention comprises an inline antimicrobial device  101  (“IAMD”) that applies precisely metered amounts of fluid additives to foodstuffs moving past the IAMD on a conveyor. IAMD  101  is typically used immediately prior to final product packaging and sealing steps. 
         [0041]    Turning now to  FIG. 1 , IAMD  101  is designed to work in conjunction with a conveyor  103  that is part of a larger conveyor-based industrial food processing system that moves foodstuff  105  to and through various food processing stations such as IAMD  101 . IAMD  101  comprises a frame  107 , plumbing system  109 , an applicator system  111 , and a programmable logic controller  113  (“PLC”). 
         [0042]    Plumbing system  109  further comprises one or more storage tanks  115 , tubing  117 , and one or more regulators  119 . Storage tanks  115  may be mounted to frame  107  and serve as a reservoir for the liquid additive that is utilized by applicator system  111 . While additive fluid may be pumped from storage tanks  115  to applicator system  111 , storage tanks  115  are preferably pressurized in order to provide adequate delivery pressure to applicator system  111 . As seen in  FIG. 1 , more than one storage tank  115  may preferably used to serve as a ballast that assists the regulator in maintaining the pressure in tubing  117  required by applicator system  111 . Furthermore, in most industrial applications, two or more storage tanks  115  will be used to store large amounts of additive in a first storage tank  115  at low pressure, which is pumped into a pressurized second storage tank  115 . 
         [0043]    The preferred pressure for a single storage tank  115  is between 0.1 to 10 psi, or higher depending on the amount of additive fluid to be administered. When more than one storage tank  115  are used, the single storage tank  115  connected to applicator system  111  via tubing  117  is also preferably pressurized to between 0.1 and 10 psi, whereas the pressure of additional storage tanks  115  will vary in relation to their usable volume as compared to the storage tank connected to applicator system  111 . 
         [0044]    Plumbing system  109  delivers additive fluid, preferably pressurized to between 0.1 and 10 psi, to applicator system  111  through regulator  119  and tubing  117 . Regulator  119  lowers the pressure of the additive fluid from the pressure in storage tank  115  to the desired pressure for use in applicator system  111 . The greater the difference in pressure between storage tank  115  and the desired pressure for applicator system  111 , the higher the rate at which additive fluid  111  may be administered at a relatively constant pressure. 
         [0045]    Turning now to  FIGS. 2 ,  3 , and  4 , applicator system  111  further comprises a housing  119 , a distributor  121 , one or more nozzles  123 , conduit  125 , nozzle cabling  127 , PLC cabling  129 , one or more optical sensors  131 , an optical sensor cabling  133 . Additive fluid delivered to applicator system  111  enters distributor  121  and is pressure-delivered to nozzles  123  via conduit  125 . Nozzles  123  are preferably configured to provide a spray pattern that matches the shape of foodstuff  105  being treated by IAMD  101 . Nozzles  123  are controlled by PLC  113 , and as such nozzles  123  must be wired to PLC  113  using nozzle cabling  127  and PLC cabling  129 . Nozzles  123  preferably have electronically-controlled valves that may be rapidly opened and closed by instructions received from PLC  113 . Optical sensors  131  deliver information to PLC  113  via optical sensor cabling  133  about the position of foodstuff  105  on conveyor  103  in relation to applicator system  111 . 
         [0046]    PLC  113  determines when to administer additive fluid to foodstuff  105  by calculating whether foodstuff  105  is located under one or more nozzles  123 . Two factors influence such calculation: first, optical sensor  131  provides a signal to PLC  113  when foodstuff  105  is located substantially beneath optical sensor  131 . Preferably, optical sensor can differentiate between packaging material  135  and foodstuff  105 . Second, PLC  113  and/or optical sensor  131  determine the linear velocity of conveyor  103 . From these two inputs, PLC  113  can determine the location of food with respect to nozzles  123 . 
         [0047]    As an example of the method by which IAMD  101  applies additive fluid to foodstuff  105 , assume that applicator system  111  is approximately 60 cm in length, optical sensors  131  are 3 cm from nearest nozzles  123 , nozzles  123  are separated by 15 cm, foodstuff  105  is 10 cm long, and separate articles of foodstuff  105  are separated by 3 cm. The conveyor moves at 50 cm/s. Nozzles are separated into four groups (NG1 to NG4), each group having two nozzles  123  in a line perpendicular to the movement of conveyor  103 . Distance refers to the position of the leading edge of foodstuff  105  as compared to optical sensor  131 . For instance, a distance of −10 cm means that when the conveyor moves another 10 cm, foodstuff  105  will just be beneath the optical sensor. A distance of 10 cm means that the entire article of foodstuff  105  has just passed beneath optical sensor  131 . The following table illustrates when PLC  113  will instruct particular nozzles  123  to turn on to dispense additive fluid while a continuous stream of articles of foodstuff  105  enters IAMD  101 : 
         [0000]    
       
         
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 t (s) 
                 d (cm) 
                 NG1 
                 NG2 
                 NG3 
                 NG4 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 0.0 
                 0 
                 off 
                 off 
                 off 
                 off 
               
               
                   
                 0.1 
                 5 
                 on 
                 off 
                 off 
                 off 
               
               
                   
                 0.2 
                 10 
                 on 
                 off 
                 off 
                 off 
               
               
                   
                 0.3 
                 15 
                 off 
                 off 
                 off 
                 off 
               
               
                   
                 0.4 
                 20 
                 on 
                 on 
                 off 
                 off 
               
               
                   
                 0.5 
                 25 
                 on 
                 on 
                 off 
                 off 
               
               
                   
                 0.6 
                 30 
                 on 
                 off 
                 off 
                 off 
               
               
                   
                 0.7 
                 35 
                 on 
                 on 
                 on 
                 off 
               
               
                   
                 0.8 
                 40 
                 off 
                 on 
                 on 
                 off 
               
               
                   
                 0.9 
                 45 
                 on 
                 on 
                 off 
                 off 
               
               
                   
                 1.0 
                 50 
                 on 
                 on 
                 on 
                 on 
               
               
                   
                 1.1 
                 55 
                 on 
                 off 
                 on 
                 on 
               
               
                   
                 1.2 
                 60 
                 on 
                 on 
                 on 
                 off 
               
               
                   
                 1.3 
                 65 
                 on 
                 on 
                 on 
                 on 
               
               
                   
                   
               
             
          
         
       
     
         [0048]    This table is provided to illustrate the role of PLC  113  and is graphically represented in  FIG. 5 . Persons having ordinary skill in the art will be able to program PLC  113  to perform the functions exemplified in the above table without undue experimentation, and will recognize that such tables are not intended to limit the scope of the invention to the specific dimensions assumed. 
         [0049]    The next consideration for PLC  113  is to determine how much additive fluid should be applied to foodstuff  105 . Typical food processing lines measure movement in terms of mass per unit velocity (i.e., 100 kg/h @ 3 m/s). Thus, in a typical assembly line, if the velocity of movement is known, the mass is also known. The amount of additive appropriate for any given foodstuff is typically determined by the mass of the foodstuff. Thus, for a given assembly line, the PLC  113  will need to be programmed with the amount of additive to be applied and the mass per unit velocity. Then, the amount of additive fluid to be administered may be calculated from the speed of conveyor  103 . For example, when conveyor  103  speeds up, more additive fluid is administered per unit time. PLC  113  may also take into account the pressure, temperature, and viscosity of additive fluid and the flow curves nozzles  123  exhibit under such conditions. 
         [0050]    As an example of how PLC  113  determines the amount of additive fluid to apply, assume that the appropriate amount of additive fluid is 10 ml kg, that conveyor  103  moves at 150 cm/s, that each article of foodstuff  105  has a mass of 0.5 kg and is 10 cm long, and that each article of foodstuff will pass under 4 nozzles  123 . In this situation, PLC  113  would instruct each of the 4 nozzles  123  to administer 1.25 mL of additive in the 0.067 s it takes for the food to pass under each nozzle, for a total of 5 mL of additive. Persons having ordinary skill in the art will be able to program PLC  113  to perform the functions in the example above without undue experimentation, and will recognize that such example is not intended to limit the scope of the invention to the specific quantities assumed. 
         [0051]    The invention may also be utilized in a conveyor-based food processing system in which the movement of conveyor  103  is semi-continuous. For semi-continuous movement of conveyor  103 , the movement of conveyor  103  may be defined in terms of index per unit time. The index is defined as number of articles of foodstuff  105  or the length of conveyor moved past a demarcation point, such as optical sensors  131 , in one semi-continuous movement of conveyor  103 . One semi-continuous movement of conveyor  103  is referred to as an interval. In a semi-continuous embodiment, IAMD  101  applies additive fluid to foodstuff  105  while conveyor  103  is in a stopped position. Preferably, in the semi-continuous method the spray pattern of nozzles  123  match the shape of foodstuff  105  so an even treatment of additive fluid is applied. As discussed above, the amount of additive fluid applied will depend on the mass of foodstuff  105 . For example, assume that four articles of foodstuff  105  move past optical sensor  131  in a given interval; IAMD  101  has four nozzles  123 ; each article of foodstuff has a mass of 0.5 kg; and the appropriate amount of additive fluid is 10 mL/kg. In this situation, each nozzle  123  would release 0.5 mL of additive fluid during each interval. 
         [0052]    The invention may be utilized in virtually any conveyor-based processing system. The volumetric capacities of plumbing system  109  and applicator system  111  may be scaled up or down to match the mass per unit velocity required by the particular application. At present, the inventor has realized granularity for application of additive fluid as low as &lt;0.5 mL per cycle of nozzle  123 . 
         [0053]    The additive fluid contemplated by the invention may be any liquid or semi-solid additive beneficial for use in a conveyor-based system, which may vary depending on the particular application desired by the user. Preferably, the additive fluid comprises a mixture of 5% acetic acid solution, 0.1% propionic acid solution, and 0.1% benzoic acid solution. The additive fluid may also be gaseous, provided that appropriate steps are taken by the user to prevent contamination of the processing environment with the gaseous additive. 
         [0054]    While the inventors have described above what they believe to be the preferred embodiments of the invention, persons having ordinary skill in the art will recognize that other and additional changes may be made in conformance with the spirit of the invention and the inventors intend to claim all such changes as may fall within the scope of the invention.