MXPA97009554A - Automatic procedure for inhibition of microbial growth in aqueous transport currents or alime procedure - Google Patents

Abstract

The present invention relates to: a method for preventing the growth of microbes in aqueous streams, by applying a C2-C12 percarboxylic acid or a mixture of acid acids to the aqueous stream and to an automatic assortment system for percarboxylic acids, based on a correlation between the oxidation reduction potential and the antimicrobial levels of the aqueous stream. Generally, the process of the invention is applicable to aqueous streams used in any number of applications such as the application of currents for the transport of food products, for example, fruits or vegetables, to the processing environment and through the various steps of processing

Description

AUTOMATIC PROCEDURE FOR THE INHIBITION OF MICROBIAL GROWTH IN AQUEOUS CURRENTS OF TRANSPORTATION OR PROCEDURE OF ALI MENTO FIELD OF THE INVENTION The invention relates to the control of microbial growth in aqueous streams. More specifically, the invention relates to the control of microbial growth in aqueous streams used to transport or process food products in processing environments, such as fruit, vegetables and food products, for example, mushrooms, poultry, tomatoes, and the like.

BACKGROUND OF THE INVENTION The arrival of food processing has a long time since the revolution of both food availability and consumer expectation for a wide variety of high quality products. Initially, food processing techniques included canning, and then refrigeration, freezing, freeze drying as well as vacuum packing. The application of several covation systems of constituent base and base of procedure has led to a wider availability of high quality food products. In turn, the price and availability of food has generally been subject to various restrictions, including environmental hazards, as well as natural weather cycles, selection and processing considerations, and total economic and market constraints. Given the large number of foods selected and processed on an annual basis, as well as the relative uncontrollable aspect of factors such as the environment and trade, producers strive to economize in the selection and processing of food products. A means to process a large volume of food, such as, for example, fruits and vegetables, is after selection, to transport these various food products through an aqueous medium to supply the food products through several processing steps and environments. For example, in specific applications, fresh fruits and vegetables can be transported through water currents through food handling equipment used in the processing plant. After harvesting, fruits and vegetables are introduced into a discharge channel system, where water acts as a means of transport and a means of cleaning. The water can be used to hold and transport the fruits or vegetables from a place of discharge to a storage or packaging site or final processing. During transportation, water can take a food item from an initial location through a series of slightly separated stages to a final station, where the product is removed from the water and packaged. The water within each stage can have a variable degree of organic charge in the form of any number of sediments and soluble materials. This water can be generally recirculated. The water may also be used in any of the processing steps to clean, cool, heat, cook, or otherwise modify the food product in some way before packing. The process water, as defined above, can sometimes be used once and discarded. However, usually a major portion of this process water is reused and, therefore, is subject to organic and microbial contamination. In some stages, this process water stream is also used to transport the food. In other steps, the process water may be a separate stream and is recirculated separately from the transport water. In any situation, the process water is contaminated with organic matter from the food, providing nutrients for the growth of microbes in the water. Examples of different types of process water are vegetable washers, vegetable cooling baths, poultry chillers and, meat washers. Given the nature of the food, as well as the presence of sediments and soluble materials, the water, the discharge channel, and other transport or processing equipment may be subjected to the growth of unwanted microorganisms. These microorganisms are generally undesirable for food, water, the discharge channel, and can cause the development, on all surfaces in contact with water, of lama or biofilm, which requires frequent cleaning for removal. In addition, since the transport water, the process water and the equipment are in contact with the food products, the control of unwanted microorganisms presents certain problems created by an environment of contact with the food that contains microorganisms. In the preceding discussion, it has been assumed that transport or process water is put in contact with the food before packing. There are also aqueous streams used to process certain types of food subsequent to packaging. Some foods are usually processed hot, cold, or otherwise after being placed in packages of metal, glass, or plastic containers, for example, bottled beer pasteurizers, cookers, or soft drinks. In all cases, the contamination of the aqueous streams by food occurs due to spillage of defective packages or spillage on the outside of the package during the packaging operation. These packaged food process streams are also, therefore, subjected to unwanted growth of microbes and high concentrations of organic matter similar to pre-packaged process and transport water. Ideally, an antimicrobial agent or compound used in such a system will have several important properties in addition to its antimicrobial efficacy. The compound or agent should not have any residual antimicrobial activity on the food. The residual activity implies the presence of a film of antimicrobial material, which will continue to have an antimicrobial effect which may require an additional rinse of the food product. The antimicrobial agent should preferably also be free of odor to prevent the transfer of undesirable odors on food products, if direct contact of the food occurs, the antimicrobial agent should also be composed of food additive materials, which will not affect the food if contamination occurs, nor will it affect human beings if incidental ingestion occurs. In addition, the antimicrobial agent should preferably be composed of naturally occurring or harmless ingredients, which are chemically compatible with the environment and do not cause any concept for toxic waste in water. In the past, the transport and process water apparatus was generally treated with sodium hypochlorite and chlorine dioxide. Generally, these materials are effective to prevent the unwanted growth of microorganisms. However, the regime of use of these chlorine-based antimicrobials is very high because they tend to be quickly consumed by the high organic load included in both fruits and vegetables and in the soil. In addition, after consumption, compounds such as chlorine dioxide decompose producing byproducts such as chlorites and chlorates, while hypochlorite produces trichloromethanes, which can be toxic at very low concentrations. Finally, chlorine dioxide is a toxic gas with an acceptable air concentration limit of 0.1 ppm. Exposure to CIO2 usually leads to headaches, nausea, and respiratory problems, requiring expensive and complicated safety devices and equipment when used. Iodophorous antimicrobial agents have also been used for several antimicrobial applications. Nevertheless, the iodophor compounds tend to decompose or may be lost by evaporation when used in an aqueous medium. In this way, long-term activity requires a high concentration of iodophor. Generally, the art has taught against the use of percarboxylic acids as antimicrobial agents in aqueous streams due to the stability aspects of the compound in the presence of high concentrations of organic matter. As a result, there is a need in the food processing industry to provide means for transportation and food processing, which also control the loading of dirt and microbes in the aqueous system without the use of high concentrations of antimicrobials such as chlorinated compounds and other halogenated constituents.

COMPENDIUM OF THE INVENTION The invention is a method for preventing the growth of microbes in aqueous streams, comprising the step of applying a percarboxylic acid or a mixture of percarboxylic acids to the aqueous stream. The application of percarboxylic acids uses an automatic assortment and control system. The method uses a probe and oxidation reduction potential controller (ORP), coupled with a percarboxylic acid assortment pump and time controllers, to control the concentration of percarboxylic acid in a production or packaging discharge channel system . The method involves an initial charge and then control of the percarboxylic acid in a discharge channel system using an ORP controller with a low and high alarm contact setting. The invention is based on the finding of a correlation between an "effective antimicrobial" level of residual percarboxylic acid in a discharge channel system and the ORP of that system. Accordingly, the invention is an automatic method for controlling the growth of microbes in an aqueous stream used to transport or process food products and packaged foods, which comprises treating said aqueous stream with an antimicrobial effective amount of a percarboxylic acid, said controlled amount. maintaining the aqueous stream at an oxidation reduction potential (ORP) of from about 280 to about 460 mv with respect to a reference electrode Ag / AgCl or, preferably between about 310 and 440 mv. More specifically, the invention is an automatic method for controlling the growth of microbes in an aqueous stream used for transportation and processing of food products and packaged goods, comprising the steps of: initially charging a percarboxylic acid to said aqueous stream until it reaches an oxidation reduction potential (ORP) of at least 280 mv with respect to an Ag / AgCl reference electrode, and allow the continuous addition of percarboxylic acid to the aqueous stream, where the addition is controlled by an ORP controller set between approximately 280 and 460 mv with respect to a reference Ag / AgCl electrode. The method of the invention is unexpectedly effective to prevent the growth of unwanted microorganisms in the apparatus for transporting and processing food. The consumption of peracetic acid is unexpectedly low in view of the organic load of both fruits or vegetables and microbial soils in the water. The method of the invention provides an antimicrobial agent useful in water for transporting and processing food products, which has a high degree of antimicrobial efficacy and which can be safely ingested by humans, since it does not impose any environmental incompatibility. The differentiation of the "acid" or "static" antimicrobial activity, the definitions of which describe the degree of efficacy, and the official laboratory protocols for measuring this efficacy are important considerations for the understanding of the applicability of antimicrobial agents and compositions. The antimicrobial compositions can effect two types of microbial cell damage. The first is a truly lethal, irreversible action, resulting in the complete destruction or incapacity of the microbial cell. The second type of cell data is reversible, so that if the organism is released or the agent, it can multiply again. The first is called bacteriocide and the last is bacteriostatic. A sterilizer and a disinfectant are, by definition, agents that provide antibacterial or bacteriocidal activity. In contrast, generally a conservative is described as an inhibitor or bacteriostatic composition.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a graphic representation of the results of the Working Example 3. Figures 2 and 3 are graphic representations of the results of the Working Example 4. Figure 4 is a schematic representation of a discharge channel system used in conjunction with the Working Example 5. The Figure 5 is a graphical representation of certain results obtained from Working Example 5. Figure 6 is a schematic representation of the automatic assortment and control system. Figure 7 is a circuit diagram of the components in the control panel of Figure 6.

DETAILED DESCRIPTION OF THE INVENTION The following describes in more detail the automatic assortment method, applying an effective antimicrobial concentration of a percarboxylic acid composition to prevent the growth of microbes in aqueous streams.

CARBOXYLIC ACID Among other constituents, the percarboxylic acid composition comprises a carboxylic acid. Generally, carboxylic acids have the formula R-COOH, wherein R can represent any number of different groups, including aliphatic groups, alicyclic groups, aromatic groups, heterocyclic groups, all these may be saturated or unsaturated, as well as substituted or unsubstituted . The carboxylic acids also occur having one, two, three or more carboxyl groups.

The carboxylic acids tend to acidify aqueous compositions, in which they are present as the hydrogen atom of the carboxyl group is activated, and can appear as an anion. The carboxylic acid constituent in the present invention, when combined with aqueous hydrogen peroxide, generally functions as an antimicrobial agent as a result of the presence of the active hydrogen atom. In addition, the carboxylic acid constituent within the invention maintains the composition at an acidic pH. The carboxylic acids, which are generally useful in the process of the invention, are those comprising percarboxylic acids. The percarboxylic acids generally have the formula R (CO 3 H) n, wherein R is an alkyl, arylalkyl, cycloalkyl, aromatic or heterocyclic group, and n is 1, 2 or 3, and designated by prefixing the main acid with peroxy. The percarboxylic acids can be made through the direct action of acid-catalyzed equilibrium of 30-98% by weight of hydrogen peroxide with the corresponding carboxylic acid, through the self-oxidation of aldehydes, or acid chlorides, or carboxylic anhydrides with hydrogen or sodium peroxide. The precarboxylic acids useful in this invention include C2-C2-percarboxylic acids such as, for example, peracetic acid, perpropionic acid, perbutyric acid, perotanoic acid, perglycolic acid, perglutaric acid, persuccinic acid, perlactic acid, percyclic acid, acid perdecanoic, or mixtures thereof. It has been found that these percarboxylic acids provide a good antimicrobial action with good stability in aqueous streams. The process of the invention also uses a combination of peracetic acid with other percarboxylic acids, preferably those mentioned above and in particular, peroctanoic acid. It has been found that this combination of percarboxylic acids provides preferred antimicrobial efficacy and stability in the presence of high organic loads. Generally, within the sterilizer, the concentration of, for example, peroctanoic acid may vary from about 10% by weight to 90% by weight, and preferably from about 10% by weight to 20% by weight. The concentration of peracetic acid can vary from about 10% by weight to 90% by weight, and preferably from about 80% by weight to 90% by weight. In its highly preferred mode, the method of the invention utilizes peracetic acid. Peracetic acid can be prepared through any number of means known to those skilled in the art, including preparation from acetaldehyde and oxygen in the presence of cobalt acetate. A 50% solution of peracetic acid can be obtained by combining acetic anhydride, hydrogen peroxide and sulfuric acid. Other methods for the formulation of peracetic acid include those described in the patent of E.U.A. Do not . 2,833, 813, which is incorporated herein by reference.

HYDROGEN PEROXIDE The antimicrobial composition of the invention may also comprise a hydrogen peroxide constituent. Hydrogen peroxide in combination with percarboxylic acid provides a surprising level of antimicrobial action against microorganisms despite the presence of high organic sediment loads. further, hydrogen peroxide can provide an effervescent action, which can irrigate any surface to which it is applied. The hydrogen peroxide works with a mechanical washing action once applied, which further cleans the application surface. An additional advantage of hydrogen peroxide is the compatibility of the food with this composition after use and decomposition. For example, combinations of peracetic acid and hydrogen peroxide result in acetic acid, water and oxygen after decomposition, all of which are compatible with the food product. Since many oxidation agents can be used, hydrogen peroxide is generally preferred for a number of reasons. After the application of the germicidal agent of H2O2 / peracetic acid, the residue left merely comprises water and an acid constituent. The deposition of these products on the application surface, such as a discharge channel, will not adversely affect the process or the food products transported therein.

Generally, the concentration of hydrogen peroxide within the composition used in the process of the invention ranges from about 1% by weight to about 50% by weight, preferably from 3% by weight to about 40% by weight, and very preferably from about 5% by weight to 305 by weight. The concentration of hydrogen peroxide is very preferred since it provides an optimal antimicrobial effect. These concentrations of hydrogen peroxide can be increased or reduced, while remaining within the scope of the invention.

AUXILIARY The antimicrobial composition of the invention can also comprise any number of auxiliaries. Specifically, the composition of the invention may comprise stabilizing agents, wetting agents, as well as pigments or dyes between any number of constituents, which may be added to the composition. Stabilizing agents can be added to the composition of the invention to stabilize the peracid and hydrogen peroxide and prevent premature oxidation of this constituent within the composition of the invention. Commonly useful chelating or sequestering agents, as stabilizing agents, in the invention, include alkyldiamine polyacetic acid type chelating agents such as EDTA (ethylenediamine tetraacetate tetrasodium salt), acrylic and polyacrylic acid type stabilizing agents, phosphonic acid and Phosphonate type chelating agents, among others. Preferred sequestering agents include phosphonic acids and phosphonate salts including 1-hydroxyethylden-1,1-diphosphonic acid (CH3C (PO3H2) 2? H), amino [tri (methylene phosphonic)] ([CH2PO3H2] 2), ethylene acid diamin [tetramethylene phosphonic], 2-fosfen buten-1, 2,4-tricarboxylic acid, as well as the alkali metal salts, ammonium salts, or alkylarylamine salts, such as mono-, di-, or tetra-ethanolamine. The stabilizing agent is used in a concentration ranging from about 0 wt% to about 20 wt% of the composition, preferably from about 0.1 wt% to about 10 wt% of the composition, and most preferably about 10 wt% of the composition. 0.2% by weight to 5% by weight of the composition. The composition used in the process of the invention may also contain, if necessary, additional ingredients necessary to aid in defoaming. Generally, defoamers that can be used according to the invention include silicas and silicones; acids or aliphatic esters; alcohols; sulfates or sulphonates; amines or amides; halogenated compounds such as fluorochlorohydrocarbons; vegetable oils, waxes, mineral oils, as well as their sulfated derivatives; fatty acid soaps such as alkaline, alkaline earth metal soaps; and phosphates and phosphate-esters such as alkyl and alkaline diphosphates, and tributyl phosphates among others; and mixtures thereof. Especially preferred are those anti-foaming agents or defoamers, which are of food grade quality given the application of the process of the invention. Up to this point, one of the most effective foaming agents comprises silicones. Silicones such as dimethylsilicon, polysiloxane glycol, methylphenol polysiloxane, trialkyl or tetra alkyl silanes, hydrophobic silica defoamers and mixtures thereof can be used in defoaming applications. Commonly available commercial defoamers include silicones such as Ardefoam® from Armor Industrial Chemical Company, which is a silicone bonded in an organic emulsion; Foam Kill® or Kresseo® available from Krusable Chemical Company, which are silicone-type and silicone-free defoamers, as well as silicone esters; and Anti-Foam A® and DC-200 ™ from Dow Corning Corporation, which are food-grade type silicones, among others. These defoamers are generally present at a concentration ranging from about 0 wt% to 5 wt%, preferably from about 0 wt% to 25 wt%, and most preferably about 0 wt% to 1 wt%. The invention may also contain any number of other constituents as needed by the application, which are known to those skilled in the art, and which may facilitate the activity of the present invention. The composition used in the invention may comprise: Composition (% by weight) Useful Preferred Work Percarboxylic acid 2-25 2-20 4-20 H2O2 1-45 5-35 7-30 Carboxylic acid 1-70 3-55 5-45 Water Rest Rest Rest Initial Concentration in Transport Water Constituent Useful Preferred Work Percarboxylic Acid 5-100 ppm 5-60 ppm 10-50 ppm H2O2 5-500 ppm 5-300 ppm 5-250 ppm Once the antimicrobial of the invention is applied to any given transport stream or process, the antimicrobial will be subjected to a demand resulting from the microbes present in the stream, as well as other organic or inorganic material present in the stream. As a general guideline, without limiting the invention, the following concentrations of antimicrobial can be found after the demand.

Residual Concentration (ppm) after Constituent Demand Useful Work Percarboxylic acid 1-85 1-45 5-30 H2O2 1-490 1-290 1-240 Since the demand can reduce the antimicrobial concentration to zero, at least about 5 ppm of peracetic acid (POAA) is generally preferred to provide the intended efficacy.

Generation of Peroxy Acids The process of the invention can also be initiated through the use of peroxy acid concentrate compositions. In such a case, the percarboxylic acid can be either generated naturally or through the combination of a hydrogen peroxide concentrate together with a carboxylic acid concentrate in light of the use such as that procedure described by Lokkesmoe et al., Patent from the USA No. 5,122,538, issued June 16, 1992, which is incorporated herein by reference. In such a case, the composition can be formed of a hydrogen peroxide concentrate comprising varying levels of hydrogen peroxide and stabilizer as shown in the table below.

Concentration (% by weight) Constituent Useful Preferred work Percarboxylic acid 5-70 15-70 25-60 Stabilizer 0-10 0-5 0.1-3 H2O 20-95 25-85 37-75 When combined with a carboxylic acid, the two concentrates result in a peroxy carboxylic acid. Generally, the carboxylic acid concentrate comprises a carboxylic acid in water as shown in the table below.

Concentration (% by weight) Constituent Useful Preferred Work carboxylic acid 50-100 65-100 80-100 Water 0-50 0-35 0-20 AUTOMATIC ASSORTMENT AND CONTROL SYSTEM The automatic method of the present invention uses an ORP controller, time controllers and pump sequences to regulate around the effective scale (see Figure 6). A basic fixation is shown to deliver the product to a product processing discharge channel. Control panel 1 contains power timing controllers, relays, ORP controller, and air solenoids. A double diaphragm air driven pump 2 is used to dose the product from the product drum 3 to the production vessel 4. The vessel 4 may be a discharge channel, tank or product container. An ORP probe 5 is mounted on the side of the container 4 or placed below the container. Figure 7 represents a circuit diagram of the internal components within the control box. When a primary switch (see operating switch representation 20) is activated, the primary time controller 21, which determines the stroke speed of the pump, the primary operation time controller 22, which sets the primary time and the primary cycle controller 23, which regulates the load frequency, provide a preset time to feed enough product into a container in order to provide a starting concentration. The control panel 1, in Figure 6, includes an ORP controller 24, shown in Figure 7. The panel can be operated with or without a high and low concentration ORP control. If the system is going to operate with an ORP control, the fixing points of the high fixing 25 ORP and the low fixing 26 are preset at 460 mv and 380 mv, respectively. The ORP controller can control both the initial charge and the subsequent development feed of a percarboxylic acid in a discharge channel system. If the system were to attempt to feed for a longer time than the preset alarm time controller 27 when the ORP value is below the low set point 26, an alarm condition will occur. The alarm has a contact 28 normally (N. O.) and a contact 29 normally closed (N. C.). The normally closed contact is closed during non-alarm conditions. The percarboxylic acid is fed using a double diaphragm pump 2 (Figure 6) established for an individual or stroke control T. The air pulses to activate the pump are fed through an air solenoid valve 30, which obtains a signal of a primary cycle time controller on / off 23. The cycle time controller will turn on with any signal from a running time controller 31 used to feed the percarboxylic acid or N contacts in time. O. low level alarm. The energy to the operating time controller 31 is fed through the contacts N. C. for the high alarm. During the initial charge phase, with the ORP value of the antecedent of the discharge channel being typically 180-300 mv, the contacts N. O. low alarm closes directly supplying power to the primary cycle time controller 23, which activates the double diaphragm pump 2 (Fig. 6) until the low level alarm is satisfied (eg, 280 mv); at that time the contacts N. O. are opened and the operation time controller 31 controls the power supply. The rate of addition of this initial charge is relatively rapid, for example about 25 to 1500 ml per minute, since it is used to load the entire discharge channel system, which can be a total process effluent of 7568. liters or more, with percarboxylic acid; that is, from 0 ppm to ~ 10 ppm residual percarboxylic acid. If necessary, an alarm (not shown), audio or visual, may be added to this primary time controller to indicate an inappropriate load. This can stop the entire system and require a check of product emptying or recharging. Comparatively, the operation timing controller 31 feeds at a rate coinciding with the drinking water development velocity of the discharge channel and, therefore, usually operated at approximately 5-50 times slower feed speed than the initial load (for example, usually from 2 to about 150 ml per minute). In this way, after the initial low alarm is obtained, the pumping system will operate the operation timing controller 31 and maintain a continuous addition of percarboxylic acid to the discharge channel system; to sustain a residual in the concentration of percarboxylic acid. This stable state result is the desired condition. If at any time during the feeding of the operating time controller, the ORP falls below the low set alarm point, due to excess dirt / microbial load or dilution of the water, this condition could trigger the primary time controller 21 more fast during a fixation period to promote the percarboxylic acid level of the discharge channel. This attempt to recharge the system will occur until it rises above the lower limit, or until the alarm condition stops the system, when defined by the alarm timer 27; that is, when the low alarm of the ORP controller is activated, the alarm time controller 27 is also activated and the ORP must rise above the low alarm level, at the time of fixing or the system stops and activates an alarm external (not shown). If the level of percarboxylic acid reaches the high level of alarm (for example, 460 mv), contacts N. C. they open, breaking the power supply to the operating time controller and avoiding the percarboxylic acid feed. When the level of the percarboxylic acid falls below the fixation point of the high alarm, the contacts N. C. again they are closed and the secondary cycle time controller will control the feed rate of the percarboxylic acid. This allows a cyclisation of the peracetic residue around the upper fixation point. This scenario allows the automatic maintenance of an "effective" level of percarboxylic acid to control microbial populations in process waters and discharge channel packing.

WORK EXAMPLES The invention will now be described in more detail with reference to the following examples. The only appropriate construction of these examples is as non-limiting illustrative examples showing various formulations, stabilities, and applications of the invention.

WORK EXAMPLE 1 To prepare a solution supplying the peracetic acid formula (or "POAA") for use in the discharge channel experiments, the following components were combined.

Component% by weight Acetic acid 43.85 35% Hydrogen peroxide 50.85 1-Hydroxyethylidene-1, 1-dif osphonic acid Dequest 2010 (60% active) 1.5 H2O 3.8 The result of this combination was a composition that has the following constitution. % by weight Acetic acid 32.0 H2O2 11.1 Dequest 2010 0.90 H2O 41.0 Peracetic acid 15.0 WORKING EXAMPLE 2 In the second Work Example, the intermediate demand of 1% and 3% tomato solutions for POAA was determined. POAA in pure water (control) was compared with similar dilutions in 1% and 3% tomato solutions. The tomato solutions were prepared by grinding fresh tomatoes in a food processor and adding 1% or 3% by weight of the slurry to the water.

TABLE 1 Control 1% 3% (without tomatoes) Tomato Tomato Average POAA Conc (ppm) 111.8 112.25 111.0 Average Conc H2O2 (ppm) 65.2 65.3 64.7 No. of tests 3 2 1 Normal Dev (POAA) 0.61 0.21 - Normal Dev (H2O2) 0.10 0.14 - Active Chlorine (ppm) 1 98.0 34.4 49.8 1 Made of measured quantities of NaOCI concentrate added to distilled water to obtain a concentration of 100 ppm [Cl].

No initial reduction in POAA concentration was observed. This result was unexpected since POAA has been reported to react significantly with high levels of organic matter. For example, Poffe et al2 reported that low levels of POAA completely decompose immediately after contacting solutions containing a Biological Oxygen Demand (BOD) of 170 mg. O2 / liter. A solution of 1% tomatoes in water has a BOD of approximately 300 mg / l, while a solution of 3% tomatoes has a BOD of approximately 900 mg / l. Table 1 also shows the large loss of active chlorine when a sodium hypochlorite solution was tested.

WORK EXAMPLE 3 The following provides a set of stability experiments expanded to the use of peas, beans and corn. Tables 2-9 show the stability of a formula which is mostly peracetic acid (with peroctanoic acid being about 10% by weight of the total content of peracetic acid and peroctanoic acid) in solutions of 1% of these prepared vegetables as described for tomato solutions in Example 2. The initial concentrations were 70%, 100%, and 90% of the control solutions (without vegetable) para-corn, beans and peas, respectively. 2"Disinfection of Effluents from Municipal Sewage Treatment Plants with Peroxy Acids", Z61. Bakt. Hyg., I. Abt. Orig. B167, 337-46 (1978).

After 3 days, 31%, 47% and 32%, respectively, of the initial concentration of perches such as POAA, was left for these vegetables. The perished showed surprising stability in solutions comprising a high concentration of organic material. TABLE 2 (CONTROL) Total Peracids (as POAA) Day PPM% Remaining 0 18.85 100% 1 19.76 100% 2 18.77 100% 3 16.80 89% TABLE 3 (1% corn) Total Peracids (as POAA) pja PPM% Remaining 0 13.15 100% 1 8.51 65% 2 6.16 47% 3 4.03 31% Initial Control Rate = 70% TABLE 4 (1% beans) Total Peracids (as POAA) Day PPM% Remaining 0 21.36 100% 1 17.48 82% 2 14.36 67% 3 9.96 47% Initial Control Percentage = 113% TABLE 5 (1% of peas) Total of Peracids (as POAA) Day PPM% Remaining 0 18.09 100% 1 12.46 69% 2 10.41 58% 5.70 32% Initial Control Percentage = 96% TABLE 6 (CONTROL) Day H H220022 P PPPMM% Remaining 0 1 100. .3300 100% 1 1 100. .9988 107% 2 1 100 ,, 9 911 106% 3 1 100. .8855 105% TABLE 7 (1% of maize) Day H202 PPM% Remaining 0 15.67 100% 1 7.21 46% 2 5.71 36% 3 1.70 11% Initial Control Percentage = 152% TABLE 8 (1% of beans) Day H202 PPM% Remaining 0 8.84 100% 1 3.09 35% 2 1.63 18% 3 1.09 12% Initial Control Rate = 86% TABLE 9 (1% of peas) Day H202 PPM% Remaining 0 8.57 100% 1 4.83 56% 2 3.37 39% 2 0.78 9% Initial Control Rate = 83% WORK EXAMPLE 4 Experiments testing the efficacy of POAA in mold and bacteria did not show any microbial growth at concentrations of 5, 10 and 20 ppm of POAA in a 1% solution of peas. As can be seen in Figure 1, the latest experiments show good mold control with 10-30 ppm of POAA in a 1% solution of peas and continued to be classified for annihilation over a period of 3 days.

WORK EXAMPLE 5 An analysis of the invention was then taken in the context of a real discharge channel supply system. As can be seen in Figure 4, a discharge channel system comprising a development tank 10, a flow line 11, a discharge channel tank 12, an overflow tank 14, with discharge pipe or drain 13, Pump line 15, pump 16, and recirculation line 18, were assembled to modalize the conditions in food transport discharge channels used in food processing plants. The development water comprised 16 grains / gal. of CaCO3 and introduced into the discharge channel at a velocity of 343 ml / min. A pea solution was introduced into the development tank 10 comprising 10% pea milled in hard water. The pea solution was diluted to 1% in the discharge channel through a flow rate of 42.5 ml / min. A dirt solution comprising 3.6% dirt was also added to the development water, which was diluted to 0.3% in the discharge channel at a flow rate of 35 ml / min. Finally, a sterilizer was added to the discharge channel assembly and diluted by a factor of 100 through a flow rate of 42 ml / min. The initial concentration and formulation for the sterilizers analyzed can be seen in Table 10 below.

TABLE 10 Example of Active / Work Concentration Condition 5A 30 ppm POAA Sterile peas Control 1 - Sterile peas 5B NaOCI / 110 ppm Cl 5C NaOCI / 110 ppm Cl 5D 30 ppm POAA Pulsed feed 5E 40 ppm POAA Continuous feed 5F 3 ppm POAA 27 ppm POAA Control 2 5G 20 ppm C10 3.7 ml / min. vel. flow 5H 1.5 ppm POOA * 13.5 POAA * POOA is peroctanoic acid The total flow rate in the discharge channel was 425 ml / minute with a recirculation flow rate created by pump 16 of 11.35 liters / minute. The total volume of the discharge channel was 8.51 liters with the overflow discharged to the overflow tank 14 to a discharge reservoir 13. The analysis for metals present in the water leaving the discharge channel of a previous experiment gave an average of 13.4 Iron ppm (Fe), 0.28 ppm copper (Cu), and 0.52 ppm manganese (Mn).

The results of the analysis can be seen in Table 1 1 and in Figure 5. The average residue (col 2) is the measured antimicrobial agent concentration taken several times a day averaged over a total period of 72 hours. The average demand (col 3) is the difference between the dosed concentrations (Table 10, col 2) and the average residual. The pH (col 4) was also averaged over a period of 72 hours, taken once every 24 hours. The accounts of the average discharge channel, col. 5, were calculated from the water samples of the discharge channel taken every 12 hours for a total period of 72 hours, and the units are from CFU (colony formation units) / ml during a normal (total) plate count. The average log reduction against control (col 6) was calculated by taking the logarithm (base 10) of the water accounts of the discharge channel and subtracting them from the water account log of the discharge channel for the control experiment. Example 5A is compared to control 1, since both use peas that have been sterilized. The rest of the examples are compared to control 2. The last column, average pea counts, gives the microbial load (CFU / ml) for the solution to the 10% pea maintained in the development tank 10 of the samples taken every 12 hours. This gives an indication of the load of microbes that has been fed into the discharge channel, in addition to the growth that occurs in the discharge channel.

TABLE 11 Residual Example Demand PH Cts. of Network. Log Cts. Work Prom. Prom. Prom. Channel of Prom. Vs peas ÍPP m) (ppm) download Control Prom. Prom. 5A 14. 9 15.1 7.5 1.7E + 03 2.8 5.0E + 04 Control 1 - - NA 1.0E + 06 3.9E + 04 5B 41 69 8.4 2.2E + 04 2.0 1.2E + 06 5C 19 11 8.2 4.9E + 04 1.7 1.2E + 06 5D 15. 7 14.3 7.53 9.5E + 03 2.4 2.0E + 06 5E 24. 1 15.9 7.4 1.5E + 04 2.2 7.1E + 04 5F 20 10 6.3 9.5E + 03 2.4 2.3E + 04 Control 2 - - NA 2.2E + 06 - 1.4E + 05 5G 0 17.5 NA 1.4E + 04 2.2 1.7E + 05 5H 5 10 7.2 4.0E + 04 1.7 5.0E + 05 WORK EXAMPLE 6 Following the killing and slaughter and cleaning of the poultry, the birds were placed in a cold aqueous stream (chiller) for at least 30 minutes before packing. Samples of chilled water from a poultry processing plant were obtained to compare the test doses of peracetic acid, a combination of peracetic acid and peroctanoic acid, sodium hypochlorite and chlorine dioxide. The results are shown in Table 12. The peracetic acid sample was that prepared from a dilution of the formula described in Work Example 1. The combination of peracetic acid and peroctanoic acid contained 27 parts per million of peracetic acid and about 3 parts per million of peroctanoic acid. Active chlorine was obtained from sodium hypochlorite. The treatment of chilled water using peracetic acid or combinations of peracetic / peroctanoic acid worked much better in the annihilation of bacteria than the treatment of hypochlorite or chorus dioxide.

TABLE 12 Sample Concentration (CFU / ml) Network. Log Not treated (Control) 1.0 X 102 30 ppm POAA < 1 2.0 30 ppm POAA / POOA < 1 2.0 30 ppm (Cl) 1.4 X 101 0.85 20 ppm CIO2 3 1.5 WORK EXAMPLE 7 1. Eight different peracids were prepared by mixing the following amounts of the mother acid, a 35% solution of H2O2, and deionized water, leaving 8 days for the solution to reach equilibrium and then analyzing the perishate and hydrogen peroxide with a titration method. of ceric sulfate / sodium thiosulfate. (Note: All concentrations of active peracid are reported as percentage of peracetic acid (POAA) to give an equivalent basis of comparison and to eliminate confusion with the distribution of peracid functionalities for di- and tri-acids).

TABLE 13 . A solution of 1% tomatoes in water was prepared as previously described by grinding the whole tomatoes in a food processor and adding 1% by weight of ground tomatoes to the water. 3. This solution was allowed to settle at room temperature during 4 days in order to allow the bacteria to grow at levels typically seen in the processing or transport water of plant plants. Measured quantities of the 8 different peracids prepared in the step were added to separate bottles containing 500 ml of 1% of the tomato solution prepared in step 2 to reach dosed levels of each peracid varying from 12 to ppm. Each test was performed in duplicate. In two of the bottles, no peracid was added. These flasks were used as controls without treatment.

The results for the two duplicates of each experiment were averaged and reported in Table 14. ro cn o cn o cn TABLE 14 co co The dosed concentration (col 3) is the concentration of each peracid (w / w) after the addition to the tomato solution. The residual concentration (col 4) is the measured amount of the peracid three minutes after the completion of the dosage. The measurement technique was again based on a titration with ceric sulfate, sodium thiosulfate. The microbial counts were measured after allowing peracid contact with the tomato solutions at 21.1 -23.8 ° C for 1, 24 and 48 hours. Peracids were neutralized after each elapsed period with a thiosulfate / peptone / catalase solution. The resulting solution, after the dilutions in series in water of dilution regulated in its pH with phosphate, it was incubated in agar of extract of trypton-glucose during 48 hours at 35 ° C. The total colony formation units per ml of solution (CFU / ml) were then counted and reported in col. 5, 7 and 9 in the previous table. The Log reductions were then calculated by subtracting the Log accounts from each peracid treated solution (experiments 2-9) during the appropriate period (counting 6, 8 and 10) of the logarithm (base 10) of the untreated microbe counts ( experiment 1). Since each test was performed in duplicate, the reported results are the arithmetic averages for each treatment. The results (Table 14) show that almost all the peracids in this study maintained a high degree of residual activity after contacting a solution of 1% tomato (except Experiment 5, persuccinic, which was dosed at an initial level low). This behavior is similar to that of peracetic acid and again showed the stability of these peracids in the presence of large amounts of organic matter. The results also show (Table 14) that the perpropionic, perbutiric, perglutaric, perglycolic, perláctico and percítrico acids all gave more than 4 log reductions in the microbial counts after a contact time of 1 hour with the 1% solution of tomato. In addition, the level of microbial killing was maintained or increased for 24 hours (and in most cases, 48 hours) for the aforementioned peracids, indicating that the residual antimicrobial activity of the peracids was also maintained during this period. The perpropionic and perbutyric acids functioned the same as peracetic acid, while the perglycolic, perlactic, and percitric acids worked almost well. Persuccinic acid was the only acid tested that did not show high antimicrobial activity under the conditions of this test; however, it was dosed only at 12 ppm. It was expected that higher doses of persuccinic acid would give much better results.

WORK EXAMPLE 8 Microbial Annihilation and Residual POAA Tables 15 and 16 show the need to maintain -2-5 pm of residual POAA in processing waters to effect and maintain substantial control of microbes and slag (> _1.0 log reduction). Below this minimum level of residual POAA, only marginal reductions of microbes occur, while substantial annihilation was found for POAA residuals of 5-10 ppm or higher. A residual above -30 ppm of POAA the economy of the treatment procedure will collapse, so a higher level cut is necessary. Tables 15 and 16 were obtained from commercial channel systems of download and show that having a residual of ~ > 2 ppm of POAA in a plant processing discharge channel, 5 minutes after the addition, produces a substantial reduction of microbes. TABLE 15 Current Discharge Channel Experiments Log Reductions Vegetable POAAa POAA of Microbes15 of testing Residual Dosing 5 min APC Coliform corn 63 ppm 42 ppm1 3.51 3.61 corn 63 ppm 48 ppm1 4.51 3.51 corn 26 ppm 15 ppm2 2.12 NA corn 13 ppm 7 ppm3 2.23 NA potato 33 ppm < 1 ppm4 0.74 NA potato 67 ppm < 1 ppm2 0.42 NA potato 90 PPm 10 ppm3 1.04 NA potato 109 ppm 30 ppm3 3.14 NA A) POAA = peroxyacetic acid. b) Vs a control sample without the addition of POAA. 1) Average of 6 experimental operations. 2) Average of 3 experimental operations. 3) Average of 2 experimental operations. 4) Average of 4 experimental operations. NA = Not available.

TABLE 16 Discharge Channel Experiments by Lot POAA Channel Reductions Log Vegetable Discharge of Residual Microbial POAA Test Dosage Test 5 min. APC Coliform onion cooler 0 ppm 0 ppm 0.0 0.0 onion cooler 2 ppm 2 ppm 1. 1 0.9 onion cooler 30 ppm 1 1 ppm 2.6 2.0 tomato tank 0 ppm 0 ppm 0.0 NA tomato tank 22 ppm 13 ppm 1 .7 NA secondary tomato 0 ppm 0 ppm 0.0 NA secondary tomato 22 ppm 17 ppm 3. 1 MA potato cutter 0 ppm 0 ppm 0.0 NA potato cutter 27 ppm 19 ppm 5.0 NA potato cutter 53 ppm 45 ppm 5.0 NA cyclone potato 0 ppm 0 ppm 0.0 0.0 cyclone potato 53 ppm 2 ppm 3.4 4. 1 potato cyclone 80 ppm 10 ppm 4.3 4. 1 potato cut 0 ppm 0 ppm 0.0 0.0 potato cut 53 ppm 50 ppm 2.8 4. 1 potato dec. ADR 0 ppm 0 ppm 0.0 NA dec. ADR 15 ppm 0 ppm 0. 1 NA potato dec. ADR 30 ppm 27 ppm 4.4 NA potato dec. ADR 60 ppm 2 ppm 1 .6 NA potato sap 0 ppm 0 ppm 0.0 NA coater 2 potato sap 15 ppm 6 ppm 3.4 NA coater 2 potato sap 30 ppm 27 ppm 4.4 NA coater 2 potato post- 0 ppm 0 ppm 0.0 NA potato bleach post-15 ppm < 1 ppm 2.4 NA Potato bleach after 30 ppm 8 ppm 3.4 NA Plea bleach post- 60 ppm 42 ppm 4.6 NA Potato bleach pre-0 ppm 0 ppm 0.0 NA Potato bleach pre 60 ppm 0 ppm 0 0 A bleach 1 pre-treated potato 90 ppm 0 ppm 0.0 NA bleach 1 EXAMPLE 9 ORP vs. POAA Residual Without POAA present, the ORP of the antecedent tends to vary from - 200 to +300 mv, depending on the pH and the temperature of the discharge channel system. Lower water temperatures distort the active region relative to a lower millivolt start value; however, the limits of the ORP controller can be adjusted to set the new low setting point scale. This is only when a POAA residual (> 2 ppm) is obtained and then ORP is raised above a lower indication limit to an effective ORP scale, for microbial kill, of -280-460 mv; that is, these residual requirements of minimum POAA (-2-5 ppm) correlate with -280-460 mv of ORP units; relative to a reference electrode Ag / AgCl in water at room temperature at a pH of -5-8 (Table 17). The unexpected results show the correlation between ORP, residual POAA, and annihilation of microbes. Higher ORP values were obtained with the increase in residual POAA; however, beyond an average of -30 ppm of POAA (-370,460 mv), the excess POAA is merely wasted, since most of the microbial reduction occurs within the first 30 ppm of residual POAA; that is, there is an effective, and economic, ORP scale of -280-460 mv to control the residual POAA and microbial accounts.

TABLE 17 ORP vs. Residual POAA vs. Microbial Reduction Vegetal Canal Temp. POAA POAA ORP Reduc. of Residual Dosing Channel Log Channel Test Download Desc. Í ° C) Discharge Microbes1 secondary tomato 15.5 0 ppm 0 ppm 240-310 O.O2 secondary tomato 15.5 26 ppm 8 ppm 410 mv 2.2 secondary tomato 15.5 30 ppm 7 ppm 420 mv 2.0 secondary tomato 15.5 45 ppm 11 ppm 430 mv 2.8 tomato secondary 15.5 60 ppm 41 ppm 430 mv 2.8 secondary tomato 15.5 90 ppm 61 ppm 490 mv NA secondary tomato 15.5 120 ppm 102 ppm 510 mv NA secondary tomato 15.5 150 ppm 129 ppm 520 mv NA potato heater 62.7 0 ppm 0 ppm -190 mv O .O3 heating potato 62.7 15 ppm 0 ppm 260 mv 0.4 distribution potato 33.8 0 ppm 0 ppm 220 mv 0.0 distributor potato 33.8 60 ppm 8 ppm 370 mv 3.2 distribution potato 33.8 60 ppm 11 ppm 380 mv 3.8 onion cooler 2.7 0 ppm 0 ppm 20 mv O.O4 onion cooler 2.7 15 ppm 3 ppm 310 mv 1.1 onion cooler 2.7 30 ppm 0 14 ppm 360 mv 2.6 onion cooler 2.7 ppm 0 ppm 50 mv NA onion cooler 2.7 15 ppm 3 ppm 300 mv NA onion cooler 2.7 30 ppm 12 ppm 320 mv NA onion cooler 2.7 45 ppm 22 ppm 360 mv NA onion cooler 2.7 60 ppm 38 ppm 45 0 mv - 1) Results obtained from commercial download channel operations, SPC = Normal Plate Count. 2) Average baseline microbe count of 3.2 x 106 counts / ml. 3) Average baseline microbe count of 1.4 x 106 counts / ml. 4) Average base line microbial count of 2.3 x 10 counts / ml. NA = not available.

WORK EXAMPLE 10 Table 18 shows an example where a sample is used in lots of plant discharge channel effluent with the addition of percarboxylic acid, ORP and residual percarboxylic acid initially increased and then fell over time; simulating that it could happen in an automatic percarboxylic acid dosing system. However, in practice, the final ORP, or residual POAA, can not be allowed to return to the old level, but it could reset the operation time controller once the ORP has reached the lower level of controller setting. ORP.

TABLE 18 Declination of ORP v POAA Residual Vegetable POAA Time of ORP of POAA test Dosing Residency Sample Residual by Lot Test Channel of 0 ppm 0 (previous) 240 mv 0 I Desc tomato 1 tomato 22 ppm 0 1 min 480 mv 22 ppm tomato «10 min 460 mv 16 ppm tomato 20 min 450 mv 15 ppm tomato 90 min 440 mv 5 ppm tomato 140 min 260 mv 0 ppm Test Channel 0 ppm 0 (previous) 290 mv 0 ppm II Desc tomato 2 tomato 22 ppm 0 1 min 430 mv 14 ppm tomato _ 5 min 430 mv 13 ppm tomato "10 min 420 mv 12 ppm tomato" 30 min 290 mv 0 ppm Test III Channel 0 ppm 0 (previous) 290 mv 0 ppm Desc tomato 2 tomato 7 ppm 0 1 min 400 mv 6 ppm tomato M 5 min 370 mv 3 ppm tomato "10 min 360 mv 2 ppm tomato 20 min 310 mv 0 ppm Test Channel 0 ppm 0 (previous) 180 mv 0 ppm IV Desc potato 1 potato 30 ppm 0 1 min 290 mv 6 ppm potato 1 min 370 mv 4 ppm potato "3 min 330 mv 1 ppm potato 5 min 220 mv 0 ppm Test Channel 0 ppm 0 (previous) 160 mv 0 ppm V Desc papa 1 Test Channel 0 ppm 0 (previous) 300 mv 0 p m VI Desc onion 1 onion 60 ppm 0 1 min 460 mv 28 ppm onion "5 m in 380 mv 15 ppm onion 10 min 310 mv 5 ppm WORK EXAMPLE 10 Table 19 shows the cumulative actual field test data, in a potato production plant, during a series of periods using the described ORP assortment system. The system was operated continuously during the treatment times shown, with the microbes test of 4 to 8 samples taken per day. The data show the ability to continuously reduce the microbial populations in the discharge channel waters substantially over the control test. The tests also verify that the ORP pump works to lower the actual field conditions, where millions of kilograms of production are being carried out.

TABLE 19 Field Analysis of the ORP System 1) An average during the operation time of the experiment using 4-8 microbial samples daily. 2) APC = Aerobic Plate Count. 3) Control experiment without additives. 4) The actual antecedent (control) plate counts were SPC = 9.9 x 107 and col? Form = 1 .5 x 105 NA = not available.

Claims (2)

1. - An automatic method for controlling the growth of microbes in an aqueous stream used to transport and process packaged food and foods, which comprises treating said aqueous stream with an effective antimicrobial amount of percarboxylic acid, said controlled amount keeping the aqueous stream at a potential of oxidation reduction (ORP) of between about 280 to about 460 mv with respect to a reference electrode Ag / AgCl.

2. The method according to claim 1, wherein the percarboxylic acid in said aqueous stream is maintained at a residual concentration of at least about 2 ppm. 3 - The method according to claim 1, wherein said percarboxylic acid comprises a C2-Cl2 percarboxylic acid. 4. The method according to claim 1, wherein said carboxylic acid comprises peracetic acid. 5 - The method according to claim 1, wherein it further comprises hydrogen peroxide. 6. The method according to claim 5, wherein the hydrogen peroxide is present in an initial concentration ranging from about 5 ppm to 50 ppm, and the percarboxylic acid is present in an initial concentration ranging from about 2 ppm at 100 ppm in the aqueous stream. 7. The method according to claim 1, wherein it comprises the steps of: initially charging a percarboxylic acid to said aqueous stream until an oxidation reduction potential (ORP) of at least 280 mv is reached with respect to a reference electrode Ag / AgCl, and allow the continuous addition of carboxylic acid to the aqueous stream, where the current is controlled by an ORP controller set between approximately 280 and 460 mv with respect to a reference electrode Ag / AGCI .