Method of Reduction and/or Elimination of a Target Agent

Abstract

The present invention relates to a method for reducing and/or eliminating a target agent, particularly from a fluid, preferably from a liquid food flow rate. Preferably, the present method makes it possible to sterilize and/or pasteurize a food in a liquid state, from the modification and control of the value of the case fatality rate Fi provided, by means of the control and regulation of process parameters Ti and Qi.

Claims

1-11. (canceled)

12. A method for reducing and/or eliminating a target agent from a fluid by means of a system comprising: a tube extending between a first end and a second end, forming an internal volume V according to a path, wherein the first end is a fluid inlet and the second end is a fluid outlet, wherein the fluid enters the internal volume V of the tube through the inlet of the tube and runs along the path to the outlet of the tube, wherein said fluid is driven by a pump, heating means fluidically connected to the inlet of the tube, at least one fluid flow rate sensor, configured to measure the flow rate Q of the fluid driven by the pump, at least one temperature sensor, located at the first and/or second end of the tube, configured to measure the temperature T of the fluid driven by the pump, control means, comprising a controller and storage means, the method comprising the following steps: a) providing the storage means of the control means with the following predetermined values: t.sub.validated, holding time of the fluid in the internal volume V of the tube, from its inlet to its outlet, T.sub.validated, temperature of the fluid at the outlet of the tube, F.sub.target, value of the case fatality rate required for the reduction and/or elimination of the target agent, b) introducing and circulating by means of the pump, during the holding time t.sub.validated, the fluid at the temperature T.sub.validated in the interior volume V of the tube, c) recording, by means of the at least one temperature sensor and the at least one flow rate sensor, for each instant t.sub.i, i=0, 1, . . . , m, the real temperature value of the fluid T.sub.i, and the real flow rate value Q.sub.i, of the fluid in the interior volume V of the tube, d) calculating for each instant of time t.sub.i, using the control means and based on the records of the real temperature T.sub.i and the real flow value Q.sub.i of the fluid recorded in step c), the holding time t.sub.mi of the fluid in the interior volume V of the tube, wherein: $t_{mi}=\frac{V}{Q_i}$ e) calculating for each instant t.sub.i, using the control means, the value of the case fatality rate provided, F.sub.i, according to the values recorded and calculated in steps c) and d), and wherein: $F_i={}_{t_0}^{t_{mi}}10^{\left(\frac{T_i-T_{\mathrm{ref}}}{Z}\right)}\mathrm{dt},$ wherein Z is a kinetic property of the reduction and/or elimination of the target agent and T.sub.ref the chosen reference temperature f) verifying, for each instant t.sub.i, using the control means, if the condition F.sub.i<F.sub.target is met, and g) regulating, using the control means, if the condition of step f) is met, the real temperature value of the fluid T.sub.i and/or the real flow rate value Q.sub.i of the fluid in the interior volume V of the tube, which verifies the condition F.sub.iF.sub.target.

13. The method for reducing and/or eliminating a target agent from a fluid according to claim 12, wherein step d) further comprises calculating the holding time factored by a magnification factor FM based on the circulation regime of the fluid.

14. The method for reducing and/or eliminating a target agent from a fluid according to claim 12, wherein step e) further comprises calculating the value of the case fatality rate provided against the reference agent, F.sub.i, according to the values recorded and calculated in steps c) and d), and wherein: $F_i^{}={}_{t_0}^{t_{\mathrm{mi}}}10^{\left(\frac{T_i-T_{\mathrm{ref}}}{Z}\right)}\mathrm{dt}$ wherein Z is a specific value of the reference agent used to define the reference treatment and T.sub.ref is the chosen reference temperature with respect to which the case fatality rate, Fi is to be expressed.

15. The method for reducing and/or eliminating a target agent from a fluid according to claim 12, wherein step g) is carried out by means of a PID algorithm of the controller of the control means.

16. The method for reducing and/or eliminating a target agent from a fluid according to claim 12, comprising a step a.1) of validating the values of step a).

17. The method for reducing and/or eliminating a target agent from a fluid according to claim 16, wherein step a.1) is carried out based on a predetermined validation graph.

18. The method for reducing and/or eliminating a target agent from a fluid according to claim 12, wherein the verification step f) is carried out by means of a predetermined verification graph.

19. The method for reducing and/or eliminating a target agent from a fluid according to claim 12, further comprising the previous step of sterilizing the tube of the system, reducing and/or eliminating a target agent present in said tube by means of a sterilizing fluid, preferably by means of steam or hot water.

20. The method for reducing and/or eliminating a target agent from a fluid according to claim 19, wherein the previous step of sterilizing the tube comprises the steps of: i. providing the storage means of the control means with the following predetermined values: F.sub.validatedsterilization: Value of the target sterilization index, T.sub.start sterilization: temperature value in at least one given sensor from which the cumulative sterilization index is calculated, ii. introducing the sterilizing agent, preferably steam or hot water, into the interior volume V of the tube, and causing it to circulate by means of the pump, until reaching the temperature T.sub.start sterilization, iii. recording, by means of the at least one temperature sensor, the real temperature T.sub.i for an instant of time t.sub.i, iv. storing, in the storage means, the value of the real temperature T.sub.i recorded in iii) for each instant of time t.sub.i v. calculating the cumulative case fatality rate F.sub.0 according to the ratio: $F_0={}_{t_0}^{t_{mi}}10^{\left(\frac{T_i-T_{\mathrm{ref}}}{\mathrm{Zref}}\right)}\mathrm{dt}$ wherein Z.sub.ref is a reduction and/or elimination kinetic property of the reference agent and T.sub.ref the chosen reference temperature with respect to which the case fatality rate F.sub.0 is to be expressed, vi. determining if the value of the cumulative case fatality rate F.sub.0 and the value of the validated sterilization index F.sub.validatedsterilization, meet the ratio F.sub.0>F.sub.validatedsterilization, that is, the cumulative case fatality rate is higher than the value of the target sterilization index established in step i).

21. The method for reducing and/or eliminating a target agent from a fluid according to claim 12, wherein the system further comprises a bypass valve, and wherein step g) of the method further comprises acting on the opening and/or closing of the bypass valve.

22. A computer program configured to implement the method according to claim 12 when it is run on the controller of the control means of the system as defined in claim 12.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0125] To complete the description and for the purpose of aiding to better understand the features of the present disclosure, a set of figures is attached to the present specification as an integral part thereof, in which the following is depicted in an illustrative and non-limiting manner:

[0126] FIG. 1 shows a flowchart of a particular embodiment of a pasteurizing/sterilizing equipment for the application of a method for reducing and/or eliminating a target agent from a fluid, comprising a bypass valve located at the first end of the tube.

[0127] FIG. 2 shows a flowchart of a particular embodiment of the pasteurizing/sterilizing equipment for the application of a method for reducing and/or eliminating a target agent from a fluid, comprising a bypass valve located at the second end of the tube.

[0128] FIG. 3 shows a particular embodiment of a validation graph, with the process pending validation, that is, with the value of the case fatality rate provided by the current treatment lower than the value of the required target case fatality rate.

[0129] FIG. 4 shows the validation graph of FIG. 3 with the process validated, that is, with the value of the case fatality rate provided by the current treatment equal to the value of the required target case fatality rate.

[0130] FIG. 5 shows a particular embodiment of a graphic verification and control process of the system of FIGS. 1 and 2.

[0131] FIG. 6 shows a particular embodiment of a graphic verification and control process of the system of FIGS. 1 and 2.

[0132] FIG. 7 shows a particular embodiment of a graphic verification and control process of the system of FIGS. 1 and 2.

[0133] FIG. 8 shows a particular embodiment of the graph of the sterilization process prior to the step of pasteurizing/sterilizing the food.

[0134] FIG. 9 depicts the steps of this method applied to the liquid food as it passes through the tube, from its inlet to its outlet, in addition to the previous steps of sterilization, validation and provision to the system of the data obtained in the previous step of validation.

DESCRIPTION OF THE INVENTION

[0135] The present disclosure is schematically depicted in FIGS. 1 and 2. Said FIGS. 1 and 2 each shows a flowchart of the system used for the implementation of the steps of the method for reducing and/or eliminating a target agent from a fluid present in a liquid food, which is pumped through a tube by means of a fluid pump.

[0136] In this particular embodiment, the method also considers a reference treatment, said reference treatment being treatment F.sub.0, widely known in the industry as an indicator of the cumulative case fatality of a microorganism.

[0137] Therefore, in a particular embodiment, the fatalities of the present method will be expressed against the reference treatment using its own parameters, T.sub.ref=121.1 C. and Z=10 C. and against the target agent, or target microorganism, designated as Bacillus stearothermophilus using random parameters Dt=1000 seconds and Z=7.3 C.

[0138] Thus, both FIG. 1 and FIG. 2 show a system comprising a tank (1) containing the pumpable food to be treated by means of the corresponding heat treatment for the reduction of the target microorganism Bacillus stearothermophilus. The liquid food flow rate is pumped from the tank (1) by means of the pump (2) to a first heat exchanger (4), where its temperature will be increased up to a predetermined value by means of heat exchange with a heating fluid.

[0139] After the liquid food flow rate leaves the first heat exchanger (4), said flow rate is pumped until it enters the tube (6). A flow meter (3), located between the pump (2) and the heat exchanger (4), makes it possible to measure the flow rate Q of the pumpable food. Additionally, a temperature sensor measures the temperature T of pumpable food flow rate before it enters the tube (6), that is, before the fluid enters the tube (6) through its inlet (6.1).

[0140] Additionally, at the outlet of the tube (6), the pumpable food is introduced into a second heat exchanger (7), by means of which the temperature of said pumpable food is reduced through heat exchange with a cooling fluid. Previously, a temperature sensor measures the temperature T of the pumpable food flow rate after it exits from the tube (6) through its outlet (6.2).

[0141] After the cooling obtained in the second heat exchanger (7), the pumpable food, already treated in the interior of the tube (6), is packaged in packaging equipment.

[0142] Additionally, this system comprises a bypass valve (5), located in the case of FIG. 1 at the first end of the tube (6), while in FIG. 2 it is located at the second end of the tube (6). Both systems also include a non-return valve (8), which prevents diverting the pumpable food after the bypass valve (5) through undesired paths.

[0143] FIGS. 1 and 2 also show control and storage means (9), which make it possible to carry out the different steps of the present method, particularly those calculations necessary for the different steps.

[0144] FIG. 3 shows a validation graph, where the value of the case fatality rate provided by the current treatment is lower than the value of the required target case fatality rate, that is, F.sub.i<F.sub.target. This indicates that the process, and therefore its predetermined values, have not been validated.

[0145] As this figure shows, point B is the minimum required F value or P value against the target agent at the reference temperature T.sub.ref, in order to meet the objective of safety and/or quality of the target agent from the present heat treatment, while point E represents the current pasteurization/sterilization treatment against the target agent and the reference agent, referenced with respect to holding temperature T.sub.m and holding time t.sub.m.

[0146] In order for the validation criterion to be met, that is, for the value of the case fatality rate provided to be equal to the value of the target or required case fatality rate, that is, F.sub.i=F.sub.target, it is necessary for said point B to coincide with point D, which represents the current treatment against the target agent, as depicted in FIG. 4.

[0147] In combination with these points, it is also necessary to take into account point D, which represents the F value or P value of the treatment equivalent to the current treatment at the reference temperature T.sub.ref, as well as point C, which represents the F value or P value provided by the system at the reference temperature T.sub.ref against the reference agent.

[0148] Additionally, point A represents the unitary reference treatment (equal to one minute), that is, the unitary F value or P value.

[0149] Finally, the points of intersection with the vertical axis, that is, with the value of the case fatality rate, represent the following: [0150] P.sub.1: threshold fatality required against the target agent, [0151] P.sub.2: threshold fatality against the reference agent, and [0152] P.sub.3: fatality provided against the target agent.

[0153] These points are also present in FIGS. 4 to 7.

[0154] FIG. 4 shows, for the same validation graph, that point B and point D coincide. In this case, the process, and therefore its predetermined values, have been validated, showing said coincidence.

[0155] FIG. 5 shows a particular embodiment of a graphic verification and control process of the system, where the values of the case fatality rates provided against the target agent (Fi) and against the reference agent (Fi) are represented.

[0156] It can also be observed in this particular embodiment that the value of the case fatality rate provided against the target agent (Fi) exceeds the value of the required target case fatality rate F.sub.target, already obtained in the previous validation process, shown in FIGS. 3 and 4, and where it can also be seen that the value of the case fatality rate provided against the reference agent (Fi) is also higher than the value obtained in the previous validation step F.sub.target.

[0157] Graphically, the points depicted in FIG. 5 are the following: [0158] Point D: represents the F value or P value of the treatment equivalent to the current treatment at the reference temperature T.sub.ref against the target agent, [0159] Point K: represents the current record of the F value or P value of the treatment equivalent to the current treatment at the reference temperature T.sub.ref against the target agent, [0160] Point C: represents the F value or P value provided by the system at the reference temperature T.sub.ref against the reference agent, [0161] Point J: represents the current record of the current F value or current P value of the system at the reference temperature T.sub.ref against the reference agent, [0162] Point E: represents the pasteurization/sterilization treatment validated against the target agent and the reference agent, and [0163] Point L: represents the current pasteurization/sterilization treatment against the target agent and the reference agent.

[0164] Additionally, FIG. 5 shows the following points: [0165] Point A: represents the F value or P value of the unitary reference treatment, [0166] Line I: represents the treatments equivalent to the current treatment against the target agent, [0167] Line G: represents the equivalent treatments against the current treatment against the reference agent, [0168] Line H: represents the threshold line delimiting valid treatments against the target agent, [0169] Line F: represents the line of reference treatments equivalent to the unitary one, [0170] Line N: represents the line of treatments equivalent to the current treatment against the target, [0171] Line M: represents the line of treatments equivalent to the current treatment against the reference agent.

[0172] In the case of FIG. 6, for another particular embodiment of the graphic verification and control process, the values of the case fatality rates provided against the target agent (Fi) and against the reference agent (Fi) are observed, as is the fact that the value of the case fatality rate provided Fi is lower than the value of the required target case fatality rate F.sub.target obtained in the previous validation process. The lines and points represented correspond to those mentioned in FIG. 5.

[0173] However, it can also be seen that the value of the case fatality rate provided against the reference agent in this case is higher than the value obtained in the validation. In this particular embodiment, the safety or quality of the food is not guaranteed and the system would act on the controls to regulate the heating means and/or the flow rate until achieving FiFo.

[0174] Lastly, FIG. 7, relating to a particular embodiment of a graphic verification and control process, represents the values of the case fatality rates provided against the target agent (Fi) and against the reference agent (Fi), while it is also observed that the value of the case fatality rate provided Fi is lower than the value of the required target case fatality rate F.sub.target obtained in the previous validation process.

[0175] Additionally, this FIG. 7 shows that the value of the case fatality rate provided against the reference agent in this case does not exceed the value obtained in the validation either. In this particular embodiment, the safety or quality of the food is not guaranteed and the system would act on the controls to regulate the heating means and/or the flow rate until achieving FiFo. The lines and points represented correspond to those mentioned in FIGS. 5 and 6.

[0176] FIG. 8 shows an example of the graph of the sterilization process prior to the step of pasteurizing/sterilizing the food.

[0177] Two graphs can be seen in this figure, the upper one relating to the evolution of the temperature of the fastest particle of the food over time, where the minimum temperature for which a sterilizing effect of the system is obtained after applying the sterilization step is also shown in broken line.

[0178] Additionally, the lower graph shows the evolution of the cumulative fatality provided by the system, in cumulative pasteurization units provided from the start of the treatment until completing the total holding time. This evolution is shown by the continuous line present in the graph.

[0179] The same graph in turn shows a point that graphically determines the fatality of the pasteurization treatment, or F.sub.0.

[0180] As can be observed in FIG. 9, the flowchart shown indicates the steps of the method applied to a liquid food as it passes through the tube, from its inlet to its outlet.

[0181] In this case, prior to the entry of the liquid food into the tube, step a.0) of sterilizing the tube is carried out, using steam or hot water. Said flow rate of steam or hot water is maintained at a temperature higher than the threshold value T.sub.start sterilization for a total time t.sub.mi, during which time the flow of steam or hot water is recirculating throughout the system, that is, in the interior volume of the tube to reduce its population of microorganisms once the preset or target value F.sub.0 has been reached, reaching the desired level of sterilization in the interior volume of said tube and in the cooling means after the tube, if any.

[0182] Next, the system performs a step a.1) of validating the variables required for the treatment, these being: [0183] t.sub.validated: the holding time of the fluid=28.3 seconds. [0184] T.sub.validated: the temperature of the fluid at the outlet of the tube=133.5 C. [0185] F.sub.target: the value of the required target case fatality rate=1413.66 seconds.

[0186] Subsequently, and once the values of these variables have been validated, step a) is carried out, wherein they are provided to the storage means of the control means, so that the treatment carried out on the liquid food inside the tube is based on these initial parameters, previously validated.

[0187] The system has temperature probes located at the inlet and/or outlet of the tube, which allow the recording of the temperature of the fluid T.sub.i for the instants of time t considered.

[0188] In the present embodiment, the system has a temperature probe at the outlet of the tube.

[0189] In this way, step b) of the method makes it possible, by means of the actuation of the probe at the outlet of the tube, to record in the storage means of the control means, the different values of the temperature of the fluid T.sub.i for the instants of time t considered. In addition, the method makes it possible, by means of the records coming from the flow rate probe, to calculate the holding time t.sub.mi of the fluid in the interior volume V of the tube, wherein:

[00013]$t_{\mathrm{mi}}=\frac{V_M}{Q_i}$

[0190] In the present example, the value of the volume necessary in the previous expression, based on the dimensions of the system, is V.sub.m=0.00785398 m.sup.3.

[0191] Said holding time t.sub.mi includes the calculation of the holding time factored by a magnification factor FM considering the circulation regime of the food, thus establishing a conservative criterion for determining the heat treatment to be applied. In the present particular embodiment, the fastest food particle is considered for each of the records of the flow rate value Q.sub.i for each instant t.sub.i.

[0192] The density and viscosity values used to calculate the FM in this exemplary embodiment are the following:

[00014]$\mathrm{Density}=1.13\mathrm{kg}/l$$\mathrm{Viscosity}=236\mathrm{cP}$

[0193] Flow behaviour index (n)=1

[0194] Reynolds number (Re) obtained: 16.93

[0195] Based on said temperature records of the fluid T.sub.i and of the holding time of the fastest particle t.sub.mi, the control means of the system make it possible, in a step c) of the present method, to calculate the value of the case fatality rate of the target agent provided, F.sub.i, for each of the instants of time t considered.

[0196] In particular, the value of the case fatality rate provided, F.sub.i, is calculated based on the following ratio for the target agent, by the control means:

[00015]$F_i={}_{t_0}^{{\mathrm{tm}}_i}10^{\left(\frac{T_i-T_{\mathrm{ref}}}{Z}\right)}\mathrm{dt}$

[0197] Where T.sub.ref=121.1 C. and Z=7.3 C.

[0198] On the other hand, the value of the case fatality rate provided compared to the reference agent, F.sub.i, is calculated based on the following relationship by the control means:

[00016]$F_i^{}={}_{t_0}^{{\mathrm{tm}}_i}10^{\left(\frac{T_i-T_{\mathrm{ref}}}{\mathrm{Zref}}\right)}\mathrm{dt}$

[0199] Where T.sub.ref=121.1 C. and Z=10 C.

[0200] Once the value of the fatality rate provided, F.sub.i, at each instant of time t is known, the system allows the comparison of said values with the value of the required target case fatality rate, F.sub.target, previously determined in step a.1).

[0201] In this way, step d) of the present method carries out the comparison of values, checking if F.sub.i<F.sub.target by means of the control methods.

[0202] In the event that the previous condition is met, the treatment carried out is not adequate to achieve the target value of reduction of the population of the target microorganism or target agent, so the control means carry out modifications in the configuration of the system to, thus, modify the parameters of the applied treatment, treatment temperature and/or flow rate or holding time and increase its efficacy on liquid food.

[0203] In this way, when step d) of the method is verified, that is, when the condition F.sub.i<F.sub.target is verified, the control means could act on the bypass valve of the system, so that the inlet flow liquid food flow rate in the interior of the tube or at its outlet is diverted and returned to the previous storage tank from where the pump that circulates the fluid food is fed.

[0204] Thus, with these modifications of the parameters of the temperature and flow rate system, there are obtained additional records of the temperature of the fluid T.sub.i and holding time t.sub.mi for the instants of time t considered, and therefore modified values of the value of the case fatality rate provided F.sub.i, until the condition is verified F.sub.iF.sub.target, which indicates that the applied treatment has the required efficacy.

[0205] In this particular embodiment, a series of two records are considered to evaluate the value of the case fatality rate in various situations:

TABLE-US-00001 Number of Fatality supplied log-decimal Flow Fastest particle Fatality required Fatality supplied against the reductions of rate Q.sub.i Temperature residence time against target against target reference agent target agent (l/h) T.sub.i ( C.) (s) agent F.sub.target (s) agent (s) (s) n.sub.target agent 355 137 39.823005468 1413.660307597 6000.897727348 1549.294693642 8.4898723 420 132.2 33.659921288 1413.660307597 1115.991896979 433.623785099 1.5788685