Ultra-high pressure sterilization stability control system for beverages

Abstract

This invention discloses a stability control system for ultra-high pressure sterilization of beverages, belonging to the field of food sterilization technology. The system includes: a pressure detection unit; a temperature detection unit; and a control unit comprising: a lethality rate determination module, used to determine the instantaneous lethality based on a preset microbial lethality kinetic model using real-time acquired pressure and temperature values; a cumulative amount calculation module, used to calculate the real-time cumulative sterilization intensity based on the instantaneous lethality; a deviation determination module, used to compare the real-time cumulative sterilization intensity with the reference cumulative sterilization intensity at the corresponding moment on a preset reference cumulative sterilization intensity curve during ultra-high pressure sterilization to determine the cumulative deviation; and a pressure adjustment module, used to dynamically adjust the target pressure value of the pressurization device based on the cumulative deviation, so that the real-time cumulative sterilization intensity follows the preset reference cumulative sterilization intensity curve. Based on this method, stability control of the ultra-high pressure sterilization process of beverages can be achieved.

Description

Technical Field

[0001] This invention belongs to the field of food sterilization technology, specifically relating to a stability control system for ultra-high pressure sterilization of beverages. Background Technology

[0002] Ultra-high pressure (UHAP) sterilization is a non-thermal processing technology that uses a high-pressure medium at room temperature or lower to kill microorganisms in packaged beverages, offering significant advantages in preserving beverage flavor and nutritional components. During UHAP sterilization, stable control of the sterilization effect is crucial for ensuring product safety and consistent quality.

[0003] Currently, the control of ultra-high pressure sterilization processes for beverages generally relies on preset pressure and time parameters. This involves setting target pressure values ​​and holding times based on experience, with sterilization completed after the holding period. This open-loop control method does not fully consider the dynamic impact of real-time fluctuations in process conditions such as temperature and pressure on the lethality of microorganisms. In actual production, due to differences in initial material temperature, equipment operating status, and environmental conditions, the actual temperature and pressure within the processing chamber often deviate from expected values. This results in significant differences in the actual sterilization effects achieved between different batches under the same process parameters, making it difficult to guarantee product quality consistency.

[0004] Since the aforementioned open-loop control method is difficult to cope with real-time fluctuations in process conditions, the stability control problem of the ultra-high pressure sterilization process of beverages has not been effectively solved. How to achieve stability control during the sterilization process to ensure the consistency and controllability of sterilization effects of different batches of products remains a technical problem to be solved in this field. Summary of the Invention

[0005] One object of the present invention is to solve at least the above-mentioned problems and / or defects, and to provide at least the advantages described below.

[0006] One objective of this invention is to achieve stability control in the ultra-high pressure sterilization process of beverages.

[0007] One object of the present invention is to provide a beverage ultra-high pressure sterilization stability control system. The system is used to control an ultra-high pressure sterilization device for beverages to perform ultra-high pressure sterilization. The ultra-high pressure sterilization device includes an ultra-high pressure processing chamber, a pressurization device communicating with the ultra-high pressure processing chamber, and a pressure relief device communicating with the ultra-high pressure processing chamber. The system includes: The pressure detection unit is used to acquire the pressure value inside the ultra-high pressure processing chamber in real time; The temperature detection unit is used to acquire the temperature value of the beverage inside the ultra-high pressure processing chamber in real time; The control unit is connected to the pressure detection unit, the temperature detection unit, the pressurization device, and the pressure relief device, respectively. The control unit includes: The lethality determination module is used to determine the instantaneous lethality based on the pressure and temperature values ​​acquired in real time and a preset microbial lethality kinetic model. The cumulative amount calculation module is used to calculate the real-time cumulative sterilization intensity based on the instantaneous lethality by integrating over time with a preset sampling period as the time step. The deviation determination module is used to determine the cumulative deviation by taking the moment when the pressurizing device starts pressurizing as the starting point of the timing during the ultra-high pressure sterilization process and comparing the real-time cumulative sterilization intensity with the reference cumulative sterilization intensity at the corresponding moment on the preset reference cumulative sterilization intensity curve. The pressure regulation module is used to dynamically adjust the target pressure value of the pressurization device according to the cumulative deviation, so that the real-time cumulative sterilization intensity follows the preset reference cumulative sterilization intensity curve.

[0008] Preferably, in the beverage ultra-high pressure sterilization stability control system, the control unit further includes: The comparison and control module is used to compare the real-time cumulative sterilization intensity with the preset target sterilization intensity, and to determine when the real-time cumulative sterilization intensity reaches the target sterilization intensity. The pressurization device is controlled to stop pressurizing, and the pressure relief device is controlled to open, so as to release the pressure of the ultra-high pressure treatment chamber to normal pressure and end the sterilization process.

[0009] Preferably, in the beverage ultra-high pressure sterilization stability control system, the preset microbial lethality kinetic model is the Weibull model, and the lethality determination module is used to determine the instantaneous lethality based on the Weibull model according to the pressure value and the temperature value acquired in real time.

[0010] Preferably, in the beverage ultra-high pressure sterilization stability control system, the cumulative amount calculation module is used to multiply the instantaneous lethality corresponding to the sampling period by the time step, using the sampling period as the time step, to obtain the instantaneous lethality increment, and then add the instantaneous lethality increment to the real-time cumulative sterilization intensity obtained at the end of the previous sampling period to obtain the real-time cumulative sterilization intensity at the end of the current sampling period; wherein, the real-time cumulative sterilization intensity at the initial moment is set to zero.

[0011] Preferably, in the beverage ultra-high pressure sterilization stability control system, the cumulative amount calculation module is further used for: During the ultra-high pressure sterilization process, the pressure value sequence collected by the pressure detection unit in N consecutive sampling cycles is obtained, and the time change rate of the pressure value is determined based on the pressure value sequence, where N is an integer greater than 1; When the rate of change of the pressure value over time changes from less than the first rate of change threshold to greater than the first rate of change threshold, the sampling period is adjusted to the first sampling period starting from the next sampling period. When the rate of change of the pressure value over time changes from being greater than the second rate of change threshold to being less than the second rate of change threshold, the sampling period is adjusted to the second sampling period starting from the next sampling period. Wherein, the first rate of change threshold is greater than the second rate of change threshold, and the first sampling period is less than the second sampling period.

[0012] Preferably, in the beverage ultra-high pressure sterilization stability control system, determining the time change rate of pressure values ​​based on the pressure value sequence includes: The difference between the last sampled value and the first sampled value in the pressure value sequence is divided by the total duration of the N consecutive sampling periods, and the resulting quotient is used as the time change rate of the pressure value.

[0013] Preferably, in the beverage ultra-high pressure sterilization stability control system, the cumulative amount calculation module is further used for: The temperature value sequence collected by the temperature detection unit within M consecutive sampling periods is obtained, and the time change rate of the temperature value is determined based on the temperature value sequence, where M is an integer greater than 1; When the time change rate of the pressure value is greater than the first change rate threshold, or the time change rate of the temperature value is greater than the preset temperature change rate threshold, the sampling period is adjusted to the first sampling period starting from the next sampling period.

[0014] Preferably, in the beverage ultra-high pressure sterilization stability control system, the cumulative amount calculation module is further used for: When the time change rate of the pressure value is less than the second change rate threshold, and the time change rate of the temperature value is less than or equal to the temperature change rate threshold, the sampling period is adjusted to the second sampling period starting from the next sampling period.

[0015] Preferably, in the beverage ultra-high pressure sterilization stability control system, the cumulative amount calculation module is used for: The difference between the last sampled value and the first sampled value in the temperature value sequence is divided by the total duration of the M consecutive sampling periods, and the resulting quotient is used as the time change rate of the temperature value.

[0016] The present invention has at least the following beneficial effects: This invention utilizes a lethality determination module to determine the instantaneous lethality based on real-time collected pressure and temperature values ​​using a pre-defined microbial lethality kinetic model. A cumulative amount calculation module performs time integration with a pre-defined sampling period as the time step to obtain the real-time cumulative sterilization intensity, thus converting process parameters into quantitatively significant sterilization effect indicators in real time. Furthermore, a deviation determination module compares the real-time cumulative sterilization intensity with a pre-defined reference cumulative sterilization intensity curve to determine the cumulative deviation. A pressure regulation module then dynamically adjusts the target pressure value of the pressurization device based on the cumulative deviation, forming a closed-loop control system with the cumulative sterilization intensity as the controlled variable. The coordinated operation of these modules ensures that the growth path of the cumulative sterilization intensity actively follows the pre-defined curve during the sterilization process, thereby achieving stable control of the ultra-high pressure sterilization process for beverages.

[0017] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the ultra-high pressure sterilization stability control system for beverages provided by the present invention. Detailed Implementation

[0019] The present invention will now be described in further detail so that those skilled in the art can implement it based on the description.

[0020] like Figure 1As shown, this invention provides a beverage ultra-high pressure sterilization stability control system. The system controls an ultra-high pressure sterilization device for ultra-high pressure sterilization. The ultra-high pressure sterilization device includes an ultra-high pressure processing chamber, a pressurizing device connected to the ultra-high pressure processing chamber, and a pressure relief device connected to the ultra-high pressure processing chamber. The system includes: a pressure detection unit for real-time acquisition of the pressure value within the ultra-high pressure processing chamber; a temperature detection unit for real-time acquisition of the temperature value of the beverage within the ultra-high pressure processing chamber; and a control unit connected to the pressure detection unit, the temperature detection unit, the pressurizing device, and the pressure relief device. The control unit includes: a lethality determination module for determining the lethality rate based on the real-time acquired pressure value. The system uses the pressure and temperature values ​​to determine the instantaneous lethality based on a preset microbial lethality kinetic model. A cumulative calculation module calculates the real-time cumulative sterilization intensity based on the instantaneous lethality by integrating over time using a preset sampling period as the time step. A deviation determination module, during ultra-high pressure sterilization, compares the real-time cumulative sterilization intensity with the reference cumulative sterilization intensity at the corresponding moment on a preset reference cumulative sterilization intensity curve, using the start time of pressurization by the pressurizing device as the timing start point, to determine the cumulative deviation. A pressure adjustment module dynamically adjusts the target pressure value of the pressurizing device based on the cumulative deviation, so that the real-time cumulative sterilization intensity follows the preset reference cumulative sterilization intensity curve.

[0021] During the ultra-high pressure sterilization process of beverages, the processing chamber is filled with a pressure-transmitting medium, and the packaged beverage to be sterilized is placed inside. A pressurization device injects the pressure-transmitting medium into the processing chamber or drives a piston, increasing the pressure inside the chamber to several hundred megapascals. A pressure relief device is used to release the pressure after sterilization. Pressure detection units and temperature detection units collect the pressure values ​​inside the processing chamber and the temperature values ​​of the beverage in real time, respectively, and transmit the collected signals to the control unit.

[0022] The lethality determination module in the control unit receives real-time collected pressure and temperature values ​​and calls a pre-stored microbial lethality kinetic model. This model describes the quantitative relationship between pressure, temperature, and the instantaneous lethality of microorganisms. The lethality determination module inputs the pressure and temperature values ​​at each sampling moment into the model to calculate the corresponding instantaneous lethality. The instantaneous lethality reflects the rate at which microorganisms are killed per unit time under the current pressure and temperature conditions.

[0023] The cumulative dose calculation module integrates the instantaneous lethality over time using a preset sampling period as the time step. Specifically, the module multiplies the instantaneous lethality corresponding to the current sampling period by the time step to obtain the increment of instantaneous lethality within that period. This increment is then successively added to the previously accumulated sterilization intensity to obtain the real-time cumulative sterilization intensity from the start of sterilization to the current moment. This real-time cumulative sterilization intensity quantitatively characterizes the overall sterilization effect applied to the beverage.

[0024] The deviation determination module internally stores a reference cumulative sterilization intensity curve. This curve represents the target trajectory of cumulative sterilization intensity increasing over time, starting from the pressurization initiation point under ideal process conditions. The deviation determination module uses the moment the pressurization device begins pressurization as the starting point for timing. At each sampling moment, it compares the real-time cumulative sterilization intensity output by the cumulative amount calculation module with the corresponding reference value on the reference cumulative sterilization intensity curve at the same moment, calculates the difference between the two, and obtains the cumulative deviation. The sign and magnitude of the cumulative deviation reflect the direction and degree of deviation of the actual sterilization process from the ideal trajectory.

[0025] The pressure regulation module receives the accumulated deviation and dynamically adjusts the target pressure value of the pressurization device according to the magnitude and direction of the deviation. When the real-time cumulative sterilization intensity is lower than the reference value, it indicates that the actual sterilization process is too slow. The pressure regulation module increases the target pressure value, increasing the instantaneous lethality and thus accelerating the growth of the cumulative sterilization intensity, bringing it back to the reference curve. When the real-time cumulative sterilization intensity is higher than the reference value, it indicates that the actual sterilization process is too fast. The pressure regulation module decreases the target pressure value, reducing the instantaneous lethality and slowing down the growth rate of the cumulative sterilization intensity. Through this closed-loop regulation, the real-time cumulative sterilization intensity continuously follows the preset reference cumulative sterilization intensity curve throughout the sterilization process, thereby achieving stable control of the ultra-high pressure sterilization process for beverages.

[0026] It should be noted that the temperature detection unit employs an armored platinum resistance temperature sensor suitable for ultra-high pressure environments. Its temperature probe extends into the chamber through a sealed pressure-feeding hole in the ultra-high pressure processing chamber wall and is immersed in the pressure-transmitting medium. Since beverage packaging is typically a flexible plastic container, the packaging wall becomes extremely thin under ultra-high pressure, resulting in rapid and sufficient heat exchange between the pressure-transmitting medium and the beverage. Experiments have verified that the temperature difference between the pressure-transmitting medium and the center temperature of the beverage inside the packaging does not exceed ±1.5℃ during pressurization and pressure holding. Therefore, using the temperature of the pressure-transmitting medium as a substitute for the beverage temperature measurement eliminates the need to damage the beverage packaging. For applications requiring higher precision, a wireless temperature sensor can be pre-embedded within the beverage packaging. This sensor transmits data outwards via a radio frequency antenna on the inner wall of the pressure vessel. Both of these implementation methods are conventional techniques in this field.

[0027] This invention continuously compares the real-time cumulative sterilization intensity with a reference curve and dynamically adjusts the target pressure value of the booster device based on the cumulative deviation obtained from the comparison. This forms a closed-loop control with the cumulative sterilization intensity as the controlled variable, enabling the cumulative sterilization intensity growth path during the sterilization process to actively follow the preset trajectory. This overcomes the problem of inconsistent sterilization effects caused by fluctuations in process conditions under open-loop control and achieves stable control of the sterilization process.

[0028] In a preferred embodiment, the beverage ultra-high pressure sterilization stability control system further includes a comparison and control module, which compares the real-time cumulative sterilization intensity with a preset target sterilization intensity, and controls the pressurization device to stop pressurizing when the real-time cumulative sterilization intensity reaches the target sterilization intensity, and controls the pressure relief device to open to release the pressure of the ultra-high pressure processing chamber to atmospheric pressure, thereby ending the sterilization process.

[0029] The control unit includes a comparison and control module. This module has a pre-stored target sterilization intensity value, which is predetermined based on product safety requirements and represents the minimum cumulative sterilization amount required to achieve a qualified sterilization effect.

[0030] During the sterilization process, the cumulative sterilization intensity calculation module continuously outputs the real-time cumulative sterilization intensity. The comparison and control module receives this real-time cumulative sterilization intensity and continuously compares it with the preset target sterilization intensity. When the real-time cumulative sterilization intensity has not yet reached the target sterilization intensity, the comparison and control module does not trigger any action, the pressurization device and the depressurization device maintain their current state, and the sterilization process continues.

[0031] When the real-time cumulative sterilization intensity increases to equal or greater than the target sterilization intensity, the comparison and control module determines that the sterilization endpoint has been reached and sends a stop pressurization signal to the pressurization device. The pressurization device then terminates all active pressurization actions. Simultaneously, an opening signal is sent to the pressure relief device, which opens to discharge the high-pressure transmission medium in the ultra-high pressure processing chamber, reducing the pressure inside the chamber to atmospheric pressure. At this point, the sterilization process is complete, and the processing chamber can be safely opened to remove the sterilized beverage product.

[0032] When the comparison and control module determines that the real-time cumulative sterilization intensity has reached the target sterilization intensity, the control unit immediately sends a command to stop pressurization and open the pressure relief mechanism. At this time, the cumulative calculation module stops the integral calculation of the instantaneous lethality, and the real-time cumulative sterilization intensity is locked as the final value. In other words, the pressure relief process is no longer included in the cumulative sterilization intensity. This is because: firstly, it usually takes several seconds from the issuance of the pressure relief command to the full opening of the pressure relief valve and the pressure dropping to normal pressure. During this period, the pressure has dropped rapidly, and the residual lethal effect of microorganisms is far lower than that during the pressure holding stage; secondly, to ensure that the sterilization effect of different batches of products is strictly consistent, the cumulative sterilization intensity at the end of the pressure holding stage is used as the final sterilization indicator, and the additional contribution of the pressure relief process is not deducted as a safety margin, thereby avoiding the introduction of uncontrollable variables due to fluctuations in the pressure relief rate.

[0033] This invention uses the cumulative sterilization intensity calculated in real time as the basis for determining the sterilization endpoint. When the cumulative sterilization intensity reaches the preset target value, the termination action is triggered, so that the sterilization process of each batch ends with the actual sterilization effect achieved, rather than relying on a fixed holding time. This avoids insufficient or excessive sterilization caused by fluctuations in process conditions and achieves accurate determination of the sterilization endpoint.

[0034] During sterilization, the pressure regulation module's tracking control and comparison, along with the control module's endpoint determination, operate in tandem, with a priority relationship between the two: when the real-time cumulative sterilization intensity has not yet reached the target sterilization intensity, the pressure regulation module continuously adjusts the target pressure value based on the cumulative deviation, ensuring the real-time cumulative sterilization intensity follows the reference curve; once the comparison and control module detects that the real-time cumulative sterilization intensity has reached or exceeded the target sterilization intensity, it immediately stops all adjustments by the pressure regulation module and forcibly terminates the sterilization process (stopping pressurization and opening depressurization). This priority setting ensures that the sterilization endpoint is determined by the actual cumulative effect, not by the time axis of the reference curve. If the cumulative sterilization intensity reaches the target value ahead of schedule before the reference curve has ended (e.g., due to the initial material temperature being higher than expected, leading to a faster lethal rate), the pressure regulation module will still attempt to reduce the target pressure value to slow the cumulative rate of increase at the previous moment, but when the cumulative amount reaches the target value, the system directly ends the sterilization process and no longer tracks the reference curve. This coordination logic is pre-configured in the control unit's program.

[0035] In a preferred embodiment, in the beverage ultra-high pressure sterilization stability control system, the preset microbial lethality kinetic model is the Weibull model, and the lethality determination module is used to determine the instantaneous lethality based on the Weibull model according to the pressure value and the temperature value acquired in real time.

[0036] In the lethality determination module of the control unit, the pre-stored microbial lethality kinetic model specifically adopts the Weibull model. The Weibull model is a nonlinear model that describes the lethal process of microorganisms under ultra-high pressure conditions. Its parameters are obtained by experimentally measuring and fitting the lethality curves of target microorganisms in specific beverages under different pressure and temperature combinations, and are pre-written into the storage unit of the lethality determination module.

[0037] During the sterilization process, the pressure and temperature detection units transmit the collected pressure and temperature values ​​to the lethality determination module at each sampling cycle. The lethality determination module uses the real-time pressure and temperature values ​​as input variables, substitutes them into a pre-stored Weibull model, and the model outputs the instantaneous lethality at that sampling moment. This instantaneous lethality is then transmitted to the cumulative calculation module for subsequent integration calculations.

[0038] Because the Weibull model can fit the nonlinear characteristics of the microbial lethality curve under ultra-high pressure conditions well, including the nonlinear effects of pressure on lethality and temperature on lethality, the instantaneous lethality calculated based on this model can accurately reflect the actual microbial lethality rate under the current process conditions.

[0039] Specifically, the model characterizes the survival curves of microorganisms under ultra-high pressure conditions in the following form: in, S ( t () represents the survival rate at time t; t ( P , T The characteristic time is a function of pressure P and temperature T; β ( P , T () is a shape parameter, and is also a function of pressure P and temperature T. Instantaneous lethality. k ( t The value is defined as the negative derivative of the logarithm of survival rate with respect to time. For the numerical implementation in the actual control process, the instantaneous lethality within each sampling period is taken as the arithmetic mean of the instantaneous lethality at the beginning and end of the period, in order to reduce the integral error. t ( P , T )and β ( P , TThe specific function form is obtained through pre-conducting ultra-high pressure lethality experiments on the target beverage and target microorganisms, using nonlinear regression fitting, and is pre-stored as a parameter table in the control unit. During real-time control, the parameter is obtained by looking up the table or interpolating based on the current pressure and temperature values. t and β Then, the instantaneous lethality rate is calculated.

[0040] In a preferred embodiment, in the beverage ultra-high pressure sterilization stability control system, the cumulative amount calculation module is used to multiply the instantaneous lethality corresponding to the sampling period by the time step, using the sampling period as the time step, to obtain the instantaneous lethality increment, and then add the instantaneous lethality increment to the real-time cumulative sterilization intensity obtained at the end of the previous sampling period to obtain the real-time cumulative sterilization intensity at the end of the current sampling period; wherein, the real-time cumulative sterilization intensity at the initial moment is set to zero.

[0041] The cumulative calculation module performs time integration using a discrete accumulation method within the digital controller. This module contains a timer that triggers a calculation process periodically according to a preset sampling period. The specific duration of the sampling period is preset based on the controller's processing capacity and the sterilization process requirements, for example, 0.1 seconds.

[0042] At the beginning of each sampling period, the cumulative amount calculation module obtains the instantaneous lethality corresponding to the current sampling time from the lethality determination module. This instantaneous lethality is multiplied by the duration of the sampling period to obtain the instantaneous lethality increment within the current sampling period. For example, if the current instantaneous lethality is a certain value and the sampling period duration is 0.1 seconds, then multiplying the two yields the newly added sterilization amount within that period.

[0043] The cumulative dose calculation module maintains an internal storage unit to save the real-time cumulative sterilization intensity obtained at the end of the previous sampling period. In the calculation of the current sampling period, the module reads this stored value, adds it to the instantaneous lethal dose increment calculated in the current period, obtains the updated cumulative value, and outputs it as the real-time cumulative sterilization intensity at the end of the current sampling period. At the same time, it is stored in the storage unit for use in the next period.

[0044] At the initial moment of the sterilization process, that is, at the zero moment when the pressurization device has not yet started pressurizing or has just begun pressurizing, the initial value of this storage unit is set to zero, indicating that no sterilization amount has accumulated. Thereafter, as each sampling cycle progresses, the cumulative sterilization intensity increases gradually from zero.

[0045] Specifically, let the sampling period be Δ t , No. i The instantaneous lethality rate within each sampling period is k i Then the firsti Instantaneous lethality increment Δ within each sampling period Q i for: set up Q i For the first i The real-time cumulative sterilization intensity (dimensionless, equivalent time) at the end of each sampling period is calculated using the following recursive formula: The initial conditions are: Q 0=0 indicates that the cumulative sterilization intensity is zero before sterilization begins. In the continuous time domain, the real-time cumulative sterilization intensity can also be expressed as an integral: In the formula, k ( t Let f(x) be a function of instantaneous lethality over time. The discrete recursive formula is a numerical approximation of this integral over the sampling period.

[0046] In a preferred embodiment, in the beverage ultra-high pressure sterilization stability control system, the cumulative quantity calculation module is further configured to: during the ultra-high pressure sterilization process, acquire the pressure value sequence collected by the pressure detection unit within N consecutive sampling periods, and determine the time change rate of the pressure value based on the pressure value sequence, where N is an integer greater than 1; when the time change rate of the pressure value changes from less than a first change rate threshold to greater than the first change rate threshold, adjust the sampling period to the first sampling period starting from the next sampling period; when the time change rate of the pressure value changes from greater than a second change rate threshold to less than the second change rate threshold, adjust the sampling period to the second sampling period starting from the next sampling period; wherein, the first change rate threshold is greater than the second change rate threshold, and the first sampling period is less than the second sampling period.

[0047] The cumulative volume calculation module also performs dynamic adjustment of the sampling period during the sterilization process. This module has two preset sampling period values: a shorter first sampling period and a longer second sampling period. For example, the first sampling period can be set to 0.05 s, and the second sampling period can be set to 0.5 s. At the start of the sterilization process, the cumulative volume calculation module defaults to the first sampling period to handle the rapid pressure changes during the initial pressurization phase.

[0048] The cumulative pressure calculation module continuously receives pressure values ​​collected by the pressure detection unit and maintains a first-in-first-out (FIFO) queue of length N in memory to store pressure values ​​collected within the most recent N consecutive sampling periods. N is an integer greater than 1, for example, N = 5. Whenever a new pressure value enters the queue, the oldest pressure value is removed, and the queue always maintains pressure data from the most recent N sampling periods.

[0049] Based on the pressure value sequence, the cumulative calculation module calculates the rate of change of the pressure value over time. Then, the module compares this rate of change with a preset first rate of change threshold and a second rate of change threshold, where the first rate of change threshold is greater than the second rate of change threshold. For example, the first rate of change threshold can be set to 50 MPa / s, and the second rate of change threshold can be set to 20 MPa / s.

[0050] When the rate of change of the pressure value over time changes from less than the first rate of change threshold to greater than the first rate of change threshold, it indicates that the pressure is rising or falling rapidly, and the sterilization process is in a stage of drastic changes in parameters such as pressurization or depressurization. At this time, the cumulative calculation module adjusts the sampling period to the shorter first sampling period from the next sampling period to capture the rapid changes in instantaneous lethality with higher time resolution, ensuring integration accuracy.

[0051] When the rate of change of the pressure value over time changes from being greater than the second rate of change threshold to being less than the second rate of change threshold, it indicates that the pressure change has leveled off and the sterilization process is in the pressure holding phase. At this time, the cumulative amount calculation module adjusts the sampling period to a longer second sampling period starting from the next sampling period to reduce the sampling and calculation frequency and reduce the computational burden on the controller.

[0052] Because there is a difference between the first and second rate of change thresholds, the sampling period will not be switched when the pressure rate of change fluctuates within the range between the two. This hysteresis range absorbs the rate of change jitter caused by sensor noise or small pressure fluctuations, avoiding frequent switching of the sampling period between the two values ​​and ensuring the continuity and stability of the integration operation.

[0053] To avoid discontinuities in the calculation of the pressure value's time-varying rate of change due to sampling period switching, the cumulative calculation module performs the following operations when switching sampling periods: First, in the last short period before the switch, the current pressure value sequence is updated; then, at the beginning of the first long period after the switch, the original pressure value queue is cleared, and pressure values ​​for N consecutive long periods are re-collected from that moment. The pressure value's time-varying rate of change is calculated only after the queue is full. Before the queue is refilled, the sampling period switching judgment is not performed, and the pressure regulation module continues to use the target pressure value adjustment rate before the switch. The pressure change rate calculation in the first long period after the switch takes effect after N periods. The above mechanism also applies to the calculation of the temperature value's time-varying rate of change. In addition, those skilled in the art can choose a smoother processing method: during the transition phase after the switch, the time window length is linearly and gradually changed (e.g., increasing the original window length by 10% each period) until a new stable window length is reached. Regardless of the specific implementation used, the principle is to avoid spurious change rates due to abrupt changes in the time window.

[0054] This invention monitors the pressure change rate in real time and dynamically switches the sampling period under the control of dual-threshold hysteresis logic, so that the sampling period matches the parameter change rate at different stages of the sterilization process. At the same time, the hysteresis interval suppresses switching jitter, making reasonable use of controller resources while ensuring calculation accuracy.

[0055] In a preferred embodiment, in the beverage ultra-high pressure sterilization stability control system, the cumulative quantity calculation module is used to: divide the difference between the last sampled value and the first sampled value in the pressure value sequence by the total duration of the N consecutive sampling cycles, and use the resulting quotient as the time change rate of the pressure value.

[0056] The cumulative calculation module uses a two-point difference method to calculate the rate of change of pressure values ​​over time. This module extracts two data points from the maintained pressure value sequence: the earliest collected first sample value and the latest collected last sample value. The time point corresponding to the first sample value and the time point corresponding to the last sample value spans N consecutive sampling periods, with a total duration of N multiplied by the duration of the current sampling period.

[0057] The cumulative calculation module calculates the difference between the last sampled value and the first sampled value. This difference reflects the total change in pressure value over a time span of N consecutive sampling periods. The module then divides this difference by the total duration of the N consecutive sampling periods; the quotient is the rate of change of pressure value over time. For example, if the pressure value sequence contains data from 5 sampling periods, with the first sampled value being 100 MPa and the last sampled value being 300 MPa, and the total duration being 0.5 s, then the difference is 200 MPa, and the rate of change is 400 MPa / s.

[0058] The obtained rate of change over time is transmitted to the sampling period switching logic and compared with a first rate of change threshold and a second rate of change threshold to determine whether the sampling period needs to be adjusted.

[0059] In a preferred embodiment, in the beverage ultra-high pressure sterilization stability control system, the cumulative quantity calculation module is further configured to: acquire the temperature value sequence collected by the temperature detection unit within M consecutive sampling periods, and determine the time change rate of the temperature value based on the temperature value sequence, where M is an integer greater than 1; when the time change rate of the pressure value is greater than the first change rate threshold, or the time change rate of the temperature value is greater than the preset temperature change rate threshold, starting from the next sampling period, adjust the sampling period to the first sampling period.

[0060] In addition to monitoring the rate of change of pressure value during the sterilization process, the cumulative amount calculation module also monitors the rate of change of temperature value simultaneously, as a supplementary criterion for switching sampling cycles.

[0061] This module continuously receives temperature values ​​collected by the temperature detection unit and maintains a first-in-first-out (FIFO) queue of length M in memory to store temperature values ​​collected within the most recent M consecutive sampling periods. M is an integer greater than 1, for example, M is 5. Whenever a new temperature value enters the queue, the oldest temperature value is removed, and the queue always maintains the temperature data from the most recent M sampling periods.

[0062] Based on this temperature value sequence, the cumulative calculation module calculates the rate of change of temperature over time. Simultaneously, the module has a preset temperature change rate threshold to determine whether the temperature is in a rapid change phase.

[0063] In each sampling period, the cumulative calculation module compares the time-varying rate of pressure with a first rate-varying rate threshold, and simultaneously compares the time-varying rate of temperature with a temperature rate-varying rate threshold. When the time-varying rate of pressure exceeds the first rate-varying rate threshold, or the time-varying rate of temperature exceeds the temperature rate-varying rate threshold, it indicates that the sterilization process is either in a phase of drastic pressure change or a phase of rapid temperature change. In either case, the instantaneous lethality may fluctuate significantly, requiring an increase in sampling density to accurately capture these changes.

[0064] When any of the above conditions are met, the cumulative calculation module adjusts the sampling period to the shorter first sampling period starting from the next sampling period. For example, in the initial stage of pressure holding, the pressure has basically stabilized, and the pressure change rate is lower than the first change rate threshold. However, due to the adiabatic compression effect, the beverage temperature is still gradually balancing, and the temperature change rate may exceed the temperature change rate threshold. At this time, although the pressure condition does not meet the short-period switching requirement, the temperature condition triggers the switching, and the system will maintain the first sampling period to ensure that the instantaneous lethality changes caused by temperature fluctuations can be fully captured.

[0065] This invention introduces the rate of temperature change as a supplementary criterion, which enables a switch to a shorter sampling period to be triggered even when the pressure has stabilized but the temperature is still changing rapidly, ensuring that the change in lethality is fully sampled and making up for the shortcomings of a single pressure criterion.

[0066] In a preferred embodiment, in the beverage ultra-high pressure sterilization stability control system, the cumulative quantity calculation module is further configured to: when the time change rate of the pressure value is less than the second change rate threshold, and the time change rate of the temperature value is less than or equal to the temperature change rate threshold, adjust the sampling period to the second sampling period starting from the next sampling period.

[0067] After switching to the first sampling period, the cumulative calculation module continuously monitors the time change rate of pressure and temperature values ​​to determine whether the conditions for switching back to the second sampling period are met.

[0068] In each sampling period, the cumulative calculation module compares the time-varying rate of change of the currently calculated pressure value with a second rate-varying rate threshold, and simultaneously compares the time-varying rate of change of the currently calculated temperature value with a temperature rate-varying rate threshold. The module determines that the condition for exiting the short period is met only when the time-varying rate of change of the pressure value is less than the second rate-varying rate threshold and the time-varying rate of change of the temperature value is less than or equal to the temperature rate-varying rate threshold. Both conditions must be met simultaneously; neither can be omitted.

[0069] When both of the above conditions are met simultaneously, it indicates that the pressure changes during the sterilization process have become relatively gradual, and the temperature changes have also become relatively stable or have only slight fluctuations. Under these circumstances, the change in instantaneous lethality is relatively slow, and it is no longer necessary to capture it at a high sampling frequency. Starting from the next sampling period, the cumulative calculation module adjusts the sampling period to a longer second sampling period to reduce the sampling and calculation frequency.

[0070] For example, in the later stages of pressure holding, the pressure has stabilized and the rate of pressure change has dropped below the second rate of change threshold. Simultaneously, the beverage temperature has also stabilized after the initial balancing process, and the rate of temperature change has dropped below the temperature rate of change threshold. At this point, both conditions are met, and the system smoothly switches from the first sampling period to the second sampling period, entering a low-frequency sampling and calculation state to save controller resources. If only the pressure condition is met while the temperature condition is not, meaning the temperature is still changing, the system continues to maintain the first sampling period until the temperature also tends to stabilize.

[0071] For example, the preset temperature change rate threshold is 5 ℃ / s. During the later stages of the pressure holding phase in the sterilization process, the pressure change rate over time has decreased to 10 MPa / s, which is less than the second change rate threshold of 20 MPa / s. Simultaneously, the temperature change rate over time has decreased to 3 ℃ / s, which is less than the temperature change rate threshold of 5 ℃ / s. At this point, both conditions are met, and the cumulative calculation module adjusts the sampling period from the current first sampling period of 0.05 seconds to the second sampling period of 0.5 seconds, starting from the next sampling period. If the pressure change rate meets the condition but the temperature change rate is still higher than 5 ℃ / s, for example, 6 ℃ / s, the system continues to maintain the first sampling period until the temperature change rate also decreases below the threshold.

[0072] This invention clarifies that switching back to a long sampling period must simultaneously meet two conditions: the pressure change rate must be lower than the second change rate threshold and the temperature change rate must be lower than or equal to the temperature change rate threshold. This ensures that the judgment of exiting the short sampling period corresponds to the composite criterion of entering the short sampling period, forming a complete hysteresis closed loop, and ensuring that switching only occurs after both pressure and temperature have stabilized.

[0073] In a preferred embodiment, the cumulative quantity calculation module in the beverage ultra-high pressure sterilization stability control system is used to: divide the difference between the last sampled value and the first sampled value in the temperature value sequence by the total duration of the M consecutive sampling periods, and use the resulting quotient as the time change rate of the temperature value.

[0074] The cumulative calculation module uses the same two-point difference method as the pressure change rate calculation method when calculating the rate of change of temperature. This module extracts two data points from the maintained temperature value sequence: the earliest acquired first sample value and the most recent acquired last sample value. The time point corresponding to the first sample value and the time point corresponding to the last sample value spans M consecutive sampling periods, with a total duration of M multiplied by the duration of the current sampling period.

[0075] The cumulative calculation module calculates the difference between the last sampled value and the first sampled value. This difference reflects the total change in temperature value over a time span of M consecutive sampling periods. The module then divides this difference by the total duration of the M consecutive sampling periods; the quotient is the rate of change of the temperature value over time. For example, if the temperature value sequence contains data from 5 sampling periods, with the first sampled value being 25 ℃ and the last sampled value being 35 ℃, and the total duration being 0.5 s, then the difference is 10 ℃, and the rate of change is 20 ℃ / s.

[0076] The obtained temperature value's rate of change over time is transmitted to the sampling period switching logic and compared with a preset temperature change rate threshold, serving as one of the criteria for determining whether to trigger a switch to the first sampling period and whether to allow exiting the first sampling period.

[0077] When the sampling period is dynamically adjusted according to process conditions, the cumulative calculation module still uses the recursive formula within each sampling period. Q i = Q i−1 + k i ⋅Δ t i Calculate the real-time cumulative sterilization intensity, where Δ t i This represents the actual duration of the current sampling period.

[0078] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. It can be applied to various fields suitable for the present invention. Other modifications can be readily implemented by those skilled in the art. Therefore, the present invention is not limited to the specific details without departing from the general concept defined by the claims and their equivalents.

Claims

1. A beverage ultra-high pressure sterilization stability control system, the system being used to control a beverage ultra-high pressure sterilization equipment to perform ultra-high pressure sterilization, the beverage ultra-high pressure sterilization equipment comprising an ultra-high pressure processing chamber, a pressurization device communicating with the ultra-high pressure processing chamber, and a pressure relief device communicating with the ultra-high pressure processing chamber, characterized in that, The system includes: The pressure detection unit is used to acquire the pressure value inside the ultra-high pressure processing chamber in real time; The temperature detection unit is used to acquire the temperature value of the beverage inside the ultra-high pressure processing chamber in real time; The control unit is connected to the pressure detection unit, the temperature detection unit, the pressurization device, and the pressure relief device, respectively. The control unit includes: The lethality determination module is used to determine the instantaneous lethality based on the pressure and temperature values ​​acquired in real time and a preset microbial lethality kinetic model. The cumulative amount calculation module is used to calculate the real-time cumulative sterilization intensity based on the instantaneous lethality by integrating over time with a preset sampling period as the time step. The deviation determination module is used to determine the cumulative deviation by taking the moment when the pressurizing device starts pressurizing as the starting point of the timing during the ultra-high pressure sterilization process and comparing the real-time cumulative sterilization intensity with the reference cumulative sterilization intensity at the corresponding moment on the preset reference cumulative sterilization intensity curve. The pressure regulation module is used to dynamically adjust the target pressure value of the pressurization device according to the cumulative deviation, so that the real-time cumulative sterilization intensity follows the preset reference cumulative sterilization intensity curve.

2. The beverage ultra-high pressure sterilization stability control system according to claim 1, characterized in that, The control unit further includes: The comparison and control module is used to compare the real-time cumulative sterilization intensity with the preset target sterilization intensity, and when the real-time cumulative sterilization intensity reaches the target sterilization intensity, control the pressurization device to stop pressurizing and control the pressure relief device to open, so as to release the pressure of the ultra-high pressure treatment chamber to normal pressure and end the sterilization process.

3. The beverage ultra-high pressure sterilization stability control system according to claim 1, characterized in that, The preset microbial lethality kinetic model is the Weibull model, and the lethality determination module is used to determine the instantaneous lethality based on the Weibull model according to the pressure value and the temperature value acquired in real time.

4. The beverage ultra-high pressure sterilization stability control system according to claim 1, characterized in that, The cumulative amount calculation module is used to multiply the instantaneous lethality corresponding to the sampling period by the time step, using the sampling period as the time step, to obtain the instantaneous lethality increment, and to add the instantaneous lethality increment to the real-time cumulative sterilization intensity obtained at the end of the previous sampling period to obtain the real-time cumulative sterilization intensity at the end of the current sampling period; wherein, the real-time cumulative sterilization intensity at the initial moment is set to zero.

5. The beverage ultra-high pressure sterilization stability control system according to claim 4, characterized in that, The cumulative amount calculation module is also used for: During the ultra-high pressure sterilization process, the pressure value sequence collected by the pressure detection unit in N consecutive sampling cycles is obtained, and the time change rate of the pressure value is determined based on the pressure value sequence, where N is an integer greater than 1; When the rate of change of the pressure value over time changes from less than the first rate of change threshold to greater than the first rate of change threshold, the sampling period is adjusted to the first sampling period starting from the next sampling period. When the rate of change of the pressure value over time changes from being greater than the second rate of change threshold to being less than the second rate of change threshold, the sampling period is adjusted to the second sampling period starting from the next sampling period. Wherein, the first rate of change threshold is greater than the second rate of change threshold, and the first sampling period is less than the second sampling period.

6. The beverage ultra-high pressure sterilization stability control system according to claim 5, characterized in that, The cumulative amount calculation module is used for: The difference between the last sampled value and the first sampled value in the pressure value sequence is divided by the total duration of the N consecutive sampling periods, and the resulting quotient is used as the time change rate of the pressure value.

7. The beverage ultra-high pressure sterilization stability control system according to claim 5, characterized in that, The cumulative amount calculation module is also used for: The temperature value sequence collected by the temperature detection unit within M consecutive sampling periods is obtained, and the time change rate of the temperature value is determined based on the temperature value sequence, where M is an integer greater than 1; When the time change rate of the pressure value is greater than the first change rate threshold, or the time change rate of the temperature value is greater than the preset temperature change rate threshold, the sampling period is adjusted to the first sampling period starting from the next sampling period.

8. The beverage ultra-high pressure sterilization stability control system according to claim 7, characterized in that, The cumulative amount calculation module is also used for: When the time change rate of the pressure value is less than the second change rate threshold, and the time change rate of the temperature value is less than or equal to the temperature change rate threshold, the sampling period is adjusted to the second sampling period starting from the next sampling period.

9. The beverage ultra-high pressure sterilization stability control system according to claim 7 or 8, characterized in that, The cumulative amount calculation module is used for: The difference between the last sampled value and the first sampled value in the temperature value sequence is divided by the total duration of the M consecutive sampling periods, and the resulting quotient is used as the time change rate of the temperature value.

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