Fresh food preservation control system based on osmotic pressure and low temperature barrier

Abstract

This invention relates to the field of fresh food preservation control technology, and discloses a fresh food preservation control system based on osmotic pressure synergistic low-temperature barrier, comprising: a category parameter locking module for acquiring and fixing the category parameters of the current batch of fresh food; a first-test conversion and evaluation module for collecting ambient temperature and humidity, calculating ambient water activity and effective osmotic pressure difference; a priority path determination module for determining the priority control path based on the inhibition degree gap sign and the upper limit of the chilling injury temperature window; a main variable correction module for adjusting temperature and humidity according to the priority path and verifying inhibition degree and osmotic pressure difference; a secondary variable fine-tuning module for fine-tuning secondary variables according to category parameters and verifying inhibition degree and osmotic pressure difference; a patrol limit module for verifying osmotic pressure difference and adjusting temperature and humidity; and a disturbance switching verification module for returning to the first-test conversion and evaluation module during disturbances and performing batch parameter verification. This invention achieves precise preservation control of fresh food during low-temperature storage, extending shelf life and maintaining stable quality.

Description

Technical Field

[0001] This invention belongs to the field of fresh food preservation control technology, specifically relating to a fresh food preservation control system based on osmotic pressure synergistic low temperature barrier. Background Technology

[0002] Low-temperature storage is a common method for extending the shelf life of fresh food. However, low temperatures significantly affect intracellular water potential, easily leading to changes in cell membrane permeability and causing chilling injury. To avoid chilling injury and cell rupture, fresh food storage requires strict control of temperature and humidity to ensure the osmotic pressure difference between the inside and outside of cells remains within a safe range. Existing fresh food preservation methods primarily slow down cell metabolism by controlling low temperature and humidity. However, these methods often fail to simultaneously balance temperature and water potential, resulting in chilling injury, cell dehydration, or excessive water absorption during storage, thus affecting quality and shelf life. In particular, traditional technologies lack effective control mechanisms for chilling injury in low-temperature storage environments, making fresh food prone to cell membrane rupture, textural changes, and nutrient loss during refrigeration. Furthermore, existing technologies offer relatively simple responses to environmental disturbances, typically involving only coarse adjustments to temperature and humidity, making it difficult to achieve precise dynamic responses and stable preservation effects. Summary of the Invention

[0003] This invention provides a fresh food preservation control system based on osmotic pressure synergistic low temperature barrier, which solves the technical problems of insufficient control of chilling injury to fresh food and cell water potential imbalance caused by inaccurate temperature and humidity regulation in related technologies.

[0004] This invention provides a fresh food preservation control system based on an osmotic pressure-synergistic low-temperature barrier, comprising:

[0005] The category parameter locking module is used to acquire and fix the category parameter set of the current batch of fresh food. The category parameter set includes: reference temperature, lower and upper limits of the chilling injury temperature window, upper limit of osmotic pressure difference, lower limit of osmotic pressure difference, water activity of fresh food tissue cells, and target inhibition degree.

[0006] The initial measurement conversion and evaluation module is used to collect ambient temperature and relative humidity, convert them to ambient water activity, and determine the equivalent inhibition degree, inhibition gap, and effective osmotic pressure difference based on the category parameter set.

[0007] The priority path determination module is used to determine the priority control path based on the sign of the inhibition gap, the ambient temperature, and the upper limit temperature of the cold injury temperature window, and to determine the main and secondary variables.

[0008] The main variable correction module is used to adjust the ambient temperature and ambient water activity according to the priority control path, and to verify the equivalent inhibition degree and effective osmotic pressure difference with the upper limit of osmotic pressure difference as a constraint.

[0009] The secondary variable fine-tuning module is used to fill the inhibition gap within the range specified by the category parameter set using secondary variables, and to verify the equivalent inhibition and effective osmotic pressure difference after fine-tuning.

[0010] The inspection and limiting module is used to review the effective osmotic pressure difference according to the inspection cycle, and adjust the environmental water activity and ambient temperature based on the relationship between the effective osmotic pressure difference and the lower and upper limits of the osmotic pressure difference.

[0011] The disturbance switching verification module is used to return to the initial test conversion evaluation module when environmental disturbances occur, switch the priority path when crossing the upper and lower limits of the cold damage temperature window, and perform static parameter verification on the category parameter set at the end of the batch.

[0012] Furthermore, by calculating the difference between the reference temperature and the ambient temperature, the temperature difference is obtained; by calculating the negative logarithm of the ambient water activity, the water activity term is obtained; and by weighting and summing the temperature difference and the water activity term based on the temperature term constant and the water activity constant, the equivalent inhibition degree is obtained.

[0013] Furthermore, the inhibition gap is obtained based on the difference between the target inhibition degree and the equivalent inhibition degree in the category parameter set;

[0014] The natural logarithm of the ambient water activity and the water activity of fresh food tissue cells is taken respectively, and the difference between the two is calculated. The product of the ambient temperature and the gas constant is divided by the molar volume of water, and the negative number is taken and multiplied with the difference to obtain the effective osmotic pressure difference.

[0015] Furthermore, the process of determining the priority control path and the main and secondary variables includes:

[0016] Step 11: Determine the sign of the inhibition gap. When the inhibition gap is greater than zero and the duration exceeds the preset time threshold, proceed to the path determination process.

[0017] Step 12: When the ambient temperature is higher than the upper limit temperature of the chilling injury window, it is determined as the temperature-priority path; when the ambient temperature is less than or equal to the upper limit temperature of the chilling injury window, it is determined as the infiltration-priority path.

[0018] Step 13: In the temperature-priority path, ambient temperature is the primary variable and ambient water activity is the secondary variable; in the permeability-priority path, ambient water activity is the primary variable and ambient temperature is the secondary variable, and priority path identifiers are generated.

[0019] Furthermore, the ambient temperature and ambient water activity were adjusted, and the equivalent inhibition degree and effective osmotic pressure difference were verified, including:

[0020] Step 21: Determine the main variables and adjustment direction based on the priority path identifier. Under the condition that the secondary variables remain unchanged, adjust the main variables in reverse according to the difference between the target inhibition degree and the current equivalent inhibition degree. When the priority path identifier is a temperature priority path, reduce the ambient temperature; when the priority path identifier is a permeability priority path, reduce the ambient water activity. Calculate the equivalent inhibition degree increment caused by the change of the main variables. When the increment is equal to the inhibition degree gap, determine the candidate setting value of the main variables.

[0021] Step 22: Input the equivalent inhibition degree and effective osmotic pressure difference with the candidate setting value of the main variable. When the verification result is greater than the upper limit of the osmotic pressure difference, the main variable is backed down by a preset step size. After each back, the equivalent inhibition degree and effective osmotic pressure difference are recalculated until the effective osmotic pressure difference is less than or equal to the upper limit of the osmotic pressure difference.

[0022] Step 23: When the effective osmotic pressure difference is less than or equal to the upper limit of the osmotic pressure difference and the equivalent inhibition degree reaches the target inhibition degree, the current main variable value is fixed as the main variable setting value, and the corresponding equivalent inhibition degree and effective osmotic pressure difference are output.

[0023] Furthermore, to fill the inhibition gap, the equivalent inhibition and effective osmotic pressure difference are rechecked, including:

[0024] Step 31: Calculate the difference between the current equivalent inhibition level and the target inhibition level to obtain the residual inhibition gap. Determine the type of secondary variable based on the priority path identifier. When the priority path identifier is a temperature priority path, the secondary variable is the ambient water activity. When the priority path identifier is a permeation priority path, the secondary variable is the ambient temperature. Set the step size of the secondary variable within the range specified by the category parameter set. The step size of the secondary variable is less than the preset ratio of the step size of the main variable.

[0025] Step 32: Determine the direction of secondary variable adjustment based on the sign of the residual inhibition gap. After each adjustment, recalculate the equivalent inhibition and effective osmotic pressure difference. When the calculated effective osmotic pressure difference is greater than the upper limit of osmotic pressure difference, roll back the previous step of secondary variable adjustment and re-verify until the effective osmotic pressure difference is less than or equal to the upper limit of osmotic pressure difference.

[0026] Step 33: When the difference between the equivalent inhibition degree and the target inhibition degree is less than the preset tolerance threshold and the effective osmotic pressure difference does not exceed the upper limit of the osmotic pressure difference, the current secondary variable value is fixed as the secondary variable setting value.

[0027] Furthermore, during the process of main variable correction and secondary variable fine-tuning, when the direction of change of the residual inhibition gap of the equivalent inhibition degree after the main variable adjustment is inconsistent with that of the effective osmotic pressure difference deviation, the arctangent of the ratio of the effective osmotic pressure difference deviation to the residual inhibition gap is calculated to obtain the deviation phase, and the cosine value is obtained to obtain the deviation compensation weight coefficient. The correction magnitude of the secondary variable is adjusted proportionally according to the deviation compensation weight coefficient. Among them, the effective osmotic pressure difference deviation is the difference between the effective osmotic pressure difference and the midpoint of the upper and lower limit intervals of the osmotic pressure difference.

[0028] Furthermore, verify the effective osmotic pressure difference and adjust the ambient water activity and ambient temperature, including:

[0029] Step 41: Obtain the environmental water activity and effective osmotic pressure difference in each inspection cycle. If the change rate of effective osmotic pressure difference between two consecutive inspections is greater than the preset change rate threshold, shorten the inspection cycle; otherwise, extend the inspection cycle. Determine the current environmental status based on the relationship between effective osmotic pressure difference and the upper and lower limits of osmotic pressure difference.

[0030] Step 42: When the effective osmotic pressure difference is less than the lower limit of the osmotic pressure difference, increase the ambient water activity or raise the ambient temperature; otherwise, decrease the water activity or lower the ambient temperature. After adjustment, recalculate the effective osmotic pressure difference until the effective osmotic pressure difference is between the upper and lower limits of the osmotic pressure difference.

[0031] Step 43: After the adjustment is completed, calculate the rate of change of effective osmotic pressure difference and the standard deviation of equivalent inhibition within two consecutive inspection cycles. When the rate of change is less than the preset steady-state threshold and the standard deviation is less than the preset standard deviation threshold, the system is determined to be in steady state, and the current environmental water activity and environmental temperature are fixed.

[0032] Furthermore, the disturbance switching verification module includes:

[0033] Step 51: When the temperature change rate exceeds the preset disturbance threshold, a disturbance flag is generated, and the disturbance level and backtracking range are determined according to the magnitude of the exceedance of the preset disturbance threshold. Among them, the equivalent inhibition degree is recalculated for mild disturbances, and the effective osmotic pressure difference and the initial set value of the main variables are recalculated simultaneously for moderate and severe disturbances.

[0034] Step 52: After backtracking, determine whether the ambient temperature crosses the upper or lower limit of the cold damage temperature window. If it crosses the lower limit, switch to the penetration priority path; if it crosses the upper limit, switch to the temperature priority path. Set a lockout period. If the temperature does not cross the limit again within the lockout period, maintain the current priority path; otherwise, delay the path switching.

[0035] Step 53: At the end of the batch, extract the reference temperature, target inhibition degree and upper and lower limits of osmotic pressure difference, calculate the deviation between the average effective osmotic pressure difference of the batch and the target value, remove sampling points with excessive variance, and adjust the reference temperature and target inhibition degree according to the target value deviation. The target value deviation is the difference between the average effective osmotic pressure difference and the median of the upper and lower limits of osmotic pressure difference.

[0036] Furthermore, during the disturbance detection and backtracking process, the temperature change rate and acceleration are calculated based on the ambient temperature, and the disturbance prediction value is obtained by weighted summation. When the disturbance prediction value is higher than the preset disturbance precursor threshold, a buffering phase is entered to reduce the adjustment rate of ambient temperature and ambient water activity. A delayed response time window is set according to the disturbance level, and the backtracking recalculation of equivalent inhibition degree and effective osmotic pressure difference is performed step by step within this delayed response time window. When the backtracking recalculation result meets the upper and lower limits of osmotic pressure difference, the buffering phase is terminated and the normal control process is restored.

[0037] The beneficial effects of this invention are as follows: By monitoring ambient temperature and water activity in real time and dynamically adjusting according to osmotic pressure difference and inhibition gap, this invention avoids cell damage caused by excessive dehydration or water absorption during low-temperature storage; through precise temperature and humidity control, it ensures that the osmotic pressure difference inside and outside the cells of fresh food is always maintained within a safe range, thus extending the shelf life of fresh food; by automatically adjusting the main and secondary variables, the system can automatically switch control paths according to changes in the storage environment, achieving precise temperature and humidity coordinated control. Overall, this invention can improve the quality stability of fresh food during storage and minimize the negative impact of environmental fluctuations on the quality of fresh food. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the fresh food preservation control system based on osmotic pressure synergistic low temperature barrier of the present invention. Detailed Implementation

[0039] The subject matter described herein will now be discussed with reference to exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and implement the subject matter described herein, and changes may be made to the function and arrangement of the elements discussed without departing from the scope of this specification. Various processes or components may be omitted, substituted, or added as needed in the examples. Furthermore, features described in some examples may be combined in other examples.

[0040] like Figure 1 As shown, the fresh food preservation control system based on the osmotic pressure synergistic low temperature barrier includes:

[0041] Category parameter locking module 1 is used to acquire and fix the category parameter set of the current batch of fresh food. The category parameter set includes: reference temperature, lower and upper limit temperatures of chilling injury temperature window, upper limit of osmotic pressure difference, lower limit of osmotic pressure difference, water activity of fresh food tissue cells, and target inhibition degree.

[0042] The first test conversion and evaluation module 2 is used to collect ambient temperature and relative humidity, convert them to ambient water activity, and determine the equivalent inhibition degree, inhibition gap, and effective osmotic pressure difference based on the category parameter set;

[0043] The priority path determination module 3 is used to determine the priority control path based on the sign of the inhibition gap, the ambient temperature and the upper limit temperature of the cold injury temperature window, and to determine the main variables and secondary variables.

[0044] The main variable correction module 4 is used to adjust the ambient temperature and ambient water activity according to the priority control path, and to verify the equivalent inhibition degree and effective osmotic pressure difference with the upper limit of osmotic pressure difference as a constraint.

[0045] Sub-variable fine-tuning module 5 is used to fill the inhibition gap within the range specified by the category parameter set using sub-variables, and to verify the equivalent inhibition and effective osmotic pressure difference after fine-tuning;

[0046] The inspection limit module 6 is used to review the effective osmotic pressure difference according to the inspection cycle, and adjust the environmental water activity and environmental temperature based on the relationship between the effective osmotic pressure difference and the lower limit and upper limit of the osmotic pressure difference.

[0047] The disturbance switching verification module 7 is used to return to the first test conversion evaluation module when environmental disturbance occurs, switch the priority path when crossing the upper and lower limits of the cold damage temperature window, and perform static parameter verification on the category parameter set at the end of the batch.

[0048] In one embodiment of the present invention, the system receives batch information through an input interface, including the type of fresh food, post-harvest maturity, and expected storage period. It then retrieves the corresponding standard parameter template from the database and performs a parameter locking operation during the initialization phase. The lower and upper limits of the chilling injury temperature window are used to define the critical temperature range within which the fresh food of this type exhibits changes in cell membrane permeability and chilling injury symptoms under low-temperature conditions. The lower limit corresponds to the initial onset of chilling injury, and the upper limit corresponds to the point where chilling injury is completely relieved. The upper and lower limits of the osmotic pressure difference are safe osmotic pressure difference ranges determined based on the difference in water potential inside and outside the fresh food cells. The water activity of fresh food tissue cells refers to the ratio of available water to total water within the cells. The target inhibition level describes the expected level of metabolic rate inhibition within the control period.

[0049] In one embodiment of the present invention, the environmental water activity is calculated based on the relative humidity. Specifically, the relative humidity is divided by 100 to obtain the environmental water activity, which represents the ratio of the partial pressure of water vapor in the air that can be used to exchange water with fresh food tissues to the saturated water vapor pressure. The temperature difference is obtained by calculating the difference between the reference temperature and the ambient temperature. This temperature difference reflects the degree of deviation of the current storage temperature from the ideal temperature conditions. The negative logarithm of the environmental water activity is calculated to obtain the water activity term. This water activity term can quantify the influence of environmental humidity on the water potential balance of fresh food cells. The equivalent inhibition degree is obtained by weighted summing of the temperature difference and the water activity term based on the temperature term constant and the water activity constant. The temperature term constant represents the sensitivity coefficient of temperature change to metabolic rate inhibition, and the water activity constant represents the influence weight of humidity change on cell osmotic potential regulation, which is set by the system.

[0050] This embodiment not only converts temperature and humidity factors into a unified equivalent inhibition degree, but also achieves a balance regulation of the osmotic pressure difference inside and outside the cells of fresh food through dynamic feedback, thereby preventing chilling injury and tissue dehydration caused by low temperature stress or sudden changes in water potential, effectively extending the storage period of fresh food and maintaining its quality stability.

[0051] In one embodiment of the present invention, the inhibition gap is obtained based on the difference between the target inhibition degree and the equivalent inhibition degree in the category parameter set; wherein, the inhibition gap represents the degree of deviation between the current inhibition state of the system and the target inhibition state, and quantifies the stability of fresh food cells in a low-temperature environment from the perspective of physiological metabolism.

[0052] The natural logarithm of both the ambient water activity and the fresh tissue cell water activity is taken, and the difference between the two is calculated. The product of the ambient temperature and the gas constant is divided by the molar volume of water, and the negative of this product is multiplied by the difference to obtain the effective osmotic pressure difference. The formula for calculating the effective osmotic pressure difference is as follows: , R represents the effective osmotic pressure difference, and R represents the gas constant. Indicates ambient temperature. Represents the molar volume of water. Indicates environmental water activity. The effective osmotic pressure difference (OSPD) represents the actual osmotic potential difference between the inside and outside of fresh food tissue cells. The larger the value, the stronger the water potential difference between the environment and the cells, and the faster the water migration rate. It quantifies the stability of fresh food cells in low-temperature environments from the perspective of physical osmosis.

[0053] This embodiment establishes a coupling relationship between temperature change and osmotic pressure difference through the above calculation process. This allows metabolic inhibition under low temperature conditions to not only depend on the cooling effect, but also to construct a preservation control mechanism based on the synergistic regulation of the osmotic pressure barrier and the temperature barrier. This mechanism can effectively prevent water potential mutation and membrane structure rupture in cells within the critical range of chilling injury, delay the cell decay process, and ultimately achieve long-term preservation and quality maintenance of fresh food under low temperature storage conditions.

[0054] In one embodiment of the present invention, the process of determining the priority control path, and the main and secondary variables, includes:

[0055] Step 11: Determine the sign of the inhibition gap. When the inhibition gap is greater than zero and the duration exceeds the preset time threshold, the system determines that the current metabolic inhibition is insufficient and enters the path determination process. When the inhibition gap is less than or equal to zero, it means that the system's inhibition level has met or exceeded the target requirements, and the current environmental state is maintained.

[0056] Step 12: When the ambient temperature is higher than the upper limit of the chilling injury temperature window, the system determines that it is currently in the non-chilling injury range. At this time, the main control method is to reduce the temperature, which is determined to be the temperature priority path. When the ambient temperature is less than or equal to the upper limit of the chilling injury temperature window, the system determines that it is in the chilling injury sensitive range. At this time, the system controls the cell osmotic balance by adjusting the ambient humidity and changing the ambient water activity, which is determined to be the osmotic priority path.

[0057] Step 13: In the temperature-priority path, ambient temperature is the primary variable and ambient water activity is the secondary variable. That is, temperature regulation is the main factor. By changing the temperature, the equivalent inhibition degree is quickly corrected. At the same time, the osmotic balance is stabilized by finely adjusting the water activity. In the osmotic-priority path, ambient water activity is the primary variable and ambient temperature is the secondary variable. That is, the core is to control air humidity and water activity. The balance of water potential inside and outside the cell is achieved by regulating the osmotic pressure gradient. At the same time, the safety of the low temperature barrier is maintained by slight temperature correction. And a priority path identifier is generated.

[0058] In this embodiment, through the dynamic determination of the priority control path and the division of primary and secondary variables, the system can adjust the control focus in real time according to the metabolic state of fresh food cells and the level of chilling injury risk in a low-temperature preservation environment, so as to achieve the synergistic effect of osmotic pressure barrier and low temperature barrier. This method can effectively reduce the risk of low temperature stress while maintaining the stability of osmotic pressure of fresh food tissue cells, and achieve the dynamic adaptive preservation control effect based on osmotic pressure synergistic low temperature barrier.

[0059] In one embodiment of the present invention, adjusting the ambient temperature and ambient water activity, and verifying the equivalent inhibition degree and effective osmotic pressure difference, includes:

[0060] Step 21: Determine the main variables and adjustment direction based on the priority path identifier. Under the condition that the secondary variables remain unchanged, adjust the main variables in reverse according to the difference between the target inhibition degree and the current equivalent inhibition degree. When the priority path identifier is a temperature priority path, the system increases the equivalent inhibition degree by reducing the ambient temperature; when the priority path identifier is a permeation priority path, the system enhances the permeation inhibition effect by reducing the ambient water activity. Calculate the equivalent inhibition degree increment caused by the change of the main variables. When the increment is equal to the inhibition degree gap, determine the candidate setpoint of the main variables.

[0061] Step 22: Input the candidate set values ​​of the main variables to verify the equivalent inhibition degree and effective osmotic pressure difference. When the verification result is greater than the upper limit of the osmotic pressure difference, the main variables are successively backed up by a preset step size, and the equivalent inhibition degree and effective osmotic pressure difference are recalculated after each back-up until the effective osmotic pressure difference is less than or equal to the upper limit of the osmotic pressure difference. This cyclic process ensures that the adjustment of the main variables will not disrupt the cellular osmotic balance and avoids excessive inhibition that could cause cell dehydration or membrane stress imbalance.

[0062] Step 23: When the effective osmotic pressure difference is less than or equal to the upper limit of the osmotic pressure difference and the equivalent inhibition degree reaches the target inhibition degree, the current main variable value is fixed as the main variable set value, and the corresponding equivalent inhibition degree and effective osmotic pressure difference are output. This fixing process keeps the main variable state stable within a short period, avoiding frequent fluctuations that could affect the stability of the osmotic pressure gradient inside the fresh food.

[0063] This embodiment uses the equivalent inhibition degree as the metabolic balance target and the effective osmotic pressure difference as the physical constraint boundary. By gradually approximating, backtracking and dynamically verifying the main variables within the low temperature range, a synergistic stability mechanism for temperature and humidity regulation is established. This mechanism can continuously maintain the balance of intracellular and extracellular water potential while preventing mutations in cell membrane permeability, thus achieving high-precision fresh food preservation control.

[0064] In one embodiment of the present invention, filling the inhibition gap and verifying the equivalent inhibition and effective osmotic pressure difference includes:

[0065] Step 31: Calculate the difference between the current equivalent inhibition level and the target inhibition level to obtain the residual inhibition gap. The residual inhibition gap refers to the remaining deviation that has not yet reached the target inhibition level after the main variable adjustment. It reflects the insufficient micro-metabolic inhibition that still exists in the system after one adjustment. Determine the type of secondary variable according to the priority path identifier. When the priority path identifier is temperature priority path, the secondary variable is ambient water activity. When the priority path identifier is osmosis priority path, the secondary variable is ambient temperature. Set the step size of the secondary variable within the preset proportion of the category parameter set. The step size of the secondary variable is less than the preset proportion of the step size of the main variable to avoid osmotic pressure overshoot or system oscillation caused by the superposition of the two variables.

[0066] Step 32: Determine the adjustment direction of the secondary variable based on the sign of the residual inhibition gap. When the residual gap is positive, it indicates insufficient inhibition, and the system adjusts the secondary variable in the direction of strengthening inhibition. When the residual gap is negative, it indicates excessive inhibition, and the system fine-tunes the secondary variable in the direction of weakening inhibition. After each adjustment, recalculate the equivalent inhibition and effective osmotic pressure difference. When the calculated effective osmotic pressure difference is greater than the upper limit of osmotic pressure difference, revert to the previous step of secondary variable adjustment and re-verify until the effective osmotic pressure difference is less than or equal to the upper limit of osmotic pressure difference. This cycle ensures that the fine-tuning process is always carried out within the safe osmotic pressure constraint range to prevent cell dehydration or structural damage due to excessive water potential gradient.

[0067] Step 33: When the difference between the equivalent inhibition degree and the target inhibition degree is less than the preset tolerance threshold and the effective osmotic pressure difference does not exceed the upper limit of the osmotic pressure difference, the current secondary variable value is fixed as the secondary variable setpoint. The preset tolerance threshold is used to define the acceptable error range of the equivalent inhibition degree to ensure a balance between control precision and response stability. The fixed secondary variable setpoint and the primary variable setpoint together constitute the new environmental control baseline of the system, providing a basis for the next control cycle.

[0068] Through the aforementioned secondary variable fine-tuning and verification mechanism, this embodiment enables the system to further refine the adjustment after the main variable is corrected, achieving synchronous convergence of the equivalent inhibition degree and the effective osmotic pressure difference, realizing the fine synergy between the osmotic pressure barrier and the low temperature barrier, and extending the quality maintenance period of fresh food during the refrigeration process.

[0069] In one embodiment of the present invention, during the process of main variable correction and secondary variable fine-tuning, when the direction of change of the residual inhibition gap of the equivalent inhibition degree after the main variable adjustment is inconsistent with that of the effective osmotic pressure difference deviation, the arctangent of the ratio of the effective osmotic pressure difference deviation to the residual inhibition gap is calculated to obtain the deviation phase, and the cosine value is obtained to obtain the deviation compensation weight coefficient. The correction magnitude of the secondary variable is proportionally adjusted according to the deviation compensation weight coefficient to make up for the residual inhibition gap and ensure that the effective osmotic pressure difference is always maintained within the set range. This process effectively avoids system instability caused by excessive or insufficient adjustment of the main and secondary variables, and ensures that the osmotic pressure balance and metabolic inhibition of fresh food are carried out simultaneously under low temperature storage conditions. The effective osmotic pressure difference deviation is the difference between the effective osmotic pressure difference and the median of the upper and lower limit intervals of the osmotic pressure difference. The median of the upper and lower limit intervals of the osmotic pressure difference represents the ideal osmotic pressure difference under normal storage temperature and humidity.

[0070] In one embodiment of the present invention, verifying the effective osmotic pressure difference and adjusting the environmental water activity and environmental temperature includes:

[0071] Step 41: During each inspection cycle, the system acquires the ambient water activity and effective osmotic pressure difference. When the rate of change of effective osmotic pressure difference between two consecutive inspections exceeds a preset threshold, the system determines that the current environment is in a relatively unstable state and shortens the inspection cycle; otherwise, the inspection cycle is extended. The system then determines the current environmental state based on the relationship between the effective osmotic pressure difference and the upper and lower limits of the osmotic pressure difference. Specifically, when the effective osmotic pressure difference is less than the lower limit, the system determines that the current environment is in an overly humid state. In this case, the system reduces excessive water absorption by lowering the ambient water activity or increasing the ambient temperature. When the effective osmotic pressure difference is greater than the upper limit, the system determines that the current environment is in an overly dry state. In this case, the system prevents cell water loss by increasing the ambient water activity or lowering the ambient temperature. When the effective osmotic pressure difference is between the upper and lower limits of the osmotic pressure difference, the system determines that the storage environment is in a normal state and no measures are taken.

[0072] Step 42: When the effective osmotic pressure difference is less than the lower limit of the osmotic pressure difference, it indicates that there is too much water in the cell. Increase the water activity of the environment or raise the ambient temperature to slow down the excessive water loss. Conversely, decrease the water activity or lower the ambient temperature. After adjustment, recalculate the effective osmotic pressure difference until the effective osmotic pressure difference is between the upper and lower limits of the osmotic pressure difference to ensure that the water potential difference between the inside and outside of the cell is within a safe range.

[0073] Step 43: After the adjustment is completed, calculate the rate of change of effective osmotic pressure difference and the standard deviation of equivalent inhibition within two consecutive inspection cycles. When the rate of change is less than the preset steady-state threshold and the standard deviation is less than the preset standard deviation threshold, the system is determined to be in steady state. The current environmental water activity and environmental temperature are then fixed and used as the parameter input for the next cycle.

[0074] This embodiment allows the system to dynamically respond to changes in environmental temperature and humidity by adjusting the inspection cycle, avoiding stability issues caused by long-term deviations. By combining the inhibition gap and osmotic pressure difference constraints, it ensures precise temperature and humidity control, reduces the risk of chilling injury, and ensures the water potential balance and metabolic stability of fresh food, thereby extending the shelf life and maintaining the quality of fresh food.

[0075] In one embodiment of the present invention, the disturbance handover verification module includes:

[0076] Step 51: When the temperature change rate exceeds the preset disturbance threshold, a disturbance flag is generated, and the disturbance level and backtracking range are determined according to the magnitude of the exceedance of the preset disturbance threshold. Among them, the equivalent suppression degree is recalculated for mild disturbances, and the effective osmotic pressure difference and the initial set values ​​of the main variables are recalculated simultaneously for moderate and severe disturbances. Through this method, the system can accurately identify disturbances of different intensities and take corresponding response measures to avoid the temperature and humidity fluctuations caused by disturbances from affecting the stability of the storage environment.

[0077] Step 52: After backtracking, determine whether the ambient temperature exceeds the upper or lower limit of the chilling injury temperature window. If it exceeds the lower limit, switch to the osmosis priority path and prioritize adjusting water activity to prevent cells from absorbing too much water. If it exceeds the upper limit, switch to the temperature priority path and prioritize adjusting the ambient temperature to prevent cells from dehydrating. Set a lockout period. If the temperature does not exceed the limit again within the lockout period, maintain the current priority path; otherwise, postpone the path switching.

[0078] Step 53: At the end of the batch, extract the reference temperature, target inhibition level, and upper and lower limits of osmotic pressure difference. Calculate the deviation between the batch's average effective osmotic pressure difference and the target value. After removing sampling points with excessive variance, adjust the reference temperature and target inhibition level according to the target value deviation. The target value deviation is the difference between the average effective osmotic pressure difference and the median of the upper and lower limits of the osmotic pressure difference. The target value deviation represents the difference between the current environmental control and the target ideal environment. When the target value deviation is positive, it indicates that the current osmotic pressure difference is too large. The system reduces the osmotic pressure difference by lowering the ambient temperature and simultaneously increases the inhibition level to slow down cell metabolism. Conversely, when the target value deviation is negative, the system increases the osmotic pressure difference by raising the ambient temperature and simultaneously decreases the inhibition level to increase the metabolic rate.

[0079] This embodiment precisely controls the metabolic rate and moisture balance of fresh food by flexibly adjusting the temperature and humidity control path and variable settings, thereby extending the shelf life of fresh food. Through the synergistic effect of temperature and humidity regulation and osmotic pressure control, it effectively avoids chilling injury and excessive dehydration, ensuring the quality stability and storage effect of fresh food.

[0080] In one embodiment of the present invention, during the disturbance detection and backtracking process, the temperature change rate and acceleration are calculated based on the ambient temperature, and a weighted sum is obtained to obtain a disturbance prediction value, which is used to represent the intensity and suddenness of the current ambient temperature change. When the disturbance prediction value is higher than the preset disturbance precursor threshold, the system determines that there is a disturbance risk and enters a buffering phase to reduce the adjustment rate of ambient temperature and ambient water activity, so as to avoid osmotic pressure imbalance and low temperature barrier damage caused by temperature and humidity fluctuations. A delayed response time window is set according to the disturbance level, and the backtracking recalculation of the equivalent inhibition degree and effective osmotic pressure difference is performed step by step within the delayed response time window. When the backtracking recalculation result meets the upper and lower limits of the osmotic pressure difference, the buffering phase is terminated and the normal control process is restored.

[0081] This embodiment can effectively cope with environmental temperature and humidity fluctuations through disturbance detection and backtracking. By using buffering phases and delayed response mechanisms to reduce system oscillations, the system can maintain stability when dealing with disturbances, avoid cell damage or chilling injury caused by over-adjustment, effectively extend the shelf life of fresh food and maintain its quality stability.

[0082] It should be noted that the interval and threshold sizes are set for ease of comparison. The size of the threshold depends on the amount of sample data and the base number set by those skilled in the art for each set of sample data, as long as it does not affect the proportional relationship between the parameter and the quantized value. Furthermore, the above formulas are all dimensionless calculations, and the formulas are derived from software simulations using a large amount of collected data to obtain the most recent real-world results. The preset parameters in the formulas are set by those skilled in the art according to the actual situation.

[0083] The embodiments of the present invention have been described above, but the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms based on the guidance of the present embodiments, all of which are within the protection scope of the present embodiments.

Claims

1. A fresh food preservation control system based on osmotic pressure in synergy with a low temperature barrier, characterized in that, include: The category parameter locking module is used to acquire and fix the category parameter set of the current batch of fresh food. The category parameter set includes: reference temperature, lower and upper limits of the chilling injury temperature window, upper limit of osmotic pressure difference, lower limit of osmotic pressure difference, water activity of fresh food tissue cells, and target inhibition degree. The initial measurement conversion and evaluation module is used to collect ambient temperature and relative humidity, convert them to ambient water activity, and determine the equivalent inhibition degree, inhibition gap, and effective osmotic pressure difference based on the category parameter set. Specifically, the temperature difference is obtained by calculating the difference between the reference temperature and the ambient temperature, the negative logarithm of the ambient water activity is calculated to obtain the water activity term, and the equivalent inhibition degree is obtained by weighted summation of the temperature difference and the water activity term based on the temperature term constant and the water activity constant. The inhibition gap is obtained by comparing the target inhibition level with the equivalent inhibition level in the category parameter set; The effective osmotic pressure difference is obtained by taking the natural logarithm of the environmental water activity and the fresh food tissue cell water activity, respectively. The product of the environmental temperature and the gas constant is divided by the molar volume of water, and the negative number is multiplied by the difference. The priority path determination module is used to determine the priority control path based on the sign of the inhibition gap, the ambient temperature, and the upper limit temperature of the cold injury temperature window, and to determine the main and secondary variables. The main variable correction module is used to adjust the ambient temperature and ambient water activity according to the priority control path, and to verify the equivalent inhibition degree and effective osmotic pressure difference with the upper limit of osmotic pressure difference as a constraint. The secondary variable fine-tuning module is used to fill the inhibition gap within the range specified by the category parameter set using secondary variables, and to verify the equivalent inhibition and effective osmotic pressure difference after fine-tuning. The inspection and limiting module is used to review the effective osmotic pressure difference according to the inspection cycle, and adjust the environmental water activity and ambient temperature based on the relationship between the effective osmotic pressure difference and the lower and upper limits of the osmotic pressure difference. The disturbance switching verification module is used to return to the initial test conversion evaluation module when environmental disturbances occur, switch the priority path when crossing the upper and lower limits of the cold damage temperature window, and perform static parameter verification on the category parameter set at the end of the batch.

2. The osmotic pressure based, synergistic low temperature barrier based fresh food preservation control system according to claim 1, characterized in that, The process of determining the priority control path, as well as the main and secondary variables, includes: Step 11: Determine the sign of the inhibition gap. When the inhibition gap is greater than zero and the duration exceeds the preset time threshold, proceed to the path determination process. Step 12: When the ambient temperature is higher than the upper limit temperature of the chilling injury window, it is determined as the temperature-priority path; when the ambient temperature is less than or equal to the upper limit temperature of the chilling injury window, it is determined as the infiltration-priority path. Step 13: In the temperature-priority path, ambient temperature is the primary variable and ambient water activity is the secondary variable; in the permeability-priority path, ambient water activity is the primary variable and ambient temperature is the secondary variable, and priority path identifiers are generated.

3. The osmotic pressure based, synergistic low temperature barrier based fresh food preservation control system as claimed in claim 1, wherein, Adjust the ambient temperature and ambient water activity, and verify the equivalent inhibition degree and effective osmotic pressure difference, including: Step 21, determining the main variable and adjustment direction according to the priority path identifier, under the condition that the secondary variable remains unchanged, inversely adjusting the main variable according to the difference between the target depression and the current equivalent depression, when the priority path identifier is the temperature priority path, reducing the environmental temperature, when the priority path identifier is the permeation priority path, reducing the environmental water activity, calculating the increment of the equivalent depression caused by the change of the main variable, when the increment is equal to the depression gap, determining the candidate setting value of the main variable; Step 22, reviewing the equivalent depression and the effective osmotic pressure difference with the candidate setting value of the main variable as the input, wherein, when the review result is greater than the upper limit of the osmotic pressure difference, the main variable is gradually returned by a preset step size, and the equivalent depression and the effective osmotic pressure difference are recalculated after each return, until the effective osmotic pressure difference is less than or equal to the upper limit of the osmotic pressure difference; Step 23, when the effective osmotic pressure difference is less than or equal to the upper limit of the osmotic pressure difference and the equivalent depression reaches the target depression, the current main variable value is solidified as the main variable setting value, and the corresponding equivalent depression and effective osmotic pressure difference are output.

4. The osmotic pressure based, synergistic low temperature barrier based fresh food preservation control system as claimed in claim 1, wherein, Supplementing the depression gap and reviewing the equivalent depression and the effective osmotic pressure difference, comprising: Step 31, calculating the difference between the current equivalent depression and the target depression to obtain a residual depression gap, and determining the secondary variable type according to the priority path identifier, when the priority path identifier is the temperature priority path, the secondary variable is the environmental water activity, when the priority path identifier is the permeation priority path, the secondary variable is the environmental temperature, and setting the secondary variable step size to a preset proportion within the range specified in the category parameter set; wherein the step size of the secondary variable is less than the preset proportion of the step size of the main variable; Step 32, determining the adjustment direction of the secondary variable according to the sign of the residual depression gap, recalculating the equivalent depression and the effective osmotic pressure difference after each adjustment, when the calculated effective osmotic pressure difference is greater than the upper limit of the osmotic pressure difference, returning the last step of the secondary variable adjustment and re-reviewing until the effective osmotic pressure difference is less than or equal to the upper limit of the osmotic pressure difference; Step 33, when the difference between the equivalent depression and the target depression is less than a preset tolerance threshold and the effective osmotic pressure difference does not exceed the upper limit of the osmotic pressure difference, solidifying the current secondary variable value as the secondary variable setting value.

5. The osmotic pressure based, synergistic low temperature barrier based fresh food preservation control system according to claim 4, characterized in that, During the main variable correction and secondary variable fine-tuning process, when the residual depression gap of the equivalent depression after the main variable adjustment and the change direction of the effective osmotic pressure difference deviation are inconsistent, the arctangent value of the ratio of the effective osmotic pressure difference deviation to the residual depression gap is calculated to obtain the deviation phase, and the cosine value is calculated to obtain the deviation compensation weight coefficient, and the modification amplitude of the secondary variable is proportionally adjusted according to the deviation compensation weight coefficient; wherein the effective osmotic pressure difference deviation is the difference between the effective osmotic pressure difference and the median of the upper and lower limits of the osmotic pressure difference.

6. The osmotic pressure based, synergistic low temperature barrier based fresh food preservation control system as claimed in claim 1, wherein, Reviewing the effective osmotic pressure difference and adjusting the environmental water activity and the environmental temperature, comprising: Step 41, obtaining the environmental water activity and the effective osmotic pressure difference in each inspection cycle, when the change rate of the effective osmotic pressure difference of two consecutive inspections is greater than a preset change rate threshold, shortening the inspection cycle, otherwise, lengthening the inspection cycle, and determining the current environmental state according to the relationship between the effective osmotic pressure difference and the upper and lower limits of the osmotic pressure difference; Step 42, when the effective osmotic pressure difference is less than the lower limit of the osmotic pressure difference, the environmental water activity or the ambient temperature is increased, otherwise, the water activity or the ambient temperature is decreased, and the effective osmotic pressure difference is recalculated after adjustment until the effective osmotic pressure difference is between the upper and lower limits of the osmotic pressure difference; Step 43, after the adjustment is completed, the change rate of the effective osmotic pressure difference and the standard deviation of the equivalent inhibition system in the continuous two inspection periods are calculated, when the change rate is less than the preset steady state threshold and the standard deviation is less than the preset standard deviation threshold, it is determined that the system is in steady state, and the current environmental water activity and environmental temperature are solidified.

7. The osmotic pressure based, synergistic low temperature barrier based fresh food preservation control system as claimed in claim 1, wherein, The disturbance switching verification module comprises: Step 51, when the temperature change rate exceeds the preset disturbance threshold, a disturbance identifier is generated, and the disturbance level and the backtracking range are determined according to the amplitude exceeding the preset disturbance threshold, wherein the equivalent inhibition system is recalculated for light disturbance, and the initial setting value of the effective osmotic pressure difference and the main variable is recalculated for moderate and severe disturbance; Step 52, after backtracking, it is judged whether the environmental temperature crosses the upper and lower limits of the chilling injury temperature window, when crossing the lower limit, the osmotic priority path is switched, when crossing the upper limit, the temperature priority path is switched, a lock period is set, when the temperature does not cross again in the lock period, the current priority path is maintained, otherwise the path switching is delayed to take effect; Step 53, at the end of the batch, the reference temperature, the target inhibition system and the osmotic pressure difference upper and lower limits are extracted, the deviation of the batch average effective osmotic pressure difference from the target value is calculated, after eliminating the sampling points with variance exceeding the limit, the reference temperature and the target inhibition system are adjusted according to the deviation of the target value, wherein the deviation of the target value is the difference between the average effective osmotic pressure difference and the median value of the osmotic pressure difference upper and lower limits.

8. The osmotic pressure based, synergistic low temperature barrier based fresh food preservation control system according to claim 7, characterized in that, In the disturbance detection and backtracking process, the temperature change rate and the change acceleration are calculated according to the environmental temperature, the disturbance prediction value is obtained by weighted summation, when the disturbance prediction value is higher than the preset disturbance precursor threshold, the buffer stage is entered, the adjustment rate of the environmental temperature and the environmental water activity is reduced; and a delay response time window is set according to the disturbance level, the backtracking and recalculation of the equivalent inhibition system and the effective osmotic pressure difference are performed step by step in the delay response time window, when the backtracking and recalculation result satisfies the upper and lower limits of the osmotic pressure difference, the buffer stage is terminated and the normal control process is restored.

Images