Intelligent control system for storage temperature of quick-frozen large health polypeptide food

Abstract

The application discloses a quick-frozen large-health polypeptide food storage temperature intelligent regulation system and belongs to the technical field of freezing regulation, and specifically comprises the following modules: a parameter acquisition module, a pulse modulation module, a delay acquisition module, an amplification comparison module, a deep cooling switching module and a constant temperature maintenance module. The delay response time of the center temperature of food is monitored by actively applying refrigerant flow pulse modulation, the delay time amplification is taken as the glass transition criterion, the deep cooling flow cooling is switched after it is determined that the glass transition stage is entered, and the maintenance flow is switched and kept stable after the target temperature is reached. According to the application, the glass transition moment is dynamically identified according to the actual thermal response characteristics of food, and the refrigerant flow is matched, so that the cooling process is synchronized with the internal state change of polypeptide food.

Description

Technical Field

[0001] This invention relates to the field of freezing control technology, specifically to an intelligent temperature control system for storing quick-frozen health-promoting polypeptide foods. Background Technology

[0002] Health-promoting peptide foods contain various bioactive peptide molecules, and their quick-freezing storage process directly affects the structural stability and subsequent bioactivity of these peptide molecules. During cooling, peptide molecules undergo a glass transition, changing from a rubbery state to a glassy state. In the glassy state, the movement of peptide molecular chains is frozen, significantly reducing the rate of internal chemical reactions and greatly improving storage stability. Rapidly cooling peptide foods to below their glass transition temperature and maintaining a stable low temperature is a key technical aspect of quick-freezing storage. During the quick-freezing process, the refrigerant flow rate needs to be adjusted to control the cooling rate and the final storage temperature.

[0003] In existing technologies, the temperature control for quick-freezing storage of polypeptide foods typically employs a preset cooling curve. This involves selecting a set of fixed refrigerant flow control parameters from a pre-stored cooling program based on the food's initial temperature and weight, and then sequentially adjusting the refrigerant flow rate over time to lower the food temperature along the preset curve. Some existing technologies also incorporate multiple temperature sensors within the quick-freezing storage chamber. By monitoring changes in the chamber's air temperature or the food's surface temperature, these sensors trigger a refrigerant flow switching operation when a preset temperature threshold is reached. All of these methods rely solely on temperature values ​​as the control criterion and do not involve real-time detection of changes in the food's internal physical state.

[0004] However, existing technologies that trigger refrigerant flow switching based on preset temperature nodes cannot identify the actual moment when peptide foods undergo a glass transition during cooling. The glass transition temperature of peptide foods depends on the molecular weight distribution range of the peptides; different batches of peptide foods have different molecular weight distributions, resulting in different glass transition temperatures. When a uniform preset temperature node is used as the criterion for refrigerant flow switching, a deviation occurs between the preset temperature node and the actual glass transition temperature of the food. If the preset temperature node is higher than the actual glass transition temperature, the refrigerant flow is switched to a maintenance flow before the food enters the glassy state, causing the cryogenic cooling phase to terminate prematurely and prolonging the time that the peptide molecules inside the food spend in the non-glassy state. If the preset temperature node is lower than the actual glass transition temperature, the refrigerant flow remains at a cryogenic flow even after the food has entered the glassy state, causing the refrigeration equipment to operate at a high load continuously, resulting in a cooling output exceeding actual demand. Summary of the Invention

[0005] The purpose of this invention is to provide an intelligent temperature control system for the storage of quick-frozen health-promoting polypeptide foods, solving the following technical problems:

[0006] Existing technologies trigger refrigerant flow switching based on preset temperature nodes, which cannot identify deviations in the actual glass transition temperature caused by differences in molecular weight distribution between different batches of polypeptide foods. The timing of refrigerant flow switching is inconsistent with the actual glass transition time of the food, resulting in switching too early or too late.

[0007] The objective of this invention can be achieved through the following technical solutions: A smart temperature control system for storing quick-frozen health-promoting polypeptide foods includes: The parameter acquisition module is used to place polypeptide foods into the quick-freezing storage chamber, acquire initial polypeptide molecular weight distribution data, collect the initial core temperature value of the food, and collect the initial air temperature value of the quick-freezing storage chamber. The pulse modulation module is used to start the cooling process and continuously cool down at the initial operating flow rate. During the cooling process, the refrigerant flow rate is periodically pulse-modulated. Each modulation momentarily increases the flow rate and maintains it for a fixed duration before resuming. The delayed acquisition module is used to continuously acquire the core temperature value of food during cooling. For each pulse modulation, the inflection point of the first rise in core temperature is detected, and the interval from the modulation time to the inflection point is recorded as the temperature response delay time. The amplification comparison module is used to take the temperature response delay time calculation benchmark value of the initial few modulations, and then calculate the increase of the delay time of each subsequent modulation relative to the benchmark value, comparing the increase with the pre-stored amplification criteria one by one. The cryogenic switching module is used to determine that the food's core temperature has entered the glass transition stage when the increase of several consecutive modulations exceeds the pre-stored increase criterion. It then switches the refrigerant flow rate from the initial operating flow rate value to the cryogenic flow rate value and stops pulse modulation. The constant temperature maintenance module is used to continue cooling at the cryogenic flow rate and continuously collect the air temperature value. When the air temperature value drops to the lower limit of the glassy storage temperature range, the refrigerant flow rate is switched from the cryogenic flow rate value to the maintenance flow rate value and the operation is maintained.

[0008] As a further aspect of the present invention: the specific process of periodically applying pulse modulation to the refrigerant flow rate in the pulse modulation module is as follows: During the cooling process, the food's center temperature value is collected in real time, and the rate of decrease in center temperature is calculated. The current rate of decrease in center temperature is compared with the rate of decrease in center temperature in the previous modulation cycle. When the rate of decrease in center temperature slows down and the amount of slowdown exceeds the pre-stored rate change threshold, the modulation interval of the next modulation cycle is shortened and the instantaneous increase in flow rate is increased. When the rate of decrease in center temperature does not slow down or the amount of slowdown does not exceed the pre-stored rate change threshold, the modulation interval and flow rate of the previous modulation cycle are kept unchanged. The amount of shortening of the modulation interval is calculated according to the pre-stored ratio based on the amount of slowdown in center temperature decrease, and the amount of increase in flow rate is calculated according to the pre-stored ratio based on the amount of slowdown in center temperature decrease.

[0009] As a further aspect of the present invention: the specific process of detecting the turning point of the first rise in the center temperature in the delayed acquisition module is as follows: Starting from the pulse modulation moment, a series of consecutive sampling points from the center temperature time series, starting from the modulation moment, are extracted to form an observation window. The first-order difference sequence of the center temperature values ​​within the observation window is calculated. In the first-order difference sequence, the first position where the value changes from negative to positive and the two consecutive difference values ​​following it are both positive are searched in chronological order. The sampling moment corresponding to the position is marked as the turning point. If no position in the difference sequence that meets the condition of changing from negative to positive and the two consecutive difference values ​​following it are both positive are found within the observation window, the sampling moment corresponding to the lowest center temperature value within the observation window is marked as the turning point.

[0010] As a further aspect of the present invention: the specific process for calculating the increase in delay time relative to the reference value in the increase comparison module is as follows: The temperature response delay time of the initial modulation is used to calculate the baseline value, and the standard deviation of the temperature response delay time of the initial modulation is also calculated. The standard deviation is multiplied by the pre-stored expansion coefficient to obtain the fluctuation tolerance range. For each subsequent modulation, the difference between the temperature response delay time of the current modulation and the baseline value is calculated. The difference is divided by the fluctuation tolerance range to obtain the standardized increase. The standardized increase is compared with the pre-stored increase criterion.

[0011] As a further aspect of the present invention: the specific process of comparing the increase with the pre-stored increase criteria in the increase comparison module is as follows: Multiple groups of peptide standard samples with known molecular weight distribution ranges were prepared. A pulse-modulated cooling process was performed on each group of standard samples, and the temperature response delay time and the corresponding food center temperature value were recorded for each modulation cycle. A joint distribution curve of the increase in temperature response delay time as the first coordinate axis and the food center temperature value as the second coordinate axis was plotted. On the joint distribution curve, the boundary position where the increase in temperature response delay time begins to leave the initial aggregation value range and the corresponding food center temperature value enters the pre-stored glass transition reference temperature range was determined. The increase value at the boundary position and the food center temperature value were recorded together as a joint criterion and stored in accordance with the molecular weight distribution range. The increase value of the current time was compared with the increase value in the joint criterion.

[0012] As a further aspect of the present invention: the specific process by which the food's core temperature is determined to enter the glass transition stage in the cryogenic switching module is as follows: When the increase of several consecutive modulations exceeds the pre-stored increase criterion, the current food center temperature value is simultaneously collected, and the cooling rate of the food center temperature value within the preset backtracking time is calculated. The calculated cooling rate is compared with the pre-stored critical cooling rate for glass transition. When the cooling rate is lower than the pre-stored critical cooling rate for glass transition, it is determined that the food center temperature has entered the glass transition stage. When the cooling rate is not lower than the pre-stored critical cooling rate for glass transition, it is not determined that the food has entered the glass transition stage, and subsequent pulse modulation is continued, and the increase comparison and cooling rate comparison are repeated.

[0013] As a further aspect of the present invention: the specific process of switching the refrigerant flow rate from the initial operating flow rate value to the cryogenic flow rate value in the cryogenic switching module is as follows: When it is determined that the food's core temperature has entered the glass transition stage, the food's core temperature value at the determination time is recorded. The remaining temperature difference is obtained by subtracting the food's core temperature value at the determination time from the pre-stored lower limit of the glassy storage temperature range. The remaining temperature difference is divided by the pre-stored allowable deep cryogenic cooling duration to obtain the required cooling rate. The refrigerant flow rate value corresponding to the required cooling rate is retrieved based on the pre-stored correspondence between the cooling rate and the refrigerant flow rate. The refrigerant flow rate is then switched from the initial operating flow rate value to the retrieved refrigerant flow rate value.

[0014] As a further aspect of the present invention: the specific process of switching the refrigerant flow rate from the cryogenic flow rate value to the maintenance flow rate value in the constant temperature maintenance module is as follows: After switching to maintain the flow rate, the air temperature value is continuously collected and the slope of the air temperature value change trend within the preset time window is calculated. The value of the fine-tuning step is calculated according to the absolute value of the slope of the change trend in a linear relationship. When the slope of the trend is positive and the air temperature has not exceeded the upper limit of the glassy storage temperature range, the refrigerant flow rate is increased by the calculated fine-tuning step. When the slope of the trend is negative and the air temperature has not fallen below the lower limit of the glassy storage temperature range, the refrigerant flow rate is decreased by the calculated fine-tuning step.

[0015] The beneficial effects of this invention are: This invention actively applies refrigerant flow pulse modulation and monitors the delayed response of the food's core temperature. The increase in the temperature response delay time is used as the criterion for identifying the glass transition of peptide foods, replacing the existing method of triggering refrigerant flow switching based on a preset temperature node. Because the internal thermal conductivity of peptide foods changes before and after the glass transition, the temperature response delay time caused by the refrigerant flow pulse experiences a sudden increase during the glass transition stage. The timing of this sudden increase is synchronized with the actual glass transition moment of the peptide food, unaffected by differences in the molecular weight distribution of peptides between different batches. This solves the problem of inconsistent refrigerant flow switching timing caused by deviations between the preset temperature node and the actual glass transition temperature. After determining the glass transition stage, the required cooling rate is calculated based on the remaining temperature difference between the food's core temperature and the target storage temperature at the determination time, and a cryogenic flow rate value is matched. The refrigerant flow rate corresponds to the actual cooling requirement of the food, avoiding premature switching of the cryogenic flow rate to the maintenance flow rate or excessive delay in maintaining the cryogenic flow rate. The cooling output of the refrigeration equipment matches the actual needs of the peptide food at each stage of quick-freezing storage. Attached Figure Description

[0016] The invention will now be further described with reference to the accompanying drawings.

[0017] Figure 1 This is a schematic diagram of the modules of the present invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Please see Figure 1 As shown, this invention is an intelligent temperature control system for storing quick-frozen health-promoting polypeptide foods, comprising: The parameter acquisition module is used to place polypeptide foods into the quick-freezing storage chamber, acquire initial polypeptide molecular weight distribution data, collect the initial core temperature value of the food, and collect the initial air temperature value of the quick-freezing storage chamber. The pulse modulation module is used to start the cooling process and continuously cool down at the initial operating flow rate. During the cooling process, the refrigerant flow rate is periodically pulse-modulated. Each modulation momentarily increases the flow rate and maintains it for a fixed duration before resuming. The delayed acquisition module is used to continuously acquire the core temperature value of food during cooling. For each pulse modulation, the inflection point of the first rise in core temperature is detected, and the interval from the modulation time to the inflection point is recorded as the temperature response delay time. The amplification comparison module is used to take the temperature response delay time calculation benchmark value of the initial few modulations, and then calculate the increase of the delay time of each subsequent modulation relative to the benchmark value, comparing the increase with the pre-stored amplification criteria one by one. The cryogenic switching module is used to determine that the food's core temperature has entered the glass transition stage when the increase of several consecutive modulations exceeds the pre-stored increase criterion. It then switches the refrigerant flow rate from the initial operating flow rate value to the cryogenic flow rate value and stops pulse modulation. The constant temperature maintenance module is used to continue cooling at the cryogenic flow rate and continuously collect the air temperature value. When the air temperature value drops to the lower limit of the glassy storage temperature range, the refrigerant flow rate is switched from the cryogenic flow rate value to the maintenance flow rate value and the operation is maintained.

[0020] In a preferred embodiment of the present invention, the specific process of periodically applying pulse modulation to the refrigerant flow rate in the pulse modulation module is as follows: After the compressor of the refrigeration equipment starts, the refrigerant circulates in the evaporator pipes at the initial operating flow rate, and the air temperature and the core temperature of the food in the quick-freezing storage chamber begin to decrease. During the cooling process, the core temperature of the food is continuously collected at a preset sampling interval of 2 seconds. Each time a new core temperature value is collected, it is immediately subtracted from the core temperature value collected at the previous sampling time. The difference is then divided by the sampling interval to obtain the current rate of decrease in core temperature. The rate of decrease in core temperature represents the speed at which heat is transferred from the inside of the food to the outside; this rate is affected by the temperature difference between the food and the air in the storage chamber, as well as the thermal diffusivity of the food itself.

[0021] The current rate of temperature decrease is compared with the rate of temperature decrease in the previous modulation cycle. The rate of temperature decrease in the previous modulation cycle is taken as the rate of decrease calculated from the last sample in the previous modulation cycle. During the comparison, the difference between the current rate of decrease and the rate of decrease in the previous cycle is calculated. If the difference is positive, it indicates that the rate of decrease has slowed down, that is, the speed at which the food's center temperature decreases is slowing down; if the difference is zero or negative, it indicates that the rate of decrease has not slowed down or has accelerated.

[0022] When the rate of decrease in the center temperature slows down, it is further determined whether the slowdown exceeds the pre-stored rate change threshold. The slowdown is the absolute value of the difference between the current rate of decrease and the rate of decrease in the previous cycle. The pre-stored rate change threshold is the upper limit of the natural fluctuation range of the rate of decrease, obtained in advance through temperature testing of multiple sets of peptide standard samples under the same operating conditions. If the slowdown exceeds the pre-stored rate change threshold, it indicates that the current rate slowdown is not caused by temperature sampling noise or minor environmental fluctuations, but rather by a substantial change in the internal thermal conductivity of the food. At this point, the modulation parameters are adjusted, shortening the modulation interval of the next modulation cycle and increasing the instantaneous increase in flow rate.

[0023] The reduction in modulation interval duration is calculated based on the reduction in the rate of decrease in center temperature according to a pre-stored ratio. The pre-stored ratio is determined as follows: during the calibration phase, for a peptide reference sample with a known molecular weight distribution range, the optimal modulation interval duration is tested under different reduction conditions. A correspondence between the reduction and the reduction in interval duration is established and stored. During conversion, the current reduction is input into this correspondence, and the corresponding reduction value is output. The increase in flow rate amplitude is also calculated based on the reduction according to a pre-stored ratio, and the pre-stored ratio is determined in the same way as described above.

[0024] When the rate of decrease in the center temperature does not slow down or the amount of slowdown does not exceed the pre-stored rate change threshold, the modulation interval duration and flow amplitude of the previous modulation cycle remain unchanged, and subsequent pulse modulation is performed with the original modulation parameters.

[0025] In another preferred embodiment of the present invention, the specific process of detecting the turning point of the first rise in the center temperature in the delayed acquisition module is as follows: At each pulse modulation execution moment, the refrigerant flow rate increases instantaneously, the refrigerant circulation volume in the evaporator pipes increases, and the air temperature in the quick-freezing storage chamber experiences a brief, accelerated drop. This accelerated drop is transferred to the interior of the food through convective heat transfer between the air and the food surface, causing a change in the food's core temperature response. From the moment of pulse modulation, it is necessary to identify the inflection point in the core temperature response to this refrigerant flow pulse within the core temperature time series.

[0026] Starting from the pulse modulation moment, a series of consecutive sampling points from the center temperature time series, beginning at the modulation moment, constitute an observation window. The number of sampling points included in the observation window is determined based on the center temperature sampling interval and the pulse modulation duration, and is set to three times the quotient obtained by dividing the pulse modulation duration by the center temperature sampling interval. For example, if the pulse modulation duration is 10 seconds and the center temperature sampling interval is 2 seconds, then the observation window contains 15 sampling points. This window length covers the complete time period from the application of the refrigerant flow pulse to the generation and recovery of the food's center temperature.

[0027] Calculate the first-order difference sequence of center temperature values ​​within the observation window. The first-order difference sequence is generated by subtracting the center temperature value of the previous sampling point from the center temperature value of the next sampling point within the observation window, along the direction of increasing time. This results in a sequence of differences arranged chronologically. A positive first-order difference value indicates that the center temperature increased within that sampling interval; a negative first-order difference value indicates that the center temperature decreased within that sampling interval; and a first-order difference value of zero indicates that the center temperature remained unchanged within that sampling interval.

[0028] In a first-order difference sequence, the search is performed sequentially to find the first position where a negative value turns positive and is immediately followed by two consecutive positive difference values. The search begins with the second element of the difference sequence and checks if each element meets the following three conditions: the current element's value is greater than zero; the value of the element preceding it is less than zero; and the values ​​of the two elements following it are both greater than zero. The position where all three conditions are met is the target search position, and the corresponding sampling time is marked as the inflection point. The requirement that the two consecutive positive difference values ​​eliminate single-point fluctuations caused by temperature sampling noise, confirming that the center temperature has entered a sustained recovery phase rather than a momentary fluctuation.

[0029] If no differential sequence position meeting the above conditions is found within the observation window, it indicates that the food's center temperature did not rise continuously after the pulse modulation, but instead continued to fall or fluctuated irregularly. In this case, the sampling time corresponding to the lowest center temperature value within the observation window is marked as the turning point. The lowest value is determined by iterating through the center temperature values ​​of all sampling points within the observation window and finding the sampling point with the smallest value through comparison.

[0030] In another preferred embodiment of the present invention, the specific process of calculating the increase in delay time relative to the reference value in the amplification comparison module is as follows: After initiating cooling and pulse modulation, the temperature response delay time corresponding to each pulse modulation is continuously recorded. The temperature response delay time refers to the time interval from the moment pulse modulation is applied until the point where the food's core temperature first rises. This time interval reflects the food's internal thermal response speed to the instantaneous increase in refrigerant flow. In the initial stage of the cooling process, the food's core temperature is high, and the moisture and peptide molecules inside the food are in a highly elastic state. The heat conduction path is unobstructed, and the temperature disturbance caused by the refrigerant flow pulse can be quickly transmitted to the food's core and captured by the temperature acquisition device. At this time, the temperature response delay time is short and the value is relatively stable.

[0031] A baseline value is calculated using the initial temperature response delay times from several modulation pulses. The initial number of values ​​is a pre-defined fixed value, for example, the temperature response delay times corresponding to the first 8 pulse modulations. These 8 temperature response delay times are summed, and the sum is divided by 8 to obtain the arithmetic mean, which is the baseline value. The baseline value represents the thermal response characteristics of food in the initial cooling stage, before the glass transition has occurred.

[0032] Simultaneously, the standard deviation of the temperature response delay time for the initial several modulations is calculated. The calculation process for the standard deviation is as follows: calculate the difference between each of the eight temperature response delay time values ​​and the baseline value, square each difference to obtain eight squared values, calculate the sum of the eight squared values, divide the sum by 8 to obtain the average squared value, and then take the square root of the average squared value to obtain the standard deviation. The standard deviation reflects the dispersion of the temperature response delay time obtained from each modulation in the initial stage of cooling. The greater the dispersion, the more unstable the internal heat conduction state of the food.

[0033] The fluctuation tolerance range is obtained by multiplying the standard deviation by a pre-stored expansion factor. The value of the pre-stored expansion factor is determined based on the normal fluctuation range of the temperature response delay time in the initial cooling stage of polypeptide foods. The expansion factor is calibrated as follows: multiple groups of polypeptide standard samples with known molecular weight distribution ranges are subjected to pulse-modulated cooling. The temperature response delay time of each modulation in the initial stage is recorded. The standard deviation of the initial stage delay time and the maximum deviation of the subsequent stage delay time from the reference value are calculated for each group of samples. The ratio of the maximum deviation value to the standard deviation is taken as the expansion factor for that group of samples. The average of the expansion factors of multiple groups of samples is taken as the pre-stored expansion factor. The fluctuation tolerance range is the allowable range for fluctuation above and below the reference value. The delay time obtained by subsequent modulation falling within this range is considered normal fluctuation, and exceeding this range is considered a substantial change.

[0034] In each subsequent modulation, after acquiring the corresponding temperature response delay time, the difference between the current modulation's temperature response delay time and the baseline value is calculated. A positive difference indicates an increase in delay time, meaning a slower internal thermal response in the food; a negative difference indicates a decrease in delay time, meaning a faster internal thermal response in the food. Dividing the difference by the fluctuation tolerance range yields the standardized increase. The standardized increase is a dimensionless value representing the multiple by which the current delay time deviates from the baseline value relative to the normal fluctuation range. A larger standardized increase indicates a more significant extension of the delay time relative to the initial state.

[0035] The standardized increase was compared with the pre-stored increase criterion. The standardized increase eliminated the influence of differences in the absolute value and fluctuation range of the initial delay time among different batches of food, and directly reflected the extension multiple of the delay time relative to the initial state. The comparison results were not affected by individual differences in food.

[0036] In another preferred embodiment of the present invention, the specific process of comparing the increase with the pre-stored increase criteria in the increase comparison module is as follows: Before implementing this regulation method, it is necessary to establish amplification criteria corresponding to different molecular weight distribution ranges of peptides. The criteria are established by preparing multiple groups of peptide standard samples with known molecular weight distribution ranges and performing a pulse modulation cooling process.

[0037] When preparing peptide standard samples, four groups of peptide samples with molecular weight distribution ranges of 500 to 1000 Daltons, 1000 to 2000 Daltons, 2000 to 5000 Daltons, and 5000 to 10000 Daltons were selected. Each group of samples was prepared as a peptide aqueous solution with a water content of 75%, and dispensed into heat-conducting containers with container dimensions consistent with the dimensions of food packaging conventionally placed in a quick-freezing storage room.

[0038] Each set of standard samples was placed into the quick-freezing storage chamber one by one, and the cooling process was initiated, executing a pulse modulation cooling process. During the cooling process, the temperature response delay time of each modulation cycle was recorded, and the corresponding food center temperature value for each modulation cycle was simultaneously recorded by a temperature acquisition device. The food center temperature value was taken from the temperature value acquired at the execution time of each modulation cycle.

[0039] Throughout the entire process of reducing the initial temperature of each set of standard samples to the target storage temperature, data from dozens of modulation cycles were recorded. Each modulation cycle contained a pair of data: the temperature response delay time of that cycle and the corresponding food center temperature value. Based on these data, the increase in temperature response delay time for each modulation cycle was calculated. The calculation method for the increase was the same as that for the standardization increase in Implementation Method 1: the baseline value and standard deviation of the temperature response delay time of the initial 8 modulations of the set of standard samples were calculated. The standard deviation was multiplied by a pre-stored expansion coefficient to obtain the fluctuation tolerance range. The difference between the delay time of each subsequent modulation and the baseline value was divided by the fluctuation tolerance range to obtain the standardization increase.

[0040] Using the standardized increase as the first coordinate axis (vertical axis) and the food center temperature as the second coordinate axis (horizontal axis), a joint distribution curve is plotted, where the standardized increase and the food center temperature value corresponding to each modulation cycle are treated as a data point. The horizontal axis of the joint distribution curve corresponds to the decreasing direction of the food center temperature from high to low from left to right, and the vertical axis corresponds to the increasing direction of the standardized increase from small to large from bottom to top.

[0041] Observe the distribution pattern of data points on the joint distribution curve. In the initial stage of cooling, the temperature at the center of the food is relatively high, and the standardized increase values ​​of each modulation cycle are small and concentrated in a narrow range, which is called the initial clustered value range. As cooling continues, the temperature at the center of the food gradually decreases, and the standardized increase values ​​begin to deviate from the initial clustered value range near a certain temperature position, shifting in the direction of increasing values. Moreover, the standardized increase values ​​after the shift no longer fall back into the initial clustered value range.

[0042] On the joint distribution curve, determine the boundary position where the following two conditions are simultaneously met: the standardized increase begins to deviate from the initial aggregation value range, and the corresponding food center temperature value enters the pre-stored glass transition reference temperature range. The pre-stored glass transition reference temperature range is a common glass transition temperature distribution range for peptide foods, such as -25°C to -35°C. Record the standardized increase value and the food center temperature value at the boundary position together as the joint criterion corresponding to the molecular weight distribution range of that group of standard samples. Store the molecular weight distribution range of each group of standard samples and the joint criterion in the corresponding storage unit.

[0043] When implementing control measures on actual food products, after each modulation calculation to obtain the standardized increase, the matching joint criteria are retrieved from the storage unit based on the initial polypeptide molecular weight distribution data, and the standardized increase of the current time is compared with the increase value in the joint criteria.

[0044] In another preferred embodiment of the present invention, the specific process of determining whether the core temperature of the food has entered the glass transition stage in the cryogenic switching module is as follows: After each pulse modulation, a standardized amplification value is calculated and compared with a pre-stored amplification criterion. The pre-stored amplification criterion is an amplification value in a joint criterion determined in advance based on the characteristics of the delay time amplification change of the peptide standard sample during the pulse modulation cooling process. The comparison result is divided into two cases: the standardized amplification exceeds the pre-stored amplification criterion, or the standardized amplification does not exceed the pre-stored amplification criterion.

[0045] When the standardized increase exceeds the pre-stored increase criterion, the comparison result is recorded as "exceeding"; when the standardized increase does not exceed the pre-stored increase criterion, the comparison result is recorded as "not exceeding". A counter is set to accumulate the number of consecutive exceedances. The counter is incremented by 1 each time the comparison result is "exceeding" and reset to zero each time the comparison result is "not exceeding". When the accumulated value of the counter reaches the preset number of consecutive exceedances, the preliminary judgment condition for the glass transition stage is triggered.

[0046] The method for determining the consecutive count value is as follows: During the pre-calibration stage, pulse-modulated cooling tests are performed on peptide standard samples with different molecular weight distribution ranges. The actual number of times the standardized increase of each group of samples continuously exceeds the initial criterion near the glass transition temperature region is recorded. The minimum value of the measured counts of multiple groups of samples is taken as the consecutive count value corresponding to that molecular weight distribution range and stored in the storage unit. When performing control on actual food, the matching consecutive count value is retrieved from the storage unit based on the initial peptide molecular weight distribution data.

[0047] When the number of consecutive measurements reaches the retrieved value, perform the following operations: Simultaneously acquire the current food center temperature value. The food center temperature value is the temperature data at the geometric center of the food acquired by the temperature acquisition device at the moment the judgment condition is triggered. At the same time, acquire all food center temperature sampling records within a preset backtracking time before the current moment. The preset backtracking time is 3 times the pulse modulation period. For example, if the pulse modulation period is 30 seconds, the backtracking time is 90 seconds.

[0048] Subtracting the food's core temperature at the end of the backtracking period from the food's core temperature at the start of the backtracking period yields the temperature decrease within the backtracking period. Dividing this temperature decrease by the backtracking period gives the rate at which the food's core temperature decreases within the preset backtracking period. The rate at which the temperature decreases represents the average speed at which the food's core temperature decreases during the backtracking period, expressed in degrees Celsius per second.

[0049] The pre-stored critical cooling rate for glass transition is read from the storage unit. The pre-calibration method for the critical cooling rate for glass transition is as follows: Cooling tests are performed on multiple groups of peptide standard samples. The temperature difference between the food's center temperature and the air temperature is monitored using a temperature acquisition device. When the temperature difference reaches an inflection point where it gradually decreases and then tends to stabilize, the cooling rate at the food's center at that inflection point is recorded. The average cooling rate at the inflection point of multiple samples is taken as the critical cooling rate for glass transition. This critical cooling rate reflects the characteristic value of the cooling rate corresponding to the change in internal thermal conductivity of the peptide food during the glass transition.

[0050] The calculated cooling rate is compared with the pre-stored critical cooling rate for glass transition. When the cooling rate is lower than the pre-stored critical cooling rate for glass transition, it indicates that the rate of temperature decrease at the center of the food has slowed to the characteristic level corresponding to glass transition, and the food center temperature is determined to have entered the glass transition stage. When the cooling rate is not lower than the pre-stored critical cooling rate for glass transition, it indicates that the food center temperature has not yet entered the glass transition stage. In this case, it is not determined that the food has entered the glass transition stage, the counter is reset to zero, and the subsequent pulse modulation and the process of comparing the amplification rate with the cooling rate is repeated.

[0051] In another preferred embodiment of the present invention, the specific process of switching the refrigerant flow rate from the initial operating flow rate value to the cryogenic flow rate value in the cryogenic switching module is as follows: Once the food's core temperature is confirmed to have entered the glass transition stage, a refrigerant flow switching operation is immediately performed. The first step of the switching operation is to record the food's core temperature value at the time of the determination; this temperature value is the food's core temperature value collected synchronously when the determination is triggered.

[0052] The lower limit value of the pre-stored glassy state storage temperature range is read from the storage unit. The glassy state storage temperature range refers to the range of storage air temperatures that peptide foods should maintain after completing the glass transition. The lower and upper limits of this range are pre-calibrated and stored based on the peptide molecular weight distribution range. During reading, the initial peptide molecular weight distribution data is used as the search criteria to retrieve the matching lower limit value from the pre-stored peptide molecular weight distribution range and glassy state storage temperature range comparison record.

[0053] The remaining temperature difference is calculated by subtracting the pre-stored lower limit of the glassy storage temperature range from the food's core temperature at the time of determination. The remaining temperature difference represents the further decrease in the food's core temperature compared to the target lower limit of the storage air temperature. For example, if the food's core temperature at the time of determination is -15 degrees Celsius and the lower limit of the glassy storage temperature range is -30 degrees Celsius, then the remaining temperature difference is 15 degrees Celsius.

[0054] The required cooling rate is obtained by dividing the remaining temperature difference by the pre-stored allowable cryogenic cooling time. The allowable cryogenic cooling time refers to the maximum time permitted from the point at which food is determined to have entered the glass transition stage until the food's core temperature drops to the lower limit of the glassy storage temperature range. This time is calibrated by testing the time it takes for the core temperature of multiple groups of peptide standard samples to drop from the determination temperature to the target temperature at different cryogenic cooling rates, and taking the 90th percentile of the cooling times for multiple groups of samples as the allowable cryogenic cooling time. The required cooling rate represents the minimum cooling rate required to complete the reduction of the remaining temperature difference within the allowable time, expressed in degrees Celsius per minute.

[0055] The required cooling rate is retrieved based on a pre-stored correspondence between cooling rate and refrigerant flow rate. The pre-establishment of this correspondence is as follows: a standard load with known heat capacity is placed in the quick-freezing storage chamber. Different refrigerant flow rates are sequentially set and the refrigeration equipment is run. The air temperature cooling rate and the load center temperature cooling rate corresponding to each refrigerant flow rate are recorded. A lookup table is created by mapping the load center temperature cooling rate to the refrigerant flow rate and stored in the storage unit. During retrieval, the required cooling rate is compared one by one with the load center temperature cooling rates in the lookup table. The refrigerant flow rate corresponding to the cooling rate that is greater than or equal to the required cooling rate and has the closest value is selected as the cryogenic flow rate.

[0056] The refrigerant flow rate is switched from the initial operating flow rate value to the retrieved cryogenic flow rate value, and the pulse modulation execution is stopped, so that the refrigeration equipment enters the cryogenic cooling stage.

[0057] In another preferred embodiment of the present invention, the specific process of switching the refrigerant flow rate from the cryogenic flow rate value to the maintenance flow rate value in the constant temperature maintenance module is as follows: While the refrigeration equipment is operating at the cryogenic flow rate, the air temperature in the quick-freezing storage compartment is continuously collected via an air temperature sensor. The sampling interval for the air temperature is consistent with the sampling interval for the center temperature. Each time a new air temperature value is collected, it is compared with the lower limit of the glassy storage temperature range.

[0058] When the air temperature drops to the lower limit of the glassy state storage temperature range, a switchover operation is triggered, changing the refrigerant flow rate from the cryogenic flow rate to the maintenance flow rate. During the switchover, the corresponding maintenance flow rate is retrieved from a pre-stored maintenance flow rate reference record based on the initial peptide molecular weight distribution data. The maintenance flow rate refers to the refrigerant flow rate required by the refrigeration equipment to maintain the air temperature in the storage chamber within the glassy state storage temperature range after the food enters the glassy state. This flow rate is typically lower than the cryogenic flow rate. The maintenance flow rate is calibrated by testing the stability of the air temperature in the storage chamber under different refrigerant flow rates for multiple groups of peptide standard samples after cryogenic cooling. The refrigerant flow rate that maintains the air temperature near the median of the glassy state storage temperature range with the smallest fluctuation is selected as the maintenance flow rate.

[0059] Switching the refrigerant flow rate from the cryogenic flow rate value to the retrieved maintenance flow rate value, the refrigeration equipment enters the constant temperature maintenance stage.

[0060] After switching to a sustained flow rate, air temperature values ​​are continuously collected, and the slope of the air temperature change trend within a preset time window is calculated. The length of the preset time window is 10 times the air temperature sampling interval; for example, if the sampling interval is 2 seconds, the time window is 20 seconds. To calculate the slope, the latest collected air temperature value within the time window is subtracted from the air temperature value at the beginning of the time window to obtain the temperature difference. This temperature difference is then divided by the time window length to obtain the slope. A positive slope indicates that the air temperature is rising, while a negative slope indicates that the air temperature is falling. The absolute value of the slope indicates the rate of temperature change.

[0061] The fine-tuning step size is calculated based on a linear relationship between the absolute value of the slope and the trend. This linear relationship is established by pre-setting the minimum absolute value of the slope to correspond to the minimum fine-tuning step size, and the maximum absolute value of the slope to correspond to the maximum fine-tuning step size. The fine-tuning step size between the minimum and maximum values ​​is calculated using linear interpolation. For example, a minimum absolute slope value of 0.01 degrees Celsius per second corresponds to a fine-tuning step size of 1% of the initial operating flow rate, a maximum absolute slope value of 0.1 degrees Celsius per second corresponds to a fine-tuning step size of 5% of the initial operating flow rate, and when the actual absolute slope value is 0.05 degrees Celsius per second, the fine-tuning step size is 3% of the initial operating flow rate.

[0062] When the slope of the temperature change trend is positive and the air temperature has not yet exceeded the upper limit of the glassy storage temperature range, the refrigerant flow rate is increased by the calculated fine-tuning step. When the slope of the temperature change trend is negative and the air temperature has not yet fallen below the lower limit of the glassy storage temperature range, the refrigerant flow rate is decreased by the calculated fine-tuning step. The fine-tuning operation is performed when the temperature has not yet reached the range boundary but has shown a trend towards the boundary. The direction of refrigerant flow rate adjustment is opposite to the temperature change trend, and the adjustment magnitude is proportional to the rate of temperature change.

[0063] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A smart temperature control system for storing quick-frozen health-promoting polypeptide foods, characterized in that, include: The parameter acquisition module is used to place polypeptide foods into the quick-freezing storage chamber, acquire initial polypeptide molecular weight distribution data, collect the initial core temperature value of the food, and collect the initial air temperature value of the quick-freezing storage chamber. The pulse modulation module is used to start the cooling process and continuously cool down at the initial operating flow rate. During the cooling process, the refrigerant flow rate is periodically pulse-modulated. Each modulation momentarily increases the flow rate and maintains it for a fixed duration before resuming. The delayed acquisition module is used to continuously acquire the core temperature value of food during cooling. For each pulse modulation, the inflection point of the first rise in core temperature is detected, and the interval from the modulation time to the inflection point is recorded as the temperature response delay time. The amplification comparison module is used to take the temperature response delay time calculation benchmark value of the initial few modulations, and then calculate the increase of the delay time of each subsequent modulation relative to the benchmark value, comparing the increase with the pre-stored amplification criteria one by one. The cryogenic switching module is used to determine that the food's core temperature has entered the glass transition stage when the increase of several consecutive modulations exceeds the pre-stored increase criterion. It then switches the refrigerant flow rate from the initial operating flow rate value to the cryogenic flow rate value and stops pulse modulation. The constant temperature maintenance module is used to continue cooling at the cryogenic flow rate and continuously collect the air temperature value. When the air temperature value drops to the lower limit of the glassy storage temperature range, the refrigerant flow rate is switched from the cryogenic flow rate value to the maintenance flow rate value and the operation is maintained.

2. The intelligent temperature control system for storing quick-frozen health-promoting polypeptide foods according to claim 1, characterized in that, In the pulse modulation module, the specific process of periodically applying pulse modulation to the refrigerant flow rate is as follows: During the cooling process, the food's center temperature value is collected in real time and the center temperature drop rate is calculated. The current center temperature drop rate is compared with the center temperature drop rate of the previous modulation cycle. When the center temperature drop rate slows down and the slowdown exceeds the pre-stored rate change threshold, the modulation interval of the next modulation cycle is shortened and the instantaneous increase in flow rate is increased. When the center temperature drop rate does not slow down or the slowdown does not exceed the pre-stored rate change threshold, the modulation interval and flow rate of the previous modulation cycle are kept unchanged. The reduction in modulation interval duration is calculated based on the reduction in the rate of decrease of the center temperature, according to a pre-stored ratio; the increase in flow rate amplitude is calculated based on the reduction in the rate of decrease of the center temperature, according to a pre-stored ratio.

3. The intelligent temperature control system for storing quick-frozen health-promoting polypeptide foods according to claim 1, characterized in that, In the delayed acquisition module, the specific process of detecting the inflection point of the first temperature rise at the detection center is as follows: Starting from the pulse modulation moment, a series of consecutive sampling points from the center temperature time series are extracted to form an observation window. The first-order difference sequence of the center temperature values ​​within the observation window is calculated. In the first-order difference sequence, the first position where the negative value turns into a positive value and the two consecutive difference values ​​following it are both positive is searched in chronological order. The sampling moment corresponding to the position is marked as the turning point. If no difference sequence position matching the transition from negative to positive and the subsequent two consecutive positive difference values ​​is found within the observation window, then the sampling time corresponding to the lowest center temperature within the observation window is marked as the turning point.

4. The intelligent temperature control system for storing quick-frozen health-promoting polypeptide foods according to claim 1, characterized in that, In the amplification comparison module, the specific process for calculating the amplification of the delay time relative to the reference value is as follows: The temperature response delay time of the initial modulation is used to calculate the baseline value, and the standard deviation of the temperature response delay time of the initial modulation is also calculated. The standard deviation is multiplied by the pre-stored expansion coefficient to obtain the fluctuation tolerance range. For each subsequent modulation, the difference between the temperature response delay time of the current modulation and the baseline value is calculated. The difference is divided by the fluctuation tolerance range to obtain the standardized increase. The standardized increase is compared with the pre-stored increase criterion.

5. The intelligent temperature control system for storing quick-frozen health-promoting polypeptide foods according to claim 4, characterized in that, In the growth rate comparison module, the specific process of comparing the growth rate with the pre-stored growth rate criteria one by one is as follows: Multiple groups of peptide standard samples with known molecular weight distribution ranges were prepared. A pulse-modulated cooling process was performed on each group of standard samples, and the temperature response delay time and the corresponding food center temperature value were recorded for each modulation cycle. A joint distribution curve of the increase in temperature response delay time as the first coordinate axis and the food center temperature value as the second coordinate axis was plotted. On the joint distribution curve, the boundary position where the increase in temperature response delay time begins to leave the initial aggregation value range and the corresponding food center temperature value enters the pre-stored glass transition reference temperature range was determined. The increase value at the boundary position and the food center temperature value were recorded together as a joint criterion and stored in accordance with the molecular weight distribution range. The increase value of the current time was compared with the increase value in the joint criterion.

6. The intelligent temperature control system for storing quick-frozen health-promoting polypeptide foods according to claim 1, characterized in that, In the cryogenic switching module, the specific process for determining whether the food's core temperature has entered the glass transition stage is as follows: When the increase of several consecutive modulations exceeds the pre-stored increase criterion, the current food center temperature value is simultaneously collected, and the cooling rate of the food center temperature value within the preset backtracking time is calculated. The calculated cooling rate is compared with the pre-stored critical cooling rate for glass transition. When the cooling rate is lower than the pre-stored critical cooling rate for glass transition, it is determined that the food center temperature has entered the glass transition stage. When the cooling rate is not lower than the pre-stored critical cooling rate for glass transition, it is not determined that the food has entered the glass transition stage, and subsequent pulse modulation is continued, and the increase comparison and cooling rate comparison are repeated.

7. The intelligent temperature control system for storing quick-frozen health-promoting polypeptide foods according to claim 6, characterized in that, In the cryogenic switching module, the specific process of switching the refrigerant flow rate from the initial operating flow rate value to the cryogenic flow rate value is as follows: When it is determined that the food's core temperature has entered the glass transition stage, the food's core temperature value at the determination time is recorded. The remaining temperature difference is obtained by subtracting the food's core temperature value at the determination time from the pre-stored lower limit of the glassy storage temperature range. The remaining temperature difference is divided by the pre-stored allowable deep cryogenic cooling duration to obtain the required cooling rate. The refrigerant flow rate value corresponding to the required cooling rate is retrieved based on the pre-stored correspondence between the cooling rate and the refrigerant flow rate. The refrigerant flow rate is then switched from the initial operating flow rate value to the retrieved refrigerant flow rate value.

8. The intelligent temperature control system for storing quick-frozen health-promoting polypeptide foods according to claim 1, characterized in that, In the constant temperature maintenance module, the specific process of switching the refrigerant flow rate from the cryogenic flow rate value to the maintenance flow rate value is as follows: After switching to maintain the flow rate, the air temperature value is continuously collected and the slope of the air temperature value change trend within the preset time window is calculated. The value of the fine-tuning step is calculated according to the absolute value of the slope of the change trend in a linear relationship. When the slope of the trend is positive and the air temperature has not exceeded the upper limit of the glassy storage temperature range, the refrigerant flow rate is increased by the calculated fine-tuning step. When the slope of the trend is negative and the air temperature has not fallen below the lower limit of the glassy storage temperature range, the refrigerant flow rate is decreased by the calculated fine-tuning step.

Images