Juice added yogurt production system and method

Abstract

The present application relates to dairy deep processing and fruit yogurt preparation technical field, especially in kind of fruit juice added yogurt production system and method. The system is connected through pipeline between the deployment tank and the high shear tank to form a large circulation loop; the fruit juice pH adjusting assembly is connected with the high shear tank, and is used for adjusting the pH of the fruit juice to be added; the constant temperature control assembly is arranged on the deployment tank and / or the high shear tank, and is arranged on the feeding pipeline between the deployment tank and the high shear tank, so that the temperature of the circulating material in the tank is maintained in the constant temperature interval; the flow proportional feeding assembly is arranged on the feeding pipeline and the pipeline between the fruit juice pH adjusting assembly and the high shear tank, so as to dynamically match the flow of the fruit juice according to the real-time flow of the milk; the liquid level closed loop adjusting assembly is arranged on the high shear tank and the reflux pipeline between the high shear tank and the deployment tank. The present application can solve the problems of the existing technology, such as the easy occurrence of plate sterilization paste plate scaling, and the difficulty in stable control of product quality consistency.

Description

Technical Field

[0001] This invention relates to the field of dairy product deep processing and fruit-flavored yogurt preparation technology, and in particular to a fruit juice-added yogurt production system and method. Background Technology

[0002] Fruit juice-based yogurt combines the nutrition of milk with the flavor of fruit, making it an important category in the deep processing of dairy products. Currently, domestic industrial production generally employs a standardized process of fruit juice blending, pH adjustment, homogenization, and plate sterilization, with plate sterilization equipment mostly using fixed process parameters of 95℃ and 300 seconds. However, as consumers increasingly demand freshness and consistent quality, the existing production processes are showing shortcomings in terms of refined control, hindering industrial upgrading and large-scale, efficient production.

[0003] Existing fruit juice yogurt production lines typically employ a dual-tank circulating material system consisting of a high-shear tank and a mixing tank. The entire batch of milk continuously circulates and replaces between the two tanks to complete the addition and mixing of fruit juice. The pH adjustment of the fruit juice is achieved by manually adding a regulator. The temperature of the milk during the circulation process changes naturally with the environment and equipment operating conditions. Fruit juice is usually added to the tanks using a fixed-flow direct injection method, and the liquid level in the high-shear tank relies on natural equilibrium between the inlet and outlet. After homogenization, the mixed material is sent to a plate sterilizer for heat treatment, followed by fermentation, filling, and other processes to obtain the finished product.

[0004] In actual production, the above process suffers from significant temperature fluctuations in milk and a tendency for the pH of fruit juice to shift. Furthermore, the matching between the feed flow rate and the circulation flow rate is generally poor, leading to instability in the material system before sterilization. This unstable material, upon entering the 95℃ plate sterilization section, easily forms scale on the heat exchange plates, limiting continuous production time, requiring frequent cleaning, and impacting operational efficiency and energy consumption. Simultaneously, fluctuations in circulation conditions can easily cause the loss of flavor compounds in the fruit juice, resulting in differences in taste, aroma, and physicochemical properties between different batches of product, making it difficult to consistently control product quality. Summary of the Invention

[0005] This invention provides a juice-added yogurt production system and method to solve the problems of scaling on plate sterilization plates and the difficulty in controlling product quality consistency caused by fluctuations in the circulating operating conditions in the prior art.

[0006] In a first aspect, embodiments of the present invention provide a juice-added yogurt production system, comprising: a mixing tank, a high-shear tank, a juice pH adjustment component, a constant temperature control component, a flow rate proportioning component, and a liquid level closed-loop adjustment component; The mixing tank and the high-shear tank are connected by a pipeline to form a large circulation loop for material circulation and replacement. The juice pH adjustment component is connected to the high-shear tank and is used to adjust the pH of the juice to be added and to deliver the target juice with a stable pH value within a preset range into the high-shear tank. The constant temperature control component is installed on the mixing tank and / or the high shear tank, and on the feed pipeline between the mixing tank and the high shear tank, for maintaining the temperature of the circulating material in the tank within a set constant temperature range. The flow rate proportioning feeding component is installed on the feed pipeline between the mixing tank and the high shear tank, and on the pipeline between the juice pH adjustment component and the high shear tank. It is used to dynamically match the flow rate of the target juice according to the real-time flow rate of milk in the large circulation loop, so that the amount of target juice added and the amount of milk fed always maintain a preset ratio. The liquid level closed-loop regulating component is installed on the high-shear tank and on the return pipeline between the high-shear tank and the mixing tank, and is used to regulate the return flow rate from the high-shear tank to the mixing tank so that the liquid level in the high-shear tank is maintained at a set value.

[0007] In a second aspect, embodiments of the present invention provide a method for producing fruit juice-added yogurt, employing the fruit juice-added yogurt production system described in the first aspect above. The method for producing fruit juice-added yogurt includes: S1. The pH of the juice to be added is adjusted by the juice pH adjustment component to stabilize the pH value of the juice within the preset range, thereby obtaining the target juice with stable pH. S2. Add milk into the mixing tank and the high-shear tank respectively, start the large circulation loop to circulate and replace milk between the mixing tank and the high-shear tank; start the constant temperature control component to maintain the milk temperature in the large circulation loop within the set constant temperature range. S3. During the operation of the large circulation loop, the instantaneous flow rate of milk in the large circulation loop is obtained in real time through the flow ratio feeding component. Based on the instantaneous flow rate and the preset ratio of juice to milk, the flow rate of the target juice is dynamically adjusted so that the amount of target juice added and the instantaneous flow rate of milk are kept in a constant ratio. S4. During the operation of the large circulation loop, the liquid level in the high shear tank is detected in real time by the liquid level closed-loop adjustment component, and the return flow rate from the high shear tank to the mixing tank is adjusted according to the deviation between the liquid level detection value and the set value, so that the liquid level in the high shear tank is maintained at the set value. Steps S2, S3, and S4 overlap at least partially in time, together forming a steady-state cyclic mixing process until a uniformly mixed yogurt base is obtained.

[0008] This invention provides a fruit juice-added yogurt production system and method. Through a large circulation loop formed between the mixing tank and the high-shear tank, and with the synergistic effect of a fruit juice pH adjustment component, a constant temperature control component, a flow rate proportioning component, and a liquid level closed-loop regulation component, a multi-dimensional, stable, and controllable circulating mixing environment is constructed. Compared to existing technologies, in terms of preventing scorching, this invention implements ultra-narrow-range closed-loop precise control of the fruit juice through the fruit juice pH adjustment component, eliminating the instability of milk proteins caused by large fluctuations in pH from the source; the constant temperature control component maintains the milk temperature in the large circulation loop at the optimal anti-flocculation temperature range, ensuring stable casein spatial conformation and significantly enhancing resistance to acid and alkali shocks; the flow rate proportioning component achieves real-time dynamic ratio matching between the fruit juice flow rate and the milk feed flow rate, completely eliminating localized fruit juice concentration accumulation and acid-alkali shocks caused by traditional fixed-flow-rate feeding methods; and the liquid level closed-loop regulation component maintains a constant working liquid level in the high-shear tank, ensuring continuous stability of the shearing conditions. The four components work together to ensure that the material system remains highly stable before entering the plate sterilization section, eliminating the generation of micro-coagulation nuclei at the source. This effectively solves the long-standing technical problem of scale buildup in plate sterilization, significantly extends the continuous operation time of the production line, and significantly reduces the frequency of equipment cleaning and overall production costs.

[0009] In terms of flavor preservation and quality improvement, this invention utilizes a constant temperature control component to provide a gentle, constant-temperature mixing environment, and a flow-ratio feeding component to achieve gentle and uniform feeding. This avoids the localized excessive physicochemical reactions caused by traditional high-temperature fluctuations and direct-flow feeding, maximizing the protection of the core volatile aroma components in the juice and effectively improving the retention rate of flavor substances. The finished product has a pure and rich fruit aroma and is free of cooking odors. Simultaneously, through the aforementioned multi-dimensional steady-state synergistic control, the physicochemical indicators of products are highly consistent across different production batches, significantly improving batch quality consistency and core market competitiveness. Furthermore, this invention relies entirely on existing dual-tank large-circulation production lines and fixed-plate sterilization processes. No new equipment, pipeline modifications, or sterilization parameter adjustments are required. The aforementioned technical effects can be achieved simply by adding and synergistically optimizing front-end process components. It has low industrialization difficulty, wide applicability, and extremely low modification costs, demonstrating excellent industrial application prospects. Attached Figure Description

[0010] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0011] Figure 1 This is a schematic diagram of a fruit juice-added yogurt production system provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of a fruit juice-added yogurt production system provided in another embodiment of the present invention; Figure 3 This is a flowchart illustrating the implementation of the fruit juice-added yogurt production method provided in this embodiment of the invention. Detailed Implementation

[0012] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0013] See Figure 1 The diagram illustrates a fruit juice-added yogurt production system according to an embodiment of the present invention, which is described in detail below: A juice-added yogurt production system includes: a mixing tank 1, a high-shear tank 2, a juice pH adjustment component 3, a constant temperature control component 4, a flow rate proportioning component 5, and a liquid level closed-loop adjustment component 6. The mixing tank 1 and the high shear tank 2 are connected by pipelines to form a large circulation loop for material circulation and replacement; The juice pH adjustment component 3 is connected to the high-shear tank 2 and is used to adjust the pH of the juice to be added and to deliver the target juice with a stable pH value within a preset range into the high-shear tank 2. The constant temperature control component 4 is installed on the mixing tank 1 and / or the high shear tank 2, and on the feed pipeline between the mixing tank 1 and the high shear tank 2, to maintain the temperature of the circulating material in the tank within the set constant temperature range. The flow rate proportioning feeding component 5 is installed on the feed pipeline between the mixing tank 1 and the high shear tank 2, and on the pipeline between the juice pH adjustment component 3 and the high shear tank 2. It is used to dynamically match the flow rate of the target juice according to the real-time flow rate of milk in the large circulation loop, so that the amount of target juice added and the amount of milk fed always maintain a preset ratio. The liquid level closed-loop regulating component 6 is installed on the high shear tank 2 and on the return pipeline between the high shear tank 2 and the mixing tank 1. It is used to regulate the return flow rate from the high shear tank 2 to the mixing tank 1 so that the liquid level in the high shear tank 2 is maintained at the set value.

[0014] In existing technologies, the acid-base adjustment of fruit juice is achieved by manually adding regulators, which easily leads to deviations in the juice's pH value and makes it difficult to obtain a stable pH value. In this embodiment, relying on the existing dual-tank large-circulation production system of high-shear tanks and mixing tanks, an innovative ultra-narrow closed-loop pH control technology for fruit juice is introduced. This abandons the traditional manual, experience-based, and extensive acid adjustment method. A closed-loop feedback control system is built through a fruit juice pH adjustment component, dynamically adjusting the regulator injection flow rate based on the real-time pH value of the fruit juice, strictly controlling the pH fluctuation deviation within ±0.05. Only after the pH parameter of the fruit juice is completely stable and meets the standard can it proceed to the subsequent mixing process. This achieves precise and controllable fruit juice properties from the source, avoids the instability and flocculation problems of milk protein caused by acid-base fluctuations, and completely eliminates the hidden dangers of material system instability caused by acid-base fluctuations.

[0015] In one embodiment, such as Figure 2 As shown, the juice pH adjustment component 3 includes: a juice tank 31, an online pH meter 32, and a variable frequency micro-metering pump 33; The juice container 31 contains the juice to be added; the juice to be added can be various edible juices, including but not limited to blueberry juice, strawberry juice, mango juice, peach juice, lemon juice, jujube juice, etc.

[0016] An online pH meter 32 is installed inside the juice tank 31 or on the discharge pipe of the juice tank 31 to detect the pH value of the juice to be added in real time; such as Figure 2 In the middle, the online pH meter 32 is installed inside the juice tank 31.

[0017] A variable frequency micro-metering pump 33 is used to quantitatively add pH adjuster to the juice tank 31. The pH adjuster is selected from food-grade sodium citrate and / or baking soda solution.

[0018] The variable frequency micro-metering pump 33 is connected to the PLC controller, which is also connected to the online pH meter 32. The PLC controller is used to receive the pH value of the juice to be added from the online pH meter 32, and according to the deviation between the pH value of the juice to be added and the preset pH target value, it controls the variable frequency micro-metering pump 33 to add pH adjuster quantitatively into the juice tank 31 until the fluctuation deviation of the pH value of the juice to be added is controlled within the preset range.

[0019] It should be noted that, because the PLC controller needs to connect to many devices, Figure 2 The PLC controller is not labeled.

[0020] The process of adjusting the pH of the juice to be added using the juice pH adjustment component 3 is as follows: An online pH meter 32 monitors the pH value of the fruit juice in real time and transmits it to a PLC controller. The PLC controller compares the measured value with a preset target value. When the deviation between the measured value and the target value is large, the PLC controller increases the output frequency of the variable frequency micro-metering pump 33, which continuously delivers the pH adjuster at the first target frequency after the increase in output frequency for 10 seconds. When the deviation between the measured value and the target value is small, the output frequency of the variable frequency micro-metering pump 33 is decreased, and it continuously delivers the adjuster at the second target frequency after the decrease in output frequency for 5 seconds.

[0021] After a single pH adjuster addition is completed, the system enters a 2-minute intermittent stirring phase to ensure the adjuster is fully diffused and mixed in the juice. After the intermittent stirring ends, the online pH meter 32 re-detects the pH of the material, and the above comparison, graded addition, and intermittent settling process is repeated until the juice pH reaches the preset target value and the fluctuation deviation is controlled within ±0.05. At this point, the system stops adding the pH adjuster.

[0022] By employing a closed-loop control method combining online real-time pH sampling with dynamic feeding via a variable frequency micro-metering pump 33, ultra-narrow pH steady-state control of the fruit juice is achieved. This ensures precise and controllable control of the fruit juice's physical properties from the source, effectively avoiding issues such as milk protein instability and flocculation caused by fluctuations in the fruit juice's acid-base balance. The fruit juice, after completing the pH stabilization pretreatment, is used as the target fruit juice and then transported to the high-shear tank 2 for subsequent mixing operations.

[0023] Existing fruit juice yogurt production lines generally adopt a dual-tank large-circulation material mixing mode consisting of a high-shear tank (2) and a mixing tank (1). However, traditional processes do not actively control the mixing temperature. During the dual-tank circulation process, milk is easily affected by external factors such as ambient temperature, equipment heat exchange efficiency, and circulation operating conditions, resulting in large fluctuations in mixing temperature, typically ranging from 15 to 28°C. Since casein in milk is highly sensitive to temperature changes, increased temperature lowers the protein denaturation threshold, significantly weakening the stability of the casein conformation. When acidic or alkaline components of fruit juice are introduced, it easily triggers conformational changes in casein, causing aggregation and precipitation, generating a large number of fine suspended nuclei. When the unstable material containing these fine nuclei enters the 95°C, 300s fixed-plate sterilization section, the nuclei are rapidly heated, adhere to the surface of the heat exchange plates, and accumulate and coke, ultimately leading to scaling and clogging of the heat exchange plates. This forces frequent production line shutdowns for Clean In Place (CIP) cleaning, severely restricting continuous production capacity. Meanwhile, significant fluctuations in mixing temperature are also a major reason for the accelerated loss of volatile flavor compounds in fruit juice and significant batch-to-batch quality differences. Therefore, precise and stable closed-loop control of the mixing temperature in the dual-tank large-circulation system is urgently needed.

[0024] To address the aforementioned technical deficiencies, in one embodiment, as follows: Figure 2As shown, the constant temperature control component 4 includes: a temperature sensor 41, a heat exchanger 42, and a proportional regulating valve 43 installed on the heat exchange medium pipeline of the heat exchanger 42. Temperature sensor 41 is installed on mixing tank 1 and / or high shear tank 2 to detect the temperature of materials inside mixing tank 1 and / or high shear tank 2 in real time; Figure 2 Temperature sensors 41 are installed on the high-shear tank 2, and temperature sensors 41 can also be installed on the mixing tank 1 to detect the mixing temperature of the materials in the mixing tank 1 and / or the high-shear tank 2 in real time. It should be noted that the number of temperature sensors 41 is not limited here, and multiple sensors can be set according to the needs in order to detect the temperature of the materials in the mixing tank 1 and / or the high-shear tank 2 more accurately. Heat exchanger 42 is installed on the feed pipeline between mixing tank 1 and high shear tank 2, and is used to regulate the temperature of the material in the feed pipeline; optionally, heat exchanger 42 is a plate heat exchanger, and the heat exchange medium includes at least one of tower water, ice water and steam. Proportional regulating valves 43 are respectively installed on the corresponding pipelines of tower water, ice water or steam in heat exchanger 42.

[0025] like Figure 2 As shown, a first proportional regulating valve 431 is provided on the pipeline of tower water entering the heat exchanger 42, a second proportional regulating valve 432 is provided on the pipeline of tower water exiting the heat exchanger 42, a third proportional regulating valve 433 is provided on the pipeline of chilled water entering the heat exchanger 42, a fourth proportional regulating valve 434 is provided on the pipeline of chilled water exiting the heat exchanger 42, and a fifth proportional regulating valve 435 is provided on the steam pipeline.

[0026] Temperature sensor 41 and proportional control valve 43 are respectively connected to PLC controller. PLC controller is used to receive material temperature sent by temperature sensor 41, and according to the deviation of material temperature from preset constant temperature range, control the opening of proportional control valve 43 to adjust the heat exchange medium flow rate of heat exchanger 42, so that the material temperature in tank is maintained within the set constant temperature range.

[0027] The aforementioned constant temperature control component 4, together with the mixing tank 1, the high-shear tank 2, and the large circulation loop, constitutes a closed-loop control system for milk temperature. The system's preset constant temperature control range is 18℃~22℃. Temperature sensor 41 collects the temperature of the milk mixture in the tank in real time throughout the process and feeds it back to the programmable logic controller (PLC). When the measured temperature is higher than 22℃, the PLC controller controls the corresponding proportional regulating valve 43 on the tower water pipeline and the chilled water pipeline to increase the opening degree, so as to increase the flow rate of the cold medium into the heat exchanger 42, thereby cooling the circulating material through the heat exchanger 42. When the measured temperature is lower than 18℃, the PLC controller switches and increases the valve opening degree of the proportional regulating valve 43 on the steam pipeline, so as to increase the flow rate of the hot medium into the heat exchanger 42, thereby heating the material. When the temperature is within the range of 18℃ to 22℃, the valves of each proportional regulating valve 43 maintain a slight opening to dynamically compensate for the natural heat loss and accumulation during the production process. This ensures that the temperature of the milk mixture in the tank remains constant within the optimal constant temperature range of 18℃ to 22℃ throughout the entire process of preparation, mixing, and shearing homogenization. This optimal constant temperature range is the optimal anti-flocculation temperature range for fruit juice mixtures, verified through extensive industrial testing. Within this optimal constant temperature range, the spatial conformation of milk casein is stable, its acid and alkali tolerance is excellent, and its resistance to mechanical shear disturbance is strong. This can maximize the structural stability of milk protein and effectively inhibit protein denaturation, micro-flocculation, and subsequent plate pasteurization problems caused by temperature fluctuations from the source. At the same time, the mild constant temperature environment is also conducive to protecting the core volatile aroma components such as esters and aldehydes in the fruit juice, maximizing the preservation of the natural flavor of the fruit juice. Relying on the dual-tank large-circulation material flow and the aforementioned real-time closed-loop temperature control mechanism, the material temperature inside the tank can be constantly controlled within the optimal constant temperature range of 18℃ to 22℃, regardless of changes in the external ambient temperature and equipment operating conditions. This provides a stable and reliable thermodynamic basis for subsequent juice addition and homogenization, significantly improving batch consistency of product quality.

[0028] In the traditional dual-tank large-circulation process of existing fruit juice yogurt production lines, fruit juice is generally added using a fixed-flow-rate direct injection method, where the feeding pump continuously injects fruit juice into the high-shear tank at a constant speed. However, during actual operation of the large circulation system, the instantaneous flow rate of milk added from mixing tank 1 to high-shear tank 2 is not constant but fluctuates continuously due to various factors such as changes in material viscosity, pumping efficiency fluctuations, differences in pipeline resistance, and liquid level changes. The fixed-flow-rate feeding method cannot dynamically match the real-time milk flow rate of the large circulation system. When the milk flow rate decreases, fixed-flow-rate feeding will result in an excessively high relative proportion of fruit juice, causing localized accumulation of fruit juice concentration and sudden changes in pH levels. Conversely, when the milk flow rate increases, fixed-flow-rate feeding will result in an insufficient relative proportion of fruit juice, causing the overall batch material ratio to deviate from the preset standard. This instantaneous imbalance not only triggers localized acid-base shocks, damaging milk protein stability and exacerbating micro-flocculation, but also causes inconsistencies in material composition at different times within the same batch, ultimately leading to significant batch-to-batch quality differences. Meanwhile, the traditional direct-flow feeding method causes the juice to enter the high-shear tank in a concentrated jet form. Near the impact point, the juice concentration is extremely high and the pH value drops sharply, while areas far from the impact point have a lower juice concentration, resulting in a highly uneven material system. This drastic local concentration difference and acid-base impact easily damage the core volatile aroma components in the juice, such as esters and aldehydes, leading to a weak fruity aroma and distorted flavor in the finished product. Therefore, there is an urgent need to develop a juice addition method that can dynamically match the real-time milk flow rate and achieve gentle and uniform feeding.

[0029] To address the aforementioned technical deficiencies, in one embodiment, as follows: Figure 2As shown, the flow rate proportioning feeding component 5 includes: a milk conveying unit 51, a juice conveying unit 52, and an atomizing nozzle 53; The milk conveying unit 51 is installed on the feed pipeline between the mixing tank 1 and the high-shear tank 2, and is used to detect the instantaneous flow rate of fresh milk fed into the high-shear tank 2 from the mixing tank 1 in real time; The juice delivery unit 52 is installed on the pipeline between the juice pH adjustment component 3 and the high shear tank 2, and is used to pump the target juice to the atomizing nozzle 53; the target juice is the juice whose pH value is stable within a preset range after pH closed-loop regulation. The discharge end of the atomizing nozzle 53 is connected to the high-shear tank 2 and is used to spray the target juice into the circulating material in the high-shear tank 2 in an atomized form.

[0030] Optionally, Figure 2 In the process, the milk conveying unit 51 may include: a milk conveying centrifugal pump 511 and a first flow meter 512; the juice conveying unit 52 may include: a juice conveying rotor pump 521 and a second flow meter 522. A milk conveying centrifugal pump 511 and a first flow meter 512 are installed on the feed pipeline between the mixing tank 1 and the high shear tank 2. The milk conveying centrifugal pump 511 is used to pump the milk in the mixing tank 1 to the high shear tank 2 to maintain a stable feed in the large circulation loop. The first flow meter 512 is connected to the PLC controller and is used to detect the instantaneous flow rate of the milk in real time and transmit the instantaneous flow rate of the milk to the PLC controller. Optionally, the atomizing nozzle 53 is disposed on the top or side of the high-shear tank 2, and the spray direction of the atomizing nozzle is toward the material liquid surface or the circulating material flow area inside the high-shear tank 2.

[0031] The juice delivery rotor pump 521 and the second flow meter 522 are installed on the pipeline between the juice pH adjustment component 3 and the high shear tank 2. The juice delivery rotor pump 521 is used to pump the target juice after pH adjustment to the atomizing nozzle 53. The second flow meter 522 is connected to the PLC controller and is used to detect the actual flow rate of the juice in real time and transmit the actual flow rate of the target juice to the PLC controller.

[0032] The aforementioned flow ratio feeding component 5, together with the PLC controller, constitutes a flow ratio follow-up atomizing feeding system. The first flow meter 512, the second flow meter 522, and the juice conveying rotor pump 521 are respectively connected to the PLC controller. After receiving the instantaneous milk flow signal sent by the first flow meter 512, the PLC controller calculates the target juice flow rate according to the preset juice to milk production ratio. The PLC controller also compares the actual target juice flow rate fed back by the second flow meter 522 with the target juice flow rate, and dynamically adjusts the operating frequency of the juice conveying rotor pump 521 according to the comparison deviation, so that the actual target juice flow rate matches the target juice flow rate in real time, and achieves a constant ratio between the juice flow rate and the milk feed flow rate.

[0033] The core control logic is as follows: using the instantaneous flow rate of milk added to the high-shear tank 2 from the mixing tank 1, which is collected in real time by the first flow meter 512, as a reference signal, the PLC controller collects the instantaneous flow rate data of milk in real time at high speed. Combined with the preset juice and milk production ratio, the target juice flow rate is dynamically calculated and determined. For example, when the instantaneous milk flow rate is 20,000 L / hour and the juice addition ratio is 2%, the calculated target juice flow rate is 408 L / hour. The PLC controller uses the calculated target juice flow rate as the control target and compares it with the actual flow rate of the target juice fed back in real time by the second flow meter 522. Based on the flow deviation, the operating frequency of the juice conveying rotor pump 521 is dynamically adjusted: when the actual flow rate of the target juice is lower than the target juice flow rate, the pump frequency is increased; when the actual flow rate of the target juice is higher than the target juice flow rate, the pump frequency is decreased. This adjustment is iterated repeatedly until the actual flow rate of the target juice matches the target juice flow rate. The PLC controller continuously monitors and adjusts the frequency. When the milk feed flow rate changes, the target juice flow rate is updated synchronously, and the frequency of the juice conveying rotor pump 521 is adjusted accordingly to ensure that the target juice addition amount and the milk feed amount are always kept in a fixed ratio.

[0034] The target fruit juice, after precise pH adjustment, is uniformly sprayed into the large-circulation material system within the high-shear tank 2 in the form of fine droplets through atomizing nozzle 53 under a constant milk temperature of 18℃~22℃. The fine droplet morphology has a large specific surface area, allowing the target fruit juice and circulating milk to achieve gentle and uniform initial mixing instantly, without localized concentration accumulation or instantaneous acid-base shocks. Combined with the continuous driving of the dual-tank large-circulation shear homogenization by the milk transfer centrifugal pump 511, the target fruit juice and milk are gently, uniformly, and fully integrated, rapidly producing a yogurt base material with uniform physical properties, no stratification, no micro-coagulation nuclei, and a highly stable system.

[0035] The aforementioned flow-ratio-driven atomized feeding method eliminates the inherent defects of the traditional fixed-flow-rate direct-pump feeding mode. Using the real-time detection of the feed milk flow rate by the first flow meter 512 as a benchmark, and the real-time feedback of the actual flow rate of the target fruit juice by the second flow meter 522, a closed-loop dynamic proportioning control is formed. This completely solves the industry-wide problems of instantaneous proportioning imbalance, localized fruit juice enrichment, and localized acid-base shocks inherent in traditional processes. Simultaneously, the atomized spray feeding method avoids the localized excessive physicochemical reactions caused by the direct-pumping of liquid streams in traditional methods, greatly protecting the core volatile aroma components such as esters and aldehydes in the fruit juice. Industrial parallel control tests have verified that using the flow-ratio-driven atomized feeding process of this invention, the retention rate of volatile aroma substances in the fruit juice can reach over 92%, which is significantly higher than the 70%–75% retention rate of traditional extensive processes and the 78%–82% retention rate of conventional dual-tank processes, effectively reducing flavor loss by approximately 20%. The product batch pH fluctuation is ≤±0.05, and the coefficient of variation for material uniformity is ≤3.0%, far superior to the levels of traditional processes.

[0036] In the traditional dual-tank large-circulation process of existing fruit juice yogurt production lines, the liquid level of the high-shear tank 2 is regulated by a natural feed-discharge balance method. That is, the feed rate of the high-shear tank 2 depends on the pumping capacity of the mixing tank 1, and the discharge rate depends on the conveying needs of downstream equipment. The liquid level is entirely maintained by the natural matching of feed and discharge. However, during actual operation of the large-circulation process, the feed flow rate from the mixing tank 1 to the high-shear tank 2 fluctuates continuously due to factors such as changes in material viscosity, fluctuations in pumping efficiency, and differences in pipeline resistance. The discharge flow rate from the high-shear tank 2 to downstream equipment also changes in real time due to changes in the operating conditions of subsequent homogenization and sterilization processes. This dynamic imbalance between the feed and discharge flow rates directly causes the liquid level in the high-shear tank 2 to fluctuate continuously, making it impossible to stabilize at the set working level. Fluctuations in liquid level trigger a series of chain reactions: when the liquid level is too low, the shear head of the high-shear motor cannot be fully submerged in the material, significantly weakening or even eliminating the shearing action, resulting in a marked decrease in material homogenization; when the liquid level is too high, the residence time of the material in the tank is prolonged, and some material is over-sheared, also affecting the homogeneity of the material system. More seriously, disorderly fluctuations in liquid level keep the material flow rate and shear intensity in the large circulation system unstable, increasing the probability of milk protein micro-flocculation and causing significant differences in material homogenization, acid-base distribution uniformity, and flavor integration between different production batches. In addition, liquid level fluctuations also cause changes in the flow rate back to blending tank 1, thereby disturbing the operational stability of the entire large circulation loop, causing disorderly fluctuations in multiple dimensions of production parameters such as temperature, flow rate, liquid level, and shear intensity, ultimately leading to product stratification, large flavor fluctuations, and poor batch quality consistency. Therefore, it is urgent to implement precise and stable closed-loop control of the liquid level in high-shear tank 2 to ensure the continuous stability of the large circulation operation.

[0037] To address the aforementioned technical deficiencies, in one embodiment, as follows: Figure 2 As shown, the liquid level closed-loop control component 6 includes: a liquid level detection unit 61 and a variable frequency reflux pump 62; The liquid level detection unit 61 is installed on the high-shear tank 2 and is used to detect the liquid level in the high-shear tank 2 in real time. The variable frequency reflux pump 62 is installed on the reflux pipeline between the high shear tank 2 and the mixing tank 1, and is used to pump the material in the high shear tank 2 back to the mixing tank 1 to adjust the discharge flow rate of the high shear tank 2. The liquid level detection unit 61 and the variable frequency reflux pump 62 are respectively connected to the PLC controller. The PLC controller is used to receive the liquid level in the high shear tank 2 sent by the liquid level detection unit 61, and control the operating frequency of the variable frequency reflux pump 62 according to the deviation between the liquid level in the high shear tank 2 and the set value, so as to adjust the reflux flow rate from the high shear tank 2 to the mixing tank 1 and maintain the liquid level in the high shear tank 2 at the set value.

[0038] In one embodiment, the liquid level detection unit 61 can be a weighing sensor or a liquid level gauge; like Figure 2 As shown, the weighing sensor can be installed on the support structure of the high shear tank 2, and the liquid level can be calculated by detecting the change in the weight of the tank.

[0039] The level gauge is installed on the side wall or top of the high-shear tank 2.

[0040] In one embodiment, the variable frequency reflux pump can be a centrifugal pump.

[0041] The aforementioned liquid level closed-loop regulation component 6, together with the PLC controller, constitutes a high-shear tank liquid level variable frequency closed-loop pressure stabilization control system. Its core control logic is as follows: the system presets the target working liquid level of the high-shear tank 2. During production, the liquid level detection unit 61 collects the liquid level signal within the high-shear tank 2 in real time and transmits it to the PLC controller. The PLC controller compares the measured liquid level value with the preset target value. When the measured liquid level is higher than the preset value, the PLC controller increases the output frequency of the variable frequency reflux pump 62, accelerating the reflux rate from the high-shear tank 2 to the distribution tank 1, increasing the reflux flow rate, and causing the liquid level in the tank to quickly drop to the set value. When the measured liquid level is lower than the preset value, the PLC controller decreases the output frequency of the variable frequency reflux pump 62, slowing down the reflux rate, reducing the reflux flow rate, and causing the liquid level in the tank to rise back to the set value. By continuously and dynamically adjusting the variable frequency reflux pump 62, the relationship between the milk feed flow rate, juice flow rate and reflux discharge flow rate is dynamically balanced in real time, so that the working liquid level of the high shear tank 2 remains constant throughout the process, ensuring that the high shear motor always operates stably at the optimal immersion depth, and that the shearing conditions are continuously stable and the material residence time is consistent.

[0042] It should be noted that the high-shear tank is equipped with a high-shear motor, which drives the shear head (or rotor) inside the high-shear tank to rotate, applying high-intensity mechanical shear force to the material inside the tank, so as to achieve rapid and uniform mixing and homogenization of the material (milk and target juice).

[0043] The aforementioned liquid level closed-loop regulation component 6, together with the constant temperature control component 4 and the flow ratio feeding component 5, forms a three-dimensional closed-loop collaborative control system of "constant temperature locking + variable frequency constant liquid level + flow ratio matching". The temperature sensor 41 continuously locks the milk mixing temperature within the optimal range of 18℃ to 22℃. The first flow meter 512 detects the feed milk flow rate in real time and dynamically matches the juice feeding rate. The liquid level detection unit 61 and the variable frequency reflux pump 62 work in real time to stabilize the working liquid level of the high-shear tank 2. The synergistic effect of these three components ensures unified and controllable operating parameters throughout the large-scale circulation process, guaranteeing constant and controllable temperature, liquid level, flow rate, and shear intensity throughout the mixing process. This three-dimensional closed-loop collaborative control system completely solves the inherent defects of traditional dual-tank large-scale circulation systems, such as large temperature fluctuations, large liquid level fluctuations, and disordered shear conditions. Precise and constant liquid level control ensures continuous and stable shearing action at the system level, eliminating uneven shearing and material residence time differences caused by liquid level fluctuations. This effectively reduces the probability of micro-flocculation of milk protein and ensures that the shearing history experienced by each batch of material is consistent, significantly improving batch-to-batch consistency of product quality and resulting in a highly stable yogurt base. Industrial parallel control tests have confirmed that after adopting the closed-loop liquid level and pressure stabilization control of this invention, the micro-flocculation rate of the material can be stably controlled within 1%, the product batch sensory score is ≥4 points, the batch pH fluctuation is ≤±0.05, and the material uniformity coefficient of variation is ≤3.0%. This completely overcomes the technical difficulties of disordered operating conditions and large product quality fluctuations caused by disordered liquid level fluctuations in traditional processes.

[0044] The homogenized yogurt base is directly fed into a plate sterilization machine, and sterilization is completed using the same sterilization parameters of 95°C and 300 seconds. Subsequent fermentation, filling, cooling and storage processes all follow the existing standardized production process.

[0045] The effectiveness of this scheme is illustrated below through comparative experiments.

[0046] Multiple parallel industrial-scale comparative tests were conducted under the same production line, the same 95℃ temperature, a fixed 300-second sterilization process, and the same raw and auxiliary materials. Comprehensive performance tests were performed on the traditional extensive process, the traditional dual-tank large-circulation process, and the proposed fruit juice-added yogurt production system. Specific test data and results are as follows: Experimental Group 1: Traditional extensive acidification process with no constant temperature control and fixed flow rate feeding. This process lacks closed-loop narrow-range pH control and a milk constant temperature locking mechanism, and the juice is fed directly at a fixed flow rate. During production, the pH fluctuation range of the juice is ±0.15 to ±0.20, and the temperature fluctuation range of the milk mixture is 15℃ to 28℃. The materials are affected by both acid-base shocks and temperature fluctuations, resulting in significant protein instability and a micro-flocculation rate as high as 8% to 12%. The production line shows obvious plate-like scaling after 2 to 3 hours of continuous production, requiring shutdown for CIP cleaning. The retention rate of volatile aroma substances in the juice is only 70% to 75%, the finished product has a weak fruity aroma and a slight cooking odor. The batch pH fluctuation is ±0.15, the flavor sensory batch score is ≤2 points, the coefficient of variation of material uniformity is ≥8.0%, and the overall production stability and product quality are poor.

[0047] Experimental Group 2: Traditional dual-tank large-circulation extensive process. This process adopts a large-circulation production mode using a high-shear tank and a mixing tank, without constant temperature control, flow ratio-based feeding, or frequency conversion constant liquid level control. Although the basic materials can be homogenized by relying on the dual-tank circulation, the production conditions fluctuate disorderly. The juice addition rate and milk flow rate cannot be dynamically matched. The liquid level in the high-shear tank fluctuates greatly, and the shearing conditions are chaotic. Local acid-base imbalance and concentration enrichment of the materials are prominent problems. The micro-flocculation rate of the materials is maintained at 5% to 7%. Plate-changing scaling occurs after 3 to 4 hours of continuous production. The retention rate of aroma substances in the juice is 78% to 82%, and the flavor of each batch fluctuates significantly. The pH of the product batch fluctuates by ±0.10, and the coefficient of variation of material uniformity is ≥6.0%. Serious defects such as smearing and flavor loss still exist.

[0048] Experimental Group 3: Precise and coordinated control process of this fruit juice-added yogurt production system. This process adopts a four-dimensional coordinated steady-state control technology, including fruit juice ±0.05 ultra-narrow closed-loop pH control, milk constant temperature locking at 18-22℃, milk flow rate ratio follow-up atomized feeding, and reflux pump frequency conversion constant liquid level. The experimental results show that this system can strictly control the pH fluctuation of fruit juice within ±0.05, maintain a constant milk mixing temperature throughout the process, and completely eliminate the protein instability caused by large fluctuations in temperature and pH; the micro-flocculation rate of the material is stably controlled within 1%, preventing the accumulation of micro-coagulation nuclei from the source; the production line can achieve continuous and stable production time of 8-10 hours, reducing the frequency of downtime cleaning by more than 70%, and reducing the overall production cost by 15%-20%; the retention rate of the core volatile aroma substances of fruit juice is increased to more than 92%; the pH fluctuation of product batches is ≤±0.05, the coefficient of variation of material uniformity is ≤3.0%, and the sensory batch score is ≥4 points, completely overcoming the industry technical bottlenecks of frequent smearing, flavor deterioration, and unstable batch quality in traditional processes.

[0049] In summary, the three sets of parallel industrial-scale control experiments demonstrate that this fruit juice-added yogurt production system is not a simple superposition of conventional parameters or a replacement of traditional processes. Rather, it addresses the inherent technical deficiencies of the dual-tank large-circulation production system for fruit juice yogurt by establishing an integrated, coupled new process system of "precise pH stabilization, constant temperature for stable protein, dynamic flow ratio, and constant liquid level for stable operating conditions." These technical features synergistically enhance each other, achieving multiple technical effects such as preventing batch burning and increasing production, preserving flavor and improving quality, and ensuring batch homogenization. Compared to existing technologies, this system possesses outstanding novelty, creativity, and industrial applicability.

[0050] This invention provides a fruit juice-added yogurt production system. Through a large circulation loop formed between the mixing tank and the high-shear tank, combined with the synergistic effects of a fruit juice pH adjustment component, a constant temperature control component, a flow rate proportioning component, and a liquid level closed-loop adjustment component, a multi-dimensional, stable, and controllable circulating mixing environment is constructed. Compared to existing technologies, this invention has the following advantages: Regarding anti-scalding, this invention employs a juice pH adjustment component to implement ultra-narrow closed-loop precise control of the juice, eliminating the root cause of milk protein instability caused by large fluctuations in pH. A constant temperature control component maintains the milk temperature in the large circulation loop within the optimal anti-flocculation temperature range, ensuring stable casein spatial conformation and significantly enhancing resistance to acid and alkali shocks. A flow ratio feeding component achieves real-time dynamic matching of juice flow rate and milk feed flow rate, completely eliminating localized juice concentration buildup and acid / alkali shocks caused by traditional fixed-flow-rate feeding methods. A liquid level closed-loop adjustment component maintains a constant working liquid level in the high-shear tank, ensuring continuous stability under shearing conditions. These four components work synergistically to maintain a highly stable material system before entering the plate sterilization section, preventing the formation of micro-coagulation nuclei at the source. This effectively solves the long-standing technical problem of scalding and scaling in plate sterilization, significantly extending the continuous operation time of the production line and significantly reducing equipment cleaning frequency and overall production costs.

[0051] In terms of flavor preservation and quality improvement, this invention utilizes a constant temperature control component to provide a gentle, constant-temperature mixing environment, and a flow-ratio feeding component to achieve gentle and uniform feeding via atomized spraying. This avoids the localized excessive physicochemical reactions caused by traditional high-temperature fluctuations and direct-pump feeding, maximizing the protection of the core volatile aroma components in the juice and effectively improving the retention rate of flavor substances. The finished product has a pure and rich fruit aroma and is free of cooking odors. Simultaneously, through the aforementioned multi-dimensional steady-state synergistic control, the physicochemical indicators of products are highly consistent across different production batches, significantly improving batch quality consistency and core market competitiveness. Furthermore, this invention relies entirely on existing dual-tank large-circulation production lines and fixed-plate sterilization processes, requiring no additional equipment, no pipeline modifications, and no adjustment of sterilization parameters. The aforementioned technical effects can be achieved simply by adding and synergistically optimizing front-end process components. It has low difficulty in industrial implementation, wide applicability, and extremely low modification costs, demonstrating excellent prospects for industrial application.

[0052] See Figure 3 This document illustrates a flowchart of a method for producing fruit juice-added yogurt according to an embodiment of the present invention. Using the fruit juice-added yogurt production system provided in any of the above embodiments, the system achieves stable production from the source by precisely controlling the pH of the fruit juice in a closed loop, ensuring stable milk preparation at a constant temperature, coordinating flow rate-ratio atomized mixing, and implementing variable frequency constant liquid level steady-state circulation. This stabilizes the fruit juice and milk mixture from the source, inhibits micro-flocculation of milk proteins, solves the problem of scaling and sticking on slab sterilizers, and maximizes the retention of the natural volatile flavor of the fruit juice. The detailed method for producing fruit juice-added yogurt is as follows: Step S1: The pH of the juice to be added is adjusted by the juice pH adjustment component to stabilize the pH value of the juice within a preset range, thereby obtaining a target juice with stable pH.

[0053] First, the pH of the various edible fruit juices to be added is adjusted in a closed loop using the fruit juice pH adjustment component. The fruit juices to be added include, but are not limited to, blueberry juice, strawberry juice, mango juice, peach juice, lemon juice, and jujube juice.

[0054] Specifically, the juice to be added is fed into the juice tank, and the online pH meter is activated to collect the pH data of the juice in real time and transmit it to the PLC controller. The PLC controller compares the measured pH value with the preset pH target value. When the measured value deviates significantly from the target value, the PLC controller increases the output frequency of the variable frequency micro-metering pump, which continuously delivers food-grade sodium citrate and / or baking soda solution into the juice tank at this frequency for 10 seconds. When the measured value deviates slightly from the target value, the output frequency of the variable frequency micro-metering pump is decreased, and the pump continuously delivers the regulator at this frequency for 5 seconds.

[0055] After a single addition operation is completed, the system enters a 2-minute intermittent stirring phase to ensure that the pH adjuster is fully diffused and mixed in the juice. After the intermittent stirring ends, the online pH meter measures the pH of the material again, and the above comparison, tiered addition, and intermittent settling process is repeated until the juice pH reaches the preset target value and the fluctuation deviation is controlled within ±0.05. At this point, the system stops adding the adjuster, and the target juice with a stable pH is obtained.

[0056] This step abandons the traditional, experience-based, and extensive acidification method. Instead, it uses a closed-loop control method that combines online real-time pH sampling with dynamic feeding via a variable frequency micro-metering pump to achieve ultra-narrow pH steady-state control of the juice. This ensures precise and controllable control of the juice's physical properties from the source, effectively avoiding problems such as milk protein instability and flocculation caused by fluctuations in the juice's acidity and alkalinity.

[0057] Step S2: Add milk into the mixing tank and the high-shear tank respectively, start the large circulation loop to circulate and replace milk between the mixing tank and the high-shear tank; start the constant temperature control component to maintain the milk temperature in the large circulation loop within the set constant temperature range.

[0058] The entire batch of standardized milk is fed into the mixing tank and the high-shear tank, respectively. A large circulation loop is activated to continuously circulate and replace the milk between the two tanks, achieving homogeneous circulation throughout the entire batch. Simultaneously, the temperature control system is activated. Specifically, temperature sensors installed on the mixing tank and / or the high-shear tank collect the milk mixing temperature in real time and feed it back to the PLC controller. The PLC controller compares the measured temperature with a preset constant temperature range (18℃~22℃). When the measured temperature is higher than 22℃, the PLC controller increases the opening of the proportional regulating valves on the tower water and chilled water pipelines, increasing the flow rate of the cold medium into the heat exchanger to cool the circulating material. When the measured temperature is lower than 18℃, the PLC controller switches and increases the opening of the proportional regulating valve on the steam pipeline, increasing the flow rate of the hot medium into the heat exchanger to heat the material. When the temperature is within the range of 18℃~22℃, the proportional regulating valves maintain a slight opening to dynamically compensate for natural heat loss and accumulation during the production process. Relying on the dual-tank large-circulation material flow and the aforementioned real-time closed-loop temperature control mechanism, the temperature of the milk mixture inside the tank is maintained at the optimal constant temperature range of 18℃ to 22℃ throughout the entire process of material preparation, mixing, and shearing homogenization. This temperature range is the optimal anti-flocculation temperature range for fruit juice mixtures, verified through extensive industrial testing. At this temperature, the spatial conformation of milk casein is stable, its acid and alkali tolerance is excellent, and its resistance to mechanical shear disturbance is strong, thus maximizing the structural stability of milk protein.

[0059] Step S3: During the operation of the large circulation loop, the instantaneous flow rate of milk in the large circulation loop is obtained in real time through the flow ratio feeding component. Based on the instantaneous flow rate and the preset ratio of juice to milk, the flow rate of the target juice is dynamically adjusted to keep the target juice addition amount and the instantaneous flow rate of milk in a constant ratio.

[0060] During the operation of the large circulation loop, the instantaneous flow rate of milk in the loop is acquired in real time through a flow ratio feeding component. Specifically, a first flow meter installed on the feed pipeline between the mixing tank and the high-shear tank detects the instantaneous flow rate of fresh milk being added to the high-shear tank from the mixing tank in real time and transmits the flow signal to the PLC controller. Based on the received instantaneous milk flow signal and the preset juice to milk production ratio, the PLC controller dynamically calculates and determines the target juice flow rate.

[0061] In one embodiment, the operating frequency of the juice delivery rotor pump in the flow ratio feeding component is adjusted in real time by a PLC controller according to the instantaneous flow rate, so that the ratio of the flow rate of the target juice to the instantaneous flow rate of the milk is constant and equal to the preset ratio; wherein, the target juice is sprayed into the circulating milk in an atomized form.

[0062] A second flow meter installed on the pipeline between the juice pH adjustment component and the high-shear tank monitors the actual output flow of the juice delivery rotor pump in real time and feeds it back to the PLC controller. The PLC controller compares the actual flow of the target juice with the target juice flow rate and dynamically adjusts the operating frequency of the juice delivery rotor pump based on the flow deviation: when the actual flow rate is lower than the target juice flow rate, the operating frequency of the juice delivery rotor pump is increased; when the actual flow rate is higher than the target juice flow rate, the operating frequency of the juice delivery rotor pump is decreased. This adjustment is iterated repeatedly until the actual juice flow rate matches the target juice flow rate. The system continuously monitors and adjusts the frequency in a loop. When the milk feed flow rate changes, the target juice flow rate is updated synchronously, and the frequency of the juice delivery rotor pump is adaptively adjusted accordingly to always ensure that the juice addition amount and the milk feed amount maintain a fixed ratio.

[0063] The target fruit juice, after precise pH adjustment, is uniformly sprayed into the large-scale circulating material system within the high-shear tank in the form of fine droplets through an atomizing nozzle under a constant milk temperature of 18℃~22℃. The fine droplet shape has a large specific surface area, allowing the fruit juice and circulating milk to achieve a gentle and uniform initial mixing instantly, without localized concentration buildup or instantaneous acid-base shocks. Combined with the continuous shear homogenization effect of the dual-tank large-scale circulating system driven by a milk transfer centrifugal pump, this achieves gentle, uniform, and comprehensive integration of the fruit juice and milk.

[0064] Step S4: During the operation of the large circulation loop, the liquid level in the high shear tank is detected in real time by the liquid level closed-loop adjustment component, and the return flow rate from the high shear tank to the mixing tank is adjusted according to the deviation between the detected liquid level value and the set value, so that the liquid level in the high shear tank is maintained at the set value.

[0065] During the operation of the large circulation loop, the liquid level in the high-shear tank is monitored in real time by a liquid level closed-loop adjustment component. Specifically, the liquid level detection unit installed on the high-shear tank collects the liquid level signal in real time and transmits it to the PLC controller. The PLC controller compares the measured liquid level value with the preset target working liquid level. When the measured liquid level is higher than the preset value, the PLC controller increases the output frequency of the variable frequency reflux pump, accelerates the reflux rate from the high-shear tank to the mixing tank, increases the reflux flow rate, and causes the liquid level in the tank to drop rapidly to the set value. When the measured liquid level is lower than the preset value, the PLC controller decreases the output frequency of the variable frequency reflux pump, slows down the reflux rate, and decreases the reflux flow rate, causing the liquid level in the tank to rise back to the set value. Through continuous and dynamic variable frequency adjustment of the variable frequency reflux pump, the relationship between the milk feed flow rate, juice flow rate, and reflux discharge flow rate is dynamically balanced in real time, ensuring that the working liquid level of the high-shear tank remains constant throughout the process. This ensures that the high-shear motor always operates stably at the optimal immersion depth, and that the shearing conditions remain stable with consistent material residence time.

[0066] Steps S2, S3, and S4 overlap at least partially in time, collectively forming a steady-state cyclic mixing process until a uniformly mixed yogurt base is obtained. A temperature sensor maintains the milk mixing temperature consistently within the optimal range of 18℃ to 22℃ throughout the process. A first flow meter monitors the milk flow rate in real time and dynamically matches the fruit juice feeding rate. The level detection unit and the variable frequency reflux pump work in real time to stabilize the working level of the high-shear tank. The synergistic effect of these three components ensures unified and controllable operating parameters across the entire large-scale circulation process. Through this four-dimensional steady-state synergistic control of constant temperature, constant flow rate, constant level, and constant shear, the temperature, level, flow rate, and shear intensity are kept constant and controllable throughout the mixing process, until a uniformly mixed, non-stratified, micro-coagulated, and highly stable yogurt base is obtained.

[0067] The homogenized, highly stable yogurt base is directly fed into the existing production line's plate sterilization equipment, strictly adhering to the factory's established 95℃, 300-second fixed sterilization process parameters. There is no need to adjust core parameters such as sterilization temperature, holding time, or heat exchange gradient, nor to modify downstream equipment or piping structures. Subsequent fermentation, filling, low-temperature cooling, finished product storage, and warehousing all follow existing standardized operating procedures, demonstrating strong process compatibility and making industrial-scale implementation seamless.

[0068] This invention provides a method for producing fruit juice-added yogurt. Steps S1 to S4 are executed sequentially and at least partially overlap in time. Through precise closed-loop control of fruit juice pH, stable milk preparation at a constant temperature of 18℃~22℃, atomized feeding with variable milk flow rate, and constant liquid level steady-state circulation using a variable frequency reflux pump, a four-dimensional stable and controllable mixing environment of temperature, liquid level, flow rate, and shear strength is constructed in a dual-tank large circulation system. This method eliminates milk protein instability and micro-flocculation caused by acid-base fluctuations, temperature fluctuations, ratio imbalances, and liquid level fluctuations from the source. This ensures that the yogurt base material maintains a highly stable physical property state before entering the plate sterilization section, effectively solving the problem of plate heat exchanger scaling, significantly extending the continuous operation time of the production line, and reducing cleaning frequency and production costs. At the same time, the atomized spray feeding method combined with the constant temperature and low-disturbance mixing environment maximizes the retention of volatile aroma components such as esters and aldehydes in the fruit juice, resulting in a pure fruit aroma, consistent flavor, and highly uniform batch quality in the finished product. Furthermore, this invention relies entirely on the existing dual-tank large-circulation production line and the 95°C, 300-second fixed plate sterilization process, requiring no hardware modification or parameter adjustment, making it easy to implement in the industrial sector with a low threshold and wide applicability.

[0069] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0070] In the above embodiments, the descriptions of each embodiment have their own emphasis. Parts not detailed or described in a particular embodiment can be referred to in the relevant descriptions of other embodiments. Unless otherwise specified or in conflict with logic, the terminology and / or descriptions between different embodiments are consistent and can be referenced interchangeably. Technical features in different embodiments can be combined to form new embodiments based on their inherent logical relationships.

[0071] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A yogurt production system with added fruit juice, characterized in that, include: Mixing tank, high-shear tank, juice pH adjustment component, constant temperature control component, flow rate proportioning component, and liquid level closed-loop control component; The mixing tank and the high-shear tank are connected by a pipeline to form a large circulation loop for material circulation and replacement. The juice pH adjustment component is connected to the high-shear tank and is used to adjust the pH of the juice to be added and to deliver the target juice with a stable pH value within a preset range into the high-shear tank. The constant temperature control component is installed on the mixing tank and / or the high shear tank, and on the feed pipeline between the mixing tank and the high shear tank, for maintaining the temperature of the circulating material in the tank within a set constant temperature range. The flow rate proportioning feeding component is installed on the feed pipeline between the mixing tank and the high shear tank, and on the pipeline between the juice pH adjustment component and the high shear tank. It is used to dynamically match the flow rate of the target juice according to the real-time flow rate of milk in the large circulation loop, so that the amount of target juice added and the amount of milk fed always maintain a preset ratio. The liquid level closed-loop regulating component is installed on the high-shear tank and on the return pipeline between the high-shear tank and the mixing tank, and is used to regulate the return flow rate from the high-shear tank to the mixing tank so that the liquid level in the high-shear tank is maintained at a set value.

2. The fruit juice-added yogurt production system according to claim 1, characterized in that, The juice pH adjustment component includes: a juice tank, an online pH meter, and a variable frequency micro-metering pump; The juice container contains the juice to be added; The online pH meter is installed inside the juice tank or on the discharge pipe of the juice tank, and is used to detect the pH value of the juice to be added in real time. The variable frequency micro-metering pump is connected to a PLC controller, which is also connected to an online pH meter. The PLC controller receives the pH value of the juice to be added from the online pH meter and controls the variable frequency micro-metering pump to add a pH adjuster to the juice tank in a quantitative manner based on the deviation between the pH value of the juice to be added and the preset pH target value, until the fluctuation deviation of the pH value of the juice to be added is controlled within a preset range.

3. The fruit juice-added yogurt production system according to claim 1, characterized in that, The constant temperature control component includes: a temperature sensor, a heat exchanger, and a proportional regulating valve installed on the heat exchange medium pipeline of the heat exchanger; The temperature sensor is installed on the mixing tank and / or the high-shear tank to detect the material temperature inside the mixing tank and / or the high-shear tank in real time; The heat exchanger is installed on the feed pipe between the mixing tank and the high shear tank, and is used to regulate the temperature of the material in the feed pipe; The temperature sensor and the proportional control valve are respectively connected to the PLC controller. The PLC controller is used to receive the material temperature sent by the temperature sensor and control the opening of the proportional control valve according to the deviation of the material temperature from the preset constant temperature range to adjust the flow rate of the heat exchange medium in the heat exchanger, so that the material temperature in the tank is maintained within the set constant temperature range.

4. The fruit juice-added yogurt production system according to claim 1, characterized in that, The flow rate proportioning feeding assembly includes: a milk conveying centrifugal pump, a first flow meter, a juice conveying rotor pump, a second flow meter, and an atomizing nozzle; The milk conveying centrifugal pump and the first flow meter are installed on the feed pipeline between the mixing tank and the high shear tank. The milk conveying centrifugal pump is used to pump the milk in the mixing tank to the high shear tank. The first flow meter is connected to the PLC controller and is used to detect the instantaneous flow rate of the milk in real time and transmit the instantaneous flow rate of the milk to the PLC controller. The juice delivery rotor pump and the second flow meter are installed on the pipeline between the juice pH adjustment component and the high shear tank. The juice delivery rotor pump is used to pump the target juice to the atomizing nozzle. The second flow meter is connected to the PLC controller and is used to detect the actual flow rate of the target juice in real time and transmit the actual flow rate of the target juice to the PLC controller. The discharge end of the atomizing nozzle is connected to the high-shear tank and is used to spray the target juice into the circulating material in the high-shear tank in an atomized form. The first flow meter, the second flow meter, and the juice delivery rotor pump are respectively connected to the PLC controller. After receiving the instantaneous milk flow signal sent by the first flow meter, the PLC controller calculates the target juice flow rate according to the preset juice to milk production ratio. The PLC controller also compares the actual target juice flow rate fed back by the second flow meter with the target juice flow rate, and dynamically adjusts the operating frequency of the juice delivery rotor pump according to the comparison deviation, so that the actual target juice flow rate matches the target juice flow rate in real time, thereby achieving a constant ratio between the juice flow rate and the milk feed flow rate.

5. The fruit juice-added yogurt production system according to claim 1, characterized in that, The liquid level closed-loop control component includes: a liquid level detection unit and a variable frequency reflux pump; The liquid level detection unit is installed on the high-shear tank and is used to detect the liquid level in the high-shear tank in real time. The variable frequency reflux pump is installed on the reflux pipeline between the high shear tank and the mixing tank; The liquid level detection unit and the variable frequency reflux pump are respectively connected to a PLC controller. The PLC controller is used to receive the liquid level in the high shear tank sent by the liquid level detection unit, and control the operating frequency of the variable frequency reflux pump according to the deviation between the liquid level in the high shear tank and the set value, so as to adjust the reflux flow rate from the high shear tank to the mixing tank.

6. The fruit juice-added yogurt production system according to claim 3, characterized in that, The heat exchanger is a plate heat exchanger, and the heat exchange medium includes at least one of tower water, chilled water, and steam. The heat exchanger is equipped with proportional regulating valves on the corresponding pipelines for tower water, ice water, or steam.

7. The fruit juice-added yogurt production system according to claim 5, characterized in that, The liquid level detection unit is a weighing sensor or a liquid level gauge; The weighing sensor is installed on the support structure of the high-shear tank and calculates the liquid level by detecting changes in the tank's weight; the liquid level gauge is installed on the side wall or top of the high-shear tank.

8. The fruit juice-added yogurt production system according to claim 4, characterized in that, The atomizing nozzle is disposed on the top or side of the high-shear tank, and the spray direction of the atomizing nozzle is toward the material liquid surface or the circulating material flow area inside the high-shear tank.

9. A method for producing fruit juice-added yogurt, characterized in that, Using the fruit juice fortified yogurt production system according to any one of claims 1-8, the method for producing fruit juice fortified yogurt includes: S1. The pH of the juice to be added is adjusted by the juice pH adjustment component to stabilize the pH value of the juice within the preset range, thereby obtaining the target juice with stable pH. S2. Add milk into the mixing tank and the high-shear tank respectively, start the large circulation loop to circulate and replace milk between the mixing tank and the high-shear tank; start the constant temperature control component to maintain the milk temperature in the large circulation loop within the set constant temperature range. S3. During the operation of the large circulation loop, the instantaneous flow rate of milk in the large circulation loop is obtained in real time through the flow ratio feeding component. Based on the instantaneous flow rate and the preset ratio of juice to milk, the flow rate of the target juice is dynamically adjusted so that the amount of target juice added and the instantaneous flow rate of milk are kept in a constant ratio. S4. During the operation of the large circulation loop, the liquid level in the high shear tank is detected in real time by the liquid level closed-loop adjustment component, and the return flow rate from the high shear tank to the mixing tank is adjusted according to the deviation between the liquid level detection value and the set value, so that the liquid level in the high shear tank is maintained at the set value. Steps S2, S3, and S4 overlap at least partially in time, together forming a steady-state cyclic mixing process until a uniformly mixed yogurt base is obtained.

10. The method for producing fruit juice-added yogurt according to claim 9, characterized in that, Based on the instantaneous flow rate and the preset juice to milk ratio, the flow rate of the target juice is dynamically adjusted, including: Based on the instantaneous flow rate, the operating frequency of the juice delivery rotor pump in the flow rate ratio feeding component is adjusted in real time by the PLC controller so that the ratio of the target juice flow rate to the instantaneous flow rate of milk is constant and equal to the preset ratio; wherein, the target juice is sprayed into the circulating milk in an atomized form.

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