Intelligent electrodialysis demineralization method for improving thermal stability of goat milk

Abstract

The invention provides an intelligent electrodialysis demineralization method and system for improving the thermal stability of goat milk. According to the method, mineral ions in goat milk are selectively removed through an electrodialysis technology, an intelligent closed-loop control system based on real-time conductivity monitoring is adopted, the ion removal proportion is accurately regulated and controlled, and particularly the molar concentration ratio of sodium ions to potassium ions is controlled to be (1.2-1.4): 1. The thermal stability of the treated goat milk is remarkably improved, the thermal stability time at 140 DEG C can be prolonged by 80-150%, and the precipitation rate after UHT treatment is lower than 2.0%. The intelligent control electrodialysis technology is applied to precise ion regulation and control of the goat milk for the first time, the technical problem that the goat milk is poor in high-temperature processing stability is solved, and the method has important industrial application value.

Description

Technical Field

[0001] This invention belongs to the field of dairy processing technology, specifically relating to an intelligent electrodialysis demineralization method for improving the thermal stability of goat milk. It is a production process that uses electrodialysis technology to precisely control the mineral ion content in goat milk and improve its thermal stability. Background Technology

[0002] As a dairy product with high nutritional value, goat milk has seen a continuous increase in consumer demand in recent years. However, goat milk suffers from significant thermal stability issues during high-temperature processing, which has become a key technological bottleneck restricting its industrial production and the development of high-end products.

[0003] Studies have found that the mineral ion composition of goat milk has a decisive influence on its thermal stability. Goat milk contains high concentrations of potassium (K⁺), sodium (Na⁺), and calcium (Ca⁺). 2 ⁺、Mg 2 Mineral ions such as ⁺ and chloride (Cl⁻) directly affect the stability of casein micelles. When goat milk is processed under ultra-high temperature sterilization (UHT, usually 135-140℃), excessive free calcium ions bind to phosphoserine residues of casein, destroying the casein protective layer on the surface of the micelles, leading to protein aggregation and precipitation.

[0004] Currently, commonly used industrial methods to improve the heat stability of goat milk mainly include: 1. Adding stabilizers: such as chelating agents like phosphates and citrates, which maintain protein stability by binding free calcium ions. However, this method has the following problems: it may introduce foreign chemicals, affecting the natural properties of the product; excessive addition may affect taste and flavor; and it is restricted by regulations in some countries and regions. 2. Ion exchange resin treatment: can remove some mineral ions, but has the following disadvantages: the treatment process is intermittent, making continuous production difficult; resin regeneration requires chemical reagents, generating wastewater; and the selectivity is poor, potentially removing beneficial components simultaneously. 3. Nanofiltration / reverse osmosis treatment: can remove some ions, but has the following problems: it mainly relies on pressure drive, resulting in high energy consumption; its selective separation ability for monovalent and divalent ions is limited; and it may lead to the loss of small molecules such as lactose.

[0005] Electrodialysis (ED) is a separation technology based on ion exchange membranes and a direct current electric field, widely used in seawater desalination, wastewater treatment, and desalination of certain foods. In the dairy industry, ED is mainly used for: whey desalination to produce infant formula base and mineral adjustment of certain dairy products. However, applying ED to the treatment of whole goat milk faces unique technical challenges: 1. Compositional complexity: Goat milk contains fat globules, protein micelles, various mineral ions, and organic acids, which may cause membrane fouling and scaling; 2. High processing precision requirements: Precise control of the removal ratio of multiple ions is needed, rather than simple overall desalination; 3. Complex thermal stability mechanism: Simultaneous control of ion concentration and ion ratio is required, especially the potassium-sodium ratio and the calcium-magnesium ratio.

[0006] Currently, there are no publicly available documents reporting the use of closed-loop controlled electrodialysis systems specifically for the precise ion regulation of goat milk to improve its thermal stability. Summary of the Invention

[0007] The technical problem solved by this invention: The purpose of this invention is to overcome the shortcomings of the prior art and provide an intelligent electrodialysis demineralization method for improving the thermal stability of goat milk. Specifically, it provides a continuous and automated electrodialysis demineralization method for goat milk, achieving selective and proportional removal of various mineral ions in goat milk; establishing an intelligent control strategy based on real-time conductivity feedback; significantly improving the thermal stability of goat milk under UHT treatment conditions; and improving the taste and flavor characteristics of goat milk products.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A smart electrodialysis demineralization method for improving the thermal stability of sheep milk includes the following steps: Step S1. Standardize and pasteurize the raw sheep milk; Step S2. The pretreated sheep milk is introduced into an electrodialysis device, which includes alternating anion exchange membranes and cation exchange membranes, and a direct current electric field is applied. Step S3. Monitor the conductivity of the processed goat milk in real time using a conductivity sensor; Step S4. Based on the deviation between the preset target conductivity value and the real-time monitored conductivity value, the DC electric field strength and / or the sheep milk flow rate are automatically adjusted through a control algorithm; Step S5. Control the molar ratio of sodium ions to potassium ions in the treated goat milk within the range of 1.2-1.4:1; Step S6. Collect the demineralized sheep milk after electrodialysis treatment.

[0009] In step S4, the control algorithm is a PID control algorithm, the target conductivity value is 1.3-1.8 mS / cm, and the DC electric field strength adjustment range is 10-50V.

[0010] Furthermore, the electrodialysis device adopts a two-stage series structure, with the target conductivity of the first stage being 1.8-2.2 mS / cm and the target conductivity of the second stage being 1.3-1.8 mS / cm.

[0011] Furthermore, step S5 also includes controlling the molar concentration ratio of calcium ions to potassium ions within the range of 0.8-1.2:1, and reducing the total concentration of potassium and sodium ions in sheep milk by 35-60% and the total concentration of calcium and magnesium ions by 15-25% after treatment.

[0012] Furthermore, step S4 also includes feedforward control based on the initial conductivity of the raw sheep milk, and preset initial operating conditions according to the difference between the initial conductivity and the target conductivity.

[0013] Furthermore, the operating temperature of the electrodialysis device is controlled at 8-15℃, and a pulsed DC electric field is used with a pulse period of 20-60 seconds and a duty cycle of 60-80%.

[0014] Furthermore, it also includes identifying the breed of raw sheep milk before electrodialysis treatment, and selecting the corresponding target conductivity value and ion ratio setting value according to the breed.

[0015] Furthermore, the demineralized sheep milk collected in step S6 has a thermal stability time at 140°C that is at least 80% longer than that of the raw sheep milk, and the precipitation rate after UHT treatment at 140°C for 4 seconds is less than 2.0% (w / w).

[0016] An intelligent electrodialysis demineralization system for implementing the above-described method includes: An electrodialysis device comprising alternating anion exchange membranes and cation exchange membranes; A DC power supply used to provide an adjustable DC electric field; A conductivity sensor is installed at the outlet of the electrodialysis device; The control system receives signals from the conductivity sensor and adjusts the output of the DC power supply and / or the speed of the feed pump according to a preset algorithm.

[0017] A demineralized goat milk product prepared by the above method, wherein the electrical conductivity of the goat milk product is 1.3-1.8 mS / cm; the molar ratio of sodium ions to potassium ions is 1.2-1.4:1; the thermal stability time at 140℃ is ≥3.0 minutes; and the precipitation rate after UHT treatment at 140℃ for 4 seconds is ≤1.5% (w / w).

[0018] Advantages of this invention compared to existing technologies: 1. This solution is the first to propose the concept of precise control of ions in sheep milk. It is not a simple desalination, but rather an optimization of the proportion of multiple ions based on the thermal stability mechanism. It establishes a sheep milk-specific model of conductivity and ion concentration, which solves the technical problem of real-time monitoring of complex systems. 2. The heat stability time of goat milk treated with this method at 140℃ can be increased by 80-150%, and the heat stability is significantly improved; the sedimentation rate of UHT treatment is reduced from the usual 5-8% to below 1.5%, and the product sedimentation rate is greatly reduced; the perceived intensity of goaty odor is reduced by 30-50%, and the taste is more mellow and delicate; the spray drying efficiency is improved, energy consumption is reduced by 5-10%, and the processing adaptability is enhanced. 3. This solution reduces manual intervention, improves product consistency, and has a high degree of automation; it contains no chemical additives, the concentrate can be recycled, and it is environmentally friendly; it reduces the amount of stabilizer used, lowers overall production costs, and has significant economic benefits. Attached Figure Description

[0019] Figure 1 This is a process flow diagram of the intelligent electrodialysis demineralization method of the present invention. Detailed Implementation

[0020] 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.

[0021] Please see Figure 1 The embodiments of the present invention are described in detail below.

[0022] This invention proposes an intelligent electrodialysis demineralization method for improving the thermal stability of sheep milk, comprising the following steps: Step S1. Standardize the raw goat milk by adjusting the fat content to 3.0-4.5% and the protein content to 3.0-3.8%, and then pasteurize it (72-75℃, 15-20 seconds). Step S2. A two-stage series electrodialysis device is used. The first stage aims to remove monovalent ions, controlling the conductivity to 1.8-2.2 mS / cm. The second stage aims to adjust the proportion of divalent ions, controlling the conductivity to 1.3-1.8 mS / cm. The device operating temperature is controlled at 8-15℃. An adjustable DC electric field is applied to the two electrodes of the device, using a pulsed DC electric field with a pulse period of 20-60 seconds and a duty cycle of 60-80%. Step S3. Install a high-precision conductivity sensor at the outlet of the electrodialysis system to monitor the conductivity of the treated sheep milk in real time and feed the signal back to the control system. Step S4. The control system automatically adjusts the DC electric field strength (10-50V) and / or the sheep milk feed flow rate (500-2000L / h) through a PID control algorithm based on the deviation between the preset target conductivity value (1.3-2.2mS / cm, 25℃) and the real-time monitored conductivity value. Step S5. Control the treated goat milk to meet the following ion ratio requirements: reduce the total concentration of potassium and sodium ions by 35-60%, reduce the total concentration of calcium and magnesium ions by 15-25%, control the molar ratio of sodium ions to potassium ions at 1.2-1.4:1, and control the molar ratio of calcium ions to potassium ions at 0.8-1.2:1. Step S6. Collect the demineralized sheep milk after electrodialysis treatment, and adjust the pH to 6.6-6.8 if necessary, and then proceed to the subsequent processing steps.

[0023] The core working principle of this invention is as follows: Under the action of a direct current electric field, charged ions in sheep milk undergo directional migration: cations (K+, Na+, Ca2+, Mg2+) move towards the cathode, while anions (Cl, PO43-, citrate, etc.) move towards the anode. This is achieved by selecting ion exchange membranes with specific permeability: cation exchange membranes allow only cations to pass through, and anion exchange membranes allow only anions to pass through. This selective migration allows different ions to be removed in specific proportions.

[0024] Example 1: Demineralization experiment of sheep milk by single-stage electrodialysis.

[0025] Equipment configuration: Electrodialysis unit: single-stage, 10 pairs of membranes (5 pairs of cation exchange membranes / 5 pairs of anion exchange membranes), effective membrane area 0.5 m² 2 DC power supply: 0-60V, 0-30A adjustable; Conductivity sensor: online, accuracy 0.01mS / cm; Control system: PLC + touch screen, built-in PID control algorithm; Raw material tank and post-processing collection tank: food-grade stainless steel.

[0026] Raw material goat milk parameters: Saanen dairy goats, 2-4 months postpartum; fat content: 3.8%; protein content: 3.4%; initial conductivity: 4.2 mS / cm (25℃). Initial ion concentration (mg / L): K⁺: 1450 ± 50, Na⁺: 350 ± 20, Ca⁺: 1450 ± 50. 2 ⁺: 1200 ± 50, Mg 2 ⁺: 120 ± 10, Cl⁻: 1500 ± 503.

[0027] Process parameter settings: Pretreatment: Standardize to 3.8% fat and 3.4% protein; Pasteurize at 75℃ for 15 seconds; Target conductivity: 1.3 mS / cm; Initial operating conditions: DC voltage: 25V, current density: 15A / m 2 Milk flow rate: 800L / h, temperature control: 15±1℃.

[0028] Implementation process: The system starts up, and raw sheep milk enters the electrodialysis device at a set flow rate; in the initial stage, feedforward control is used, and the initial voltage is set to 25V based on the initial conductivity of 4.2mS / cm; after the processing begins, the outlet conductivity sensor monitors the data in real time; from the first 1 to the last 5 minutes, the outlet conductivity drops from 4.2 to 2.5mS / cm, and the control system maintains the voltage at 25V; from the last 6 to the last 15 minutes, the conductivity drops to 2.1mS / cm, and the PID controller gradually reduces the voltage to 18V; from the last 16 to the last 30 minutes, the system enters a steady state, with the conductivity stabilizing at 1.3±0.05mS / cm and the voltage fluctuating within the range of 16-18V.

[0029] Experimental results data Table 1: Changes in ion concentration in Example 1 Ion types Raw material concentration (mg / L) Post-treatment concentration (mg / L) Removal rate (%) Molar ratio change K⁺ 1450 416 71.3 K / Na: 1.32-1.35 Na⁺ 350 297 15.1 <![CDATA[Ca 2 ⁺]]> 1200 960 20.0 Ca / K: 0.85-1.00 <![CDATA[Mg 2 ⁺]]> 120 90 25.0 Cl⁻ 1500 1050 30.0 Table 2: Thermal stability test results of Example 1 Test conditions Raw material: goat milk Processed goat milk Improvement rate Thermal stability time at 120℃ (min) 12.5 25.3 +102% Thermal stability time at 135℃ (min) 3.8 8.2 +116% Thermal stability time at 140℃ (min) 1.5 3.5 +133% Precipitation rate (%w / w) after UHT treatment at 140℃ for 4 seconds: 6 6.2 1.3 -79% Table 3: Sensory evaluation results, 10-person evaluation panel, 10-point scale project Raw material: goat milk Processed goat milk improve intensity of muttony smell 6.5 3.2 -51% Smoothness of texture 5.8 8.2 +41% Overall acceptance 6.0 8.5 +42% The performance analysis of this experiment is as follows: the conductivity was controlled at 3.0±0.05 mS / cm, with a relative error of <1.7%; the response time from start-up to steady state was 25 minutes; the anti-interference ability was demonstrated by artificially simulating a raw material conductivity fluctuation of +0.3 mS / cm at the 20th minute, and the system recovered to stability within 3 minutes; the energy consumption was approximately 8.5 kWh for processing 1 ton of sheep milk.

[0030] Example 2: Demineralization Experiment Based on Two-Stage Electrodialysis Equipment configuration: Electrodialysis unit: two stages in series, 8 pairs of membranes per stage; interstage cooling: a plate heat exchanger is installed at the outlet of the first stage to control the feed temperature of the second stage; multi-parameter monitoring: online monitoring of conductivity, pH and temperature.

[0031] Process Method: Staged Demineralization Concept: First Stage: Focus on removing monovalent ions (K⁺, Na⁺, Cl⁻), with a target conductivity of 1.8 mS / cm; Second Stage: Finely adjust the proportion of divalent ions (Ca... 2 ⁺、Mg 2(⁺), target conductivity 1.3 mS / cm. Temperature gradient control: First stage: 10-12℃; Second stage: 8-10℃. Multivariate control: Main control variable: outlet conductivity; Auxiliary variables: current efficiency and voltage drop at each stage; Constraint: membrane surface velocity > 0.05 m / s.

[0032] Implementation Process: First Stage Treatment: Raw material conductivity: 4.3 mS / cm, target conductivity: 1.8 mS / cm, operating voltage: 20-28V adaptive adjustment, treatment time: 15 minutes to reach steady state. Interstage Treatment: Temperature adjustment: cooling from 12℃ to 9℃; pH fine-tuning: adjusting to 6.7±0.1 with food-grade citric acid. Second Stage Treatment: Feed conductivity: 1.8 mS / cm; target conductivity: 1.3 mS / cm; pulsed electric field (30s period, 70% duty cycle); treatment time: 12 minutes to reach steady state.

[0033] Comparison of experimental results Table 4: Comparison of ion control precision between Example 2 and Example 1 index Example 1 Example 2 improve K / Na ion molar ratio control precision ±0.08 ±0.03 +63% Ca / K ion molar ratio control precision ±0.10 ±0.04 +60% Batch-to-batch conductivity coefficient of variation (CV) 2.1% 0.8% +62% Time to reach steady state (min) 25 27 Basically equivalent Table 5: Comparison of Thermal Stability Improvement Effects Test Project Raw material: goat milk Example 1 Example 2 Thermal solidification time (140℃ min) 1.5 3.5 4.2 Sedimentation rate (140℃ / 4s %) 6.2 1.3 0.8 Protein denaturation rate (%) 15.3 8.5 5.2 Example 3: Adaptability verification of different goat milk breeds Experimental design: Three common dairy goat breeds were selected: Saanen goat (high-yielding), Toggenburg goat (medium-yielding), and Alps goat (local breed).

[0034] Control method: The control system has built-in optimized parameter combinations for different varieties, preset initial operating conditions, fine-tuned target conductivity, and optimized ion ratio setpoint.

[0035] Experimental results Table 6: Effects of treatment on different breeds of goat milk variety Initial conductivity (mS / cm) Target conductivity (mS / cm) Optimized Na / K ion ratio Improved thermal stability (%) Saanen 4.2 1.3 1.35:1 +133% Tugenburg 3.9 1.2 1.25:1 +128% Alps 4.5 1.5 1.40:1 +120% Quality control and stability verification: Long-term continuous operation shows that the standard deviation of key product indicators is extremely small.

[0036] Conclusion: Example 2 (two-stage series connection + pulsed electric field + advanced control) is superior to Example 1 in terms of product quality, process stability, and long-term economic efficiency. Example 3 shows that the system can be adapted to different varieties (Saanen, Tougamburg, Alps) of sheep milk through parameter fine-tuning, with thermal stability improvements exceeding 120%. After 7 days of continuous production, the standard deviation of key product indicators (thermal stability time, sedimentation rate) is extremely small, making it suitable for continuous industrial production.

[0037] In summary, this invention provides a complete, mature, and fully validated method for precise ion control in sheep milk. Experimental data fully demonstrate that this technology not only fundamentally solves the problem of poor thermal stability in sheep milk, but also achieves simultaneous improvements in product quality, production efficiency, and economic benefits through intelligent and precise process control.

[0038] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0039] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An intelligent electrodialytic demineralization method for improving the heat stability of goat milk, characterized by: The method comprises the following steps: Step S1. Standardizing and pasteurizing the raw goat milk; Step S2. Introducing the pretreated goat milk into an electrodialysis device comprising anion exchange membranes and cation exchange membranes arranged alternately, and applying a direct current electric field; Step S3. Monitoring the conductivity of the treated goat milk in real time through a conductivity sensor; Step S4. Automatically adjusting the strength of the direct current electric field and / or the flow rate of the goat milk based on the deviation between the preset target conductivity value and the real-time monitored conductivity value through a control algorithm; Step S5. Controlling the molar concentration ratio of sodium ions to potassium ions in the treated goat milk to be within the range of 1.2-1.4:1; Step S6. Collecting the demineralized goat milk treated by electrodialysis.

2. The method for improving the heat stability of goat milk by intelligent electrodialytic demineralization according to claim 1, characterized in that: The control algorithm in step S4 is a PID control algorithm, the target conductivity value is 1.3-1.8 mS / cm, and the adjustment range of the strength of the direct current electric field is 10-50 V.

3. The method for improving the heat stability of goat milk by intelligent electrodialytic demineralization according to claim 1, characterized in that: The electrodialysis device adopts a two-stage series structure, the target conductivity of the first stage is 1.8-2.2 mS / cm, and the target conductivity of the second stage is 1.3-1.8 mS / cm.

4. The method for improving the heat stability of goat milk by intelligent electrodialytic demineralization according to claim 1, characterized in that: In step S5, the molar concentration ratio of calcium ions to potassium ions is also controlled to be within the range of 0.8-1.2:1, the total concentration of potassium ions and sodium ions in the treated goat milk is reduced by 35-60%, and the total concentration of calcium ions and magnesium ions is reduced by 15-25%.

5. The method for improving heat stability of goat milk by intelligent electrodialytic demineralization according to claim 1, characterized in that: In step S4, feedforward control is also performed based on the initial conductivity of the raw goat milk, and the initial operating conditions are preset according to the difference between the initial conductivity and the target conductivity.

6. The method for improving heat stability of goat milk by intelligent electrodialytic demineralization according to claim 1, characterized in that: The operating temperature of the electrodialysis device is controlled at 8-15℃, and a pulse direct current electric field is used, with a pulse period of 20-60 seconds and a duty cycle of 60-80%.

7. The method for improving heat stability of goat milk by intelligent electrodialytic demineralization according to claim 1, characterized in that: The method further comprises identifying the breed of the raw goat milk before electrodialysis treatment, and selecting corresponding target conductivity values and ion proportion setting values according to the breed.

8. The method for improving heat stability of goat milk by intelligent electrodialytic demineralization according to claim 1, characterized in that: The demineralized goat milk collected in step S6 has a heat stability time at 140℃ that is at least 80% higher than that of the raw goat milk, and a sedimentation rate after UHT treatment at 140℃ / 4 seconds of less than 2.0% (w / w).

9. An intelligent electrodialytic demineralization system implementing the method of any one of claims 1-8, characterized by: The method comprises: an electrodialysis device comprising anion exchange membranes and cation exchange membranes arranged alternately; a direct current power supply for providing an adjustable direct current electric field; a conductivity sensor arranged at the outlet of the electrodialysis device; a control system receiving signals from the conductivity sensor and adjusting the output of the direct current power supply and / or the speed of the feed pump according to a preset algorithm.

10. A demineralised sheep milk product prepared by the method of any one of claims 1 to 8, characterised in that: The conductivity of the goat milk product is 1.3-1.8 mS / cm, the molar concentration ratio of sodium ions to potassium ions is 1.2-1.4:1, the heat stability time at 140℃ is ≥3.0 minutes, and the sedimentation rate after UHT treatment at 140℃ / 4 seconds is ≤1.5% (w / w).

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