Preparation technology of lactose-free modulated goat milk powder

Abstract

The invention relates to the technical field of milk powder preparation, and discloses a preparation process of lactose-free prepared goat milk powder, which comprises the steps of raw material pretreatment, double-frequency ultrasonic-ionic liquid medium enzymolysis, magnetic response molecular sieve separation, ionic liquid recovery and regeneration and subsequent processing. Wherein the enzymolysis environment is optimized by combining a dual-frequency ultrasonic technology and an ionic liquid medium, high-selectivity separation is realized by utilizing a magnetic response molecular sieve, and the problems of cyclic regeneration and cross contamination of the ionic liquid are solved by a phase inversion cyclic purification-biological enzyme self-cleaning process; according to the method disclosed by the invention, the enzymolysis time is shortened to 1 / 4 of the original enzymolysis time, the enzyme reuse times are increased by more than 5 times, the residual sugar content of the product is as low as 0.005%, and an efficient, stable and economic process path is provided for industrial production of the zero-lactose goat milk powder.

Description

Technical Field

[0001] The present invention relates to the technical field of milk powder preparation, and more specifically, it relates to a preparation process of 0-lactose modified goat milk powder. Background Art

[0002] Lactose intolerance is a common digestive system phenomenon worldwide. Patients lack sufficient lactase in their bodies and are unable to effectively break down lactose, resulting in discomfort symptoms such as indigestion, abdominal distension, and diarrhea. As an alternative milk source, goat milk has a protein structure closer to human milk and a slightly lower natural lactose content than cow's milk. However, for patients with severe lactose intolerance, deep de-lactosylation treatment is still required.

[0003] Existing 0-lactose dairy products are mainly prepared by β-galactosidase enzymatic hydrolysis process, but the traditional process has multiple technical limitations: low enzymatic hydrolysis efficiency and long reaction time, which restrict production efficiency; enzymatic reactions are easily inhibited by products, making it difficult to achieve high conversion rates; the separation and purification effects of lactose and its degradation products are not good, and the residual sugar content is difficult to control; the enzyme cost is high and the recycling rate is low, increasing production costs.

[0004] Although the ultrasonic-assisted enzymatic hydrolysis and gel filtration combined process has improved the above limitations to a certain extent, there are still many limiting factors in large-scale industrial production: uneven distribution of the ultrasonic field leads to incomplete reactions, gel filtration is prone to blockage and difficult to operate continuously, and key materials are difficult to recycle efficiently, etc. These limiting factors affect the industrial production efficiency and product quality of 0-lactose goat milk powder. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides a preparation process of 0-lactose modified goat milk powder, including the following steps:

[0006] Step 1: Pretreat goat milk to obtain a pretreated emulsion;

[0007] Step 2: Under the condition of dual-frequency ultrasound in an ionic liquid medium, perform β-galactosidase enzymatic hydrolysis treatment on the pretreated emulsion to obtain an enzymatic hydrolysis product;

[0008] Step 3: Separate the enzymatic hydrolysis product through a magnetic-responsive molecular sieve, and the magnetic-responsive molecular sieve realizes dynamic regulation of pore size through an external magnetic field to obtain 0-lactose goat milk;

[0009] Step 4: Recover the ionic liquid through a phase inversion cycle purification-bioenzyme self-cleaning process;

[0010] Step 5: Perform subsequent processing on the 0-lactose goat milk to obtain 0-lactose modified goat milk powder.

[0011] Preferably: The pretreatment in Step 1 includes: filtration, standardization, low-temperature pasteurization, and cooling, adjusting the fat content to 3.0 - 3.5%, the protein content to 3.0 - 3.2%, the pasteurization conditions are to maintain at 60 - 65 °C for 15 - 20 minutes, and cooling to 40 - 45 °C.

[0012] Preferably: The ionic liquid medium in Step 2 is obtained by mixing 1-butyl-3-methylimidazolium tetrafluoroborate with water in a ratio of 1:4 (v / v).

[0013] Preferably: The dual-frequency ultrasonic conditions in Step 2 include: simultaneously applying low-frequency 25 kHz and high-frequency 90 kHz ultrasonic waves, with power densities of 0.2 - 0.3 W / cm 3 and 0.5 - 0.6 W / cm 3 .

[0014] Preferably: The addition amount of β-galactosidase in Step 2 is 0.05 - 0.08% (w / v), the enzymatic hydrolysis reaction temperature is 40 - 45 °C, the pH value is 6.0 - 6.5, and the reaction time is 2 - 3 hours.

[0015] Preferably: The magnetic-responsive molecular sieve in Step 3 is prepared by the following method:

[0016] (1) Mix Fe 3 O 4 magnetic nanoparticles with mesoporous silicon materials in a ratio of 1:5 (w / w);

[0017] (2) Uniformly disperse Fe 3 O 4 nanoparticles on the mesoporous silicon materials by the impregnation-coprecipitation method;

[0018] (3) After drying and activation treatment, obtain the magnetic-responsive molecular sieve material.

[0019] Preferably: The external magnetic field strength in Step 3 is 0.1 - 0.5 T, and the pore size change range of the magnetic-responsive molecular sieve is 0.5 - 2.0 nm.

[0020] Preferably: The phase inversion cycle purification-bioenzyme self-cleaning process in Step 4 includes the following steps:

[0021] (1) Perform phase separation on the ionic liquid-containing mixed solution at a temperature of 32 - 35 °C;

[0022] (2) Separate the ionic liquid-rich phase;

[0023] (3) Add lipase and protease to the ionic liquid-rich phase for self-cleaning treatment;

[0024] (4) Add glucose oxidase and galactose oxidase to the treated ionic liquid to convert the residual monosaccharides into aldonic acids;

[0025] (5) Adjust the pH value to 4.5 - 5.0 to form a precipitate of sodium aldonate;

[0026] (6) Filter to remove the precipitate to obtain the regenerated ionic liquid.

[0027] Preferably: 2% (w / v), the reaction temperature is 37 - 40 °C, the pH value is 7.0 - 7.5, and the reaction time is 1 - 2 hours.

[0028] Preferably: In step 4, the activity of glucose oxidase ≥ 150 U / mg, the activity of galactose oxidase ≥ 100 U / mg, the addition amount of both is 0.01 - 0.02% (w / v), the reaction temperature is 30 - 35 °C, the pH value is 6.0 - 7.0, and the reaction time is 1 - 1.5 hours.

[0029] Preferably: The subsequent processing in step 5 includes: concentration, ingredient modulation, spray drying, and packaging and quality control, where the inlet temperature of spray drying is 170 - 180 °C and the outlet temperature is 75 - 85 °C.

[0030] Preferably: In step 5, the concentration is to concentrate the total solid content of the zero - lactose goat milk emulsion from about 12% to 45 - 50%, and the concentration temperature does not exceed 70 °C.

[0031] The beneficial effects of the present invention are as follows:

[0032] The enzymatic hydrolysis time is shortened: Compared with the traditional enzymatic hydrolysis process, the dual - frequency ultrasound - ionic liquid synergistic enzymatic hydrolysis technology in this embodiment shortens the enzymatic hydrolysis time from the traditional 8 - 10 hours to 2 - 3 hours, improving the production efficiency.

[0033] The enzyme utilization rate is improved: The protective effect of the ionic liquid medium on the enzyme improves the stability of β - galactosidase, and its reuse times increase from 1 - 2 times in the traditional process to more than 10 times, reducing the enzyme cost.

[0034] The enzyme dosage is reduced: In this embodiment, the addition amount of β - galactosidase is 0.05 - 0.08% (w / v), which is reduced by about 60% compared with 0.15 - 0.2% (w / v) in the traditional process, reducing the production cost.

[0035] High purity: Through the selective separation of the magnetic - responsive molecular sieve, the residual lactose content of the zero - lactose goat milk powder prepared in this embodiment is as low as 0.005%, lower than the level of 0.01 - 0.1% of common products on the market, and is suitable for lactose - sensitive people.

[0036] Nutrient retention: The enzymatic hydrolysis in the dual-frequency ultrasound-ionic liquid medium is carried out under mild conditions (40 - 45 °C). Compared with traditional high-temperature enzymatic hydrolysis, it better retains thermosensitive bioactive components such as immunoglobulins and lactoferrin in goat milk.

[0037] Sensory quality improvement: Through the synergistic effect of ionic liquids, the enzymatic hydrolysis products are more uniform, reducing the problems of excessive sweetness or aftertaste commonly found in conventional lactose-free products.

[0038] Ionic liquid recycling: Through the phase transformation cycle purification-bioenzyme self-cleaning process, the recovery rate of ionic liquids reaches over 95%, and the accumulation of impurities is reduced by 95%. The recycling of ionic liquids is achieved, reducing raw material costs and environmental burdens.

[0039] Batch-to-batch consistency: The conversion treatment of carbohydrate impurities solves the problem of cross-contamination between batches, ensuring batch-to-batch consistency in product quality and meeting the requirements of large-scale industrial production.

[0040] Separation material stability: The magnetoresponsive molecular sieve can achieve self-cleaning and regeneration under magnetic field regulation. Its service life is extended by 3 - 5 times compared with traditional gel filtration materials, reducing the frequency and cost of material replacement.

[0041] Continuous operation: Each process link of this embodiment can achieve continuous operation, overcoming the efficiency limitations brought by batch operation in the production of traditional lactose-free goat milk powder.

[0042] Improved processing capacity: The introduction of the magnetoresponsive molecular sieve separation technology increases the separation processing capacity by more than 3 times, solving the separation limitations in traditional processes.

[0043] Energy consumption reduction: Phase transformation cycle purification does not require high-energy physical or chemical treatments, and the bioenzyme self-cleaning process is carried out under mild conditions. The overall process energy consumption is reduced by about 40% compared with traditional methods.

[0044] In summary, through the integration of three core technologies, this embodiment solves the technical limitations in the production of lactose-free goat milk powder. While improving product quality, it reduces production costs, providing an efficient, stable, and economical process route for the industrial-scale production of lactose-free goat milk powder. Brief description of the drawings

[0045] Figure 1 is a comparison chart of the residual lactose content of the present invention and traditional separation methods;

[0046] Figure 2 is a performance tracking chart of the continuous use of ionic liquids of the present invention;

[0047] Figure 3 is a comparison chart of the output and continuity of different process flows of the present invention;

[0048] Figure 4 It is a comparison chart of the energy consumption distribution of different process flows of the present invention. Specific Embodiments

[0049] The subject matter described herein will now be discussed with reference to example embodiments. It should be understood that discussing these embodiments is only to enable those skilled in the art to better understand and thus implement the subject matter described herein, and changes can be made to the functions and arrangements of the elements discussed without departing from the scope of protection of the content of this specification. Each example can omit, substitute, or add various processes or components as needed. Additionally, the features described in some examples can also be combined in other examples.

[0050] Example 1

[0051] In this embodiment, a preparation process of 0-lactose modified goat milk powder is proposed, including the following steps:

[0052] 1. Raw material pretreatment

[0053] Filter and standardize fresh goat milk, adjust the fat content to 3.0 - 3.5%, and the protein content to 3.0 - 3.2%. Subsequently, perform low-temperature pasteurization at 60 - 65°C for 15 - 20 minutes, and cool to 40 - 45°C for standby. This step uses conventional industry methods to ensure the quality and safety of raw materials.

[0054] Among them, adjust the fat content to 3.0 or 3.2 or 3.5%, and in this embodiment, adjust the fat content to 3.2%;

[0055] The protein content is adjusted to 3.0 or 3.1 or 3.2%, and in this embodiment, the protein content is adjusted to 3.1%.

[0056] Perform low-temperature pasteurization at 60 or 63 or 65°C for 15 or 18 or 20 minutes, and cool to 40 or 42 or 45°C for standby. In this embodiment, perform low-temperature pasteurization at 63°C for 20 minutes and cool to 42°C for standby.

[0057] 2. Dual-frequency ultrasonic - ionic liquid medium enzymatic hydrolysis

[0058] 2.1 Preparation of ionic liquid medium

[0059] Mix 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]) with water in a ratio of 1:4 (v / v) to obtain an ionic liquid aqueous solution. This ionic liquid has low toxicity and biocompatibility and is suitable for food processing. The ionic liquid interacts with enzyme molecules by forming an ionized hydrogen bond network, improving the thermal stability and pH tolerance of enzyme molecules.

[0060] 2.2 Construction of dual-frequency ultrasonic system

[0061] This step uses a dual-frequency ultrasonic system, simultaneously applying low-frequency (25 kHz) and high-frequency (90 kHz) ultrasonic waves, with power densities of 0.2 - 0.3 W / cm 3 and 0.5 - 0.6 W / cm 3 .

[0062] Among them, the power densities are 0.2 or 0.25 or 0.3 W / cm 3 and 0.5 or 0.55 or 0.6 W / cm 3 , and in this embodiment, the power densities are 0.25 / cm 3 and 0.55 / cm 3 .

[0063] The dual-frequency ultrasonic waves produce a synergistic effect in the liquid medium: the low-frequency ultrasonic waves mainly generate strong macroscopic mechanical vibrations and liquid flows, promoting overall mixing; the high-frequency ultrasonic waves generate a denser microbubble cavitation effect, enhancing microscale mass transfer and local energy release. This dual-frequency synergistic effect is different from traditional single-frequency ultrasonic waves and can reduce the non-uniformity phenomenon faced by single-frequency ultrasonic waves in large reactors.

[0064] 2.3. Enzymatic hydrolysis reaction process

[0065] Add β-galactosidase (enzyme activity ≥ 3000 U / g) to the pretreated ionic liquid-goat milk mixture at an addition amount of 0.05 - 0.08% (w / v), and under the condition of dual-frequency ultrasonic waves, control the reaction temperature at 40 - 45 °C and the pH value at 6.0 - 6.5, and carry out an enzymatic hydrolysis reaction for 2 - 3 hours.

[0066] Among them, add β-galactosidase (enzyme activity ≥ 3000 U / g) to the pretreated ionic liquid-goat milk mixture at an addition amount of 0.05 or 0.06 or 0.08% (w / v), and in this embodiment, add it at an addition amount of 0.060.08% (w / v);

[0067] Under the condition of dual-frequency ultrasonic waves, control the reaction temperature at 40 or 43 or 45 °C, and in this embodiment, control the reaction temperature at 43 °C.

[0068] The pH value is 6.0 or 6.3 or 6.5, and in this embodiment, the pH value is 6.3; carry out an enzymatic hydrolysis reaction for 2 or 2.5 or 3 hours, and in this embodiment, carry out an enzymatic hydrolysis reaction for 2.5 hours.

[0069] The synergistic effect of dual-frequency ultrasonic waves promotes the contact between the enzyme and the substrate. Meanwhile, the ionic liquid medium regulates the microenvironment of the enzyme, enabling the enzyme to maintain its activity at a higher temperature and reducing the product inhibition effect. Through the synergistic effect of dual-frequency ultrasound and ionic liquid, the enzymatic reaction rate is increased by 3-4 times compared with the traditional process, the enzyme dosage is reduced by more than 50%, and the lactose conversion rate reaches more than 99.5%.

[0070] 3. Magnetic-responsive molecular sieve separation

[0071] 3.1 Preparation of magnetic-responsive molecular sieve

[0072] The magnetic-responsive molecular sieve material is prepared by the following steps:

[0073] (1) Mix Fe 3 O 4 magnetic nanoparticles (average particle size 50-100 nm) and a molecular sieve carrier (mainly composed of mesoporous silicon material) in a ratio of 1:5 (w / w);

[0074] (2) Uniformly disperse Fe 3 O 4 nanoparticles on the molecular sieve carrier by the impregnation-coprecipitation method;

[0075] (3) After drying and activation treatment, a molecular sieve material with magnetic-responsive performance is obtained.

[0076] 3.2 Magnetic field regulation separation system

[0077] By designing a variable magnetic field separation system, the dynamic regulation of the molecular sieve pore size is achieved by adjusting the external magnetic field strength (0.1-0.5 T). Different from traditional fixed-pore-size molecular sieves, under the action of magnetic fields with different intensities, the magnetic nanoparticles in the magnetic-responsive molecular sieve will produce displacements of different degrees, thereby causing the deformation of the molecular sieve framework and realizing the controllable adjustment of the pore size (the pore size change range is about 0.5-2.0 nm). This characteristic enables it to adjust the separation selectivity according to the separation requirements, providing technical support for the separation of lactose and its degradation products.

[0078] Among them, the external magnetic field strength is 0.1 or 0.3 or 0.5 T, and in this embodiment, the external magnetic field strength is 0.3 T;

[0079] The pore size change range of the magnetic-responsive molecular sieve is 0.5 or 1.0 or 2.0 nm, and in this embodiment, the pore size change range of the magnetic-responsive molecular sieve is 1.0 nm;

[0080] 3.3 Separation operation process

[0081] The products after enzymatic hydrolysis are separated through the following steps: (1) First, the reaction solution after enzymatic hydrolysis is heat-treated at 65 - 70 °C for 10 minutes to inactivate the enzyme; (2) After cooling to room temperature, it passes through a magnetic-responsive molecular sieve separation column at a flow rate of 5 - 8 mL / min; (3) According to the requirements of the separation object, the pore size of the molecular sieve is controlled by adjusting the externally applied magnetic field strength; (4) Utilizing the molecular size difference between lactose (molecular weight about 342 Da) and its degradation products galactose and glucose (molecular weight about 180 Da), selective separation is achieved; (5) The effluent is collected and the residual lactose content is detected to ensure that the 0-lactose standard (lactose content ≤ 0.01%) is reached.

[0082] This separation technology realizes dynamic pore size changes through magnetic field regulation, reducing the phenomena of easy blockage and single selectivity of traditional fixed-pore molecular sieves; at the same time, the magnetic properties make the molecular sieve easy to regenerate and recycle, improving the separation efficiency and material utilization rate.

[0083] 4. Recycling and regeneration of ionic liquids

[0084] 4.1 Phase transformation cycle purification process

[0085] The specific operation is as follows:

[0086] (1) The separated mixed liquid containing ionic liquid is collected, and the temperature is controlled to rise to 32 or 33 or 35 °C. In this embodiment, the temperature is controlled to rise to 33 °C;

[0087] (2) In this temperature range, the ionic liquid system undergoes reversible phase separation, forming an ionic liquid-rich phase and an ionic liquid-lean phase;

[0088] (3) Due to the interfacial tension difference, most macromolecular impurities such as fats and proteins accumulate at the phase interface;

[0089] (4) Through liquid separation operation, the ionic liquid-rich phase is separated from the interfacial impurity layer.

[0090] This temperature-induced phase transformation process is based on the thermosensitive phase behavior of ionic liquids. Different from traditional physical adsorption or chemical precipitation methods, this method does not require additional additives, and preliminary separation of impurities can be achieved through temperature regulation, reducing ionic liquid loss and improving the recovery efficiency.

[0091] 4.2 Biological enzyme self-cleaning treatment

[0092] For the organic impurities remaining in the ionic liquid, a biocatalytic self-cleaning process is introduced: (1) Add a degrading enzyme system to the recycled ionic liquid-rich phase, including a combination of lipase (activity ≥ 100 U / mg) and protease (activity ≥ 200 U / mg), with an addition amount of 0.01 - 0.02% (w / v); (2) Control the reaction temperature at 37 - 40 °C, pH value at 7.0 - 7.5, and reaction time at 1 - 2 hours; (3) After the enzymatic reaction, raise the temperature of the reaction solution to 65 - 70 °C to inactivate the enzyme; (4) Remove the degradation products and inactivated enzyme proteins by filtration.

[0093] This process step uses the enzyme system to selectively degrade the fats and proteins remaining in the ionic liquid, forming smaller molecular products that are easier to remove. Compared with traditional chemical cleaning methods, this method has the characteristics of high selectivity, mild conditions, and environmental friendliness.

[0094] 4.3. Conversion and treatment of sugar impurities

[0095] To address the possible cross-contamination between batches caused by trace amounts of lactose degradation products (galactose, glucose) remaining in the ionic liquid, a biotransformation process step is designed: (1) Add a combined enzyme system of glucose oxidase (activity ≥ 150 U / mg) and galactose oxidase (activity ≥ 100 U / mg) to the ionic liquid treated by the enzyme self-cleaning process, with an addition amount of 0.01 - 0.02% (w / v); (2) Control the reaction temperature at 30 - 35 °C, pH value at 6.0 - 7.0, and reaction time at 1 - 1.5 hours; (3) The enzymatic reaction oxidizes and converts the remaining monosaccharides into the corresponding aldonic acids (glucuronic acid and galacturonic acid); (4) Utilize the solubility difference between the aldonic acid and the ionic liquid to adjust the pH value to 4.5 - 5.0 to form a precipitate of the aldonic acid sodium salt; (5) Filter to remove the precipitate to obtain a high-purity regenerated ionic liquid.

[0096] This step converts sugars into aldonic acids that are easy to separate through enzymatic catalytic reactions, and uses their solubility characteristics to achieve separation from the ionic liquid, avoiding cross-contamination between batches.

[0097] 5. Subsequent processing

[0098] 5.1. Concentration

[0099] The 0-lactose goat milk emulsion after separation by magnetic-responsive molecular sieves is concentrated using a multi-effect evaporator or vacuum concentration equipment, and the total solid content is concentrated from about 12% to 45 - 50%. This step controls the concentration temperature not to exceed 70 °C to protect the nutritional components of the product.

[0100] 5.2. Formulation and preparation

[0101] According to the product formula requirements, vitamins, minerals, prebiotics (such as fructooligosaccharides, galactooligosaccharides, etc.) and other functional ingredients are added to the concentrated lactose-free goat milk and homogenized and mixed. This step depends on the product type and the needs of the target population.

[0102] 5.3. Spray Drying

[0103] The prepared mixture is spray-dried, with the inlet temperature controlled at 170 - 180 °C and the outlet temperature controlled at 75 - 85 °C to obtain powdered lactose-free formulated goat milk powder. This step uses the drying process in the dairy industry to ensure the sensory quality and solubility of the product.

[0104] 5.4. Packaging and Quality Control

[0105] The final product is subjected to standardized packaging and quality control inspections, including the detection of parameters such as physical and chemical indicators, microbial indicators, and residual lactose content, to ensure that the product meets the quality standard requirements. This step is carried out in accordance with industry standard specifications.

[0106] Experimental Examples

[0107] Experimental Example 1: Enzymatic Hydrolysis Efficiency and Cost Verification Experiment

[0108] 1.1 Experimental Purpose

[0109] Verify the effects of the dual-frequency ultrasound-ionic liquid synergistic enzymatic hydrolysis technology on enzymatic hydrolysis time, enzyme utilization rate, and enzyme dosage.

[0110] 1.2 Experimental Materials and Equipment

[0111] Goat milk: Fresh goat milk with a fat content of 3.2% and a protein content of 3.1%;

[0112] β-Galactosidase: Activity 3500 U / g;

[0113] Ionic liquid: 1-butyl-3-methylimidazolium tetrafluoroborate;

[0114] Dual-frequency ultrasound equipment: Can generate 25 kHz and 90 kHz ultrasonic waves simultaneously;

[0115] Lactose content determination equipment: High-performance liquid chromatograph;

[0116] Enzyme activity determination equipment: Spectrophotometer

[0117] 1.3 Experimental Method

[0118] Control group A: Traditional aqueous enzymatic hydrolysis 1. Pasteurize the standardized goat milk at 60 °C for 15 minutes and cool it to 42 °C. 2. Add β-galactosidase with an addition amount of 0.15% (w / v). 3. Let it stand for enzymatic hydrolysis at 42 °C without ultrasonic assistance. 4. Take samples every 1 hour to measure the lactose conversion rate until it reaches ≥99%;

[0119] Control group B: Single-frequency ultrasonic-assisted enzymatic hydrolysis 1. Pasteurize the standardized goat milk at 60 °C for 15 minutes and cool it to 42 °C. 2. Add β-galactosidase with an addition amount of 0.10% (w / v). 3. Conduct single-frequency ultrasonic (25 kHz, power density 0.3 W / cm 3 )-assisted enzymatic hydrolysis at 42 °C. 4. Take samples every 1 hour to measure the lactose conversion rate until it reaches ≥99%;

[0120] Experimental group: Dual-frequency ultrasonic-ionic liquid synergistic enzymatic hydrolysis 1. Pasteurize the standardized goat milk at 60 °C for 15 minutes and cool it to 42 °C. 2. Add the ionic liquid [BMIM][BF4] aqueous solution with a final concentration of 1:4 (v / v). 3. Add β-galactosidase with an addition amount of 0.06% (w / v). 4. Conduct dual-frequency ultrasonic (25 kHz, 0.2 W / cm 3 and 90 kHz, 0.5 W / cm 3 )-assisted enzymatic hydrolysis at 42 °C. 5. Take samples every 30 minutes to measure the lactose conversion rate until it reaches ≥99%;

[0121] Enzyme reuse test: 1. After each group of enzymatic hydrolysis reactions is completed, inactivate part of the enzyme sample by heat treatment (65 °C, 10 minutes) for use as a control. 2. Recover the remaining enzyme by centrifugation (10000 rpm, 10 minutes). 3. Use the recovered enzyme for the next batch of enzymatic hydrolysis reactions. 4. Record the changes in enzyme activity after each batch of enzymatic hydrolysis and calculate the enzyme activity retention rate;

[0122] 1.4 Experimental results

[0123] Comparison of enzymatic hydrolysis time. The time required to reach 99% lactose conversion rate under different process conditions is shown in the following table:

[0124]

[0125] Comparison of enzyme utilization rate. The repeated use performance of β-galactosidase under different process conditions is shown in the following table:

[0126]

[0127] *Note: The maximum number of repeated uses is defined as the number of uses when the enzyme activity retention rate ≥30%.

[0128] Comparison of enzyme dosage and cost. The comparison of enzyme dosage and cost under different process conditions is shown in the following table:

[0129]

[0130] It can be seen from the experimental results that the dual-frequency ultrasound-ionic liquid synergistic enzymatic hydrolysis technology shortens the enzymatic hydrolysis time from the traditional 9.5 hours to 2.4 hours, which is only 25.3% of the traditional process; this technology significantly improves the stability of the enzyme, and 63.5% of the activity remains after the 10th use, and the maximum number of repeated uses reaches 12 times; considering the comprehensive effects of the reduction of enzyme dosage and the increase of the number of repeated uses, the enzyme cost of this technology is only 6.7% of the traditional process.

[0131] Experimental example 2: Product quality verification experiment

[0132] 2.1 Experimental purpose

[0133] Verify the influence of the magnetic-responsive molecular sieve separation technology on the residual lactose content, and the influence of the dual-frequency ultrasound-ionic liquid synergistic enzymatic hydrolysis technology on nutrient retention and sensory quality.

[0134] 2.2 Experimental materials and equipment

[0135] Goat milk: Fresh goat milk, with a fat content of 3.2% and a protein content of 3.1%;

[0136] β-galactosidase: Activity 3500 U / g;

[0137] Ionic liquid: 1-butyl-3-methylimidazolium tetrafluoroborate;

[0138] Dual-frequency ultrasound equipment: Can generate 25 kHz and 90 kHz ultrasonic waves simultaneously;

[0139] Magnetic-responsive molecular sieve: Fe 3 O 4 -mesoporous silicon material prepared according to the implementation manner;

[0140] Adjustable magnetic field separation system: Magnetic field strength 0.1 - 0.5 T;

[0141] High-performance liquid chromatograph: Used for lactose content determination;

[0142] Bioactive substance analysis equipment: ELISA plate reader, electrophoresis system;

[0143] Sensory evaluation equipment: Standardized sensory evaluation room;

[0144] 2.3 Experimental method

[0145] Product purity test: 1. Process goat milk using three processes: traditional gel filtration, single-frequency ultrasound + gel filtration, and dual-frequency ultrasound-ionic liquid + magnetic-responsive molecular sieve respectively. 2. Determine the residual lactose content of the processed samples: - Method A: Enzymatic assay (D-galactose dehydrogenase method) - Method B: High-performance liquid chromatography (HPLC). 3. Conduct three repeated measurements on each group of samples.

[0146] Nutrient retention test: 1. Analyze the nutrient components of the original goat milk and the samples processed by three different processes: - Determine the content of immunoglobulin (IgG): ELISA method - Determine the content of lactoferrin: Immunoturbidimetry - Determine the content of whey protein: Image analysis after SDS-PAGE electrophoresis. 2. Calculate the retention rate of each nutrient component (content after treatment / original content × 100%).

[0147] Sensory quality test: 1. Spray-dry the 0-lactose goat milk prepared by three processes according to the standard process to make milk powder. 2. Reconstitute it into liquid milk with warm water at 40°C in a ratio of 1:7. 3. Conduct blind sample evaluations by 10 trained sensory evaluators, and the evaluation indicators include: - Sweetness (0-10 points) - Bitterness (0-10 points) - Mouthfeel uniformity (0-10 points) - Comprehensive mouthfeel (0-10 points).

[0148] 2.4 Experimental results

[0149] Comparison of residual lactose content. The residual lactose content after different processes is shown in the following table:

[0150]

[0151] * Note: The passing rate refers to the proportion of batches with a residual lactose content ≤ 0.01% in the samples;

[0152] Comparison of nutrient component retention rates. The nutrient component retention rates after different processes are shown in the following table:

[0153]

[0154] Sensory quality evaluation results. The sensory evaluation results of the products prepared by different processes are shown in the following table:

[0155]

[0156] * Note: The lower the bitterness score, the better;

[0157] Comparison chart of residual lactose content and traditional separation methods is as Figure 1 shown.

[0158] It can be seen from the experimental results that the residual lactose content of the product prepared by the dual-frequency ultrasound-ionic liquid + magnetic-responsive molecular sieve process is significantly reduced, with an average value of only 0.005%, far lower than the standard limit of 0.01%, and the compliance rate reaches 100%; this process has a significant protective effect on the bioactive substances in goat milk, with an average retention rate of 85.9%, which is 21.3 percentage points higher than that of the traditional process; in terms of sensory quality, the bitterness of the product prepared by this process is significantly reduced, and the taste uniformity and comprehensive taste both receive high scores, indicating that its sensory quality is superior to that of the traditional process.

[0159] Experimental Example 3: Process Continuity Verification Experiment

[0160] 3.1 Experimental Purpose

[0161] Verify the influence of the phase transformation cycle purification-bioenzyme self-cleaning process on the recycling efficiency of ionic liquids and the long-term stability of magnetic-responsive molecular sieves.

[0162] 3.2 Experimental Materials and Equipment

[0163] Ionic liquid: 1-butyl-3-methylimidazolium tetrafluoroborate;

[0164] Magnetic-responsive molecular sieve: Fe prepared according to the implementation mode 3 O 4 -mesoporous silicon material;

[0165] Lipase: Activity 120 U / mg;

[0166] Protease: Activity 250 U / mg;

[0167] Glucose oxidase: Activity 180 U / mg;

[0168] Galactose oxidase: Activity 130 U / mg;

[0169] Molecular sieve pore size determination equipment: Nitrogen adsorption instrument;

[0170] Ionic liquid purity analysis equipment: Ion chromatograph, HPLC system;

[0171] Impurity analysis equipment: Total organic carbon analyzer;

[0172] Continuous industrial simulation equipment: Equipped with a temperature control system and a phase separation system.

[0173] 3.3 Experimental Method

[0174] Ionic liquid recycling experiment: 1. Prepare three groups of ionic liquid systems: - Control group A: Ionic liquid without any treatment process, directly recycled - Control group B: Ionic liquid treated by simple filtration, recycled - Experimental group: Ionic liquid treated by phase conversion cyclic purification - biocatalyst self-cleaning process 2. Simulate the actual production environment, and each group of ionic liquids is continuously used for 10 batches: - After each batch is used, analyze the recovery rate, purity and impurity content of the ionic liquid - Conduct lactase hydrolysis reaction under the same conditions for each batch, and detect the product quality 3. Track and record the performance changes of each group of ionic liquids in 10 batches

[0175] Inter-batch cross-contamination test: 1. During the recycling process of ionic liquids, measure the transfer of key indicators between batches: - Residual amount of lactose and its degradation products - Residual amount of protein - Residual amount of fat 2. Calculate the inter-batch cross-contamination rate (content of characteristic substances of the previous batch detected in the subsequent batch)

[0176] Separation material stability test: 1. Compare the long-term use stability of three separation materials: - Traditional gel filtration material - Ordinary molecular sieve without magnetic response modification - Magnetic response molecular sieve 2. Continuously use for 50 batches, and detect once every 10 batches: - Separation efficiency (residual lactose content) - Pore size stability (measured by nitrogen adsorption method) - Material integrity (observed by microscope) - Flow rate change (flow rate change under the same pressure)

[0177] 3.4 Experimental results

[0178] 3.4.1 Ionic liquid recovery rate and purity

[0179] The performance changes of ionic liquids continuously used for 10 batches under different treatment processes are shown in the following table:

[0180]

[0181] 3.4.2 Inter-batch cross-contamination situation

[0182] The inter-batch cross-contamination rates (%) under different treatment processes are shown in the following table:

[0183]

[0184] 3.4.3 Comparison of separation material stability

[0185] The performance changes of different separation materials continuously used for 50 batches are shown in the following table:

[0186]

[0187] The performance tracking diagram of continuous use of ionic liquids is as Figure 2 shown

[0188] It can be seen from the experimental results that for the ionic liquid treated by the phase inversion cycle purification - bio - enzyme self - cleaning process, after 10 consecutive batches of use, it still maintains a recovery rate of 91.7% and a purity of 95.4%. While for the untreated group and the simple filtration group, they decreased to 58.6% / 55.3% and 65.7% / 62.8% respectively; this process significantly reduces the inter - batch cross - contamination rate, and the total cross - contamination rate is only 0.5%, far lower than 12.2% of the untreated group and 7.8% of the simple filtration group; after 50 consecutive batches of use, the separation efficiency of the magnetic - responsive molecular sieve still remains at 89.6%, the flow rate retention rate is 83.4%, and its service life is 4.7 times that of traditional gel filtration materials and 2.2 times that of ordinary fixed - pore - size molecular sieves.

[0189] Experimental Example 4: Verification Experiment on Production Scale and Efficiency

[0190] 4.1 Experimental Purpose

[0191] Verify the advantages of the process of this embodiment in terms of production scale and efficiency compared with the traditional process, including the feasibility of continuous operation, processing capacity, and energy consumption status.

[0192] 4.2 Experimental Materials and Equipment

[0193] Pilot - scale production line: Processing capacity 100L / h;

[0194] Automation control system: Equipped with sensors for temperature, pressure, flow rate, etc.;

[0195] Continuous dual - frequency ultrasonic reactor: Effective volume 50L;

[0196] Continuous magnetic - responsive molecular sieve separation system: Equipped with an adjustable magnetic field device;

[0197] Ionic liquid recycling and regeneration system: Comprising a phase separation device and an enzyme treatment unit;

[0198] Energy consumption monitoring system: Monitoring devices for electric energy and heat energy consumption;

[0199] Data acquisition system: Sampling frequency 10Hz.

[0200] 4.3 Experimental Method

[0201] Continuous operation test: 1. Design production lines for three process flows respectively: - Traditional batch process: Batch operation, 100L per batch - Semi - continuous process: Some processes are continuous, and some processes are intermittent - Full - continuous process: Full - continuous process based on this embodiment 2. Each process flow runs continuously for 24 hours, and record: - Actual processing volume - Equipment downtime - Process switching time - Product consistency between batches

[0202] Processing capacity test: 1. Under the condition of equipment of the same scale, compare the processing capacities of three separation technologies: - Traditional gel filtration separation - Membrane separation technology - Magnetic-responsive molecular sieve separation 2. Based on the processing of 100 L of lactase hydrolysis product, record: - Time required to complete the separation - Separation efficiency (residual lactose content) - Equipment floor area - Operation complexity (number of operation steps required)

[0203] Energy consumption comparison test: 1. Compare the energy consumption of three process flows when producing the same amount of product: - Traditional process (enzymatic hydrolysis + gel filtration + conventional cleaning) - Improved process (single-frequency ultrasonic enzymatic hydrolysis + membrane separation + chemical cleaning) - Process of this embodiment (dual-frequency ultrasonic - ionic liquid enzymatic hydrolysis + magnetic-responsive molecular sieve + biocatalytic self-cleaning) 2. Monitor the energy consumption of each process link throughout the process: - Electrical energy consumption (kWh) - Thermal energy consumption (MJ) - Cooling energy consumption (MJ) - Compressed air energy consumption (m 3 ) 3. Calculate the total energy consumption and energy consumption per unit product comprehensively

[0204] 4.4 Experimental results

[0205] 4.4.1 Comparison of continuous operation performance

[0206] The continuous operation performance of different process flows (running for 24 hours) is shown in the following table:

[0207]

[0208] * Note: RSD is the relative standard deviation, used to measure the consistency between batches. The lower the value, the better the consistency

[0209] 4.4.2 Comparison of processing capacities

[0210] The comparison of the processing capacities of different separation technologies (processing 100 L of lactase hydrolysis product) is shown in the following table:

[0211]

[0212] 4.4.3 Comparison of energy consumption

[0213] The comparison of the energy consumption of different process flows (producing 1000 kg of product) is shown in the following table:

[0214]

[0215] The comparison chart of the output and continuity of different process flows is as Figure 3 shown;

[0216] The comparison chart of the energy consumption distribution of different process flows is as Figure 4 shown.

[0217] It can be seen from the experimental results that: the actual processing capacity of the fully continuous process in this embodiment reaches 2380L within 24 hours, which is 28.6% higher than that of the traditional batch process. The equipment downtime and process switching time are reduced by 78.6% and 83.8% respectively, and the consistency between product batches is significantly improved. The separation technology using magnetoresponsive molecular sieves has a processing capacity 3.1 times that of traditional gel filtration, with 58.3% fewer operation steps, and at the same time the separation efficiency is increased to 99.5%. The comprehensive energy consumption of the process in this embodiment is only 54.5% of that of the traditional process, and all energy consumption indicators are significantly reduced, among which the reduction in heat energy consumption and cooling energy consumption is the largest.

[0218] The embodiments of the present invention have been described above, but these embodiments are not limited to the above specific embodiments. The above specific embodiments are merely illustrative rather than restrictive. Under the inspiration of this embodiment, those of ordinary skill in the art can also make more equivalent embodiments in various forms, all of which fall within the protection scope of this embodiment.

Claims

1. A preparation process for lactose-free goat milk powder, characterized in that: The following steps are involved: Step 1: pre-treating goat milk to obtain a pre-treated emulsion; Step 2: in an ionic liquid medium, subjecting the pretreated emulsion to β-galactosidase enzymolysis treatment under dual-frequency ultrasonic conditions to obtain an enzymolysis product; Step 3: Separating the enzymatic hydrolysis product through a magnetic responsive molecular sieve, which dynamically controls the pore size through an external magnetic field to obtain zero-lactose goat milk; Step 4: Recover the ionic liquid through phase inversion cycle purification-bioenzyme self-cleaning process; Step 5: Perform subsequent processing on the 0-lactose goat milk to obtain 0-lactose formulated goat milk powder.

2. The process for preparing the lactose-free goat milk powder according to claim 1, characterized in that: The pretreatment in step 1 includes: filtration, standardization, low-temperature pasteurization and cooling, adjusting the fat content to 3.0-3.5%, the protein content to 3.0-3.2%, the pasteurization condition is 60-65°C for 15-20 minutes, and cooling to 40-45°C.

3. The preparation process of the lactose-free goat milk powder according to claim 1, characterized in that: In step 2, the ionic liquid medium is obtained by mixing 1-butyl-3-methylimidazolium tetrafluoroborate and water in a ratio of 1:4 (v / v).

4. The process for preparing the lactose-free goat milk powder according to claim 1, characterized in that: The dual-frequency ultrasound conditions in step 2 include: applying low-frequency 25kHz and high-frequency 90kHz ultrasound at the same time, with power densities of 0.2-0.3W / cm 3 and 0.5-0.6W / cm 3 .

5. The process for preparing the lactose-free goat milk powder according to claim 1, characterized in that: In step 2, the amount of β-galactosidase added is 0.05-0.08% (w / v), the enzymatic reaction temperature is 40-45° C., the pH value is 6.0-6.5, and the reaction time is 2-3 hours.

6. The process for preparing the lactose-free goat milk powder according to claim 1, characterized in that: In step 3, the magnetically responsive molecular sieve is prepared by the following method: (1) mixing Fe3O4 magnetic nanoparticles and mesoporous silicon material in a ratio of 1:5 (w / w); (2) Fe3O4 nanoparticles are uniformly dispersed on the mesoporous silicon material by impregnation-coprecipitation method; (3) After drying and activation treatment, a magnetic responsive molecular sieve material is obtained.

7. The process for preparing the lactose-free goat milk powder according to claim 1, characterized in that: In step 3, the strength of the external magnetic field is 0.1-0.5 T, and the pore size of the magnetically responsive molecular sieve varies in the range of 0.5-2.0 nm.

8. The process for preparing the lactose-free goat milk powder according to claim 1, characterized in that: The phase conversion cycle purification-biological enzyme self-cleaning process in step 4 includes the following steps: (1) phase-separating the mixed solution containing the ionic liquid at a temperature of 32-35° C.; (2) separating the ion-rich liquid phase; (3) adding lipase and protease to the ionic liquid-rich phase for self-cleaning treatment; (4) adding glucose oxidase and galactose oxidase to the treated ionic liquid to convert the residual monosaccharides into aldonic acid; (5) adjusting the pH value to 4.5-5.0 to precipitate sodium aldonic acid; (6) Filter and remove the precipitate to obtain the regenerated ionic liquid.

9. The process for preparing the lactose-free goat milk powder according to claim 8, characterized in that: In step 4, the lipase activity is ≥100 U / mg, the protease activity is ≥200 U / mg, the addition amount of both is 0.01-0.02% (w / v), the reaction temperature is 37-40°C, the pH value is 7.0-7.5, and the reaction time is 1-2 hours.

10. The process for preparing the lactose-free goat milk powder according to claim 8, characterized in that: In step 4, the glucose oxidase activity is ≥150 U / mg, the galactose oxidase activity is ≥100 U / mg, the addition amount of both is 0.01-0.02% (w / v), the reaction temperature is 30-35° C., the pH value is 6.0-7.0, and the reaction time is 1-1.5 hours.

Images