A method for preparing alpha-lactalbumin and related products and uses thereof

Abstract

The application discloses a preparation method of alpha-lactalbumin and related products and application thereof, and relates to the technical field of dairy product processing. The application provides a method for efficiently extracting alpha-lactalbumin by optimizing a heat treatment step with natural whey protein as a source. The method has the advantages of low cost, simple operation, large flux, high efficiency, high purity of obtained alpha-lactalbumin and the like, and the method is beneficial to maintaining the activity of alpha-lactalbumin. The obtained alpha-lactalbumin is rich in alpha-helix and has high similarity with the natural structure of alpha-lactalbumin. The application provides a new way for the industrialized separation and production of alpha-lactalbumin.

Description

Technical Field

[0001] This invention relates to the field of dairy processing technology, and more specifically, to a method for preparing α-lactalbumin and related products and applications. Background Technology

[0002] Whey protein is an important nutrient in whey. With the development of comprehensive whey utilization technology, many important functions of whey protein have been gradually discovered. Due to its high nutritional value, easy digestion and absorption, and excellent processing performance, it is widely used in infant formula, health products, and pharmaceuticals.

[0003] Alpha-lactalbumin is widely found in the milk of mammals and humans, and is one of the main components of whey. In cow's milk, the content of alpha-lactalbumin is approximately 1.2 g / L, accounting for 2%–3% of total milk protein; in breast milk, it accounts for 20%–25% of total protein, making it a major protein and a core protein ingredient in infant formula. For infants, alpha-lactalbumin is rich in tryptophan, which can be converted into the neurotransmitter serotonin in the body, promoting the maturation of neurons and synaptic connections, thereby improving infant sleep and enhancing learning and memory abilities. In addition, alpha-lactalbumin exhibits certain functional properties in terms of antibacterial, antioxidant, anticancer, and antitumor activities. Meanwhile, β-lactoglobulin is also an important protein in cow's milk whey, but it is not present in breast milk; therefore, for some infants, β-lactoglobulin is a major allergen. Therefore, to promote the humanization of infant formula, it is necessary to separate alpha-lactalbumin from β-lactoglobulin in cow's milk and purify alpha-lactalbumin.

[0004] Previous studies have shown that α-lactalbumin and β-lactoglobulin are highly similar in molecular weight (14KD and 18KD), isoelectric point (4.7 and 5.3), and hydrolysis characteristics, making them difficult to separate. Common separation methods include enzymatic hydrolysis, selective precipitation, membrane separation, and ion exchange. The first three methods suffer from low recovery rates, high costs, and low purity. In contrast, ion exchange offers higher purity and recovery rates, but has the limitation of low daily processing capacity.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing α-lactalbumin and related products and applications.

[0007] This invention is implemented as follows:

[0008] In a first aspect, embodiments of the present invention provide a method for preparing α-lactalbumin, comprising: obtaining a whey protein solution after removing casein from skim milk; subjecting the whey protein solution to heat treatment, the heat treatment comprising a preheating stage and a reaction stage; wherein, the preheating stage comprises: preheating the whey protein solution to a second set temperature, the second set temperature being 40~65°C, and holding at that temperature for 0~30 min; the reaction stage comprises: heating the product from the preheating stage to a third set temperature, the third set temperature being 90~110°C, and holding at that temperature for 1~120 s.

[0009] Secondly, embodiments of the present invention provide products prepared by the preparation method described in the foregoing embodiments.

[0010] Thirdly, embodiments of the present invention provide a composition whose active ingredient includes the product described in the foregoing embodiments.

[0011] Fourthly, embodiments of the present invention provide the application of the preparation method as described in the foregoing embodiments or the product as described in the foregoing embodiments in the preparation of food or health products.

[0012] The present invention has the following beneficial effects:

[0013] This invention provides a highly efficient extraction method for α-lactalbumin from natural whey protein through optimized heat treatment steps. This process has advantages such as low cost, simple operation, high throughput, high efficiency, and high purity of the obtained α-lactalbumin. Furthermore, this process helps maintain the activity of α-lactalbumin, and the obtained α-lactalbumin is rich in α-helices and has a high degree of similarity to the natural structure of α-lactalbumin. This invention provides a new approach for the industrial separation and production of α-lactalbumin. Attached Figure Description

[0014] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a process flow diagram for the preparation of α-lactalbumin. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0017] On one hand, embodiments of the present invention provide a method for preparing α-lactalbumin, which includes: obtaining a whey protein solution after removing casein from skim milk, and subjecting the whey protein solution to heat treatment, wherein the heat treatment includes a preheating stage and a reaction stage;

[0018] The preheating stage includes: preheating the whey protein solution to a second set temperature, which is 40~65℃, and holding it at that temperature for 0~30 minutes; the reaction stage includes: heating the product from the preheating stage to a third set temperature, which is 90~110℃, and holding it at that temperature for 1~120 seconds.

[0019] In an optional embodiment, the preparation method further includes: preparing whey protein solution after removing casein from skim milk.

[0020] In an optional embodiment, the preparation of the whey protein solution after removing casein from skim milk includes: microfiltration of skim milk to obtain a permeate and a retentate after microfiltration; ultrafiltration of the permeate after microfiltration to obtain the retentate as the whey protein solution after removing casein from skim milk.

[0021] In an optional embodiment, the pore size of the microfiltration membrane is 0.05~0.2 micrometers, specifically any one or any two of 0.05, 0.1, 0.15, and 0.2 micrometers. The temperature of the microfiltration can be 10~60℃, optionally 30~50℃; the transmembrane pressure difference of the microfiltration is controlled at 1~2 bar, optionally 1~1.6 bar, and the formula for calculating the transmembrane pressure difference is: .

[0022] In an optional embodiment, the volumetric concentration factor of the microfiltration is 2 to 5 times, specifically any one or any two of 2, 3, 4 and 5 times.

[0023] In an optional embodiment, the filter membrane of the microfiltration is a spiral wound membrane, a plate membrane, or a tubular membrane.

[0024] In optional embodiments, the molecule cutoff of the ultrafiltration membrane is 3~100kDa, optionally 5~30kDa, or optionally 10kDa; the ultrafiltration temperature is 10~25℃, optionally 15~20℃; the ultrafiltration concentration factor is 2~5 times, optionally 3 times; and the ultrafiltration membrane is a spiral wound membrane, a plate membrane, or a tubular membrane.

[0025] In an optional embodiment, the preparation further includes: washing the retentate after ultrafiltration, wherein the washing filtrate is RO water, and the washing ratio is 1 to 5 times the volume of skim milk, optionally 1 to 2 times. After washing, the preparation may further include concentrating the washed filtrate to achieve a protein concentration of 0.2% to 20% (w / v), optionally 1% to 20%, and a lactose content of less than 10 g / L, optionally less than 1 g / L.

[0026] In an optional embodiment, before the heat treatment, the preparation method further includes: adding calcium ions to the whey protein solution to a calcium content of 0.1~2 g / L, specifically any one or any two of the following: 0.1, 0.2, 0.4, 0.6, 0.8, 1, 1.2, 1.4, 1.6, 1.8, and 2 g / L. A 0.1~2 mol / L calcium chloride solution can be used for adding calcium ions. The concentration of calcium chloride can be 0.5~1.5 mol / L.

[0027] In an optional embodiment, before performing the heat treatment, the preparation method further includes: adjusting the pH of the whey protein solution to 6.3-8.5, specifically within any one or any two of the following ranges: 6.3, 6.4, 6.6, 6.8, 7, 7.2, 7.4, 7.6, 7.8, 8, 8.2, 8.4, and 8.5. The pH adjuster used for adjusting the pH can be a 0.1-2 mol / L hydrochloric acid solution and / or a 0.1-2 mol / L sodium hydroxide solution. The concentration of the hydrochloric acid solution and / or the sodium hydroxide solution can be 0.5-1.5 mol / L.

[0028] In an optional embodiment, before the preheating stage, the heat treatment further includes a preparation stage; the preparation stage includes: heating the whey protein solution to a first set temperature and holding it at that temperature for 0-60 minutes; the first set temperature is 15-40°C. The first set temperature can be any one or any two of the following: 15, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, and 40°C. The holding time can be any one or any two of the following: 0, 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, and 60 minutes.

[0029] In an optional embodiment, the second set temperature can be any one or a range between any two of 40, 42, 44, 45, 46, 48, 50, 52, 54, 55, 56, 58, 60, 62, 64 and 65°C.

[0030] In an optional embodiment, the heat preservation time of the preheating stage can be any one or any two of 0, 1, 5, 10, 15, 20, 25 and 30 min.

[0031] In an optional embodiment, the heating rate of the preheating stage is 5~20℃ / s, specifically any one or any two of 5, 6, 8, 10, 12, 14, 15, 16, 18 and 20℃ / s.

[0032] In an optional embodiment, the third set temperature can be any one or a range between any two of 90, 92, 94, 95, 96, 98, 100, 102, 104, 105, 106, 108 and 110°C.

[0033] In an optional embodiment, the holding time of the reaction stage is any one or any two of the following: 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115 and 120 s.

[0034] In an optional embodiment, the heating rate of the reaction stage is 5~30℃ / s, specifically any one or any two of 5, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28 and 30℃ / s.

[0035] In an optional embodiment, the reaction stage further includes: cooling the product after the reaction to 0~25°C, optionally 4~10°C, at a cooling rate of 20~50°C / s, optionally 30°C / s.

[0036] In an optional embodiment, the preparation method further includes: filtering the heat-treated product to obtain an α-lactalbumin solution and a β-lactoglobulin solution as the permeate;

[0037] In an optional embodiment, the pore size of the filter membrane is 50~500 nm, specifically any one or any two of 50, 100, 150, 200, 250, 300, 350, 400, 450 and 500 nm.

[0038] In optional embodiments, the filter membrane can be a spiral wound membrane, a plate membrane, a tubular membrane, or a rotary ceramic membrane. The filtration temperature can be 10~25℃, optionally 15~20℃; the concentration factor of the filtration can be 2~5 times, optionally 3 times.

[0039] In an optional embodiment, the preparation method further includes washing the filtered retentate, wherein the washing filtrate can be RO water, and the washing ratio is 3 to 6 times the volume of the retentate, optionally 4 to 5 times. The preparation method further includes concentrating the filtered permeate to achieve a protein concentration of 10% to 30% (w / w), optionally 15% to 25%.

[0040] In an optional embodiment, the preparation method further includes: ultrafiltration concentration of the α-lactalbumin solution to obtain a high-purity α-lactalbumin solution.

[0041] In an optional embodiment, the molecule cutoff of the ultrafiltration membrane is 3~30kDa, optionally 5~15kDa, and the concentration factor is 2~5 times, optionally 3 times.

[0042] In optional embodiments, the filter membrane for ultrafiltration concentration can be a spiral wound membrane, a plate membrane, or a tubular membrane. The ultrafiltration temperature can be 10-25°C, optionally 15-20°C.

[0043] In an optional embodiment, the ultrafiltration concentration further includes washing the obtained retentate, the washing filtrate being RO water, and the washing volume being 1 to 5 times the initial volume of the feed solution (the high-purity α-lactalbumin solution obtained after filtration), optionally 1 to 2 times; the washing filtrate further includes continuing to concentrate the ultrafiltration concentration of the retentate to make the protein concentration in the feed solution 5% to 30% (w / w), optionally 5% to 20%.

[0044] In an optional embodiment, the preparation method further includes drying the α-lactalbumin solution or the high-purity α-lactalbumin solution.

[0045] In an optional embodiment, the drying method is at least one of spray drying, electrostatic spray drying, low-temperature spray drying, or freeze drying.

[0046] In an optional embodiment, the high-purity α-lactalbumin solution or its dried product has an α-helical content of ≥58%.

[0047] In an optional embodiment, the high-purity α-lactalbumin solution or its dried product has an α-lactalbumin powder with a protein content ≥30%, an α-lactalbumin purity (as a percentage of total protein) ≥40%, a calcium content ≥1500mg / kg, a fat content ≤3%, a moisture content ≤6%, an ash content ≤5%, an impurity content ≤12mg / kg, and an insolubility index ≤0.1mL.

[0048] In an optional embodiment, the preparation method further includes filtering the high-purity α-lactalbumin solution using a 0.22-micron sterile filter to obtain a final high-purity α-lactalbumin solution with a protein content ≥5%, α-lactalbumin purity (as a percentage of total protein) ≥40%, α-helices in the α-lactalbumin ≥50%, calcium content ≥100 mg / kg, fat content <0.3%, and ash content ≤0.5%.

[0049] On the other hand, embodiments of the present invention provide products prepared by the preparation method described in any of the foregoing embodiments.

[0050] On the other hand, embodiments of the present invention provide a composition whose active ingredient includes the product described in any of the foregoing embodiments.

[0051] In optional embodiments, the composition further includes a pharmaceutically acceptable carrier. A pharmaceutically acceptable carrier includes, but is not limited to, any pharmaceutically acceptable excipient, carrier, adjuvant, additive, surfactant, desiccant, or diluent.

[0052] In optional embodiments, the composition may be a food or health product.

[0053] In an optional embodiment, the composition is milk powder.

[0054] Furthermore, embodiments of the present invention provide the application of the preparation method as described in any of the foregoing embodiments or the product as described in any of the foregoing embodiments in the preparation of food or health products.

[0055] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0056] Example 1

[0057] A method for preparing α-lactalbumin, comprising the following steps.

[0058] (1) Microfiltration

[0059] Skim milk was microfiltered using a 0.1-micron spiral wound membrane at a temperature of 50°C; the transmembrane pressure difference was controlled at 1 bar, and the concentration factor was 3 times; the retentate after microfiltration was washed with RO water at a ratio of 1.5 times the volume of skim milk. At this point, the permeate was natural whey protein and the retentate was casein.

[0060] (2) Ultrafiltration

[0061] The permeate (natural whey) from step (1) was ultrafiltered using a 10 kDa spiral wound membrane at a temperature of 10°C and a concentration factor of 3 times to obtain the permeate and retentate.

[0062] The retentate after ultrafiltration is washed with RO water at a ratio of 1:1 (the volume of skim milk in step (1)). After washing, the solution is further concentrated to achieve a protein concentration of 1.5% (w / w) and a lactose content of less than 1 g / L. At this point, the permeate is lactose solution and the retentate is concentrated whey protein solution.

[0063] (3) Calcium ions and pH adjustment

[0064] The concentrated whey protein solution in step (2) was adjusted to a calcium content of 1 g / L and a pH of 7.0 using a 1 mol / L calcium chloride solution, a 1 mol / L hydrochloric acid solution, or a 1 mol / L sodium hydroxide solution.

[0065] (4) Heat treatment

[0066] Preparation stage: Heat the concentrated whey protein solution with adjusted pH and calcium content from step (3) to the preparation temperature of 30°C and keep it warm for 20 minutes;

[0067] Preheating stage: rapidly heat to the preheating temperature of 50℃ at a rate of 15℃ / s, and hold for 5 minutes;

[0068] Reaction stage: Rapidly heat to the reaction temperature of 99℃ at a rate of 20℃ / s, and hold for 30 seconds;

[0069] After the reaction is complete, the temperature is lowered to 4°C at a rate of 30°C / s.

[0070] (5) Filtration

[0071] The concentrated whey protein solution after heat treatment in step (4) was filtered using a spiral wound membrane with a pore size of 75 nm and a membrane filtration temperature of 10 °C. The concentration factor was 2 times to obtain permeate and retentate. The retentate was washed with RO water and the washing factor was 5 times the volume of the concentrated solution. After washing, the solution was further concentrated to make the protein concentration in the solution 20% (w / w).

[0072] At this point, the permeate is a high-purity natural α-lactalbumin solution, and the retentate is a β-lactoglobulin solution.

[0073] (6) Ultrafiltration

[0074] The high-purity natural α-lactalbumin solution in step (5) was concentrated by ultrafiltration using a 10kDa spiral wound membrane at an ultrafiltration temperature of 10°C. The concentration factor was 3 times to obtain retentate and permeate. The retentate was washed and filtered with RO water at a washing factor of 1 times the initial volume of the feed solution (high-purity natural α-lactalbumin solution) in step (5). After washing and filtration, the feed solution was further concentrated to a protein concentration of 20% (w / w). At this point, the retentate obtained was high-purity natural α-lactalbumin solution.

[0075] (7) Drying

[0076] High-purity natural α-lactalbumin powder was obtained by spray drying the high-purity natural α-lactalbumin solution in step (6).

[0077] The process flow diagram can be referred to. Figure 1 .

[0078] Example 2

[0079] A method for preparing α-lactalbumin, largely the same as in Example 1, with the difference being:

[0080] Step (7): After filtering the high-purity natural α-lactalbumin solution from step (6) using a 0.22-micron sterile filter, the solution is aseptically bottled to obtain the α-lactalbumin solution.

[0081] Example 3

[0082] A method for preparing α-lactalbumin, largely the same as in Example 1, with the difference being:

[0083] The heat preservation time for the reaction stage in step (4) is 7 seconds.

[0084] Example 4

[0085] A method for preparing α-lactalbumin, largely the same as in Example 1, with the difference being:

[0086] The reaction temperature in step (4) is 104℃ and the holding time is 8s.

[0087] Example 5

[0088] A method for preparing α-lactalbumin, largely the same as in Example 1, with the difference being:

[0089] The reaction temperature in step (4) is 99℃, and the holding time is 60s.

[0090] Example 6

[0091] A method for preparing α-lactalbumin, largely the same as in Example 1, with the difference being:

[0092] The heating rate of the reaction stage in step (4) is 30℃ / s.

[0093] Example 7

[0094] A method for preparing α-lactalbumin, largely the same as in Example 1, with the difference being:

[0095] The heating rate of the reaction stage in step (4) is 5℃ / s.

[0096] Example 8

[0097] A method for preparing α-lactalbumin, largely the same as in Example 1, with the difference being:

[0098] The heating rate in the preheating stage of step (4) is 5℃ / s.

[0099] Example 9

[0100] A method for preparing α-lactalbumin, largely the same as in Example 1, with the difference being:

[0101] The temperature of the preheating stage in step (4) is 65°C.

[0102] Example 10

[0103] A method for preparing α-lactalbumin, largely the same as in Example 1, with the difference being:

[0104] The preparation stage has been omitted.

[0105] Example 11

[0106] A method for preparing α-lactalbumin, largely the same as in Example 1, with the difference being:

[0107] Step (3) has been omitted.

[0108] Comparative Example 1

[0109] A method for preparing α-lactalbumin, largely the same as in Example 1, with the difference being:

[0110] The reaction stage in step (4) has been omitted.

[0111] Comparative Example 2

[0112] A method for preparing α-lactalbumin, largely the same as in Example 1, with the difference being:

[0113] The reaction temperature in step (4) is 80℃.

[0114] Experimental Example 1

[0115] The products of Examples 1-11 and Comparative Examples 1-2 were tested.

[0116] Total solids and moisture were determined according to Method 1 of GB 5009.3-2016; ash content was determined according to Method 1 of GB 5009.4-2016; protein content was determined according to Method 1 of GB 5009.5-2016; and the contents of α-lactalbumin and β-lactoglobulin were determined using high performance liquid chromatography-tandem triple quadrupole mass spectrometry (UHPLC-MS / MS) under the following conditions:

[0117] Chromatographic column: Acquity UPLC BEH 300 C18 column (particle size 1.7μm, 2.1×100mm)

[0118] Chromatographic conditions: Mobile phase A was 0.1% formic acid aqueous solution, and mobile phase B was acetonitrile aqueous solution containing 0.1% formic acid. The injection volume was 5 μL, and the column temperature was 40°C. The LC elution gradient program was as follows: initially, 5% mobile phase B was held for 1.2 min, then the linear gradient was increased to 60% mobile phase B within 1.8 min, then to 80% mobile phase B within 1 min, and then to 100% mobile phase B within 0.2 min. The system was then equilibrated at 100% mobile phase B for 1.4 min, and then returned to 5% mobile phase B within 2.2 min. The total run time for each injection was 8 min.

[0119] Ion source: Electrospray ionization (ESI);

[0120] Mass spectrometry conditions: capillary voltage 3.50 kV, cone voltage 30 V, source temperature 150°C, desolvation gas temperature 350°C, cone gas flow rate 50 L / h nitrogen, desolvation gas flow rate 900 L / h nitrogen, argon collision gas pressure 3 × 10⁻⁶ for MS / MS analysis. -3 mbar;

[0121] Calculate the purity of α-La (α-lactalbumin) and β-Lg (β-lactoglobulin) using the following formula:

[0122] ;

[0123] ;

[0124] Where x represents the purity of α-La and y represents the purity of β-Lg.

[0125] α-helix content was determined using circular dichroism spectroscopy. The specific method was as follows: Heat-treated samples were diluted to a protein concentration of 0.1–0.2 mg / mL, and the protein concentration was measured using a BCA kit. The samples were placed in a 1 mm quartz sample cell, with pure water as a control. The circular dichroism of the samples was determined using a circular dichroism spectroscopy instrument, yielding far-UV CD spectra. The scanning wavelength range was 190 nm to 260 nm, with a bandwidth of 1 nm, and the testing temperature was 25 °C. The protein concentration and scanning results were imported into the DicroWeb website to calculate the content of α-helices, β-sheets, β-turns, and random coils.

[0126] The results are as follows.

[0127] Table 1. Detection results of Example 1

[0128]

[0129] Table 2 Detection results of Example 2

[0130]

[0131] Table 3. Detection results of Example 3

[0132]

[0133] The results show that when the reaction temperature is 99℃ and the reaction time is 7s, the purity and extraction rate of α-lactalbumin decrease.

[0134] Table 4. Detection results of Example 4

[0135]

[0136] The results show that a reaction temperature of 104℃ and a reaction time of 8s significantly improved the purity of α-lactalbumin, but reduced the extraction rate.

[0137] Table 5. Detection results of Example 5

[0138]

[0139] When the reaction time was 60s, the purity of α-lactalbumin was greatly improved, but the extraction rate was greatly reduced, and the α-helix content was also reduced.

[0140] Table 6. Detection results of Example 6

[0141]

[0142] A heating rate of 30℃ / s has little impact on the experimental results.

[0143] Table 7 Detection results of Example 7

[0144]

[0145] When the heating rate during the reaction stage was 5℃ / s, the purity of α-lactalbumin was improved, but the extraction rate decreased.

[0146] Table 8 Detection results of Example 8

[0147]

[0148] The heating rate of 5℃ / s during the preheating stage has little effect on the purity and α-helix content of α-lactalbumin.

[0149] Table 9. Detection results of Example 9

[0150]

[0151] The preheating temperature of 65℃ caused a decrease in the extraction rate of α-lactalbumin.

[0152] Table 10 Detection results of Example 10

[0153]

[0154] By omitting the preparation stage, the purity of α-lactalbumin increased, but the extraction rate and α-helix content decreased, and the separation efficiency was greatly reduced in the subsequent step (5) filtration stage.

[0155] Table 11 Detection results of Example 11

[0156]

[0157] Step (3) was omitted, resulting in a decrease in the extraction rate of α-lactalbumin and the content of α-helices.

[0158] Table 12 Detection results of Comparative Example 1

[0159]

[0160] Omitting the reaction stage in step (4) will prevent the effective separation of α-lactalbumin and β-lactoglobulin.

[0161] Table 13 Detection results of Comparative Example 2

[0162]

[0163] The reaction temperature in step (4) is 80℃, which limits the separation effect of α-lactalbumin and β-lactoglobulin.

[0164] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing α-lactalbumin, characterized in that, It includes: Obtain a whey protein solution after removing casein from skim milk, and subject the whey protein solution to heat treatment, the heat treatment including a preheating stage and a reaction stage; The preheating stage includes: preheating the whey protein solution to a second set temperature, which is 40~65℃, and holding it at that temperature for 1~15 minutes. The reaction stage includes: heating the product from the preheating stage to a third set temperature, which is 96~102℃, and holding it at that temperature for 25~35s; the heating rate of the reaction stage is 5~22℃ / s. Before the preheating stage, the heat treatment also includes a preparation stage; the preparation stage includes: heating the whey protein solution to a first set temperature and holding it at that temperature for 5 to 60 minutes; the first set temperature is 15 to 40°C. Before the heat treatment, the preparation method further includes: adding calcium ions to the whey protein solution to a calcium content of 0.5~1.5 g / L, and adjusting the pH of the whey protein solution to 6.6~7.

4.

2. The preparation method according to claim 1, characterized in that, The second set temperature is 45~55℃.

3. The preparation method according to claim 1, characterized in that, The heating rate during the preheating stage is 5~20℃ / s.

4. The preparation method according to claim 1, characterized in that, The third set temperature is 98~100℃.

5. The preparation method according to any one of claims 1 to 4, characterized in that, The preparation method further includes filtering the heat-treated product to obtain an α-lactalbumin solution and a β-lactoglobulin solution as the permeate.

6. The preparation method according to claim 5, characterized in that, The filtration membrane has a pore size of 50~500 nm.

7. The preparation method according to claim 5, characterized in that, The preparation method further includes: ultrafiltration concentration of the α-lactalbumin solution to obtain a high-purity α-lactalbumin solution.

8. The preparation method according to claim 7, characterized in that, The ultrafiltration membrane has a molecular cutoff of 3-30 kDa and a concentration factor of 2-5 times.

9. The preparation method according to claim 7, characterized in that, The preparation method further includes drying the α-lactalbumin solution or the high-purity α-lactalbumin solution.

10. The preparation method according to claim 7, characterized in that, The high-purity α-lactalbumin solution or its dried product has an α-helix content of ≥58%.

11. The preparation method according to any one of claims 1 to 4, characterized in that, The preparation of the whey protein solution after removing casein from skim milk includes: Skim milk is microfiltered to obtain permeate and retentate after microfiltration; The permeate after microfiltration is subjected to ultrafiltration, and the retentate obtained is the whey protein solution obtained after removing casein from the skim milk.

12. The preparation method according to claim 11, characterized in that, The pore size of the microfiltration membrane is 0.05~0.2 micrometers.

13. The preparation method according to claim 11, characterized in that, The ultrafiltration membrane has a molecular cutoff of 3~100kDa.

14. A composition, characterized in that, Its active ingredients include the products prepared by the preparation method according to any one of claims 1 to 13.

15. The preparation method according to any one of claims 1 to 13 or the composition according to claim 14 in the preparation of food or health products.

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