Separation method of soybean whey protein in yellow serofluid and whey protein product

Abstract

The invention discloses a separation method of soybean whey protein in yellow serofluid and a whey protein product, the separation method is carried out by using a foam separation device, the foam separation device comprises a foam separation column, the foam separation column is obliquely arranged, the top of the foam separation column is opened, and the bottom of the foam separation column is provided with an air inlet and a discharge valve; the foam separating device further comprises a foam collecting bottle used for collecting foam flowing out of the top opening of the foam separating column. The method for separating the soybean whey protein in the yellow serofluid comprises the following steps: diluting the yellow serofluid with water, and adjusting the pH value of the yellow serofluid to obtain yellow serofluid; carrying out homogenization treatment on the yellow slurry; and injecting the homogenized yellow serofluid into a foam separation column, and introducing air, so that the yellow serofluid generates foam, the foam flows out from an opening in the top of the foam separation column and flows into a foam collection bottle, and the soybean whey protein separated from the yellow serofluid is obtained. The soybean whey protein in the yellow serofluid can be efficiently separated, and the structure and the function of the soybean whey protein are not obviously influenced.

Description

Technical Field

[0001] The invention relates to the technical field of food processing, and in particular to a method for separating soybean whey protein in yellow pulp water and a whey protein product. Background Art

[0002] Yellow pulp water is wastewater generated during the production and processing of soy products. It is slightly yellow in color and contains a variety of trace active substances. It is very easy to deteriorate and has a peculiar smell. It is a typical high-concentration organic wastewater. With the acceleration of the industrial utilization of soybeans in my country, the output of soybean processing by-products has increased year by year. Among them, yellow pulp water is the main liquid by-product in the processing of soy products. The cost of harmless treatment is extremely high. Any discharge will cause serious environmental pollution, such as water quality deterioration or soil environmental pollution caused by biodegradation. Yellow pulp water is rich in protein, sugars and minerals, and also contains high-value organic substances such as soybean isoflavones. The recycling and reuse of these substances can not only reduce the cost of wastewater treatment and reduce environmental pollution, but also extend the soybean industry chain, bringing objective economic benefits to soybean food production companies.

[0003] Yellow slurry contains abundant bioactive substances such as soy whey protein. It is considered to be a functional food raw material with high potential due to its good processing characteristics, such as foaming and emulsifying properties. However, the concentration of soy whey protein in yellow slurry is low, and traditional separation technologies, such as flocculation and membrane treatment, have problems such as low efficiency, high cost or complex operation when dealing with low-concentration proteins. In addition, these methods may have adverse effects on the structure and function of soy whey protein, limiting its application in food and medicine.

[0004] The foam separation method uses the adsorption principle to pass gas into the solution to make the surfactant in it form bubbles, and collect the foam discharged from the separation column to achieve the separation and enrichment of the target substance. This method has the advantages of being green, environmentally friendly, low cost, and easy to operate. At the same time, the treatment process has little damage to the structure of macromolecules such as proteins in the solution, so it is considered to be used for the separation and enrichment of soy whey protein in yellow slurry water. However, in yellow slurry water, some soy whey proteins will form aggregates, which will affect its foaming performance and the efficiency of foam separation.

[0005] At present, there are reports that the foam separation of soybean protein wastewater can only separate whey protein in China. The document "Foam Separation Experiment of Whey Protein in Soybean Protein Wastewater" (Yang Xiangping, Liu Yuandong, Qin Hailiang, Xi Zuojia, "Chemical Industry Progress" 2008 (1): 92-97) reported the foam separation experiment of whey protein in soybean protein wastewater, studied the influence of factors such as pH, gas flow rate, feed concentration, liquid column and broken film layer height on the whey protein separation effect, and even under the optimal experimental conditions, the recovery rate of whey protein by foam separation was only 48.5%. Patent "Separation and Preparation Method of Protein in Soybean Protein Wastewater" (Publication No. CN103549111A, Publication Date February 5, 2014) discloses a separation and preparation method of protein in soybean protein wastewater, which relates to a method for separating protein in soybean wastewater by two-stage foam separation technology. Although the recovery rate of this method can reach more than 90%, the processing time is long and the operation is complicated. Summary of the invention

[0006] In view of the above technical problems, the present invention provides a separation method for recovering soybean whey protein from yellow pulp water with high efficiency, low cost and little damage to the structure of soybean whey protein.

[0007] The technical principle of the present invention is as follows: after diluting yellow slurry water with water and adjusting the pH value, high-speed shear homogenization treatment is performed to form strong hydraulic shear and turbulence so that the material is fully dispersed and homogenized; the homogenized yellow slurry water is then injected into a foam separation column, air is introduced to generate foam in the yellow slurry water in the foam separation column, and the foam flows out from the top of the foam separation column, and the foam flowing out from the top of the foam separation column is collected by a foam collection bottle to separate and obtain high-purity soybean whey protein.

[0008] Specifically, the present invention provides a method for separating soy whey protein from yellow slurry water, wherein the method for separating soy whey protein from yellow slurry water is performed using a foam separation device, wherein the foam separation device comprises a foam separation column, wherein the foam separation column is arranged in an inclined manner so that the center line of the foam separation column forms a preset angle A with the horizontal direction, the top of the foam separation column is arranged in an open manner, and the bottom of the foam separation column is provided with an air inlet and a discharge valve, and the foam separation device further comprises a foam collection bottle, wherein the foam collection bottle is used to collect foam flowing out of the top opening of the foam separation column;

[0009] The method for separating soybean whey protein in yellow pulp water comprises the following steps:

[0010] Firstly, dilute the yellow slurry with water and adjust its pH value to obtain yellow slurry;

[0011] The yellow slurry is subjected to high-speed shear homogenization treatment by a high-speed shear homogenizer, wherein the speed of the high-speed shear homogenizer is 2500-7500 r / min, and the homogenization treatment time is 30-40 s;

[0012] The homogenized yellow slurry is injected into a foam separation column, and air is introduced into the foam separation column to generate foam in the yellow slurry water in the foam separation column and flow out from the top opening of the foam separation column and into a foam collecting bottle. The foam in the foam collecting bottle is defoamed to obtain the soy whey protein separated from the yellow slurry water.

[0013] Optionally, the step of first diluting the yellow slurry water with water and adjusting its pH value to obtain the yellow slurry comprises:

[0014] Adding purified water to the yellow slurry to dilute the yellow slurry to a concentration of soy whey protein of 1.3 to 1.6 g / L, to obtain a dilution;

[0015] The pH value of the dilution solution is adjusted to 5.0-5.5 to obtain a yellow slurry.

[0016] Optionally, in the step of subjecting the yellow slurry to high-speed shear homogenization treatment using a high-speed shear homogenizer:

[0017] The rotation speed of the high-speed shear homogenizer is 5000r / min.

[0018] Optionally, the step of injecting the homogenized yellow slurry into a foam separation column:

[0019] The liquid volume of the foam separation column is 10-20% of the total volume of the foam separation column.

[0020] Optionally, in the step of introducing air into the foam separation column:

[0021] The air intake flow rate is 100-300 mL / min.

[0022] Optionally, in the step of injecting the homogenized yellow slurry into a foam separation column and introducing air into the foam separation column:

[0023] The liquid volume of the foam separation column is 15% of the total volume of the foam separation column;

[0024] The air flow rate is 150 mL / min.

[0025] Optionally, the preset angle A has an angle range of 55 to 65 degrees.

[0026] Optionally, the ratio of the inner diameter to the height of the foam separation column is 1:3-4.

[0027] Optionally, the foam separation device further comprises an air intake pipeline, which is connected to the air inlet of the foam separation column, and the air intake pipeline comprises an air compressor, a pressure gauge and a flow controller which are sequentially arranged in a direction gradually approaching the foam separation column.

[0028] Furthermore, the present invention also provides a whey protein product, which includes soy whey protein, and the soy whey protein is separated from yellow slurry water by using the above-mentioned method for separating soy whey protein in yellow slurry water.

[0029] Beneficial Effects

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] (1) The present invention sets the foam separation column used for foam separation to form a certain inclination angle with the horizontal plane, which is more convenient for the direct discharge of the yellow slurry water foam, with higher efficiency and easier operation; at the same time, a discharge valve is also provided at the bottom of the foam separation column to facilitate the discharge of the remaining liquid after the separation is completed, which has the advantages of simple structure, easy operation and green environmental protection.

[0032] (2) In the present invention, by subjecting the yellow slurry water to high-speed shear homogenization treatment, the dispersion state and structural characteristics of the soy whey protein in the yellow slurry water can be changed, thereby affecting its surface activity, making the protein molecules more evenly dispersed in the solution, thereby making it easier to move to the gas-liquid interface in the subsequent foam separation process, thereby improving the separation efficiency.

[0033] (3) The soy whey protein obtained by using the foam separation device and the method for separating soy whey protein from yellow slurry water provided by the present invention has a high recovery rate of up to 93%, and has no significant effect on the structure and function of the soy whey protein. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0035] Figure 1 A schematic structural diagram of an embodiment of a foam separation device provided by the present invention;

[0036] Figure 2 A schematic flow chart of an embodiment of a method for separating soy whey protein from yellow pulp water provided by the present invention;

[0037] Figure 3This is the liquid chromatogram of soy whey protein before and after foam separation.

[0038] Figure numbers: 100, foam separation device; 1, air compressor; 2, pressure gauge; 3, flow controller; 4, air inlet; 5, unloading valve; 6, foam separation column; 7, foam collecting bottle.

[0039] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0040] To make the purpose, technical scheme and advantages of the embodiment of the present invention clearer, the technical scheme in the embodiment of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiment, it is carried out according to the normal conditions or the conditions recommended by the manufacturer. If the reagents or instruments used do not specify the manufacturer, they are all conventional products that can be purchased commercially. In addition, the meaning of "and / or" appearing in the full text includes three parallel schemes, taking "A and / or B" as an example, including scheme A, or scheme B, or schemes that A and B meet at the same time. In addition, the technical schemes between the various embodiments can be combined with each other, but must be based on the ability of ordinary technicians in the field to achieve. When the combination of technical solutions is contradictory or cannot be achieved, it should be considered that the combination of such technical solutions does not exist, and is not within the scope of protection required by the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present invention.

[0041] The inventor has proposed a method and device for efficiently separating soy whey protein from yellow slurry through process and equipment improvements. The method and device have simple processing technology, short time consumption, and no significant effect on the structure of soy whey protein. Specifically, the present invention proposes a method for separating soy whey protein from yellow slurry using a foam separation device designed and improved by the inventor. Figure 1 FIG. 1 is an example of a foam separation device 100 provided by the present invention. Figure 2 The figure shows an embodiment of the method for separating soy whey protein in yellow pulp water based on the foam separation device 100 provided by the present invention.

[0042] See also Figure 1As shown, in this embodiment, the foam separation device 100 includes a foam separation column 6, which is tilted so that the center line of the foam separation column 6 forms a preset angle A with the horizontal direction, the top of the foam separation column 6 is open, and the bottom of the foam separation column 6 is provided with an air inlet 4 and a discharge valve 5. The foam separation device 100 also includes a foam collection bottle 7, which is used to collect foam flowing out of the top opening of the foam separation column 6. It should be noted that the foam collection bottle 7 can be integrally arranged with the foam separation column 6 or separately arranged. In some embodiments of the present invention, it is preferred that the foam collection bottle 7 is integrally arranged with the foam separation column 6, which is more convenient for assembly.

[0043] See also Figure 2 As shown, in this embodiment, the method for separating soy whey protein in yellow slurry water comprises the following steps:

[0044] Step S10, first diluting the yellow slurry water with water and adjusting its pH value to obtain a yellow slurry;

[0045] Step S20, using a high-speed shear homogenizer to perform high-speed shear homogenization on the yellow slurry, the speed of the high-speed shear homogenizer is 2500-7500 r / min, and the homogenization time is 30-40 s;

[0046] Step S30, injecting the homogenized yellow slurry into the foam separation column 6, and introducing air into the foam separation column 6, so that the yellow slurry water in the foam separation column 6 generates foam and flows out from the top opening of the foam separation column 6 and flows into the foam collecting bottle 7, and defoaming the foam in the foam collecting bottle 7 to obtain the soy whey protein separated from the yellow slurry water.

[0047] The foam separation method provided by the invention has a high recovery rate of soybean whey protein in yellow pulp water, which can reach up to 93% at most, has no significant effect on the structure and function of the soybean whey protein, and has a simple equipment structure, is easy to operate, and is easy to realize industrial production.

[0048] Further, in some embodiments of the present invention, step S10 includes:

[0049] Step S10a, adding purified water to the yellow slurry to dilute the yellow slurry to a concentration of soy whey protein of 1.3-1.6 g / L, to obtain a diluted solution;

[0050] Step S10b, adjusting the pH value of the dilution solution to 5.0-5.5 to obtain a yellow slurry.

[0051] Wherein, adjusting the pH value of the diluent to 5.0-5.5 can be achieved by adding a certain amount of acetic acid and sodium acetate to the diluent.

[0052] In some embodiments of the present invention, the rotation speed of the high-speed shear homogenizer is preferably 5000 r / min, and the homogenization time is 30 s.

[0053] In some embodiments of the present invention, when the homogenized yellow slurry is injected into the foam separation column 6, the liquid volume of the foam separation column 6 is 10-20% of the total volume of the foam separation column 6. Further, preferably, the liquid volume of the foam separation column 6 is 15% of the total volume of the foam separation column 6.

[0054] In some embodiments of the present invention, in the step of introducing air into the foam separation column 6, the air intake flow rate is 100-300 mL / min, and by controlling the air intake flow rate, the amount and rate of yellow slurry water foam generated in the foam separation column 6 can be regulated. Further, preferably, the air intake flow rate is 150 mL / min.

[0055] In some embodiments of the present invention, the preset angle A is in the range of 55 to 65°. Within this inclination range, the yellow slurry water foam generated in the foam separation column 6 is more likely to flow out from the top opening of the foam separation column 6. Further, it is preferred that the preset angle A is set to 60°, which has a higher collection efficiency for the yellow slurry water foam.

[0056] Furthermore, in some embodiments of the present invention, the ratio of the inner diameter to the height of the foam separation column 6 is 1:3-4.

[0057] Further reading Figure 1 As shown, in an embodiment of the present invention, the foam separation device 100 also includes an air intake pipeline, which is connected to the air inlet 4 of the foam separation column 6. The air intake pipeline includes an air compressor 1, a pressure gauge 2 and a flow controller 3 which are arranged in sequence in a direction gradually approaching the foam separation column 6. Through the setting of the flow controller 3, the air intake flow rate of air entering the foam separation column 6 can be well controlled to regulate the amount and rate of yellow slurry water foam generated in the foam separation column 6.

[0058] In order to further optimize the separation process, the present invention optimizes the process parameters in the separation method with the recovery rate of soy whey protein as an indicator, and focuses on the separation effect of the high-speed shear homogenizer speed (2500r / min, 5000r / min, 7500r / min), different air flow rates (100mL / min, 150mL / min, 300mL / min) and liquid loading (10%, 15%, 20%) to conduct a three-factor three-level crossover experiment. The separation operation process of soy whey protein is as follows:

[0059] Take a certain amount of yellow pulp water, dilute its protein concentration with purified water to 1.3-1.6 g / L, adjust the pH value to 5.5, and then homogenize it with a high-speed shear homogenizer for 30 seconds; then use Figure 1 The foam separation device 100 shown injects the homogenized yellow slurry water into the foam separation column 6 from the top opening of the foam separation column 6, turns on the air compressor 1, and bubbles appear in the foam separation column 6 after the air flow flows in and continuously move upward, and then enters the foam collection bottle 7, and the collected foam layer is defoamed to enrich the soy whey protein solution. When the foam layer no longer overflows from the top opening of the foam separation column 6, close the air flow valve, open the discharge valve 5 at the bottom of the foam separation column 6, and discharge the remaining liquid. Among them, the inner diameter of the foam separation column 6 is 60mm, the column height is 180mm, and the foam separation column 6 is placed at an angle, and the angle between its center line and the horizontal plane is 60°.

[0060] The results of the three-factor three-level crossover experiment are shown in Table 1.

[0061] Table 1 Recovery rate of soy whey protein under different parameter conditions

[0062] Homogenizer speed (r / min) Liquid volume (%) Inlet flow rate (mL / min) Recovery rate (%) 2500 10 100 50 2500 15 150 61 2500 20 300 59 5000 10 100 85 5000 15 150 93 5000 20 300 79 7500 10 100 81 7500 15 150 83 7500 20 300 69

[0063] The experimental results (Table 1) show that the speed of the homogenizer has a significant effect on the recovery rate of soy whey protein. Under a relatively low speed (2500r / min), the recovery rate shows a trend of first rising and then falling with the increase of the liquid loading amount. When the speed is increased to 5000r / min and 7500r / min, the recovery rate of soy whey protein increases when the liquid loading amount is 15%; the air flow rate has different effects on the recovery rate under different homogenizer speeds. When the air flow rate is 150mL / min and the homogenizer speed is 5000r / min, the recovery rate of soy whey protein is the highest, up to 93%. Therefore, the homogenizer speed can be selected to be 5000r / min, the liquid loading amount is 15%, and the air flow rate is 150mL / min, as the optimum conditions for the separation method of soy whey protein in yellow pulp water provided by the present invention.

[0064] The present invention also provides a whey protein product, the whey protein product includes soy whey protein, and the soy whey protein is separated from yellow slurry water by using the method for separating soy whey protein in yellow slurry water provided in the above embodiment. It should be noted that since the whey protein product provided by the present invention adopts all embodiments of the method for separating soy whey protein in yellow slurry water, it at least has all the beneficial effects of the above embodiments, which will not be repeated here one by one.

[0065] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments and drawings. It should be understood that the following embodiments are only used to explain the present invention and are not used to limit the present invention.

[0066] Example 1

[0067] (1) Take a certain amount of yellow slurry water, add purified water to dilute it to a concentration of soy whey protein of 1.5 g / L, and then adjust the pH value to 5.3 to obtain yellow slurry.

[0068] (2) The yellow slurry obtained in step (1) was homogenized using a high-speed shear homogenizer, the speed of the high-speed shear homogenizer was 5000 r / min, and the homogenization time was 30 s.

[0069] (3) Build Figure 1 In the foam separation device shown, the inner diameter of the foam separation column 6 is 60 mm, the column height is 180 mm, the angle between the center line of the foam separation column 6 and the horizontal plane is 60°, the yellow slurry that has been homogenized in step (2) is injected into the foam separation column 6 from the top opening of the foam separation column 6, and the liquid filling amount is 15% of the total volume of the foam separation column 6, the air compressor 1 is turned on, and the flow controller is adjusted so that the air intake flow rate of the air into the foam separation column 6 is 150 mL / min. After the air flow enters the foam separation column 6 from the air inlet 4, bubbles appear in the foam separation column 6 and continue to move upward until they overflow from the top opening of the foam separation column 6 and flow into the foam collection bottle 7. The foam collected in the foam collection bottle 7 is defoamed to obtain the soy whey protein separated from the yellow slurry, and the discharge valve 5 is opened to discharge the remaining liquid in the foam separation column 6.

[0070] Example 2

[0071] (1) Take a certain amount of yellow slurry water, add purified water to dilute it to a concentration of soy whey protein of 1.3 g / L, and then adjust the pH value to 5.0 to obtain yellow slurry.

[0072] (2) The yellow slurry obtained in step (1) was homogenized using a high-speed shear homogenizer, the speed of the high-speed shear homogenizer was 5000 r / min, and the homogenization time was 35 s.

[0073] (3) Build Figure 1In the foam separation device shown, the inner diameter of the foam separation column 6 is 60 mm, the column height is 240 mm, the angle between the center line of the foam separation column 6 and the horizontal plane is 55°, the yellow slurry that has been homogenized in step (2) is injected into the foam separation column 6 from the top opening of the foam separation column 6, and the liquid filling amount is 10% of the total volume of the foam separation column 6, the air compressor 1 is turned on, and the flow controller is adjusted so that the air intake flow rate of the air into the foam separation column 6 is 100 mL / min. After the air flow enters the foam separation column 6 from the air inlet 4, bubbles appear in the foam separation column 6 and continue to move upward until they overflow from the top opening of the foam separation column 6 and flow into the foam collection bottle 7. The foam collected in the foam collection bottle 7 is defoamed to obtain the soy whey protein separated from the yellow slurry, and the discharge valve 5 is opened to discharge the remaining liquid in the foam separation column 6.

[0074] Example 3

[0075] (1) Take a certain amount of yellow slurry water, add purified water to dilute it to a concentration of soy whey protein of 1.6 g / L, and then adjust the pH value to 5.5 to obtain yellow slurry.

[0076] (2) The yellow slurry obtained in step (1) was homogenized using a high-speed shear homogenizer, the speed of the high-speed shear homogenizer was 5000 r / min, and the homogenization time was 40 s.

[0077] (3) Build Figure 1 In the foam separation device shown, the inner diameter of the foam separation column 6 is 60 mm, the column height is 210 mm, the angle between the center line of the foam separation column 6 and the horizontal plane is 65°, the yellow slurry that has been homogenized in step (2) is injected into the foam separation column 6 from the top opening of the foam separation column 6, and the liquid filling amount is 20% of the total volume of the foam separation column 6, the air compressor 1 is turned on, and the flow controller is adjusted so that the air intake flow rate of the air into the foam separation column 6 is 300 mL / min, after the air flow enters the foam separation column 6 from the air inlet 4, bubbles appear in the foam separation column 6 and continuously move upward until they overflow from the top opening of the foam separation column 6 and flow into the foam collection bottle 7, the foam collected in the foam collection bottle 7 is defoamed to obtain the soy whey protein separated from the yellow slurry, and the discharge valve 5 is opened to discharge the remaining liquid in the foam separation column 6.

[0078] Comparative Example 1

[0079] A certain amount of yellow pulp water was taken (the protein concentration in the yellow pulp water stock solution was 3.3 g / L, determined by the Coomassie Brilliant Blue G-250 method), and the protein concentration of the yellow pulp water was not adjusted. The subsequent processing steps and parameter conditions were the same as those in Example 1.

[0080] Comparative Example 2

[0081] Take a certain amount of yellow slurry water, add purified water to dilute it to the concentration of soy whey protein of 1.4 g / L, and then adjust the pH value to 5.4. Do not perform high-speed shear homogenization on the yellow slurry water, and the subsequent processing steps and parameter conditions are the same as those in Example 1.

[0082] Performance Test:

[0083] (1) Determination of whey protein content

[0084] The protein-Coomassie Brilliant Blue complex has a maximum absorption wavelength at 595nm. The absorbance value is measured at this wavelength and the protein content in the sample is calculated through the standard curve. The test process is as follows:

[0085] Preparation of BSA standard solution: Weigh 20 mg of bovine serum albumin, dissolve it in water and make up to 200 mL to prepare a 0.1 g / L protein standard solution for standby use.

[0086] Preparation of Coomassie Brilliant Blue solution: Weigh 100 mg of Coomassie Brilliant Blue G-250, dissolve it in 50 mL of 95% ethanol, then add 100 mL of 85% phosphoric acid, make up to 1000 mL with distilled water, filter with filter paper, and draw a protein standard curve with the mass concentration of bovine serum albumin solution as the horizontal axis and the absorbance at 595 nm at the corresponding concentration as the vertical axis.

[0087] Determination of whey protein content: Take an appropriate amount of whey protein and Coomassie Brilliant Blue solution, mix them thoroughly, let them stand for a period of time, measure the absorbance at 595nm, and substitute it into the standard curve to calculate the protein content.

[0088] The protein recovery rate was calculated as follows:

[0089]

[0090] Where: R is the recovery rate of soy whey protein, %;

[0091] ρ0 and ρ f are the protein concentrations in the initial sample and foam solution, mg / mL, respectively;

[0092] V0 and V f are the volumes of the initial sample and foam liquid, mL

[0093] The results of the determination of the recovery rate of soybean whey protein in each embodiment and comparative example are shown in Table 2 below.

[0094] Table 2 Soybean whey protein recovery rate of each embodiment and comparative example

[0095] Sample Type Soy whey protein recovery rate (%) Example 1 93 Example 2 75 Example 3 84 Comparative Example 1 47 Comparative Example 2 41

[0096] The following conclusions can be drawn from the results in Table 2:

[0097] In Comparative Example 1, without adjusting the protein concentration of the yellow pulp water, even if the soybean whey protein in the yellow pulp water was subjected to foam separation under the optimal parameter conditions of a homogenizer speed of 5000 r / min, a liquid volume of 15%, and an air intake flow rate of 150 mL / min, the recovery rate of the soybean whey protein was only 47%. This indicates that diluting the protein concentration in the yellow pulp water stock solution with pure water first can effectively improve the efficiency of foam separation of soybean whey protein.

[0098] In Comparative Example 2, when the yellow slurry water was not homogenized, even if the soybean whey protein in the yellow slurry water was subjected to foam separation under the optimal parameter conditions of 15% liquid volume and 150 mL / min air flow, the recovery rate of the soybean whey protein was only 41%. This indicates that high-speed homogenization of the yellow slurry water after dilution and pH adjustment can effectively improve the efficiency of foam separation of soybean whey protein.

[0099] In the embodiment of the present invention, by first diluting the protein concentration in the yellow pulp water stock solution and then performing foam separation after high-speed shear homogenization, the soy whey protein in the yellow pulp water can be efficiently separated, and the recovery rate can be as high as 93%. The process is simple, time-saving, and more environmentally friendly and energy-saving.

[0100] (2) Molecular weight test of soy whey protein

[0101] The molecular weight of soy whey protein in yellow slurry water before and after foam separation was determined using Agilent liquid chromatography 1200 to evaluate the effect of foam separation on the structure of soy whey protein. The chromatographic column selected was Shodex Protein KW-804 column, the mobile phase was 0.05M phosphate buffer solution with a pH of 7.0 (containing 0.1M NaCl), the detection wavelength of the ultraviolet detector was 280nm, the column temperature was 25°C, and the injection volume was 20μL.

[0102] The liquid chromatogram of soy whey protein before and after foam separation is as follows Figure 3 As shown. Figure 3 It can be seen that the proteins before and after separation have three peaks at 11.5min, 17min and 23min, among which the highest peak at 11.5min accounts for about 75% of the total peak area, and there is no obvious change in the proportion of the total peak area occupied by each peak between the two groups, indicating that the foam separation process has no significant effect on the structure of soy whey protein.

[0103] The above are only preferred embodiments of the present invention, and do not limit the patent scope of the present invention. For those skilled in the art, the present invention may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the patent protection scope of the present invention.

Claims

1. A method for separating soybean whey protein from yellow pulp water, characterized in that: The method for separating soy whey protein from yellow slurry water is carried out using a foam separation device, the foam separation device comprising a foam separation column, the foam separation column being arranged in an inclined manner so that the center line of the foam separation column forms a preset angle A with the horizontal direction, the top of the foam separation column is arranged in an open manner, the bottom of the foam separation column is provided with an air inlet and a discharge valve, the foam separation device further comprising a foam collection bottle, the foam collection bottle being used to collect foam flowing out of the top opening of the foam separation column; The method for separating soybean whey protein in yellow pulp water comprises the following steps: Firstly, dilute the yellow slurry with water and adjust its pH value to obtain yellow slurry; The yellow slurry is subjected to high-speed homogenization by a high-speed shear homogenizer, wherein the speed of the high-speed shear homogenizer is 2500-7500 r / min, and the homogenization time is 30-40 s; The homogenized yellow slurry is injected into a foam separation column, and air is introduced into the foam separation column to generate foam in the yellow slurry water in the foam separation column and flow out from the top opening of the foam separation column and into a foam collecting bottle. The foam in the foam collecting bottle is defoamed to obtain the soy whey protein separated from the yellow slurry water.

2. The method for separating soybean whey protein from yellow slurry water according to claim 1, characterized in that: The step of first diluting the yellow slurry water with water and adjusting its pH value to obtain the yellow slurry comprises: Adding purified water to the yellow slurry to dilute the yellow slurry to a concentration of soy whey protein of 1.3 to 1.6 g / L, to obtain a dilution; The pH value of the dilution solution is adjusted to 5.0-5.5 to obtain a yellow slurry.

3. The method for separating soybean whey protein from yellow slurry water according to claim 1, characterized in that: In the step of subjecting the yellow slurry to high-speed shear homogenization with a high-speed shear homogenizer: The rotation speed of the high-speed shear homogenizer is 5000r / min.

4. The method for separating soybean whey protein from yellow slurry water according to claim 1, characterized in that: The step of injecting the homogenized yellow slurry into the foam separation column: The liquid volume of the foam separation column is 10-20% of the total volume of the foam separation column.

5. The method for separating soybean whey protein from yellow slurry water according to claim 1, characterized in that: In the step of introducing air into the foam separation column: The air intake flow rate is 100-300 mL / min.

6. The method for separating soybean whey protein from yellow slurry water according to claim 1, characterized in that: In the step of injecting the homogenized yellow slurry into a foam separation column and introducing air into the foam separation column: The liquid volume of the foam separation column is 15% of the total volume of the foam separation column; The air flow rate is 150 mL / min.

7. The method for separating soybean whey protein from yellow slurry water according to claim 1, characterized in that: The preset angle A ranges from 55° to 65°.

8. The method for separating soybean whey protein from yellow slurry water according to claim 1, characterized in that: The ratio of the inner diameter to the height of the foam separation column is 1:3-4.

9. The method for separating soybean whey protein from yellow slurry water according to claim 1, characterized in that: The foam separation device also includes an air intake pipeline, which is connected to the air inlet of the foam separation column. The air intake pipeline includes an air compressor, a pressure gauge and a flow controller which are arranged in sequence in a direction gradually approaching the foam separation column.

10. A whey protein product, characterized in that The whey protein product comprises soy whey protein, and the soy whey protein is separated from yellow slurry water by using the method for separating soy whey protein in yellow slurry water as claimed in any one of claims 1 to 9.

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