Preparation method of selenium-rich egg powder

Abstract

The application discloses a preparation method of selenium-rich egg powder, which uses selenium-rich eggs as raw materials, adopts a spray drying method to prepare the egg powder, and combines steam explosion and subcritical extraction methods to treat the egg powder, so that the selenium-rich egg powder with high protein content, low fat and good dispersibility is obtained. Compared with the method without steam explosion and subcritical extraction, the dispersibility of the egg powder is obviously increased, and the fat content in the egg yolk powder and the whole egg powder is obviously reduced. The selenium-rich egg powder prepared by the application technology is natural and safe, rich in nutrition, and has excellent physiological activities of regulating immunity, antioxidation, antiosteoporosis and anti-inflammation, and can be applied to the development of solid beverages, health foods, functional foods and other products as food raw materials or ingredients.

Description

Technical Field

[0001] This invention relates to a method for preparing selenium-enriched egg powder, belonging to the food field. Background Technology

[0002] Selenium is an essential trace element for the human body, playing a vital role in preventing oxidative damage and immune deficiencies. Insufficient selenium intake can cause Keshan disease, Kashin-Beck disease, and immune dysfunction, and increase the incidence of serious diseases such as cancer and cardiovascular disease. Since the human body cannot synthesize selenium, it must be obtained from external sources. Selenium exists in two forms: inorganic selenium and organic selenium. Inorganic selenium is highly toxic and has low bioavailability; while organic selenium compounds have high bioavailability, strong biological activity, and high safety.

[0003] Selenium-enriched eggs are produced by adding selenium-enriched compound feed to chicken feed. Inorganic selenium in the feed is passively absorbed by the hen's intestines and reduced to organic selenium compounds, or transported to organs and tissues to synthesize selenoamino acids for enrichment. Organic selenium is actively absorbed by the body through the amino acid absorption mechanism, converted into selenoproteins, and directly utilized by the body. Sufficient selenium in the feed helps laying hens maintain a dynamic balance of selenium in their bodies during the laying cycle, continuously producing selenium-enriched eggs, while also improving egg quality. Compared with other selenium-enriched foods, selenium-enriched eggs have high nutritional value, low cost, convenient processing, and high organic selenium content, while also possessing various physiological functions, such as enhancing human immunity, anti-tumor effects, and promoting brain development.

[0004] Selenium-enriched egg powder is prepared from selenium-enriched eggs through spray drying. Compared to selenium-enriched eggs, it has advantages such as convenient transportation and long shelf life. However, due to the heat denaturation of egg proteins during spray drying, the dispersibility of selenium-enriched egg powder is poor. A common solution is enzymatic hydrolysis of the egg powder. Enzymatic hydrolysis of selenium-enriched egg powder has advantages such as mild reaction conditions, easy process control, environmental friendliness, and low purification cost. However, because egg proteins, especially the high-phosphoproteins and high-density lipoproteins in egg yolks, have poor water solubility and strong intermolecular interactions, there are few active sites for enzyme interaction, resulting in long reaction times and low enzymatic hydrolysis efficiency. In addition, selenium-enriched egg yolk powder and selenium-enriched whole egg powder have high fat and cholesterol content, making them unsuitable for special populations such as those with high blood lipids, high blood pressure, and the elderly, thus limiting their widespread application. Therefore, the preparation of a selenium-enriched egg powder with good dispersibility and low fat content is of great significance.

[0005] Subcritical extraction is a novel oil extraction technology with advantages such as no solvent residue, high extraction rate, and protection of beneficial components. Existing methods for removing oil from egg yolks using subcritical extraction all require pretreatment steps to achieve high defatting efficiency. For example, patent CN109971538B discloses a method for preparing egg yolk oil using subcritical propane extraction. This method first dilutes the egg yolk to remove water-soluble proteins, aiming to break the emulsion and enhance the targeting of subsequent protease hydrolysis. Further enzymatic hydrolysis is used to treat the remaining lipoproteins, breaking the emulsion and releasing the oil. These steps can effectively improve the efficiency of subcritical extraction of egg yolk oil, but the process is complex and requires a large throughput. Patent CN 113549103B discloses a two-step subcritical extraction method for preparing egg yolk lecithin. This method first performs freeze-thaw treatment on the egg yolk to break the emulsion, and then removes water-soluble proteins through dilution and centrifugation, which is beneficial for subsequent defatting. The freeze-thaw process in the pretreatment steps is very costly in industry, and the samples need to be diluted by a large factor, resulting in large processing volumes and complex procedures. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing selenium-enriched egg powder. By subjecting the egg powder prepared by spray drying to steam explosion treatment, and then combining it with subcritical extraction to reduce the fat content in the egg powder, a selenium-enriched egg powder with good dispersibility and low oil content is obtained.

[0007] To achieve the above objectives, the present invention provides a method for preparing selenium-enriched egg powder, the specific steps of which are as follows:

[0008] (1) Pretreatment: Take fresh selenium-enriched eggs, wash them, and use an egg separator to separate the eggs to obtain whole egg liquid, or separate the whole egg liquid into egg white liquid and egg yolk liquid;

[0009] (2) Spray drying: Spray dry the whole egg liquid or egg white liquid and egg yolk liquid obtained in step (1) to obtain whole egg powder or egg white powder and egg yolk powder;

[0010] (3) Steam explosion: The whole egg powder or egg white powder and egg yolk powder obtained in step (2) are subjected to steam explosion to obtain the exploded whole egg powder or egg white powder and egg yolk powder;

[0011] (4) Granulation: The burst egg yolk powder or whole egg powder obtained in step (3) is granulated into particles with a diameter of 1-3 mm and a length of 5-15 mm by an extrusion granulator.

[0012] (5) Subcritical extraction: The egg yolk powder particles or whole egg powder particles obtained in step (4) are degreased using the subcritical propane extraction method.

[0013] (6) Product collection and inspection: Collect the defatted whole egg powder or egg yolk powder obtained in step (5) and the burst protein powder obtained in step (3), and inspect the quality of the whole egg powder or egg yolk powder and protein powder.

[0014] In one embodiment of the present invention, in step (1), the selenium-enriched eggs are eggs laid by laying hens fed with selenium-enriched feed. After the laying hens consume selenium-enriched feed, organic selenium will accumulate in the egg white and yolk of the eggs. The organic selenium content in the selenium-enriched eggs is ≥0.45mg / kg.

[0015] In one embodiment of the present invention, in step (2), the spray drying conditions for the whole egg liquid or egg yolk liquid are: inlet air temperature 175-180°C and outlet air temperature 75-80°C; and the spray drying conditions for the egg white liquid are: inlet air temperature 170-175°C and outlet air temperature 70-75°C.

[0016] In one embodiment of the present invention, in step (3), the steam explosion conditions are: steam pressure 0.5-2.5 MPa, processing time 60-120 s, and moisture content 10-20%.

[0017] In one embodiment of the present invention, in step (4), during the extrusion granulation, the extrusion pressure is 10-30 MPa, and the moisture content of the egg yolk powder or whole egg powder is 10-20%.

[0018] In one embodiment of the present invention, in step (5), during subcritical propane extraction, the ratio of egg yolk powder or whole egg powder to propane extraction solvent is 1:5 to 1:10 (w / v), the extraction pressure is 0.5 to 2.5 MPa, the extraction temperature is 35 to 45°C, and the extraction time is 30 to 90 min.

[0019] In one embodiment of the present invention, in step (5), after the egg yolk powder or whole egg powder particles are degreased, the solvent propane is recovered by utilizing the pressure difference of the pressure vessel.

[0020] In one embodiment of the present invention, the pressure vessel in step (5) includes an evaporation vessel.

[0021] The present invention also provides selenium-enriched egg powder prepared using the above-described preparation method.

[0022] The present invention also provides an application of the above-mentioned selenium-enriched egg powder in solid beverages, health foods and functional foods.

[0023] The beneficial effects achieved by this invention are as follows:

[0024] (1) Selenium-enriched egg powder was prepared by spray drying. The selenium-enriched egg powder prepared by spray drying was subjected to steam explosion treatment, and the egg yolk powder or whole egg powder was degreased by subcritical extraction technology. The selenium-enriched egg powder prepared by this method has good dispersibility and low oil content.

[0025] (2) This invention uses steam explosion treatment on selenium-enriched protein powder, which breaks down the protein molecular chains, reduces the molecular weight, and improves the dispersibility to 90.6%. Selenium-enriched egg yolk powder and whole egg powder are pretreated using steam explosion technology to disrupt the yolk structure and release oil. Subcritical extraction technology is then used to extract egg yolk oil. The oil content in the selenium-enriched egg yolk powder is as low as 5.2%, with a dispersibility as high as 76%; the oil content in the selenium-enriched whole egg powder is as low as 4.6%, with a dispersibility as high as 82%.

[0026] (3) The present invention first uses a steam explosion method to process the selenium-enriched egg powder prepared by spray drying, and then combines it with subcritical extraction technology for degreasing. Before degreasing, there is no need to perform special pretreatment on the egg yolk or whole egg liquid. Steam explosion can cause the egg yolk sphere structure to depolymerize, which is conducive to the subsequent subcritical extraction solvent entering the egg yolk sphere, thereby achieving a high degreasing effect.

[0027] (4) The selenium-enriched egg powder prepared by the method of the present invention is natural and safe, rich in nutrients, and has a high content of organic selenium. It has excellent physiological activities such as regulating immunity, anti-oxidation, anti-osteoporosis, and anti-inflammation. It can be used as a food raw material or ingredient in the development of solid beverages, health foods, functional foods and other products. Detailed Implementation

[0028] The preferred embodiments of the present invention are described below. It should be understood that the embodiments are for better explanation of the present invention and are not intended to limit the present invention.

[0029] Protein content was determined using the Kjeldahl method.

[0030] Fat content was determined using the chloroform-methanol method.

[0031] Method for determining selenium content: First, the sample is pretreated using a wet digestion method. The specific steps are as follows: Accurately weigh 0.1–0.2 g of sample (powder) into a digestion tube, add 2 mL of H₂O₂ and 5 mL of HNO₃ to create a strongly acidic digestion environment. After slightly tightening the tube cap 1–2 turns, place it on a graphite digester for digestion. Start timing when the instrument temperature rises to between 120 and 160°C, and digest for at least 70 minutes to ensure complete digestion. After digestion, dilute the mixture to 10 mL with deionized water. Filter the diluted sample solution using a 0.22 μm aqueous filter membrane. Finally, determine the organic selenium content in the sample using inductively coupled ion mass spectrometry (ICP-MS). ICP-MS operating conditions: RF power: 1350 W; nebulizer: glass concentric nebulizer; sampling cone type: Ni; sampling rate: 0.5 mL / min; number of repetitions: 3; acquisition mode: standard; scan / reading: 20.

[0032] Method for determining dispersibility: Place 0.5g of powder sample into a beaker containing 10mL of deionized water, stir at 700r / min for 60s, and immediately filter the solution through a 200-mesh sieve. Take 2mL of the filtrate and dry it in an oven at 105℃ until constant weight. Weigh the sample as m, and calculate the dispersibility of the sample according to the following formula.

[0033]

[0034] Example 1

[0035] A method for preparing selenium-enriched egg powder includes the following steps:

[0036] (1) Pretreatment: Take several fresh selenium-enriched eggs, wash them, beat them to obtain selenium-enriched whole egg liquid, take part of the whole egg liquid, and separate it into selenium-enriched egg white liquid and selenium-enriched egg yolk liquid.

[0037] (2) Spray drying: The selenium-enriched egg white liquid obtained in step (1) is spray dried at an air inlet temperature of 172°C and an air outlet temperature of 73°C to obtain selenium-enriched protein powder; the selenium-enriched egg yolk liquid and selenium-enriched whole egg liquid obtained in step (1) are spray dried at an air inlet temperature of 176°C and an air outlet temperature of 77°C to obtain selenium-enriched egg yolk powder and selenium-enriched whole egg powder.

[0038] (3) Steam explosion: The selenium-enriched protein powder obtained in step (2) was subjected to steam explosion treatment at a steam pressure of 1.7 MPa for 80 s; the selenium-enriched egg yolk powder obtained in step (2) was subjected to steam explosion treatment at a steam pressure of 2.5 MPa for 110 s; the selenium-enriched whole egg powder obtained in step (2) was subjected to steam explosion treatment at a steam pressure of 2.1 MPa for 100 s, with a moisture content of 18%.

[0039] (4) Granulation: The selenium-enriched egg yolk powder and selenium-enriched whole egg powder obtained in step (3) are made into cylindrical granules with a diameter of 6 mm using an extrusion granulator. The extrusion pressure during extrusion granulation is 18 MPa.

[0040] (5) Subcritical extraction: The selenium-enriched egg yolk powder obtained in step (4) was degreased using subcritical propane extraction. The subcritical extraction conditions were: egg yolk powder to propane ratio of 1:9 (w / v), extraction pressure of 2.4 MPa, extraction temperature of 42℃, and extraction time of 90 min. The selenium-enriched whole egg powder obtained in step (4) was degreased using subcritical propane extraction. The subcritical extraction conditions were: whole egg powder to propane ratio of 1:7 (w / v), extraction pressure of 2.2 MPa, extraction temperature of 40℃, and extraction time of 70 min. After extraction, the propane solvent was recovered by utilizing the pressure difference of the reaction vessel.

[0041] (6) Product collection and inspection: Collect the selenium-enriched egg yolk powder and selenium-enriched whole egg powder obtained in step (5), as well as the selenium-enriched protein powder obtained in step (3), and determine the organic selenium content, protein content, dispersibility and fat content of the three selenium-enriched egg powders. The test results of the three selenium-enriched egg powders are shown in Table 1, Table 2 and Table 3 respectively.

[0042] Example 2

[0043] A method for preparing selenium-enriched egg powder includes the following steps:

[0044] (1) Pretreatment: Take several fresh selenium-enriched eggs, wash them, beat them to obtain selenium-enriched whole egg liquid, take part of the whole egg liquid, and separate it into selenium-enriched egg white liquid and selenium-enriched egg yolk liquid.

[0045] (2) Spray drying: The selenium-enriched egg white liquid obtained in step (1) is spray dried at an air inlet temperature of 170°C and an air outlet temperature of 70°C to obtain selenium-enriched protein powder; the selenium-enriched egg yolk liquid and selenium-enriched whole egg liquid obtained in step (1) are spray dried at an air inlet temperature of 175°C and an air outlet temperature of 76°C to obtain selenium-enriched egg yolk powder and selenium-enriched whole egg powder.

[0046] (3) Steam explosion: The selenium-enriched protein powder obtained in step (2) was subjected to steam explosion treatment under a steam pressure of 1.2 MPa for 90 s; the selenium-enriched egg yolk powder obtained in step (2) was subjected to steam explosion treatment under a steam pressure of 2.3 MPa for 80 s; the selenium-enriched whole egg powder obtained in step (2) was subjected to steam explosion treatment under a steam pressure of 1.5 MPa for 110 s, with a moisture content of 15%.

[0047] (4) Granulation: The selenium-enriched egg yolk powder and selenium-enriched whole egg powder obtained in step (3) are made into cylindrical granules with a diameter of 7 mm using an extrusion granulator and an extrusion pressure of 12 MPa.

[0048] (5) Subcritical extraction: The selenium-enriched egg yolk powder obtained in step (4) was degreased using subcritical propane extraction. The subcritical extraction conditions were: egg yolk powder to propane ratio of 1:9 (w / v), extraction pressure of 2.4 MPa, extraction temperature of 42℃, and extraction time of 90 min. The selenium-enriched whole egg powder obtained in step (4) was degreased using subcritical propane extraction. The subcritical extraction conditions were: whole egg powder to propane ratio of 1:7 (w / v), extraction pressure of 2.2 MPa, extraction temperature of 40℃, and extraction time of 70 min. After extraction, the propane solvent was recovered by utilizing the pressure difference of the reaction vessel.

[0049] (6) Product collection and inspection: Collect the selenium-enriched egg yolk powder and selenium-enriched whole egg powder obtained in step (5), as well as the selenium-enriched protein powder obtained in step (3), and determine the organic selenium content, protein content, dispersibility and fat content of the three selenium-enriched egg powders. The test results of the three selenium-enriched egg powders are shown in Table 1, Table 2 and Table 3 respectively.

[0050] Example 3

[0051] A method for preparing selenium-enriched egg powder includes the following steps:

[0052] (1) Pretreatment: Take several fresh selenium-enriched eggs, wash them, beat them to obtain selenium-enriched whole egg liquid, take part of the whole egg liquid, and separate it into selenium-enriched egg white liquid and selenium-enriched egg yolk liquid.

[0053] (2) Spray drying: The selenium-enriched egg white liquid obtained in step (1) is spray dried at an inlet air temperature of 175°C and an outlet air temperature of 75°C to obtain selenium-enriched protein powder; the selenium-enriched egg yolk liquid and selenium-enriched whole egg liquid obtained in step (1) are spray dried at an inlet air temperature of 178°C and an outlet air temperature of 80°C to obtain selenium-enriched egg yolk powder and selenium-enriched whole egg powder.

[0054] (3) Steam explosion: The selenium-enriched protein powder obtained in step (2) was subjected to steam explosion treatment under a steam pressure of 0.6 MPa for 70 s; the selenium-enriched egg yolk powder obtained in step (2) was subjected to steam explosion treatment under a steam pressure of 1.5 MPa for 120 s; the selenium-enriched whole egg powder obtained in step (2) was subjected to steam explosion treatment under a steam pressure of 1.0 MPa for 90 s, with a moisture content of 18%.

[0055] (4) Granulation: The selenium-enriched egg yolk powder and selenium-enriched whole egg powder obtained in step (3) are made into cylindrical granules with a diameter of 6 mm using an extrusion granulator. The extrusion pressure during extrusion granulation is 18 MPa.

[0056] (5) Subcritical extraction: The selenium-enriched egg yolk powder obtained in step (4) was degreased using subcritical propane extraction. The subcritical extraction conditions were: egg yolk powder to propane ratio of 1:9 (w / v), extraction pressure of 2.4 MPa, extraction temperature of 42℃, and extraction time of 90 min. The selenium-enriched whole egg powder obtained in step (4) was degreased using subcritical propane extraction. The subcritical extraction conditions were: whole egg powder to propane ratio of 1:7 (w / v), extraction pressure of 2.2 MPa, extraction temperature of 40℃, and extraction time of 70 min. After extraction, the propane solvent was recovered by utilizing the pressure difference of the reaction vessel.

[0057] (6) Product collection and inspection: Collect the selenium-enriched egg yolk powder and selenium-enriched whole egg powder obtained in step (5), as well as the selenium-enriched protein powder obtained in step (3), and determine the organic selenium content, protein content, dispersibility and fat content of the three selenium-enriched egg powders. The test results of the three selenium-enriched egg powders are shown in Table 1, Table 2 and Table 3 respectively.

[0058] Example 4

[0059] A method for preparing selenium-enriched egg powder includes the following steps:

[0060] (1) Pretreatment: Take several fresh selenium-enriched eggs, wash them, beat them to obtain selenium-enriched whole egg liquid, take part of the whole egg liquid, and separate it into selenium-enriched egg white liquid and selenium-enriched egg yolk liquid.

[0061] (2) Spray drying: The selenium-enriched egg white liquid obtained in step (1) is spray dried at an air inlet temperature of 172°C and an air outlet temperature of 73°C to obtain selenium-enriched protein powder; the selenium-enriched egg yolk liquid and selenium-enriched whole egg liquid obtained in step (1) are spray dried at an air inlet temperature of 176°C and an air outlet temperature of 77°C to obtain selenium-enriched egg yolk powder and selenium-enriched whole egg powder.

[0062] (3) Steam explosion: The selenium-enriched protein powder obtained in step (2) was subjected to steam explosion treatment under a steam pressure of 1.7 MPa for 80 s; the selenium-enriched egg yolk powder obtained in step (2) was subjected to steam explosion treatment under a steam pressure of 2.5 MPa for 110 s; the selenium-enriched whole egg powder obtained in step (2) was subjected to steam explosion treatment under a steam pressure of 2.1 MPa for 100 s, with a moisture content of 18%.

[0063] (4) Granulation: The selenium-enriched egg yolk powder and selenium-enriched whole egg powder obtained in step (3) are made into cylindrical granules with a diameter of 6 mm using an extrusion granulator. The extrusion pressure during extrusion granulation is 18 MPa.

[0064] (5) Subcritical extraction: The selenium-enriched egg yolk powder obtained in step (4) was degreased using subcritical propane extraction. The subcritical extraction conditions were: egg yolk powder to propane ratio of 1:9 (w / v), extraction pressure of 1.5 MPa, extraction temperature of 38℃, and extraction time of 45 min. The selenium-enriched whole egg powder obtained in step (4) was degreased using subcritical propane extraction. The subcritical extraction conditions were: whole egg powder to propane ratio of 1:7 (w / v), extraction pressure of 1.0 MPa, extraction temperature of 40℃, and extraction time of 80 min. After extraction, the propane solvent was recovered by utilizing the pressure difference of the reaction vessel.

[0065] (6) Product collection and inspection: Collect the selenium-enriched egg yolk powder and selenium-enriched whole egg powder obtained in step (5), as well as the selenium-enriched protein powder obtained in step (3), and determine the organic selenium content, protein content, dispersibility and fat content of the three selenium-enriched egg powders. The test results of the three selenium-enriched egg powders are shown in Table 1, Table 2 and Table 3 respectively.

[0066] Comparative Example 1

[0067] A method for preparing selenium-enriched egg powder, the method comprising the following steps:

[0068] (1) Pretreatment: Take several fresh selenium-enriched eggs, wash them, beat them to obtain selenium-enriched whole egg liquid, take part of the whole egg liquid, and separate it into selenium-enriched egg white liquid and selenium-enriched egg yolk liquid.

[0069] (2) Spray drying: The selenium-enriched egg white liquid obtained in step (1) is spray dried at an air inlet temperature of 172°C and an air outlet temperature of 73°C to obtain selenium-enriched protein powder; the selenium-enriched egg yolk liquid and selenium-enriched whole egg liquid obtained in step (1) are spray dried at an air inlet temperature of 176°C and an air outlet temperature of 77°C to obtain selenium-enriched egg yolk powder and selenium-enriched whole egg powder.

[0070] (3) Granulation: The selenium-enriched egg yolk powder and selenium-enriched whole egg powder obtained in step (2) are made into cylindrical granules with a diameter of 6 mm using an extrusion granulator. The extrusion pressure during extrusion granulation is 18 MPa, and the moisture content of the egg yolk powder and whole egg powder is 18%.

[0071] (4) Subcritical extraction: The selenium-enriched egg yolk powder obtained in step (3) was degreased using subcritical propane extraction technology. The subcritical extraction conditions were: egg yolk powder to propane ratio of 1:9 (w / v), extraction pressure of 2.4 MPa, extraction temperature of 42℃, and extraction time of 90 min. The selenium-enriched whole egg powder obtained in step (4) was degreased using subcritical propane extraction technology. The subcritical extraction conditions were: whole egg powder to propane ratio of 1:7 (w / v), extraction pressure of 2.2 MPa, extraction temperature of 40℃, and extraction time of 70 min. After extraction, the propane solvent was recovered by utilizing the pressure difference of the reaction vessel.

[0072] (5) Product collection and inspection: Collect the selenium-enriched egg yolk powder and selenium-enriched whole egg powder obtained in step (4), as well as the selenium-enriched protein powder obtained in step (2), and determine the organic selenium content, protein content, dispersibility and fat content of the three selenium-enriched egg powders. The test results of the three selenium-enriched egg powders are shown in Table 1, Table 2 and Table 3 respectively.

[0073] Table 1. Content of organic selenium, protein, and fat in selenium-enriched protein powder, and dispersibility of the protein powder.

[0074]

[0075] *Note: -- indicates not detected.

[0076] Table 2. Content of organic selenium, protein, and fat in selenium-enriched egg yolk powder, and dispersibility of protein powder.

[0077]

[0078]

[0079] Table 3. Content of organic selenium, protein, and fat in selenium-enriched whole egg powder, and dispersibility of protein powder.

[0080]

[0081] As shown in Tables 1-3, the selenium-enriched egg powder obtained by steam explosion and subcritical extraction methods has high organic selenium content, high protein content, and good dispersibility. Steam explosion pretreatment is a crucial step, significantly improving the dispersibility and degreasing efficiency of the selenium-enriched egg powder. This is mainly attributed to the fact that steam explosion treatment breaks down protein molecular chains, reduces molecular weight, and improves dispersibility; simultaneously, it deagglomerates the egg yolk spheres, facilitating the subsequent subcritical extraction solvent to penetrate the yolk spheres and achieve a higher degreasing effect.

[0082] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A method for preparing selenium-enriched egg powder, characterized in that, Includes the following steps: (1) Pretreatment: Take fresh selenium-enriched eggs, wash them, and use an egg separator to separate the eggs to obtain whole egg liquid, or separate the whole egg liquid into egg white liquid and egg yolk liquid; (2) Spray drying: Spray dry the whole egg liquid or egg white liquid and egg yolk liquid obtained in step (1) to obtain whole egg powder or egg white powder and egg yolk powder; (3) Steam explosion: The whole egg powder or egg white powder and egg yolk powder obtained in step (2) are subjected to steam explosion to obtain the exploded whole egg powder or egg white powder and egg yolk powder. The pressure of steam explosion is 1.5~2.5MPa, the time is 60~120s, and the moisture content is 10~20%. (4) Granulation: The burst egg yolk powder or whole egg powder obtained in step (3) is granulated into particles with a diameter of 1~3 mm and a length of 5~15 mm by an extrusion granulator; (5) Subcritical extraction: The whole egg powder or egg yolk powder particles obtained in step (4) are degreased using subcritical propane extraction. During subcritical propane extraction, the ratio of the whole egg powder or egg yolk powder particles to the extraction solvent propane is 1:5 to 1:10 (w / v), the extraction pressure is 0.5 to 2.5 MPa, the extraction temperature is 35 to 45℃, and the extraction time is 30 to 90 min. (6) Product collection and inspection: Collect the defatted whole egg powder or egg yolk powder granules obtained in step (5) and the burst protein powder obtained in step (3), and inspect the quality of the whole egg powder or egg yolk powder granules and protein powder.

2. The method according to claim 1, characterized in that, In step (1), the selenium-enriched eggs contain ≥0.45 mg / kg of organic selenium.

3. The preparation method according to claim 1, characterized in that, In step (2), the spray drying conditions for the whole egg liquid or egg yolk liquid are: inlet air temperature 175~180 ℃ and outlet air temperature 75~80 ℃. The spray drying conditions for the egg white liquid are: inlet air temperature 170~175 ℃ and outlet air temperature 70~75 ℃.

4. The preparation method according to claim 1, characterized in that, In step (4), the extrusion pressure is 10~30 MPa during extrusion granulation.

5. The preparation method according to claim 1, characterized in that, In step (5), after the whole egg powder or egg yolk powder particles are degreased, the solvent propane is recovered using the pressure difference of the pressure vessel.

6. The preparation method according to claim 5, characterized in that, The pressure vessel mentioned in step (5) includes an evaporator.

7. The selenium-enriched egg powder prepared by any one of the preparation methods according to claims 1-6.

8. The use of the selenium-enriched egg powder according to claim 7 in solid beverages and health foods.

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