Processing method of selenium-rich egg product

Abstract

The invention relates to the field of food processing, and discloses a processing method of a selenium-rich egg product, which comprises the following steps: adding selenium-rich yeast hydrolysate and an endogenous antioxidant into feed of egg laying poultry to obtain raw material eggs rich in organic selenium and antioxidant substances, and constructing an endogenous protection system; the raw material eggs are placed in a pickling solution containing sodium hydroxide, sodium chloride and L-arginine serving as a sacrificial alkali buffering agent to be cured so as to weaken damage of a strong alkali environment to organic selenium; and coating the cured egg product with a layer of composite bioactive coating composed of chitosan, tea polyphenol and phytic acid to provide an exogenous physical and chemical barrier. According to the method, a complete technical chain with a synergistic effect of three stages of endogenous protection, process buffering and exogenous protection is constructed, so that the preservation rate of organic selenium in the product is remarkably improved, oxidation and microorganism breeding in the storage period are effectively inhibited, the shelf life is prolonged, and the safety of the product is improved.

Description

Technical Field

[0001] The invention relates to the technical field of food processing, in particular to a processing method of a selenium-enriched egg product. Background Art

[0002] Preserved eggs, a traditional egg product with a unique flavor, are deeply loved by consumers. To enhance their nutritional value, developing selenium-enriched preserved eggs rich in the trace element selenium has become a research hotspot within the industry. Organic selenium, particularly selenomethionine, which occurs naturally in eggs, offers high bioavailability and low toxicity, making it an ideal dietary selenium source. However, the key challenge facing the industrial production of selenium-enriched preserved eggs is how to effectively preserve this valuable nutrient while ensuring product safety and stability.

[0003] The core of preserved egg processing lies in protein gelation in a strong alkaline environment. Existing processing techniques, whether traditional coating or modern soaking methods, rely on a strong alkaline solution. However, this strong alkaline environment significantly damages chemically sensitive organic selenium compounds, leading to the irreversible degradation and loss of key functional components such as selenomethionine. This results in a final product with a selenium content far below expectations, significantly diminishing its nutritional value.

[0004] Furthermore, traditional methods sometimes use additives containing heavy metals such as lead and copper to stabilize the curing process and seal eggshell pores, posing serious food safety risks. While lead-free processes have become mainstream, the resulting preserved eggs face storage stability issues once they are removed from the curing environment. The inherent porosity of the eggshell makes it susceptible to oxygen exposure during shelf life, leading to lipid oxidation and flavor degradation. It also creates an opportunity for microbial intrusion, limiting the product's shelf life and market reach.

[0005] Therefore, how to collaboratively solve the three key issues of organic selenium's stability during strong alkali processing, the safety hazards of traditional auxiliary materials, and the quality deterioration of finished products during storage in a unified technical system is a technical challenge that technicians in this field urgently need to solve. Summary of the Invention

[0006] The present invention aims to overcome the shortcomings of the existing technology and provide a method for processing selenium-enriched egg products. This method aims to address technical issues in traditional processes, such as the large-scale degradation and loss of organic selenium due to the strong alkaline environment, the safety hazards of traditional dressings, and the oxidative deterioration of finished products during storage. By constructing a comprehensive and coordinated protection system from the source, processing, to finished product storage, this method maximizes the retention of the organic selenium active ingredients in the egg products and improves the stability and safety of the products.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions: The present invention provides a method for processing selenium-enriched egg products, which comprises the following steps: (a) Obtaining raw material selenium-enriched eggs: This step aims to build an endogenous protective system for eggs. Specifically, functional components are evenly mixed and added to the basic diet of laying birds for feeding.

[0008] The functional components include selenium-enriched yeast hydrolyzate as a core selenium source, the final addition amount of which in the feed is 0.5-1.5 mg / kg in terms of selenium; and a composition as an endogenous antioxidant synergist. Preferably, the synergist is a combination of natural vitamin E and grape seed extract.

[0009] The raw selenium-rich eggs obtained by feeding in this way are not only enriched with highly biologically active organic selenium, but also simultaneously enriched with antioxidants, providing the first level of protection for the stability of organic selenium during subsequent processing.

[0010] (b) Strong alkaline pickling and aging: This step aims to reduce the damage of the strong alkaline environment to organic selenium. The raw selenium-enriched eggs obtained in step (a) are placed in an innovative pickling liquid for soaking and ripening.

[0011] The innovative pickling solution crucially introduces a sacrificial alkaline buffer into a base solution containing sodium hydroxide and sodium chloride. The sacrificial alkaline buffer is preferably L-arginine.

[0012] In a preferred embodiment, the components and concentrations of the innovative pickling solution are: 35-55 g / L of sodium hydroxide, 30-50 g / L of sodium chloride, and 5-15 g / L of L-arginine.

[0013] The curing and ripening in this step is carried out at a temperature of 20-25° C. and lasts for 25-35 days.

[0014] (c) Composite bioactive coating: This step is intended to provide long-term active protection for the finished product. The finished preserved egg, which has been treated, cleaned, and dried in step (b), is coated with a layer of composite bioactive coating liquid and dried to form a protective film.

[0015] The composite bioactive coating comprises: chitosan as a film-forming matrix; tea polyphenols as a main antioxidant; and phytic acid with metal ion chelating and cross-linking functions.

[0016] In a preferred embodiment, the formula of the composite bioactive coating liquid is: 10-20 g / L chitosan, 3-6 g / L tea polyphenols, 1-3 g / L phytic acid, and 5-10 g / L glycerol as a plasticizer.

[0017] The coating solution is preferably prepared using a 1.0-1.5% (v / v) L-lactic acid aqueous solution as a solvent.

[0018] The drying process after coating is carried out at a temperature of 40-50°C until a complete, transparent and dry protective film is formed on the surface of the eggshell.

[0019] In a preferred embodiment, the specific preparation method of the composite bioactive coating liquid includes the following steps: 1) Slowly dissolve chitosan, a membrane-forming matrix, in an L-lactic acid aqueous solution while heating in a 40-50°C water bath and stirring. Continue stirring until a uniform, transparent chitosan-based solution is formed. 2) cooling the base liquid to room temperature; 3) Under continuous stirring, glycerol, tea polyphenols and phytic acid are sequentially added to the cooled chitosan-based liquid, and stirring is continued until all components are completely dissolved and mixed uniformly. After standing to degas, the composite bioactive coating liquid is obtained.

[0020] Compared with the prior art, the innovation of the present invention is: The present invention systematically solves the core technical difficulties in the processing of selenium-enriched egg products by constructing a complete technical chain with three synergistic stages of "endogenous protection-process buffering-exogenous protection".

[0021] First of all, through the scientific compounding of source feed, an antioxidant system is pre-installed inside the egg, fundamentally improving the ability of raw eggs to resist the stress of subsequent processing.

[0022] Secondly, the most innovative aspect of this invention lies in the introduction of L-arginine into the strongly alkaline pickling solution as a sacrificial alkaline buffer. The mechanism is that L-arginine's molecular structure enables it to act as a pH buffer in a strong alkaline environment. More importantly, it acts as a preferential reactant, actively consuming some chemical groups that are destructive to organic selenium, thereby "sacrificing" itself and effectively shielding the core functional component of eggs from direct chemical attack by the strong alkaline environment, methionine.

[0023] Finally, the composite bioactive coating employed in this invention provides a multifunctional physical and chemical barrier. The dense chitosan film effectively blocks oxygen and moisture penetration and inhibits microbial growth. Tea polyphenols encapsulated within the film act as highly effective free radical scavengers, actively neutralizing small amounts of oxygen that penetrate. The addition of phytic acid creates a synergistic effect, not only chelating trace metal ions that could catalyze oxidation reactions but also cross-linking with chitosan molecules, further enhancing the film's compactness and mechanical strength.

[0024] The present invention provides a method for processing selenium-enriched egg products, which has the following beneficial effects: 1. This invention achieves comprehensive, systematic protection for organic selenium in egg products by constructing a comprehensive, three-stage synergistic technology chain: "endogenous protection - process buffering - exogenous protection." This approach begins at the source, pre-introducing antioxidants into the egg through feed compounding. It then strengthens the processing process by utilizing sacrificial buffers to mitigate the destructive effects of the alkaline environment. Finally, it safeguards the end product with a reactive coating that provides long-term protection. This interconnected design delivers comprehensive protection for organic selenium far exceeding any single technological improvement.

[0025] 2. This invention significantly reduces the degradation loss of organic selenium during the core process of strong alkaline curing. The key lies in the innovative introduction of L-arginine into the curing liquid as a sacrificial alkaline buffer. L-arginine preferentially reacts with destructive chemical groups in the curing liquid, effectively shielding the eggs from direct chemical attack by the strong alkaline on selenomethionine, a core functional component of eggs. This proactively intervenes in the degradation process through chemical mechanisms, representing a key technological breakthrough in achieving a high preservation rate.

[0026] 3. This invention effectively improves the storage stability and shelf life of egg products by forming a multifunctional composite bioactive coating on their surface. The chitosan in the coating provides a physical barrier, while tea polyphenols provide a chemical antioxidant barrier. The addition of phytic acid not only chelates metal ions that could catalyze oxidation but also cross-links with chitosan, enhancing the film's compactness. This active protective mechanism, combining physical barrier and chemical protection, ensures stable product quality during long-term storage and distribution. DETAILED DESCRIPTION

[0027] To make the purpose, technical solutions and advantages of the present invention more clear, the technical solutions of the present invention will be described in detail below with reference to the embodiments. However, it will be understood by those skilled in the art that, in the present invention, the technical solutions described therein may be modified or replaced by equivalents without departing from the spirit and scope of the present invention, and such modifications or replacements shall be included within the scope of protection of the present invention.

[0028] Unless otherwise specified, the selenium-enriched eggs and ordinary duck eggs used as raw materials in the following examples and comparative examples are all fresh duck eggs from the same batch with an egg weight of 65-75 g. Example

[0029] This embodiment provides a method for processing selenium-enriched egg products, which specifically comprises the following steps: 1. Selenium-enriched Eggs: Selenium-enriched yeast hydrolysate, natural vitamin E, and grape seed extract were added to the basal diet of laying ducks. The selenium-enriched yeast hydrolysate was added at a rate of 1.0 mg / kg, natural vitamin E at 200 mg / kg, and grape seed extract at 350 mg / kg, calculated as elemental selenium. This mixed feed was fed to healthy laying ducks for 35 days, and qualified eggs produced during this period were collected for use as raw materials.

[0030] 2. Strong Alkali Curing: Prepare a curing solution with the following components and concentrations: 45 g / L sodium hydroxide, 40 g / L sodium chloride, and 10 g / L L-arginine. Place the selenium-enriched eggs obtained in step 1 in this curing solution and seal and curing at 22°C for 30 days. After curing, remove the preserved eggs, rinse with clean water, and air-dry.

[0031] 3. Composite Bioactive Coating: Prepare the coating solution by dissolving 15 g of chitosan in 1 liter of 1.2% (v / v) L-lactic acid aqueous solution at 45°C to form a base solution. After cooling, add 4.5 g of tea polyphenols, 2.0 g of phytic acid, and 8 g of glycerol in that order and stir thoroughly. Immerse the preserved eggs (dried from step 2) in the coating solution for 30 seconds. Remove and dry with hot air at 45°C for 45 minutes until the coating is dry.

[0032] Finally, the finished product is obtained, which is recorded as S1. Example

[0033] This embodiment provides a method for processing selenium-enriched egg products, which specifically comprises the following steps: 1. Selenium-enriched Eggs: Selenium-enriched yeast hydrolysate, natural vitamin E, and grape seed extract were added to the basal diet of laying ducks. The selenium-enriched yeast hydrolysate was added at a rate of 0.6 mg / kg, natural vitamin E at 120 mg / kg, and grape seed extract at 250 mg / kg. This mixed feed was fed to healthy laying ducks for 30 days, and qualified eggs produced during this period were collected for use as raw materials.

[0034] 2. Strong Alkali Curing: Prepare a curing solution with the following components and concentrations: 38 g / L sodium hydroxide, 32 g / L sodium chloride, and 6 g / L L-arginine. Place the selenium-enriched eggs obtained in step 1 in this curing solution and curate in a sealed container at 20°C for 25 days. After curing, remove the preserved eggs, rinse with clean water, and air-dry.

[0035] 3. Composite Bioactive Coating: Prepare the coating solution by dissolving 12 g of chitosan in 1 liter of 1.0% (v / v) L-lactic acid aqueous solution at 40°C to form a base solution. After cooling, add 3.5 g of tea polyphenols, 1.5 g of phytic acid, and 6 g of glycerol in that order and stir thoroughly. Immerse the preserved eggs (dried in step 2) in the coating solution for 45 seconds. Remove and dry with hot air at 40°C for 35 minutes until the coating is dry.

[0036] Finally, the finished product is obtained, which is recorded as S2. Example

[0037] This embodiment provides a method for processing selenium-enriched egg products, which specifically comprises the following steps: 1. Selenium-enriched Eggs: Selenium-enriched yeast hydrolysate, natural vitamin E, and grape seed extract were added to the basal diet of laying ducks. The selenium-enriched yeast hydrolysate was added at a rate of 1.4 mg / kg, natural vitamin E at 280 mg / kg, and grape seed extract at 480 mg / kg. This mixed feed was fed to healthy laying ducks for 42 consecutive days, and qualified eggs produced during this period were collected for use as raw materials.

[0038] 2. Strong Alkali Curing: Prepare a curing solution with the following components and concentrations: 52 g / L sodium hydroxide, 48 g / L sodium chloride, and 14 g / L L-arginine. Place the selenium-enriched eggs obtained in step 1 in this curing solution and seal and curing at 25°C for 35 days. After curing, remove the preserved eggs, rinse with clean water, and air-dry.

[0039] 3. Composite Bioactive Coating: Prepare the coating solution by dissolving 18 g of chitosan in 1 liter of 1.5% (v / v) L-lactic acid aqueous solution at 50°C to form a base solution. After cooling, add 5.5 g of tea polyphenols, 2.8 g of phytic acid, and 9 g of glycerol in that order and stir thoroughly. Immerse the preserved eggs (dried in step 2) in the coating solution for 60 seconds. Remove and dry with hot air at 50°C for 55 minutes until the coating is dry.

[0040] Finally, the finished product is obtained, which is recorded as S3.

[0041] Comparative Example 1: Compared with Example 1, the difference is that L-arginine is not added to the pickling liquid in step 2, and the rest are the same. Finally, a finished product is obtained, which is recorded as D1.

[0042] Comparative Example 2: Compared with Example 1, the difference is that after step 2, the coating treatment in step 3 is not performed, and the rest are the same. Finally, a finished product is obtained, which is recorded as D2.

[0043] Comparative Example 3: Compared with Example 1, the difference is that ordinary duck eggs that have not been fed with special feed are used as raw materials, and the rest are the same. Finally, a finished product is obtained, which is recorded as D3.

[0044] Comparative Example 4: Compared with Example 1, the differences are as follows: ordinary duck eggs that have not been fed with special feed are used as raw materials, L-arginine is not added to the pickling liquid in step 2, and the coating treatment in step 3 is not performed after step 2 is completed. All other steps are the same. The final product is obtained, which is recorded as D4.

[0045] Test Example 1: This test is designed to determine the content of the core organic selenium component, selenomethionine, in each sample.

[0046] The test steps are as follows: 1. Sample pretreatment: Take the finished eggs obtained in Examples 1-3 and Comparative Examples 1-4, peel off the eggshells, take the edible parts (egg whites and yolks), place them in a homogenizer, and homogenize them at high speed at 4°C for 2 minutes to prepare a uniform sample homogenate. After packaging, freeze and store at -20°C for later use.

[0047] 2. Enzymatic extraction: Accurately weigh approximately 0.5 g of sample and homogenize it in a centrifuge tube. Add 5 mL of 50 mmol / L Tris-HCl buffer (pH 7.5). Subsequently, add proteinase K solution to a final concentration of 100 μg / mL. Place the centrifuge tube in a 37°C water bath shaker and allow enzymatic digestion to proceed for 12 hours in the dark. After enzymatic digestion, heat the sample in a 100°C water bath for 10 minutes to inactivate the enzyme. After cooling to room temperature, centrifuge at 10,000 g for 15 minutes. Remove the supernatant and filter it through a 0.22 μm filter membrane. Collect the filtrate for analysis.

[0048] 3. Chromatography and mass spectrometry analysis: High performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICP-MS) was used for determination.

[0049] Chromatographic conditions: Anion exchange chromatography column was used for separation; the mobile phase was a gradient elution solution containing ammonium formate; the flow rate was 1.0 mL / min.

[0050] Mass spectrometry conditions: monitoring selenium isotopes 78 Se.

[0051] A series of concentration gradient standard solutions were prepared using a certified selenomethionine standard to generate a standard curve for quantification using the external standard method. Each sample was measured in triplicate, and the results were averaged.

[0052] The results of the determination of the selenomethionine content in each sample are shown in Table 1 below.

[0053] Table 1 Determination results of selenomethionine content in each sample Sample number Selenomethionine content (μg / g) S1 2.11 S2 1.83 S3 2.24 D1 0.87 D2 1.95 D3 0.07 D4 0.04 As shown in Table 1, the selenomethionine content in the final products of samples S1, S2, and S3, prepared using the complete technical solution of the present invention, was significantly higher than that of all the comparative examples. Among them, the organic selenium content in comparative examples D3 and D4, which were prepared from ordinary duck eggs, was almost negligible. This confirms that obtaining raw eggs rich in organic selenium and endogenous antioxidants through a specific feeding method is the fundamental prerequisite for achieving a high selenium content in the final product.

[0054] Comparing the results of S1 and D1 reveals the core innovation of this invention in the processing process. Under identical conditions, the selenomethionine content of sample D1 plummeted from 2.11 μg / g to 0.87 μg / g simply due to the lack of L-arginine in the pickling liquid, a loss of over 58%. This strongly demonstrates the effectiveness of introducing L-arginine as a sacrificial buffer in a strong alkaline environment. By preferentially neutralizing groups destructive to organic selenium, it successfully shields the selenomethionine in the egg from the chemical attack of the strong base, playing a critical role in process protection.

[0055] A comprehensive comparison of the results from S1, D2, and D3 reveals the overall advantages of the three-stage synergistic protection system of the present invention. Compared with D2, which only provides source protection (lacking a coating), or D3, which only provides process protection (lacking source enrichment), the complete example S1 exhibits the highest organic selenium preservation rate. This demonstrates that the three stages, from obtaining raw eggs enriched with endogenous antioxidants, to gentle curing using sacrificial buffers, and finally to the coating protection step, are closely linked and indispensable, together constituting a comprehensive, multi-dimensional protection for organic selenium, ultimately achieving maximum retention of the target functional ingredients in the product.

[0056] Test Example 2: This test aims to evaluate the ability of each sample to resist lipid oxidation during storage by simulating accelerated storage conditions. The evaluation indicator is the thiobarbituric acid reactive substances (TBARS) value, which reflects the content of malondialdehyde (MDA), a lipid oxidation product.

[0057] The test steps are as follows: 1. Accelerated storage: The finished eggs (in shell) obtained in Examples 1-3 and Comparative Examples 1-4 were placed in a single layer on a tray and placed in a constant temperature and humidity chamber set at 40±1°C and 75±5% for continuous storage for 30 days.

[0058] 2. Sample determination: After storage, remove the sample. The sample preparation method is the same as in Test Example 1 to obtain a sample homogenate. Accurately weigh 5.0 g of sample homogenate into a stoppered test tube and add an appropriate amount of trichloroacetic acid solution for protein precipitation and extraction. After centrifugation, take the supernatant and mix it with an equal volume of thiobarbituric acid (TBA) solution. Heat the mixture in a 95°C water bath for 40 minutes. At this time, MDA reacts with TBA to form a red compound. After the reaction is completed, quickly cool to room temperature. Use a spectrophotometer to measure the absorbance of the reaction solution at a wavelength of 532 nm. Calculate the MDA content in the sample using a standard curve prepared using a malondialdehyde standard. Each sample is measured in parallel three times, and the results are averaged.

[0059] The TBARS test results of each sample after accelerated storage are shown in Table 2 below.

[0060] Table 2 TBARS values of samples after accelerated storage Sample number TBARS value (mg MDA / kg) S1 0.26 S2 0.31 S3 0.22 D1 0.35 D2 0.88 D3 0.52 D4 1.47 The data in Table 2 demonstrate the advantages of the present invention's technical solution in improving product storage stability. The TBARS values of Examples S1, S2, and S3 were all maintained at extremely low levels, lower than those of all comparative examples. This demonstrates that the present method can effectively inhibit lipid oxidation in egg products during storage, thereby extending the shelf life of the product. Among them, Sample D4, prepared using traditional methods, had the highest TBARS value, indicating the most severe oxidative deterioration.

[0061] Comparing the results of S1 and D2, we can clearly see the key role of the composite bioactive coating in the back-end protection of the product. Under the condition that the raw materials and pickling process are exactly the same, the TBARS value of the D2 sample increased sharply by more than two times compared with S1 simply because the final coating step is missing. The mechanism is that the composite coating designed by the present invention provides a multifunctional physical and chemical composite barrier: the dense film layer formed by chitosan effectively blocks the penetration of external oxygen; the tea polyphenols coated in the film act as an efficient free radical scavenger and can actively neutralize a small amount of oxygen that penetrates; and phytic acid further consolidates this protection system by chelating the trace metal ions that catalyze the oxidation reaction and enhance the density of the film.

[0062] Comparing the results of S1, D2, and D3 reveals the essential need for the synergistic effect of the present invention's "endogenous protection" and "exogenous protection." Sample D3 (coated but without endogenous protection) showed improved stability compared to D4, but was still significantly inferior to S1. This demonstrates that establishing an endogenous protection system by pre-introducing antioxidants such as natural vitamin E and grape seed extract into the egg's feed is equally crucial for combating oxidation. Ultimately, only samples S1, S2, and S3, which combined endogenous protection with exogenous coating protection, exhibited the lowest oxidation levels. This fully demonstrates the comprehensive, synergistic protection system constructed by the present invention, which achieves optimal product quality protection through the combined action of internal antioxidants and external barriers.

[0063] Test Example 3: This test is designed to evaluate the total number of microorganisms on the eggshell surface of each sample after accelerated storage, so as to assess the ability of the method of the present invention to inhibit microbial infection.

[0064] The test steps are as follows: 1. Accelerated storage: The samples were stored in a constant temperature and humidity chamber at 40±1°C and 75±5% relative humidity for 30 consecutive days under the same storage conditions as in Test Example 2.

[0065] 2. Sample determination: After storage, take the samples out of the constant temperature and humidity chamber. In a sterile operating table, use a sterile cotton swab to evenly apply a 10 cm2 area on the surface of each sample eggshell. 2 Place the cotton swab with the sample in a test tube containing 9 mL of sterile saline and shake thoroughly for 1 minute to elute. This is the original bacterial solution. Perform a 10-fold gradient dilution of the original bacterial solution. Take 1 mL of the appropriately diluted bacterial solution and inoculate it on the plate count agar (PCA) medium using the pour plate method. Place the culture dish upside down in a constant temperature incubator at 37°C and culture for 48 hours. Count the number of colonies and calculate the total number of colonies per square centimeter of the eggshell surface (CFU / cm 2), the results are expressed as logarithmic values (log CFU / cm 2 Each sample was measured three times in parallel, and the results were averaged.

[0066] The results of the total bacterial count on the surface of each sample after accelerated storage are shown in Table 3 below.

[0067] Table 3 Total bacterial counts on eggshell surface after accelerated storage of each sample Sample number <![CDATA[Total surface colony count (log CFU / cm 2 )]]> S1 1.88 S2 1.95 S3 1.74 D1 1.91 D2 4.67 D3 1.98 D4 5.23 The data in Table 3 demonstrate the remarkable effectiveness of the present invention in inhibiting microbial growth on product surfaces and improving product hygiene and safety. After rigorous accelerated storage, the total bacterial count on the surfaces of all coated samples (S1, S2, S3, D1, and D3) remained extremely low. In contrast, the surface microbial counts of uncoated samples D2 and D4 were more than two logarithmic levels higher, indicating significant microbial contamination. This directly demonstrates that the coating step employed in the present invention provides a decisive microbial protection effect.

[0068] The core mechanism of this excellent antibacterial effect stems from the unique design of the composite bioactive coating. Chitosan, the film-forming matrix, is a natural broad-spectrum antimicrobial polymer. It interacts with negatively charged components on the surface of microbial cell membranes, disrupting their integrity and thereby inhibiting or even killing microorganisms. Furthermore, the dense physical film formed by cross-linking chitosan, tea polyphenols, and phytic acid effectively blocks microorganisms from adhering to the eggshell surface, providing a protective barrier.

[0069] A comprehensive comparison of all samples shows that the microbial safety of the final product is mainly determined by the exogenous protection step. However, the full-process protection system constructed by the present invention is an organic whole. The egg products with more stable quality and higher integrity obtained through source enrichment and process protection provide a better foundation for subsequent coating protection. Ultimately, it is this multi-dimensional coordinated protection from the inside out that ensures that the selenium-enriched egg products prepared by the present invention are not only more stable in chemical composition and have a higher preservation rate of functional ingredients, but also have incomparable advantages in terms of microbial safety and shelf life.

[0070] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for processing selenium-enriched egg products, characterized in that: The following steps are involved: (a) obtaining raw selenium-enriched eggs: adding a selenium source and an endogenous antioxidant synergist to poultry feed to obtain raw selenium-enriched eggs in which organic selenium and antioxidant substances are simultaneously enriched; (b) strong alkaline pickling and ripening: placing the raw selenium-enriched eggs in a pickling solution containing sodium hydroxide, sodium chloride and a sacrificial alkaline buffer for soaking and ripening; (c) Composite bioactive coating: The finished preserved egg product treated, cleaned and dried in step (b) is coated with a composite bioactive coating liquid consisting of a film-forming matrix, a primary antioxidant and a metal ion chelating agent and dried to form a protective film.

2. The method for processing selenium-enriched egg products according to claim 1, wherein The endogenous antioxidant synergist in step (a) is a combination of natural vitamin E and grape seed extract.

3. The method for processing selenium-enriched egg products according to claim 1, characterized in that: The sacrificial alkaline buffer in step (b) is L-arginine.

4. The method for processing selenium-enriched egg products according to claim 3, characterized in that: The components and concentrations of the pickling solution are: 35-55 g / L sodium hydroxide, 30-50 g / L sodium chloride, and 5-15 g / L L-arginine.

5. The method for processing selenium-enriched egg products according to claim 1, characterized in that: The composite bioactive coating in step (c) comprises: Chitosan as a film-forming matrix; Tea polyphenols as primary antioxidants; Phytic acid as a metal ion chelator and cross-linking agent.

6. The method for processing selenium-enriched egg products according to claim 5, characterized in that: The formula of the composite bioactive coating liquid is: 10-20 g / L chitosan, 3-6 g / L tea polyphenols, 1-3 g / L phytic acid, and 5-10 g / L glycerol are used as plasticizers.

7. The method for processing selenium-enriched egg products according to claim 5 or 6, characterized in that: The composite bioactive coating liquid is prepared using a 1.0-1.5% v / v L-lactic acid aqueous solution as a solvent.

8. The method for processing selenium-enriched egg products according to claim 1, characterized in that: The strong alkaline curing and aging in step (b) is carried out at a temperature of 20 to 25° C. and lasts for 25 to 35 days.

9. The method for processing selenium-enriched egg products according to claim 1, characterized in that: The drying process in step (c) is carried out at a temperature of 40 to 50° C. until a complete and dry protective film is formed on the surface of the eggshell.

10. The method for processing selenium-enriched egg products according to claim 1, characterized in that: The selenium source in step (a) is selenium-enriched yeast hydrolyzate, and its addition amount in poultry feed is 0.5-1.5 mg / kg in terms of selenium element.