An egg disinfection, preservation and fresh-keeping integrated composite coating solution and a processing method thereof

Abstract

This invention belongs to the fields of food biosafety and preservation technology, post-laying processing technology for poultry eggs, and natural biological preservatives. Specifically, it relates to a composite coating liquid and integrated treatment method that utilizes a combination of a lytic phage cocktail and an edible composite coating. The egg disinfection, antiseptic, and preservation integrated coating liquid of this invention combines pathogenic bacteriophage + putrefactive bacteriophage bacterial solution with an edible oil composite coating, achieving four functions: precise sterilization of the egg surface, long-lasting antibacterial effect, eggshell protection, and quality maintenance. This effectively solves the defects of existing egg preservation technologies, such as chemical residues, inconsistent sterilization, damage to the eggshell cuticle, and short shelf life.

Description

Technical Field

[0001] This invention belongs to the fields of food biosafety and preservation technology, post-laying processing technology for poultry eggs, and natural biological preservatives. Specifically, it relates to a composite coating liquid that uses a combination of a lytic phage cocktail and an edible composite coating, as well as an integrated treatment method for targeted disinfection, continuous preservation, and quality maintenance of eggs. Background Technology

[0002] Eggs are a staple food in the human diet, providing comprehensive nutrition and serving as the world's most widely consumed source of high-quality protein. However, during routine storage, a large number of microorganisms can enter the egg through the pores on its shell surface. Eggs are particularly susceptible to contamination by bacteria such as Salmonella, Escherichia coli, Proteus mirabilis, and Pseudomonas aeruginosa, leading to spoilage, affecting their edible value and processing quality, and posing food safety risks and economic losses.

[0003] Currently, the daily preservation of eggs typically includes the following methods: First, chemical disinfectants (sodium hypochlorite, peracetic acid, etc.) are used. However, this method only provides instantaneous sterilization and lacks sustained antibacterial ability. It also damages the eggshell's cuticle, accelerates moisture evaporation and CO2 escape, and poses a risk of chemical residue. Second, physical coatings are used. However, the coated mineral oil only provides passive barrier properties and lacks active sterilization, rendering it ineffective against already contaminated bacteria. Third, modified atmosphere packaging is used, but this has the problem of high cold chain costs, cannot reduce the initial bacterial load, and still cannot solve the problem of spoilage bacteria proliferation. Fourth, antibacterial coatings using plant essential oils or chitosan are used, but these have drawbacks such as poor antibacterial spectrum, weak specificity, poor durability, and the potential to alter the egg's flavor.

[0004] Currently, egg coating has become a common technique for controlling egg quality and extending shelf life. Its advantages include low production cost, good preservation effect, and ease of automation, making it widely popular. However, the egg coating materials widely used in the market are liquid paraffin and mineral oil. Due to their lack of edibility, biodegradability, antibacterial properties, and toxicological testing capabilities, their safety in the food industry has been consistently questioned, and customer acceptance in the market has been less than satisfactory.

[0005] Therefore, there is a growing demand in the field for a safe, edible, targeted sterilization, long-lasting antiseptic, and quality-protecting biological preservation technology for eggs. Summary of the Invention

[0006] Therefore, the technical problem to be solved by the present invention is to provide a targeted phage. An edible composite coating liquid, which can perform targeted disinfection, continuous preservation and quality maintenance on eggs in an integrated manner; The second technical problem to be solved by this invention is to provide a targeted phage-based... An integrated treatment method for disinfection, preservation, and freshness maintenance of eggs using edible composite coating liquid.

[0007] To address the aforementioned technical problems, this invention provides an integrated composite coating liquid for egg disinfection, preservation, and freshness maintenance, comprising a mixture of a film-based liquid and a bacteriophage bacterial solution; wherein, The membrane base liquid includes food-grade oils; The bacteriophage bacterial solution is a bacterial solution containing bacteriophages, wherein the bacteriophages include a mixture of pathogenic bacteriophages and putrefactive bacteriophages.

[0008] Specifically, in the integrated composite coating liquid for egg disinfection, preservation, and freshness maintenance, the ratio of pathogenic bacteriophages to putrefactive bacteriophages in the bacteriophage solution is 1-2:1-2.

[0009] Specifically, in the integrated composite coating liquid for egg disinfection, preservation, and freshness maintenance, the bacteriophage bacterial solution contains: The pathogenic bacteriophage includes at least one of Salmonella bacteriophage, Escherichia coli bacteriophage, or Staphylococcus bacteriophage; The putrefactive bacteriophage includes at least one of Pseudomonas bacteriophage, Enterobacter cloacae, or Proteus mirabilis bacteriophage.

[0010] Specifically, in the integrated composite coating liquid for egg disinfection, preservation, and freshness maintenance, the bacteriophage bacterial solution contains: The pathogenic bacteriophages include a mixture of Salmonella bacteriophages, Escherichia coli bacteriophages, and Staphylococcus bacteriophages in a ratio of 1-2:1-2:1-2; The putrefactive bacteriophages comprise a mixture of Pseudomonas bacteriophages, Enterobacter cloacae, and Proteus mirabilis bacteriophages in a ratio of 1-2:1-2:1-2.

[0011] Specifically, in the integrated composite coating liquid for egg disinfection, preservation, and freshness maintenance, the bacteriophage bacterial solution contains: The Salmonella phage mentioned includes Salmonella phage SG8P3, which is classified as Salmonella pullorum phage and has the accession number CCTCC NO: M 2020205. The Escherichia coli phage includes Escherichia coli phage EC35P1, which is classified as Escherichiacoliphage and has the accession number CCTCC NO: M 2020438. The staphylococcal phage includes Staphylococcus aureus phage Sa88P1, which is classified as Staphylococcus aureus phage and has the accession number CCTCC NO: M 2020767. The Pseudomonas phage includes Pseudomonas lundensis phage PL1P1, which is classified as Pseudomonas lundensis phage and has the accession number CCTCC NO: M 20251191. The *Proteus mirabilis* phage includes *Proteus mirabilis* phage ZDPM. P1, classified as *Proteus mirabilis phage*, with accession number CCTCC NO: M 2022475.

[0012] Specifically, the integrated composite coating liquid for egg disinfection, preservation, and freshness maintenance includes the following components in terms of mass content: Bacteriophage, wherein the titer of the bacteriophage based on the bacterial culture is ≥10 10 PFU / mL; Trehalose, wherein the trehalose concentration is 0.5-1.0 wt% based on the mass concentration of the bacteriophage bacterial solution; MgCl2, wherein the concentration of MgCl2 is 3-8 mM based on the concentration of the bacteriophage culture; Add PBS buffer to bring the total to 100 wt%.

[0013] Specifically, the egg disinfection, anti-corrosion and preservation integrated composite coating liquid includes food-grade mineral oil.

[0014] Specifically, the integrated composite coating solution for egg disinfection, preservation, and freshness maintenance, wherein the bacteriophage is based on a final concentration ≥10 of the coating solution. 8 PFU / g.

[0015] This invention also discloses the application of the integrated composite coating liquid for egg disinfection, preservation, and freshness maintenance in the field of fresh egg disinfection, preservation, and freshness maintenance.

[0016] This invention also discloses an integrated method for disinfecting, preserving, and keeping eggs fresh, comprising the following steps: (1) Pre-treatment of fresh eggs; (2) The eggs are coated with the integrated egg disinfection, anti-corrosion and preservation coating liquid; (3) Dry at low temperature to obtain the product.

[0017] Specifically, the integrated egg disinfection, preservation, and freshness maintenance method is as follows: In step (1), the pretreatment step includes washing the fresh eggs in warm water at 40-45℃ for 30-60 seconds; and / or, In step (2), the coating thickness is 20-40 μm; and / or, In step (2), the coating step includes an dip-coating or spraying process; and / or, In step (3), the low-temperature drying includes using The process involves drying with 30℃ cold air for 3-5 minutes.

[0018] The egg disinfection, anti-corrosion and preservation integrated coating liquid of the present invention uses a combination of pathogenic bacteriophage and putrefactive bacteriophage bacterial liquid with edible oil composite coating to achieve four functions: precise sterilization of egg surface, long-lasting antibacterial effect, eggshell protection and quality maintenance. It effectively solves the defects of existing egg preservation technologies such as chemical residues, unsustainable sterilization, damage to eggshell cuticle, and short shelf life.

[0019] In the egg disinfection, preservation, and freshness-preserving integrated coating liquid of this invention, the bacteriophage is a mixture of pathogenic bacteriophages and putrefactive bacteriophages, especially a mixture of Salmonella bacteriophages, Escherichia coli bacteriophages, Staphylococcus bacteriophages, Pseudomonas bacteriophages, Enterobacter cloacae, and Proteus mirabilis bacteriophages. This mixture can specifically kill pathogenic bacteria such as Salmonella, Escherichia coli, and Proteus mirabilis, reducing foodborne safety risks. It also continuously inhibits putrefactive bacteria such as Pseudomonas during the shelf life, effectively protecting the integrity of the eggshell cuticle, reducing moisture and CO2 loss, delaying protein thinning and pH rise, and effectively delaying spoilage, off-odors, and yolk loss, thus ensuring the quality of the eggs.

[0020] The egg disinfection, anti-corrosion and preservation integrated coating liquid of the present invention can achieve a shelf life of up to 21 days under refrigeration at 4℃ and a shelf life of up to 7-14 days at room temperature. The preserved eggs have no chemical residues, no drug resistance and are safe to eat. It is suitable for industrial grading and packaging production lines for fresh eggs and is applicable to the processing of eggs that can be eaten raw, branded eggs and long shelf-life eggs.

[0021] The integrated egg disinfection, preservation and freshness protection method of the present invention, after coating with the composite coating liquid and then drying at low temperature, can protect the bacteriophages to survive stably in a dry environment, achieve a slow-release and long-lasting effect, and help protect the eggshell cuticle, maintain Haugh units and weight loss rate, and improve the product grade.

[0022] The integrated egg disinfection, preservation and freshness maintenance method of the present invention, through the integrated process of pre-cleaning, composite coating and low temperature cold air drying, can achieve four functions: precise sterilization of egg surface, long-term antibacterial effect, eggshell protection and quality maintenance. It is not only simple to operate, but also has a significant preservation effect and is suitable for daily use. Attached Figure Description

[0023] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein: Figure 1(a) shows the results of phage plaque observation in the contents of the egg in Experiment Example 1, and (b)-(g) are electron micrographs of the detected Salmonella phage, Escherichia coli phage, Staphylococcus phage, Pseudomonas phage, Enterobacter cloacae phage, and Proteus mirabilis phage, respectively. Figure 2 The bacteriophage described in this invention Schematic diagram of the cross-sectional structure of an edible composite coated eggshell; Figure 3 shows the test results of eggs stored at room temperature (25℃) in Experiment Example 2. (a) is the 0-21 day bactericidal kinetics comparison curve of eggs (change in colony count); (b) is the comprehensive quality curve of eggs after 21 days (change in Haugh units). Figure 4 shows the test results under refrigeration at 4℃ in Experiment Example 3. (a) is the 0-21 day bactericidal kinetics comparison curve of eggs (change in colony count); (b) is the comprehensive quality curve of eggs after 21 days (change in Haugh units). Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention.

[0025] To address the difficulty in preserving fresh eggs, the present invention provides an integrated composite coating liquid for egg disinfection, preservation, and freshness protection, comprising a mixture of a film-based liquid and a bacteriophage bacterial solution, as described in the following embodiment; wherein, The membrane base liquid includes food-grade oils; The bacteriophage bacterial solution is a bacterial solution containing bacteriophages, wherein the bacteriophages include a mixture of pathogenic bacteriophages and putrefactive bacteriophages.

[0026] In some specific embodiments, the ratio of pathogenic bacteriophages to putrefactive bacteriophages in the bacteriophage culture is 1-2:1-2.

[0027] Specifically, in the integrated composite coating liquid for egg disinfection, preservation, and freshness maintenance, the bacteriophage bacterial solution contains: The pathogenic bacteriophage includes at least one of Salmonella bacteriophage, Escherichia coli bacteriophage, or Staphylococcus bacteriophage; The putrefactive bacteriophage includes at least one of Pseudomonas bacteriophage, Enterobacter cloacae, or Proteus mirabilis bacteriophage.

[0028] In some specific embodiments, the bacteriophage bacterial solution contains: The pathogenic bacteriophages include a mixture of Salmonella bacteriophages, Escherichia coli bacteriophages, and Staphylococcus bacteriophages in a ratio of 1-2:1-2:1-2; The putrefactive bacteriophages comprise a mixture of Pseudomonas bacteriophages, Enterobacter cloacae, and Proteus mirabilis bacteriophages in a ratio of 1-2:1-2:1-2.

[0029] In some specific embodiments, the bacteriophage bacterial solution includes the following components in terms of mass content: Bacteriophage, wherein the titer of the bacteriophage based on the bacterial culture is ≥10 10 PFU / mL; Trehalose, wherein the trehalose concentration is 0.5-1.0 wt% based on the mass concentration of the bacteriophage bacterial solution; MgCl2, wherein the concentration of MgCl2 is 3-8 mM based on the concentration of the bacteriophage culture; Add PBS buffer to bring the total to 100 wt%.

[0030] In some specific embodiments, the food-grade oil includes food-grade mineral oil.

[0031] In some specific embodiments, the bacteriophage is based on a final concentration of ≥10⁻⁶ of the coating solution. 8 PFU / g.

[0032] In the following embodiments of the present invention, an integrated method for disinfection, preservation, and freshness maintenance of eggs is also disclosed, comprising the following steps: (1) Pre-treatment of fresh eggs; (2) The eggs are coated with the integrated egg disinfection, anti-corrosion and preservation coating liquid; (3) Dry at low temperature to obtain the product.

[0033] In some specific embodiments, step (1) includes washing the fresh eggs with warm water at 40-45°C for 30-60 seconds.

[0034] In some specific embodiments, in step (2), the coating thickness of the coating step is 20-40 μm.

[0035] In some specific embodiments, step (2) includes a coating process such as dip-coating or spraying.

[0036] In some specific embodiments, in step (3), the low-temperature drying includes... The process involves drying with 30℃ cold air for 3-5 minutes.

[0037] In the following embodiments of the present invention, the bacteriophage includes a mixture of Salmonella bacteriophage, Escherichia coli bacteriophage, Staphylococcus bacteriophage, Pseudomonas bacteriophage, Enterobacter cloacae, and Proteus mirabilis bacteriophage.

[0038] As an exemplary embodiment, in the following embodiments of the present invention, the Salmonella phage selected is Salmonella phage SG8P3, which is classified and named Salmonella pullorum phage, with accession number CCTCC NO: M2020205, deposited at the China Center for Type Culture Collection, located at Wuhan University, Luojia Mountain, Wuchang, Wuhan, Hubei Province, on June 12, 2020.

[0039] As an exemplary embodiment, in the following embodiments of the present invention, the Escherichia coli phage is selected as Escherichia coli phage EC35P1, which is classified and named Escherichia coliphage. Its accession number is CCTCC NO: M2020438, the depositary institution is China Center for Type Culture Collection, located at Wuhan University, Luojia Mountain, Wuchang, Wuhan, Hubei Province, and the deposit date is August 20, 2020.

[0040] As an exemplary embodiment, in the following embodiments of the present invention, the staphylococcal phage is selected as Staphylococcus aureus phage Sa88P1, which is classified as Staphylococcus aureus phage, with accession number CCTCCNO: M 2020767. The depositary institution is the China Center for Type Culture Collection, located at Wuhan University, Luojia Mountain, Wuchang District, Wuhan City, Hubei Province, and the deposit date is November 23, 2020.

[0041] As an exemplary embodiment, in the following embodiments of the present invention, the Pseudomonas phage is selected as Pseudomonas lundensis phage PL1P1, which is classified and named as Pseudomonas lundensis phage. Its accession number is CCTCC NO: M 20251191, the depositary institution is China Center for Type Culture Collection, located at Wuhan University, Luojia Mountain, Wuchang, Wuhan, Hubei Province, and the deposit date is May 26, 2025.

[0042] As an exemplary embodiment, in the following embodiments of the present invention, the *Proteus mirabilis* phage is selected as *Proteus mirabilis* phage ZDPM. P1, classified as *Proteus mirabilis phage*, with accession number CCTCCNO: M 2022475, is deposited at the China Center for Type Culture Collection, located at Wuhan University, Luojia Mountain, Wuchang District, Wuhan City, Hubei Province, on April 25, 2022.

[0043] As an exemplary implementation, in the following embodiments of the present invention, the Enterobacter cloacae bacteriophage can be a commercially available product. In this solution, the Enterobacter cloacae bacteriophage commercially available from Figelek (Nanjing) Biotechnology Co., Ltd. is selected, such as the "Jishining" bacteriophage product.

[0044] As an exemplary embodiment, in the following embodiments of the present invention, the membrane base liquid is selected as 10# food-grade white mineral oil.

[0045] As an exemplary embodiment, in the following embodiments of the present invention, the bacteriophage bacterial solution is prepared by mixing using conventional methods.

[0046] As an exemplary embodiment, in the following embodiments of the present invention, the mixing step of the membrane base liquid and the bacteriophage bacterial solution can be carried out by conventional methods.

[0047] Example 1 The preparation method of the composite coating liquid described in this embodiment includes the following steps: (1) Salmonella phage SG8P3, Escherichia coli phage EC35P1, Staphylococcus phage Sa88P1, Pseudomonas phage PL1P1, Enterobacter cloacae, and Proteus mirabilis phage ZDPM were selected. P1, mixed in a ratio of 1:1:1:1:1:1, yielded a phage composition; trehalose, MgCl2, and PBS buffer (pH 6.8-7.2) were then mixed to prepare a phage culture, wherein the phage titer in the culture was 10. 10 The concentration of PFU / mL, the concentration of trehalose is 0.5%, and the concentration of MgCl2 is 5mM; (2) Select 10# food-grade white mineral oil as the membrane base solution and mix it with the bacteriophage bacterial solution to obtain the desired coating solution; wherein, the amount of 10# food-grade white mineral oil is used to adjust the final concentration of the bacteriophage in the coating solution to 10. 8 The standard is PFU / mL.

[0048] The integrated egg disinfection, preservation, and freshness maintenance method described in this embodiment includes the following steps: (1) Take fresh eggs to be processed and spray them with 42°C warm water for 45 seconds; (2) The composite coating liquid is used to coat the eggs after the above treatment; the coating thickness is controlled to be 30 μm by conventional dip-lift coating method; (3) Dry at a low temperature of 25°C for 4 minutes to obtain the product.

[0049] Example 2 The preparation method of the composite coating liquid described in this embodiment includes the following steps: (1) Salmonella phage SG8P3, Escherichia coli phage EC35P1, Staphylococcus phage Sa88P1, Pseudomonas phage PL1P1, Enterobacter cloacae, and Proteus mirabilis phage ZDPM were selected. P1, mixed in a ratio of 1:2:1:2:1:2, yielded a phage composition; trehalose, MgCl2, and PBS buffer (pH 6.8-7.2) were then mixed to prepare a phage culture, wherein the phage titer in the culture was 10. 10 The concentration of PFU / mL, the concentration of trehalose is 0.8%, and the concentration of MgCl2 is 8mM; (2) Select 10# food-grade white mineral oil as the membrane base solution and mix it with the bacteriophage bacterial solution to obtain the desired coating solution; wherein, the amount of 10# food-grade white mineral oil is used to adjust the final concentration of the bacteriophage in the coating solution to 10. 8 The standard is PFU / mL.

[0050] The integrated egg disinfection, preservation, and freshness maintenance method described in this embodiment includes the following steps: (1) Take fresh eggs to be processed and spray them with 40℃ warm water for 60 seconds; (2) The composite coating liquid is used to coat the eggs after the above treatment; the coating thickness is controlled to be 20 μm by conventional dip-lift coating method; (3) Dry at a low temperature of 25°C for 3 minutes to obtain the product.

[0051] Example 3 The preparation method of the composite coating liquid described in this embodiment includes the following steps: (1) Salmonella phage SG8P3, Escherichia coli phage EC35P1, Staphylococcus phage Sa88P1, Pseudomonas phage PL1P1, Enterobacter cloacae, and Proteus mirabilis phage ZDPM were selected. P1, mixed in a ratio of 2:1:2:1:2:1, yielded a phage composition; trehalose, MgCl2, and PBS buffer (pH 6.8-7.2) were then mixed to prepare a phage culture, wherein the phage titer in the culture was 10. 10 The concentration of PFU / mL, the concentration of trehalose is 1.0%, and the concentration of MgCl2 is 3mM; (2) Select 10# food-grade white mineral oil as the membrane base solution and mix it with the bacteriophage bacterial solution to obtain the desired coating solution; wherein, the amount of 10# food-grade white mineral oil is used to adjust the final concentration of the bacteriophage in the coating solution to 10. 8 The standard is PFU / mL.

[0052] The integrated egg disinfection, preservation, and freshness maintenance method described in this embodiment includes the following steps: (1) Take fresh eggs to be processed and spray them with 45℃ warm water for 30 seconds; (2) The composite coating liquid is used to coat the eggs after the above treatment; the coating thickness is controlled to be 30 μm by conventional dip-lift coating method; (3) Dry at a low temperature of 25°C for 5 minutes to obtain the product.

[0053] Comparative Example 1 This comparative scheme uses sodium hypochlorite-composite coating solution to treat fresh eggs.

[0054] The sodium hypochlorite-composite coating solution comprises: The treatment method of the sodium hypochlorite-composite coating solution is the same as in Example 1.

[0055] Experimental Example 1. Microscopic detection of eggs In this experimental example, fresh eggs were treated with the coating solution and treatment method described in Example 1, and the bacteriophages were observed after standing for 21 days. Microscopic details of edible composite coated eggshells.

[0056] In this experimental example, the contents of the experimental egg were analyzed. As shown in Figure 1(a), active phage plaques could be detected on the bacterial culture dish, indicating that the bacteriophages in the coating solution can penetrate into the egg through the pores of the eggshell, thus achieving the preservation of the egg from the inside.

[0057] In this experimental example, further targeted analysis detected the following bacteriophages: Salmonella SG8P3, Escherichia coli EC35P1, Staphylococcus aureus Sa88P1, Pseudomonas aeruginosa PL1P1, Enterobacter cloacae, and Proteus mirabilis ZDPM. Electron micrographs of P1 are shown in Figure 1(b)-(g).

[0058] In this experimental example, a schematic diagram of the cross-sectional structure of the eggshell is shown in the attached figure. Figure 2As shown in the diagram. 1-Edible composite coating layer, 2-Egg contents, 3-Eggshell cuticle, 4-Eggshell layer, 5-Eggshell membrane, 6-Released active bacteriophage. This further demonstrates how bacteriophages can penetrate the eggshell surface and enter the egg's interior.

[0059] 2. Basic room temperature preservation effect (25℃, 7-14 days) In this experimental example, fresh eggs were treated with the coating solution and treatment method under the sodium hypochlorite-composite coating scheme in Example 1 and Comparative Example 1, and eggs without coating treatment were used as blank controls. All eggs were placed at room temperature (25°C) and stored under the same conditions for 7-14 days.

[0060] Samples were taken at storage days 0, 3, 7, 14, and 21. Three eggs were randomly selected from each group for each sample, and the following indicators were measured: (1) Sensory quality of eggs: Observe whether the eggshell surface is moldy, sticky, or has an odor, record the degree of egg spoilage, and score according to four levels: fresh (9-10 points), slightly spoiled (6-8 points), moderately spoiled (3-5 points), and severely spoiled (0-2 points). The initial sensory score is 9.5±0.3 points. (2) Determination of total colony count: Refer to GB 4789.2-2016 "Food Microbiology Examination: Determination of Total Colony Count", wipe a 5cm×5cm area on the surface of the egg with a sterile cotton swab, wash it off and perform a 10-fold serial dilution, select 2-3 suitable dilutions and spread them on nutrient agar medium, incubate at 37℃ for 24-48h, count the total colony count, and control the initial total colony count on the egg surface to below 10² CFU / cm²; (3) Physicochemical quality of eggs: Haugh units (initial value ≥70, grade A fresh eggs), yolk index (initial value 0.38±0.02), and shell strength (initial value 35±2 N) were measured using an egg quality analyzer; the pH value of the egg liquid was measured using a pH meter (initial value 7.2±0.1); the weight loss rate of eggs was determined by gravimetric method, and the calculation formula was: weight loss rate (%) = (initial weight - sample weight) / initial weight × 100%; (4) Volatile basic nitrogen (TVB-N) content: Refer to GB 5092.228-2016 "Determination of volatile basic nitrogen in food" and use semi-micro nitrogen determination method. The initial TVB-N content of fresh eggs is ≤5 mg / 100g, and the spoilage threshold is set at 15mg / 100g to evaluate the degree of egg spoilage.

[0061] All experiments were performed in triplicate, and data are expressed as mean ± standard deviation.

[0062] One-way ANOVA was performed using SPSS 26.0 statistical software to compare the significance of differences (P < 0.05) in various indicators of eggs among different treatment groups and different storage times. 0.05 is considered statistically significant (P < 0.05). (0.01 indicates a highly significant difference), and Duncan's test was used for multiple comparisons.

[0063] In this experimental example, the test results are shown in Table 1 and Figure 3 below. Note: Different letters in the same row represent the significance level P. 0.05, where the same letter indicates no significant difference (P). 0.05.

[0064] Table 1. Test data at 25℃ (room temperature storage)

[0065] As can be seen, under the composite coating liquid and treatment method described in this invention, fresh eggs can achieve a total bacterial count of 7 days under basic room temperature preservation (25℃, 7-14 days). 10 3 CFU / sample, total bacterial count after 14 days 10 CFU / egg, 7-day Huff Units: ≥62 (Grade A), 14-day Huff Units: ≥59 (Grade B), 14-day weight loss rate: ≤2.0%, and the preserved eggs have no off-odor, no broken yolks, and no spoilage.

[0066] Based on the above data, it can be seen that compared with the blank control, sodium hypochlorite-composite coating group, and the phage-composite coating group described in this invention have significant advantages in antibacterial and preservation effects. The phages in the coating solution can effectively inhibit the proliferation of microorganisms on the egg surface. The total number of colonies in the phage-composite coating group is much lower than that in the control group and sodium hypochlorite-composite coating, and the number of spoilage bacteria and pathogenic bacteria is reduced by 1-3 orders of magnitude. Moreover, phage treatment can effectively delay the deterioration of egg quality, slow down the increase in weight loss rate and TVB-N content, and achieve higher retention rates of Haugh units and eggshell strength. The eggs maintain fresh egg quality during a 14-day storage period at room temperature, and the spoilage time is significantly delayed.

[0067] It is evident that the composite coating liquid and integrated processing technology described in this invention can achieve fresh preservation of eggs for up to 14 days at room temperature.

[0068] 3. Basic refrigeration preservation effect (4℃, 21 days) In this experimental example, fresh eggs were treated with the coating solution and treatment method under the sodium hypochlorite-composite coating scheme in Example 1 and Comparative Example 1, and eggs without coating treatment were used as blank control. All eggs were placed in a refrigerated environment (4°C) and stored under the same conditions for 21 days.

[0069] Samples were taken at 0d, 3d, 7d, 14d and 21d of storage, with 3 eggs randomly selected from each group each time. Relevant indicators were measured, and the specific test indicators and methods were the same as in Experiment 1 above.

[0070] In this experimental example, the test results are shown in Table 2 and Figure 4 below. Note: Different letters in the same row represent the significance level P. 0.05, where the same letter indicates no significant difference (P). 0.05.

[0071] Table 2. Test data under 4℃ refrigeration conditions

[0072] As can be seen, under the composite coating liquid and treatment method described in this invention, fresh eggs can achieve a total bacterial count of 21 days under basic cold storage preservation (4℃, 21 days). 10 CFU / piece, ≥62 Haugh units in 21 days (Grade A), 21-day weight loss rate 2.0%, and the preserved eggs have no off-odor, no broken yolks, and no spoilage.

[0073] Based on the above data, it can be seen that compared with the blank control, sodium hypochlorite-composite coating group, the phage-composite coating group described in this invention has significant advantages in antibacterial and preservation effects. The phages in the coating solution can effectively inhibit the proliferation of microorganisms on the egg surface. The total number of colonies in the phage-composite coating group is much lower than that in the control group and sodium hypochlorite-composite coating, and the number of spoilage bacteria and pathogenic bacteria is reduced by 1-3 orders of magnitude. Moreover, phage treatment can effectively delay the deterioration of egg quality, slow down the increase rate of weight loss and TVB-N content, and achieve higher retention rates of Haugh units and eggshell strength. The eggs maintain fresh egg quality during a 21-day storage period at 4℃, and the spoilage time is significantly delayed. Furthermore, the preservation effect of phage is more stable under 4℃ refrigeration conditions, and all indicators are superior to those of room temperature storage.

[0074] It is evident that the composite coating liquid and integrated processing technology described in this invention can achieve fresh preservation of eggs for up to 21 days under refrigeration conditions.

[0075] In summary, the composite coating liquid of this invention combines pathogenic bacteriophage, putrefactive bacteriophage, and edible oil composite coating. Through an integrated process of pre-cleaning, composite coating, and low-temperature cold air drying, the bacteriophage in the resulting bacteriophage-composite coating can be slowly released into the egg to kill bacteria, extending the egg's shelf life. Overall, it achieves four functions: precise sterilization of the egg surface, long-lasting antibacterial effect, eggshell protection, and quality maintenance. It can effectively solve the defects of existing egg preservation technologies, such as chemical residues, inconsistent sterilization, damage to the eggshell cuticle, and short shelf life.

[0076] The embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A composite coating liquid for disinfecting, preserving, and keeping eggs fresh, characterized in that, It includes a mixture of membrane-based solution and bacteriophage culture; wherein, The membrane base liquid includes food-grade oils; The bacteriophage bacterial solution is a bacterial solution containing bacteriophages, wherein the bacteriophages include a mixture of pathogenic bacteriophages and putrefactive bacteriophages.

2. The integrated composite coating liquid for egg disinfection, preservation, and freshness maintenance according to claim 1, characterized in that, In the phage culture, the ratio of pathogenic bacteriophages to putrefactive bacteriophages is 1-2:1-2.

3. The integrated composite coating liquid for egg disinfection, preservation, and freshness maintenance according to claim 1 or 2, characterized in that, In the bacteriophage bacterial solution: The pathogenic bacteriophage includes at least one of Salmonella bacteriophage, Escherichia coli bacteriophage, or Staphylococcus bacteriophage; The putrefactive bacteriophage includes at least one of Pseudomonas bacteriophage, Enterobacter cloacae, or Proteus mirabilis bacteriophage.

4. The integrated composite coating liquid for egg disinfection, preservation, and freshness maintenance according to claim 3, characterized in that, In the bacteriophage bacterial solution: The pathogenic bacteriophages include a mixture of Salmonella bacteriophages, Escherichia coli bacteriophages, and Staphylococcus bacteriophages in a ratio of 1-2:1-2:1-2; The putrefactive bacteriophages comprise a mixture of Pseudomonas bacteriophages, Enterobacter cloacae, and Proteus mirabilis bacteriophages in a ratio of 1-2:1-2:1-2.

5. The integrated composite coating liquid for egg disinfection, preservation, and freshness maintenance according to claim 3 or 4, characterized in that: The Salmonella phage mentioned includes Salmonella phage SG8P3, which is classified as Salmonella pullorumphage and has the accession number CCTCC NO: M 2020205. The Escherichia coli phage includes Escherichia coli phage EC35P1, which is classified as Escherichiacoliphage and has the accession number CCTCC NO: M 2020438. The staphylococcal phage includes Staphylococcus aureus phage Sa88P1, which is classified as Staphylococcus aureus phage and has the accession number CCTCC NO: M 2020767. The Pseudomonas phage includes Pseudomonas lundensis phage PL1P1, which is classified as Pseudomonas lundensis phage and has the accession number CCTCC NO: M 20251191. The *Proteus mirabilis* phage includes *Proteus mirabilis* phage ZDPM. P1, classified as *Proteusmirabilis phage*, with accession number CCTCC NO: M 2022475.

6. The integrated composite coating liquid for egg disinfection, preservation, and freshness maintenance according to any one of claims 1-5, characterized in that, The bacteriophage bacterial solution comprises the following components in terms of mass content: Bacteriophage, wherein the titer of the bacteriophage based on the bacterial culture is ≥10 10 PFU / mL; Trehalose, wherein the trehalose concentration is 0.5-1.0 wt% based on the mass concentration of the bacteriophage bacterial solution; MgCl2, wherein the concentration of MgCl2 is 3-8 mM based on the concentration of the bacteriophage culture; Add PBS buffer to bring the total to 100 wt%.

7. The integrated composite coating liquid for egg disinfection, preservation, and freshness maintenance according to any one of claims 1-6, characterized in that: The food-grade oils include food-grade mineral oils; And / or, the phage is based on a final concentration ≥10 of the coating solution. 8 PFU / g.

8. The application of the integrated composite coating liquid for egg disinfection, preservation and freshness protection as described in any one of claims 1-7 in the field of fresh egg disinfection, preservation and freshness protection.

9. A method for integrated disinfection, preservation, and freshness maintenance of eggs, characterized in that, Includes the following steps: (1) Pre-treatment of fresh eggs; (2) The eggs are coated with the integrated composite coating liquid for disinfection, preservation and freshness protection of eggs as described in any one of claims 1-7; (3) Dry at low temperature to obtain the product.

10. The integrated egg disinfection, preservation, and freshness maintenance method according to claim 9, characterized in that: In step (1), the pretreatment step includes washing the fresh eggs in warm water at 40-45℃ for 30-60 seconds; and / or, In step (2), the coating thickness is 20-40 μm; and / or, In step (2), the coating step includes an dip-coating or spraying process; and / or, In step (3), the low-temperature drying includes using The process involves drying with 30℃ cold air for 3-5 minutes.

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