A method for controlling biogenic amines in the processing of marine fish

Abstract

This application discloses a method for controlling biogenic amines in the processing of marine fish, relating to the technical field of marine fish processing. The method includes thawing raw fish, pretreatment, biogenic amine control, and post-treatment. The main method for controlling biogenic amines involves first dripping antibacterial plant essential oil onto the surface of boneless fish fillets, and then soaking the fillets in a biogenic amine inhibitor (oregano essential oil-chitosan preservative solution) for 10-30 minutes. This application effectively improves the control of biogenic amines in marine fish. The volatile compounds in the plant essential oil have multiple functions, including antibacterial, insecticidal, and antiviral effects. When dripped onto the fish fillets, they can inhibit bacteria, and the essential oil flavor can reduce the fishy smell of marine fish. The subsequent soaking with the biogenic amine inhibitor reduces the formation of biogenic amines, effectively controlling their production and improving the overall control of biogenic amines in marine fish.

Description

Technical Field

[0001] This application relates to the technical field of marine fish processing, and in particular to a method for controlling biogenic amines in the processing of marine fish. Background Technology

[0002] The processing of marine fish is often accompanied by problems such as strong fishy smell, easy discoloration, poor tissue structure stability, easy loss of nutrients, and high loss rate. Marine fish will produce biogenic amines during processing and storage, which can easily lead to excessive biogenic amine levels. They are high-histamine fish, which can have a safety impact on consumers.

[0003] Biogenic amines are a general term for a class of low-molecular-weight organic compounds containing amino groups that possess biological activity. They can be considered substances formed by replacing 1-3 hydrogen atoms in an ammonia molecule with alkyl or aryl groups. They are low-molecular-weight organic bases belonging to aliphatic, ester-cyclic, or heterocyclic groups, commonly found in animals, plants, and food. They are also precursors for the synthesis of hormones, alkaloids, nucleotides, proteins, and aromatic compounds. Moderate intake of biogenic amines can promote growth, enhance metabolic activity, boost immunity, and scavenge free radicals; however, excessive intake can cause adverse physiological reactions such as headaches, abdominal cramps, and vomiting.

[0004] Regarding the aforementioned technologies, the treatment of biogenic amines in marine fish typically involves distillation, heating, and then packaging and freezing to remove some of the existing biogenic amines. However, biogenic amines continue to be produced after the fish dies, and existing technologies are not very effective in controlling biogenic amines during subsequent treatment processes. Summary of the Invention

[0005] To improve the control of biogenic amines in marine fish, this application provides a method for controlling biogenic amines in the processing of marine fish.

[0006] The method for controlling biogenic amines in the processing of marine fish provided in this application adopts the following technical solution:

[0007] A method for controlling biogenic amines in the processing of marine fish includes the following steps:

[0008] S1, Thawing raw fish: Let frozen seawater fish thaw by standing still;

[0009] S2, Pre-treatment: After thawing, the seawater fish is washed with running water, then sliced ​​and deboned. It is then washed again with running water and the fish is inspected. After removing foreign objects, it is washed to obtain boneless fish fillets.

[0010] S3, Biogenic Amine Control: First, drip antibacterial plant essential oil onto the surface of the boneless fish fillet, and then soak the boneless fish fillet for 10-30 minutes using a biogenic amine inhibitor, which is oregano essential oil-chitosan preservative solution.

[0011] S4, Post-processing: Dry the soaked fish fillets, package them, and store them in a cold storage.

[0012] Optionally, in step S3, the volume fraction of oregano essential oil in the oregano essential oil-chitosan preservative solution is 0.1% to 0.3%, and the mass concentration of chitosan is 10 to 20 g / L.

[0013] By adopting the above technical solution, the main biogenic amine in marine fish is histamine. Histamine is a product of bacteria decomposing amino acids in fish meat. Its production requires two conditions: free histidine and amine-producing bacteria. The filleting and deboning of raw fish can be completed manually and mechanically. After inspection, it is ensured that there are no fish bones, scales, or foreign objects left on the fillets. After washing, clean, boneless fish fillets are obtained, achieving preliminary sterilization. The plant essential oils and biogenic amine inhibitors are edible. The volatile compounds in the plant essential oils have multiple functions, including antibacterial, insecticidal, and antiviral effects. When dripped onto the fish fillets, they can inhibit bacteria, and the aroma of the essential oils can reduce the fishy smell of marine fish. Then, after soaking with biogenic amine inhibitors, the formation of biogenic amines is reduced, effectively controlling the production of biogenic amines and improving the biogenic amine control effect in marine fish.

[0014] Chitosan is a natural carbohydrate copolymer obtained by the deacetylation of chitin. It can be extracted from the shells of shrimp and crabs and has good biocompatibility, broad-spectrum antibacterial properties, excellent film-forming properties, antioxidant properties, and is naturally non-toxic and easily degradable. Because chitosan itself can reduce the growth of pathogenic microorganisms in food, chitosan and its derivative polymer molecules can be used as excellent materials for edible coatings and antibacterial films. Due to the narrow antibacterial spectrum of chitosan, by combining it with other natural active ingredients such as oregano oil, it can better preserve the nutrition and flavor of marine fish, prevent spoilage, and control the formation of biogenic amines.

[0015] Optionally, in step S3, the biogenic amine inhibitor further includes a tea polyphenol preservative solution with a mass concentration of 2-3 g / L.

[0016] By adopting the above technical solution, tea polyphenols have inhibitory activity against nearly a hundred kinds of bacteria in nature, showing broad-spectrum antibacterial properties. They are good food preservatives. When freezing fresh fish, adding tea polyphenol antioxidants can prevent the oxidation of fish fat.

[0017] Optionally, in step S3, the boneless fish fillets are first soaked in tea polyphenol preservation solution for 15-20 minutes, and then soaked in oregano essential oil-chitosan preservation solution for 10 minutes.

[0018] By adopting the above technical solution, boneless fish fillets are first soaked in tea polyphenol preservation solution, and then placed in oregano essential oil-chitosan preservation solution to generate an edible film. The chitosan film can form a film on the surface of the fish fillets, blocking the fish meat from contacting oxygen and slowing down the growth and reproduction of aerobic bacteria.

[0019] Optionally, in step S3, the antibacterial plant essential oil includes the following components in parts by weight: 2-4 parts oregano essential oil, 3-5 parts cinnamon essential oil, 1-3 parts clove essential oil, and 60-100 parts olive oil.

[0020] By adopting the above technical solutions, the main components of oregano essential oil are carvacrol and thymol. When applied to meat and seafood products, it exhibits good antibacterial and antioxidant activity. Cinnamon essential oil is a pale yellow oily liquid extracted from cinnamon bark, an edible spice. It has good broad-spectrum antibacterial and antioxidant effects. Its main active ingredient is cinnamaldehyde, which can be used as a natural food preservative in the food industry. Clove essential oil has antibacterial effects against five types of Gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae, Salmonella paratyphi, Citrobacter spp., and Enterobacter cloacae), one type of Gram-positive bacterium (Staphylococcus aureus), and one type of fungus (Candida albicans). Olive oil is used as a base oil for dilution and also has antibacterial properties. Different essential oils have a synergistic effect when combined. The synergistic effect of the essential oil combination can improve its antimicrobial activity in fatty seafood products, thus the antibacterial effect of the compound essential oil is better.

[0021] Optionally, in step S1, the marine fish are thawed by standing in water at 5-15°C.

[0022] By adopting the above technical solution, the raw fish suffers less damage during static thawing, thereby reducing the possibility of bacteria multiplying and forming biogenic amines from the damaged areas. Furthermore, thawing at a lower temperature ensures the fresh taste and nutrition of the fish meat. The low-temperature thawing environment slows down bacterial activity, resulting in fresher and safer thawed products.

[0023] Optionally, in step S1, when thawing the marine fish, salt is added to the water and stirred evenly, with the salt water concentration being 0.7% to 1.1%.

[0024] By adopting the above technical solution, adding salt can accelerate the thawing rate of marine fish, reduce the thawing time, and prevent damage to the nutrients in the fish meat.

[0025] Optionally, in step S2, the fish fillets are passed through an X-ray machine during inspection.

[0026] By adopting the above technical solution, the X-ray inspection machine uses low-energy X-rays to quickly detect the internal quality and foreign objects of the inspected items, and displays the images of the inspected items on a computer. The X-ray machine can ensure the inspection effect of fish fillets, ensuring that the fish fillets are free of fish bones or other impurities, and guaranteeing the processing effect of the fish fillets.

[0027] Optionally, in step S2, an environmentally friendly disinfectant is used for disinfecting the X-ray machine.

[0028] By adopting the above technical solution and using environmentally friendly disinfectants that can decompose in the natural environment to disinfect equipment regularly, the impact on the environment can be reduced.

[0029] Optionally, the environmentally friendly disinfectant is selected as a polyhexamethylene guanidine disinfectant.

[0030] By adopting the above technical solution, the guanidine group in polyhexamethylene guanidine salt has extremely strong positive charge. Since various bacteria and viruses are negatively charged, polyhexamethylene guanidine salt can easily adsorb bacteria and viruses and destroy the lipid layer, thereby preventing bacteria and viruses from dividing and multiplying and losing their activity. Even if bacteria and viruses mutate, it will not affect the inactivation effect. Moreover, microorganisms do not develop drug resistance to polyhexamethylene guanidine salt. It has a broad bactericidal spectrum and can kill a variety of bacteria and pathogenic fungi such as Staphylococcus aureus, Salmonella, Campylobacter, Escherichia coli O157, Shigella, and Candida albicans. It has excellent properties such as low effective concentration, fast action, stable properties, and easy solubility in water. It can be used at room temperature, has long-term antibacterial effect, no side effects, is non-corrosive, colorless, odorless, non-toxic, non-flammable, non-explosive, and safe to use.

[0031] In summary, this application includes at least one of the following beneficial technical effects:

[0032] 1. The process of filleting and deboning the raw fish can be completed manually or mechanically. After inspection, it is ensured that there are no fish bones, scales, or foreign objects left on the fillets. After washing, clean, boneless fish fillets are obtained, achieving preliminary sterilization. The plant essential oils and biogenic amine inhibitors are edible. The volatile compounds in the plant essential oils have multiple functions, including antibacterial, insecticidal, and antiviral effects. When dripped onto the fish fillets, they can inhibit bacteria, and the aroma of the essential oils can reduce the fishy smell of marine fish. Then, after soaking with biogenic amine inhibitors, the formation of biogenic amines is reduced, effectively controlling the production of biogenic amines and improving the biogenic amine control effect in marine fish.

[0033] 2. Chitosan is a natural carbohydrate copolymer obtained by the deacetylation of chitin. It can be extracted from the shells of shrimp and crabs and has good biocompatibility, broad-spectrum antibacterial properties, excellent film-forming properties, antioxidant properties, and is naturally non-toxic and easily degradable. Because chitosan itself can reduce the growth of pathogenic microorganisms in food, chitosan and its derivative polymer molecules can be used as excellent materials for edible coatings and antibacterial films. Due to the narrow antibacterial spectrum of chitosan, by combining it with other natural active ingredients such as oregano oil, it can better preserve the nutrition and flavor of marine fish, prevent spoilage, and control the formation of biogenic amines.

[0034] 3. The main components of oregano essential oil are carvacrol and thymol, which exhibit good antibacterial and antioxidant activity when applied to meat and seafood products. Cinnamon essential oil is a pale yellow oily liquid extracted from cinnamon bark, an edible spice. It has good broad-spectrum antibacterial and antioxidant effects. Its main active ingredient is cinnamaldehyde, which can be used as a natural food preservative in the food industry. Clove essential oil has antibacterial effects against five types of Gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae, Salmonella paratyphi, Citrobacter spp., and Enterobacter cloacae), one type of Gram-positive bacterium (Staphylococcus aureus), and one type of fungus (Candida albicans). Olive oil is used as a base oil for dilution and also has antibacterial properties. Different essential oils have synergistic effects when combined. The synergistic effect of essential oil combinations can enhance their antimicrobial activity in fatty seafood products, thus the antibacterial effect of compound essential oils is better. Detailed Implementation

[0035] The following detailed description, in conjunction with specific embodiments, illustrates a method for controlling biogenic amines used in the processing of marine fish. It should be noted that, unless otherwise specified, all procedures in the following embodiments were carried out under conventional conditions or conditions recommended by the manufacturer; and all raw materials used in the following embodiments, unless otherwise specified, are commercially available.

[0036] Examples of preparation of antibacterial plant essential oils 1-4

[0037] Preparation Example 1

[0038] Place 90g of olive oil in a beaker, add 3g of oregano oil, 5g of cinnamon oil and 2g of clove oil and mix well.

[0039] Preparation Example 2

[0040] Place 90g of olive oil in a beaker, then add 10g of oregano essential oil and mix well.

[0041] Preparation Example 3

[0042] Place 90g of olive oil in a beaker, add 10g of cinnamon essential oil and mix well.

[0043] Preparation Example 4

[0044] Place 90g of olive oil in a beaker, add 10g of clove essential oil and mix well.

[0045] Examples of preparation of oregano essential oil-chitosan preservative solution 5-6

[0046] Preparation Example 5

[0047] Weigh 15g of chitosan and 2mL of oregano essential oil into a beaker, add 5mL of 2.0% glacial acetic acid, and then dilute to 1000mL with sterile distilled water. Refrigerate the flask.

[0048] Preparation Example 6

[0049] Weigh 5g of chitosan and 2mL of oregano essential oil into a beaker, add 5mL of 2.0% glacial acetic acid, and then dilute to a volumetric flask with sterile distilled water to a volumetric flask of 1000mL. Refrigerate the flask.

[0050] Example 7 of tea polyphenol preservation solution preparation

[0051] Weigh 2g of tea polyphenols, transfer them to a 1000mL volumetric flask, dilute to volume with sterile distilled water, and refrigerate.

[0052] Example

[0053] Example 1

[0054] First, let the frozen seawater fish thaw in a 0.9% salt solution at 10℃ until it can be sliced.

[0055] The fish is cleaned in a running water washing tank below 20℃. A filleting machine is used to fillet the fish, removing the internal organs and scales. Depending on the type of fish and processing requirements, head removal or cutting into sections may be performed at this step. The fish processing method here is existing technology and will not be described in detail. After manually removing the fish bones, the fish fillets are washed again with running water. Then, the fish fillets are inspected by an X-ray foreign body detector. If fish bones or other foreign objects are detected, they are removed and the fish is washed again to obtain boneless fish fillets. The X-ray foreign body detector needs to be disinfected daily with polyhexamethylene monoguanidine disinfectant.

[0056] A drop of the antibacterial plant essential oil obtained in Preparation Example 1 was dropped onto the surface of the fish fillet. Then the fish fillet was treated with a biogenic amine inhibitor, that is, the fish fillet was immersed in the tea polyphenol preservation solution obtained in Preparation Example 7 for 20 minutes, and then the fish fillet was immersed in the oregano essential oil-chitosan preservation solution obtained in Preparation Example 5 for 10 minutes.

[0057] After the fish fillets are dried, they are vacuum-packed and stored in a cold storage at -18℃ after passing inspection. It should be noted that the operating environment in the above process is below 20℃.

[0058] Example 2

[0059] The difference between this embodiment and Example 1 is that the antibacterial plant essential oil obtained in Preparation Example 2 is used, while the rest are consistent with Example 1.

[0060] Example 3

[0061] The difference between this embodiment and Example 1 is that the antibacterial plant essential oil obtained in Preparation Example 3 is used, while the rest is consistent with Example 1.

[0062] Example 4

[0063] The difference between this embodiment and Example 1 is that the antibacterial plant essential oil obtained in Preparation Example 4 is used, while the rest are consistent with Example 1.

[0064] Example 5

[0065] The difference between this embodiment and Example 1 is that a drop of the antibacterial plant essential oil obtained in Preparation Example 1 is dropped onto the surface of the fish fillet, and then the fish fillet is immersed in the tea polyphenol preservation solution obtained in Preparation Example 7 for 20 minutes, and then the fish fillet is immersed in the oregano essential oil-chitosan preservation solution obtained in Preparation Example 6 for 10 minutes. The rest is the same as in Example 1.

[0066] Example 6

[0067] The difference between this embodiment and Example 1 is that a drop of the antibacterial plant essential oil obtained in Preparation Example 1 is dropped onto the surface of the fish fillet, and then the fish fillet is immersed in the tea polyphenol preservation solution obtained in Preparation Example 7 for 10 minutes, and then the fish fillet is immersed in the oregano essential oil-chitosan preservation solution obtained in Preparation Example 5 for 10 minutes. The rest is the same as in Example 1.

[0068] Example 7

[0069] The difference between this embodiment and Example 1 is that a drop of the antibacterial plant essential oil obtained in Preparation Example 1 is dropped onto the surface of the fish fillet, and then the fish fillet is directly immersed in the oregano essential oil-chitosan preservation solution obtained in Preparation Example 5 for 10 minutes. The rest is the same as in Example 1.

[0070] Example 8

[0071] The difference between this embodiment and Embodiment 1 is that the frozen marine fish are thawed by standing in a 0.9% saline solution at 35°C; otherwise, they are the same as in Embodiment 1.

[0072] Example 9

[0073] The difference between this embodiment and Embodiment 1 is that the frozen marine fish are thawed by standing in pure water at 10°C; otherwise, they are the same as in Embodiment 1.

[0074] Example 10

[0075] The difference between this embodiment and Embodiment 1 is that the disinfectant is decyl dimethyl ammonium chloride, while the rest is the same as in Embodiment 1.

[0076] Comparative Example

[0077] Comparative Example 1

[0078] The difference between this embodiment and Embodiment 1 is that antibacterial plant essential oils are not used to treat the fish fillets; otherwise, they are consistent with Embodiment 1.

[0079] Comparative Example 2

[0080] The difference between this embodiment and Embodiment 1 is that the fish fillets are not treated with biogenic amine inhibitors; otherwise, they are consistent with Embodiment 1.

[0081] Comparative Example 3

[0082] The difference between this embodiment and Embodiment 1 is that the fish fillets are not treated with antibacterial plant essential oils and biogenic amine inhibitors; otherwise, they are consistent with Embodiment 1.

[0083] Comparative Example 4

[0084] The difference between this embodiment and Embodiment 1 is that the biogenic amine inhibitor is cinnamon essential oil-chitosan preservative solution, while the rest are consistent with Embodiment 1.

[0085] Performance testing

[0086] Biogenic amine content test

[0087] Fish fillets obtained after processing using the above examples and comparative examples and stored in cold storage for different times were thawed in 15°C cold water, and their biogenic amine content was tested. The biogenic amine content test was conducted according to GB5009.208-2016 "National Food Safety Standard - Determination of Biogenic Amines in Food". The main biogenic amine in marine fish is histamine. After measurement, the histamine content in the sample was calculated. Five groups of samples were tested under the same conditions, and the average value was taken. The test results are as follows:

[0088] Table 1: Test results of histamine content (mg / kg) in marine fish at different storage times

[0089] 0 12h 24h 7 days 30 days Example 1 10.37 13.58 21.28 40.12 77.23 Example 2 15.23 18.34 26.28 57.05 86.54 Example 3 13.59 16.65 23.86 46.34 81.40 Example 4 16.81 19.71 27.33 48.66 93.76 Example 5 19.14 20.29 29.91 66.85 105.59 Example 6 12.25 14.86 22.83 43.90 79.09 Example 7 18.43 19.88 28.47 62.44 94.04 Example 8 17.88 19.21 27.18 59.97 89.14 Example 9 16.32 17.37 29.42 52.32 88.67 Example 10 15.63 16.76 18.31 56.09 83.98 Comparative Example 1 40.58 51.05 60.57 105.23 169.20 Comparative Example 2 68.31 74.37 89.06 149.41 264.55 Comparative Example 3 94.17 106.72 174.86 205.77 372.84 Comparative Example 4 25.62 39.85 52.27 97.65 143.90

[0090] Sensory flavor testing was conducted on fish fillets before they were packaged and stored in cold storage. Sensory evaluations were performed after 1 hour, 3 hours, and 12 hours, observing their morphology and assessing their aroma. The evaluation results are as follows:

[0091] Table 2: Sensory Evaluation Results of Marine Fish

[0092]

[0093]

[0094] As can be seen from Tables 1 and 2, the raw fish in Examples 1-10 had no pungent odor after 12 hours and had not spoiled. The histamine content of the processed fish fillets remained low even after 30 days of storage, meeting national standards, and biogenic amines were effectively controlled.

[0095] Compared with Example 1, the essential oil in Example 1 is a compound essential oil of three plant essential oils. The three essential oils can play a synergistic role, achieving better antibacterial effect and better control of biogenic amines.

[0096] Compared with Example 1, Example 5 has a different amount of chitosan added. As shown in Table 1, when the mass concentration of chitosan in Example 1 is 15 g / L, the control effect of biogenic amines is better.

[0097] Compared with Example 1, Example 6 showed that the fish fillets were soaked in the tea polyphenol preservative solution for a shorter time, while Example 7 did not soak in the tea polyphenol preservative solution. As can be seen from the data in Table 1, Example 1 had a better biogenic amine control effect. Adding tea polyphenol preservative solution and maintaining it in it for a sufficient time can improve the biogenic amine control effect.

[0098] Compared with Example 1, Example 8 uses a different thawing temperature for the raw fish. As shown in Table 1, thawing at a lower temperature can achieve better control of biogenic amines.

[0099] Compared with Example 1, in Example 9, whether salt was added during the thawing of the raw fish, as shown in Table 1, the control of biogenic amines was better after adding a small amount of salt to thaw the fish. Salt itself has a certain bactericidal function and can accelerate the thawing rate and reduce the bacterial growth on the fish during thawing.

[0100] Compared with Example 1, Example 10 uses a different disinfectant for the X-ray machine. As shown in Table 1, the polyhexamethylene guanidine disinfectant is more sensitive to histamine-producing bacteria in marine fish and has a better disinfection effect.

[0101] Compared with Comparative Example 1 and Comparative Example 2, one did not use antibacterial plant essential oil, and the other did not use biogenic amine inhibitor. Compared with Comparative Example 3, neither antibacterial plant essential oil nor biogenic amine inhibitor was added. As can be seen from the data in Tables 1 and 2, its biogenic amine content is much higher than that of Example 1, and the difference will be greater over time.

[0102] Compared with Example 1, Comparative Example 4 used cinnamon oil-chitosan instead of oregano oil-chitosan to produce an edible film. As shown in Table 1, its biogenic amine control effect was not as good as that of oregano oil-chitosan.

[0103] In summary, the method used in Example 1 has the best effect on controlling biogenic amines.

[0104] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for controlling the processing of biogenic amines in marine fish, characterized by: The method comprises the following steps: S1, thawing raw fish: placing frozen seawater fish to thaw; S2, pretreatment: washing the thawed seawater fish with running water, then cutting and removing the spine, washing again with running water, checking the fish body, removing foreign matters, and washing to obtain spineless fish fillets; S3, controlling biological amine: first, dropping bacteriostatic plant essential oil on the surface of the spineless fish fillets, then immersing the spineless fish fillets in a biological amine inhibitor for 10-30 min, the biological amine inhibitor being oregano essential oil-chitosan preservative solution, the bacteriostatic plant essential oil comprising the following components in parts by weight: oregano essential oil 2-4 parts, cinnamon essential oil 3-5 parts, clove essential oil 1-3 parts, and olive oil 60-100 parts; S4, post-treatment: drying the immersed fish fillets, packaging, and storing in a refrigerator.

2. The method of claim 1, wherein the method is characterized by: In the step S3, the volume fraction of oregano essential oil in the oregano essential oil-chitosan preservative solution is 0.1%-0.3%, and the mass concentration of chitosan is 10-20 g / L.

3. The method of claim 2, wherein the method is characterized by: In the step S3, the biological amine inhibitor further comprises tea polyphenol preservative solution with a mass concentration of 2-3 g / L.

4. The method according to claim 3, wherein: In the step S3, the spineless fish fillets are first immersed in the tea polyphenol preservative solution for 15-20 min, and then immersed in the oregano essential oil-chitosan preservative solution for 10 min.

5. The method of claim 1, wherein the method is characterized by: In the step S1, the seawater fish is placed to thaw in water at 5-15 ℃.

6. The method of claim 5, wherein the method is characterized by: In the step S1, when the seawater fish is thawed, salt is added to the water and stirred uniformly, and the concentration of the salt water is 0.7%-1.1%.

7. The method of claim 1, wherein the method is characterized by: In the step S2, the fish fillets are passed through an X-ray machine when being checked.

8. The method according to claim 7, wherein: In the step S2, the X-ray machine is disinfected with an environmentally friendly disinfectant.

9. The method according to claim 8, wherein: The environmentally friendly disinfectant is selected as a polyhexamethylene guanidine disinfectant.

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