A method for preventing deterioration of irradiation fresh-keeping of chilled fresh meat

Abstract

The present application belongs to the field of food preservation technology, and relates to a preservation treatment method for preventing deterioration of cold fresh meat after irradiation preservation. The preservation treatment of the cold fresh meat is completed by pre-sterilization of the meat by spraying, soaking of the meat in active nano-preservation liquid, nitrogen filling and packaging, irradiation sterilization and storage in a low-temperature environment. According to the principle of irradiation chemistry, the generation of irradiation odor is related to the generation of oxygen free radicals and peroxides in irradiated food. The addition of the additive liquid into the cold fresh product makes the oxygen free radicals and peroxides generated in the irradiation process react with the components in the additive liquid, reduces the generation of irradiation odor, and prolongs the shelf life by combining pre-sterilization treatment, soaking in preservation liquid and irradiation sterilization.

Description

Technical Field

[0001] This invention belongs to the field of food preservation technology, and more specifically relates to a preservation treatment method for preventing the deterioration of chilled meat due to irradiation. Background Technology

[0002] Chilled fresh meat refers to fresh meat from poultry or livestock that has been rapidly cooled to a carcass temperature of 0-4°C during slaughter, strictly adhering to veterinary inspection and quarantine regulations, and maintained within this temperature range throughout the entire food supply chain. Chilled fresh meat boasts advantages such as tenderness, juiciness, delicious flavor, rich nutrition, and safety, and is gradually replacing hot fresh meat and frozen meat as the mainstream of meat consumption. With economic development, improved living standards, and increased food safety awareness, consumers are paying increasing attention to the quality and safety of meat products. Chilled fresh meat has a high nutrient content, making it highly susceptible to microbial growth and spoilage. Contaminated chilled fresh meat and its products seriously endanger human health and are a major cause of foodborne illnesses and food poisoning. Currently, due to the high initial bacterial count, the 0°C-4°C refrigeration temperature used for chilled fresh meat is insufficient to inhibit microbial growth and other related changes, resulting in a short shelf life that fails to meet market circulation requirements. Protein oxidation during refrigeration alters protein structure, leading to a deterioration in the sensory quality and a decrease in nutritional value of meat products.

[0003] Irradiation technology, as a recognized cold sterilization technique, has advantages such as no temperature rise, no residue, no damage to original packaging, energy saving, high efficiency, and convenience. While irradiation offers certain advantages over other preservation methods—killing most microorganisms in chilled meat after gamma irradiation, effectively extending its shelf life—irradiated meat develops an off-odor and changes its color. Gamma irradiation oxidizes proteins and lipids in the meat, potentially damaging protein structure and causing reactions such as amino oxidation, deamination, decarboxylation, and cross-linking degradation. This leads to protein degradation and ultimately the formation of volatile substances like sulfides, resulting in the off-odor. For a long time, the off-odor from irradiation has been a major obstacle to the promotion of irradiated cooked meats and a primary reason why consumers find it unacceptable. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a preservation treatment method for preventing the deterioration of chilled fresh meat during irradiation. This preservation treatment method effectively solves the problems of irradiation-induced protein oxidation, the generation of irradiated flavor, and color changes. It is simple and effective to operate, meets the preservation requirements of chilled fresh meat, improves meat quality, and extends its shelf life.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] One of the technical solutions of the present invention is to provide an active nano-preservative liquid, comprising 0.3-0.9 mg / mL of active ingredients, 2.5-5.0 mg / mL of protein, 1-2.5 mg / mL of dietary fiber, and 2.5-4 mg / mL of galacturonic acid.

[0007] Furthermore, the active ingredient includes at least one of tea polyphenols, curcumin, and luteolin.

[0008] Furthermore, the protein component is at least one of soybean peptide hydrophobic aggregates, walnut protein, and soybean protein, preferably soybean peptide hydrophobic aggregates.

[0009] Preferably, the preparation steps of the soybean peptide hydrophobic aggregates include: adding soybean protein isolate to deionized water to prepare a 4% (w / v) protein solution, adding 0.5% (v / v) Alcalase for enzymatic hydrolysis, the enzymatic hydrolysis conditions being pH 8.5, 50℃, and the enzymatic hydrolysis time being 1 hour, followed by boiling water to inactivate the enzyme for 15 minutes, then rapidly cooling to room temperature and adjusting the pH to 7, centrifuging (10000g, 25℃) for 20 minutes, and the precipitate being the soybean peptide hydrophobic aggregates.

[0010] Furthermore, the dietary fiber component is water-soluble dietary fiber from navel orange peel, with a particle size of 200-400 mesh.

[0011] Preferably, the preparation steps of the navel orange peel water-soluble dietary fiber include: adding navel orange peel ultrafine powder (200-400 mesh) to deionized water to prepare a 5% (w / v) dispersion, stirring in a 60°C water bath for 4 hours, cooling to room temperature, filtering, concentrating the filtrate to 1 / 5, precipitating with 4 times the volume of 95% ethanol, and collecting the precipitate as navel orange peel water-soluble dietary fiber.

[0012] When the active ingredient is tea polyphenols or curcumin, the concentration of the active ingredient in the active nano-preservative solution is preferably 0.3 to 0.9 mg / mL; when the active ingredient is luteolin, the concentration of the active ingredient in the active nano-preservative solution is preferably 0.5 to 0.75 mg / mL.

[0013] The curcumin and luteolin used in this invention possess strong antioxidant activity, but their poor water solubility and sensitivity to light and temperature affect their stability, leading to poor bioavailability. The pectin (galacturonic acid) used in this invention exhibits gastrointestinal digestibility and can improve the targeting and sustainable release of the loaded active substances. Therefore, pectin effectively carries active ingredients, thereby improving their solubility and stability, and ultimately enhancing their bioavailability.

[0014] The second technical solution of the present invention provides a method for preparing the above-mentioned active nano-preservative liquid, comprising:

[0015] The protein components were prepared into a dispersion, the pH was adjusted to 10-12, and then ultrasonic and microwave treated for 10-20 minutes. The active substances and dietary fiber were then added to the dispersion and magnetically stirred at room temperature for 20-30 minutes to obtain a mixture.

[0016] After adjusting the pH of the mixture to 5-7, galacturonic acid was added, and the mixture was stirred and centrifuged to collect the supernatant.

[0017] The liquid component obtained by dialysis of the supernatant is the active nano-preservative liquid.

[0018] Furthermore, the average particle size of the active nano-preservative liquid is 200–500 nm.

[0019] Furthermore, in the ultrasonic and microwave processing, the ultrasound and microwave are performed synchronously, with the ultrasound power being 300-500W and the microwave power being 150-250W.

[0020] Furthermore, the stirring time after adding galacturonic acid is 5 to 10 minutes.

[0021] Furthermore, the centrifugation speed is 5000-8000 r / min, and the time is 10-20 min.

[0022] Furthermore, the dialysis is performed for 24 hours using a dialysis bag with a specification of 3500 Da.

[0023] Here, dialysis not only removes the salts produced when adjusting the pH value, but also improves the stability of the preservation solution.

[0024] The third technical solution of the present invention provides an application of the above-mentioned active nano-preservative liquid in preventing the deterioration of chilled meat by irradiation.

[0025] Fourth technical solution of the present invention: A method for preventing the deterioration of chilled fresh meat due to irradiation, comprising:

[0026] The process of preserving chilled meat involves rinsing and pre-sterilizing the meat, soaking it in the aforementioned active nano-preservative solution, packaging it with nitrogen, sterilizing it with irradiation, and storing it in a low-temperature environment.

[0027] Furthermore, the meat products include one of chicken, pork, beef, and lamb.

[0028] Furthermore, the method of pre-sterilization by rinsing includes rinsing the meat with an organic acid solution for 30-60 seconds to complete the pre-sterilization by rinsing.

[0029] Preferably, the concentration of the organic acid solution is 0.05–0.25 wt.%.

[0030] Preferably, the organic acid includes citric acid and tartaric acid in a mass ratio of 1-2:1-3, more preferably 1:1.

[0031] Furthermore, the soaking time is 60–120 seconds.

[0032] Furthermore, the amount of nitrogen in the nitrogen-filled packaging is 20-35% of the packaging volume.

[0033] Furthermore, the irradiation sterilization includes irradiating the chilled fresh meat in the irradiation source field with 60Co-γ rays, with an irradiation dose of 2-6 kGy and an irradiation ambient temperature of 2-6°C. Preferably, the irradiation dose is 4 kGy and the irradiation ambient temperature is 4°C.

[0034] As can be seen from the above technical solution, compared with the existing technology, it has the following beneficial effects:

[0035] This invention utilizes the nano-encapsulation properties and acid-base interactions of protein components, dietary fiber, and pectin (galacturonic acid) to promote the binding of protein pectin with active substances, thereby greatly improving the water solubility, stability, and inhibitory effect on the deterioration of irradiated meat.

[0036] Based on the principles of radiation chemistry, this invention addresses the generation of irradiation odor, which is related to the production of oxygen free radicals and peroxides in irradiated foods. By adding an active nano-preservative liquid to chilled products to reduce irradiation odor, the oxygen free radicals and peroxides generated during irradiation react with the components in the active nano-preservative liquid, reducing the oxidation of protein and fat in meat caused by irradiation, thus reducing the generation of irradiation odor and extending shelf life.

[0037] After using this invention to irradiate chilled meat, there is no obvious irradiation smell, and the growth of spoilage bacteria in chilled meat can be effectively inhibited. The three-stage combined use of pre-sterilization, nano-composite preservation liquid and irradiation sterilization can reduce juice loss, reduce color changes, and inhibit irradiation-induced protein and fat oxidation, thus extending shelf life and maintaining product quality. Attached Figure Description

[0038] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0039] Figure 1 This is a particle size distribution diagram of the active nano-preservative liquid A prepared in Example 1.

[0040] Figure 2 This is a particle size distribution diagram of the active nano-preservative liquid B prepared in Example 2.

[0041] Figure 3 This is a particle size distribution diagram of the active nano-preservative liquid C prepared in Example 3.

[0042] Figure 4 The hydroxyl radical scavenging ability (a) and total antioxidant capacity (b) of dietary fiber in the active nano-preservative liquids prepared in Examples 1-3 are shown. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] In this embodiment of the invention, the protein components are selected from soybean peptide hydrophobic aggregates, walnut protein, and soybean protein, and the dietary fiber is water-soluble dietary fiber from navel orange peel. Based on the principle that the protein components and polysaccharides have nano-encapsulation properties and that acid-base combination promotes the binding of protein pectin and active substances, this invention selects at least one or more combinations of soybean peptide hydrophobic aggregates, walnut protein, and soybean protein. The final technical effects are not significantly different, so they can be substituted in the same amount.

[0045] Preparation of hydrophobic aggregates of soybean peptides: Soy protein isolate was added to deionized water to prepare a 4% (w / v) protein solution. 0.5% (v / v) Alcalase was added for enzymatic hydrolysis. The hydrolysis conditions were pH 8.5, 50℃, and hydrolysis time of 1 h. After boiling water to inactivate the enzyme for 15 min, the solution was quickly cooled to room temperature and the pH was adjusted to 7. The solution was then centrifuged (10000g, 25℃) for 20 min. The precipitate was the hydrophobic aggregates of soybean peptides.

[0046] Preparation of water-soluble dietary fiber from navel orange peel: Navel orange peel ultrafine powder (200-400 mesh) was added to deionized water to prepare a 5% (w / v) dispersion. The dispersion was stirred in a water bath at 60℃ for 4 hours, cooled to room temperature, filtered, and the filtrate was concentrated to 1 / 5. The filtrate was precipitated overnight with 4 times the volume of 95% ethanol, centrifuged, and the precipitate was collected to obtain water-soluble dietary fiber from navel orange peel.

[0047] Walnut protein and soy protein are commercially available products.

[0048] In the examples and comparative examples, the ultrasonic power was 400W and the microwave power was 200W.

[0049] Example 1

[0050] Preparation of active nano-preservative liquid:

[0051] Soybean peptide hydrophobic aggregates were added to a certain amount of deionized water and stirred at room temperature for 1 hour to prepare a dispersion. The pH value was adjusted to 10-12 and then treated with ultrasound and microwave simultaneously for 15 minutes. Luteolin and dietary fiber were added to the dispersion and magnetically stirred at room temperature for 20-30 minutes to obtain a mixture.

[0052] After adjusting the pH of the mixture to 7, add galacturonic acid and stir for 5-10 minutes. Then, centrifuge at 6000 r / min for 20 minutes and collect the supernatant.

[0053] The supernatant was dialyzed for 24 hours using a dialysis bag with a specification of 3500 Da to obtain the active nano-preservative liquid, which is denoted as active nano-preservative liquid A.

[0054] Among them, the concentration of soybean peptide hydrophobic aggregates in the active nano-preservative liquid was 4 mg / mL, the concentration of citrus dietary fiber was 1.8 mg / mL, the concentration of galacturonic acid was 2.5 mg / mL, and the concentration of luteolin was 0.6 mg / mL.

[0055] Example 2

[0056] Preparation of active nano-preservative liquid:

[0057] Soybean peptide hydrophobic aggregates were added to a certain amount of deionized water and stirred at room temperature for 1 hour to prepare a dispersion. The pH value was adjusted to 10-12 and then ultrasonically and microwaved for 15 minutes. Tea polyphenols and dietary fiber were added to the dispersion and magnetically stirred at room temperature for 20-30 minutes to obtain a mixture.

[0058] After adjusting the pH of the mixture to 7, add galacturonic acid and stir for 5-10 minutes. Then, centrifuge at 6000 r / min for 20 minutes and collect the supernatant.

[0059] The supernatant was dialyzed for 24 hours using a dialysis bag with a specification of 3500 Da to obtain the active nano-preservative liquid, which is denoted as active nano-preservative liquid B.

[0060] The active nano-preservative liquid contained soybean peptide hydrophobic aggregates at a concentration of 4 mg / mL, citrus dietary fiber at a concentration of 1.8 mg / mL, galacturonic acid at a concentration of 2.5 mg / mL, and tea polyphenols at a concentration of 0.9 mg / mL.

[0061] Example 3

[0062] Preparation of active nano-preservative liquid:

[0063] Soybean peptide hydrophobic aggregates were added to a certain amount of deionized water and stirred at room temperature for 1 hour to prepare a dispersion. The pH value was adjusted to 10-12 and then ultrasonically and microwaved for 15 minutes. Curcumin and dietary fiber were added to the dispersion and magnetically stirred at room temperature for 30 minutes to obtain a mixture.

[0064] After adjusting the pH of the mixture to 7, add galacturonic acid and stir for 5-10 minutes. Then, centrifuge at 6000 r / min for 20 minutes and collect the supernatant.

[0065] The supernatant was dialyzed for 24 hours using a dialysis bag with a specification of 3500 Da to obtain the active nano-preservative liquid, which is denoted as active nano-preservative liquid C.

[0066] The active nano-preservative liquid contained soybean peptide hydrophobic aggregates at a concentration of 4 mg / mL, citrus dietary fiber at a concentration of 1.8 mg / mL, galacturonic acid at a concentration of 2.5 mg / mL, and curcumin at a concentration of 0.7 mg / mL.

[0067] Example 4

[0068] Steps for preserving chicken breast:

[0069] Chicken breast was soaked in a 0.05 wt.% organic acid solution (citric acid: tartaric acid mass ratio of 1:1) for 60 seconds to obtain pre-sterilized chilled meat.

[0070] Soak the pre-sterilized chilled meat in active nano-preservative liquid A for 100 seconds, hang it up to drain, divide the drained chilled chicken breast into freezer bags, fill the freezer bags with nitrogen to a total volume of 30%, and then immediately seal the bags to preserve freshness.

[0071] The packaged chilled chicken breast was placed in a packaging box and placed in an irradiation source field. The chilled chicken breast in the irradiation source field was irradiated with 60Co-γ rays at a dose of 2kGy and an irradiation environment temperature of 4℃.

[0072] After irradiation, the chilled chicken breast is stored at a temperature of 4°C and a humidity of 65%.

[0073] Example 5

[0074] Steps for preserving chicken breast:

[0075] The only difference from Example 4 is that the irradiation dose is 4 kGy, otherwise it is the same as Example 4.

[0076] Example 6

[0077] Steps for preserving chicken breast:

[0078] The only difference from Example 4 is that the irradiation dose is 6 kGy, otherwise it is the same as Example 4.

[0079] Example 7

[0080] Steps for preserving chicken breast:

[0081] Chicken breast was soaked in a 0.1 wt.% organic acid solution (citric acid: tartaric acid mass ratio of 1:1) for 60 seconds to obtain pre-sterilized chilled meat.

[0082] Soak the pre-sterilized chilled meat in active nano-preservative liquid B for 120 seconds, hang it up to drain, divide the drained chilled chicken breast into freezer bags, fill the freezer bags with nitrogen to a total volume of 30%, and then immediately seal the bags to preserve freshness.

[0083] The packaged chilled chicken breast was placed in a packaging box and placed in an irradiation source field. The chilled chicken breast in the irradiation source field was irradiated with 60Co-γ rays at a dose of 2kGy and an irradiation environment temperature of 4℃.

[0084] After irradiation, the chilled chicken breast is stored at a temperature of 4°C and a humidity of 65%.

[0085] Example 8

[0086] Steps for preserving chicken breast:

[0087] The only difference from Example 7 is that the irradiation dose is 4 kGy, otherwise it is the same as Example 7.

[0088] Example 9

[0089] Steps for preserving chicken breast:

[0090] The only difference from Example 7 is that the irradiation dose is 6 kGy; otherwise, they are the same.

[0091] Example 10

[0092] Steps for preserving chicken breast:

[0093] Chicken breast was soaked in a 0.1 wt.% organic acid solution (citric acid: tartaric acid mass ratio of 1:1) for 45 seconds to obtain pre-sterilized chilled meat.

[0094] Soak the pre-sterilized chilled meat in active nano-preservative liquid C for 100 seconds, hang it up to drain, divide the drained chilled chicken breast into freezer bags, fill the freezer bags with nitrogen to a total volume of 20%, and then immediately seal the bags to preserve freshness.

[0095] The packaged chilled chicken breast was placed in a packaging box and placed in an irradiation source field. The chilled chicken breast in the irradiation source field was irradiated with 60Co-γ rays at a dose of 2kGy and an irradiation environment temperature of 4℃.

[0096] After irradiation, the chilled chicken breast is stored at a temperature of 4°C and a humidity of 65%.

[0097] Example 11

[0098] Steps for preserving chicken breast:

[0099] The only difference from Example 10 is that the irradiation dose is 4 kGy, otherwise it is the same as Example 10.

[0100] Example 12

[0101] Steps for preserving chicken breast:

[0102] The only difference from Example 10 is that the irradiation dose is 6 kGy, otherwise it is the same as Example 10.

[0103] Comparative Example 1

[0104] Compared to Example 4, the difference lies in that the chicken breast was not soaked and irradiated using active nano-preservative solution A. The preservation process for the chicken breast is as follows:

[0105] Chicken breast was soaked in a 0.05 wt.% organic acid solution (citric acid: tartaric acid mass ratio of 1:1) for 60 seconds to obtain pre-sterilized chilled meat.

[0106] Pack the pre-sterilized chilled meat into freezer bags, fill the freezer bags with nitrogen to 30% of their volume, and then immediately seal the bags to preserve freshness.

[0107] Place the packaged chilled chicken breast into a box and store it at a temperature of 4°C and a humidity of 65%.

[0108] Comparative Example 2

[0109] The steps for preserving chicken breast are as follows:

[0110] The only difference from Example 4 is that the active nano-preservative solution A was not used for soaking treatment; otherwise, it is the same as Example 4.

[0111] Comparative Example 3

[0112] The steps for preserving chicken breast are as follows:

[0113] The only difference from Example 5 is that the active nano-preservative solution A was not used for soaking treatment; otherwise, it is the same as Example 5.

[0114] Comparative Example 4

[0115] The steps for preserving chicken breast are as follows:

[0116] The only difference from Example 6 is that the active nano-preservative solution A was not used for soaking treatment; otherwise, it is the same as Example 6.

[0117] Comparative Example 5

[0118] The steps for preserving chicken breast are as follows:

[0119] The only difference from Example 4 is that it was not irradiated; otherwise, it was the same as Example 4.

[0120] Comparative Example 6

[0121] The steps for preserving chicken breast are as follows:

[0122] The only difference from Example 7 is that it was not irradiated; otherwise, it was the same as Example 7.

[0123] Comparative Example 7

[0124] The steps for preserving chicken breast are as follows:

[0125] The only difference from Example 10 is that it was not irradiated; otherwise, it was the same as Example 10.

[0126] Comparative Example 8

[0127] The only difference from Example 1 is that no protein component was added when preparing the active nano-preservative liquid.

[0128] Comparative Example 9

[0129] The only difference from Example 1 is that luteolin was not added when preparing the active nano-preservative liquid.

[0130] Comparative Example 10

[0131] The only difference from Example 1 is that galacturonic acid was not added when preparing the active nano-preservative liquid.

[0132] Comparative Example 11

[0133] The only difference from Example 4 is that the active nano-preservative liquid prepared in Comparative Example 8 is used instead of nano-active preservative liquid A.

[0134] Comparative Example 12

[0135] The only difference from Example 4 is that the active nano-preservative liquid prepared in Comparative Example 9 is used instead of nano-active preservative liquid A.

[0136] Comparative Example 13

[0137] The only difference from Example 4 is that the active nano-preservative liquid prepared in Comparative Example 10 replaces nano-active preservative liquid A.

[0138] Test case

[0139] 1. Total bacterial count

[0140] For the chilled fresh meat obtained in Examples 4-12, Comparative Examples 1-7, and Comparative Examples 11-13, the total bacterial count was determined at 0d, 3d, 6d, 9d, 15d, and 18d, and the results are shown in Table 1.

[0141] The detection method is as follows: Refer to the national standard (GB 4789.2-2016 National Food Safety Standard, Microbiological Examination of Food, Determination of Total Colony Count). Take 10g of meat into a conical flask, add 90mL of water, and shake in a shaker for 15min to obtain a 10-fold dilution. After serial dilution, pipette 1mL of each dilution into petri dishes, repeating each dilution three times. Pour in 15-20mL of culture medium, allow to solidify, and then incubate at 25℃ for 48h. Count the total colony count.

[0142] Table 1 Total bacterial count

[0143]

[0144]

[0145] Note: The total bacterial count in chilled fresh chicken breast should not exceed 1×10⁻⁶ according to national standards for chilled meat. 6 If the total bacterial count exceeds CFU / g, it can be considered that the chilled chicken breast has spoiled. Therefore, when the total bacterial count is higher than the national standard, it will no longer be tested.

[0146] It should be noted that the total number of colonies at day 0 varies due to differences between individual samples and different treatment methods.

[0147] The data from Example 4 and Comparative Example 1 show that Comparative Example 1, which was not soaked in or irradiated with active nano-preservative liquid A, already exceeded the national standard on the 6th day. On the 3rd day, the total number of colonies in Comparative Example 1 was 35.71 times that of Example 4.

[0148] The data from Example 4 and Comparative Example 2 show that Comparative Example 2, which was irradiated, exceeded the national standard on the 9th day. The total number of colonies in Comparative Example 2 on the 9th day was 3.55 times that of Example 4.

[0149] A comparison of the data from Comparative Example 3 and Example 5 shows that the total number of colonies in Comparative Example 3 when it deteriorated was 6 times that of Example 5.

[0150] When Comparative Example 4 and Example 6 were kept fresh for 15 days, the total bacterial count of Comparative Example 4 was 1.86 times that of Example 6.

[0151] Compared with Example 4, the total bacterial count of Comparative Example 5 was 3.06 times that of Example 4 on the 9th day of preservation.

[0152] Compared with Example 7, the total bacterial count of Comparative Example 6 was 6.04 times that of Example 7 on the 9th day of preservation.

[0153] Compared with Example 10, the total bacterial count of Comparative Example 7 was 3.86 times that of Example 10 on the 9th day of preservation.

[0154] As can be seen from the above comparison, the preservation method of the present invention can effectively extend the shelf life of chilled chicken breast.

[0155] 2. Volatile basic nitrogen (TVB-N)

[0156] For the chilled fresh meat obtained in Examples 4-12, Comparative Examples 1-7 and Comparative Examples 11-13, the volatile basic nitrogen (TVB-N) was measured at 0d, 3d, 6d, 9d, 15d and 18d, and the results are shown in Table 2.

[0157] The detection method is as follows: The determination of volatile basic nitrogen (TVB-N) is carried out in accordance with the national standard (GB 5009.228-2016 National Food Safety Standard - Determination of Volatile Basic Nitrogen in Food). The meat is chopped, and 10g of meat (accurate to 0.001g) is accurately weighed into a 250mL stoppered conical flask. 100mL of water is added, and the mixture is homogenized for 2 minutes. The mixture is then filtered through filter paper, and 10mL of the filtrate is accurately transferred into a digestion tube. 1.0g of magnesium oxide is added, and the mixture is distilled for testing.

[0158] Table 2 TVB-N

[0159]

[0160] The national standard stipulates that the volatile basic nitrogen content of chilled fresh chicken breast should be ≤15mg / 100g.

[0161] As shown in Table 2, the volatile basic nitrogen (TVB-N) content of chilled chicken breast gradually increased during storage. Comparative Example 1 exceeded the standard on the sixth day, with a TVB-N value of 15.8 mg / 100g. In Examples 4-12, the TVB-N values ​​after 18 days of storage did not exceed the national standard, indicating that the preservation method of this invention can delay the increase in TVB-N values, thereby delaying the spoilage of chilled chicken breast and extending the product's shelf life.

[0162] 3. Lipid oxidation index

[0163] For the chilled fresh meat obtained in Examples 4-12, Comparative Examples 1-7 and Comparative Examples 11-13, the fat oxidation index (TBA value) was measured at 0d, 3d, 6d, 9d, 15d and 18d, and the results are shown in Table 3.

[0164] The detection method was performed according to the spectrophotometric method, Method II, of GB 5009.181-2016. Weigh 5g of sample into a 100mL stoppered conical flask, add 30mL of trichloroacetic acid mixture, and shake well. Cover and shake in a constant temperature shaker for 30min. Cool to room temperature and filter. Transfer 3mL of this filtrate to a 25mL covered cuvette, add 3mL of trichloroacetic acid mixture as a blank, add 3mL of thiobarbituric acid aqueous solution, cover, and mix thoroughly. Incubate in a 90℃ water bath for 30min, then remove and cool to room temperature.

[0165] In a series of malondialdehyde standard solutions, standard solutions of each concentration are precisely aspirated using a pipette to prepare standard curves. TBA aqueous solution is added to the standard curves and sample solutions, the mixture is sealed and thoroughly mixed, heated in a water bath at 90°C for 30 minutes, and then cooled to room temperature for detection.

[0166] Table 3. TBA index for lipid oxidation

[0167]

[0168]

[0169] With the extension of storage period, the increasing trend of TBA significantly increased. Within the irradiation dose range of 0 kGy to 6 kGy, the higher the irradiation dose, the higher the initial content of thiobarbituric acid, and the increasing trend significantly increased with the extension of storage period. As can be seen from the data in Table 3, the initial values ​​of thiobarbituric acid in Examples 4-12 were significantly smaller than those in Comparative Examples 2-4 (irradiation only). Their overall values ​​increased with time, but the trend was relatively gradual compared to the irradiation groups. The TBA value of Comparative Example 4 (6 kGy) increased the fastest. The higher the irradiation dose, the faster and more severe the fat oxidation. However, after adding the preservative solution and then modifying the atmosphere packaging before irradiation, the rate of fat oxidation can be effectively inhibited, thereby extending the storage period.

[0170] 4. Determination of color L* and color b*

[0171] For the chilled fresh meat obtained in Examples 4-12, Comparative Examples 1-7, and Comparative Examples 11-13, the color L* and color b* were measured at 0d, 3d, 6d, 9d, 15d, and 18d.

[0172] The color L* test results are shown in Table 4.

[0173] The color b* test results are shown in Table 5.

[0174] Table 4 Color L*

[0175]

[0176]

[0177] Table 5 Color b*

[0178]

[0179]

[0180] As shown in Tables 4 and 5, the color L* of chilled chicken breast decreased significantly during storage (P<0.01). The color gradually decreased in each treatment group, and the decreasing trend was obvious. The brightness changed from bright to dark, which may be due to the increase in storage period and the change in meat quality.

[0181] Color b* (yellowness) indicates the degree of fat oxidation. As shown in the table, the b* value increases with the extension of storage period. Comparing the data of Examples 4-12 in Table 5 with those of Comparative Examples 2-4, it can be seen that the preservation methods of Examples 4-12 can slow down fat oxidation caused by irradiation and reduce yellowness. During storage, Examples 4-12 of the present invention have a certain color-preserving effect on chilled chicken breast.

[0182] 5. Changes in the content of protein oxidation indicators and changes in protein secondary structure

[0183] To investigate the changes in protein oxidation index content, surface hydrophobicity, thiol content, and carbonyl content were measured in the chilled fresh meat obtained in Examples 4-12, Comparative Examples 1-7, and Comparative Examples 11-13. The results are shown in Table 7. The detection method was as follows:

[0184] Carbonyl: The myofibrillar protein (MP) concentration was adjusted to 5 mg / mL. 1 mL of the adjusted protein solution was added to a 5 mL test tube, followed by 1 mL of 2,4-dinitrophenylhydrazine (DNPH, 10 mmol / L, dissolved in 2 mol / L solution). The mixture was reacted at room temperature for 1 hour, vortexed for 1 hour every 20 min. Then, 1 mL of trichloroacetic acid (TCA, 20%) solution was added and mixed. The mixture was centrifuged at 2000 r / min at 4 °C. The supernatant was discarded. 1 mL of a mixture of ethyl acetate and ethanol (1:1) was added to the precipitate to wash it thoroughly three times until completely decolorized. Then, 3 mL of guanidine hydrochloride solution (6 mol / L) was added and the mixture was reacted in a 37 °C water bath for 20 min to completely dissolve the precipitate. Slightly insoluble substances in the reaction solution were removed by centrifugation at 10000 r / min for 5 min. The absorbance of the supernatant was measured at 370 nm. The carbonyl content is expressed as nmol / mg protein, and the calculation formula is shown in equation (1).

[0185] A = A1 * n * 10 6 / (ε*p) Equation (1)

[0186] Where A represents the total carbonyl mass molar concentration, nmol / mg protein, A1 represents the absorbance at 370nm, n represents the dilution factor, ε represents the molar absorptivity (22000L / (mol*cm)), and P represents the MP solution, mg / mL.

[0187] Thiol groups: 0.5 mL of MP solution (4 mg / mL) was added to 4.5 mL of solution A (8 mol / L urea, 3 mmol / L EDTA, 1% SDS, 0.2 mol / L Tris-HCl, pH=8.0), and incubated at 25 °C for 30 minutes. Then, 4 mL of the mixture was added to 0.5 mL of buffer B (10 mmol / L Tris-HCl, 10 mmol / L DTNB, pH=8.0), and incubated at 40 °C for 25 minutes. After cooling to room temperature, the absorbance was measured at 412 nm, and the total thiol content was calculated using the formula shown in equation (2).

[0188] Total thiol content = A × D / (M × C) Equation (2)

[0189] In the formula, A represents the absorbance value, D represents the dilution factor, M represents the molecular absorptivity, which is 13600 / (mol / L)*cm, and C represents the MP concentration.

[0190] Surface hydrophobicity: determined according to the method described above. Add 200 μL of 1 mg / mL bromophenol blue (BPB) solution to 1 mL of 5 mg / mL myofibrillar protein solution. Separately, take 1 mL of 20 mmol / L phosphate buffer (pH 6.0) and add 200 μL of 1 mg / mL BPB solution. Shake at room temperature for 10 minutes, then centrifuge at 5000 r / min for 15 minutes. Dilute the supernatant 10 times and measure its absorbance at 595 nm. Surface hydrophobicity is calculated according to formula (3).

[0191]

[0192] Where A0 is the absorbance of the blank control solution (Abs); A1 is the absorbance of the sample solution (Abs); and 200 is the total mass (ug) of BPB added to the MP solution.

[0193] To investigate changes in protein secondary structure, α-helices, β-sheets, β-turns, and random coils were measured in chilled fresh meat samples obtained in Examples 4-12, Comparative Examples 1-7, and Comparative Examples 11-13. The results are shown in Table 5. The detection method was as follows: raw meat was cut into thin slices of approximately 3 mm, and the meat samples were pressed onto a stage. A 50x long-focusing lens was used to focus a laser onto the sample on a glass slide. The test parameters used were a 785 nm laser, a 600° grating, 25% transmittance, an exposure time of 30 s, 8 scans, and a scanning range of 400-800 cm⁻¹. -1 The Raman spectra were measured in triplicate, and the data were processed using NGSLabSpec software and PeakFitv 4.12 software.

[0194] Table 6. Changes in the content of protein oxidation indicators

[0195]

[0196] Electron beam irradiation causes myofibrillar protein oxidation, reducing the content of active thiol groups. Irradiation preservation, while preserving freshness, also increases the total carbonyl value and surface hydrophobicity of proteins. Table 6, comparing the data from Comparative Examples 1-4 with those from Examples 4-12, shows that the preservation method of the present invention can inhibit the increase in carbonyl groups caused by irradiation-induced protein oxidation and reduce the thiol content. Simultaneously, the proteins and pectin in the preservation solution facilitate the function of active substances.

[0197] Table 7 Changes in protein secondary structure

[0198]

[0199] As can be seen from the data in Comparative Examples 1-4 in Table 7, with the increase of irradiation dose, the α-helix decreases and the β-sheet increases, indicating that irradiation causes the rearrangement of ordered structures such as the α-helix of proteins or the conversion with disordered structures. This suggests that high-dose irradiation promotes the conversion of α-helices in myofibrillar proteins to β-sheet structures. Compared with the compact α-helix conformation, the peptide chains of the β-sheet structure are more extended in space, exposing active groups such as -SH and hydrophobic groups located inside the molecule, causing protein denaturation and accelerating protein oxidation. However, the α-helix content of myofibrillar proteins in the treatment groups of Examples 4-12 is close to that of Comparative Example 1 (blank control group), indicating that the preservation treatment of the present invention can delay the oxidation of thiol groups during irradiation, suggesting that the preservation treatment method of Examples 4-12 can make the structure of chilled meat relatively more stable.

[0200] Figures 1-3 The particle size distribution curves of the active nano-preservative liquids corresponding to Examples 1 to 3 of the present invention are shown respectively. It can be seen that the active nano-preservative liquids prepared by the present invention have a uniform particle size distribution and an average particle size between 200 and 500 nm.

[0201] Figure 4 The hydroxyl radical scavenging ability (a) and total antioxidant capacity (b) of dietary fiber in the active nano-preservative liquids prepared in Examples 1-3 are shown.

[0202] Antioxidant activity was evaluated using hydroxyl radical scavenging capacity and total antioxidant capacity, using the following specific methods:

[0203] Hydroxyl radical scavenging ability: 4.0 mL of 6 mmol / L salicylic acid-anhydrous ethanol solution, 4.0 mL of 6 mmol / L ferrous sulfate solution, 2.0 mL of sample diluent, and 0.2 mL of 6 mmol / L hydrogen peroxide solution were transferred sequentially, shaken well, incubated in a water bath at 37℃ for 30 min, cooled, and the absorbance was measured at 510 nm (A1). Distilled water was used instead of H2O2 solution as the sample control group (A2), and distilled water was used instead of the sample solution as the blank control group (A0). The calculation formula is as follows:

[0204]

[0205] Total antioxidant capacity

[0206] The determination was performed according to the operating procedures of the Total Antioxidant (T-AOC) assay kit.

[0207] in Figure 4 (a) The hydroxyl radical scavenging capacity of dietary fiber in navel orange peel with different particle sizes. It can be seen that as the number of sieves increases, the hydroxyl radical scavenging capacity of water-soluble dietary fiber in navel orange peel first increases and then decreases, reaching a maximum of 89.41% at 400 mesh. Figure 4(b) The total antioxidant capacity of dietary fiber from navel orange peel at different particle sizes shows that as the number of sieves increases, the total antioxidant capacity of water-soluble dietary fiber in navel orange peel gradually increases and then decreases, which is consistent with the trend of hydroxyl radical scavenging capacity. It reaches its maximum value of 15.34 μmol / g DW at 400 mesh. This indicates that the dietary fiber in navel orange peel has a certain ability to scavenge free radicals.

[0208] Table 8 shows the antioxidant activity of the active nano-preservative liquids prepared in Examples 1-3. Curcumin is a curcumin monomer, polyphenol is a tea polyphenol, and luteolin is a luteolin monomer. The free radical scavenging capabilities were evaluated using ABTS and DPPH, and the specific methods are as follows:

[0209] Determination of ABTS scavenging ability:

[0210] Preparation of ABTS stock solution: Mix 7 mM ABTS solution and 2.45 mM potassium persulfate and let stand for 12-16 h. Before use, dilute the stock solution to prepare the working solution. The absorbance at 734 nm after mixing the diluents is approximately 0.70. ABTS scavenging capacity is determined by diluting the sample to a certain concentration, adding 50 μL to a 96-well plate, then adding 150 μL of the ABTS working solution. After reaction, the absorbance is measured at 734 nm. Use an equal volume of deionized water to replace the sample as a blank control. Use equal volumes of Trolox at different concentrations (0-150 μM) to replace the sample as standard antioxidant groups to create a standard curve. Calculate the ABTS scavenging activity of the sample based on the standard curve, expressed as the TEAC value (Trolox equivalent antioxidant capacity), i.e., μmol TE / g sample.

[0211] DPPH free radical scavenging activity assay: 2 mL of sample was mixed with an equal volume of 0.2 mM DPPH·methanol solution, and the mixture was vigorously shaken in a vortex apparatus until homogeneous. After standing at room temperature in the dark for 30 min, the absorbance was measured at 517 nm using a UV754N. Methanol was used as a blank in the reaction with DPPH·methanol solution instead of the sample, and ethanol was used as a control in the reaction with DPPH·methanol solution instead of the sample. The formula for calculating DPPH free radical scavenging activity is:

[0212] DPPH free radical scavenging activity (%) = [1-(A sample -A blank ) / A control ]×100%

[0213] In the formula A sample A blank and A control The absorbance values ​​at 517 nm represent the absorbance of the sample, blank, and control, respectively.

[0214] The antioxidant activity of preservative-loaded SPN was evaluated by measuring the ABTS and free radical scavenging activities of SPN, luteolin, polyphenols, curcumin, and preservative solutions A, B, and C loaded with luteolin, polyphenols, and curcumin, as shown in Table 8. After loading with active substances, the ABTS free radical scavenging capacity of the resulting preservative solutions was significantly improved (p<0.05). The DPPH free radical scavenging activities of free curcumin, luteolin, and tea polyphenols were slightly lower than those of the loaded preservative solutions. This is because the DPPH free radical scavenging activity was measured in an ethanol system, while the free active substances are well soluble in ethanol, indicating that loading curcumin, luteolin, etc., into SPN does not affect the physiological activity of curcumin itself. Free luteolin and curcumin (at the same loading concentration) showed almost no ABTS radical scavenging activity. This is because luteolin and curcumin have low solubility in the aqueous phase, which verifies that the improved water solubility of luteolin and curcumin after loading enhances their biological activity in the aqueous system.

[0215] Table 8 Antioxidant activity of preservative liquid and monomeric active substances

[0216]

[0217] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0218] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. The application of an active nano-preservation solution for preventing the deterioration of irradiation preservation of chilled fresh meat, characterized in that, The active nanometer preservative liquid for preventing deterioration of irradiation fresh-keeping of chilled fresh meat comprises 0.3-0.9 mg / mL of active ingredients, 2.5-5.0 mg / mL of protein ingredients, 1-2.5 mg / mL of dietary fibers and 2.5-4 mg / mL of galacturonic acid ingredients; The active ingredients comprise at least one of tea polyphenols, curcumin and luteolin; The protein ingredients are at least one of soybean peptide hydrophobic aggregate, walnut protein and soybean protein; The dietary fibers are water-soluble dietary fibers of navel orange peels, and the particle size is 200-400 mesh; The preparation steps of the active nanometer preservative liquid for preventing deterioration of irradiation fresh-keeping of chilled fresh meat comprise: The protein ingredients are configured as a dispersion liquid, and after the pH value is adjusted to 10-12, ultrasonic and microwave treatment is performed for 10-20 min; then the active substances and the dietary fibers are added into the dispersion liquid, and magnetic stirring is performed at room temperature for 20-30 min to obtain a mixed liquid; after the pH value of the mixed liquid is adjusted to 5-7, galacturonic acid is added, and stirring is performed for 10 min, and then centrifugation is performed to obtain supernatant; the supernatant is subjected to dialysis to obtain a liquid component, which is the active nanometer preservative liquid; The ultrasonic and microwave in the ultrasonic and microwave treatment are performed synchronously, the ultrasonic power is 300-500 W, and the microwave power is 150-250 W; The steps of the application comprise: after the meat product is subjected to pre-sterilization by washing, soaking in the active nanometer preservative liquid and nitrogen packaging, irradiation sterilization is performed, and the meat product is stored in a low-temperature environment to complete the fresh-keeping treatment of the chilled fresh meat; the irradiation sterilization comprises irradiation of the chilled fresh meat in an irradiation source field by 60Co-γ rays, and the irradiation dose is 2-6 kGy.

2. Use according to claim 1, characterized in that, The method of the pre-sterilization by washing comprises: the meat product is subjected to washing with an organic acid solution for 30-60 s to complete the pre-sterilization by washing.

3. Use according to claim 2, characterized in that, The concentration of the organic acid solution is 0.05-0.25 wt.%; the organic acid comprises citric acid and tartaric acid, and the mass ratio is 1-2:1-3.

4. Use according to claim 1, characterized in that, The soaking time is 60-120 s.

5. The use according to claim 1, characterized in that, The temperature of the low-temperature environment storage is 0-4℃, and the humidity is 60-75%.

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