A method for preserving the quality of marinated duck products

Abstract

The present invention provides a method for preserving the quality of marinated duck products. The method includes the following steps: S1: roasting the marinated duck; S2: after cooling, wrapping the sterilized marinated duck with a temperature-responsive preservative film embedded with an antioxidant; S3: packaging and vacuumizing with a packaging bag; S4: preserving at room temperature after sterilization. The present invention uses a temperature-responsive preservative film embedded with an antioxidant to preserve the marinated duck. The shell layer of the preservative film is composed of temperature-responsive hydroxypropyl cellulose and polyvinyl alcohol. During the preservation of the marinated duck, with the change of temperature, the pore size and porosity of the preservative film change, thereby regulating the release of the antioxidant. When the temperature is high, the release is fast, and when the temperature is low, the release is slow.

Description

Technical Field

[0001] The present invention relates to the technical field of food preservation, and particularly relates to a method for preserving the quality of marinated duck products. Background Art

[0002] Marinated duck is a traditional marinated product in China, rich in nutrition, protein and moisture, meeting the current development trend of food nutrition, convenience and functional diversification. However, due to the rich nutritional components and high water activity of marinated duck, and more importantly, the high fat content of marinated duck, lipid oxidation and spoilage are likely to occur during processing, storage, transportation and sales. In the processing of traditional meat products, firstly, some antioxidants, preservatives and colorants are usually added to preserve food, but currently these commonly used additives are mainly chemically synthesized products, and their safety is constantly questioned. For example, adding the food antioxidant tert-butylhydroquinone to marinated products usually causes too high acid value; nitrates and nitrites are widely used in marinated products to play roles such as coloring, bacteriostasis, antioxidant, improving flavor and texture, etc., but the two will be converted into nitrosamines, which have mutagenic and carcinogenic effects. Secondly, packaging is used to achieve the purpose of preservation. The commonly used packaging methods mainly include vacuum packaging, modified atmosphere packaging, traditional antibacterial packaging, etc., but the effects are not ideal. Moreover, the aroma of marinated duck, as an important part of the quality of marinated duck, is often ignored. Therefore, providing a method for preserving the original aroma of marinated duck and better preserving it at room temperature is an urgent problem to be solved currently. Summary of the Invention

[0003] Technical problems to be solved: Aiming at the above technical problems, the purpose of the present invention is to provide a method for preserving the quality of marinated duck products, using a temperature-responsive preservative film embedded with an antioxidant to preserve marinated duck. The shell layer of the preservative film is composed of temperature-responsive hydroxypropyl cellulose and polyvinyl alcohol. During the preservation of marinated duck, with the change of temperature, the pore size and porosity of the preservative film change, thereby regulating the release of the antioxidant. At high temperature, the release is fast, and at low temperature, the release is slow.

[0004] Technical solution: A method for preserving the quality of marinated duck products includes the following steps:

[0005] S1: Roasting of marinated duck;

[0006] S2: After cooling, wrapping the sterilized marinated duck with a temperature-responsive preservative film embedded with an antioxidant;

[0007] S3: Packaging with a packaging bag and vacuumizing;

[0008] S4: Preserving at room temperature after sterilization.

[0009] Preferably, the thickness of the temperature-responsive preservative film embedded with antioxidants is 8-12 μm.

[0010] Preferably, the preparation method of the temperature-responsive cling film embedded with antioxidants is as follows:

[0011] S21: β-cyclodextrin, hydroxypropyl cellulose, polyvinyl alcohol and water are mixed and stirred to dissolve, and allowed to stand for degassing to obtain a shell electrospinning solution;

[0012] S22: mixing an antioxidant and a 60% ethanol solution to obtain a core electrospinning solution;

[0013] S23: Spinning is performed using a coaxial electrospinning method to obtain a spinning membrane;

[0014] S24: Drying at room temperature to obtain the temperature-responsive plastic wrap embedded with the antioxidant.

[0015] Preferably, the mass ratio of the β-cyclodextrin, hydroxypropyl cellulose, polyvinyl alcohol and water is (10-15): (4-6): 30: 100. Preferably, the antioxidant is a mixture of natural antioxidants, namely grape seed extract and carnosine, and the mass ratio of the two is (1-2): 1.

[0016] Preferably, the mass-to-volume ratio of the grape seed extract and carnosine mixture to the 60% ethanol solution is (6-9):100. Preferably, the coaxial electrospinning conditions are: a core electrospinning solution flow rate of 0.5 mL / h, a shell electrospinning solution flow rate of 0.6 mL / h, a spinning voltage of 20 kV, and a receiving distance of 15 cm.

[0017] Preferably, the sterilization method adopts high-temperature steaming sterilization at a temperature of 145° C. and a time of 10 minutes.

[0018] Beneficial effects:

[0019] 1. The present invention uses a temperature-responsive preservative film embedded with an antioxidant to preserve the marinated duck. The shell layer of the preservative film is composed of temperature-responsive hydroxypropyl cellulose and polyvinyl alcohol. During the storage of the marinated duck, the pore size and porosity of the preservative film change with the change of temperature, thereby regulating the release of the antioxidant. When the temperature is high, the release is fast, and when the temperature is low, the release is slow.

[0020] 2. β-cyclodextrin is also added to the shell layer of the preservative film of the present invention. β-cyclodextrin can effectively restrain the aroma of the braised duck, so that it can maintain its original fragrance as much as possible. At the same time, β-cyclodextrin also has a certain pore-forming effect, generating fine pores so that the antioxidant can be released to a certain extent under low temperature conditions.

[0021] 3. In the present invention, the antioxidant is encapsulated in the shell layer of the fresh-keeping film by coaxial electrospinning, which can increase its stability, maintain a high antioxidant effect, and can be slowly released during use, reducing the oxidation of grease, generating a rancid smell, affecting the taste, and prolonging the shelf life of the marinated duck.

[0022] 4. In the present invention, the antioxidant is selected as a mixture of natural grape seed extract and carnosine. From the test data of Example 14, Comparative Example 6 and Comparative Example 7, it can be seen that the effect of the mixture of grape seed extract and carnosine is far better than that of using grape seed extract or carnosine alone, and its synergistic mechanism remains to be further studied.

[0023] 5. The temperature-responsive fresh-keeping film embedded with antioxidant of the present invention can not only effectively maintain the original aroma of the marinated duck, but also has a good antioxidant effect, maintain the quality of the marinated duck, and avoid the use of preservatives at the same time, and the method is healthier. Brief Description of the Drawings

[0024] Figure 1 It is the DSC curve of the temperature-responsive fresh-keeping film of Example 8. Detailed Description of the Invention

[0025] The present invention provides a method for preserving the quality of marinated duck products. To make the purpose, technical solution and effect of the present invention clearer and more definite, the following will further elaborate on the present invention in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0026] Example 1

[0027] The preparation method of the temperature-responsive fresh-keeping film embedded with antioxidant is as follows:

[0028] S21: Take β-cyclodextrin, hydroxypropyl cellulose, polyvinyl alcohol and water with a mass ratio of 10:4:30:100, mix and stir to dissolve, and let it stand for defoaming to obtain the shell layer electrospinning solution;

[0029] S22: Take a mixture of grape seed extract and carnosine with a mass ratio of 1.5:1 and a 60% ethanol solution, and mix and stir. The mass-volume ratio of the mixture of grape seed extract and carnosine to the 60% ethanol solution is 8:100 to obtain the core layer electrospinning solution;

[0030] S23: Use the coaxial electrospinning method for spinning. The conditions for coaxial electrospinning are: the flow rate of the core layer electrospinning solution is 0.5 mL / h, the flow rate of the shell layer electrospinning solution is 0.6 mL / h, the spinning voltage is 20 kV, and the receiving distance is 15 cm to obtain the spun film;

[0031] S24: Dry at room temperature to obtain the temperature-responsive fresh-keeping film embedded with antioxidant.

[0032] Example 2

[0033] The preparation method of the temperature-responsive fresh-keeping film embedded with antioxidants is as follows:

[0034] S21: Take β-cyclodextrin, hydroxypropyl cellulose, polyvinyl alcohol and water with a mass ratio of 10:5:30:100, mix and stir to dissolve, and let stand to defoam to obtain the shell electrospinning solution;

[0035] S22: Take a mixture of grape seed extract and carnosine with a mass ratio of 1.5:1 and a 60% ethanol solution, mix and stir. The mass-volume ratio of the mixture of grape seed extract and carnosine to the 60% ethanol solution is 8:100 to obtain the core electrospinning solution;

[0036] S23: Use the coaxial electrospinning method for spinning. The conditions for coaxial electrospinning are: the flow rate of the core electrospinning solution is 0.5 mL / h, the flow rate of the shell electrospinning solution is 0.6 mL / h, the spinning voltage is 20 kV, and the receiving distance is 15 cm to obtain the spun film;

[0037] S24: Dry at room temperature to obtain the temperature-responsive fresh-keeping film embedded with antioxidants.

[0038] Example 3

[0039] The preparation method of the temperature-responsive fresh-keeping film embedded with antioxidants is as follows:

[0040] S21: Take β-cyclodextrin, hydroxypropyl cellulose, polyvinyl alcohol and water with a mass ratio of 10:6:30:100, mix and stir to dissolve, and let stand to defoam to obtain the shell electrospinning solution;

[0041] S22: Take a mixture of grape seed extract and carnosine with a mass ratio of 1.5:1 and a 60% ethanol solution, mix and stir. The mass-volume ratio of the mixture of grape seed extract and carnosine to the 60% ethanol solution is 8:100 to obtain the core electrospinning solution;

[0042] S23: Use the coaxial electrospinning method for spinning. The conditions for coaxial electrospinning are: the flow rate of the core electrospinning solution is 0.5 mL / h, the flow rate of the shell electrospinning solution is 0.6 mL / h, the spinning voltage is 20 kV, and the receiving distance is 15 cm to obtain the spun film;

[0043] S24: Dry at room temperature to obtain the temperature-responsive fresh-keeping film embedded with antioxidants.

[0044] Example 4

[0045] The preparation method of the temperature-responsive fresh-keeping film embedded with antioxidants is as follows:

[0046] S21: Mix β-cyclodextrin, hydroxypropyl cellulose, polyvinyl alcohol and water with a mass ratio of 13:4:30:100, stir and dissolve, and stand for defoaming to obtain the shell electrospinning solution;

[0047] S22: Mix a mixture of grape seed extract and carnosine with a mass ratio of 1.5:1 and an ethanol solution with a concentration of 60%, and the mass-volume ratio of the mixture of grape seed extract and carnosine to the 60% ethanol solution is 8:100, and stir to obtain the core electrospinning solution;

[0048] S23: Use the coaxial electrospinning method for spinning. The conditions for coaxial electrospinning are: the flow rate of the core electrospinning solution is 0.5 mL / h, the flow rate of the shell electrospinning solution is 0.6 mL / h, the spinning voltage is 20 kV, and the receiving distance is 15 cm to obtain the spun film;

[0049] S24: Dry at room temperature to obtain the temperature-responsive fresh-keeping film embedded with antioxidants.

[0050] Example 5

[0051] The preparation method of the temperature-responsive fresh-keeping film embedded with antioxidants is as follows:

[0052] S21: Mix β-cyclodextrin, hydroxypropyl cellulose, polyvinyl alcohol and water with a mass ratio of 13:5:30:100, stir and dissolve, and stand for defoaming to obtain the shell electrospinning solution;

[0053] S22: Mix a mixture of grape seed extract and carnosine with a mass ratio of 1.5:1 and an ethanol solution with a concentration of 60%, and the mass-volume ratio of the mixture of grape seed extract and carnosine to the 60% ethanol solution is 8:100, and stir to obtain the core electrospinning solution;

[0054] S23: Use the coaxial electrospinning method for spinning. The conditions for coaxial electrospinning are: the flow rate of the core electrospinning solution is 0.5 mL / h, the flow rate of the shell electrospinning solution is 0.6 mL / h, the spinning voltage is 20 kV, and the receiving distance is 15 cm to obtain the spun film;

[0055] S24: Dry at room temperature to obtain the temperature-responsive fresh-keeping film embedded with antioxidants.

[0056] Example 6

[0057] The preparation method of the temperature-responsive fresh-keeping film embedded with antioxidants is as follows:

[0058] S21: Mix β-cyclodextrin, hydroxypropyl cellulose, polyvinyl alcohol and water with a mass ratio of 13:6:30:100, stir and dissolve, and stand for defoaming to obtain the shell electrospinning solution;

[0059] S22: Mix and stir a mixture of grape seed extract and carnosine with a mass ratio of 1.5:1 and an ethanol solution with a concentration of 60%. The mass-to-volume ratio of the mixture of grape seed extract and carnosine to the 60% ethanol solution is 8:100 to obtain a core layer electrospinning solution;

[0060] S23: Use coaxial electrospinning method for spinning. The conditions for coaxial electrospinning are as follows: the flow rate of the core layer electrospinning solution is 0.5 mL / h, the flow rate of the shell layer electrospinning solution is 0.6 mL / h, the electrospinning voltage is 20 kV, and the receiving distance is 15 cm to obtain a spun film;

[0061] S24: Dry at room temperature to obtain a temperature-responsive preservative film embedded with antioxidants.

[0062] Example 7

[0063] The preparation method of the temperature-responsive preservative film embedded with antioxidants is as follows:

[0064] S21: Take β-cyclodextrin, hydroxypropyl cellulose, polyvinyl alcohol and water with a mass ratio of 15:4:30:100, mix and stir to dissolve, and let stand for defoaming to obtain a shell layer electrospinning solution;

[0065] S22: Mix and stir a mixture of grape seed extract and carnosine with a mass ratio of 1.5:1 and an ethanol solution with a concentration of 60%. The mass-to-volume ratio of the mixture of grape seed extract and carnosine to the 60% ethanol solution is 8:100 to obtain a core layer electrospinning solution;

[0066] S23: Use coaxial electrospinning method for spinning. The conditions for coaxial electrospinning are as follows: the flow rate of the core layer electrospinning solution is 0.5 mL / h, the flow rate of the shell layer electrospinning solution is 0.6 mL / h, the electrospinning voltage is 20 kV, and the receiving distance is 15 cm to obtain a spun film;

[0067] S24: Dry at room temperature to obtain a temperature-responsive preservative film embedded with antioxidants.

[0068] Example 8

[0069] The preparation method of the temperature-responsive preservative film embedded with antioxidants is as follows:

[0070] S21: Take β-cyclodextrin, hydroxypropyl cellulose, polyvinyl alcohol and water with a mass ratio of 15:5:30:100, mix and stir to dissolve, and let stand for defoaming to obtain a shell layer electrospinning solution;

[0071] S22: Mix and stir a mixture of grape seed extract and carnosine with a mass ratio of 1.5:1 and an ethanol solution with a concentration of 60%. The mass-to-volume ratio of the mixture of grape seed extract and carnosine to the 60% ethanol solution is 8:100 to obtain a core layer electrospinning solution;

[0072] S23: Spinning is carried out by coaxial electrospinning. The conditions for coaxial electrospinning are as follows: the flow rate of the core-layer electrospinning solution is 0.5 mL / h, the flow rate of the shell-layer electrospinning solution is 0.6 mL / h, the spinning voltage is 20 kV, and the receiving distance is 15 cm to obtain a spun film;

[0073] S24: It is dried at room temperature to obtain a temperature-responsive fresh-keeping film embedded with an antioxidant.

[0074] Example 9

[0075] The preparation method of the temperature-responsive fresh-keeping film embedded with an antioxidant is as follows:

[0076] S21: Take β-cyclodextrin, hydroxypropyl cellulose, polyvinyl alcohol and water with a mass ratio of 15:5:30:100, mix and stir to dissolve, and let it stand for defoaming to obtain a shell-layer electrospinning solution;

[0077] S22: Take a mixture of grape seed extract and carnosine with a mass ratio of 1:1 and a 60% ethanol solution, mix and stir. The mass-volume ratio of the mixture of grape seed extract and carnosine to the 60% ethanol solution is 8:100 to obtain a core-layer electrospinning solution;

[0078] S23: Spinning is carried out by coaxial electrospinning. The conditions for coaxial electrospinning are as follows: the flow rate of the core-layer electrospinning solution is 0.5 mL / h, the flow rate of the shell-layer electrospinning solution is 0.6 mL / h, the spinning voltage is 20 kV, and the receiving distance is 15 cm to obtain a spun film;

[0079] S24: It is dried at room temperature to obtain a temperature-responsive fresh-keeping film embedded with an antioxidant.

[0080] Example 10

[0081] The preparation method of the temperature-responsive fresh-keeping film embedded with an antioxidant is as follows:

[0082] S21: Take β-cyclodextrin, hydroxypropyl cellulose, polyvinyl alcohol and water with a mass ratio of 15:5:30:100, mix and stir to dissolve, and let it stand for defoaming to obtain a shell-layer electrospinning solution;

[0083] S22: Take a mixture of grape seed extract and carnosine with a mass ratio of 2:1 and a 60% ethanol solution, mix and stir. The mass-volume ratio of the mixture of grape seed extract and carnosine to the 60% ethanol solution is 8:100 to obtain a core-layer electrospinning solution;

[0084] S23: Spinning is carried out by coaxial electrospinning. The conditions for coaxial electrospinning are as follows: the flow rate of the core-layer electrospinning solution is 0.5 mL / h, the flow rate of the shell-layer electrospinning solution is 0.6 mL / h, the spinning voltage is 20 kV, and the receiving distance is 15 cm to obtain a spun film;

[0085] S24: Obtain the temperature-responsive preservative film embedded with antioxidants by drying at room temperature.

[0086] Example 11

[0087] The preparation method of the temperature-responsive preservative film embedded with antioxidants is as follows:

[0088] S21: Take β-cyclodextrin, hydroxypropyl cellulose, polyvinyl alcohol and water with a mass ratio of 15:5:30:100, mix and stir to dissolve, and let it stand for defoaming to obtain the shell electrospinning solution;

[0089] S22: Take a mixture of grape seed extract and carnosine with a mass ratio of 1.5:1 and a 60% ethanol solution, mix and stir. The mass-volume ratio of the mixture of grape seed extract and carnosine to the 60% ethanol solution is 6:100 to obtain the core electrospinning solution;

[0090] S23: Use the coaxial electrospinning method for spinning. The conditions for coaxial electrospinning are: the flow rate of the core electrospinning solution is 0.5 mL / h, the flow rate of the shell electrospinning solution is 0.6 mL / h, the spinning voltage is 20 kV, and the receiving distance is 15 cm to obtain the spun film;

[0091] S24: Obtain the temperature-responsive preservative film embedded with antioxidants by drying at room temperature.

[0092] Example 12

[0093] The preparation method of the temperature-responsive preservative film embedded with antioxidants is as follows:

[0094] S21: Take β-cyclodextrin, hydroxypropyl cellulose, polyvinyl alcohol and water with a mass ratio of 15:5:30:100, mix and stir to dissolve, and let it stand for defoaming to obtain the shell electrospinning solution;

[0095] S22: Take a mixture of grape seed extract and carnosine with a mass ratio of 1.5:1 and a 60% ethanol solution, mix and stir. The mass-volume ratio of the mixture of grape seed extract and carnosine to the 60% ethanol solution is 9:100 to obtain the core electrospinning solution;

[0096] S23: Use the coaxial electrospinning method for spinning. The conditions for coaxial electrospinning are: the flow rate of the core electrospinning solution is 0.5 mL / h, the flow rate of the shell electrospinning solution is 0.6 mL / h, the spinning voltage is 20 kV, and the receiving distance is 15 cm to obtain the spun film;

[0097] S24: Obtain the temperature-responsive preservative film embedded with antioxidants by drying at room temperature.

[0098] Comparative Example 1

[0099] The difference between this comparative example and Example 8 is that it does not contain β-cyclodextrin, which is replaced by hydroxypropyl cellulose, specifically as follows:

[0100] The preparation method of the temperature-responsive fresh-keeping film embedded with antioxidants is as follows:

[0101] S21: Take hydroxypropyl cellulose, polyvinyl alcohol and water with a mass ratio of 20:30:100, mix and stir to dissolve, and let it stand for defoaming to obtain the shell electrospinning solution;

[0102] S22: Take a mixture of grape seed extract and carnosine with a mass ratio of 1.5:1 and a 60% ethanol solution, and mix and stir. The mass-volume ratio of the mixture of grape seed extract and carnosine to the 60% ethanol solution is 8:100 to obtain the core electrospinning solution;

[0103] S23: Use the coaxial electrospinning method for spinning. The conditions for coaxial electrospinning are: the flow rate of the core electrospinning solution is 0.5 mL / h, the flow rate of the shell electrospinning solution is 0.6 mL / h, the spinning voltage is 20 kV, and the receiving distance is 15 cm to obtain the spun film;

[0104] S24: Dry at room temperature to obtain the temperature-responsive fresh-keeping film embedded with antioxidants.

[0105] Comparative Example 2

[0106] The difference between this comparative example and Example 8 is that the antioxidant uses a single grape seed extract, specifically as follows:

[0107] The preparation method of the temperature-responsive fresh-keeping film embedded with antioxidants is as follows:

[0108] S21: Take β-cyclodextrin, hydroxypropyl cellulose, polyvinyl alcohol and water with a mass ratio of 15:5:30:100, mix and stir to dissolve, and let it stand for defoaming to obtain the shell electrospinning solution;

[0109] S22: Take grape seed extract and a 60% ethanol solution, mix and stir. The mass-volume ratio of grape seed extract to the 60% ethanol solution is 8:100 to obtain the core electrospinning solution;

[0110] S23: Use the coaxial electrospinning method for spinning. The conditions for coaxial electrospinning are: the flow rate of the core electrospinning solution is 0.5 mL / h, the flow rate of the shell electrospinning solution is 0.6 mL / h, the spinning voltage is 20 kV, and the receiving distance is 15 cm to obtain the spun film;

[0111] S24: Dry at room temperature to obtain the temperature-responsive fresh-keeping film embedded with antioxidants.

[0112] Comparative Example 3

[0113] The difference between this comparative example and Example 8 is that a single carnosine is used as the antioxidant, specifically as follows:

[0114] The preparation method of the temperature-responsive fresh-keeping film embedded with an antioxidant is as follows:

[0115] S21: Take β-cyclodextrin, hydroxypropyl cellulose, polyvinyl alcohol and water with a mass ratio of 15:5:30:100, mix and stir to dissolve, and let it stand for defoaming to obtain the shell electrospinning solution;

[0116] S22: Take carnosine and a 60% ethanol solution, mix and stir, and the mass-volume ratio of carnosine to the 60% ethanol solution is 8:100 to obtain the core electrospinning solution;

[0117] S23: Use the coaxial electrospinning method for spinning. The conditions for coaxial electrospinning are as follows: the flow rate of the core electrospinning solution is 0.5 mL / h, the flow rate of the shell electrospinning solution is 0.6 mL / h, the spinning voltage is 20 kV, and the receiving distance is 15 cm to obtain a spun film;

[0118] S24: Dry at room temperature to obtain the temperature-responsive fresh-keeping film embedded with an antioxidant.

[0119] The thickness of the fresh-keeping film in the above examples is 10 μm.

[0120] Measure the encapsulation efficiency of the mixture of grape seed extract and carnosine in the fresh-keeping film;

[0121] Measure the mechanical properties: including tensile strength and elongation at break.

[0122] Table 1

[0123] Entrapment efficiency (%) Tensile strength (MPa) Elongation at break (%) Example 1 89.36 17.15 38.54 Example 2 88.83 16.56 37.91 Example 3 88.42 16.33 37.46 Example 4 89.70 17.52 38.97 Example 5 89.72 17.59 38.94 Example 6 89.14 16.89 38.22 Example 7 89.52 17.41 38.82 Example 8 89.81 17.63 39.01 Example 9 89.77 17.62 38.99 Example 10 89.79 17.63 38.98 Example 11 89.63 17.56 38.87 Example 12 89.83 17.66 39.01 Comparative Example 1 80.34 15.42 34.25 Comparative Example 2 89.69 17.62 38.97 Comparative Example 3 89.73 17.65 38.99

[0124] Measure the temperature-sensitive characteristics of the fresh-keeping film of Example 8, and use differential scanning calorimetry to measure its phase transition process and phase transition temperature. The results are as Figure 1 shown. There are two absorption peaks at 28.5 and 31.8 °C respectively, with obvious temperature-sensitive characteristics, and it can be obtained from the test that the main working range of its temperature-sensitive characteristics is 29-32 °C.

[0125] Measure the release rates of the mixture of grape seed extract and carnosine on the 1st day, 10th day and 20th day in environments of 0 °C, 15 °C and 32 °C respectively.

[0126] Table 2

[0127]

[0128]

[0129] After comprehensive comparison, including encapsulation efficiency, mechanical properties, and release rate, which should be neither too fast nor too slow. If it is too fast, subsequent preservation cannot keep up; if it is too slow, the quality of the marinated duck in the early stage will be affected. Therefore, the temperature-responsive preservative film embedded with antioxidants prepared in Example 8 was selected for subsequent experiments.

[0130] Example 13

[0131] A method for preserving the quality of marinated duck products, comprising the following steps:

[0132] S1: Roasting of marinated duck;

[0133] S2: After cooling, wrap the sterilized marinated duck with a temperature-responsive preservative film with a thickness of 8 μm embedded with antioxidants;

[0134] S3: Package with a packaging bag and evacuate;

[0135] S4: Sterilize by high-temperature steaming, at a temperature of 145 °C for 10 min, and preserve at room temperature after sterilization.

[0136] Example 14

[0137] A method for preserving the quality of marinated duck products, comprising the following steps:

[0138] S1: Roasting of marinated duck;

[0139] S2: After cooling, wrap the sterilized marinated duck with a temperature-responsive preservative film with a thickness of 10 μm embedded with antioxidants;

[0140] S3: Package with a packaging bag and evacuate;

[0141] S4: Sterilize by high-temperature steaming, at a temperature of 145 °C for 10 min, and preserve at room temperature after sterilization.

[0142] Example 15

[0143] A method for preserving the quality of marinated duck products, comprising the following steps:

[0144] S1: Roasting of marinated duck;

[0145] S2: After cooling, wrap the sterilized marinated duck with a temperature-responsive preservative film with a thickness of 12 μm embedded with antioxidants;

[0146] S3: Package with a packaging bag and evacuate;

[0147] S4: Sterilize by high-temperature steaming, at a temperature of 145 °C for 10 min, and preserve at room temperature after sterilization.

[0148] Comparative Example 4

[0149] The difference between this comparative example and Example 14 is that instead of using the temperature-responsive fresh-keeping film embedded with antioxidants prepared, a conventional fresh-keeping film on the market (brand: Miaojie) is used, and an equal amount of antioxidants in Example 14 is added during the roasting process of marinated duck.

[0150] Comparative Example 5

[0151] The difference between this comparative example and Example 14 is that instead of using the fresh-keeping film prepared in Example 8, the fresh-keeping film prepared in Comparative Example 1 is used.

[0152] Comparative Example 6

[0153] The difference between this comparative example and Example 14 is that instead of using the fresh-keeping film prepared in Example 8, the fresh-keeping film prepared in Comparative Example 2 is used.

[0154] Comparative Example 7

[0155] The difference between this comparative example and Example 14 is that instead of using the fresh-keeping film prepared in Example 8, the fresh-keeping film prepared in Comparative Example 3 is used.

[0156] After the marinated duck is stored at room temperature (24 - 30 °C) for 20 days, the total number of colonies, volatile basic nitrogen and sensory evaluation are carried out on it;

[0157] Total number of colonies: It is determined according to the plate counting method in the national standard GB / T4789.2 - 2008, with 3 plates for each dilution gradient.

[0158] Volatile basic nitrogen: Based on the principle of semi-micro Kjeldahl method, an automatic Kjeldahl nitrogen analyzer is used to determine the volatile basic nitrogen of the marinated duck.

[0159] Sensory evaluation: A scoring group consisting of 10 teachers and students from this college conducts sensory evaluation, and the evaluation criteria are shown in Table 3 below.

[0160] Table 3 Sensory scoring criteria for marinated duck

[0161]

[0162] Table 4

[0163]

[0164]

[0165] As can be seen from Table 4, the total number of colonies in Examples 13 - 15 is relatively low, fully meeting the requirements of the Hygiene Standard for Cooked Meat Products (GB2726 - 2005). The total number of bacteria in braised and marinated meat products should be ≤ 4.9 lg (CFU / g). The volatile basic nitrogen and sensory evaluation are both the best in Example 15, but the cost of Example 15 is also the highest. After comprehensive comparison, Example 14 has the highest cost performance.

[0166] The aroma components were determined by GC - MS, and the results are shown in Table 5.

[0167] Table 5

[0168]

[0169] As can be seen from Table 5, 42 aroma components were detected in the braised duck of Example 14, while only 14 and 19 aroma components were detected in Comparative Example 4 and Comparative Example 5 respectively. Thus, it can be seen that the fresh - keeping film added with β - cyclodextrin can effectively bind the aroma components in the braised duck.

Claims

1. A method for preserving the quality of marinated duck products, characterized in that, It includes the following steps: S1: Roasting the marinated duck; S2: After cooling, wrapping the sterilized marinated duck with a temperature-responsive preservative film embedded with an antioxidant; S3: Packaging with a packaging bag and evacuating; S4: Fresh-keeping at room temperature after sterilization; The preparation method of the temperature-responsive preservative film embedded with an antioxidant is as follows: S21: Take β-cyclodextrin, hydroxypropyl cellulose, polyvinyl alcohol and water, mix and stir to dissolve, and let it stand for defoaming to obtain a shell layer electrospinning solution; S22: Take an antioxidant and a 60% ethanol solution, mix and stir to obtain a core layer electrospinning solution; S23: Spin by coaxial electrospinning method to obtain a spun film; S24: Dry at room temperature to obtain a temperature-responsive preservative film embedded with an antioxidant; The mass ratio of the β-cyclodextrin, hydroxypropyl cellulose, polyvinyl alcohol and water is (10-15):(4-6):30:100; The antioxidant is a natural antioxidant, which is a mixture of grape seed extract and carnosine, and the mass ratio of the two is (1-2):1; The conditions of the coaxial electrospinning are: the flow rate of the core layer electrospinning solution is 0.5 mL / h, the flow rate of the shell layer electrospinning solution is 0.6 mL / h, the electrospinning voltage is 20 kV, and the receiving distance is 15 cm.

2. The quality preservation method of a marinated duck product according to claim 1, characterized in that The thickness of the temperature-responsive preservative film embedded with an antioxidant is 8-12 μm.

3. A method for preserving the quality of marinated duck products according to claim 1, characterized in that, The mass-volume ratio of the mixture of grape seed extract and carnosine and the 60% ethanol solution is (6-9):

100.

4. A method for preserving the quality of marinated duck products according to claim 1, characterized in that, In S4, the sterilization method is high-temperature steaming sterilization, the temperature is 145°C, and the time is 10 min.

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