Chicken premade dish and preparation method thereof

Abstract

The invention relates to the technical field of food processing, in particular to a chicken premade dish and a preparation method thereof. By innovatively integrating a laccase-chequer-shaped indocalamus leaf cross-linking system and a double-frequency ultrasonic pretreatment process, the water retention, bacteriostasis and flavor regulation performance of the chicken premade dish can be synchronously improved, and the effect cannot be replaced by other enzymes such as papain; besides, double-frequency ultrasonic pretreatment is adopted, dynamic balance of deep penetration-surface tenderization is achieved through frequency alternation, and compared with single-frequency or traditional soaking, the method can better cooperate with laccase catalysis to directionally cross-link the preservative, and the effects of water retention, bacteriostasis and flavor regulation and control are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of food processing, and specifically relates to a chicken prefabricated dish and a preparation method thereof. Background Art

[0002] With the acceleration of the social rhythm and the change of people's lifestyles, convenient and fast prefabricated dish products are widely welcomed in the market. As a healthy meat with high protein and low fat, chicken is an important category in the prefabricated dish market. However, in the production, processing and heating processes of prefabricated chicken products, there are generally technical problems such as poor water retention, nutrient loss, and deteriorated taste, which seriously affect the product quality and the consumer's eating experience.

[0003] In the processing of traditional chicken prefabricated dishes, poor water retention, microbial spoilage and taste deterioration are long-existing technical problems in the industry. In addition, the traditional process relies on static soaking or single-frequency ultrasonic treatment, which is difficult to achieve deep penetration of the flavoring base, resulting in uneven flavor and residual fishy smell. Therefore, developing a green and efficient multi-functional synergistic technology to simultaneously improve water retention, antibacterial property and sensory quality has become an urgent need for the upgrading of the prefabricated dish industry. Summary of the Invention

[0004] In view of the deficiencies in the prior art, the present invention provides a chicken prefabricated dish and a preparation method thereof.

[0005] A chicken prefabricated dish, calculated by mass, is composed of the following raw materials: 85-90 parts of pretreated chicken, 6-10 parts of a composite flavoring base, and 3-6 parts of a laccase-catalyzed directional cross-linking preservative.

[0006] The composite flavoring base, calculated by mass percentage, is composed of the following components: Table salt 10-12%; White granulated sugar 5-7%; Soy sauce 8-12%; Cooking wine 4-6%; Black pepper powder 1-3%; Monosodium glutamate 4-6%; Chili powder 3-5%; Rapeseed oil 10-12%; The balance is water.

[0007] The preparation method of the laccase-catalyzed directional cross-linking preservative includes the following steps: S1 Raw material pretreatment: Mix the Indocalamus leaf powder and water at a mass ratio of 1:(14 - 16), perform water bath treatment at 79 - 81 °C for 25 - 35 min, filter through a 0.4 - 0.5 μm filter membrane to obtain a filtrate, and obtain the Indocalamus leaf extract after freeze-drying; Mix whey protein and water at 45 - 55 °C at a mass ratio of 3:(46 - 48), stir at 200 - 300 r / min until completely dissolved to obtain a whey protein solution; S2 Construction of cross-linking system: Add the Indocalamus leaf extract obtained in S1 to the whey protein solution obtained in S1, then add laccase and a CaCl2 solution with a concentration of 0.05 - 0.15 mol / ml, then place it under constant temperature stirring reaction at 40 - 50 °C for 110 - 130 min, and control the dissolved oxygen to be 4 - 6 mg / L; S3 Reaction termination and curing: After the reaction in step S2 ends, raise the temperature to 80 - 90 °C and maintain it for 8 - 12 min to inactivate laccase, then transfer it to a cold storage at 0 - 4 °C and let it stand for 10 - 14 h to obtain a fresh-keeping gel; S4 Post-treatment process: Cut the fresh-keeping gel obtained in step S3 into 3 - 7 mm³ particles, wash it 2 - 3 times with water to remove free calcium ions, then vacuum freeze-dry it to a water content of 1 wt% - 5 wt% to obtain a dried fresh-keeping gel, and pulverize it through a 90 - 120 mesh sieve to obtain the laccase-catalyzed directional cross-linked fresh-keeping agent.

[0008] The Indocalamus leaf powder described in step S1 is subjected to drying treatment, with a water content of 1 wt% - 7 wt%, and is obtained by passing through a 90 - 120 mesh sieve.

[0009] In the whey protein solution in step S2, the concentration of the Indocalamus leaf extract is 2 - 4 wt%, and the concentration of the CaCl2 solution in the whey protein solution is 15 mmol / ml.

[0010] The addition amount of laccase in step S2 is 40 - 60 U / g of whey protein.

[0011] The conditions for vacuum freeze-drying in step S4 are -50 - (-40) °C and 9 - 11 Pa.

[0012] The present invention also provides a preparation method for a prefabricated chicken dish, including the following steps: (1) Cut the chicken pieces evenly, then immerse them in a 1 - 2 wt% saline solution, and perform dual-frequency ultrasonic field treatment for 14 - 16 min. After completion, take them out and drain to obtain pretreated chicken; (2) By mass, put 85 - 90 parts of the pretreated chicken obtained in step (1) into a tumbler, add 6 - 10 parts of a compound flavoring base material and 3 - 6 parts of the laccase-catalyzed directional cross-linked fresh-keeping agent, set the vacuum degree to -0.085 - (-0.095) MPa, the rotation speed to 10 - 12 r / min, and the temperature to 3 - 5 °C, and tumble for 30 - 45 min to obtain flavored chicken; (3) Vacuum package the seasoned chicken obtained in step (3) using a special microwave heating packaging bag, and then freeze it to -10°C - (-5)°C to obtain the chicken prefabricated dish.

[0013] In the dual-frequency ultrasonic field treatment described in step (1), the low-frequency ultrasonic frequency is 39 - 41 kHz, the high-frequency is 0.9 - 1.1 MHz, the power density is 14 - 16 W / cm², the two frequencies alternate, and each frequency is treated for 85 - 95 s.

[0014] Advantages of the present invention: By innovatively integrating the laccase - bamboo leaf crosslinking system and the dual-frequency ultrasonic pretreatment process, the present invention can simultaneously improve the water retention, antibacterial, and flavor regulation properties of chicken prefabricated dishes, and this effect cannot be replaced by other enzymes such as papain; in addition, the dual-frequency ultrasonic pretreatment of the present invention achieves a dynamic balance of "deep penetration - surface tenderization" through frequency alternation. Compared with single frequency or traditional soaking, it can better synergistically catalyze the directional crosslinking preservative with laccase, playing a role in water retention, antibacterial, and flavor regulation.

[0015] In summary, through the synergistic regulation of the laccase - bamboo leaf crosslinking system and dual-frequency ultrasound, the present invention breaks through the technical bottleneck that it is difficult to balance "water retention - antibacterial - flavor" in traditional preservation technologies, providing a new solution for the quality upgrade of prefabricated dishes. Specific embodiments

[0016] Table salt, granulated sugar, soy sauce, cooking wine, black pepper powder, monosodium glutamate, chili powder, and rapeseed oil are conventional edible seasonings in the art.

[0017] Whey protein, product number: S31107, Shanghai Yuanye Bio-Technology Co., Ltd.

[0018] Laccase, purity: 120 U / g, product number: S10189, Shanghai Yuanye Bio-Technology Co., Ltd.

[0019] Papain, purity: 800 u / mg, product number: S10011, Shanghai Yuanye Bio-Technology Co., Ltd.

[0020] Example 1

[0021] A chicken prefabricated dish is composed of the following raw materials by mass: 85 parts of pretreated chicken, 10 parts of compound seasoning base, and 5 parts of laccase-catalyzed directional crosslinking preservative.

[0022] The compound seasoning base is composed of the following components by mass percentage: Table salt 11%; Granulated sugar 6%; Soy sauce 10%; Cooking wine 5%; 2% black pepper powder; 5% monosodium glutamate; 4% chili powder; 11% rapeseed oil; The balance is water.

[0023] The preparation method of the laccase-catalyzed directional cross-linking preservative includes the following steps: S1 Raw material pretreatment: Mix bamboo leaf powder and water at a mass ratio of 1:15, treat in a water bath at 80 °C for 30 min, filter through a 0.45 μm filter membrane to obtain a filtrate, and obtain bamboo leaf extract after freeze-drying; Mix whey protein and water at 50 °C at a mass ratio of 3:47, stir at 300 r / min until completely dissolved to obtain a whey protein solution; S2 Construct a cross-linking system: Add the bamboo leaf extract obtained in S1 to the whey protein solution obtained in S1, then add laccase and a 0.1 mol / ml CaCl2 solution, and then place it in a constant temperature magnetic stirrer at 45 °C for 120 min, controlling the dissolved oxygen to be 5 mg / L; S3 Reaction termination and curing: After the reaction in step S2 ends, raise the temperature to 85 °C and maintain it for 10 min to inactivate laccase, and then transfer it to a 4 °C cold storage and let it stand for 12 h to obtain a preservation gel; S4 Post-treatment process: Cut the preservation gel obtained in step S3 into 5 mm³ particles, wash it 3 times with water to remove free calcium ions, then vacuum freeze-dry it to a water content of 4 wt% to obtain a dried preservation gel, and pulverize it through a 100-mesh sieve to obtain the laccase-catalyzed directional cross-linking preservative.

[0024] The bamboo leaf powder described in step S1 is obtained by drying treatment with a water content of 5 wt% and passing through a 100-mesh sieve.

[0025] In the whey protein solution of step S2, the concentration of the bamboo leaf extract is 3 wt%, and the concentration of the CaCl2 solution in the whey protein solution is 15 mmol / ml.

[0026] The addition amount of laccase in step S2 is 50 U / g of whey protein.

[0027] The conditions for vacuum freeze-drying in step S4 are -50 °C and 10 Pa.

[0028] A preparation method of a prefabricated chicken dish includes the following steps: (1) Cut the chicken pieces evenly, then immerse them in 1.5 wt% saline solution, treat them in a 40 kHz / 1 MHz dual-frequency ultrasonic field for 15 min, take them out and drain them after completion to obtain pretreated chicken; (2) Put 85 parts by mass of the pretreated chicken obtained in step (1) into a tumbling machine, add 10 parts of a compound flavor base and 5 parts of a laccase-catalyzed directional cross-linking preservative, set the vacuum degree to -0.09 MPa, the rotation speed to 12 r / min, and the temperature to 4 °C, and tumble for 40 min to obtain flavored chicken; (3) Vacuum package the flavored chicken obtained in step (3), use a special microwave heating packaging bag, and then freeze it to -8 °C to obtain the chicken ready-to-cook dish.

[0029] In the 40 kHz / 1 MHz dual-frequency ultrasonic field treatment in step (1), the low-frequency ultrasonic frequency is 40 kHz, the high-frequency frequency is 1 MHz, the power density is 15 W / cm², the two frequencies alternate, and each frequency is treated for 90 s.

[0030] Example 2

[0031] A chicken ready-to-cook dish is composed of the following raw materials by mass: 85 parts of pretreated chicken, 10 parts of a compound flavor base, and 5 parts of a laccase-catalyzed directional cross-linking preservative.

[0032] The compound flavor base is composed of the following components by mass percentage: Table salt 11%; Granulated sugar 6%; Soy sauce 10%; Cooking wine 5%; Black pepper powder 2%; Monosodium glutamate 5%; Chili powder 4%; Rapeseed oil 11%; The balance is water.

[0033] The preparation method of the laccase-catalyzed directional cross-linking preservative includes the following steps: S1 Raw material pretreatment: Mix the bamboo leaf powder and water at a mass ratio of 1:15, treat it in a water bath at 80 °C for 30 min, filter it through a 0.45 μm filter membrane to obtain a filtrate, and obtain bamboo leaf extract after freeze-drying; Mix whey protein and water at 50 °C at a mass ratio of 3:47, and stir at 300 r / min until completely dissolved to obtain a whey protein solution; S2 Construct a cross-linking system: Add the bamboo leaf extract obtained in S1 to the whey protein solution obtained in S1, then add laccase and a 0.1 mol / ml CaCl2 solution, and then place it in a constant temperature stirring reaction at 45 °C for 120 min, controlling the dissolved oxygen to be 5 mg / L; S3 Reaction termination and curing: After the reaction in step S2 is completed, raise the temperature to 85 °C and maintain it for 10 min to inactivate laccase, and then transfer it to a 4 °C cold storage and let it stand for 12 h to obtain a preservation gel; Post-treatment process S4: The fresh-keeping gel obtained in the cutting step S3 is in the form of 5 mm³ particles, which are rinsed with water three times to remove free calcium ions, and then vacuum freeze-dried until the water content is 4 wt% to obtain the dried fresh-keeping gel. The dried fresh-keeping gel is pulverized and sieved through a 100-mesh sieve to obtain the laccase-catalyzed directional cross-linking fresh-keeping agent.

[0034] The bamboo leaf powder described in step S1 is subjected to a drying treatment, with a water content of 5 wt%, and is obtained by sieving through a 100-mesh sieve.

[0035] In the whey protein solution of step S2, the concentration of the bamboo leaf extract is 3 wt%, and the concentration of the CaCl₂ solution in the whey protein solution is 15 mmol / ml.

[0036] The addition amount of laccase in step S2 is 30 U / g of whey protein.

[0037] The conditions for vacuum freeze-drying in step S4 are -50 °C and 10 Pa.

[0038] A preparation method of a prefabricated chicken dish, comprising the following steps: (1) Cut the chicken pieces evenly, then immerse them in 1.5 wt% salt water, and treat them with a 40 kHz / 1 MHz dual-frequency ultrasonic field for 15 min. After completion, take them out and drain to obtain the pretreated chicken. (2) By mass, put 85 parts of the pretreated chicken obtained in step (1) into a tumbler, add 10 parts of a compound flavoring base and 5 parts of the laccase-catalyzed directional cross-linking fresh-keeping agent, set the vacuum degree to -0.09 MPa, the rotation speed to 12 r / min, and the temperature to 4 °C, and tumble for 40 min to obtain the flavored chicken. (3) Vacuum package the flavored chicken obtained in step (3), use a special microwave heating packaging bag, and then freeze it to -8 °C to obtain the prefabricated chicken dish.

[0039] In the 40 kHz / 1 MHz dual-frequency ultrasonic field treatment described in step (1), the low-frequency ultrasonic frequency is 40 kHz, the high-frequency frequency is 1 MHz, the power density is 15 W / cm², the two frequencies alternate, and each frequency is treated for 90 s.

[0040] Example 3

[0041] A prefabricated chicken dish, by mass, is composed of the following raw materials: 85 parts of pretreated chicken, 10 parts of a compound flavoring base, and 5 parts of the laccase-catalyzed directional cross-linking fresh-keeping agent.

[0042] The compound flavoring base, by mass percentage, is composed of the following components: Table salt 11%; Granulated sugar 6%; Soy sauce 10%; Cooking wine 5%; Black pepper powder 2%; Monosodium glutamate 5%; Chili powder 4%; Rapeseed oil 11%; The balance is water.

[0043] The preparation method of the laccase-catalyzed directional cross-linking preservative includes the following steps: S1 Raw material pretreatment: Mix the Indocalamus leaf powder and water at a mass ratio of 1:15, treat them in a water bath at 80 °C for 30 min, filter through a 0.45 μm filter membrane to obtain a filtrate, and obtain the Indocalamus leaf extract after freeze-drying; Mix the whey protein and water at 50 °C at a mass ratio of 3:47, stir at 300 r / min until completely dissolved to obtain a whey protein solution; S2 Construct a cross-linking system: Add the Indocalamus leaf extract obtained in S1 to the whey protein solution obtained in S1, then add laccase and a 0.1 mol / ml CaCl2 solution, and then place it in a constant temperature magnetic stirrer at 45 °C for 120 min, controlling the dissolved oxygen to be 5 mg / L; S3 Reaction termination and curing: After the reaction in step S2 ends, raise the temperature to 85 °C and maintain it for 10 min to inactivate laccase, and then transfer it to a 4 °C cold storage and let it stand for 12 h to obtain a preservation gel; S4 Post-treatment process: Cut the preservation gel obtained in step S3 into 5 mm³ particles, wash it 3 times with water to remove free calcium ions, and then vacuum freeze-dry it to a water content of 4 wt% to obtain a dried preservation gel, and crush it through a 100-mesh sieve to obtain the laccase-catalyzed directional cross-linking preservative.

[0044] The Indocalamus leaf powder described in step S1 is obtained by drying treatment with a water content of 5 wt% and passing through a 100-mesh sieve.

[0045] In the whey protein solution of step S2, the concentration of the Indocalamus leaf extract is 3 wt%, and the concentration of the CaCl2 solution in the whey protein solution is 15 mmol / ml.

[0046] The addition amount of laccase in step S2 is 70 U / g of whey protein.

[0047] The conditions for vacuum freeze-drying in step S4 are -50 °C and 10 Pa.

[0048] A preparation method of a prefabricated chicken dish includes the following steps: (1) Cut the chicken pieces evenly, then immerse them in 1.5 wt% brine, treat them with a 40 kHz / 1 MHz dual-frequency ultrasonic field for 15 min, take them out and drain them after completion to obtain pretreated chicken; (2) By mass, put 85 parts of the pretreated chicken obtained in step (1) into a tumbling machine, add 10 parts of a compound flavoring base and 5 parts of a laccase-catalyzed directional cross-linking preservative, set the vacuum degree to -0.09 MPa, the rotation speed to 12 r / min, and the temperature to 4 °C, and tumble for 40 min to obtain flavored chicken; (3) Vacuum package the flavored chicken obtained in step (3), use a special microwave heating packaging bag, and then freeze it to -8 °C to obtain the chicken ready-to-eat dish.

[0049] In the 40 kHz / 1 MHz dual-frequency ultrasonic field treatment in step (1), the low-frequency ultrasonic frequency is 40 kHz, the high-frequency frequency is 1 MHz, the power density is 15 W / cm², the two frequencies alternate, and each frequency is treated for 90 s.

[0050] Example 4

[0051] A chicken ready-to-eat dish, by mass, consists of the following raw materials: 85 parts of pretreated chicken, 10 parts of a compound flavoring base, and 5 parts of a laccase-catalyzed directional cross-linking preservative.

[0052] The compound flavoring base, by mass percentage, consists of the following components: Table salt 11%; Granulated sugar 6%; Soy sauce 10%; Cooking wine 5%; Black pepper powder 2%; Monosodium glutamate 5%; Chili powder 4%; Rapeseed oil 11%; The balance is water.

[0053] The preparation method of the laccase-catalyzed directional cross-linking preservative includes the following steps: S1 Raw material pretreatment: Mix the bamboo leaf powder and water at a mass ratio of 1:15, treat it in a water bath at 80 °C for 30 min, filter through a 0.45 μm filter membrane to obtain a filtrate, and obtain bamboo leaf extract after freeze-drying; Mix whey protein and water at 50 °C at a mass ratio of 3:47, and stir at 300 r / min until completely dissolved to obtain a whey protein solution; S2 Construct a cross-linking system: Add the bamboo leaf extract obtained in S1 to the whey protein solution obtained in S1, then add laccase and a 0.1 mol / ml CaCl2 solution, and then place it in a constant temperature stirring reaction at 35 °C for 120 min, controlling the dissolved oxygen to be 5 mg / L; S3 Reaction termination and curing: After the reaction in step S2 ends, raise the temperature to 85 °C and maintain it for 10 min to inactivate laccase, and then transfer it to a 4 °C cold storage and let it stand for 12 h to obtain a preservation gel; S4 Post-treatment process: The fresh-keeping gel obtained in the cutting step S3 is in the form of 5 mm³ particles, which are rinsed with water three times to remove free calcium ions, and then vacuum freeze-dried until the water content is 4 wt%, obtaining the dried fresh-keeping gel. The dried fresh-keeping gel is pulverized and sieved through a 100-mesh sieve to obtain the laccase-catalyzed directional cross-linking fresh-keeping agent.

[0054] The Indocalamus leaf powder described in step S1 is subjected to a drying treatment, with a water content of 5 wt%, and is obtained by sieving through a 100-mesh sieve.

[0055] In the whey protein solution of step S2, the concentration of the Indocalamus leaf extract is 3 wt%, and the concentration of the CaCl2 solution in the whey protein solution is 15 mmol / ml.

[0056] The addition amount of laccase in step S2 is 50 U / g of whey protein.

[0057] The conditions for vacuum freeze-drying in step S4 are -50°C and 10 Pa.

[0058] A preparation method of a prefabricated chicken dish includes the following steps: (1) Cut the chicken pieces evenly, then immerse them in 1.5 wt% saline solution, and treat them with a 40 kHz / 1 MHz dual-frequency ultrasonic field for 15 min. After that, take them out and drain, obtaining the pretreated chicken. (2) By mass, put 85 parts of the pretreated chicken obtained in step (1) into a tumbler, add 10 parts of a compound flavoring base and 5 parts of the laccase-catalyzed directional cross-linking fresh-keeping agent. Set the vacuum degree to -0.09 MPa, the rotation speed to 12 r / min, and the temperature to 4°C, and tumble for 40 min to obtain the flavored chicken. (3) Vacuum package the flavored chicken obtained in step (3), use a special microwave heating packaging bag, and then freeze it to -8°C to obtain the prefabricated chicken dish.

[0059] In the 40 kHz / 1 MHz dual-frequency ultrasonic field treatment described in step (1), the low-frequency ultrasonic frequency is 40 kHz, the high-frequency frequency is 1 MHz, the power density is 15 W / cm², the two frequencies alternate, and each frequency is treated for 90 s.

[0060] Example 5

[0061] A prefabricated chicken dish, by mass, is composed of the following raw materials: 85 parts of pretreated chicken, 10 parts of a compound flavoring base, and 5 parts of the laccase-catalyzed directional cross-linking fresh-keeping agent.

[0062] The compound flavoring base, by mass percentage, is composed of the following components: Table salt 11%; Granulated sugar 6%; Soy sauce 10%; Cooking wine 5%; Black pepper powder 2%; Monosodium glutamate 5%; Chili powder 4%; Rapeseed oil 11%; The balance is water.

[0063] The preparation method of the laccase-catalyzed directional cross-linking preservative comprises the following steps: S1 Raw material pretreatment: Mix the bamboo leaf powder and water at a mass ratio of 1:15, dissolve in a water bath at 80°C for 30 min, filter through a 0.45-μm filter membrane to obtain a filtrate, and obtain bamboo leaf extract after freeze-drying; Mix whey protein and water at 50°C at a mass ratio of 3:47, stir at 300 r / min until completely dissolved to obtain a whey protein solution; S2 Construct a cross-linking system: Add the bamboo leaf extract obtained in S1 to the whey protein solution obtained in S1, then add laccase and a 0.1 mol / ml CaCl2 solution, and then place it in a constant temperature magnetic stirrer at 55°C for 120 min, controlling the dissolved oxygen to be 5 mg / L; S3 Reaction termination and curing: After the reaction in step S2 is completed, raise the temperature to 85°C and maintain for 10 min to inactivate laccase, and then transfer it to a 4°C cold storage and let it stand for 12 h to obtain a preservation gel; S4 Post-treatment process: Cut the preservation gel obtained in step S3 into 5 mm³ particles, wash with water 3 times to remove free calcium ions, and then vacuum freeze-dry to a water content of 4 wt% to obtain a dry preservation gel, which is pulverized and passed through a 100-mesh sieve to obtain the laccase-catalyzed directional cross-linking preservative.

[0064] The bamboo leaf powder described in step S1 is obtained by drying treatment with a water content of 5 wt% and passing through a 100-mesh sieve.

[0065] In the whey protein solution of step S2, the concentration of the bamboo leaf extract is 3 wt%, and the concentration of the CaCl2 solution in the whey protein solution is 15 mmol / ml.

[0066] The addition amount of laccase in step S2 is 50 U / g of whey protein.

[0067] The conditions for vacuum freeze-drying in step S4 are -50°C and 10 Pa.

[0068] A preparation method of a prefabricated chicken dish comprises the following steps: (1) Cut the chicken pieces evenly, then immerse them in 1.5 wt% salt water, treat them with a 40 kHz / 1 MHz dual-frequency ultrasonic field for 15 min, take them out and drain them after completion to obtain pretreated chicken; (2) Put 85 parts by mass of the pretreated chicken obtained in step (1) into a tumbler, add 10 parts of a compound flavoring base and 5 parts of a laccase-catalyzed directional cross-linking preservative, set the vacuum degree to -0.09 MPa, the rotation speed to 12 r / min, and the temperature to 4 °C, and tumble for 40 min to obtain flavored chicken; (3) Vacuum package the flavored chicken obtained in step (3), use a special microwave heating packaging bag, and then freeze it to -8 °C to obtain the chicken ready-to-eat dish.

[0069] In the 40 kHz / 1 MHz dual-frequency ultrasonic field treatment in step (1), the low-frequency ultrasonic frequency is 40 kHz, the high-frequency frequency is 1 MHz, the power density is 15 W / cm², the two frequencies alternate, and each frequency is treated for 90 s.

[0070] Example 6

[0071] A chicken ready-to-eat dish is composed of the following raw materials by mass: 85 parts of pretreated chicken, 10 parts of a compound flavoring base, and 5 parts of a laccase-catalyzed directional cross-linking preservative.

[0072] The compound flavoring base is composed of the following components by mass percentage: Table salt 11%; Granulated sugar 6%; Soy sauce 10%; Cooking wine 5%; Black pepper powder 2%; Monosodium glutamate 5%; Chili powder 4%; Rapeseed oil 11%; The balance is water.

[0073] The preparation method of the laccase-catalyzed directional cross-linking preservative includes the following steps: S1 Raw material pretreatment: Mix the bamboo leaf powder and water according to a mass ratio of 1:15, perform a water bath treatment at 80 °C for 30 min, filter through a 0.45 μm filter membrane to obtain a filtrate, and obtain a bamboo leaf extract after freeze-drying; Mix whey protein and water at 50 °C according to a mass ratio of 3:47, and stir at 300 r / min until completely dissolved to obtain a whey protein solution; S2 Construct a cross-linking system: Add the bamboo leaf extract obtained in S1 to the whey protein solution obtained in S1, then add laccase and a 0.1 mol / ml CaCl2 solution, and then place it in a constant temperature stirring reaction at 45 °C for 120 min, controlling the dissolved oxygen to be 5 mg / L; S3 Reaction termination and curing: After the reaction in step S2 ends, raise the temperature to 85 °C and maintain it for 10 min to inactivate laccase, and then transfer it to a 4 °C cold storage and let it stand for 12 h to obtain a preservation gel; S4 Post-treatment process: The fresh-keeping gel obtained in the cutting step S3 is in the form of 5 mm³ particles, which are rinsed with water three times to remove free calcium ions, and then vacuum freeze-dried until the water content is 4 wt% to obtain the dried fresh-keeping gel. The dried fresh-keeping gel is pulverized and sieved through a 100-mesh sieve to obtain the laccase-catalyzed directional cross-linking fresh-keeping agent.

[0074] The bamboo leaf powder described in step S1 is subjected to a drying treatment, with a water content of 5 wt%, and is obtained by sieving through a 100-mesh sieve.

[0075] In the whey protein solution of step S2, the concentration of the bamboo leaf extract is 1 wt%, and the concentration of the CaCl₂ solution in the whey protein solution is 15 mmol / ml.

[0076] The addition amount of laccase in step S2 is 50 U / g of whey protein.

[0077] The conditions for vacuum freeze-drying in step S4 are -50 °C and 10 Pa.

[0078] A preparation method of a prefabricated chicken dish includes the following steps: (1) Cut the chicken pieces evenly, then immerse them in 1.5 wt% brine, and treat them with a 40 kHz / 1 MHz dual-frequency ultrasonic field for 15 min. After that, take them out and drain to obtain the pretreated chicken. (2) By mass, put 85 parts of the pretreated chicken obtained in step (1) into a tumbler, add 10 parts of a composite flavoring base and 5 parts of the laccase-catalyzed directional cross-linking fresh-keeping agent, set the vacuum degree to -0.09 MPa, the rotation speed to 12 r / min, and the temperature to 4 °C, and tumble for 40 min to obtain the flavored chicken. (3) Vacuum package the flavored chicken obtained in step (3), use a special microwave heating packaging bag, and then freeze it to -8 °C to obtain the prefabricated chicken dish.

[0079] In the 40 kHz / 1 MHz dual-frequency ultrasonic field treatment described in step (1), the low-frequency ultrasonic frequency is 40 kHz, the high-frequency frequency is 1 MHz, the power density is 15 W / cm², the two frequencies alternate, and each frequency is treated for 90 s.

[0080] Example 7

[0081] A prefabricated chicken dish, by mass, consists of the following raw materials: 85 parts of pretreated chicken, 10 parts of a composite flavoring base, and 5 parts of the laccase-catalyzed directional cross-linking fresh-keeping agent.

[0082] The composite flavoring base, by mass percentage, consists of the following components: Table salt 11%; Granulated sugar 6%; Soy sauce 10%; Cooking wine 5%; Black pepper powder 2%; Monosodium glutamate 5%; Chili powder 4%; Rapeseed oil 11%; The balance is water.

[0083] The preparation method of the laccase-catalyzed directional cross-linking preservative comprises the following steps: S1 Raw material pretreatment: Mix the bamboo leaf powder and water according to a mass ratio of 1:15, treat them in a water bath at 80 °C for 30 min, filter through a 0.45 μm filter membrane to obtain a filtrate, and obtain bamboo leaf extract after freeze-drying; Mix whey protein and water at 50 °C according to a mass ratio of 3:47, stir at 300 r / min until completely dissolved to obtain a whey protein solution; S2 Construct a cross-linking system: Add the bamboo leaf extract obtained in S1 to the whey protein solution obtained in S1, then add laccase and a 0.1 mol / ml CaCl2 solution, and then place it in a constant temperature magnetic stirrer at 45 °C for reaction for 120 min, controlling the dissolved oxygen to be 5 mg / L; S3 Reaction termination and curing: After the reaction in step S2 ends, raise the temperature to 85 °C and maintain it for 10 min to inactivate laccase, and then transfer it to a 4 °C cold storage and let it stand for 12 h to obtain a preservation gel; S4 Post-treatment process: Cut the preservation gel obtained in step S3 into 5 mm³ particles, wash it 3 times with water to remove free calcium ions, and then vacuum freeze-dry it to a water content of 4 wt% to obtain a dried preservation gel, and pulverize it through a 100-mesh sieve to obtain the laccase-catalyzed directional cross-linking preservative.

[0084] The bamboo leaf powder described in step S1 is obtained by drying treatment, with a water content of 5 wt% and passing through a 100-mesh sieve.

[0085] In the whey protein solution of step S2, the concentration of the bamboo leaf extract is 5 wt%, and the concentration of the CaCl2 solution in the whey protein solution is 15 mmol / ml.

[0086] The addition amount of laccase in step S2 is 50 U / g of whey protein.

[0087] The conditions for vacuum freeze-drying in step S4 are -50 °C and 10 Pa.

[0088] A preparation method of a prefabricated chicken dish comprises the following steps: (1) Cut the chicken pieces evenly, then immerse them in 1.5 wt% brine, treat them with a 40 kHz / 1 MHz dual-frequency ultrasonic field for 15 min, take them out and drain them after completion to obtain pretreated chicken; (2) Put 85 parts by mass of the pretreated chicken obtained in step (1) into a tumbler, add 10 parts of a compound flavor base and 5 parts of a laccase-catalyzed directional cross-linking preservative, set the vacuum degree to -0.09 MPa, the rotation speed to 12 r / min, and the temperature to 4 °C, and tumble for 40 min to obtain flavored chicken; (3) Vacuum package the flavored chicken obtained in step (3), use a special microwave heating packaging bag, and then freeze it to -8 °C to obtain the chicken ready-to-cook dish.

[0089] In the 40 kHz / 1 MHz dual-frequency ultrasonic field treatment in step (1), the low-frequency ultrasonic frequency is 40 kHz, the high-frequency frequency is 1 MHz, the power density is 15 W / cm², the two frequencies alternate, and each frequency is treated for 90 s.

[0090] Example 8

[0091] A chicken ready-to-cook dish is composed of the following raw materials by mass: 85 parts of pretreated chicken, 10 parts of a compound flavor base, and 5 parts of a laccase-catalyzed directional cross-linking preservative.

[0092] The compound flavor base is composed of the following components by mass percentage: Table salt 11%; Granulated sugar 6%; Soy sauce 10%; Cooking wine 5%; Black pepper powder 2%; Monosodium glutamate 5%; Chili powder 4%; Rapeseed oil 11%; The balance is water.

[0093] The preparation method of the laccase-catalyzed directional cross-linking preservative includes the following steps: S1 Raw material pretreatment: Mix bamboo leaf powder and water at a mass ratio of 1:15, treat it in a water bath at 80 °C for 30 min, filter through a 0.45 μm filter membrane to obtain a filtrate, and obtain bamboo leaf extract after freeze-drying; Mix whey protein and water at 50 °C at a mass ratio of 3:47, and stir at 300 r / min until completely dissolved to obtain a whey protein solution; S2 Construct a cross-linking system: Add the bamboo leaf extract obtained in S1 to the whey protein solution obtained in S1, then add laccase and a 0.1 mol / ml CaCl2 solution, and then place it in a constant temperature magnetic stirrer at 45 °C for 120 min, controlling the dissolved oxygen to be 5 mg / L; S3 Reaction termination and curing: After the reaction in step S2 ends, raise the temperature to 85 °C and maintain it for 10 min to inactivate laccase, and then transfer it to a 4 °C cold storage and let it stand for 12 h to obtain a preservation gel; Post-treatment process S4: The fresh-keeping gel obtained in the cutting step S3 is in the form of 5 mm³ particles, which are rinsed with water three times to remove free calcium ions, and then vacuum freeze-dried until the water content is 4 wt% to obtain the dried fresh-keeping gel. The dried fresh-keeping gel is pulverized and sieved through a 100-mesh sieve to obtain the laccase-catalyzed directional cross-linking fresh-keeping agent.

[0094] The bamboo leaf powder described in step S1 is subjected to a drying treatment, with a water content of 5 wt%, and is obtained by sieving through a 100-mesh sieve.

[0095] In the whey protein solution of step S2, the concentration of the bamboo leaf extract is 3 wt%, and the concentration of the CaCl2 solution in the whey protein solution is 15 mmol / ml.

[0096] The addition amount of laccase in step S2 is 50 U / g of whey protein.

[0097] The conditions for vacuum freeze-drying in step S4 are -50 °C and 10 Pa.

[0098] A preparation method of a chicken ready-to-cook dish, comprising the following steps: (1) Cut the chicken pieces evenly, then immerse them in 1.5 wt% brine, and treat them with a 40 kHz ultrasonic field for 15 min. After that, take them out and drain to obtain the pretreated chicken. (2) By mass, put 85 parts of the pretreated chicken obtained in step (1) into a tumbler, add 10 parts of a compound flavoring base and 5 parts of the laccase-catalyzed directional cross-linking fresh-keeping agent, set the vacuum degree to -0.09 MPa, the rotation speed to 12 r / min, and the temperature to 4 °C, and tumble for 40 min to obtain the flavored chicken. (3) Vacuum package the flavored chicken obtained in step (3), use a special microwave heating packaging bag, and then freeze it to -8 °C to obtain the chicken ready-to-cook dish.

[0099] In the 40 kHz ultrasonic field treatment described in step (1), the power density is 15 W / cm².

[0100] Example 9

[0101] A chicken ready-to-cook dish, by mass, consists of the following raw materials: 85 parts of pretreated chicken, 10 parts of a compound flavoring base, and 5 parts of the laccase-catalyzed directional cross-linking fresh-keeping agent.

[0102] The compound flavoring base, by mass percentage, consists of the following components: Table salt 11%; White granulated sugar 6%; Soy sauce 10%; Cooking wine 5%; Black pepper powder 2%; Monosodium glutamate 5%; Chili powder 4%; 11% rapeseed oil; The balance is water.

[0103] The preparation method of the laccase-catalyzed directional cross-linking preservative includes the following steps: S1 Raw material pretreatment: Mix the Indocalamus leaf powder and water at a mass ratio of 1:15, treat them in a water bath at 80°C for 30 min, filter through a 0.45 μm filter membrane to obtain a filtrate, and obtain the Indocalamus leaf extract after freeze-drying; Mix whey protein and water at 50°C at a mass ratio of 3:47, stir at 300 r / min until completely dissolved to obtain a whey protein solution; S2 Construct a cross-linking system: Add the Indocalamus leaf extract obtained in S1 to the whey protein solution obtained in S1, then add laccase and a 0.1 mol / ml CaCl2 solution, and then place it in a constant temperature magnetic stirrer at 45°C for 120 min, controlling the dissolved oxygen to be 5 mg / L; S3 Reaction termination and curing: After the reaction in step S2 ends, raise the temperature to 85°C and maintain it for 10 min to inactivate laccase, and then transfer it to a 4°C cold storage and let it stand for 12 h to obtain a preservation gel; S4 Post-treatment process: Cut the preservation gel obtained in step S3 into 5 mm³ particles, wash it 3 times with water to remove free calcium ions, and then vacuum freeze-dry it to a water content of 4 wt% to obtain a dried preservation gel, and crush it through a 100-mesh sieve to obtain the laccase-catalyzed directional cross-linking preservative.

[0104] The Indocalamus leaf powder described in step S1 is obtained by drying treatment, with a water content of 5 wt%, and passing through a 100-mesh sieve.

[0105] In the whey protein solution in step S2, the concentration of the Indocalamus leaf extract is 3 wt%, and the concentration of the CaCl2 solution in the whey protein solution is 15 mmol / ml.

[0106] The addition amount of laccase in step S2 is 50 U / g of whey protein.

[0107] The conditions for vacuum freeze-drying in step S4 are -50°C and 10 Pa.

[0108] A preparation method of a prefabricated chicken dish includes the following steps: (1) Cut the chicken pieces evenly, then immerse them in 1.5 wt% brine, treat them with a 1 MHz ultrasonic field for 15 min, and take them out and drain after completion to obtain pretreated chicken; (2) By mass, put 85 parts of the pretreated chicken obtained in step (1) into a tumbler, add 10 parts of a compound flavoring base material and 5 parts of the laccase-catalyzed directional cross-linking preservative, set the vacuum degree to -0.09 MPa, the rotation speed to 12 r / min, and the temperature to 4°C, and tumble for 40 min to obtain flavored chicken; (3) Vacuum package the seasoned chicken obtained in step (3) using a special microwave heating packaging bag, and then freeze it to -8°C to obtain the chicken ready-to-cook food.

[0109] In the 1 MHz ultrasonic field treatment in step (1), the power density is 15 W / cm².

[0110] Comparative Example 1

[0111] A chicken ready-to-cook food is composed of the following raw materials by mass: 85 parts of pretreated chicken, 10 parts of compound seasoning base, and 5 parts of preservative.

[0112] The compound seasoning base is composed of the following components by mass percentage: Table salt 11%; White granulated sugar 6%; Soy sauce 10%; Cooking wine 5%; Black pepper powder 2%; Monosodium glutamate 5%; Chili powder 4%; Rapeseed oil 11%; The balance is water.

[0113] The preparation method of the preservative includes the following steps: S1 Raw material pretreatment: Mix the Indocalamus leaf powder and water at a mass ratio of 1:15, treat it in a water bath at 80°C for 30 min, filter through a 0.45 μm filter membrane to obtain a filtrate, and obtain the Indocalamus leaf extract after freeze-drying; Mix whey protein and water at 50°C at a mass ratio of 3:47, and stir at 300 r / min until completely dissolved to obtain a whey protein solution; S2 Construct a cross-linking system: Add the Indocalamus leaf extract obtained in S1 to the whey protein solution obtained in S1, then add papain and a 0.1 mol / ml CaCl₂ solution, and then place it in a constant temperature and stir at 45°C for 120 min, controlling the dissolved oxygen to be 5 mg / L; S3 Reaction termination and curing: After the reaction in step S2 ends, raise the temperature to 85°C and maintain it for 10 min to inactivate laccase, and then transfer it to a 4°C cold storage and let it stand for 12 h to obtain a preservation gel; S4 Post-treatment process: Cut the preservation gel obtained in step S3 into 5 mm³ particles, wash it 3 times with water to remove free calcium ions, and then vacuum freeze-dry it to a water content of 4 wt% to obtain a dried preservation gel, and pulverize it through a 100-mesh sieve to obtain the preservative.

[0114] In the whey protein solution in step S2, the concentration of the Indocalamus leaf extract is 3 wt%, and the concentration of the CaCl₂ solution in the whey protein solution is 15 mmol / ml.

[0115] The Indocalamus leaf powder described in step S1 is dried to a water content of 5 wt% and sieved through a 100-mesh sieve to obtain it.

[0116] In step S2, the addition amount of papain is 50 U / g of whey protein.

[0117] In step S4, the conditions for vacuum freeze-drying are -50 °C and 10 Pa.

[0118] A preparation method of a chicken ready-to-eat dish includes the following steps: (1) Cut the chicken pieces evenly, then immerse them in 1.5 wt% brine, and treat them with a 40 kHz / 1 MHz dual-frequency ultrasonic field for 15 min. After that, take them out and drain to obtain pretreated chicken. (2) By mass, put 85 parts of the pretreated chicken obtained in step (1) into a tumbler, add 10 parts of a compound flavoring base and 5 parts of a preservative. Set the vacuum degree to -0.09 MPa, the rotation speed to 12 r / min, and the temperature to 4 °C, and tumble for 40 min to obtain flavored chicken. (3) Vacuum package the flavored chicken obtained in step (3) using a special microwave heating packaging bag, and then freeze it to -8 °C to obtain the chicken ready-to-eat dish.

[0119] In the 40 kHz / 1 MHz dual-frequency ultrasonic field treatment described in step (1), the low-frequency ultrasonic frequency is 40 kHz, the high-frequency is 1 MHz, the power density is 15 W / cm², the two frequencies alternate, and each frequency is treated for 90 s.

[0120] Comparative Example 2

[0121] A chicken ready-to-eat dish, by mass, consists of the following raw materials: 85 parts of pretreated chicken, 10 parts of a compound flavoring base, and 5 parts of a laccase-catalyzed directional cross-linking preservative.

[0122] The compound flavoring base, by mass percentage, consists of the following components: Table salt 11%; White granulated sugar 6%; Soy sauce 10%; Cooking wine 5%; Black pepper powder 2%; Monosodium glutamate 5%; Chili powder 4%; Rapeseed oil 11%; The balance is water.

[0123] The preparation method of the laccase-catalyzed directional cross-linking preservative includes the following steps: S1 Raw material pretreatment: Mix whey protein and water at 50 °C in a mass ratio of 3:47, and stir at 300 r / min until completely dissolved to obtain a whey protein solution. S2 Construct a cross-linking system: Add laccase and 0.1 mol / ml CaCl2 solution to the whey protein solution obtained in S1, then place it in a constant temperature magnetic stirrer at 45 °C for 120 min, and control the dissolved oxygen to 5 mg / L; S3 Reaction termination and curing: After the reaction in step S2 is completed, raise the temperature to 85 °C and maintain it for 10 min to inactivate laccase, then transfer it to a 4 °C cold storage and let it stand for 12 h to obtain a fresh-keeping gel; S4 Post-treatment process: Cut the fresh-keeping gel obtained in step S3 into 5 mm³ particles, wash it 3 times with water to remove free calcium ions, then vacuum freeze-dry it to a water content of 4 wt%, obtain a dried fresh-keeping gel, and crush it through a 100-mesh sieve to obtain the laccase-catalyzed directional cross-linked fresh-keeping agent.

[0124] The concentration of the CaCl2 solution in the whey protein solution in step S2 is 15 mmol / ml.

[0125] The addition amount of laccase in step S2 is 50 U / g of whey protein.

[0126] The conditions for vacuum freeze-drying in step S4 are -50 °C and 10 Pa.

[0127] A preparation method of a prefabricated chicken dish, comprising the following steps: (1) Cut the chicken pieces evenly, then immerse them in 1.5 wt% salt water, and treat them with a 40 kHz / 1 MHz dual-frequency ultrasonic field for 15 min. After that, take them out and drain them to obtain pretreated chicken; (2) By mass, put 85 parts of the pretreated chicken obtained in step (1) into a tumbler, add 10 parts of a compound flavoring base material and 5 parts of the laccase-catalyzed directional cross-linked fresh-keeping agent, set the vacuum degree to -0.09 MPa, the rotation speed to 12 r / min, and the temperature to 4 °C, and tumble for 40 min to obtain flavored chicken; (3) Vacuum package the flavored chicken obtained in step (3), use a special microwave heating packaging bag, and then freeze it to -8 °C to obtain the prefabricated chicken dish.

[0128] In the 40 kHz / 1 MHz dual-frequency ultrasonic field treatment in step (1), the low-frequency ultrasonic frequency is 40 kHz, the high-frequency frequency is 1 MHz, the power density is 15 W / cm², the two frequencies alternate, and each frequency is treated for 90 s.

[0129] Comparative Example 3

[0130] A prefabricated chicken dish, by mass, consists of the following raw materials: 85 parts of pretreated chicken, 10 parts of a compound flavoring base material, and 0.1 part of potassium sorbate.

[0131] The compound flavoring base material, by mass percentage, consists of the following components: 11% table salt; 6% granulated sugar; 10% soy sauce; 5% cooking wine; 2% black pepper powder; 5% monosodium glutamate; 4% chili powder; 11% rapeseed oil; The balance is water.

[0132] A preparation method of a prefabricated chicken dish, comprising the following steps: (1) Cut the chicken pieces evenly, then immerse them in 1.5 wt% saline solution, and treat them with a 40 kHz / 1 MHz dual-frequency ultrasonic field for 15 min. After that, take them out and drain, to obtain pretreated chicken; (2) By mass, put 85 parts of the pretreated chicken obtained in step (1) into a tumbling machine, add 10 parts of a compound flavor base and 0.1 part of potassium sorbate, set the vacuum degree to -0.09 MPa, the rotation speed to 12 r / min, and the temperature to 4 °C, and tumble for 40 min, to obtain flavored chicken; (3) Vacuum package the flavored chicken obtained in step (3), use a special microwave heating packaging bag, and then freeze it to -8 °C, to obtain the prefabricated chicken dish.

[0133] In the 40 kHz / 1 MHz dual-frequency ultrasonic field treatment in step (1), the low-frequency ultrasonic frequency is 40 kHz, the high-frequency is 1 MHz, the power density is 15 W / cm², the two frequencies alternate, and each frequency is treated for 90 s.

[0134] Comparative Example 4

[0135] A prefabricated chicken dish, by mass, consists of the following raw materials: 85 parts of pretreated chicken, 10 parts of a compound flavor base, and 5 parts of a laccase-catalyzed directional cross-linking preservative.

[0136] The compound flavor base, by mass percentage, consists of the following components: 11% table salt; 6% granulated sugar; 10% soy sauce; 5% cooking wine; 2% black pepper powder; 5% monosodium glutamate; 4% chili powder; 11% rapeseed oil; The balance is water.

[0137] The preparation method of the laccase-catalyzed directional cross-linking preservative comprises the following steps: S1 Raw material pretreatment: Indocalamus leaf powder and water were mixed in a mass ratio of 1:15, treated in a water bath at 80°C for 30 min, filtered through a 0.45 μm filter membrane to obtain a filtrate, and freeze-dried to obtain an Indocalamus leaf extract; whey protein and 50°C water were mixed in a mass ratio of 3:47, stirred at 300 r / min until completely dissolved, to obtain a whey protein solution; S2: constructing a cross-linking system: adding the indigo leaf extract obtained in S1 to the whey protein solution obtained in S1, and then adding laccase and 0.1 mol / ml CaCl2 solution, and then placing the mixture under constant temperature stirring at 45°C for 120 min, and controlling the dissolved oxygen to 5 mg / L; S3 Reaction termination and curing: After the reaction of step S2 is completed, the temperature is raised to 85°C and maintained for 10 minutes to inactivate laccase, and then transferred to a 4°C cold storage and allowed to stand for 12 hours to obtain a fresh-keeping gel; S4 post-processing process: the fresh-keeping gel obtained in step S3 is cut into 5 mm³ particles, washed with water three times to remove free calcium ions, and then vacuum-freeze-dried to a water content of 4 wt % to obtain a dry fresh-keeping gel, which is crushed through a 100-mesh sieve to obtain the laccase-catalyzed directional cross-linking preservative.

[0138] The concentration of the Indocalamus leaf extract in the whey protein solution of step S2 is 3 wt %, and the concentration of the CaCl 2 solution in the whey protein solution is 15 mmol / ml.

[0139] In step S1, the indocalamus leaf powder is dried to have a water content of 5 wt % and is sieved through a 100-mesh sieve.

[0140] The amount of laccase added in step S2 is 50 U / g whey protein.

[0141] The conditions for vacuum freeze drying in step S4 are -50°C and 10Pa.

[0142] A method for preparing a pre-prepared chicken dish comprises the following steps: (1) Cut the chicken pieces into even pieces, and then soak them in 1.5 wt% salt water for 15 min. After soaking, take them out and drain them to obtain pretreated chicken; (2) Put 85 parts of the pretreated chicken obtained in step (1) into a tumbling machine, add 10 parts of a composite seasoning base and 5 parts of a laccase-catalyzed directional cross-linking preservative, set the vacuum degree to -0.09 MPa, the speed to 12 r / min, and the temperature to 4°C, and tumble for 40 minutes to obtain seasoned chicken; (3) The seasoned chicken obtained in step (3) is vacuum packaged, heated in a special packaging bag using a microwave, and then frozen to -8°C to obtain the chicken pre-cooked dish.

[0143] In the 40 kHz / 1 MHz dual-frequency ultrasonic field treatment described in step (1), the low-frequency ultrasonic frequency is 40 kHz, the high-frequency frequency is 1 MHz, the power density is 15 W / cm², the two frequencies alternate, and each frequency is treated for 90 s.

[0144] Test Example 1

[0145] Refer to GB 5009.3-2016 "National Food Safety Standard - Determination of Moisture in Foods" to determine the water retention performance of the prefabricated chicken dishes obtained in each example and comparative example. Take 100 grams of the prefabricated chicken dish sample, ensure uniform cutting, remove the surface free water with absorbent paper, and weigh it (denoted as W1). Place the sample in a microwave oven and heat it at 800 W for 3 min. After heating, let it stand for 1 min to facilitate uniform distribution of heat. After cooling, gently blot the surface moisture with absorbent paper and weigh it (denoted as W2).

[0146] Calculate the water retention rate: Water retention rate (%) = ; The results are shown in Table 1.

[0147] Table 1: Results of Water Retention Performance Determination

[0148] Test Example 2

[0149] Refer to GB 4789.2-2022 "National Food Safety Standard - Food Microbiology Examination - Determination of Total Colonies" to detect the total number of colonies on the 7th and 14th days under the condition of refrigeration at 4°C. The results are shown in Table 2.

[0150] Table 2: Results of Storage Effect Detection

[0151] Test Example 3 Refer to GB / T 12311-2008 "Sensory Analysis - Methodology - General Guidance" to evaluate the taste of the prefabricated chicken dishes after microwave heating. The results are shown in Table 3.

[0152] Table 3: Sensory Evaluation

[0153] It can be seen from the test results in Table 1, Table 2, and Table 3 that through the synergistic regulation of the laccase-indocalamus leaf cross-linking system and dual-frequency ultrasound, the present invention has achieved a breakthrough improvement in the water retention, antibacterial property, and sensory quality of prefabricated chicken dishes.

[0154] As can be seen from Table 1, the water retention rate of the chicken pre-prepared dish prepared in the embodiment is up to 93.5%, which is significantly better than 77.8% of the comparative example. The reason is that laccase catalyzes the directional cross-linking of whey protein and indigo leaf extract to form a gel with excellent water retention performance. The water retention rate of Examples 2-5 in Table 1 is reduced by 3.3-11.7% compared with that of Example 1. By comparing Example 1 with Example 2-5, it can be seen that the laccase concentration of 50U / g whey protein and the cross-linking temperature of 45°C make the water retention performance of the gel reach the optimal level, while the papain used in the traditional enzymatic method or the potassium sorbate chemical preservation used in Comparative Example 1 reduces its water retention rate by 30-40%; the dual-frequency ultrasound used in Example 1 destroys the cell membrane through the synergistic effect of 40kHz low frequency + 1MHz high frequency to promote the penetration of small molecules, so that the laccase catalyzed directional cross-linking preservative can better invade the chicken, and its water retention rate is significantly better than the single-frequency ultrasound of Examples 8-9 and the unsonicated comparative example 4.

[0155] As can be seen from Table 2, the total number of bacterial colonies in Example 1 after 14 days of refrigeration is 3.8×10 4 The results show that the colony count of Example 2 without Indocalamus increased by 23 times compared with that of Example 1; Example 1 adopts dual-frequency ultrasonic pretreatment, and the laccase-catalyzed directional cross-linking preservative is evenly dispersed, so that the preservative can better penetrate into the chicken, and the colony count is reduced by 97% compared with that of Example 4 without ultrasonic, which breaks through the limitation of traditional preservatives relying on chemical inhibition.

[0156] As can be seen from Table 3, the odor masking score (8.8 points) and saltiness uniformity (9.5 points) of Example 1 meet the commercial requirements, which is attributed to the entrapment and adsorption of fishy molecules by the laccase cross-linking network and the deep penetration of the seasoning base driven by dual-frequency ultrasound. The score of Comparative Example 4 was reduced by 38% without ultrasound. More importantly, the setting of the 3wt% indocalamus leaf extract concentration balances the polyphenol cross-linking efficiency and flavor interference (Examples 6-7 have residual fishy smell or bitterness after changing the concentration of indocalamus leaf extract, and the optimization of the laccase catalysis temperature of 45°C avoids protein denaturation caused by high temperature. The dryness score of Example 5 is reduced by 22% compared with Example 1.

[0157] In the prior art, laccase is mostly used for lignin modification. However, the present invention creatively discovers that its catalysis of the cross-linking of whey protein and bamboo leaf polyphenols can simultaneously improve the water retention, antibacterial, and flavor regulation properties, and this effect cannot be replaced by other enzymes such as papain; a laccase concentration of 50 U / g of whey protein, a cross-linking temperature of 45 °C, and an addition amount of 3 wt% of bamboo leaf extract are the best choices for improving the water retention, antibacterial, and flavor regulation properties; finally, the present invention uses dual-frequency ultrasonic pretreatment to achieve a dynamic balance of "deep penetration - surface tenderization" through frequency alternation. Compared with single frequency or traditional soaking, it can better synergistically catalyze the directional cross-linking preservative with laccase, playing a role in water retention, antibacterial, and flavor regulation.

[0158] In summary, through the synergistic regulation of the laccase - bamboo leaf cross-linking system and dual-frequency ultrasound, the present invention breaks through the technical bottleneck that it is difficult to balance "water retention - antibacterial - flavor" in traditional preservation technologies, providing a new solution for the quality upgrade of prefabricated dishes.

Claims

1. A pre-cooked chicken dish, characterized in that: The raw materials are as follows, calculated by weight: 85-90 parts of pretreated chicken, 6-10 parts of compound seasoning base, and 3-6 parts of laccase-catalyzed directional cross-linking preservative.

2. The chicken pre-cooked dish according to claim 1, characterized in that: The composite seasoning base material is composed of the following components by mass percentage: Salt 10-12%; White sugar 5-7%; Soy sauce 8-12%; Cooking wine 4-6%; Black pepper 1-3%; MSG 4-6%; Chili powder 3-5%; Rapeseed oil 10-12%; The balance is water.

3. The chicken pre-cooked dish according to claim 1, characterized in that: The preparation method of the laccase-catalyzed directional cross-linking preservative comprises the following steps: S1 Raw material pretreatment: Mix the indigo leaf powder and water in a mass ratio of 1: (14-16), treat in a water bath at 79-81°C for 25-35min, filter through a 0.4-0.5μm filter membrane to obtain the filtrate, and freeze-dry to obtain the indigo leaf extract; mix whey protein and 45-55°C water in a mass ratio of 3: (46-48), stir at 200-300r / min until completely dissolved, and obtain the whey protein solution; S2 constructing a cross-linking system: adding the indigo leaf extract obtained in S1 to the whey protein solution obtained in S1, then adding laccase and 0.05-0.15 mol / ml CaCl2 solution, and then placing at 40-50°C for constant temperature stirring for 110-130 min, and controlling the dissolved oxygen to 4-6 mg / L; S3 Reaction termination and curing: After the reaction of step S2 is completed, the temperature is raised to 80-90°C and maintained for 8-12 minutes to inactivate laccase, and then transferred to a 0-4°C cold storage and allowed to stand for 10-14 hours to obtain a fresh-keeping gel; S4 post-processing process: the fresh-keeping gel obtained in step S3 is cut into 3-7 mm³ particles, washed with water 2-3 times to remove free calcium ions, and then vacuum-freeze-dried to a water content of 1wt%-5wt% to obtain a dry fresh-keeping gel, which is crushed through a 90-120 mesh sieve to obtain the laccase-catalyzed directional cross-linking preservative.

4. The chicken pre-cooked dish as claimed in claim 3, characterized in that: In step S1, the indocalamus leaf powder is dried to have a water content of 1wt%-7wt% and is sieved through a 90-120 mesh sieve.

5. The chicken pre-cooked dish as claimed in claim 3, characterized in that: The concentration of the Indocalamus leaf extract in the whey protein solution of step S2 is 2-4wt%, and the concentration of the CaCl2 solution in the whey protein solution is 15mmol / ml.

6. The chicken pre-cooked dish as claimed in claim 3, characterized in that: The amount of laccase added in step S2 is 40-60 U / g whey protein.

7. The chicken pre-cooked dish according to claim 3, characterized in that: The conditions for vacuum freeze drying in step S4 are -50-(-40)°C and 9-11Pa.

8. A method for preparing the pre-prepared chicken dish according to any one of claims 1 to 7, characterized in that: The following steps are involved: (1) Cut the chicken pieces evenly, immerse them in 1-2 wt% saline, and treat them in a dual-frequency ultrasonic field for 14-16 minutes. After treatment, take them out and drain them to obtain pretreated chicken; (2) Put 85-90 parts by weight of the pretreated chicken obtained in step (1) into a tumbling machine, add 6-10 parts of a composite seasoning base and 3-6 parts of a laccase-catalyzed directional cross-linking preservative, set the vacuum degree to -0.085-(-0.095) MPa, the rotation speed to 10-12 r / min, the temperature to 3-5°C, and tumble for 30-45 minutes to obtain seasoned chicken; (3) The seasoned chicken obtained in step (3) is vacuum packaged, heated in a special packaging bag using a microwave, and then frozen to -10°C to (-5)°C to obtain the chicken pre-cooked dish.

9. The method for preparing the prepared chicken dish according to claim 8, characterized in that: In the dual-frequency ultrasonic field treatment of step (1), the low-frequency ultrasonic frequency is 39-41kHz, the high-frequency frequency is 0.9-1.1MHz, the power density is 14-16W / cm², the two frequencies are alternated, and each frequency is treated for 85-95s.

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