Roast duck production process

Abstract

The invention relates to the technical field of food processing, and discloses a roast duck production process which comprises the following steps: firstly, performing inflation, skin scalding, sugar coating and low-temperature large-air-volume drying on a duck embryo to reduce the moisture of a skin layer to a set range; secondly, pouring a sol-state gel soup base into the abdominal cavity, cooling and gelatinizing the sol-state gel soup base, and meanwhile, spraying a weakly-alkaline oil-water micro-emulsified penetrating fluid onto the skin; then carrying out instantaneous high-temperature impact at 228-232 DEG C for about 8 minutes, so that a porous bulking layer is formed on the epidermis; and finally, quickly passing through the maximum ice crystal generation zone through the ultralow-temperature quick-freezing tunnel. According to the method disclosed by the invention, by utilizing a gel phase change support and enzymolysis tenderization technology and cooperating with efficient heat transfer and interface catalytic action of a micro-emulsification medium, epidermis coloring and texture recombination within a short time are realized. According to the process, the baking time is shortened, the water loss of meat is reduced, the problems that the skin of the quick-frozen roast duck is softened and the meat is dry and hard after the quick-frozen roast duck is reheated are effectively solved, and the production efficiency and sensory quality of the product are improved.

Description

Technical Field

[0001] This invention relates to the field of food processing technology, and in particular to a roast duck production process. Background Technology

[0002] Roast duck, a traditional poultry product, is widely loved by consumers for its crispy skin, tender meat, and reddish-brown color. With the development of industrialized production, quick-frozen pre-prepared roast duck has gradually become one of the mainstream product forms in the market. The traditional quick-frozen roast duck production process usually follows the processing path of high-temperature, long-term roasting. Typical process parameters are set to roast at a temperature of 180℃ to 200℃ for 40 to 60 minutes, combined with a pasteurization step to ensure the microbiological safety of the product.

[0003] However, this prolonged high-temperature heat treatment has a significant impact on the sensory quality of the product. Duck meat proteins denature and coagulate under continuous high temperatures, causing contraction of the muscle fibers and resulting in the loss of a large amount of juice from the muscle. This makes the final product dry, hard, coarse, and tough, making it difficult to replicate the tender and juicy characteristics of freshly prepared duck meat.

[0004] Furthermore, excessive heat can interfere with the Maillard reaction process in the skin, easily leading to scorching or over-carbonization, causing the duck skin to turn dark brown or even black, failing to achieve the characteristic jujube-red appearance of traditional roast duck. In addition, prolonged high-temperature environments also result in the volatilization of flavor substances and the loss of some nutrients, leading to a significant difference in overall quality between existing pre-made roast duck products and freshly roasted products. Summary of the Invention

[0005] The purpose of this invention is to provide a roast duck production process that solves the technical problems of existing quick-frozen roast duck production processes, which result in shrinkage and hardening of meat fibers, severe loss of juice, and poor skin color and taste due to prolonged high-temperature treatment.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A roast duck production process includes the following steps:

[0008] S1. Pretreatment and Drying: Select duck embryos, separate the subcutaneous fat layer and muscle layer through aeration, scald the skin, coat with sugar, and then dry at low temperature with high air volume. Control the drying temperature at 4±1℃, the circulating air speed at 3.0-5.0m / s, and the total drying time at 20-26 hours to reduce the moisture content of the skin layer to 14.0%-15.5%.

[0009] S2. Gel Infusion and Microemulsion Spraying: Infuse 150-200mL of sol-gel broth into the abdominal cavity of the dried duck embryo, seal it, and cool it to 3-5℃ to allow it to gel in situ; then spray 15.0-20.0g of weakly alkaline oil-water microemulsion penetrating liquid onto the surface of the duck skin to form an oil film layer; S3. Instantaneous High-Temperature Shock Roasting: Place the duck embryo in an oven at 228-232℃ and shock it at high temperature for 7.5-8.5 minutes until a porous puffed layer forms on the skin;

[0010] S4. Ultra-low temperature quick-freezing: The roasted duck embryo is immediately sent into a quick-freezing tunnel at -45℃ to -50℃, and the time to pass through the maximum ice crystal formation zone is controlled to be ≤3 minutes, so that the core temperature of the product drops to below -18℃ within 7-8.5 minutes, thus producing pre-made roast duck.

[0011] By adopting the above technical solution, this invention utilizes the combined effects of gel phase change, enzymatic tenderization, and microemulsion heat transfer to achieve color formation and texture improvement under short-term high-temperature conditions. The specific principle is as follows:

[0012] The gel broth injected in step S2 remains solid during the low-temperature drying stage, supporting the duck embryo's shape and preventing abdominal cavity collapse caused by prolonged air drying. Simultaneously, the proteases embedded in the gel continuously degrade the connective tissue of the duck meat's inner wall in the solid medium, disrupting the myofibril network. Upon entering the high-temperature environment of step S3, the gel rapidly undergoes a phase transition, transforming into a liquid and boiling. High-pressure steam is generated within the sealed abdominal cavity, heating the duck meat from the inside. This bidirectional heat transfer mode—internal steam heating and external high-temperature roasting—shortens the path of heat transfer to the meat's center, allowing the enzymatically pretreated duck meat to reach cooking temperature within minutes while retaining moisture.

[0013] The weakly alkaline oil-water microemulsion penetrating liquid sprayed in step S2 utilizes its micron-sized dispersed particles to increase the specific surface area of ​​the oil film and improve heat transfer efficiency. Because the microstructure of this penetrating liquid can penetrate deep into the micropores of the epidermis, and the system's pH value is adjusted to a weakly alkaline environment of approximately 8.5, the activation energy of the Maillard reaction is lowered, promoting the ring-opening of reducing sugars and the condensation of amino acids. Under high-temperature shock at approximately 230℃, the browning reaction rate within the epidermis is significantly accelerated. Combined with the rapid vaporization of water, the epidermis completes coloring and forms a porous, swollen structure within approximately 8 minutes.

[0014] Step S1 controls the epidermal moisture content at a low level of 14.0%-15.5%, while the internal muscle layer retains a higher moisture content, creating a humidity gradient. This difference ensures that during high-temperature shock, heat is primarily consumed in the expansion, dehydration, and shaping of the epidermal layer, without causing excessive water loss in the internal muscle layer.

[0015] Preferably, in step S1, the humidity control of the low-temperature high-volume drying is as follows: the initial relative humidity is 75%-78%, and it gradually decreases to 55%-58% in the middle and later stages, with the weight loss rate controlled at 1.2%-1.5% / h.

[0016] The initial period is 0-6 hours, and the middle and later periods are 6-24 hours.

[0017] By adopting the above technical solutions, the phased reduction of humidity avoids the formation of a hard shell due to excessive evaporation of surface moisture in the early stage of drying, ensuring that internal moisture can continuously migrate to the surface; controlling the rate of weight loss allows the subcutaneous fat to separate appropriately from the dermis, reserving microscopic space for subsequent skin expansion at high temperatures.

[0018] Preferably, in step S2, the gel soup base is made from the following raw materials by weight percentage:

[0019] The mixture contains 4.5%-5.0% hydrophilic colloid, 0.04%-0.05% enzymatic hydrolysis synergist, 0.46%-0.95% salt, with the remainder being base duck bone broth.

[0020] The compounded hydrophilic colloid is composed of low-acyl gellan gum, konjac gum, and κ-carrageenan in a mass ratio of (1.5-2.5):1:1;

[0021] The enzymatic hydrolysis synergist is a mixture of bromelain and papain in a mass ratio of 3:1.

[0022] The activity of the bromelain is ≥50000 U / g, and the activity of the papain is ≥100000 U / g.

[0023] By adopting the above technical solution, the compound hydrophilic colloid of this ratio has thermal reversibility, forming a gel of a certain strength at 4℃ and rapidly melting into a low-viscosity sol above 45℃, which meets the requirements of drying support and heating release; the compound enzyme preparation maintains its activity at low temperature, specifically degrading collagen in connective tissue and improving the tenderness of duck meat.

[0024] Preferably, in step S2, the weakly alkaline oil-water microemulsion permeate comprises, by mass percentage:

[0025] The composition consists of an oil phase of 28.0%-29.0%, a reducing sugar complex of 9.0%-9.5%, a compound emulsifier of 1.0%-1.5%, and the remainder being an aqueous phase.

[0026] The oil phase is refined duck oil, the reducing sugar complex is composed of glucose and xylose in a mass ratio of 3-5:1, and the compound emulsifier is composed of soybean lecithin and sucrose fatty acid ester in a mass ratio of 0.5-1.5:1.

[0027] The average droplet size of the dispersed phase of the weakly alkaline oil-water microemulsion permeate is 0.5-2.0 μm.

[0028] By adopting the above technical solution, xylose has a faster reaction rate and provides the basic base color; glucose reacts relatively slowly and maintains a continuous browning process; duck oil, as an oil phase, is similar to the composition of duck skin, and combined with the microemulsion state, it can act as an efficient heat medium to transfer high-temperature energy instantly and shorten the coloring time.

[0029] Preferably, in step S4, the roasted duck embryo is immediately sent into a quick-freezing tunnel at -45°C to -50°C, and the time spent passing through the maximum ice crystal formation zone is controlled to be ≤3 minutes, so that the core temperature of the product drops to below -18°C within 7-8.5 minutes.

[0030] By adopting the above technical solution, the temperature is rapidly reduced, which causes the water inside the cells to form small and evenly distributed ice crystals. This reduces the mechanical damage to the cell membrane caused by the growth of ice crystals, thereby reducing the juice loss rate during thawing.

[0031] In summary, the present invention has at least one of the following beneficial technical effects:

[0032] 1. This invention improves the cooking efficiency and tenderness of roast duck by combining internal gel infusion with external microemulsion spraying. The gel broth remains solid during the drying stage to support the duck embryo's shape, and liquefies to release steam during the high-temperature stage, utilizing embedded proteases to tenderize the connective tissue. The weakly alkaline microemulsion increases the heat transfer area and lowers the Maillard reaction activation energy using micron-sized oil droplets. This combination allows the duck embryo to achieve skin browning and internal cooking within minutes under high-temperature stress, avoiding excessive moisture evaporation caused by traditional long-time roasting and achieving a crispy exterior and tender interior.

[0033] 2. The humidity gradient control and high-temperature puffing process employed in this invention improves the surface texture and color stability of the pre-roasted duck. By segmented drying, the surface moisture is precisely controlled at a low level, establishing a moisture difference between the inside and outside. This ensures that during high-temperature impact, heat is preferentially used for dehydration and puffing of the surface layer, forming a stable porous structure. Combined with the coloring effect of the compound reducing sugars, the product exhibits a uniform jujube-red color. Furthermore, this porous structure helps maintain the crispness of the skin during subsequent freezing and reheating, reducing softening.

[0034] 3. The ultra-low temperature quick-freezing process of this invention reduces the juice loss rate of the product. Utilizing the low-temperature environment, the duck embryo, after being subjected to high-temperature shock, quickly passes through the zone of maximum ice crystal formation, promoting the formation of small and evenly distributed ice crystals within the cells. This crystallization method reduces the mechanical damage to muscle cell membranes caused by ice crystal growth, thus ensuring that the product maintains high water retention and juicy flavor even after cold chain storage and final reheating. Detailed Implementation

[0035] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the preparation examples, comparative examples, and test examples. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Preparation Examples 1-6:

[0037] Preparation Example 1:

[0038] This preparation example provides a low-temperature active thixotropic gel soup base with median enzyme activity and optimal colloidal ratio, comprising the following steps:

[0039] S1. Component compounding: Weigh 22.5g of low-acyl gellan gum, 11.25g of konjac gum, and 11.25g of κ-carrageenan at a mass ratio of 2:1:1, and mix them evenly to obtain a compound hydrophilic colloid (total 45g); Weigh 0.3g of bromelain (≥50000U / g) and 0.1g of papain (≥100000U / g) at a mass ratio of 3:1, and mix them evenly to obtain an enzymatic hydrolysis synergist (total 0.4g); Separately prepare 4.6g of salt and 950g of basic duck bone broth.

[0040] S2. Dissolution and shear crosslinking: Heat the basic duck bone broth to 88°C, start the high-shear emulsifier, set the speed to 900 rpm, and slowly add the compound hydrophilic colloid and salt prepared in step S1 while stirring; keep the temperature in the range of 85°C-90°C and continue high-speed shear stirring for 12 minutes until the system is completely hydrated and dissolved to form a uniform sol solution without particles.

[0041] S3. Cooling, Inoculation, and Shaping: Rapidly cool the above sol solution to 41°C, add the enzymatic hydrolysis synergist prepared in step S1, reduce the stirring speed to 200 rpm and gently stir for 2 minutes to avoid introducing air bubbles and ensure uniform dispersion of the enzyme preparation; then transfer the mixture to a clean container and place it in a 4°C environment to cool and allow it to undergo a phase transition to form a solid gel, thus obtaining the gel sol matrix. In this system, the mass percentage of the compounded hydrophilic colloid is 4.5%, the mass percentage of the enzymatic hydrolysis synergist is 0.04%, and the mass percentage of the base sol solution is 95.0%.

[0042] Preparation Example 2:

[0043] This preparation example provides a low-temperature active thixotropic gel soup base with low enzyme activity concentration and low colloidal strength, comprising the following steps:

[0044] S1. Component compounding: Weigh 17.5g of low-acyl gellan gum, 8.75g of konjac gum, and 8.75g of κ-carrageenan at a mass ratio of 2:1:1, and mix them evenly to obtain a compound hydrophilic colloid (total 35.0g); Weigh 0.15g of bromelain (≥50000U / g) and 0.05g of papain (≥100000U / g) at a mass ratio of 3:1, and mix them evenly to obtain an enzymatic hydrolysis synergist (total 0.2g); Separately prepare 4.8g of salt and 960.0g of basic duck bone broth.

[0045] S2. Dissolution and shear crosslinking: Heat the basic duck bone broth to 85°C, start the high-shear emulsifier, set the speed to 800 rpm, and slowly add the compound hydrophilic colloid and salt prepared in step S1 while stirring; keep the temperature at 85°C and continue shearing and stirring for 10 minutes until the system is completely hydrated and dissolved to form a uniform sol solution without particles.

[0046] S3. Cooling, Inoculation, and Shaping: Cool the above sol solution to 40°C, add the enzymatic hydrolysis synergist prepared in step S1, reduce the stirring speed to 200 rpm and gently stir for 2 minutes to avoid introducing air bubbles and ensure uniform dispersion of the enzyme preparation; then transfer the mixture to a clean container and place it in a 4°C environment to cool and allow it to undergo a phase transition to form a solid gel, thus obtaining the gel sol matrix. In this system, the mass percentage of the compounded hydrophilic colloid is 3.5%, the mass percentage of the enzymatic hydrolysis synergist is 0.02%, and the mass percentage of the base sol solution is 96.0%.

[0047] Preparation Example 3:

[0048] This preparation example provides a low-temperature active thixotropic gel soup base with high enzyme activity concentration and high colloidal strength, comprising the following steps:

[0049] S1. Component compounding: Weigh 25.0g of low-acyl gellan gum, 12.5g of konjac gum, and 12.5g of κ-carrageenan at a mass ratio of 2:1:1, and mix them evenly to obtain a compound hydrophilic colloid (total 50.0g); Weigh 0.375g of bromelain (≥50000U / g) and 0.125g of papain (≥100000U / g) at a mass ratio of 3:1, and mix them evenly to obtain an enzymatic hydrolysis synergist (total 0.5g); Separately prepare 9.5g of salt and 940.0g of basic duck bone broth.

[0050] S2. Dissolution and Shear Crosslinking: Heat the base duck bone broth to 90°C, start the high-shear emulsifier, set the speed to 1000 rpm, and slowly add the compound hydrophilic colloid and salt prepared in step S1 while stirring; keep the temperature at 90°C and continue to stir with strong shear for 15 minutes to ensure that the high-concentration colloid is completely hydrated and dissolved to form a uniform, particle-free thick sol solution.

[0051] S3. Cooling, Inoculation, and Shaping: Cool the above sol solution to 42°C, add the enzymatic hydrolysis synergist prepared in step S1, reduce the stirring speed to 200 rpm and gently stir for 2 minutes to avoid introducing air bubbles and ensure uniform dispersion of the enzyme preparation; then transfer the mixture to a clean container and place it in a 4°C environment to cool and allow it to undergo a phase transition to form a high-strength solid gel, thus obtaining the gel sol matrix. In this system, the mass percentage of the compounded hydrophilic colloid is 5.0%, the mass percentage of the enzymatic hydrolysis synergist is 0.05%, and the mass percentage of the base sol solution is 94.0%.

[0052] Preparation Example 4:

[0053] This preparation example provides an optimally formulated weakly alkaline oil-water microemulsion permeate with a pH of 8.5, comprising the following steps:

[0054] S1. Aqueous phase preparation: Weigh 72.0g of glucose and 18.0g of xylose (mass ratio 4:1), add them to 620.0g of deionized water, and stir until the reducing sugar complex is completely dissolved to obtain the aqueous phase base.

[0055] S2. Dispersion of oil phase and emulsifier: Weigh 5.0g of soybean lecithin and 5.0g of sucrose fatty acid ester (mass ratio 1:1) as compound emulsifier; measure 280.0g of refined duck oil, heat to 63℃, add the compound emulsifier to the hot oil, stir to fully dissolve and disperse, and obtain the oil phase base material.

[0056] S3. High-pressure homogenization and emulsification: Under stirring, the oil phase base material from step S2 is slowly injected into the aqueous phase base material from step S1. The high-shear emulsifier is started, the speed is set to 4000 rpm, and the primary emulsion is obtained after 4 minutes. Then, it is sent to a high-pressure homogenizer and homogenized twice under a pressure of 45 MPa to control the average particle size of the dispersed phase droplets between 0.5-2.0 μm, forming a stable microemulsion system.

[0057] S4. pH Gradient Adjustment: A 10% sodium carbonate aqueous solution was added dropwise to the microemulsion system while stirring. The pH was monitored in real-time using a pH meter until it stabilized at 8.5 at 25°C, yielding a weakly alkaline oil-water microemulsion. In this system, the oil phase accounted for approximately 28.0% of the total mass, the reducing sugar complex for approximately 9.0%, and the compounded emulsifier for approximately 1.0%.

[0058] Preparation Example 5:

[0059] This preparation example provides a weakly alkaline oil-water microemulsion permeate with a low pH and low solids content, including the following steps:

[0060] S1. Preparation of aqueous phase: Weigh 68.0g of glucose and 17.0g of xylose (mass ratio 4:1), add them to 650.0g of deionized water, and stir until the reducing sugar complex is completely dissolved to obtain the aqueous phase base.

[0061] S2. Dispersion of oil phase and emulsifier: Weigh 5.0g of soybean lecithin and 5.0g of sucrose fatty acid ester (mass ratio 1:1) as compound emulsifier; measure 255.0g of refined duck oil, heat to 60℃, add the compound emulsifier to the hot oil, stir to fully dissolve and disperse it, and obtain the oil phase base material.

[0062] S3. High-pressure homogenization and emulsification: Under stirring, the oil phase base material from step S2 is slowly injected into the aqueous phase base material from step S1. The high-shear emulsifier is started, the speed is set to 3000 rpm, and the primary emulsion is obtained after 3 minutes. Then, it is sent to the high-pressure homogenizer and homogenized twice under a pressure of 40 MPa to form a microemulsion system from the dispersed phase droplets.

[0063] S4. pH Gradient Adjustment: A 10% sodium carbonate aqueous solution was added dropwise to the microemulsion system while stirring. The pH was monitored in real-time using a pH meter until it stabilized at 8.0 at 25°C, thus obtaining the weakly alkaline oil-water microemulsion permeate of Example 5. In this system, the oil phase accounted for approximately 25.5% of the mass, the reducing sugar complex accounted for approximately 8.5%, and the basic aqueous phase accounted for approximately 65.0%.

[0064] Preparation Example 6:

[0065] This preparation example provides a weakly alkaline oil-water microemulsion permeate with a high pH value and a higher proportion of oil phase, including the following steps:

[0066] S1. Aqueous phase preparation: Weigh 76.0g of glucose and 19.0g of xylose (mass ratio 4:1), add them to 600.0g of deionized water, and stir until the reducing sugar complex is completely dissolved to obtain the aqueous phase base.

[0067] S2. Dispersion of oil phase and emulsifier: Weigh 7.5g of soybean lecithin and 7.5g of sucrose fatty acid ester (mass ratio 1:1) as compound emulsifier; measure 290.0g of refined duck oil, heat to 65℃, add the compound emulsifier to the hot oil, stir to fully dissolve and disperse it, and obtain the oil phase base material.

[0068] S3. High-pressure homogenization and emulsification: Under stirring, the oil phase base material from step S2 is slowly injected into the aqueous phase base material from step S1. The high-shear emulsifier is started and the speed is set to 5000 rpm. The primary emulsion is obtained by strong shearing for 5 minutes. Then, it is sent to a high-pressure homogenizer and homogenized twice under a high pressure of 50 MPa to control the average particle size of the dispersed phase droplets at 0.5-2.0 μm, forming a thick microemulsion system.

[0069] S4. pH Gradient Adjustment: A 10% sodium carbonate aqueous solution was added dropwise to the microemulsion system while stirring. The pH was monitored in real-time using a pH meter until it stabilized at 9.0 at 25°C, yielding a weakly alkaline oil-water microemulsion. In this system, the oil phase accounted for approximately 29.0% of the total mass, the reducing sugar complex for approximately 9.5%, and the compounded emulsifier for approximately 1.5%.

[0070] Examples 1-4:

[0071] Example 1:

[0072] This embodiment provides a roast duck production process, using the gel broth prepared in Preparation Example 1 and the weakly alkaline oil-water microemulsion permeate prepared in Preparation Example 4, including the following steps:

[0073] S1. Pretreatment and basic sugar coating:

[0074] Duck embryos weighing 2.0-2.2 kg were selected and inflated through the subcutaneous tissue of the neck at 0.18 MPa to achieve a separation of over 95% between the subcutaneous fat layer and the muscle layer. The skin was then scalded three times with boiling water at 99℃, with each contact lasting 4 seconds and a total heat treatment time of 12 seconds, until the skin shrank and tightened. A 13.5% pure maltose aqueous solution (45℃) was prepared and evenly applied to the surface of the duck embryos, which were then drained for 8 minutes.

[0075] S2, Low-temperature, high-volume intelligent drying:

[0076] The processed duck embryos were placed in a drying room, with the temperature set at 4.0℃ throughout the process and the airflow maintained at 4.0 m / s to ensure turbulence. The relative humidity was controlled at 78% in the initial stage (0-6 hours) and gradually reduced to 58% in the middle and later stages (6-24 hours). The weight loss rate was monitored in real time and was approximately 1.3% / h, with a total drying time of 24 hours. At the end, the moisture content of the duck embryo's skin layer was measured at 14.5%, and the skin appeared translucent and keratinous.

[0077] S3, Gel infusion and microemulsion-enhanced color mixing:

[0078] The gelled broth prepared in Example 1 was heated to 45°C and converted into a sol state. 180 ml was poured into the side opening of the duck and then sealed. Utilizing the residual cooling (approximately 4°C) after the duck was air-dried at low temperature, the broth re-gelled in situ within the abdominal cavity within 15 minutes. At this time, the enzymatic synergist in the broth began to micro-degrade the connective tissue of the duck meat's inner wall. Next, using a high-pressure atomizing spray gun (pressure 0.4 MPa), the weakly alkaline oil-water microemulsion penetrating liquid prepared in Example 4 was evenly sprayed onto the dried duck skin surface at a rate of 18.0 g / duck, forming a uniform oil film layer.

[0079] S4. Instantaneous high-temperature shock baking:

[0080] Preheat the oven cavity to a stable temperature of 230℃. Place the duck embryos in the oven and maintain a precise dwell time of 8.0 minutes. Monitor the skin color online; remove the ducks from the oven when the L value is approximately 58.0 and the a value is approximately 13.5. At this point, a porous, puffed layer with a thickness of approximately 0.4mm has formed on the skin.

[0081] S5, Ultra-low Temperature Gradient Quick Freezing:

[0082] The roasted duck carcasses are immediately placed in a quick-freezing tunnel with an air inlet temperature set at -45°C and a wind speed of 9 m / s. The product's geometric center temperature drops below -18°C within 7.5 minutes, and the time spent passing through the maximum ice crystal formation zone (-1°C to -5°C) is controlled within 2.5 minutes to ensure small ice crystals within the product. It is then vacuum-packed and stored in a -18°C cold storage.

[0083] Example 2:

[0084] This embodiment provides a roast duck production process, using the gel broth prepared in Preparation Example 2 and the weakly alkaline oil-water microemulsion permeate prepared in Preparation Example 5, including the following steps:

[0085] S1. Pretreatment and basic sugar coating:

[0086] Select duck embryos weighing approximately 2.0 kg and inflate them at 0.15 MPa to ensure separation of skin and meat. Perform a three-stage heat treatment using boiling water at 98℃, with each stage lasting 3 seconds and a total heat treatment time of 10 seconds. Prepare a 12.0% pure maltose aqueous solution (40℃) and apply it to the surface of the duck embryos, allowing them to drain for 5 minutes.

[0087] S2, Low-temperature, high-volume intelligent drying:

[0088] The duck embryos were placed in a drying room, and a phased heating method was implemented: the temperature was set at 4℃ for 0-12 hours to promote initial dehydration and low-temperature enzyme activation; the temperature was set at 10℃ for 12-24 hours to accelerate internal enzymatic reactions. The airflow speed was maintained at 3.0 m / s throughout the process, and the humidity gradually decreased from 75% initially to 55% in the later stages. The weight loss rate was controlled at 1.2% / h. After 24 hours of drying, the surface moisture content was approximately 15.0%.

[0089] S3, Gel infusion and microemulsion-enhanced color mixing:

[0090] The gelling broth (low enzyme activity and low colloidal strength) prepared in Preparation Example 2 was heated and melted, then poured into the duck's abdomen in 150 ml and sealed. The duck's body temperature after air drying was used to gel the broth within 20 minutes, creating a softer internal support and allowing for gentle enzymatic hydrolysis. Subsequently, a weakly alkaline oil-water microemulsion permeating solution (pH 8.0) prepared in Preparation Example 5 was sprayed onto the duck skin surface using an atomizing spray gun (pressure 0.3 MPa), with a spraying amount of 15.0 g per duck, forming a basic oil film layer.

[0091] S4. Instantaneous high-temperature shock baking:

[0092] Preheat the oven to 228℃. Place the duck embryos into the oven, and extend the dwell time to 8.5 minutes to compensate for the lower oven temperature and the lower pH of the coloring solution. Monitor the skin color online, and remove the ducks from the oven when the L and a values ​​reach the predetermined thresholds (L*≈60.0, a*≈12.0), at which point a puffed layer of approximately 0.3 mm will have formed on the skin.

[0093] S5, Ultra-low Temperature Gradient Quick Freezing:

[0094] The product is placed in a quick-freezing tunnel with an inlet temperature of -45℃ and an air velocity of 8m / s. The product's core temperature is controlled to drop below -18℃ within 8.0 minutes, and the time to pass through the maximum ice crystal formation zone is approximately 2.8 minutes. Subsequently, it undergoes modified atmosphere packaging and is transferred to a -18℃ cold storage.

[0095] Example 3:

[0096] This embodiment provides a roast duck production process, using the gel broth prepared in Preparation Example 3 and the weakly alkaline oil-water microemulsion permeate prepared in Preparation Example 6, including the following steps:

[0097] S1. Pretreatment and basic sugar coating:

[0098] Select plump duck embryos weighing 2.2-2.4 kg and inflate them under a slightly higher pressure of 0.20 MPa to ensure full release of the skin. Then, use a three-stage immersion and extraction process in boiling water at 100℃, with each stage lasting 5 seconds and a total heat treatment time of 15 seconds, to maximize the firmness of the duck skin. Prepare a 15.0% pure maltose aqueous solution (50℃) and thoroughly coat the surface of the duck embryos, then drain for 10 minutes.

[0099] S2, Low-temperature, high-volume intelligent drying:

[0100] The duck embryos were placed in a drying room with the temperature constantly controlled at 3.5℃ to inhibit excessive reaction of the high-concentration enzyme solution. A strong turbulent airflow mode with a circulation speed of 5.0 m / s was set. Humidity control was even more stringent, initially maintained at 75%, and then rapidly reduced to 55% in the middle and later stages. The weight loss rate was controlled at the upper limit of 1.5% / h, and drying was carried out for 24 hours to ensure that the moisture content of the epidermis was reduced to below 14.0%, forming a dense stratum corneum.

[0101] S3, Gel infusion and microemulsion-enhanced color mixing:

[0102] The gelling broth prepared in Preparation Example 3 was heated and melted, with the injection volume increased to 200 ml per duck. Its high colloidal strength allowed for rapid gelation within 10 minutes, providing strong support. Subsequently, a weakly alkaline oil-water microemulsion (pH 9.0) prepared in Preparation Example 6 was sprayed onto the duck skin surface using a high-pressure atomizing spray gun (pressure 0.5 MPa), with a spray volume of 20.0 g per duck. The high pH and high oil phase ratio promoted the Maillard reaction.

[0103] S4. Instantaneous high-temperature shock baking:

[0104] Preheat the oven cavity to a stable temperature of 232℃. Place the duck embryos into the oven and subject them to a rapid high-temperature shock, with the dwell time precisely controlled at 7.5 minutes. Monitor the skin color online, and remove them from the oven immediately when the L value drops to 55.0 and the a value reaches 15.0. At this point, the skin undergoes vigorous puffing, forming a porous, crisp layer approximately 0.5mm thick.

[0105] S5, Ultra-low Temperature Gradient Quick Freezing:

[0106] The product is placed in a quick-freezing tunnel and subjected to an extreme freezing program with an air inlet temperature of -50°C and a wind speed of 10 m / s. This causes the geometric center temperature of the product to drop sharply to below -18°C within 7.0 minutes, and the time for the maximum ice crystal formation zone to pass through is compressed to 2.2 minutes. The product is then vacuum-sealed and transferred to a -18°C cold storage.

[0107] Example 4:

[0108] This embodiment provides a roast duck production process, using the gel broth prepared in Preparation Example 1 and the weakly alkaline oil-water microemulsion permeate prepared in Preparation Example 4, including the following steps:

[0109] S1. Pretreatment and basic sugar coating:

[0110] Large-sized duck embryos with a single-frozen weight of 2.5 kg were selected. To ensure sufficient release of subcutaneous fat, the inflation pressure was set to the upper limit of 0.20 MPa. A three-dip, three-lift process was performed using boiling water at 100℃. Due to the large size of the ducks, the total heat treatment time was controlled to 15 seconds. A 15.0% pure maltose aqueous solution (48℃) was prepared and applied to the surface of the duck embryos. The embryos were then drained for 10 minutes to ensure even maltose coating.

[0111] S2, Low-temperature, high-volume intelligent drying:

[0112] The duck embryos were placed in a drying room with the temperature set at 4.0℃. Considering the increased surface area of ​​the ducks, the circulating air velocity was set to 4.5 m / s to enhance convective heat transfer. The humidity control strategy remained consistent with Example 1 (reducing humidity from 78% to 58%). The total weight loss was closely monitored. After 24 hours of drying, the skin moisture content was ensured to be below 15.0%, and the skin exhibited a uniform keratinized state.

[0113] S3, Gel infusion and microemulsion-enhanced color mixing:

[0114] To address the increased abdominal cavity volume of the 2.5kg duck embryo, the injection volume of the gelled broth prepared in Example 1 was adjusted to the upper limit of the process range, 200ml. After sealing, it was gelled within 15 minutes using a low-temperature environment to ensure sufficient internal support and flavor release. Subsequently, a high-pressure atomizing spray gun (pressure 0.4MPa) was used to spray the weakly alkaline oil-water microemulsion penetrating liquid prepared in Example 4 onto the duck skin surface, with the spraying amount increased to 20.0g / bird to ensure the formation of a continuous and uniformly thick microemulsion heat-conducting oil film over a larger surface area.

[0115] S4. Instantaneous high-temperature shock baking:

[0116] Preheat the oven cavity to 230℃. Considering the influence of the specific heat capacity and surface area of ​​large-sized duck embryos, the high-temperature shock time is slightly adjusted to 8.5 minutes. Monitor the skin color online, and remove the duck from the oven when the L and a values ​​reach the standard range (L*≈58.0, a*≈13.5), ensuring that the thickness of the puffed skin layer reaches about 0.4mm and there is no scorching.

[0117] S5, Ultra-low Temperature Gradient Quick Freezing:

[0118] The roasted duck carcasses are placed in a quick-freezing tunnel. Due to the increased heat load of the product, high-intensity freezing conditions are maintained, with an air inlet temperature of -45°C and a wind speed of 9 m / s. The product's geometric center temperature is controlled to drop below -18°C within 8.0 minutes, and the time for the maximum ice crystal formation zone to pass through is controlled within 2.8 minutes. Subsequently, the product is vacuum-packed and transferred to a -18°C cold storage.

[0119] Comparative Examples 1-5:

[0120] Comparative Example 1:

[0121] Compared with Example 1, the differences are as follows: the traditional roast duck processing technology is adopted, that is, step S1 is changed to air-drying the duck at room temperature (20-25℃) for 6 hours; step S3 does not involve filling the gel soup base and spraying the microemulsion; step S4 is changed to traditional hanging oven slow roasting (180℃-200℃, roasting for 40 minutes); step S5 is changed to directly transferring the duck to a -18℃ cold storage for conventional freezing. All other steps are different.

[0122] Comparative Example 2:

[0123] Compared with Example 1, the difference is that the gel soup in step S3 is removed and replaced with an equal volume of ordinary salt water (salt content 1.2%). That is, the infusion solution does not contain compound hydrophilic colloid and enzymatic hydrolysis synergist, so it cannot form a gel and has no biological enzymatic hydrolysis effect. The remaining steps and parameters are the same.

[0124] Comparative Example 3:

[0125] Compared with Example 1, the difference is that the weakly alkaline oil-water microemulsion penetrating liquid in step S3 is removed and replaced with an equal amount of ordinary neutral glucose aqueous solution (concentration 10%, pH 7.0), that is, the spraying liquid does not contain duck oil phase, compound emulsifier and alkaline regulator, and the remaining steps and parameters are the same.

[0126] Comparative Example 4:

[0127] Compared with Example 1, the difference is that the low-temperature drying time in step S2 is shortened from 24 hours to 6 hours, resulting in insufficient dehydration of duck skin and insufficient enzymatic hydrolysis time. The remaining steps and parameters are the same.

[0128] Comparative Example 5:

[0129] Compared with Example 1, the difference is that the ultra-low temperature gradient quick-freezing in step S5 is removed and replaced by a conventional freezing process, that is, the baked product is directly placed in a -18℃ cold storage for natural slow freezing, without the quick-freezing tunnel process of rapidly passing through the ice crystal zone, and the remaining steps and parameters are the same.

[0130] Test Examples 1-6:

[0131] Test Example 1: Verification of short-term high-temperature shock heat transfer efficiency

[0132] Experimental steps:

[0133] Duck embryos processed in step S3 of Example 1 were selected. Miniature K-type thermocouples were implanted at the center of the skin of the duck breast, leg, and back, with the probe depth controlled at 0.5 mm subcutaneously. The samples were placed in an oven preheated to 230°C, and temperature change data from 0 to 8.5 minutes after entering the oven were collected using a multi-channel temperature recorder at a sampling frequency of 10 Hz. The experiment was repeated 5 times, and the average value of three points was taken.

[0134] Experimental data:

[0135] Table 1: Record of epidermal temperature changes during instantaneous high-temperature shock

[0136] Time (min) Duck breast skin temperature T1 (°C) Duck leg skin temperature T2 (°C) Duck back skin temperature T3 (°C) Average temperature (°C) 0.0 4.2 4.1 4.3 4.20 1.0 38.7 35.4 40.1 38.07 2.0 76.5 72.8 78.4 75.90 3.0 112.3 108.9 115.6 112.27 4.0 145.8 141.2 148.5 145.17 5.0 172.4 168.7 176.9 172.67 6.0 195.1 191.5 198.8 195.13 7.0 208.6 205.3 212.4 208.77 8.0 218.9 215.7 221.2 218.60

[0137] Results Analysis and Conclusions:

[0138] Table 1 shows that the duck embryo skin temperature rose from 4.2℃ to 218.6℃ within 8 minutes. The average heating rate in the first 3 minutes exceeded 35℃ / min, higher than the thermal conductivity of conventional water-based solutions. This indicates that the microemulsion sprayed in step S3 formed a continuous oil-phase medium film on the duck skin surface. Oil has a low specific heat capacity and a high boiling point, acting as a heat transfer medium to allow the skin layer to rapidly cross the isothermal boiling zone of moisture under radiant heat, directly entering the high-temperature zone required for Maillard reaction and fat oxidation. The rapid increase in skin temperature confirms the heat transfer basis for completing roasting within 8 minutes using this process.

[0139] Test Example 2: Verification of Epidermal Chromatography Kinetics and pH Regulation

[0140] Experimental steps:

[0141] Prepare 20 duck embryos from the same batch of processed ducks, and divide them into 10 groups. Place each group into a 230℃ oven for heat shock of different durations (0 min to 9 min). After baking, use a CR-400 colorimeter to measure the L* (brightness), a* (redness), and b* (yellowness) values ​​of the breast epidermis. Measure 3 points for each duck and calculate the average value.

[0142] Experimental data:

[0143] Table 2: Changes in epidermal color parameters under weakly alkaline microemulsion system

[0144] Baking time (min) L* value (brightness) a* value (redness) b* value (yellowness) Color and condition description 0 76.42 2.15 8.34 pale 1 75.18 3.41 9.12 Slightly yellow 2 72.55 5.86 14.28 Light yellow with a slight sheen 3 69.34 7.92 18.67 golden 4 66.89 9.45 22.41 Deep golden yellow 5 63.71 10.88 26.53 Light red 6 60.25 12.14 28.76 Jujube Red 7 58.64 13.92 30.15 Bright red 8 56.12 14.85 31.42 Deep red and bright

[0145] Results Analysis and Conclusions:

[0146] Table 2 shows that the a value increases significantly between the 3rd and 7th minutes, while the L value decreases simultaneously to the 55-60 range. The weakly alkaline environment (pH 8.5) created by the permeate lowers the activation energy of the condensation reaction between amino acids and carbonyl compounds, accelerating the browning reaction within minutes. The data from the 7th-8th minute (a*≈14, L*≈56-58) represent the optimal color point. At the 9th minute, the L* value drops to 53.08 accompanied by caramelization, indicating sugar carbonization, confirming that 7.5-8.5 minutes is the suitable processing time window.

[0147] Test Example 3: Verification of the effect of bio-enzymatic hydrolysis in low-temperature air drying process

[0148] Experimental steps:

[0149] For the low-temperature drying process, duck breast meat samples were collected at three time points: 0h, 12h, and 24h. Superficial fat and connective tissue membranes were removed, and the deep muscle tissue was minced and mixed thoroughly. The amino acid nitrogen content in the samples was determined by formaldehyde titration to characterize the degree of protein degradation.

[0150] Experimental data:

[0151] Table 3: Changes in amino acid nitrogen content of muscle tissue during low-temperature air drying

[0152] Air drying time (h) Content of Sample 1 (mg / 100g) Content of Sample 2 (mg / 100g) Content of sample 3 (mg / 100g) Average content (mg / 100g) Relative growth rate (%) 0 65.4 66.1 64.9 65.47 - 12 98.7 101.3 99.5 99.83 52.48 24 142.3 145.8 141.6 143.23 118.77

[0153] Results Analysis and Conclusions:

[0154] Table 3 shows that after 24 hours of air drying, the amino acid nitrogen content in duck meat increased from 65.47 mg / 100g to 143.23 mg / 100g, an increase of 118.77%. Under low-temperature conditions of 4℃, the complex enzyme system in the gel broth remained active, causing degradation of myofibril proteins and connective tissue. The increase in amino acid nitrogen indicates that the internal structure of the meat had been tenderized during the drying stage. This biochemical process compensated for the insufficient heat-induced maturation time during the subsequent 8 minutes of high-temperature shock, preventing the meat from becoming tough.

[0155] Test Example 4: Verification of the Correlation between Texture Properties and Process Parameters

[0156] Experimental steps:

[0157] The frozen samples from Example 1 and each comparative example were reheated to a core temperature of 75°C using microwave, and then cooled to 40°C at room temperature for instrumental analysis. A TA.XTPlus texture analyzer was used for the analysis.

[0158] Shear force test: Duck breast meat was cut into 1cm×1cm×3cm cuboids, with the muscle fiber direction perpendicular to the blade. A Warner-Bratzler shear probe was used at a downward speed of 2.0mm / s to record the maximum shear force. Ten parallel samples were tested in each group.

[0159] Puncture strength test: Intact liposuction chest skin was fixed to the central hole stage. A 2mm diameter P / 2 cylindrical probe was used at a descending speed of 1.0mm / s to record the first peak force and rupture distance at the moment of penetration. Ten parallel samples were tested in each group.

[0160] Experimental data:

[0161] Table 4: Shear force and puncture strength test data of samples in each group

[0162] Group Shear force (N) (meat tenderness) Puncture force (N) (epidermal brittleness) Rupture distance (mm) Data Feature Description Example 1 18.42±1.25 3.15±0.42 0.82±0.15 Easy to cut, brittle outer skin Comparative Example 1 35.67±3.84 8.92±2.11 2.45±0.63 The flesh is firm and the skin is tough. Comparative Example 2 42.15±4.12 3.34±0.51 0.88±0.20 The meat is firm and the skin is crispy. Comparative Example 4 19.11±1.56 12.87±1.98 3.56±0.84 The meat is tender and the skin is very chewy. Comparative Example 5 26.83±5.22 5.12±1.15 1.12±0.33 The tissue is loose and the skin is slightly soft.

[0163] Results Analysis and Conclusions:

[0164] Table 4 shows that the shear force of Example 1 was lower than that of Comparative Example 2. Comparative Example 2 did not add low-temperature active enzymes; during the air-drying process, the myofibrils remained intact, and the short heating time of 8 minutes was insufficient to gelatinize the collagen, resulting in high meat firmness. Example 1 utilized a gelling broth to weaken the connective tissue during the low-temperature process, reducing the shear force of the final product.

[0165] Regarding the crispness of the outer skin, the puncture force of Example 1 was lower than that of Comparative Example 4. Comparative Example 4 had a shorter drying time, and the water activity of the outer skin did not drop to the critical point. Example 1 underwent 24 hours of segmented drying, resulting in a dehydrated glassy state of the outer skin, which formed a microporous structure under high temperature and steam pressure. Comparative Example 4, due to its higher residual moisture content, exhibited a cooking hardening effect at high temperatures rather than puffing and crispness.

[0166] Test Example 5: Sensory Quality and Microemulsion Color Development Effect Verification

[0167] Experimental steps:

[0168] An evaluation team of 12 personnel trained in food sensory evaluation was formed. Blind testing was conducted on the reheated samples of Example 1 and the comparative examples, which were randomly numbered. Evaluation indicators included: skin crispness, meat tenderness, color uniformity, and juiciness. A 10-point scoring system was used, with 10 representing the best and 1 representing the worst.

[0169] Experimental data:

[0170] Table 5: Sensory evaluation scores of the product after reheating

[0171] Group Crispy skin meat tenderness Color uniformity juicy Overall score Example 1 9.2 9.1 9.4 8.9 9.15 Comparative Example 1 6.4 5.2 7.1 5.5 6.05 Comparative Example 2 9.0 3.8 9.1 6.2 7.03 Comparative Example 3 9.1 8.8 4.2 8.7 7.70 Comparative Example 4 3.5 8.9 5.6 8.5 6.63

[0172] Results Analysis and Conclusions:

[0173] Table 5 shows that Comparative Example 3 had a low color score, indicating that glucose water alone could not complete the Maillard reaction for color formation under the conditions of 230℃ / 8 minutes. Example 1 had a color score of 9.4, indicating that the weakly alkaline environment of pH 8.5 combined with a micron-sized oil film improved the heat transfer efficiency and reaction rate, promoting rapid color formation.

[0174] The lower tenderness score in Comparative Example 2 affected the overall score, confirming the impact of enzymatic hydrolysis on the texture of short-time roasted products. In Example 1, all scores were around 9 points, indicating that the parameters of each process were well-balanced in terms of color, texture, and juiciness.

[0175] Test Example 6: Validation of Frozen Storage Stability and Quick-Freezing Process

[0176] Experimental steps:

[0177] Each group of samples was stored in a -18℃ cold storage for 90 days. Testing was conducted after the storage period.

[0178] Thawing loss rate determination: Measure the weight W1 before freezing, thaw naturally (center temperature 0-4℃) and absorb surface moisture, and then measure the weight W2 to calculate the loss percentage.

[0179] Skin moisture absorption rate determination: After thawing, duck skin was placed in a constant temperature and humidity chamber (25℃, RH60%) for 30 minutes, and the weight increase rate was measured.

[0180] Experimental data:

[0181] Table 6: Stability Indicators After 90 Days of Frozen Storage

[0182] Group Thawing loss rate (%) Epidermal moisture absorption rate (%) Result Features Example 1 2.14 4.35 The juices are well retained, and the crispness of the skin remains consistent. Comparative Example 4 2.56 13.22 The outer layer absorbs moisture and softens quickly, losing its crispness. Comparative Example 5 7.89 6.78 Severe fluid loss and tissue collapse

[0183] Results Analysis and Conclusions:

[0184] The data in Table 6 mainly reflect the impact of quick-freezing methods and drying degrees on shelf-life quality.

[0185] Comparative Example 5 showed a thawing loss rate of 7.89%, higher than that of Example 1. The slow-freezing process caused large ice crystals to form in the intercellular spaces, damaging the muscle cell membrane and leading to juice loss during thawing. Example 1 used a -45°C rapid freezing temperature, resulting in small, evenly distributed ice crystals that maintained the integrity of the cell structure.

[0186] Regarding the moisture absorption rate, Comparative Example 4 had a value of 13.22%, significantly higher than Example 1. This indicates that insufficient drying leads to increased hygroscopicity of the skin, making it prone to softening after reheating. Example 1, on the other hand, was thoroughly dried, resulting in a stable glassy structure with low hygroscopicity.

[0187] The technical solution in Example 1, through precise coupling of parameters at each stage, effectively solves the common technical problems of traditional quick-frozen roast duck, such as dry and hard meat, non-crispy skin, and significant thawing loss, while ensuring industrial production efficiency. The data fully supports the inventiveness and practicality claimed by this invention.

Claims

1. A process for producing roasted duck, characterized by, The method comprises the following steps: S1, pretreatment and drying: select duck embryo, separate the subcutaneous fat layer and muscle layer by air separation, scald the skin, hang sugar, and then perform low-temperature and high-velocity drying, control the drying temperature to be 4±1℃, the circulating air speed to be 3.0-5.0m / s, and the total drying time to be 20-26 hours, so that the water content of the epidermis layer is reduced to 14.0%-15.5%; S2, gel perfusion and microemulsion spraying: 150-200mL of sol-gel soup is perfused into the abdominal cavity of the dried duck embryo, and the duck embryo is cooled to 3-5℃ after being sealed to form in-situ gel; then 15.0-20.0g of weak alkaline oil-water microemulsion permeate is sprayed on the surface of the duck skin to form an oil film layer; S3, instant high-temperature impact roasting: the duck embryo is placed in a roaster with a temperature of 228-232℃, and is subjected to high-temperature impact for 7.5-8.5 minutes, so that a porous puffed layer is formed on the epidermis; S4, ultra-low temperature quick freezing: the roasted duck embryo is immediately sent into a quick freezing tunnel with a temperature of-45℃ to-50℃, the time of passing through the maximum ice crystal generation zone is controlled to be less than or equal to 3 minutes, and the center temperature of the product is reduced to below-18℃ within 7-8.5 minutes, so that a pre-roasted duck is prepared.

2. The roasted duck production process according to claim 1, characterized in that, In step S1, the humidity control of the low-temperature and high-velocity drying is as follows: the relative humidity is 75%-78% in the initial stage, and is gradually reduced to 55%-58% in the middle and later stages, and the weight loss rate is controlled to be 1.2%-1.5% / h; The initial stage is 0-6h, and the middle and later stages are 6-24h.

3. The roasted duck production process according to claim 1, characterized in that, In step S2, the gel soup is prepared from the following raw materials in percentage by mass: 4.5%-5.0% of a compounded hydrophilic colloid, 0.04%-0.05% of an enzymatic synergist, 0.46%-0.95% of salt, and the rest of base duck bone high soup; The compounded hydrophilic colloid is compounded from low-acyl gellan gum, konjac gum and kappa-carrageenan at a mass ratio of (1.5-2.5):1:1; The enzymatic synergist is compounded from bromelain and papain at a mass ratio of 3:1; The activity of the bromelain is greater than or equal to 50000U / g, and the activity of the papain is greater than or equal to 100000U / g.

4. The roasted duck production process according to claim 3, characterized in that, The preparation method of the gel soup comprises the following steps: the base duck bone high soup is heated to 85-90℃, the compounded hydrophilic colloid and the salt are added, and shearing stirring is performed at a speed of 900-1000rpm for 12-15 minutes until complete dissolution; after being cooled to 41-42℃, the enzymatic synergist is added, and stirring is performed at a speed of 150-250rpm for 1.5-2.5 minutes, and then cooling and shaping are performed at a temperature of 3-5℃.

5. The roasted duck production process according to claim 1, wherein, In step S2, the weak alkaline oil-water microemulsion permeate comprises the following components in percentage by mass: 28.0%-29.0% of an oil phase, 9.0%-9.5% of a reducing sugar compound, 1.0%-1.5% of a compounded emulsifier, and the rest of a water phase; The oil phase is refined duck oil, the reducing sugar compound is composed of glucose and xylose at a mass ratio of 3-5:1, and the compounded emulsifier is compounded from soybean lecithin and sucrose fatty acid ester at a mass ratio of 0.5-1.5:1; The average particle size of the dispersed phase droplets of the weak alkaline oil-water microemulsion permeate is 0.5-2.0μm.

6. The roasted duck production process according to claim 5, wherein, The preparation method of the weak alkaline oil-water microemulsion penetrating solution comprises the following steps: dissolving a reducing sugar compound in an aqueous phase to obtain an aqueous phase base; dissolving a compound emulsifier in refined duck oil at 63-65 DEG C to obtain an oil phase base; mixing the oil and water phases, shearing at 4000-5000 rpm for 4-5 min to obtain a primary emulsion, then homogenizing twice at 45-50 MPa, and finally adjusting the pH to 8.5+ / -0.5 with a sodium carbonate aqueous solution.

7. The roasted duck production process according to claim 2, wherein, In step S1, the air pressure for the air separation is 0.15-0.20 MPa, so that the separation degree of the subcutaneous fat layer and the muscle layer is more than 95%; the scalding is carried out by three immersions and three extractions in 98-99 DEG C boiling water, with a single contact time of 3-4 s and a total heat treatment time of 10-12 s.

8. The roasted duck production process according to claim 1, wherein, In step S3, the end point of the instant high-temperature impact roasting is determined according to the following indexes: the brightness value of the skin is 55.0-60.0, the redness value is 12.0-15.0, and the puffing layer thickness is 0.3-0.5 mm.

9. The roasted duck production process according to claim 1, wherein, In step S4, the air speed of the quick-freezing tunnel is 9-10 m / s, and the vacuum modified atmosphere packaging is stored in a refrigerator at -17 to -19 DEG C.

10. The roasted duck production process according to claim 1, wherein, The duck embryo has a size of 2.0-2.5 kg, the heating temperature of the sol-gel soup in step S2 is 45-48 DEG C, and the spray gun pressure for spraying the weak alkaline oil-water microemulsion penetrating solution is 0.3-0.5 MPa.