Frozen roasted duck product and method of making same

Abstract

This application relates to the field of food processing technology, specifically disclosing a frozen roast duck product and its preparation method. A method for preparing a frozen roast duck product includes the following steps: S1. A cooked and sliced ​​roast duck is placed in a quick-freezing environment within 10 minutes; S2. The roast duck is quick-frozen under conditions of a temperature ≤-80℃ and a strong airflow with a wind speed ≥5m / s, controlling the center temperature of the roast duck to drop from the initial temperature to ≤-5℃ within 30 minutes; wherein the time the roast duck remains in the temperature range of -1℃ to -5℃ is controlled to be ≤3 minutes; S3. The roast duck treated in S2 is stored in an environment of ≤-18℃; Furthermore, the preparation method of this application has the advantage of improving the quality of frozen roast duck products, ensuring that the thawed roast duck maintains good taste, flavor, and texture.

Description

Technical Field

[0001] This application relates to the field of food processing technology, and more specifically, to a frozen roast duck product and its preparation method. Background Technology

[0002] Roast duck is a traditional delicacy, beloved by consumers for its crispy skin, tender meat, bright red color, and rich aroma. Traditionally, roast duck is best enjoyed freshly roasted to ensure optimal taste and flavor. However, with the fast pace of life and changing consumption habits, consumers are increasingly demanding convenient, ready-to-eat roast duck products. To extend the shelf life of roast duck and facilitate transportation and storage, frozen roast duck products have emerged. These products are made by freezing roasted duck; consumers simply need to refrigerate them after purchase, offering the advantages of convenience and speed.

[0003] However, during the freezing process, existing frozen roast duck products are prone to damage to the muscle fiber structure and cell tissue of the roast duck due to the formation and growth of ice crystals. This leads to problems such as poor taste, dry meat, severe loss of juice, and separation of skin and meat after thawing. In particular, for roast ducks that have already been sliced, the exposed area of ​​the cut surface is larger, making them more susceptible to freezing damage and resulting in quality deterioration. In addition, traditional freezing methods are slow, and the roast duck stays in the maximum ice crystal formation zone of -1°C to -5°C for a long time, which will form larger ice crystals and cause irreversible damage to the tissue structure of the roast duck. Summary of the Invention

[0004] In order to improve the quality of frozen roast duck products and maintain good taste, flavor and texture after thawing, this application provides a method for preparing frozen roast duck products.

[0005] In a first aspect, this application provides a method for preparing frozen roast duck products, employing the following technical solution: A method for preparing frozen roast duck products includes the following steps: S1. Place the cooked and sliced ​​roast duck into a quick-freezing environment within 10 minutes; S2. Under the conditions of temperature ≤-80℃ and strong wind speed ≥5m / s, the roast duck is quick-frozen, and the core temperature of the roast duck is controlled to drop from the initial temperature to ≤-5℃ within 30 minutes; wherein, the time of the roast duck in the temperature range of -1℃ to -5℃ is controlled to be ≤3 minutes. S3. Store the roast duck treated in S2 at an environment of ≤-18℃.

[0006] By adopting the above technical solution, the cooked and sliced ​​roast duck is placed in a quick-freezing environment within 10 minutes, which reduces the time the roast duck stays at room temperature, thereby reducing the risk of microbial contamination and quality deterioration. Quick-freezing under ultra-low temperature conditions of ≤-80℃ and strong airflow with a wind speed of ≥5m / s significantly increases the freezing speed, allowing the core temperature of the roast duck to drop to ≤-5℃ within 30 minutes. Controlling the time the roast duck stays in the maximum ice crystal formation zone to ≤3 minutes, the ultra-fast freezing speed ensures that the ice crystals are small in size and evenly distributed, minimizing mechanical damage to the duck's muscle fibers and cell tissues, thus effectively protecting the duck's textural properties. Simultaneously, the strong airflow accelerates heat exchange, further improving freezing efficiency. The resulting frozen roast duck retains its excellent taste, flavor, and texture after thawing, with crispy skin, tender meat, and abundant juice, significantly improving the quality of the frozen roast duck product.

[0007] Preferably, the wind speed of the strong airflow is 6-12 m / s.

[0008] By adopting the above technical solution, controlling the wind speed of the strong airflow to 6-12m / s can further improve freezing efficiency, shorten freezing time, and at the same time avoid excessive wind speed causing the surface of the roast duck to dry or suffer physical damage.

[0009] Preferably, the quick-freezing environment is a tunnel-type quick-freezing device.

[0010] By adopting the above technical solutions, the tunnel-type quick-freezing device has good continuous production capacity and stable freezing effect.

[0011] Preferably, the quick-freezing process employs a three-stage gradient freezing method: Level 1: Under conditions of -35℃ to -40℃, forced convection air cooling is used with a wind speed ≥8m / s and a treatment time of 15-25min. Level 2: Surface spraying treatment using an edible colloidal coating liquid at -25℃ to -30℃, wherein the edible colloidal coating liquid contains the following percentages of raw materials: 0.3% sodium alginate, 0.1% gellan gum, and the balance being water; Level 3: Under conditions of -18℃ to -20℃, directional airflow impact treatment is adopted, with an airflow speed of 3-5m / s, until the center temperature of the roast duck reaches -18℃.

[0012] By adopting the above technical solution, a three-stage gradient freezing process can achieve more precise control of the freezing process. The first stage, forced convection circulating air cooling, can quickly reduce the surface temperature of the roast duck and form an initial frozen layer. The second stage uses an edible colloidal coating liquid for surface spraying treatment. Sodium alginate and gellan gum can form a protective film on the surface of the roast duck, reducing moisture loss during freezing and preventing surface drying and oxidation. The third stage, directional airflow impact treatment, can make the center temperature of the roast duck drop evenly to the target temperature. The three-stage gradient freezing works together to ensure freezing speed, reduce freezing damage, and improve the quality of frozen roast duck.

[0013] Preferably, before the first stage of forced convection air cooling, a pre-cooling stage of pulsed pressurization injection is included: under 0-4℃ conditions, the composite antifreeze agent is injected into the subcutaneous fat layer by pulsed pressurization, wherein the pressure of the pulsed pressurization is 0.1-0.2MPa, the pressurization holding time is 1min, the pressure release time is 2min, and the cycle is repeated 3-5 times.

[0014] By adopting the above technical solution, the compound cryoprotectant is injected into the subcutaneous fat layer through pulsating pressurization during the pre-cooling stage. The alternating pulsating pressurization can promote the penetration of the cryoprotectant into the tissue, so that the cryoprotectant is evenly distributed in the subcutaneous fat layer and the gap between muscle tissue. The cryoprotectant can inhibit ice crystal growth, reduce freezing damage, and protect the integrity of cell membrane structure, thereby further improving the quality of roast duck after thawing.

[0015] Preferably, the composite antifreeze agent comprises the following percentages of raw materials: 1-2% whey protein, 2% maltodextrin, 0.05% tea polyphenols, and the balance being water.

[0016] By adopting the above technical solutions, whey protein has good hydration capacity and film-forming properties, which can protect the protein structure and reduce denaturation during freezing; maltodextrin can bind with water, reduce free water content, and inhibit ice crystal growth; tea polyphenols have antioxidant effects and can inhibit fat oxidation and color deterioration during freezing. The combination of the three has a synergistic effect and can effectively improve the antifreeze protection effect.

[0017] Preferably, before the quick-freezing process in S2, a vacuum tumbling pretreatment step is included for the cooked and sliced ​​roast duck. The treatment liquid used in the vacuum tumbling process contains trehalose and sodium citrate. The amount of trehalose added is 0.3 wt% of the weight of the roast duck, and the amount of sodium citrate added is 0.5 wt% of the weight of the roast duck.

[0018] By adopting the above technical solution, vacuum tumbling pretreatment allows trehalose and sodium citrate in the treatment solution to penetrate evenly into the interior of the roast duck tissue. Trehalose is an excellent natural antifreeze agent that can stabilize cell membrane structure and reduce freezing damage; sodium citrate has a water-retaining effect, which can reduce juice loss after thawing; and the mechanical action of vacuum tumbling can also loosen muscle fibers and improve the tenderness of the product.

[0019] Preferably, during the quick-freezing process in S2, ultrasonic-assisted treatment at a frequency of 20-40 kHz is performed, with an ultrasonic power density of 0.5-1.5 W / cm³. 2 .

[0020] By adopting the above technical solutions, ultrasonic-assisted treatment can promote uniform nucleation of ice crystals, inhibit the growth of large ice crystals, make the ice crystals smaller and more uniformly distributed, and the cavitation effect of ultrasound can enhance the heat transfer process, further improving the freezing speed and freezing efficiency.

[0021] Secondly, this application provides a frozen roast duck product, which adopts the following technical solution: A frozen roast duck product is prepared by a method for preparing frozen roast duck products.

[0022] By adopting the above technical solution, the resulting frozen roast duck products have good quality. After thawing, they are tender, juicy, and retain their flavor well, overcoming the problems of traditional frozen roast duck products being dry and losing a lot of juice.

[0023] In summary, this application has the following beneficial effects: 1. Because this application uses ultra-low temperature strong airflow quick-freezing technology, the time that the roast duck stays in the maximum ice crystal formation zone is controlled to be ≤3min, so that the ice crystals are small and uniform, avoiding mechanical damage to the tissue structure of the roast duck, thus effectively protecting the textural characteristics of the roast duck, and maintaining good taste, flavor and texture after thawing.

[0024] 2. This application adopts a three-stage gradient freezing process, combined with forced convection cooling, edible colloidal coating and directional airflow impact treatment, to achieve precise control of the freezing process, which not only ensures the freezing speed but also reduces freezing damage and improves the quality of frozen roast duck.

[0025] 3. This application also uses pulsed pressure injection of composite antifreeze protectant, vacuum tumbling pretreatment and ultrasonic-assisted treatment to further improve the antifreeze effect, reduce moisture loss and fat oxidation, and make the roast duck after thawing maintain a better taste, color and flavor. Detailed Implementation

[0026] The present application will be further described in detail below with reference to the embodiments. Preparation example of composite antifreeze agent

[0027] Preparation Example 1 The compound antifreeze contains the following percentages of ingredients: 1.5% whey protein, 2% maltodextrin, 0.05% tea polyphenols, and the remainder is water.

[0028] Add whey protein, maltodextrin, and tea polyphenols to water and stir at 25°C until completely dissolved to obtain a composite antifreeze agent. Preparation example of edible colloidal coating solution

[0029] Preparation Example 2 The edible colloidal coating solution contains the following percentages of raw materials: 0.3% sodium alginate, 0.1% gellan gum, and the balance being water.

[0030] Sodium alginate and gellan gum are added to water and heated and stirred in a 60°C water bath until completely dissolved. The solution is then cooled to room temperature to obtain an edible colloidal coating solution. Example

[0031] Example 1 A method for preparing frozen roast duck products includes the following steps: S1. The cooked and sliced ​​roast duck is placed into a tunnel-type quick-freezing device within 8 minutes. S2. Under conditions of -85℃ temperature and strong wind speed of 8m / s, the roast duck is quick-frozen, and the core temperature of the roast duck is controlled to drop from the initial temperature to -5℃ within 25 minutes; wherein, the time of the roast duck in the temperature range of -1℃ to -5℃ is controlled to be 2.5 minutes. S3. Store the roast duck treated in S2 at -20℃.

[0032] Example 2

[0033] A method for preparing frozen roast duck products includes the following steps: S1. The cooked and sliced ​​roast duck is placed into a tunnel-type quick-freezing device within 5 minutes. S2. Quick-freezing treatment employs a three-stage gradient freezing process: Level 1: Under conditions of -38℃, forced convection air cooling is used with a wind speed of 9m / s and a treatment time of 20min. Second stage: At -28°C, the edible colloidal coating liquid prepared in Preparation Example 2 was used for surface spraying treatment, with the spraying amount being 2% of the weight of the roast duck; Level 3: At -19℃, a directional airflow impact treatment is used with an airflow speed of 4m / s until the center temperature of the roast duck reaches -18℃. S3. Store the roast duck treated in S2 at -20℃.

[0034] Example 3

[0035] The difference between Example 3 and Example 1 is that in Example 3, during the quick-freezing process in S2, ultrasonic-assisted treatment with a frequency of 30kHz and an ultrasonic power density of 0.5W / cm² is performed.

[0036] Example 4

[0037] The difference between Example 4 and Example 1 is that in Example 4, during the quick-freezing process in S2, ultrasonic-assisted treatment with a frequency of 30kHz and an ultrasonic power density of 1.5W / cm² is performed.

[0038] Example 5

[0039] The difference between Example 5 and Example 1 is that in Example 5, during the quick-freezing process in S2, ultrasonic-assisted treatment with a frequency of 30kHz and an ultrasonic power density of 0.2W / cm² is performed.

[0040] Example 6

[0041] The difference between Example 6 and Example 1 is that in Example 6, during the quick-freezing process in S2, ultrasonic-assisted treatment with a frequency of 30kHz and an ultrasonic power density of 2.5W / cm² is performed.

[0042] Example 7

[0043] The difference between Example 7 and Example 1 is that in Example 7, before the first stage of forced convection air cooling, a pre-cooling stage of pulsed pressurization injection is included: at 2°C, the composite antifreeze agent prepared in Example 1 is injected into the subcutaneous fat layer by pulsed pressurization. The pressure of pulsed pressurization is 0.15 MPa, the pressurization time is 1 min, the pressure release time is 2 min, and the cycle is repeated 4 times.

[0044] Example 8

[0045] The difference between Example 8 and Example 7 is that in Example 8, the pressure of the pulsating pressurization is 0.1 MPa, and the cycle is repeated 3 times.

[0046] Example 9

[0047] The difference between Example 9 and Example 7 is that in Example 9, the pressure of the pulsating pressurization is 0.2 MPa, and the cycle is 5 times.

[0048] Example 10

[0049] The difference between Example 10 and Example 7 is that in Example 10, the pressure of the pulsating pressurization is 0.05 MPa, and the cycle is 4 times.

[0050] Example 11

[0051] The difference between Example 11 and Example 7 is that in Example 11, the pressure of the pulsating pressurization is 0.35 MPa, and the cycle is 4 times. Comparative Example

[0052] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that in Comparative Example 1, the temperature of quick-freezing treatment is -30℃, the wind speed is 2m / s, and the time the roast duck stays in the temperature range of -1℃ to -5℃ is 8min.

[0053] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that in Comparative Example 2, the cooked and sliced ​​roast duck was placed in the quick-freezing environment 30 minutes later. Performance testing

[0054] Frozen roast duck products were prepared according to the preparation methods of Examples 1-11 and Comparative Examples 1-2. After being frozen and stored at -18°C for 30 days, the products were taken out and their microstructure was observed: the morphology of ice crystals and cell integrity of muscle tissue were observed using a scanning electron microscope, and the average diameter of ice crystals was measured. Then, after thawing at 4℃ for 1 hour, the thawed roast duck was reheated by heating it in an air fryer at 110℃ for 7 minutes, and the following performance tests were conducted. The results are recorded in Table 1.

[0055] Juice loss rate determination: Weigh the frozen roast duck before thawing (m1) and after thawing, weigh it with absorbent paper to remove surface moisture (m2). Calculate the juice loss rate according to the formula: Juice loss rate (%) = (m1-m2) / m1×100%.

[0056] Texture properties determination: The crispness and tenderness of roast duck skin and duck meat were determined using a texture analyzer; crispness was expressed as breaking force, with a smaller breaking force indicating greater crispness; tenderness was expressed as shear force, with a smaller shear force indicating greater tenderness.

[0057] Cortical porosity determination: Microscopic image analysis was used to calculate the proportion of pore area per unit area of ​​the cortex, and the porosity retention rate was calculated by comparing with that of fresh roast duck.

[0058] Sensory evaluation: A sensory evaluation team of 20 trained food professionals was invited to conduct sensory evaluation of the thawed and reheated roast duck. The evaluation items included appearance and color (10 points), crispness (10 points), tenderness (10 points), flavor intensity (10 points), and juiciness (10 points), for a total score of 50 points.

[0059] Table 1. Quality test results of frozen roast duck products project Average ice crystal diameter / μm Juice loss rate / % Crispy Duck Skin / N Duck meat tenderness / N Cortical porosity retention rate / % Sensory total score Example 1 18 5.23 8.14 12.35 88 42.6 Example 2 14 4.56 7.54 11.23 91 45.1 Example 3 13 4.12 7.21 10.65 90 46.2 Example 4 12 4.08 7.15 10.58 91 46.4 Example 5 17 5.01 7.98 11.98 86 43.0 Example 6 19 5.34 8.32 12.56 84 41.8 Example 7 10 3.89 6.87 10.12 93 47.2 Example 8 12 4.12 7.12 10.56 91 46.3 Example 9 11 3.95 6.96 10.31 92 46.9 Example 10 15 4.68 7.56 11.45 87 44.2 Example 11 16 5.12 8.05 12.18 85 42.8 Comparative Example 1 65 10.23 12.65 18.92 62 32.5 Comparative Example 2 48 8.94 11.23 16.87 70 35.8 As can be seen from Table 1, Examples 1-2 and Comparative Examples 1-2, the frozen roast duck products prepared in Examples 1-2 have a lower juice loss rate, good duck skin crispness and duck meat tenderness, smaller average ice crystal diameter, higher skin porosity retention rate, and a significantly better overall sensory score than the comparative examples. Examples 1-2 adopted quick-freezing treatment under strong airflow conditions of ≤-80℃ temperature and ≥5m / s wind speed, and controlled the residence time of the roast duck in the maximum ice crystal formation zone of -1℃ to -5℃ to ≤3min. The ultra-low temperature combined with strong airflow for rapid heat exchange resulted in small and uniform ice crystal formation, which greatly reduced mechanical damage to muscle fibers and cell tissues, thereby effectively reducing juice loss and maintaining the crispy taste of duck skin and tender texture of duck meat after reheating.

[0060] In contrast, Comparative Example 1 had a higher freezing temperature and slower airflow, resulting in a dwell time of up to 8 minutes in the maximum ice crystal formation zone. This led to large ice crystals, severely damaging the tissue structure and causing a juice loss rate as high as 10.23%, significantly deteriorating the taste. Comparative Example 2 was not placed in the quick-freezing environment in time, and its initial quality had already declined, further affecting the sensory score of the final product.

[0061] As can be seen from Table 1, Examples 3-4, and Example 1, Examples 3-4 applied a frequency of 30kHz and a power density of 0.5W / cm² during the quick-freezing process. 2 and 1.5W / cm 2 Ultrasonic-assisted treatment further reduced the juice loss rate, improved the crispness of the duck skin and the tenderness of the duck meat, reduced the average diameter of ice crystals, and improved the overall sensory score. This indicates that the cavitation effect of ultrasound promoted uniform nucleation of ice crystals, inhibited the growth of large ice crystals, and made the ice crystals smaller and more evenly distributed. At the same time, ultrasound enhanced the heat transfer process, further shortened the freezing time, and thus better protected the tissue structure and textural properties of the roast duck. However, the ultrasonic power density in Example 5 was too low, the cavitation effect was insufficient, and the effect was not obvious. The ultrasonic power density in Example 6 was too high, which may have caused excessive mechanical vibration damage to the roast duck tissue, resulting in an increase in the juice loss rate and a decrease in the overall sensory score. This shows that an appropriate ultrasonic power density is crucial for improving the assisted freezing effect.

[0062] As can be seen from Table 1, Examples 7-9 and Examples 1 and 5, Examples 7-9 added a step of pulsating pressurized injection of the composite cryoprotectant during the pre-cooling stage. Among them, Example 7 showed the best effect, indicating that the alternating changes in pulsating pressurization promoted the uniform penetration of the composite cryoprotectant into the subcutaneous fat layer and the interstitial space of muscle tissue. Whey protein protected the protein structure and reduced denaturation, maltodextrin bound free water to inhibit ice crystal growth, and tea polyphenols inhibited fat oxidation. The synergistic effect of the three significantly reduced freezing damage. However, the pressure in Example 10 was too low, resulting in insufficient penetration; the pressure in Example 11 was too high, which may have caused mechanical compression damage to the tissue, resulting in a poor effect.

[0063] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for preparing frozen roast duck products, characterized in that, Includes the following steps: S1. Place the cooked and sliced ​​roast duck into a quick-freezing environment within 10 minutes; S2. Under the conditions of temperature ≤-80℃ and strong wind speed ≥5m / s, the roast duck is quick-frozen, and the core temperature of the roast duck is controlled to drop from the initial temperature to ≤-5℃ within 30 minutes; wherein, the time of the roast duck in the temperature range of -1℃ to -5℃ is controlled to be ≤3 minutes. S3. Store the roast duck treated in S2 at an environment of ≤-18℃.

2. The method for preparing a frozen roast duck product according to claim 1, characterized in that, The wind speed of the strong airflow is 6-12 m / s.

3. The method for preparing a frozen roast duck product according to claim 1, characterized in that, The quick-freezing environment is a tunnel-type quick-freezing device.

4. The method for preparing a frozen roast duck product according to claim 1, characterized in that, The quick-freezing process employs a three-stage gradient freezing method: Level 1: Under conditions of -35℃ to -40℃, forced convection air cooling is used with a wind speed ≥8m / s and a treatment time of 15-25min. Level 2: Surface spraying treatment using an edible colloidal coating liquid at -25℃ to -30℃, wherein the edible colloidal coating liquid contains the following percentages of raw materials: 0.3% sodium alginate, 0.1% gellan gum, and the balance being water; Level 3: Under conditions of -18℃ to -20℃, directional airflow impact treatment is adopted, with an airflow speed of 3-5m / s, until the center temperature of the roast duck reaches -18℃.

5. The method for preparing a frozen roast duck product according to claim 4, characterized in that, Before the first stage of forced convection air cooling, a pre-cooling stage of pulsed pressurization injection is also included: under 0-4℃ conditions, the composite antifreeze is injected into the subcutaneous fat layer by pulsed pressurization. The pressure of the pulsed pressurization is 0.1-0.2MPa, the pressurization time is 1min, the pressure release time is 2min, and the cycle is repeated 3-5 times.

6. The method for preparing a frozen roast duck product according to claim 5, characterized in that, The composite antifreeze contains the following percentages of raw materials: 1-2% whey protein, 2% maltodextrin, 0.05% tea polyphenols, and the remainder is water.

7. The method for preparing a frozen roast duck product according to claim 1, characterized in that, Before the quick-freezing process in S2, a vacuum tumbling pretreatment step is also included for the cooked and sliced ​​roast duck. The treatment liquid used in the vacuum tumbling process contains trehalose and sodium citrate. The amount of trehalose added is 0.3 wt% of the weight of the roast duck, and the amount of sodium citrate added is 0.5 wt% of the weight of the roast duck.

8. The method for preparing a frozen roast duck product according to claim 1, characterized in that, During the quick-freezing process of S2, ultrasonic-assisted treatment at a frequency of 20-40 kHz and an ultrasonic power density of 0.5-1.5 W / cm³ is performed. 2 .

9. A frozen roast duck product, characterized in that, The product is prepared by any one of the following methods: a frozen roast duck product according to claims 1-8.