Quick-frozen roast duck and preparation method thereof

Abstract

The invention belongs to the technical field of food processing, and discloses a quick-frozen roast duck and a preparation method thereof. The preparation method comprises the following steps: spraying a tea polyphenol solution on a duck, baking, carrying out first vacuum cooling treatment, spraying an acid solution, and carrying out second vacuum cooling treatment and quick-freezing treatment. The production and accumulation of a large amount of carboxy methyl lysine in the processing and freezing storage process of the quick-frozen roast duck are avoided, so that the quick-frozen roast duck can still keep relatively low carboxy methyl lysine content after being frozen and stored for a long time. After the quick-frozen roast duck is frozen and preserved for 6 months, the content of carboxymethyl lysine is still lower than 2.5 mg / kg.

Description

Technical Field

[0001] The invention relates to the technical field of food processing, and in particular to a quick-frozen roast duck and a preparation method thereof. Background Art

[0002] Roast duck is a traditional meat product in my country. It is usually made of stuffed duck with distinct fat and lean parts and thick subcutaneous fat. It is prepared through processes such as pickling, sugaring, and roasting. It has the characteristics of bright red color, tender meat, mellow taste, fat but not greasy. It is well-known at home and abroad and is deeply loved by consumers. However, roast duck is not resistant to storage. The existing technology usually preserves roast duck after vacuum packaging, but even with refrigeration, its shelf life can only reach about 15 days. In the refrigeration process, roast duck is still susceptible to a series of changes in properties caused by microorganisms and enzymes, resulting in odor, which reduces the sensory quality. Quick-freezing the existing roast duck to make quick-frozen roast duck and freezing it at -18℃ can effectively inhibit the enzyme activity and microbial growth in roast duck, and protect the water holding capacity of protein in roast duck. Compared with other storage methods, it can maintain the sensory quality of roast duck to the greatest extent and extend its shelf life to 6 months or more. However, during the roasting process, roast duck will produce carboxymethyl lysine through the Maillard reaction. This substance is the main biomarker of advanced glycation end products. In the human body, it will bind to the specific receptors of tissue cells and destroy the functional characteristics of cells. In addition, it has a low metabolic rate in the human body. Long-term accumulation will threaten human health and cause a variety of chronic diseases such as atherosclerosis, Alzheimer's disease, and coronary heart disease. The content of carboxymethyl lysine in the roast duck that has just been roasted is generally 3 mg / kg or more. If the roast duck is frozen and then stored, carboxymethyl lysine will be further slowly generated during the frozen storage process. After 30 days of storage, its carboxymethyl lysine content will accumulate to 10 mg / kg or more. If the storage time is extended, more carboxymethyl lysine will be generated and accumulated in the quick-frozen roast duck, which in turn limits the development of quick-frozen roast duck. Summary of the invention

[0003] Based on the above reasons, the first purpose of the present invention is to provide a method for preparing quick-frozen roast duck, in which the duck is sprayed with a tea polyphenol solution and then roasted, subjected to a first vacuum cooling treatment, and then sprayed with an acid solution for a second vacuum cooling and quick freezing treatment, thereby avoiding the production and accumulation of a large amount of carboxymethyllysine during the processing and frozen storage of the roast duck.

[0004] The second object of the present invention is to provide a quick-frozen roast duck prepared according to the above preparation method.

[0005] In order to achieve the above object, in a first aspect, the present invention provides a method for preparing a quick-frozen roast duck, comprising the following steps: After being sprayed with tea polyphenol solution, the duck is roasted, subjected to a first vacuum cooling treatment, and then sprayed with acid solution, subjected to a second vacuum cooling treatment and quick-frozen treatment.

[0006] Furthermore, the solubility of the tea polyphenols solution is 1%-3%.

[0007] Furthermore, the dosage of the tea polyphenol solution is 0.6%-1% of the weight of the duck.

[0008] Furthermore, the acid in the acid solution is one or more of ascorbic acid, malic acid, citric acid, and lactic acid.

[0009] Furthermore, the concentration of the acid solution is 0.6%-0.8%.

[0010] Furthermore, the amount of the acid solution used is 0.3%-0.6% of the weight of the duck.

[0011] Furthermore, the vacuum degree of the first vacuum cooling treatment is 0.004-0.006 MPa, and the time is 8-10 min.

[0012] Furthermore, the vacuum degree of the second vacuum cooling treatment is 0.004-0.006 MPa, and the time is 10-12 min.

[0013] In a second aspect, the present invention provides a quick-frozen roast duck prepared by any of the aforementioned methods for preparing quick-frozen roast duck.

[0014] Furthermore, the quick-frozen roast duck is frozen and preserved at -18°C.

[0015] The beneficial effects of the present invention are: The present invention sprays the duck with a tea polyphenol solution, sprays the duck with an acid solution after roasting, and simultaneously performs a first vacuum cooling treatment and a second vacuum cooling treatment, thereby effectively delaying the generation and accumulation of carboxymethyl lysine in the quick-frozen roast duck during processing and frozen storage, so that the quick-frozen roast duck still maintains a low carboxymethyl lysine content after long-term frozen storage.

[0016] The quick-frozen roast duck of the present invention has a relatively low carboxymethyl lysine content, which is lower than 2.5 mg / kg, after being frozen and stored for 6 months. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical scheme and advantages of the present invention clearer, the scheme of the present invention is further described in detail below in conjunction with embodiment.It will be appreciated by those skilled in the art that the following examples are exemplary only, and are not intended to limit the scope of the present invention.In addition, in the following description, those not indicating specific conditions in the examples are carried out according to the conditions of normal conditions or manufacturer's recommendations.Reagents used or instruments not indicating manufacturers are conventional products that can be obtained by commercial purchase.

[0018] Existing roast ducks are generally prepared through processes such as pickling, sugaring, and roasting, and are stored after vacuum packaging, but even with refrigeration, their shelf life is short. Quick-freezing the roast duck and then freezing it can prevent its skin from being crispy and its taste from being reduced, but the roast duck will produce carboxymethyl lysine through the Maillard reaction during the roasting process. If it is further quick-frozen and frozen, the structure and conformation of the protein rich in the roast duck will gradually change as the frozen storage time increases, causing it to produce and accumulate more carboxymethyl lysine.

[0019] In view of this, a first embodiment of the present invention provides a method for preparing a quick-frozen roast duck, comprising the following steps: After being sprayed with tea polyphenol solution, the duck is roasted, subjected to a first vacuum cooling treatment, and then sprayed with acid solution, subjected to a second vacuum cooling treatment and quick-frozen treatment.

[0020] It should be noted that, in the present embodiment, the effect of the tea polyphenol solution is to delay the production and accumulation of carboxymethyl lysine in the quick-frozen roast duck during processing and frozen storage. Tea polyphenols is an antioxidant, which has been used in many types of food such as meat products, rice and flour products, seasonings, beverages, etc., but is mostly used to control the production of carboxymethyl lysine in food during processing. There are few reports on the influence of tea polyphenols on the formation of carboxymethyl lysine during food storage, especially during frozen storage. The applicant has found in long-term research that spraying tea polyphenol solution on the surface of the duck and then baking it can not only avoid the duck from generating more carboxymethyl lysine during baking, but also delay its production and accumulation of carboxymethyl lysine in subsequent quick freezing and frozen storage processes. This may be because during baking, tea polyphenols are gradually decomposed into catechins due to high temperature and enter the duck, so that the acidity of the duck is enhanced, thereby delaying its production and accumulation of carboxymethyl lysine in subsequent quick freezing and frozen storage processes.

[0021] It should be noted that the solubility of the tea polyphenol solution in the present embodiment is 1%-3%, and the dosage is 0.6%-1% of the duck's weight. Reducing the concentration and dosage of the tea polyphenol solution will result in poor effects due to the low content of tea polyphenol and subsequent catechin components, while increasing the concentration and dosage of the tea polyphenol solution will result in the usage of tea polyphenol exceeding the maximum usage in smoked, roasted, and grilled meat foods specified in GB 2760-2014 "National Food Safety Standard for the Use of Food Additives". In addition, other antioxidants specified in GB2760-2014 "National Food Safety Standard for the Use of Food Additives" that can be used in smoked, roasted, and grilled meat foods, such as bamboo leaf antioxidants, rosemary extract, calcium propionate, etc., can also control the production of more carboxymethyl lysine in the quick-frozen roast duck during the roasting process, but cannot significantly delay the production and accumulation of carboxymethyl lysine in the quick-frozen roast duck during processing and frozen storage.

[0022] Furthermore, it should be noted that the use of the above tea polyphenol solution can only keep the carboxymethyl lysine content of the quick-frozen roast duck at a low level within 1 month of frozen storage. If the frozen storage time is too long, such as extended to 6 months, the carboxymethyl lysine content in the quick-frozen roast duck will still gradually accumulate to 10 mg / kg or more. In view of the above situation, the applicant further found that after the duck is roasted, the acid spraying and then quick freezing can further delay the production and accumulation of carboxymethyl lysine in the quick-frozen roast duck during subsequent processing and frozen storage, so that the quick-frozen roast duck still maintains a low carboxymethyl lysine content after 6 months of frozen storage.

[0023] In this embodiment, the acid in the acid solution is one or more of ascorbic acid, malic acid, citric acid, and lactic acid, the concentration of the acid solution is 0.6%-0.8%, and the amount of the acid solution is 0.3%-0.6% of the mass of the duck.

[0024] It should be noted that, in this embodiment, the purpose of the first vacuum cooling treatment is to reduce the temperature of the roasted duck to room temperature, avoid high temperature from decomposing the components in the acid solution, and prevent the duck from oxidizing during the cooling process to generate carboxymethyllysine. The purpose of the second vacuum cooling treatment is to promote the acid solution to enter the roasted duck, so as to effectively reduce the content of carboxymethyllysine in the quick-frozen roast duck.

[0025] In a specific embodiment, the vacuum degree of the first vacuum cooling treatment is 0.004-0.006 MPa, and the time is 8-10 min. This treatment can quickly reduce the temperature of the roasted duck to room temperature; the vacuum degree of the second vacuum cooling treatment is 0.004-0.006 MPa, and the time is 10-12 min.

[0026] It should be noted that, in the present embodiment, the duck is a stuffed duck with distinct fat and lean parts. Before spraying with the tea polyphenol solution, the duck also undergoes a series of pre-treatments including slaughtering, scalding, plucking, gutting, cleaning, scalding and pickling. After spraying with the tea polyphenol solution, the duck also undergoes a sugar-coating treatment. The aforementioned series of pre-treatments and sugar-coating treatments are all conventional processes in the preparation of roast duck.

[0027] In this embodiment, the duck is roasted at a temperature of 190-210° C. for 40-50 minutes.

[0028] In this embodiment, the quick-freezing temperature of the duck is 50-55°C. The quick-freezing time can be conventionally adjusted according to the specific size of the duck. This embodiment does not make any specific limitation. The duck can be quick-frozen until the core temperature is -18°C.

[0029] The second embodiment of the present invention provides a quick-frozen roast duck prepared according to the above preparation method. The quick-frozen roast duck is frozen and stored at -18°C, and the carboxymethyl lysine content of the quick-frozen roast duck is still less than 2.5 mg / kg after 6 months of storage.

[0030] Specific embodiments for implementing the present invention will be disclosed below, as well as corresponding comparative examples to demonstrate the relevant technical effects of the present invention.

[0031] Example 1 Preparation of quick-frozen roast duck The ducks were selected to be clearly fat and lean, and after being slaughtered, scalded, plucked, gutted, cleaned, scalded and pickled, they were sprayed with a 1% tea polyphenol solution, the amount of which was 0.6% of the duck's weight, and then the ducks were treated with sugar and roasted at 200℃ for 45 min to obtain roast ducks. The roast duck was subjected to a first vacuum cooling treatment at a vacuum degree of 0.005 MPa for 9 minutes, and then sprayed with an ascorbic acid solution with a concentration of 0.7% and subjected to a second vacuum cooling treatment at a vacuum degree of 0.005 MPa for 11 minutes, wherein the amount of the ascorbic acid solution was 0.45% of the duck's mass. The duck was then quick-frozen at -53°C until the center temperature of the duck was -18°C, thereby obtaining a quick-frozen roast duck.

[0032] Example 2 Preparation of quick-frozen roast duck The ducks were selected to be fat and lean, and after being slaughtered, scalded, plucked, gutted, cleaned, scalded and pickled, they were sprayed with 2% tea polyphenol solution, the amount of which was 0.8% of the duck's weight. The ducks were then sugared and roasted at 190℃ for 50 min to obtain roast ducks. The roast duck was subjected to a first vacuum cooling treatment at a vacuum degree of 0.004 MPa for 10 min, and then sprayed with a 0.6% malic acid solution and subjected to a second vacuum cooling treatment at a vacuum degree of 0.006 MPa for 10 min, wherein the amount of the malic acid solution was 0.3% of the duck's mass. The duck was then quick-frozen at -50°C until the center temperature of the duck was -18°C, thereby obtaining a quick-frozen roast duck.

[0033] Example 3 Preparation of quick-frozen roast duck The ducks were selected to be fat and lean, and after being slaughtered, scalded, plucked, gutted, cleaned, scalded and pickled, they were coated with a 3% tea polyphenol solution, the amount of which was 1% of the duck's weight. The ducks were then sugared and roasted at 210℃ for 40 min to obtain roast ducks. The roast duck was subjected to a first vacuum cooling treatment at a vacuum degree of 0.006 MPa for 8 min, and then sprayed with a 0.8% citric acid solution and subjected to a second vacuum cooling treatment at a vacuum degree of 0.004 MPa for 12 min, wherein the amount of the citric acid solution was 0.6% of the duck's mass. The duck was then quick-frozen at -55°C until the center temperature of the duck was -18°C, thereby obtaining a quick-frozen roast duck.

[0034] Comparative Example 1 Preparation of Quick-Frozen Roast Duck The quick-frozen roast duck is prepared by traditional technology, and the specific preparation method is as follows: Select the stuffed duck with distinct fat and lean parts, slaughter, scald, remove the hair, gut, clean, scald the skin and pickle it, then hang sugar and bake it at 200℃ for 45 minutes to obtain the roast duck; The roast duck is quick-frozen at -53°C until the center temperature of the roast duck is -18°C to obtain a quick-frozen roast duck.

[0035] Comparative Example 2 Preparation of Quick-Frozen Roast Duck The preparation method is the same as that of Example 1, except that the step of spraying the tea polyphenol solution is omitted in Comparative Example 2.

[0036] Comparative Example 3 Preparation of Quick-Frozen Roast Duck The preparation method is the same as that of Example 1, except that the concentration of the tea polyphenol solution in Comparative Example 3 is 0.8%.

[0037] Comparative Example 4 Preparation of Quick-Frozen Roast Duck The preparation method is the same as that in Example 1, except that the amount of the tea polyphenol solution in Comparative Example 4 is 0.5%.

[0038] Comparative Example 5 Preparation of Quick-Frozen Roast Duck The preparation method is the same as that of Example 1, except that in Comparative Example 5, the tea polyphenol solution is replaced by the bamboo leaf antioxidant solution.

[0039] Comparative Example 6 Preparation of Quick-Frozen Roast Duck The preparation method is the same as that of Example 1, except that in Comparative Example 6, rosemary extract solution is used to replace the tea polyphenol solution.

[0040] Comparative Example 7 Preparation of Quick-Frozen Roast Duck The preparation method is the same as that of Example 1, except that in Comparative Example 7, calcium propionate solution is used to replace the tea polyphenol solution.

[0041] Comparative Example 8 Preparation of Quick-Frozen Roast Duck The preparation method is the same as that of Example 1, except that the step of spraying the ascorbic acid solution is omitted in Comparative Example 8.

[0042] Comparative Example 9 Preparation of Quick-Frozen Roast Duck The preparation method is the same as that of Example 1, except that, in Comparative Example 9, the first vacuum cooling treatment step is omitted, and the ascorbic acid solution is directly sprayed on the duck after roasting.

[0043] Comparative Example 10 Preparation of Quick-Frozen Roast Duck The preparation method is the same as that of Example 1, except that, in Comparative Example 10, the second vacuum cooling treatment step is omitted.

[0044] Comparative Example 11 Preparation of Quick-Frozen Roast Duck The preparation method is the same as that in Example 1, except that the first vacuum cooling treatment in Comparative Example 11 is replaced by a natural cooling treatment under normal pressure.

[0045] Comparative Example 12 Preparation of Quick-Frozen Roast Duck The preparation method is the same as that in Example 1, the difference is that in Comparative Example 12, the first vacuum cooling treatment is replaced by a natural cooling treatment under normal pressure, and the second vacuum cooling treatment step is eliminated.

[0046] Test Example Determination of Carboxymethyl Lysine Content The quick-frozen roast ducks of Examples 1-3 and Comparative Examples 1-12 were placed in -18°C for frozen storage, and the carboxymethyl lysine content of the samples stored for 0 days, 1 month, 2 months and 6 months was determined. The carboxymethyl lysine content is the sum of the bound and free carboxymethyl lysine contents, and the determination method is enzyme-linked immunosorbent assay, which is carried out according to the kit operating instructions. The determination results are shown in Table 1.

[0047] Table 1 Determination results of carboxymethyl lysine content in quick-frozen roast duck at different storage times .

[0048] According to the experimental results in Table 1, it can be seen that after the quick-frozen roast ducks of Examples 1-3 were frozen and stored for 6 months, the carboxymethyllysine content was less than 2.5 mg / kg, while the quick-frozen roast ducks of Comparative Examples 1-12 produced and accumulated more carboxymethyllysine after being frozen and stored for 1-2 months, indicating that the process of the present invention can effectively delay the production and accumulation of carboxymethyllysine in the quick-frozen roast ducks during processing and frozen storage.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing quick-frozen roast duck, characterized in that: The following steps are involved: After being sprayed with tea polyphenol solution, the duck is roasted, subjected to a first vacuum cooling treatment, and then sprayed with acid solution, subjected to a second vacuum cooling treatment and quick-frozen treatment.

2. The preparation method according to claim 1, characterized in that The concentration of the tea polyphenols solution is 1%-3%.

3. The preparation method according to claim 2, characterized in that: The dosage of the tea polyphenol solution is 0.6%-1% of the weight of the duck.

4. The preparation method according to claim 1, characterized in that: The acid in the acid solution is one or more of ascorbic acid, malic acid, citric acid and lactic acid.

5. The preparation method according to claim 4, characterized in that: The concentration of the acid solution is 0.6%-0.8%.

6. The preparation method according to claim 4 or 5, characterized in that: The amount of the acid solution used is 0.3%-0.6% of the duck's mass.

7. The preparation method according to claim 1, characterized in that: The vacuum degree of the first vacuum cooling treatment is 0.004-0.006 MPa, and the time is 8-10 min.

8. The preparation method according to claim 1, characterized in that: The vacuum degree of the second vacuum cooling treatment is 0.004-0.006 MPa, and the time is 10-12 min.

9. The quick-frozen roast duck prepared by the method for preparing the quick-frozen roast duck according to any one of claims 1 to 8.

10. The quick-frozen roast duck according to claim 9, characterized in that: The quick-frozen roast duck is frozen and preserved at -18°C.