Fresh-keeping agent and fresh-keeping method for stuffing of steamed stuffed buns

Abstract

The invention discloses a preservative for stuffing of steamed stuffed buns. The preservative comprises the following components: 5-12 parts of epsilon-polylysine; 5 to 10 parts of nisin; 1 to 10 parts of natamycin; 0.1 to 8 parts of lysozyme; 2-14 parts of tea polyphenol, 2-15 parts of a vitamin compound and 1-10 parts of a natural plant extract; 5-20 parts of chitosan, 2-10 parts of a cryoprotectant and 10-50 parts of a weakly acidic buffer solution. The vitamin C and the vitamin E are wrapped in the sodium alginate and chitosan membrane material by utilizing the characteristic that the vitamin C and the vitamin E are stable to acid, so that the stability of the vitamin is improved, the vitamin is prevented from being decomposed, on the other hand, the vitamin can be slowly released in the refrigeration process, the oxidation resistance of the preservative is prolonged, and the effect of lasting preservation is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of food preservation, and in particular to a preservative for steamed bun fillings and a preservation method. Background Art

[0002] As a traditional Chinese delicacy, steamed buns are popular among the public for their rich and diverse fillings and unique flavors. Whether it is fresh and fragrant meat fillings, sweet and refreshing vegetarian fillings, or unique mixed fillings, they can all bring people a wonderful taste enjoyment. However, during the storage and sales process, steamed bun fillings are easily affected by factors such as microbial contamination and oxidation reactions, resulting in deterioration, taste change, and nutrient loss. This not only reduces the quality of steamed buns, but also shortens their shelf life, limiting the further development of the steamed bun industry.

[0003] The main reason for the deterioration of bun fillings is the rampant growth of microorganisms. Fillings are rich in nutrients such as protein and carbohydrates. Under suitable temperature and humidity conditions, bacteria, molds and other microorganisms multiply rapidly, decomposing the nutrients in the fillings, producing odors and toxins, and causing the fillings to deteriorate. On the other hand, many bun fillings add oil to enhance the flavor, but oil is prone to oxidation under the action of oxygen, light and high temperature, generating harmful substances such as peroxides and aldehydes and ketones, which affect the taste and reduce the nutritional value.

[0004] Preservatives and scientific preservation methods play a pivotal role in maintaining the quality of bun fillings and extending the shelf life. Suitable preservatives can effectively inhibit the growth and reproduction of microorganisms, slow down the oxidation process, and maintain the color, aroma, taste and nutritional content of the fillings. Currently, commonly used preservatives include antibacterial agents, antioxidants, etc. For example, antioxidants such as vitamin C and vitamin E are added to prevent oil oxidation. However, due to the influence of the water content, temperature and other additives of the fillings, the decomposition of vitamin C and vitamin E in the fillings will be accelerated, the vitamin content in the fillings will be reduced, and the preservation effect will be affected.

[0005] The appropriate preservation method can create a suitable storage environment for the filling, maximize the effectiveness of the preservative, and ensure that the filling of the buns always remains in good condition for a certain period of time. The most commonly used preservation method at present is physical freezing, which quickly freezes the filling at -30℃ or lower. In a short period of time, the water in the filling forms ice crystals, which pass through the maximum ice crystal formation zone and freeze. The ice crystals destroy and damage the structure of the frozen meat filling. In addition, long-term low-temperature frozen storage often causes loss of filling flavor and nutrition. At the same time, due to the dehydration of the filling, the taste becomes hard and worse. Summary of the invention

[0006] In view of the above, the present invention conducts in-depth research on preservatives and preservation methods for steamed bun fillings, aiming to provide practical technical support for the steamed bun production industry and help improve the quality and shelf life of steamed bun fillings.

[0007] The specific technical solutions of the present invention are as follows:

[0008] In a first aspect, the present invention provides a preservative for steamed bun fillings, comprising the following components in parts by weight:

[0009] 5-12 parts of ε-polylysine; 5-10 parts of nisin; 1-10 parts of natamycin; 0.1-8 parts of lysozyme; 2-14 parts of tea polyphenols, 2-15 parts of vitamin complex, 1-10 parts of natural plant extract; 5-20 parts of chitosan, 2-10 parts of cryoprotectant, 10-50 parts of weak acid buffer;

[0010] The vitamin complex includes one or a combination of vitamin C and vitamin E;

[0011] The weakly acidic buffer is a citric acid-sodium citrate buffer or a disodium hydrogen phosphate-citric acid buffer, and the pH value is 3.5-6.5;

[0012] The natural plant extract comprises one or a combination of two or more of spice extract, grape seed extract, green tea extract, rosemary extract and mulberry leaf extract.

[0013] Preferably, the weakly acidic buffer is a citric acid-sodium citrate buffer with a pH value of 5.5-6.5.

[0014] Preferably, the cryoprotectant comprises soy protein isolate and carrageenan, and the weight ratio of the two is (1-10):1.

[0015] In a second aspect, the present invention provides a method for preserving steamed bun fillings, using the preservative as described above. The method comprises the following specific steps:

[0016] (1) Preparation of preservative:

[0017] 1.1. Prepare a citric acid-sodium citrate buffer solution with a pH value of 3.5-6.5, add part of chitosan, stir and mix evenly at a low temperature of 45-75°C, add the vitamin complex and continue stirring to react, then perform fluidized bed spray drying or vacuum freeze drying to obtain composite film-coated vitamin particles;

[0018] 1.2. Take 10-20 parts of ε-polylysine, 5-10 parts of nisin, 1-10 parts of natamycin, 0.1-8 parts of lysozyme, 0.1-10 parts of tea polyphenols, 1-10 parts of natural plant extracts, 2-15 parts of cryoprotectants, and the remaining chitosan for later use;

[0019] (2) Add a cryoprotectant to the minced and seasoned meat filling, stir evenly, and perform vacuum infiltration in a vacuum drying oven. Then, add the composite film-coated vitamin particles prepared in step 1.1 and the remaining preservative ingredients in step 1.2. The remaining chitosan is added last after the filling is stirred and mixed, and the stirring is continued to mix evenly, and the filling is vacuum frozen at a sub-zero temperature.

[0020] Preferably, in step 1.1, a fluidized bed spray granulation method is used, and the fluidized bed air inlet temperature is 50-80°C and the air volume is 50-90m 3 / h.

[0021] More preferably, the fluidized bed air inlet temperature is 55-60°C, and the air volume is 60-80m 3 / h.

[0022] Further preferably, the vacuum penetration conditions in step 2 are: maintaining a vacuum degree of -0.05MPa to 0.1MPa in a vacuum drying oven for 20-60min.

[0023] The technical effects of the present invention are as follows:

[0024] Vitamin C and vitamin E are common antioxidants that can neutralize free radicals in fillings and convert them into stable substances, preventing oil oxidation and color changes, thereby maintaining the original flavor and color of the fillings and extending their shelf life. However, vitamin C and vitamin E are very unstable to oxygen and are easily oxidized. In addition, vitamin C is water-soluble and vitamin E is fat-soluble, while fillings contain not only water but also oil. In this environment, vitamins are more easily oxidized, and fluctuations in ambient temperature also affect their oxidation rate, resulting in a decrease in the antioxidant performance of the preservative in the filling, making it difficult to achieve a long-term preservation effect.

[0025] The present invention utilizes the acid-stable property of vitamins C and E, utilizes a weak acid buffer to compound sodium alginate and chitosan, adds vitamins C and E, utilizes a weak acid buffer to provide a weak acid environment to retain the vitamin components to the greatest extent, and simultaneously a complex reaction occurs between chitosan and sodium alginate, so that the chitosan-sodium alginate is transformed from an irregular coil structure into a nanofiber structure, forming a composite nanofiber membrane to wrap the vitamins. The vitamins are wrapped in the sodium alginate and chitosan membrane materials, which can improve the stability of the vitamins and prevent them from being decomposed by other components in the fillings and the external environment during filling preparation and frozen transportation. On the other hand, the vitamins can be slowly released during the refrigeration process, prolonging the antioxidant performance of the preservative and achieving a long-lasting preservation effect.

[0026] A part of the chitosan in the preservative of the present invention is used to encapsulate vitamins, and the other part is directly added at the rear end of the filling production to achieve the effect of a "protective film" around the meat filling. At the same time, the sugar molecules in the chitosan replace the water molecules around the muscle protein in the filling to achieve the effect of stabilizing the meat protein structure in the filling. The combination of the cryoprotectant and the free water in the meat filling increases the proportion of bound water in the meat filling, reduces the content of freezable water, and reduces the destruction and damage of ice crystals to the organizational structure of the frozen dumpling meat filling, thereby inhibiting the growth of microorganisms, reducing the ice crystals generated during the freezing process, and ensuring the fresh taste of the filling.

[0027] Chitosan is a natural polysaccharide that can form a dense film on the surface of the filling, isolating oxygen, moisture and microorganisms. It is like putting a protective coat on the filling, effectively slowing down the deterioration of the filling.

[0028] Tea polyphenols are rich in antioxidants, which not only have a certain antiseptic ability, but also can inhibit the growth of microorganisms to a certain extent. The catechins contained in them can destroy the structure of microbial cell membranes, thereby preventing microorganisms from absorbing the nutrients of bun fillings and achieving the purpose of preservation.

[0029] In the present invention, in the early stage of filling preparation and frozen storage, before the vitamins are released, the antioxidant property of tea polyphenols is mainly used to achieve the purpose of antioxidant preservation, and the purpose of extending the preservation time and improving the preservation effect is achieved by compounding the directly added tea polyphenols with the coated vitamins.

[0030] Nisin has a significant inhibitory effect on Gram-positive bacteria. Natamycin has an inhibitory effect on most molds and yeasts. ε-Polylysine has an inhibitory effect on most Gram-negative and Gram-positive bacteria. It is highly water-soluble and heat-stable, and has a good effect on inhibiting heat-resistant Bacillus.

[0031] Natural plant extracts can not only play a role in preservation and enhancement, but also have an antioxidant effect, thereby enhancing the preservation effect.

[0032] In summary, a single preservative ingredient often has certain limitations. Therefore, the present invention achieves the effects of bactericidal, antibacterial and antioxidant by compounding multiple preservative ingredients. The combination of these ingredients expands the antibacterial spectrum and improves the preservation effect. The compound preservative has significant advantages. Different ingredients can produce a synergistic effect, which can inhibit the growth of microorganisms and prevent oxidation reactions, thus protecting the bun fillings in all directions.

[0033] The invention is suitable for meat stuffings of steamed buns, not limited to meat stuffings such as pork, mutton, beef, shrimp meat, etc., and can also be used in mixed stuffings. DETAILED DESCRIPTION

[0034] The above contents of the present invention are further described in detail below through examples, but this should not be understood as the scope of the above subject matter of the present invention being limited to the following examples, and all technologies implemented based on the above contents of the present invention belong to the scope of the present invention.

[0035] The raw materials used in the present invention: ε-polylysine, nisin, natamycin, lysozyme, tea polyphenols, vitamin complex, chitosan, natural plant extracts, cryoprotectants, weak acid buffer can all be directly purchased.

[0036] Specifically, the natural plant extract described below refers to a mixed natural plant extract obtained by mixing a spice extract, a rosemary extract, and a mulberry leaf extract in a weight ratio of 1:1:1.

[0037] The cryoprotectant is a mixture of soy protein isolate and carrageenan, with a weight ratio of 3:1.

[0038] The weakly acidic buffer solution refers to a citric acid-sodium citrate buffer solution with a pH value of 5.5.

[0039] The vitamin complex refers to a mixture of vitamin C and vitamin E, with the weight ratio of the two being 1:1.

[0040] Example 1

[0041] 1. Take 40 parts of the prepared citric acid-sodium citrate buffer solution with a pH value of 5.5, add 10 parts of chitosan, stir and mix evenly under low temperature conditions of 55±3°C, add 8 parts of vitamin complex and continue to stir and react, then use fluidized bed spray granulation method, the fluidized bed inlet temperature is 55-60°C, the air volume is 70-80m3 / h, to obtain composite film-coated vitamin particles.

[0042] 2. Add 10 parts of cryoprotectant to the minced and seasoned meat filling, stir evenly, maintain the vacuum degree of -0.1MPa in a vacuum drying oven, and perform vacuum penetration for 30 minutes. Then add the composite film-coated vitamin particles prepared in step 1.1, and mix and stir;

[0043] 3. Add 10 parts of ε-polylysine, 8 parts of nisin, 4 parts of natamycin, 2 parts of lysozyme, 8 parts of tea polyphenols, and 8 parts of natural plant extracts, stir to mix, then add 10 parts of chitosan and continue to stir to mix evenly. Package, vacuum freeze at -40℃--30℃, and store in a freezer.

[0044] Example 2

[0045] 1. Take 40 parts of the prepared citric acid-sodium citrate buffer solution with a pH value of 5.5, add 10 parts of chitosan, stir and mix evenly at a low temperature of 55±3°C, add 8 parts of vitamin complex and continue stirring to react, then vacuum freeze-dry for 36 hours to obtain solid powdery composite film-coated vitamin particles.

[0046] 2. Add 10 parts of cryoprotectant to the minced and seasoned meat filling, stir evenly, maintain the vacuum degree of -0.1MPa in a vacuum drying oven, and perform vacuum penetration for 30 minutes. Then add the composite film-coated vitamin particles prepared in step 1.1, and mix and stir;

[0047] 3. Add 10 parts of ε-polylysine, 8 parts of nisin, 4 parts of natamycin, 2 parts of lysozyme, 8 parts of tea polyphenols, and 8 parts of natural plant extracts, stir to mix, then add 10 parts of chitosan and continue to stir to mix evenly, package, vacuum freeze at -40℃--30℃, and store in a freezer.

[0048] Example 3

[0049] 1. Take 40 parts of the prepared citric acid-sodium citrate buffer solution with a pH value of 5.5, add 10 parts of chitosan, stir and mix evenly at a low temperature of 55±3°C, add 10 parts of vitamin complex and continue stirring to react, then vacuum freeze-dry for 36 hours to obtain solid powdery composite film-coated vitamin particles.

[0050] 2. Add 10 parts of cryoprotectant to the minced and seasoned meat filling, stir evenly, maintain the vacuum degree of -0.1MPa in a vacuum drying oven, and perform vacuum penetration for 30 minutes. Then add the composite film-coated vitamin particles prepared in step 1.1, and mix and stir;

[0051] 3. Add 12 parts of ε-polylysine, 6 parts of nisin, 8 parts of natamycin, 0.5 parts of lysozyme, 10 parts of tea polyphenols, and 8 parts of natural plant extracts, stir to mix, then add 8 parts of chitosan and continue to stir to mix evenly, package, vacuum freeze at -40℃--30℃, and store in a freezer.

[0052] Comparative Example 1

[0053] 1. Add 10 parts of cryoprotectant to the minced and seasoned meat filling, stir evenly, maintain the vacuum degree of -0.1MPa in a vacuum drying oven, and perform vacuum penetration for 30 minutes, then add 10 parts of vitamin complex and 10 parts of chitosan and mix;

[0054] 2. Add 12 parts of ε-polylysine, 6 parts of nisin, 8 parts of natamycin, 0.5 parts of lysozyme, 10 parts of tea polyphenols, and 8 parts of natural plant extracts, stir and mix, then add 8 parts of chitosan and continue to stir and mix evenly. Package, vacuum freeze at -40℃--30℃, and store in a freezer.

[0055] Comparative Example 2

[0056] 1. Add 10 parts of cryoprotectant to the minced and seasoned meat filling, stir evenly, and place in a vacuum drying oven to maintain a vacuum degree of -0.1MPa for 30 minutes;

[0057] 2. Add 12 parts of ε-polylysine, 6 parts of nisin, 8 parts of natamycin, 0.5 parts of lysozyme, 10 parts of tea polyphenols, and 8 parts of natural plant extracts, stir and mix, then add 8 parts of chitosan and continue to stir and mix evenly. Package, vacuum freeze at -40℃--30℃, and store in a freezer.

[0058] Test Method

[0059] 1. Determination method of total colony count: refer to GB4789.2-2016.

[0060] The fillings obtained in Examples 1-3 and Comparative Examples 1 and 2 were stored in a refrigerator, and the total number of colonies (unit: log10 CFU / g) was measured at 0, 2, 4, 6, 8, 10, 12, and 14 days, respectively. The results are shown in Table 1.

[0061] Table 1 Results of total colony count (log10 CFU / g)

[0062]

[0063]

[0064] As can be seen from Table 1, the total colony count in the fillings of Comparative Examples 1 and 2 began to increase significantly on the 6th day and exceeded the national standard on the 10th day (total colony count>6log10CFU / g), while the total colony count in the fillings of Examples 1-3 of the present invention did not exceed the national standard until the 14th day, extending the shelf life.

[0065] 2. Determination of vitamin C: The vitamin C content was determined by 2,6-dichloroindophenol titration method (refer to GB / T6195-86).

[0066] The fillings obtained in Examples 1-3 and Comparative Example 1 were stored in a refrigerator, and the vitamin C content was measured at 2, 4, 6, 8, 10, 12, and 14 days, respectively. The vitamin C content of the filling prepared in Example 1 at 0 days was recorded as 1, and the ratio of the measured values ​​of other examples and comparative examples to the vitamin C content was calculated to observe the change in the vitamin C content. The results are shown in Table 2.

[0067] Table 2 Vitamin C determination results

[0068] 0d 2d 4d 6d 8d 10d 12d 14d Example 2 1.00 1.44 1.66 1.83 1.87 1.58 1.37 1.26 Example 2 1.05 1.52 1.61 1.87 1.89 1.57 1.42 1.30 Example 3 1.12 1.64 1.83 1.91 1.94 1.62 1.49 1.34 Comparative Example 1 2.14 1.90 1.62 1.21 1.02 0.81 0.67 0.34

[0069] As can be seen from Table 2, the vitamin C content in the filling of Comparative Example 1 continues to decrease from the initial peak, and vitamin C begins to decompose. The rate of decrease is low in the early stage, and it begins to decrease significantly on the fourth day; while the vitamin C content of Examples 1-3 of the present invention exists at the time of initial measurement, and continues to increase in the early stage, reaches a peak on the eighth day, and then begins to decrease. Analysis shows that most of the vitamin C is coated during preparation, and then slowly released, and the vitamin C content continues to increase; but at the same time, there is a small amount of incompletely wrapped vitamin C in the filling, which is also the reason why the vitamin C content of Comparative Example 1 is higher than that of Examples 1-3 at the beginning, and during the entire test process, vitamin C in Examples 1-3 is continuously released, and the content continues to increase, but at the same time, vitamin C also undergoes a decomposition reaction at the same time, which is also the reason why the value of the vitamin C content in Examples 1-3 when it reaches a peak value is lower than the initial content value of vitamin C in Comparative Example 1. But overall, the vitamin C content can achieve a continuous high content effect using the method of the present invention, and increase the antioxidant and fresh-keeping effect.

[0070] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention without departing from the technical essence of the claims of the present invention shall still fall within the protection scope of the claims of the present invention.

Claims

1. A preservative for steamed bun fillings, characterized in that: It includes the following components by weight: 5-12 parts of ε-polylysine; 5-10 parts of nisin; 1-10 parts of natamycin; 0.1-8 parts of lysozyme; 2-14 parts of tea polyphenols, 2-15 parts of vitamin complex, 1-10 parts of natural plant extract; 5-20 parts of chitosan, 2-10 parts of cryoprotectant, 10-50 parts of weak acid buffer; The vitamin complex includes one or a combination of vitamin C and vitamin E; The weakly acidic buffer is a citric acid-sodium citrate buffer or a disodium hydrogen phosphate-citric acid buffer, and the pH value is 3.5-6.5; The natural plant extract comprises one or a combination of two or more of spice extract, grape seed extract, green tea extract, rosemary extract and mulberry leaf extract.

2. The preservative for steamed bun fillings according to claim 1, characterized in that: The weakly acidic buffer solution is a citric acid-sodium citrate buffer solution with a pH value of 5.5-6.

5.

3. The preservative for steamed bun fillings according to claim 1, characterized in that: The cryoprotectant comprises soy protein isolate and carrageenan, and the weight ratio of the two is (1-10):

1.

4. A method for preserving steamed bun fillings, characterized in that: Use the preservative as described in any one of claims 1 to 3.

5. The method for preserving steamed bun fillings according to claim 1, characterized in that: The specific steps include: (1) Preparation of preservative: 1.

1. Prepare a citric acid-sodium citrate buffer solution with a pH value of 3.5-6.5, add part of chitosan, stir and mix evenly at a low temperature of 45-75°C, add the vitamin complex and continue stirring to react, then perform fluidized bed spray drying or vacuum freeze drying to obtain composite film-coated vitamin particles; 1.

2. Take 10-20 parts of ε-polylysine, 5-10 parts of nisin, 1-10 parts of natamycin, 0.1-8 parts of lysozyme, 0.1-10 parts of tea polyphenols, 1-10 parts of natural plant extracts, 2-15 parts of cryoprotectants, and the remaining chitosan for later use; (2) Add a cryoprotectant to the minced and seasoned meat filling, stir evenly, and perform vacuum infiltration in a vacuum drying oven. Then, add the composite film-coated vitamin particles prepared in step 1.1 and the remaining preservative ingredients in step 1.

2. The remaining chitosan is added last after the filling is stirred and mixed, and the stirring is continued to mix evenly, and the filling is vacuum frozen at a sub-zero temperature.

6. The method for preserving steamed bun fillings according to claim 5, characterized in that: In step 1.1, fluidized bed spray granulation method is used, the fluidized bed air inlet temperature is 50-80℃, the air volume is 50-90m 3 / h.

7. The method for preserving steamed bun fillings according to claim 6, characterized in that: The fluidized bed inlet air temperature is 55-60°C, and the air volume is 60-80m 3 / h.

8. The method for preserving steamed bun fillings according to claim 5, characterized in that: The vacuum penetration conditions in step 2 are: maintaining a vacuum degree of -0.05MPa--0.1MPa in a vacuum drying oven, and vacuum penetration for 20-60min.

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