A method for quickly and controllably preparing low-salt salted egg yolk using egg yolk powder

Abstract

The present invention discloses a method for rapidly and controllably preparing low-salt salted egg yolks using egg yolk powder, and belongs to the technical field of food processing. The method comprises the following steps: (1) ethanol denaturation treatment of the egg yolk powder; (2) ethanol removal; (3) low-temperature drying treatment; and (4) preparation of low-salt salted egg yolks: compounding the partially denatured egg yolk powder with an appropriate amount of salt and water, fully mixing, and then heating to obtain low-salt salted egg yolks. The texture of the salted egg yolks prepared by the method is not significantly different from that of the salted egg yolks prepared by the traditional process, and the method has a high oil yield and a soft mouthfeel. The individual differences of the products are small, and the method is easy to standardize and control, and the production cycle can be greatly shortened. The salt content is significantly reduced, and the amount of salt added can be precisely controlled to avoid excessive salt content. The method is easy to operate, the process is simple, no salted egg white by-products are produced, the production cost is low, and the method has broad market prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of food processing, and particularly relates to a method for quickly and controllably preparing low-salt salted egg yolks by utilizing egg yolk powder. Background Art

[0002] As a renowned traditional egg product, salted egg is deeply loved by consumers for its unique qualities, including freshness, softness, sandiness, and oiliness. Salted egg yolks are commonly used in Chinese pastries such as rice dumplings, mooncakes, and egg yolk pastries. They are also used in various Chinese dishes and salted egg yolk-flavored foods, demonstrating their broad market potential.

[0003] Currently, salted egg yolks are produced primarily through traditional pickling and quick pickling. Traditional pickling involves the osmotic action of high-concentration salt, with NaCl gradually penetrating through the eggshell into the egg white and yolk, gradually transferring water out of the shell. Under the influence of NaCl and dehydration, the yolk protein aggregates and denatures, and oil seeps out, forming a mature salted egg yolk. However, the traditional pickling process is slow, requiring at least four to five weeks to form a mature salted egg yolk, a significant wait time. Egg size, freshness, and pickling conditions also influence the pickling process, resulting in significant variation in the quality of the resulting salted egg yolk, making standardization difficult. Furthermore, mature salted egg yolks have a high salt content, ranging from approximately 7% to 10% for the egg white and 2.5% to 3% for the egg yolk. Excessive salt intake can easily lead to high blood pressure and various cardiovascular and cerebrovascular diseases. Furthermore, a large amount of salty salted egg white cannot be effectively utilized, with most discarded, resulting in a waste of protein resources and significant environmental pollution. Rapid curing involves separating the yolk from the egg white, preserving the intact yolk structure. This process primarily involves dry curing, wet curing, and reconstitution. While the rapid curing process significantly shortens salt penetration time, it also presents numerous challenges. First, separating the yolk from the egg white is difficult, and the yolk membrane is easily broken, resulting in a low yield. Dry curing results in high salt content and a flattened egg yolk. Wet curing results in water-filled egg yolks, resulting in poor internal gelation and low oil yield. Reconstitution also involves the addition of a molding agent to the egg yolk, resulting in a significantly different taste than traditional salted egg yolks.

[0004] Therefore, it is of great significance to develop a new, rapid and controllable method to produce low-salt salted egg yolks. Egg yolk powder is a common egg yolk product on the market. It has uniform and stable quality, a long shelf life, and is easy to use. However, current research shows that egg yolk powder has good gel properties. When using egg yolk powder as a raw material and using traditional pickling methods, the egg yolk protein easily aggregates to form a uniform egg yolk gel, reducing the oil yield of the product and failing to achieve the sandy and oily texture of traditional pickled salted egg yolks. Therefore, there is an urgent need to develop a method to control the excessive aggregation of egg yolk protein to achieve the rapid and controllable preparation of low-salt salted egg yolks using egg yolk powder. Summary of the Invention

[0005] Technical issues

[0006] The existing salted egg yolk processing technology has problems such as long preparation time, complex procedures, low yield, and difficulty in standardization. The resulting salted egg yolk has excessive salt content and low oil yield. Therefore, the present invention develops the idea of ​​using egg yolk powder to prepare salted egg yolk. However, egg yolk powder easily aggregates to form a uniform egg yolk gel during preparation, reducing the oil yield of the product and affecting the final quality of the product.

[0007] Technical content

[0008] In order to solve the above problems, the present invention provides a method for quickly and controllably preparing low-salt salted egg yolks using egg yolk powder. Previous studies have shown that gel formation is mainly related to the soluble protein in the egg yolk protein component slurry. In addition, although oils and fats do not directly participate in the formation of the gel, they can interact with proteins and have an important influence on the strength of the gel. The present invention treats egg yolk powder with different concentrations of ethanol to cause controllable partial denaturation of the egg yolk protein, reduce the gel-forming ability of the egg yolk protein, and change the texture characteristics of the egg yolk protein polymer. In addition, ethanol can promote the leaching of oils and fats in the egg yolk powder, and act as an inactive filler to hinder the interaction between proteins. By compounding salt and water, a salted egg yolk with a fast production speed, controllable salt content, and a high similarity in texture to traditional pickled salted egg yolks is obtained.

[0009] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions.

[0010] A method for quickly and controllably preparing low-salt salted egg yolks using egg yolk powder may specifically include the following steps:

[0011] (1) Denaturation of egg yolk powder: Disperse the egg yolk powder in ethanol at high speed and then stir to obtain a denatured egg yolk powder solution;

[0012] (2) De-drying: the denatured egg yolk powder solution obtained in step (1) is subjected to vacuum evaporation treatment, and then subjected to low-temperature drying to obtain dry denatured egg yolk powder;

[0013] (3) Preparation of low-salt salted egg yolk: Add water and salt to the dried denatured egg yolk powder obtained in step (2), stir thoroughly, and then steam under normal pressure for 10 to 15 minutes to obtain soft and oily low-salt salted egg yolk.

[0014] In one embodiment of the present invention, the rotation speed of the high-speed dispersion in step (1) is 4000-6000 r / min, and the time is 0.5-1 min.

[0015] In one embodiment of the present invention, the ethanol concentration in step (1) is 30% to 60% (volume concentration).

[0016] In one embodiment of the present invention, the material-liquid ratio of egg yolk powder and ethanol in step (1) is 1 g: 8-12 mL.

[0017] Preferably, the material-liquid ratio of egg yolk powder and ethanol in step (1) is 1 g: 10 mL.

[0018] In one embodiment of the present invention, the stirring treatment in step (1) is carried out at room temperature at a rotation speed of 200 to 300 r / min for 0.8 to 1.5 h.

[0019] In one embodiment of the present invention, the vacuum evaporation temperature in step (2) is 40-60° C., and the processing time is 0.5-1 h.

[0020] In one embodiment of the present invention, the low-temperature drying in step (2) is hot air drying, and the specific conditions are: drying temperature 50-60°C, and time 20-24 h.

[0021] In one embodiment of the present invention, the amount of water added in step (3) is 20% to 30% of the total mass of the system.

[0022] In one embodiment of the present invention, the amount of salt added in step (3) is 0% to 3.1% of the total mass of the system.

[0023] Preferably, the amount of salt added in step (3) is 1% to 2% of the total mass of the system.

[0024] The present invention provides low-salt salted egg yolk prepared according to the method.

[0025] Beneficial effects

[0026] (1) The present invention can greatly shorten the production time of salted egg yolks, shorten the production cycle, and the entire preparation process only takes about 24 hours. In addition, the texture of the prepared salted egg yolks is not significantly different from that of the salted egg yolks prepared by the traditional process of long-term pickling.

[0027] (2) Ethanol, as an organic solvent, can cause protein denaturation under certain conditions. However, in order to obtain a product texture similar to salted egg yolk, the present invention requires a controlled "partial" denaturation of the egg yolk protein. This is because ordinary egg yolk powder has too strong a gelling property, and the texture of the product obtained is very different from that of salted egg yolk. Completely denatured egg yolk protein also cannot obtain a texture similar to that of salted egg yolk due to the severe degree of protein denaturation. Therefore, in the present invention, it is very important to control the degree of denaturation of the egg yolk protein. Therefore, in the present invention, ethanol within a certain concentration range is preferred, and the degree of denaturation of the egg yolk protein is perfectly controlled. The resulting composite has texture characteristics and oil yield similar to those of salted egg yolk, thereby innovating a rapid and controllable method for preparing salted egg yolk.

[0028] (3) The texture of the salted egg yolk produced by the present invention has little individual difference and is easy to standardize and control. In addition, the present invention can control the amount of salt added to the salted egg yolk to prevent consumers from taking in too much salt, which meets the standards of a healthy diet.

[0029] (4) The present invention is easy to operate, has a simple process, does not produce salted egg white by-products, has low production costs, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The low-salt salted egg yolk is made from egg yolk powder. The left picture is the low-salt salted egg yolk of Example 1, and the right picture is a cross-sectional view of the low-salt salted egg yolk of Example 1. DETAILED DESCRIPTION

[0031] The technical solutions in the examples of the present application will be described clearly and completely below. Obviously, the described examples are only examples of a part of the present application, rather than all examples. It should be emphasized that the following examples are for better explanation of the present invention and are not intended to limit the present invention. The methods described are all conventional methods unless otherwise specified.

[0032] Source of raw materials

[0033] Egg yolk powder was purchased from Anhui Rongda Poultry Co., Ltd. Salted chicken eggs and salted duck eggs for control were purchased from local supermarkets and made using traditional pickling techniques.

[0034] Test Method

[0035] Texture: Gel texture analysis was performed on each sample using a TA-XT2 texture analyzer (TA-XT2) at room temperature. Cooked salted egg yolks were cut into cubes with a length, width, and height of 10 mm, and the texture was measured six times in parallel. TPA mode was used. Measurement parameters: pre-test speed 5.0 mm / s, test speed 1.0 mm / s, post-test speed 5.0 mm / s, compression ratio 50%, recovery time 5 s, trigger point load 5 g, and probe model P / 36R.

[0036] Oil yield: Weigh approximately 2 g of sample, add 25 mL of distilled water, and homogenize using a homogenizer (8,000-10,000 rpm) for approximately 30 seconds. Centrifuge at 8,000 rpm for 25 minutes. Transfer the salted egg yolk liquid to a separatory funnel. Add 25 mL of organic solvent (V:n-hexane:V:isopropanol = 3:2) to the separatory funnel for extraction. Collect the supernatant into the corresponding numbered beaker. Place the sample in a 55°C water bath to evaporate most of the solvent, then dry in a 105°C oven to constant weight. Calculate the free fat content.

[0037] Take approximately 1 g of sample and add 20 mL of an organic solvent (V:n-hexane:V:isopropanol = 3:2). Homogenize at 8,000–10,000 rpm for approximately 1 minute, then filter through filter paper. After evaporating most of the solvent in a 55°C water bath, dry the sample in a 105°C oven, cool in a desiccator, and weigh. Calculate the total fat content.

[0038] The oil yield of salted egg yolk is: Oil yield (%) = free fat content / total fat content.

[0039] Salt content: To a 5 g egg yolk sample, add 20 mL of 0.1 mol / L AgNO₃ and 10 mL of 30 mL / 100 mL HNO₃. Boil the mixture until all solids except silver chloride have dissolved. Afterward, cool the mixture to room temperature and add 5 mL of 5 g / 100 g FeNH₄(SO₄)₂·12H₂O. Titrate the mixture with 0.1 mol / L KSCN standard solution until the solution turns a permanent light brown color. Calculate the percent salt content of the sample using the following equation:

[0040] Salt (g / 100g) = 5.8 × [(V1 × N1) − (V2 × N2)] / W

[0041] Where V1 is the volume of AgNO3 solution (mL), N1 is the molar concentration of AgNO3 solution (mol / L), V2 is the consumed volume of KSCN solution (mL), N2 is the molar concentration of KSCN solution (mol / L), and W is the weight of the sample (g).

[0042] Example 1

[0043] A method for quickly and controllably preparing low-salt salted egg yolks using egg yolk powder may specifically include the following steps:

[0044] (1) Denaturation treatment of egg yolk powder: disperse the egg yolk powder in 30% ethanol at a high speed of 5000 r / min for 1 min with a material-liquid ratio of 1 g:10 mL, and then stir at 300 r / min at room temperature for 1 h;

[0045] (2) Ethanol removal: The egg yolk powder solution obtained in step (1) was subjected to vacuum evaporation at 50°C for 1 h;

[0046] (3) Drying: The egg yolk powder solution obtained in step (2) is dried with hot air at a temperature of 60°C for 24 h;

[0047] (4) Preparation of low-salt salted egg yolk: Add 25% water and 1.5% salt to the dried egg yolk powder obtained in step (3) and stir thoroughly. Steam the resulting mixture under normal pressure for 10 min.

[0048] Example 2

[0049] The ethanol concentration in step (1) in Example 1 was changed to 40%, and the other conditions were the same as in Example 1.

[0050] Example 3

[0051] The ethanol concentration in step (1) in Example 1 was changed to 50%, and the other conditions were the same as in Example 1.

[0052] Example 4

[0053] The ethanol concentration in step (1) in Example 1 was changed to 60%, and the other conditions were the same as in Example 1.

[0054] Example 5

[0055] The amount of water added in step (4) of Example 1 was changed to 20%, and the other conditions were the same as those of Example 1.

[0056] Example 6

[0057] The amount of water added in step (4) of Example 4 was changed to 20%, and the other conditions were the same as those of Example 1.

[0058] Example 7

[0059] The amount of water added in step (4) of Example 1 was changed to 30%, and the other conditions were the same as those of Example 1.

[0060] Example 8

[0061] The amount of water added in step (4) of Example 4 was changed to 30%, and the other conditions were the same as those of Example 1.

[0062] Example 9

[0063] The amount of salt added in step (4) of Example 1 was changed to 1%, and the other conditions were the same as those of Example 1.

[0064] Example 10

[0065] The amount of salt added in step (4) of Example 1 was changed to 2%, and the other conditions were the same as those of Example 1.

[0066] Comparative Example 1

[0067] The egg yolk powder that has not been treated with ethanol was treated in step (4) of Example 1.

[0068] Comparative Example 2

[0069] The amount of water added in step (1) of Example 1 was replaced by 10%, and the other conditions remained the same as in Example 1.

[0070] Comparative Example 3

[0071] The amount of water added in step (1) of Example 1 was replaced by 40%, and the other conditions remained the same as in Example 1.

[0072] Comparative Example 4

[0073] The ethanol concentration in step (1) of Example 5 was replaced with 20%, and the other conditions remained the same as in Example 5.

[0074] Comparative Example 5

[0075] The ethanol concentration in step (1) of Example 5 was replaced with 70%, and the other conditions remained the same as in Example 5.

[0076] Comparative Example 6

[0077] Salted duck egg yolks sold in the market.

[0078] Comparative Example 7

[0079] Salted egg yolks sold in the market.

[0080] Comparative Example 8

[0081] The amount of salt added in step (4) of Example 1 was replaced by 0, and the other conditions remained the same as in Example 1.

[0082] Comparative Example 9

[0083] The amount of salt added in step (4) of Example 1 was replaced with 3.1%, and other conditions remained the same as in Example 1.

[0084] The physical properties, salt content and oil yield of Examples 1-10 and Comparative Examples 1-9 were measured. The results are shown in Table 1:

[0085] Table 1 Physical properties, salt content and oil yield of Examples 1-10 and Comparative Examples 1-9

[0086]

[0087] The results indicate that ethanol-treated egg yolk powder reduces the hardness, elasticity, cohesiveness, and chewiness of salted egg yolks, while increasing their oil yield. When treated with ethanol at concentrations between 30% and 60%, and with a water content between 20% and 30%, the resulting salted egg yolks have a texture similar to those obtained using traditional curing methods.

[0088] Example 1, Example 5, and Example 7 show that when treated with 30% ethanol and the amount of water added is 20-30%, the mixture obtained after heating can obtain a texture and taste similar to that of the traditional pickled salted egg yolk in Reference Example 7, and the oil yield also reaches the level of traditional pickled egg yolk. Example 2, that is, the egg yolk powder treated with 40% ethanol, can obtain a salted egg yolk with lower hardness and chewiness than the traditional pickled salted egg yolk in Reference Example 7 after heating, and the oil yield is also 2.2% higher than the traditional pickled salted egg yolk, but compared with the traditional pickled salted duck egg yolk in Reference Example 6, the texture is hard and the oil yield is low. Example 3, the egg yolk powder treated with 50% ethanol, the salted egg yolk obtained after heating the mixture has slightly lower hardness, cohesion, and chewiness than the traditional pickled salted duck egg yolk in Reference Example 6, and is softer in texture, but the oil yield is slightly lower. Example 4, Example 6, and Example 8 show that when treated with 60% ethanol and added with 20-30% water, the mixture obtained after heating can obtain a hardness reduction of 28.96%-31.48%, elasticity reduction of 13.56%-20.34%, cohesion reduction of 8.33%-19.44%, chewiness reduction of 15.46%-32.61%, and slightly higher oil yield compared to the traditional pickled salted duck egg yolk in Control Example 6. The texture is softer, oily but not greasy, and the quality and taste are improved. The results of Examples 9 and 10 show that using the method provided by the present invention, the salted egg yolk obtained can still obtain texture indicators such as hardness, cohesion, chewiness and oil yield similar to those of traditional pickled salted egg yolks at a lower salt content than traditional pickled salted egg yolks. It can be seen that within the parameter range described in the present invention, the salt content of the prepared salted egg yolk is significantly lower than that of the salted egg yolk obtained by traditional pickling, but the texture, taste and oil yield similar to those of traditional pickled salted chicken and duck egg yolks can be obtained.

[0089] The egg yolk powder that reference example 1 does not adopt ethanol treatment shows higher hardness, elasticity, cohesion after treatment, illustrates that egg yolk albumen still has stronger protein gel property at this moment, and texture is quite different from traditional salted egg yolk, and oil yield is 14.53%, 19.04% lower than traditional pickled salted egg yolk oil yield; Reference example 2 illustrates that in the range of water addition lower than the present invention, protein concentration is raised under the conditions of embodiment 5, and hardness, elasticity, cohesion and chewiness are higher after heating the mixture obtained, and show as protein gel property, and differ greatly from traditional salted egg yolk texture; Reference example 3 illustrates that in the range of water addition higher than the present invention, the mixture moisture content obtained is higher, and protein content is reduced, resulting in having lower hardness and chewiness, but its elasticity is 0.84, 12% higher than the elasticity of reference example 7 traditional pickled egg yolk, still show as protein gel property, and differ greatly from traditional salted egg yolk texture; Reference example 4 illustrates that in the range of water addition lower than the present invention, protein concentration is raised under the conditions of embodiment 5, and hardness, elasticity, cohesion and chewiness are higher, and hardness, elasticity, cohesion and chewiness are higher, and hardness, elasticity, cohesion and chewiness are higher, and hardness, elasticity, cohesion and chewiness are differ greatly from traditional salted egg yolk texture Within the range of ethanol concentration, the hardness, elasticity, cohesion and chewiness of the obtained mixture after heating are lower than those of the untreated egg yolk powder, but the elasticity of the traditional pickled egg yolk in Reference Example 7 is increased by 17.33%, and the cohesion is increased by 25.42%, and it still has protein gel properties, which is quite different from the texture of the traditional salted egg yolk. Reference Example 5 shows that when the ethanol concentration is higher than the ethanol treatment concentration range of the present invention, the obtained mixture is heated, and the hardness, elasticity, cohesion and chewiness of the traditional pickled salted duck egg yolk in Reference Example 6 are reduced by 60.62%, 32.20%, 47.22% and 78.93%, respectively, and the cohesion is reduced by more (67.80%) than that of the traditional pickled salted egg yolk in Reference Example 7, indicating that high-concentration ethanol treatment of egg yolk causes a higher degree of protein denaturation, a low degree of bonding between protein molecules, too little chewiness, and a large amount of oil is released, making it softer and more rotten than the traditional pickled salted egg yolk, showing a muddy feeling, and a decline in quality and taste. Therefore, outside the parameter range described in the present invention, the system will have too high elasticity or cohesion, and the egg yolk protein molecules will be tightly connected, thus exhibiting protein gel properties; or it will have too low cohesion, and the egg yolk protein molecules will have almost no connection, thus exhibiting the mud-like properties of salted egg yolk.

[0090] The results of control examples 8 and 9 show that when the salt content is lower or higher than the range described in the present invention, the texture index and oil yield index of the obtained product are not significantly affected. However, from the perspective of taste and health, too low or too high salt content has an adverse effect on the taste of the product or on human health. Within the salt content range described in the present invention, the salt content of the prepared salted egg yolk is significantly lower than that of the salted egg yolk obtained by traditional pickling, but the texture, taste and oil yield similar to those of traditional pickled salted chicken and duck egg yolks can be obtained, and the salt content can be precisely controlled and adjusted according to taste requirements.

[0091] The above description is provided to further explain the present invention in detail in conjunction with specific / preferred embodiments and is not intended to limit the present invention. Any person skilled in the art may make various modifications and alterations without departing from the scope and technique of the present invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A method for rapidly and controllably preparing low-salt salted egg yolks using egg yolk powder, characterized in that: The following steps are involved: (1) Denaturation of egg yolk powder: Disperse the egg yolk powder in 30% to 60% ethanol at high speed, and then stir to obtain a denatured egg yolk powder solution; the material-liquid ratio of egg yolk powder to ethanol is 1 g: 8-12 mL; (2) De-drying: the denatured egg yolk powder solution obtained in step (1) is subjected to vacuum evaporation treatment, and then subjected to low-temperature drying to obtain dry denatured egg yolk powder; (3) Preparation of low-salt salted egg yolk: Add water and salt to the dried denatured egg yolk powder obtained in step (2), stir thoroughly, and then steam under normal pressure for 10 to 15 minutes to obtain soft and oily low-salt salted egg yolk.

2. The method according to claim 1, wherein In step (1), the speed of high-speed dispersion is 4000~6000 r / min, and the time is 0.5~1 min.

3. The method according to claim 1, wherein The stirring treatment in step (1) is carried out at room temperature at a rotation speed of 200 to 300 r / min for 0.8 to 1.5 h.

4. The method according to claim 1, wherein In step (2), the vacuum evaporation temperature is 40-60°C, and the treatment time is 0.5-1 h.

5. The method according to claim 1, wherein The low-temperature drying in step (2) is hot air drying, and the conditions are: drying temperature 50-60°C, and time 20-24 h.

6. The method according to claim 1, wherein The amount of water added in step (3) is 20% to 30% of the total mass of the system.

7. The method according to claim 1, wherein The amount of salt added in step (3) is 0% to 3.1% of the total mass of the system.

8. The method according to claim 7, characterized in that The amount of salt added in step (3) is 1% to 2% of the total mass of the system.

9. A low-salt salted egg yolk prepared according to the method according to any one of claims 1 to 8.

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