A high-efficiency separation pickling method of low-salt-content high-quality salted yolk

Abstract

The present application relates to a kind of efficient separation curing method of low salt content high-quality salted egg yolk, the method is with fresh whole duck egg yolk as raw material, after being separated and cured by ultrasonic cooperation NaCl dry method, a kind of salted egg yolk with high oil yield, low salt content, with grit feeling is obtained.The present application first uniformly spreads a layer of NaCl particle in curing nest (in the form of salt nest), the thickness of salt nest keeps consistent, the egg white of fresh duck egg is separated, and the excess egg white on egg yolk is absorbed by filter paper, and the complete egg yolk is placed in salt nest, then the egg yolk is completely wrapped with NaCl, after being sealed, it is placed in ultrasonic cleaning machine at 600-1200 W, 20-30 ℃ curing.The present application uses ultrasonic cooperation NaCl to carry out dry separation curing to duck egg yolk, significantly shortens the curing time of salted egg yolk, and improves the oil yield and grit feeling of salted egg yolk, provides theoretical reference for efficient separation curing of salted egg yolk, avoids the waste of salted egg white, and promotes the application of duck egg in food industry.

Description

Technical Field

[0001] The invention relates to the field of egg product processing, in particular to a method for efficiently separating and pickling low-salt-content, high-quality salted egg yolks. Background Art

[0002] Salted egg yolk is rich in lecithin, unsaturated fatty acids, amino acids and other important nutrients for human life. It has the characteristics of freshness, fragrance, looseness, sandiness, fineness and oiliness. The important characteristics of salted egg yolk are oil yield and gritty texture. These characteristics make it popular among the public and widely used in food processing, such as egg yolk pastry, moon cakes, rice dumplings, etc. The characteristics of duck egg yolk (high fat content) make it suitable for preparing salted egg yolk. The preparation of traditional salted egg yolk is mainly to pickle duck eggs in saturated salt water. The salted egg white prepared by this method has an extremely high salt content (8%-11.5%), which is difficult to eat and does not meet the current low-salt healthy diet guidelines. Therefore, most of the salted egg white is directly discarded, resulting in a serious waste of resources. In addition, the pickling time of this method is as long as 30-40 days, which is difficult to meet the large demand for salted egg yolk in the food industry.

[0003] Compared to traditional whole-egg curing, salted egg yolks can now be cured using separate curing, which involves separating the egg white and curing the yolk separately. This separate curing method includes wet and dry curing. Wet curing involves separating the yolk using a salt solution or a salt / spice mixture. Curing typically takes 2-5 days. For example, patent application number 201110203992.4, entitled "Method for Rapidly Curing Salted Egg Yolks Using a Wet Method," is available. Due to differences in the moisture content of the curing system, wet curing is slower than dry curing. Consequently, for the same curing time, the oil yield of wet-cured salted egg yolks is lower than that of dry-cured ones. Furthermore, a major drawback of wet curing is the difficulty in addressing the problem of water-filled and gelatinized yolks. Dry curing effectively addresses this issue. Shortening curing time, increasing the oil yield of salted egg yolks, and preventing water-filled yolks are pressing challenges in the wet-curing process of separate salted egg yolks.

[0004] Dry curing is the use of dry salt or a small amount of solution added to the salt to make wet salt (non-solution) to separate and curing the egg yolk, such as the patent application number 202211143909.3, the invention name is "A method for quickly curing salted egg yolks" and the patent application number 01106358.0, the invention name is "A process for curing salted egg yolks". Compared with wet curing, the dry curing time is shorter, generally 24-72 hours, and the degree of protein aggregation in the egg yolk is small, resulting in a poor gritty feeling of the salted egg yolk; dry-cured salted egg yolks are prone to being too salty (>2%), and the protein and lipids in the egg yolk are excessively separated, resulting in an uneven texture of the salted egg yolk; the salted egg yolks prepared by the dry curing method also have the disadvantage of a flat yolk shape. Therefore, improving the gritty taste of salted egg yolks, improving curing efficiency, and avoiding a flat curing shape are problems that need to be urgently solved in the current dry separation and curing process of salted egg yolks.

[0005] To address the problems arising from the curing process, researchers have continuously optimized the curing process for salted egg yolks, using ultrasound to synergize with NaCl to separate the yolks. On the one hand, ultrasound synergistically promotes the penetration of NaCl into the yolks, improving curing efficiency. While ensuring high quality, the curing time for salted egg yolks was effectively shortened to 44 hours, significantly reducing the curing time and improving curing efficiency. On the other hand, ultrasound disrupts the structure of the yolk protein, which helps enhance the grittiness of the salted egg yolks and improves their texture. Simultaneously, ultrasound promotes the separation of protein and lipids in the yolks, effectively increasing the oil yield of the salted egg yolks. Furthermore, this curing method involves separating the egg whites and yolks before placing the yolks in a box-type curing box for curing. The separated egg whites can be reused, saving resources. Furthermore, the box-type curing box effectively solves the problem of flat yolks in dry curing, resulting in a salted egg yolk product with a better appearance. Summary of the Invention

[0006] One of the objectives of the present invention is to address the shortcomings of existing salting technologies and provide a method for efficiently separating and curing low-salt, high-quality salted egg yolks, thereby resolving the problems of long curing cycles, flat shapes, and suboptimal quality of salted egg yolks in the prior art. Another objective is to provide a simple and easy-to-operate curing method to enable industrialized production of salted egg yolks, providing a reference for the efficient separation and curing of low-salt, high-quality salted egg yolks. The present invention effectively shortens the curing time of salted egg yolks to 44 hours, resulting in salted egg yolks with a high oil yield, low NaCl content, a strong grittiness, a uniform texture, a neat shape, a unique flavor, and an orange-yellow color.

[0007] The technical solution adopted by the present invention is:

[0008] A method for efficiently separating and pickling low-salt-content, high-quality salted egg yolks, comprising the following steps:

[0009] (1) Salt nest preparation: Using a 4-aperture pickling box, evenly spread a layer of NaCl particles in the pickling nest (58 cm in diameter), maintaining a uniform thickness and forming a salt nest shape;

[0010] (2) Separation of egg white and yolk: Separate the egg white and yolk of fresh duck eggs and absorb the excess egg white from the yolk with filter paper;

[0011] (3) NaCl separation and pickling of egg yolks: Place the whole egg yolks from step (2) into the prepared salt nest, completely wrap the egg yolks with NaCl particles, close the lid of the pickling box, and place them in a ziplock bag for sealing;

[0012] (4) Ultrasonic assisted NaCl pickling of egg yolks: the duck egg yolks prepared in step (3) were placed in a box-type ultrasonic cleaning machine for pickling;

[0013] (5) Preparation of salted egg yolk samples: Take out the salted egg yolks that have been pickled, remove the NaCl on the surface of the salted egg yolks, and heat them to prepare cooked salted egg yolks.

[0014] Preferably, in step (1), the NaCl particles should be fine and uniform, not in a lumpy state, and the thickness of the salt pit should be kept consistent as much as possible.

[0015] Preferably, in step (2), duck eggs that are less than 3 days old and weigh 65±2 g are used.

[0016] Preferably, in step (2), the egg yolk and egg white are separated completely, and the integrity of the egg yolk needs to be maintained, and the egg yolk membrane cannot be broken.

[0017] Preferably, in step (3), NaCl is required to completely wrap the egg yolk.

[0018] Preferably, in step (4), the conditions for ultrasonic assisted pickling are 900-1100W and 20-30°C.

[0019] Preferably, in step (5), the method for preparing the cooked salted egg yolk is to heat the egg yolk in water at 80-100° C. for 20-30 min.

[0020] The beneficial effects of the present invention are:

[0021] 1. The raw material used in the present invention is whole egg yolk. The duck egg yolk is dry-separated and pickled by ultrasound in combination with NaCl. The separated duck egg white can be used for food processing, thereby avoiding waste of duck egg white and saving resources.

[0022] 2. The advantages of the present invention are that the oil yield and grittiness of salted egg yolk can be significantly improved, with the oil yield being increased by 21.73%.

[0023] 3. The present invention can effectively shorten the pickling time of salted egg yolks, improve the pickling efficiency, and reduce the pickling time of salted egg yolks from 30 days to 44-48 hours.

[0024] 4. The salt content of the salted egg yolk prepared by the present invention is lower than that of the salted egg yolk prepared by the traditional method, and the NaCl content is reduced from more than 2% to 1%, so that the salted egg yolk has a palatable NaCl content and meets the current people's pursuit of low-salt healthy food. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The following are the results of NaCl content in the salted egg yolks obtained in the examples and comparative examples.

[0026] Figure 2 The oil yield of the salted egg yolk obtained in each embodiment and comparative example is shown.

[0027] Figure 3 The textural characteristics of the salted egg yolks obtained in the embodiments and comparative examples are shown.

[0028] Figure 4 The following are the low-field nuclear magnetic resonance results of the salted egg yolks obtained in the embodiments and comparative examples.

[0029] Figure 5 The laser confocal microscopy results of the salted egg yolks obtained in the embodiments and comparative examples are shown.

[0030] Figure 6 1 is the microstructure of the salted egg yolk obtained in each embodiment and comparative example.

[0031] Figure 7 It is a physical picture of the salted egg yolk obtained in each embodiment and comparative example. DETAILED DESCRIPTION

[0032] The following will be combined with specific embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0033] A method for efficiently separating and pickling low-salt-content, high-quality salted egg yolks, comprising the following steps:

[0034] (1) Salt nest preparation: Using a 4-aperture pickling box, evenly spread a layer of NaCl particles in the pickling nest (58 cm in diameter), maintaining a uniform thickness and forming a salt nest shape;

[0035] (2) Separation of egg white and yolk: Separate the egg white and yolk of fresh duck eggs and absorb the excess egg white from the yolk with filter paper;

[0036] (3) Salted egg yolk pickling: Place the whole egg yolk without the egg white into the prepared salt pit, use NaCl particles to completely cover the egg yolk, close the lid of the pickling box and put it into a self-sealing bag and seal it; place it in a constant temperature incubator / box-type ultrasonic cleaning machine for pickling;

[0037] (4) Preparation of salted egg yolk samples: Take out the salted egg yolks that have been pickled, remove the NaCl on the surface of the salted egg yolks, and heat them to prepare cooked salted egg yolks.

[0038] The NaCl particles in step (1) should be fine and uniform, not in a lumpy state, and the thickness of the salt pit should be kept consistent as much as possible.

[0039] The egg yolk in step (2) needs to remain intact and the yolk membrane cannot be broken.

[0040] The temperature of the constant temperature incubator in step (3) is 20-30°C, and the ultrasonic condition is 600-1200W.

[0041] The salted egg yolk in step (4) is cooked by heating in water at 80-100° C. for 20-30 minutes.

[0042] The above method uses ultrasound to synergize with NaCl to pickle salted egg yolks. Ultrasonic treatment can accelerate the penetration of NaCl into the egg yolk. At the same time, ultrasound can destroy the structure of the egg yolk protein and accelerate the breakdown of the originally stable protein-lipid emulsion system in the egg yolk, thereby significantly improving the curing efficiency of the salted egg yolk and enhancing the quality of the salted egg yolk. Compared with salted egg yolks prepared by traditional methods, the salted egg yolks prepared by this method have a lower NaCl content, a higher oil yield, a stronger grittiness, and a shorter curing time. This invention provides a practical reference for the separation and curing of salted egg yolks, which is conducive to promoting the application of duck egg yolks in the food industry.

[0043] Example 1

[0044] A method for efficiently separating and pickling low-salt-content, high-quality salted egg yolks, comprising the following steps:

[0045] (1) Salt nest preparation: Using a 4-aperture pickling box, evenly spread a layer of NaCl particles in the pickling nest (58 cm in diameter), maintaining a uniform thickness and forming a salt nest shape;

[0046] (2) Separation of egg white and yolk: Separate the egg white and yolk of fresh duck eggs and absorb the excess egg white from the yolk with filter paper;

[0047] (3) NaCl separation and pickling of egg yolks: Place the whole egg yolks from step (2) into the prepared salt nest, completely wrap the egg yolks with NaCl particles, close the lid of the pickling box, and seal the egg yolks in a ziplock bag;

[0048] (4) Ultrasonic assisted NaCl pickling of egg yolks: Place the duck egg yolks prepared in step (3) in a box-type ultrasonic cleaning machine at 600-1200W and 20-30°C for 44 hours;

[0049] (5) Preparation of salted egg yolk samples: Take out the salted egg yolks that have been pickled, remove the NaCl on the surface of the salted egg yolks, and heat them to prepare cooked salted egg yolks.

[0050] Example 2

[0051] A method for efficiently separating and pickling low-salt-content, high-quality salted egg yolks, comprising the following steps:

[0052] (1) Salt nest preparation: Using a 4-aperture pickling box, evenly spread a layer of NaCl particles in the pickling nest (58 cm in diameter), maintaining a uniform thickness and forming a salt nest shape;

[0053] (2) Separation of egg white and yolk: Separate the egg white and yolk of fresh duck eggs and absorb the excess egg white from the yolk with filter paper;

[0054] (3) NaCl separation and pickling of egg yolks: Place the whole egg yolks from step (2) into the prepared salt nest, completely wrap the egg yolks with NaCl particles, close the lid of the pickling box, and place them in a ziplock bag for sealing;

[0055] (4) Ultrasonic assisted NaCl pickling of egg yolks: Place the duck egg yolks prepared in step (3) in a box-type ultrasonic cleaning machine at 600-1200W and 20-30°C for 48 hours;

[0056] (5) Preparation of salted egg yolk samples: Take out the salted egg yolks that have been pickled, remove the NaCl on the surface of the salted egg yolks, and heat them to prepare cooked salted egg yolks.

[0057] Comparative Example 1

[0058] (1) Separation of egg white and yolk: Separate the egg white and yolk of fresh duck eggs and absorb the excess egg white from the yolk with filter paper;

[0059] (2) Egg yolk sample preparation: Egg yolk with excess egg white removed was heated to prepare cooked egg yolk.

[0060] Comparative Example 2

[0061] (1) Salt nest preparation: Using a 4-aperture pickling box, evenly spread a layer of NaCl particles in the pickling nest (58 cm in diameter), maintaining a uniform thickness and forming a salt nest shape;

[0062] (2) Separation of egg white and yolk: Separate the egg white and yolk of fresh duck eggs and absorb the excess egg white from the yolk with filter paper;

[0063] (3) NaCl separation and pickling of egg yolks: Place the whole egg yolks from step (2) into the prepared salt nest, completely cover the egg yolks with NaCl particles, close the lid of the pickling box, place the egg yolks in a ziplock bag, and place them in a constant temperature incubator at 20-30°C for 48 hours;

[0064] (4) Preparation of salted egg yolk samples: Take out the salted egg yolks that have been pickled, remove the NaCl on the surface of the salted egg yolks, and heat them to prepare cooked salted egg yolks.

[0065] 1. Determination of NaCl content

[0066] The NaCl content of salted egg yolk was determined by direct titration. 1 mL of 5% potassium chromate was used as an indicator and titrated with 0.1 M (standardized) silver nitrate solution until a brick-red precipitate formed in the solution. The volume of silver nitrate consumed was recorded. The NaCl content of the sample was calculated according to the following formula. The results are shown in the figure below. Figure 1 shown.

[0067] NaCl content (%) = (0.05844 × N × V) / m × 100

[0068] Where: N is the concentration of AgNO3 (mol / L); V is the consumed volume of AgNO3 (mL); m is the sample weight (g); 0.05844 is the equivalent of NaCl.

[0069] 2. Determination of oil yield

[0070] 3 g of salted egg yolk sample was added to 25 mL of isopropanol / n-hexane (2:3, v:v) mixture and homogenized at 9,000 r / min for 1 min. The filtrate was evaporated in a water bath at 55°C to remove most of the solvent, and then dried in an oven at 105°C to constant weight. The residue was weighed as total fat M1 (g). 3 g of sample was mixed with 25 mL of ultrapure water and homogenized at 9,000 r / min for 1 min. After centrifugation at 10°C and 8,000×g for 15 min, 25 mL of isopropanol / n-hexane (2:3, v:v) mixture was added to the supernatant. The organic solvent-lipid layer extracted by separation was evaporated in a water bath at 55°C to remove most of the solvent, and then dried in an oven at 105°C to constant weight as free fat M2 (g). The oil yield was calculated according to the following formula, and the measurement results are as follows: Figure 2 shown.

[0071]

[0072] 3. Determination of texture characteristics

[0073] The hardness, elasticity and chewiness of salted egg yolk were measured using a texture analyzer. The pre-test speed was 5.0 mm / s, the test speed was 2.0 mm / s, the post-test speed was 5.0 mm / s, and the compression rate was 30%. The test results are as follows: Figure 3 shown.

[0074] 4. Low-field NMR analysis

[0075] The spin-spin relaxation time (T2) of salted egg yolk was measured using a low-field nuclear magnetic resonance imaging analyzer. The whole salted egg yolk was placed in a 60mm diameter radio frequency coil, and the CPMG (Carr-Purcell-Meiboom-Gill) pulse sequence was used to collect the decay signal. The sampling frequency was 200kHz, the main frequency was 21MHz, the radio frequency delay was 0.02ms, the 90° pulse width was 14.00μs, the analog gain was 20.0dB, the digital gain was 3dB, the repeated sampling waiting time was 2,000ms, and the accumulation times were 4. After obtaining the exponential decay graph, the Multi-ExpInv Analysis software was used for inversion, the number of relaxation time points was 200, and the number of iterations was 100,000 times. The spin-spin relaxation time of the egg yolk sample is as follows Figure 4 shown.

[0076] 5. Laser Confocal Microscopy

[0077] The egg yolk sample was dissolved in Nile Blue A buffer and Nile Red solution and stirred manually until homogeneous. 20 μL of the sample solution was applied to a glass slide. Experimental parameters: In fluorescence mode, HeNe-R excitation wavelength was 533 nm and emission wavelength was 630 nm. Under the excitation wavelength of 540 nm, HeNe-G with emission wavelength of 488 nm was used. The low-field NMR results of the egg yolk sample are shown in Figure 2. Figure 5 shown.

[0078] 6. Determination of the Microstructure of Salted Egg Yolk

[0079] The egg yolk samples were immersed in 2.5% glutaraldehyde (0.2M phosphate buffer, pH = 7.2) for 2 hours; then immersed in 0.2M phosphate buffer (pH = 7.2) for 15 minutes; then immersed in deionized water for 15 minutes; and then dehydrated in a gradient of 50%, 70%, 80%, 90%, and 100% ethanol for 15 minutes. After freeze-drying, the samples were sprayed with gold and scanned by SEM. The results are shown in Figure 2. Figure 6 shown.

[0080] Figure 1The results showed that the NaCl content in Comparative Example 1 was extremely low, at only 0.12%; the NaCl content in Comparative Example 2 remained consistent with that in Example 1, at 1.02%; and the NaCl content in Example 3 was significantly increased, reaching 1.11%. This indicates that the synergistic effect of ultrasound significantly accelerated the penetration of NaCl into the egg yolk under the same curing time. The continuous ultrasonic vibrations generated and transmitted enormous energy, causing cavitation. This cavitation reduced the aggregation of egg yolk protein particles, facilitating NaCl penetration.

[0081] Figure 2 The results show that compared with Comparative Example 2, the oil yield of Example 1 increased by 29.09%, and the oil yield of Example 2 increased by 76.92%. This phenomenon can be observed visually with the naked eye from the abstract schematic diagram. Within a certain range, the oil yield of salted egg yolk is directly proportional to the NaCl content, and the increase in oil yield is often accompanied by a decrease in moisture content, corresponding to the moisture content result. The NaCl content of Example 2 increased significantly, indicating that ultrasound increased the NaCl content of salted egg yolk, and therefore the oil yield of Example 2 was significantly improved. In addition, low-frequency ultrasound can produce intense cavitation and mechanical effects, accelerating the breakdown of the originally stable protein-lipid system in the egg yolk, causing the excellent emulsification system in the egg yolk to become unstable, thereby improving the effect of oil-water separation. This leads to the freeing of more fat during the heating process of the salted egg yolk, increasing the oil yield. Therefore, under the same NaCl content, the oil yield of Example 1 is significantly higher than that of Comparative Example 2, indicating that ultrasound may have destroyed the structure of the protein and increased the oil yield of the salted egg yolk. The above results show that ultrasound not only improves the oil yield of salted egg yolk by promoting the penetration of NaCl, but also improves the oil yield of salted egg yolk by changing the structure of protein, which effectively shortens the pickling time of salted egg yolk.

[0082] Figure 3 The results show that: comparing the samples of Comparative Example 2 and Example 1 with the same NaCl content, the hardness of Example 1 is significantly increased, which may be because the ultrasonic treatment enhances the interaction between proteins, resulting in an increase in gel hardness. The elasticity of the salted egg yolks in Examples 1 and 2 increases, but there is no significant difference. For Example 2, in addition to hardness, its chewiness is also significantly higher than that of Example 1. Analysis of the reasons shows that the increase in NaCl content will prompt the salted egg yolk to form a tighter gel network structure, resulting in a significant increase in the hardness of the salted egg yolk gel, so the chewiness is significantly improved. Ultrasound and Na + The synergistic effect of the salted egg yolk and the low-density lipoprotein in the salted egg yolk may have destroyed the structure of the low-density lipoprotein and enhanced the release of free lipids in the salted egg yolk. This resulted in a tighter protein-protein bond, thus improving the chewiness of Example 2. +The effect of ultrasound on the electrostatic interaction of proteins is also one of the reasons for the increase in chewiness. The above results show that the salted egg yolks prepared by ultrasound and NaCl pickling (Examples 1 and 2) have better gel quality.

[0083] Figure 4 The results show that three proton peaks were observed in Comparative Example 2, Example 1 and Example 2, marked as T 21 , T 22 , T 23 , whereas no T was observed in the egg yolk of Comparative Example 1 21 The proton peak indicates that there are no hydrogen protons tightly bound to proteins in cooked fresh egg yolks, that is, there is no bound water in Comparative Example 1, which can also be used to explain the higher moisture content in Comparative Example 1. Comparing the relaxation spectra of the three salted egg yolk samples (Comparative Example 2, Example 1 and Example 2), the peaks of Example 1 in each region are significantly shifted to the left, indicating that the hydrogen protons tightly bound to proteins migrate to short relaxation times after ultrasonic synergistic treatment, and the relaxation time is significantly lower than that of Comparative Example 1. This shows that under the same NaCl content, ultrasonic action increases lipid release, promotes the shrinkage and dehydration of salted egg yolks, shortens the relaxation time, and leads to a decrease in the mobility of hydrogen protons. Compared with Example 1, the relaxation time of Example 2 is further reduced. Analysis of the reasons shows that in addition to the ultrasonic effect, the increase in NaCl content enhances the dehydration of salted egg yolks and weakens the mobility of hydrogen protons to a greater extent, resulting in a significant decrease in the relaxation time of Example 2. From Figure 4 It can be seen that the content of strongly bound water in the sample of Example 2 is the highest.

[0084] Figure 5 The results show that compared with the fresh egg yolk of Comparative Example 1, the protein particles in the salted egg yolk (Comparative Example 2, Example 1 and Example 2) are smaller, which may be related to the destruction of lipoproteins during the curing process. NaCl curing can lead to the release of free lipids in the salted egg yolk, causing the protein to lose some of its emulsifying ability. Compared with Comparative Example 2, it can be seen that the protein particles in Examples 1 and 2 are significantly smaller and more evenly distributed, and the free lipid content is increased, indicating that ultrasound and NaCl curing enhance the degree of destruction of lipoproteins in the salted egg yolk, enhance the release of free lipids, and improve the oil yield of the salted egg yolk.

[0085] Figure 6The result shows that: in salted egg yolk (Comparative Example 2, Example 1, Example 2), polyhedron particles are arranged closely, which is mainly due to the dehydration in the pickling process, which is consistent with the moisture content result variation trend, indicating that the pickling method used in this study can induce salted egg yolk to form gravel, thereby improving the mouthfeel of salted egg yolk. Comparative Example 2 and Example 2 of the same pickling time are compared, and it is found that more NaCl particles are distributed in Example 2, indicating that ultrasonic collaborative pickling promotes the penetration of NaCl in salted egg yolk, which is consistent with the NaCl content result. Comparative Example 2 and Example 1 of the sample of the same NaCl content are compared, and it is found that in Example 1, polyhedron particles are arranged closely and are evenly distributed, indicating that ultrasonic collaborative treatment improves the uniformity of salted egg yolk gel structure. The salted egg yolk pickled in ultrasonic collaborative NaCl, the pores in the gel structure are significantly reduced, and the hardness change with salted egg yolk is the same trend, which helps to improve the edible quality of salted egg yolk.

[0086] The above embodiments are merely preferred technical solutions of the present invention and should not be construed as limiting the present invention. The embodiments and features in the embodiments of this application may be arbitrarily combined with each other unless they conflict. The scope of protection of the present invention shall be the technical solutions described in the claims, including equivalent alternatives to the technical features of the technical solutions described in the claims. Equivalent alternatives and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A method for efficiently separating and curing low-salt-content, high-quality salted egg yolks, characterized by: The method comprises the following steps: (1) Salt nest preparation: Use a pickling box to evenly spread a layer of NaCl particles in the pickling nest, keeping the thickness uniform and forming a salt nest shape; (2) Separation of egg white and yolk: Separate the egg white and yolk of fresh duck eggs and absorb the excess egg white from the yolk with filter paper; (3) NaCl pickled egg yolk: Place the whole egg yolk prepared in step (2) into the prepared salt nest, completely cover the egg yolk with NaCl particles, close the lid of the pickling box, and place it in a ziplock bag for sealing; (4) Ultrasonic assisted NaCl pickling of egg yolk: The duck egg yolk in step (3) was pickled with NaCl using ultrasonic assisted pickling at a temperature of 600-1200 W and a temperature of 20-30°C. (5) Preparation of salted egg yolk samples: Take out the salted egg yolks that have been pickled, remove the NaCl on the surface of the salted egg yolks, and heat them to prepare cooked salted egg yolks.

2. The method for efficiently separating and curing low-salt-content high-quality salted egg yolks according to claim 1, wherein: In step (1), the NaCl particles cannot be in a lumpy shape, and the thickness of the salt pit should be kept consistent as much as possible.

3. The method for efficiently separating and curing low-salt-content high-quality salted egg yolks according to claim 1, characterized in that: In the step (2), duck eggs that are less than 3 days old and weigh 63-67 g are required.

4. The method for efficiently separating and curing low-salt-content high-quality salted egg yolks according to claim 1, wherein: In step (2), the egg yolk and egg white must be completely separated and the egg yolk membrane must not be broken.

5. The method for efficiently separating and curing low-salt-content high-quality salted egg yolks according to claim 1, characterized in that: In the step (3), NaCl is used to completely coat the duck egg yolk.

6. The method for efficiently separating and curing low-salt-content, high-quality salted egg yolks according to claim 1, characterized in that: In the step (5), the method for preparing the cooked salted egg yolk is to heat it in water at 80-100° C. for 20-30 min.

Images