Method for freezing pseudosciaena crocea based on three-frequency orthogonal ultrasonic-assisted technology

Abstract

The invention discloses a method for freezing pseudosciaena crocea under the assistance of three-frequency orthogonal ultrasound, which specifically comprises the following steps: step S1, knocking the head of fresh pseudosciaena crocea, slaughtering, removing gills and viscera, then washing, filling into a polyethylene bag, and carrying out vacuum packaging; s2, carrying out freezing treatment and cooling through three-frequency orthogonal ultrasonic-assisted freezing with the ultrasonic power of 175w; and S3, observing the temperature change through a T-shaped thermocouple, taking out the large yellow croaker when the temperature is reduced to-18 DEG C, and storing the large yellow croaker in a refrigerator at-18 DEG C for 5 days. According to the method for freezing the pseudosciaena crocea through the three-frequency orthogonal ultrasonic-assisted technology, the water holding capacity of fish meat can be improved, the lipid oxidation degree is effectively inhibited, and the protein aggregation degree and the protein denaturation degree are reduced.

Description

Technical Field

[0001] The present invention relates to the field of ultrasonic-assisted technology, in particular to a method for freezing large yellow croaker based on a three-frequency orthogonal ultrasonic-assisted technology. Background Art

[0002] Ultrasound is a sound wave with a frequency beyond human hearing, ranging from 20 kHz to 500 MHz. Depending on the frequency of application, it can be categorized as low-frequency or high-frequency. Low-frequency ultrasound has higher energy and is widely used in food processing and storage. Cavitation is the primary physical mechanism by which ultrasound operates in liquid media.

[0003] Cavitation generally involves three stages: the formation, growth, and violent collapse of cavitation bubbles. When ultrasound waves are introduced into a container filled with liquid, the liquid vibrations generate tens of thousands of tiny bubbles, or cavitation bubbles. These bubbles grow in the negative pressure zone created by the longitudinal propagation of ultrasound waves and rapidly close in the positive pressure zone, thereby being compressed and stretched under alternating positive and negative pressures. At the moment the bubbles are compressed and collapse, enormous instantaneous pressure is generated, typically reaching tens to hundreds of MPa. When this collapse occurs near a solid surface, it generates microjets with defined pressure (100 MPa), temperature (5000 K), and velocity (400 km / s), thereby increasing the mass transfer rate. Ultrasound waves can also induce micro-agitation in the liquid, thereby altering mass transfer.

[0004] Current aquatic product freezing techniques, such as air blast freezing and immersion freezing (IF), suffer from common drawbacks such as slow freezing speeds and reduced food quality. Ultrasonic-assisted freezing is an emerging freezing technology. Ultrasonic-assisted freezing adds an ultrasonic field to immersion freezing, leveraging the cavitation effect to increase the freezing rate and improve food quality. Ice crystal formation is the most significant factor affecting food quality during freezing, and large ice crystals can cause severe damage to tissues. Ultrasonic-assisted freezing has been shown to effectively induce nucleation, control the crystallization process, reduce ice crystal size, inhibit protein denaturation, and improve food quality during freezing. However, current ultrasonic-assisted freezing methods superimpose ultrasound waves on a single horizontal, two-dimensional plane, ignoring the three-dimensional nature of space. This results in problems such as uneven ultrasonic field strength during food freezing and cavitation shielding within the ultrasonic field. Ultrasonic-assisted freezing is being applied to cover the entire three-dimensional space using ultrasound waves in both horizontal and vertical planes to mitigate the drawbacks of uneven ultrasound propagation and cavitation shielding associated with multi-frequency ultrasonic-assisted freezing. Summary of the Invention

[0005] The present invention proposes a method for freezing large yellow croaker based on triple-frequency orthogonal ultrasound-assisted technology. The ultrasound-assisted technology is applied to the freezing process of large yellow croaker to study the effects of triple-frequency orthogonal ultrasound-assisted freezing on the quality characteristics of large yellow croaker, such as thawing loss, water holding capacity, LF-NMR, MRI, TPA analysis, TBA, protein solubility and surface hydrophobicity. The cavitation effect generated by ultrasound can effectively induce nucleation, control the crystallization process, reduce the size of ice crystals, improve the water holding capacity of fish meat, and effectively inhibit the degree of lipid oxidation and reduce the degree of protein aggregation and denaturation.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] The three-frequency orthogonal ultrasound-assisted freezing method specifically includes the following steps:

[0008] Step S1: slaughtering fresh large yellow croaker by knocking the head, removing the gills and internal organs, then rinsing and placing in polyethylene bags for vacuum packaging;

[0009] Step S2, cooling by three-frequency orthogonal (horizontal 20, 28 kHz + vertical 40 kHz) ultrasonic assisted freezing (TOUAF) with an ultrasonic power of 175 W;

[0010] Step S3: Observe the temperature change by using a T-type thermocouple. When the temperature drops to -18°C, take out the large yellow croaker and store it in a refrigerator at -18°C for 5 days.

[0011] As a preferred embodiment, the body length of the large yellow croaker is about 35±5.0 cm.

[0012] As a preferred embodiment, the body mass is about 500g±20g.

[0013] As a preferred embodiment, a calcium chloride solution with a mass concentration of 298 g / L is used as the refrigerant.

[0014] As a preferred embodiment, the temperature is maintained at -25.0°C.

[0015] As a preferred embodiment, the ultrasonic device is set to an alternating mode of 30 seconds on and 30 seconds off to minimize the negative impact of thermal effects during the freezing process.

[0016] The above-mentioned three-frequency orthogonal ultrasonic assisted freezing method is applied to fish freezing.

[0017] The method for freezing large yellow croaker based on triple-frequency orthogonal ultrasound-assisted technology specifically comprises the following steps:

[0018] Step S1: slaughtering fresh large yellow croaker by knocking the head, removing the gills and internal organs, then rinsing and placing in polyethylene bags for vacuum packaging;

[0019] Step S2, cooling by three-frequency orthogonal (horizontal 20, 28 kHz + vertical 40 kHz) ultrasonic assisted freezing (TOUAF) with an ultrasonic power of 175 W;

[0020] Step S3, observing the temperature change by using a T-type thermocouple, taking out the large yellow croaker when the temperature drops to -18°C, and storing it in a refrigerator at -18°C for 5 days;

[0021] Step S4. The experiment was divided into five groups, namely, an ultrasonic assisted freezing treatment group (TOUAF-160) with an ultrasonic power of 160W and three orthogonal frequencies (horizontally 20, 28kHz + vertically 40kHz), an ultrasonic assisted freezing treatment group (TOUAF-175) with an ultrasonic power of 175W, an ultrasonic assisted freezing treatment group (TOUAF-190) with an ultrasonic power of 190W, an ultrasonic assisted freezing treatment group (TOUAF-205) with an ultrasonic power of 205W, and a group without ultrasonic treatment (immersion freezing IF) as the control group.

[0022] Beneficial effects:

[0023] The triple-frequency orthogonal ultrasound-assisted freezing technology used in the method for freezing large yellow croaker of the present invention can improve the water holding capacity of fish meat, and effectively inhibit the degree of lipid oxidation, reduce the degree of protein aggregation and reduce the degree of protein denaturation. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of thawing loss of each experimental group in Example 1 of the present invention.

[0025] Figure 2 Schematic diagram of the water holding capacity of each experimental group in Example 3 of the present invention.

[0026] Figure 3 Schematic diagram of the transverse relaxation spectrum of each experimental group in Example 4 of the present invention.

[0027] Figure 4 Schematic diagram of magnetic resonance imaging of each experimental group in Example 4 of the present invention.

[0028] Figure 5 Schematic diagram of TBA content in each experimental group in Example 6 of the present invention.

[0029] Figure 6 Schematic diagram of protein solubility of each experimental group in Example 7 of the present invention.

[0030] Figure 7 Schematic diagram of the surface hydrophobicity of each experimental group in Example 8 of the present invention.

[0031] Figure 8 Schematic diagram of the ultrasonic device of the present invention.

[0032] Table 1 is a comparison of the color differences of the experimental groups in Example 3 of the present invention.

[0033] Table 2 shows the texture characteristics of each experimental group in Example 5 of the present invention. DETAILED DESCRIPTION

[0034] The following is a detailed description of an embodiment of the present invention in conjunction with the accompanying drawings: This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and specific operation process are given, but the protection scope of the present invention is not limited to the following embodiment.

[0035] Example 1

[0036] The method for freezing large yellow croaker based on triple-frequency orthogonal ultrasound-assisted technology specifically comprises the following steps:

[0037] Step S1: slaughtering fresh large yellow croaker by knocking the head, removing the gills and internal organs, then rinsing and placing in polyethylene bags for vacuum packaging;

[0038] Step S2, cooling by three-frequency orthogonal (horizontal 20, 28 kHz + vertical 40 kHz) ultrasonic assisted freezing (TOUAF) with an ultrasonic power of 175 W;

[0039] Step S3, observing the temperature change by using a T-type thermocouple, taking out the large yellow croaker when the temperature drops to -18°C, and storing it in a refrigerator at -18°C for 5 days;

[0040] Step S4. The experiment was divided into five groups, namely, an ultrasonic assisted freezing treatment group (TOUAF-160) with an ultrasonic power of 160W and three orthogonal frequencies (horizontally 20, 28kHz + vertically 40kHz), an ultrasonic assisted freezing treatment group (TOUAF-175) with an ultrasonic power of 175W, an ultrasonic assisted freezing treatment group (TOUAF-190) with an ultrasonic power of 190W, an ultrasonic assisted freezing treatment group (TOUAF-205) with an ultrasonic power of 205W, and a group without ultrasonic treatment (immersion freezing IF) as the control group.

[0041] Other parameters were as follows: large yellow croaker was approximately 35 ± 5.0 cm long and weighed approximately 500 ± 20 g. A calcium chloride solution with a mass concentration of 298 g / L was used as the refrigerant and maintained at −25.0°C. The ultrasonic device was set to an alternating mode of 30 seconds on and 30 seconds off to minimize the negative effects of thermal effects during the freezing process.

[0042] Thaw loss reflects the loss of water and the stability of water in the sample. Thaw loss is closely related to the muscle tissue state of the food. The liquid lost after thawing is actually caused by ice crystals destroying cells and tissues during the freezing process. The increase in thawing loss also affects the flavor of the fish. Lower thawing loss is conducive to the maintenance of fish flavor substances. The thawing loss of large yellow croaker samples treated with TOUAF changed significantly. The thawing loss of the TOUAF-175 ultrasonic treatment group was the lowest at 2.34%. The results showed that the ultrasonic assisted freezing technology with three orthogonal frequencies (horizontally 20, 28kHz + vertically 40kHz) with an ultrasonic power of 175W effectively reduced the thawing loss rate of large yellow croaker samples.

[0043] Example 2

[0044] The method for freezing large yellow croaker based on triple-frequency orthogonal ultrasound-assisted technology specifically comprises the following steps:

[0045] Step S1: slaughtering fresh large yellow croaker by knocking the head, removing the gills and internal organs, then rinsing and placing in polyethylene bags for vacuum packaging;

[0046] Step S2, cooling by three-frequency orthogonal (horizontal 20, 28 kHz + vertical 40 kHz) ultrasonic assisted freezing (TOUAF) with an ultrasonic power of 175 W;

[0047] Step S3, observing the temperature change by using a T-type thermocouple, taking out the large yellow croaker when the temperature drops to -18°C, and storing it in a refrigerator at -18°C for 5 days;

[0048] Step S4. The experiment was divided into five groups, namely, an ultrasonic assisted freezing treatment group (TOUAF-160) with an ultrasonic power of 160W and three orthogonal frequencies (horizontally 20, 28kHz + vertically 40kHz), an ultrasonic assisted freezing treatment group (TOUAF-175) with an ultrasonic power of 175W, an ultrasonic assisted freezing treatment group (TOUAF-190) with an ultrasonic power of 190W, an ultrasonic assisted freezing treatment group (TOUAF-205) with an ultrasonic power of 205W, and a group without ultrasonic treatment (immersion freezing IF) as the control group.

[0049] Other parameters were as follows: large yellow croaker was approximately 35 ± 5.0 cm long and weighed approximately 500 ± 20 g. A calcium chloride solution with a mass concentration of 298 g / L was used as the refrigerant and maintained at −25.0°C. The ultrasonic device was set to an alternating mode of 30 seconds on and 30 seconds off to minimize the negative effects of thermal effects during the freezing process.

[0050] WHC reflects the ability of cells to retain residual water in fish from different perspectives. Figure 2As shown, the WHC of samples treated with TOUAF was higher than that of the IF group (75.39%), ranging from 77.4% to 79.45% overall. The TOUAF-175 ultrasonic treatment group had the highest water-holding capacity. This is because rapid freezing shortens the time it takes for large yellow croaker samples to pass through the zone of maximum ice crystal formation, resulting in smaller and more uniform ice crystals formed within the food, and thus reducing the physical damage caused by ice crystals to cells. These results indicate that TOUAF-175 ultrasonic treatment effectively improves the water-holding capacity of fish muscle tissue and reduces damage to muscle tissue caused by ice crystals formed during freezing.

[0051] Example 3

[0052] The method for freezing large yellow croaker based on triple-frequency orthogonal ultrasound-assisted technology specifically comprises the following steps:

[0053] Step S1: slaughtering fresh large yellow croaker by knocking the head, removing the gills and internal organs, then rinsing and placing in polyethylene bags for vacuum packaging;

[0054] Step S2, cooling by three-frequency orthogonal (horizontal 20, 28 kHz + vertical 40 kHz) ultrasonic assisted freezing (TOUAF) with an ultrasonic power of 175 W;

[0055] Step S3, observing the temperature change by using a T-type thermocouple, taking out the large yellow croaker when the temperature drops to -18°C, and storing it in a refrigerator at -18°C for 5 days;

[0056] Step S4. The experiment was divided into five groups, namely, an ultrasonic assisted freezing treatment group (TOUAF-160) with an ultrasonic power of 160W and three orthogonal frequencies (horizontally 20, 28kHz + vertically 40kHz), an ultrasonic assisted freezing treatment group (TOUAF-175) with an ultrasonic power of 175W, an ultrasonic assisted freezing treatment group (TOUAF-190) with an ultrasonic power of 190W, an ultrasonic assisted freezing treatment group (TOUAF-205) with an ultrasonic power of 205W, and a group without ultrasonic treatment (immersion freezing IF) as the control group.

[0057] Other parameters were as follows: large yellow croaker was approximately 35 ± 5.0 cm long and weighed approximately 500 ± 20 g. A calcium chloride solution with a mass concentration of 298 g / L was used as the refrigerant and maintained at −25.0°C. The ultrasonic device was set to an alternating mode of 30 seconds on and 30 seconds off to minimize the negative effects of thermal effects during the freezing process.

[0058] Color is one of the most intuitive criteria consumers use to judge food quality. Myoglobin content correlates with the a* value, while lipid oxidation L* and b* values ​​correlate. As shown in Table 1, the L* values ​​of large yellow croaker samples subjected to different freezing treatments exhibited varying degrees of variation. The group treated with TOUAF-175 ultrasonication exhibited the lowest L* values. This is because rapid freezing with TOUAF-175 ultrasonication reduces water loss, and the lower surface free water content reduces color change. Total color difference (ΔE) better reflects overall color change, with a similar trend to the L* value. The results indicate that samples treated with TOUAF-175 ultrasonication exhibited the best results, with minimal changes in total color difference ΔE. The rapid freezing with TOUAF-175 inhibits ice crystal growth to a certain extent. Ice crystal damage to cells leads to light scattering, which is also a factor in color change. Rapid freezing with TOUAF-175 maintains the integrity of muscle cells and reduces water loss in the fish. The three-frequency orthogonal ultrasound expands the cavitation area, promotes the cavitation effect, and greatly reduces the damage of ice crystals to fish tissues.

[0059] Table 1 Comparison of color difference among experimental groups

[0060]

[0061] Example 4

[0062] The method for freezing large yellow croaker based on triple-frequency orthogonal ultrasound-assisted technology specifically comprises the following steps:

[0063] Step S1: slaughtering fresh large yellow croaker by knocking the head, removing the gills and internal organs, then rinsing and placing in polyethylene bags for vacuum packaging;

[0064] Step S2, cooling by three-frequency orthogonal (horizontal 20, 28 kHz + vertical 40 kHz) ultrasonic assisted freezing (TOUAF) with an ultrasonic power of 175 W;

[0065] Step S3, observing the temperature change by using a T-type thermocouple, taking out the large yellow croaker when the temperature drops to -18°C, and storing it in a refrigerator at -18°C for 5 days;

[0066] Step S4. The experiment was divided into five groups, namely, an ultrasonic assisted freezing treatment group (TOUAF-160) with an ultrasonic power of 160W and three orthogonal frequencies (horizontally 20, 28kHz + vertically 40kHz), an ultrasonic assisted freezing treatment group (TOUAF-175) with an ultrasonic power of 175W, an ultrasonic assisted freezing treatment group (TOUAF-190) with an ultrasonic power of 190W, an ultrasonic assisted freezing treatment group (TOUAF-205) with an ultrasonic power of 205W, and a group without ultrasonic treatment (immersion freezing IF) as the control group.

[0067] Other parameters were as follows: large yellow croaker was approximately 35 ± 5.0 cm long and weighed approximately 500 ± 20 g. A calcium chloride solution with a mass concentration of 298 g / L was used as the refrigerant and maintained at −25.0°C. The ultrasonic device was set to an alternating mode of 30 seconds on and 30 seconds off to minimize the negative effects of thermal effects during the freezing process.

[0068] The water distribution and migration in the sample can be measured by measuring the T2 relaxation time of hydrogen protons through low-frequency nuclear magnetic resonance (LF-NMR). The three peaks in the curve represent the three states of water in the fish body. 21 As represented by the water, its state is stable and difficult to change. Non-flowing water is the main state of water in fish body, distributed in the muscle fibers of fish, and is represented by T 22 Indicates. T 23 It is free water that can flow freely between cells and easily lead to water loss. Most of the water in the fish body exists in the form of non-flowing water. 22 The change of peak value can reflect the distribution and migration of water in the sample. The group treated with TOUAF has obvious advantages, among which TOUAF-175 has a higher T 22 The values ​​were higher, indicating the highest immobile water content. This indicates that TOUAF-175 sonication reduced cell damage caused by ice crystal growth and effectively inhibited the migration of immobile water. The results show that TOUAF-175 sonication enhanced the vertical and horizontal ultrasonic field strengths, expanded the cavitation zone, promoted the cavitation effect, formed small and uniform ice crystals, reduced the free water content, and reduced the migration of intracellular water during sample freezing.

[0069] Magnetic resonance imaging (MRI) can directly reflect the distribution of water content. The red area indicates a higher water content, and the blue area indicates a lower water content. Figure 4 The IF group exhibited a yellowish appearance, indicating that some water had migrated and been lost from the sample. The TOUAF group generally exhibited a deeper red color. These results indicate that TOUAF-175 ultrasonic treatment enhanced the vertical and horizontal ultrasonic field strengths, expanded the cavitation zone, promoted the cavitation effect, formed small, uniform ice crystals, reduced the free water content, and minimized the migration of intracellular water during sample freezing.

[0070] Example 5

[0071] The method for freezing large yellow croaker based on triple-frequency orthogonal ultrasound-assisted technology specifically comprises the following steps:

[0072] Step S1: slaughtering fresh large yellow croaker by knocking the head, removing the gills and internal organs, then rinsing and placing in polyethylene bags for vacuum packaging;

[0073] Step S2, cooling by three-frequency orthogonal (horizontal 20, 28 kHz + vertical 40 kHz) ultrasonic assisted freezing (TOUAF) with an ultrasonic power of 175 W;

[0074] Step S3: Observe the temperature change by using a T-type thermocouple. When the temperature drops to -18°C, take out the large yellow croaker and store it in a refrigerator at -18°C for 5 days.

[0075] Step S4. The experiment was divided into five groups, namely, an ultrasonic assisted freezing treatment group (TOUAF-160) with an ultrasonic power of 160W and three orthogonal frequencies (horizontally 20, 28kHz + vertically 40kHz), an ultrasonic assisted freezing treatment group (TOUAF-175) with an ultrasonic power of 175W, an ultrasonic assisted freezing treatment group (TOUAF-190) with an ultrasonic power of 190W, an ultrasonic assisted freezing treatment group (TOUAF-205) with an ultrasonic power of 205W, and a group without ultrasonic treatment (immersion freezing IF) as the control group.

[0076] Other parameters were as follows: large yellow croaker was approximately 35 ± 5.0 cm long and weighed approximately 500 ± 20 g. A calcium chloride solution with a mass concentration of 298 g / L was used as the refrigerant and maintained at −25.0°C. The ultrasonic device was set to an alternating mode of 30 seconds on and 30 seconds off to minimize the negative effects of thermal effects during the freezing process.

[0077] Textural properties are the most intuitive evaluation of aquatic products by consumers. Texture characteristics such as hardness, chewiness, and resilience are undoubtedly important factors in food and directly influence consumer choice. Large yellow croaker samples exhibited varying degrees of hardness after freezing (Table 2). The highest hardness, 5365.53 g, was achieved after TOUAF-175 ultrasonic treatment. Furthermore, compared to the IF group, TOUAF-175 showed an increase in elasticity by 0.25%, cohesion by 0.90%, chewiness by 1.16%, and resilience by 0.99%. By accelerating the freezing rate, TOUAF-175 ultrasonic treatment promotes the formation of fine, uniform ice crystals, thereby preventing water loss and protein aggregation caused by ice crystals disrupting muscle fibers. TOUAF-175 ultrasonic treatment exhibits superior texture properties. This is because the ultrasonic power at this power releases less latent heat during the freezing process, causing less damage to muscle tissue, thus ensuring the quality of the large yellow croaker samples. The results showed that TOUAF-175 ultrasonic treatment could improve the quality of frozen large yellow croaker, and selecting an ultrasonic power of 175w had a more positive effect on the textural properties of large yellow croaker.

[0078] Table 2 Texture characteristics of each experimental group

[0079]

[0080] Example 6

[0081] The method for freezing large yellow croaker based on triple-frequency orthogonal ultrasound-assisted technology specifically comprises the following steps:

[0082] Step S1: slaughtering fresh large yellow croaker by knocking the head, removing the gills and internal organs, then rinsing and placing in polyethylene bags for vacuum packaging;

[0083] Step S2, cooling by three-frequency orthogonal (horizontal 20, 28 kHz + vertical 40 kHz) ultrasonic assisted freezing (TOUAF) with an ultrasonic power of 175 W;

[0084] Step S3, observing the temperature change by using a T-type thermocouple, taking out the large yellow croaker when the temperature drops to -18°C, and storing it in a refrigerator at -18°C for 5 days;

[0085] Step S4. The experiment was divided into five groups, namely, an ultrasonic assisted freezing treatment group (TOUAF-160) with an ultrasonic power of 160W and three orthogonal frequencies (horizontally 20, 28kHz + vertically 40kHz), an ultrasonic assisted freezing treatment group (TOUAF-175) with an ultrasonic power of 175W, an ultrasonic assisted freezing treatment group (TOUAF-190) with an ultrasonic power of 190W, an ultrasonic assisted freezing treatment group (TOUAF-205) with an ultrasonic power of 205W, and a group without ultrasonic treatment (immersion freezing IF) as the control group.

[0086] Other parameters were as follows: large yellow croaker was approximately 35 ± 5.0 cm long and weighed approximately 500 ± 20 g. A calcium chloride solution with a mass concentration of 298 g / L was used as the refrigerant and maintained at −25.0°C. The ultrasonic device was set to an alternating mode of 30 seconds on and 30 seconds off to minimize the negative effects of thermal effects during the freezing process.

[0087] TBA is used to assess the extent of lipid oxidation in fish by detecting secondary oxidation products. Figure 5 The results showed that the TBA values ​​of each group of samples changed to varying degrees after different freezing treatments. Treatment with TOUAF-175 significantly reduced the TBA value, reaching 0.108 mg MDA / kg (P < 0.05). Compared with IF, TOUAF-175 ultrasonic treatment effectively inhibited the increase in TBA values ​​of frozen samples. TOUAF-175 ultrasonic treatment accelerated freezing by increasing the cavitation area, and the resulting fine ice crystals better maintained the structural integrity of the cells. Furthermore, TOUAF-175 ultrasonic treatment reduced the activities of lipase, phospholipase, and lipoxygenase through rapid freezing, effectively slowing lipid oxidation in fish. These results indicate that TOUAF-175 ultrasonic treatment effectively reduces the effects of thermal effects on lipid oxidation and significantly reduces TBA values.

[0088] Example 7

[0089] The method for freezing large yellow croaker based on triple-frequency orthogonal ultrasound-assisted technology specifically comprises the following steps:

[0090] Step S1: slaughtering fresh large yellow croaker by knocking the head, removing the gills and internal organs, then rinsing and placing in polyethylene bags for vacuum packaging;

[0091] Step S2, cooling by three-frequency orthogonal (horizontal 20, 28 kHz + vertical 40 kHz) ultrasonic assisted freezing (TOUAF) with an ultrasonic power of 175 W;

[0092] Step S3: Observe the temperature change by using a T-type thermocouple. When the temperature drops to -18°C, take out the large yellow croaker and store it in a refrigerator at -18°C for 5 days.

[0093] Step S4. The experiment was divided into five groups, namely, an ultrasonic assisted freezing treatment group (TOUAF-160) with an ultrasonic power of 160W and three orthogonal frequencies (horizontally 20, 28kHz + vertically 40kHz), an ultrasonic assisted freezing treatment group (TOUAF-175) with an ultrasonic power of 175W, an ultrasonic assisted freezing treatment group (TOUAF-190) with an ultrasonic power of 190W, an ultrasonic assisted freezing treatment group (TOUAF-205) with an ultrasonic power of 205W, and a group without ultrasonic treatment (immersion freezing IF) as the control group.

[0094] Other parameters were as follows: large yellow croaker was approximately 35 ± 5.0 cm long and weighed approximately 500 ± 20 g. A calcium chloride solution with a mass concentration of 298 g / L was used as the refrigerant and maintained at −25.0°C. The ultrasonic device was set to an alternating mode of 30 seconds on and 30 seconds off to minimize the negative effects of thermal effects during the freezing process.

[0095] During the freezing and storage of fish, MP denaturation and aggregation of insoluble high molecular weight MP are prone to occur. Aggregates are difficult to dissolve, resulting in decreased MP solubility. Therefore, protein solubility can reflect the degree of oxidative denaturation of muscle protein. Figure 6, the protein solubility after TOUAF-175 ultrasonic treatment was the highest (60.33%). The results showed that TOUAF-175 significantly improved the protein solubility of frozen large yellow croaker (p<0.05). This is due to the influence of the cavitation effect during the freezing process, which broke the physical force that controls the intermolecular cross-linking of protein aggregates, hindered the aggregation of protein macromolecules, and increased the solubility of protein. TOUAF expands the cavitation area and promotes cavitation through orthogonal mode, which has a positive effect on the proteolysis of frozen samples. TOUAF-175 ultrasonic treatment uses an appropriate frequency to expand the cavitation area and increase the cavitation rate, while avoiding mechanical damage to the muscle caused by excessive ultrasound. The faster freezing rate forms fine ice crystals between the muscle fibers, effectively slowing down the aggregation of protein and improving the protein solubility of large yellow croaker samples.

[0096] Example 8

[0097] The method for freezing large yellow croaker based on triple-frequency orthogonal ultrasound-assisted technology specifically comprises the following steps:

[0098] Step S1: slaughtering fresh large yellow croaker by knocking the head, removing the gills and internal organs, then rinsing and placing in polyethylene bags for vacuum packaging;

[0099] Step S2, cooling by three-frequency orthogonal (horizontal 20, 28 kHz + vertical 40 kHz) ultrasonic assisted freezing (TOUAF) with an ultrasonic power of 175 W;

[0100] Step S3, observing the temperature change by using a T-type thermocouple, taking out the large yellow croaker when the temperature drops to -18°C, and storing it in a refrigerator at -18°C for 5 days;

[0101] Step S4. The experiment was divided into five groups, namely, an ultrasonic assisted freezing treatment group (TOUAF-160) with an ultrasonic power of 160W and three orthogonal frequencies (horizontally 20, 28kHz + vertically 40kHz), an ultrasonic assisted freezing treatment group (TOUAF-175) with an ultrasonic power of 175W, an ultrasonic assisted freezing treatment group (TOUAF-190) with an ultrasonic power of 190W, an ultrasonic assisted freezing treatment group (TOUAF-205) with an ultrasonic power of 205W, and a group without ultrasonic treatment (immersion freezing IF) as the control group.

[0102] Changes in the protein surface can be reflected by surface hydrophobicity. Changes in the protein molecular structure change the surface structure, exposing additional hydrophobic residues, leading to an increase in surface hydrophobicity. After freezing treatment, the surface hydrophobicity of each group of large yellow croaker increased to varying degrees ( Figure 7This is due to oxidative denaturation of the protein, which alters its internal structure and promotes protein unfolding, exposing hydrophobic groups. The relatively low surface hydrophobicity of TOUAF treatment is due to orthogonal ultrasound amplifying the cavitation region, reducing the degree of protein unfolding, making its conformation more stable, and reducing the exposure of hydrophobic amino acid residues during MP unfolding. The TOUAF-175 ultrasound treatment had the lowest surface hydrophobicity, due to the appropriate combination of orthogonal ultrasound frequencies, which reduced damage to muscle cells during rapid freezing and reduced mechanical damage to the muscle during freezing.

[0103] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A three-frequency orthogonal ultrasonic assisted freezing method, characterized in that: The specific steps include: Step S1: slaughtering fresh large yellow croaker by knocking the head, removing the gills and internal organs, then rinsing and placing in polyethylene bags for vacuum packaging; Step S2, performing freezing treatment and cooling by using triple-frequency orthogonal ultrasound assisted freezing with an ultrasonic power of 175W; Step S3: Observe the temperature change by using a T-type thermocouple. When the temperature drops to -18°C, take out the large yellow croaker and store it in a refrigerator at -18°C for 5 days.

2. The three-frequency orthogonal ultrasound assisted freezing method according to claim 1, characterized in that: The body length of large yellow croaker is about 35±5.0cm.

3. The three-frequency orthogonal ultrasound assisted freezing method according to claim 1, characterized in that: The body mass is approximately 500g±20g.

4. The three-frequency orthogonal ultrasound assisted freezing method according to claim 1, characterized in that: A calcium chloride solution with a mass concentration of 298 g / L was used as the refrigerant and the temperature was maintained at -25.0°C.

5. The three-frequency orthogonal ultrasound assisted freezing method according to claim 1, characterized in that: The ultrasonic device was set to an alternating mode of 30 s on and 30 s off to minimize the negative impact of thermal effects during the freezing process.

6. Application of the above three-frequency orthogonal ultrasonic assisted freezing method in fish freezing.

7. A method for freezing large yellow croaker based on triple-frequency orthogonal ultrasound-assisted technology, characterized in that: The specific steps include: Step S1: slaughtering fresh large yellow croaker by knocking the head, removing the gills and internal organs, then rinsing and placing in polyethylene bags for vacuum packaging; Step S2, performing freezing treatment and cooling by using triple-frequency orthogonal ultrasound assisted freezing with an ultrasonic power of 175W; Step S3, observing the temperature change by using a T-type thermocouple, taking out the large yellow croaker when the temperature drops to -18°C, and storing it in a refrigerator at -18°C for 5 days; Step S4, the experiment was divided into five groups, namely, a three-frequency orthogonal ultrasonic assisted freezing treatment group with an ultrasonic power of 160W, an ultrasonic assisted freezing treatment group with an ultrasonic power of 175W, an ultrasonic assisted freezing treatment group with an ultrasonic power of 190W, an ultrasonic assisted freezing treatment group with an ultrasonic power of 205W, and a group without ultrasonic treatment as a control group.

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