Preparation method of liquid edible salmon fish oil and salmon fish oil

Abstract

This invention discloses a method for preparing liquid edible salmon oil and the salmon oil itself, comprising the following steps: using chilled salmon belly as raw material, the chilled salmon belly is washed, drained, and minced into a paste; the fish paste is evenly placed in a jacketed kettle, heated, and the temperature inside the kettle is raised to 180-200℃ and maintained for 30-40 minutes; after maintaining the temperature at 180-200℃, the temperature inside the jacketed kettle is cooled to 130-140℃, and 3-5% of the mass of the fish paste is added. High-temperature resistant, oleophobic porous microspheres are used to form a uniformly distributed oxygen barrier layer on the top surface of the oil layer. The mixture is then maintained at 130-140℃ for 2-3 hours, with stirring every 30-35 minutes during this period. After maintaining at 130-140℃ for 2-3 hours, the temperature is lowered to 55-60℃ and stirred continuously at 55-60℃ for 10-15 minutes. The mixture is then filtered, cooled, and allowed to stand. The supernatant is collected to obtain orange-red salmon oil. This application obtains low-fishy salmon edible oil through a heating refining process without other complex treatment methods.

Description

Technical Field

[0001] This invention belongs to the field of fish oil processing, and relates to a method for preparing liquid edible salmon oil and the salmon oil itself. Background Technology

[0002] Currently, fish oil extracted from deep-sea fish such as salmon is generally processed through complex purification processes to produce health-promoting fish oil rich in EPA and DHA. This is because existing methods for refining salmon edible oil using simple refining techniques have been found to produce a fishy smell without any additives or complex purification processes. However, health-promoting fish oil rich in EPA and DHA, while containing relatively low levels of other components, can only be used as a supplement. It is not heat-resistant, lacks broad-spectrum susceptibility, and is unsuitable for use as cooking oil.

[0003] The fishy smell of salmon oil mainly comes from two sources: 1. trimethylamine produced, and 2. the oxidation reaction of unsaturated fatty acids with oxygen in the air, which produces an unpleasant odor. The refining process of salmon oil requires an open environment, which causes the unsaturated fatty acids produced during the refining process to undergo a significant oxidation reaction, producing a distinct odor. Therefore, it is impossible to obtain salmon edible oil with a low fishy smell through a simple refining process. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing liquid edible salmon oil and salmon oil, which solves the problem that low-fishy edible salmon oil cannot be obtained through simple oil refining processes.

[0005] The technical solution adopted in this invention is as follows:

[0006] A method for preparing liquid edible salmon oil includes the following steps:

[0007] S1. Using fresh salmon belly as raw material, clean and drain the fresh salmon belly, and mince it into a paste for later use.

[0008] S2. Refining the fish paste after step S1 into oil, including the following specific steps:

[0009] S2.1 Place the fish paste evenly in a jacketed kettle, heat it, and keep the temperature inside the kettle at 180-200℃ for 30-40 minutes;

[0010] S2.2 After maintaining the temperature at 180-200℃ for 30-40 minutes, the temperature inside the jacketed kettle is lowered to 130-140℃. 3-5% of the fish paste mass of high-temperature resistant oleophobic porous microspheres are added. The density of the high-temperature resistant oleophobic porous microspheres is less than that of salmon oil. The high-temperature resistant oleophobic porous microspheres form a uniformly distributed oxygen barrier layer on the top surface of the oil layer. Then, the temperature is maintained at 130-140℃ for 2-3 hours. During this period, the mixture is stirred every 30-35 minutes for 2-3 minutes each time. The end of each stirring is used as the starting point for calculating the next stirring interval.

[0011] S2.3 After maintaining the temperature at 130-140℃ for 2-3 hours, cool the temperature to 55-60℃ and stir continuously at 55-60℃ for 10-15 minutes. Then filter, cool, let stand, and take the supernatant to obtain orange-red salmon oil.

[0012] Furthermore, the high-temperature resistant oleophobic porous microspheres comprise the following components: 100 parts of ethylene-vinyl alcohol copolymer-modified porous low-density sintered microspheres, 22-25 parts of chitosan-modified acidic clay, and 1-2 parts of calcium chloride. The high-temperature resistant oleophobic porous microspheres of this application can withstand 130-140℃ and remain stable at this temperature.

[0013] Furthermore, the salmon oil contains a higher content of monounsaturated fatty acids than polyunsaturated fatty acids, and the total unsaturated fatty acid content is >84%.

[0014] Further, step S1 includes the following specific steps: using fresh salmon belly as raw material, after cleaning the fresh salmon belly, soak it in milk for 20-30 minutes, then clean and drain it, and mince it into a paste for later use.

[0015] Furthermore, the ethylene-vinyl alcohol copolymer-modified porous low-density sintered microspheres are prepared by the following method:

[0016] A. Treat coconut shell fiber with 3% (w / w) cellulase solution for 2 hours, filter, and obtain enzyme-treated coconut shell fiber.

[0017] B. Enzyme-treated coconut shell fiber and hollow glass microspheres are mixed at a mass ratio of 1:1.5. After mixing evenly, the mixture is calcined at 500-550℃ for 2-2.5 hours to obtain porous low-density sintered microspheres.

[0018] C. Porous low-density sintered microspheres are immersed in a 10wt% ethylene-vinyl alcohol copolymer solution for 12-14 hours, filtered, and dried to obtain ethylene-vinyl alcohol copolymer modified porous low-density sintered microspheres; wherein the ratio of porous low-density sintered microspheres to ethylene-vinyl alcohol copolymer solution is 1:12 g / mL.

[0019] Further, the chitosan-modified acidic clay is prepared by the following method: acidic clay is dispersed in deionized water to obtain a clay dispersion; chitosan is dissolved in a 2wt% dilute acetic acid solution to obtain a chitosan solution; the clay dispersion and the chitosan solution are mixed and stirred evenly, and then reacted at 70°C for 3 hours. After the reaction is completed, the mixture is filtered and dried to obtain chitosan-modified acidic clay; wherein the mass ratio of chitosan to acidic clay is 1:10.

[0020] Furthermore, the preparation method of the high-temperature resistant oleophobic porous microspheres includes the following steps: dispersing chitosan-modified acidic clay in anhydrous ethanol until uniform dispersion is obtained; adding ethylene-vinyl alcohol copolymer-modified porous low-density sintered microspheres and calcium chloride to the suspension, stirring at 50°C for 1-1.5 hours, filtering, and drying to obtain high-temperature resistant oleophobic porous microspheres.

[0021] Furthermore, the ethylene-vinyl alcohol copolymer contains 35% ethylene units and 65% vinyl alcohol units in molar content.

[0022] The salmon oil prepared by the above method contains >50% monounsaturated fatty acids, >84% total unsaturated fatty acids, and ≥70 mg / kg calcium. Among these, cis-9-octadecenoic acid >40%, cis-4,7,10,13,16,19-docosahexaenoic acid ≥5%, and cis-5,8,11,14,17-eicosapentaenoic acid ≥3%, and the combined content of cis-4,7,10,13,16,19-docosahexaenoic acid and cis-5,8,11,14,17-eicosapentaenoic acid is <10%.

[0023] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0024] 1. This invention discloses a method for preparing liquid edible salmon oil based on a simple heating refining technique. By controlling the refining temperature to below 200℃, primarily concentrated between 130-140℃, the influence of temperature on salmon can be reduced. High temperatures accelerate the oxidation of unsaturated fatty acids and other substances, making the fish oil smell fishy; however, excessively low temperatures will affect the oil yield. Therefore, this application utilizes three temperature control segments of 180-200℃, 130-140℃, and 55-60℃. While ensuring a high oil yield, it can be combined with high-temperature resistant oleophobic porous microspheres to reduce the fishy smell of the fish oil. No other deodorization operations are required after refining. This is equivalent to obtaining low-fishy salmon edible oil through a one-step refining method, and the refined fish oil can be used as cooking oil.

[0025] 2. The high-temperature oleophobic porous microspheres of this invention do not produce additional substances during the oil refining process, thus not affecting the quality of the fish oil. The density of the high-temperature oleophobic porous microspheres is lower than that of the fish oil. During the oil refining process, an oxygen barrier layer with an oxygen barrier effect is formed on the top surface. Compared with the existing completely open environment, while avoiding the formation of water droplets from water vapor condensation, the contact area and amount of unsaturated fatty acids in the fish oil with oxygen are reduced, thereby effectively reducing the oxidation degree of unsaturated fatty acids. As the protection degree of unsaturated fatty acids decreases, the fishy smell will be significantly reduced, achieving the deodorization effect during the preparation process.

[0026] 3. The high-temperature oleophobic porous microspheres of this invention use ethylene-vinyl alcohol copolymer-modified porous low-density sintered microspheres as a carrier to achieve a lightweight oxygen barrier effect. Combined with chitosan-modified acidic clay, they have an adsorption and deodorization function. Calcium chloride enables the ethylene-vinyl alcohol copolymer-modified porous low-density sintered microspheres to bond firmly with the chitosan-modified acidic clay, forming a stable oxygen barrier and deodorization layer, thus preventing structural damage during use and ensuring effective oxygen barrier and deodorization.

[0027] 4. In this invention, the high-temperature oleophobic porous microspheres utilize the calcination of coconut shell fibers to form a porous structure on the surface of hollow glass microspheres, providing space for the filling of chitosan-modified acidic clay, thus forming porous, low-density sintered microspheres; the ethylene-vinyl alcohol copolymer has excellent oxygen barrier properties, and multiple microspheres fill each other to form an oxygen barrier layer; the ethylene-vinyl alcohol copolymer and chitosan have certain oleophobic properties, ensuring that the high-temperature oleophobic porous microspheres do not indiscriminately adsorb oils, thereby reducing the amount of fish oil extracted. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort, wherein:

[0029] Figure 1 This is a photograph of the fish oil prepared in Example 2 of the present invention;

[0030] Figure 2 This is a diagram illustrating the raw material processing of this invention;

[0031] Figure 3 , Figure 4 , Figure 5 This is the test report of the fish oil prepared in Example 2 of this invention;

[0032] Figure 6 This is an electron microscope image of the high-temperature resistant oleophobic porous microspheres prepared in Example 2 of the present invention. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described embodiments are merely some embodiments of the invention, and not all embodiments. The components of the embodiments of the invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0034] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0035] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0036] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0037] This invention discloses a method for preparing liquid edible salmon oil, comprising the following steps:

[0038] S1. Using fresh salmon belly as raw material, clean and drain the fresh salmon belly, and mince it into a paste for later use.

[0039] S2. Refining the fish paste after step S1 into oil, including the following specific steps:

[0040] S2.1 Place the fish paste evenly in a jacketed kettle, heat it, and keep the temperature inside the kettle at 180-200℃ for 30-40 minutes;

[0041] S2.2 After maintaining the temperature at 180-200℃ for 30-40 minutes, the temperature inside the jacketed kettle is lowered to 130-140℃. 3-5% of the fish paste mass of high-temperature resistant oleophobic porous microspheres are added. The density of the high-temperature resistant oleophobic porous microspheres is less than that of salmon oil. The high-temperature resistant oleophobic porous microspheres form a uniformly distributed oxygen barrier layer on the top surface of the oil layer. Then, the temperature is maintained at 130-140℃ for 2-3 hours. During this period, the mixture is stirred every 30-35 minutes for 2-3 minutes each time. The end of each stirring is used as the starting point for calculating the next stirring interval.

[0042] S2.3 After maintaining the temperature at 130-140℃ for 2-3 hours, cool the temperature to 55-60℃ and stir continuously at 55-60℃ for 10-15 minutes. Then filter, cool, let stand, and take the supernatant to obtain orange-red salmon oil.

[0043] In the following embodiments, the high-temperature resistant oleophobic porous microspheres comprise the following components: 100 parts of ethylene-vinyl alcohol copolymer modified porous low-density sintered microspheres, 22-25 parts of chitosan modified acid clay, and 1-2 parts of calcium chloride.

[0044] In the following embodiments, the content of monounsaturated fatty acids in the salmon oil is higher than the content of polyunsaturated fatty acids, and the content of total unsaturated fatty acids is >84%.

[0045] In the following embodiments, step S1 includes the following specific steps: using fresh salmon belly as raw material, the fresh salmon belly is cleaned and soaked in milk for 20-30 minutes, then cleaned and drained, and minced into a paste for later use.

[0046] In the following embodiments, the ethylene-vinyl alcohol copolymer modified porous low-density sintered microspheres were prepared by the following method:

[0047] A. Treat coconut shell fiber with 3% (w / w) cellulase solution for 2 hours, filter, and obtain enzyme-treated coconut shell fiber.

[0048] B. Enzyme-treated coconut shell fiber and hollow glass microspheres were mixed at a mass ratio of 1:1.5. After being mixed evenly, the mixture was calcined at 550℃ for 2 hours to obtain porous low-density sintered microspheres.

[0049] C. Porous low-density sintered microspheres were immersed in a 10 wt% ethylene-vinyl alcohol copolymer solution for 14 hours, filtered, and dried to obtain ethylene-vinyl alcohol copolymer modified porous low-density sintered microspheres; wherein the ratio of porous low-density sintered microspheres to ethylene-vinyl alcohol copolymer solution was 1:12 g / mL.

[0050] In the following embodiments, the chitosan-modified acidic clay was prepared by the following method: acidic clay was dispersed in deionized water to obtain a clay dispersion; chitosan was dissolved in a 2wt% dilute acetic acid solution to obtain a chitosan solution; the clay dispersion and the chitosan solution were mixed and stirred evenly, and then reacted at 70°C for 3 hours. After the reaction was completed, the mixture was filtered and dried to obtain chitosan-modified acidic clay; wherein the mass ratio of chitosan to acidic clay was 1:10.

[0051] In the following embodiments, the preparation method of the high-temperature resistant oleophobic porous microspheres includes the following steps: dispersing chitosan-modified acidic clay in anhydrous ethanol until uniform dispersion is obtained to form a suspension; adding ethylene-vinyl alcohol copolymer-modified porous low-density sintered microspheres and calcium chloride to the suspension, stirring at 50°C for 1-1.5 hours, filtering, and drying to obtain high-temperature resistant oleophobic porous microspheres.

[0052] In the following embodiments, the ethylene-vinyl alcohol copolymer has a molar content of 35% for ethylene units and a molar content of 65% for vinyl alcohol units.

[0053] The salmon oil prepared by the above method contains >50% monounsaturated fatty acids, >84% total unsaturated fatty acids, and ≥70 mg / kg calcium. Among these, cis-9-octadecenoic acid >40%, cis-4,7,10,13,16,19-docosahexaenoic acid ≥5%, and cis-5,8,11,14,17-eicosapentaenoic acid ≥3%, and the sum of the contents of cis-4,7,10,13,16,19-docosahexaenoic acid and cis-5,8,11,14,17-eicosapentaenoic acid is <10%.

[0054] Example 1:

[0055] This embodiment provides a method for preparing liquid edible salmon oil, comprising the following steps:

[0056] S1. Using 2.5kg of chilled salmon belly (after thawing) as raw material, wash the chilled salmon belly and soak it in milk for 25 minutes, then wash and drain it, and mince it into a paste for later use.

[0057] S2. Refining the fish paste after step S1 into oil, including the following specific steps:

[0058] S2.1 Place the fish paste evenly in a jacketed kettle, heat it, raise the temperature inside the kettle to 190℃ and maintain it for 35 minutes;

[0059] S2.2 After maintaining the temperature at 190℃ for 35 minutes, the temperature inside the jacketed kettle is reduced to 140℃. 4% of the fish paste mass of high-temperature resistant oleophobic porous microspheres are added. The density of the high-temperature resistant oleophobic porous microspheres is less than that of salmon oil. The high-temperature resistant oleophobic porous microspheres form a uniformly distributed oxygen barrier layer on the top surface of the oil layer. Then, the temperature is maintained at 140℃ for 3 hours. During the maintenance period, the mixture is stirred every 30 minutes for 3 minutes each time. The time when the stirring ends is used as the starting time for calculating the next stirring interval.

[0060] S2.3 After maintaining the temperature at 140℃ for 3 hours, the temperature is lowered to 60℃ and stirred continuously at 60℃ for 15 minutes. Then, the mixture is filtered, cooled, and allowed to stand. The supernatant is then collected to obtain orange-red salmon oil.

[0061] The high-temperature resistant oleophobic porous microspheres comprise the following components: 100 parts of ethylene-vinyl alcohol copolymer-modified porous low-density sintered microspheres, 22 parts of chitosan-modified acidic clay, and 1 part of calcium chloride; and are prepared by the following method: the preparation method of the high-temperature resistant oleophobic porous microspheres includes the following steps: dispersing chitosan-modified acidic clay in anhydrous ethanol until uniformly dispersed to obtain a suspension; adding ethylene-vinyl alcohol copolymer-modified porous low-density sintered microspheres and calcium chloride to the suspension, stirring at 50°C for 1.5 hours, filtering, and drying to obtain high-temperature resistant oleophobic porous microspheres; the high-temperature resistant oleophobic porous microspheres have a temperature tolerance greater than 140°C. This application incorporates high-temperature resistant, oleophobic porous microspheres of fish paste quality, comprising microspheres with particle sizes of 400-500 μm, 150-200 μm, and 30-50 μm, wherein the mass ratio of the 400-500 μm, 150-200 μm, and 30-50 μm microspheres is 3:2:2 (this ratio is used in all the following examples); in the oil refining process, if microspheres of a single particle size range are used, it is difficult to form a uniform oxygen barrier layer visible to the naked eye; the particle size of the chitosan-modified acidic clay (the clay used is nano-sized clay) is within the pore size coverage range of the ethylene-vinyl alcohol copolymer-modified porous low-density sintered microspheres.

[0062] Example 2:

[0063] This embodiment differs from Embodiment 1 in that the high-temperature resistant oleophobic porous microspheres in this embodiment comprise the following components: 100 parts of ethylene-vinyl alcohol copolymer-modified porous low-density sintered microspheres, 23.5 parts of chitosan-modified acidic clay, and 1.5 parts of calcium chloride; the high-temperature resistant oleophobic porous microspheres have a temperature tolerance greater than 140℃; all other components are the same. A photograph of the fish oil prepared in this embodiment is shown below. Figure 1 As shown in the diagram, the raw material processing procedure is as follows: Figure 2 As shown, the test report of the product prepared in this embodiment is as follows: Figure 3 , Figure 4, Figure 5 As shown; the electron micrograph of the high-temperature resistant oleophobic porous microspheres prepared in this embodiment is shown in the figure. Figure 6 As shown.

[0064] Example 3:

[0065] This embodiment differs from Embodiment 1 in that the high-temperature resistant oleophobic porous microspheres in this embodiment include the following components: 100 parts of ethylene-vinyl alcohol copolymer modified porous low-density sintered microspheres, 25 parts of chitosan modified acid clay, and 2 parts of calcium chloride; the high-temperature resistant oleophobic porous microspheres have a tolerance temperature greater than 140℃; all other components are the same.

[0066] Example 4:

[0067] This embodiment provides a method for preparing liquid edible salmon oil, comprising the following steps:

[0068] S1. Using 2.5kg of chilled salmon belly (after thawing) as raw material, wash the chilled salmon belly and soak it in milk for 25 minutes, then wash and drain it, and mince it into a paste for later use.

[0069] S2. Refining the fish paste after step S1 into oil, including the following specific steps:

[0070] S2.1 Place the fish paste evenly in a jacketed kettle, heat it, raise the temperature inside the kettle to 180℃ and maintain it for 40 minutes;

[0071] S2.2 After maintaining the temperature at 180℃ for 40 minutes, the temperature inside the jacketed kettle is reduced to 130℃. 4% of the fish paste mass of high-temperature resistant oleophobic porous microspheres are added. The density of the high-temperature resistant oleophobic porous microspheres is less than that of salmon oil. The high-temperature resistant oleophobic porous microspheres form a uniformly distributed oxygen barrier layer on the top surface of the oil layer. Then, the temperature is maintained at 130℃ for 3 hours. During the maintenance period, the mixture is stirred every 35 minutes for 3 minutes each time. The time when the stirring ends is used as the starting time for calculating the next stirring interval.

[0072] S2.3 After maintaining the temperature at 130℃ for 3 hours, the temperature is lowered to 60℃ and stirred continuously at 60℃ for 15 minutes. Then, the mixture is filtered, cooled, and allowed to stand. The supernatant is then collected to obtain orange-red salmon oil.

[0073] The high-temperature resistant oleophobic porous microspheres comprise the following components: 100 parts of ethylene-vinyl alcohol copolymer-modified porous low-density sintered microspheres, 23.5 parts of chitosan-modified acidic clay, and 1.5 parts of calcium chloride, and are prepared by the following method: The preparation method of the high-temperature resistant oleophobic porous microspheres includes the following steps: dispersing chitosan-modified acidic clay in anhydrous ethanol until uniformly dispersed to obtain a suspension; adding ethylene-vinyl alcohol copolymer-modified porous low-density sintered microspheres and calcium chloride to the suspension, stirring at 50°C for 1.5 hours, filtering, and drying to obtain high-temperature resistant oleophobic porous microspheres; the high-temperature resistant oleophobic porous microspheres have a temperature tolerance greater than 140°C.

[0074] Example 5:

[0075] This embodiment provides a method for preparing liquid edible salmon oil, comprising the following steps:

[0076] S1. Using 2.5kg of chilled salmon belly (after thawing) as raw material, wash the chilled salmon belly and soak it in milk for 30 minutes, then wash and drain it, and mince it into a paste for later use.

[0077] S2. Refining the fish paste after step S1 into oil, including the following specific steps:

[0078] S2.1 Place the fish paste evenly in a jacketed kettle, heat it, raise the temperature inside the kettle to 200℃ and maintain it for 30 minutes;

[0079] S2.2 After maintaining the temperature at 200℃ for 30 minutes, the temperature inside the jacketed kettle is reduced to 140℃. 4% of the fish paste mass of high-temperature resistant oleophobic porous microspheres are added. The density of the high-temperature resistant oleophobic porous microspheres is less than that of salmon oil. The high-temperature resistant oleophobic porous microspheres form a uniformly distributed oxygen barrier layer on the top surface of the oil layer. Then, the temperature is maintained at 140℃ for 2 hours. During the maintenance period, the mixture is stirred every 30 minutes for 3 minutes each time. The time when the stirring ends is used as the starting time for calculating the next stirring interval.

[0080] S2.3 After maintaining the temperature at 140℃ for 2 hours, the temperature is lowered to 55℃ and stirred continuously at 55℃ for 10 minutes. Then, the mixture is filtered, cooled, and allowed to stand. The supernatant is then collected to obtain orange-red salmon oil.

[0081] The high-temperature resistant oleophobic porous microspheres comprise the following components: 100 parts of ethylene-vinyl alcohol copolymer-modified porous low-density sintered microspheres, 23.5 parts of chitosan-modified acidic clay, and 1.5 parts of calcium chloride, and are prepared by the following method: The preparation method of the high-temperature resistant oleophobic porous microspheres includes the following steps: dispersing chitosan-modified acidic clay in anhydrous ethanol until uniformly dispersed to obtain a suspension; adding ethylene-vinyl alcohol copolymer-modified porous low-density sintered microspheres and calcium chloride to the suspension, stirring at 50°C for 1.5 hours, filtering, and drying to obtain high-temperature resistant oleophobic porous microspheres; the high-temperature resistant oleophobic porous microspheres have a temperature tolerance greater than 140°C.

[0082] Example 6:

[0083] Based on Example 2, the difference is that in this example, the amount of high-temperature resistant oleophobic porous microspheres added is 3% of the mass of the fish paste. All other aspects are the same.

[0084] Example 7:

[0085] Based on Example 2, the difference is that in this example, the amount of high-temperature resistant oleophobic porous microspheres added is 5% of the mass of the fish paste. All other aspects are the same.

[0086] Comparative Example 1

[0087] The comparative example provides a method for preparing liquid edible salmon oil, which includes the following steps:

[0088] S1. Using 2.5kg of chilled salmon belly (after thawing) as raw material, wash the chilled salmon belly and soak it in milk for 25 minutes, then wash and drain it, and mince it into a paste for later use.

[0089] S2. Refining the fish paste after step S1 into oil includes the following specific steps: evenly placing the fish paste in a jacketed kettle, heating it, raising the temperature inside the kettle to 190℃ and maintaining it for 3 hours; then filtering, cooling, letting it stand, and taking the supernatant to obtain orange-red salmon oil.

[0090] Comparative Example 2

[0091] The comparative example provides a method for preparing liquid edible salmon oil, which includes the following steps:

[0092] S1. Using 2.5kg of chilled salmon belly (after thawing) as raw material, wash the chilled salmon belly and soak it in milk for 25 minutes, then wash and drain it, and mince it into a paste for later use.

[0093] S2. Refining the fish paste after step S1 into oil, including the following specific steps:

[0094] S2.1 Place the fish paste evenly in a jacketed kettle, heat it, raise the temperature inside the kettle to 190℃ and maintain it for 35 minutes;

[0095] S2.2 After maintaining the temperature at 190℃ for 35 minutes, the temperature inside the jacketed kettle is reduced to 140℃, and then maintained at 140℃ for 3 hours;

[0096] S2.3 After maintaining the temperature at 140℃ for 3 hours, the temperature is lowered to 60℃ and stirred continuously at 60℃ for 15 minutes. Then, the mixture is filtered, cooled, and allowed to stand. The supernatant is then collected to obtain orange-red salmon oil.

[0097] Comparative Example 3

[0098] Based on Example 2, the difference from Example 2 is that the high-temperature resistant oleophobic porous microspheres in this comparative example do not include chitosan-modified acid clay, and the preparation method has been adapted, while the rest are the same.

[0099] Comparative Example 4

[0100] Based on Example 2, the difference from Example 2 is that the acidic clay in the high-temperature resistant oleophobic porous microspheres of this comparative example is not modified with chitosan, and the preparation method is adapted, while the rest are the same.

[0101] Comparative Example 5

[0102] Based on Example 2, the difference from Example 2 is that the high-temperature resistant oleophobic porous microspheres in this comparative example do not contain calcium chloride, and the preparation method has been adapted, while the rest are the same.

[0103] Comparative Example 6

[0104] Based on Example 2, the difference from Example 2 is that the porous low-density sintered microspheres in this comparative example of high-temperature resistant oleophobic porous microspheres are not modified with ethylene-vinyl alcohol copolymer, and the preparation method is adapted, while the rest are the same.

[0105] Experimental Example 1

[0106] The appearance, odor, anisidine value, peroxide value, content of monounsaturated fatty acids, content of polyunsaturated fatty acids, and content of cis-4,7,10,13,16,19-docosahexaenoic acid (DHA) and cis-5,8,11,14,17-eicosapentaenoic acid (EPA) of the fish oils prepared in Examples 1-7 and Comparative Examples 1-6 were tested. The detection methods for the above fatty acid contents were in accordance with GB5009.168-2016, Method III. The detection methods for appearance, odor, anisidine value, and peroxide value (meq / kg) were in accordance with the People's Republic of China Aquatic Industry Standard SC / T 3502-2016. The results are shown in Table 1.

[0107] Table 1. Fish oil performance testing

[0108] Appearance odor Anisamine value Peroxide value Monounsaturated fatty acid content Polyunsaturated fatty acid content EPA+DHA Example 1 Orange-red, clear and transparent, without sediment. It has a slight fishy smell characteristic of fish oil, but no rancid smell. ＜20 ＜5 50.3-50.8% 34-34.5% ＞8% Example 2 Orange-red, clear and transparent, without sediment. It has a slight fishy smell characteristic of fish oil, but no rancid smell. ＜15 ＜4 51-52% 33.2-33.5% ＞8% Example 3 Orange-red, clear and transparent, without sediment. It has a slight fishy smell characteristic of fish oil, but no rancid smell. ＜20 ＜5 51-51.5% 33.6-33.9% ＞8% Example 4 Orange-red, clear and transparent, without sediment. It has a slight fishy smell characteristic of fish oil, but no rancid smell. ＜20 ＜5 50.1-50.3% 34-34.3% ＞8% Example 5 Orange-red, clear and transparent, without sediment. It has a slight fishy smell characteristic of fish oil, but no rancid smell. ＜20 ＜5 50.5-51% 33.7-34% ＞8% Example 6 Orange-red, clear and transparent, without sediment. It has a slight fishy smell characteristic of fish oil, but no rancid smell. ≤20 ＜4 52.2-52.5% 32-32.2% ≥8% Example 7 Orange-red, clear and transparent, without sediment. It has a slight fishy smell characteristic of fish oil, but no rancid smell. ＜20 ＜5 51-52% 33-33.3% ＞8% Comparative Example 1 Brownish-red, slightly cloudy, with sediment. It has a distinct rancid fish oil smell. ＞20 ＞5 35-35.5% 21-21.2% ＜5% Comparative Example 2 Orange-red, slightly cloudy, no sediment It has a distinct rancid fish oil smell. ＞20 ＞5 44.3-45.1% 25.7-25.9% ＜7% Comparative Example 3 Orange-red, slightly cloudy, with sediment. It has a distinct fishy smell characteristic of fish oil, and a slight rancid smell. ＞20 ≥5 49-50.3% 30.1-30.4% ≥8% Comparative Example 4 Orange-red, slightly cloudy, with sediment. It has a slight fishy smell characteristic of fish oil, but no rancid smell. ＜20 ＜5 49.9-50.2% 31.7-31.9% ＞8% Comparative Example 5 Orange-red, slightly cloudy, with sediment. It has a slight fishy smell characteristic of fish oil, but no rancid smell. ＜20 ＜5 50.3-50.5% 33.2-33.4% ＞8% Comparative Example 6 Orange-red, slightly cloudy, with sediment. It has a distinct rancid fish oil smell. ＞20 ≥5 47-47.6% 28.8-29% ＜8%

[0109] In this application, the amount of high-temperature resistant oleophobic porous microspheres and the temperature all affect the content of unsaturated fatty acids. A high content of polyunsaturated fatty acids can affect the stability of fish oil, while a low content can affect its nutritional value. Therefore, this application rationally adjusts the content of monounsaturated and polyunsaturated fatty acids. The fish oil prepared within the range of Example 2 in this application represents the best quality. During actual research and development, it was found that the structural stability of the high-temperature resistant oleophobic porous microspheres significantly affects the appearance characteristics of the fish oil. The fish oil should be clear, transparent, and free of sediment.

[0110] Experimental Example 2

[0111] The fish oils from Examples 1-7 were tested as follows, and the results are shown in Table 2:

[0112] The content of trans oleic acid in fish oil was determined according to the third method of standard GB 5009.168-2016;

[0113] According to the People's Republic of China Aquatic Industry Standard SC / T 3502-2016, the acid value (calculated as KOH) in fish oil was tested, in mg / g.

[0114] The contaminant content in fish oil was tested according to the National Food Safety Standard for Limits of Contaminants in Food (GB 2762).

[0115] Microbiological testing: Based on existing microbiological testing technologies, fish oil is tested to determine whether it contains pathogenic bacteria (including Salmonella, Staphylococcus aureus, etc.).

[0116] Table 2 Fish oil performance testing

[0117] trans-9-octadecenoic acid trans, trans-9,12-octadecadienoic acid acid value Lead (as Pb) mg / kg Total arsenic (as As) mg / kg Total mercury (as Hg) mg / kg Pathogenic bacteria Example 1 Not detected Not detected ＜1 ＜0.005 ND ND Not detected Example 2 Not detected Not detected ＜1 ＜0.005 ND ND Not detected Example 3 Not detected Not detected ＜1 ＜0.005 ND ND Not detected Example 4 Not detected Not detected ＜1 ＜0.005 ND ND Not detected Example 5 Not detected Not detected ＜1 ＜0.005 ND ND Not detected Example 6 Not detected Not detected ＜1 ＜0.005 ND ND Not detected Example 7 Not detected Not detected ＜1 ＜0.005 ND ND Not detected

[0118] The fish oil prepared in this application meets food safety standards, and its heavy metal content and microbial content all meet the requirements. Furthermore, other physicochemical properties of the fish oil prepared in this application comply with standard SC / T 3502-2016.

[0119] Experimental Example 3

[0120] The performance of the high-temperature resistant oleophobic porous microspheres prepared in Example 2 and Comparative Examples 3-6 was tested, and the results are shown in Table 3:

[0121] Density: The density of the high-temperature resistant oleophobic porous microspheres of this application was measured (to determine whether the microspheres floated on the surface of salmon oil (using the fish oil prepared in Example 2 as the test liquid). If they floated on the surface of the fish oil, it indicated that the density of the high-temperature resistant oleophobic porous microspheres was less than the density of the fish oil, which was approximately 0.92 g / cm³. 3 );

[0122] Oleophobicity: The high-temperature resistant oleophobic porous microspheres were prepared and pressed into flat discs using a tablet compression method. One drop of 2 μL of standard oil (hexadecane) was used as the test liquid, and the oil contact angle on the disc surface was measured at 23°C and 50% relative humidity.

[0123] Chemical stability: Accurately weigh 1.0 g of dried microspheres and place them in 20 mL of salmon oil (the fish oil prepared in Example 2). Let them stand at 140 °C for 3 hours, remove them and cool them. Filter the microspheres with a filter screen to recover them. Wash them several times with ethanol and dry them. Detect the mass loss rate of the microspheres before and after soaking. Mass loss rate = (mass of microspheres before soaking - mass of microspheres after soaking) / mass of microspheres before soaking × 100%.

[0124] Heat resistance: Take 10 mg of dried microsphere sample and place it in the sample pan of the TGA instrument. Under nitrogen atmosphere, heat from 30 °C to 140 °C at a rate of 10 °C / min. Observe the temperature at which significant mass loss (usually defined as 1% loss) begins to appear in the TGA curve.

[0125] Table 3 Performance testing of high-temperature resistant oleophobic porous microspheres

[0126] density Oil contact angle Chemical stability (mass loss rate) Heat resistance Example 2 Density less than that of fish oil ＞120° <0.1% (virtually no loss) No significant mass loss was observed at 140℃, indicating heat resistance > 140℃. Comparative Example 3 Density less than that of fish oil ＞120° <0.1% (virtually no loss) No significant mass loss was observed at 140℃, indicating heat resistance > 140℃. Comparative Example 4 Density less than that of fish oil 110-120° ＞1% No significant mass loss was observed at 140℃, indicating heat resistance > 140℃. Comparative Example 5 Density less than that of fish oil ＞120° ＞1% No significant mass loss was observed at 140℃, indicating heat resistance > 140℃. Comparative Example 6 Density less than that of fish oil 110-120° ＞1% No significant mass loss was observed at 140℃, indicating heat resistance > 140℃.

[0127] The high-temperature resistant oleophobic porous microspheres used in this application have good oleophobicity and heat resistance, and basically do not produce additional components in salmon.

[0128] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing liquid edible salmon oil, characterized in that: Includes the following steps: S1. Using fresh salmon belly as raw material, clean and drain the fresh salmon belly, and mince it into a paste for later use. S2. Refining the fish paste after step S1 into oil, including the following specific steps: S2.

1. Place the fish paste evenly in a jacketed kettle, heat it, and keep the temperature inside the kettle at 180-200℃ for 30-40 minutes. S2.2 After maintaining the temperature at 180-200℃ for 30-40 minutes, the temperature inside the jacketed kettle is lowered to 130-140℃. 3-5% of the fish paste mass of high-temperature resistant oleophobic porous microspheres are added. The density of the high-temperature resistant oleophobic porous microspheres is less than that of salmon oil. The high-temperature resistant oleophobic porous microspheres form a uniformly distributed oxygen barrier layer on the top surface of the oil layer. Then, the temperature is maintained at 130-140℃ for 2-3 hours. During this period, the mixture is stirred every 30-35 minutes for 2-3 minutes each time. The end of each stirring is used as the starting point for calculating the next stirring interval. S2.3 After maintaining the temperature at 130-140℃ for 2-3 hours, cool the temperature to 55-60℃ and stir continuously at 55-60℃ for 10-15 minutes. Then filter, cool, let stand, and take the supernatant to obtain salmon oil. The high-temperature resistant oleophobic porous microspheres comprise the following components: 100 parts of ethylene-vinyl alcohol copolymer modified porous low-density sintered microspheres, 22-25 parts of chitosan modified acid clay, and 1-2 parts of calcium chloride. The ethylene-vinyl alcohol copolymer-modified porous low-density sintered microspheres were prepared by the following method: A. Treat coconut shell fiber with 3% (w / w) cellulase solution for 2 hours, filter, and obtain enzyme-treated coconut shell fiber. B. Enzyme-treated coconut shell fiber and hollow glass microspheres are mixed at a mass ratio of 1:1.

5. After mixing evenly, the mixture is calcined at 500-550℃ for 2-2.5 hours to obtain porous low-density sintered microspheres. C. Porous low-density sintered microspheres were immersed in a 10wt% ethylene-vinyl alcohol copolymer solution for 12-14 hours, filtered, and dried to obtain ethylene-vinyl alcohol copolymer modified porous low-density sintered microspheres; wherein the ratio of porous low-density sintered microspheres to ethylene-vinyl alcohol copolymer solution was 1:12 g / mL. The preparation method of the high-temperature resistant oleophobic porous microspheres includes the following steps: dispersing chitosan-modified acidic clay in anhydrous ethanol until uniform dispersion is obtained; adding ethylene-vinyl alcohol copolymer-modified porous low-density sintered microspheres and calcium chloride to the suspension, stirring at 50°C for 1-1.5 hours, filtering, and drying to obtain high-temperature resistant oleophobic porous microspheres; High-temperature resistant oleophobic porous microspheres include microspheres with particle sizes of 400-500 μm, 150-200 μm, and 30-50 μm.

2. The method for preparing liquid edible salmon oil according to claim 1, characterized in that: The salmon oil contains more monounsaturated fatty acids than polyunsaturated fatty acids, and the total unsaturated fatty acid content is >84%.

3. The method for preparing liquid edible salmon oil according to claim 1, characterized in that: Step S1 includes the following specific steps: using fresh salmon belly as raw material, after cleaning the fresh salmon belly, soak it in milk for 20-30 minutes, then clean and drain it, and mince it into a paste for later use.

4. The method for preparing liquid edible salmon oil according to claim 1, characterized in that: The chitosan-modified acidic clay was prepared by the following method: acidic clay was dispersed in deionized water to obtain a clay dispersion; chitosan was dissolved in a 2wt% dilute acetic acid solution to obtain a chitosan solution; the clay dispersion and the chitosan solution were mixed and stirred evenly, and then reacted at 70°C for 3 hours. After the reaction was completed, the mixture was filtered and dried to obtain the chitosan-modified acidic clay; wherein the mass ratio of chitosan to acidic clay was 1:

10.

5. The method for preparing liquid edible salmon oil according to claim 1, characterized in that: The ethylene-vinyl alcohol copolymer has a molar content of 35% for ethylene units and a molar content of 65% for vinyl alcohol units.

6. Salmon oil prepared by the preparation method according to any one of claims 1-5, characterized in that: The salmon oil contains >50% monounsaturated fatty acids and >84% total unsaturated fatty acids; among which, the contents of cis-4,7,10,13,16,19-docosahexaenoic acid and cis-5,8,11,14,17-eicosapentaenoic acid are <10%.

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