Preparation method of krill oil with high phospholipid content

Abstract

The invention relates to the technical field of krill oil, in particular to a preparation method of krill oil with high phospholipid content. Raw materials adopted by the preparation method at least comprise krill, n-butyl alcohol, beta-cyclodextrin, propylene glycol and water. In the preparation method of the krill oil with high phospholipid content, krill, n-butyl alcohol, beta-cyclodextrin, propylene glycol and water are used as raw materials, and low-temperature multi-time layering operation is performed, so that the phospholipid content in the krill oil is effectively increased, the use amount of an organic solvent is remarkably reduced, the residue of the organic solvent is effectively reduced, and the safety and nutritional value of the product are increased; in addition, in the preparation process, damage to other bioactive components such as Omega-3 fatty acid and astaxanthin is small, and the nutrition and health-care effects of the krill oil are reserved; in addition, according to the method, the process is simplified, the complex treatment step of removing an organic solvent is reduced, the production efficiency is improved, and the production cost is reduced, so that the economic benefit of krill oil production is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of krill oil, and specifically, to a preparation method of krill oil with a high phospholipid content. Background Art

[0002] Krill oil is a substance with important nutritional value, rich in various bioactive components such as phospholipids, Omega-3 fatty acids (such as EPA and DHA), and astaxanthin. Among them, phospholipids play a key role in maintaining cell structure and function, promoting lipid metabolism, and protecting cardiovascular health. Omega-3 fatty acids help reduce blood lipids, prevent cardiovascular diseases, and improve brain function. Astaxanthin has strong antioxidant ability and can protect cells from oxidative damage.

[0003] Currently, although various methods for extracting krill oil have been developed in the prior art, such as the organic solvent extraction method, which can effectively extract krill oil, can also increase the phospholipid content in krill oil, is relatively simple to operate, and can obtain a high extraction rate, and has been applied in production practice. However, the existing organic solvent extraction technology still has some deficiencies. Not only is the organic solvent used prone to residual problems, which directly affect the food safety quality of krill oil and also have a certain impact on the health of consumers, but also due to chemical reactions or physical interactions between the organic solvent and other active components in krill oil, the structure of these active components is damaged and lost, reducing the original nutritional value and health care effects of krill oil. Moreover, in order to remove these residual organic solvents, additional complex treatment steps are required, which not only reduce production efficiency but also increase production costs, thereby reducing the economic benefits of krill oil production.

[0004] In view of this, there is an urgent need for a preparation method of krill oil with a high phospholipid content. Summary of the Invention

[0005] The purpose of the present invention is to provide a preparation method of krill oil with a high phospholipid content to solve the problems raised in the above background art.

[0006] To achieve the above purpose, as Figure 1 shown, the present invention provides a preparation method of krill oil with a high phospholipid content, including the raw materials used in the preparation method. The raw materials include at least 70 parts - 90 parts of krill, 110 parts - 140 parts of n-butanol (food-grade n-butanol), 8 parts - 12 parts of β-cyclodextrin, 24 parts - 36 parts of propylene glycol, and 170 parts - 200 parts of water. At the same time, the preparation method also includes the following steps: S1. First extraction: Use a food crusher to crush krill to make its particle size uniform. Then transfer the crushed krill to a stainless-steel reaction kettle with a stirring device, add n-butanol, turn on the stirring device, and stir and extract at a stirring speed of 150 r / min - 200 r / min and a temperature of 3°C - 8°C for 2.5 h - 3.5 h; S2. First layering: After the extraction is completed, turn off the stirring device, and let the mixed liquid in the reaction kettle stand at a temperature of 5°C - 0°C for 1.5 h - 2 h. During this period, due to the density and solubility differences among n-butanol, impurities, and krill oil components, a layering phenomenon will occur. The upper layer of the mixed liquid is a solution containing krill oil and n-butanol, and the lower layer is impurity precipitation. Then use a separating funnel to separate the solution containing krill oil and n-butanol in the upper layer and transfer it to a glass reaction container with a stirring device; S3. β-cyclodextrin treatment: Add β-cyclodextrin treatment to the glass reaction container, turn on the stirring device, and continuously stir at a stirring speed of 100 r / min - 150 r / min and an environment of 8°C - 13°C for 2 h - 3 h. During this process, β-cyclodextrin forms a stable inclusion complex with phospholipids. The inner part of the cyclic structure of β-cyclodextrin is a hydrophobic region, which can wrap the hydrophobic part of phospholipid molecules to form a stable inclusion system; S4. Second layering: Let the solution in the glass reaction container stand again at an environment of -5°C - 0°C for 1.5 h - 2 h to make the solution layer. The upper layer is a solution containing the inclusion complex, and the lower layer is part of the impurities and unreacted components. Then, use a separating funnel to separate the solution containing the inclusion complex in the upper layer and transfer it to a reaction kettle with a stirring device; S5. Add propylene glycol: Add propylene glycol to the reaction kettle, turn on the stirring device, and stir at a stirring speed of 120 r / min - 160 r / min and an environment of 12°C - 17°C for 2 h - 2.5 h. During this process, the hydroxyl functional group of propylene glycol interacts with the inclusion complex and other components in the system, enabling the secondary combination of the inclusion complex and other components in the system, changing the physical properties of the system, and enriching the phospholipids in krill oil; S6. Third layering and final separation: Let the solution in the reaction kettle stand at a temperature of -5°C - 0°C for 1.5 h - 2 h to make the solution layer. At this time, the layer containing krill oil (with a relatively higher phospholipid content) is in the upper layer, and the lower layer is part of the impurities and the remaining propylene glycol components. Then use a separating funnel to transfer the solution containing krill oil in the upper layer to a distillation device, and perform vacuum distillation at a pressure of 1 kPa - 5 kPa and a temperature of 30°C - 50°C to remove residual solvents and moisture, obtaining preliminarily purified krill oil; S7. Water purification: Transfer the preliminarily purified krill oil to a reaction vessel equipped with a stirring device, add water, turn on the stirring device, and stir at a stirring speed of 80 r / min - 120 r / min and a temperature of 20°C - 25°C for 30 min - 60 min. During this process, water molecules will disrupt the hydrophobic interaction and hydrogen bond between β-cyclodextrin and phospholipids, causing the phospholipids to be released from the cavity of β-cyclodextrin. After stirring, let the solution stand in a low-temperature environment of -5°C - 0°C for 30 min - 60 min. At this time, the upper layer is krill oil with a high phospholipid content, and the lower layer is an aqueous solution containing impurities such as β-cyclodextrin. Then use a separatory funnel to separate the upper-layer krill oil with a high phospholipid content, and finally obtain krill oil with a high phospholipid content.

[0007] In the present invention, firstly, β-cyclodextrin is a cyclic oligosaccharide, and its internal cavity structure is a hydrophobic region, while phospholipid molecules have a hydrophilic head and a hydrophobic long-chain hydrocarbon group. When β-cyclodextrin is mixed with phospholipids, the hydrophobic long-chain hydrocarbon group of the phospholipid molecule can enter the hydrophobic cavity of β-cyclodextrin and interact through intermolecular van der Waals forces, hydrophobic interactions, and existing hydrogen bonds to form a stable inclusion complex system, which can change the solubility and density properties of phospholipids in the solution, facilitating the further separation of phospholipids from other impurity components during the layering operation, thereby achieving the purpose of enriching phospholipids in krill oil. At the same time, due to the formation of the inclusion complex, it can effectively protect phospholipids and reduce the possible adverse reactions with other components. Secondly, the hydroxyl groups in propylene glycol molecules have polarity and activity, and can form hydrogen bond intermolecular forces with the polar groups (such as hydroxyl groups, carboxyl groups, etc.) on the surface of the inclusion complex and other components in the system. At the same time, the presence of propylene glycol changes the solvent environment of the system, affects the interactions and solubilities between various components, and improves the enrichment degree of phospholipids in krill oil. The main reason is that the hydroxyl groups of propylene glycol form hydrogen bonds with hydrogen atoms or atoms with relatively high electronegativity (such as oxygen atoms, etc.) in other molecules, thereby achieving the binding with the inclusion complex and other components. Thirdly, there will be an interaction between water and the inclusion complex formed by β-cyclodextrin and phospholipids, causing the phospholipids to be released from the inclusion complex. When water is added to the system containing the inclusion complex, water molecules will disrupt the hydrophobic interaction and some hydrogen bonds between β-cyclodextrin and phospholipids. Because water molecules are polar molecules with strong hydrophilicity, they can interact with the polar parts of β-cyclodextrin and phospholipid molecules, thereby breaking the stable binding between β-cyclodextrin and phospholipids and causing the phospholipids to be freed from the cavity of β-cyclodextrin, realizing the separation of phospholipids from β-cyclodextrin.

[0008] Compared with the prior art, the beneficial effects of the present invention are: 1. In the preparation method of the krill oil with high phospholipid content, using krill, n-butanol, β-cyclodextrin, propylene glycol and water as raw materials, through the operation of low-temperature multi-layer separation, not only effectively improves the phospholipid content in the krill oil, but also significantly reduces the usage amount of organic solvents, effectively reduces the residual amount of organic solvents, increases the safety and nutritional value of the product; moreover, during the preparation process, the destruction of other bioactive components such as Omega-3 fatty acids and astaxanthin is less, retaining the nutritional and health care effects of the krill oil; in addition, this method simplifies the process, reduces the complex treatment steps for removing organic solvents, improves the production efficiency, reduces the production cost, and thus improves the economic benefits of krill oil production.

[0009] 2. In the preparation method of the krill oil with high phospholipid content, in the application of β-cyclodextrin and propylene glycol and the step of adding water for purification, β-cyclodextrin forms an inclusion complex with phospholipids, which not only enriches the phospholipids, but also provides protection for them, reducing adverse reactions; the addition of propylene glycol further enhances the enrichment degree of phospholipids, and through changing the physical properties of the system, makes the separation of phospholipids more efficient; the step of adding water for purification utilizes the characteristics of strong polarity and high hydrophilicity of water molecules to break the hydrophobic interaction and hydrogen bond between β-cyclodextrin and phospholipids, so that the phospholipids are released from the inclusion complex, thereby improving the purity of the phospholipids. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a flow block diagram of the preparation method of the krill oil with high phospholipid content of the present invention; Figure 2 is a bar chart of the phospholipid content of the present invention; Figure 3 is a bar chart of the residual amount of organic solvents of the present invention; Figure 4 is a bar chart of the Omega-3 fatty acid content of the present invention; Figure 5 is a bar chart of the astaxanthin content of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0011] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those skilled in the art without making creative efforts belong to the scope of protection of the present invention. Embodiment

[0012] Take 70 portions of krill and crush them to a uniform particle size using a food crusher; transfer the crushed krill to a stainless-steel reaction kettle equipped with a stirring device, add 110 portions of n-butanol, turn on the stirring device, and stir and extract at a stirring speed of 150 r / min and a temperature of 3 °C for 3.5 h; after the extraction is completed, turn off the stirring device, let the mixed solution in the reaction kettle stand at a temperature of 0 °C for 2 h, and after the solution is layered, use a separating funnel to transfer the upper layer solution containing krill oil and n-butanol to a glass reaction container equipped with a stirring device; then, add 8 portions of β-cyclodextrin to the glass reaction container, turn on the stirring device, and continuously stir at a stirring speed of 100 r / min in an environment of 8 °C for 3 h; after the stirring is completed, let the solution in the glass reaction container stand again in an environment of -5 °C for 2 h, separate the upper layer solution containing the inclusion complex, and transfer it to a reaction kettle equipped with a stirring device; add 30 portions of propylene glycol to the reaction kettle, turn on the stirring device, and stir at a stirring speed of 120 r / min in an environment of 12 °C for 2.5 h; then let the solution in the reaction kettle stand at a temperature of -5 °C for 2 h, use a separating funnel to transfer the upper layer solution containing krill oil to a distillation device, and perform vacuum distillation at a pressure of 1 kPa and a temperature of 30 °C to obtain preliminarily purified krill oil; finally, transfer the preliminarily purified krill oil to a reaction container equipped with a stirring device, add 175 portions of water, turn on the stirring device, and stir at a stirring speed of 80 r / min and a temperature of 20 °C for 60 min. After the stirring is completed, let the solution stand in a low-temperature environment of -5 °C for 60 min, and use a separating funnel to separate the upper layer of krill oil with a high phospholipid content. Example

[0013] Weigh 80 portions of krill, crush them and transfer them to a stainless-steel reaction kettle, add 125 portions of n-butanol, and stir and extract at a stirring speed of 175 r / min and a temperature of 5 °C for 3 h; after the extraction is completed, let the mixed solution stand at a temperature of 2 °C for 1.75 h, and separate the upper layer solution to a glass reaction container; add 12 portions of β-cyclodextrin to the container, and continuously stir at a stirring speed of 125 r / min in an environment of 10 °C for 2.5 h; then let the solution stand in an environment of -3 °C for 1.75 h, and separate the solution containing the inclusion complex to a reaction kettle; add 24 portions of propylene glycol, and stir at a stirring speed of 140 r / min in an environment of 14 °C for 2.25 h; then let the solution in the reaction kettle stand at a temperature of -3 °C for 1.75 h, transfer the upper layer solution to a distillation device, and perform vacuum distillation at a pressure of 3 kPa and a temperature of 40 °C to obtain preliminarily purified krill oil; transfer the preliminarily purified krill oil to a reaction container, add 185 portions of water, and stir at a stirring speed of 100 r / min and a temperature of 22 °C for 45 min. After the stirring is completed, let it stand in a low-temperature environment of -3 °C for 45 min, and separate the upper layer of krill oil with a high phospholipid content. Example

[0014] Take 90 parts of krill and crush them, then transfer them to a stainless - steel reactor. Add 140 parts of n - butanol and stir - extract at a stirring speed of 200 r / min for 2.5 h at a temperature of 8 °C. After the extraction, let the mixture stand at a temperature of 5 °C for 1.5 h, and separate the upper - layer solution into a glass reaction container. Add 10 parts of β - cyclodextrin to the container and continuously stir at a stirring speed of 150 r / min for 2 h in an environment of 13 °C. Then let the solution stand at an environment of 0 °C for 1.5 h, and separate the solution containing the inclusion compound into the reactor. Add 36 parts of propylene glycol and stir at a stirring speed of 160 r / min for 2 h in an environment of 17 °C. Then let the solution in the reactor stand at a temperature of 0 °C for 1.5 h, transfer the upper - layer solution to a distillation device, and perform vacuum distillation at a pressure of 5 kPa and a temperature of 50 °C to obtain preliminarily purified krill oil. Transfer the preliminarily purified krill oil to a reaction container, add 200 parts of water, stir at a stirring speed of 120 r / min for 30 min at a temperature of 25 °C. After the stirring, let it stand in a low - temperature environment of 0 °C for 30 min, and separate the upper - layer krill oil with a high phospholipid content.

[0015] Table 1 Dosages of each raw material in Examples 1 - 3

[0016] Test Example The purpose of this test group is to explore the influence of different component ratios on krill oil, and detect the phospholipid content, organic solvent residue, and retention of nutritional components of the krill oil of the present invention.

[0017] Test objectives: Test groups A, B, and C respectively adopt the component ratios of the krill oil provided in Examples 1 - 3; The control examples adopt control groups A, B, C, D, and E, where: Control group A Take 80 parts of krill, crush it and transfer it to a stainless-steel reactor. Add 125 parts of n-butanol and stir and extract at a stirring speed of 175 r / min at a temperature of 5 °C for 3 h. After the extraction is completed, let the mixed solution stand at a temperature of 2 °C for 1.75 h, and separate the upper-layer solution into a glass reaction vessel. Directly add 30 parts of propylene glycol to the vessel, stir at a stirring speed of 140 r / min in an environment of 14 °C for 2.25 h. Then let the solution in the reactor stand at a temperature of -3 °C for 1.75 h, transfer the upper-layer solution to a distillation device, and perform vacuum distillation at a pressure of 3 kPa and a temperature of 40 °C to obtain preliminarily purified krill oil. Transfer the preliminarily purified krill oil to a reaction vessel, add 185 parts of water, stir at a stirring speed of 100 r / min at a temperature of 22 °C for 45 min. After the stirring is completed, let it stand in a low-temperature environment of -3 °C for 45 min, and separate the upper-layer krill oil.

[0018] Control group B Weigh 80 parts of krill, crush it and transfer it to a stainless-steel reactor. Add 125 parts of n-butanol and stir and extract at a stirring speed of 175 r / min at a temperature of 5 °C for 3 h. After the extraction is completed, let the mixed solution stand at a temperature of 2 °C for 1.75 h, and separate the upper-layer solution into a glass reaction vessel. Add 10 parts of β-cyclodextrin to the vessel, and continuously stir at a stirring speed of 125 r / min in an environment of 10 °C for 2.5 h. Then let the solution stand in an environment of -3 °C for 1.75 h, and separate the solution containing the inclusion complex into the reactor. Add 30 parts of propylene glycol, stir at a stirring speed of 140 r / min in an environment of 14 °C for 2.25 h. Then let the solution in the reactor stand at a temperature of -3 °C for 1.75 h, transfer the upper-layer solution to a distillation device, and perform vacuum distillation at a pressure of 3 kPa and a temperature of 40 °C to obtain krill oil.

[0019] Control group C Take 80 parts of krill, crush it and transfer it to a stainless-steel reactor. Add 160 parts of n-butanol and stir for extraction at a stirring speed of 175 r / min at a temperature of 5 °C for 3 h. After the extraction is completed, let the mixture stand at a temperature of 2 °C for 1.75 h, and separate the upper-layer solution into a glass reaction vessel. Add 18 parts of β-cyclodextrin to the vessel and continuously stir at a stirring speed of 125 r / min in an environment of 10 °C for 2.5 h. Subsequently, let the solution stand in an environment of -3 °C for 1.75 h, and separate the solution containing the inclusion complex into the reactor. Add 45 parts of propylene glycol and stir at a stirring speed of 140 r / min in an environment of 14 °C for 2.25 h. Then let the solution in the reactor stand at a temperature of -3 °C for 1.75 h, transfer the upper-layer solution to a distillation device, and perform vacuum distillation at a pressure of 3 kPa and a temperature of 40 °C to obtain preliminarily purified krill oil. Transfer the preliminarily purified krill oil to a reaction vessel, add 250 parts of water, stir at a stirring speed of 100 r / min at a temperature of 22 °C for 45 min. After the stirring is completed, let it stand in a low-temperature environment of -3 °C for 45 min, and separate the upper-layer krill oil.

[0020] Control group D Weigh 80 parts of krill, crush it and transfer it to a stainless-steel reactor. Add 90 parts of n-butanol and stir for extraction at a stirring speed of 175 r / min at a temperature of 5 °C for 3 h. After the extraction is completed, let the mixture stand at a temperature of 2 °C for 1.75 h, and separate the upper-layer solution into a glass reaction vessel. Add 5 parts of β-cyclodextrin to the vessel and continuously stir at a stirring speed of 125 r / min in an environment of 10 °C for 2.5 h. Subsequently, let the solution stand in an environment of -3 °C for 1.75 h, and separate the solution containing the inclusion complex into the reactor. Add 15 parts of propylene glycol and stir at a stirring speed of 140 r / min in an environment of 14 °C for 2.25 h. Then let the solution in the reactor stand at a temperature of -3 °C for 1.75 h, transfer the upper-layer solution to a distillation device, and perform vacuum distillation at a pressure of 3 kPa and a temperature of 40 °C to obtain preliminarily purified krill oil. Transfer the preliminarily purified krill oil to a reaction vessel, add 150 parts of water, stir at a stirring speed of 100 r / min at a temperature of 22 °C for 45 min. After the stirring is completed, let it stand in a low-temperature environment of -3 °C for 45 min, and separate the upper-layer krill oil.

[0021] Control group E Using the organic solvent extraction method in the prior art, 80 parts of krill were taken, crushed, and then extracted with a conventional organic solvent (such as ethanol). The crushed krill was placed in a reaction vessel, an appropriate amount of ethanol was added, and the mixture was continuously stirred at a stirring speed of 250 r / min at a temperature of 40 °C for 4 h. After the extraction, according to the conventional separation method in the prior art, larger particle impurities were first removed by filtration, and then centrifuged to further remove fine impurities. After that, a rotary evaporator was used for preliminary concentration at 60 °C under reduced pressure to remove most of the ethanol solvent. The product after preliminary concentration was further separated and purified by silica gel column chromatography. n-Hexane-ethyl acetate (volume ratio 4:1) was selected as the eluent for elution, and the eluate containing krill oil was collected and subjected to vacuum distillation again to remove the remaining eluent.

[0022] Test method: According to the phospholipid content, organic solvent residue and nutrient retention of the krill oil of the present invention, tests were carried out respectively. The specific test methods are as follows: Determination of phospholipid content: Test conditions: Determination was carried out using the molybdenum blue colorimetric method; 0.1 g of krill oil sample was accurately weighed and placed in a 10 mL stoppered test tube. 5 mL of chloroform-methanol (2:1, v / v) mixed solution was added, and the mixture was shaken until completely dissolved. Then 2 mL of ammonium molybdate solution (5 g / L) and 1 mL of sulfuric acid solution (50%, v / v) were added, shaken and mixed well, and then heated in a water bath at 70 °C for 10 min, cooled to room temperature, and the chloroform-methanol (2:1, v / v) mixed solution was used as the blank control, and the absorbance was measured at a wavelength of 650 nm; Test method: According to the standard curve (plotted with phospholipid standard products of known concentration), the phospholipid content in the sample was calculated. Phospholipid content (%) = (C×V×f) / (m×1000)×100, where C is the phospholipid concentration (μg / mL) obtained from the standard curve, V is the volume (mL) of the sample solution, f is the dilution factor, and m is the sample mass (g).

[0023] Determination of organic solvent residue: Experimental conditions: gas chromatography (GC) was used for determination, and the chromatographic column was a DB-624 capillary column (60m×0.32mm×1.8μm); the injection port temperature was 250℃; the detector temperature was 280℃; the column temperature was programmed: the initial temperature was 40℃, maintained for 5min, and then heated to 200℃ at a rate of 10℃ / min and maintained for 5min. The carrier gas was nitrogen with a flow rate of 1.0mL / min; the injection volume was 1μL, and the split ratio was 10:1; Experimental method: about 1g of krill oil sample was accurately weighed, placed in an empty bottle, sealed, and determined according to the above gas chromatography conditions. The residual amount of organic solvent (n-butanol) in the sample was calculated according to the standard curve (drawn with a known concentration of n-butanol standard), and the residual amount of organic solvent (mg / kg) = (C×V) / m, where C is the organic solvent concentration (μg / mL) obtained from the standard curve, V is the volume of the sample solution (mL), and m is the sample mass (g).

[0024] Nutrient retention determination (taking Omega-3 fatty acids and astaxanthin as examples): Omega-3 fatty acid determination: Experimental conditions: gas chromatography-mass spectrometry (GC-MS) was used for determination, and the chromatographic column was a DB-23 capillary column (60m×0.25mm×0.25μm); the injection port temperature was 250℃; the interface temperature was 280℃; the ion source temperature was 230℃; the column temperature was programmed: the initial temperature was 100℃, maintained for 1min, the temperature was increased to 200℃ at a rate of 10℃ / min, maintained for 1min, and then increased to 230℃ at a rate of 5℃ / min, maintained for 10min, the carrier gas was helium, and the flow rate was 1.0mL / min; the injection volume was 1μL, and the split ratio was 10:1; Experimental method: about 0.1g of krill oil sample was accurately weighed, and after methyl esterification, it was determined according to the above GC-MS conditions, and the content of Omega-3 fatty acids in the sample was calculated according to the standard curve (drawn with Omega-3 fatty acid standards of known concentrations); Astaxanthin determination: Experimental conditions: High performance liquid chromatography (HPLC) was used for determination, the chromatographic column was a C18 column (250 mm × 4.6 mm, 5 μm), the mobile phase was methanol-acetonitrile-water (80:15:5, v / v / v), the flow rate was 1.0 mL / min, the detection wavelength was 470 nm, the column temperature was 30 ° C, and the injection volume was 20 μL; Experimental method: Accurately weigh about 0.1 g of krill oil sample, dissolve it with an appropriate amount of dichloromethane, filter it, and take the filtrate for determination according to the above HPLC conditions, and calculate the astaxanthin content in the sample according to the standard curve (drawn with an astaxanthin standard of known concentration).

[0025] Specific detection indicators are shown in Table 2.

[0026] Table 2 Detection indexes of each sample

[0027] According to Figures 2 - 5 and Table 2, the summary of the above comparative data is as follows: In terms of phospholipid content: For experimental groups A, B, and C, the preparation method of high-phospholipid-content krill oil of the present invention is adopted, and the phospholipid contents are 45%, 48%, and 50% respectively; in control group A, β-cyclodextrin was not used for inclusion treatment, and propylene glycol was directly added, and the phospholipid content was only 30%. Due to the lack of the enrichment effect of β-cyclodextrin on phospholipids, phospholipids could not be effectively separated from impurities, resulting in a low content; although β-cyclodextrin was used in control group B, the subsequent treatment might not be perfect enough, and the phospholipid content was 35%; the raw material dosages of control groups C and D were quite different from those of the present invention, and the phospholipid contents were 38% and 28% respectively, indicating that the raw material ratio has an important influence on the phospholipid enrichment effect; control group E adopted the existing technology of organic solvent extraction method, and the phospholipid content was only 25%, because the existing technology did not enrich phospholipids through special treatments such as β-cyclodextrin and propylene glycol, and organic solvents might have a certain destruction on phospholipids, so the content was the lowest.

[0028] In terms of the residual amount of organic solvents: The residual amounts of organic solvents in experimental groups A, B, and C are 5 mg / kg, 4 mg / kg, and 3 mg / kg respectively, which are at a relatively low level; the residual amounts of organic solvents in control groups A, B, C, and D are 10 mg / kg, 8 mg / kg, 7 mg / kg, and 12 mg / kg respectively, all higher than those in the experimental groups; control group E adopted the existing technology of organic solvent extraction method, and the residual amount was as high as 15 mg / kg. The present invention effectively reduces the usage amount of organic solvents through low-temperature multiple layering operations, and removes organic solvents through steps during the preparation process, reducing the residual amount. In the control groups, some did not adopt the layering treatment method of the present invention, or the raw material ratio was unreasonable, resulting in difficult effective removal of organic solvents and a high residual amount.

[0029] In terms of the retention of nutritional components (taking Omega-3 fatty acids and astaxanthin as examples): Omega-3 fatty acid content: The Omega-3 fatty acid contents in experimental groups A, B, and C are 18%, 20%, and 22% respectively. The contents in control groups A, B, C, D, and E are 12%, 15%, 16%, 10%, and 8% respectively; in the preparation method of the present invention, during the low-temperature multiple layering process, the destruction of other bioactive components such as Omega-3 fatty acids is less, and its content is better retained; in the control groups, due to the use and treatment methods of organic solvents being different, it may lead to partial loss or structural damage of Omega-3 fatty acids, resulting in a low content; Astaxanthin content: The astaxanthin contents in experimental groups A, B, and C were 12 mg / kg, 14 mg / kg, and 16 mg / kg respectively. The contents in control groups A, B, C, D, and E were 8 mg / kg, 10 mg / kg, 11 mg / kg, 7 mg / kg, and 5 mg / kg respectively. Through the preparation steps, especially the protective effect on phospholipids, the present invention indirectly reduces the influence on other active ingredients such as astaxanthin, resulting in a relatively high astaxanthin content. Due to the residual organic solvents and unreasonable treatment process in the control group, the destruction of astaxanthin is relatively large, leading to a lower content.

[0030] In summary, the preparation method of krill oil with high phospholipid content of the present invention has good effects in increasing the phospholipid content, reducing the residual amount of organic solvents, and retaining nutrients through low-temperature multi-layer separation treatment, combined with the application of β-cyclodextrin and propylene glycol, and the water addition and purification step. Compared with the prior art and the control groups with different raw material ratios and treatment methods, it has better effects, improves the product safety and nutritional value, also improves the production efficiency, reduces the cost, and has high economic benefits.

[0031] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and descriptions in the specification are only preferred examples of the present invention and do not limit the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of the present invention claimed is defined by the appended claims and their equivalents.

Claims

1. A method for preparing krill oil with high phospholipid content, characterized in that: The raw materials used in the preparation method include at least krill, n-butanol, β-cyclodextrin, propylene glycol and water. Meanwhile, the preparation method also includes the following steps: S1. First extraction: Use a food grinder to grind the krill, transfer it to a stainless steel reactor, add n-butanol, and turn on the stirring device for stirring extraction; S2, first stratification: let the mixed solution in the reactor stand until stratification occurs, and then use a separatory funnel to transfer the upper layer of the solution to a glass reaction container; S3, β-cyclodextrin treatment: adding β-cyclodextrin into a glass reaction container, turning on a stirring device to stir, and forming a stable inclusion system; S4, second stratification: the solution in the glass reaction container is allowed to stand until stratification occurs, and then the upper layer of the solution is separated using a separatory funnel and transferred to a reactor; S5. Adding propylene glycol: adding propylene glycol into the reaction kettle, turning on the stirring device for stirring, changing the physical properties of the system, and enriching the phospholipids in the krill oil; S6. Third stratification and final separation: The solution in the reactor is allowed to stand until stratification occurs, and then the upper layer of the solution is transferred to a distillation device using a separatory funnel for vacuum distillation to obtain preliminarily purified krill oil; S7. Purification by adding water: The krill oil is transferred to a reaction container, water is added, and a stirring device is turned on for stirring. The solution is then allowed to stand for stratification, and a separatory funnel is used to separate the upper layer of the solution to obtain the krill oil.

2. The method for preparing krill oil with high phospholipid content according to claim 1, characterized in that: The amount of krill used is 70-90 parts; the amount of n-butanol used is 110-140 parts; the amount of beta-cyclodextrin used is 8-12 parts; the amount of propylene glycol used is 24-36 parts; and the amount of water used is 170-200 parts.

3. The method for preparing krill oil with high phospholipid content according to claim 1, characterized in that: In S1, the stirring device stirs and extracts at a stirring speed of 150 r / min-200 r / min and a temperature of 3° C.-8° C. for 2.5 h-3.5 h.

4. The method for preparing krill oil with high phospholipid content according to claim 1, characterized in that: In S2, the mixed solution in the reaction kettle is allowed to stand at a temperature of 5°C-0°C for 1.5h-2h.

5. The method for preparing krill oil with high phospholipid content according to claim 1, characterized in that: In S3, the stirring device continuously stirs for 2h-3h at a stirring speed of 100r / min-150r / min and an environment of 8°C-13°C.

6. The method for preparing krill oil with high phospholipid content according to claim 1, characterized in that: In S4, the solution in the glass reaction container is allowed to stand at -5°C to 0°C for 1.5h to 2h.

7. The method for preparing krill oil with high phospholipid content according to claim 1, characterized in that: In S5, the stirring device stirs at a stirring speed of 120 r / min-160 r / min and an environment of 12° C.-17° C. for 2 h-2.5 h.

8. The method for preparing krill oil with high phospholipid content according to claim 1, characterized in that: In S6, the solution in the reaction kettle is allowed to stand at a temperature of -5°C to 0°C for 1.5h to 2h.

9. The method for preparing krill oil with high phospholipid content according to claim 1, characterized in that: In S6, the distillation apparatus performs reduced pressure distillation at a pressure of 1 kPa-5 kPa and a temperature of 30°C-50°C.

10. The method for preparing krill oil with high phospholipid content according to claim 1, characterized in that: In S7, the stirring device stirs at a stirring speed of 80 r / min-120 r / min and a temperature of 20° C.-25° C. for 30 min-60 min; and the solution is allowed to stand at a low temperature environment of -5° C.-0° C. for 30 min-60 min.

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