A deodorized Antarctic krill oil and its extraction method

Abstract

The present invention belongs to the field of food technology, and particularly relates to a deodorized Antarctic krill oil and an extraction method thereof. Compared with the prior art, the present invention performs deodorization treatment through modified nanofiltration membrane treatment and refining process, reducing the fishy smell of Antarctic krill oil while ensuring the extraction rate of krill oil. At the same time, the method has simple process and low cost, solving the problems of reduced product extraction rate, poor deodorization effect, harsh preparation conditions and high cost caused by the existing deodorization technology, and improving the acceptance and use experience of consumers as a functional food.

Description

Technical Field

[0001] The present invention belongs to the technical field of food, and particularly relates to a deodorized Antarctic krill oil and an extraction method thereof. Background Art

[0002] Antarctic krill oil is extracted from Antarctic krill and is rich in active ingredients such as phospholipids, unsaturated fatty acids, astaxanthin, etc. A large number of studies have proven that Antarctic krill oil, as a functional food, has significant effects in improving cardiovascular health, preventing neurodegenerative diseases of the brain, protecting the liver and bone joints, etc. However, currently available Antarctic krill oil products generally have a certain fishy smell, which greatly affects the acceptance and usage experience of consumers. The fishy smell substances in Antarctic krill oil include unsaturated esters, amines, etc., among which the content of unsaturated esters is relatively high, which is one of the main reasons for the fishy smell of Antarctic krill oil.

[0003] Currently, there are few studies on the deodorization of Antarctic krill oil. The existing deodorization technologies mainly include adsorption method, encapsulation method, microbial fermentation method, enzymatic hydrolysis method, plant-based deodorants, etc. However, these methods often have limitations. Commonly used adsorbents include activated carbon, clay, alumina, etc. Their adsorption selectivity is poor, and while adsorbing fishy smell substances, they will also adsorb some other substances that are important for the nutrition of the product, reducing the extraction rate of krill oil. The encapsulation method is difficult to achieve complete encapsulation of fishy smell substances, and the deodorization effect is poor. When using the microbial fermentation method for deodorization, the fermentation conditions are extremely harsh, and temperature, pH value, dissolved oxygen content, etc. need to be strictly controlled. If the conditions are slightly inappropriate, the growth and metabolism of microorganisms will be inhibited, thus affecting the deodorization effect. When using the enzymatic hydrolysis method for deodorization, the activity of the enzyme is also affected by various factors such as temperature, pH value, and substrate concentration. Deviating from the optimal range, the activity of the enzyme will decrease or even inactivate, thus affecting the deodorization effect. At the same time, some side reactions may occur during the enzymatic hydrolysis process, generating new off-flavor substances, such as the over-decomposition of proteins to produce bitter peptides, etc., which affect the overall flavor of the product, and the cost of enzyme preparations is relatively high, affecting the economic benefits of the product. Plant-based deodorants include spices, tea leaves, perilla, scallions, ginger, garlic, etc. Most of these deodorants mask the fishy smell through their unique odors and flavors, and the fishy smell in the product may reappear over time.

[0004] The Chinese patent with the application number 201810078300.X discloses a preparation method of high-quality Antarctic krill oil. During the preparation process, a method of multi-stage grinding combined with enzymatic hydrolysis is adopted to achieve the deodorization of krill oil. However, the types and amounts of removed odor substances are not clear, and only the deodorization effect is judged by the faintness of the odor, which has subjective deviation. The Chinese patent with the application number 201810842218.X discloses a deaminated low-odor krill oil and its preparation method. During the preparation process of krill oil, ion exchange resin and macroporous adsorption resin are used for adsorption deodorization, reducing the content of trimethylamine and trimethylamine oxide in krill oil. However, this method does not remove another major type of odor substances in Antarctic krill oil - unsaturated esters. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a deodorized Antarctic krill oil and its extraction method, which ensures the extraction rate of krill oil while reducing the odor of Antarctic krill oil.

[0006] The present invention provides an extraction method of deodorized Antarctic krill oil, comprising the following steps:

[0007] S1) Extract Antarctic krill powder with an ethanol aqueous solution to obtain an extract;

[0008] S2) Perform nanofiltration treatment on the extract to obtain a retentate; the nanofiltration membrane used for the nanofiltration treatment comprises a base membrane; trehalose is grafted on the surface of the base membrane;

[0009] S3) Concentrate the retentate to obtain a concentrated solution;

[0010] S4) Mix the concentrated solution with an aqueous solution of NaH2PO4, and sediment to obtain a precipitate phase;

[0011] S5) Mix the precipitate phase with ethanol, and concentrate to obtain deodorized Antarctic krill oil.

[0012] Preferably, the nanofiltration membrane is prepared according to the following method:

[0013] Immerse the base membrane in a trehalose aqueous solution and then perform heat treatment to obtain the nanofiltration membrane.

[0014] Preferably, the surface of the base membrane has carboxyl functional groups;

[0015] The density of carboxyl functional groups in the base membrane is 0.8 mmol / g - 1.3 mmol / g;

[0016] The molecular weight cut-off of the base membrane is 300 - 800 Dalton;

[0017] The mass concentration of trehalose in the trehalose aqueous solution is 10% - 20%.

[0018] Preferably, the soaking time is 1 to 5 h;

[0019] The temperature of the heat treatment is 50°C to 70°C; the time of the heat treatment is 5 to 15 min.

[0020] Preferably, in the step S1), the mass concentration of ethanol in the ethanol aqueous solution is 90% to 98%;

[0021] The mass-volume ratio of the Antarctic krill powder to the ethanol aqueous solution is 1 g:(5 to 10) mL;

[0022] The extraction time is 1 to 5 h.

[0023] Preferably, the pressure of the nanofiltration treatment is 10 to 20 bar.

[0024] Preferably, in the step S3), the volume of the concentrated solution is 1 / 3 to 1 / 7 of the volume of the retentate.

[0025] Preferably, the mass concentration of the NaH2PO4 aqueous solution is 0.5% to 3%;

[0026] The volume ratio of the concentrated solution to the NaH2PO4 aqueous solution is 1:(1 to 3);

[0027] The sedimentation time is 6 to 15 h.

[0028] Preferably, the mass-volume ratio of the precipitate phase to ethanol is 1 g:(1 to 3) mL.

[0029] The present invention also provides a deodorized Antarctic krill oil obtained by the above extraction method, wherein the content of ethyl palmitate in the deodorized Antarctic krill oil is less than 1 mg / g; the content of 2-(dimethylamino)ethyl 3-cyclopentylpropionate in the deodorized Antarctic krill oil is less than 2 mg / g; the content of methyl 5,8,11,14,17-eicosapentaenoate in the deodorized Antarctic krill oil is less than 2 mg / g; the content of ethyl 3,6,9,12,15-eicosapentaenoate in the deodorized Antarctic krill oil is less than 1 mg / g.

[0030] The present invention also provides a food comprising the above deodorized Antarctic krill oil.

[0031] The present invention provides a method for extracting deodorized Antarctic krill oil, comprising the following steps: S1) extracting Antarctic krill powder with an aqueous ethanol solution to obtain an extract; S2) subjecting the extract to nanofiltration treatment to obtain a retentate; the nanofiltration membrane used in the nanofiltration treatment comprises a base membrane; trehalose is grafted on the surface of the base membrane; S3) concentrating the retentate to obtain a concentrated solution; S4) mixing the concentrated solution with an aqueous NaH2PO4 solution and sedimenting to obtain a precipitate phase; S5) mixing the precipitate phase with ethanol and concentrating to obtain deodorized Antarctic krill oil. Compared with the prior art, the present invention performs deodorization treatment through modified nanofiltration membrane treatment and refining process, reducing the fishy smell of Antarctic krill oil while ensuring the extraction rate of krill oil. At the same time, the method has a simple process and low cost, solving the problems of reduced product extraction rate, poor deodorization effect, harsh preparation conditions and high cost caused by the existing deodorization technology, and improving the acceptance and use experience of consumers as a functional food. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is the gas chromatography-mass spectrometry chromatogram of the Antarctic krill oil obtained in Comparative Example 1 of the present invention;

[0033] Figure 2 is the gas chromatography-mass spectrometry chromatogram of the Antarctic krill oil obtained in Example 2 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0035] The present invention provides a method for extracting deodorized Antarctic krill oil, comprising the following steps: S1) extracting Antarctic krill powder with an aqueous ethanol solution to obtain an extract; S2) subjecting the extract to nanofiltration treatment to obtain a retentate; the nanofiltration membrane used in the nanofiltration treatment comprises a base membrane; trehalose is grafted on the surface of the base membrane; S3) concentrating the retentate to obtain a concentrated solution; S4) mixing the concentrated solution with an aqueous NaH2PO4 solution and sedimenting to obtain a precipitate phase; S5) mixing the precipitate phase with ethanol and concentrating to obtain deodorized Antarctic krill oil.

[0036] Among them, the present invention does not have special restrictions on the sources of all raw materials, and they can be commercially available.

[0037] Extract Antarctic krill powder with an aqueous ethanol solution to obtain an extract; the mass concentration of ethanol in the aqueous ethanol solution is preferably 90% - 98%, more preferably 93% - 97%, and still more preferably 95% - 97%; the mass-to-volume ratio of Antarctic krill powder to the aqueous ethanol solution is preferably 1 g:(5 - 10) mL, more preferably 1 g:(6 - 10) mL, still more preferably 1 g:(7 - 9) mL, and most preferably 1 g:8 mL; the extraction is preferably carried out at room temperature; the extraction time is preferably 1 - 5 h, more preferably 2 - 4 h, still more preferably 2 - 3 h, and most preferably 2.5 h.

[0038] Subject the extract to nanofiltration treatment to obtain a retentate; the nanofiltration membrane used in the nanofiltration treatment includes a base membrane; the surface of the base membrane preferably has carboxyl functional groups; the hydroxyl groups on trehalose can be grafted onto the surface of the base membrane by reacting with the carboxyl functional groups on the surface of the base membrane; the density of carboxyl functional groups in the base membrane is preferably between 0.8 mmol / g and 1.3 mmol / g; optionally, the density of carboxyl functional groups in the base membrane is 0.8 mmol / g, 0.9 mmol / g, 1 mmol / g, 1.1 mmol / g, 1.2 mmol / g, 1.3 mmol / g or the range between any two of the above values; the base membrane is preferably an organic polymer nanofiltration membrane; the molecular weight cut-off of the base membrane is preferably 300 - 800 Daltons, more preferably 400 - 600 Daltons, still more preferably 500 Daltons; the pressure of the nanofiltration treatment is preferably 10 - 20 bar, more preferably 13 - 18 bar, still more preferably 14 - 16 bar, and most preferably 15 bar.

[0039] In a specific embodiment provided by the present invention, the nanofiltration membrane is prepared by the following method: soak the base membrane in a trehalose aqueous solution and then perform heat treatment to obtain the nanofiltration membrane; the mass concentration of trehalose in the trehalose aqueous solution is preferably 10% - 20%; optionally, the mass concentration of trehalose in the trehalose aqueous solution is 10%, 12%, 15%, 18%, 20% or the range between any two of the above values; the soaking time is preferably 1 - 5 h, more preferably 1 - 4 h, still more preferably 2 - 3 h, and most preferably 2 h; after soaking, it is preferably taken out and drained of the excess solution, and then heat treatment is carried out; the temperature of the heat treatment is preferably 50°C - 70°C, more preferably 55°C - 65°C, still more preferably 60°C; the time of the heat treatment is preferably 5 - 15 min, more preferably 8 - 12 min, still more preferably 10 min.

[0040] Concentrate the retentate to obtain a concentrated solution; the volume of the concentrated solution is preferably 1 / 3 to 1 / 7 of the volume of the retentate, more preferably 1 / 4 to 1 / 6 of the volume of the retentate, and still more preferably 1 / 5 of the volume of the retentate.

[0041] Mix the concentrated solution with an aqueous solution of NaH₂PO₄ and sediment to obtain a precipitate phase; the mass concentration of the aqueous solution of NaH₂PO₄ is preferably 0.5% to 3%; optionally, the mass concentration of the aqueous solution of NaH₂PO₄ is 0.5%, 1%, 1.5%, 2%, 2.5%, 3% or the range between any two of the above values; the sedimentation time is preferably 6 to 15 h, more preferably 6 to 12 h, and still more preferably 8 to 10 h.

[0042] Mix the precipitate phase with ethanol and concentrate to obtain deodorized Antarctic krill oil; the mass-to-volume ratio of the precipitate phase to ethanol is preferably 1 g:(1 - 3) mL, more preferably 1 g:(1.5 - 2.5) mL, and still more preferably 1 g:2 mL; the concentration is preferably vacuum concentration.

[0043] The present invention performs deodorization treatment through a modified nanofiltration membrane treatment and refining process, reducing the fishy smell of Antarctic krill oil while ensuring the extraction rate of krill oil. At the same time, this method has a simple process and low cost, solving the problems of reduced product extraction rate, poor deodorization effect, harsh preparation conditions and high cost caused by existing deodorization technologies, and improving the acceptance and usage experience of consumers as a functional food.

[0044] The present invention also provides a deodorized Antarctic krill oil obtained by the above extraction method, wherein the content of ethyl palmitate in the deodorized Antarctic krill oil is less than 1 mg / g; the content of 2-(dimethylamino)ethyl 3-cyclopentylpropionate in the deodorized Antarctic krill oil is less than 2 mg / g; the content of methyl 5,8,11,14,17-eicosapentaenoate in the deodorized Antarctic krill oil is less than 2 mg / g; the content of ethyl 3,6,9,12,15-eicosapentaenoate in the deodorized Antarctic krill oil is less than 1 mg / g.

[0045] In a specific embodiment provided by the present invention, the content of ethyl palmitate in the deodorized Antarctic krill oil is preferably less than 0.8 mg / g, more preferably less than 0.6 mg / g, still more preferably less than 0.55 mg / g, and most preferably less than 0.55 mg / g.

[0046] In a specific embodiment provided by the present invention, the content of 2-(dimethylamino)ethyl 3-cyclopentylpropionate in the deodorized Antarctic krill oil is preferably less than 1.5 mg / g, more preferably less than 1.1 mg / g.

[0047] In a specific embodiment provided by the present invention, the content of methyl 5,8,11,14,17 - eicosapentaenoate in the deodorized Antarctic krill oil is preferably less than 1.5 mg / g, more preferably less than 1.1 mg / g.

[0048] In a specific embodiment provided by the present invention, the content of ethyl 3,6,9,12,15 - eicosapentaenoate in the deodorized Antarctic krill oil is preferably less than 0.8 mg / g, more preferably less than 0.7 mg / g, still more preferably less than 0.6 mg / g, and most preferably less than 0.5 mg / g.

[0049] The present invention also provides a food comprising the above - mentioned deodorized Antarctic krill oil.

[0050] To further illustrate the present invention, the following examples are used to describe in detail a deodorized Antarctic krill oil and its extraction method provided by the present invention.

[0051] All reagents used in the following examples are commercially available.

[0052] Comparative Example 1: In the preparation process of Antarctic krill oil in this comparative example, it does not go through nanofiltration membrane treatment and only goes through impurity removal by washing with pure water.

[0053] 1.1 Take 400 g of Antarctic krill powder, add 3.2 L of 97% ethanol solution, stir and extract at room temperature for 2.5 h, and centrifuge to remove the residue to obtain 3000 mL of extract.

[0054] 1.2 Concentrate the extract under reduced pressure to 600 mL, add 1200 mL of pure water, mix and stir for washing and impurity removal, and then settle overnight.

[0055] 1.3 Take 73 g of the precipitated phase after sedimentation, add 146 mL of absolute ethanol, stir and mix evenly, and then continue to concentrate under reduced pressure to obtain 69 g of Antarctic krill oil.

[0056] Comparative Example 2: In the preparation process of Antarctic krill oil in this comparative example, it does not go through nanofiltration membrane treatment and only goes through impurity removal by washing with 1% NaH₂PO₄ solution.

[0057] 2.1 Take 400 g of Antarctic krill powder, add 3.2 L of 97% ethanol solution, stir and extract at room temperature for 2.5 h, and centrifuge to remove the residue to obtain 3000 mL of extract.

[0058] 2.2 Concentrate the extract under reduced pressure to 600 mL, add 1200 mL of 1% NaH₂PO₄ solution, mix and stir for washing and impurity removal, and then settle overnight.

[0059] 2.3 Take 72 g of the precipitated phase after sedimentation, add 144 mL of absolute ethanol, stir and mix evenly, and then continue to concentrate under reduced pressure to obtain 68 g of Antarctic krill oil.

[0060] Comparative Example 3: In the preparation process of Antarctic krill oil in this comparative example, it was treated with a common nanofiltration membrane and washed with 1% NaH2PO4 to remove impurities.

[0061] 3.1 Take 400 g of Antarctic krill powder, add 3.2 L of 97% ethanol solution, stir and extract at room temperature for 2.5 h, and centrifuge to remove the residue to obtain 3000 mL of the extract.

[0062] 3.2 Treat the extract with an organic polymer nanofiltration membrane with a carboxyl functional group (density: 0.8 mmol / g - 1.3 mmol / g) on the surface and a molecular weight cut-off of 500 Da, and select a pressure of 15 bar to obtain 2100 mL of the retentate.

[0063] 3.3 Concentrate the retentate under reduced pressure to 420 mL, add 840 mL of 1% NaH2PO4 solution, mix and stir for washing and impurity removal, and then sediment overnight.

[0064] 3.4 Take 75 g of the precipitated phase after sedimentation, add 150 mL of absolute ethanol, stir and mix evenly, and then continue to concentrate under reduced pressure to obtain 69 g of Antarctic krill oil.

[0065] Comparative Example 4: In the preparation process of Antarctic krill oil in this comparative example, it was treated with a lactose-modified nanofiltration membrane and washed with 1% NaH2PO4 to remove impurities.

[0066] 4.1 Take 400 g of Antarctic krill powder, add 3.2 L of 97% ethanol solution, stir and extract at room temperature for 2.5 h, and centrifuge to remove the residue to obtain 3000 mL of the extract.

[0067] 4.2 Treat the extract with a lactose-modified nanofiltration membrane, select a pressure of 15 bar, and obtain 2100 mL of the retentate.

[0068] 4.3 Concentrate the retentate under reduced pressure to 420 mL, add 840 mL of 1% NaH2PO4 solution, mix and stir for washing and impurity removal, and then sediment overnight.

[0069] 4.4 Take 71 g of the precipitated phase after sedimentation, add 142 mL of absolute ethanol, stir and mix evenly, and then continue to concentrate under reduced pressure to obtain 67 g of Antarctic krill oil.

[0070] Preparation method of lactose-modified nanofiltration membrane: ① Use an organic polymer nanofiltration membrane with a carboxyl functional group on the surface (density: 0.8 mmol / g - 1.3 mmol / g) and a molecular weight cut-off of 500 Dalton as the base membrane. After rinsing it clean with deionized water, let it dry naturally. ② Immerse the dried membrane in a 15% lactose aqueous solution for 2 h, then take out the membrane and drain the excess solution. ③ Place the drained membrane in an oven at 60 °C for heat treatment for 5 min to obtain the lactose-modified nanofiltration membrane.

[0071] Comparative Example 5: During the preparation process of Antarctic krill oil in this comparative example, it was treated with a trehalose-modified nanofiltration membrane and washed with pure water to remove impurities.

[0072] 5.1 Take 400 g of Antarctic krill powder, add 3.2 L of 97% ethanol solution, stir and extract at room temperature for 2.5 h, and centrifuge to remove the residue to obtain 3000 mL of extract.

[0073] 5.2 Treat the extract with a trehalose-modified nanofiltration membrane, select a pressure of 15 bar, and obtain 2100 mL of retentate.

[0074] 5.3 Concentrate the retentate under reduced pressure to 420 mL, add 840 mL of pure water, mix and stir for washing and impurity removal, and then let it settle overnight.

[0075] 5.4 Take 72 g of the precipitated phase after sedimentation, add 144 mL of absolute ethanol, stir and mix evenly, and then continue to concentrate under reduced pressure to obtain 68.5 g of Antarctic krill oil.

[0076] Example 1

[0077] 1.1 Take 400 g of Antarctic krill powder, add 3.2 L of 97% ethanol solution, stir and extract at room temperature for 2.5 h, and centrifuge to remove the residue to obtain 3000 mL of extract.

[0078] 1.2 Treat the extract with a nanofiltration membrane modified with 10% trehalose, select a pressure of 15 bar, and obtain 2100 mL of retentate.

[0079] 1.3 Concentrate the retentate under reduced pressure to 420 mL, add 840 mL of 1% NaH2PO4 solution, mix and stir for washing and impurity removal, and then let it settle overnight.

[0080] 1.4 Take 72 g of the precipitated phase after sedimentation, add 144 mL of absolute ethanol, stir and mix evenly, and then continue to concentrate under reduced pressure to obtain 67 g of Antarctic krill oil.

[0081] Preparation method of 10% trehalose-modified nanofiltration membrane: ① Use an organic polymer nanofiltration membrane with a carboxyl functional group (density: 0.8 mmol / g - 1.3 mmol / g) on the surface and a molecular weight cut-off of 500 Da as the base membrane. After rinsing it thoroughly with deionized water, let it dry naturally. ② Immerse the dried membrane in a 10% trehalose aqueous solution for 2 h, then take out the membrane and drain the excess solution. ③ Place the drained membrane in an oven at 60 °C for heat treatment for 10 min to obtain a 10% trehalose-modified nanofiltration membrane.

[0082] Example 2

[0083] 2.1 Take 400 g of Antarctic krill powder, add 3.2 L of 97% ethanol solution, stir and extract at room temperature for 2.5 h, and centrifuge to remove the residue to obtain 3000 mL of extract.

[0084] 2.2 Treat the extract with a nanofiltration membrane modified with 15% trehalose, select a pressure of 15 bar, and obtain 2100 mL of retentate.

[0085] 2.3 Concentrate the retentate under reduced pressure to 420 mL, add 840 mL of 1% NaH2PO4 solution, mix and stir for washing and impurity removal, and then sediment overnight.

[0086] 2.4 Take 74 g of the precipitated phase after sedimentation, add 148 mL of absolute ethanol, stir and mix evenly, and then continue to concentrate under reduced pressure to obtain 67.5 g of Antarctic krill oil.

[0087] The preparation method of the 15% trehalose-modified nanofiltration membrane is the same as that of the 10% trehalose-modified nanofiltration membrane in Example 1, except that the 10% trehalose aqueous solution is replaced with a 15% trehalose aqueous solution.

[0088] Example 3

[0089] 3.1 Take 400 g of Antarctic krill powder, add 3.2 L of 97% ethanol solution, stir and extract at room temperature for 2.5 h, and centrifuge to remove the residue to obtain 3000 mL of extract.

[0090] 3.2 Treat the extract with a nanofiltration membrane modified with 20% trehalose, select a pressure of 15 bar, and obtain 2100 mL of retentate.

[0091] 3.3 Concentrate the retentate under reduced pressure to 420 mL, add 840 mL of 1% NaH2PO4 solution, mix and stir for washing and impurity removal, and then sediment overnight.

[0092] 3.4 Take 75 g of the precipitated phase after sedimentation, add 150 mL of absolute ethanol, stir and mix evenly, and then continue to concentrate under reduced pressure to obtain 69 g of Antarctic krill oil.

[0093] The preparation method of the 20% trehalose-modified nanofiltration membrane is the same as that of the 10% trehalose-modified nanofiltration membrane in Example 1, except that the 10% trehalose aqueous solution is replaced with a 20% trehalose aqueous solution.

[0094] Example 4

[0095] 4.1 Take 400 g of Antarctic krill powder, add 3.2 L of 97% ethanol solution, stir and extract at room temperature for 2.5 h, and centrifuge to remove the residue to obtain 3000 mL of extract.

[0096] 4.2 Treat the extract with a nanofiltration membrane modified with 15% trehalose, select a pressure of 15 bar, and obtain 2100 mL of retentate.

[0097] 4.3 Concentrate the retentate under reduced pressure to 420 mL, add 840 mL of 0.5% NaH2PO4 solution, mix and stir for washing and impurity removal, and then sediment overnight.

[0098] 4.4 Take 71 g of the precipitated phase after sedimentation, add 142 mL of absolute ethanol, stir and mix evenly, and then continue to concentrate under reduced pressure to obtain 68.5 g of Antarctic krill oil.

[0099] Example 5

[0100] 5.1 Take 400 g of Antarctic krill powder, add 3.2 L of 97% ethanol solution, stir and extract at room temperature for 2.5 h, and centrifuge to remove the residue to obtain 3000 mL of extract.

[0101] 5.2 Treat the extract with a nanofiltration membrane modified with 15% trehalose, select a pressure of 15 bar, and obtain 2100 mL of retentate.

[0102] 5.3 Concentrate the retentate under reduced pressure to 420 mL, add 840 mL of 2% NaH2PO4 solution, mix and stir for washing and impurity removal, and then sediment overnight.

[0103] 5.4 Take 73 g of the precipitated phase after sedimentation, add 146 mL of absolute ethanol, stir and mix evenly, and then continue to concentrate under reduced pressure to obtain 68 g of Antarctic krill oil.

[0104] The Antarctic krill oil obtained in Comparative Examples 1-5 and Examples 1-5 was analyzed by gas chromatography-mass spectrometry, and the components in the Antarctic krill oil are shown in Table 1; the gas chromatography-mass spectrometry chromatogram of the Antarctic krill oil obtained in Comparative Example 1 is as Figure 1 shown; the gas chromatography-mass spectrometry chromatogram of the Antarctic krill oil obtained in Example 2 is as Figure 2As shown below. Chromatographic conditions: The chromatographic column is an HP-5MS capillary column (30 m × 0.25 mm × 0.25 μm); the column oven temperature is maintained at 50 °C for 5 min, then increased to 170 °C at a rate of 3 °C / min; then increased to 230 °C at a rate of 5 °C / min and maintained for 10 min; the injection port temperature is 250 °C; the carrier gas (He) flow rate is 0.8 mL / min, the desorption temperature is 250 °C, and injection is performed in splitless mode. Mass spectrometry conditions: The transfer line temperature is 280 °C, the ion source temperature is 230 °C, the quadrupole temperature is 150 °C, the scanning range is m / z 35 - 500, and the ionization voltage is 70 eV.

[0105] Ten people with certain sensory evaluation experience were selected to form an evaluation group to conduct a sensory evaluation of the fishy smell of the krill oil samples obtained in each case. The scoring ranged from 0 to 10 points, with a higher score indicating a stronger fishy smell, and finally the average value was obtained. Table 1 shows the extraction rate, phospholipid content, fishy smell score, and the content of four main ester fishy smell substances of the krill oil in each case, where the extraction rate = (weight of Antarctic krill oil / weight of Antarctic krill powder) × 100%. It can be seen from the table that the deodorization method has basically no effect on the extraction rate and phospholipid content of Antarctic krill oil. The fishy smell scores of the krill oil in each comparative example were all ≥ 8 points, indicating a very strong fishy smell. The fishy smell scores of the krill oil in each example were all ≤ 2 points, indicating a relatively light fishy smell. The removal rates of the four main macromolecular ester fishy smell substances in Examples 1 - 5 all reached over 85%.

[0106] The calculation formula for the removal rate of the main ester fishy smell substances in Table 1 compared with Comparative Example 1 is: (A - B) / A; where A is the content of the main ester fishy smell substances in Comparative Example 1; B is the content of the main ester fishy smell substances in the other comparative examples or examples.

[0107] Table 1 Comparison of the extraction rate, fishy smell score, and removal rate of the main ester fishy smell substances of the krill oil in each case

[0108]

[0109]

[0110] As can be seen from Table 1, the present invention uses the precise retention of the trehalose-modified nanofiltration membrane combined with the auxiliary washing effect of the weak acid salt to efficiently remove the ester fishy smell substances in the krill oil, and the removal rate of the four main ester fishy smell substances reaches over 85%. Moreover, the operation of the present invention is simple and easy to control, avoiding the addition of harmful chemical reagents, and ensuring the naturalness and safety of Antarctic krill oil.

[0111] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can still be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for extracting deodorized Antarctic krill oil, characterized in that: The following steps are involved: S1) extracting Antarctic krill powder with ethanol-water solution to obtain an extract; S2) subjecting the extract to nanofiltration treatment to obtain a retentate; the nanofiltration membrane used for the nanofiltration treatment comprises a basement membrane; the surface of the basement membrane is grafted with trehalose; the pressure of the nanofiltration treatment is 10-20 bar; S3) concentrating the retentate to obtain a concentrate; S4) mixing the concentrated solution with a NaH2PO4 aqueous solution, and settling to obtain a precipitate phase; the mass concentration of the NaH2PO4 aqueous solution is 0.5% to 3%; S5) mixing the precipitate phase with ethanol and concentrating the mixture to obtain the deodorized Antarctic krill oil; The nanofiltration membrane is prepared according to the following method: The basement membrane is immersed in a trehalose aqueous solution and then heat-treated to obtain a nanofiltration membrane; the surface of the basement membrane has a carboxyl functional group; The density of the carboxyl functional groups in the base film is 0.8 mmol / g to 1.3 mmol / g; The molecular weight cut-off of the basement membrane is 300-800 Daltons; The mass concentration of trehalose in the trehalose aqueous solution is 10% to 20%.

2. The extraction method according to claim 1, characterized in that The soaking time is 1 to 5 hours; The temperature of the heat treatment is 50°C to 70°C; the time of the heat treatment is 5 to 15 min.

3. The extraction method according to claim 1, characterized in that The mass concentration of ethanol in the ethanol aqueous solution in step S1) is 90% to 98%; The mass volume ratio of the Antarctic krill powder to the ethanol aqueous solution is 1 g: (5-10) mL; The extraction time is 1 to 5 h.

4. The extraction method according to claim 1, characterized in that The volume of the concentrated solution in step S3) is 1 / 3 to 1 / 7 of the volume of the retentate solution.

5. The extraction method according to claim 1, characterized in that The volume ratio of the concentrated solution to the NaH2PO4 aqueous solution is 1:(1-3); The sedimentation time is 6 to 15 hours.

6. The extraction method according to claim 1, characterized in that The mass volume ratio of the precipitate phase to ethanol is 1 g: (1-3) mL.

7. The deodorized Antarctic krill oil obtained by the extraction method according to any one of claims 1 to 6, characterized in that: The content of ethyl palmitate in the deodorized Antarctic krill oil is less than 1 mg / g; the content of 2-dimethylaminoethyl 3-cyclopentylpropionate in the deodorized Antarctic krill oil is less than 2 mg / g; the content of 5,8,11,14,17-eicosapentaenoic acid methyl ester in the deodorized Antarctic krill oil is less than 2 mg / g; the content of 3,6,9,12,15-eicosapentaenoic acid ethyl ester in the deodorized Antarctic krill oil is less than 1 mg / g.

8. A food comprising the deodorized Antarctic krill oil extracted by the extraction method according to any one of claims 1 to 6 or the deodorized Antarctic krill oil according to claim 7.

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