Deodorized euphausia superba oil and extraction method thereof

Abstract

The invention belongs to the technical field of food, and particularly relates to deodorized euphausia superba oil and an extraction method thereof. Compared with the prior art, the method has the advantages that fishy smell removal treatment is performed through modified nanofiltration membrane treatment and a refining process, so that the extraction rate of the euphausia superba oil is ensured while the fishy smell of the euphausia superba oil is reduced. And meanwhile, the method is simple in process and low in cost, the problems of low product extraction rate, poor deodorization effect, harsh preparation conditions and high cost caused by the existing deodorization technology are solved, and the acceptability and the use experience of consumers are improved as a functional food.

Description

Technical Field

[0001] The invention belongs to the technical field of food, and in particular relates to 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, and astaxanthin. A large number of studies have shown that Antarctic krill oil, as a functional food, has significant effects in improving cardiovascular health, preventing brain neurodegenerative diseases, protecting the liver and bones and joints, etc. However, the Antarctic krill oil products currently on the market generally have a certain fishy smell, which greatly affects consumers' acceptance and usage experience. The fishy 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] At present, there are few studies on the deodorization of Antarctic krill oil. The existing deodorization technologies mainly include adsorption method, embedding method, microbial fermentation method, enzymatic method, plant deodorizers, etc. However, these methods often have limitations. Commonly used adsorbents include activated carbon, kaolin, alumina, etc., which have poor adsorption selectivity. While adsorbing fishy substances, they also adsorb some other substances that are important for product nutrition, reducing the krill oil extraction rate. The embedding method is difficult to achieve complete embedding of fishy substances, and the deodorization effect is poor. The fermentation conditions for deodorization by microbial fermentation are extremely harsh, and strict control of temperature, Ph value, dissolved oxygen content, etc. is required. If the conditions are slightly unsuitable, the growth and metabolism of microorganisms will be inhibited, thereby affecting the deodorization effect. The activity of enzymes during enzymatic deodorization is also affected by many factors such as temperature, pH value, substrate concentration, etc. If it deviates from the optimal range, the activity of the enzyme will be reduced or even inactivated, thus affecting the deodorization effect. At the same time, some side reactions may occur during the enzymatic hydrolysis process, generating new odor substances, such as excessive protein decomposition to produce bitter peptides, which affect the overall flavor of the product. The high cost of enzyme preparations affects the economic benefits of the product. Plant-based deodorizers include spices, tea, perilla, onion, ginger, garlic, etc. Most of these deodorizers cover up the fishy smell through their own unique smell and taste. As time goes by, the fishy smell in the product may become prominent again.

[0004] The Chinese patent application number 201810078300.X discloses a method for preparing high-quality Antarctic krill oil. In the preparation process, a multi-stage grinding and synergistic enzymatic hydrolysis method is used to remove the fishy smell of krill oil. However, the types and amounts of fishy substances removed are not clear. The fishy smell is only judged by the blandness of the fishy smell, which is subjective. The Chinese patent application number 201810842218.X discloses a deamined low-smelling krill oil and a method for preparing it. In the krill oil preparation process, ion exchange resin and macroporous adsorption resin are used for adsorption and deodorization, which reduces the content of trimethylamine and trimethylamine oxide in krill oil. However, this method does not remove another major category of fishy 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 an extraction method thereof, wherein the extraction method reduces the fishy smell of the Antarctic krill oil while ensuring the extraction rate of the krill oil.

[0006] The present invention provides a method for extracting deodorized Antarctic krill oil, comprising the following steps:

[0007] S1) extracting Antarctic krill powder with ethanol-water solution to obtain an extract;

[0008] S2) subjecting the extract to nanofiltration to obtain a retentate; the nanofiltration membrane used in the nanofiltration process comprises a basement membrane; the surface of the basement membrane is grafted with trehalose;

[0009] S3) concentrating the retentate to obtain a concentrate;

[0010] S4) mixing the concentrated solution with a NaH2PO4 aqueous solution and settling to obtain a precipitate phase;

[0011] S5) mixing the precipitate phase with ethanol and concentrating the mixture to obtain the deodorized Antarctic krill oil.

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

[0013] The basement membrane is immersed in a trehalose aqueous solution and then heat-treated to obtain a nanofiltration membrane.

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

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

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

[0017] The mass concentration of trehalose in the trehalose aqueous solution is 10% to 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, the mass concentration of ethanol in the ethanol aqueous solution in step S1) is 90% to 98%;

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

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

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

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

[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:(1-3);

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

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

[0029] The present invention also provides a deodorized Antarctic krill oil extracted by the above-mentioned extraction method, wherein 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.

[0030] The present invention also provides a food, comprising the above-mentioned 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 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; S3) concentrating the retentate to obtain a concentrated solution; S4) mixing the concentrated solution with an aqueous solution of NaH2PO4, settling, and obtaining a precipitate phase; S5) mixing the precipitate phase with ethanol, concentrating, and obtaining deodorized Antarctic krill oil. Compared with the prior art, the present invention performs deodorization treatment by modified nanofiltration membrane treatment and refining process, reduces the fishy smell of Antarctic krill oil, and ensures the extraction rate of krill oil. At the same time, the method has a simple process and low cost, solves the problems of reduced product extraction rate, poor deodorization effect, harsh preparation conditions and high cost caused by the existing deodorization technology, and improves consumer acceptance and use experience as a functional food. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0034] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0035] The invention provides a method for extracting deodorized Antarctic krill oil, comprising the following steps: S1) extracting Antarctic krill powder with an 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; trehalose is grafted on the surface of the basement membrane; S3) concentrating the retentate to obtain a concentrated solution; S4) mixing the concentrated solution with an aqueous NaH2PO4 solution, settling, and obtaining a precipitate phase; S5) mixing the precipitate phase with ethanol, and concentrating to obtain the deodorized Antarctic krill oil.

[0036] The present invention has no particular limitation on the sources of all raw materials, and any raw materials available on the market can be used.

[0037] Antarctic krill powder is extracted with ethanol-water solution to obtain an extract; the mass concentration of ethanol in the ethanol-water solution is preferably 90%-98%, more preferably 93%-97%, and more preferably 95%-97%; the mass volume ratio of the Antarctic krill powder to the ethanol-water solution is preferably 1 g: (5-10) mL, more preferably 1 g: (6-10) mL, 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, more preferably 2-3 h, and most preferably 2.5 h.

[0038] The extract is subjected to nanofiltration treatment to obtain a retentate; the nanofiltration membrane used for the nanofiltration treatment includes a basement membrane; the surface of the basement membrane preferably has carboxyl functional groups; the hydroxyl groups on the trehalose can be grafted onto the surface of the basement membrane by reacting with the carboxyl functional groups on the surface of the basement membrane; the density of the carboxyl functional groups in the basement membrane is preferably between 0.8 mmol / g and 1.3 mmol / g; optionally, the density of the carboxyl functional groups in the basement 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 a range between any two of the above values; the basement membrane is preferably an organic polymer nanofiltration membrane; the molecular weight cutoff of the basement membrane is preferably 300-800 Daltons, more preferably 400-600 Daltons, and more preferably 500 Daltons; the pressure of the nanofiltration treatment is preferably 10-20 bar, more preferably 13-18 baor, 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 according to the following method: the basement membrane is immersed in a trehalose aqueous solution and then heat-treated 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 a range between any two of the above values; the immersion treatment time is preferably 1~5 h, more preferably 1~4 h, more preferably 2~3 h, and most preferably 2 h; after the immersion treatment, it is preferred to remove and drain excess solution, and then heat-treat; the heat treatment temperature is preferably 50℃~70℃, more preferably 55℃~65℃, and more preferably 60℃; the heat treatment time is preferably 5~15 min, more preferably 8~12 min, and more preferably 10 min.

[0040] The retentate is concentrated 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 even more preferably 1 / 5 of the volume of the retentate.

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

[0042] The precipitate phase is mixed with ethanol and concentrated to obtain deodorized Antarctic krill oil; the mass 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 even more preferably 1 g: 2 mL; the concentration is preferably reduced pressure concentration.

[0043] The present invention uses modified nanofiltration membrane treatment and refining process to remove the fishy smell of Antarctic krill oil, while ensuring the extraction rate of krill oil. At the same time, the method is simple in process and low in cost, and solves the problems of reduced product extraction rate, poor fishy smell removal effect, harsh preparation conditions and high cost caused by existing fishy smell removal technology. As a functional food, it improves consumer acceptance and usage experience.

[0044] The present invention also provides a deodorized Antarctic krill oil extracted by the above-mentioned extraction method, wherein 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.

[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, even 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-dimethylaminoethyl 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 5,8,11,14,17-eicosapentaenoic acid methyl ester 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 3,6,9,12,15-eicosapentaenoic acid ethyl ester in the deodorized Antarctic krill oil is preferably less than 0.8 mg / g, more preferably less than 0.7 mg / g, even 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] In order to further illustrate the present invention, the deodorized Antarctic krill oil and the extraction method thereof provided by the present invention are described in detail below in conjunction with examples.

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

[0052] Comparative Example 1: In the preparation process of Antarctic krill oil in this comparative example, no nanofiltration membrane treatment was performed and only pure water washing was performed to remove impurities.

[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, centrifuge to remove the residue and obtain 3000 mL of extract.

[0054] 1.2 The extract was concentrated under reduced pressure to 600 mL, 1200 mL of pure water was added, the mixture was mixed and stirred for washing and impurity removal, and then settled overnight.

[0055] 1.3 Take 73 g of the precipitate phase after sedimentation, add 146 mL of anhydrous ethanol, stir and mix well, 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 the Antarctic krill oil in this comparative example, no nanofiltration membrane treatment was performed and only 1% NaH2PO4 solution was used for washing and impurity removal.

[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, centrifuge to remove the residue and obtain 3000 mL of extract.

[0058] 2.2 The extract was concentrated under reduced pressure to 600 mL, 1200 mL of 1% NaH2PO4 solution was added, the mixture was mixed and stirred for washing and impurity removal, and then settled overnight.

[0059] 2.3 Take 72 g of the precipitate phase after sedimentation, add 144 mL of anhydrous ethanol, stir and mix well, 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 ordinary 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, centrifuge to remove the residue and obtain 3000 mL of extract.

[0062] 3.2 The extract was treated with an organic polymer nanofiltration membrane with a surface carboxyl functional group (density: 0.8 mmol / g~1.3 mmol / g) and a molecular weight cutoff of 500 Daltons. The pressure was selected to be 15 bar, and 2100 mL of the retentate was obtained.

[0063] 3.3 The intercepted liquid was concentrated under reduced pressure to 420 mL, 840 mL of 1% NaH2PO4 solution was added, mixed and stirred for washing and impurity removal, and then settled overnight.

[0064] 3.4 Take 75 g of the precipitate phase after sedimentation, add 150 mL of anhydrous ethanol, stir and mix well, and then continue to reduce pressure and concentrate to obtain 69 g of Antarctic krill oil.

[0065] Comparative Example 4: In the preparation process of Antarctic krill oil in this comparative example, the oil 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, centrifuge to remove the residue and obtain 3000 mL of extract.

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

[0068] 4.3 The intercepted liquid was concentrated under reduced pressure to 420 mL, 840 mL of 1% NaH2PO4 solution was added, mixed and stirred for washing and impurity removal, and then settled overnight.

[0069] 4.4 Take 71 g of the precipitate phase after sedimentation, add 142 mL of anhydrous ethanol, stir and mix well, 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 carboxyl functional groups (density: 0.8 mmol / g~1.3mmol / g) on ​​the surface and a molecular weight cutoff of 500 Dalton as the base membrane, rinse it with deionized water and dry it naturally; ② Soak the dried filter membrane in a 15% lactose aqueous solution for 2 hours, take out the filter membrane and drain the excess solution. ③ Place the drained filter membrane in a 60℃ oven for heat treatment for 5 minutes to obtain a lactose modified nanofiltration membrane.

[0071] Comparative Example 5: In the preparation process of Antarctic krill oil in this comparative example, trehalose-modified nanofiltration membrane treatment and pure water washing were used 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, centrifuge to remove the residue and obtain 3000 mL of extract.

[0073] 5.2 The extract was treated with a trehalose-modified nanofiltration membrane, the pressure was selected to be 15 bar, and 2100 mL of the retentate was obtained.

[0074] 5.3 The retentate was concentrated under reduced pressure to 420 mL, 840 mL of pure water was added, the mixture was mixed and stirred for washing and impurity removal, and then settled overnight.

[0075] 5.4 Take 72 g of the precipitate phase after sedimentation, add 144 mL of anhydrous ethanol, stir and mix well, 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, centrifuge to remove the residue and obtain 3000 mL of extract.

[0078] 1.2 The extract was treated with a nanofiltration membrane modified with 10% trehalose, the pressure was selected to be 15 bar, and 2100 mL of the retentate was obtained.

[0079] 1.3 The retentate was concentrated under reduced pressure to 420 mL, 840 mL of 1% NaH2PO4 solution was added, the mixture was mixed and stirred for washing and impurity removal, and then settled overnight.

[0080] 1.4 Take 72 g of the precipitate phase after sedimentation, add 144 mL of anhydrous ethanol, stir and mix well, and then continue to reduce pressure and concentrate 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 carboxyl functional groups (density: 0.8 mmol / g~1.3 mmol / g) on ​​the surface and a molecular weight cutoff of 500 Dalton as the base membrane, rinse it with deionized water and dry it naturally; ② Soak the dried filter membrane in a 10% mass fraction trehalose aqueous solution for 2 h, remove the filter membrane and drain the excess solution. ③ Place the drained filter membrane in a 60℃ oven 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, centrifuge to remove the residue and obtain 3000 mL of extract.

[0084] 2.2 The extract was treated with a nanofiltration membrane modified with 15% trehalose, and the pressure was selected to be 15 bar to obtain 2100 mL of retentate.

[0085] 2.3 The retentate was concentrated under reduced pressure to 420 mL, 840 mL of 1% NaH2PO4 solution was added, the mixture was mixed and stirred for washing and impurity removal, and then settled overnight.

[0086] 2.4 Take 74 g of the precipitate phase after sedimentation, add 148 mL of anhydrous ethanol, stir and mix well, and then continue to reduce pressure and concentrate 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 by 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, centrifuge to remove the residue and obtain 3000 mL of extract.

[0090] 3.2 The extract was treated with a nanofiltration membrane modified with 20% trehalose, and the pressure was selected to be 15 bar to obtain 2100 mL of retentate.

[0091] 3.3 The retentate was concentrated under reduced pressure to 420 mL, 840 mL of 1% NaH2PO4 solution was added, the mixture was mixed and stirred for washing and impurity removal, and then settled overnight.

[0092] 3.4 Take 75 g of the precipitate phase after sedimentation, add 150 mL of anhydrous ethanol, stir and mix well, and then continue to reduce pressure and concentrate 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 by 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, centrifuge to remove the residue and obtain 3000 mL of extract.

[0096] 4.2 The extract was treated with a nanofiltration membrane modified with 15% trehalose, and the pressure was selected to be 15 bar to obtain 2100 mL of retentate.

[0097] 4.3 The retentate was concentrated under reduced pressure to 420 mL, 840 mL of 0.5% NaH2PO4 solution was added, the mixture was mixed and stirred for washing and impurity removal, and then settled overnight.

[0098] 4.4 Take 71 g of the precipitate phase after sedimentation, add 142 mL of anhydrous ethanol, stir and mix well, and then continue to reduce pressure and concentrate 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, centrifuge to remove the residue and obtain 3000 mL of extract.

[0101] 5.2 The extract was treated with a nanofiltration membrane modified with 15% trehalose, and the pressure was selected to be 15 bar, and 2100 mL of the retentate was obtained.

[0102] 5.3 The retentate was concentrated to 420 mL under reduced pressure, 840 mL of 2% NaH2PO4 solution was added, the mixture was mixed and stirred for washing and impurity removal, and then settled overnight.

[0103] 5.4 Take 73 g of the precipitate phase after sedimentation, add 146 mL of anhydrous ethanol, stir and mix well, and then continue to reduce pressure and concentrate to obtain 68 g of Antarctic krill oil.

[0104] The Antarctic krill oil obtained in Comparative Examples 1 to 5 and Examples 1 to 5 was analyzed by gas chromatography-mass spectrometry, and the components in the Antarctic krill oil were shown in Table 1; the gas chromatography-mass spectrometry chromatogram of the Antarctic krill oil obtained in Comparative Example 1 was shown in Figure 1 As shown; the gas chromatography-mass spectrometry chromatogram of the Antarctic krill oil obtained in Example 2 is as follows Figure 2As shown. Chromatographic conditions: the chromatographic column is a HP-5MS capillary column (30m×0.25mm×0.25μm); the column oven temperature is 50℃ for 5min, 3℃ / min to 170℃; 5℃ / min to 230℃ for 10min; the injection port temperature is 250℃; the carrier gas (He) flow rate is 0.8 mL / min, the desorption temperature is 250℃, and the injection mode is splitless. Mass spectrometry conditions: transmission line temperature is 280℃, ion source temperature is 230℃, quadrupole temperature is 150℃, scanning range is m / z35-500, and ionization voltage is 70eV.

[0105] An evaluation team consisting of 10 people with certain sensory evaluation experience was selected to conduct a sensory evaluation of the fishy smell of the krill oil samples obtained in each case. The scores ranged from 0 to 10, with the higher the score, the heavier the fishy smell, and the average value was finally calculated. Table 1 shows the krill oil extraction rate, phospholipid content, fishy smell score and the content of four main ester fishy substances in each case, where the extraction rate = Antarctic krill oil weight / Antarctic krill powder weight × 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 score of krill oil in each comparative example is ≥8 points, and the fishy smell is very strong. The fishy smell score of krill oil in each embodiment is ≤2 points, and the fishy smell is relatively light. The removal rate of the four main macromolecular ester fishy substances in Examples 1 to 5 all reached more than 85%.

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

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

[0108] As shown in Table 1, the present invention utilizes the precise interception of the trehalose modified nanofiltration membrane combined with the auxiliary washing effect of the weak acid salt to efficiently remove the ester odor substances in the krill oil, and the removal rate of the four main ester odor substances is more than 85%. In addition, the present invention is simple to operate, easy to control, avoids the addition of harmful chemical reagents, and ensures the naturalness and safety of Antarctic krill oil.

[0109] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection 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 to obtain a retentate; the nanofiltration membrane used in the nanofiltration process comprises a basement membrane; the surface of the basement membrane is grafted with trehalose; 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; S5) mixing the precipitate phase with ethanol and concentrating the mixture to obtain the deodorized Antarctic krill oil.

2. The extraction method according to claim 1, characterized in that 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%.

3. The extraction method according to claim 2, 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.

4. 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.

5. The extraction method according to claim 1, characterized in that The pressure of the nanofiltration treatment is 10-20 bar.

6. 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.

7. The extraction method according to claim 1, characterized in that The mass concentration of the NaH2PO4 aqueous solution is 0.5% to 3%; The volume ratio of the concentrated solution to the NaH2PO4 aqueous solution is 1:(1-3); The sedimentation time is 6 to 15 hours.

8. 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.

9. The deodorized Antarctic krill oil obtained by the extraction method according to any one of claims 1 to 8, 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.

10. A food comprising the deodorized Antarctic krill oil extracted by the extraction method according to any one of claims 1 to 8 or the deodorized Antarctic krill oil according to claim 9.

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