Method for preparing black soldier fly oil from fresh black soldier fly larvae

Abstract

The present invention discloses a method for preparing black soldier fly oil from fresh black soldier fly larvae, which includes adding citric acid to the fresh black soldier fly larvae and pulverizing to obtain a fresh insect slurry, or adding a citric acid solution to the fresh black soldier fly larvae for treatment to obtain a fresh insect slurry; adding an extraction solvent to the fresh insect slurry for extraction to obtain a three-phase mixture, subjecting the three-phase mixture to solid-liquid separation and oil-water separation to obtain a mixed oil phase, removing the extraction solvent in the mixed oil phase, and removing residues and impurities to obtain fresh black soldier fly larvae oil. The present invention uses citric acid to treat fresh black soldier fly larvae. The acidic environment provided by citric acid is conducive to the separation of some lipids from proteins and carbohydrates in biological cells. It can not only protect the active substances (such as proteins) in fresh black soldier fly larvae, improve the protein quality, but also increase the oil extraction rate (up to more than 90%); the chelating effect of citric acid reduces the catalytic activity of enzymes, thereby effectively inhibiting browning involving enzymes, making the extracted oil lighter in color and improving the quality of black soldier fly oil.

Description

Technical Field

[0001] The present invention relates to the preparation of black soldier fly oil, and in particular to a method for preparing black soldier fly oil using fresh black soldier fly larvae as raw materials. Background Art

[0002] The black soldier fly (Hermetia illucens), scientific name Hermetia illucens Hermetia illucens L. ), is an insect of the order Diptera and the family Stratiomyidae, living a saprophytic life, and can convert huge amounts of organic waste into high-value-added biological substances. The biomass of black soldier fly larvae is rich in protein, lipid and trace elements. Its biomass contains 29.26% - 45.10% crude protein and 32.40% - 54.88% crude fat, and has high feeding value. As one of the main components in the body of black soldier fly larvae, saturated fatty acids are mainly lauric acid and palmitic acid, with contents of 25.34% and 16.17% respectively, and polyunsaturated fatty acids are mainly linoleic acid, reaching 27.25%. Therefore, using the nutrients of black soldier flies to carry out deep processing and utilization of black soldier flies, such as preparing black soldier fly oil using black soldier flies, has good economic and social benefits for reflecting the added value of this resource-based insect.

[0003] The extraction of black soldier fly oil is divided into two categories according to raw materials: dry insect extraction and fresh insect extraction. For dry insect extraction, various extraction methods such as pressing method and extraction method are mostly used. Among them, the extraction method is widely used due to its low cost and high extraction rate, but the disadvantage is that it requires a large amount of heat energy to dry the raw materials, takes a long time, and destroys the active nutrients (especially proteins) in the insect body.

[0004] At present, there are few studies on extracting oil using fresh insects. Chinese Patent CN115109641A discloses a method for separating and extracting fly protein and oil, but in the extraction process of this method, enzyme preparations need to be added for enzymatic hydrolysis, the cost of the enzyme is high and the oil yield is low (only 78%). Weiliang Feng, Xiong Huan, etc. used fresh black soldier fly larvae as raw materials and prepared black soldier fly oil by homogenization method: directly mixing an organic extraction solvent with the insect body and performing high-speed homogenization for 1 minute, then separating and purifying to obtain black soldier fly oil. Although this method is simple and has low energy consumption, when directly performing high-speed homogenization of the solvent, it is easy to form a solvent vortex, the solvent is easy to volatilize, the risk factor is high, the requirements for production equipment are high, it is difficult to achieve large-scale production, and the oil extraction rate is only 75.92%. Summary of the Invention

[0005] The object of the present invention is to provide a method for preparing black soldier fly oil from fresh black soldier fly larvae, which can not only protect the bioactive substances (such as proteins) in the black soldier fly larvae for the fine processing of the larval proteins, but also improve the oil extraction rate of fresh black soldier fly larvae (up to 95%) on the premise of ensuring the quality of black soldier fly oil, and is also convenient for industrial production, having good economic and social benefits.

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

[0007] The method for preparing black soldier fly oil from fresh black soldier fly larvae according to the present invention includes the following steps:

[0008] S1. Add solid citric acid to fresh black soldier fly larvae and crush to obtain fresh insect slurry, or add a citric acid solution to fresh black soldier fly larvae for treatment to obtain fresh insect slurry. The concentration of the citric acid solution is 3.0% - 6.0%, and the ratio of fresh black soldier fly larvae to the citric acid solution is 1g:1.0ml - 1g:2.0ml;

[0009] S2. Add the treated fresh insect slurry to an extraction solvent, and the material-liquid ratio of the fresh insect slurry to the extraction solvent is ≥1g:3ml; perform low-temperature extraction at 30 - 70°C for 2 - 5 times to obtain a three-phase mixture of a solid phase, an aqueous phase, and a mixed oil phase;

[0010] S3. Perform solid-liquid separation on the three-phase mixture obtained in step S2, and then perform oil-water separation to obtain a mixed oil phase of the extraction solvent and fresh black soldier fly larvae oil;

[0011] S4. Remove the extraction solvent from the mixed oil phase to obtain a crude extract of fresh black soldier fly larvae oil;

[0012] S5. After subjecting the crude extract of fresh black soldier fly larvae oil to residue removal and impurity removal, obtain fresh black soldier fly larvae oil.

[0013] The present invention uses citric acid to treat fresh black soldier fly larvae. The acidic environment provided by citric acid is beneficial to the separation of some lipids from proteins and carbohydrates in biological cells during the subsequent extraction process, improving the oil extraction rate (the oil extraction rate is above 90%, even up to 95%) and protecting the proteins in the crude protein of fresh black soldier fly larvae, improving the protein quality; citric acid can also chelate Cu 2＋ 、Mg 2＋ 、Fe 2＋Polyvalent metal ions, which are usually cofactors for the action of enzymes. The chelating effect of citric acid can effectively reduce the catalytic activity of enzymes, thereby effectively inhibiting browning involving enzymes, making the extracted oil lighter in color and improving the quality of black soldier fly oil. Additionally, the high shear force provided by high-pressure homogenization and the high-intensity centrifugal action further adopted in the present invention can fully break the cells of fresh black soldier fly larvae, facilitating the release of fat, increasing the contact area between fat and the solvent, and further improving the oil extraction rate.

[0014] In a more preferred embodiment of the present invention, in step S1, adding a citric acid solution to fresh black soldier fly larvae to obtain a fresh insect slurry specifically is: adding a citric acid solution to fresh black soldier fly larvae at a material-liquid ratio of 1 g:1.0 ml to 1 g:2.0 ml, performing high-pressure homogenization at room temperature, with the high-pressure homogenization speed ≥ 8000 r / min, to obtain a fresh insect slurry. The high shear force provided by high-pressure homogenization and the high-intensity centrifugal action can fully break the cells of fresh black soldier fly larvae, facilitating the release of fat, increasing the contact area between fat and the solvent, and further improving the oil extraction rate.

[0015] In a preferred embodiment of the present invention, the extraction solvent used in step S2 includes any one or a combination of two or more of n-hexane, vegetable oil extraction solvent, petroleum ether, or isopropyl ether.

[0016] More preferably, the extraction solvent used in step S2 is a vegetable oil extraction solvent or petroleum ether with a boiling range of 60°C to 90°C, and the material-liquid ratio of the fresh insect slurry to the extraction solvent is 1 g:3.5 ml to 1 g:7.0 ml. More preferably, the material-liquid ratio of the fresh insect slurry to the extraction solvent is 1 g:5.0 ml.

[0017] In a preferred embodiment of the present invention, the temperature for low-temperature extraction in step S2 is 30°C to 70°C, and the extraction time is 0.5 h to 2.0 h. More preferably, the extraction temperature is controlled at 40 - 60°C.

[0018] In a preferred embodiment of the present invention, in step S4, removing the extraction solvent from the mixed oil phase includes the following: evaporating and recovering the organic solvent in the oil phase under the conditions of 45~65°C and -0.045 MPa~ -0.095 MPa. In actual production, a recovery pot, thin-film evaporator, or molecular distillation technology can be used to remove the extraction solvent from the oil phase to obtain the crude oil of fresh black soldier fly larvae.

[0019] Compared with the prior art, the present invention uses citric acid to treat fresh black soldier fly larvae. The acidic environment provided by citric acid is beneficial to the separation of some lipids from proteins and carbohydrates in biological cells during the subsequent leaching process, improving the oil extraction rate and protecting the proteins in the crude protein of fresh black soldier fly larvae, and improving the protein quality; citric acid can also chelate Cu 2＋, Mg 2＋ , Fe 2＋ Polyvalent metal ions, which are usually cofactors for the action of enzymes. The chelation of citric acid can effectively reduce the catalytic activity of enzymes, thereby effectively inhibiting browning involving enzymes, making the extracted oil lighter in color and improving the quality of black soldier fly oil. In addition, the high shear force provided by high-pressure homogenization and the high-intensity centrifugal action further adopted in the present invention can fully break the cells of fresh black soldier fly larvae, facilitating the release of fat, increasing the contact area between fat and the solvent, and further improving the oil extraction rate.

[0020] The present invention uses fresh black soldier fly larvae as raw materials for oil extraction. Through reasonable treatment with fresh larvae, fresh larval slurry is obtained, and by optimizing the extraction process parameters of the fresh larval slurry, the oil extraction rate from fresh black soldier fly larvae is increased to over 90% (even up to 95%), overcoming the technical problem of low oil extraction rate from existing fresh black soldier fly larvae. The obtained black soldier fly oil has excellent quality, low peroxide value, light color and faint odor, which is beneficial to the preparation of deep-processed products such as microcapsule powder in the later stage; in addition, the extraction process of the present invention is relatively mild, with a high oil extraction rate, and can be produced on an industrial scale; furthermore, the present invention can also protect active substances such as insect body proteins from being damaged while ensuring the quality of the oil, which is beneficial to the deep processing of insect body proteins and is of great significance for improving the quality of deep-processed products of insect body proteins.

[0021] The oil extraction process of the present invention is safe and reasonable, has low requirements for equipment, and conventional equipment can meet the production requirements, which is conducive to large-scale production; compared with dry insect extraction, the larval drying step is omitted, which not only reduces the production cost but also avoids the inactivation of natural active ingredients caused by larval drying extraction. In addition, during actual production, the organic solvent recovered after each extraction can be reused, reducing the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is the process route diagram of the preparation method of the present invention.

[0023] Figure 2 is the fresh black soldier fly larva oil extracted with vegetable oil extraction solvent as the extraction solvent in Example 4.

[0024] Figure 3 is the fresh black soldier fly larva oil extracted with petroleum ether as the extraction solvent in Example 2.

[0025] Figure 4 is the state diagram of the fresh black soldier fly larva oil in Example 2 after degumming and alkali refining and drying treatment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] The fresh black soldier fly larvae raw materials used in the present invention are selected from commercially available 5th instar fresh larvae (purchased from Henan Zhongda Fly Source Biotechnology Co., Ltd.) or frozen fresh larvae, and the larvae should be kept clean and not browned. It should be noted that the petroleum ether used in the following examples refers to petroleum ether with a boiling range of 60-90 °C unless otherwise specified.

[0027] The present invention provides a method for preparing black soldier fly oil from fresh black soldier fly larvae. The method is to directly crush the fresh black soldier fly larvae by adding citric acid to obtain a fresh insect slurry, or to homogenize and crush the fresh black soldier fly larvae by adding a citric acid solution, which can not only ensure the extraction rate of the fresh black soldier fly larvae oil, but also ensure the quality of the fresh black soldier fly larvae oil, facilitate subsequent deep processing such as microcapsule powder, protect the protein of the fresh black soldier fly larvae from being damaged, improve the quality of the fresh black soldier fly larvae protein, and contribute to the deep processing of the fresh black soldier fly larvae protein.

[0028] The method for preparing black soldier fly oil from fresh black soldier fly larvae according to the present invention has a process route as Figure 1 shown, and the specific steps include:

[0029] S1. Add a citric acid solution (prepared from soft water and anhydrous citric acid) to the purchased clean and non-browned 5th instar fresh black soldier fly larvae at a ratio of 1 g:1 ml to 1 g:2 ml for homogenization and crushing to obtain a fresh black soldier fly larvae slurry; the mass concentration of the citric acid solution is controlled at 3.0% - 6.0% (preferably 3.5% - 5.5%);

[0030] Alternatively, add anhydrous citric acid to the above fresh black soldier fly larvae at a mass ratio of 1 g:0.05 g (i.e., add 50 g of citric acid to 1000 g of fresh black soldier fly larvae), and then directly crush to obtain a fresh black soldier fly larvae slurry;

[0031] S2. Add the treated fresh insect slurry to an extraction solvent and perform low-temperature extraction 2 - 5 times at 20 °C - 70 °C, with each extraction time being 45 min - 120 min, to obtain a three-phase mixture of insect residue, aqueous phase, and mixed oil solution;

[0032] Among them, the extraction solvent is n-hexane, vegetable oil extraction solvent, petroleum ether, or isopropyl ether, and the extraction solvent is preferably a vegetable oil extraction solvent or petroleum ether. The material-liquid ratio of the fresh insect slurry to the extraction solvent is 1 g:3 ml - 1 g:7 ml (preferably 1 g:3.5 ml - 1 g:6.0 ml); the extraction time is 0.5 h - 2.0 h, preferably 40 min - 90 min, more preferably 60 min; the extraction temperature is preferably 30 °C - 65 °C, more preferably 40 °C - 50 °C; the extraction times are preferably 2 - 3 times, more preferably 2 times;

[0033] S3. Centrifuge the three-phase mixture obtained in step S2, and then separate the oil phase and the water phase using an oil-water separator to obtain a mixed oil phase of the extraction solvent and the grease.

[0034] S4. Remove the extraction solvent from the mixed oil phase and recover it (the recovered extraction solvent can be reused to reduce production costs) under the conditions of 45~65°C and -0.045 MPa~-0.095 MPa to obtain a crude extract of fresh black soldier fly larvae oil. Among them, when removing the extraction solvent, a recovery pot, a thin-film evaporator or molecular distillation technology can be used, etc.

[0035] S5. After removing residues and impurities from the crude extract of fresh black soldier fly larvae oil, obtain the finished product of fresh black soldier fly larvae oil.

[0036] Among them, when actually removing residues, it is preferably to remove residues by filling with nitrogen, and the temperature for removing residues is controlled at 60~65°C, and nitrogen is used to carry away the residual extraction solvent in the crude extract of fresh black soldier fly larvae oil; a bag filter is used for impurity removal.

[0037] The present invention will be described in more detail through specific examples below for the understanding of those skilled in the art. It should be noted that in the following examples, the oil extraction rate of fresh black soldier fly larvae is calculated by a conventional method, and the calculation formula of the oil extraction rate is as follows:

[0038]

[0039] In the formula, the water content of fresh insects is determined by the direct drying method in GB 5009.3-2016; the crude fat content of dried insects is determined by the Soxhlet extraction method in GB 5009.6-2016 with the dried fresh insects as raw materials.

[0040] During calculation, the weight of fresh insects, the crude fat content of dried insects and the water content of fresh insects are known parameters, and the oil extraction rate can be calculated according to the weight of the obtained finished product of fresh black soldier fly larvae oil.

[0041] Example 1 This example uses the direct citric acid crushing method to process fresh black soldier fly larvae

[0042] S1. Add 10 g of anhydrous citric acid to 200 g of 5th-instar fresh black soldier fly larvae and crush them to obtain a fresh black soldier fly larvae slurry (hereinafter referred to as "fresh insect slurry").

[0043] S2. Add the processed fresh insect slurry to petroleum ether, and the material-liquid ratio of the fresh insect slurry to petroleum ether is 1 g:5 ml. Extract twice at 50°C, and each extraction lasts for 60 min.

[0044] S3. Centrifuge the three-phase mixture obtained in step S2 to obtain an aqueous phase, a solid phase, and a mixed oil phase. Separate the oil phase and the aqueous phase using an oil-water separator to obtain a mixed oil phase of the extraction solvent and grease.

[0045] S4. Under the conditions of 45~65 °C and -0.045 MPa~-0.095 MPa, use a recovery pot to remove the extraction solvent from the mixed oil phase and recover it (the recovered extraction solvent can be used again) to obtain a crude extract of fresh black soldier fly larvae oil.

[0046] S5. Nitrogen-flush and remove residues from the crude extract of fresh black soldier fly larvae oil. Control the residue-removing temperature at 60~65 °C, use nitrogen to carry away the residual extraction solvent in the crude extract of fresh black soldier fly larvae oil, and filter it using a bag filter after residue removal.

[0047] Calculated, the grease extraction rate of fresh black soldier fly larvae in this example is 90.14%.

[0048] In this example, fresh black soldier fly larvae were treated with a citric acid solution to obtain a fresh black soldier fly larvae slurry. The acidic environment provided by the citric acid solution is beneficial to the separation of some lipids from proteins and carbohydrates in biological cells during the subsequent leaching process, improving the grease extraction rate and protecting the proteins in the crude protein of fresh black soldier fly larvae, and improving the protein quality. Citric acid can also chelate multivalent metal ions such as Cu 2＋ , Mg 2＋ , Fe 2＋ . These metal ions are usually cofactors for enzyme action. The chelating effect of citric acid can effectively reduce the catalytic activity of enzymes, thereby effectively inhibiting browning involving enzymes, making the extracted grease lighter in color and improving the quality of black soldier fly oil.

[0049] Example 2 In this example, fresh black soldier fly larvae were treated with a citric acid solution + high-pressure homogenization

[0050] S1. Add a 5% citric acid solution to 2000 g of 5th-instar fresh black soldier fly larvae at a ratio of 1 g:1 ml, and then perform high-pressure homogenization at room temperature with a high-pressure homogenization speed of 10,000 r / min to obtain a fresh black soldier fly larvae slurry (referred to as "fresh larvae slurry").

[0051] S2. Add the treated fresh larvae slurry to petroleum ether. The material-liquid ratio of the fresh larvae slurry to petroleum ether is 1 g:5 ml, and extract at 50 °C for 2 times, with each extraction for 60 min.

[0052] S3. Centrifuge the three-phase mixture obtained in step S2 to obtain an aqueous phase, a solid phase, and a mixed oil phase containing petroleum ether. Use an oil-water separator to separate the aqueous phase and the mixed oil phase to obtain a mixed oil phase.

[0053] S4. Under the conditions of 45 - 65 °C and -0.045 MPa to -0.095 MPa, use a recovery pot to remove the extraction solvent from the mixed oil phase and recover it (the recovered extraction solvent can be used again), obtaining a crude extract of fresh black soldier fly larvae oil;

[0054] S5. Nitrogen purge the crude extract of fresh black soldier fly larvae oil, control the degassing temperature at 60 - 65 °C, use nitrogen to carry away the residual extraction solvent in the crude extract of fresh black soldier fly larvae oil, and remove impurities using a centrifugal filter after degassing to obtain 168.74 g of finished fresh black soldier fly larvae oil.

[0055] After calculation, the extraction rate of fresh black soldier fly oil in this example is 95.35%.

[0056] Compared with Example 1, in this example, fresh black soldier fly larvae are treated with a citric acid solution + high-pressure homogenization. The shearing force and high-intensity centrifugal action provided by high-pressure homogenization can fully break the biological cells of fresh black soldier fly larvae, further improving the oil extraction rate of fresh black soldier fly larvae.

[0057] Example 3. In this example, fresh black soldier fly larvae are treated with lemon solutions of different concentrations

[0058] The difference between this example and Example 2 lies in the different concentrations of the citric acid aqueous solution. In this example, using fresh black soldier fly larvae as the raw material, the fresh black soldier fly larvae are divided into five groups, and citric acid solutions with concentrations of 3.5%, 4.0%, 4.5%, 5.0%, and 5.5% are added to the fresh black soldier fly larvae at a ratio of 1 g:1 ml, and then high-pressure homogenization is carried out. The oil extraction rates of the five groups of fresh black soldier fly larvae are shown in Table 1.

[0059] Table 1

[0060]

[0061] As can be seen from the table, when the mass concentration of the citric acid solution is in the range of 3.5% - 5.5%, the oil extraction rate of fresh black soldier fly larvae can reach more than 90%, and as the concentration increases, the oil extraction rate of fresh black soldier fly larvae gradually increases and then remains balanced. Therefore, the concentration of the citric acid solution in the present invention is controlled in the range of 3.5% - 5.5%, preferably controlled in the range of 4.0% - 5.0%, and the 5% citric acid solution is the best.

[0062] Example 4. In this example, vegetable oil extraction solvent is used to extract fresh black soldier fly larvae slurry

[0063] The difference between this example and Example 2 is that in this example, vegetable oil extraction solvent is used as the extraction solvent. The specific content is: add the treated fresh larvae slurry to the vegetable oil extraction solvent at a material-liquid ratio of 1 g:5 ml, and extract at 50 °C for 2 times, with each extraction for 60 min.

[0064] In this example, the dosage of fresh black soldier fly larvae is 2000 g, and finally 167.43 g of fresh black soldier fly larvae oil product can be obtained. The refined oil is clear and transparent and has the unique taste of black soldier fly larvae. See specifically Figure 2 .

[0065] After calculation, the extraction rate of fresh black soldier fly oil in this example is 91.82%.

[0066] Example 5 This example examines the effect of the material-liquid ratio of fresh insect slurry and petroleum ether on the extraction rate

[0067] The difference between this example and Example 2 is only that: in this example, the material-liquid ratio of petroleum ether and fresh insect slurry is 1 g: 3.5 ml, 1 g: 4 ml, 1 g: 6 ml, and the corresponding oil extraction rates for different material-liquid ratios are shown in Table 2.

[0068] Table 2

[0069]

[0070] As can be seen from Table 2, when the material-liquid ratio of fresh insect slurry and petroleum ether ≥ 1 g: 3.5 ml, the oil extraction rates are all greater than 90%, indicating that the material-liquid ratio of fresh insect slurry and petroleum ether is preferably controlled above 1 g: 3.5 ml. In addition, as the dosage of petroleum ether increases, the oil extraction rate gradually increases and then gradually reaches equilibrium. Therefore, in actual production, in view of the principles of safety production and economy, the material-liquid ratio of fresh insect slurry and petroleum ether is preferably 1 g: 4 ml to 1 g: 6 ml, with 1 g: 5 ml being the optimal.

[0071] Example 6 This example takes the extraction temperature as a variable

[0072] The difference between this example and Example 2 is only that: in step S2 of this example, the extraction temperatures are 30 °C, 40 °C, 60 °C and 65 °C in sequence, and the corresponding oil extraction rates for different extraction temperatures are shown in Table 3.

[0073] Table 3

[0074]

[0075] As can be seen from Table 3, when the extraction temperature is between 30 °C and 65 °C, the oil extraction rates are all greater than 90%. Among them, as the extraction temperature increases, the oil extraction rate first increases and then decreases, and reaches the maximum at 50 °C. Therefore, in actual production, the extraction temperature of fresh insect slurry is preferably 40 °C to 60 °C, more preferably 50 °C.

[0076] Example 7 This example takes the extraction time as a variable

[0077] The difference between this embodiment and Embodiment 2 lies only in that: in step S2 of this embodiment, the extraction times are 45 min, 90 min, and 120 min in sequence, and the oil extraction rates corresponding to different extraction temperatures are shown in Table 4.

[0078] Table 4

[0079]

[0080] As can be seen from Table 4, when the extraction temperature is between 45 min and 120 min, the oil extraction rates are all greater than 90%. Among them, as the extraction time increases, the oil extraction rate first increases and then decreases, and the oil extraction rate reaches the maximum when the single extraction time is 60 min. In actual production, the extraction time of the fresh insect slurry in the present invention should be controlled within 90 min, preferably controlled at 60 min.

[0081] Example 8 This example takes the number of extraction times as a variable

[0082] The difference between this embodiment and Embodiment 2 lies only in that: in step S2 of this embodiment, the extraction temperatures are 3 times, 4 times, and 5 times in sequence, and the oil extraction rates corresponding to different extraction temperatures are shown in Table 5.

[0083] Table 5

[0084]

[0085] As can be seen from Table 4, when the number of extraction times ≥ 2 times, the oil extraction rates corresponding to different extraction times ≥ 94%, but as the number of extraction times increases, the oil extraction rate basically does not change. Therefore, in actual production, the number of extraction times is preferably 2 times, so as to reduce the amount of extraction solvent used, shorten the oil extraction time, and reduce the production cost of the enterprise.

[0086] It can be seen from Examples 1-8 that the present invention uses citric acid or 3.5% - 5% citric acid solution to treat fresh black soldier fly larvae to obtain fresh black soldier fly larvae slurry. The acidic environment provided by citric acid is beneficial to the separation of some lipids from proteins and carbohydrates in biological cells during the subsequent extraction process, improving the oil extraction rate and protecting the proteins in the crude protein of fresh black soldier fly larvae, and improving the protein quality; citric acid can also chelate polyvalent metal ions such as Cu 2＋ Mg 2＋ Fe 2＋ These metal ions are usually cofactors of enzyme action. The chelating effect of citric acid can effectively reduce the catalytic activity of enzymes, thereby effectively inhibiting browning involving enzymes, making the extracted oil lighter in color and improving the quality of black soldier fly oil. In addition, the shearing force and high-intensity centrifugal action provided by high-pressure homogenization can fully break the biological cells of fresh black soldier fly larvae, further improving the oil extraction rate of fresh black soldier fly larvae.

[0087] As can be seen from Examples 2-8, the oil extraction rate of fresh black soldier fly larvae in the present invention is above 90%, and even as high as 95% (such as in Example 2). The black soldier fly oil in Example 2 was successively subjected to conventional degumming, caustic refining for deacidification, and dehydration and drying treatments to obtain fresh black soldier fly caustic-refined oil; the physicochemical analysis was carried out on the black soldier fly oil finished product and the fresh black soldier fly caustic-refined oil obtained in Example 2, and the physicochemical indexes are shown in Table 6, and the fatty acid composition and content of the black soldier fly oil (analyzed by gas chromatography-mass spectrometry (GC-MS)) are shown in Table 7.

[0088] Table 6 Physicochemical indexes of fresh black soldier fly larvae oil and its caustic-refined product

[0089]

[0090] As can be seen from Table 6 above, after the degumming and deacidification and drying treatments of the fresh black soldier fly larvae oil, the moisture and volatiles, acid value, peroxide value, and solvent residue in the fresh black soldier fly larvae oil are significantly reduced. The oil color of the fresh black soldier fly larvae oil before and after refining is transparent yellowish-brown (see Figure 3 ), and transparent dark yellow (see Figure 4 ), respectively, with good quality. Using it for the preparation of microcapsule powder of black soldier fly oil, the obtained microcapsule powder has a small odor and improves the quality of the microcapsule powder.

[0091] Table 7 Fatty acid composition of fresh black soldier fly larvae oil and fresh black soldier fly caustic-refined oil

[0092]

[0093] As can be seen from Table 7, the main saturated fatty acids in the black soldier fly larvae oil are lauric acid (C12:0), palmitic acid (C16:0), myristic acid (C14:0), and stearic acid (C18:0); the monounsaturated fatty acid is mainly oleic acid (C18:1), followed by palmitoleic acid (C16:1); the polyunsaturated fatty acid is mainly linoleic acid (C18:2);

[0094] After the degumming and caustic refining for deacidification and drying treatments of the fresh black soldier fly larvae oil, the fatty acid content in the oil increases from the original 53.61% to 83.94%. The content of lauric acid in the oil is as high as 29.97%, and the total content of unsaturated fatty acids (including oleic acid, linoleic acid, and α-linolenic acid) is as high as 35.59%, indicating that the oil extraction process of the present invention can effectively ensure the quality of the refined oil.

[0095] The above-described embodiments are only the preferred solutions of the present invention, but they are not intended to limit the present invention. Those of ordinary skill in the relevant technical fields can still make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all technical solutions obtained by adopting equivalent substitution or equivalent transformation fall within the protection scope of the present invention.

Claims

1. A method for preparing black soldier fly oil from fresh black soldier fly larvae, characterized in that: It includes the following steps: S1. Add a citric acid solution to the fresh black soldier fly larvae according to a material-liquid ratio of 1 g: 1.0 ml to 1 g: 2.0 ml, and perform high-pressure homogenization at room temperature. The high-pressure homogenization speed is ≥ 8000 r / min to obtain a fresh insect slurry. The concentration of the citric acid solution is 3.5% - 5.5%; S2. Add the treated fresh insect slurry to an extraction solvent. The material-liquid ratio of the fresh insect slurry to the extraction solvent is 1 g: 3.5 ml to 1 g: 6 ml; perform low-temperature extraction at 40 - 60 °C for 2 - 5 times, and the extraction time for each time is 45 min - 90 min to obtain a three-phase mixture of solid phase, water phase and mixed oil phase; S3. Perform solid-liquid separation on the three-phase mixture obtained in step S2, and then perform oil-water separation to obtain a mixed oil phase of the extraction solvent and fresh black soldier fly larvae oil; S4. Remove the extraction solvent from the mixed oil phase to obtain a crude extract of fresh black soldier fly larvae oil; S5. After subjecting the crude extract of fresh black soldier fly larvae oil to residue removal and impurity removal, obtain fresh black soldier fly larvae oil; S6. Perform degumming, caustic refining and dehydration drying treatments on the fresh black soldier fly larvae oil obtained in S5 in sequence to obtain fresh black soldier fly caustic-refined oil; The extraction solvent used in step S2 is petroleum ether.

2. The method for preparing black soldier fly oil from fresh black soldier fly larvae according to claim 1, characterized in that: The concentration of the citric acid solution in step S1 is 5%.

3. The method for preparing black soldier fly oil from fresh black soldier fly larvae according to claim 1, characterized in that: The extraction solvent used in step S2 is petroleum ether with a boiling range of 60 °C - 90 °C.

4. The method for preparing black soldier fly oil from fresh black soldier fly larvae according to claim 1, characterized in that: The material-liquid ratio of the fresh insect slurry to the extraction solvent in step S2 is 1 g: 5 ml.

5. The method for preparing black soldier fly oil from fresh black soldier fly larvae according to claim 1, characterized in that: In step S2, low-temperature extraction is performed at 50 °C for 2 - 5 times.

6. The method for preparing black soldier fly oil from fresh black soldier fly larvae according to claim 1, characterized in that: The extraction time for each time in step S2 is 60 min.

7. The method for preparing black soldier fly oil from fresh black soldier fly larvae according to claim 1, characterized in that: In step S4, removing the extraction solvent from the mixed oil phase includes the following: Evaporate and recover the extraction solvent in the oil phase under the conditions of 45 - 65 °C and -0.045 MPa - -0.095 MPa.

8. The method for preparing black soldier fly oil from fresh black soldier fly larvae according to claim 1, characterized in that: In step S5, the residue removal temperature of the crude extract of fresh black soldier fly larvae oil is 60 °C - 65 °C.

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