Deep eutectic solvent for converting and extracting free astaxanthin as well as preparation and extraction methods of deep eutectic solvent
By using a deep eutectic solvent composed of diamine-based hydrogen bond acceptors and phenol-based hydrogen bond donors, the problem of cumbersome and high cost of astaxanthin extraction in the prior art is solved, and the efficient and green method of converting astaxanthin ester into free astaxanthin is achieved, which is suitable for large-scale applications.
Patent Information
- Application Number
- CN202510683258.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-26
- Publication Date
- 2025-08-19
AI Technical Summary
When extracting astaxanthin, the saponification process is complicated, the reagents are consumed, the cost is high, and it is not environmentally friendly, making it difficult to obtain free astaxanthin efficiently.
A deep eutectic solvent composed of diamine-based hydrogen bond acceptors and phenol-based hydrogen bond donors is prepared by mixing and cooling, and is used to convert and extract astaxanthin ester into free astaxanthin. The extraction method includes mixing, conversion, separation and drying steps.
It realizes efficient, green and low-cost astaxanthin extraction, which can convert astaxanthin ester into free astaxanthin in one step, with high extraction efficiency and is suitable for large-scale applications.
Smart Images
Figure CN120502129A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of natural ingredient extraction, and specifically relates to a deep eutectic solvent for converting and extracting free astaxanthin, a preparation method thereof, and a method for extracting free astaxanthin. Background Art
[0002] Astaxanthin is a naturally occurring carotenoid found in abundance in various microorganisms, phytoplankton, and marine animals. Astaxanthin possesses strong antioxidant properties, primarily due to the active electronic effects of its conjugated double bonds and hydroxyl groups. These compounds effectively quench highly oxidative singlet reactive oxygen species and other free radicals in the environment, preventing them from damaging cells. Furthermore, astaxanthin exhibits anti-inflammatory, anti-tumor, and weight-loss properties. Currently, astaxanthin has become a key ingredient in dietary supplements and functional cosmetics, with growing demand and market size, resulting in a relatively high price. Natural sources of astaxanthin include algae, red yeast, salmon, and krill. Haematococcus pluvialis, with astaxanthin accumulation reaching approximately 3-5% of dry weight, is currently one of the primary sources of natural astaxanthin. However, naturally occurring astaxanthin is typically esterified with C16, C18, or C20 fatty acids to form astaxanthin esters. Astaxanthin monoesters account for approximately 75%, astaxanthin diesters for approximately 20%, and free astaxanthin for only 5%. Therefore, astaxanthin esters must be converted to astaxanthin through saponification. This saponification process involves strong acid and alkali treatment, is cumbersome, consumes a lot of reagents, is costly, and is environmentally unfriendly. Therefore, developing a green and efficient method for extracting free astaxanthin is of great value.
[0003] A deep eutectic solvent (DES) is a stable solvent that is generally liquid at room temperature and formed by the melting of two or more substances through intermolecular hydrogen bonding. It is a two- or multi-component mixture composed of a hydrogen bond acceptor (HBA) and a hydrogen bond donor (HBD) in a specific molar ratio. Its melting point is significantly lower than that of the individual components and can be prepared by heating, freeze-drying, and grinding. Deep eutectic solvents are characterized by being nonvolatile and nonflammable; having a simple preparation process that requires no purification; readily available and inexpensive raw materials; and exhibiting good biocompatibility and biodegradability. Summary of the Invention
[0004] In response to the above-mentioned prior art, the present invention provides a deep eutectic solvent for converting and extracting free astaxanthin, a preparation method thereof, and a method for extracting free astaxanthin, in order to develop a new idea for astaxanthin extraction.
[0005] In order to achieve the above-mentioned object, the technical solution adopted by the present invention is to provide a deep eutectic solvent for converting and extracting free astaxanthin, wherein the deep eutectic solvent is composed of a diamine hydrogen bond acceptor and a phenol hydrogen bond donor.
[0006] On the basis of the above technical solution, the present invention can also be improved as follows.
[0007] Furthermore, the diamine hydrogen bond acceptor is at least one of 1,3-propylenediamine, 1,2-propylenediamine, 1,4-butylenediamine, 1,6-hexanediamine and 1,8-octanediamine; the phenol hydrogen bond donor is at least one of phenol, p-chlorophenol, o-chlorophenol, m-chlorophenol, p-cresol, o-cresol, m-cresol, p-aminophenol, o-aminophenol and 4-methoxyphenol.
[0008] Furthermore, the molar ratio of the diamine hydrogen bond acceptor to the phenol hydrogen bond donor is 1-6:1.
[0009] The present invention also discloses a method for preparing the deep eutectic solvent for converting and extracting free astaxanthin, comprising the following steps: The diamine hydrogen bond acceptor and the phenol hydrogen bond donor are mixed according to a specified molar ratio, shaken to obtain the mixture, and then cooled and allowed to stand to room temperature.
[0010] The present invention also discloses a method for extracting free astaxanthin, which comprises extracting a raw material containing astaxanthin ester or a crude astaxanthin ester with the deep eutectic solvent for converting and extracting free astaxanthin.
[0011] Further, astaxanthin extraction comprises the following steps: S1: mixing the raw material containing astaxanthin ester or the crude astaxanthin ester with a deep eutectic solvent for converting and extracting free astaxanthin, and converting and extracting at a temperature of 1-30° C. for 1-2 hours in a protective gas atmosphere to obtain an astaxanthin extract; S2: Add water to the astaxanthin extract, let it stand at room temperature to separate the layers; then centrifuge, collect the upper oily substance, wash with water, and dry to obtain the astaxanthin extract.
[0012] Furthermore, the raw material containing astaxanthin ester is Haematococcus pluvialis powder.
[0013] Furthermore, the Haematococcus pluvialis powder is subjected to a wall-breaking treatment, and the wall-breaking treatment method is: mixing the Haematococcus pluvialis powder with 5.5M hydrochloric acid at a material-liquid ratio of 1g:100mL, reacting at 70°C for 6.5min, filtering, washing, and freeze-drying to obtain the product.
[0014] Furthermore, the material-liquid ratio of the raw material containing astaxanthin ester to the deep eutectic solvent used for converting and extracting free astaxanthin is 1 g:40~150 mL.
[0015] The beneficial effects of the present invention are: 1. The deep eutectic solvent used for the conversion and extraction of free astaxanthin in the present invention is composed of a diamine hydrogen bond acceptor and a phenol hydrogen bond donor. It is a deep eutectic solvent with a completely new composition, which broadens the way for the development of new deep eutectic solvents.
[0016] 2. The deep eutectic solvent used for converting and extracting free astaxanthin in the present invention is used as an extractant to effectively extract astaxanthin from astaxanthin ester-containing raw materials, providing a new idea for the extraction of astaxanthin.
[0017] 3. The deep eutectic solvent used for the conversion and extraction of free astaxanthin in the present invention integrates conversion and extraction, enabling a single-step conversion of astaxanthin esters in the raw material into free astaxanthin and extraction. The process for extracting astaxanthin using the deep eutectic solvent of the present invention is simple, highly efficient, time-efficient, low-cost, environmentally friendly, and suitable for large-scale application. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 This is the HPLC analysis chart of the all-trans astaxanthin reference substance; Figure 2 HPLC analysis of crude astaxanthin esters from Haematococcus pluvialis obtained by traditional extraction method in Example 1; Figure 3 This is an HPLC analysis chart of the crude astaxanthin obtained by conversion and extraction using 1,3-propylenediamine-m-cresol DES in Example 2; Figure 4 HPLC analysis of crude astaxanthin obtained by conversion and extraction using 1,3-propylenediamine-p-chlorophenol DES in Example 3; Figure 5 This is an HPLC analysis chart of the crude astaxanthin obtained by conversion and extraction using 1,4-butanediamine-m-cresol DES in Example 4; Figure 6 This is an HPLC analysis chart of the crude astaxanthin obtained by conversion and extraction using 1,6-hexanediamine-m-cresol DES in Example 5; Figure 7 HPLC analysis of crude astaxanthin obtained by conversion and extraction using 1,8-octanediamine-m-cresol DES in Example 6; Figure 8 This is an HPLC analysis chart of the crude astaxanthin obtained by conversion and extraction using 1,3-propylenediamine-ethylene glycol DES in Example 7; Figure 9 This is an HPLC analysis chart of the crude astaxanthin obtained by conversion and extraction using choline chloride-m-cresol DES in Example 8; Figure 10 This is the HPLC analysis chart of astaxanthin extracted by traditional acid-base saponification conversion in Example 9. DETAILED DESCRIPTION
[0019] The present invention will be further described in detail below in conjunction with specific embodiments. The examples provided are only for illustrating the present invention and are not intended to limit the scope of the present invention. The examples provided below can serve as a guide for further improvements by those skilled in the art and are not intended to limit the present invention in any way.
[0020] Unless otherwise specified, the experimental methods in the following examples are conventional methods and were performed according to the techniques or conditions described in the literature in the field or according to the product instructions. The materials and reagents used in the following examples, unless otherwise specified, were all commercially available.
[0021] Example 1: Extraction of astaxanthin esters from Haematococcus pluvialis using traditional methods The traditional extraction method includes the following steps: S1: Mixing Haematococcus pluvialis powder with 5.5M hydrochloric acid at a material-liquid ratio of 1 g:100 mL, reacting in a 70°C water bath for 6.5 min, then filtering to remove the hydrochloric acid solution, washing with water three times, and freeze-drying to obtain cracked Haematococcus pluvialis powder; S2: The broken wall Haematococcus pluvialis powder was mixed with ethanol at a solid-liquid ratio of 1 g:60 mL, and ultrasonic extraction was performed at room temperature for 5 min to obtain a crude astaxanthin ester extract.
[0022] The crude astaxanthin ester extract was subjected to HPLC analysis; the analysis conditions were as follows: Chromatographic column: C30 column (YMC, 250×4.6 mm, 5 µm); column temperature: 25°C; mobile phase: methanol (A), methyl tert-butyl ether (B) and 1% acetic acid aqueous solution (C); gradient elution: 0-15 min, 81%-66% A, 15%-30% B; 15-22 min, 66%-16% A, 30%-80% B; 22-28 min, 16%-81% A, 80%-15% B; 28-33 min, 81%-81% A, 15%-15% B; flow rate: 1 mL / min; detector: DAD, detection wavelength 474 nm.
[0023] Figure 1 and Figure 2 The following are HPLC analyses of an all-trans astaxanthin reference substance and a crude astaxanthin ester extract from Haematococcus pluvialis. It can be seen that the vast majority of astaxanthin in Haematococcus pluvialis exists in the form of astaxanthin esters, with very little free astaxanthin.
[0024] Example 2 A deep eutectic solvent for converting and extracting free astaxanthin, the deep eutectic solvent consisting of 1,3-propylenediamine and m-cresol, and the preparation method thereof is as follows: 1,3-Propylenediamine and m-cresol are mixed in a molar ratio of 3:1, ultrasonically shaken until the mixture is uniform, and then the solution is naturally cooled to room temperature (heat will be released during the mixing process) to obtain a deep eutectic solvent DES.
[0025] The astaxanthin extraction was performed using the deep eutectic solvent in this embodiment, which specifically includes the following steps: S1: Mixing Haematococcus pluvialis powder with 5.5M hydrochloric acid at a material-liquid ratio of 1 g:100 mL, reacting in a 70°C water bath for 6.5 min, then filtering to remove the hydrochloric acid solution, washing with water three times, and freeze-drying to obtain cracked Haematococcus pluvialis powder; S2: Mix the cracked Haematococcus pluvialis powder with a deep eutectic solvent at a material-liquid ratio of 1 g:110 mL, and extract at 5°C in a nitrogen atmosphere for 2 h to obtain an astaxanthin extract; S3: Add water to the astaxanthin extract, let it stand at room temperature to separate the layers; then centrifuge, collect the upper oily substance, wash it with water three times, and then dry it to constant weight.
[0026] The astaxanthin extract was subjected to HPLC analysis; the analysis conditions were the same as in Example 1. The HPLC analysis results of the astaxanthin extract were as follows: Figure 3 As shown. Figure 1 All-trans free astaxanthin and Figure 2 Compared with the HPLC spectrum of the crude astaxanthin ester extract, it can be seen that 1,3-propylenediamine-m-cresol DES can be used to extract and convert astaxanthin ester into free astaxanthin from Haematococcus pluvialis in one step, and the conversion is relatively complete.
[0027] The content of free astaxanthin in the astaxanthin extract was analyzed by HPLC external standard method, and the yield of free astaxanthin extracted by transformation of Haematococcus pluvialis was calculated to be 35.8 mg / g.
[0028] Example 3 A deep eutectic solvent for converting and extracting free astaxanthin, the deep eutectic solvent consisting of 1,3-propylenediamine and p-chlorophenol, and the preparation method thereof is as follows: 1,3-Propanediamine and p-chlorophenol are mixed in a molar ratio of 1:1, ultrasonically shaken until the mixture is uniform, and then the solution is naturally cooled to room temperature (heat will be released during the mixing process) to obtain a deep eutectic solvent DES.
[0029] The astaxanthin extraction was performed using the deep eutectic solvent in this embodiment, which specifically includes the following steps: S1: Mixing Haematococcus pluvialis powder with 5.5M hydrochloric acid at a material-liquid ratio of 1 g:100 mL, reacting in a 70°C water bath for 6.5 min, then filtering to remove the hydrochloric acid solution, washing with water three times, and freeze-drying to obtain cracked Haematococcus pluvialis powder; S2: Mix the cracked Haematococcus pluvialis powder with a deep eutectic solvent at a material-liquid ratio of 1 g:40 mL, and extract under a nitrogen atmosphere at room temperature for 2 h to obtain an astaxanthin extract; S3: Add water to the astaxanthin extract, let it stand at room temperature to separate the layers; then centrifuge, collect the upper oily substance, wash it with water three times, and then dry it to constant weight.
[0030] The astaxanthin extract was subjected to HPLC analysis; the analysis conditions were the same as in Example 1. The HPLC analysis results of the astaxanthin extract were as follows: Figure 4 As shown. Figure 1 All-trans free astaxanthin and Figure 2 Compared with the HPLC spectrum of the crude astaxanthin ester extract, it can be seen that 1,3-propylenediamine-p-chlorophenol DES can be used to partially extract and convert astaxanthin esters from Haematococcus pluvialis into free astaxanthin.
[0031] The content of free astaxanthin in the astaxanthin extract was analyzed by HPLC external standard method, and the yield of free astaxanthin extracted by transformation of Haematococcus pluvialis was calculated to be 9.1 mg / g.
[0032] Example 4 A deep eutectic solvent for converting and extracting free astaxanthin, the deep eutectic solvent consisting of 1,4-butanediamine and m-cresol, and the preparation method thereof is as follows: 1,4-Butanediamine and m-cresol are mixed in a molar ratio of 1:1, ultrasonically shaken until the mixture is uniform, and then the solution is naturally cooled to room temperature (heat will be released during the mixing process) to obtain a deep eutectic solvent DES.
[0033] The astaxanthin extraction was performed using the deep eutectic solvent in this embodiment, which specifically includes the following steps: S1: Mixing Haematococcus pluvialis powder with 5.5M hydrochloric acid at a material-liquid ratio of 1 g:100 mL, reacting in a 70°C water bath for 6.5 min, then filtering to remove the hydrochloric acid solution, washing with water three times, and freeze-drying to obtain cracked Haematococcus pluvialis powder; S2: Mix the cracked Haematococcus pluvialis powder with a deep eutectic solvent at a material-liquid ratio of 1 g:70 mL, and extract under a nitrogen atmosphere at room temperature for 2 h to obtain an astaxanthin extract; S3: Add water to the astaxanthin extract, let it stand at room temperature to separate the layers; then centrifuge, collect the upper oily substance, wash it with water three times, and then dry it to constant weight.
[0034] The astaxanthin extract was subjected to HPLC analysis; the analysis conditions were the same as in Example 1. The HPLC analysis results of the astaxanthin extract were as follows: Figure 5 As shown. Figure 1 All-trans free astaxanthin and Figure 2Compared with the HPLC spectrum of the crude astaxanthin ester extract, it can be seen that 1,4-diaminobutane-m-cresol DES can be used to partially extract and convert astaxanthin esters from Haematococcus pluvialis into free astaxanthin.
[0035] The content of free astaxanthin in the astaxanthin extract was analyzed by HPLC external standard method, and the yield of free astaxanthin extracted by transformation of Haematococcus pluvialis was calculated to be 7.3 mg / g.
[0036] Example 5 A deep eutectic solvent for converting and extracting free astaxanthin, the deep eutectic solvent consisting of 1,6-hexanediamine and m-cresol, and the preparation method thereof is as follows: 1,6-Hexanediamine and m-cresol are mixed in a molar ratio of 1:1, ultrasonically shaken until the mixture is uniform, and then the solution is naturally cooled to room temperature (heat will be released during the mixing process) to obtain a deep eutectic solvent DES.
[0037] The astaxanthin extraction was performed using the deep eutectic solvent in this embodiment, which specifically includes the following steps: S1: Mixing Haematococcus pluvialis powder with 5.5M hydrochloric acid at a material-liquid ratio of 1 g:100 mL, reacting in a 70°C water bath for 6.5 min, then filtering to remove the hydrochloric acid solution, washing with water three times, and freeze-drying to obtain cracked Haematococcus pluvialis powder; S2: Mix the cracked Haematococcus pluvialis powder with a deep eutectic solvent at a material-liquid ratio of 1 g:70 mL, and extract under a nitrogen atmosphere at room temperature for 2 h to obtain an astaxanthin extract; S3: Add water to the astaxanthin extract, let it stand at room temperature to separate the layers; then centrifuge, collect the upper oily substance, wash it with water three times, and then dry it to constant weight.
[0038] The astaxanthin extract was subjected to HPLC analysis; the analysis conditions were the same as in Example 1. The HPLC analysis results of the astaxanthin extract were as follows: Figure 6 As shown. Figure 1 All-trans free astaxanthin and Figure 2 Compared with the HPLC spectrum of the crude astaxanthin ester extract, it can be seen that 1,6-hexanediamine-m-cresol DES can be used to partially extract and convert astaxanthin esters from Haematococcus pluvialis into free astaxanthin.
[0039] The content of free astaxanthin in the astaxanthin extract was analyzed by HPLC external standard method, and the yield of free astaxanthin extracted by transformation of Haematococcus pluvialis was calculated to be 5.8 mg / g.
[0040] Example 6 A deep eutectic solvent for converting and extracting free astaxanthin, the deep eutectic solvent consisting of 1,8-octanediamine and m-cresol, and the preparation method thereof is as follows: 1,8-octanediamine and m-cresol are mixed in a molar ratio of 1:1, ultrasonically shaken until the mixture is uniform, and then the solution is naturally cooled to room temperature (heat will be released during the mixing process) to obtain a deep eutectic solvent DES.
[0041] The astaxanthin extraction was performed using the deep eutectic solvent in this embodiment, which specifically includes the following steps: S1: Mixing Haematococcus pluvialis powder with 5.5M hydrochloric acid at a material-liquid ratio of 1 g:100 mL, reacting in a 70°C water bath for 6.5 min, then filtering to remove the hydrochloric acid solution, washing with water three times, and freeze-drying to obtain cracked Haematococcus pluvialis powder; S2: Mix the cracked Haematococcus pluvialis powder with a deep eutectic solvent at a material-liquid ratio of 1 g:70 mL, and extract under a nitrogen atmosphere at room temperature for 2 h to obtain an astaxanthin extract; S3: Add water to the astaxanthin extract, let it stand at room temperature to separate the layers; then centrifuge, collect the upper oily substance, wash it with water three times, and then dry it to constant weight.
[0042] The astaxanthin extract was subjected to HPLC analysis; the analysis conditions were the same as in Example 1. The HPLC analysis results of the astaxanthin extract were as follows: Figure 7 As shown. Figure 1 All-trans free astaxanthin and Figure 2 By comparing the HPLC spectra of the crude astaxanthin ester extract, it can be seen that 1,8-octanediamine and m-cresol DES can partially extract and convert astaxanthin esters from Haematococcus pluvialis into free astaxanthin.
[0043] The content of free astaxanthin in the astaxanthin extract was analyzed by HPLC external standard method, and the yield of free astaxanthin extracted by transformation of Haematococcus pluvialis was calculated to be 6.9 mg / g.
[0044] Example 7 A deep eutectic solvent for converting and extracting free astaxanthin, the deep eutectic solvent consisting of 1,3-propylenediamine and ethylene glycol, and the preparation method thereof is as follows: 1,3-Propylenediamine and ethylene glycol are mixed in a molar ratio of 1:1, ultrasonically shaken until the mixture is uniformly mixed, and then the solution is naturally cooled to room temperature (heat will be released during the mixing process) to obtain a deep eutectic solvent DES.
[0045] The astaxanthin extraction was performed using the deep eutectic solvent in this embodiment, which specifically includes the following steps: S1: Mixing Haematococcus pluvialis powder with 5.5M hydrochloric acid at a material-liquid ratio of 1 g:100 mL, reacting in a 70°C water bath for 6.5 min, then filtering to remove the hydrochloric acid solution, washing with water three times, and freeze-drying to obtain cracked Haematococcus pluvialis powder; S2: Mix the cracked Haematococcus pluvialis powder with a deep eutectic solvent at a material-liquid ratio of 1 g:40 mL, and extract under a nitrogen atmosphere at room temperature for 2 h to obtain an astaxanthin extract; S3: Add water to the astaxanthin extract, let it stand at room temperature to separate the layers; then centrifuge, collect the upper oily substance, wash it with water three times, and then dry it to constant weight.
[0046] The astaxanthin extract was subjected to HPLC analysis; the analysis conditions were the same as in Example 1. The HPLC analysis results of the astaxanthin extract were as follows: Figure 8 As shown. Figure 1 All-trans free astaxanthin and Figure 2 Comparing the HPLC spectra of crude astaxanthin ester extracts with those of the 1,3-propylenediamine-ethylene glycol DES, it can be seen that the efficiency of converting free astaxanthin into free astaxanthin is very low, indicating that the DES generated by diamine HBA and phenol HBD is specific for converting astaxanthin esters into free astaxanthin.
[0047] The content of free astaxanthin in the astaxanthin extract was analyzed by HPLC external standard method, and the yield of free astaxanthin extracted by transformation of Haematococcus pluvialis was calculated to be 1.2 mg / g.
[0048] Example 8 A deep eutectic solvent for converting and extracting free astaxanthin, the deep eutectic solvent consisting of choline chloride and m-cresol, and the preparation method thereof is as follows: Choline chloride and m-cresol are mixed in a molar ratio of 1:2, ultrasonically shaken until the mixture is uniform, and then the solution is naturally cooled to room temperature (heat will be released during the mixing process) to obtain the deep eutectic solvent DES.
[0049] The astaxanthin extraction was performed using the deep eutectic solvent in this embodiment, which specifically includes the following steps: S1: Mixing Haematococcus pluvialis powder with 5.5M hydrochloric acid at a material-liquid ratio of 1 g:100 mL, reacting in a 70°C water bath for 6.5 min, then filtering to remove the hydrochloric acid solution, washing with water three times, and freeze-drying to obtain cracked Haematococcus pluvialis powder; S2: Mix the cracked Haematococcus pluvialis powder with a deep eutectic solvent at a material-liquid ratio of 1 g:70 mL, and extract under a nitrogen atmosphere at room temperature for 2 h to obtain an astaxanthin extract; S3: Add water to the astaxanthin extract, let it stand at room temperature to separate the layers; then centrifuge, collect the upper oily substance, wash it with water three times, and then dry it to constant weight.
[0050] The astaxanthin extract was subjected to HPLC analysis; the analysis conditions were the same as in Example 1. The HPLC analysis results of the astaxanthin extract were as follows: Figure 9 As shown. Figure 1 All-trans free astaxanthin and Figure 2 Comparing the HPLC spectra of crude astaxanthin ester extracts with those obtained with choline chloride-m-cresol DES, it can be seen that the efficiency of converting free astaxanthin into free astaxanthin is very low. This further demonstrates the specificity of DES generated by diamine HBA and phenol HBD for converting astaxanthin esters into free astaxanthin.
[0051] The content of free astaxanthin in the astaxanthin extract was analyzed by HPLC external standard method, and the yield of free astaxanthin extracted by transformation of Haematococcus pluvialis was calculated to be 0.3 mg / g.
[0052] Example 9: Extraction of astaxanthin from Haematococcus pluvialis using traditional saponification method In order to compare the efficiency of the method of the present invention, the same treatment method as the liquid chromatography method for the determination of astaxanthin in Haematococcus algae in national standard GB / T 31520-2015 was used to transform and extract free astaxanthin in algae powder, specifically comprising the following steps: S1: Add Haematococcus pluvialis powder into dichloromethane-methanol (25:75, v / v) solution at a solid-liquid ratio of 1 g:1000 mL, and extract by ultrasonication three times, each time for 3 min. S2: Centrifuge and collect the supernatant; remove 5 mL and dilute to 50 mL with dichloromethane-methanol solution; S3: Take 5 mL of the fixed volume solution, add 0.7 mL of 0.1 mol / L sodium hydroxide-methanol solution, and react at low temperature (5°C) for 12 h; S4: Add 0.4 mL of 2% phosphoric acid-methanol solution (volume fraction) to the reaction-completed solution to obtain an astaxanthin extract.
[0053] The content of free astaxanthin in the extract was analyzed by HPLC external standard method, and the yield of free astaxanthin extracted by transformation of Haematococcus pluvialis was calculated to be 39.71 mg / g.
[0054] Figure 10 This is the HPLC analysis of astaxanthin extracted by traditional acid-base saponification conversion, and the analysis conditions are the same as those in Example 1. Figure 1 All-trans free astaxanthin and Figure 2 Comparison of the HPLC spectra of crude astaxanthin ester extracts using the conventional method reveals that astaxanthin esters can also be extracted and converted into free astaxanthin. The yield achieved by the conventional method is comparable to that achieved using 1,3-propylenediamine-m-cresol (3:1) DES in Example 2 of the present invention. However, the conventional method has multiple steps and is time-consuming (12 hours), while the present method is simple, requiring only 1-2 hours and exhibiting high efficiency.
[0055] Although the specific embodiments of the present invention have been described in detail in conjunction with the embodiments, this should not be construed as limiting the scope of protection of this patent. Within the scope described by the claims, various modifications and variations that can be made by those skilled in the art without creative work still fall within the scope of protection of this patent.
Claims
1. A deep eutectic solvent for converting and extracting free astaxanthin, characterized by: The deep eutectic solvent consists of a diamine hydrogen bond acceptor and a phenol hydrogen bond donor.
2. The deep eutectic solvent for conversion and extraction of free astaxanthin according to claim 1, characterized in that: The diamine hydrogen bond acceptor is at least one of 1,3-propylenediamine, 1,2-propylenediamine, 1,4-butylenediamine, 1,6-hexanediamine and 1,8-octanediamine; the phenol hydrogen bond donor is at least one of phenol, p-chlorophenol, o-chlorophenol, m-chlorophenol, p-cresol, o-cresol, m-cresol, p-aminophenol, o-aminophenol and 4-methoxyphenol.
3. The deep eutectic solvent for conversion and extraction of free astaxanthin according to claim 2, characterized in that: The molar ratio of the diamine hydrogen bond acceptor to the phenol hydrogen bond donor is 1-6:
1.
4. The method for preparing a deep eutectic solvent for converting and extracting free astaxanthin according to any one of claims 1 to 3, characterized in that: The following steps are involved: The diamine hydrogen bond acceptor and the phenol hydrogen bond donor are mixed according to a specified molar ratio, shaken to obtain the mixture, and then cooled and allowed to stand to room temperature.
5. A method for extracting free astaxanthin, characterized in that: The astaxanthin ester-containing raw material or crude astaxanthin ester is extracted using the deep eutectic solvent for converting and extracting free astaxanthin according to any one of claims 1 to 3.
6. The method for extracting free astaxanthin according to claim 5, wherein Astaxanthin extraction involves the following steps: S1: mixing the raw material containing astaxanthin ester or the crude astaxanthin ester with a deep eutectic solvent for converting and extracting free astaxanthin, and converting and extracting at a temperature of 1-30° C. for 1-2 hours in a protective gas atmosphere to obtain an astaxanthin extract; S2: Add water to the astaxanthin extract, let it stand at room temperature to separate the layers; then centrifuge, collect the upper oily substance, wash with water, and dry to obtain the astaxanthin extract.
7. The use according to claim 6, characterized in that: The raw material containing astaxanthin ester is Haematococcus pluvialis powder.
8. The use according to claim 7, characterized in that The Haematococcus pluvialis powder is subjected to a wall-breaking treatment, wherein the wall-breaking treatment is as follows: the Haematococcus pluvialis powder is mixed with 5.5M hydrochloric acid at a material-liquid ratio of 1 g:100 mL, reacted at 70° C. for 6.5 min, filtered, washed, and freeze-dried to obtain the obtained product.
9. The use according to claim 6, characterized in that: The material-liquid ratio of the raw material containing astaxanthin ester to the deep eutectic solvent used for converting and extracting free astaxanthin is 1g:40~150mL.