Methods for cis-isomerization

Abstract

This invention provides a cis-isomerization method that can efficiently and quickly cis-isomerize carotenoid compounds. [Solution] The cis-isomerization method is a method for cis-isomerizing a carotenoid compound, comprising a suspension preparation step S1, a light irradiation step S2, and a residual particle removal step S3. In the suspension preparation step S1, a suspension is prepared by dispersing carotenoid compound particles in a solvent. In the light irradiation step S2, pulsed laser light is irradiated onto the suspension prepared in the suspension preparation step S1 to cis-isomerize the carotenoid compound particles dispersed in the solvent and dissolve them in the solvent. In the residual particle removal step S3, particles remaining dispersed in the solvent are removed.

Description

Technical Field

[0001] The present invention relates to a method for cis-isomerizing carotenoid compounds.

Background Art

[0002] Carotenoid compounds are a group of natural pigment compounds contained in plants and animals. Carotenoid compounds generally have a cis-trans isomer with a basic skeleton of a chemical formula C 40 H 56 formed by bonding eight isoprene units. Natural carotenoid compounds are all-trans forms.

[0003] There are many types of carotenoid compounds. Carotenoid compounds are roughly classified into carotenes composed only of carbon atoms and hydrogen atoms, and xanthophylls composed of carbon atoms, hydrogen atoms, and oxygen atoms. Examples of carotenes include α-carotene, β-carotene, lycopene, etc. Examples of xanthophylls include lutein, zeaxanthin, canthaxanthin, astaxanthin, etc.

[0004] Some carotenoid compounds are expected to have medical effects. For example, many carotenoid compounds are said to have antioxidant ability. β-carotene is said to have provitamin activity. Also, lutein is said to be effective in enhancing eye function and preventing eye diseases. Carotenoid compounds can be suitably used as ingredients contained in, for example, foods and drinks, cosmetics, pharmaceuticals, supplements, etc. In order for carotenoid compounds to exhibit the expected effects, it is desirable that the absorption of carotenoid compounds into the human body is good.

[0005] Patent Document 1 and Non-Patent Documents 1-3 describe methods for cis-isomerizing carotenoid compounds, and also state that cis-isomerization improves the solubility and bioavailability of carotenoid compounds. The cis-isomerization method described in Patent Document 1 involves irradiating a solution of acetone or the like containing dissolved lycopene with light to cis-isomerize the dissolved lycopene. The cis-isomerization method described in Non-Patent Document 1 involves adding a photosensitizer (methylene blue, chlorophyll a, erythrosine, rose bengal) to an acetone solution containing dissolved lycopene, and then irradiating this solution with light to cis-isomerize the dissolved lycopene. Patent Document 1 and Non-Patent Document 1 list mercury lamps, xenon lamps, halogen lamps, and fluorescent lamps as examples of light sources that emit light to irradiate the solution. The cis-isomerization methods described in Non-Patent Documents 2 and 3 involve heating a dichloromethane solution containing dissolved β-carotene, astaxanthin, or lycopene to cis-isomerize these carotenoid compounds. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2015-51929 [Non-patent literature]

[0007] [Non-Patent Document 1] M. Honda, H. Igami, T. Kawana, K.Hayashi, M. Takehara, Y. Inoue and C. Kitamura, "Photosensitized E / Z Isomerizationof (all-E)-Lycopene Aiming at Practical Applications," J Agric Food Chem2014 Vol.62 Issue 47 Pages 11353-6 [Non-Patent Document 2] M. Honda, T. Kodama, H. Kageyama,T. Hibino, W. , H. Kanda and M. Goto, "Enhanced Solubility and ReducedCrystallinity of Carotenoids, β-Carotene and Astaxanthin, byZ-Isomerization," European Journal of Lipid Science and Technology 2018Vol.120 Issue 11 Pages 1800191 [Non-Patent Document 3] K. Murakami, M. Honda, R.Takemura, T. Fukaya, M. Kubota, Wahyudiono, et al. "The thermal Z-isomerization-induced change in solubility and physical properties of (all-E)-lycopene," BiochemBiophys Res Commun 2017 Vol.491 Issue 2 Pages 317-322 [Overview of the project] [Problems that the invention aims to solve]

[0008] The cis-isomerization methods described in Patent Document 1 and Non-Patent Documents 1-3 require a long time to cis-isomerize carotenoid compounds and have low efficiency.

[0009] This invention was made to solve the above-mentioned problems and aims to provide a cis-isomerization method that can cis-isomerize carotenoid compounds in a short time with high efficiency. [Means for solving the problem]

[0010] The cis-isomerization method of the present invention is a method for cis-isomerizing a carotenoid compound. A first aspect of the cis-isomerization method of the present invention comprises a suspension preparation step of preparing a suspension in which particles of a carotenoid compound are dispersed in a solvent, and a light irradiation step of irradiating the suspension with pulsed laser light to cis-isomerize the particles of the carotenoid compound and dissolve them in the solvent.

[0011] A second aspect of the cis-isomerization method of the present invention further comprises, in addition to the first aspect, a residual particle removal step for removing carotenoid compound particles that remain dispersed in the solvent after the light irradiation step.

[0012] In a third aspect of the cis-isomerization method of the present invention, in addition to the solvents of the first or second aspect, the solvent is ethanol, methanol, acetone, or hexane.

[0013] In the fourth aspect of the cis-isomerization method of the present invention, in addition to any of the first to third aspects, the carotenoid compound is α-carotene, β-carotene, lycopene, astaxanthin, or lutein.

[0014] In the fifth aspect of the cis isomerization method of the present invention, in addition to any of the first to fourth aspects, the suspension is irradiated with pulsed laser light having a central wavelength in the wavelength range of 275 nm to 700 nm during the photoirradiation step.

[0015] In the sixth aspect of the cis-isomerization method of the present invention, in addition to any of the first to fourth aspects, in the photoirradiation step, if the carotenoid compound is β-carotene, pulsed laser light having a central wavelength in the wavelength range of 450 nm to 600 nm is irradiated onto the suspension.

[0016] In the seventh aspect of the cis-isomerization method of the present invention, in addition to any of the first to fourth aspects, in the photoirradiation step, if the carotenoid compound is astaxanthin, pulsed laser light having a central wavelength in the wavelength range of 450 nm to 650 nm is irradiated onto the suspension.

[0017] In the eighth aspect of the cis-isomerization method of the present invention, in addition to any one of the first to fourth aspects, in the light irradiation step, when the carotenoid compound is lycopene, pulsed laser light having a central wavelength within the wavelength range of 500 nm to 620 nm is irradiated onto the suspension.

[0018] An aspect of the present invention can be a method for producing food and drink products, cosmetics, pharmaceuticals, or supplements using the carotenoid compound cis-isomerized by the above cis-isomerization method as a raw material.

Effects of the Invention

[0019] According to the present invention, a carotenoid compound can be cis-isomerized with high efficiency in a short time.

Brief Description of the Drawings

[0020] [Figure 1] FIG. 1 is a flowchart of the cis-isomerization method of the present embodiment. [Figure 2] FIG. 2 is a diagram showing the configuration of an apparatus suitable for carrying out the light irradiation step S2 in the cis-isomerization method of the present embodiment. [Figure 3] FIG. 3 is a diagram showing the absorption spectrum obtained when pulsed laser light is irradiated in the first example. [Figure 4] FIG. 4 is a diagram showing the absorption spectrum obtained when cw laser light is irradiated in the comparative example. [Figure 5] FIG. 5 is a diagram showing the absorption spectrum obtained in the second example. [Figure 6] FIG. 6 is a graph showing the relationship between the absorbance at a wavelength of 450 nm and the irradiation light intensity obtained in the second example. [Figure 7] FIG. 7 is a diagram showing the absorption spectrum obtained when β-carotene is used in the third example. [Figure 8] FIG. 8 is a diagram showing the absorption spectrum obtained when astaxanthin is used in the third example. [Figure 9]Figure 9 shows the absorption spectrum obtained when lycopene was used in the third embodiment. [Figure 10] Figure 10 shows the absorption spectrum obtained when α-carotene was used in the third example. [Figure 11] Figure 11 shows the absorption spectrum obtained when canthaxanthin was used in the third example. [Figure 12] Figure 12 shows the absorption spectrum obtained when zeaxanthin was used in the third example. [Figure 13] Figure 13 shows the absorption spectrum obtained when lutein was used in the third embodiment. [Figure 14] Figure 14 shows the absorption spectrum obtained when ethanol was used in the fourth example. [Figure 15] Figure 15 shows the absorption spectrum obtained when methanol was used in the fourth example. [Figure 16] Figure 16 shows the absorption spectrum obtained when acetone was used in the fourth example. [Figure 17] Figure 17 shows the absorption spectrum obtained when hexane was used in the fourth example. [Figure 18] Figure 18 shows the absorption spectrum obtained when ethanol was used in the fifth example. [Figure 19] Figure 19 shows the absorption spectrum obtained when methanol was used in the fifth example. [Figure 20] Figure 20 shows the absorption spectrum obtained when acetone was used in the fifth example. [Figure 21] Figure 21 shows the absorption spectrum obtained when hexane was used in the fifth example. [Figure 22] Figure 22 shows the absorption spectra obtained in the sixth embodiment for each irradiation wavelength in the range of 460 nm to 520 nm. [Figure 23]Figure 23 shows the absorption spectra obtained in the sixth embodiment for each irradiation wavelength in the range of 515 nm to 550 nm. [Figure 24] Figure 24 shows the absorption spectra obtained in the sixth embodiment for each irradiation wavelength in the range of 540 nm to 600 nm. [Figure 25] Figure 25 is a graph showing the relationship between the absorbance at a wavelength of 445 nm and the irradiation wavelength obtained in the sixth embodiment. [Figure 26] Figure 26 shows the absorption spectra obtained in the 7th embodiment for each irradiation wavelength in the range of 450 nm to 560 nm. [Figure 27] Figure 27 shows the absorption spectra obtained in the 7th embodiment for each irradiation wavelength in the range of 550 nm to 590 nm. [Figure 28] Figure 28 shows the absorption spectra obtained in the 7th embodiment for each irradiation wavelength in the range of 580 nm to 650 nm. [Figure 29] Figure 29 is a graph showing the relationship between the absorbance at a wavelength of 470 nm obtained in the seventh example and the irradiation light wavelength. [Figure 30] Figure 30 shows the absorption spectrum obtained in the 8th embodiment when pulsed laser light irradiation was performed under the first condition (irradiation light wavelength 532 nm, pulse width 100 μs). [Figure 31] Figure 31 shows the absorption spectrum obtained in the 8th embodiment when pulsed laser light irradiation was performed under the second condition (irradiation light wavelength 420 nm, pulse width 5 ns). [Figure 32] Figure 32 shows the absorption spectrum obtained in the 8th embodiment when pulsed laser light irradiation was performed under the third condition (irradiation light wavelength 420 nm, pulse width 35 fs). [Figure 33] Figure 33 is a graph showing the relationship between absorbance at a wavelength of 450 nm and the irradiation light energy when the irradiation light wavelength is 532 nm and the pulse widths are 5 ns and 100 μs, respectively, in the 8th embodiment. [Figure 34]Figure 34 is a graph showing the relationship between absorbance at a wavelength of 450 nm and the irradiation light energy when the irradiation light wavelength is 420 nm and the pulse widths are 5 ns and 35 fs, respectively, in the 8th embodiment. [Figure 35] Figure 35 is a chromatogram showing the results of HPLC component analysis of the solution obtained when pulsed laser light irradiation was performed under the third condition (irradiation wavelength 420 nm, pulse width 35 fs, irradiation time 5 minutes) in the eighth example. [Figure 36] Figure 36 shows the absorption spectrum obtained in the ninth embodiment when pulsed laser light irradiation was performed under the first condition (irradiation light wavelength 532 nm, pulse width 100 μs). [Figure 37] Figure 37 shows the absorption spectrum obtained in the ninth embodiment when pulsed laser light irradiation was performed under the second condition (irradiation light wavelength 420 nm, pulse width 5 ns). [Figure 38] Figure 38 shows the absorption spectrum obtained in the ninth embodiment when pulsed laser light irradiation was performed under the third condition (irradiation light wavelength 420 nm, pulse width 35 fs). [Figure 39] Figure 39 is a graph showing the relationship between absorbance at a wavelength of 470 nm and the irradiation light energy when the irradiation light wavelength is 532 nm and the pulse widths are 5 ns and 100 μs, respectively, in the ninth embodiment. [Figure 40] Figure 40 is a graph showing the relationship between absorbance at a wavelength of 470 nm and the irradiation light energy when the irradiation light wavelength is 420 nm and the pulse widths are 5 ns and 35 fs, respectively, in the ninth embodiment. [Figure 41] Figure 41 is a chromatogram showing the results of HPLC component analysis of the solution obtained in the 9th example when pulsed laser light irradiation was performed under the third condition (irradiation light wavelength 420 nm, pulse width 35 fs, irradiation time 5 minutes). [Modes for carrying out the invention]

[0021] Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to these examples and is intended to include all modifications within the meaning and scope equivalent to the claims as shown in the claims.

[0022] Figure 1 is a flowchart of the cis-isomerization method of this embodiment. The cis-isomerization method of this embodiment is a method for cis-isomerizing a carotenoid compound and comprises a suspension preparation step S1, a light irradiation step S2, and a residual particle removal step S3.

[0023] In the suspension preparation step S1, a suspension is prepared by dispersing carotenoid compound particles in a solvent. The type of carotenoid compound can be any. The solvent can be any, but an organic solvent is preferred, such as ethanol, methanol, acetone, or hexane. It is preferable to degas the suspension to remove oxygen or to bubble it with an inert gas such as nitrogen or argon, but this is not necessary. Performing these treatments improves the cis-isomerization efficiency in the subsequent light irradiation step S2.

[0024] In the light irradiation step S2, the suspension prepared in the suspension preparation step S1 is irradiated with pulsed laser light to cis-isomerize the carotenoid compound particles dispersed in the solvent and dissolve them in the solvent. The pulse width of the pulsed laser light may be a value in a wide range including several ns to several hundred ns, and may be several hundred microseconds or several tens of fs.

[0025] The central wavelength of the pulsed laser light is preferably within the range of 275 nm to 700 nm, where the suspension absorbs light, and there is a more suitable range depending on the type of carotenoid compound. In the following, the wavelength range in which cis isomerization and photodissolution occur most efficiently is defined as the wavelength range in which cis isomerization and photodissolution occur efficiently, where the absorbance is 1 / 2 or more of the absorbance at the wavelength at which cis isomerization and photodissolution occur most efficiently (maximum wavelength).

[0026] The wavelength of light at which cis isomerization and photodissolution occur most efficiently is hardly absorbed in solutions where carotenoid compound particles are not dispersed (not in suspension). The wavelength of absorption maximum in the solution is λ peak Therefore, the wavelength range in which cis isomerization and photodissolution occur is λ peak ~λ peak The wavelength range is +180nm, and the wavelength range in which cis isomerization and photodissolution occur efficiently is λ peak +40nm~λ peak This is within the range of +120nm.

[0027] In the case of β-carotene, the suspension absorbs light when the central wavelength is in the range of 275 nm to 700 nm. Cis isomerization and photodissolution occur when the central wavelength is in the range of 450 nm to 600 nm. Cis isomerization and photodissolution occur efficiently when the central wavelength is in the range of 500 nm to 560 nm. Cis isomerization and photodissolution occur most efficiently when the central wavelength is 530 nm.

[0028] In the case of astaxanthin, the suspension absorbs light when the central wavelength is in the range of 350 nm to 700 nm. Cis isomerization and photodissolution occur when the central wavelength is in the range of 450 nm to 650 nm. Cis isomerization and photodissolution occur efficiently when the central wavelength is in the range of 530 nm to 620 nm. Cis isomerization and photodissolution occur most efficiently when the central wavelength is 580 nm.

[0029] In the case of lycopene, the suspension absorbs light when the central wavelength is in the range of 350 nm to 700 nm. Cis isomerization and photodissolution occur when the central wavelength is in the range of 500 nm to 620 nm. Cis isomerization and photodissolution occur efficiently when the central wavelength is in the range of 500 nm to 590 nm. Cis isomerization and photodissolution occur most efficiently when the central wavelength is 530 nm.

[0030] In the light irradiation step S2, the cis-isomerized carotenoid compound dissolves in the solvent. On the other hand, if particles of the carotenoid compound that were not cis-isomerized remain, these residual particles remain dispersed in the solvent. Therefore, in the residual particle removal step S3 after the light irradiation step S2, it is preferable to remove the particles remaining dispersed in the solvent by filtration or centrifugation.

[0031] The cis-isomerization method of this embodiment can cis-isomerize carotenoid compounds in a short time and with high efficiency compared to the cis-isomerization methods described in Patent Document 1 and Non-Patent Documents 1-3.

[0032] Carotenoid compounds cis-isomerized by the cis-isomerization method of this embodiment can be used as raw materials to manufacture foods, beverages, cosmetics, pharmaceuticals, and supplements. Foods, beverages, cosmetics, pharmaceuticals, and supplements containing cis-isomerized carotenoid compounds are expected to have health maintenance and beauty benefits based on the efficacy of the carotenoid compounds (e.g., antioxidant capacity, provitamin activity, enhanced eye function, prevention of eye diseases, etc.) because the carotenoid compounds are well absorbed by the body. Examples of foods and beverages containing carotenoid compounds include various beverages, as well as jellies, jams, sherbets, and the like.

[0033] Figure 2 shows the configuration of an apparatus suitable for performing the light irradiation step S2 in the cis isomerization method of this embodiment. The cis isomerization apparatus 1 shown in this figure comprises a pulsed laser light source 11, a dimming device 12, a beam splitter 13, a shutter 14, a sample cell 15, a beam trap 16, and a power meter 17.

[0034] The pulsed laser light source 11 outputs pulsed laser light to be irradiated onto the sample in the sample cell 15. The dimming unit 12 receives the pulsed laser light output from the pulsed laser light source 11, adjusts the intensity of the pulsed laser light, and outputs it to the beam splitter 13. The beam splitter 13 receives the pulsed laser light output from the dimming unit 12 and splits the pulsed laser light into two. The beam splitter 13 outputs one of the split beams to the shutter 14 and the other split beam to the power meter 17.

[0035] The shutter 14 receives the pulsed laser light, which is one of the branched beams output from the beam splitter 13. The shutter 14 can switch between allowing the pulsed laser light to pass through and blocking it, and sets the duration for which the pulsed laser light is irradiated onto the sample in the sample cell 15.

[0036] The sample cell 15 is a cell that contains the suspension prepared in the suspension preparation step S1. The sample cell 15 is preferably made of a material that absorbs pulsed laser light poorly, such as quartz glass. Furthermore, the sample cell 15 is preferably equipped with a function to agitate the suspension to prevent the particles in the suspension from settling.

[0037] The pulsed laser light that reaches the sample cell 15 from the shutter 14 is irradiated onto the suspension in the sample cell 15. A portion of the pulsed laser light is absorbed or scattered by the suspension, and the pulsed laser light that passes through the suspension is output to the beam trap 16. The beam trap 16 traps the pulsed laser light that has arrived from the sample cell 15.

[0038] The power meter 17 receives the pulsed laser light, which is the other branched beam output from the beam splitter 13, and measures the average power of the pulsed laser light. By adjusting the attenuator 12 based on the measurement value from the power meter 17 and the branching ratio in the beam splitter 13, the average power of the pulsed laser light irradiated onto the sample in the sample cell 15 can be set.

[0039] Next, examples of the cis-isomerization method will be described. In each example, suspensions were prepared, irradiated with light, and residual particles were removed under various conditions, after which the absorption spectrum of the sample solution was measured. Based on this absorption spectrum, the degree of photoisomerization of the carotenoid compound by light irradiation was evaluated. The vertical axis scale is not common in each figure showing the absorption spectrum.

[0040] (First embodiment) In the first example, the change in the absorption spectrum when a β-carotene ethanol suspension was irradiated with pulsed laser light was compared with that of a comparative example irradiated with a CW laser light. A suspension was prepared by adding 1 mg of β-carotene per 1 mL of ethanol and stirring thoroughly. For both the pulsed laser light and the CW laser light, the wavelength was 532 nm, the average power was 100 mW, the irradiation beam diameter was 1 mm, and the irradiation time ranged from 0 to 60 minutes. The pulse repetition frequency of the pulsed laser light was 500 Hz, and the pulse width was 5 ns. After laser irradiation, the sample solution was centrifuged to remove residual particles, and the resulting supernatant was diluted 100-fold. The absorption spectrum of the diluted solution was then measured.

[0041] Figure 3 shows the absorption spectrum obtained when pulsed laser light was irradiated in the first embodiment. Figure 4 shows the absorption spectrum obtained when continuous wave laser light was irradiated in the comparative example. As shown in these figures, in the comparative example where a suspension of β-carotene was irradiated with continuous wave laser light, no change in the absorption spectrum was observed. In contrast, when a suspension of β-carotene was irradiated with pulsed laser light, it was observed that the absorbance increased with increasing irradiation time. Furthermore, when pulsed laser light was irradiated, the solubility of β-carotene increased with increasing irradiation time.

[0042] The improvement in solubility and the change in the absorption spectrum upon irradiation with pulsed laser light are thought to be due to photoisomerization of the 9th or 13th position of β-carotene, which was all-trans before irradiation, to the cis state. Furthermore, component analysis of the supernatant after centrifugation following pulsed laser irradiation using high-performance liquid chromatography (HPLC) confirmed that β-carotene underwent cis isomerization upon pulsed laser irradiation. From the above, it can be concluded that irradiating an ethanol suspension of β-carotene with pulsed laser light can cause cis isomerization of the β-carotene in the suspension.

[0043] (Second example) In the second example, the change in the absorption spectrum was observed when pulsed laser light of various average powers was irradiated onto an ethanol suspension of β-carotene. A suspension was prepared by adding 1 mg of β-carotene to 1 mL of ethanol and stirring thoroughly. The pulsed laser light irradiated onto the suspension had a wavelength of 532 nm, an average power ranging from 0 mW to 600 mW, a pulse repetition frequency of 20 Hz, a pulse width of 5 ns, an irradiation beam diameter of 5.4 mm, and an irradiation time of 30 seconds. After laser irradiation, the suspension was filtered through a syringe filter with a pore size of 0.22 μm to remove residual particles, and the resulting solution was diluted 100-fold. The absorption spectrum of the diluted solution was then measured.

[0044] Figure 5 shows the absorption spectrum obtained in the second embodiment. Figure 6 is a graph showing the relationship between absorbance at a wavelength of 450 nm and the irradiation light intensity obtained in the second embodiment. As shown in these figures, in the low irradiation light intensity range (approximately 20 mW or less), the increase in absorbance was proportional to the square of the irradiation light intensity. As the irradiation light intensity increased, the absorbance increased in proportion to the irradiation light intensity. When the irradiation light intensity was 200 mW or higher, the change in absorbance in response to the change in irradiation light intensity tended to become smaller.

[0045] (Third embodiment) In the third example, changes in the absorption spectra of ethanol suspensions of various types of carotenoid compounds were observed when irradiated with pulsed laser light. The carotenoid compounds used were β-carotene, astaxanthin, lycopene, α-carotene, canthaxanthin, zeaxanthin, and lutein. The solvent used was ethanol or methanol. Each carotenoid compound was added to the solvent and thoroughly stirred to prepare a suspension, which was then placed in a 1 cm quartz cell. 500 μg of each of β-carotene, astaxanthin, lycopene, α-carotene, and canthaxanthin was added per 1 mL of ethanol. 300 μg of zeaxanthin was added per 1 mL of methanol. 50 mg of lutein granules with a 10% lutein content was added per 1 mL of methanol. For the pulsed laser light irradiated onto the suspension in a quartz cell, the wavelength was 532 nm, the average power was 100 mW, the pulse repetition frequency was 20 Hz, the pulse width was 5 ns, the irradiation beam diameter was 5 mm, and the irradiation time ranged from 0 to 10 minutes. After laser irradiation, the suspension was filtered through a syringe filter with a pore size of 0.22 μm to remove residual particles, and the resulting solution was diluted 100-fold. The absorption spectrum of the diluted solution was then measured.

[0046] Figure 7 shows the absorption spectrum obtained when β-carotene was used in the third example. Figure 8 shows the absorption spectrum obtained when astaxanthin was used in the third example. Figure 9 shows the absorption spectrum obtained when lycopene was used in the third example. Figure 10 shows the absorption spectrum obtained when α-carotene was used in the third example. Figure 11 shows the absorption spectrum obtained when canthaxanthin was used in the third example. Figure 12 shows the absorption spectrum obtained when zeaxanthin was used in the third example. Figure 13 shows the absorption spectrum obtained when lutein was used in the third example. As shown in these figures, for all carotenoid compounds, cis-isomerization of the carotenoid compounds in the suspension can be achieved by irradiating the ethanol suspension with pulsed laser light, and it can be seen that photodissolution and photoisomerization progress as the irradiation time increases.

[0047] (Fourth embodiment) In the fourth example, changes in the absorption spectrum of β-carotene suspensions prepared using various solvents were observed when irradiated with pulsed laser light. The solvents used were ethanol, methanol, acetone, and hexane. 1 mg of β-carotene was added to 1 mL of each solvent and thoroughly stirred to prepare a suspension, which was then placed in a 1 cm quartz cell. The pulsed laser light irradiated onto the suspension in the quartz cell had a wavelength of 532 nm, an average power of 15 mW, a pulse repetition frequency of 10 Hz, a pulse width of 5 ns, an irradiation beam diameter of 2 mm, and irradiation times ranging from 0 to 10 minutes. After laser irradiation, the sample solution was centrifuged to remove residual particles, and the resulting supernatant was diluted 100-fold. The absorption spectrum of the diluted solution was then measured.

[0048] Figure 14 shows the absorption spectrum obtained when ethanol was used in the fourth example. Figure 15 shows the absorption spectrum obtained when methanol was used in the fourth example. Figure 16 shows the absorption spectrum obtained when acetone was used in the fourth example. Figure 17 shows the absorption spectrum obtained when hexane was used in the fourth example. As shown in these figures, in all solvents, irradiating a suspension of β-carotene with pulsed laser light can cause cis-isomerization of the β-carotene in the suspension, and it can be seen that photodissolution and photoisomerization progress as the irradiation time increases.

[0049] (Fifth example) In the fifth example, the change in the absorption spectrum of astaxanthin suspensions prepared using various solvents was observed when pulsed laser light was irradiated. The solvents used were ethanol, methanol, acetone, and hexane. 500 μg of astaxanthin was added to 1 mL of each solvent and thoroughly stirred to prepare a suspension, which was then placed in a 1 cm quartz cell. Pulsed laser light irradiation, removal of residual particles, and absorption spectrum measurement were performed in the same manner as in the fourth example.

[0050] Figure 18 shows the absorption spectrum obtained when ethanol was used in the fifth example. Figure 19 shows the absorption spectrum obtained when methanol was used in the fifth example. Figure 20 shows the absorption spectrum obtained when acetone was used in the fifth example. Figure 21 shows the absorption spectrum obtained when hexane was used in the fifth example. As shown in these figures, with any of the solvents, the astaxanthin in the suspension can be cis-isomerized by irradiating the suspension with pulsed laser light, and it can be seen that photodissolution and photoisomerization progress as the irradiation time increases. In particular, the effect of cis-isomerization of astaxanthin is greater when ethanol or methanol is used as the solvent.

[0051] (Sixth embodiment) In the sixth example, changes in the absorption spectrum were observed when pulsed laser light of various wavelengths was irradiated onto an ethanol suspension of β-carotene. A suspension was prepared by adding 1 mg of β-carotene to 1 mL of ethanol and stirring thoroughly, and this suspension was placed in a 1 cm quartz cell. The pulsed laser light irradiated onto the suspension in the quartz cell had wavelengths ranging from 460 nm to 600 nm, an average power of 15 mW, a pulse repetition frequency of 10 Hz, a pulse width of 5 ns, an irradiation beam diameter of 2 mm, and an irradiation time of 15 minutes. A tunable pulsed laser light source was used. After laser irradiation, the sample solution was centrifuged to remove residual particles, and the resulting supernatant was diluted 100-fold. The absorption spectrum of the diluted solution was then measured.

[0052] Figure 22 shows the absorption spectra obtained in the sixth embodiment for each irradiation wavelength in the range of 460 nm to 520 nm. Figure 23 shows the absorption spectra obtained in the sixth embodiment for each irradiation wavelength in the range of 515 nm to 550 nm. Figure 24 shows the absorption spectra obtained in the sixth embodiment for each irradiation wavelength in the range of 540 nm to 600 nm. Figure 25 is a graph showing the relationship between absorbance at a wavelength of 445 nm and the irradiation wavelength obtained in the sixth embodiment.

[0053] In the case of a β-carotene suspension, light absorption occurs in the wavelength range of 275 nm to 700 nm. As shown in these figures, cis-isomerization of β-carotene in the suspension was possible by irradiating it with pulsed laser light at any wavelength within the broad wavelength range tested. Cis-isomerization of β-carotene was more effective when pulsed laser light with wavelengths within the range of 500 nm to 560 nm was irradiated onto the β-carotene suspension. In particular, cis-isomerization of β-carotene was most effective when pulsed laser light with a wavelength of 530 nm was irradiated onto the β-carotene suspension.

[0054] (Seventh Example) In the seventh example, changes in the absorption spectrum were observed when pulsed laser light of various wavelengths was irradiated onto an ethanol suspension of astaxanthin. A suspension was prepared by adding 500 μg of astaxanthin to 1 mL of ethanol and stirring thoroughly, and this suspension was placed in a 1 cm quartz cell. Pulsed laser light irradiation, residual particle removal, and absorption spectrum measurement were performed in the same manner as in the sixth example. However, the irradiation wavelength was in the range of 450 nm to 650 nm.

[0055] Figure 26 shows the absorption spectra obtained in the 7th embodiment for each irradiation wavelength in the range of 450 nm to 560 nm. Figure 27 shows the absorption spectra obtained in the 7th embodiment for each irradiation wavelength in the range of 550 nm to 590 nm. Figure 28 shows the absorption spectra obtained in the 7th embodiment for each irradiation wavelength in the range of 580 nm to 650 nm. Figure 29 is a graph showing the relationship between absorbance at 470 nm and irradiation wavelength obtained in the 7th embodiment.

[0056] In the case of astaxanthin suspension, light absorption occurs in the wavelength range of 350 nm to 700 nm. As shown in these figures, by irradiating the astaxanthin suspension with pulsed laser light at any wavelength within the broad wavelength range tested, the astaxanthin in the suspension could be cis-isomerized. When pulsed laser light with wavelengths within the range of 530 nm to 620 nm was irradiated onto the astaxanthin suspension, cis-isomerization of astaxanthin was more effective. In particular, when pulsed laser light with a wavelength of 580 nm was irradiated onto the astaxanthin suspension, cis-isomerization of astaxanthin was most effective.

[0057] (Eighth example) In the eighth example, changes in the absorption spectrum were observed when pulsed laser light of various pulse widths was irradiated onto an ethanol suspension of β-carotene. A suspension was prepared by adding 1 mg of β-carotene to 1 mL of ethanol and stirring thoroughly, and this suspension was placed in a 1 cm quartz cell. Pulsed laser light irradiation of the suspension in the quartz cell was performed under the following three conditions. In the first condition, the wavelength was 532 nm, the average power was 30 mW, the pulse repetition frequency was 5 Hz, the pulse width was 100 μs, the irradiation beam diameter was 1 mm, and the irradiation time was in the range of 0 to 9 minutes. In the second condition, the wavelength was 420 nm, the average power was 20 mW, the pulse repetition frequency was 20 Hz, the pulse width was 5 ns, the irradiation beam diameter was 1 mm, and the irradiation time was in the range of 0 to 20 minutes. Under the third condition, the wavelength was 420 nm, the average power was 87 mW, the pulse repetition frequency was 1 kHz, the pulse width was 35 fs, the irradiation beam diameter was 1 mm, and the irradiation time ranged from 0 to 20 minutes. After irradiation with laser light under each of the first to third conditions, the suspension was filtered through a syringe filter with a pore size of 0.22 μm to remove residual particles. The resulting solution was then diluted 10-fold, and the absorption spectrum of the diluted solution was measured.

[0058] Figure 30 shows the absorption spectrum obtained in the 8th embodiment when pulsed laser light irradiation was performed under the first condition (irradiation wavelength 532 nm, pulse width 100 μs). Figure 31 shows the absorption spectrum obtained in the 8th embodiment when pulsed laser light irradiation was performed under the second condition (irradiation wavelength 420 nm, pulse width 5 ns). Figure 32 shows the absorption spectrum obtained in the 8th embodiment when pulsed laser light irradiation was performed under the third condition (irradiation wavelength 420 nm, pulse width 35 fs). As shown in these figures, by irradiating a suspension of β-carotene with pulsed laser light at any of the pulse widths tried, it was possible to cis-isomerize the β-carotene in the suspension. From this, it can be seen that cis-isomerization of β-carotene can be achieved by irradiating a suspension with pulsed laser light with a pulse width ranging from at least several tens of fs to several hundred μm.

[0059] Figure 33 is a graph showing the relationship between absorbance at a wavelength of 450 nm and the irradiation energy when the irradiation wavelength was 532 nm and the pulse widths were 5 ns and 100 μs, respectively, in the 8th embodiment. Figure 34 is a graph showing the relationship between absorbance at a wavelength of 450 nm and the irradiation energy when the irradiation wavelength was 420 nm and the pulse widths were 5 ns and 35 fs, respectively, in the 8th embodiment. As shown in these figures, regardless of whether microsecond pulsed laser light, nanosecond pulsed laser light, or femtosecond pulsed laser light was used for irradiation, the cis isomerization of β-carotene progressed as the irradiation energy increased. Furthermore, when the irradiation energy was the same, cis isomerization of β-carotene was most effective when nanosecond pulsed laser light was used to irradiate the β-carotene suspension.

[0060] Figure 35 is a chromatogram showing the results of HPLC component analysis of the solution obtained when pulsed laser light irradiation was performed under the third condition (irradiation wavelength 420 nm, pulse width 35 fs, irradiation time 5 minutes) in the eighth example. This chromatogram was obtained at an observation wavelength of 455 nm. As can be seen, before irradiation with femtosecond pulsed laser light, the all-trans isomer at the 17.2 min position accounts for most of the composition, but after irradiation with femtosecond pulsed laser light for 5 minutes, the all-trans isomer at the 17.2 min position increases, and the 13-cis isomer at the 14.2 min position and the 9-cis isomer at the 19.4 min position appear. This indicates that photoisomerization occurs due to femtosecond pulsed laser light irradiation, and the cis isomer is formed.

[0061] (9th example) In the ninth example, changes in the absorption spectrum were observed when pulsed laser light of various pulse widths was irradiated onto an ethanol suspension of astaxanthin. A suspension was prepared by adding 500 μg of astaxanthin to 1 mL of ethanol and stirring thoroughly, and this suspension was placed in a 1 cm quartz cell. Pulsed laser light irradiation, removal of residual particles, and absorption spectrum measurement were performed in the same manner as in the eighth example.

[0062] Figure 36 shows the absorption spectrum obtained in the 9th embodiment when pulsed laser light irradiation was performed under the first condition (irradiation wavelength 532 nm, pulse width 100 μs). Figure 37 shows the absorption spectrum obtained in the 9th embodiment when pulsed laser light irradiation was performed under the second condition (irradiation wavelength 420 nm, pulse width 5 ns). Figure 38 shows the absorption spectrum obtained in the 9th embodiment when pulsed laser light irradiation was performed under the third condition (irradiation wavelength 420 nm, pulse width 35 fs). As shown in these figures, by irradiating the astaxanthin suspension with pulsed laser light at any of the pulse widths tried, it was possible to cis-isomerize the astaxanthin in the suspension. From this, it can be seen that cis-isomerization of astaxanthin can be achieved by irradiating the suspension with pulsed laser light with a pulse width in the range of at least tens of fs to several hundred μm.

[0063] Figure 39 is a graph showing the relationship between absorbance at a wavelength of 470 nm and the irradiation energy when the irradiation wavelength was 532 nm and the pulse widths were 5 ns and 100 μs, respectively, in the ninth example. Figure 40 is a graph showing the relationship between absorbance at a wavelength of 470 nm and the irradiation energy when the irradiation wavelength was 420 nm and the pulse widths were 5 ns and 35 fs, respectively, in the ninth example. As shown in these figures, when irradiated with nanosecond pulsed laser light, the effect of cis isomerization of astaxanthin was greater compared to when irradiated with microsecond pulsed laser light, and the cis isomerization of astaxanthin progressed as the irradiation energy increased. When irradiated with microsecond pulsed laser light and femtosecond pulsed laser light, respectively, the change in the degree of cis isomerization of astaxanthin was small even when the irradiation energy was increased. Comparing femtosecond pulsed laser irradiation with nanosecond pulsed laser irradiation, cis isomerization was more advanced with femtosecond pulsed laser irradiation in the range of low irradiation light energy, while cis isomerization was more advanced with nanosecond pulsed laser irradiation in the range of high irradiation light energy.

[0064] Figure 41 is a chromatogram showing the results of HPLC component analysis of the solution obtained in the 9th example when pulsed laser light irradiation was performed under the third condition (irradiation wavelength 420 nm, pulse width 35 fs, irradiation time 5 minutes). This chromatogram was obtained at an observation wavelength of 476 nm. As can be seen, although the amount of change is small due to the large amount of decomposition, it can be seen that the cis isomer peak at the 36-minute position has increased after irradiation with femtosecond pulsed laser light for 5 minutes, indicating that photoisomerization also occurs with femtosecond pulsed laser light irradiation. [Explanation of Symbols]

[0065] 1...Cis isomerization apparatus, 11...Pulsed laser light source, 12...Density reducer, 13...Beam splitter, 14...Shutter, 15...Sample cell, 16...Beam trap, 17...Power meter.

Claims

1. A suspension preparation step involves preparing a suspension in which particles of a carotenoid compound are dispersed in a solvent, A light irradiation step involves irradiating the suspension with pulsed laser light to cis-isomerize the carotenoid compound particles and dissolve them in the solvent. A cis-isomerization method comprising the following features.

2. The method further comprises a residual particle removal step for removing particles of the carotenoid compound that remain and are dispersed in the solvent after the light irradiation step. The cis-isomerization method according to claim 1.

3. The solvent is ethanol, methanol, acetone, or hexane. The cis-isomerization method according to claim 1.

4. The carotenoid compound is α-carotene, β-carotene, lycopene, astaxanthin, or lutein. The cis-isomerization method according to claim 1.

5. In the light irradiation step, pulsed laser light having a central wavelength within the wavelength range of 275 nm to 700 nm is irradiated onto the suspension. The cis-isomerization method according to claim 1.

6. In the light irradiation step, if the carotenoid compound is β-carotene, pulsed laser light having a central wavelength in the wavelength range of 450 nm to 600 nm is irradiated onto the suspension. The cis-isomerization method according to claim 1.

7. In the light irradiation step, if the carotenoid compound is astaxanthin, pulsed laser light having a central wavelength in the wavelength range of 450 nm to 650 nm is irradiated onto the suspension. The cis-isomerization method according to claim 1.

8. In the light irradiation step, if the carotenoid compound is lycopene, pulsed laser light having a central wavelength in the wavelength range of 500 nm to 620 nm is irradiated onto the suspension. The cis-isomerization method according to claim 1.

9. A method for producing food and beverages using a carotenoid compound that has been cis-isomerized by the cis-isomerization method described in any one of claims 1 to 8 as a raw material.

10. A method for producing cosmetics using a carotenoid compound that has been cis-isomerized by the cis-isomerization method described in any one of claims 1 to 8 as a raw material.

11. A method for producing a pharmaceutical product using a carotenoid compound that has been cis-isomerized by the cis-isomerization method described in any one of claims 1 to 8 as a raw material.

12. A method for producing a supplement using a carotenoid compound that has been cis-isomerized by the cis-isomerization method described in any one of claims 1 to 8 as a raw material.

Images