Control method and control system for refining treatment by monitoring color value, and method for producing polyhydroxyalkanoate resin

Abstract

According to the present invention, by monitoring the color value during the process of purifying a crude solution containing polyhydroxyalkanoate (PHA) and controlling the conditions of the purification process in real time based on the color value, it is possible to reliably produce a high-quality polyhydroxyalkanoate resin with excellent color development properties.

Description

[Technical Field]

[0001] The present disclosure relates to a method and system for controlling a purification process by monitoring color values in the purification process, and a method for producing a polyhydroxyalkanoate resin. The present disclosure also relates to a method for producing a polyhydroxyalkanoate resin with excellent color using the same. [Background technology]

[0002] Polyhydroxyalkanoates (PHAs) are biodegradable polymers composed of several hydroxylcarboxylic acids that are produced by many microorganisms and used as intracellular storage materials. Polyhydroxyalkanoates have similar physical properties to conventional petroleum-derived synthetic polymers such as polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), polybutylene succinate terephthalate (PBST), and polybutylene succinate adipate (PBSA), and are completely biodegradable and highly biocompatible.

[0003] Specifically, polyhydroxyalkanoates are natural thermoplastic polyester polymers that accumulate within microbial cells. Because they are biodegradable materials, they can be composted and ultimately decompose into carbon dioxide, water, and organic waste without producing harmful waste. In particular, polyhydroxyalkanoates are biodegradable in both soil and marine environments, making them environmentally friendly.

[0004] In the production method of polyhydroxyalkanoate resin, PHA particles formed and accumulated in microbial cells are normally surrounded by proteins, phospholipids, polypeptides, etc. even after extraction. To remove such impurities, additional purification processes such as decolorization and deproteinization are carried out. Prior art literature

[0005] (Patent Document 1) Korean Patent Publication No. 2001-0009719 Summary of the Invention [Problem to be solved by the invention]

[0006] In the manufacturing method of polyhydroxyalkanoate resin, various impurities, including cell-derived components, are removed through decolorization and deproteinization. While performing this process, there is a problem in that it is not possible to qualitatively or quantitatively distinguish between impurities present in solid PHA particles and liquid in real time. In particular, impurities remaining in PHA resin particles must be strictly controlled in mass production because they can cause discoloration and deterioration of polymer properties during processing. However, due to the above-mentioned problems, real-time control of impurity removal processing is extremely difficult.

[0007] As a result of the inventors' investigations, they have devised a process that enables the stable production of polyhydroxyalkanoate resins with excellent color by monitoring the color value of the treatment solution during the purification process, adjusting purification conditions such as decolorization based on the color value, and predicting the color value of the final product.

[0008] It is an object of the present disclosure to provide a method and system for controlling a refining process through monitoring color value in the refining process, and a process using the same for producing polyhydroxyalkanoate resins with excellent color quality. [Means for solving the problem]

[0009] According to one aspect of the present disclosure, there is provided a method for controlling a purification process for producing a polyhydroxyalkanoate (PHA) resin, in which the color value of a treatment liquid or its supernatant during the purification process, or of a purified liquid or its supernatant after the purification process, is measured, and the purification process is controlled based on the measured color value.

[0010] In one form, the measurement of color value is a in the CIE LAB color space. * Including the measurement of the a value of the above-mentioned treated solution or its supernatant * Based on the change in value, the above purification treatment conditions can be adjusted.

[0011] In another embodiment, a * The change in value is due to the a * value and a of the crude solution or its supernatant * It may be confirmed by comparing the value with that of the crude solution or its supernatant before the purification treatment, or the a value of the treatment solution or its supernatant during the purification treatment. * This may be confirmed by observing the change in value over time.

[0012] In another embodiment, the color value measurement is a * The a value of the purified solution and its supernatant is measured. * Based on the value, the b of polyhydroxyalkanoate resin in the CIE LAB color space * The value may be predicted.

[0013] Another aspect of the present disclosure provides a control system for a purification process, comprising: a purification unit that performs a purification process for producing a polyhydroxyalkanoate (PHA) resin; a monitoring unit that measures the color value of the treatment liquid or its supernatant during the purification process, or the color value of the purified liquid and its supernatant after the purification process; and a control unit that controls the purification process based on the measured color value.

[0014] Another aspect of the present disclosure provides a method for producing a polyhydroxyalkanoate (PHA) resin from a crude solution obtained by a purification process of the PHA resin, the method comprising at least one of the following steps: (a) measuring the color value of the treatment solution or its supernatant during the purification process; and (b) measuring the color value of the purified solution and its supernatant after the purification process.

[0015] In one embodiment, the measurement of color value in step (a) is performed using a * Including the measurement of the a value of the treated solution or its supernatant * Based on the change in value, the purification process conditions may be adjusted.

[0016] In another embodiment, the treatment comprises the step of: * The method further comprises measuring the a value of the treated solution or its supernatant. * of the above crude solution or its supernatant * Changes to values may be checked.

[0017] In another embodiment, the purification process comprises a decolorization process, which is performed sequentially using a first oxidant, a second oxidant, or both, wherein the first oxidant can include sodium hypochlorite (NaClO) and the second oxidant can include hydrogen peroxide (H0).

[0018] In another embodiment, when the decolorization treatment is carried out using a second oxidizing agent and the following relationship (1A) is satisfied, the amount of the oxidizing agent added in the decolorization treatment may be increased. a0 < a30 (1A) In the relationship (1A), a0 is the a of the crude solution * a30 is the a value of the treated liquid after the addition of the second oxidizing agent * value.

[0019] In another embodiment, the decolorization treatment is carried out by sequentially using a first oxidizing agent and a second oxidizing agent, and when the following relationship (1B) is satisfied, the amount of at least one of the first oxidizing agent and the second oxidizing agent added in the decolorization treatment may be increased. a0'>a30' (1B) In the relationship (1B), a0' is the a of the supernatant of the crude solution. * a30' is the a value of the supernatant of the treated liquid after the addition of the first oxidizing agent. * value.

[0020] In one embodiment, the color value in step (b) is measured by measuring the color value of the purified liquid and its supernatant. * This includes the measurement of the b value of polyhydroxyalkanoate resins in the CIE LAB color space. * The values are a of the purified liquid and its supernatant * The prediction may be based on the value.

[0021] In another embodiment, the polyhydroxyalkanoate resin * The value may be predicted from the following relationship (2A): b * =Y+(X1×a1)+(X2×a2)(2A)

[0022] In the above relationship (2A), a1 is the a of the purified liquid * a2 is the a value of the supernatant of the purified solution * values, Y is 10 to 21, X1 is -2.5 to 4.0, and X2 is -3.5 to 3.0. More specifically, Y is 14.68 to 16.68, X1 is -0.39 to 1.61, and X2 is -1.35 to 0.65.

[0023] In another embodiment, the polyhydroxyalkanoate resin * The value may be predicted from the following relationship (2B): b * =Y'+(X1'×a1')+(X2'×a2')(2B) In the relationship (2B), a1' is the a of the purified liquid * a2' is the value of the supernatant of the purified solution * The values are Y' between 4 and 15, X1' between -7 and -1, and X2' between -8 and -1. More specifically, Y' is between 8.15 and 10.15, X1' is between -5.15 and -3.15, and X2' is between -5.04 and -3.04.

[0024] In another aspect, the predicted polyhydroxyalkanoate resin b * Value is the target b * If it is greater than this value, additional purification steps may be performed.

[0025] In another embodiment, the crude solution containing polyhydroxyalkanoate may be prepared by a method including a process of performing solid-liquid separation of a fermentation liquid containing polyhydroxyalkanoate to obtain biomass, a process of mixing the biomass with an additive containing a surfactant to obtain a suspension, a process of crushing the biomass in the suspension to obtain a slurry, and a process of performing solid-liquid separation of the slurry. [Effects of the Invention]

[0026] According to the method and system of the present disclosure, by monitoring the color value during the purification process and adjusting the purification process conditions based on the color value, it is possible to more effectively remove impurities, predict the color value of the final product, and take measures in advance, thereby stably preparing a polyhydroxyalkanoate resin with excellent color development properties. [Brief explanation of the drawings]

[0027] [Figure 1] Figure 1 shows how the refining process can be controlled by monitoring the color value. [Figure 2a] FIG. 2a shows a method for producing a PHA resin, including a purification process (using only H2O2 for decolorization), according to one embodiment. [Figure 2b] FIG. 2b shows another embodiment of a method for producing PHA resin including a purification process (using NaClO2 and H2O2 for decolorization). [Figure 3a] FIG. 3a shows the results of monitoring the color value over time during the purification process in the method for producing a PHA resin according to the embodiment. [Figure 3b] FIG. 3b shows the results of monitoring color value over time during the purification process in a method for producing a PHA resin according to another embodiment. [Figure 4a] FIG. 4a shows the correlation between the predicted b* value and the actually measured b* value of a PHA resin in a method for producing a PHA resin according to one embodiment. [Figure 4b] FIG. 4b shows the correlation between the predicted b* value and the actually measured b* value of a PHA resin in a method for producing a PHA resin according to another embodiment. [Figure 5] FIG. 5 shows a schematic diagram of the concept of predicting the color value of the final PHA resin envisioned in the present disclosure. [Figure 6] FIG. 6 shows the concepts of L*, a*, and b* in the CIE (Commission Internationale de l'Eclairage) LAB color space. DETAILED DESCRIPTION OF THE INVENTION

[0028] The present disclosure will now be described in further detail with reference to various embodiments.

[0029] The terms used herein to distinguish between components are not intended to limit the scope of the present disclosure. Furthermore, unless otherwise specified, the singular forms are intended to include the plural forms.

[0030] In this specification, the term "comprising" is used to explicitly identify certain features, regions, steps, treatments, elements, and / or components, and does not exclude the presence or addition of other features, regions, steps, treatments, components, elements, and / or components, unless specifically stated to the contrary.

[0031] In this specification, terms such as "first," "second," etc. are used to describe various components, but these components should not be bound by these terms. These terms are used to distinguish one element from another.

[0032] Control of the refining process by monitoring color value and preparing PHA resin One aspect of the present disclosure provides a method for controlling a polyhydroxyalkanoate (PHA) resin purification process by monitoring color value. The purification process control method of the present invention measures the color value of a treatment solution or its supernatant in a purification process for producing a polyhydroxyalkanoate (PHA) resin, or of a purified solution or its supernatant after the purification process, and controls the purification process based on the measured color value.

[0033] The treatment liquid is obtained during the purification process (e.g., decolorization and deproteinization) of a crude PHA solution, and may be a purified liquid obtained after the purification process is completed. The crude solution, treatment liquid, and purified liquid each contain PHA, impurities, a solvent, etc., and may be in the form of a solution, suspension, dispersion, slurry, etc. Alternatively, the color value may be measured by separating a supernatant from the crude solution, treatment liquid, or purified liquid. The supernatant refers to the upper liquid excluding insoluble solids that have settled to the bottom by centrifugation, sedimentation, etc.

[0034] As described above, the method of the present disclosure provides for monitoring color values during processing, and has the advantages of not requiring a separate pretreatment of the sample to be analyzed, and enabling rapid analysis and immediate confirmation of results. The color values monitored in the present disclosure are a in the CIE LAB color space, which can be measured using a spectrophotometer. * and b * Figure 6 shows the L * , a * , b * As shown in Figure 6, a * The value indicates whether the color is closer to red or green. If it's negative, it's closer to green. If it's positive, it's closer to red. * The value indicates whether the color is closer to blue or yellow. If it's negative, it's closer to blue. If it's positive, it's closer to yellow.

[0035] In the production process of polyhydroxyalkanoate resin, various types of impurities, including cell-derived components, are removed by the purification process. The purification process has the problem of being unable to distinguish between solid PHA particles and impurities present in the liquid in real time, either qualitatively or quantitatively. In particular, impurities remaining in PHA resin particles must be strictly controlled in mass production processes, as they can cause discoloration and deterioration of polymer properties during processing. However, due to the above-mentioned issues, real-time control of the impurity removal process has been extremely difficult.

[0036] The present inventors have investigated the b * The value increases as the amount of impurities increases, so b * The color value was thought to reflect the content of impurities in the final PHA resin to some extent. Therefore, the inventors analyzed the data obtained by monitoring the color value. In some purification processes, the a measured during the purification process * The value is the b value of the most final PHA resin. * It was found that there was a significant correlation with the value (see Table 1).

[0037] Therefore, the measurement of color value in this disclosure is a in the CIE LAB color space. * This may include measuring values.

[0038] 1 shows a method for controlling the refining process by monitoring the color value. Referring to FIG. 1, this method comprises monitoring the color value of the processing solution or its supernatant in the CIE LAB color space during the refining process. * and / or after the purification process, the a value of the purified solution and its supernatant is monitored (S100). * and monitoring the value (S200).

[0039] In one embodiment, the above-mentioned treatment liquid or its supernatant liquid * Based on the change in value, the purification process conditions can be adjusted.

[0040] For example, a of the treated liquid or its supernatant * The value is the a of the crude solution or its supernatant before purification treatment.* This can be confirmed by comparing the value of the treated solution or its supernatant. * This may be confirmed by checking the change in value over time during the purification process.

[0041] Specifically, at the start of the purification process, the a of the treatment liquid or its supernatant * The change in the value is monitored, and the normal or abnormal state is distinguished based on the increase or decrease. If there is an abnormality, the amount of oxidizing agent added in the decolorization treatment can be increased. For this purpose, the treatment is performed by increasing the amount of oxidizing agent added to the crude solution or its supernatant. * The method further comprises measuring the a value of the treated solution or its supernatant. * of the above crude solution or its supernatant * Changes to values may be checked.

[0042] In another example, while carrying out the purification treatment, * The change in the value is continuously monitored, and the normal or abnormal state is judged based on the increase or decrease. If an abnormality occurs, the amount of oxidizing agent added in the decolorization treatment can be increased. For this purpose, after the start of the purification treatment, the a of the treatment solution or its supernatant is measured at regular time intervals, for example, every 10 minutes, every 20 minutes, or every 30 minutes. * Repeatedly measure these a * The values are compared to determine whether there is a decrease or increase.

[0043] According to another embodiment of the present invention, the b * The values are a of the purified liquid and its supernatant * can be predicted based on the value.

[0044] One aspect of the present disclosure provides a control system for a polyhydroxyalkanoate (PHA) resin purification process by monitoring color values. The purification control system of the present invention includes a purification unit that performs a purification process to produce a polyhydroxyalkanoate (PHA) resin, a monitoring unit that measures the color values of the treatment solution or its supernatant during the purification process, or the color values of the purified solution and its supernatant after the purification process, and a control unit that controls the purification process based on the measured color values.

[0045] The purification section may include, for example, a decolorization section and a deproteinization section. The crude PHA solution is sent to the decolorization section to be decolorized, and then the treatment solution is passed through the deproteinization section to obtain a purified solution in which deproteinization is complete. The decolorization section may also contain an acidic or alkaline component for pH adjustment and one or more oxidizing agents for decolorization. Decolorization may be performed at least once. The protein removal section may also contain an acidic or alkaline component for pH adjustment and one or more proteases. Therefore, the decolorization section and the deproteinization section each include a reactor, and the reactor may include an inlet for feeding the raw material and sample, an outlet for discharging the treatment solution or purified solution, and a temperature control section. The reactors may also include a connector such as a tube for connecting the inlet and outlet.

[0046] The monitoring unit may include, for example, a spectrophotometer capable of measuring the color value of a sample. The monitoring unit may also include an extractor that extracts a sample of the crude solution, the treated solution, or the purified solution from each reactor installed in the purification unit. The monitoring unit may also include a centrifuge that separates the supernatant from the sample of the treated solution or the purified solution.

[0047] The control unit may include an analysis unit that receives and analyzes (compares, reads, determines, predicts, etc.) the color value information measured by the monitoring unit. The control unit and the monitoring unit may be electrically connected to transmit such color value information. The control unit may further include a processing unit that adjusts the refining treatment conditions or provides feedback on whether or not to perform additional refining treatment based on the results of the analysis by the analysis unit. The control unit is also electrically connected to the refining unit to control the flow of the refining treatment in response to feedback sent from the processor.

[0048] According to the method and system of the present disclosure, the results of monitoring the color value during processing can be applied to the purification process in real time, allowing for more effective removal of impurities. The color value of the final PHA resin can be predicted and addressed in advance, allowing for the stable preparation of PHA resins with excellent color development properties.

[0049] Another aspect of the present disclosure provides a method for producing a polyhydroxyalkanoate (PHA) resin by monitoring the color value, which comprises at least one of the following steps: (a) measuring the color value of a treatment solution or its supernatant during a purification treatment, and (b) measuring the color value of a purified solution or its supernatant after the purification treatment.

[0050] In the process of the present disclosure, the purification treatment may include, for example, a decolorization treatment and a deproteinization treatment.

[0051] Hereinafter, each treatment and step of the manufacturing method according to the present disclosure will be described in detail.

[0052] Polyhydroxyalkanoates Polyhydroxyalkanoates (PHAs) can be classified into crystalline, semi-crystalline, and amorphous polyhydroxyalkanoates depending on their molecular structure.

[0053] In one embodiment, the polyhydroxyalkanoate may include amorphous polyhydroxyalkanoate. Due to its unique flexibility and adhesiveness, amorphous polyhydroxyalkanoate is difficult to repeatedly separate solids and liquids and wash during aqueous purification. The final purified PHA has a high impurity content, making it difficult to commercialize. According to the present disclosure, the color of the final product can be significantly improved by decolorizing the amorphous PHA using two oxidizing agents in sequence during the purification process.

[0054] In another embodiment, the polyhydroxyalkanoate may include a semi-crystalline polyhydroxyalkanoate. According to another embodiment, the polyhydroxyalkanoate may include a crystalline polyhydroxyalkanoate. According to another embodiment, the polyhydroxyalkanoate may include two or more of an amorphous polyhydroxyalkanoate, a semi-crystalline polyhydroxyalkanoate, and a crystalline polyhydroxyalkanoate.

[0055] The polyhydroxyalkanoate may contain at least one repeating unit selected from the group consisting of 2-hydroxybutyric acid (2-HB), 3-hydroxybutyric acid (3-HB), 3-hydroxypropionic acid (3-HP), 3-hydroxybutyric acid (3-HV), 3-hydroxyself-acid (3-HH), 3-hydroxyheptanoic acid (3-HHep), 3-hydroxyoctanoic acid (3-HO), 3-hydroxynonanoic acid (3-HN), 3-hydroxydecanoic acid (3-HD), 3-hydroxydodecanoic acid (3-HDd), 4-hydroxybutyric acid (4-HB), 4-hydroxybutyric acid (4-HV), 5-hydroxybutyric acid (5-HV), and 6-hydroxyself-acid (6-HH).

[0056] Furthermore, the polyhydroxyalkanoate may contain isomers. For example, the polyhydroxyalkanoate may contain structural isomers, enantiomers, or geometric isomers. Specifically, the polyhydroxyalkanoate may contain structural isomers.

[0057] The polyhydroxyalkanoate may be a homopolymer or a copolymer, and in one embodiment, the polyhydroxyalkanoate may include a copolymer, specifically a copolymer containing two or more different repeat units randomly arranged in the polymer chain.

[0058] For example, the polyhydroxyalkanoate may contain 4-hydroxybutyric acid (4-HB) repeat units. For example, the content of 4-HB (4-hydroxybutyric acid) repeat units in the polyhydroxyalkanoate may be 0.1% by weight or more, 1% by weight or more, 5% by weight or more, 10% by weight or more, 20% by weight or more, 30% by weight or more, 40% by weight or more, 50% by weight or more, 60% by weight or more, 100% by weight or less, 99% by weight or less, 90% by weight or less, 80% by weight or less, 70% by weight or less, or 60% by weight or less, based on the total weight of the polyhydroxyalkanoate. Specifically, the polyhydroxyalkanoate may contain 25% by weight or more of 4-hydroxybutyric acid (4-HB) repeat units.

[0059] Specifically, the polyhydroxyalkanoate may be a copolymer containing 4-HB repeating units. Examples of repeating units that the polyhydroxyalkanoate may contain in addition to 4-HB include at least one selected from the group consisting of lactic acid, glycolic acid, 2-hydroxybutyric acid (2-HB), 3-hydroxybutyric acid (3-HB), 3-hydroxypropionic acid (3-HP), 3-hydroxybutyric acid (3-HV), 3-hydroxyself-acid (3-HH), 3-hydroxyheptanoic acid (3-HHep), 3-hydroxyoctanoic acid (3-HO), 3-hydroxynonanoic acid (3-HN), 3-hydroxydecanoic acid (3-HD), 3-hydroxydodecanoic acid (3-HDd), 4-hydroxybutyric acid (4-HV), 5-hydroxybutyric acid (5-HV), and 6-hydroxyself-acid (6-HH).

[0060] More specifically, the polyhydroxyalkanoate may contain, in addition to the 4-HB repeating unit, one or more repeating units selected from the group consisting of 3-HB, 3-HP, 3-HH, 3-HV, 4-HV, 5-HV, and 6-HH. For example, the polyhydroxyalkanoate may contain a copolymer containing a 4-HB repeating unit and a 3-HB repeating unit. Specifically, the polyhydroxyalkanoate may contain poly-3-hydroxybutyrate-co-4-hydroxybutyrate (P3HB-co-4HB).

[0061] The PHA may contain one or more PHAs. For example, it may contain a first PHA, a second PHA, or a mixture thereof. For example, the first PHA may be an amorphous PHA and the second PHA may be a semi-crystalline PHA. The first PHA may contain 4-HB repeating units in an amount of, for example, 15% to 60% by weight, 15% to 55% by weight, 20% to 55% by weight, 25% to 55% by weight, 30% to 55% by weight, 35% to 55% by weight, 20% to 50% by weight, 25% to 50% by weight, 30% to 50% by weight, 35% to 50% by weight, or 20% to 40% by weight. The second PHA may contain 4-HB repeat units in an amount of, for example, 0.1% to 30% by weight, 0.5% to 30% by weight, 1% to 30% by weight, 3% to 30% by weight, 1% to 28% by weight, 1% to 25% by weight, 1% to 24% by weight, 1% to 20% by weight, 1% to 15% by weight, 2% to 25% by weight, 3% to 25% by weight, 3% to 24% by weight, 5% to 24% by weight, 5% to 20% by weight, more than 5% to less than 20% by weight, 7% to 20% by weight, 10% to 20% by weight, 15% to 25% by weight, or 15% to 24% by weight. The PHA may also be a mixture of the first PHA and the second PHA in a weight ratio of 20:80 to 80:20 or 30:70 to 70:30.

[0062] Crude polyhydroxyalkanoate solution The crude polyhydroxyalkanoate solution may be prepared by a fermentation process.

[0063] The method for producing polyhydroxyalkanoate (PHA) by fermentation may be carried out by a known method, for example, by using a wild-type or genetically modified microorganism cultured on a specific substrate to produce polyhydroxyalkanoate by fermentation, and is not particularly limited.

[0064] Polyhydroxyalkanoates produced by fermentation accumulate within the cells of microorganisms, and therefore require separation and purification.

[0065] For example, biomass containing polyhydroxyalkanoate is separated from the fermentation broth, and a surfactant is added to disrupt the microbial cells, thereby isolating only the polyhydroxyalkanoate.

[0066] As an example, a crude solution containing polyhydroxyalkanoate (PHA) may be prepared by a method in which a fermentation liquid containing PHA is subjected to solid-liquid separation to obtain biomass, an additive containing a surfactant is mixed with the biomass to obtain a suspension, the biomass in the suspension is crushed to obtain a slurry, and the slurry is subjected to solid-liquid separation.

[0067] First, the fermentation liquid formed by the microorganisms is subjected to solid-liquid separation by mechanical separation methods such as centrifugation or membrane separation, or other known methods, to separate the biomass containing cells in which polyhydroxyalkanoate (PHA) has accumulated.

[0068] The biomass thus separated may be mixed with a solvent to adjust the solids concentration. A surfactant may also be mixed with the biomass. For example, an anionic surfactant or a nonionic surfactant may be used as the surfactant. Specifically, sodium laureth sulfate, sodium lauryl sulfate, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, etc. may be used. This may result in a suspension containing biomass, a surfactant, etc.

[0069] The biomass in the suspension is then pulverized. The pulverization may be performed by mechanical pulverization (physical pulverization) or chemical pulverization (non-mechanical pulverization). For example, ultrasonic pulverization, high-pressure pulverization, or mill pulverization may be used. Ultrasonic pulverization may be performed, for example, at an energy level of 20 Hz or higher for 10 to 60 minutes. High-pressure pulverization may be performed, for example, at a pressure of 10 bar or higher for 1 to 60 minutes. Milling may also be performed using a colloid mill, bead mill, or ball mill for 1 to 60 minutes.

[0070] As a result of the pulverization, a slurry containing polyhydroxyalkanoate fine particles and cell-derived impurities such as cell walls may be obtained. The slurry is subjected to solid-liquid separation by a mechanical separation method such as centrifugation or membrane separation, or by other known methods, to obtain a crude polyhydroxyalkanoate solution.

[0071] The crude solution of polyhydroxyalkanoate contains trace amounts of cell-derived impurities (proteins, lipids, etc.), and therefore requires further purification.

[0072] For example, the protein content in the crude solution may be 3.5% by mass or less, 3% by mass or less, 2.7% by mass or less, or 2.5% by mass or less, or 1% by mass or more, 1.5% by mass or more, or 0.1% by mass or more, based on the total solid weight in the crude solution.

[0073] Furthermore, the lipid content in the crude solution may be 1.5 wt % or less, 1.3 wt % or less, 1 wt % or less, or 0.7 wt % or less, or 0.1 wt % or more, 0.2 wt % or more, or 0.3 wt % or more, based on the total solid weight in the crude solution.

[0074] Furthermore, the solid content in the crude solution may be 1% by mass or more, 3% by mass or more, 5% by mass or more, 7% by mass or more, or 10% by mass or more, relative to the total weight of the crude solution, and may be 80% by mass or less, 50% by mass or less, 30% by mass or less, 20% by mass or less, or 15% by mass or less.

[0075] The supernatant liquid can also be separated from the crude solution prepared in this manner by centrifugation, sedimentation, etc., and used to measure the color value, which will be described in detail in the section on monitoring color value below.

[0076] Refining process The purification process for producing a PHA resin from a crude solution may include a decolorization process.

[0077] The decolorization treatment may be carried out by adding one or more oxidizing agents to the crude solution. Specifically, the decolorization treatment may be carried out using a first oxidizing agent, a second oxidizing agent, or both in sequence. The first oxidizing agent may include sodium hypochlorite (NaClO2), and the second oxidizing agent may include hydrogen peroxide (H2O2).

[0078] In one embodiment, the bleaching treatment can be carried out with a second oxidizing agent.

[0079] The amount of hydrogen peroxide used in the decolorization treatment may be 0.01 wt % or more, 0.02 wt % or more, 0.03 wt % or more, 0.04 wt % or more, 0.05 wt % or more, 0.06 wt % or more, 0.1 wt % or more, 0.2 wt % or more, 0.3 wt % or more, 0.4 wt % or more, 0.5 wt % or more, 2.0 wt % or less, 1.7 wt % or less, 1.5 wt % or less, 1.3 wt % or less, 1.2 wt % or less, 1.1 wt % or less, 1 wt % or less, 0.9 wt % or less, 0.8 wt % or less, 0.7 wt % or less, or 0.6 wt % or less, relative to the total weight of the crude solution.

[0080] The bleaching treatment may be carried out under basic pH conditions. For example, the pH range for bleaching may be 7 or more, 7.5 or more, 8 or more, or 8.5 or more, or 13 or less, 12 or less, 11 or less, 10.5 or less, 10 or less, 9.5 or less, or 9 or less. Specifically, bleaching may be carried out at a pH of 7 to 13 or a pH of 8 to 13. More specifically, bleaching may be carried out at a pH of 8 to 11 or a pH of 8 to 10.

[0081] An alkaline component may be used to adjust the pH to a basic level. Examples of alkaline components used to adjust the pH in the decolorization treatment include, but are not limited to, sodium hydroxide, potassium hydroxide, lithium hydroxide, and sodium carbonate. The crude solution contains an appropriate amount of such alkaline component, allowing it to be adjusted to a desired basic pH.

[0082] The temperature in the bleaching treatment may be 40° C. or higher, 45° C. or higher, 50° C. or higher, 55° C. or higher, or 60° C. or higher, and 90° C. or lower, 80° C. or lower, 75° C. or lower, 70° C. or lower, or 65° C. or lower. Specifically, bleaching may be performed at a temperature of 40° C. to 90° C. or 50° C. to 70° C.

[0083] The time required for the bleaching treatment may be 10 minutes or more, 30 minutes or more, or 50 minutes or more, or may be 3 hours or less, 2 hours or less, or 1 hour 30 minutes or less, and specifically may be 30 minutes to 1 hour 30 minutes.

[0084] In another embodiment, the bleaching treatment may be performed by sequentially using a first oxidizing agent and a second oxidizing agent. Specifically, the bleaching treatment may include a first bleaching treatment using the first oxidizing agent and a second bleaching treatment using the second oxidizing agent.

[0085] The first decolorization treatment may be performed using a first oxidizing agent containing sodium chlorite (NaClO2). When decolorization is performed using sodium hypochlorite as an oxidizing agent, the color development is more improved and there is almost no decrease in molecular weight compared to other chlorine-based oxidizing agents (e.g., sodium hypochlorite). This is thought to be because cell-derived impurities (proteins, lipids, etc.) in the crude solution react with sodium hypochlorite and decompose, while PHA is less likely to decompose.

[0086] The amount of sodium chlorite used in the decolorization treatment may be 0.01 wt% or more, 0.02 wt% or more, 0.03 wt% or more, 0.04 wt% or more, 0.05 wt% or more, 0.06 wt% or more, 0.1 wt% or more, 0.2 wt% or more, 0.3 wt% or more, 0.4 wt% or more, 0.5 wt% or more, 1.3 wt% or less, 1.2 wt% or less, 1.1 wt% or less, 1 wt% or less, 0.9 wt% or less, 0.8 wt% or less, 0.7 wt% or less, or 0.6 wt% or less, based on the total weight of the crude solution. Specifically, in the first bleaching step, the sodium chlorite may be used in an amount of 0.01 to 1 wt% or 0.05 to 1 wt% based on the total weight of the crude solution. When the amount of sodium chlorite used is within the above-mentioned preferred range, a sufficient decolorization effect can be achieved while suppressing molecular weight reduction.

[0087] The first bleaching may be performed under acidic pH conditions. For example, the pH range during the first bleaching is 7 or less, 6.5 or less, 6 or less, 5.5 or less, 5 or less, 4.5 or less, or 4 or less, or may be 1 or more, 1.5 or more, 2 or more, 2.5 or more, 3 or more, or 3.5 or more. Specifically, the first bleaching may be performed at a pH of 1 to 7 or a pH of 2 to 7. More specifically, the first bleaching may be performed at a pH of 3 to 6 or a pH of 3 to 5.

[0088] An acid component may be used to adjust the pH to an acidic level. Acid components used to adjust the pH in the first bleaching step include, but are not limited to, phosphoric acid, sulfuric acid, hydrochloric acid, and nitric acid. This crude solution contains an appropriate amount of acid component, so it can be adjusted to a desired acidic pH.

[0089] The temperature during the first bleaching may be 40° C. or higher, 45° C. or higher, 50° C. or higher, 55° C. or higher, or 60° C. or higher, and 90° C. or lower, 80° C. or lower, 75° C. or lower, 70° C. or lower, or 65° C. or lower. Specifically, the first bleaching may be performed at a temperature of 40 to 90° C. or 50 to 70° C.

[0090] The time required for the first bleaching may be 10 minutes or more, 30 minutes or more, or 50 minutes or more, or may be 3 hours or less, 2 hours or less, or 1 hour 30 minutes or less, and specifically may be 30 minutes to 1 hour 30 minutes.

[0091] The second bleaching may be performed using a second oxidizing agent containing hydrogen peroxide (HO). The pH conditions, examples of the alkaline component to be added, the amount of oxidizing agent to be added, temperature, and time conditions for the second bleaching may be the same as those exemplified for the bleaching treatment using hydrogen peroxide.

[0092] In the second bleaching step, hydrogen peroxide is used as an oxidizing agent after sodium chlorite is used as an oxidizing agent in the first bleaching step. This significantly reduces the content of impurities (proteins and lipids) after the second bleaching step, and reduces the re-adsorption rate of impurities during solid (PHA) recovery. This allows for a reduction in the amount of enzyme used for protein degradation in the subsequent deproteinization step, thereby reducing production costs. Furthermore, the use of hydrogen peroxide in the second bleaching step in succession with sodium chlorite (first oxidizing agent) also reduces the amount of hydrogen peroxide used.

[0093] A deproteinization treatment may be performed after the decolorization treatment. The protein removal treatment may be performed using a protease. Examples of proteases include alcalase, pepsin, trypsin, papain, chymotrypsin, aminopeptidase, and carboxypeptidase. One or more of these may be used. Protein removal may be performed under basic pH conditions. For example, the pH range for deproteinization may be 7 or higher, 7.5 or higher, 8 or higher, or 8.5 or higher, or 12 or lower, 11 or lower, 10.5 or lower, 10 or lower, 9.5 or lower, or 9 or lower. The temperature for deproteinization may be 40°C or higher, 45°C or higher, 50°C or higher, 55°C or higher, or 60°C or higher, and 90°C or lower, 80°C or lower, 75°C or lower, 70°C or lower, or 65°C or lower.

[0094] Additionally, a supernatant liquid can be separated from the treatment solution during the purification process, or a supernatant liquid can be separated from the purified solution during the purification process and used to measure color value, which will be described in detail below in the section on monitoring color value.

[0095] Controlling refining conditions by monitoring color value The method of the present disclosure includes measuring and analyzing the color value of the treatment solution or its supernatant during the purification treatment, and controlling the conditions of the purification treatment.

[0096] For example, color value measurements are made using a * Including measurement of the a value of the above-mentioned treated solution or its supernatant, * Based on the change in value, the purification process conditions may be adjusted.

[0097] For example, a of the treated liquid or its supernatant * The value is the a of the crude solution or its supernatant before purification treatment. * This can be confirmed by comparing the value of the treated solution or its supernatant. * This may be confirmed by checking the change in value over time during the purification process.

[0098] Specifically, at the start of the purification process, the a of the treatment liquid or its supernatant * The change in the value is monitored, and the normal or abnormal state is distinguished based on the increase or decrease. If there is an abnormality, the amount of oxidizing agent added in the decolorization treatment can be increased. For this purpose, the treatment is performed by increasing the amount of oxidizing agent added to the crude solution or its supernatant. * The method further comprises measuring the a value of the treated solution or its supernatant. * of the above crude solution or its supernatant * Changes to values may be checked.

[0099] In another example, while carrying out the purification treatment, *The change in the value is continuously monitored, and the normal or abnormal state is judged based on the increase or decrease. If an abnormality occurs, the amount of oxidizing agent added in the decolorization treatment can be increased. For this purpose, after the start of the purification treatment, the a of the treatment solution or its supernatant is measured at regular time intervals, for example, every 10 minutes, every 20 minutes, or every 30 minutes. * Repeatedly measure these a * The values are compared to determine whether there is a decrease or increase.

[0100] According to another embodiment, the method of the present disclosure includes measuring the color values of the purified solution and its supernatant after the purification process, and predicting the color value of the final PHA based on the measured color values. If the predicted color value does not meet the target color value, further purification may be performed.

[0101] Specifically, a * The values are the b values of the purified solution and its supernatant after protein removal treatment. * The value of the final PHA resin was monitored. * If the value is judged to be inappropriate, additional bleaching treatment may be performed.

[0102] FIG. 2b shows a method for producing a PHA resin according to an embodiment, including a bleaching treatment (using only hydrogen peroxide).

[0103] FIG. 2b shows another embodiment of a method for producing a PHA resin, which includes a decolorization treatment (using sodium chlorite or the like).

[0104] Referring to Figures 2a and 2b, the purification process for producing a PHA resin may be divided into three cases: (A) when the purification process is abnormally performed, (B) when the purification process is performed normally but the color value of the final product is predicted to be unsuitable, and (C) when the purification process is performed normally but the color value of the final product is predicted to be suitable.

[0105] In the cases of (A) and (B), a PHA resin with low color development is obtained, so it is necessary to take appropriate measures by monitoring the color development value.

[0106] (A) When the refining process is abnormal When the initial crude PHA solution contains a large amount of impurities, the oxidizing agent added in the decolorization process reacts with the impurities dissolved in the crude solution first, without removing the impurities attached to the PHA particles, resulting in a shortage of oxidizing agent and preventing normal decolorization. Therefore, the change in color value (a of the treatment solution) in the initial stage of normal and abnormal progress of the decolorization process is * The change in

[0107] In one embodiment, referring to FIG. 2a, in the decolorization treatment using the second oxidizing agent (H2O2), * The value of a of the crude solution * If the value of the oxidizing agent increases, it can be considered abnormal. Therefore, the amount of oxidizing agent added may be increased. Specifically, if the following relationship (1A) is satisfied, the amount of oxidizing agent added in the decolorizing treatment may be increased. a0 < a30 (1A) In the relationship (1A), a0 is the a of the crude solution * a30 is the a value of the treated liquid after the addition of the second oxidizing agent * value.

[0108] After the addition of the second oxidant, * The value may be measured, for example, 1 minute, 5 minutes, 10 minutes, 20 minutes, 30 minutes, or 60 minutes after the addition of the second oxidizing agent, and more specifically, about 30 minutes after the addition of the second oxidizing agent.

[0109] According to another embodiment, referring to FIG. 2b, in the decolorization treatment using the first oxidizing agent (NaClO), * The value of a of the crude solution * If the oxidizing agent concentration is lower than the value, it may be considered abnormal. Therefore, the amount of oxidizing agent added may be increased. Specifically, when the following relationship (1B) is satisfied, the amount of at least one of the first oxidizing agent and the second oxidizing agent added in the decolorizing treatment may be increased, and more specifically, the amount of the second oxidizing agent added may be increased. a0'>a30' (1B) In the relationship (1B), a0' is the a of the supernatant of the crude solution. * a30' is the a value of the supernatant of the treated liquid after the addition of the first oxidizing agent. * value.

[0110] After the addition of the first oxidant, the supernatant of the treated solution * The value may be measured, for example, 1 minute, 5 minutes, 10 minutes, 20 minutes, 30 minutes, or 60 minutes after the addition of the first oxidizing agent, and more specifically, about 30 minutes after the addition of the first oxidizing agent.

[0111] As described above, in the decolorization treatment using sodium chlorite, the color value of only the supernatant of the treatment solution may be monitored, and the treatment solution may be centrifuged or otherwise separated into the supernatant.

[0112] In particular, in the decolorization treatment using hydrogen peroxide and the decolorization treatment using sodium chlorite, the a * The normal or abnormal state is determined based on the change in the value. Referring to FIG. 3a, the a * While an increase in the value may be judged as abnormal, referring to Figure 3b, the a of the supernatant 30 minutes after the addition of sodium chlorite * If the value is decreasing, it may be determined to be abnormal.

[0113] (B) When the color value of the final product is predicted to be non-conforming On the other hand, even if the purification treatment of polyhydroxyalkanoate resin is carried out normally, there are cases where the desired final properties (color value) cannot be obtained due to reasons such as the subsequent rapid decrease in the activity of the oxidizing agent.

[0114] In such cases, the color value of the purified liquid after purification treatment (for example, bleaching and deproteinization treatment) can be measured, the color value of the final PHA resin can be predicted, and appropriate measures can be taken in advance.

[0115] Therefore, the method of the present disclosure may include monitoring the color value of the purified liquid after the purification treatment and predicting the color value of the polyhydroxyalkanoate resin.

[0116] The purification process causes impurities adhering to the surface of the PHA particles to fall off and dissolve in the solvent.

[0117] Taking this into consideration, as shown in Figure 5, it is thought that the color of the PHA resin alone mixed into the purified liquid can be predicted by excluding the color of the supernatant liquid in which the impurities are dissolved from the color of the purified liquid (a mixture of PHA and impurities in a solvent).

[0118] Therefore, the measurement of the color value of the purified liquid is based on the a of the purified liquid and its supernatant in the CIE LAB color space. * and measuring the b value of the polyhydroxyalkanoate resin in the CIE LAB color space. * The values are a of the purified liquid and its supernatant * The prediction may be based on the value.

[0119] Specifically, the present inventors have investigated the a * value, a of the supernatant * value, and the final PHA resin b * The correlation can be derived by measuring the values with different numbers of treatments and performing statistical analysis based on these data. Examples of statistical analysis methods include, but are not limited to, regression analysis, specifically linear regression analysis or nonlinear regression analysis, and more specifically multiple regression analysis.

[0120] As an example, polyhydroxyalkanoate resin b * The value may be predicted from the following relationship (2A): b * =Y+(X1×a1)+(X2×a2)(2A) In the relationship (2A), a1 is the a of the purified liquid * a2 is the a value of the supernatant of the purified liquid * value.

[0121] In the relationship (2A), Y may be 10 or greater, 11 or greater, 12 or greater, 13 or greater, 14 or greater, 15 or greater, or 15.5 or greater, and may be 21 or less, 20 or less, 19 or less, 18 or less, 17 or less, 16.5 or less, or 16 or less. In the relationship (2A), X1 may be -2.5 or greater, -2.0 or greater, -1.5 or greater, -1 or greater, -0.5 or greater, 0 or greater, 0.3 or greater, 0.5 or greater, or may be 4.0 or less, 3.5 or less, 3 or less, 2.5 or less, 2 or less, 1.5 or less, 1 or less, or 0.7 or less. In the relationship (2A), X2 may be -3.5 or more, -3.0 or more, -2.5 or more, -2 or more, -1.5 or more, -1 or more, or -0.5 or more, or may be 3.0 or less, 2.5 or less, 2 or less, 1.5 or less, 1 or less, 0.5 or less, or 0 or less. Specific examples of the relationship (2A) include Y being 10 to 21 or 14.68 to 16.68, X1 being -2.5 to 4.0 or -0.39 to 1.61, and X2 being -3.5 to 3.0 or -1.35 to 0.65. A more specific example of the relationship (2A) is Y being approximately 15.68, X1 being approximately 0.61, and X2 being approximately -0.35.

[0122] Another example is polyhydroxyalkanoate resin b * The value may be predicted from the following relationship (2B): b * =Y'+(X1'×a1')+(X2'×a2')(2B) In the relationship (2B), a1' is the a of the purified liquid * a2' is the a value of the supernatant of the purified solution * value.

[0123] In the above relationship (2B), Y' may be 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 8.5 or more, or 9 or more, and may be 15 or less, 14 or less, 13 or less, 12 or less, 11 or less, 10 or less, or 9.5 or less. In the relationship (2B), X1' may be -7.0 or more, -6.5 or more, -6 or more, -5.5 or more, -5 or more, -4.5 or more, -1.0 or less, -1.5 or less, -2.0 or less, -2.5 or less, -3.0 or less, -3.5 or less, or -4.0 or less. In the relationship (2B), X2' may be -8 or more, -7 or more, -6 or more, -5.5 or more, -5 or more, -4.5 or more, or -4.3 or more, or may be -1 or less, -1.5 or less, -2 or less, -2.5 or less, -3 or less, -3.5 or less, or -4 or less. Specific examples of the relationship (2B) include Y' being 4 to 15 or 8.15 to 10.15, X1' being -7 to -1 or -5.15 to -3.15, and X2' being -8 to -1 or -5.04 to -3.04. More specific examples of the relationship (2B) include Y' being approximately 9.15, X1' being approximately -4.15, and X2' being approximately -4.04.

[0124] Referring to Figures 4a and 4b, the measurement of PHA resin * Value and prediction b * The values show a high correlation.

[0125] As mentioned above, the b * The value is predicted after the purification process, so the target b * If the range is not met, further purification treatment may be carried out before recovering the solid (PHA). * The value can be, for example, less than 15, and specifically can be 14 or less, 13 or less, 12 or less, 11 or less, or 10 or less.

[0126] Specifically, in the manufacturing method, the predicted b * Value is the target b *If the value exceeds this value, further purification treatment may be carried out, more specifically, further bleaching treatment may be carried out. Further bleaching may be carried out one or more times, and specific conditions for the bleaching treatment may be those exemplified above.

[0127] After purification, the solid is recovered, washed with water and dehydrated to obtain the final purified polyhydroxyalkanoate resin.

[0128] Polyhydroxyalkanoate resin The polyhydroxyalkanoate resins prepared by the methods of the present disclosure can be modified to improve color. For example, the polyhydroxyalkanoate resins can have a color of b on the CIE LAB color coordinate system. * The value may be 20 or less. Specifically, the b value of the polyhydroxyalkanoate resin in the CIE LAB color coordinate system * The value may be 14 or less, 13.5 or less, 13 or less, and 0 or more, 1 or more, 5 or more, 10 or more.

[0129] The polyhydroxyalkanoate resin may have a glass transition temperature (Tg) of, for example, -45°C to -10°C, -35°C to -10°C, -35°C to -15°C, -35°C to -20°C, or -30°C to -20°C.

[0130] The melting temperature (Tm) of the polyhydroxyalkanoate resin may not be measured, or may be, for example, 100 to 170°C, 100 to 160°C, 110 to 160°C, or 120 to 150°C.

[0131] The polyhydroxyalkanoate resin of the present disclosure may include amorphous polyhydroxyalkanoates, semi-crystalline polyhydroxyalkanoates, and mixtures thereof. For example, the crystallization temperature (Tc) of the polyhydroxyalkanoate resin may not be measured, or the crystallization temperature (Tc) may be measured as 60°C to 120°C, specifically 60°C to 110°C, 70°C to 120°C, or 75°C to 115°C.

[0132] The repeating units constituting the polyhydroxyalkanoate resin may include at least one selected from the group consisting of 2-hydroxybutyric acid (2-HB), 3-hydroxybutyric acid (3-HB), 3-hydroxypropionic acid (3-HP), 3-hydroxybutyric acid (3-HV), 3-hydroxyself-acid (3-HH), 3-hydroxyheptanoic acid (3-HHep), 3-hydroxyoctanoic acid (3-HO), 3-hydroxynonanoic acid (3-HN), 3-hydroxydecanoic acid (3-HD), 3-hydroxydodecanoic acid (3-HDd), 4-hydroxybutyric acid (4-HB), 4-hydroxybutyric acid (4-HV), 5-hydroxybutyric acid (5-HV), and 6-hydroxyself-acid (6-HH).

[0133] In one embodiment, the polyhydroxyalkanoate resin may contain 4-hydroxybutyric acid (4-HB) repeat units. Specifically, the polyhydroxyalkanoate resin may contain a copolymer containing 4-HB repeat units. For example, the content of 4-HB (4-hydroxybutyric acid) repeat units in the polyhydroxyalkanoate resin may be 0.1% by weight or more, 1% by weight or more, 5% by weight or more, 10% by weight or more, 20% by weight or more, 30% by weight or more, 40% by weight or more, 50% by weight or more, 60% by weight or more, 100% by weight or less, 99% by weight or less, 90% by weight or less, 80% by weight or less, 70% by weight or less, or 60% by weight or less, based on the total weight of the polyhydroxyalkanoate resin. Specifically, the polyhydroxyalkanoate resin may contain 25% by weight or more of 4-hydroxybutyric acid (4-HB) repeat units.

[0134] The weight average molecular weight (Mw) of the polyhydroxyalkanoate resin may be, for example, 50,000 or more, 100,000 or more, 200,000 or more, 300,000 or more, 400,000 or more, or 500,000 or more, or 1,200,000 or less, 900,000 or less, 800,000 or less, 700,000 or less, or 600,000 or less.

[0135] The polyhydroxyalkanoate resin may also have a purity of 95% or more, 97% or more, 98% or more, 98.5% or more, 98.55% or more, or 98.6% or more.

[0136] The present disclosure will be described in more detail below with reference to the drawings of the embodiments, however, these examples are merely illustrative and are not intended to limit the present disclosure.

[0137] Preparation Example 1: Preparation of PHA fermentation liquid A genetically modified E. coli strain was used to prepare the PHA fermentation broth. First, the PHA-producing bacteria were seed cultured, and after securing a certain amount, the main fermentation was carried out. For the fermentation of the PHA-producing strain, glucose or raw sugar was used as the carbon source, and various inorganic components were added as nutrients. Sodium hydroxide solution or ammonia gas was used to adjust the fermentation pH. The fermentation process using the PHA-producing bacteria was carried out at 30-40°C and pH 6-9.

[0138] Preparation Example 2: Preparation of crude PHA solution The PHA fermentation broth was subjected to solid-liquid separation using a mechanical separator to separate the biomass from medium impurities containing PHA. The separated biomass was adjusted to a total solids concentration of 10-15% by mass. A surfactant (sodium laureth sulfate, 30%, Miwon Co.) was added at 0.13% by mass relative to the total weight of the reaction solution. After thorough stirring, physical cell disruption was performed using a high-pressure homogenizer (Bertoli) (400-800 bar, 1 pass). The crude PHA solution thus obtained was subjected to a second solid-liquid separation to separate the PHA-containing solids and cell-derived impurities, yielding a crude PHA solution (a solution containing unpurified PHA).

[0139] Preparation Example 3A: Decolorization treatment using only hydrogen peroxide The crude PHA solution was added with 20% aqueous sodium hydroxide (NaOH) to adjust the pH to 9-9.5. A 30% aqueous solution of hydrogen peroxide (H2O2) was added in an amount of 0.44-0.77% by mass based on the total weight of the reaction solution. The decolorization reaction was carried out for 2 hours in a shaking incubator (IS-971R, JEIO TECH) at 60°C.

[0140] Preparation Example 3B: Bleaching treatment - performed using sodium chlorite and hydrogen peroxide in this order. (1) First bleaching treatment A 23% aqueous solution of sodium chlorite (NaClO2) adjusted to pH 6.0 using a 10% aqueous solution of phosphoric acid (H3PO4) was added at 0.22 to 0.55 mass% based on the total weight of the crude PHA solution. The final pH of the reaction solution was fixed at pH 4.0 using a 10% aqueous solution of phosphoric acid. The reaction was carried out in a shaking incubator (IS-971R, JEIO TECH) at 60°C for 1 hour.

[0141] (2) Second bleaching treatment A 20% aqueous solution of sodium hydroxide (NaOH) was added to the first decolorized slurry to adjust the pH to 9-9.5. A 30% aqueous solution of hydrogen peroxide was added in an amount of 0.22-0.55% by mass based on the total weight of the reaction solution. The decolorization reaction was carried out for 1 hour in a shaking incubator (IS-971R, JEIO TECH) at 60°C.

[0142] Preparation Example 4: Deproteinization treatment After the decolorization treatment, a 20% aqueous solution of sodium hydroxide was added to the reaction solution to adjust the pH to 9.5. TM ) was added in an amount of 0.011 to 0.044% by mass based on the total weight of the reaction solution. The protein removal reaction was carried out for 2 hours in a shaking incubator (IS-971R, JEIO TECH) at 60°C. After deproteinization, the recovered solid (PHA) was washed with water and dried to obtain the final purified polyhydroxyalkanoate resin.

[0143] Test Example 1: Derivation of factors reflecting the behavior of impurities during processing (multiple regression analysis) The purified solutions obtained by various purification treatments (bleaching and deproteinization) were evaluated for three color values (L * , a * , b * The b of the PHA resin finally obtained from the purified liquid was measured. *The values were measured using a spectrophotometer (CM-5, Konica Minolta). * The value increases as the amount of impurities increases, so b * The value reflects to some extent the content of impurities in the final PHA resin.

[0144] Which of the three color values of the purified liquid, either alone or in combination with two color values, had a significant correlation with the color value of the final product (i.e., there was an impurity removal effect). The three color values (L * , a * , b * The b of the PHA resin finally obtained from each treatment was measured. * The values were subjected to multiple linear regression analysis (n=67), and the results are shown in Table 1 below.

[0145] [Table 1]

[0146] As can be seen from the table above, when considering the p-value, which is an index for determining the reliability of correlation in multiple linear regression analysis, the color value of the refined liquid in the refinement process is a * The value of b of the final PHA resin * It was found that the most significant relationship was between the values.

[0147] Example 1A: Monitoring color value (using hydrogen peroxide alone) The color value was monitored during the purification process, including the decolorization treatment using hydrogen peroxide alone. Specifically, the changes in color value were measured during the preparation of a PHA fermentation liquid (Preparation Example 1), the preparation of a crude PHA solution (Preparation Example 2), and the decolorization treatment using hydrogen peroxide alone (Preparation Example 3A), and the pH of these treatment solutions was monitored. 12 ml of each treatment solution was taken and filled into a 20 mm quartz cell, and the transmittance of the sample was measured. * The color value was monitored by measuring the value.

[0148] First, the crude PHA solution obtained in Preparation Example 2 (the PHA solution obtained by disrupting and washing the PHA fermentation liquid, before adjusting the pH and decolorizing) * Thereafter, while the decolorization treatment of Preparation Example 3A and the deproteinization treatment of Preparation Example 4 were being carried out, the treatment solution was sampled at 30-minute intervals, and the a * The value was calculated.

[0149] a of the treatment solution measured 30 minutes after the start of decolorization treatment with hydrogen peroxide (addition of hydrogen peroxide) * The value of the crude PHA solution before decolorization is * If the value decreased, it was considered normal progression, and if it increased, it was considered abnormal progression.

[0150] The results are shown in Table 2 below and in Figure 3a.

[0151] [Table 2]

[0152] As can be seen from Table 2 and Figure 3a, a * The initial pH of the crude PHA solution was 0 to 7. If the decolorization process proceeded normally, the pH of the treated solution was * The value decreased by 40 to 80% compared to the initial value, whereas if the decolorization process proceeded abnormally, the a of the treatment solution after 30 minutes * The values increased by 2.0 to 4.5 times compared to the initial values.

[0153] Example 1B: Color Value Monitoring (Using Sodium Chlorite and Hydrogen Peroxide) The color value was monitored during purification treatments including decolorization treatments using sodium chlorite and hydrogen peroxide. Specifically, a PHA fermentation broth (Preparation Example 1), a crude PHA solution (Preparation Example 2), and decolorization treatments using sodium chlorite and hydrogen peroxide in succession (Preparation Example 3B) were prepared, and the treated solutions were centrifuged to obtain supernatants, and the color values of these supernatants were monitored.

[0154] To monitor the color value, 15 ml of each treatment solution was taken out and centrifuged at 3,800 rpm for 20 minutes in a centrifuge (Combi-514R, Hanil Co.), and 12 ml of the separated supernatant was poured into a 20 mm quartz cell. * The values were measured.

[0155] First, the supernatant of the crude PHA solution obtained in Preparation Example 2 (the PHA solution after recovering the PHA fermentation liquid by cell disruption and washing, but before pH adjustment and decolorization) was analyzed. * Thereafter, the first and second decolorization treatments of Preparation Example 3B and the deproteinization treatment of Preparation Example 4 were carried out, and the treated solution was sampled at 30-minute intervals. * The values were measured.

[0156] a of the supernatant of the treated solution measured 30 minutes after the start of the first decolorization treatment with sodium chlorite (addition of sodium chlorite) * The value of the supernatant of the crude PHA solution before decolorization is * If the value increased, it was considered to be a normal progression, and if it decreased, it was considered to be an abnormal progression.

[0157] The results are shown in Table 3 below and in Figure 3b.

[0158] [Table 3] As can be seen from Table 3 above and Figure 3b, a * The pH of the supernatant of the initial crude PHA solution was -2 to 0. During the normal course of decolorization, the pH of the supernatant of the treatment solution was * The values increased by 50-75% compared to the initial values after 30 minutes, whereas in abnormal progression, they decreased by 3.5 times compared to the initial values after 30 minutes.

[0159] Example 2A: PHA resin b * Value prediction (using hydrogen peroxide only) The color value (a * value) was measured, and the color value (b* Specifically, a purified liquid was obtained by preparing a PHA fermentation liquid (Preparation Example 1), preparing a crude PHA solution (Preparation Example 2), performing a decolorization treatment using hydrogen peroxide alone (Preparation Example 3A), and performing a deproteinization treatment (Preparation Example 4). The color value of the purified liquid was measured, and the final color value was predicted based on this. The color value of the PHA resin finally obtained by recovering the solids was measured and compared with the predicted value.

[0160] First, the purified solution after deproteinization was extracted, * The purified solution was centrifuged, the supernatant was taken, and the a * The solid matter was then recovered and the b value of the finally obtained polyhydroxyalkanoate resin was measured. * The color values were measured for 21 samples. The results are shown in the table below.

[0161] By performing multiple linear regression analysis using the measured color value data, the following relationship was derived. Final PHA resin b * =15.68+(0.61×a1)+(-0.35×a2) where a1 is the a of the refined liquid in the CIE LAB color space * a2 is the a value of the supernatant of the purified liquid * value.

[0162] Furthermore, the purified liquid and the supernatant * Substituting the values into the above equation, the final PHA resin is predicted b * The values were calculated and the results are shown in the table below.

[0163] [Table 4]

[0164] Based on the above results, measurement b * Value and prediction b * The correlation with the values is shown in Figure 4a, and the coefficient of determination (R 2 ) was confirmed to be high (0.8466).

[0165] Example 2B: PHA resin b * Value prediction (using sodium chlorite and hydrogen peroxide) The color value (a * value) was measured, and the color value (b * The color value of the purified liquid was measured, and the final color value was predicted based on the measured color value. The color value of the polyhydroxyalkanoate resin finally obtained by recovering the solid matter was measured and compared with the predicted value.

[0166] First, the purified solution after deproteinization was extracted, * The purified solution was centrifuged, the supernatant was taken, and the a * The b value of the polyhydroxyalkanoate resin finally obtained by recovering the solid matter was measured. * The color values were measured for nine samples. The results are shown in the table below.

[0167] By performing multiple linear regression analysis using the measured color value data, the following relationship was derived. b * Final PHA resin=9.15+(-4.15×a1')+(-4.04×a2') where a1' is the a of the refined liquid in the CIE LAB color space. * a2' is the value of the supernatant of the purified solution * value.

[0168] Furthermore, the purified liquid and its supernatant * Substituting the values into the above equation, the final PHA resin is predicted b * The values were calculated and the results are shown in the table below.

[0169] [Table 5]

[0170] Based on the above results, measurement b * Value and prediction b * The correlation with the values is shown in Figure 4b, and the coefficient of determination (R 2 ) was confirmed to be high (0.8257).

[0171] Example 3: Control of the refining process by monitoring color value In Example 2A, when the decolorization treatment became abnormal, the amount of hydrogen peroxide added was increased (1.5 times, 2.0 times) and the decolorization treatment was continued. After that, the deproteinization and solid content recovery were performed. * The values were measured.

[0172] In Example 2A, when the decolorization treatment was carried out excessively after the deproteinization treatment, the decolorization treatment was further carried out. * The values were measured.

[0173] In Example 2B, when the decolorization treatment was abnormally carried out, the amount of sodium chlorite added was increased (0.5%) and the decolorization treatment was carried out. After that, the deproteinization and solid content recovery were carried out. * The values were measured.

[0174] In Example 2B, when the decolorization treatment was abnormally carried out, the amount of hydrogen peroxide added was increased (1.5%). After that, the deproteinization and solid content recovery were carried out. * The values were measured.

[0175] Comparative Example The purification process was carried out in the same manner as in Example 3, except that the treatment conditions were not adjusted even when the decolorization process became abnormal. Then, based on the relationship derived in Example 2A or 2B, the predicted value b * The value was calculated.

[0176] b obtained in Comparative Example and Example 3 * The values are compared in Table 6 below.

[0177] [Table 6]

[0178] As can be seen from Table 6 above, if the decolorization treatment is abnormal, increasing the amount of oxidizing agent or performing additional decolorization can improve the b of the final PHA resin. * In particular, increasing the amount of oxidant was more effective than additional decolorization. * It was effective in reducing the value.

Claims

1. A method for controlling a purification process for producing a polyhydroxyalkanoate (PHA) resin, comprising measuring the color value of a treatment liquid or its supernatant during the purification process, or of a purified liquid and its supernatant after the purification process, and controlling the purification process based on the measured color value.

2. The measurement of the color value is a in the CIE LAB color space ＊ The measurement of the a value of the treated solution or its supernatant is included. ＊ The method of claim 1 , further comprising adjusting purification process conditions based on the change in the value.

3. a ＊ The change in value is the a of the treated solution or its supernatant. ＊ value and the a of the crude solution or its supernatant before the purification treatment ＊ or by comparing the a value of the treatment solution or its supernatant during the purification treatment. ＊ 3. The method for controlling a refining process according to claim 2, wherein the determination is made by a change in the value over time.

4. The measurement of the color value is a in the CIE LAB color space ＊ the b value of the polyhydroxyalkanoate resin in the CIE LAB color space; ＊ The values of the purified solution and its supernatant are ＊ 2. The method of claim 1, wherein the prediction is based on a value.

5. a purification unit that performs purification processing to produce a polyhydroxyalkanoate (PHA) resin; a monitoring unit for measuring the color value of the treatment solution or its supernatant during the purification treatment, or the color value of the purified solution and its supernatant after the purification treatment; a control unit that controls the refining process based on the measured color value; A control system for a refining process comprising:

6. A method for producing a polyhydroxyalkanoate resin from a crude solution containing polyhydroxyalkanoate (PHA) through a purification process, the method comprising at least one of the following steps: (a) measuring the color value of the treatment liquid or its supernatant during the purification process; and (b) measuring the color value of the purified liquid and its supernatant after the purification process.

7. The measurement of the color value in step (a) is carried out by measuring the color value of the processing solution or its supernatant in the CIE LAB color space. ＊ The measurement of the a value of the treated solution or its supernatant is included. ＊ The method for producing a polyhydroxyalkanoate resin according to claim 6, wherein the purification conditions are adjusted based on the change in the value.

8. a of the crude solution or its supernatant ＊ The method further comprises measuring the a value of the crude solution or its supernatant. ＊ a of the treated solution or its supernatant against the value ＊ The method for producing a polyhydroxyalkanoate resin according to claim 7, wherein a change in the value is confirmed.

9. The purification process includes a decolorization process, and the decolorization process is carried out sequentially using a first oxidizing agent, a second oxidizing agent, or both, and the first oxidizing agent is sodium hypochlorite (NaClO ２ ), and the second oxidant comprises hydrogen peroxide (H ２ O ２ 9. The method for producing the polyhydroxyalkanoate resin according to claim 8, comprising:

10. the decolorization treatment is carried out with the second oxidizing agent, 10. The method for producing a polyhydroxyalkanoate resin according to claim 9, wherein the amount of the oxidizing agent added in the decolorizing treatment is increased when the following relationship (1A) is satisfied: a0<a30 (1A) In the relationship (1A), a0 is the a of the crude solution ＊ a30 is the value of the a of the treatment liquid after the addition of the second oxidizing agent. ＊ value.

11. the decolorization treatment is carried out using the first oxidizing agent and the second oxidizing agent in sequence, 10. The method for producing a polyhydroxyalkanoate resin according to claim 9, wherein the amount of at least one of the first oxidizing agent and the second oxidizing agent added in the decolorizing treatment is increased when the following relationship (1B) is satisfied: a0'>a30' (1B) In the relationship (1B), a0' is the a of the supernatant of the crude solution ＊ a30' is the a value of the supernatant of the treated liquid after adding the first oxidizing agent. ＊ value.

12. The measurement of the color value in step (b) is carried out by measuring the color value of the purified liquid and its supernatant. ＊ and measuring the b value of the polyhydroxyalkanoate resin in the CIE LAB color space. ＊ The values of the purified solution and its supernatant were ＊ The method for producing the polyhydroxyalkanoate resin according to claim 6, wherein the prediction is based on the value.

13. b of the polyhydroxyalkanoate resin ＊ The method for producing a polyhydroxyalkanoate resin according to claim 12, wherein the value is predicted from the following relationship (2A): b ＊ =Y+(X1×a1)+(X2×a2)(2A) In the relationship (2A), a1 is the a of the purified liquid ＊ a2 is the a value of the supernatant of the purified solution ＊ values, Y is 10 to 21, X1 is −2.5 to 4.0, and X2 is −3.5 to 3.

0.

14. b of the polyhydroxyalkanoate resin ＊ The method for producing a polyhydroxyalkanoate resin according to claim 12, wherein the value is predicted from the following relationship (2B): b ＊ =Y’+(X1’×a1’)+(X2’×a2’)(2B) In the relationship (2B), a1' is the a of the purified liquid ＊ a2' is the value of the supernatant of the purified solution ＊ Y' is a value between 4 and 15, X1' is a value between -7 and -1, and X2' is a value between -8 and -1.

15. The predicted polyhydroxyalkanoate resin b ＊ The value is the target b ＊ The method for producing a polyhydroxyalkanoate resin according to claim 12, wherein further purification treatment is carried out when the value is greater than the above value.

16. The crude solution containing the polyhydroxyalkanoate is A treatment of obtaining biomass by solid-liquid separation of the fermentation liquid containing polyhydroxyalkanoate; A process of mixing the biomass with an additive containing a surfactant to obtain a suspension; and a process of pulverizing the biomass in the suspension to obtain a slurry. and subjecting the slurry to solid-liquid separation. A method for producing the polyhydroxyalkanoate resin according to claim 6.

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