Method for separating galactose from xylose mother liquor

Abstract

The invention relates to the technical field of galactose separation, in particular to a method for separating galactose from xylose mother liquor, which comprises the following steps: diluting the xylose mother liquor, and inoculating active dry yeast powder into the diluted xylose mother liquor for fermentation to obtain xylose fermentation liquor; filtering and concentrating the xylose fermentation liquor to obtain a raw material; and controlling the sample loading flow and the eluent flow in the two-dimensional liquid chromatography separation process of the raw materials, and separating the stock solution to obtain a galactose component solution. The invention aims to improve the purity of galactose in the separation process.

Description

Technical Field

[0001] The present application relates to the technical field of galactose separation, and in particular to a method for separating galactose from xylose mother liquor. Background Art

[0002] Xylose mother liquor is the waste sugar liquid left after xylose is produced by chemical methods using biomass resources such as corn cobs and sugarcane bagasse. It is usually a dark-colored viscous liquid with a certain fluidity. Xylose mother liquor mainly contains xylose, L-arabinose, glucose and galactose, and also contains impurities such as colloids, pigments and proteins. Among them, galactose is a hexose that is soluble in water and ethanol, slightly soluble in glycerol, and easy to crystallize. When crystallized from an aqueous solution, it contains one molecule of crystal water. The melting point is 118~120℃; when crystallized from an ethanol solution, it becomes an anhydrous substance with a melting point of 165~168℃. The appearance is white crystals with right-handed optical rotation. Chemical formula , relative molecular mass 180.6. Galactose contains calories and can be used as a nutritional sweetener, and its sweetness is about 0.6 times that of sucrose. In addition, it can also be used in organic synthesis and has important applications in the pharmaceutical industry.

[0003] Monosaccharides can be separated from xylose mother liquor by chemical methods, chromatographic separation methods, membrane separation methods, and microbial methods. The commonly used method for separating galactose in modern times is simulated moving bed chromatography in chromatographic separation methods. The existing two-dimensional liquid chromatography technology couples and integrates two sets of three-component liquid chromatography separation systems. After the xylose mother liquor is separated by a two-dimensional liquid chromatography system, a galactose component solution can be obtained. However, since the traditional method uses a fixed sample flow rate and eluent flow rate, which are set according to empirical values, it is impossible to achieve adsorption and desorption equilibrium during the separation process, and the purity of the final galactose is low. Summary of the invention

[0004] In order to solve the above technical problems, the present application provides a method for separating galactose from xylose mother liquor to solve the existing problems.

[0005] The present invention discloses a method for separating galactose from xylose mother liquor using the following technical scheme: One embodiment of the present application provides a method for separating galactose from xylose mother liquor, the method comprising the following steps: S1, diluting the xylose mother liquor, and inoculating active dry yeast powder into the diluted xylose mother liquor for fermentation to obtain a xylose fermentation liquid; S2, filtering and concentrating the xylose fermentation broth to obtain a raw material; S3, controlling the sample flow rate and the eluent flow rate during the two-dimensional liquid chromatography separation of the raw material, the control process includes: S301: In the two-dimensional liquid chromatography system, a plurality of sampling points are sequentially set from the feed port end to the discharge port end, and the optical rotation of each sampling point at the current moment and all sampling moments before the current moment and a preset time length is obtained, and the bubble influence factor of each sampling point at the current moment is determined by analyzing the discrete degree of the optical rotation of each sampling point at the current moment and all sampling moments before the current moment, and the difference in the optical rotation of each sampling point between the current moment and the previous sampling moment, so as to obtain the corrected optical rotation of each sampling point at the current moment; S302: fitting the corrected optical rotations of all sampling points at the current moment to obtain a fitting curve, determining the peak width at the current moment according to the changing trend of the fitting curve between adjacent sampling points on both sides of the maximum value on the fitting curve, and determining the optical rotation change factor at the current moment in combination with the distribution of the changing trend of the fitting curve between all adjacent sampling points on the fitting curve and the extreme distribution of the fitting values ​​on the fitting curve, and controlling the sample flow rate and the eluent flow rate in the separation process at the current moment; S4, separating the stock solution to obtain a galactose component solution.

[0006] Preferably, the components of the xylose mother liquor include, by mass fraction: xylose content of 40% to 52%, arabinose content of 25% to 32%, glucose content of 10% to 18%, galactose content of 10% to 16%, and other impurities content of 3% to 7%.

[0007] Preferably, the method of diluting the xylose mother liquor and inoculating the active dry yeast powder into the diluted xylose mother liquor for fermentation to obtain the xylose fermentation liquid is as follows: diluting the xylose mother liquor with deionized water to a refractive concentration of 15% to 30%, inoculating the active dry yeast powder into the diluted xylose mother liquor at a ratio of 0.1% to 0.4% (m / V), blowing air to oxygenate the diluted and inoculated xylose mother liquor and controlling the temperature at 25 to 35° C., and fermenting for 20 to 30 hours to obtain the xylose fermentation liquid.

[0008] Preferably, the process of filtering and concentrating the xylose fermentation broth to obtain the raw material is: filtering the color substances and inorganic ions in the xylose fermentation broth to obtain sugar solution, controlling the temperature of the sugar solution at 60-70°C, and evaporating and concentrating the sugar solution to a refractive index of 45%-65% to obtain the raw material.

[0009] Preferably, the two-dimensional liquid chromatography separation of the raw materials includes: the stationary phase of the first-dimensional liquid chromatography system is one of calcium, sodium, potassium, hydrogen or hydroxyl-type styrene skeleton resin, comprising 7 to 9 chromatographic columns, each chromatographic column has a column height of 1m to 3m, a column diameter of 1m to 3m, and an operating temperature of 50 to 80°C; the stationary phase of the second-dimensional liquid chromatography system is one of calcium, sodium, potassium, hydrogen or hydroxyl-type styrene skeleton resin, comprising 7 to 9 chromatographic columns, each chromatographic column has a column height of 1m to 3m, a column diameter of 1m to 3m, and an operating temperature of 50 to 80°C.

[0010] Preferably, the expression of the bubble influence factor of each sampling point at the current moment is: ; In the formula, Represents the bubble influence factor of the j-th sampling point at the current moment; Indicates the standard deviation of the optical rotation of the jth sampling point at the current moment and all previous sampling moments; Represents the difference in optical rotation of the jth sampling point between the current moment and its previous sampling moment; Represents a preset value; norm[ ] represents a normalization function; exp( ) represents an exponential function with a natural constant as the base.

[0011] Preferably, the method for obtaining the corrected optical rotation of each sampling point at the current moment is: If the bubble influence factor of the j-th sampling point at the current moment is greater than the preset threshold, the optical rotation of the j-th sampling point at the current moment is eliminated, and the missing data at the j-th sampling point at the current moment is supplemented by the interpolation method, and the supplemented data is used as the corrected optical rotation of the j-th sampling point at the current moment; otherwise, the optical rotation of the j-th sampling point at the current moment is recorded as the corrected optical rotation of the j-th sampling point at the current moment.

[0012] Preferably, the method for determining the peak width at the current moment is: Calculate the slope of the fitting curve between each sampling point on the fitting curve at the current moment and its previous sampling point as the slope value of each sampling point at the current moment; Taking the maximum value on the fitting curve at the current moment as the center, the total number of sampling points whose slope values ​​are continuously positive before the maximum value and the total number of sampling points whose slope values ​​are continuously negative after the maximum value are counted respectively. The sum of the total number of sampling points whose slope values ​​are continuously positive and the total number of sampling points whose slope values ​​are continuously negative is recorded as the peak width at the current moment.

[0013] Preferably, the expression of the optical rotation change factor at the current moment is: ; In the formula, Indicates the optical rotation change factor at the current moment; Represents the mean of the slope values ​​of all sampling points at the current moment; Indicates the peak width at the current moment; represents the maximum value on the fitting curve at the current moment; norm() represents the normalization function.

[0014] Preferably, the control of the sample loading flow rate and the eluent flow rate in the separation process at the current moment includes: The optical rotation change factor at the current moment is used as the objective function of the optimization algorithm, and the constraint conditions are set as follows: the sample flow rate of the first-dimensional liquid chromatography system is within a preset first range, the eluent flow rate is within a preset second range, and the sample flow rate of the second-dimensional liquid chromatography system is within the preset first range, and the eluent flow rate is within the preset second range; The optimization algorithm is iterated, and the sample flow rate and eluent flow rate of the first and second dimensional liquid chromatography systems corresponding to the maximum value of the objective function are taken as the optimal sample flow rate and optimal eluent flow rate of the first and second dimensional liquid chromatography systems in the separation process at the current moment.

[0015] This application has at least the following beneficial effects: The present application constructs a bubble influence factor for each sampling point by analyzing the discrete degree of the optical rotation of each sampling point at the current moment and all previous sampling moments, as well as the difference in the optical rotation of each sampling point between the current moment and the previous sampling moment, and corrects the optical rotation according to the bubble influence factor, thereby eliminating the influence of bubbles in the optical rotation acquisition process, improving the accuracy of the optical rotation data, and thus improving the control accuracy of the sample flow rate and the eluent flow rate; further, the corrected optical rotation of all sampling points at the current moment is fitted to obtain a fitting curve, and according to the changing trend of the fitting curve between adjacent sampling points on both sides of the maximum value on the fitting curve, combined with the distribution of the changing trend of the fitting curve between all adjacent sampling points on the fitting curve, and the extreme distribution of the fitting values ​​on the fitting curve, an optical rotation change factor is constructed, which reflects the change in the concentration of galactose during the separation process, thereby determining whether the sample flow rate and the eluent flow rate are appropriate under the current separation conditions, achieving optimized separation of galactose, and improving the purity of galactose during the separation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0017] Figure 1A flow chart of the steps of a method for separating galactose from xylose mother liquor provided in one embodiment of the present application; Figure 2 A curve diagram of optical rotation change after flow control provided in one embodiment of the present application. DETAILED DESCRIPTION

[0018] In order to further explain the technical means and effects adopted by the present application to achieve the predetermined invention purpose, the following is a detailed description of the method for separating galactose from a xylose mother liquor proposed in the present application, its specific implementation, structure, characteristics and effects, in conjunction with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" does not necessarily refer to the same embodiment. In addition, the specific features, structures or characteristics of one or more embodiments may be combined in any suitable form.

[0019] Unless otherwise defined, terms such as "comprises", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that a circuit structure, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such articles or devices. In the absence of further restrictions, an element defined by the statement "comprising a ..." does not exclude the presence of other identical elements in the article or device comprising the element. In addition, the term "and\or" used herein includes any and all combinations of one or more related listed items. All technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present application belongs.

[0020] The specific scheme of the method for separating galactose from xylose mother liquor provided by the present application is described in detail below with reference to the accompanying drawings.

[0021] Example 1 Example 1 provides a method for separating galactose from xylose mother liquor. For details, please refer to Figure 1 , the method comprises the following steps: S1, diluting the xylose mother liquor, and inoculating active dry yeast powder into the diluted xylose mother liquor for fermentation to obtain xylose fermentation liquid.

[0022] Depending on the production raw materials and production processes, the component contents of the xylose solution are slightly different. In this embodiment, a xylose mother liquor containing 40% xylose, 25% arabinose, 10% glucose, 10% galactose and 3% other impurities is used as the xylose mother liquor to be separated, and the xylose mother liquor is diluted with deionized water until the refractive index of the solution is 15%, thereby obtaining the diluted xylose mother liquor.

[0023] Furthermore, in this embodiment, active dry yeast powder was inoculated into the diluted xylose mother liquor at a ratio of 0.1% (m / V), aerated and oxygenated, and the temperature was controlled at 25° C. for 20 hours to obtain xylose fermentation liquid.

[0024] S2, filtering and concentrating the xylose fermentation broth to obtain raw materials.

[0025] In the xylose fermentation liquid obtained after dilution and fermentation of the xylose mother liquor, most of the glucose and miscellaneous sugars have been removed, and the colloids, proteins and solids are then removed by filtration. Finally, activated carbon combined with anion and cation exchange resins are used to remove color substances and inorganic ions in the xylose fermentation liquid to obtain a sugar liquid with a transmittance higher than a preset percentage.

[0026] It should be noted that the value of the preset percentage is artificially set. In this embodiment, the value of the preset percentage is 80%. The implementer can also set it by himself according to the specific situation. This embodiment does not impose any special restrictions.

[0027] Furthermore, in this embodiment, the sugar solution temperature is controlled at 60° C. and evaporated and concentrated to 45% to obtain a raw material.

[0028] S3, controlling the sample loading flow rate and the eluent flow rate during the two-dimensional liquid chromatography separation process of the raw material.

[0029] Preferably, in this embodiment, the stationary phase of the first-dimensional liquid chromatography system is potassium-type styrene resin, and the stationary phase of the second-dimensional liquid chromatography system is hydroxyl-type styrene resin. The first-dimensional liquid chromatography system comprises 7 chromatographic columns connected end to end in series, with a column height of 1m and a column diameter of 1m, and the second-dimensional liquid chromatography system comprises 8 chromatographic columns connected end to end in series, with a column height of 1.5m and a column diameter of 1.5m.

[0030] It should be noted that the two-dimensional liquid chromatography system is a well-known technology, and its specific principle will not be described in detail.

[0031] S301: In the two-dimensional liquid chromatography system, multiple sampling points are sequentially set from the feed port to the discharge port, and the optical rotation of each sampling point at the current moment and all the sampling moments before it within a preset time period is obtained. By analyzing the discrete degree of the optical rotation of each sampling point at the current moment and all the sampling moments before it, and the difference in the optical rotation of each sampling point between the current moment and the previous sampling moment, the bubble influence factor of each sampling point at the current moment is determined to obtain the corrected optical rotation of each sampling point at the current moment.

[0032] A plurality of sampling points are set in the first-dimensional and second-dimensional liquid chromatography systems. The positions of the sampling points are set at the feed port, the discharge port and the connection position of the adjacent chromatographic columns. The sampling points are arranged in ascending order according to the positions from the feed port to the discharge port in the two-dimensional liquid chromatography system.

[0033] Furthermore, a high-quality sampling valve is installed at each sampling point to ensure its sealing to prevent leakage and cross contamination of the original solution. The collected samples are transported to the online polarimeter for detection through a chemically corrosion-resistant sampling tube connected to the sampling valve.

[0034] It should be noted that the sampling pump selected in this embodiment is a peristaltic pump. The flow rate of the sampling pump is set to 1 mL per sampling, and the sampling time interval is set to 2 minutes. The settings of the sampling flow rate and time interval are both manually set, and the implementer can also set them according to the specific situation. This embodiment does not impose any special restrictions.

[0035] Furthermore, during the separation process, the sampling pump automatically extracts samples from each sampling point at a preset time interval. The extracted samples first pass through an online filtration device to filter out solid impurities and prevent them from entering the polarimeter measurement cell, and the optical rotation of the pre-treated samples is measured. Optical rotation is a physical quantity that measures the ability of a substance to rotate plane polarized light. The sodium light D line emitted by the polarimeter light source becomes plane polarized light after passing through a polarizer. Since the galactose in the sample has optical rotation, the vibration plane of the polarized light rotates. The rotation angle is the optical rotation. Different sugar molecules have different optical rotation abilities due to differences in chiral centers, hydroxyl positions, and spatial conformations. Therefore, the concentration changes can be reflected by the changes in optical rotation at different sampling points, and the flow rate can be adjusted accordingly.

[0036] In the chromatographic column, the stationary phase interacts with the mobile phase to separate the components in the mixture. When the sample passes through the chromatographic column with the mobile phase, adsorption occurs between the molecules of different components and the stationary phase. Furthermore, as the mobile phase continues to flow, the adsorbed components gradually detach from the stationary phase. The speed and degree of desorption are affected by many factors, such as temperature, pressure, flow rate of the mobile phase, and the interaction between the components and the stationary phase. By adjusting these factors, the desorption process can be controlled.

[0037] In this embodiment, two-dimensional liquid chromatography is used to separate the stock solution, wherein the stock solution is the above-mentioned pre-treated xylose mother liquor. In the two-dimensional liquid chromatography system, the various sugar components in the xylose mother liquor produce different degrees of adsorption with the stationary phase due to differences in molecular structure, thereby achieving the separation of galactose. By controlling the appropriate sample flow rate and eluent flow rate, the adsorption and desorption processes in the chromatographic column can be balanced, thereby obtaining a high-purity galactose product.

[0038] The loading flow rate refers to the volume of xylose mother liquor injected into the chromatographic column per unit time. When the loading flow rate is too large, the residence time of galactose in the column is greatly shortened, and effective adsorption and desorption cycles cannot be achieved, resulting in reduced galactose purity in the effluent; when the loading flow rate is too small, the adsorption time of sugars in the column is prolonged, but it is easy to cause system efficiency bottlenecks and diffusion interference. Moreover, long-term residence will increase the risk of secondary adsorption of impurities and galactose, reducing the purity of the final galactose produced.

[0039] The eluent flow rate refers to the volume of eluent flowing through the chromatographic column per unit time. When the eluent flow rate is too high, the sugar molecules will be rapidly desorbed from the stationary phase, but too fast a flow rate will cause different sugars to be eluted in large quantities at the same time, resulting in incomplete separation and a decrease in product purity. When the eluent flow rate is insufficient, it is difficult to effectively promote the desorption of galactose molecules from the stationary phase, which affects the purity of galactose and prolongs the overall separation cycle, increasing production costs and equipment losses, and reducing the process economic benefits and product quality stability.

[0040] Therefore, precise control of sample flow rate and eluent flow rate during the separation process is crucial to the purity of galactose separation.

[0041] According to the above analysis, the sample flow rate and eluent flow rate can be controlled by adjusting the optical rotation. When the sampling pump collects samples from the sampling point, bubbles may appear in the pipeline, and the bubbles will affect the measurement accuracy of the optical rotation, thereby reducing the accuracy of the sample flow rate and eluent flow rate control. In the optical rotation measurement optical path, bubbles are equivalent to the inhomogeneous area of ​​the optical medium. When the light passes through the sugar solution sample containing bubbles, the refractive index difference between the bubbles and the solution is large, causing the light to refract, scatter and reflect. Therefore, bubbles will deflect the light and superimpose it on the optical rotation signal, causing the fluctuation and deviation of the measured value to increase, affecting the accuracy of the quantitative analysis of galactose concentration, and increasing the risk of misjudgment in the separation process based on optical rotation.

[0042] Therefore, by analyzing the change of optical rotation and eliminating the interference of bubbles, the accuracy of optical rotation data can be improved, thereby improving the accuracy of sample flow rate and eluent flow rate control. Specifically: The bursting of bubbles will cause local pressure pulses, which will impact the flow dynamics of the liquid in the pipeline and the measurement environment of the polarimeter. The propagation of pressure waves changes the optical uniformity and distribution state of the sample in the optical path, and the optical rotation signal changes suddenly in a short period of time, forming a spike pulse noise in the acquisition curve. This noise interferes with data trend analysis and threshold judgment, such as the slope misjudgment deviation at the key node of galactose concentration change slope calculation. Therefore, by analyzing the discrete degree of the optical rotation of each sampling point at the current moment and all previous sampling moments, as well as the difference in the optical rotation of each sampling point between the current moment and the previous sampling moment, the bubble influence factor of each sampling point at the current moment is determined to obtain the corrected optical rotation of each sampling point at the current moment, specifically: The bubble influence factor of the jth sampling point at the current moment The expression is: ; In the formula, Indicates the standard deviation of the optical rotation of the jth sampling point at the current moment and all previous sampling moments; Represents the difference in optical rotation of the jth sampling point between the current moment and its previous sampling moment; Represents a preset value; norm[ ] represents a normalization function; exp( ) represents an exponential function with a natural constant as the base.

[0043] It should be noted that the preset value A represents an adjustment parameter, which is used to amplify the difference in optical rotation between adjacent measurement points. If the value of A is too large, it may lead to excessive sensitivity to changes in optical rotation. Even small normal fluctuations may be mistaken for the influence of bubbles, thereby causing false alarms. If the value of the preset value A is too small, the change in optical rotation caused by bubbles may be suppressed, so that the calculated bubble influence factor cannot accurately reflect the actual influence of bubbles, and the optical rotation anomaly cannot be effectively detected in the presence of bubbles. Therefore, the preset value A in this embodiment is 10, and the implementer may also reasonably set it based on the specific situation. This embodiment does not impose any special restrictions.

[0044] According to the bubble influence factor of each sampling point at the current moment, it can be understood that, under normal circumstances, the difference in optical rotation at different moments of the same sampling point is small, and if bubbles appear during measurement, the optical rotation data may fluctuate, resulting in an increase in the standard deviation; and the greater the difference in optical rotation between adjacent moments of the same sampling point caused by the spike pulse noise caused by the appearance of bubbles, the greater the bubble influence factor, indicating that the optical rotation obtained at the corresponding sampling point at the current moment is more likely to be affected by bubbles, and the data point is less reliable and needs to be processed more; on the contrary, the smaller the standard deviation and the smaller the difference, the higher the stability of the data point at the current sampling moment, and the less likely it is to be affected by bubbles, that is, the smaller the bubble influence factor.

[0045] Furthermore, according to the bubble influence factor, the optical rotation of each sampling point at the current moment is corrected, specifically: If the bubble influence factor of the j-th sampling point at the current moment is greater than the preset threshold, the optical rotation of the j-th sampling point at the current moment is eliminated, and the missing data at the j-th sampling point at the current moment is supplemented by the interpolation method, and the supplemented data is used as the corrected optical rotation of the j-th sampling point at the current moment; conversely, if the bubble influence factor of the j-th sampling point at the current moment is less than or equal to the preset threshold, the optical rotation of the j-th sampling point at the current moment is recorded as the corrected optical rotation of the j-th sampling point at the current moment.

[0046] It should be noted that the value of the preset threshold is artificially set. In this embodiment, the value of the preset threshold is 0.8. The implementer can also set it by himself according to the specific situation. This embodiment does not impose any special restrictions.

[0047] There are many commonly used interpolation methods. Spline interpolation is used in this embodiment. The implementer can also use other interpolation methods such as Lagrange interpolation according to the specific situation. This embodiment does not impose any special restrictions on the selection of interpolation method. Spline interpolation is a well-known technology and its specific principle will not be repeated.

[0048] S302: Fit the corrected optical rotation of all sampling points at the current moment to obtain a fitting curve, determine the peak width at the current moment according to the changing trend of the fitting curve between adjacent sampling points on both sides of the maximum value on the fitting curve, and determine the optical rotation change factor at the current moment in combination with the distribution of the changing trend of the fitting curve between all adjacent sampling points on the fitting curve and the extreme distribution of the fitting values ​​on the fitting curve, and control the sample flow rate and eluent flow rate in the separation process at the current moment.

[0049] The change in optical rotation can reflect the change in galactose concentration during the separation process. The optical rotation of galactose is proportional to its concentration, that is, the greater the concentration of galactose during the separation process, the greater the optical rotation. Therefore, by analyzing the change in the corrected optical rotation of different sampling points at the current moment, the optical rotation change factor at the current moment is determined, specifically: Fit the corrected optical rotation of all sampling points at the current moment to obtain a fitting curve; It should be noted that there are many commonly used curve fitting methods. In this embodiment, the least squares method is used to fit the corrected optical rotation. The implementer may also use other fitting methods such as polynomial function fitting. This embodiment does not impose any special restrictions on the selection of the fitting method.

[0050] Among them, the least square method is a well-known technology, and its specific principle will not be repeated here.

[0051] Further, the slope of the fitting curve between each sampling point on the fitting curve at the current moment and its previous sampling point is calculated as the slope value of each sampling point at the current moment; Taking the maximum value on the fitting curve at the current moment as the center, the total number of sampling points whose slope values ​​are continuously positive before the maximum value and the total number of sampling points whose slope values ​​are continuously negative after the maximum value are counted respectively. The sum of the total number of sampling points whose slope values ​​are continuously positive and the total number of sampling points whose slope values ​​are continuously negative is recorded as the peak width at the current moment.

[0052] The optical rotation change factor at the current moment The expression is: ; In the formula, Represents the mean of the slope values ​​of all sampling points at the current moment; Indicates the peak width at the current moment; represents the maximum value on the fitting curve at the current moment; norm() represents the normalization function.

[0053] It should be understood that the slope of the optical rotation reflects the rate of change of galactose concentration, and the slope can provide important information for adsorption and desorption during the separation process. If the mean of the slope value is positive and large, it means that the galactose concentration is increasing rapidly, which may be due to the fact that galactose is being desorbed from the stationary phase and the desorption rate is fast; It represents the peak width at the current moment. The larger the ratio of the peak width to the maximum value on the fitting curve, the greater the change in galactose concentration, which may mean that more galactose participates in the adsorption and desorption process during the separation process, or the elution process is more intense; therefore, the larger the mean value of the slope value, the larger the ratio of the peak width to the maximum value on the fitting curve, and the larger the rotational photometric change factor, indicating that the current separation conditions are more suitable, that is, the sample flow rate and the eluent flow rate are more appropriate.

[0054] On the contrary, if the mean of the slope value is negative and the absolute value is large, it may mean that galactose is being adsorbed and the concentration is decreasing; the smaller the ratio of the peak width to the maximum value on the fitting curve, the less optimized the separation conditions are, resulting in insufficient adsorption or desorption of galactose, or the lower the galactose content. The smaller the final optical rotation change factor, the smaller the galactose concentration changes during the separation process, and the sample flow rate and eluent flow rate need to be adjusted to quickly increase the concentration.

[0055] Further, the optical rotation change factor at the current moment is used as the objective function of the optimization algorithm, and the constraint conditions are set as follows: the sample flow rate of the first-dimensional liquid chromatography system is within the preset first range, the eluent flow rate is within the preset second range, and the sample flow rate of the second-dimensional liquid chromatography system is within the preset first range, and the eluent flow rate is within the preset second range, wherein the initial sample flow rate and eluent flow rate of the first and second-dimensional liquid chromatography systems are both preset values; The optimization algorithm is iterated, and the sample flow rate and eluent flow rate of the first and second dimensional liquid chromatography systems corresponding to the maximum value of the objective function are taken as the optimal sample flow rate and optimal eluent flow rate of the first and second dimensional liquid chromatography systems in the separation process at the current moment.

[0056] It should be noted that the optimization algorithm used in this embodiment is a gradient descent algorithm, and the preset first range is set to 0.5BV / h~4BV / h, the preset second range is set to 0.5BV / h~5BV / h, and the preset value is 2BV / h, that is, the initial first and second dimensional liquid chromatography systems The sample flow rate and eluent flow rate are both 2BV / h, among which the gradient descent method is a well-known technology and its specific principles are not repeated here.

[0057] S4, separating the stock solution to obtain a galactose component solution.

[0058] Finally, the stock solution is separated according to the real-time regulated sample flow rate and eluent flow rate to obtain a galactose component solution. The separation process is a well-known technique, and the specific separation steps are not described in detail.

[0059] Example 2 Example 2 provides a method for separating galactose from xylose mother liquor. For details, please refer to Figure 1 , the method comprises the following steps: S1, diluting the xylose mother liquor, and inoculating active dry yeast powder into the diluted xylose mother liquor for fermentation to obtain xylose fermentation liquid.

[0060] Depending on the production raw materials and production processes, the component contents of the xylose solution are slightly different. In this embodiment, a xylose mother liquor containing 42% xylose, 26% arabinose, 11% glucose, 11% galactose and 4% other impurities is used as the xylose mother liquor to be separated, and the xylose mother liquor is diluted with deionized water until the refractive index of the solution is 22%, thereby obtaining the diluted xylose mother liquor.

[0061] Furthermore, in this embodiment, active dry yeast powder was inoculated into the diluted xylose mother liquor at a ratio of 0.2% (m / V), aerated and oxygenated, and the temperature was controlled at 30° C. for 25 hours to obtain xylose fermentation liquid.

[0062] S2, filtering and concentrating the xylose fermentation liquid, controlling the temperature of the sugar liquid at 65°C, and evaporating and concentrating it to 53% to obtain a raw material, wherein the operation of filtering the xylose fermentation liquid is the same as that in Example 1.

[0063] S3, controlling the sample loading flow rate and the eluent flow rate during the two-dimensional liquid chromatography separation process of the raw material.

[0064] Preferably, in this embodiment, the stationary phase of the first-dimensional liquid chromatography system is calcium-type styrene resin, and the stationary phase of the second-dimensional liquid chromatography system is sodium-type styrene resin. The first-dimensional liquid chromatography system comprises 8 chromatographic columns connected end to end, with a column height of 2m and a column diameter of 2m, and the second-dimensional liquid chromatography system comprises 8 chromatographic columns connected end to end, with a column height of 2.5m and a column diameter of 2.5m. The steps of controlling the sample flow rate and the eluent flow rate during the two-dimensional liquid chromatography separation of the raw material are the same as in Example 1.

[0065] S4, the process of separating the stock solution to obtain the galactose component solution is the same as in Example 1.

[0066] Example 3 Example 3 provides a method for separating galactose from xylose mother liquor. For details, please refer to Figure 1 , the method comprises the following steps: S1, diluting the xylose mother liquor, and inoculating active dry yeast powder into the diluted xylose mother liquor for fermentation to obtain xylose fermentation liquid.

[0067] Depending on the production raw materials and production processes, the component contents of the xylose solution are slightly different. In this embodiment, a xylose mother liquor containing 43% xylose, 27% arabinose, 12% glucose, 13% galactose and 5% other impurities is used as the xylose mother liquor to be separated, and the xylose mother liquor is diluted with deionized water until the refractive index of the solution is 30%, thereby obtaining the diluted xylose mother liquor.

[0068] Furthermore, in this example, active dry yeast powder was inoculated into the diluted xylose mother liquor at a ratio of 0.4% (m / V), aerated and oxygenated, and the temperature was controlled at 35° C. for 30 hours to obtain xylose fermentation liquor.

[0069] S2, filtering and concentrating the xylose fermentation liquid, controlling the temperature of the sugar liquid at 70°C, and evaporating and concentrating it to 65% to obtain a raw material, wherein the operation of filtering the xylose fermentation liquid is the same as that in Example 1.

[0070] S3, controlling the sample loading flow rate and the eluent flow rate during the two-dimensional liquid chromatography separation process of the raw material.

[0071] Preferably, in this embodiment, the stationary phase of the first-dimensional liquid chromatography system is calcium-type styrene resin, and the stationary phase of the second-dimensional liquid chromatography system is sodium-type styrene resin. The first-dimensional liquid chromatography system comprises 9 chromatographic columns connected end to end, with a column height of 2.5m and a column diameter of 2.5m, and the second-dimensional liquid chromatography system comprises 9 chromatographic columns connected end to end, with a column height of 3m and a column diameter of 3m. The steps of controlling the sample flow rate and the eluent flow rate during the two-dimensional liquid chromatography separation of the raw material are the same as in Example 1.

[0072] S4, the process of separating the stock solution to obtain the galactose component solution is the same as in Example 1.

[0073] Comparison of Examples In order to verify the validity of the parameters of this application, this application sets up a number of comparative examples, specifically: Comparative Example 1: The sample flow rate of the first and second dimension liquid chromatography systems was set to 2.2 BV / h, the eluent flow rate was set to 2.0 BV / h, and the flow rate was not adjusted during the separation process. Except for the explanation, the process flow and parameters of Comparative Example 1 were consistent with those of Example 1.

[0074] Comparative Example 2: The sample flow rate of the first-dimensional liquid chromatography system is set to 1.2 BV / h, the eluent flow rate is set to 2.0 BV / h, the sample flow rate of the second-dimensional liquid chromatography system is set to 1.4 BV / h, the eluent flow rate is set to 2.2 BV / h, and the flow rate is not adjusted during the separation process. Except for the instructions, the process flow and parameters of Comparative Example 2 are consistent with those of Example 2.

[0075] Comparative Example 3: The sample flow rate of the first-dimensional liquid chromatography system is set to 2.0 BV / h, the eluent flow rate is set to 1.8 BV / h, the sample flow rate of the second-dimensional liquid chromatography system is set to 2.4 BV / h, the eluent flow rate is set to 1.6 BV / h, and the flow rate is not adjusted during the separation process. Except for the instructions, the process flow and parameters of Comparative Example 3 are consistent with those of Example 3.

[0076] The final galactose separation purity is shown in the following table: Table 1. Comparison of galactose purity

[0077] From the comparison in the table, it can be seen that if the flow rate is not controlled during the separation process, if the sample flow rate and eluent flow rate are set too high or too low, it is not conducive to the separation process, resulting in a decrease in the purity of the final galactose. If the flow rate is controlled during the separation process, the purity of the final galactose is significantly improved.

[0078] And the effectiveness of the flow control of this application has been verified through the curve of the optical rotation change after flow control, as shown in the following figure: Figure 2 As shown, Figure 2 The horizontal axis represents the sampling point number, from 1 to 17, and the vertical axis represents the optical rotation, in degrees, represented by the symbol °.

[0079] As can be seen from the figure, as the separation process proceeds, other sugars in the xylose mother liquor solution continue to decrease, while galactose continues to be enriched, so the optical rotation corresponding to galactose continues to increase. The real-time adjustment of the sample flow rate and the eluent flow rate makes the optical rotation change smoothly, achieving adsorption and desorption equilibrium during the separation process, and ultimately significantly improving the purity of galactose.

[0080] It is understood that references to "one embodiment" or "some embodiments" etc. described in the specification of the present application mean that one or more embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, if "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. appear in different places in this specification, they do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0081] It should be noted that the sequence of the above-mentioned embodiments of the present application is only for description and does not represent the advantages and disadvantages of the embodiments. And the above-mentioned specific embodiments of this specification are described. In addition, the process depicted in the accompanying drawings does not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multi-tasking and parallel processing are also possible or may be advantageous. At the same time, the size of the sequence number of each step in the embodiment does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments in this specification.

[0082] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A method for separating galactose from xylose mother liquor, characterized in that: The following steps are involved: S1, diluting the xylose mother liquor, and inoculating active dry yeast powder into the diluted xylose mother liquor for fermentation to obtain a xylose fermentation liquid; S2, filtering and concentrating the xylose fermentation broth to obtain a raw material; S3, controlling the sample flow rate and the eluent flow rate during the two-dimensional liquid chromatography separation of the raw material, the control process includes: S301: In the two-dimensional liquid chromatography system, a plurality of sampling points are sequentially set from the feed port end to the discharge port end, and the optical rotation of each sampling point at the current moment and all sampling moments before the current moment and a preset time length is obtained, and the bubble influence factor of each sampling point at the current moment is determined by analyzing the discrete degree of the optical rotation of each sampling point at the current moment and all sampling moments before the current moment, and the difference in the optical rotation of each sampling point between the current moment and the previous sampling moment, so as to obtain the corrected optical rotation of each sampling point at the current moment; S302: fitting the corrected optical rotations of all sampling points at the current moment to obtain a fitting curve, determining the peak width at the current moment according to the changing trend of the fitting curve between adjacent sampling points on both sides of the maximum value on the fitting curve, and determining the optical rotation change factor at the current moment in combination with the distribution of the changing trend of the fitting curve between all adjacent sampling points on the fitting curve and the extreme distribution of the fitting values ​​on the fitting curve, and controlling the sample flow rate and the eluent flow rate in the separation process at the current moment; S4, separating the stock solution to obtain a galactose component solution.

2. The method for separating galactose from xylose mother liquor according to claim 1, characterized in that: The components of the xylose mother liquor include, by mass fraction, 40% to 52% xylose, 25% to 32% arabinose, 10% to 18% glucose, 10% to 16% galactose, and 3% to 7% other impurities.

3. The method for separating galactose from xylose mother liquor according to claim 1, characterized in that: The method for diluting the xylose mother liquor and inoculating the active dry yeast powder into the diluted xylose mother liquor for fermentation to obtain the xylose fermentation liquid is as follows: using deionized water to dilute the xylose mother liquor to a refractive concentration of 15% to 30%, inoculating the active dry yeast powder into the diluted xylose mother liquor at a ratio of 0.1% to 0.4% (m / V), blowing air to oxygenate the diluted and inoculated xylose mother liquor and controlling the temperature at 25 to 35° C., and fermenting for 20 to 30 hours to obtain the xylose fermentation liquid.

4. The method for separating galactose from xylose mother liquor according to claim 1, characterized in that: The process of filtering and concentrating the xylose fermentation broth to obtain the raw material is as follows: filtering the color substances and inorganic ions in the xylose fermentation broth to obtain sugar solution, controlling the temperature of the sugar solution at 60-70° C., and evaporating and concentrating the sugar solution to a refractive index of 45%-65% to obtain the raw material.

5. The method for separating galactose from xylose mother liquor according to claim 1, characterized in that: The two-dimensional liquid chromatography separation of the raw materials includes: the stationary phase of the first-dimensional liquid chromatography system is one of calcium, sodium, potassium, hydrogen or hydroxyl-type styrene skeleton resin, including 7 to 9 chromatographic columns, each chromatographic column has a column height of 1m to 3m, a column diameter of 1m to 3m, and an operating temperature of 50 to 80°C; the stationary phase of the second-dimensional liquid chromatography system is one of calcium, sodium, potassium, hydrogen or hydroxyl-type styrene skeleton resin, including 7 to 9 chromatographic columns, each chromatographic column has a column height of 1m to 3m, a column diameter of 1m to 3m, and an operating temperature of 50 to 80°C.

6. The method for separating galactose from xylose mother liquor according to claim 1, characterized in that: The expression of the bubble influence factor of each sampling point at the current moment is: ; In the formula, Represents the bubble influence factor of the j-th sampling point at the current moment; Indicates the standard deviation of the optical rotation of the jth sampling point at the current moment and all previous sampling moments; Represents the difference in optical rotation of the jth sampling point between the current moment and its previous sampling moment; Represents a preset value; norm[ ] represents a normalization function; exp( ) represents an exponential function with a natural constant as the base.

7. The method for separating galactose from xylose mother liquor according to claim 1, characterized in that: The method for obtaining the corrected optical rotation of each sampling point at the current moment is: If the bubble influence factor of the j-th sampling point at the current moment is greater than the preset threshold, the optical rotation of the j-th sampling point at the current moment is eliminated, and the missing data at the j-th sampling point at the current moment is supplemented by the interpolation method, and the supplemented data is used as the corrected optical rotation of the j-th sampling point at the current moment; otherwise, the optical rotation of the j-th sampling point at the current moment is recorded as the corrected optical rotation of the j-th sampling point at the current moment.

8. The method for separating galactose from xylose mother liquor according to claim 1, characterized in that: The method for determining the peak width at the current moment is: Calculate the slope of the fitting curve between each sampling point on the fitting curve at the current moment and its previous sampling point as the slope value of each sampling point at the current moment; Taking the maximum value on the fitting curve at the current moment as the center, the total number of sampling points whose slope values ​​are continuously positive before the maximum value and the total number of sampling points whose slope values ​​are continuously negative after the maximum value are counted respectively. The sum of the total number of sampling points whose slope values ​​are continuously positive and the total number of sampling points whose slope values ​​are continuously negative is recorded as the peak width at the current moment.

9. The method for separating galactose from xylose mother liquor as claimed in claim 8, characterized in that: The expression of the optical rotation change factor at the current moment is: ; In the formula, Indicates the optical rotation change factor at the current moment; Represents the mean of the slope values ​​of all sampling points at the current moment; Indicates the peak width at the current moment; represents the maximum value on the fitting curve at the current moment; norm() represents the normalization function.

10. The method for separating galactose from xylose mother liquor according to claim 5, characterized in that: The control of the sample loading flow rate and the eluent flow rate in the separation process at the current moment includes: The optical rotation change factor at the current moment is used as the objective function of the optimization algorithm, and the constraint conditions are set as follows: the sample flow rate of the first-dimensional liquid chromatography system is within a preset first range, the eluent flow rate is within a preset second range, and the sample flow rate of the second-dimensional liquid chromatography system is within the preset first range, and the eluent flow rate is within the preset second range; The optimization algorithm is iterated, and the sample flow rate and eluent flow rate of the first and second dimensional liquid chromatography systems corresponding to the maximum value of the objective function are taken as the optimal sample flow rate and optimal eluent flow rate of the first and second dimensional liquid chromatography systems in the separation process at the current moment.

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