High-fluidity crystal L-arabinose and production method thereof

Abstract

The invention discloses a high-fluidity crystal L-arabinose and a production method thereof. The specific preparation method of the high-fluidity crystal L-arabinose comprises the following steps: xylose mother liquor treatment: fermenting xylose mother liquor to obtain a pretreatment solution; preparing a crystallization raw material: separating arabinose fraction feed liquid from the pretreatment liquid to serve as the crystallization raw material; and crystallization: carrying out staged cooling crystallization on the crystallization raw material at different cooling rates, and carrying out crystal growing for a certain time after cooling is finished, so as to obtain the L-arabinose crystal. The arabinose with coarse particles and high fluidity can be obtained through the method, can be used as powder for blanking or preparing powder products in production, and is directly applied to products such as solid preparations and solid beverages.

Description

Technical Field

[0001] The present application belongs to the field of biochemical engineering and relates to the production technology of L-arabinose, in particular to a crystalline L-arabinose with high fluidity and a preparation method thereof. Background Art

[0002] L-arabinose (C5H10O5) is an aldehyde pentose, also known as L(+)-arabinose. It was originally a monosaccharide isolated from gum arabic. Free L-arabinose rarely exists in nature. It is usually combined with other monosaccharides and exists in the form of heteropolysaccharides in colloids, hemicellulose, bacterial polysaccharides and certain glycosides. L-arabinose is a non-caloric sweetener that is increasingly used in the fields of food and medicine. It can be used as a pharmaceutical intermediate, for the preparation of bacterial culture media in the biochemical field, and for the synthesis of spices. L-arabinose products are becoming more and more popular as food sweeteners. Its medical and health functions, such as lowering blood sugar and preventing tooth decay, have also been confirmed by scientific research institutes.

[0003] Since free L-arabinose exists less in nature, it is mainly produced by industrial technology. In actual production, how to obtain L-arabinose particles with better fluidity is crucial. For example, patent CN 116554239 A mentions a method for preparing L-arabinose granules, the raw material of which is arabinose with a purity of ≥99%, which is re-dissolved for recrystallization, and centrifuged and dried to obtain granules to improve fluidity. The crystallization method adopted by patent CN 101665524 B requires 2 or more times of boiling sugar for crystallization. Each crystallization requires re-dissolving the sugar paste centrifuged from the last crystallization, evaporating and concentrating, and then crystallizing again. Patent CN116444584 A discloses two methods for preparing high-purity arabinose, both of which use finished arabinose as raw material, decolorize again after sugaring, and further process. However, these methods require multiple crystallizations, which increase energy consumption, and the yield is not high, which reduces production efficiency. Summary of the invention

[0004] In order to solve the problems existing in the above-mentioned prior art, the present application provides an improved L-arabinose preparation process, which can obtain arabinose with coarse particles and high fluidity.

[0005] The specific technical solutions of this application are as follows:

[0006] The present application provides a method for preparing L-arabinose, which comprises the following steps:

[0007] Xylose mother liquor treatment: fermenting the xylose mother liquor to obtain a pre-treated liquid;

[0008] Preparation of crystallization raw material: separating the arabinose fraction liquid from the pre-treated liquid as the crystallization raw material;

[0009] Crystallization: The crystallization raw material is cooled and crystallized in stages at different cooling rates, and after the cooling is completed, the crystal is grown for a certain period of time to obtain the L-arabinose crystal.

[0010] Furthermore, the crystallization step of the preparation method includes staged cooling crystallization at different cooling rates, and the staged cooling sequentially includes a first cooling stage, a second cooling stage and a third cooling stage. In the first cooling stage, the crystallization temperature drops to 55°C, in the second cooling stage, the crystallization temperature drops to 45°C, and in the third cooling stage, the crystallization temperature drops to 28~35°C.

[0011] Further preferably, the cooling rates of the first cooling stage, the second cooling stage and the third cooling stage increase successively.

[0012] Furthermore, the crystallization step of the preparation method also includes growing the crystal for a certain period of time after the staged cooling crystallization, and the growing time is 12 to 48 hours.

[0013] More preferably, the crystal growing temperature is 28-35°C.

[0014] Further preferably, the solid content of the L-arabinose crystals after crystal growth is ≥50%.

[0015] Furthermore, the xylose mother liquor treatment step of the preparation method includes removing miscellaneous sugars in the xylose mother liquor by fermentation.

[0016] Further preferably, the miscellaneous sugars include at least glucose and galactose.

[0017] Furthermore, the xylose mother liquor treatment step of the preparation method further comprises filtering and removing impurities in the xylose mother liquor after fermentation.

[0018] Further preferably, the impurities include gel, bacteria and macromolecular pigments.

[0019] Furthermore, the xylose mother liquor processing step of the preparation method also includes concentrating the xylose mother liquor after fermentation.

[0020] Further preferably, the pretreatment liquid has a sugar concentration of 45% to 55% after the concentration.

[0021] Furthermore, the crystallization raw material preparation step of the preparation method includes obtaining an arabinose fraction solution by chromatographic separation.

[0022] Further preferably, the arabinose content of the arabinose fraction liquid is 70% to 80%.

[0023] Furthermore, the crystallization raw material preparation step of the preparation method also includes decolorizing the arabinose fraction solution.

[0024] Further preferably, the decolorization treatment is carried out using activated carbon.

[0025] Furthermore, the crystallization raw material preparation step of the preparation method also includes desalting the arabinose fraction solution.

[0026] More preferably, the desalination treatment is carried out by ion exchange, electrodialysis and / or EDI electric desalination.

[0027] Furthermore, the crystallization raw material preparation step of the preparation method also includes concentrating the separated arabinose fraction liquid.

[0028] Further preferably, after concentration, the crystallization raw material has a sugar concentration of 55% to 65%.

[0029] Furthermore, the crystallization step of the preparation method also includes negative pressure concentration of the crystallization raw material before crystallization.

[0030] Further preferably, the crystallization raw material is concentrated to a sugar concentration of 72% to 78% by negative pressure concentration.

[0031] Furthermore, the crystallization step of the preparation method also includes adding seed crystals to the crystallization raw material before crystallization.

[0032] More preferably, the seed crystals are arabinose of 80-100 mesh.

[0033] Further preferably, the amount of the seed crystal added is 0.01% to 0.05% of the mass of the crystallization raw material.

[0034] Furthermore, the preparation method also includes the step of centrifugal separation after crystal growing.

[0035] Furthermore, the preparation method also includes a drying step after crystal growing.

[0036] More preferably, drying is performed after the centrifugal separation.

[0037] More preferably, the moisture content of the L-arabinose crystals after drying is less than 0.5%.

[0038] The present application also provides L-arabinose prepared by any of the preparation methods described above.

[0039] The present application also provides an L-arabinose, wherein the L-arabinose has an angle of repose <30°, a compression degree ≤10%, and a bulk density ≥0.8 g / cm 3 , the Hausner ratio is 1.00~1.11.

[0040] The present application also provides the preparation method or the use of the L-arabinose in the preparation of a powder product. Furthermore, the powder product includes a solid beverage or a solid preparation.

[0041] Effects of the Invention

[0042] The preparation method provided in this application has the following technical effects:

[0043] (1) The prior art generally adopts two crystallizations, while the technical solution of the present application adopts one crystallization, which can effectively shorten the production process and reduce the consumption of energy such as water, electricity, and steam, thereby improving production efficiency and saving energy;

[0044] (2) Compared with traditional sugar boiling crystallization, cooling crystallization reduces the residence time of sugar solution at high temperature, reduces the occurrence of Maillard reaction, isomerization, polymerization, decomposition and other reactions, thereby inhibiting the formation of crystallization inhibitors.

[0045] (3) During the arabinose crystal precipitation stage, the cooling rate is precisely controlled in stages, so that the arabinose particles appear to be long or short under an electron microscope, and the crystal surface is smooth. This morphology has better fluidity than slender needle-shaped crystals with rough surfaces, and is not prone to secondary breakage or agglomeration.

[0046] (4) Adding crystal growing steps and adjusting the crystal growing time can further increase the size of the crystal particles, improve fluidity, and increase the crystal yield to more than 60%.

[0047] The technical solution of the present application can obtain coarse-grained, high-fluidity arabinose, which can be directly used in the compounding of solid preparations, solid beverages, etc. without granulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 A schematic diagram of the process flow of a method for preparing L-arabinose provided in this application. DETAILED DESCRIPTION

[0049] The specific embodiments of the present application will be described in more detail below in conjunction with examples. It should be understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present application and to enable the scope of the present application to be fully communicated to those skilled in the art.

[0050] It should be noted that the words "including" or "comprising" mentioned throughout the specification and claims are open-ended terms and should be interpreted as "including but not limited to". The subsequent description of the specification is a preferred embodiment of the present application, but the description is for the purpose of illustrating the general principles of the present application and is not intended to limit the scope of the present application. The scope of protection of the present application shall be determined by the definition of the attached claims.

[0051] In one aspect of the present application, a method for preparing high-fluidity L-arabinose is provided, comprising the following steps:

[0052] Xylose mother liquor treatment: fermenting the xylose mother liquor to obtain a pre-treated liquid;

[0053] Preparation of crystallization raw material: separating the arabinose fraction liquid from the pre-treated liquid as the crystallization raw material;

[0054] Crystallization: The crystallization raw material is cooled and crystallized in stages at different cooling rates, and after the cooling is completed, the crystal is grown for a certain period of time to obtain the L-arabinose crystal.

[0055] In a specific embodiment, the xylose mother liquor in the present application comes from the xylose mother liquor of agricultural and forestry wastes, and the agricultural and forestry wastes include but are not limited to: corn cobs, wheat straw, beet pulp, sugarcane bagasse, crop straw, plant stems, leaves and roots, bran, corn husks, etc., and any other agricultural and forestry wastes containing pentoses.

[0056] In a specific embodiment, the xylose mother liquor contains xylose, xylan, L-arabinose, glucose, galactose, mannose, rhamnose and the like in addition to L-arabinose.

[0057] In a specific embodiment, most of the miscellaneous sugars except L-arabinose in the xylose mother liquor are removed by fermentation.

[0058] In some specific embodiments, the miscellaneous sugars include at least hexose such as glucose and galactose.

[0059] In some specific embodiments, glucose and galactose can be removed by conventional fermentation means. For example, glucose fermentation can use common baker's yeast or brewer's yeast as the nutrient carbon source of the strain to produce carbon dioxide and water or ethanol by changing the conditions, and galactose fermentation can be performed by screening strains that can utilize galactose and optimizing the fermentation conditions. Miscellaneous sugars with low contents such as mannose and rhamnose can produce carbon dioxide and water while fermenting glucose and galactose, and no additional processing steps are required.

[0060] In a specific embodiment, the xylose mother liquor treatment step further comprises a filtration step, wherein the impurities in the xylose mother liquor are removed by filtration after fermentation.

[0061] In a specific embodiment, the filtration step can further remove other miscellaneous sugar components in the xylose mother liquor, as well as impurities such as gel, bacteria and macromolecular pigments formed during the fermentation process.

[0062] In some specific embodiments, mechanical filtration equipment and / or membrane filtration equipment are used to remove impurities in the xylose mother liquor.

[0063] In a specific embodiment, the xylose mother liquor treatment step further includes a concentration step. In some preferred embodiments, the xylose mother liquor is concentrated after being fermented and filtered.

[0064] In some specific embodiments, after concentration, a pretreatment liquid with a sugar concentration of 45% to 55% is obtained, and subsequent crystallization raw material preparation operations are performed.

[0065] In a specific embodiment, the crystallization raw material preparation step of the preparation method comprises obtaining an arabinose fraction solution by chromatographic separation.

[0066] In some specific embodiments, the temperature of the chromatography separation system is set at 60° C. to 65° C., and the chromatography fraction with an arabinose content of 70% to 80% after chromatography separation is selected.

[0067] In some specific embodiments, the arabinose content of the arabinose fraction solution obtained by chromatographic separation is 70% to 80%.

[0068] In a specific embodiment, the crystallization raw material preparation step further comprises decolorizing the arabinose fraction solution obtained by chromatographic separation.

[0069] In some specific embodiments, the decolorization treatment is performed using activated carbon.

[0070] In some preferred embodiments, 0.05% to 0.5% (mass percentage) of activated carbon is added to the arabinose fraction solution obtained by chromatographic separation, stirred at 50° C. to 65° C. for 30 min to 60 min, and the waste carbon is removed by plate and frame filtration to obtain a decolorized solution.

[0071] In a specific embodiment, the crystallization raw material preparation step further includes desalting the arabinose fraction solution.

[0072] In some specific embodiments, the decolorizing solution is further subjected to a desalting treatment after the above-mentioned decolorizing treatment.

[0073] In some specific embodiments, the desalination treatment is performed by one or more of ion exchange, electrodialysis and EDI electric desalination.

[0074] In some specific embodiments, the desalination treatment includes first using electrodialysis or EDI desalination, and then performing ion exchange desalination.

[0075] In a specific embodiment, salt and residual pigments are removed by desalination.

[0076] In a specific embodiment, the crystallization raw material preparation step further comprises concentrating the separated arabinose fraction solution.

[0077] In some specific embodiments, after the above-mentioned decolorization treatment and / or desalination treatment, a concentration treatment is further performed.

[0078] In some specific embodiments, MVR or triple-effect concentration is used for concentration treatment.

[0079] In some specific embodiments, when the sugar concentration of the feed solution is lower than 60%, a triple-effect vacuum falling film evaporator is used for concentration, and when the sugar concentration of the feed solution is higher than 60%, a single-effect vacuum evaporator is used for concentration.

[0080] In some specific embodiments, after concentration, a crystalline raw material having a sugar concentration of 55% to 65% is obtained.

[0081] In a specific embodiment, the above-mentioned crystallization raw material, preferably the crystallization raw material after being decolorized, desalted and concentrated, is further subjected to a subsequent crystallization step.

[0082] In an embodiment of the present application, the crystallization step includes performing staged cooling crystallization at different cooling rates.

[0083] In a specific embodiment, the staged cooling is to precisely control the corresponding cooling rates in different cooling stages so that the crystal particles change from the original slender needle shape to a thick and long or thick and short shape.

[0084] In some specific embodiments, the staged cooling process includes three cooling stages, namely, a first cooling stage, a second cooling stage and a third cooling stage.

[0085] In some specific embodiments, the temperature is lowered very slowly in the first cooling stage to allow the already formed fine nuclei to grow slowly, preventing the temperature from lowering too fast, causing nucleation to explode, and forming a large number of fine crystals. In the case of extremely slow cooling, the crystals that precipitate as the supersaturation increases with the temperature decrease preferentially attach to the existing nuclei and grow, and it is not easy to form new nuclei, so that the nuclei are few and large. In the second cooling stage, the nuclei have grown up, and the cooling rate can be appropriately accelerated to induce the newly precipitated crystals to continue to attach to the existing nuclei and grow further. In the third cooling stage, the cooling rate is further accelerated to accelerate the precipitation of crystals and shorten the crystallization time to improve production efficiency.

[0086] In some specific embodiments, in the first cooling stage, the crystallization temperature is reduced to 55°C, in the second cooling stage, the crystallization temperature is reduced to 45°C, and in the third cooling stage, the crystallization temperature is reduced to 28-35°C.

[0087] In some preferred embodiments, the cooling rate in the first cooling stage is 0.3°C / h~0.5°C / h, the cooling rate in the second cooling stage is 0.5°C / h~1.0°C / h, and the cooling rate in the third cooling stage is 1.0°C / h~1.5°C / h, and the rate will reach 28~35°C.

[0088] In a specific embodiment, the preparation method further comprises concentrating the crystallization raw material under negative pressure before the crystallization step.

[0089] In some specific embodiments, the negative pressure concentration includes concentrating the crystallization raw material under negative pressure in a sugar boiling tank at a temperature of 60°C to 70°C.

[0090] In some specific embodiments, the crystallization raw material is concentrated to a sugar concentration of 72% to 78% by negative pressure concentration.

[0091] In a specific embodiment, the preparation method further comprises adding seed crystals to the crystallization raw material before the crystallization step.

[0092] In some specific embodiments, the seed crystal is arabinose of 80-100 mesh.

[0093] In some specific embodiments, the amount of the seed crystal added is 0.01% to 0.05% of the mass of the crystallization raw material.

[0094] In some specific implementations, it is necessary to ensure that the seed crystals do not melt. If the seed crystals melt, appropriate additional seed crystals are added.

[0095] In some specific embodiments, the crystallization raw material after adding the seed crystal is discharged into a crystallizer for the staged cooling crystallization.

[0096] In a specific embodiment, the crystallization step further includes growing crystals after staged cooling crystallization.

[0097] In a specific embodiment, the crystal growing is carried out at a crystal growing temperature of 28-35° C. (i.e., the temperature after the third cooling stage ends).

[0098] In a specific implementation manner, the stirring is maintained at the crystal growing temperature for a duration of 12 to 48 hours.

[0099] In some preferred embodiments, the solid content of L-arabinose crystals in the massecuite obtained after crystal growing is ≥50%.

[0100] In a specific embodiment, the preparation method further comprises the step of centrifugal separation after crystal growing.

[0101] In some specific embodiments, the L-arabinose paste obtained after crystal aging is centrifuged, and when no mother liquor is observed to be secreted during the centrifugation process, high-purity water is sprayed intermittently for washing until the crystals in the centrifuge are observed to turn white through the sight glass and the centrifugation is stopped when the washing liquid is no longer secreted.

[0102] In a specific embodiment, the preparation method further comprises a drying step after crystal growing.

[0103] In some specific embodiments, the centrifugal separation is performed first after crystal growth, and then the L-arabinose crystals obtained after the centrifugal separation are dried.

[0104] In some specific embodiments, the centrifuged L-arabinose crystals are placed in a fluidized bed for staged drying.

[0105] In some preferred embodiments, the temperature of the hot air section of the staged drying is 95° C. to 105° C., the temperature of the warm air section is 50° C. to 60° C., and the temperature of the cold air section is 20° C. to 25° C. By adjusting the temperature, the discharge temperature and the ambient temperature of the packaging room are controlled to be less than 5° C.

[0106] In some specific embodiments, the moisture content of the L-arabinose crystals obtained after drying is less than 0.5%.

[0107] In some embodiments, a scanning electron microscope is used to observe the crystal morphology, and to detect the flowability index and application status of the crystal.

[0108] The present application also provides L-arabinose prepared by any of the preparation methods described above.

[0109] The present application also provides an L-arabinose, wherein the angle of repose of the L-arabinose is less than 30°, for example, the angle of repose is 29°, 28°, 27°, 26°, 25°, 24°, 23°, 22°, 21°, 20°, the compression degree of the L-arabinose is ≤10%, for example, the compression degree is 10%, 9.5%, 9%, 8.5%, 8%, 7.5%, 7%, 6.5%, 6%, 5.5%, 5%, and the bulk density of the L-arabinose is ≥0.8 g / cm 3 , for example, the bulk density is 0.8 g / cm 3 , 0.75 g / cm 3 , 0.7 g / cm 3 , 0.65 g / cm 3 , 0.6 g / cm 3 , 0.55g / cm 3, 0.5 g / cm 3 , 0.4 g / cm 3 , the Hausner ratio of the L-arabinose is 1.00-1.11, for example, the Hausner ratio is 1, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09, 1.10, 1.11.

[0110] The L-arabinose provided in the present application is a high-fluidity crystal, which can be conveniently used as a powder feed in production or in the preparation of powder products (such as solid beverages, etc.).

[0111] Example

[0112] This application generally and / or specifically describes the materials and experimental methods used in the experiments. In the following examples, the seed crystals used are L-arabinose produced by Jinan Shengquan Tanghetang Biotechnology Co., Ltd., with a purity of ≥99% (in compliance with standard QB / T 4321-2012), and are ground and sieved through 80-100 mesh. The remaining reagents or instruments used, unless otherwise specified, are conventional reagents or instruments that can be purchased commercially.

[0113] Example 1

[0114] (1) Xylose mother liquor treatment: The xylose mother liquor is fermented to obtain a pretreated liquid.

[0115] (2) Preparation of crystallization raw material: The pre-treated liquid obtained in the previous step was separated by chromatography, and the chromatographic fraction with an arabinose content of 75.43% was added with activated carbon accounting for 0.1% of the mass of the sugar solution at 60°C. After stirring for 40 minutes, the activated carbon was removed by filtration to obtain a decolorized sugar solution. The decolorized sugar solution was removed from salt and some residual pigments by an ion exchange system, and then concentrated to a sugar concentration of 60% to be used as a crystallization raw material.

[0116] (3) Crystallization: The crystallization raw material obtained in the previous step is concentrated under negative pressure in a vacuum reactor. During the concentration process, the temperature of the sugar solution is 65℃~67℃. After the concentration reaches 73% sugar concentration, arabinose with a size of 80-100 meshes accounting for 0.03% of the base material mass is added as a seed crystal. After stirring evenly, the concentration is stopped and the temperature is lowered in stages: the first stage is from 65℃~67℃ to 55℃, with a cooling rate of 0.3℃ / h; the second stage is from 55℃ to 45℃, with a cooling rate of 0.75℃ / h; the third stage is from 45℃ to 30℃, with a cooling rate of 1.2℃ / h. After the cooling is completed, the mixture is kept warm and stirred at 30℃ for 24 hours for crystal growth, so that the crystals continue to precipitate and the particles grow.

[0117] (4) Centrifugal drying: After the crystal growth is completed, the sugar paste is transferred to a centrifuge for centrifugation. When no mother liquor is observed to be secreted during the centrifugation process, high-purity water is sprayed intermittently for washing until the crystals in the centrifuge are observed to turn white through the sight glass and the centrifugation is stopped when the washing liquid no longer secretes. The crystals after centrifugation are placed in a fluidized bed for segmented drying. The temperature of the hot air section is 95℃~105℃, the temperature of the warm air section is 50℃~60℃, and the temperature of the cold air section is 20℃~25℃. The moisture content of the arabinose after drying is controlled to be less than 0.5%. The yield of arabinose is 60.32%. Yield = mass of arabinose after drying / mass of arabinose in the crystallization raw material*100%;

[0118] Example 2

[0119] The difference between Example 2 and Example 1 is that the staged cooling rates in the crystallization step are: the first stage is cooling from 65°C~67°C to 55°C, with a cooling rate of 0.3°C / h, the second stage is cooling from 55°C to 45°C, with a cooling rate of 0.75°C / h, and the third stage is cooling from 45°C to 30°C, with a cooling rate of 1.35°C / h.

[0120] Example 3

[0121] The difference between Example 3 and Example 1 is that the staged cooling rates in the crystallization step are: the first stage is cooling from 65°C~67°C to 55°C, with a cooling rate of 0.3°C / h, the second stage is cooling from 55°C to 45°C, with a cooling rate of 0.75°C / h, and the third stage is cooling from 45°C to 30°C, with a cooling rate of 1.5°C / h.

[0122] Example 4

[0123] The difference between Example 4 and Example 1 is that the staged cooling rates in the crystallization step are: the first stage is cooling from 65°C~67°C to 55°C, with a cooling rate of 0.3°C / h, the second stage is cooling from 55°C to 45°C, with a cooling rate of 0.85°C / h, and the third stage is cooling from 45°C to 30°C, with a cooling rate of 1.5°C / h.

[0124] Example 5

[0125] The difference between Example 5 and Example 1 is that the staged cooling rates in the crystallization step are: the first stage is cooling from 65°C~67°C to 55°C, with a cooling rate of 0.3°C / h, the second stage is cooling from 55°C to 45°C, with a cooling rate of 1°C / h, and the third stage is cooling from 45°C to 30°C, with a cooling rate of 1.5°C / h.

[0126] Example 6

[0127] The difference between Example 6 and Example 1 is that the staged cooling rates in the crystallization step are: the first stage is cooling from 65°C~67°C to 55°C, with a cooling rate of 0.4°C / h, the second stage is cooling from 55°C to 45°C, with a cooling rate of 1°C / h, and the third stage is cooling from 45°C to 30°C, with a cooling rate of 1.5°C / h.

[0128] Example 7

[0129] The difference between Example 7 and Example 1 is that the staged cooling rates in the crystallization step are: the first stage is cooling from 65°C~67°C to 55°C, with a cooling rate of 0.5°C / h, the second stage is cooling from 55°C to 45°C, with a cooling rate of 1°C / h, and the third stage is cooling from 45°C to 30°C, with a cooling rate of 1.5°C / h.

[0130] Example 8

[0131] The difference between Example 8 and Example 7 is that the crystal growing time in the crystallization step is 12 hours.

[0132] Example 9

[0133] The difference between Example 9 and Example 7 is that the crystal growing time in the crystallization step is 48 hours.

[0134] Comparative Example 1

[0135] The difference between Comparative Example 1 and Example 7 is that there is no crystal growing time in the crystallization step (the crystal growing time is 0 hours).

[0136] Comparative Example 2

[0137] The difference between Comparative Example 2 and Example 1 is that there is no crystal growing time in the crystallization step (the crystal growing time is 0 hours).

[0138] Comparative Example 3

[0139] The difference between Comparative Example 3 and Example 1 is that the staged cooling in the crystallization step is changed to continuous cooling to 30° C. at a fixed cooling rate of 1° C. / h, and crystal cultivation is carried out for 24 hours.

[0140] Comparative Example 4

[0141] The difference between Comparative Example 4 and Example 1 is that: finished arabinose with a sugar content of 99.1% is used as raw material for crystallization, the staged cooling in the crystallization step is changed to continuous cooling to 50°C at a fixed cooling rate of 1°C / h, and centrifugation is directly performed without crystal cultivation.

[0142] Comparative Example 5

[0143] (1) Xylose mother liquor treatment: The xylose mother liquor is fermented to obtain a pretreated liquid.

[0144] (2) Preparation of crystallization raw material: The pre-treated liquid obtained in the previous step was separated by chromatography, and the chromatographic fraction with an arabinose content of 75.43% was added with activated carbon accounting for 0.1% of the mass of the sugar solution at 60°C. After stirring for 40 minutes, the activated carbon was removed by filtration to obtain a decolorized sugar solution. The decolorized sugar solution was removed from salt and some residual pigments by an ion exchange system, and then concentrated to a sugar concentration of 60% to be used as a crystallization raw material.

[0145] (3) Feed crystallization: Take half of the crystallization raw material obtained in the previous step and add it to a vacuum reactor for negative pressure concentration. Control the concentration temperature at 65°C~67°C. When the sugar concentration reaches 72%, add arabinose with a size of 80-100 mesh, which accounts for 0.03% of the base material mass, as a seed crystal. After stirring evenly, start feeding the remaining sugar solution. The feeding process is completed in about 11 hours.

[0146] (4) Centrifugal drying: After the addition is completed, continue to concentrate for 1 hour and transfer to a centrifuge for centrifugation. When no mother liquor is observed to be secreted during the centrifugation process, spray high-purity water for washing intermittently until the crystals in the centrifuge are observed to turn white from the sight glass and the centrifugation is stopped when the washing liquid no longer secretes. The crystals after centrifugation enter the fluidized bed for segmented drying. The temperature of the hot air section is 95℃~105℃, the temperature of the warm air section is 50℃~60℃, and the temperature of the cold air section is 20℃~25℃. The moisture content of arabinose after drying is controlled to be less than 0.5%. The yield of arabinose is 47.93%.

[0147] Comparative Example 6

[0148] (1) Feed crystallization: Dissolve the finished arabinose with a content of 99.1% at 60°C to a sugar concentration of 50%. Take half of it and add it to a vacuum reactor for negative pressure concentration to a sugar concentration of 59%. Add arabinose with a size of 80-100 mesh, which accounts for 0.03% of the mass of the base material, as a seed crystal. After stirring evenly, start feeding the remaining sugar solution. The feeding process is completed in about 11 hours.

[0149] (2) Centrifugal drying: After the addition is completed, continue to concentrate for 1 hour and transfer to a centrifuge for centrifugation. When no mother liquor is observed to be secreted during the centrifugation process, spray high-purity water for washing intermittently until the crystals in the centrifuge are observed to turn white from the sight glass and the centrifugation is stopped when the washing liquid no longer secretes. The crystals after centrifugation enter the fluidized bed for segmented drying. The temperature of the hot air section is 95℃~105℃, the temperature of the warm air section is 50℃~60℃, and the temperature of the cold air section is 20℃~25℃. The moisture content of arabinose after drying is controlled to be less than 0.5%. The yield of arabinose is 45.43%.

[0150] Comparative Example 7

[0151] The difference between Comparative Example 7 and Example 1 is that the staged cooling rates in the crystallization step are: the first stage is cooled from 65°C~67°C to 55°C, the cooling rate is 0.5°C / h, the second stage is cooled from 55°C to 45°C, the cooling rate is 1°C / h, the third stage is cooled from 45°C to 30°C, the cooling rate is 0.5°C / h, and the arabinose yield is 52.32%.

[0152] Comparative Example 8

[0153] The difference between Comparative Example 8 and Example 1 is that the staged cooling rates in the crystallization step are: the first stage is cooled from 65°C~67°C to 55°C, the cooling rate is 1.5°C / h, the second stage is cooled from 55°C to 45°C, the cooling rate is 1°C / h, the third stage is cooled from 45°C to 30°C, the cooling rate is 0.5°C / h, and the arabinose yield is 50.87%.

[0154] The performance of the arabinose obtained in each example and comparative example was tested according to the following method:

[0155] The dried arabinose was tested for bulk density, tap density, compression, Hausner ratio, and angle of repose, and the average value was obtained after three tests. The packaging application was tested on a three-sided peak powder packaging machine, especially to observe whether the packaging material was unloaded smoothly and whether the bag was stuck during the packaging process.

[0156] The main instruments and detection methods used in the above experiments and detection processes are as follows:

[0157] Electron microscope: TESCAN CLARA field emission scanning electron microscope;

[0158] Sugar concentration: tested with a handheld saccharimeter;

[0159] Arabinose content: HPLC detection, area normalization method calculation;

[0160] Solid content: The percentage of crystals obtained by centrifugation of the massecuite in the sugar boiling tank;

[0161] Angle of repose: The angle of repose tester complies with the national standard GB11986-89 and the international standard ISO4324-1977; three repetitive tests are performed for each test and the average value is taken. When the angle of repose is greater than 60°, no reading can be made, and at the same time, the compression is greater than 38%, and the Hausner ratio is greater than 1.60, the fluidity is judged to be very poor.

[0162] Bulk density: Detected by FT-103 natural loose bulk density meter, in line with standard GB / T 16913.3-1997.

[0163] Tap density: tested by HY-100A powder density tester.

[0164] Application test: Finished arabinose is packaged on an automatic packaging machine for powder and granule preparations to observe its fluidity. The equipment uses Jinan Tianlu's DXD-F three-side sealing powder packaging machine, taking 15g per bag as an example.

[0165] The main parameters and test results of each embodiment and comparative example are shown in Table 1 and Table 2.

[0166] Table 1

[0167]

[0168] Table 2

[0169]

[0170] From the experimental results of the above embodiments and comparative examples, it can be seen that:

[0171] (1) By adopting the staged cooling and crystallization method proposed in this application, and continuing to grow crystals after cooling, a higher product yield can be obtained, which can reach more than 50%. The product has excellent fluidity and can be unloaded smoothly without bag jamming when used in small bag packaging. Especially when the cooling rate in the first and second stages of the staged cooling is relatively slow (such as Examples 1-5), the product yield is higher (up to more than 60%) and the fluidity is better (angle of repose <30°, bulk density >0.8g / cm 3 ).

[0172] (2) The results of Examples 1 and 9 and Comparative Examples 1 and 2 show that when the product is centrifuged immediately after the staged cooling without the crystal growing step, the repose angle of the product increases to more than 45° and the fluidity is poor. When the product is used for small bag packaging, there will be a jam during the unloading process, resulting in occasional bag jamming.

[0173] (3) The results of comparative example 3 show that when the crystallization is not carried out by cooling in stages, the temperature is cooled at a constant rate during the entire cooling process, and the crystal is grown, the yield can be greater than 50% when the raw material arabinose content is low, but the repose angle cannot be read. When the repose angle is changed to greater than 60°, the material is stuck when it is unloaded when it is used for small bag packaging, resulting in material jamming in the bag, indicating that its fluidity is very poor.

[0174] (4) The results of Comparative Example 4 show that when the finished arabinose (purity> 99%) is used as the raw material for crystallization, the temperature is lowered at a constant rate throughout the cooling process. When the temperature is lowered to 50°C, the supersaturation is large, the sugar paste is viscous, the stirring current suddenly increases, and the load is too high. Centrifugal treatment is required, and the product yield is low and the fluidity is poor.

[0175] (5) Comparative Examples 5 and 6 used conventional fed-batch crystallization, resulting in low product yield and poor fluidity.

[0176] (6) Comparative Examples 7 and 8 show that the cooling rate in the staged cooling process is also important. If the cooling rate is not accelerated step by step (e.g., a cooling rate that is fast at first and slow later, or slow at first and slow in the middle), although the yield can reach 50% after 24 hours of crystal growth, the product bulk density is extremely low, the angle of repose is greater than 60°, and the fluidity is extremely poor.

[0177] In summary, the use of a slow cooling rate followed by a fast cooling rate in stages can significantly improve the fluidity of the arabinose product, making its repose angle less than 40°. When the high temperature stage is extremely slow, the repose angle is less than 30°, and the bulk density is greater than 0.8 g / cm 3 ; Through crystal cultivation, the fluidity is further improved and the yield is greatly increased to 60%. In actual production, extremely slow cooling can be used within the cooling rate range to obtain higher fluidity according to application requirements; or, on the premise of meeting application requirements, the cooling rate can be appropriately accelerated within the range to shorten production time and increase production capacity.

[0178] The above is only the preferred embodiment of the present application, and does not limit the present application in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present application without departing from the technical solution of the present application still falls within the protection scope of the technical solution of the present application.

Claims

1. A method for preparing high-fluidity crystalline L-arabinose, comprising the following steps: Xylose mother liquor treatment: fermenting the xylose mother liquor to obtain a pre-treated liquid; Preparation of crystallization raw material: separating the arabinose fraction liquid from the pre-treated liquid as the crystallization raw material; Crystallization: adding seed crystals to the crystallization raw material, performing staged cooling and crystallization at different cooling rates, and performing crystal cultivation for a certain period of time after the cooling is completed to obtain the L-arabinose crystals. Among them, the staged cooling includes a first cooling stage, a second cooling stage and a third cooling stage in sequence. In the first cooling stage, the crystallization temperature drops to 55°C, in the second cooling stage, the crystallization temperature drops to 45°C, in the third cooling stage, the crystallization temperature drops to 28~35°C, and the cooling rates of the first cooling stage, the second cooling stage and the third cooling stage increase in sequence.

2. The preparation method according to claim 1, wherein The crystal growing temperature is 28-35° C., and the crystal growing time is 12-48 hours.

3. The preparation method according to claim 1, wherein The solid content of the L-arabinose crystals obtained after crystal growth is ≥50%.

4. The preparation method according to claim 1, wherein The xylose mother liquor treatment step includes removing miscellaneous sugars in the xylose mother liquor by fermentation.

5. The preparation method according to claim 1, wherein The xylose mother liquor treatment step also includes filtering to remove impurities in the xylose mother liquor after fermentation.

6. The preparation method according to claim 1, wherein The xylose mother liquor treatment step also includes concentrating the xylose mother liquor after fermentation.

7. The preparation method according to claim 1, wherein In the step of preparing the crystallization raw material, the arabinose fraction solution is obtained by chromatographic separation.

8. The preparation method according to claim 1, wherein The crystallization raw material preparation step also includes decolorizing the arabinose fraction solution.

9. The preparation method according to claim 1, wherein The crystallization raw material preparation step also includes desalting the arabinose fraction solution.

10. The preparation method according to claim 1, wherein: The crystallization raw material preparation step also includes concentrating the arabinose fraction solution.

11. The preparation method according to claim 1, wherein: The crystallization step also includes concentrating the crystallization raw material under negative pressure before crystallization.

12. The preparation method according to claim 1, wherein: The preparation method also includes a step of centrifugal separation after crystal growth.

13. The preparation method according to claim 1, wherein: The preparation method also includes a drying step after crystal growth.

14. Use of the method according to any one of claims 1 to 13 in preparing a powder product, wherein the powder product comprises a solid beverage or a solid preparation.

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