Method for preparing fructooligosaccharide

Abstract

Provided in the present invention is a method for preparing a fructooligosaccharide, pertaining to the technical field of fructooligosaccharide synthesis. The method of the present invention comprises the following steps: (1) preparing a reaction stock solution; (2) adding a fructosyltransferase to the reaction stock solution and then carrying out a constant-temperature water bath reaction; during the reaction, supplementing with a sugar solution to continue the reaction to obtain a first-process saccharified solution; (3) filtering the first-process saccharified solution through a semipermeable membrane to obtain a retentate and a filtrate; (4) subjecting the filtrate to a constant-temperature water bath reaction to obtain a second-process saccharified solution, and then mixing the second-process saccharified solution with the retentate to obtain a crude fructooligosaccharide solution; and (5) subjecting the crude fructooligosaccharide solution to decolorization, desalting, chromatographic separation, evaporative concentration, and drying to prepare a fructooligosaccharide powder. The method shortens the reaction time, increases the utilization rate of fructose, promotes the generation of kestose in the system, raises the content of kestose in the fructooligosaccharide, and reduces the water activity of the fructooligosaccharide.

Description

A method for preparing oligofructose

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese Patent Application No. 202411832681.8, filed on December 13, 2024, entitled “A method for preparing fructooligosaccharides”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to the field of fructooligosaccharide synthesis, and particularly to a method for preparing fructooligosaccharides. Background Technology

[0004] Fructooligosaccharides (FOS), also known as fructooligosaccharides, are a mixture of fructotriose (GF2), fructotetraose (GF3), and fructopentose (GF4) formed by sucrose molecules linked to 1-3 fructose molecules via β-(1→2) glycosidic bonds. Their molecular formula is GF-Fn. FOS possesses both prebiotic and dietary fiber functions, making them suitable for diabetics. They lower cholesterol, improve lipid metabolism, and promote the growth of beneficial bacteria in the gut, thus offering excellent health benefits. Currently, industrial production of FOS primarily uses sucrose as a raw material, utilizing fructosyltransferase (FTase) or β-fructofuranosidase (FFase) for enzymatic conversion. Studies have shown that fructotriose in FOS is more effective than other FOS in promoting probiotic growth. Its lower degree of polymerization makes it easier to absorb and utilize in the human gut, but its low content and difficulty in separation and purification have always been major obstacles to industrial production.

[0005] Chinese patent document CN104928332A discloses a method for preparing high-purity fructooligosaccharides. The method includes the following steps: (1) hydrolyzing chicory with inulinase to obtain a primary fructooligosaccharide solution; (2) decolorizing, debittering, and desalting the primary fructooligosaccharide solution in step (1) to obtain a secondary fructooligosaccharide solution; (3) adding β-D-fructosyltransferase to the secondary fructooligosaccharide solution in step (2) and reacting at 20-35℃ for 1-8 hours to obtain a tertiary fructooligosaccharide solution; (4) treating the tertiary fructooligosaccharide mixture obtained in step (3) with a nanofiltration membrane, collecting the filtrate, and obtaining an fructooligosaccharide solution with a purity greater than 99%. Although the fructooligosaccharides in this invention have high purity, the degree of polymerization is in the range of 4-6, resulting in low fructooligosaccharide content and high water activity. The product is prone to moisture absorption and is not conducive to preservation and extending shelf life.

[0006] Chinese patent document CN110669808A discloses a method for preparing fructooligosaccharides with high fructosaccharide content. The method includes the following steps: (1) mixing ionic liquid and fructosyltransferase in a mass ratio of (0.7-1):2 and allowing it to stand for equilibrium; (2) preparing a sucrose solution with a mass fraction of 55-56% in a reaction vessel, and then adjusting the pH of the sucrose solution to 5.5-5.8; (3) placing the reaction vessel in a water bath at a constant temperature of 45-52℃ and heating it. After the temperature of the sucrose solution is balanced, adding the balanced ionic liquid and fructosyltransferase mixture, and continuously stirring the saccharification reaction for 11-14 hours, then adding the fructose solution to continue the saccharification reaction for 30-35 hours, and terminating the saccharification reaction by inactivating the enzyme; after decolorization, filtration, membrane filtration, chromatographic separation, and concentration, liquid fructooligosaccharides with high fructosaccharide content are prepared, with fructosaccharide accounting for 87-93% of the fructooligosaccharides, and the chromatographic separation yield of fructooligosaccharides is above 97%. Although the invention produces a high content of fructooligosaccharides, the overall reaction time is relatively long, and the yield of oligofructose and the content of fructooligosaccharides can be further improved.

[0007] In summary, there is currently a lack of technology that can further improve the yield of fructooligosaccharides and the content of sucrose trisaccharides while achieving saccharification and polymerization in a shorter time and obtain fructooligosaccharides with low water activity. Summary of the Invention

[0008] In view of this, the purpose of this invention is to provide a method for preparing fructooligosaccharides; this invention uses Fe 2+ Ions act as thermal stabilizers for fructosyltransferases, allowing for segmented saccharification by controlling temperature and time during the saccharification process. Sucrose solution is added as needed, and a semi-permeable membrane device is incorporated during saccharification to collect fructosyltransferase. This shortens the reaction time, increases fructose utilization, promotes the formation of fructosyltransferase in the system, increases the fructosyltransferase content in fructooligosaccharides, and reduces the water activity of fructooligosaccharides.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] This invention provides a method for preparing fructooligosaccharides, comprising the following steps:

[0011] (1) Add Fe to the sucrose solution 2+ Then adjust the pH to obtain the reaction stock solution;

[0012] (2) After adding fructosyltransferase to the reaction stock solution, a constant temperature water bath reaction is carried out; when the sucrose mass fraction in the system is 35-40%, sucrose solution is added to make the sucrose mass fraction 50-55%, and then the reaction is continued for 10-12 hours to obtain the first process saccharification solution;

[0013] (3) The saccharification solution of the first process is filtered using a semi-permeable membrane with a molecular weight cutoff of 350-500 Da to obtain a retentate and a filtrate;

[0014] (4) The filtrate is subjected to a constant temperature water bath reaction to obtain the second process saccharification liquid, and then the second process saccharification liquid is mixed with the retentate to obtain the crude oligofructose liquid;

[0015] (5) Add activated carbon to the crude fructooligosaccharide liquid and filter it after decolorization to obtain the first filtrate.

[0016] (6) The first filtrate is desalted using strong acid cation resin D001 and weak base anion resin D301P to obtain the second filtrate.

[0017] (7) The second filtrate was separated by chromatography, concentrated by evaporation, and dried to prepare fructooligosaccharide powder;

[0018] In step (2), the constant temperature water bath reaction temperature is 60-65℃, and the reaction time is 5-7h;

[0019] In step (4), the water bath reaction temperature is 40-45℃ and the reaction time is 4-6h.

[0020] Preferably, the sucrose solution in step (1) has a mass fraction of 55-60%.

[0021] Preferably, Fe in step (1) 2+ The amount added is 45-55 mM.

[0022] Preferably, the pH is adjusted to 5.5 to 6.0 in step (1).

[0023] Preferably, the amount of fructosyltransferase added in step (2) is 6-8 U / g.

[0024] Preferably, the amount of activated carbon added in step (5) is 1.0 to 2.0% of the dry weight of the crude fructooligosaccharide liquid.

[0025] Preferably, the decolorization temperature in step (5) is 55-60°C and the time is 15-20 min.

[0026] Preferably, in step (6), the material feeding temperature is 35-40℃, the material feeding speed is 1-3 BV / h, and the output pH is 5.0-6.0.

[0027] Beneficial technical effects:

[0028] This invention overcomes the problems of long reaction time, low fructooligosaccharide content, low water activity, and easy hygroscopicity in the preparation of fructooligosaccharides. The resulting fructooligosaccharides have a fructooligosaccharide content ≥95%, a fructooligosaccharide conversion rate of 65-70%, a fructose residue ratio of ≤2%, and a water activity of 0.83-0.86 (based on a 50% concentration). The fructooligosaccharides prepared by this invention contain a high content of fructooligosaccharides, resulting in better intestinal probiotic proliferation. Simultaneously, the low water activity reduces hygroscopicity and extends the product's shelf life. Detailed Implementation

[0029] This invention provides a method for preparing fructooligosaccharides, comprising the following steps:

[0030] (1) Add Fe to the sucrose solution 2+ Then adjust the pH to obtain the reaction stock solution;

[0031] (2) After adding fructosyltransferase to the reaction stock solution, a constant temperature water bath reaction is carried out; when the sucrose mass fraction in the system is 35-40%, sucrose solution is added to make the sucrose mass fraction 50-55%, and then the reaction is continued for 10-12 hours to obtain the first process saccharification solution;

[0032] (3) The saccharification solution of the first process is filtered using a semi-permeable membrane with a molecular weight cutoff of 350-500 Da to obtain a retentate and a filtrate;

[0033] (4) The filtrate is subjected to a constant temperature water bath reaction to obtain the second process saccharification liquid, and then the second process saccharification liquid is mixed with the retentate to obtain the crude oligofructose liquid;

[0034] (5) Add activated carbon to the crude fructooligosaccharide liquid and filter it after decolorization to obtain the first filtrate.

[0035] (6) The first filtrate is desalted using strong acid cation resin D001 and weak base anion resin D301P to obtain the second filtrate.

[0036] (7) The second filtrate was separated by chromatography, concentrated by evaporation, and dried to prepare fructooligosaccharide powder.

[0037] This invention adds Fe to a sucrose solution 2+ Then adjust the pH to obtain the reaction stock solution.

[0038] In this invention, the mass fraction of the sucrose solution is preferably 55-60%, such as 55%, 56%, 57%, 58%, 59%, or 60%, and is preferably within the range of any of the above values ​​as the upper or lower limit.

[0039] In this invention, the Fe 2+The preferred amount of the additive is 45-55 mM, more preferably 48-53 mM, such as 45 mM, 46 mM, 47 mM, 48 mM, 49 mM, 50 mM, 51 mM, 52 mM, 53 mM, 54 mM, 55 mM, and preferably any of the above values ​​as the upper or lower limit.

[0040] This invention adds Fe ions, which can protect the thermal stability of the enzyme, to the sucrose solution before the reaction. 2+ Increasing the reaction temperature can effectively protect the enzyme activity of fructosyltransferase under high temperature conditions, which helps to accelerate the hydrolysis rate of sucrose in the first process, shorten the enzyme reaction time, and improve production efficiency.

[0041] In this invention, the pH adjustment is preferably 5.5 to 6.0, such as 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, and preferably a range of values ​​with any of the above values ​​as the upper or lower limit.

[0042] In this invention, fructosyltransferase is added to the reaction stock solution, followed by a constant-temperature water bath reaction. When the sucrose mass fraction in the system reaches 35-40%, sucrose solution is added to bring the sucrose mass fraction to 50-55%, and the reaction continues for 10-12 hours to obtain the first-stage saccharification solution. Since hydrolysis preferentially occurs at higher temperatures and higher sucrose concentrations, the addition of sucrose solution in the first stage increases the substrate concentration, further promoting the hydrolysis reaction. This provides a reserve of small molecule sugars for the synthesis of more low-polymerization-degree fructotrioses in the second stage, further increasing the fructotriose content and improving the quality of oligofructoses.

[0043] In this invention, the amount of fructosyltransferase added is preferably 6-8 U / g, such as 6 U / g, 7 U / g, or 8 U / g, and preferably within the range of any of the above values ​​as the upper or lower limit.

[0044] In this invention, the constant temperature water bath reaction temperature is preferably 60-65℃, more preferably 63℃; the reaction time is preferably 5-7h, more preferably 6h.

[0045] This invention filters the saccharification liquid from the first process using a semi-permeable membrane with a molecular weight cutoff of 350-500 Da to obtain a retentate and a filtrate. Before the polymerization reaction in the second process, this invention adds a semi-permeable membrane capable of retaining fructotriose. Since fructotriose has a molecular weight of 504.44 and sucrose has a molecular weight of 342.3, a 350-500 Da semi-permeable membrane is selected for filtration. This ensures that molecules such as sucrose and fructose can pass through while preventing the partially polymerized fructotriose from entering the second process. This reduces the formation of high molecular weight fructotetraose and fructopentose in the second process, significantly increasing the fructotriose content.

[0046] This invention involves subjecting the filtrate to a constant-temperature water bath reaction to obtain a second-stage saccharification solution, which is then mixed with a retentate to obtain a crude fructooligosaccharide solution.

[0047] In this invention, the water bath reaction temperature is preferably 40-45°C, more preferably 43°C; the reaction time is preferably 4-6 hours, more preferably 5 hours.

[0048] This invention is the first to divide the production of fructosaccharides from sucrose into two processes. In the first process, the hydrolytic activity of fructosaccharides is controlled to be greater than the polymerization activity by increasing the temperature, which is conducive to rapid hydrolysis and accumulation of small molecule sugars. In the second process, the polymerization activity of fructosaccharides is controlled to be greater than the hydrolytic activity by decreasing the temperature, which is conducive to rapid polymerization. By shortening the polymerization time of the second process, the degree of polymerization of a large number of fructosaccharides is controlled at a low level. Furthermore, lowering the temperature can inhibit the hydrolysis of the synthesized fructosaccharide products by fructosaccharides, thereby increasing the yield.

[0049] Furthermore, this invention produces fructooligosaccharides during the saccharification process. Under high temperature conditions, the water activity of fructooligosaccharides decreases. At the same time, the two-step reaction process can significantly consume fructose molecules in the system. Fructose itself has significant hygroscopicity, and the amount of fructose residue in the system is low, which can reduce the hygroscopicity of fructooligosaccharides and extend the product shelf life.

[0050] In this invention, activated carbon is added to the crude fructooligosaccharide solution, and the solution is decolorized and filtered to obtain a first filtrate.

[0051] In this invention, the amount of activated carbon added is preferably 1.0 to 2.0% of the dry basis mass of the crude fructooligosaccharide liquid, more preferably 1.2 to 1.8%.

[0052] In this invention, the decolorization temperature is preferably 55-60°C, and the time is preferably 15-20 min.

[0053] In this invention, the first filtrate is desalted using a strong acid cation resin D001 and a weak base anion resin D301P to obtain a second filtrate.

[0054] In this invention, the preferred material feeding temperature is 35-40°C, the preferred material feeding speed is 1-3 BV / h, and the preferred discharge pH is 5.0-6.0.

[0055] The second filtrate was separated by chromatography, concentrated by evaporation, and dried to prepare fructooligosaccharide powder.

[0056] In this invention, chromatographic separation, evaporation concentration, and drying can be performed using methods in the prior art.

[0057] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0058] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0059] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0060] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This application specification and embodiments are merely exemplary.

[0061] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0062] Unless otherwise specified, "room temperature" and "normal temperature" in this invention refer to 25±2℃.

[0063] The raw materials used in the following embodiments of the present invention are sourced from: the present invention can use β-fructosyltransferase, which is conventional in the art;

[0064] In the embodiments of the present invention, the fructosyltransferase is β-fructosyltransferase prepared by Chinese patent CN104130950A.

[0065] All others were obtained from commercial sales.

[0066] The detection methods in this invention are as follows:

[0067] Fructosyltransferase activity assay:

[0068] The enzyme activity assay was performed in accordance with QB / T 5357-2018.

[0069] Methods for detecting water activity:

[0070] According to GB 5009.238-2016 "Determination of water activity in food" method for determining water activity.

[0071] Example 1

[0072] A method for preparing fructooligosaccharides includes the following steps:

[0073] (1) Prepare a 56% sucrose solution in a reaction vessel, and add 50mM Fe. 2+ Then adjust the pH of the sucrose solution to 5.8.

[0074] (2) After adding fructosyltransferase to the sucrose solution in step (1) at 7 U / g, the solution is heated in a constant temperature water bath at 63°C for 6 hours until the sucrose mass fraction is 38%. Sucrose solution is added until the sucrose mass fraction is 53%, and the reaction is continued for 11 hours to obtain the first process saccharification solution.

[0075] (3) The first process saccharification liquid in step (2) is filtered through a semi-permeable membrane with a molecular weight cutoff of 500 Da to obtain a retentate and a filtrate. The filtrate is reacted in a water bath at 43°C for 5 hours to obtain the second process saccharification liquid. The retentate is then mixed to obtain the crude oligofructose liquid.

[0076] (4) Add 1.5% of the crude fructooligosaccharide liquid from step (3) to activated carbon, heat to 58°C and keep warm for 18 minutes, then decolorize and filter.

[0077] (5) The crude liquor after decolorization in step (4) is desalted using strong acid cation resin D001 and weak base anion resin D301P. The feed temperature is 37°C, the feed rate is 2 BV / h, and the output pH is 5.5.

[0078] (6) The crude liquid obtained after decolorization and desalting in step (6) is separated by chromatography, concentrated by evaporation, and dried to prepare fructooligosaccharide powder.

[0079] Example 2

[0080] A method for preparing fructooligosaccharides includes the following steps:

[0081] (1) Prepare a 55% sucrose solution in a reaction vessel, and add 45mM Fe. 2+ Then adjust the pH of the sucrose solution to 5.5.

[0082] (2) After adding fructosyltransferase to the sucrose solution in step (1) at 6 U / g, heat it in a constant temperature water bath at 60°C for 5 hours until the sucrose mass fraction is 35%. Then add sucrose solution until the sucrose mass fraction is 50% and continue to react for 10 hours to obtain the first process saccharification solution.

[0083] (3) The first process saccharification liquid in step (2) is filtered through a semi-permeable membrane with a molecular weight cutoff of 400 Da to obtain a retentate and a filtrate. The filtrate is reacted at a water bath temperature of 40°C for 4 hours to obtain the second process saccharification liquid. The retentate is then mixed to obtain the crude oligofructose liquid.

[0084] (4) Add 1.0% of the crude fructooligosaccharide liquid from step (3) to activated carbon, heat to 55°C and keep warm for 15 minutes, then decolorize and filter.

[0085] (5) The crude liquor after decolorization in step (4) is desalted using strong acid cation resin D001 and weak base anion resin D301P. The feed temperature is 35℃, the feed rate is 1BV / h, and the output pH is 5.0.

[0086] (6) The crude liquid obtained after decolorization and desalting in step (5) is separated by chromatography, concentrated by evaporation, and dried to prepare fructooligosaccharide powder.

[0087] Example 3

[0088] A method for preparing fructooligosaccharides includes the following steps:

[0089] (1) Prepare a 60% sucrose solution in a reaction vessel, and add 55mM Fe. 2+ Then adjust the pH of the sucrose solution to 6.0.

[0090] (2) After adding fructosyltransferase to the sucrose solution in step (1) at 8 U / g, heat it in a constant temperature water bath at 65°C for 7 hours until the sucrose mass fraction is 40%. Then, add sucrose solution until the sucrose mass fraction is 55%, and continue to react for 12 hours to obtain the first process saccharification solution.

[0091] (3) The first process saccharification liquid in step (2) is filtered through a semi-permeable membrane with a molecular weight cutoff of 450 Da to obtain a retentate and a filtrate. The filtrate is reacted at a water bath temperature of 45°C for 6 hours to obtain the second process saccharification liquid. The retentate is then mixed to obtain the crude oligofructose liquid.

[0092] (4) Add 2.0% of the crude fructooligosaccharide liquid from step (3) to activated carbon, heat to 60°C and keep warm for 20 minutes, then decolorize and filter.

[0093] (5) The crude liquor after decolorization in step (4) is desalted using strong acid cation resin D001 and weak base anion resin D301P. The feed temperature is 40℃, the feed rate is 3BV / h, and the output pH is 6.0.

[0094] (6) The crude liquid obtained after decolorization and desalting in step (5) is separated by chromatography, concentrated by evaporation, and dried to prepare fructooligosaccharide powder.

[0095] Comparative Example 1

[0096] The specific implementation method of this comparative example is basically the same as that of Example 1, except that: no sucrose solution is added in step (2).

[0097] Comparative Example 2

[0098] The specific implementation method of this comparative example is basically the same as that of Example 1, except that Fe is not added in step (1). 2+ .

[0099] Comparative Example 3

[0100] The specific implementation method of this comparative example is basically the same as that of Example 1, except that the water bath temperature in step (3) is the same as that in step (2).

[0101] Comparative Example 4

[0102] The specific implementation method of this comparative example is basically the same as that of Example 1, except that step (3) does not use a semi-permeable membrane with a molecular weight cutoff of 350-500 Da for filtration.

[0103] Experimental Example 1

[0104] The specific steps for enzyme activity assay are as follows: a high concentration of sucrose substrate is added to an acetate-sodium acetate buffer (pH 5.0) to prepare a 55% sucrose concentration solution. Fructosyltransferase is added, and the hydrolytic enzyme activity is measured by the amount of free glucose released (one molecule of glucose released must be one molecule of sucrose hydrolyzed). The polymerase activity is measured by the amount of synthesized oligofructose. The enzyme activity assay results are expressed as relative enzyme activity. The test results are shown in Table 1.

[0105] Table 1 Enzyme activity in hydrolysis and polymerization reactions.

[0106] As shown in Table 1, the hydrolase activity and polymerase activity in Comparative Example 2 were both lower than those in Example 1, indicating that Fe 2+It can significantly protect the reactivity of fructosyltransferase under high temperature conditions; in Comparative Example 3, the hydrolytic activity of fructosyltransferase in both stages was higher than that of polymerase, indicating that high temperature conditions can significantly enhance the hydrolytic effect of fructosyltransferase, resulting in increased fructose residue and reduced conversion rate of oligofructose; low temperature conditions can effectively enhance polymerase activity and increase yield.

[0107] Experimental Example 2

[0108] The conversion rate of fructooligosaccharides, the content of sucrose trisaccharides in fructooligosaccharides, the percentage of residual fructose, and the water activity of Implementation 1 and Comparative Examples 1–4 were tested. The test results are shown in Table 2.

[0109] Table 2. Test Results of Various Parameters

[0110] Table 2 shows that the conversion rate of fructooligosaccharides in Comparative Example 1 was much lower than that in Example 1. This indicates that adding sucrose during the saccharification process, when more fructose is hydrolyzed in the first stage, allows sucrose to rapidly combine with fructose to produce fructotriose, which has a significant effect on increasing the conversion rate of fructooligosaccharides and the content of fructotriose. In Comparative Example 2, both the conversion rate of fructooligosaccharides and the content of fructotriose in fructooligosaccharides were lower than in Example 1, while the percentage of residual fructose and the water activity were higher than in Example 1. This indicates that the enzyme stabilizer Fe 2+ The addition of [the substance] can effectively protect the activity of fructosyltransferase, effectively consume the hydrolyzed fructose, reduce the water activity of the product, ensure the smooth and efficient progress of the overall saccharification reaction, and improve the various indicators of fructooligosaccharides. In Comparative Example 3, the conversion rate of fructooligosaccharides and the content of fructooligosaccharides in fructooligosaccharides were also lower than those in Example 1. This indicates that continuous high temperature will keep the process in the first stage, and continuous hydrolysis will result in a large amount of residual fructose, leading to a low conversion rate of fructooligosaccharides. In Comparative Example 4, the content of fructooligosaccharides in fructooligosaccharides was lower than that in Example 1. This indicates that adding a semi-permeable membrane for retention before the second stage can effectively increase the content of fructooligosaccharides and reduce the generation of high-polymerization-degree fructooligosaccharides in the subsequent polymerization process.

[0111] In summary, this invention produces fructooligosaccharides by introducing metal ions that protect the thermal stability of enzymes, controlling the reaction temperature and time to allow hydrolysis and polymerization to proceed in stages, and using a semi-permeable membrane for filtration. This not only results in a rapid reaction and a product with low water activity and good hygroscopic resistance, but also improves the yield of fructooligosaccharides and the content of fructooligosaccharides, providing new technical support for high-quality fructooligosaccharides.

[0112] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for the preparation of oligofructose, characterized in that, The method comprises the following steps: (1) Fe was added into sucrose solution 2+ Then the pH was adjusted to obtain the reaction stock solution; (2) After adding fructosyltransferase into the reaction solution, constant temperature water bath reaction is carried out; when the mass fraction of sucrose in the system is 35-40%, sucrose solution is added to make the mass fraction of sucrose 50-55%, and then the reaction is continued for 10-12 hours to obtain a first process saccharification liquid; (3) The first process saccharification liquid is filtered by using a semi-permeable membrane with a molecular weight cut-off of 350-500 Da to obtain a cut-off liquid and a filtrate; (4) The filtrate is subjected to constant temperature water bath reaction to obtain a second process saccharification liquid, and then the second process saccharification liquid is mixed with the cut-off liquid to obtain a crude fructooligosaccharide liquid; (5) Activated carbon is added into the crude fructooligosaccharide liquid to carry out decolorization filtration to obtain a first filtrate; (6) The first filtrate is subjected to desalination by using strong acid cation resin D001 and weak base anion resin D301P to obtain a second filtrate; (7) The second filtrate is subjected to chromatographic separation, evaporation concentration and drying to prepare a fructooligosaccharide powder. In the step (2), the constant temperature water bath reaction temperature is 60-65℃, and the reaction time is 5-7 hours. In the step (4), the water bath reaction temperature is 40-45℃, and the reaction time is 4-6 hours.

2. The production method according to claim 1, characterized by, In the step (1), the mass fraction of sucrose solution is 55-60%.

3. The preparation method according to claim 1, characterized in that, In step (1), Fe 2+ The amount added is 45-55 mM.

4. The method of claim 1, wherein, In the step (1), the pH is adjusted to 5.5-6.

0.

5. The preparation method according to claim 1, characterized in that, In the step (2), the addition amount of fructosyltransferase is 6-8 U / g.

6. The method of claim 1, wherein, In the step (5), the addition amount of activated carbon is 1.0-2.0% of the dry basis mass of the crude fructooligosaccharide liquid.

7. The preparation method according to claim 1, characterized in that, In the step (5), the decolorization temperature is 55-60℃, and the time is 15-20 minutes.

8. The method of claim 1, wherein, In the step (6), the temperature is 35-40℃, the flow rate is 1-3 BV / h, and the pH of the outlet is 5.0-6.0.

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