Production method of xylooligosaccharide

Abstract

The invention discloses a xylooligosaccharide production method which comprises the following steps: diluting a xylose mother solution, carrying out first ion exchange on a diluent, evaporating and concentrating an ion exchange filtrate, carrying out chromatographic separation on a concentrated solution, decolorizing and filtering an extracting solution after chromatographic separation, carrying out second ion exchange on a decolorized filtrate, evaporating and concentrating, and carrying out spray drying on a concentrated feed liquid to prepare powdery xylooligosaccharide. According to the method, the xylose mother liquor can be used for preparing the high-purity xylooligosaccharide, the source of the xylooligosaccharide is fully developed, waste is turned into wealth, and the environment is not influenced while the cost is saved.

Description

Technical Field

[0001] The invention relates to the technical field of xylooligosaccharide processing, in particular to a method for producing xylooligosaccharide. Background Art

[0002] The main components of oligoxylose are a mixture of polysaccharides such as xylobiose, xylotriose and xylotetraose, with a degree of polymerization of 2-7 and a sweetness of about 50% of sucrose. It has a pure sweetness similar to sucrose. Oligoxylose has good physical and chemical properties, such as selective proliferation of intestinal probiotics; lowering cholesterol, improving the bioavailability of calcium; anti-oxidation, antibacterial, enhancing immunity, improving the cardiovascular system; and meeting the sweetness needs of diabetics and obese people. It is widely used in the food and pharmaceutical industries.

[0003] Xylooligosaccharides have unique advantages among functional sugars. They can selectively promote the proliferation of intestinal bifidobacteria. Because of their good acid and heat stability, they can be added to food, beverages, dairy products, and health products. At present, most domestic production methods of xylooligosaccharides are to use corn cobs or hemicellulose for acid hydrolysis or enzymatic hydrolysis to extract xylooligosaccharides. This method has a high production cost and a low extraction rate of xylooligosaccharides. It requires a large amount of raw materials and the production method is relatively rough.

[0004] Industrially, after the corn cob is extracted, hydrolyzed, refined, and xylose is extracted, a portion of the xylose mother liquor will remain. The material contains many ingredients, mainly including oligoxylose, glucose, xylose, arabinose, mannose, and some unknown sugar substances. At present, the conventional practice is to chromatographically separate the mother liquor to extract xylose or concentrate it as a caramel pigment or carbon source with low added value for sale, which has low added value. The prior art also discloses a scheme for extracting oligoxylose from xylose mother liquor, but it directly performs chromatographic separation on the xylose mother liquor, and the separation effect is not good, resulting in low purity of the finally obtained oligoxylose.

[0005] Based on this, how to effectively extract xylooligosaccharides and improve the purity of xylooligosaccharides has become an urgent problem to be solved. Summary of the invention

[0006] The purpose of the present invention is to provide a method for producing xylooligosaccharides to obtain high-purity xylooligosaccharides, improve the added value of chromatographic residues, and have no other harmful by-products in the production process.

[0007] To achieve the above object, the present invention provides a method for producing xylo-oligosaccharides, comprising the following steps:

[0008] A method for producing xylo-oligosaccharides comprises the following steps:

[0009] Step 1, diluting the xylose mother liquor to obtain a dilution solution;

[0010] Step 2, performing a first ion exchange on the diluted solution in step 1 to remove impurity ions in the diluted solution, and obtaining an ion exchange filtrate with a conductivity of less than 50 μs / cm;

[0011] Step 3, vacuum evaporating and concentrating the ion exchange filtrate in step 2 to obtain a concentrated solution;

[0012] Step 4, subjecting the concentrated solution in step 3 to chromatographic separation according to a certain water-to-solid ratio to obtain an extract and a raffinate;

[0013] Step 5, decolorizing and filtering the extract in step 4 to obtain a decolorized filtrate;

[0014] Step 6, subjecting the decolorized filtrate in step 5 to a second ion exchange to further remove impurity ions, thereby obtaining an ion exchange filtrate;

[0015] Step 7, concentrating the ion exchange filtrate in step 6 by vacuum evaporation to obtain a concentrated solution;

[0016] Step 8, spray-drying the concentrated solution in step 7 to obtain a powdered xylo-oligosaccharide product, wherein the xylobiose content in the finished product is greater than 80%, and the xylo-oligosaccharide content is greater than 95%. Due to the subsequent spray drying of the chromatographic extract, the xylo-oligosaccharide content may decrease under high temperature conditions, so the content of the extract is higher than that of the finished product.

[0017] Furthermore, the dilution refractive index of the xylose mother liquor in step 1 is 45%-50%. In the present invention, since the first ion exchange is performed after the xylose mother liquor is diluted, a too low concentration will result in a high frequency of resin regeneration during the ion exchange process and the subsequent ion exchange will require reconcentration, and a too high concentration will result in a high ion exchange column pressure and a slow material flow rate. Therefore, the dilution concentration of the xylose mother liquor is controlled to be 45%-50% in the present invention, which can meet these two requirements.

[0018] Furthermore, the refractive index of the concentrated solution in step 3 is 50%-55%. If the concentration of the concentrated solution is too low, the chromatographic separation efficiency will be low, while if the concentration is too high, the pressure of the chromatographic system will be high, making it difficult to separate. In the present invention, the refractive index of the concentrated solution is 50%-55%, which can keep the separation efficiency and separation accuracy within a reasonable range.

[0019] Furthermore, the second ion exchange in step 6 obtains an ion exchange filtrate with a transmittance greater than 90%, a pH greater than 4.0, and a conductivity less than 20 μs / cm, which can make the final product have a better taste.

[0020] Furthermore, due to the characteristics of the chromatographic separation resin and the process parameter requirements, the material-water ratio of the chromatographic separation in step 4 is not greater than 1:3, so that the content of xylooligosaccharides in the extract is higher and the impurities are less at a suitable productivity.

[0021] Furthermore, in step 5, the extract is decolorized for 30-60 minutes and then filtered through a plate-and-frame filter, and the filtration pressure is 0.2-0.4 Mpa. During filtration in the present invention, if the filtration pressure is lower than this range, the pre-coat layer is easy to fall off, resulting in a filter penetration phenomenon; if the filtration pressure is higher than this range, the flow rate will be small.

[0022] Furthermore, in step 5, the extract in step 4 is heated to 50-60°C, and 0.5-10.000 activated carbon is added according to the volume ratio, and then stirred and filtered in sequence to obtain a decolorized filtrate. When the extract is at a temperature of 45-65°C, the higher the temperature, the better the decolorization effect, but after exceeding 60°C, the decolorization effect does not change much, and the higher the temperature, the higher the energy consumption, so 50-60°C is selected. When the activated carbon addition amount is 0.5-1%, the effect is good and the benefit is optimal, so 0.5-1% is selected as the activated carbon addition range.

[0023] Furthermore, the ion exchange steps in step 2 and step 6 both include cation exchange and anion exchange. How to achieve cation and anion exchange through ion exchange resin and how to use ion exchange resin are common knowledge in the art and will not be described in detail.

[0024] Furthermore, the refractive index of the concentrated solution in step 7 is controlled at 50-55%, and the evaporation temperature is controlled at 60-70° C., so as to ensure that the functionality, stability and high quality of the xylo-oligosaccharides are maintained during the evaporation and concentration process.

[0025] The method for producing xylooligosaccharides of the present invention comprises the following steps: diluting a xylose mother liquor, subjecting the diluent to a first ion exchange, evaporating and concentrating the ion exchange filtrate, subjecting the concentrated liquid to chromatographic separation, decolorizing and filtering the extract after chromatographic separation, subjecting the decolorized filtrate to a second ion exchange and evaporation concentration, and spray drying the concentrated liquid to prepare powdered xylooligosaccharides. Since the xylose mother liquor has a relatively simple composition and fewer impurities, in the art, when using the xylose mother liquor for chromatographic separation to further extract substances such as xylooligosaccharides, arabinose or xylose, the general method is to directly chromatographically separate after dilution. However, in the present invention, the diluted xylose mother liquor is first subjected to ion exchange, and the conductivity of the ion exchange filtrate is controlled to be less than 50 μs / cm, so that impurity ions can be removed and the purity of the ion exchange liquid can be improved. This can not only ensure that the ion exchange liquid does not damage the chromatographic resin, but more importantly, the concentration of the ion exchange filtrate obtained after the first ion exchange is reduced. After the ion exchange filtrate is evaporated and concentrated to obtain a concentrated liquid of a certain concentration, the chromatographic separation can be performed, so that the efficiency of the chromatographic separation and the content of xylooligosaccharides in the extract can be improved, thereby improving the purity of the final xylooligosaccharide product.

[0026] Therefore, the present invention can obtain high-purity oligoxylose, reduce the production cost of oligoxylose, and thus obtain sugar-free food. In addition, the raffinate after chromatographic separation can be used as a raw material to obtain xylose and arabinose after chromatographic separation and extraction again, or sold as a prebiotic, which not only reduces environmental pollution but also increases economic benefits. DETAILED DESCRIPTION

[0027] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail in the following embodiments.

[0028] Embodiment 1:

[0029] Step 1, diluting the xylose mother liquor to a refractive index of 45%;

[0030] Step 2, subjecting the mother liquor in step 1 to cation exchange and anion exchange to obtain an ion exchange filtrate with a conductivity of less than 50 μs / cm;

[0031] Step 3, vacuum evaporating and concentrating the ion exchange filtrate in step 2 to obtain a concentrated solution, wherein the refractive index of the concentrated solution is controlled at 50%;

[0032] Step 4, subjecting the concentrated solution in step 3 to chromatographic separation at a material-water ratio of 1:2.61 to obtain an extract and a raffinate; wherein the content of xylo-oligosaccharides in the extract is 96.1%;

[0033] Step 5, decolorizing and filtering the extract in step 4, wherein the amount of activated carbon added is 0.5%, the decolorization temperature is 50°C, the decolorization time is 30 minutes, and filtering;

[0034] Step 6, performing cation exchange and anion exchange on the decolorizing solution in step 5 to obtain an ion exchange filtrate with a transmittance of 91.1%, a pH of 4.3, and a conductivity of 11.78 μs / cm;

[0035] Step 7, vacuum evaporating and concentrating the ion exchange filtrate in step 6 to obtain a concentrated solution, wherein the refractive index of the concentrated solution is controlled at 50% and the evaporation temperature is controlled at 60° C.;

[0036] Step 8, spray drying the concentrated solution in step 7 to obtain a powdered xylo-oligosaccharide finished product, wherein the xylo-oligosaccharide X0S 2-7 The content is 95.8%, and XOS 2-4 Content 91.4%.

[0037] Embodiment 2:

[0038] Step 1, dilute the xylose mother liquor and concentrate it to a refractive index of 47%.

[0039] Step 2, subjecting the mother liquor in step 1 to cation exchange and anion exchange to obtain an ion exchange filtrate with a conductivity of less than 50 μs / cm;

[0040] Step 3, vacuum evaporating and concentrating the ion exchange filtrate in step 2 to obtain a concentrated solution, wherein the refractive index of the concentrated solution is controlled at 52%;

[0041] Step 4, subjecting the concentrated solution in step 3 to chromatographic separation at a material-water ratio of 1:2.73 to obtain an extract and a raffinate; wherein the content of xylo-oligosaccharides in the extract is 96.3%.

[0042] Step 5, decolorizing and filtering the extract in step 4, wherein the amount of activated carbon added is 0.7%, the decolorization temperature is 55°C, the decolorization time is 45 minutes, and filtering;

[0043] Step 6, performing cation exchange and anion exchange on the decolorized solution in step 5 to obtain an ion exchange filtrate with a transmittance of 92.8%, a pH of 4.5, and a conductivity of 12.04 μs / cm;

[0044] Step 7, vacuum evaporating and concentrating the ion exchange filtrate in step 6 to obtain a concentrated solution, wherein the refractive index of the concentrated solution is controlled at 52% and the evaporation temperature is controlled at 65° C.;

[0045] Step 8, spray drying the concentrated solution in step 7 to obtain a powdered xylo-oligosaccharide finished product. 2-7 The content is 95.6%, and XOS 2-4 Content 91.3%.

[0046] Embodiment 3:

[0047] Step 1, dilute the xylose mother liquor chromatography residue to a concentration of 50%,

[0048] Step 2, subjecting the mother liquor in step 1 to cation exchange and anion exchange to obtain an ion exchange filtrate with a conductivity of less than 50 μs / cm;

[0049] Step 3, vacuum evaporating and concentrating the ion exchange filtrate in step 2 to obtain a concentrated solution, wherein the refractive index of the concentrated solution is controlled at 55%;

[0050] Step 4, subjecting the concentrated solution in step 3 to chromatographic separation at a material-water ratio of 1:2.87 to obtain an extract and a raffinate; wherein the content of xylo-oligosaccharides in the extract is 96.2%.

[0051] Step 5, decolorizing and filtering the extract in step 4, wherein the amount of activated carbon added is 1%, the decolorization temperature is 60°C, the decolorization time is 60 minutes, and filtering;

[0052] Step 6, subjecting the decolorizing solution in step 5 to cation exchange and anion exchange to obtain an ion exchange filtrate with a transmittance of 94.7%, a pH of 4.2, and a conductivity of 10.97 μs / cm;

[0053] Step 7, vacuum evaporating and concentrating the ion exchange filtrate in step 6 to obtain a concentrated solution, wherein the refractive index of the concentrated solution is controlled at 55% and the evaporation temperature is controlled at 60° C.;

[0054] Step 8, spray drying the concentrated solution in step 7 to obtain a powdered xylo-oligosaccharide finished product, wherein the xylo-oligosaccharide X0S 2-7 The content is 95.5%, and XOS 2-4 Content 91.1%.

[0055] In summary, when the oligoxylose production method provided by the present invention is applied, the xylose mother liquor is diluted, the diluted liquid is subjected to the first ion exchange, the ion exchange filtrate is evaporated and concentrated, the concentrated liquid is chromatographed, the extract after chromatographic separation is decolorized and filtered, the decolorized filtrate is subjected to the second ion exchange and evaporation and concentration, and the concentrated liquid is spray-dried to prepare powdered oligoxylose. In the present invention, the diluted xylose mother liquor is first subjected to ion exchange, and the conductivity of the ion exchange filtrate is controlled to be less than 50μs / cm, which can remove impurity ions and improve the purity of the ion exchange liquid, not only ensuring that the ion exchange liquid does not damage the chromatographic resin, but more importantly, the concentration of the ion exchange filtrate obtained after the first ion exchange is reduced, and the ion exchange filtrate is evaporated and concentrated to obtain a certain concentration of concentrated liquid and then subjected to chromatographic separation, which can improve the efficiency of chromatographic separation and the content of oligoxylose in the extract, and thus can improve the purity of the final product of oligoxylose.

[0056] The present invention can effectively utilize xylose mother liquor to obtain high-purity xylooligosaccharide liquid, and then obtain the finished xylooligosaccharide powder through a subsequent spray drying process. Among them, the present invention can improve the purity of xylooligosaccharide by first ion exchange and evaporation concentration and then by chromatographic separation process, and the pigment in the extract can be effectively removed by adding activated carbon to obtain purified xylooligosaccharide liquid. In addition, the raffinate separated by chromatography can be used as a prebiotic concentrate or to extract xylose and arabinose, which not only reduces the pollution to the environment, but also increases the economic benefits.

[0057] In addition, the following comparative tests were conducted in this application:

[0058] Experiment 1: The extract of step 4 was set up with four experimental groups with different amounts of activated carbon added at the same concentration to obtain the decolorization effect of oligoxylose in different experimental groups, and the experimental results are shown in Table 1:

[0059] Table 1

[0060]

[0061] From the data in Table 1, we can conclude that:

[0062] (1) Under the same activated carbon addition amount and concentration, at a temperature of 45-65°C, the higher the temperature, the better the decolorization effect. After exceeding 60°C, the decolorization effect does not change much, but the energy consumption increases with the increase in temperature, so the present invention finally selects 50-60°C.

[0063] (2) Under the same concentration and temperature, the effect of adding 0.3% activated carbon is poor, and the cost increases when the activated carbon addition exceeds 1%. When the activated carbon addition is 0.5-1%, the effect is better and the benefit is optimal, so 0.5-1% is selected as the activated carbon addition range.

[0064] Experiment 2: Three mother liquors with the same xylooligosaccharide concentration were subjected to chromatographic separation, and various components before and after chromatography were compared. The experimental results are shown in Table 2:

[0065] Table 2

[0066]

[0067] From the data in Table 2, we can conclude that:

[0068] In the present invention, the oligoxylose content is increased after treatment by the combination of ion interaction, evaporation concentration and chromatographic separation, that is, the oligoxylose content of the product can be effectively removed and increased.

[0069] Experiment 3: Comparison of results after changing some process routes

[0070] (1) In the process route of the present invention, only the chromatographic extract is decolorized.

[0071] (2) Increase decolorization before chromatography and keep the chromatographic extract decolorized.

[0072] (3) Add decolorization before chromatography and remove decolorization of chromatographic extract.

[0073] Table 3

[0074] Project Name Transmittance of extract (%) Xylooligosaccharide content in extract (%) (1) 93.8 95.8 (2) 94.1 96.0 (3) 88.7 95.6

[0075] It can be concluded from the data in Table 3 that increasing the decolorization before chromatography does not increase the light transmittance and xylo-oligosaccharide content of the extract, but the cost will increase. Reducing the decolorization of the extract will significantly reduce the light transmittance of the extract. Therefore, the current process of the present invention is optimal, and there is no need to increase decolorization before chromatography.

[0076] In summary, the process for producing xylooligosaccharides provided by the present invention has the following advantages:

[0077] 1. Through the implementation of the present invention, the content of xylooligosaccharides in xylose mother liquor can be effectively increased while reducing the number of process steps.

[0078] 2. The present invention can improve the added value of xylose mother liquor, and the residual liquid after chromatographic separation can be sold as prebiotics to increase market share.

[0079] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0080] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0081] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for producing xylo-oligosaccharides, characterized in that: The following steps are involved: Step 1, diluting the xylose mother liquor to obtain a dilution solution; Step 2, performing a first ion exchange on the diluted solution in step 1 to obtain an ion exchange filtrate with a conductivity of less than 50 μs / cm; Step 3, vacuum evaporating and concentrating the ion exchange filtrate in step 2 to obtain a concentrated solution; Step 4, subjecting the concentrated solution in step 3 to chromatographic separation according to a certain water-to-solid ratio to obtain an extract and a raffinate; Step 5, decolorizing and filtering the extract in step 4 to obtain a decolorized filtrate; Step 6, subjecting the decolorized filtrate in step 5 to a second ion exchange to obtain an ion exchange filtrate; Step 7, concentrating the ion exchange filtrate in step 6 by vacuum evaporation to obtain a concentrated solution; Step 8, spray-drying the concentrated solution in step 7 to obtain a powdered xylo-oligosaccharide product.

2. The method for producing xylo-oligosaccharides according to claim 1, wherein The refractive index of the xylose mother liquor in step 1 is 45%-50%.

3. The method for producing xylo-oligosaccharides according to claim 1, characterized in that: The refractive index of the concentrated solution in step 3 is 50%-55%.

4. The method for producing xylo-oligosaccharides according to claim 1, wherein The second ion exchange in step 6 obtains an ion exchange filtrate with a transmittance of >90%, a pH of >4.0, and a conductivity of <20 μs / cm.

5. The method for producing xylo-oligosaccharides according to claim 1, characterized in that: The material-water ratio of the chromatographic separation in step 4 is not greater than 1:

3.

6. The method for producing xylo-oligosaccharides according to claim 1, characterized in that: In step 5, the extract is decolorized for 30-60 minutes and then filtered through a plate and frame filter with a filtration pressure of 0.2-0.4 MPa.

7. The method for producing xylo-oligosaccharides according to claim 1, characterized in that: In the step 5, the extract in the step 4 is heated to 50-60° C., and 0.5 to 10.000 activated carbon is added according to the volume ratio, and then stirred and filtered in sequence to obtain a decolorized filtrate.

8. The method for producing xylo-oligosaccharides according to claim 1, characterized in that: The ion exchange steps in step 2 and step 6 both include cation exchange and anion exchange.

9. The method for producing xylo-oligosaccharides according to claim 1, characterized in that: The refractive index of the concentrated solution in step 7 is controlled at 50-55%, and the evaporation temperature is controlled at 60-70°C.

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