A preparation method and application of mannan oligosaccharide

Abstract

The present invention discloses a preparation method and application of mannan oligosaccharide. The preparation method of mannan oligosaccharide includes: reacting guar gum with an oxidant in the presence of water; wherein, the temperature of the reaction is 60-90 °C. The mannan oligosaccharide generated by the present invention can be used as a fertilizer synergist for crops, especially can promote the growth of crops (such as wheat). Specifically, it can promote crops (such as wheat) to increase root length (rooting) and stem length, and increase root fresh weight and stem fresh weight; activate the plant immune response and improve the stress resistance of plants.

Description

Technical Field

[0001] The present invention relates to the technical field of biochemistry, and specifically refers to a preparation method and application of mannan oligosaccharide. Background Art

[0002] Guar gum is a highly purified natural polysaccharide extracted from guar beans widely planted in the Indian subcontinent. The molecular weight of guar gum is about 220,000 Da. In terms of molecular structure, guar gum is a non-ionic polysaccharide. Its molecular main chain is composed of polymannose, and the D-pyranose mannose units are connected by β(1-4) glycosidic bonds. The D-pyranose galactose is connected to the polymannose main chain by α(1-6) bonds. The molar ratio of mannose to galactose units in guar gum is 2:1, that is, every other mannose unit is connected with a galactose branch.

[0003] Medically, mannan oligosaccharide can be used as an excellent immune activator and a powerful free radical scavenger, activating macrophages, neutrophils, etc. to remove cell debris caused by radiation; it can assist damaged tissues such as lymphoid tissue cells to accelerate the recovery of cytokines; it can reduce low-density fat in the blood, increase high-density fat, and reduce the occurrence of hyperlipidemia. Summary of the Invention

[0004] To solve at least one of the problems in the prior art, the present invention provides a preparation method and application of mannan oligosaccharide.

[0005] A preparation method of mannan oligosaccharide includes: reacting guar gum with an oxidant in the presence of water; wherein the temperature of the reaction is 60-90°C.

[0006] The present invention discovers that when reacting guar gum with an oxidant in the presence of water within the above temperature range, the generated mannan oligosaccharide has a low degree of polymerization, good solubility, is easy to absorb, and can be used as a fertilizer synergist for crops, especially can promote the growth of crops (such as wheat). Specifically, it can promote crops (such as wheat) to increase root length (rooting) and stem length, and increase root fresh weight and stem fresh weight.

[0007] Further research finds that if the temperature of the above reaction is too low, such as below 50°C, the degradation rate is slow, the degradation is insufficient, the product has a high degree of polymerization, a large molecular weight, a large viscosity, and a dark color, which is not conducive to the absorption and utilization of plants; if the temperature of the above reaction is too high, such as above 90°C, the reaction is too violent and there is a certain danger. And the proportion of monosaccharides in the degradation product increases, and its functionality decreases.

[0008] According to some preferred embodiments of the present invention, the temperature of the reaction is 60-85°C, optionally 70-80°C, specifically for example 60°C, 65°C, 70°C, 75°C, 80°C, 85°C.

[0009] According to some preferred embodiments of the present invention, the oxidant is selected from MnO 2 , H 2 O 2 , concentrated sulfuric acid, nitric acid, KMnO 4 , K 2 Cr 2 O 7 , KClO 3 , or one or more of them, more preferably H 2 O 2 and / or concentrated sulfuric acid. It has been found that selecting these oxidants can achieve the purpose of less residue, easy removal, and better stability when compounded with other substances (fertilizer raw materials).

[0010] According to some preferred embodiments of the present invention, the weight ratio of the guar gum to water is (1 - 3):(10 - 100), and it can be optionally 1:(20 - 50), such as 1:10, 1:20, 1:30, 1:30, 1:40, 1:50. It has been found that within this ratio range, the reaction time can be significantly reduced and the product yield can be ensured.

[0011] According to some preferred embodiments of the present invention, the weight ratio of the oxidant to water is 1:(5 - 20), such as 1:5, 1:7, 1:10, 1:15, 1:20. It has been found that within this ratio range, the reaction time can be significantly reduced and the guar gum can be properly degraded.

[0012] According to some preferred embodiments of the present invention, the reaction time is based on the full degradation of the guar gum. For example, the time can be 3 - 4 h.

[0013] According to some preferred embodiments of the present invention, the above method further includes a step of filtration after the reaction, such as ultrafiltration.

[0014] According to some preferred embodiments of the present invention, the above method further includes a step of concentration after filtration.

[0015] According to some preferred embodiments of the present invention, the above method further includes a drying step after filtration or concentration. The dried product is mannan oligosaccharide powder.

[0016] According to some specific embodiments of the present invention, the above method includes:

[0017] 1) Placing an appropriate amount of oxidant and water into a reaction kettle, and the weight ratio of the oxidant to water is 1:(5 - 20);

[0018] 2) Adding guar gum into the reaction kettle in step 1), the ratio of the guar gum to water is 1:(20 - 50), and adjusting the internal temperature of the reaction kettle to between 60 - 90 °C, and reacting fully for 3 - 4 h;

[0019] 3) Concentrate using an ultrafiltration device;

[0020] 4) Dry the liquid obtained in step 3) using a spray drying device to obtain mannan oligosaccharide powder.

[0021] The present invention also includes the mannan oligosaccharide or mannan oligosaccharide powder prepared by the above method.

[0022] According to an embodiment of the present invention, the degree of polymerization of the mannan oligosaccharide or mannan oligosaccharide powder is 1 - 50; and / or, the molecular weight is 180 - 9000 Da.

[0023] According to an embodiment of the present invention, the degree of polymerization of the mannan oligosaccharide or mannan oligosaccharide powder is the molecular weight divided by the molecular weight of mannose monosaccharide.

[0024] According to an embodiment of the present invention, the molecular weight of the mannan oligosaccharide or mannan oligosaccharide powder is measured by the dilute solution viscosity method.

[0025] In agricultural production, in the face of various stress conditions, the mannan oligosaccharide of the present invention can be used as a stress protection agent to activate the plant immune response and improve the stress resistance of plants.

[0026] The present invention also includes the application of the above mannan oligosaccharide or mannan oligosaccharide powder in crop production, such as being used as a fertilizer synergist for crops.

[0027] Specifically, the application includes promoting crops (such as wheat) to increase root length (rooting) and stem length, and increasing root fresh weight and stem fresh weight.

[0028] Specifically, the crops include wheat.

[0029] Specifically, when the mannan oligosaccharide or mannan oligosaccharide powder prepared by the present invention is used for crop root irrigation or micro - irrigation, drip irrigation, flushing or foliar spraying, the concentration can be 0.5 - 50 ppm, such as 10 ppm.

[0030] The mannan oligosaccharide or mannan oligosaccharide powder prepared by the present invention can be used for crop root irrigation or micro - irrigation, drip irrigation, flushing or foliar spraying, and for crop irrigation or foliar spraying according to the growth period.

[0031] The mannan oligosaccharide or mannan oligosaccharide powder prepared by the present invention does not contain any toxic or harmful components, has high cost - effectiveness, and is suitable for the production of green and safe crops.

[0032] The advantages of the present invention compared with the prior art are as follows:

[0033] The mannan oligosaccharide of the present invention is used as a fertilizer synergist for crops, does not add any toxic or harmful components, is suitable for the production of green and safe crops. It has low cost and simple process, and realizes large - scale agricultural production application. Description of the Drawings

[0034] Figure 1 Experimental Example 2 Results of hydroponic wheat experiment (growth of hydroponic wheat). Detailed Description of the Invention

[0035] The present invention will be further described in detail below in conjunction with the embodiments. Example 1

[0036] A method for preparing a mannan oligosaccharide powder, comprising the following steps:

[0037] Step 1: Place an appropriate amount of H 2 O 2 and water into a reaction kettle, and the weight ratio of H 2 O 2 to water is 1:5;

[0038] Step 2: Add guar gum to the reaction kettle in Step 1, and stir continuously during the addition process. The weight ratio of guar gum to water is 1:50, and adjust the internal temperature of the reaction kettle to 80 °C, continue to stir, and react fully for 3 h;

[0039] Step 3: Concentrate using an ultrafiltration device;

[0040] Step 4: Dry the liquid obtained in Step 3 using a spray drying device to finally obtain a mannan oligosaccharide powder. Example 2

[0041] A method for preparing a mannan oligosaccharide powder, comprising the following steps:

[0042] Step 1: Place an appropriate amount of concentrated sulfuric acid and water into a reaction kettle, and the weight ratio of concentrated sulfuric acid to water is 1:20;

[0043] Step 2: Add guar gum to the reaction kettle in Step 1, and stir continuously during the addition process. The weight ratio of guar gum to water is 1:50, and adjust the internal temperature of the reaction kettle to 70 °C, continue to stir, and react fully for 4 h;

[0044] Step 3: Concentrate using an ultrafiltration device;

[0045] Step 4: Dry the liquid obtained in Step 3 using a spray drying device to finally obtain a mannan oligosaccharide powder. Example 3

[0046] A method for preparing a mannan oligosaccharide powder, comprising the following steps:

[0047] Step 1: Place an appropriate amount of H 2 O 2 and water into a reaction kettle, and H 2O 2 The weight ratio to water is 1:10;

[0048] Step 2: Add guar gum into the reactor in Step 1, stir continuously during the addition process, the weight ratio of guar gum to water is 1:20, and adjust the internal temperature of the reactor to 70 °C, continue to stir, and react fully for 3 h;

[0049] Step 3: Centrifuge at 3000 r / min for 30 min, and take the supernatant;

[0050] Step 4: Dry the liquid obtained in Step 3 using an oven to obtain a solid;

[0051] Step 5: Pulverize the solid obtained in Step 4 using a pulverizer to finally obtain mannan oligosaccharide powder. Comparative Example 1

[0052] Step 1: Place an appropriate amount of H 2 O 2 and water into the reactor, the weight ratio of H 2 O 2 to water is 1:5;

[0053] Step 2: Add guar gum into the reactor in Step 1, stir continuously during the addition process, the weight ratio of guar gum to water is 1:50, and adjust the internal temperature of the reactor to 50 °C, continue to stir, and react fully for 3 h.

[0054] It was found that the reaction product was still in a viscous colloid state. Comparative Example 2

[0055] Step 1: Place an appropriate amount of H 2 O 2 and water into the reactor, the weight ratio of H 2 O 2 to water is 1:5;

[0056] Step 2: Add guar gum into the reactor in Step 1, stir continuously during the addition process, the weight ratio of guar gum to water is 1:50, and adjust the internal temperature of the reactor to 80 °C, continue to stir, and react fully for 2 h.

[0057] It was found that the reaction product was still in a viscous colloid state. Comparative Example 3

[0058] Step 1: Place an appropriate amount of H 2 O 2 and water into the reactor, the weight ratio of H 2 O 2 to water is 1:1;

[0059] Step 2: Add guar gum into the reactor in Step 1, stir continuously during the addition process, with the weight ratio of guar gum to water being 1:50, adjust the internal temperature of the reactor to 80 °C, continue stirring, and react fully for 3 h.

[0060] It was found that the reaction product was still in a viscous colloid state.

[0061] Experimental Example 1

[0062] The experimental results of the samples prepared in the above Examples 1-3 and Comparative Examples 1-3 are shown in Table 1 below.

[0063] Method for measuring solubility: Refer to "Determination of Water-insoluble Matter Content in Water-soluble Fertilizers (NY / T 1115-2006)".

[0064] Method for measuring intrinsic viscosity: Measured using an Ubbelohde capillary viscometer.

[0065] Table 1

[0066] Category Solubility of the obtained product Color of the obtained product Intrinsic viscosity dl / g Example 1 Fully water-soluble (water-insoluble matter ≤ 2%) White 0.52 Example 2 Fully water-soluble (water-insoluble matter ≤ 2%) White 1.19 Example 3 Fully water-soluble (water-insoluble matter ≤ 2%) White 0.65 Comparative Example 1 Not fully water-soluble (water-insoluble matter > 2%) Dark color, brown 5.45 Comparative Example 2 Not fully water-soluble (water-insoluble matter > 2%) Dark color, brown 4.04 Comparative Example 3 Not fully water-soluble (water-insoluble matter > 2%) Dark color, brown 3.57

[0067] Note: Intrinsic viscosity, a measure of solution viscosity, can be used to reflect the molecular weight of the reaction product. The larger the intrinsic viscosity, the greater the viscosity and the larger the average molecular weight.

[0068] Experimental Example 2

[0069] On November 16, 2022, a hydroponic wheat experiment was conducted, and the tested variety was Xinong 529.

[0070] The experiment was set up with 5 treatments, namely mannan oligosaccharide, 28-homobrassinolide, and naphthoxyacetic acid in Examples 1-3, with concentrations of 10 ppm, 10 ppm, 10 ppm, 0.02 ppm, and 10 ppm respectively, all being the concentrations in the hydroponic solution. The experimental results are shown in Table 2 and Figure 1 .

[0071] Table 2 Measured data of agronomic traits for each treatment in the experiment

[0072] Treatment Root length cm Stem length cm Fresh root weight g Fresh stem weight g Mannan oligosaccharide (Example 1) 12.9 b 9.4 a 0.07 a 0.08 a Mannan oligosaccharide (Example 2) 12.66 b 9.5 a 0.07 a 0.07 ab Mannan oligosaccharide (Example 3) 12.97 b 8.9 b 0.07 a 0.08 a 28-Homobrassinolide 14.26 a 8.68 a 0.04 b 0.07 ab Naphthoxyacetic acid 6.42 c 7.65 a 0.04 b 0.06 b

[0073] Note: Different lowercase letters indicate significant differences. (Principle for marking significant differences: First, arrange the means from largest to smallest (from top to bottom), and mark the letter a after the largest mean. Compare this mean with each mean in turn (downward process). All means with non-significant differences are marked with the same letter a until a mean with a significant difference from it is encountered, and then the letter b is marked, and the downward comparison stops. The significant differences are obtained by processing the experimental data with the data processing software SPSS 19.0.)

[0074] Figure 1Among them, from left to right, there are the growth situations of wheat under the treatments of mannan oligosaccharide of Example 1, 28-homobrassinolide, and naphthoxyacetic acid in sequence.

[0075] As can be seen from Table 2 and Figure 1 it can be known that from the various indexes of wheat, the fertilizer synergist of the present invention has an obvious promoting effect on the wheat roots. As a hormone, 28-homobrassinolide performs better in promoting the root length. However, the root quality thereof is much smaller than that of the mannan oligosaccharide of the present invention. Moreover, as a hormone, the use of 28-homobrassinolide has certain risks.

[0076] The fertilizer synergist prepared by the preparation method of the present invention is applied to vegetables by root irrigation or micro-irrigation, drip irrigation, flushing or foliar spraying, and is applied to grains and fruits by irrigation or foliar spraying according to the growth period.

[0077] Although the present invention has been described in detail with general descriptions and specific embodiments above, based on the present invention, some modifications or improvements can be made, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection required by the present invention.

Claims

1. A preparation method of mannan oligosaccharide for promoting the growth of crops, characterized in that, it includes: reacting guar gum with an oxidant in the presence of water; wherein, the weight ratio of the guar gum to water is 1:(20 - 50), and the weight ratio of the oxidant to water is 1:(10 - 20); the temperature of the reaction is 70 - 80 °C, and the reaction time is 3 - 4 h; the molecular weight of the mannan oligosaccharide is 180 - 9000 Da and not 180 Da.

2. The preparation method of mannan oligosaccharide for promoting the growth of crops according to claim 1, characterized in that, The oxidant is selected from H 2 O 2 , concentrated sulfuric acid, nitric acid, KMnO 4 , K 2 Cr 2 O 7 , KClO 3 or one or more of them.

3. The preparation method of mannan oligosaccharide for promoting the growth of crops according to claim 1 or 2, characterized in that, it includes: 1) Placing an appropriate amount of oxidant and water into a reaction kettle, and the weight ratio of the oxidant to water is 1:(10 - 20); 2) Adding guar gum into the reaction kettle in step 1), and the ratio of the guar gum to water is 1:(20 - 50), and adjusting the internal temperature of the reaction kettle to between 70 - 80 °C, and fully reacting for 3 - 4 h; 3) Concentrating using an ultrafiltration device; 4) Drying the liquid obtained in step 3) using a spray drying device to obtain mannan oligosaccharide powder.

4. Mannan oligosaccharide or mannan oligosaccharide powder prepared by the method according to any one of claims 1 - 3.

5. The application of the mannan oligosaccharide or mannan oligosaccharide powder according to claim 4 in crop production.

6. According to the application of claim 5, the application includes promoting crops to increase root length and stem length, and improving root fresh weight and stem fresh weight.

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