Preparation method and application of maltooligosaccharide

Abstract

According to the preparation method and the application of the maltooligosaccharide, high-straightness corn kernels are preferably selected as raw materials, and after microwave cooking and pulsed electric field cooperative treatment, the nutritional ingredients of corn are guaranteed, meanwhile, the corn kernels can be softened, a starch-protein composite structure can be destroyed, and the maltooligosaccharide has more excellent processing performance; the compounded alpha-amylase, alpha-transglucosidase and maltotriase are compounded, so that more maltooligosaccharides can be prepared; the prepared immobilized compound enzyme is high in thermal stability, the enzymolysis reaction efficiency and the enzymolysis effect can be guaranteed, the enzymolysis controllable degree is high, the immobilized compound enzyme can be reused, the production cost is reduced, the overall yield and purity are high, and the immobilized compound enzyme can replace serum protein to feed young animals, promote immune system development and improve organism immunity. The disease resistance is improved; the growth is promoted; the morbidity probability is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of maltooligosaccharide, and in particular to a preparation method of maltooligosaccharide and application thereof. Background Art

[0002] Maltooligosaccharide is an oligosaccharide composed of 3 to 10 glucose units connected by α-1,4 glycosidic bonds. It is a new sugar source that can prolong energy supply time, strengthen body endurance, resist fatigue, and is easy to digest and absorb. It has the characteristics of low sweetness, low permeability, high viscosity, good moisture retention, low hygroscopicity, and strong thickening effect. These unique properties make it have good adaptability to food processing. At the same time, maltooligosaccharide is also an important prebiotic that can promote the proliferation of beneficial bacteria such as bifidobacteria in the intestine and inhibit the growth of harmful bacteria, thereby maintaining the balance of intestinal microecology, improving intestinal function, enhancing the body's immune function, and providing the body with resistance to disease. Therefore, the use of maltooligosaccharide in the aquaculture industry has a very broad application prospect. Many oligosaccharides are usually prepared by controlling the hydrolysis and splitting of starch. In the production of oligosaccharides, the glycosidic bonds of starch molecules are partially hydrolyzed to produce at least one oligosaccharide, and more typically, a mixture of several oligosaccharides is produced. The mixture of oligosaccharides prepared in this way usually includes at least one oligosaccharide.

[0003] The prior art generally uses corn starch as raw material, and is prepared by liquefaction, concentration, drying and other processes through enzyme action. However, the prepared malt oligosaccharide still has the problem of low yield and easy agglomeration, which limits its application. In addition, the prior art mostly uses free enzymes, which have low reuse rate and lead to high cost. Summary of the invention

[0004] Based on this, in order to solve the problem that the maltooligosaccharide prepared in the prior art has low yield and is easy to agglomerate, thereby limiting its application, and the prior art mostly uses free enzymes, which have low reuse rates and also lead to high costs. The present invention provides a method for preparing maltooligosaccharide and its application, and the specific technical scheme is as follows:

[0005] A method for preparing maltooligosaccharide, comprising the following steps:

[0006] S1, pre-treating high-amylose corn kernels, adding water to perform microwave cooking, grinding at a low speed, performing pulse electric field treatment, and drying to obtain a mixture A;

[0007] S2, adding water to the mixture A, stirring evenly, adding the immobilized complex enzyme, reacting for 1 h to 3 h, recovering the immobilized complex enzyme, and obtaining a mixture B;

[0008] S3, filtering the mixture B, adding activated carbon for decolorization, and dialyzing to obtain a dialysate;

[0009] S4, continue to add the immobilized complex enzyme into the dialysate, treat for 15h to 20h, take the supernatant after centrifugation, concentrate it, and spray dry it to obtain maltooligosaccharide.

[0010] Furthermore, in step S1, the pretreatment is: adding water to the high-amylose corn kernels so that the water content accounts for 10% to 15% of the total mass, and stirring at a speed of 500r / min to 1000r / min for 30min to 40min, and then placing them in a peeling machine for several peeling processes so that the peeling rate reaches more than 90%, and then crushing them and passing them through a mesh sieve of 80 mesh to 120 mesh.

[0011] Furthermore, in step S1, the power of the microwave cooking is 250W to 300W, and the time is 15min to 20min.

[0012] Furthermore, in step S1, the rotation speed of the low-speed grinding is 150 r / min to 200 r / min.

[0013] Furthermore, in step S1, the electric field intensity of the pulse electric field treatment is 20KV / cm to 25KV / cm, the pulse frequency is 200Hz to 250Hz, and the treatment time is 5min to 10min.

[0014] Furthermore, in step S2, the material-liquid ratio of the mixture A to water is (5 g to 10 g) / 10 mL.

[0015] Furthermore, the preparation method of the immobilized complex enzyme is as follows: α-amylase, α-glucosidase and maltotriosidase are mixed to obtain a mixed enzyme, and then glutaraldehyde is added, cross-linked at 0-4°C for 1h-2h, and then sodium alginate solution is added, mixed evenly, and sodium acetate buffer is added, and hardened for 1h-3h to obtain an immobilized enzyme.

[0016] Furthermore, the mass ratio of the α-amylase, α-glucosidase and maltotriosidase is (1-5): (1-9): (1-7).

[0017] Furthermore, the added amount of glutaraldehyde accounts for 10% to 15% of the mass of the mixed enzyme.

[0018] In addition, the present invention also provides an application of maltooligosaccharide, which is the application of the maltooligosaccharide in feeding young animals.

[0019] Compared with the prior art, this application has the following beneficial effects:

[0020] 1. The present invention selects high-straight corn kernels as raw materials, and after microwave cooking and pulse electric field synergistic treatment, it can soften the corn kernels and destroy the starch-protein composite structure while ensuring the nutritional components of the corn, so that the corn kernels have better processing performance.

[0021] 2. The present invention compounds the compounded α-amylase, α-glucose transaminase and maltotriosidase to prepare more maltooligosaccharides; and the immobilized composite enzyme is prepared with high thermal stability, which can not only ensure the efficiency and effect of the enzymatic hydrolysis reaction, but also has a high degree of controllability of the enzymatic hydrolysis, and the immobilized composite enzyme can be reused to reduce production costs.

[0022] 3. The maltooligosaccharide prepared by the process of the present invention contains less macromolecular miscellaneous sugars and impurities, has high purity and yield, can replace serum protein to feed young animals, promote the development of the immune system, increase the body's immunity, improve disease resistance and promote growth, and reduce the probability of disease. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with its embodiments. It should be understood that the specific implementation methods described herein are only used to explain the present invention and do not limit the protection scope of the present invention.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0025] A method for preparing maltooligosaccharide in one embodiment of the present invention comprises the following steps:

[0026] S1, pre-treating high-amylose corn kernels, adding water to perform microwave cooking, grinding at a low speed, performing pulse electric field treatment, and drying to obtain a mixture A;

[0027] S2, adding water to the mixture A, stirring evenly, adding the immobilized complex enzyme, reacting for 1 h to 3 h, recovering the immobilized complex enzyme, and obtaining a mixture B;

[0028] S3, filtering the mixture B, adding activated carbon for decolorization, and dialyzing to obtain a dialysate;

[0029] S4, continue to add the immobilized complex enzyme into the dialysate, treat for 15h to 20h, take the supernatant after centrifugation, concentrate it, and spray dry it to obtain maltooligosaccharide.

[0030] In one embodiment, in step S1, the pretreatment is: adding water to the high-amylose corn kernels so that the water content accounts for 10% to 15% of the total mass, and stirring at a speed of 500r / min to 1000r / min for 30min to 40min, and then placing them in a peeling machine for several peeling processes so that the peeling rate reaches more than 90%, and then crushing them and passing them through a mesh sieve of 80 mesh to 120 mesh.

[0031] In one embodiment, in step S1, the power of the microwave cooking is 250W to 300W, and the time is 15min to 20min.

[0032] In one embodiment, in step S1, the rotation speed of the low-speed grinding is 150 r / min to 200 r / min.

[0033] In one of the embodiments, in step S1, the electric field intensity of the pulse electric field treatment is 20KV / cm to 25KV / cm, the pulse frequency is 200Hz to 250Hz, and the treatment time is 5min to 10min.

[0034] In one embodiment, in step S2, the material-liquid ratio of the mixture A to water is (5 g-10 g) / 10 mL.

[0035] In one embodiment, the preparation method of the immobilized complex enzyme is as follows: α-amylase, α-glucosidase and maltotriosidase are mixed to obtain a mixed enzyme, and then glutaraldehyde is added, cross-linked at 0-4°C for 1h-2h, and then sodium alginate solution is added, mixed evenly, and sodium acetate buffer is added, and hardened for 1h-3h to obtain an immobilized enzyme.

[0036] In one embodiment, the mass ratio of α-amylase, α-glucosidase and maltotriosidase is (1-5): (1-9): (1-7).

[0037] In one embodiment, the amount of glutaraldehyde added is 2% to 5% of the mass of the mixed enzyme.

[0038] In one of the embodiments, the mass percentage concentration of the sodium alginate solution is 20% to 45%.

[0039] In one embodiment, the volume ratio of the mixed enzyme to the sodium alginate solution is (1-7): (10-15).

[0040] In one embodiment, in step S2, the amount of the immobilized complex enzyme added is 3% to 8% of the mass of the mixture A.

[0041] In one embodiment, in step S2, the reaction temperature is 60°C to 85°C.

[0042] In one embodiment, in step S3, the amount of activated carbon added is 5% to 10% of the mass of the mixture B.

[0043] In one embodiment, in step S3, the DE value of the dialysate is greater than 30.

[0044] In one embodiment, in step S4, the amount of immobilized complex enzyme added is 4% to 7% of the dialysate mass.

[0045] In one embodiment, in step S4, the treatment temperature is 60°C to 95°C.

[0046] In one embodiment, in step S4, the rotation speed of the centrifugal treatment is 5000 r / min to 8000 r / min, and the time is 3 min to 10 min.

[0047] In one embodiment, the spray drying process is: preheating the spray dryer for 5 minutes, so that the air temperature at the inlet reaches 80℃~90℃, and the air temperature at the outlet reaches 60℃~70℃, and then the concentrated liquid is sent to the spray drying tower through a high-pressure homogenization pressure of 15MPa~25MPa, and spray drying is performed under the conditions of an inlet air temperature of 100℃~120℃, an exhaust air temperature of 65℃~90℃, and a feed flow rate of 3.5L / h~7.0L / h. The spray drying method can reduce the probability of agglomeration of oligosaccharides and can be used in the field of animal feeding.

[0048] In addition, the present invention also provides an application of maltooligosaccharide, which is the application of the maltooligosaccharide in feeding young animals.

[0049] The above scheme has a high yield in preparing maltooligosaccharide, the immobilized complex enzyme can be reused, and the overall production cost is controllable.

[0050] The embodiments of the present invention will be described in detail below with reference to specific examples.

[0051] Embodiment 1:

[0052] A method for preparing maltooligosaccharide comprises the following steps:

[0053] S1. Add water to the high-linear corn kernels so that the water content accounts for 12% of the total mass, stir at a speed of 800 r / min for 35 min, then place in a peeling machine for several peeling processes so that the peeling rate reaches more than 90%, then crush, pass through an 80-mesh sieve, then add water, microwave cook at a power of 250 W for 15 min, then grind at a low speed at a speed of 150 r / min, and then perform pulse electric field treatment at an electric field strength of 20 KV / cm and a pulse frequency of 200 Hz for 10 min, and after drying, obtain a mixture A;

[0054] S2, mixing α-amylase, α-glucosidase and maltotriosidase in a mass ratio of 5:7:3 to obtain a mixed enzyme, then adding 3% glutaraldehyde accounting for the mass of the mixed enzyme, cross-linking at 0°C for 2h, then adding a sodium alginate solution with a mass percentage concentration of 35%, mixing evenly, and adding sodium acetate buffer, and hardening for 3h to obtain an immobilized enzyme;

[0055] According to the material-liquid ratio of the mixture A to water being 8 g / 10 mL, water was added to the mixture A, and after being stirred evenly, 5% of the mass of the immobilized complex enzyme was added, and the mixture was reacted at 85° C. for 3 h, and the immobilized complex enzyme was recovered to obtain a mixture B;

[0056] S3, after filtering the mixture B, adding 7% of the weight of the mixture B in activated carbon for decolorization, and dialyzing to obtain a dialysate;

[0057] S4, adding 4% of the mass of the dialysate to the immobilized complex enzyme, treating the dialysate at 90° C. for 15 h, centrifuging the dialysate at 6000 r / min for 5 min, taking the supernatant, and concentrating the supernatant to obtain a concentrated solution;

[0058] S5. Preheat the spray dryer for 5 minutes to make the air temperature at the inlet reach 85°C and the air temperature at the outlet reach 60°C, then send the concentrated liquid into the spray drying tower through a high-pressure homogenization pressure of 15MPa, and spray dry it under the conditions of an inlet air temperature of 100°C, an exhaust air temperature of 65°C, and a feed flow rate of 5.0L / h to obtain maltooligosaccharides.

[0059] Embodiment 2:

[0060] A method for preparing maltooligosaccharide comprises the following steps:

[0061] S1. Add water to the high-linear corn kernels so that the water content accounts for 13% of the total mass, stir at a speed of 800 r / min for 40 min, then place in a peeling machine for several peeling processes so that the peeling rate reaches more than 90%, then crush, pass through a 100-mesh sieve, then add water, microwave cook at a power of 260 W for 15 min, then grind at a low speed at a speed of 180 r / min, then perform pulse electric field treatment at an electric field strength of 22 KV / cm and a pulse frequency of 220 Hz for 6 min, and after drying, obtain a mixture A;

[0062] S2, mixing α-amylase, α-glucosidase and maltotriosidase in a mass ratio of 4:7:4 to obtain a mixed enzyme, then adding 4% glutaraldehyde of the mass of the mixed enzyme, cross-linking at 0°C for 2h, then adding a sodium alginate solution with a mass percentage concentration of 38%, mixing evenly, and adding sodium acetate buffer, and hardening for 3h to obtain an immobilized enzyme;

[0063] According to the material-liquid ratio of the mixture A to water being 8 g / 10 mL, water was added to the mixture A, and after being stirred evenly, 5% of the mass of the immobilized complex enzyme was added, and the mixture was reacted at 80° C. for 3 h, and the immobilized complex enzyme was recovered to obtain a mixture B;

[0064] S3, after filtering the mixture B, adding 7% of the weight of the mixture B in activated carbon for decolorization, and dialyzing to obtain a dialysate;

[0065] S4, adding 7% of the mass of the dialysate to the immobilized complex enzyme into the dialysate, treating at 95° C. for 16 h, centrifuging at 8000 r / min for 8 min, taking the supernatant, and concentrating to obtain a concentrated solution;

[0066] S5. Preheat the spray dryer for 5 minutes to make the air temperature at the inlet reach 90°C and the air temperature at the outlet reach 70°C, and then send the concentrated liquid into the spray drying tower through a high-pressure homogenization pressure of 25MPa, and spray dry it under the conditions of an inlet air temperature of 120°C, an exhaust air temperature of 90°C, and a feed flow rate of 6.0L / h to obtain maltooligosaccharides.

[0067] Embodiment 3:

[0068] A method for preparing maltooligosaccharide comprises the following steps:

[0069] S1. Add water to the high-linear corn kernels so that the water content accounts for 15% of the total mass, stir at a speed of 1000 r / min for 30 min, then place in a peeling machine for several peeling processes to make the peeling rate reach more than 90%, then crush, pass through a 120-mesh sieve, then add water, microwave cook at a power of 300 W for 15 min, then grind at a low speed at a speed of 150 r / min, then perform pulse electric field treatment at an electric field strength of 25 KV / cm and a pulse frequency of 250 Hz for 5 min, and after drying, obtain a mixture A;

[0070] S2, mixing α-amylase, α-glucosidase and maltotriosidase in a mass ratio of 5:8:2 to obtain a mixed enzyme, then adding 3% glutaraldehyde accounting for the mass of the mixed enzyme, cross-linking at 0°C for 2h, then adding a sodium alginate solution with a mass percentage concentration of 40%, mixing evenly, and adding sodium acetate buffer, and hardening for 3h to obtain an immobilized enzyme;

[0071] According to the material-liquid ratio of the mixture A to water being 8 g / 10 mL, water was added to the mixture A, and after being stirred evenly, 5% of the mass of the immobilized complex enzyme was added, and the mixture was reacted at 80° C. for 2 h, and the immobilized complex enzyme was recovered to obtain a mixture B;

[0072] S3, after filtering the mixture B, adding 8% of the weight of the mixture B in activated carbon for decolorization, and dialyzing to obtain a dialysate;

[0073] S4, adding 7% of the mass of the immobilized complex enzyme to the dialysate, treating at 95° C. for 18 h, centrifuging at 6000 r / min for 8 min, taking the supernatant, and concentrating to obtain a concentrated solution;

[0074] S5. Preheat the spray dryer for 5 minutes to make the air temperature at the inlet reach 90°C and the air temperature at the outlet reach 65°C, and then send the concentrated liquid into the spray drying tower through a high-pressure homogenization pressure of 22MPa, and spray dry it under the conditions of an inlet air temperature of 110°C, an exhaust air temperature of 85°C, and a feed flow rate of 4.5L / h to obtain maltooligosaccharides.

[0075] Comparative Example 1:

[0076] The difference between Comparative Example 1 and Example 3 is that a single α-amylase is added in Comparative Example 1, and the rest is the same as Example 3.

[0077] Comparative Example 2:

[0078] The difference between Comparative Example 2 and Example 3 is that a single α-glucosidase is added in Comparative Example 2, and the other steps are the same as those in Example 3.

[0079] Comparative Example 3:

[0080] The difference between Comparative Example 3 and Example 3 is that a single maltotriosidase is added in Comparative Example 3, and the rest is the same as Example 3.

[0081] Comparative Example 4:

[0082] The difference between Comparative Example 4 and Example 3 is that the preparation method of the immobilized complex enzyme is different, and the other parts are the same as Example 3. The preparation method of the immobilized complex enzyme in Comparative Example 4 is as follows:

[0083] Alpha-amylase, alpha-glucose transaminase and maltotriosidase in a mass ratio of 5:8:2 are mixed to obtain a mixed enzyme, and then gelatin accounting for 10% of the mass of the mixed enzyme is added, heated to 65° C. and stirred for 20 minutes, and then cooled to obtain an immobilized enzyme.

[0084] Comparative Example 5:

[0085] The difference between Comparative Example 5 and Example 3 is that in Comparative Example 5, α-amylase, α-glucosidase and maltotriosidase in a mass ratio of 5:8:2 are mixed to obtain a mixed enzyme, which is directly added for use, i.e., no immobilization treatment is performed, and the rest is the same as Example 3.

[0086] Comparative Example 6:

[0087] The difference between Comparative Example 6 and Example 3 is that Comparative Example 6 does not undergo a microwave cooking process, and the rest is the same as Example 3.

[0088] Comparative Example 7:

[0089] The difference between Comparative Example 7 and Example 3 is that Comparative Example 7 is not subjected to pulse electric field treatment, and the rest is the same as Example 3.

[0090] Comparative Example 8:

[0091] The difference between Comparative Example 8 and Example 3 is that the conventional drying process is used in Comparative Example 8 instead of spray drying. That is, the drying process of Comparative Example 8 is: drying the concentrated liquid at a temperature of 110° C. for 40 minutes, and the rest is the same as Example 3.

[0092] The immobilized composite enzymes prepared in Examples 1 to 3 and the immobilized composite enzymes prepared in Comparative Examples 1 to 4 were subjected to performance tests, and the results are shown in Table 1 below.

[0093] The method is as follows: weigh several grams of immobilized enzyme, add an appropriate amount of acetic acid buffer with a pH of 5.0, then add 1 mL of methyl aD-glucoside with a mass percentage of 2%, and shake in a 40°C water bath for 1 hour. After the reaction is completed, take 1 mL of the reaction solution, add 3 mL of the enzyme complex reagent, place in a 36°C water bath for 40 minutes, cool at room temperature, and then add 6 mL of distilled water to make the volume 10 mL. Measure the absorbance at a wavelength of 505 nm. Add 1 mL of diluted free enzyme to 8 mL of distilled water, heat and boil for 10 minutes to inactivate the enzyme, and then add 1 mL of 2% methyl-α-glucose transaminase solution. Under this condition for 1 hour, the amount of enzyme that acts on methyl-α-glucose transaminase to generate 1 pg of glucose is defined as 1 activity unit.

[0094]

[0095]

[0096] From the data analysis of Table 1, it can be seen that the present application obtains a mixed enzyme by mixing α-amylase, α-glucosidase and maltotriosidase, then cross-linking by specific glutaraldehyde, and then embedding by sodium alginate solution, and can obtain an immobilized composite enzyme with excellent physical strength as a whole, and the activity recovery rate of the immobilized composite enzyme is high, and it can be reused. However, in Comparative Examples 1 to 3, a single enzyme is immobilized, and the overall enzyme activity recovery rate is worse than that of Example 3. In Comparative Example 4, gelatin is used for embedding, and not only the immobilized composite enzyme strength is poor, but also the enzyme activity recovery rate is low, which does not meet the requirements of reuse.

[0097] In addition, the products prepared in Examples 1 to 3 and the products prepared in Comparative Examples 1 to 8 were analyzed to obtain the conversion rate of maltooligosaccharide. The results are shown in Table 2 below.

[0098] Table 2:

[0099]

[0100]

[0101] From the data analysis of Table 2, it can be seen that the present application, by optimizing the composition of the immobilized complex enzyme and the preparation process of oligomaltosaccharide, has a synergistic effect as a whole, can effectively increase the conversion rate of oligomaltosaccharide, and the oligomaltosaccharide obtained after spray drying is not easy to agglomerate, and the oligomaltosaccharide obtained by conventional drying process in Comparative Example 8 has agglomeration phenomenon, indicating that spray drying helps to reduce the probability of oligomaltosaccharide agglomeration. Meanwhile, in the preparation process, the processing of the complex enzyme also affects the composition change of the oligomaltosaccharide obtained, and then causes the problem of agglomeration in the storage process in the later stage. Therefore, by the optimization of the present application process, oligomaltosaccharide with more stable storage performance can be obtained.

[0102] Application examples:

[0103] The oligomaltose prepared in Example 3 was applied to the feeding of young animals, for weaned piglets, a control group was set up, and under the same feeding conditions and basic diet as the control group, the oligomaltose prepared in Example 3 with a mass percentage content of 0.6% was added to the application example 1 group; the difference between application example 2 and application example 1 was that the addition amount of oligomaltose was 0.8%, and the others were the same as application example 1; the difference between application example 3 and application example 1 was that the addition amount of oligomaltose was 1%, and the others were the same as application example 1; the difference between application example 4 and application example 1 was that the addition amount of oligomaltose was 1.2%, and the others were the same as application example 1; the difference between application example 5 and application example 1 was that the addition amount of oligomaltose was 1.5%, and the others were the same as application example 1. Compared with the control group, the obtained diarrhea rate reduction rate is shown in Table 3.

[0104] Table 3:

[0105]

[0106] From the data analysis of Table 3, it can be seen that the maltooligosaccharide prepared in the present application can be used in the feeding of young animals, can significantly improve the immune function of piglets and reduce the incidence of disease.

[0107] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0108] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing maltooligosaccharide, characterized in that: The preparation method comprises the following steps: S1, pre-treating high-amylose corn kernels, adding water to perform microwave cooking, grinding at a low speed, performing pulse electric field treatment, and drying to obtain a mixture A; S2, adding water to the mixture A, stirring evenly, adding the immobilized complex enzyme, reacting for 1 h to 3 h, recovering the immobilized complex enzyme, and obtaining a mixture B; S3, filtering the mixture B, adding activated carbon for decolorization, and dialyzing to obtain a dialysate; S4, continue to add the immobilized complex enzyme into the dialysate, treat for 15h to 20h, take the supernatant after centrifugation, concentrate it, and spray dry it to obtain maltooligosaccharide.

2. The preparation method according to claim 1, characterized in that: In step S1, the pretreatment is: adding water to the high-amylose corn kernels so that the water content accounts for 10% to 15% of the total mass, and stirring at a speed of 500r / min to 1000r / min for 30min to 40min, and then placing them in a peeling machine for several peeling processes so that the peeling rate reaches more than 90%, and then crushing them and passing them through a mesh sieve of 80 mesh to 120 mesh.

3. The preparation method according to claim 1, characterized in that: In step S1, the power of the microwave cooking is 250W to 300W, and the time is 15min to 20min.

4. The preparation method according to claim 1, characterized in that: In step S1, the rotation speed of the low-speed grinding is 150 r / min to 200 r / min.

5. The preparation method according to claim 1, characterized in that: In step S1, the electric field intensity of the pulse electric field treatment is 20KV / cm to 25KV / cm, the pulse frequency is 200Hz to 250Hz, and the treatment time is 5min to 10min.

6. The preparation method according to claim 1, characterized in that: In step S2, the material-liquid ratio of the mixture A to water is (5 g to 10 g) / 10 mL.

7. The preparation method according to claim 1, characterized in that: The preparation method of the immobilized complex enzyme is as follows: α-amylase, α-glucosidase and maltotriosidase are mixed to obtain a mixed enzyme, glutaraldehyde is added, cross-linked for 1h to 2h at 0-4°C, sodium alginate solution is added, mixed evenly, sodium acetate buffer is added, and the immobilized enzyme is obtained after hardening for 1h to 3h.

8. The preparation method according to claim 7, characterized in that: The mass ratio of the α-amylase, α-glucosidase and maltotriosidase is (1-5): (1-9): (1-7).

9. The preparation method according to claim 8, characterized in that: The added amount of the glutaraldehyde accounts for 10% to 15% of the mass of the mixed enzyme.

10. An application of maltooligosaccharide, characterized in that: The maltooligosaccharide is the maltooligosaccharide according to any one of claims 1 to 9, and the application is the application of the maltooligosaccharide in feeding young animals.

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