A method for preparing glucose from starch

Abstract

The invention discloses a method for preparing glucose from starch, belongs to the technical field of preparing glucose by enzymolysis, and the method comprises the following steps: sizing, ultrasonic treatment, pretreatment, pre-expansion treatment, hydrolysis saccharification, filtration, desalination, concentration, and drying; the method for the pre-expansion treatment is to first add pre-treated gum arabic solution and carboxymethyl starch to the pre-treated starch slurry, stir for 20-30min and mix evenly at a speed of 600-800rpm, then warm up to 58-62°C, and keep 30-40min at this temperature to pre-expand starch particles. The method reduces the production energy consumption of glucose, shortens the production cycle, and improves the glucose yield and glucose value of glucose prepared by raw amylase, the glucose yield is 97.8-98.4%, and the glucose value is 96.2-96.6%.

Description

Technical Field

[0001] The invention belongs to the technical field of preparing glucose by enzymatic hydrolysis, and specifically relates to a method for preparing glucose from starch. Background Art

[0002] Starch is a polymeric carbohydrate composed of a large number of glucose units connected by glycosidic bonds. It is the main reserve polymer of corn, wheat, oats, rice, cassava, etc., and is often used as a raw material for starch sugar production in industrial production. Both inorganic acids and enzymes can catalyze the hydrolysis of starch into glucose, but the hydrolysis methods are different. The former is chaotic, that is, it randomly cuts the α-1,4 and α-1,6 glycosidic bonds of starch molecules and releases low-polymerization substances at the same time. The acid hydrolysis process of starch is carried out in several stages, and various intermediates are generated at the same time, and finally it is completely hydrolyzed into glucose. The enzymatic hydrolysis process of starch is specific, and different enzymes have different specificities. Compared with the traditional acid hydrolysis of starch, the uniqueness of enzymatic hydrolysis is that it can reduce the odor and color of the sugar solution, and can obtain a higher product yield and reduce refining costs.

[0003] The traditional production process of enzymatic conversion of starch into glucose requires two steps, namely liquefaction (90℃-110℃) and saccharification (about 65℃), which are respectively carried out by α-amylase and saccharifying enzyme. The liquefaction step is usually carried out at a higher temperature, generally between 90℃ and 110℃, and the liquefaction time may be as long as about 1 hour, or even longer; the temperature of the saccharification step is usually between 50℃ and 70℃, and the liquefaction time takes 36-72h. Due to the long-term high temperature setting in this stage, the energy input accounts for about 30%-40% of the entire starch-based production process, thus increasing the production cost of starch sugar products.

[0004] In order to reduce starch processing costs, reduce energy consumption in the production process, and shorten production cycles, it is necessary to provide and use enzymes that can directly hydrolyze raw starch at low temperatures. Raw starch enzymes can catalyze the hydrolysis of α-1,4 glucosidic bonds from the non-reducing end of starch chains, and can also slowly hydrolyze α-1,6 glucosidic bonds. They can directly hydrolyze raw starch into glucose, combining starch gelatinization, liquefaction, and saccharification in traditional processes into one step for direct saccharification, avoiding high-temperature cooking and simplifying the starch transport process.

[0005] The substrate of raw amylase is ungelatinized starch granules. Compared with the enzymatic hydrolysis of gelatinized starch, the degradation of raw starch is more complicated. Because during the gelatinization process, the molecular structure of starch becomes loose, the double helix dissociates, and the degree of disorder increases, making it easier for enzyme molecules to approach and act on the breaking sites of the starch molecular chains. At the same time, the network structure formed after gelatinization increases the contact area between starch molecules and enzyme molecules, and also improves the efficiency of the enzymatic hydrolysis reaction. Raw amylase omits the gelatinization step for the hydrolysis of starch granules and can directly act on starch granules. The tight stacking of the crystalline structure of starch granules hinders the combination of enzyme molecules and starch, making it difficult for the enzyme to penetrate and degrade, reducing the degradation efficiency of raw starch.

[0006] CN104673861A discloses a method for improving the enzymatic hydrolysis efficiency of raw starch. High-concentration starch is used as a substrate, raw amylase is added, and the temperature is controlled in two stages. The reaction is first carried out at 45-60°C for 15-40 minutes, and then the temperature is raised to 60-70°C for reaction. The total reaction time is 2-3 hours. This method improves the enzymatic hydrolysis efficiency and the glucose yield is increased to about 40%. This method can improve the enzymatic hydrolysis efficiency of raw starch to a certain extent, but the glucose yield is still low, the starch cannot be fully converted into glucose, the raw material is seriously wasted, the glucose output is limited, and the production efficiency is low.

[0007] CN118979084A discloses a method for preparing glucose-malt syrup by synergistically hydrolyzing raw starch with multiple enzymes. In this application, 1-5U / mg raw amylase is acted on starch slurry at 30-35°C for 10-20h, then the temperature is raised to 55-65°C, and 0.5-1.5U / mg high-temperature resistant α-amylase, 0.5-1.5U / mg medium-temperature α-amylase, 0.5-1.5U / mg glucose amylase and pullulanase are added for synergistic hydrolysis for 60h, which can increase the hydrolysis rate to 96.09% and the DE value to 43.86. Compared with the traditional method, the energy consumption in the high-temperature gelatinization stage of starch can be avoided, and a certain energy-saving effect can be achieved. However, the hydrolysis rate of starch by raw amylase in this application is 42.37%, which is still relatively low. Large doses of multiple enzymes are required to synergize to increase the hydrolysis rate. The energy consumption of multi-enzyme hydrolysis is high, resulting in high production costs, and the production cycle of this method is long. Summary of the invention

[0008] In view of the shortcomings of the prior art, the present invention provides a method for preparing glucose from starch, which reduces the production energy consumption of preparing glucose by enzymatic hydrolysis, shortens the production cycle, reduces the amount of enzyme used, and improves the glucose yield and glucose value of glucose prepared by raw amylase.

[0009] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0010] A method for preparing glucose from starch, comprising the following steps: slurry adjustment, ultrasonic treatment, pretreatment, pre-expansion treatment, hydrolysis and saccharification, filtration, desalination, concentration, and drying;

[0011] The preparation method is specifically as follows:

[0012] The slurry preparation method comprises mixing corn starch and water evenly to obtain starch slurry;

[0013] The mass concentration of the starch slurry is 20-30%.

[0014] The ultrasonic treatment method comprises the following steps: subjecting the starch slurry to ultrasonic treatment at a frequency of 20-22 KHz for 15-20 min, and then subjecting the starch slurry to ultrasonic treatment at a frequency of 28-30 KHz for 15-20 min, to obtain the starch slurry after ultrasonic treatment.

[0015] The pretreatment method comprises adding calcium chloride to the starch slurry after ultrasonic treatment, adjusting the pH value of the slurry to 4.5-5 with a hydrochloric acid solution, stirring and balancing for 20-30 minutes, adding α-1,4-glucose hydrolase, reacting at 50-55° C. for 2-3 hours, adjusting the pH value to 12-14 with a sodium hydroxide solution, standing for 10-15 minutes to inactivate the enzyme, stirring and balancing for 20-30 minutes, adjusting the pH value of the slurry to 4.8-5.2 with a hydrochloric acid solution, adding transferglucosidase, stirring and reacting at 50-55° C. and 200-300 rpm for 5-8 hours, adjusting the pH value to 12-14 with a sodium hydroxide solution, standing for 10-15 minutes to inactivate the enzyme, and adjusting the pH value to 7-8 with a hydrochloric acid solution to obtain a pretreated starch slurry;

[0016] The concentration of the hydrochloric acid solution is 0.1-0.15 mol / L;

[0017] The amount of calcium chloride added is 200-250 mg / L;

[0018] The concentration of the sodium hydroxide solution is 0.5-0.6 mol / L;

[0019] The added amount of the α-1,4-glucose hydrolase is 40-50 U / g;

[0020] The added amount of the transglucosidase is 200-300 U / g.

[0021] The pre-expansion treatment method comprises first adding a pre-treated gum arabic solution and carboxymethyl starch to a pre-treated starch slurry, stirring at a speed of 600-800 rpm for 20-30 minutes to mix evenly, then heating to 58-62° C. and maintaining the temperature for 30-40 minutes to pre-expand the starch particles to obtain a pre-expanded starch slurry;

[0022] The preparation method of the pretreated gum arabic solution is as follows: dissolving gum arabic in water at 50-55° C. to prepare a 40-45wt% gum arabic solution, then raising the temperature to 80-85° C., keeping the temperature for 1-1.5 hours, and then cooling the temperature to 50-55° C. to obtain the pretreated gum arabic solution;

[0023] The degree of substitution DS of the carboxymethyl starch is greater than 0.2;

[0024] The mass ratio of the pretreated starch slurry, the pretreated gum arabic solution and the carboxymethyl starch is 100:6-8:3-5.

[0025] The hydrolysis saccharification method comprises adjusting the pH of the pre-swollen starch slurry to 4.0-4.5 with a hydrochloric acid solution, adding raw amylase to the pre-swollen starch slurry, and reacting at a temperature of 50-55° C. for 5-6 hours to obtain a glucose solution;

[0026] The concentration of the hydrochloric acid solution is 0.1-0.15 mol / L;

[0027] The added amount of the raw amylase is 60-80 U / g.

[0028] The filtering method comprises the following steps: lowering the temperature of the glucose solution to 40-45° C., adding activated carbon for decolorization, filtering, and then filtering and removing impurities from the glucose solution using a membrane filtration system to obtain a permeate.

[0029] The desalination method is to put the permeate into an ion exchange column for desalination, purification and refining to obtain a purified sugar solution.

[0030] The concentration method is to purify the sugar solution at 120-130° C. by vacuum concentration to obtain glucose crystals.

[0031] The drying method comprises placing the glucose crystals at 50-60° C. and drying them for 1-1.5 hours, and then crushing and sieving to obtain the finished glucose product.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] (1) The method for preparing glucose from starch of the present invention avoids the high-temperature gelatinization process. The temperature required for the hydrolysis and saccharification process is low, and the hydrolysis and saccharification temperature is 50-55°C, which reduces the production energy consumption of preparing glucose and shortens the time. The time of the main hydrolysis and saccharification process is reduced to within 6 hours, shortening the production cycle.

[0034] (2) The method of the present invention is used to improve the glucose yield and glucose value of glucose prepared by raw amylase, with the glucose yield being 97.8-98.4% and the glucose value (DE value) being 96.2-96.6%. DETAILED DESCRIPTION

[0035] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific implementation methods of the present invention are now described.

[0036] Example 1

[0037] A method for preparing glucose from starch, comprising the following steps: slurry adjustment, ultrasonic treatment, pretreatment, pre-expansion treatment, hydrolysis and saccharification, filtration, desalination, concentration, and drying;

[0038] The preparation method is specifically as follows:

[0039] (1) Slurry preparation: Mix corn starch and water evenly to obtain a starch slurry with a mass concentration of 20%.

[0040] (2) Ultrasonic treatment: The starch slurry is ultrasonically treated at a frequency of 20 kHz for 20 min, and then ultrasonically treated at a frequency of 28 kHz for 20 min to obtain an ultrasonically treated starch slurry.

[0041] (3) Pretreatment: Calcium chloride was added to the starch slurry after ultrasonic treatment in an amount of 200 mg / L, the pH of the slurry was adjusted to 4.5 with 0.1 mol / L hydrochloric acid solution, stirred and balanced for 20 min, and then α-1,4-glucose hydrolase was added. After reacting at 50°C for 3 h, the pH was adjusted to 12 with 0.5 mol / L sodium hydroxide solution, and the enzyme was inactivated for 10 min. After stirring and balancing for 20 min, the pH of the slurry was adjusted to 4.8 with 0.1 mol / L hydrochloric acid solution, and then transfer glucosidase was added. After reacting at 50°C and 200 rpm for 8 h, the pH was adjusted to 12 with 0.5 mol / L sodium hydroxide solution, and the enzyme was inactivated for 10 min. Then, the pH was adjusted to 7 with 0.1 mol / L hydrochloric acid solution to obtain a pretreated starch slurry.

[0042] The added amount of the α-1,4-glucose hydrolase is 40 U / g;

[0043] The added amount of the transglucosidase is 200 U / g.

[0044] (4) Pre-expansion treatment: first, add the pre-treated gum arabic solution and carboxymethyl starch to the pre-treated starch slurry, stir at 600 rpm for 30 min to mix evenly, then heat to 58 °C and maintain at this temperature for 40 min to pre-expand the starch particles to obtain a pre-expanded starch slurry;

[0045] The method for preparing the pretreated gum arabic solution comprises dissolving gum arabic in water at 50° C. to prepare a 40 wt % gum arabic solution, then raising the temperature to 80° C., keeping the temperature for 1.5 hours, and then cooling the temperature to 50° C. to obtain the pretreated gum arabic solution;

[0046] The degree of substitution DS of the carboxymethyl starch is greater than 0.2;

[0047] The mass ratio of the pretreated starch slurry, the pretreated gum arabic solution and the carboxymethyl starch is 100:6:3.

[0048] (5) Hydrolysis and saccharification: The pH of the pre-swollen starch slurry was adjusted to 4.0 with a 0.1 mol / L hydrochloric acid solution, and raw amylase was added to the pre-swollen starch slurry. The reaction was carried out at a temperature of 50°C for 6 hours to obtain a glucose solution.

[0049] The added amount of the raw amylase is 60 U / g.

[0050] (6) Filtration: Lower the temperature of the glucose solution to 40°C, add activated carbon for decolorization and filtration, and then use a membrane filtration system to filter and remove impurities from the glucose solution to obtain a permeate.

[0051] (7) Desalination: The permeate is loaded into an ion exchange column for desalination and purification to obtain purified sugar solution.

[0052] (8) Concentration: The purified sugar solution is concentrated by vacuum concentration at 120°C to obtain glucose crystals.

[0053] (9) Drying: Dry the glucose crystals at 50°C for 1.5 hours, and then crush and sieve to obtain the finished glucose product.

[0054] Example 2

[0055] A method for preparing glucose from starch, comprising the following steps: slurry adjustment, ultrasonic treatment, pretreatment, pre-expansion treatment, hydrolysis and saccharification, filtration, desalination, concentration, and drying;

[0056] The preparation method is specifically:

[0057] (1) Slurry preparation: Mix corn starch and water evenly to obtain a starch slurry with a mass concentration of 25%.

[0058] (2) Ultrasonic treatment: The starch slurry was ultrasonically treated at a frequency of 21 kHz for 18 min, and then ultrasonically treated at a frequency of 29 kHz for 18 min to obtain an ultrasonically treated starch slurry.

[0059] (3) Pretreatment: Calcium chloride was added to the starch slurry after ultrasonic treatment in an amount of 220 mg / L, the pH of the slurry was adjusted to 4.7 with 0.12 mol / L hydrochloric acid solution, and the mixture was stirred for 25 min. α-1,4-glucose hydrolase was added and reacted at 52°C for 2.5 h, and the pH was adjusted to 13 with 0.55 mol / L sodium hydroxide solution, and the mixture was allowed to stand for 12 min to inactivate the enzyme, and the mixture was stirred for 25 min. The pH of the slurry was adjusted to 5 with 0.12 mol / L hydrochloric acid solution, and then transfer glucosidase was added, and the mixture was stirred for 6 h at 52°C and 250 rpm, and the pH was adjusted to 13 with 0.55 mol / L sodium hydroxide solution, and the mixture was allowed to stand for 12 min to inactivate the enzyme, and the pH was adjusted to 7.5 with 0.12 mol / L hydrochloric acid solution to obtain a pretreated starch slurry.

[0060] The added amount of the α-1,4-glucose hydrolase is 45 U / g;

[0061] The added amount of the transglucosidase is 250 U / g.

[0062] (4) Pre-expansion treatment: first, add the pre-treated gum arabic solution and carboxymethyl starch to the pre-treated starch slurry, stir at 700 rpm for 25 min to mix evenly, then heat to 60°C and maintain at this temperature for 35 min to pre-expand the starch particles to obtain a pre-expanded starch slurry;

[0063] The method for preparing the pretreated gum arabic solution comprises dissolving gum arabic in water at 52° C. to prepare a 42 wt % gum arabic solution, then raising the temperature to 82° C., keeping the temperature for 1.2 hours, and then cooling the temperature to 52° C. to obtain the pretreated gum arabic solution;

[0064] The degree of substitution DS of the carboxymethyl starch is greater than 0.2;

[0065] The mass ratio of the pretreated starch slurry, the pretreated gum arabic solution and the carboxymethyl starch is 100:7:4.

[0066] (5) Hydrolysis and saccharification: The pH of the pre-swollen starch slurry was adjusted to 4.2 with a 0.12 mol / L hydrochloric acid solution, and raw amylase was added to the pre-swollen starch slurry. The reaction was carried out at a temperature of 52°C for 5.5 hours to obtain a glucose solution;

[0067] The added amount of the raw amylase is 70 U / g.

[0068] (6) Filtration: Reduce the temperature of the glucose solution to 42°C, add activated carbon for decolorization and filtration, and then use a membrane filtration system to filter and remove impurities from the glucose solution to obtain a permeate.

[0069] (7) Desalination: The permeate is loaded into an ion exchange column for desalination and purification to obtain purified sugar solution.

[0070] (8) Concentration: The purified sugar solution is concentrated by vacuum concentration at 125°C to obtain glucose crystals.

[0071] (9) Drying: Dry the glucose crystals at 55°C for 1.2 hours, and then crush and sieve to obtain the finished glucose product.

[0072] Example 3

[0073] A method for preparing glucose from starch, comprising the following steps: slurry adjustment, ultrasonic treatment, pretreatment, pre-expansion treatment, hydrolysis and saccharification, filtration, desalination, concentration, and drying;

[0074] The preparation method is specifically:

[0075] (1) Slurry preparation: Mix corn starch and water evenly to obtain a starch slurry with a mass concentration of 30%.

[0076] (2) Ultrasonic treatment: The starch slurry was ultrasonically treated at a frequency of 22 kHz for 15 min, and then ultrasonically treated at a frequency of 30 kHz for 15 min to obtain an ultrasonically treated starch slurry.

[0077] (3) Pretreatment: Calcium chloride was added to the starch slurry after ultrasonic treatment in an amount of 250 mg / L, the pH of the slurry was adjusted to 5 with 0.15 mol / L hydrochloric acid solution, stirred and balanced for 30 min, α-1,4-glucose hydrolase was added, and the pH was adjusted to 14 with 0.6 mol / L sodium hydroxide solution after reacting at 55°C for 2 h, and the enzyme was inactivated for 15 min. Stirring and balancing for 30 min, the pH of the slurry was adjusted to 5.2 with 0.15 mol / L hydrochloric acid solution, and then transfer glucosidase was added, and the reaction was stirred at 55°C and 300 rpm for 5 h, and the pH was adjusted to 14 with 0.6 mol / L sodium hydroxide solution. The enzyme was inactivated for 15 min, and then the pH was adjusted to 8 with 0.15 mol / L hydrochloric acid solution to obtain a pretreated starch slurry;

[0078] The added amount of the α-1,4-glucose hydrolase is 50 U / g;

[0079] The added amount of the transglucosidase is 300 U / g.

[0080] (4) Pre-expansion treatment: first, add the pre-treated gum arabic solution and carboxymethyl starch to the pre-treated starch slurry, stir at 600 rpm for 30 min to mix evenly, then heat to 62 °C and maintain at this temperature for 30 min to pre-expand the starch particles to obtain a pre-expanded starch slurry;

[0081] The method for preparing the pretreated gum arabic solution comprises dissolving gum arabic in water at 55° C. to prepare a 45 wt% gum arabic solution, then raising the temperature to 85° C., keeping the temperature for 1 hour, and then cooling the temperature to 55° C. to obtain the pretreated gum arabic solution;

[0082] The degree of substitution DS of the carboxymethyl starch is greater than 0.2;

[0083] The mass ratio of the pretreated starch slurry, the pretreated gum arabic solution and the carboxymethyl starch is 100:8:5.

[0084] (5) Hydrolysis and saccharification: The pH of the pre-swollen starch slurry was adjusted to 4.5 with a 0.15 mol / L hydrochloric acid solution, and raw amylase was added to the pre-swollen starch slurry. The reaction was carried out at a temperature of 55°C for 5 hours to obtain a glucose solution.

[0085] The added amount of the raw amylase is 80 U / g.

[0086] (6) Filtration: Reduce the temperature of the glucose solution to 45°C, add activated carbon for decolorization and filtration, and then use a membrane filtration system to filter and remove impurities from the glucose solution to obtain a permeate.

[0087] (7) Desalination: The permeate is loaded into an ion exchange column for desalination and purification to obtain purified sugar solution.

[0088] (8) Concentration: The purified sugar solution is concentrated by vacuum concentration at 130°C to obtain glucose crystals.

[0089] (9) Drying: Dry the glucose crystals at 60°C for 1 hour, and then crush and sieve to obtain the finished glucose product.

[0090] Comparative Example 1

[0091] Comparative Example 1 adopts the method for preparing glucose from starch described in Example 2, except that the addition of transferglucosidase is omitted in the pretreatment step, and the remaining steps are the same.

[0092] Comparative Example 2

[0093] Comparative Example 2 adopts the method for preparing glucose from starch described in Example 2, except that the pre-expansion treatment step is omitted, and the pre-treated starch slurry is used instead of the pre-expansion starch slurry in the hydrolysis saccharification step, and the remaining steps are the same.

[0094] Comparative Example 3

[0095] Comparative Example 3 adopts the method for preparing glucose from starch described in Example 2, except that in the pre-expansion treatment step, the addition of the pre-treated gum arabic solution and carboxymethyl starch is omitted, and the remaining steps are the same.

[0096] Test Example 1

[0097] For the methods for preparing glucose from starch in Examples 1-3 and Comparative Examples 1-3, the glucose yield and the glucose value (DE value) were measured respectively, wherein the calculation formula for the glucose yield is:

[0098]

[0099] Where: Purity of finished glucose product = sample absorbance / standard absorbance;

[0100] The sample is an aqueous solution of the finished glucose prepared in the examples and comparative examples dissolved in water, and the concentration of the finished glucose in the sample is consistent with the concentration of glucose in the standard solution.

[0101] Determination of glucose value (DE value): Use DNS (dinitrosalicylic acid) method to measure the reducing ability of the hydrolysis product, that is, the glucose value (DE value) of the product, and calculate the reducing sugar content according to the standard curve. The calculation formula of DE value is:

[0102]

[0103] The test results are shown in Table 1.

[0104] Table 1 Glucose yield and glucose value (DE value)

[0105]

[0106] As shown in Table 1, the glucose yields obtained by the methods of Examples 1-3 were 97.8-98.4%, and the glucose values ​​(DE values) were 96.2-96.6%. Compared with Example 2, the glucose yields and glucose values ​​of Comparative Examples 1-3 decreased to varying degrees.

[0107] The present invention pretreats starch slurry by using α-1,4-glucose hydrolase and transfer glucosidase to reduce the main chain length of starch and increase the branching degree of starch. Due to the increase in the branching degree, the amorphous region gradually occupies a dominant position, and the average chain length also decreases accordingly, so that starch molecules can form a network structure during pre-swelling treatment, which is beneficial for the contact between the enzyme and the starch molecules, so that the enzyme can better act on the glycosidic bonds on the starch chain, and the starch hydrolysis rate is improved, thereby improving the glucose yield and the glucose value.

[0108] After starch granules are treated at 58-62°C for 30-40 minutes, the raw starch granules can be properly expanded. The expanded starch granules have a higher affinity for raw amylase, which makes it easier for raw amylase to attack the surface and the inside of the starch granules at the same time. The enzyme and starch can react more fully, reducing the viscosity of the starch paste, accelerating the enzymatic hydrolysis rate, and facilitating the enzymatic hydrolysis reaction. The pretreated gum arabic added during the pre-expansion treatment has a highly branched structure and can form a complex with starch granules, thereby changing the structure of starch granules. By changing the structure of starch granules, raw amylase can more easily contact starch molecules, thereby increasing the accessibility of the enzyme and promoting the hydrolysis reaction. On the other hand, gum arabic forms a hydration film on the surface of starch granules to prevent the pre-expanded starch molecules from interpenetrating with each other to form large starch groups, which hinder the contact reaction between the enzyme and the starch molecules. The heating treatment of gum arabic can inactivate the oxidase and peroxidase contained in the gum arabic, reducing their interference with the hydrolysis of starch by raw amylase; the carboxymethyl starch added together with the pretreated gum arabic has a negative charge, which makes a certain charge repulsion between the carboxymethyl starch molecules. This charge repulsion helps to disperse the starch molecules in the aqueous solution, reduces the agglomeration and entanglement between the starch molecules, and makes it easier for the raw amylase to contact the starch molecules.

[0109] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing glucose from starch, characterized in that: The method for preparing glucose from starch comprises the following steps: slurry adjustment, ultrasonic treatment, pretreatment, pre-expansion treatment, hydrolysis and saccharification, filtration, desalination, concentration, and drying; The pretreatment method comprises adding calcium chloride to the starch slurry after ultrasonic treatment, adjusting the pH of the slurry to 4.5-5, stirring and balancing for 20-30 minutes, adding α-1,4-glucose hydrolase, reacting at 50-55° C. for 2-3 hours, adjusting the pH of the slurry to 12-14, standing for 10-15 minutes to inactivate the enzyme, stirring and balancing for 20-30 minutes, adjusting the pH to 4.8-5.2, adding transglucosidase, stirring and reacting at 50-55° C. and 200-300 rpm for 5-8 hours, adjusting the pH to 12-14, standing for 10-15 minutes to inactivate the enzyme, and then adjusting the pH to 7-8 to obtain a pretreated starch slurry; The pre-expansion treatment method comprises first adding a pre-treated gum arabic solution and carboxymethyl starch to a pre-treated starch slurry, stirring at a speed of 600-800 rpm for 20-30 minutes to mix evenly, then heating to 58-62° C. and maintaining the temperature for 30-40 minutes to pre-expand the starch particles to obtain a pre-expanded starch slurry; The preparation method of the pretreated gum arabic solution is as follows: dissolving gum arabic in water at 50-55° C. to prepare a 40-45wt% gum arabic solution, then raising the temperature to 80-85° C., keeping the temperature for 1-1.5 hours, and then cooling the temperature to 50-55° C. to obtain the pretreated gum arabic solution; The degree of substitution DS of the carboxymethyl starch is greater than 0.2; The hydrolysis saccharification method comprises adjusting the pH of the pre-swollen starch slurry to 4.0-4.5, adding raw amylase to the pre-swollen starch slurry, and reacting at a temperature of 50-55° C. for 5-6 hours to obtain a glucose solution.

2. A method for preparing glucose from starch according to claim 1, characterized in that: The ultrasonic treatment method comprises the following steps: subjecting the starch slurry to ultrasonic treatment at a frequency of 20-22 KHz for 15-20 min, and then subjecting the starch slurry to ultrasonic treatment at a frequency of 28-30 KHz for 15-20 min, to obtain the starch slurry after ultrasonic treatment.

3. A method for preparing glucose from starch according to claim 1, characterized in that: In the pretreatment step, the amount of calcium chloride added is 200-250 mg / L; The addition amount of the α-1,4-glucose hydrolase is 40-50 U / g; The added amount of the transglucosidase is 200-300 U / g.

4. A method for preparing glucose from starch according to claim 1, characterized in that: In the pre-expansion treatment step, the mass ratio of the pre-treated starch slurry, the pre-treated gum arabic solution, and the carboxymethyl starch is 100:6-8:3-5.

5. A method for preparing glucose from starch according to claim 1, characterized in that: In the hydrolysis and saccharification step, the amount of raw amylase added is 60-80 U / g.

6. A method for preparing glucose from starch according to claim 1, characterized in that: The slurry adjustment method comprises mixing corn starch and water evenly to obtain starch slurry; the mass concentration of the starch slurry is 20-30%.

7. A method for preparing glucose from starch according to claim 1, characterized in that: The filtering method comprises the following steps: lowering the temperature of the glucose solution to 40-45° C., adding activated carbon for decolorization, filtering, and then filtering and removing impurities from the glucose solution using a membrane filtration system to obtain a permeate.

8. A method for preparing glucose from starch according to claim 1, characterized in that: The desalination method is to put the permeate into an ion exchange column for desalination, purification and refining to obtain a purified sugar solution.

9. A method for preparing glucose from starch according to claim 1, characterized in that: The concentration method is to purify the sugar solution at 120-130° C. by vacuum concentration to obtain glucose crystals.

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