Method for jointly preparing resistant starch and starch sugar

Abstract

The invention belongs to the technical field of food processing, and particularly relates to a method for jointly preparing resistant starch and starch sugar, which comprises the following steps: (1) mixing corn starch with water to prepare starch milk, adjusting the pH value of the starch milk, and heating and gelatinizing to obtain gelatinized liquid; (2) cooling the gelatinized liquid, performing enzyme debranching treatment, and performing enzyme deactivation and cooling to obtain enzymatic hydrolysate; (3) performing dynamic membrane separation on the enzymatic hydrolysate to obtain an extract and an extracting solution; and (4) treating the extract to prepare resistant starch, adjusting the pH value of the extracting solution, performing enzymolysis, and concentrating to obtain starch sugar. Starch chains below DP12 are effectively separated, the content of resistant starch reaches 60% or above, the crystallinity and the short-range order degree are both higher than those of resistant starch which is not subjected to membrane filtration, and the content of glucose in starch sugar reaches 90% or above. And the preparation process is simple, low in production energy consumption and convenient for industrial popularization and application.

Description

Technical Field

[0001] The invention belongs to the technical field of food processing, and in particular relates to a method for jointly preparing resistant starch and starch sugar. Background Art

[0002] Corn starch is a deep-processed product of corn. At present, the production capacity of corn starch is seriously oversupplied, and the high-value processing of starch is particularly important. Corn resistant starch is a high-value product of corn starch. Resistant starch refers to resistant starch that cannot be digested and absorbed by the small intestine, but can be fermented into short-chain fatty acids by microorganisms in the colon. It has the effects of inhibiting the increase in postprandial blood sugar, lowering blood lipids, and promoting the proliferation of intestinal probiotics. Type 3 resistant starch refers to aged starch, which refers to resistant starch prepared by decomposing starch into short chains of α-glucan and then controlling crystallization. Studies have shown that low degree of polymerization (DP) starch chains are not only easily digested, but also can hinder the regeneration of resistant starch to form stable crystals, thereby reducing the content of resistant starch (RS).

[0003] At present, extrusion, microwaves, ultrasound and other means are used to decompose low-DP starch chains or inhibit the regeneration of DP starch chains, but these methods consume a lot of energy. For example, in Chinese Patent Application No. 2023101566186, extrusion combined with heat-resistant α-amylase is used to decompose easily digestible starch to obtain resistant starch. However, this method is only suitable for high-amylose starch as raw material, while other starches are easily decomposed into glucose by heat-resistant α-amylase. For another example, in Chinese Patent Application No. 202410949673.5, a temperature above 170°C is used to prepare high-content resistant starch, but it is difficult for ordinary equipment to achieve a high temperature of 170°C.

[0004] Membrane separation technology is widely used in separating saccharification liquid to produce starch sugar. However, there are few reports on using membrane separation technology to separate enzymatic hydrolysate to produce resistant starch. This is because most saccharification liquids are small molecules that can be filtered by general membrane pore size and conditions, while resistant starch has a large molecular structure. In addition, the enzymatic hydrolysate used to prepare resistant starch is very easy to anneal at room temperature, forming recrystallization and unable to pass through membrane filtration devices. Summary of the invention

[0005] The purpose of the present invention is to provide a method for jointly preparing resistant starch and starch sugar, thereby overcoming the shortcomings of the prior art, utilizing a dynamic membrane separation method instead of an enzymatic decomposition method to separate easily digestible low-DP starch molecular chains, and having high controllability, high resistant starch content and yield, and low production cost; at the same time, the low-DP starch molecular chains can be used to prepare starch sugar, and compared with the traditional process for preparing starch sugar using starch as raw material, the liquefaction step and the amount of saccharifying enzyme used and the enzymatic hydrolysis time are reduced.

[0006] In order to achieve the above object, the technical solution of the present invention is:

[0007] A method for jointly preparing resistant starch and starch sugar comprises the following steps:

[0008] (1) mixing corn starch and water to prepare starch milk, adjusting the pH of the starch milk, and then heating and gelatinizing the mixture to obtain a gelatinized liquid;

[0009] (2) After the gelatinization liquid is cooled, an enzyme debranching treatment is performed to inactivate the enzyme and cool the liquid to obtain an enzymatic hydrolyzate;

[0010] (3) subjecting the enzymatic hydrolysate to dynamic membrane separation to obtain an extract and an extract;

[0011] (4) The extract is processed to produce resistant starch, and the extract is adjusted in pH, followed by enzymatic hydrolysis and concentration to obtain starch sugar.

[0012] In some other embodiments, the corn starch and water are mixed in a ratio of 1 g: (5-20) ml; preferably, the corn starch and water are mixed in a ratio of 1 g: 10 ml;

[0013] The pH is 4-5; preferably, the pH is 4.5;

[0014] The heating gelatinization conditions are: heating temperature is 110-130°C, heating time is 15-30min;

[0015] Preferably, the heating gelatinization conditions are: heating temperature is 121° C., and heating time is 20 min.

[0016] In some other embodiments, in step (2), the gelatinized liquid is cooled to a temperature of 50-70° C.; preferably, the gelatinized liquid is cooled to a temperature of 60° C.;

[0017] The enzymatic debranching treatment is firstly treated with pullulanase and then treated with isoamylase.

[0018] In some other embodiments, in step (2), the pullulanase treatment conditions are: the addition amount of pullulanase is 5-100 U / g, the temperature is 50-60° C., the time is 1-5 h, and the enzyme inactivation temperature is 80-90° C.;

[0019] Preferably, the pullulanase treatment conditions are: the addition amount of pullulanase is 5 U / g, the temperature is 60° C., the time is 3 h, and the enzyme inactivation temperature is 85° C.;

[0020] The isoamylase treatment conditions are as follows: the pH is adjusted to 4-5, the amount of isoamylase added is 0-0.5 U / g, the temperature is 45-55°C, the time is 20-30h, and the enzyme inactivation temperature is 80-90°C;

[0021] Preferably, the isoamylase treatment conditions are: the adjusted pH is 5, the amount of isoamylase added is 0.5 U / g, the temperature is 50° C., the time is 24 h, and the enzyme inactivation temperature is 85° C.

[0022] In some other embodiments, in step (3), the dynamic membrane separation is: the enzymatic hydrolysate and water are respectively introduced into the organic membrane separation jacket material tank at a certain flow rate for continuous dynamic countercurrent extraction until the Brix at the water outlet is 0-0.4%.

[0023] In some other embodiments, in step (3), the conditions for dynamic membrane separation are: the pore size of the organic membrane is 1000-3500Da, the temperature is 25-60°C, the pressure is 0.12-0.5Mpa, the flow rate of the enzymatic solution is 30-50ml / min, and the flow rate of water is 20-150ml / min.

[0024] Preferably, the conditions for the dynamic membrane separation are: the pore size of the organic membrane is 2000Da, the temperature is 50°C, the pressure is 0.4Mpa, the flow rate of the enzymatic solution is 30ml / min, and the flow rate of water is 100ml / min.

[0025] In some other embodiments, in step (3), the extract is an enzymatic hydrolyzate containing starch chains with a DP of more than 12; the extract is an enzymatic hydrolyzate containing starch chains with a DP of less than 12.

[0026] In some other embodiments, in step (4), the extract is treated under the following conditions: regeneration at 4-10°C for 12-30h to obtain a precipitate, drying at 40-50°C, and grinding;

[0027] Preferably, the extract is processed under the following conditions: regeneration at 4°C for 24 hours to obtain a precipitate, drying at 50°C, and grinding.

[0028] In some other embodiments, in step (4), the pH of the extract is adjusted to 4-5, and the conditions for the enzymatic hydrolysis are: the added enzyme is amyloglucosidase, the added amount is 80-120U / g, the temperature is 45-55°C, and the time is 12-30h; the concentration temperature is 75-90°C;

[0029] Preferably, the pH of the extract is adjusted to 5, and the conditions for the enzymatic hydrolysis are: the addition amount is 120 U / g, the temperature is 50° C., and the time is 24 h; the concentration temperature is 85° C.

[0030] In some other embodiments, the content of the resistant starch is greater than 60%; the content of glucose in the starch sugar is greater than 90%.

[0031] Beneficial effects of the present invention:

[0032] (1) The present invention adopts the dynamic membrane filtration method for the first time to achieve efficient separation of resistant starch, and at the same time, amyloglucosidase is added to the extract to prepare starch sugar, thereby achieving the combined preparation of resistant starch and starch sugar.

[0033] (2) The present invention can effectively separate starch chains below DP12 by optimizing the dynamic membrane filtration process, and the resistant starch content reaches more than 60%, and the crystallinity and short-range order are higher than those of the resistant starch that has not been membrane-filtered. The resistant starch particles that have been membrane-filtered are irregular in shape, but can form complete particles, and the average particle size is larger than that of the resistant starch that has not been membrane-filtered. The resistant starch that has not been membrane-filtered cannot form complete particles. The glucose content in the starch sugar reaches more than 90%.

[0034] (3) The preparation process of the present invention is simple, the production energy consumption is low, and it is easy to promote and apply industrialization. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0036] Figure 1 The SEM images of the resistant starch in the embodiments of the present invention, wherein (a) is resistant starch without film coating, and (b) is resistant starch with film coating;

[0037] Figure 2 1 is a particle size distribution diagram of the resistant starch in the examples of the present invention, wherein (a) is resistant starch that has not been film-coated, and (b) is resistant starch that has been film-coated. DETAILED DESCRIPTION

[0038] Example 1

[0039] A method for jointly preparing resistant starch and starch sugar comprises the following steps:

[0040] Corn starch and water were mixed in a mass ratio of 1:10 to prepare starch milk, and the starch milk was placed in a fermentation tank. The pH of the starch milk was adjusted to 4.5 with a sodium acetate buffer solution of 0.1 mol / L pH = 3.8, and heated to 127°C for 10 minutes to make it completely gelatinized. The gelatinized starch milk was cooled to 60°C, and pullulanase was added at an addition amount of 5U / g, and reacted at 60°C for 3h; after the reaction, the enzyme was inactivated at 85°C for 10min; after the enzyme was inactivated, it was cooled to 50°C, the pH was adjusted to 5, and isoamylase was added at an addition amount of 0.5U / g, and the reaction was oscillated at 50°C for 24h; after the reaction, the enzyme was inactivated at 90°C for 10min, and the enzyme was cooled to 50°C to obtain the enzymolyzate.

[0041] Add the enzymatic hydrolysate and water into the organic membrane separation jacket material tank, set the temperature of the material pipe to 50°C, the enzymatic hydrolysate injection rate to 30ml / min, the 50°C water supplement liquid injection rate to 100ml / min, the pressure in the organic membrane separation jacket material tank to 0.40MPa, the temperature of the organic membrane outer layer to 50°C, the organic membrane to select a pore size of 2000Da, the enzymatic hydrolysate concentrate to be circulated and filtered until the outlet of the enzymatic hydrolysate clear liquid is detected by a saccharimeter to be 0% Brix, collect the extract, and recover all the remaining extracts in the material tank.

[0042] The extract is placed at 4°C for 24 hours, the supernatant is slowly poured out (mixed with the membrane filtered extract, collectively referred to as the extract), the precipitate is dried at 45°C, and ground to obtain the resistant starch.

[0043] The pH of the extract was adjusted to 5 with 0.1 mol / L citric acid, 100 U / g amyloglucosidase was added, and the mixture was reacted at 50°C for 24 h; the mixture was concentrated by rotary evaporation at 85°C to obtain starch sugar.

[0044] During the experiment, the effects of the amount of pullulanase and isoamylase added, organic membrane separation, the pore size of the organic membrane, the organic membrane separation temperature and the organic membrane separation pressure on the resistant starch content and yield in the enzymatic hydrolyzate were studied. Among them, the determination methods of resistant starch content, recovery rate and amylose content are as follows:

[0045] The resistant starch content was determined using the megazyme resistant starch kit (according to AOAC 2002.02).

[0046] Resistant starch yield = m1 / m0×100%, m1 is the mass of resistant starch; m0 is the mass of native starch. It was determined using the Megazyme amylose detection kit.

[0047] The glucose content in starch sugar was determined using the Megazyme D-glucose detection kit. Starch sugar yield = m2 / m0*100%, where m2 is the mass of glucose in starch sugar.

[0048] (1) Effect of pullulanase and isoamylase addition on resistant starch content and yield (without film treatment)

[0049] The effects of the addition of pullulanase and isoamylase on the content and yield of resistant starch (without film) were studied, as shown in Table 1. Since isoamylase has higher specificity than pullulanase, but is too expensive, more pullulanase is used as much as possible. It can be seen from Table 1 that excessive pullulanase content will lead to reduced resistant starch content and yield. This is because excessive pullulanase will break down starch chains into glucose; if the isoamylase content is too low, the cutting efficiency of amylopectin will be reduced, resulting in low resistant starch content. Therefore, the resistant starch content prepared by using a combination of 5U / g pullulanase and 0.5U / g isoamylase is as high as 23.33%, and the yield is 91.50%.

[0050] Table 1 Effect of pullulanase and isoamylase addition on resistant starch content and yield (without film)

[0051] Pullulanase U / g,3h Isoamylase U / g, 24h Resistant starch content% Yield % 5 0 9.48 90.20 5 0.1 11.81 88.98 5 0.25 21.02 89.52 5 0.5 23.33 91.50 10 0.5 19.94 92.05 50 0.5 15.54 57.06 100 0.5 11.35 44.68

[0052] (2) Organic membrane separation and the effect of the pore size of the organic membrane on the separation of enzymatic hydrolysates

[0053] The separation effect of organic membrane separation and the pore size of the organic membrane on the enzymatic hydrolysate was studied. The starch emulsion was first treated with a combination of 5U / g pullulanase and 0.5U / g isoamylase to obtain an enzymatic hydrolysate. The content and yield of resistant starch obtained by membrane separation before and after the enzymatic hydrolysate was separated and by membrane separation with different pore sizes were measured. The results are shown in Table 2. It can be seen from Table 2 that this is because if the organic membrane separation is not performed (not through the membrane), the low DP starch molecular chain increases the non-resistant starch content and hinders the formation of resistant starch. If the pore size of the organic membrane is too small, the separation degree of the low DP starch molecular chain is insufficient, and the effect of improving the resistant starch content is poor. If the pore size is too large, the useful molecular chain will be separated out, resulting in a low yield of resistant starch. After the solid is filtered through a 2000Da membrane, the resistant starch content and yield are the best.

[0054] Table 2 Content and yield of resistant starch obtained before and after organic membrane separation and membrane separation with different pore sizes

[0055] Resistant starch content% Yield % Not through the membrane 22.84 81.56 1000Da 47.05 55.52 2000Da 62.84 53.20 3500Da 63.2 34.32

[0056] (3) Effect of organic membrane separation temperature on the separation of enzymatic hydrolysate

[0057] The effect of organic membrane separation temperature on the resistant starch in the enzymatic hydrolysate and its yield was studied as shown in Table 3. It can be seen from Table 3 that when filtering at 25°C, the membrane is blocked. This is because too low a temperature will cause the starch enzymatic hydrolysate to anneal and form resistant starch recrystallization. Too high a temperature will be destructive to the organic membrane, destroying the membrane pore size and making the filtration process uncontrollable. Therefore, the resistant starch content and yield are optimal when the organic membrane separation temperature is 50°C.

[0058] Table 3 Content and yield of resistant starch obtained by organic membrane separation temperature

[0059] Temperature / ℃ Resistant starch content% Yield % 25(Room temperature) 30.51 12.28 50 64.20 50.71 60 55.92 22.24

[0060] (4) Separation effect of organic membrane separation pressure on enzymatic hydrolysate

[0061] The pressure of organic membrane separation directly affects the water inflow rate of the clean water replenisher, and then affects the overall amount of water added. The study found that when the pressure is 0.12, the clear liquid flow rate is 20ml / min, and the amount of water added after the end is 4.25 times that of the original liquid. When the pressure is 0.4, the clear liquid flow rate is 100ml / min, and the amount of water added after the end is 2.45 times that of the original liquid. When the pressure is 0.5, the clear flow rate is about 150ml / min, and the amount of water added after the end is 4 times that of the original liquid.

[0062] By adjusting the organic membrane separation pressure, it was found that the pressure had little effect on the yield and recovery rate of resistant starch. After debugging, a pressure of 0.4 was the most suitable condition for use.

[0063] Based on the above research, the optimal conditions for the content and yield of resistant starch are determined as follows:

[0064] When 5U / g pullulanase plus 0.5U / g isoamylase, 2000Da membrane filtration, organic membrane separation temperature is 50℃, pressure is 0.4, the clear liquid flow rate is 100ml / min.

[0065] Performance Testing:

[0066] (1) The quality of resistant starch prepared using the optimal combination of conditions is determined as follows

[0067] Table 4 shows the resistant starch content, yield, amylose content, starch sugar yield and glucose content. It can be seen from Table 4 that the resistant starch content and starch sugar yield are increased after the enzymatic hydrolyzate is separated by organic membrane. This is because pullulanase and isoamylase cut off the side branches of amylopectin, and the cut side branches can become short amylose. Therefore, the amylose content reaches more than 50% after enzymatic hydrolysis, and the low DP starch molecular chain and starch sugar are separated after passing through the membrane (this part is treated with amyloglucosidase to obtain starch sugar), which reduces the amylose content in the resistant starch that has passed through the membrane. In addition, after the low DP starch molecular chain is filtered out, the recrystallization formed by the remaining starch chain is more complete, so the resistant starch content is higher.

[0068] Table 4 Resistant starch quality

[0069]

[0070]

[0071] (2) Crystallinity and short-range order of resistant starch

[0072] The crystallinity of resistant starch was determined by X-ray diffraction, and the short-range order of resistant starch was determined by Fourier transform infrared spectrometer as shown in Table 5. It can be seen from Table 5 that the crystallinity and short-range order of resistant starch were improved after the enzymatic hydrolysate was separated by organic membrane. This is because the low DP starch chain cannot be regenerated to form a double helix, and hinders other starch molecular chains from rearranging and crystallizing. Therefore, the crystallinity, short-range order (IR1047 / 1022) and double helix (IR995 / 1022) of resistant starch after membrane separation are higher.

[0073] Table 5 Crystallinity and order of resistant starch

[0074]

[0075] (3) Distribution of branch chain length of resistant starch

[0076] The distribution of resistant starch chain length was determined using the Thermo ICS5000 ion chromatography system and electrochemical detector as shown in Table 6. It can be seen from Table 6 that after the enzymatic hydrolysate was separated by an organic membrane, the membrane filtration method can effectively separate starch chains below DP12, and the resistant starch content reaches more than 60%. This is because the content of chain length DP>25 and above is proportional to the resistant starch content.

[0077] Table 6 Distribution of branch chain length of resistant starch

[0078]

[0079] (4) SEM and particle size distribution of resistant starch

[0080] The starch sample was evenly dispersed on the conductive glue, sprayed with gold, and the morphology of the sample was observed using a ThermoApreo scanning electron microscope at an accelerating voltage of 20 kV. Figure 1 As shown, (a) is unfilmed resistant starch, and (b) is filmed resistant starch. Figure 1 It can be seen that the resistant starch particles after membrane treatment are irregular in shape, but can form complete particles, while RS without membrane treatment cannot form complete particles. This is because too many small molecular starch chains cannot form double helices and arrange in recrystallized bodies, and hinder the regeneration of resistant starch.

[0081] The sample was dispersed in deionized water, stirred with ultrasound for 5 minutes, and then gradually added to the sample unit and adjusted to achieve appropriate light shielding. The starch particle size distribution was measured using a Malvern 2000 laser particle size analyzer, such as Figure 2 As shown, (a) is unfilmed resistant starch, and (b) is filmed resistant starch. Figure 2It can be seen that the average particle size of the film-coated resistant starch granules is larger than that of the unfilmed resistant starch granules. This is because the unfilmed resistant starch cannot form complete starch granules after retrogradation.

[0082] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. 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 jointly preparing resistant starch and starch sugar, characterized in that: The following steps are involved: (1) mixing corn starch and water to prepare starch milk, adjusting the pH of the starch milk, and then heating and gelatinizing the mixture to obtain a gelatinized liquid; (2) After the gelatinization liquid is cooled, an enzyme debranching treatment is performed to inactivate the enzyme and cool the liquid to obtain an enzymatic hydrolyzate; (3) subjecting the enzymatic hydrolysate to dynamic membrane separation to obtain an extract and an extract; (4) The extract is processed to produce resistant starch, and the extract is adjusted in pH, followed by enzymatic hydrolysis and concentration to obtain starch sugar.

2. The method for jointly preparing resistant starch and starch sugar according to claim 1, characterized in that: In step (1), the mixing ratio of corn starch to water is 1 g: (5-20) ml; preferably, the mixing ratio of corn starch to water is 1 g: 10 ml; The pH is 4-5; preferably, the pH is 4.5; The heating gelatinization conditions are: heating temperature is 110-130°C, heating time is 15-30min; Preferably, the heating gelatinization conditions are: heating temperature is 121° C., and heating time is 20 min.

3. The method for jointly preparing resistant starch and starch sugar according to claim 1, characterized in that: In step (2), the gelatinized liquid is cooled to a temperature of 50-70°C; preferably, the gelatinized liquid is cooled to a temperature of 60°C; The enzymatic debranching treatment is firstly treated with pullulanase and then treated with isoamylase.

4. The method for jointly preparing resistant starch and starch sugar according to claim 3, characterized in that: In step (2), the pullulanase treatment conditions are: the addition amount of pullulanase is 5-100 U / g, the temperature is 50-60° C., the time is 1-5 h, and the enzyme inactivation temperature is 80-90° C.; Preferably, the pullulanase treatment conditions are: the addition amount of pullulanase is 5 U / g, the temperature is 60° C., the time is 3 h, and the enzyme inactivation temperature is 85° C.; The isoamylase treatment conditions are as follows: the pH is adjusted to 4-5, the amount of isoamylase added is 0-0.5 U / g, the temperature is 45-55°C, the time is 20-30h, and the enzyme inactivation temperature is 80-90°C; Preferably, the isoamylase treatment conditions are: the adjusted pH is 5, the amount of isoamylase added is 0.5 U / g, the temperature is 50° C., the time is 24 h, and the enzyme inactivation temperature is 85° C.

5. The method for jointly preparing resistant starch and starch sugar according to claim 1, characterized in that: In step (3), the dynamic membrane separation is as follows: the enzymatic hydrolysate and water are respectively introduced into the organic membrane separation jacket material tank at a certain flow rate for continuous dynamic countercurrent extraction until the Brix at the water outlet is 0-0.4%.

6. The method for jointly preparing resistant starch and starch sugar according to claim 1, characterized in that: In step (3), the conditions for dynamic membrane separation are: the pore size of the organic membrane is 1000-3500Da, the temperature is 25-60°C, the pressure is 0.12-0.5Mpa, the flow rate of the enzymatic solution is 30-50ml / min, and the flow rate of water is 20-150ml / min. Preferably, the conditions for the dynamic membrane separation are: the pore size of the organic membrane is 2000Da, the temperature is 50°C, the pressure is 0.4Mpa, the flow rate of the enzymatic solution is 30ml / min, and the flow rate of water is 100ml / min.

7. The method for jointly preparing resistant starch and starch sugar according to claim 6, characterized in that: In step (3), the extract is an enzymatic hydrolyzate containing starch chains with a DP of more than 12; and the extract is an enzymatic hydrolyzate containing starch chains with a DP of less than 12.

8. The method for jointly preparing resistant starch and starch sugar according to claim 1, characterized in that: In step (4), the extract is treated under the following conditions: regeneration at 4-10°C for 12-30h to obtain a precipitate, drying at 40-50°C, and grinding; Preferably, the extract is processed under the following conditions: regeneration at 4°C for 24 hours to obtain a precipitate, drying at 50°C, and grinding.

9. The method for jointly preparing resistant starch and starch sugar according to claim 1, characterized in that: In step (4), the pH of the extract is adjusted to 4-5, and the conditions of the enzymatic hydrolysis are: the enzyme added is amyloglucosidase, the addition amount is 80-120U / g, the temperature is 45-55°C, and the time is 12-30h; the concentration temperature is 75-90°C; Preferably, the pH of the extract is adjusted to 5, and the conditions for the enzymatic hydrolysis are: the addition amount is 120 U / g, the temperature is 50° C., and the time is 24 h; the concentration temperature is 85° C.

10. The method for jointly preparing resistant starch and starch sugar according to claim 1, characterized in that: The content of the resistant starch reaches more than 60%; the content of glucose in the starch sugar reaches more than 90%.

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