Method for producing and processing a low glycemic value raw material

Abstract

The application discloses a production and processing method of low glycemic index raw materials, comprising: obtaining starch-containing raw materials; pretreating the raw materials to obtain pretreated materials; adding at least one amylase to the pretreated materials to perform a first enzymatic reaction to obtain a first enzymatic solution; adding pullulanase and beta-amylase to the first enzymatic solution to perform a second enzymatic reaction to obtain a second enzymatic solution rich in amylose fragments; and finally performing enzyme inactivation treatment on the second enzymatic solution, and performing recrystallization treatment by controlling a temperature gradient to rearrange the amylose fragments into resistant starch, thereby obtaining the low glycemic index raw materials. The method significantly improves the in-situ generation rate of resistant starch through the synergistic effect of a composite enzyme system and a variable-temperature recrystallization process, the obtained raw materials have a low glycemic index, are suitable for the needs of diabetic groups and blood sugar management, and meanwhile, good processing adaptability and taste are maintained.

Description

Technical Field

[0001] This invention relates to the field of food processing technology, and in particular to a method for producing and processing raw materials with low glycemic index. Background Technology

[0002] In existing technologies for producing low-glycemic index (GI) raw materials, a single enzymatic hydrolysis or physical modification method is typically used to reduce the GI of the raw materials. For example, some methods directly select high-amylose varieties or modify the starch structure through physical means such as cooking or extrusion, while others use α-amylase alone for partial hydrolysis to slow down digestion. These methods can reduce the GI value of the product to some extent, but they still have significant shortcomings.

[0003] However, existing technologies generally face two core problems: first, the in-situ formation rate of resistant starch is low, and simple enzymatic hydrolysis or physical treatment is insufficient to effectively induce starch molecule rearrangement to form a stable resistant starch structure, resulting in a limited decrease in the GI value of the final product; second, processing adaptability is poor, and the processed raw materials often have a rough texture, are difficult to shape, and exhibit large fluctuations in GI values ​​between different batches, making it difficult to meet the requirements of stable industrial production. These problems limit the widespread application of low-GI raw materials in the functional food field.

[0004] Therefore, there is an urgent need to develop a method for producing low-glycemic index raw materials that can significantly improve the efficiency of resistant starch formation while improving processing performance and product stability, in order to meet the urgent demand of people with diabetes and those under blood sugar management for high-quality low-GI food ingredients. Summary of the Invention

[0005] This application provides a method for producing and processing raw materials with low glycemic index, including the following steps: S1: Obtain starch-containing raw materials; S2: Pre-treat starch-containing raw materials to obtain pre-treated materials; S3: Add at least one amylase to the pretreated material to carry out the first enzymatic hydrolysis reaction and obtain the first enzymatic hydrolysate; S4: Add pullulanase and β-amylase to the first hydrolysate to carry out the second hydrolysis reaction and obtain the second hydrolysate rich in amylose fragments; S5: The second enzymatic hydrolysate is subjected to enzyme inactivation treatment, and recrystallization is carried out under controlled temperature gradient to rearrange the amylose fragments to form resistant starch, thereby obtaining raw materials with low glycemic value.

[0006] In some embodiments, the amylase used in the first enzymatic hydrolysis reaction is a thermostable α-amylase, the reaction temperature is 85-95°C, the reaction time is 10-30 minutes, and the enzyme addition amount is 5-15 U / g.

[0007] In some embodiments, the conditions for the second enzymatic hydrolysis reaction are: temperature 50-65℃, pH 4.0-5.5, and reaction time 2-6 hours; wherein the amount of pullulanase added is 10-50 U / g, and the amount of β-amylase added is 20-80 U / g.

[0008] In some embodiments, the recrystallization process includes: rapidly cooling the second enzymatic hydrolysate after enzyme inactivation to 35-45°C, then slowly cooling it to 4-10°C at a rate of 0.5-2°C / min, and allowing it to stand for 12-48 hours.

[0009] In some embodiments, during the recrystallization process, a shear force is applied to the second enzymatic hydrolysate. The shear force is provided by a homogenizer or a high-shear dispersing emulsifier at a speed of 3000-8000 rpm for a processing time of 5-15 minutes.

[0010] In some embodiments, before the first enzymatic hydrolysis reaction, a natural plant polyphenol compound is added to the pretreated material as a competitive inhibitor of amylase. The natural plant polyphenol compound is selected from at least one of green tea extract, grape seed extract, or apple peel extract, and the amount added is 0.5%-3% based on the dry weight of the starch-containing raw material.

[0011] In some embodiments, after recrystallization, a membrane separation purification step is further included: microfiltration of the recrystallized material using a ceramic membrane with a pore size of 0.1-0.5 μm, and collection of the permeate; then nanofiltration of the permeate using a nanofiltration membrane with a molecular weight cutoff of 1000-5000 Da, and collection of the retained liquid.

[0012] In some embodiments, after the membrane separation and purification step, a nutrient fortification and drying step is further included: a micronutrient premix containing chromium, zinc, B vitamins and dietary fiber is added to the retentate, and then spray drying is performed with an inlet air temperature of 160-180°C and an outlet air temperature of 70-90°C to obtain a low glycemic index raw material powder.

[0013] In some embodiments, the pretreatment includes: ultra-finely pulverizing the starch-containing raw material to make the average particle size D50 of the starch-containing raw material less than 50 μm, and mixing it with water to prepare a slurry with a solid content of 15%-25%.

[0014] In some embodiments, the starch-containing raw material is a grain or legume with a high amylose content, wherein the amylose content in the starch-containing raw material accounts for more than 40% of the dry basis total starch mass.

[0015] This invention provides a method for producing low glycemic index (GI) raw materials, comprising the following steps: obtaining starch-containing raw materials and pretreating them; adding at least one amylase to the pretreated materials for a first enzymatic hydrolysis reaction; adding pullulanase and β-amylase to the first hydrolysate for a second enzymatic hydrolysis reaction to obtain a second hydrolysate rich in amylose fragments; and finally, subjecting the second hydrolysate to enzyme inactivation treatment and recrystallizing it under controlled temperature gradient to rearrange the amylose fragments into resistant starch, thereby obtaining low GI raw materials. This method significantly improves the in-situ formation rate of resistant starch through the synergistic effect of a complex enzyme system in stages, resulting in a significantly reduced glycemic index in the obtained raw materials. It also exhibits good processing adaptability and a delicate texture, with stable and controllable GI values ​​between batches, meeting the industrial production needs of diabetic patients and those requiring blood sugar management for low GI food raw materials. Attached Figure Description

[0016] Figure 1 This is a flowchart of a method for producing and processing raw materials with low glycemic index, as proposed in this invention. Detailed Implementation

[0017] The following description is intended to disclose the invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art.

[0018] This application provides a method for producing and processing raw materials with low glycemic indexes, such as... Figure 1 As shown, it includes the following steps: S1: Obtain starch-containing raw materials; S2: Pre-treat starch-containing raw materials to obtain pre-treated materials; S3: Add at least one amylase to the pretreated material to carry out the first enzymatic hydrolysis reaction and obtain the first enzymatic hydrolysate; S4: Add pullulanase and β-amylase to the first hydrolysate to carry out the second hydrolysis reaction and obtain the second hydrolysate rich in amylose fragments; S5: The second enzymatic hydrolysate is subjected to enzyme inactivation treatment, and recrystallization is carried out under controlled temperature gradient to rearrange the amylose fragments to form resistant starch, thereby obtaining raw materials with low glycemic value.

[0019] This embodiment provides a method for producing and processing raw materials with low glycemic indexes, which will be described in detail below with reference to specific implementation methods.

[0020] First, obtain starch-containing raw materials. These can be grains or legumes with high amylose content, such as specialty corn, barley, and chickpeas. The reason for choosing these raw materials is that they naturally contain a high proportion of amylose. Amylose is less easily degraded by human digestive enzymes than amylopectin, forming the basis for low-GI ingredients. Furthermore, high-amylose raw materials are more likely to form stable resistant starch structures during subsequent enzymatic hydrolysis and recrystallization, laying the material foundation for the low glycemic index of the final product.

[0021] Next, the starch-containing raw materials undergo pretreatment to obtain pretreated materials. Pretreatment typically includes operations such as washing, soaking, pulverizing, and slurry preparation. For example, the raw materials are ultra-finely pulverized to control the average particle size below 50 micrometers, and then mixed with water to prepare a slurry with a solid content between 15% and 25%. The purpose of ultra-fine pulverization is to disrupt the cell wall structure of the raw materials and the dense coating layer of starch granules, increasing the specific surface area and thus improving the contact efficiency and uniformity of subsequent enzymatic hydrolysis reactions. Slurry preparation aims to create a suitable liquid-phase environment, allowing enzyme molecules to diffuse fully and bind to the substrate. This step eliminates the physical barriers inherent in the raw materials, providing optimal mass transfer conditions for the enzymatic hydrolysis reaction.

[0022] Then, at least one amylase is added to the pretreated material to carry out the first enzymatic hydrolysis reaction, obtaining the first hydrolysate. In this step, a heat-resistant α-amylase is typically selected, and the reaction is carried out at 85 to 95 degrees Celsius for 10 to 30 minutes, with the enzyme addition controlled at 5 to 15 units per gram of dry raw material. The main purpose of the first enzymatic hydrolysis reaction is to liquefy the starch, that is, to randomly cleave the α-1,4 glycosidic bonds within the starch molecules, breaking down long-chain starch into shorter-chain dextrins and oligosaccharides, thereby significantly reducing the viscosity of the slurry. After the viscosity is reduced, subsequent stirring, heat transfer, and enzyme molecule migration become smoother, creating conditions for the next step of precise debranching. Without this liquefaction step, the high-concentration starch slurry will be very viscous, making it difficult for pullulanase and β-amylase to uniformly contact all the substrates, resulting in low debranching efficiency.

[0023] Next, pullulanase and β-amylase were added to the first hydrolysate for a second enzymatic hydrolysis reaction, yielding a second hydrolysate rich in amylose fragments. The temperature of the second hydrolysis reaction was controlled at 50–65°C, the pH adjusted to 4.0–5.5, and the reaction time lasted 2–6 hours. The amount of pullulanase added was 10–50 units per gram of dry basis feedstock, and the amount of β-amylase added was 20–80 units. Pullulanase is a highly specific debranching enzyme that efficiently cleaves the α-1,6 glycosidic bonds at the branching points of amylopectin, releasing the originally highly branched amylopectin into a large number of linear amylose fragments. Simultaneously, β-amylase, starting from the non-reduced end of the starch chain, cleaves one maltose molecule every other glucose unit, further shortening the chain length and exposing more linear ends. The synergistic effect of these two enzymes produced two key effects: firstly, the concentration of free amylose fragments in the system was significantly increased; secondly, the chain length distribution of these fragments tended to be concentrated, which is beneficial for subsequent ordered rearrangement. The fundamental reason for this step is that only a sufficient number of linear fragments of appropriate length can tightly pack together to form a stable double helix structure during the subsequent recrystallization process, thereby transforming into resistant starch. If only the liquefaction process of the first enzymatic hydrolysis is used, the resulting fragments are mostly highly branched dextrins, which are almost unable to participate in rearrangement.

[0024] Finally, the second enzymatic hydrolysate is subjected to enzyme inactivation treatment, followed by recrystallization under controlled temperature gradient. This allows the amylose fragments to rearrange and form resistant starch, yielding a low-glycemic index raw material. Enzyme inactivation is typically achieved through heating, such as raising the hydrolysate to above 95 degrees Celsius and maintaining this temperature for 5 to 10 minutes to completely inactivate the enzyme protein and prevent further hydrolysis of the already formed amylose fragments during subsequent cooling. After enzyme inactivation, a temperature gradient control program is immediately initiated: the material is first rapidly cooled to 35 to 45 degrees Celsius, then slowly cooled to 4 to 10 degrees Celsius at a rate of 0.5 to 2 degrees Celsius per minute, and left to stand at this low temperature for 12 to 48 hours. The purpose of rapid cooling is to quickly bring the amylose molecules to a supersaturated state, providing the driving force for nucleation; while the subsequent slow cooling facilitates crystal growth, allowing the amylose fragments to stack in an orderly manner, forming a stable V-shaped or B-shaped crystalline structure, i.e., resistant starch. This resistant starch cannot be hydrolyzed by α-amylase in the human small intestine and therefore does not cause a rise in blood sugar. Controlling the temperature gradient is crucial for regulating crystal size and perfection: excessively rapid cooling produces numerous small and unstable crystal nuclei, resulting in low resistant starch yield; excessively slow cooling takes too long and may produce overly coarse crystals, affecting subsequent processing and texture. By precisely setting the gradient, high-yield resistant starch crystals with suitable particle size can be obtained in a shorter time.

[0025] In summary, this embodiment achieves efficient in-situ production of resistant starch through a three-step cascade process of liquefaction, debranching, and recrystallization. The first enzymatic hydrolysis overcomes the viscosity barrier, the second enzymatic hydrolysis creates an ample source of linear fragments, and temperature gradient recrystallization locks the linear fragments into resistant structures. Each step is interconnected and indispensable. Compared with existing technologies, this method does not require the addition of resistant starch or chemical cross-linking agents; it can convert ordinary starch raw materials into low-GI raw materials simply through enzyme and temperature control. The resulting product can have a resistant starch content of over 30% and a glycemic index below 55, while maintaining a delicate texture and good processing plasticity, making it highly suitable for large-scale industrial production.

[0026] In some embodiments, the amylase used in the first enzymatic hydrolysis reaction is a thermostable α-amylase, the reaction temperature is 85-95°C, the reaction time is 10-30 minutes, and the enzyme dosage is 5-15 U / g (based on the dry weight of the starch-containing raw material). In this case, "1 U" refers to the amount of enzyme required to catalyze the production of 1 μmol of reducing sugar (calculated as glucose) per minute under the above-mentioned test conditions. The test substrate is 1% w / v soluble starch, pH 6.0, 70°C, and the results are standardized as U / mL enzyme solution or U / mg protein. The feed amount is converted to U per gram of dry weight of starch-containing raw material (U / g dry weight). The first enzymatic hydrolysis reaction uses a thermostable α-amylase, and the reaction temperature is controlled between 85 and 95 degrees Celsius, the reaction time is set to 10 to 30 minutes, and the enzyme dosage is 5 to 15 units per gram of dry weight of starch-containing raw material. The selection of this set of parameters is based on a comprehensive consideration of the characteristics of different raw materials and equipment conditions, which will be illustrated by several specific examples below.

[0027] For example, when the raw material is ordinary corn starch, its gelatinization temperature is relatively high (approximately 72 to 78 degrees Celsius). Setting the reaction temperature at around 90 degrees Celsius ensures complete gelatinization of the starch granules, while the thermoresistant α-amylase maintains high activity at this temperature. In practice, the prepared slurry can be pumped into a jacketed reactor equipped with stirring and steam heating. After the temperature reaches 90 degrees Celsius, liquid thermoresistant α-amylase is added at a ratio of 10 units per kilogram of dry raw material, and the reaction is maintained for 20 minutes. At this point, the viscosity of the slurry will rapidly decrease from the initial several thousand centipoises to several hundred centipoises, indicating good liquefaction. Another example is for brown rice flour raw materials. Because brown rice contains more fiber and protein, the initial viscosity of the slurry is higher. Therefore, the reaction temperature is slightly increased to 93 degrees Celsius, the enzyme dosage is increased to 13 units per gram of dry base, and the reaction time is extended to 25 minutes to ensure complete liquefaction. Another example is the processing of wheat starch in a continuous jet cooker. The slurry is passed through a high-temperature steam jet head at a certain flow rate and instantly heated to 95 degrees Celsius. At the same time, enzyme solution is injected online, and the residence time is controlled at about 15 seconds. Then, it enters the holding tube and is kept warm for 10 minutes, which can also achieve the ideal liquefaction effect.

[0028] Using the above parameters for the first enzymatic hydrolysis reaction yielded significant beneficial effects. Firstly, the temperature range of 85 to 95 degrees Celsius ensured sufficient gelatinization and expansion of the starch, while also falling within the optimal range for the thermoresistant α-amylase, avoiding enzyme inactivation due to excessively high temperatures or incomplete gelatinization due to excessively low temperatures. Secondly, the reaction time of 10 to 30 minutes was sufficient to randomly cleave long-chain starch molecules into shorter dextrins and oligosaccharides, significantly reducing the viscosity of the slurry. This created excellent flowability and mass transfer conditions for the subsequent addition of pullulanase and β-amylase for the second enzymatic hydrolysis reaction; low viscosity meant that enzyme molecules could diffuse more quickly to all substrate surfaces, thus improving debranching efficiency. Furthermore, the enzyme addition of 5 to 15 units per gram of dry basis, as verified experimentally, ensured liquefaction while avoiding over-hydrolysis. Over-hydrolysis produces excessive small-molecule sugars, which would increase the difficulty of subsequent recrystallization and reduce the yield of resistant starch. In summary, this set of parameters achieves a precise balance between liquefaction depth and the requirements of subsequent processes, making it a crucial link in the entire process chain.

[0029] In some embodiments, the conditions for the second enzymatic hydrolysis reaction are: temperature 50-65°C, pH 4.0-5.5, and reaction time 2-6 hours; wherein the amount of pullulanase added is 10-50 U / g, and the amount of β-amylase added is 20-80 U / g. The second enzymatic hydrolysis reaction employs a specific process window, specifically maintaining the reaction temperature between 50 and 65°C, adjusting the pH to 4.0-5.5, controlling the reaction time to 2-6 hours, and simultaneously adding pullulanase at 10-50 units per gram of starch-containing raw material (dry basis) and β-amylase at 20-80 units. This combination of parameters stems from a trade-off between the optimal operating conditions of the two enzymes and consideration of substrate characteristics, which will be illustrated below with several practical examples.

[0030] The first example deals with waxy corn starch, which has a very high branching content and requires strong debranching capabilities. In practice, the slurry after the first enzymatic hydrolysis is cooled to 55 degrees Celsius, and the pH is adjusted to 4.8 with dilute hydrochloric acid. Then, enzyme solution is added at a ratio of 30 units of pullulanase and 50 units of β-amylase per kilogram of dry base material. The reaction is incubated for 4 hours with stirring. Samples are taken every half hour during the reaction to detect the reducing sugar content and iodine color change. When the blue color gradually weakens and stabilizes, debranching is basically complete. The second example deals with potato starch, which has a high viscosity after gelatinization and contains a small amount of phosphate groups, resulting in a slightly narrower pH tolerance range. Therefore, the reaction temperature is set to 60 degrees Celsius, the pH is adjusted to 5.2, the pullulanase dosage is reduced to 20 units per gram of dry base to avoid excessive debranching leading to overly short chains, while 60 units of β-amylase are used. The reaction time is extended to 5 hours to ensure sufficient linear fragment formation. The third example is an industrial continuous production scenario, in which materials are continuously pumped into a jacketed tubular reactor. The reaction zone temperature is maintained at 62 degrees Celsius and pH 5.0 through automatic control using an online pH meter and temperature sensor. The material stays in the tube for about 3 hours. Enzyme solution is continuously injected at the inlet in proportion, and viscosity changes are monitored in real time at the outlet to ensure consistent product quality.

[0031] Using the above conditions for the second enzymatic hydrolysis reaction yielded several beneficial effects. First, the temperature range of 50 to 65 degrees Celsius simultaneously met the activity requirements of pullulanase and β-amylase. The optimal temperature for pullulanase is typically 55 to 60 degrees Celsius, while that for β-amylase is 50 to 65 degrees Celsius. Both maintain high activity within this range, avoiding efficiency loss due to temperature mismatch. Second, the weakly acidic environment of pH 4.0 to 5.5 not only matches the closest pH range for both enzymes but also inhibits the growth of unwanted microorganisms without causing excessive acid hydrolysis of starch. Third, the reaction time of 2 to 6 hours is sufficient for pullulanase to fully cleave the α-1,6 glycosidic bonds of amylopectin, while β-amylase also has ample time to cleave maltose units from the non-reducing ends. The synergistic effect of both results in the optimal concentration and length distribution of amylose fragments in the system. If the time is too short, debranching will be incomplete, and the remaining branch points will hinder subsequent recrystallization; if the time is too long, β-amylase may over-degrade the amylose fragments into excessively short oligosaccharides, losing its rearrangement ability. Controlling the amount of enzyme added is equally crucial: a dose of pullulanase of 10 to 50 units per gram ensures that most branching points are opened, while a dose of β-amylase of 20 to 80 units per gram generates sufficient linear ends while preserving appropriate chain length, providing precursors of excellent quantity and quality for the subsequent formation of resistant starch. Overall, this set of parameters achieves a precise balance between debranching depth and fragment length, which is the core element determining the final yield of resistant starch in this process.

[0032] In some embodiments, the recrystallization process includes: rapidly cooling the enzyme-inactivated second enzymatic hydrolysate to 35-45°C, then slowly cooling it to 4-10°C at a rate of 0.5-2°C / min, and allowing it to stand for 12-48 hours. The recrystallization process employs a segmented temperature control strategy: first, rapidly cooling the enzyme-inactivated second enzymatic hydrolysate to 35-45°C, then slowly cooling it to 4-10°C at a rate of 0.5-2°C / min, and allowing it to stand at this low temperature for 12-48 hours. This process parameter design aims to guide the orderly aggregation of amylose fragments to form stable resistant starch crystals, which will be illustrated below through several specific implementation scenarios.

[0033] The first example involves processing chickpea starch hydrolysate on a small-scale laboratory basis. After enzyme inactivation, the beaker containing the hydrolysate was placed in an ice-water bath and rapidly stirred to lower the temperature from 95°C to 40°C within 5 minutes. The beaker was then transferred to a constant-temperature incubator, with a cooling program set to decrease the temperature by 1.5°C per hour, reaching 5°C after approximately 20 hours. It was then kept at 5°C for 24 hours, and the precipitate was removed and centrifuged. X-ray diffraction analysis showed typical B-type crystallization peaks, indicating a resistant starch content of 38%. The second example involves processing corn starch hydrolysate on a pilot-scale production line. After enzyme inactivation, the material was rapidly cooled to 42°C using a plate heat exchanger, then transferred to a jacketed crystallization tank. Circulating chilled water was circulated through the jacket, and the cooling rate was controlled by a PLC at 1°C per minute, reaching 4°C after approximately 38 minutes. The material was kept at 4°C for 36 hours, with the agitator activated every 6 hours to prevent clumping. The final product, after in vitro simulated digestion testing, showed a glycemic index of only 52. ​​The third example is a continuous crystallization process suitable for large-scale production. The enzyme-inactivated material is first rapidly cooled to 38 degrees Celsius in a quencher, then enters a series of crystallization towers connected in series. The outer walls of the towers are equipped with semiconductor cooling plates. By adjusting the current, the temperature inside the towers is distributed in an axial gradient. The material resides in the towers for approximately 18 hours, and the outlet temperature stabilizes at 6 degrees Celsius. The entire process requires no manual intervention and exhibits good batch-to-batch reproducibility.

[0034] The benefits of the above recrystallization process are multifaceted. The first step, rapid cooling to 35-45 degrees Celsius, triggers nucleation, causing amylose molecules to quickly reach a supersaturated state within this temperature range, forming numerous tiny nuclei and providing ample growth points for subsequent crystal growth. If the cooling rate is too slow or the starting temperature is too high, the number of nuclei is small and uneven, resulting in coarse crystals and low yield. The subsequent slow cooling to 4-10 degrees Celsius at a rate of 0.5-2 degrees Celsius per minute is crucial, allowing the nuclei to grow gradually in an orderly manner. The amylose fragments stack layer by layer along the crystal lattice, forming a highly ordered double helix structure—the true resistant starch crystal. Too rapid a cooling rate leads to increased crystal defects and decreased resistance to enzymatic hydrolysis; too slow a cooling rate is too time-consuming and detrimental to production efficiency. Finally, the product is left to stand at a low temperature of 4 to 10 degrees Celsius for 12 to 48 hours, which is equivalent to an annealing and ripening process. This allows the not-yet-fully-aligned molecular chains sufficient time to adjust their conformation, fill lattice gaps, and further improve crystallinity and thermal stability. Too short a standing time results in insufficient ripening and a low resistant starch content; too long a time leads to diminishing marginal benefits and increased energy consumption. Overall, this temperature-time combination achieves an optimal balance between nucleation density, crystal perfection, and production efficiency, resulting in a final product with a stable resistant starch content between 30% and 40%, a glycemic index below 55, and good thermal stability and processing adaptability.

[0035] In some embodiments, during the recrystallization process, a shear force is applied to the second enzymatic hydrolysate. This shear force is provided by a homogenizer or a high-shear dispersing emulsifier at a speed of 3000-8000 rpm for 5-15 minutes. To further optimize the crystalline morphology and product uniformity of the resistant starch, a shear force is applied to the second enzymatic hydrolysate during the recrystallization process. The shear force is provided by a homogenizer or a high-shear dispersing emulsifier at a speed controlled at 3000-8000 rpm for 5-15 minutes. The purpose of this operation is to introduce mechanical external force during the rearrangement of amylose molecules, breaking down local concentration gradients and temperature inhomogeneities, and promoting more uniform molecular participation in crystallization.

[0036] In practical applications, parameters can be flexibly adjusted according to different raw materials and equipment conditions. For example, when processing the second enzymatic hydrolysate from corn starch, after the recrystallization temperature is rapidly cooled to 40 degrees Celsius, a high-shear dispersing emulsifier is started and continuously processed at 6000 rpm for 10 minutes. At this time, the solution is in the early stage of nucleation, and the strong shearing action breaks up the amylose aggregates that are not yet fully dispersed in the solution, while generating a large number of uniform microbubbles and eddies, which greatly increases the frequency of molecular collisions and nucleation sites. Another example is the processing of chickpea starch enzymatic hydrolysate on a pilot production line. The enzyme-inactivated material is pumped into an online high-shear homogenizer, with the speed set at 4000 rpm. The material stays in the homogenizer for about 8 minutes and then directly enters the crystallizer for subsequent slow cooling. This online processing method avoids temperature fluctuations during the material transfer process and ensures process continuity. The third example is for high-viscosity barley raw materials. Due to the relatively high content of amylopectin, the second enzymatic hydrolysate still has a certain viscosity. In this case, the rotation speed is increased to 7500 rpm and the processing time is extended to 15 minutes to ensure that the shear force can penetrate the high-viscosity area, so that all linear segments can be fully exposed and participate in rearrangement.

[0037] During the recrystallization process, shear force is applied to the second enzymatic hydrolysate using a high-shear dispersing emulsifier or homogenizer. Specifically, after the enzyme-inactivated second enzymatic hydrolysate is rapidly cooled to 35-45 degrees Celsius, it is immediately pumped into the working chamber of the high-shear dispersing emulsifier. The rotor rotates at a high speed of 3000-8000 revolutions per minute, creating a narrow gap between the stator and rotor. Under the powerful centrifugal and shear forces, the material is forced through this gap, and droplets and particles are repeatedly torn and dispersed. The processing time is controlled between 5 and 15 minutes depending on the material volume and the required shear intensity. A circulating processing method can be adopted, where the material flows back from the emulsifier outlet to the inlet, passing through the shear zone multiple times until the desired dispersion effect and crystallization uniformity are achieved. For continuous production lines, the high-shear emulsifier can be installed on the pipeline between the crystallization tank and the cooling heat exchanger, allowing the material to undergo shear treatment in one pass before directly entering the subsequent slow cooling stage. Throughout the process, shear force disrupts the local aggregates formed by amylose molecules in the early stage of nucleation, forcing the molecular chains to disperse and align uniformly, thus providing a large number of uniform crystal nuclei for subsequent ordered recrystallization.

[0038] Applying shear force brings several significant benefits. First, shear force effectively breaks down the localized gel-like structure formed in the early stages of recrystallization, preventing the formation of large amorphous masses and ensuring that resistant starch crystal nuclei are evenly distributed in the liquid phase, resulting in a fine-sized, concentrated crystal population. Compared to static recrystallization, crystal size can be reduced by 30% to 50% under dynamic shear conditions, meaning the final product has a smoother texture and is free of gritty feel. Second, shear force promotes the extension and orientation of amylose molecular chains, making them more likely to align in parallel to form a double helix structure, thus improving the perfection of crystallization. Experiments show that under shear force of 3000 to 8000 rpm, the yield of resistant starch can be increased by 8 to 12 percentage points compared to static conditions, with a significant reduction in batch-to-batch standard deviation. Furthermore, shear force enhances heat transfer efficiency, resulting in a smaller temperature gradient throughout the crystallizer and avoiding uneven crystallization caused by localized overheating or undercooling. In summary, introducing shear force during recrystallization not only improves the low-GI performance and quality stability of the product, but also provides a reliable technical guarantee for the scale-up and continuous production of the process.

[0039] In some embodiments, prior to the first enzymatic hydrolysis reaction, a natural plant polyphenolic compound is added to the pretreated material as a competitive inhibitor of amylase. This natural plant polyphenolic compound is selected from at least one of green tea extract, grape seed extract, or apple peel extract, and the amount added is controlled between 0.5% and 3% based on the dry weight of the starch-containing raw material. The purpose of this step is to delay the hydrolysis rate in the initial stage of the enzymatic hydrolysis reaction through the reversible binding of polyphenol molecules to the active site of amylase, thereby creating more favorable kinetic conditions for subsequent linear fragment accumulation and rearrangement.

[0040] In practical applications, the source of polyphenols can be flexibly selected based on the characteristics of the raw materials and the target GI value. For example, when processing ordinary corn starch raw materials, commercially available green tea extract (tea polyphenol content ≥98%) is weighed at 1.5% of its dry weight, dissolved in a small amount of warm water (40℃), and then evenly sprayed into the pretreated material during the slurry preparation stage, stirred for 10 minutes to allow for full adsorption. Subsequently, heat-resistant α-amylase is added for the first enzymatic hydrolysis according to the conventional process. Another example is for highland barley raw materials, which contain a certain amount of phenolic substances. Grape seed extract (proanthocyanidin content ≥95%) is selected as a supplementary inhibitor, added at 2% of its dry weight, and directly mixed into the ultra-finely pulverized slurry, using high-speed shearing to ensure uniform dispersion. A third example is in industrial continuous production, where apple peel extract (rich in chlorogenic acid and phlorizin) is pre-prepared into a 10% aqueous solution, injected proportionally into the feed pipeline through a metering pump, so that the final addition reaches 0.8% of its dry weight. It then enters a static mixer for thorough mixing before entering the enzymatic hydrolysis reactor.

[0041] The beneficial effects of adding natural plant polyphenols are mainly reflected in three aspects. First, polyphenol molecules can competitively bind to the active sites of amylases (especially α-amylase), temporarily inhibiting their catalytic activity and changing the hydrolysis rate of the first enzymatic reaction from a rapid burst to a gradual process. This gentle liquefaction process avoids excessive local hydrolysis that produces a large amount of short-chain sugars, thus retaining more medium-length dextrins. These dextrins are more easily converted into linear fragments of suitable length by pullulanase and β-amylase in the subsequent second enzymatic hydrolysis. Second, polyphenols themselves have strong antioxidant activity, protecting amylose molecules from oxidative degradation during subsequent recrystallization and drying processes, maintaining their structural integrity, and indirectly improving the yield of resistant starch. Experimental data show that when the addition amount is 1% to 2%, the resistant starch content of the final product can be increased by an additional 5 to 8 percentage points. Furthermore, these natural polyphenols are derived from common food byproducts (such as grape seeds and apple peels), making them widely available and inexpensive. Adding them to products can also impart additional health benefits (such as scavenging free radicals and improving gut microbiota), aligning with the trend towards clean label and functional foods. It is important to note that the addition amount should not exceed 3%, otherwise, excessively high polyphenol concentrations may overly inhibit enzyme activity, leading to incomplete liquefaction and excessively high slurry viscosity, which in turn affects the normal operation of subsequent processes. Therefore, a range of 0.5% to 3% represents the optimal balance between inhibitory effects and processing feasibility.

[0042] In some embodiments, after recrystallization, a membrane separation purification step is further included: microfiltration of the recrystallized material using a ceramic membrane with a pore size of 0.1-0.5 μm, collecting the permeate; then nanofiltration of the permeate using a nanofiltration membrane with a molecular weight cutoff of 1000-5000 Da, collecting the retentate. The membrane separation purification step added after recrystallization further enhances the purity and low-GI characteristics of the product. Specifically, the recrystallized material is first microfiltered using a ceramic membrane with a pore size of 0.1 to 0.5 micrometers, collecting the permeate; then nanofiltration of the permeate using a nanofiltration membrane with a molecular weight cutoff of 1000 to 5000 Daltons, collecting the retentate. This combined membrane process can accurately separate large molecular weight active ingredients such as resistant starch and proteins from small molecular weight sugars, salts, and water, thereby obtaining high-purity, low-GI raw materials.

[0043] In practical applications, membrane parameters can be flexibly adjusted according to material characteristics and equipment conditions. For example, when processing recrystallized materials derived from corn starch, a tubular ceramic membrane module with a pore size of 0.2 micrometers is selected, and microfiltration is performed at a transmembrane pressure of 0.3 MPa. The feed solution temperature is maintained at 40 degrees Celsius to prevent the dissolution of resistant starch. During microfiltration, unreacted fibers, bacterial debris, and some large molecular weight colloids are retained, while resistant starch, proteins, and small molecule sugars pass through the membrane pores into the permeate with the aqueous phase. The collected permeate then enters a spiral-wound nanofiltration membrane system, with the membrane molecular weight cutoff set at 2000 Daltons and the operating pressure at 1.0 MPa. The nanofiltration membrane can effectively retain resistant starch and proteins with molecular weights greater than 2000, while smaller molecular weight glucose, maltose, and inorganic salts are discharged with the water, forming the permeate. The final collected retentate is a concentrate rich in resistant starch and protein. Another example involves chickpeas, a high-protein feed. To prevent the formation of a gel layer on the membrane surface, the pore size of the microfiltration membrane is adjusted to 0.45 micrometers, and a cross-flow filtration mode is employed, with the flow rate controlled at 2 meters per second to mitigate concentration polarization. The nanofiltration membrane has a molecular weight cutoff of 3000 Daltons to better retain the larger molecular weight globulins in chickpeas. A third example is a continuous production line where microfiltration and nanofiltration modules are arranged in series, with a buffer tank and online concentration detector in between. When the solid content of the retentate reaches 15%, the system automatically switches to the next batch of feed, achieving semi-continuous operation.

[0044] The membrane separation purification process offers several beneficial effects. First, ceramic microfiltration efficiently removes undissolved fibers, bacterial debris, and large molecular aggregates that may remain during recrystallization. These impurities, if left in the final product, would affect taste and storage stability. The pore size range of 0.1 to 0.5 micrometers effectively intercepts the vast majority of suspended particles while allowing resistant starch and protein to pass through, achieving initial purification. Second, nanofiltration plays a crucial purification role. Nanofiltration membranes with a molecular weight cutoff of 1000 to 5000 Daltons selectively retain resistant starch (typically with molecular weights of tens to hundreds of thousands) and protein, while allowing small sugar molecules (such as glucose and maltose, with molecular weights of 180 to 342) and monovalent salt ions to pass through. This significantly removes digestible small sugar molecules that can cause glycemic spikes, resulting in a substantial increase in the relative content of resistant starch. Experimental data shows that after nanofiltration, the proportion of resistant starch in the product can increase from approximately 30% to over 55%, while the total sugar content decreases to below 5%, and the glycemic index further decreases to below 45. Furthermore, the membrane separation process is carried out at room temperature or low temperature, avoiding the loss of heat-sensitive nutrients, while consuming far less energy than evaporation and concentration, making it suitable for industrial scale-up. The retentate can be directly used for subsequent spray drying or freeze drying to obtain a powder product with good flowability. Overall, this membrane separation purification step effectively complements the preceding enzymatic hydrolysis and recrystallization processes, ensuring the high purity, low sugar content, and excellent physiological efficacy of the final low-GI raw material.

[0045] In some embodiments, after the membrane separation and purification step, a nutrient fortification and drying step is further included: a micronutrient premix containing chromium, zinc, B vitamins, and dietary fiber is added to the retentate, followed by spray drying at an inlet air temperature of 160-180°C and an outlet air temperature of 70-90°C to obtain a low glycemic index (GI) raw material powder. The nutrient fortification and drying step is further added after the membrane separation and purification step. Specifically, a micronutrient premix containing chromium, zinc, B vitamins, and dietary fiber is added to the nanofiltration retentate, followed by spray drying at an inlet air temperature of 160-180°C and an outlet air temperature of 70-90°C to finally obtain a low GI raw material powder. The purpose of this step is to impart additional nutritional functions to the product while retaining its low GI characteristics, and to transform the liquid retentate into a powder form that is easy to store, transport, and use through spray drying.

[0046] In actual production, the composition and dosage of premixes can be flexibly adjusted according to the target population and product positioning. The first example is a formula specifically for diabetic patients, which adds 200 micrograms of chromium (in the form of chromium picolinate), 15 milligrams of zinc (in the form of zinc gluconate), 0.8 milligrams of vitamin B1, 1.0 milligrams of vitamin B6, 2.0 micrograms of vitamin B12, and 5 grams of inulin-type dietary fiber per 100 grams of retentate dry solids. These premixes are first dissolved in a small amount of retentate, then added back to the main retentate, stirred evenly, and then spray-dried. The inlet air temperature is set at 170 degrees Celsius, and the outlet air temperature is controlled at 80 degrees Celsius, resulting in a powder with a moisture content of less than 4% and good flowability. The second example is a product for weight management, where the amount of chromium added is appropriately reduced (150 micrograms), the proportion of dietary fiber is increased (8 grams per 100 grams of dry solids), and 0.5 milligrams of folic acid are added. The spray drying parameters were adjusted to an inlet air temperature of 165 degrees Celsius and an outlet air temperature of 75 degrees Celsius to obtain a slightly larger particle size and improve dispersibility during reconstitution. The third example is a general-purpose low-GI raw material, without added trace elements, with only 5% oat β-glucan added as a dietary fiber source. Spray drying was performed at an inlet air temperature of 175 degrees Celsius and an outlet air temperature of 85 degrees Celsius to improve drying efficiency and adapt to mass production.

[0047] The addition of micronutrient premixes and the use of specific spray-drying parameters bring multiple beneficial effects. First, chromium enhances insulin sensitivity, helping to stabilize postprandial blood sugar; zinc participates in insulin synthesis and secretion; B vitamins are key components of various coenzymes in glucose metabolism; and dietary fiber further slows gastric emptying and glucose absorption. These nutrients work synergistically with low-GI raw materials, resulting in a final product that not only has a slow glycemic index but also helps improve the body's overall blood sugar regulation. Second, the inlet air temperature of 160 to 180 degrees Celsius in spray drying is sufficient to evaporate moisture in a very short time. Simultaneously, because a dry crust quickly forms on the droplet surface, the internal temperature does not exceed the wet-bulb temperature (approximately 50 to 60 degrees Celsius), thus preserving heat-sensitive B vitamins and trace elements. The outlet air temperature of 70 to 90 degrees Celsius ensures that the product reaches the target moisture content without excessive heat causing discoloration or a burnt taste. Compared to freeze drying, spray drying is lower in cost, has higher production capacity, and is suitable for continuous industrial production. Furthermore, the retentate itself has already had most of the small-molecule sugars removed by nanofiltration, resulting in a high content of resistant starch and protein in the solids. The spray-dried powder exhibits low hygroscopicity, good storage stability, and retains excellent low-GI properties even after rehydration. By adjusting the inlet and outlet air temperatures, the particle size distribution and bulk density of the powder can be controlled to meet the needs of different downstream applications (such as tablets, granules, and baking premixes). Overall, this nutritional fortification and drying step transforms the low-GI raw materials obtained from the preceding multi-step processes into a commercially viable end product with added nutritional value, truly achieving a leap from laboratory technology to market application.

[0048] In some embodiments, the pretreatment includes: ultra-fine pulverizing the starch-containing raw material to reduce its average particle size D50 to less than 50 μm, and then mixing it with water to prepare a slurry with a solid content of 15%-25%. The pretreatment step employs a combination of ultra-fine pulverization and slurry preparation. Specifically, the starch-containing raw material is ultra-fine pulverized to reduce its average particle size D50 to less than 50 μm, and then mixed with water to prepare a slurry with a solid content of 15% to 25%. The purpose of this operation is to maximally disrupt the cell walls and dense structure of the starch granules through physical means, providing a large reaction interface and a uniform liquid phase environment for the subsequent enzymatic hydrolysis reaction.

[0049] In practical applications, appropriate pulverizing equipment and process parameters can be selected based on the hardness and moisture content of different raw materials. For example, when processing corn raw materials, the corn kernels are first coarsely pulverized to 20 mesh, and then fed into an airflow ultrafine pulverizer with a working pressure of 0.8 MPa and a grading speed of 3500 rpm. After one pulverization, a sample is taken for testing, and the laser particle size analyzer shows a D50 of 32 micrometers, which meets the requirements. Subsequently, the ultrafine powder is added to the mixing tank, and water is added at a dry powder to water mass ratio of 1:4, i.e., a solid content of 20%, and stirred for 30 minutes to form a uniform slurry. Another example is for highland barley raw materials. Due to its tough outer layer and high content of β-glucan, a vibratory mill is used for ultrafine pulverization with zirconia beads as the grinding media. The grinding time is 15 minutes, and the output D50 is 45 micrometers. When preparing the slurry, considering the water absorption and swelling properties of β-glucan, the solid content is adjusted to 18% to prevent the slurry from becoming too viscous. The third example involves processing chickpeas. Chickpeas have a high fat content, and direct grinding can easily cause clumping. Therefore, they are first degreased, and then a disc mill is used with a blade rotation speed of 6000 rpm and a screen aperture of 0.2 mm. The resulting density (D50) is 28 microns. The solids content is set at 22% during pulp preparation, and a small amount of sodium citrate is added as a dispersant to prevent protein aggregation.

[0050] Using ultrafine grinding to a D50 of less than 50 micrometers, combined with slurry preparation with a solid content of 15% to 25%, brings several beneficial effects. First, ultrafine grinding increases the specific surface area of ​​the raw material by tens or even hundreds of times, allowing subsequently added amylase to be more quickly adsorbed onto the starch granule surface, significantly increasing the enzymatic hydrolysis rate and shortening the reaction time by 20% to 30%. Simultaneously, because the cell walls are fully disrupted, the previously encapsulated starch molecules are completely exposed, avoiding incomplete local reactions caused by mass transfer resistance, thus improving the uniformity of enzymatic hydrolysis. Second, controlling the average particle size to below 50 micrometers effectively avoids the formation of unreacted nuclei in large particles during subsequent enzymatic hydrolysis due to internal heat and mass transfer lag, ensuring that every particle undergoes the same process conditions. The batch-to-batch coefficient of variation for the resistant starch content of the final product can be controlled within 5%. Furthermore, the solid content range of 15% to 25% has been repeatedly verified: below 15%, the slurry's water content is too high, significantly increasing energy consumption in subsequent enzymatic hydrolysis and drying processes; above 25%, the slurry viscosity is too high, making stirring and pumping difficult, and the small particles after ultrafine grinding are prone to secondary agglomeration. Therefore, this solid content range ensures good flowability and mass transfer efficiency while also taking into account economic efficiency. Overall, this pretreatment step lays a solid physical foundation for the entire low-GI raw material production process and is a prerequisite for the efficient and stable conduct of all subsequent biochemical reactions.

[0051] In some embodiments, the starch-containing raw material is a grain or legume with a high amylose content, wherein the amylose content in the starch-containing raw material accounts for more than 40% of the total dry-basis starch mass. The selection of grains or legumes with a high amylose content as the starch-containing raw material specifically requires that the amylose content in the raw material accounts for more than 40% of the total dry-basis starch mass. This selection is based on the fundamental structural differences between amylose and amylopectin: amylose is a linear molecule, which more easily forms resistant starch crystals through ordered hydrogen bonding during cooling, while the highly branched structure of amylopectin is not conducive to such ordered stacking. Therefore, the amylose content of the raw material directly determines the potential upper limit of resistant starch formation in subsequent processes.

[0052] In actual procurement and production, this indicator can be achieved by screening specific varieties or using specialized raw materials obtained through hybridization breeding. The first example is high-amylose corn starch. Commercially available high-amylose corn varieties have an amylose content of 50% to 70%. During procurement, suppliers are required to provide third-party testing reports confirming an amylose content of no less than 45%. After entering the factory, samples are taken from each batch for verification using the iodine colorimetric method. This raw material has a regular particle shape and few impurities, making it very suitable as a starting material for this method. The second example is barley, especially certain local varieties from Tibet, such as Zangqing 320, whose amylose content is typically between 42% and 48%. Before use, the barley needs to be dehulled and polished to remove the bran before grinding into powder. Because barley is also rich in β-glucan, it can play a certain thickening and protective role in subsequent enzymatic hydrolysis, which is beneficial for the formation of resistant starch. The third example is chickpeas, especially the Dishi type chickpea variety, whose amylose content is approximately 40% to 45%. Chickpeas also contain high levels of protein and dietary fiber, which act as a physical barrier during recrystallization, preventing excessive aggregation of amylose molecules and resulting in a more uniform crystal size distribution. When using chickpeas, the whole chickpeas are ultra-finely ground and used directly for soy milk preparation, eliminating the need for additional protein separation.

[0053] Using raw materials with an amylose content of over 40% yields significant benefits. Firstly, the high amylose content provides ample substrate for subsequent debranching and recrystallization. In the second enzymatic hydrolysis stage, the number of amylose fragments released after pullulanase cleaves the branching points of amylopectin is positively correlated with the amylose content of the raw material itself. If the amylose content of the raw material is below 40%, even after sufficient debranching, the total amount of usable amylose fragments in the system remains limited, making it difficult to achieve a resistant starch yield exceeding 25%. However, when the amylose content reaches over 40%, the resistant starch yield can easily reach 30% to 40%, or even higher. Secondly, high amylose raw materials exhibit better thermal stability and mechanical strength during recrystallization, resulting in resistant starch crystals with higher melting points that are less susceptible to damage during subsequent spray drying or baking applications, ensuring that the low-GI characteristics of the final product are maintained after processing. Furthermore, these raw materials typically also contain higher levels of resistant starch precursors and lower amylopectin proportions, resulting in a wider process window for enzymatic hydrolysis and recrystallization, greater tolerance to temperature and time fluctuations, and improved stability control for industrial production. From a cost perspective, although the price of high-amylose-content raw materials is slightly higher than that of ordinary raw materials, their high conversion efficiency may actually result in a lower overall cost per unit product. Therefore, setting the amylose content of raw materials at over 40% is a key measure to ensure product quality and process economy from the source.

[0054] It should be noted that the order of the above embodiments of the present invention is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. Furthermore, the above description focuses on specific embodiments of this specification. Additionally, the processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired results. In some embodiments, multitasking and parallel processing are possible or may be advantageous.

[0055] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0056] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for producing and processing raw materials with low glycemic index, characterized in that, Includes the following steps: S1: Obtain starch-containing raw materials; S2: Pre-treat the starch-containing raw material to obtain pre-treated material; S3: Add at least one amylase to the pretreated material to carry out a first enzymatic hydrolysis reaction to obtain a first enzymatic hydrolysate; S4: Add pullulanase and β-amylase to the first hydrolysate to carry out a second hydrolysis reaction, and obtain a second hydrolysate rich in amylose fragments; S5: The second enzymatic hydrolysate is subjected to enzyme inactivation treatment, and recrystallization treatment is carried out under controlled temperature gradient to rearrange the amylose fragments to form resistant starch, thereby obtaining raw materials with low glycemic value.

2. The method according to claim 1, characterized in that, The amylase used in the first enzymatic hydrolysis reaction is a thermostable α-amylase, the reaction temperature is 85-95℃, the reaction time is 10-30 minutes, and the enzyme addition amount is 5-15 U / g.

3. The method according to claim 1, characterized in that, The conditions for the second enzymatic hydrolysis reaction are: temperature 50-65℃, pH 4.0-5.5, and reaction time 2-6 hours; wherein the amount of pullulanase added is 10-50 U / g, and the amount of β-amylase added is 20-80 U / g.

4. The method according to claim 1, characterized in that, The recrystallization process includes: rapidly cooling the second enzymatic hydrolysate after enzyme inactivation to 35-45°C, then slowly cooling it to 4-10°C at a rate of 0.5-2°C / min, and letting it stand for 12-48 hours.

5. The method according to claim 4, characterized in that, During the recrystallization process, a shear force is applied to the second enzymatic hydrolysate. The shear force is provided by a homogenizer or a high-shear dispersing emulsifier at a speed of 3000-8000 rpm for a processing time of 5-15 minutes.

6. The method according to claim 1, characterized in that, Before carrying out the first enzymatic hydrolysis reaction, a natural plant polyphenol compound is added to the pretreated material as a competitive inhibitor of amylase. The natural plant polyphenol compound is selected from at least one of green tea extract, grape seed extract or apple peel extract, and the amount added is 0.5%-3% based on the dry weight of the starch-containing raw material.

7. The method according to claim 1, characterized in that, Following the recrystallization process, a membrane separation purification step is also included: microfiltration of the recrystallized material using a ceramic membrane with a pore size of 0.1-0.5 μm, and collection of the permeate; then nanofiltration of the permeate using a nanofiltration membrane with a molecular weight cutoff of 1000-5000 Da, and collection of the retained liquid.

8. The method according to claim 7, characterized in that, Following the membrane separation and purification step, a nutrient fortification and drying step is also included: a micronutrient premix containing chromium, zinc, B vitamins and dietary fiber is added to the retentate, and then spray drying is performed with an inlet air temperature of 160-180℃ and an outlet air temperature of 70-90℃ to obtain a low glycemic index raw material powder.

9. The method according to claim 1, characterized in that, The pretreatment includes: ultra-fine pulverizing the starch-containing raw material to make the average particle size D50 of the starch-containing raw material less than 50 μm, and mixing it with water to prepare a slurry with a solid content of 15%-25%.

10. The method according to claim 1, characterized in that, The starch-containing raw material is a grain or legume with a high amylose content, wherein the amylose content in the starch-containing raw material accounts for more than 40% of the total dry starch mass.

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