Low-GI special dietary food and preparation method thereof

Abstract

The invention belongs to the technical field of food processing, and discloses a low-GI special dietary food and a preparation method thereof.The preparation method comprises the following preparation steps that carbohydrate, carboxymethylated fiber and phosphate are added into water, heating reaction is conducted, and a modified base material is obtained; puffing the insoluble dietary fibers to obtain puffed fibers; and mixing the modified base material, puffed fiber and an auxiliary agent, heating, carrying out mould pressing, and cooling to obtain the low-GI special dietary food. The low-GI special dietary food prepared by the method achieves dual nutrition and health goals of stable blood sugar and continuous satiety.

Description

Technical Field

[0001] This application relates to the field of food processing technology, and in particular to a low-GI special dietary food and its preparation method. Background Technology

[0002] The glycemic index (GI) measures the impact of carbohydrates in food on blood glucose levels. A high GI value reflects the speed and ability of a food to raise blood glucose levels after digestion. Low-GI foods (GI ≤ 55) are broken down slowly in the digestive tract, resulting in a gradual release of glucose and a smaller rise in blood glucose. High-GI foods (GI ≥ 70) are digested rapidly, leading to sharp fluctuations in blood glucose. The GI concept aims to help people regulate their glycemic response through dietary choices, and is particularly important for the long-term dietary management of patients with metabolic diseases such as diabetes and obesity, as well as healthy individuals.

[0003] In daily life, to balance blood sugar control needs with dietary convenience, the food industry often tends to develop formulations with significantly reduced carbohydrate content, even producing near-zero-carb dietary alternatives. While such designs directly avoid the risks of high GI, they overlook the fundamental role of carbohydrates in the body's energy system and overall nutritional structure—they are not only the primary fuel source for the central nervous system but also a basic macronutrient for maintaining physiological functions. While purely carbohydrate-free solutions may result in lower GI values ​​in the short term, they are unlikely to meet the needs of balanced nutrition in the long run and are not sustainable for daily diets. Summary of the Invention

[0004] The technical problem to be solved by this invention is to propose a low-GI special dietary food and its preparation method, which aims to solve the problem of excessively high GI value of dietary food in the intestinal environment due to excessive blood sugar content.

[0005] To address the aforementioned technical problems, this invention proposes a method for preparing a low-GI special dietary food, the method comprising the following preparation steps: S1. Add carbohydrates, carboxymethyl cellulose and phosphate to water, heat and react to obtain the modified base material; S2. Insoluble dietary fiber is expanded to obtain expanded fiber; S3. After mixing the modified base material, expanded fiber, and additives, heat and mold, then cool to obtain a low-GI special dietary food.

[0006] In some embodiments, the carbohydrates in step S1 include at least one of oat flour, wheat flour, quinoa flour, and highland barley flour; the carboxymethylated fiber includes at least one of carboxymethyl cellulose, carboxymethyl β-glucan, and carboxymethyl guar gum; and the phosphate includes at least one of sodium tripolyphosphate, sodium hexametaphosphate, and sodium pyrophosphate.

[0007] In some embodiments, step S1 includes: S1.1 Add the fiber raw material to isopropanol, stir and add 25~40wt% sodium hydroxide aqueous solution at room temperature, and continue stirring and reacting for 30~90min to obtain an alkalized solution. The fiber raw material includes at least one of cellulose, β-glucan, and guar gum powder. The mass ratio of fiber raw material:isopropanol:sodium hydroxide aqueous solution is 1:(5~8):(3~5). S1.2 Add chloroacetic acid to the alkaline solution, heat to 50~70℃ and stir for 2~4 hours to obtain the reaction solution and adjust its pH to neutral. Add it to a 70% ethanol aqueous solution, filter, wash with ethanol, dry and pulverize to obtain hydroxymethylated fiber. The mass ratio of chloroacetic acid to fiber raw material is (0.8~1.2):1. S1.3. After mixing hydroxymethylated cellulose, carbohydrates, and phosphates, deionized water is added to obtain a suspension with a solid content of 25-35%. Dilute hydrochloric acid is added dropwise to adjust the pH of the suspension to 9.5-10.0. The suspension is stirred at 40-50℃ for 3-4 hours, maintaining the pH at 9.5-10.0 during the stirring process. After stirring is completed, the pH is adjusted to neutral. The mixture is centrifuged, and the precipitate is washed with deionized water, dried, and crushed to obtain the modified base material. The mass ratio of hydroxymethylated cellulose, carbohydrates, and phosphates is (20-30):(65-75):(3-7).

[0008] In some embodiments, the insoluble dietary fiber in step S2 includes at least one of oat bran, wheat bran, and rice bran.

[0009] In some embodiments, step S2 includes: S2.1. Crush insoluble dietary fiber and pass it through an 80-mesh sieve to obtain fiber powder. Mix it with water and let it stand at 25~30℃ for 10~12 hours to obtain wet fiber. The mass ratio of fiber powder to water is 1:(0.6~0.8). S2.2 Add the wet fiber to a twin-screw extruder and expand it at 110~130℃ and 2~4MPa for 15~30s to obtain expanded material. Add it to a citrate buffer solution and stir at 100~120℃ for 30~60min. Centrifuge, filter, and dry to obtain expanded fiber. The mass ratio of expanded material to citrate buffer solution is 1:(8~12), and the concentration of citric acid in the citrate buffer solution is 2~5wt%.

[0010] In some embodiments, the adjuvant in step S3 includes at least one of protein, mineral, and sweetener; The protein includes at least one of soy protein isolate, whey protein isolate, pea protein, and rice protein; The minerals include at least one of calcium carbonate, zinc gluconate, ferric pyrophosphate, and selenium-enriched yeast; Sweeteners include at least one of erythritol, steviol glycosides, mogrosides, and sucralose.

[0011] In some embodiments, step S3 includes: S3.1 After mixing the modified base material, expanded fiber, auxiliary agent and glycerin, stir and mix at 60~70℃ for 15~25min to obtain the premixed base material, wherein the mass ratio of modified base material: expanded fiber: auxiliary agent: glycerin is (60~70):(25~35):(8~12):(10~20); S3.2 Place the material in a mold at 120~135℃ and hot press it at 10~15MPa pressure for 4~6 minutes to obtain a low-GI special dietary food.

[0012] In addition, a low-GI special dietary food is provided, which is prepared by the preparation method of a low-GI special dietary food described above.

[0013] The beneficial effects of this invention are: First, in step S1, phosphate reacts with the hydroxyl groups on the starch molecular chains in carbohydrates through esterification, forming phosphate bonds and constructing a three-dimensional cross-linked network. This enhances the structural density of the starch granules, making them more difficult for amylases to access and hydrolyze. Simultaneously, the carboxymethylated fibers in the reaction system, through their abundant carboxyl anions, physically entangle with the starch and phosphate networks via hydrogen bonds, further reinforcing this anti-enzymatic barrier. The expanded fibers prepared in step S2 have a well-developed porous structure and a large specific surface area. In step S3, the hot-pressing process softens the modified matrix into a flowable gel phase at high temperature, and the high pressure forces the expanded fibers to be injected and filled into the compressed porous skeleton. After cooling and setting, the two form a stable interpenetrating composite structure through mechanical interlocking and interfacial molecular forces, forming a soluble gel network-insoluble porous skeleton interpenetrating system. This composite structure exhibits multiple synergistic functions in the gastrointestinal tract: Firstly, in the upper small intestine, it significantly delays the contact between amylase and substrate through spatial barrier effects. Combined with the resistance to enzymatic hydrolysis via a chemical cross-linking network, it collectively delays the release and absorption of glucose, resulting in a smoother postprandial blood glucose curve and effectively reducing the product's glycemic index. Secondly, the strong water absorption of the puffed fiber significantly increases the volume of chyme, delaying gastric emptying through mechanical stimulation. Undigested resistant components enter the large intestine and are fermented by gut microbiota to produce short-chain fatty acids and active metabolites. These substances not only provide a continuous energy supply but also extend the duration of satiety through neuroendocrine pathways by stimulating colonic L cells to release satiety hormones such as glucagon-like peptide-1 and peptide YY. The entire process demonstrates multi-level synergy from molecular modification to macroscopic structure, from delayed digestion to metabolic regulation, ultimately achieving the dual nutritional health goals of stable blood glucose and sustained satiety. Attached Figure Description

[0014] Figure 1 This is a schematic flowchart of a method for preparing a low-GI special dietary food according to an embodiment of the present invention. Detailed Implementation

[0015] In the description of this application, it should be noted that, unless specific conditions are specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0016] Please refer to Figure 1 This invention provides a method for preparing a low-GI special dietary food, the method comprising the following preparation steps: S1. Add carbohydrates, carboxymethyl cellulose and phosphate to water and heat to react, to obtain the modified base material.

[0017] In step S1, the carbohydrates include at least one of oat flour, wheat flour, quinoa flour, and highland barley flour; the carboxymethylated fiber includes at least one of carboxymethyl cellulose, carboxymethyl β-glucan, and carboxymethyl guar gum; and the phosphate includes at least one of sodium tripolyphosphate, sodium hexametaphosphate, and sodium pyrophosphate. Phosphate reacts with the hydroxyl groups on the starch molecular chain in carbohydrates through esterification, forming phosphate ester bonds and constructing a three-dimensional cross-linked network. This enhances the structural compactness of starch granules, making them more difficult for amylases to access and hydrolyze. At the same time, carboxymethyl cellulose in the reaction system physically entangles with the starch and phosphate network through hydrogen bonds via its abundant carboxyl anions, further reinforcing this anti-enzymatic barrier.

[0018] Step S1 includes: S1.1 Add the fiber raw material to isopropanol, stir and add 25~40wt% sodium hydroxide aqueous solution at room temperature, and continue stirring and reacting for 30~90min to obtain an alkalized solution. The fiber raw material includes at least one of cellulose, β-glucan, and guar gum powder. The mass ratio of fiber raw material:isopropanol:sodium hydroxide aqueous solution is 1:(5~8):(3~5).

[0019] Isopropanol, as a non-aqueous solvent, can effectively inhibit the dissolution and swelling of fiber raw materials, ensuring that the reaction proceeds controllably in a heterogeneous system, thereby obtaining higher reaction efficiency and a more uniform alkalization depth. At the same time, the optimized mass ratio ensures that sodium hydroxide can fully penetrate into the fiber interior to fully activate its hydroxyl groups and form alkoxides, providing a highly reactive intermediate for the subsequent carboxymethylation step. Furthermore, the mild room temperature conditions avoid excessive degradation of the fiber under strong alkali, ultimately yielding a uniform and stable alkalization solution, laying a key foundation for the preparation of highly substituted and structurally complete carboxymethylated fibers.

[0020] S1.2 Add chloroacetic acid to the alkaline solution, heat to 50~70℃ and stir for 2~4 hours to obtain the reaction solution and adjust its pH to neutral. Add it to a 70% ethanol aqueous solution, filter, wash with ethanol, dry and pulverize to obtain hydroxymethylated fiber. The mass ratio of chloroacetic acid to fiber raw material is (0.8~1.2):1.

[0021] Carboxymethylated fibers (such as carboxymethyl cellulose) exhibit a sharp decrease in solubility in aqueous solutions of high-concentration ethanol, resulting in selective precipitation as fibrous or flocculent solids. Impurities such as sodium chloride show only a limited decrease in solubility in the ethanol-water system and primarily remain in the ethanol-water mother liquor. Solid-liquid separation is then achieved through filtration, followed by washing the filter cake with ethanol to further dissolve and remove trace impurity ions adsorbed on the fiber surface. This method efficiently removes soluble impurities such as chloride ions, purifying the fibers to high purity while avoiding significant product loss due to water washing. Furthermore, the volatile nature of ethanol facilitates subsequent drying.

[0022] S1.3. After mixing hydroxymethylated cellulose, carbohydrates, and phosphates, deionized water is added to obtain a suspension with a solid content of 25-35%. Dilute hydrochloric acid is added dropwise to adjust the pH of the suspension to 9.5-10.0. The suspension is stirred at 40-50℃ for 3-4 hours, maintaining the pH at 9.5-10.0 during the stirring process. After stirring is completed, the pH is adjusted to neutral. The mixture is centrifuged, and the precipitate is washed with deionized water, dried, and crushed to obtain the modified base material. The mass ratio of hydroxymethylated cellulose, carbohydrates, and phosphates is (20-30):(65-75):(3-7).

[0023] Under weakly alkaline conditions and mild heating, phosphate preferentially undergoes esterification and cross-linking with the hydroxyl groups on starch molecules to form a stable three-dimensional covalent network, endowing the matrix with intrinsic resistance to enzymatic degradation. Simultaneously, hydroxymethylated fibers, with their abundant carboxyl groups, physically entangle and reinforce the aforementioned phosphate-starch network through hydrogen bonds and ionic interactions, enhancing its structural stability. The entire aqueous suspension system ensures sufficient contact and mass transfer of reactant molecules. Finally, through pH adjustment, centrifugation, and washing, a modified matrix material with uniform structure and significantly improved digestibility is obtained. This matrix material combines the rigid resistance of chemical cross-linking with the tough maintenance of physical entanglement, laying a core material foundation for the subsequent preparation of low-GI special dietary foods with sustained-release carbohydrate functions.

[0024] S2. Insoluble dietary fiber is expanded to obtain expanded fiber.

[0025] The insoluble dietary fiber in step S2 includes at least one of oat bran, wheat bran, and rice bran.

[0026] By puffing insoluble dietary fibers such as oat bran, wheat bran, or rice bran, puffed fibers with a well-developed porous structure and a large specific surface area are obtained. In the final product, these fibers can encapsulate starch particles through physical adsorption, increase chyme viscosity, and form a diffusion barrier, effectively delaying the contact between amylase and substrate and the dissolution rate of glucose. This reduces the intensity of immediate digestion and absorption of carbohydrates in the intestinal environment, smooths the postprandial blood glucose response, and directly contributes to reducing the overall glycemic index of the product.

[0027] Step S2 includes: S2.1. Crush insoluble dietary fiber and pass it through an 80-mesh sieve to obtain fiber powder. Mix it with water and let it stand at 25~30℃ for 10~12 hours to obtain wet fiber. The mass ratio of fiber powder to water is 1:(0.6~0.8).

[0028] By pre-treating insoluble dietary fiber with hydration, it can fully and uniformly absorb a limited amount of water without causing gelatinization or excessive swelling, forming a wet fiber gel matrix with specific plasticity and cohesiveness. This not only effectively improves the efficiency and uniformity of steam generation during subsequent puffing, ensuring a more porous and crispy puffed structure, but also allows it to better combine with other hydrophilic components (such as modified matrix materials) in the final food system, improving the overall texture uniformity and taste.

[0029] S2.2 Add the wet fiber to a twin-screw extruder and expand it at 110~130℃ and 2~4MPa for 15~30s to obtain expanded material. Add it to a citrate buffer solution and stir at 100~120℃ for 30~60min. Centrifuge, filter, and dry to obtain expanded fiber. The mass ratio of expanded material to citrate buffer solution is 1:(8~12), and the concentration of citric acid in the citrate buffer solution is 2~5wt%.

[0030] The wet fibers are instantly expanded by high-pressure hot extrusion to form a porous and crumbly physical structure. Then, a mild acid-catalyzed hydrothermal reaction is carried out in a citric acid buffer solution. The beneficial effects are: the acidic environment is used to controllably etch and hydrolyze the surface of the expanded fibers, partially breaking the glycosidic bonds at the edges of the amorphous and crystalline regions, further increasing the porosity and specific surface area.

[0031] S3. After mixing the modified base material, expanded fiber, and additives, heat and mold, then cool to obtain a low-GI special dietary food.

[0032] The adjuvants in step S3 include at least one of protein, mineral, and sweetener; The protein includes at least one of soy protein isolate, whey protein isolate, pea protein, and rice protein; The minerals include at least one of calcium carbonate, zinc gluconate, ferric pyrophosphate, and selenium-enriched yeast; Sweeteners include at least one of erythritol, steviol glycosides, mogrosides, and sucralose.

[0033] In step S3, the hot pressing process softens the modified base material into a flowable gel phase at high temperature, and the high pressure forces it to be injected and filled with the compressed porous skeleton of the expanded fiber. After cooling and shaping, the two form a stable interpenetrating composite structure through mechanical interlocking and interfacial molecular forces, forming a soluble gel network-insoluble porous skeleton interpenetrating system. This composite structure exhibits multiple synergistic functions in the gastrointestinal tract: on the one hand, in the upper small intestine, it significantly delays the contact between amylase and substrate through spatial barrier effect, and combined with the resistance to enzymatic hydrolysis by the chemical cross-linking network, it jointly delays the release and absorption of glucose, forming a smooth postprandial blood glucose curve and effectively reducing the glycemic index of the product; on the other hand, the strong water absorption of the puffed fiber significantly increases the volume of chyme, delaying gastric emptying through mechanical stimulation, while the undigested resistant components enter the large intestine and are fermented by the microbial community to produce short-chain fatty acids and active metabolites. These substances not only provide a continuous energy supply, but also extend the duration of satiety through the neuroendocrine pathway by stimulating the release of glucagon-like peptide-1, peptide YY and other satiety hormones from colonic L cells.

[0034] Step S3 includes: S3.1 After mixing the modified base material, expanded fiber, auxiliary agent and glycerin, stir and mix at 60~70℃ for 15~25min to obtain the premixed base material, wherein the mass ratio of modified base material: expanded fiber: auxiliary agent: glycerin is (60~70):(25~35):(8~12):(10~20).

[0035] Glycerin, acting as a plasticizer and medium at 60-70℃, effectively promotes the interfacial fusion and intercalation between the soluble component (modified matrix) and the insoluble component (expanded fiber). On the one hand, it allows the hydrophilic segments in the modified matrix, such as carboxymethylated fiber and phosphorylated starch, to fully expand and pre-gel, laying the foundation for the subsequent formation of a continuous hydrated gel network. On the other hand, glycerin penetrates into the porous skeleton of the expanded fiber, softening its fiber walls and enhancing its flexibility. This treatment allows the molten or softened soluble gel precursor to more fully penetrate and encapsulate the insoluble fiber skeleton during subsequent heating and molding, forming a stable interpenetrating structure after cooling and solidification, where the soluble gel network runs through and is anchored to the insoluble porous skeleton.

[0036] S3.2 Place the material in a mold at 120~135℃ and hot press it at 10~15MPa pressure for 4~6 minutes to obtain a low-GI special dietary food.

[0037] The high-temperature and high-pressure hot pressing process utilizes the good thermoplasticity of the material after plasticization with glycerol, causing the soluble fiber components in the modified base material to melt and flow at 120~135℃. At the same time, it forces the expanded fiber skeleton to undergo tight deformation and rearrangement. The molten soluble components fully penetrate and encapsulate the insoluble skeleton under high pressure. After cooling, a dense and stable continuous melt-solidified phase-fiber skeleton interpenetrating network structure is formed. This structure not only gives the product a solid texture and shape retention, but also effectively delays the contact hydrolysis of carbohydrates by digestive enzymes through the physical barrier effect. It is the core molding step to achieve the low glycemic index function.

[0038] In one embodiment, to further enhance the low-GI effect, polyphenol-resistant starch is added. The preparation method of the polyphenol-resistant starch is as follows: Prepare a resistant starch solution with a concentration of 8-15 wt% using water, heat to 85-95℃ for 25-35 min to gelatinize, and then cool to 50℃ to obtain a gelatinized solution. Add polyphenolic compounds and laccase to the gelatinized solution and adjust the pH of the gelatinized solution to 5.0. Under light-protected conditions, stir and react at 45-55℃ for 10-12 h. Then, sterilize at 90℃ for 8-10 min by increasing the temperature at 3-5℃ / min. Cool to room temperature, centrifuge, filter, wash with ethanol, and dry to obtain polyphenol-resistant starch. The mass ratio of gelatinized solution, polyphenolic compounds, and laccase is 1:(0.05-0.15):(0.02-0.05), and the laccase activity is ≥50 U / mL.

[0039] Resistant starch includes at least one of pea resistant starch, corn resistant starch, potato resistant starch, and brown rice resistant starch, and polyphenolic compounds include at least one of chlorogenic acid, ferulic acid, gallic acid, and catechins.

[0040] The mass ratio of polyphenol resistant starch to modified base material and expanded fiber is (5~15):(60~70):(25~35).

[0041] It should be noted that, depending on the actual application, vitamins, trace elements and other nutrients that meet food safety standards may also be added to the above-mentioned additives.

[0042] In addition, this application also provides a low-GI special dietary food, which is prepared by the preparation method of a low-GI special dietary food described above.

[0043] For example, the present invention provides the following specific embodiments to illustrate the specific preparation method: Example 1 S1.1 Add cellulose to isopropanol, stir at room temperature and add 30wt% sodium hydroxide aqueous solution, continue stirring and react for 60 min to obtain an alkalized solution, wherein the mass ratio of cellulose:isopropanol:sodium hydroxide aqueous solution is 1:6:4; S1.2 Add chloroacetic acid to the alkaline solution, heat to 60℃ and stir for 3 hours to obtain a reaction solution and adjust its pH to neutral. Add it to a 70% ethanol aqueous solution, filter, wash with ethanol, dry and pulverize to obtain hydroxymethyl cellulose, wherein the mass ratio of chloroacetic acid to cellulose is 1:1. S1.3. After mixing hydroxymethyl cellulose, oat flour, and sodium tripolyphosphate, deionized water was added to obtain a suspension with a solid content of 30%. Dilute hydrochloric acid was added dropwise to adjust the pH of the suspension to 9.8. The suspension was stirred at 45°C for 3.5 hours, maintaining the pH at 9.5~10.0 during the stirring process. After stirring was completed, the pH was adjusted to neutral. The mixture was centrifuged, and the precipitate was washed with deionized water, dried, and crushed to obtain the modified base material. The mass ratio of hydroxymethyl cellulose, oat flour, and sodium tripolyphosphate was 25:70:5. S2.1. Crush oat bran and pass it through an 80-mesh sieve to obtain fiber powder. Mix it with water and let it stand at 25~30℃ for 10~12 hours to obtain wet fiber. The mass ratio of fiber powder to water is 1:0.7. S2.2 The wet fibers were added to a twin-screw extruder and expanded at 120℃ and 3MPa for 22s to obtain expanded material. This expanded material was then added to a citrate buffer solution and stirred at 110℃ for 45min. The mixture was then centrifuged, filtered, and dried to obtain expanded fibers. The mass ratio of the expanded material to the citrate buffer solution was 1:10, and the concentration of citric acid in the citrate buffer solution was 3.5wt%. S3.1 After mixing the modified base material, expanded fiber, auxiliary agent and glycerin, stir and mix at 65℃ for 20min to obtain the premixed base material, wherein the mass ratio of modified base material: expanded fiber: auxiliary agent: glycerin is 65:30:10:15; S3.2 Place the material in a mold at 130℃ and hot press it at 12MPa pressure for 5 minutes to obtain a low-GI special dietary food.

[0044] The adjuvant is composed of pea protein, potassium sorbate, and erythritol in a mass ratio of 97:1:2.

[0045] Example 2 The process is basically the same as in Example 1, except that step S3.1 also includes polyphenolic pea resistant starch, and the mass ratio of polyphenolic pea resistant starch to modified base material and expanded fiber is 10:65:30. The preparation steps of polyphenolic pea resistant starch are as follows: Pea resistant starch was prepared into a 12wt% mixture with water, heated to 90℃ for 30 min to gelatinize, and then cooled to 50℃ to obtain a gelatinized solution. Chlorogenic acid and laccase were added to the gelatinized solution, and the pH of the gelatinized solution was adjusted to 5.0. The mixture was stirred at 50℃ for 11 h under light-protected conditions, and then sterilized at 90℃ for 9 min by increasing the temperature at 4℃ / min. After cooling to room temperature, the mixture was centrifuged, filtered, washed with ethanol, and dried to obtain polyphenolic pea resistant starch. The mass ratio of gelatinized solution, chlorogenic acid, and laccase was 1:0.1:0.035, and the laccase activity was 60 U / mL.

[0046] Comparative Example 1 It is basically the same as Example 1, except that the modified base material does not contain carboxymethyl cellulose, that is, it does not contain carboxymethylated fiber.

[0047] Comparative Example 2 It is basically the same as Example 1, except that the modified base material does not contain sodium tripolyphosphate, that is, it does not contain phosphate.

[0048] Comparative Example 3 It is basically the same as Example 1, except that the insoluble dietary fiber is not puffed.

[0049] Comparative Example 4 It is basically the same as Example 1, except that cellulose is used instead of hydroxymethyl cellulose in the modified base material.

[0050] Comparative Example 5 It is basically the same as Example 1, except that cellulose is used instead of hydroxymethyl cellulose in the modified base material and sodium tripolyphosphate is not contained, and the insoluble dietary fiber is not puffed.

[0051] Performance testing: To evaluate the low-GI efficacy of the product, healthy adult male SD rats were selected and divided into 7 groups of 5 rats each according to Examples 1-2 and Comparative Examples 1-5. After acclimatization, the rats were fasted for 12 hours and administered the test substance by gavage at 10 mL / kg body weight. Blood glucose levels were measured by tail vein sampling before gavage (0 min) and at 15, 30, 60, and 120 min after gavage. The blood glucose levels are shown in Table 1.

[0052] Table 1 Blood glucose levels in SD rats As shown in Table 1, compared with Comparative Example 5, the low-GI special dietary foods prepared in Examples 1-2 showed smaller fluctuations in blood glucose within two hours after consumption, and the final blood glucose was significantly lower than that of Comparative Example 5. Observations of Comparative Examples 1-3 and Example 1 show that when carboxymethyl cellulose, phosphate, or insoluble dietary fiber is lacking or not puffed, the amplitude of blood glucose fluctuations increases, ultimately leading to elevated blood glucose. Among these, the lack of phosphate has the most severe impact on the effect. Finally, observing Comparative Example 4 and Example 1, it can be seen that when ordinary soluble dietary fiber is used to provide carboxymethyl fiber, although there is still a certain improvement compared to Comparative Example 5, the improvement is still limited.

[0053] The above embodiments are preferred embodiments of this application, but the implementation of this application is not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of this application shall be considered equivalent substitutions and shall be included within the protection scope of this application.

Claims

1. A method for preparing a low-GI special dietary food, characterized in that, The preparation method includes the following preparation steps: S1. Add carbohydrates, carboxymethyl cellulose and phosphate to water, heat and react to obtain the modified base material; S2. Insoluble dietary fiber is expanded to obtain expanded fiber; S3. After mixing the modified base material, expanded fiber, and additives, heat and mold, then cool to obtain a low-GI special dietary food.

2. The method for preparing a low-GI special dietary food according to claim 1, characterized in that, In step S1, the carbohydrates include at least one of oat flour, wheat flour, quinoa flour, and highland barley flour; the carboxymethylated fiber includes at least one of carboxymethyl cellulose, carboxymethyl β-glucan, and carboxymethyl guar gum; and the phosphates include at least one of sodium tripolyphosphate, sodium hexametaphosphate, and sodium pyrophosphate.

3. The method for preparing a low-GI special dietary food according to claim 1, characterized in that, Step S1 includes: S1.1 Add the fiber raw material to isopropanol, stir and add 25~40wt% sodium hydroxide aqueous solution at room temperature, and continue stirring and reacting for 30~90min to obtain an alkalized solution. The fiber raw material includes at least one of cellulose, β-glucan, and guar gum powder. The mass ratio of fiber raw material:isopropanol:sodium hydroxide aqueous solution is 1:(5~8):(3~5). S1.2 Add chloroacetic acid to the alkaline solution, heat to 50~70℃ and stir for 2~4 hours to obtain the reaction solution and adjust its pH to neutral. Add it to a 70% ethanol aqueous solution, filter, wash with ethanol, dry and pulverize to obtain hydroxymethylated fiber. The mass ratio of chloroacetic acid to fiber raw material is (0.8~1.2):

1. S1.

3. After mixing hydroxymethylated cellulose, carbohydrates, and phosphates, deionized water is added to obtain a suspension with a solid content of 25-35%. Dilute hydrochloric acid is added dropwise to adjust the pH of the suspension to 9.5-10.

0. The suspension is stirred at 40-50℃ for 3-4 hours, maintaining the pH at 9.5-10.0 during the stirring process. After stirring is completed, the pH is adjusted to neutral. The mixture is centrifuged, and the precipitate is washed with deionized water, dried, and crushed to obtain the modified base material. The mass ratio of hydroxymethylated cellulose, carbohydrates, and phosphates is (20-30):(65-75):(3-7).

4. The method for preparing a low-GI special dietary food according to claim 1, characterized in that, The insoluble dietary fiber in step S2 includes at least one of oat bran, wheat bran, and rice bran.

5. The method for preparing a low-GI special dietary food according to claim 1, characterized in that, Step S2 includes: S2.

1. Crush insoluble dietary fiber and pass it through an 80-mesh sieve to obtain fiber powder. Mix it with water and let it stand at 25~30℃ for 10~12 hours to obtain wet fiber. The mass ratio of fiber powder to water is 1:(0.6~0.8). S2.2 Add the wet fiber to a twin-screw extruder and expand it at 110~130℃ and 2~4MPa for 15~30s to obtain expanded material. Add it to a citrate buffer solution and stir at 100~120℃ for 30~60min. Centrifuge, filter, and dry to obtain expanded fiber. The mass ratio of expanded material to citrate buffer solution is 1:(8~12), and the concentration of citric acid in the citrate buffer solution is 2~5wt%.

6. The method for preparing a low-GI special dietary food according to claim 1, characterized in that, The adjuvants in step S3 include at least one of protein, mineral, and sweetener; The protein includes at least one of soy protein isolate, whey protein isolate, pea protein, and rice protein; The minerals include at least one of calcium carbonate, zinc gluconate, ferric pyrophosphate, and selenium-enriched yeast; Sweeteners include at least one of erythritol, steviol glycosides, mogrosides, and sucralose.

7. The method for preparing a low-GI special dietary food according to claim 1, characterized in that, Step S3 includes: S3.1 After mixing the modified base material, expanded fiber, auxiliary agent and glycerin, stir and mix at 60~70℃ for 15~25min to obtain the premixed base material, wherein the mass ratio of modified base material: expanded fiber: auxiliary agent: glycerin is (60~70):(25~35):(8~12):(10~20); S3.2 Place the material in a mold at 120~135℃ and hot press it at 10~15MPa pressure for 4~6 minutes to obtain a low-GI special dietary food.

8. A low-GI special dietary food, characterized in that, The low-GI special dietary food is prepared by any one of the preparation methods of a low-GI special dietary food according to claims 1-7.

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