Rye composite powder with low glycemic index and preparation method thereof

Abstract

The invention discloses rye composite powder with a low glycemic index and a preparation method of the rye composite powder, and relates to the technical field of food processing. The preparation method of the rye composite powder with the low glycemic index comprises the following steps: adding water into rye powder, mixing, and sequentially carrying out alkali treatment, acid neutralization treatment, primary enzymolysis, heating gelatinization, ingredient addition, secondary enzymolysis, high-pressure homogenization treatment and spray drying treatment, so as to obtain the rye composite powder with the low glycemic index. Finally, the composite powder product with high soluble dietary fiber content, low glycemic index, good brewing performance and nutrition function synergy is obtained. Through alkaline hydrolysis wall breaking, double-enzymolysis graded release, regulation and control of starch digestion characteristics by light gelatinization, improvement of physical properties by high-pressure homogenization and synergistic interaction of functional ingredients, the problem that existing high-fiber powder is difficult to realize high soluble dietary fibers, low GI and good reconstituability at the same time is solved. The prepared rye composite powder has the advantages that the nutrition function is obviously improved, the process controllability is strong, and the rye composite powder is suitable for large-scale continuous production.

Description

Technical Field

[0001] This invention relates to the field of food processing technology, and in particular to a low glycemic index rye compound powder and its preparation method. Background Technology

[0002] With changes in modern lifestyles and adjustments in dietary structure, the incidence of chronic diseases such as hyperglycemia, obesity, and metabolic syndrome continues to rise, and consumers' demand for health foods with functions such as regulating blood sugar and improving gut health is increasing. Against this backdrop, developing functional foods that combine high dietary fiber content with a low glycemic index (GI) has become one of the research hotspots in the fields of food science and nutrition.

[0003] Currently, the development of high-fiber powders with low glycemic index (GI) mainly adopts the following technical paths: (1) Physical grinding method: whole grains (such as oats, rye, wheat bran, etc.) are conventionally ground or ultra-finely ground to directly produce powder. This method is simple, but the cell wall structure is intact, resulting in low soluble dietary fiber dissolution rate and poor bioavailability; (2) Single enzymatic hydrolysis method: xylanase or cellulase is used to treat grain raw materials under mild conditions to increase the soluble fiber content. However, due to the lack of pretreatment, the enzyme is difficult to effectively penetrate the cell wall, and the reaction efficiency is low; (3) Compound ingredient dry mixing method: commercially available rye flour is physically mixed with ingredients such as oligofructose and maltodextrin to make meal replacement powder or instant powder. Although such products claim to be "high fiber and low GI", they lack structural modification, have poor solubility, are prone to clumping, have poor reconstitution properties, and the GI value is unstable. Therefore, conventional methods for preparing low glycemic index foods still lack systematic understanding of the cell wall structure of raw materials and the targeted release of functional components, making it difficult to simultaneously achieve the goals of high soluble dietary fiber, low GI, good reconstitution properties, and enrichment of multiple functional factors. Summary of the Invention

[0004] The main objective of this invention is to propose a low glycemic index rye compound powder and its preparation method, aiming to solve the problem that existing high-fiber powders cannot simultaneously achieve high soluble dietary fiber, low GI and good reconstitution properties.

[0005] To achieve the above objectives, this invention proposes a method for preparing low glycemic index rye compound flour, comprising the following steps: S1. Rye flour and water are mixed to form a slurry, and then the slurry is subjected to alkali treatment and acid neutralization treatment in sequence to obtain pretreated rye slurry. S2. The pretreated rye pulp is mixed with the first complex enzyme and subjected to one enzymatic hydrolysis. After enzyme inactivation treatment, the first enzymatic hydrolysis product is obtained. The first complex enzyme includes cellulase, xylanase and lipase. S3. Heat the first enzymatic hydrolysis product to gelatinize the starch portion of the first enzymatic hydrolysis product, and obtain the gelatinized first enzymatic hydrolysis product. S4. The gelatinized first enzymatic hydrolysis product and the ingredients are mixed, and then a second complex enzyme is added for secondary enzymatic hydrolysis. After enzyme inactivation treatment, the second enzymatic hydrolysis product is obtained; wherein, the second complex enzyme includes protease and amylase. S5. The second enzymatic hydrolysis product is subjected to homogenization and spray drying processes in sequence to obtain rye compound powder with a low glycemic index.

[0006] In one embodiment, step S1, the method for preparing the rye flour includes: pulverizing rye grains; wherein the pulverizing process includes one of the following methods: (a) Grinding process using a hammer mill; (b) Use a mechanical impact pulverizer for pulverization.

[0007] In one embodiment, in step S1: The step of mixing rye flour and water to form a slurry includes: mixing rye flour and water at a mass ratio of 1:(10~12), stirring at 25~30℃ for 20~30 minutes to obtain the slurry; and / or, The pH value of the alkali treatment is 10.5~11.5, the temperature of the alkali treatment is 65~70℃, and the time of the alkali treatment is 60~90 min; and / or, Citric acid is used for acid neutralization treatment, the pH value of the acid neutralization treatment is 6.0~6.5, the temperature of the acid neutralization treatment is 65~70℃, and the time of the acid neutralization treatment is 15~20min.

[0008] In one embodiment, in step S2: The pH value of the first enzymatic hydrolysis is 6.0~6.5, the temperature of the first enzymatic hydrolysis is 50~55℃, and the time of the first enzymatic hydrolysis is 2~3 hours; and / or, The amount of cellulase added is 50-100 U / g, the amount of xylanase added is 100-200 U / g, and the amount of lipase added is 20-50 U / g.

[0009] In one embodiment, in step S3: When heating the first enzymatic hydrolysis product, the heating temperature is 85~95℃ and the heating time is 20~30min.

[0010] In one embodiment, in step S4, the ingredients include maltodextrin, sesame meal, fructooligosaccharides, and soybean lecithin, and the mass ratio of rye flour, maltodextrin, sesame meal, fructooligosaccharides, and soybean lecithin is (68~78):15:10:2:5.

[0011] In one embodiment, step S4, the secondary enzymatic hydrolysis includes: First, add protease and hydrolyze for 1 hour at pH 6.5-7.0 and 50-55℃. Then add amylase and continue hydrolysis for 1 hour at pH 6.5-7.0 and 60-65℃.

[0012] In one embodiment, the amount of protease added is 50-100 U / g, and the amount of amylase added is 30-60 U / g.

[0013] In one embodiment, in step S5: The homogenization process is performed using a high-pressure microfluidic homogenizer, and the parameters of the homogenization process include: pressure of 120~150 MPa, number of cycles of 1~2, and outlet temperature of 40~60℃; and / or, The parameters of the spray drying process include: centrifugal atomization, constant feed rate, inlet temperature of 160~180℃, and outlet temperature of 80~90℃.

[0014] The present invention also proposes a low glycemic index rye compound powder, which is prepared according to the preparation method described in the foregoing technical solution.

[0015] The technical solution of the present invention provides a method for preparing low glycemic index rye compound powder. After adding water to rye flour to make a slurry, the rye flour is subjected to alkali treatment, acid neutralization treatment, primary enzymatic hydrolysis, heating and gelatinization, addition of ingredients, secondary enzymatic hydrolysis, homogenization treatment and spray drying treatment in sequence, and finally a compound powder product with high soluble dietary fiber content, low glycemic index, good reconstitution performance and synergistic nutritional function is obtained. In the technical solution of this invention, firstly, alkali treatment is used to break the ester bond between arabinoxylan and ferulic acid, effectively releasing free ferulic acid and promoting the dissolution of soluble dietary fiber such as arabinoxylan, significantly improving its bioavailability. Subsequently, acid neutralization is performed to adjust the pH to a suitable range, creating favorable conditions for subsequent enzymatic hydrolysis. Then, an enzymatic hydrolysis stage is carried out using a complex enzyme system of cellulase, xylanase, and lipase to hydrolyze and generate functional oligosaccharides such as oligodextrose and xylooligosaccharides, releasing bound fat-soluble functional factors (such as bound vitamin E, phytosterols, and other antioxidants), achieving simultaneous enrichment and synergistic effects of multiple active ingredients, yielding the first enzymatic hydrolysis product. Finally, heating and gelatinization are used to moderately disrupt the starch crystal structure, enhancing the accessibility of its enzyme action sites and providing a viscosity basis, resulting in a paste. The first enzymatic hydrolysis product is obtained after gelatinization. Then, ingredients are added to the gelatinized first enzymatic hydrolysis product, followed by a second enzymatic hydrolysis stage with a complex enzyme to obtain the second enzymatic hydrolysis product. A complex enzyme system composed of protease and amylase is used, which on the one hand promotes moderate protein hydrolysis, improves protein digestibility, and reduces potential allergenicity; on the other hand, it causes mild enzymatic hydrolysis of starch, partially converting it into maltodextrin and resistant dextrin, while retaining more medium- and short-chain oligosaccharides, effectively delaying the glucose release rate, thereby maintaining the product's low glycemic index (GI) and achieving precise control of the GI value. Subsequently, the second enzymatic hydrolysis product is homogenized. Through high-intensity shearing and cavitation, the particle size of the second enzymatic hydrolysis product is significantly reduced, improving the system's uniformity and stability, and greatly enhancing the solubility, dispersibility, and reconstitution properties of the final product. Finally, spray drying is performed to obtain the finished black rice composite powder. Therefore, the technical solution of this invention solves the problem that existing high-fiber powders cannot simultaneously achieve high soluble dietary fiber, low GI, and good reconstitution properties through alkaline hydrolysis to break down cell walls, dual enzymatic hydrolysis for graded release, mild gelatinization to regulate starch digestibility, high-pressure homogenization to improve physical properties, and synergistic effects of functional ingredients. Furthermore, the prepared rye compound powder not only has significantly improved nutritional functions, but also exhibits strong process controllability and good repeatability, making it suitable for large-scale continuous production and possessing broad application prospects. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0017] Figure 1 This is a process flow diagram for preparing low glycemic index rye compound powder according to Example 1 of the present invention.

[0018] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0021] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0022] Currently, the development of high-fiber powders with low glycemic index (GI) mainly adopts the following technical paths: (1) Physical grinding method: whole grains (such as oats, rye, wheat bran, etc.) are conventionally ground or ultra-finely ground to directly produce powder. This method is simple, but the cell wall structure is intact, resulting in low soluble dietary fiber dissolution rate and poor bioavailability; (2) Single enzymatic hydrolysis method: xylanase or cellulase is used to treat grain raw materials under mild conditions to increase the soluble fiber content. However, due to the lack of pretreatment, the enzyme is difficult to effectively penetrate the cell wall, and the reaction efficiency is low; (3) Compound ingredient dry mixing method: commercially available rye flour is physically mixed with ingredients such as oligofructose and maltodextrin to make meal replacement powder or instant powder. Although such products claim to be "high fiber and low GI", they lack structural modification, have poor solubility, are prone to clumping, have poor reconstitution properties, and the GI value is unstable. Therefore, conventional methods for preparing low glycemic index foods still lack systematic understanding of the cell wall structure of raw materials and the targeted release of functional components, making it difficult to simultaneously achieve the goals of high soluble dietary fiber, low GI, good reconstitution properties, and enrichment of multiple functional factors.

[0023] In view of this, the present invention proposes a method for preparing low glycemic index rye compound flour, comprising the following steps: S1. Rye flour and water are mixed to form a slurry, and then the slurry is subjected to alkali treatment and acid neutralization treatment in sequence to obtain pretreated rye slurry. S2. The pretreated rye pulp is mixed with the first complex enzyme and subjected to one enzymatic hydrolysis. After enzyme inactivation treatment, the first enzymatic hydrolysis product is obtained. The first complex enzyme includes cellulase, xylanase and lipase. S3. Heat the first enzymatic hydrolysis product to gelatinize the starch portion of the first enzymatic hydrolysis product, and obtain the gelatinized first enzymatic hydrolysis product. S4. The gelatinized first enzymatic hydrolysis product and the ingredients are mixed, and then a second complex enzyme is added for secondary enzymatic hydrolysis. After enzyme inactivation treatment, the second enzymatic hydrolysis product is obtained; wherein, the second complex enzyme includes protease and amylase. S5. The second enzymatic hydrolysis product is subjected to homogenization and spray drying processes in sequence to obtain rye compound powder with a low glycemic index.

[0024] The technical solution of the present invention provides a method for preparing low glycemic index rye compound powder. After adding water to rye flour to make a slurry, the powder is subjected to alkali treatment, acid neutralization treatment, enzymatic hydrolysis by compound enzyme, heating and gelatinization, addition of ingredients, enzymatic hydrolysis by compound enzyme, homogenization treatment and spray drying treatment, and finally obtains a compound powder product with high soluble dietary fiber content, low glycemic index, good reconstitution performance and synergistic nutritional function.

[0025] In the technical solution of this invention, firstly, alkali treatment breaks the ester bond between arabinoxylan and ferulic acid, effectively releasing free ferulic acid and promoting the dissolution of soluble dietary fiber such as arabinoxylan, significantly improving its bioavailability. Subsequently, acid neutralization treatment adjusts the pH to a suitable range, creating favorable conditions for subsequent enzymatic hydrolysis. Then, an enzymatic hydrolysis stage is performed using a complex enzyme system of cellulase, xylanase, and lipase to hydrolyze and generate functional oligosaccharides such as oligodextrose and xylooligosaccharides, releasing bound fat-soluble functional factors (such as bound vitamin E and phytosterols, etc., antioxidants), achieving simultaneous enrichment and synergistic effects of multiple active ingredients, yielding the first enzymatic hydrolysis product. Subsequently, heating and gelatinization treatment moderately disrupts the starch crystal structure, enhancing the accessibility of its enzyme action sites and providing a viscosity basis, yielding the gelatinized product. The first enzymatic hydrolysis product is obtained by adding ingredients to the gelatinized first enzymatic hydrolysis product, followed by a second enzymatic hydrolysis stage with a complex enzyme to obtain the second enzymatic hydrolysis product. A complex enzyme system composed of protease and amylase is used to promote moderate hydrolysis of proteins, improve protein digestibility, and reduce potential allergenicity. Simultaneously, it causes mild enzymatic hydrolysis of starch, partially converting it into maltodextrin and resistant dextrin, while retaining more medium- and short-chain oligosaccharides, effectively slowing down the glucose release rate and maintaining the product's low glycemic index (GI) characteristics, achieving precise control of the GI value. Subsequently, high-pressure microfluidic homogenization technology is introduced to homogenize the second enzymatic hydrolysis product. Through high-intensity shearing and cavitation, the particle size is significantly reduced, improving the system's uniformity and stability, and greatly enhancing the final product's solubility, dispersibility, and reconstitution properties. Finally, spray drying is performed to obtain the finished black rice composite powder. Therefore, the technical solution of this invention solves the problem that existing high-fiber powders cannot simultaneously achieve high soluble dietary fiber, low GI and good reconstitution properties by alkaline hydrolysis to break the cell wall, dual enzymatic hydrolysis to release the starch in stages, mild gelatinization to regulate starch digestion characteristics, high-pressure homogenization to improve physical properties, and functional ingredients to enhance synergistic effects.

[0026] The rye compound powder prepared by this invention not only has significantly improved nutritional functions, but also has strong process controllability and good repeatability, making it suitable for large-scale continuous production and with broad application prospects.

[0027] In an embodiment of the present invention, step S1, the method for preparing the rye flour includes: pulverizing rye grains; wherein the pulverizing process includes one of the following methods: (a) Grinding process using a hammer mill; (b) Use a mechanical impact pulverizer for pulverization.

[0028] Rye flour can be purchased or prepared at home. In the technical solution of this invention, rye flour is obtained by pulverizing rye grains. Pulverizing clean and dried rye grains (moisture content ≤10%) can break down the physical barrier of cell walls, increase the specific surface area, which is beneficial to improving the penetration efficiency of subsequent alkali solutions and enzymes, and increasing the content of soluble dietary fiber.

[0029] It should be noted that the temperature must be controlled at ≤40℃ during the grinding process to prevent denaturation of heat-sensitive components. Moreover, compared to rye flour that has not undergone ultrafine grinding, rye flour that has undergone ultrafine grinding is more conducive to producing rye compound flour with a low glycemic index, high soluble dietary fiber content, and good synergistic effects in reconstitution and nutritional function.

[0030] In an embodiment of the present invention, step S1, the step of mixing rye flour and water to form a slurry, includes: mixing rye flour and water at a mass ratio of 1:(10~12), stirring at 25~30°C for 20~30 min to obtain the slurry. Mixing rye flour and water to form a uniform slurry is to establish a homogeneous reaction system, which facilitates mass transfer in subsequent chemical and enzymatic reactions. In one embodiment of the present invention, the slurry is obtained by mixing rye flour and water at a mass ratio of 1:10 and stirring at 25~30°C for 30 min.

[0031] In an embodiment of the present invention, in step S1, the pH value of the alkali treatment is 10.5-11.5, the temperature of the alkali treatment is 65-70°C, and the time of the alkali treatment is 60-90 min. Exemplarily, the pH value of the alkali treatment can be set to 10.5, 11, or 11.5, the temperature of the alkali treatment can be 65°C, 66°C, 67°C, 68°C, 69°C, or 70°C, and the time of the alkali treatment can be 60 min, 70 min, 80 min, or 90 min. Specifically, the alkali treatment can be achieved by slowly adding NaOH solution to the slurry. During alkali treatment, the alkali solution can dissolve lignin, disrupt the cell wall complex structure, and break the ester bond between ferulic acid and arabinoxylan, thereby facilitating the release of free ferulic acid; simultaneously, it can increase the dissolution rate of hemicellulose such as arabinoxylan and increase the content of soluble dietary fiber.

[0032] In an embodiment of the present invention, in step S1, citric acid is used for acid neutralization treatment. The pH value of the acid neutralization treatment is 6.0-6.5, the temperature of the acid neutralization treatment is 65-70°C, and the time of the acid neutralization treatment is 15-20 minutes. Exemplarily, the pH value of the acid neutralization treatment can be 6.0, 6.2, or 6.5, the temperature of the acid neutralization treatment can be 65°C, 66°C, 67°C, 68°C, 69°C, or 70°C, and the time of the acid neutralization treatment can be 15 minutes, 18 minutes, or 20 minutes. The technical solution of the present invention uses food-grade citric acid to adjust the pH back to 6.0-6.5, thereby terminating the alkaline hydrolysis reaction. Furthermore, the use of citric acid also provides a synergistic effect of metal chelation and antioxidant activity, improving the quality and service life of the prepared rye compound flour.

[0033] In an embodiment of the present invention, in step S2, the pH value of the first enzymatic hydrolysis is 6.0-6.5, the temperature of the first enzymatic hydrolysis is 50-55°C, and the time of the first enzymatic hydrolysis is 2-3 hours. Setting the enzymatic hydrolysis parameters in this way is beneficial to improving the hydrolysis efficiency and yield. For example, the pH value of the first enzymatic hydrolysis can be 6.0, 6.2, or 6.5; the temperature of the first enzymatic hydrolysis can be 50°C, 51°C, 52°C, 53°C, 54°C, or 55°C; and the time of the first enzymatic hydrolysis can be 2 hours, 2.5 hours, or 3 hours.

[0034] In an embodiment of the present invention, in step S2, the amount of cellulase added is 50-100 U / g, the amount of xylanase added is 100-200 U / g, and the amount of lipase added is 20-50 U / g, with the enzyme activity calculated on a dry basis (g) of rye flour.

[0035] Single enzymes are difficult to penetrate cell walls effectively, resulting in low reaction efficiency. This invention employs a single enzymatic hydrolysis using cellulase, xylanase, and lipase. Cellulase hydrolyzes some cellulose into oligodextrose, improving solubility; xylanase specifically hydrolyzes arabinoxylan to generate xylooligosaccharides (XOS), which have strong prebiotic effects and inhibit glucose absorption; lipase hydrolyzes residual lipids, reducing oxidative rancidity and releasing bound vitamin E, phytosterols, and other antioxidants. Setting the amount of cellulase to 50-100 U / g, the amount of xylanase to 100-200 U / g, and the amount of lipase to 20-50 U / g results in a better single-stage enzymatic hydrolysis effect while controlling costs.

[0036] In an embodiment of the present invention, step S2 includes high-temperature enzyme inactivation. The enzyme is inactivated by heating the enzymatically hydrolyzed reaction product solution to 85-90°C and maintaining this temperature for 10-15 minutes. This high-temperature enzyme inactivation inactivates the first-stage enzyme, prevents excessive degradation, and fixes the product structure.

[0037] In an embodiment of the present invention, in step S3, when heating the first enzymatic hydrolysis product, the heating temperature is 85~95℃ and the heating time is 20~30min.

[0038] Starch in its natural state exists in granular form with a highly ordered crystalline structure. This structure tightly encapsulates starch molecules (mainly amylose and amylopectin), making it difficult for water molecules to penetrate and for enzyme molecules to contact. The gelatinization process, through the provision of heat and water, causes starch granules to absorb water, swell, and rupture, ultimately disintegrating and releasing the internal starch molecules into the solution, forming a viscous paste. Therefore, gelatinization facilitates subsequent secondary enzymatic hydrolysis and provides a viscosity base, which is beneficial for subsequent homogenization. However, insufficient gelatinization results in starch granules not fully absorbing water, swelling, and rupturing, leaving the internal starch molecules incompletely exposed. This makes it difficult for proteases and amylases to effectively contact and hydrolyze the substrate, leading to low enzymatic hydrolysis efficiency. Excessive gelatinization, on the other hand, causes excessive starch degradation or the formation of an overly viscous gel, wasting energy and potentially increasing the system viscosity, affecting mass transfer and mixing, and inhibiting enzyme diffusion and activity. Furthermore, excessive gelatinization may lead to the heat loss of some nutrients (such as vitamins). This application achieves moderate starch gelatinization while maintaining high enzymatic hydrolysis efficiency by controlling the heating temperature and time within the aforementioned range.

[0039] In an embodiment of the present invention, in step S4, the ingredients include maltodextrin, sesame meal, fructooligosaccharides and soybean lecithin, and the mass ratio of rye flour, maltodextrin, sesame meal, fructooligosaccharides and soybean lecithin is (68~78):15:10:2:5.

[0040] Maltodextrin is a low-DE (glucose equivalent) starch hydrolysate with good flowability, solubility, and anti-caking properties. It effectively improves powder flowability and dispersibility, enhancing the processing performance of rye compound powder and facilitating storage and use. Simultaneously, as a slow-release carbohydrate, maltodextrin can regulate the glycemic index and carbohydrate structure of the product. Furthermore, as a carrier, maltodextrin helps to evenly disperse other functional ingredients (such as sesame meal and fructooligosaccharides), improving formula stability. Sesame meal is rich in high-quality plant protein, compensating for the deficiency of these amino acids in cereal proteins and improving the overall protein nutritional value. Sesame meal also contains a certain amount of insoluble dietary fiber, which helps enhance satiety and gut health. Fructooligosaccharides act as prebiotics, synergistically enhancing the "high-fiber + prebiotic" health attributes of the compound powder with the dietary fiber naturally present in rye. Soy lecithin contributes to material flowability and formability, improving processing performance and providing some nutritional value.

[0041] Adding maltodextrin, sesame meal, fructooligosaccharides, and soy lecithin to rye compound flour can not only significantly improve its nutritional density and functionality, but also effectively improve its processing performance and sensory quality, which helps to develop high-value-added health foods.

[0042] It should be noted that sesame meal needs to be added before the second enzymatic hydrolysis. The purpose is to use protease to hydrolyze the protein in sesame meal. The polypeptides generated after protein hydrolysis have better nutritional value and functional properties.

[0043] In an embodiment of the present invention, step S4 includes the following: First, add protease and hydrolyze for 1 hour at pH 6.5-7.0 and 50-55℃. Then add amylase and continue hydrolysis for 1 hour at pH 6.5-7.0 and 60-65℃.

[0044] Using protease to treat the first enzymatic hydrolysate after gelatinization breaks down large, complex proteins into smaller peptides and free amino acids, which helps improve protein digestibility and reduce allergenicity. Using α-amylase to treat the product involves a mild dextrinization process, which partially degrades starch (converting some starch into maltodextrin and resistant dextrin) but does not completely hydrolyze it (avoiding complete hydrolysis to glucose), thus retaining more oligosaccharides and maintaining low GI characteristics.

[0045] Considering that proteases and amylases have different optimal operating temperatures (proteases at lower temperatures and amylases at higher temperatures), mixed enzymatic hydrolysis is less efficient than stepwise enzymatic hydrolysis. The present invention employs a method of first using proteases at a lower temperature and then using amylases at a higher temperature, which allows for easier temperature control and higher hydrolysis efficiency.

[0046] The technical solution of this invention sets the enzymatic hydrolysis conditions within the above-mentioned range, which enables the protease and amylase to have high enzymatic activity, thereby improving the hydrolysis efficiency and yield. For example, when the gelatinized first enzymatic hydrolysis product is mixed with the protease for enzymatic hydrolysis, the pH value during hydrolysis can be 6.5, 6.8, or 7.0, and the hydrolysis temperature can be 50℃, 51℃, 52℃, 53℃, 54℃, or 55℃; when amylase is added for further enzymatic hydrolysis, the pH value during hydrolysis can be 6.5, 6.8, or 7.0, and the hydrolysis temperature can be 60℃, 61℃, 62℃, 63℃, 64℃, or 65℃.

[0047] In an embodiment of the present invention, in step S4, the amount of protease added is 50~100U / g, and the amount of amylase added is 30~60U / g.

[0048] Setting the amount of protease added to 50-100 U / g results in good enzymatic hydrolysis while controlling costs. Setting the amount of amylase added to 30-60 U / g controls the starch to undergo only mild dextrinization, converting some starch into maltodextrin and resistant dextrin, avoiding complete hydrolysis to glucose, retaining more oligosaccharides, and maintaining low GI characteristics. It should be noted that in this invention, the amount of protease added is calculated at 50-100 U / g, based on the amount of sesame meal added, using sesame meal dry basis as the standard; the amount of amylase added is calculated at 30-60 U / g, based on rye flour dry basis as the standard.

[0049] In an embodiment of the present invention, step S4 involves enzyme inactivation via high-temperature inactivation. Similarly, the reaction product solution after enzymatic hydrolysis can be heated to 90-95°C and maintained for 10-15 minutes for high-temperature enzyme inactivation. High-temperature enzyme inactivation prevents excessive degradation and ensures long-term product storage stability.

[0050] In an embodiment of the present invention, in step S5, the homogenization process is performed using a high-pressure microfluidic homogenizer. The parameters of the homogenization process include: a pressure of 120-150 MPa, a cycle count of 1-2 times, and an outlet temperature of 40-60°C. For example, during homogenization, the pressure can be 120 MPa, 130 MPa, 140 MPa, or 150 MPa; the cycle count can be 1 or 2 times; and the outlet temperature can be 40°C, 45°C, 50°C, 55°C, or 60°C. After homogenization, the rye compound powder particles are refined to submicron level (<1 μm), improving dispersibility and stability, and enhancing the powder-forming properties and reconstitution properties of subsequent spray drying. Homogenization also exposes more functional components by disrupting the starch-protein-cellulose complex.

[0051] In an embodiment of the present invention, in step S5, the parameters of the spray drying process include: centrifugal atomization, constant feed rate, inlet temperature of 160℃~180℃, and outlet temperature of 80~90℃. Exemplarily, during spray drying, the inlet temperature can be 160℃, 165℃, 170℃, 175℃, or 180℃, and the outlet temperature can be 80℃, 85℃, or 60℃. The purpose of spray drying is to rapidly dehydrate, producing free-flowing fine powder while retaining the heat-sensitive functional components.

[0052] The present invention also proposes a low glycemic index rye compound powder, which is prepared according to the preparation method described in the foregoing technical solution.

[0053] The technical solution of the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be understood that the following embodiments are only used to explain the present invention and are not intended to limit the present invention.

[0054] In the following examples and comparative examples, the rye grains, maltodextrin, soybean lecithin, sesame meal, and fructooligosaccharides were sourced from Hubei Heimaixiang Agricultural Co., Ltd. The cellulase, xylanase, lipase, flavor protease, and α-amylase were purchased from Shanghai Yuanye Biotechnology Co., Ltd.

[0055] Example 1 This embodiment provides a method for preparing low glycemic index rye compound flour, the process flow is as follows: Figure 1 As shown, the preparation method of the low glycemic index rye compound flour includes the following steps: 1) Preparation of rye flour: The clean and dried rye grains (moisture content ≤10%) are pulverized using a mechanical impact ultrafine pulverizer (dish-grading integrated) (process parameters: linear speed 120 m / s). -1 (Grading wheel at 1800 rpm, cycled 3 times) to obtain rye flour; 2) Alkali treatment: Mix rye flour and water at a mass ratio of 1:10 to form a slurry. Slowly add NaOH solution to the slurry to adjust the pH value of the slurry to 11. Then, stir the mixture at a constant temperature of 70℃ for 60 minutes with a stirring speed of 200 rpm to obtain the alkali-treated slurry. 3) Acid neutralization treatment: The pH of the alkali-treated slurry was adjusted back to 6.5 with food-grade citric acid and stirred at 65°C for 20 minutes to obtain pretreated rye slurry; 4) First enzymatic hydrolysis: The pretreated rye pulp from step 3) is mixed with the first compound enzyme (stirring speed 120 rpm), and enzymatic hydrolysis is carried out at 55℃ and pH 6.2 for 2.5 h. After hydrolysis, the liquid is heated to 85℃ and held for 10 min to obtain the first enzymatic hydrolysis product. The first compound enzyme includes 60 U / g cellulase, 120 U / g xylanase and 30 U / g lipase. 5) Heating and gelatinization: Heat the first enzymatic hydrolysis product from step 4) to 90°C and maintain for 25 minutes to gelatinize the starch portion in the first enzymatic hydrolysis product, thereby obtaining the gelatinized first enzymatic hydrolysis product; 6) Secondary enzymatic hydrolysis and addition of ingredients: Add ingredients to the gelatinized first enzymatic hydrolysis product obtained in step 5), then add protease (flavor protease, 60 U / g), and enzymatically hydrolyze for 1 h at pH 6.8 and 52℃. Then add α-amylase (50 U / g), and continue enzymatic hydrolysis for 1 h at pH 6.8 and 62℃. Raise the temperature to 90℃ and maintain it for 10 min to obtain the second enzymatic hydrolysis product. The ingredients include maltodextrin (DE 6-12), sesame meal (defatted powder, particle size ≤50μm), soybean lecithin (powder type), and fructooligosaccharides (FOS, ≥95%). The mass ratio of rye flour, maltodextrin, sesame meal, soybean lecithin, and fructooligosaccharides is 68:15:10:2:5. 7) Homogenization and spray drying: The second enzymatic hydrolysis product is subjected to homogenization (high pressure micro-jet homogenizer, pressure 120MPa, 1 cycle, outlet temperature 50℃) and spray drying (centrifugal atomization, constant feed rate, inlet temperature 170℃, outlet temperature 85℃) to obtain rye compound powder with low glycemic index.

[0056] Example 2 Compared with Example 1, the difference is that in step 1), a hammer cyclone mill is used for pulverization, and the specific parameters are shown in Table 1.

[0057] Example 3 Compared with Example 1, the difference is that in step 1), a hammer mill is used for pulverization, and a centrifugal air classifier is used to screen out fine powder after pulverization. Specific parameters are shown in Table 1.

[0058] The effects of different grinding methods and particle sizes on the quality of rye compound flour were tested. Particle size was used to evaluate the grinding effect, and SDF content was used to evaluate the quality of rye compound flour under different grinding particle sizes.

[0059] ① Particle size testing: Dry method using laser particle size analyzer; opacity 0.1-10%; spherical model used for analysis; ② SDF (soluble dietary fiber) content detection: The detection was carried out in accordance with GB / T 37492-2019 "Grain and Oil Inspection - Determination of Water-Soluble Dietary Fiber in Cereals and Their Products - Enzyme Gravimetric Method".

[0060] Table 1. Test results of particle size and SDF content in Examples 1-3

[0061] The test results in Table 1 show that the particle size has a significant impact on the SDF and free ferulic acid content in the finished rye compound flour. Using a mechanical ultrafine pulverizer to grind rye grains can significantly reduce the SDF content in the rye flour. 50When the particle size is controlled at 18μm, it reaches the ultrafine powder level, at which point the SDF content is highest.

[0062] Examples 4 to 6 Examples 4-6 provide a method for preparing low glycemic index rye compound powder. The preparation method is largely the same as that of Example 1. The only difference is that in the alkali treatment process in step 2), the alkali treatment time in Example 4 is 90 min, the alkali treatment time in Example 5 is 120 min, and the alkali treatment time in Example 6 is 30 min.

[0063] The effects of different alkali treatment times on the quality of rye compound flour were tested, and the effects of alkali treatment on the quality of rye compound flour were evaluated using SDF and free ferulic acid content.

[0064] ①The SDF content detection method is the same as described above.

[0065] ② Determination of Free Ferulic Acid Content: Weigh approximately 1.0 g of the prepared rye compound powder sample into a centrifuge tube. Add 10-20 mL of 70% methanol aqueous solution; vortex to mix, then sonicate at 40℃ for 30 min; subsequently centrifuge at 8000 rpm for 10 min, and collect the supernatant. Filter the supernatant through a 0.45 μm organic filter membrane; the filtrate can be used for HPLC analysis. Prepare ferulic acid standard working solutions of 1, 5, 10, 20, and 50 μg / mL for plotting standard curves. Detect ferulic acid using HPLC at 320 nm and plot the ferulic acid standard curve; after injecting the sample solution, input it into the standard curve to obtain the ferulic acid content in the solution, then convert it to the free ferulic acid content per 100 g of powder.

[0066] Table 2. Test results of SDF content and free ferulic acid content in Examples 1 and 4-6.

[0067] The test data in Table 2 show that, compared with the group that has not undergone alkali treatment, alkali treatment can effectively increase the content of SDF and free ferulic acid in the finished rye compound flour. The effect is best when the alkali treatment time is 60-90 min, with higher SDF and free ferulic acid content.

[0068] Examples 7 to 9 Examples 7-9 provide a method for preparing low glycemic index rye compound flour. The preparation method is largely the same as that of Example 1. The only difference is that in the homogenization process of step 7), the homogenization pressure in Example 7 is 60 MPa, the homogenization pressure in Example 8 is 90 MPa, and the homogenization pressure in Example 9 is 150 MPa.

[0069] The effects of different high-pressure microjet homogenization pressures on the quality of rye compound flour were tested. The effects of different high-pressure microjet homogenization pressures on the quality of rye compound flour were evaluated by wetting time, centrifugal sedimentation rate, storage stratification rate and cold water solubility.

[0070] Table 3. Test results of wetting time, centrifugal sedimentation rate, storage stratification rate, and cold water solubility for Examples 1 and 7-9.

[0071] The test data in Table 3 show that, compared with the group that did not undergo homogenization, high-pressure micro-jet homogenization can effectively improve the reconstitution and stability of rye compound powder. Furthermore, as the homogenization pressure increases, the centrifugal sedimentation rate, storage stratification rate, and wetting time decrease, while the cold water solubility increases.

[0072] Comparative Examples 1 to 4 Comparative Examples 1-3 each provide a method for preparing low glycemic index rye compound flour. The preparation methods are largely the same as those in Example 1. The only difference is that in the enzymatic hydrolysis process of step 4), Comparative Example 1 does not perform step 4), Comparative Example 2 uses only a single cellulase for enzymatic hydrolysis, Comparative Example 3 uses only a single xylanase for enzymatic hydrolysis, and Comparative Example 4 uses only a single lipase for enzymatic hydrolysis.

[0073] The effects of different single-stage enzymatic hydrolysis processes on the quality of rye compound flour were tested. The effects of single-stage enzymatic hydrolysis process on the quality of rye compound flour were evaluated by xylooligosaccharide content, antioxidant activity, peroxide value, acid value and cold water solubility.

[0074] ① Determination of xylooligosaccharide content: A series of standard solutions were prepared using xylose as the standard. HPLC with a differential refractive index detector and an amino column was used to plot a standard curve. Weigh 1 g (accurate to 0.001 g) of the sample into a 50 mL colorimetric tube, add 15 mL of water to dissolve, vortex to mix, sonicate for 30 min, then dilute to the mark with anhydrous ethanol, mix well, centrifuge (8000 r / min, 5 min), and collect 25.0 mL of the supernatant. Evaporate the ethanol in a boiling water bath (or concentrate under nitrogen at 70℃ to remove ethanol), redissolve in water, and transfer to a 25 mL volumetric flask and dilute to the mark. If the solution is turbid, centrifuge (8000 r / min, 5 min) and collect the supernatant as the sample solution before hydrolysis. Filter through a 0.45 μm filter membrane for analysis using HPLC. Substitute the sample solution detection value into the standard curve to determine the oligosaccharide content in the sample.

[0075] ② Antioxidant activity (DPPH scavenging rate): Detected using a kit. Take 2.0 g of sample (dry weight) and place it in a 25 mL colorimetric tube. Add 10 mL of 70% ethanol solution, shake well, and place in a boiling water bath for 30 min to gelatinize completely. Then, remove and sonicate in an ultrasonic cleaner for 30 min. Make up to 25 mL with 70% ethanol solution, centrifuge, and collect the supernatant for testing. The testing procedure is performed according to the kit instructions. Take 50 μL of sample supernatant and mix it thoroughly with 950 μL of reagent one. Measure the absorbance (A1) at 515 nm. Use the kit extract as a blank control to measure the absorbance (A0). The DPPH scavenging rate is calculated using the following formula:

[0076] ③ Peroxide value: Tested according to the method in GB 5009.227-2023 "National Food Safety Standard - Determination of Peroxide Value in Food".

[0077] ④ Acid value: Tested according to the method in GB 5009.229-2025 "National Food Safety Standard - Determination of Acid Value in Food".

[0078] ⑤ Cold water solubility: Take 1g of sample and prepare a 1% suspension with 100mL of distilled water. Stir at room temperature for 30min, then centrifuge at 4000r / min for 15min. After centrifugation, take 25mL of the supernatant and dry it in a 105℃ oven. Weigh the mass of the dried sample. The solubility of starch is calculated using the following formula: Solubility (%) = (mass of dried sample × 4 / mass of dried sample) × 100.

[0079] Table 4. Test results of xylooligosaccharide content, antioxidant activity, peroxide value, acid value, and cold water solubility in Examples 1 and Comparative Examples 1-4.

[0080] Table 4 shows that without a single enzymatic hydrolysis (Comparative Example 1), the results for xylooligosaccharide content, antioxidant activity, peroxide value, acid value, and cold water solubility of the rye compound flour all deteriorate. Table 4 also shows that the test results of Example 1 are superior to those of Comparative Examples 2-4, indicating that the synergistic effect of the compound enzyme is far superior to that of a single enzyme. Compound enzymatic hydrolysis can effectively increase the xylooligosaccharide content and antioxidant activity in rye compound flour, while also inhibiting oxidative rancidity and improving solubility in cold water.

[0081] Comparative Examples 5 to 7 Comparative Examples 5-7 each provide a method for preparing low glycemic index rye compound flour. The preparation methods are largely the same as those in Example 1. The only difference is that in the secondary enzymatic hydrolysis process of step 6), Comparative Example 5 does not perform step 6), Comparative Example 6 uses only a single flavor protease for enzymatic hydrolysis, and Comparative Example 7 uses only a single α-amylase for enzymatic hydrolysis.

[0082] The effects of different secondary enzymatic hydrolysis processes on the quality of rye compound flour were tested. Protein digestibility, nitrogen solubility, resistant starch content, and GI value were used to evaluate the effects of secondary enzymatic hydrolysis processes on the quality of rye compound flour.

[0083] ① Protein in vitro digestibility determination: Weigh 1.000g of rye compound powder (passed through an 80-mesh sieve to ensure uniformity), place it in a 50mL centrifuge tube, add 20mL of pH 2.0 hydrochloric acid-pepsin solution (pepsin activity 1:10000, enzyme amount is 1% of the total protein mass of the sample); then place the centrifuge tube in a 37℃ constant temperature water bath shaker, shake at 150rpm for 2h, during which the pH is adjusted to 2.0 with 1mol / L HCl every 30min to maintain the optimal environment for pepsin; after digestion, adjust the pH to 7.5 with 1mol / L NaOH, add 20mL of pH 7.5 phosphate buffer-trypsin solution (trypsin activity 1:250, enzyme amount is 1% of the total protein mass of the sample), continue digestion at 37℃ and 150rpm for 4h; add 10mL of 10% trichloroacetic acid (TCA) solution to terminate the enzymatic reaction, centrifuge at 4000rpm for 15min, and collect the supernatant; use the Kjeldahl nitrogen determination method (GB (5009.5-2016) Determine the "digestible protein content in the supernatant" and the "total protein content of the sample" respectively; calculate the in vitro digestibility of protein according to the following formula: in vitro digestibility of protein = (digestible protein content / total protein content of the sample) × 100%.

[0084] ② Nitrogen solubility: Weigh 2.000g of rye compound powder and place it in a 100mL centrifuge tube. Add 50mL of 25℃ ultrapure water and stir magnetically for 30min (300rpm) to fully dissolve the protein. Centrifuge at 4000rpm for 15min and transfer the supernatant to a 50mL volumetric flask. Wash the centrifuge tube residue twice with a small amount of ultrapure water and add the washing liquid to the volumetric flask. Make up to 50mL. Take 10mL of the supernatant after making up to 50mL and determine the "nitrogen content of the supernatant" using the Kjeldahl method. At the same time, take 0.500g of the original sample and determine the "total nitrogen content of the sample". Calculate the nitrogen solubility using the following formula: Nitrogen solubility = (nitrogen content of the supernatant × 50 / 10) / (total nitrogen content of the sample) × 100%. Where 50 / 10 is the volume adjustment factor of the supernatant.

[0085] ③ Resistant starch content: Weigh 1.000g of rye compound powder and place it in a 50mL centrifuge tube. Add 40mL of pH 6.0 phosphate buffer and 5mL of pancreatic α-amylase solution (300U / mL). Incubate at 37℃ in a water bath at 160rpm for 16h to hydrolyze digestible starch (converting it to maltose). Add 80mL of anhydrous ethanol (95% v / v) and let stand at 4℃ for 1h to allow resistant starch to precipitate completely. Centrifuge at 4000rpm for 15min, discard the supernatant (containing digestible starch hydrolysis products), and retain the precipitate at the bottom of the tube. Wash the precipitate three times with 80% ethanol solution (20mL each time) to remove residual maltose. Transfer the precipitate to a 100mL Erlenmeyer flask, add 10mL of 2mol / L KOH solution, and stir magnetically in an ice bath for 30min (to dissolve the resistant starch). Use 1mol / L... Adjust the pH to 4.5 with HCl, add 5 mL of saccharifying enzyme solution (1000 U / mL), and shake in a 50°C water bath for 30 min to hydrolyze the resistant starch into glucose. The glucose concentration in the hydrolysate is determined using the glucose oxidase-peroxidase (GOD-POD) method. The resistant starch content is calculated using the following formula: resistant starch content = (glucose mass × 0.9 / sample mass) × 100%; where 0.9 in the formula is the conversion factor for glucose to starch.

[0086] ④ In vitro glycemic index (GI) determination: Weigh 2.000g of rye complex powder (calculated as carbohydrates), place it in a 100mL Erlenmeyer flask, and add 50mL of pH 5000ml. 5.2 Acetate buffer was mixed with 10 mL of α-amylase solution (100 U / mL) and shaken in a 37°C water bath for 30 min (simulating preliminary digestion in the mouth and stomach); 5 mL of saccharifying enzyme solution (1000 U / mL) was added and shaken again at 37°C for 120 min (simulating small intestinal digestion). 5 mL samples were taken at 0 min, 30 min, 60 min, 90 min, and 120 min, centrifuged at 4000 rpm for 10 min, and the supernatant was collected. The glucose concentration of the supernatant at each time point was determined using the GOD-POD method, and a "glucose release curve" was plotted. Using white bread (2.000 g) as a reference (GI=100), the "area under the glucose release curve (AUC)" for both the sample and white bread was calculated. The in vitro GI value was calculated using the following formula: In vitro GI value = (sample AUC / white bread AUC) × 100.

[0087] Table 5. Results of protein digestibility, nitrogen solubility, resistant starch content, and GI value tests for Examples 1 and Comparative Examples 5-7.

[0088] Table 5 shows that performing only one enzymatic hydrolysis (Comparative Example 5) without secondary enzymatic hydrolysis results in poorer test results for protein digestibility, nitrogen solubility, resistant starch content, and GI value of the rye compound flour. Table 5 also shows that the test results of Example 1 are better than those of Comparative Examples 6-7, indicating that the synergistic effect of the compound enzyme is superior to that of a single enzyme during the secondary enzymatic hydrolysis process. Compound enzymatic hydrolysis can effectively improve the digestibility of protein in rye compound flour, increase the soluble protein content, increase the resistant starch content, and reduce the GI value of the product.

[0089] Comparative Examples 8 to 9 Comparative Examples 8 and 9 respectively provide a method for preparing low glycemic index rye compound flour. The preparation method is largely the same as that of Example 1. The only difference is that in the addition process of step 6), Comparative Example 8 does not add defatted sesame meal (mass ratio, rye flour: maltodextrin: soybean lecithin: fructooligosaccharide = 78:15:2:5), and Comparative Example 9 does not add fructooligosaccharide (mass ratio, rye ultrafine flour: maltodextrin: soybean lecithin: sesame meal = 73:15:2:10).

[0090] The effects of different ingredient compositions on the quality of rye compound flour were tested. The effects of each formulation were evaluated using protein content, SDF content, cold water solubility, DPPH scavenging rate, resistant starch content, and GI value.

[0091] Protein content was determined using the method described in GB 5009.5-2025, "National Food Safety Standard - Determination of Protein in Food". The methods for testing SDF content, cold water solubility, DPPH scavenging rate, resistant starch content, and GI value were the same as those described above.

[0092] Table 6. Results of protein content, SDF content, and cold water solubility tests for Examples 1 and Comparative Examples 8-9.

[0093] Table 7. Test results of DPPH scavenging rate, resistant starch content, and GI value for Example 1 and Comparative Examples 8-9.

[0094] Based on the test data in Tables 6 and 7, it can be seen that the addition of defatted sesame meal and fructooligosaccharides has a significant impact on SDF, resistant starch and GI value. The compound formula with the addition of maltodextrin, soybean lecithin, fructooligosaccharides and sesame meal is more beneficial for controlling postprandial blood glucose.

[0095] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for preparing a low glycemic index rye compound flour, characterized in that, Includes the following steps: S1. Rye flour and water are mixed to form a slurry, and then the slurry is subjected to alkali treatment and acid neutralization treatment in sequence to obtain pretreated rye slurry. S2. The pretreated rye pulp is mixed with the first complex enzyme and subjected to one enzymatic hydrolysis. After enzyme inactivation treatment, the first enzymatic hydrolysis product is obtained. The first complex enzyme includes cellulase, xylanase and lipase. S3. Heat the first enzymatic hydrolysis product to gelatinize the starch portion of the first enzymatic hydrolysis product, and obtain the gelatinized first enzymatic hydrolysis product. S4. The gelatinized first enzymatic hydrolysis product and the ingredients are mixed, and then a second complex enzyme is added for secondary enzymatic hydrolysis. After enzyme inactivation treatment, the second enzymatic hydrolysis product is obtained; wherein, the second complex enzyme includes protease and amylase. S5. The second enzymatic hydrolysis product is subjected to homogenization and spray drying in sequence to obtain rye compound powder with low glycemic index.

2. The method for preparing low glycemic index rye compound flour as described in claim 1, characterized in that, In step S1, the method for preparing the rye flour includes: pulverizing rye grains; wherein the pulverizing process includes one of the following methods: (a) Grinding process using a hammer mill; (b) Use a mechanical impact ultrafine pulverizer for pulverization.

3. The method for preparing low glycemic index rye compound flour as described in claim 1, characterized in that, In step S1: The step of mixing rye flour and water to form a slurry includes: mixing rye flour and water at a mass ratio of 1:(10~12), stirring at 25~30℃ for 20~30 minutes to obtain the slurry; and / or, The pH value of the alkali treatment is 10.5~11.5, the temperature of the alkali treatment is 65~70℃, and the time of the alkali treatment is 60~90 min; and / or, The acid neutralization treatment is performed using citric acid, with a pH value of 6.0-6.5, a temperature of 65-70°C, and a duration of 15-20 minutes.

4. The method for preparing low glycemic index rye compound flour as described in claim 1, characterized in that, In step S2: The pH value of the first enzymatic hydrolysis is 6.0~6.5, the temperature of the first enzymatic hydrolysis is 50~55℃, and the time of the first enzymatic hydrolysis is 2~3 hours; and / or, The amount of cellulase added is 50-100 U / g, the amount of xylanase added is 100-200 U / g, and the amount of lipase added is 20-50 U / g.

5. The method for preparing low glycemic index rye compound flour as described in claim 1, characterized in that, In step S3, when heating the first enzymatic hydrolysis product, the heating temperature is 85~95℃ and the heating time is 20~30min.

6. The method for preparing low glycemic index rye compound flour as described in claim 1, characterized in that, In step S4, the ingredients include maltodextrin, sesame meal, fructooligosaccharides and soybean lecithin, and the mass ratio of rye flour, maltodextrin, sesame meal, fructooligosaccharides and soybean lecithin is (68~78):15:10:2:

5.

7. The method for preparing low glycemic index rye compound flour as described in claim 1, characterized in that, In step S4, the secondary enzymatic hydrolysis includes: First, add protease and hydrolyze for 1 hour at pH 6.5-7.0 and 50-55℃. Then, add amylase and continue hydrolyzing for 1 hour at pH 6.5-7.0 and 60-65℃.

8. The method for preparing low glycemic index rye compound flour as described in claim 7, characterized in that, The amount of protease added is 50~100U / g, and the amount of amylase added is 30~60U / g.

9. The method for preparing low glycemic index rye compound flour as described in claim 1, characterized in that, In step S5: The homogenization process is performed using a high-pressure microfluidic homogenizer, and the parameters of the homogenization process include: pressure of 120~150 MPa, number of cycles of 1~2, and outlet temperature of 40~60℃; and / or, The parameters of the spray drying process include: centrifugal atomization, constant feed rate, inlet temperature of 160~180℃, and outlet temperature of 80~90℃.

10. A low glycemic index rye compound flour, characterized in that, The low glycemic index rye compound flour It is prepared according to any one of claims 1 to 9.

Images