Soluble high-fiber sorghum flour and preparation method thereof

Abstract

The invention discloses soluble high-fiber sorghum flour and a preparation method thereof. The method comprises the following steps: soaking unhulled sorghum serving as a raw material in salt water to soften fibers; grinding, mixing with defatted soybean powder, and carrying out directional enzymolysis by using a compound enzyme, so that the content of starch is reduced, a fermentation carbon source is provided, and meanwhile, a lignin network is cracked to improve the dispersity and flavor; then bacillus licheniformis is inoculated for fermentation, fibers are softened by utilizing acid produced by metabolism of the bacillus licheniformis, protein and phytic acid are hydrolyzed by producing enzyme, and the solubility and flavor are remarkably improved; then fruit fibers are added, a fiber crystal structure is destroyed through homogenization, an emulsified network is formed, and the taste and the fineness are optimized; and finally, carrying out spray drying and fluidized bed granulation processes to obtain a finished product with excellent flowability, instant solubility and high fiber retention rate. While the dietary fiber nutrition of the whole sorghum grains is reserved to the maximum extent, the brewing property and sensory quality of the whole sorghum grains are effectively improved, and the market acceptability of the whole sorghum grains is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of deep processing of agricultural products, and particularly relates to a high-fiber high-solubility sorghum powder and a preparation method thereof. BACKGROUND

[0002] The problem of diabetes is becoming increasingly serious worldwide. Diabetes and its complications have a serious impact on the health of patients, and also bring a heavy burden to the social economy. One of the main reasons for diabetes is excessive intake of carbohydrates (sugar) in the diet. Long-term excessive intake of carbohydrates leads to impaired islet function and abnormally high blood sugar.

[0003] In the current era of increasing emphasis on healthy eating, consumers' demand for food has gradually shifted from simply being full to being nutritious, healthy, and functional. As the "seventh nutrient", dietary fiber plays a key role in maintaining intestinal health and preventing chronic diseases, and its market demand is increasing. People's healthy diet is more inclined to be low in sugar, high in fiber, and high in protein.

[0004] Sorghum, as an ancient and widely cultivated grain, plays an important role in the global food system. It is not only high in yield, but also rich in dietary fiber, making it an excellent raw material for developing high-fiber foods. However, traditional sorghum flour has certain limitations in terms of taste, solubility, and digestive properties, which limits its widespread application in the healthy food industry. Therefore, the development of a high-fiber sorghum powder based on sorghum, through the compounding of other raw materials and the use of advanced processing techniques, can improve its taste, solubility, and reduce the GI value after digestion. This not only meets the urgent needs of people for healthy food, but also has great market potential and economic benefits, and is of great significance to the development of the grain deep processing industry. SUMMARY

[0005] The technical problem to be solved is that in sorghum processing, if the hull is not removed, more cellulose can be retained, resulting in higher fiber content in the sorghum powder. However, the solubility and taste of the powder without hull removal will be worse, and although the high-fiber content goal is achieved, the acceptance of people is lower. The present application improves the taste and solubility of sorghum powder by first soaking the fiber in salt water and then using enzyme and fermentation processes without removing the hull. The taste and flavor of the sorghum powder are further improved through compounding and granulation, solving the problem of dry and bitter taste of traditional coarse grains and high-fiber foods.

[0006] Technical solution: A method for preparing a high-fiber sorghum powder with high solubility, comprising the following steps: S1. Remove impurities from the sorghum particles, soak them in salt water, rinse them out with clean water, then mix them with water and grind them at low speed, and then grind them at high speed to obtain a slurry; S2. Add defatted soybean flour to the slurry, adjust the pH value, add compound enzyme and stir evenly, sonicate at constant temperature, and end the enzymatic hydrolysis by heating. S3. Adjust the pH of the enzymatically hydrolyzed slurry, inoculate it with activated Bacillus licheniformis bacterial solution, transfer it to a fermentation tank for fermentation, and sterilize and cool it after the fermentation is completed; S4. Mix the pulp and fruit fiber, add water and stir to adjust the solid content of the pulp, homogenize and spray dry, and sieve to obtain sorghum fine powder; S5. The fine sorghum powder is granulated by fluidized bed to obtain easily soluble high-fiber sorghum powder.

[0007] Furthermore, in S1, the concentration of the brine is 1-3 wt.%; the mass ratio of sorghum to brine is 1:(2-4); the soaking temperature is 30-45℃, and the soaking time is 12-36h; the mass ratio of sorghum to water is 1:(1-2); the low-speed grinding speed is 15000-18000 rpm, and the time is 1-3min; the high-speed grinding speed is 20000-25000 rpm, and the time is 2-5min.

[0008] Furthermore, in S2, the mass ratio of slurry to defatted soybean flour is (20-30):1; the pH value is adjusted to 4.5-5.5; the complex enzymes include laccase, lignin peroxidase, α-amylase, β-amylase, isoamylase, and maltase; the constant temperature ultrasound temperature is 40-55℃, the ultrasound power is 200-300W, and the time is 2-3h; the heating temperature is 85-95℃, and the duration is 15-20min.

[0009] Furthermore, the enzyme activities of laccase, lignin peroxidase, α-amylase, β-amylase, isoamylase, and maltase in the slurry are 15-20 U / g, 15-20 U / g, 15-20 U / g, 100-200 U / g, 80-200 U / g, and 20-50 U / g, respectively.

[0010] Furthermore, in step S3, the pH is adjusted to 6.5-7.5; the inoculation amount is 5-10 wt.% of the slurry; and the concentration of the Bacillus licheniformis bacterial solution is 1×10⁻⁶. 8 -1×10 9 CFU / mL; fermentation temperature 35-37℃, fermentation time 24-36h, fermentation stirring speed 200-300 rpm, fermentation aeration rate 0.6-1.0L / (L·min); sterilization temperature 121℃, time 15-20min.

[0011] Furthermore, the fermentation temperature is 37°C, the fermentation time is 36 hours, and the fermentation aeration rate is 0.8 L / (L·min).

[0012] 7. The method for preparing easily soluble high-fiber sorghum flour according to claim 1, characterized in that: the mass ratio of slurry to fruit fiber in S4 is (40-50):1; the solid content is 10-20 wt.%; and the homogenization pressure is 25-35 MPa.

[0013] Furthermore, the fluidized bed granulation conditions in S5 are as follows: 5-8 wt.% of hydroxypropyl methylcellulose is atomized and sprayed in at an atomization pressure of 0.3-0.5 MPa, forming particles with a diameter of 100-200 μm.

[0014] The preparation method described above yields an easily soluble, high-fiber sorghum powder.

[0015] The above describes the application of an easily soluble, high-fiber sorghum flour in solid beverages, premixed powders, meal replacement powders, pasta, baking, and functional foods. Beneficial effects

[0016] This invention involves processing sorghum without removing the husk, thus preserving dietary fibers such as cellulose and hemicellulose to the maximum extent, resulting in a product with higher fiber content, in line with the trend of whole grain health. Through the action of amylase and ligninase, while reducing the content of sugars such as starch and generating flavor substances, it selectively cleaves the cross-linked structure of lignin, reducing the insolubility of fiber, improving water dispersibility, and alleviating the rough and astringent taste, making the high-fiber powder more acceptable.

[0017] This invention employs Bacillus licheniformis fermentation, which utilizes the sugars produced by enzymatic hydrolysis of sorghum flour and the abundant proteins in soybean flour to produce metabolites such as lactic acid. This improves the solubility and mouthfeel of sorghum flour, enriches the product flavor, and strictly controls the fermentation conditions to prevent the consumption of small molecule sugars such as monosaccharides produced by enzymatic hydrolysis. Bacillus licheniformis utilizes cellulose to ensure a high cellulose content in the product while achieving a low GI value.

[0018] This invention employs a combined enzymatic hydrolysis and fermentation process, simultaneously achieving the goals of improving taste, enhancing flavor, and increasing fiber content. Further homogenization ensures a more uniform distribution of protein, starch, and fiber particles, forming a stable colloidal system. This prevents clumping of the product after spray drying and imparts a smoother, paste-like texture to the final product. Through protein addition and mechanical action, the solubility of the powder in water is improved, resulting in a smooth, grain-free texture suitable for preparing beverages or as a food ingredient.

[0019] This invention adds fruit fiber, which not only increases fiber content and abundance, but also adds natural fruit aroma and antioxidants, enhancing flavor and health benefits. In addition, it contains pectin, which can improve the water-holding capacity of powder and improve its quality in subsequent food processing.

[0020] This invention obtains fine powder through spray drying, ensuring uniform composition and drying efficiency; then the fine powder is combined with atomized hydroxypropyl methylcellulose (HPMC) binder to form larger, porous particles, which significantly improves solubility.

[0021] This invention uses sorghum as the main raw material, retaining its fiber and nutrients, and adds soybean flour, which not only supplements high-quality plant protein, but also uses its protein and lecithin to improve the dispersibility and taste of the system. Attached Figure Description

[0022] Figure 1 This is a graph showing the GI values ​​of high-fiber sorghum flour prepared in Example 1 and Comparative Examples 1-8, as determined by animal experiments. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments. The following embodiments are illustrative of the present invention, but the present invention is not limited to the following embodiments: Example 1

[0024] A method for preparing easily soluble high-fiber sorghum flour includes the following steps: S1. Remove impurities from 1000g of sorghum grains, soak them in 2000g of 2wt.% salt water at 30℃ for 24 hours, then rinse them with clean water, mix them with 1000g of water, grind them at 15000 rpm for 2 minutes, and then grind them at 25000 rpm for 3 minutes to obtain a slurry. S2. Add 100g of defatted soybean flour to the slurry, adjust the pH to 5.0, add laccase, lignin peroxidase, α-amylase, β-amylase, isoamylase and maltase and stir evenly. The activities of each enzyme reach 20U / g, 15U / g, 20U / g, 100U / g, 80U / g and 20U / g respectively. Under 45℃, sonicate at 200W for 2h, and then heat to 95℃ for 15min to end the enzymatic hydrolysis. S3. Adjust the pH of the enzymatically hydrolyzed slurry to 7.0, and inoculate with 105g of activated 1×10⁻⁶ mol / L slurry. 8 CFU / mL Bacillus licheniformis culture was transferred to a fermenter, stirred at 200 rpm, aerated at 0.6 L / (L·min), fermented at 37℃ for 36 h, and then sterilized at 121℃ for 15 min and cooled. S4. Mix 2000g of slurry and 50g of fruit fiber, add water and stir to adjust the solid content of the slurry to 20wt.%, homogenize at 30MPa and spray dry, then pass through a 100-mesh sieve to obtain sorghum fine powder; S5. The fine sorghum powder is passed through a fluidized bed, and 5 wt.% of hydroxypropyl methylcellulose is atomized and sprayed in at an atomization pressure of 0.5 MPa to granulate into particles with a particle size of 100-200 μm, thus obtaining easily soluble high-fiber sorghum powder. Example 2

[0025] A method for preparing easily soluble high-fiber sorghum flour includes the following steps: S1. Remove impurities from 1000g of sorghum grains, soak them in 2000g of 2wt.% salt water at 30℃ for 24 hours, then rinse them with clean water, mix them with 2000g of water, grind them at 15000 rpm for 2 minutes, and then grind them at 25000 rpm for 3 minutes to obtain a slurry. S2. Add 100g of defatted soybean flour to the slurry, adjust the pH to 5.0, add laccase, lignin peroxidase, α-amylase, β-amylase, isoamylase and maltase and stir evenly. The activities of each enzyme reach 20U / g, 15U / g, 20U / g, 100U / g, 80U / g and 20U / g respectively. Under 45℃, sonicate at 200W for 2h, and then heat to 95℃ for 15min to end the enzymatic hydrolysis. S3. Adjust the pH of the enzymatically hydrolyzed slurry to 7.0, and inoculate with 155g of activated 1×10⁻⁶ mol / L slurry. 8 CFU / mL Bacillus licheniformis culture was transferred to a fermenter, stirred at 200 rpm, aerated at 0.6 L / (L·min), fermented at 37℃ for 36 h, and then sterilized at 121℃ for 15 min and cooled. S4. Mix 2000g of slurry and 50g of fruit fiber, add water and stir to adjust the solid content of the slurry to 20wt.%, homogenize at 30MPa and spray dry, then pass through a 100-mesh sieve to obtain sorghum fine powder; S5. The fine sorghum powder is passed through a fluidized bed, and 5 wt.% of hydroxypropyl methylcellulose is atomized and sprayed in at an atomization pressure of 0.5 MPa to granulate into particles with a particle size of 100-200 μm, thus obtaining easily soluble high-fiber sorghum powder. Example 3

[0026] A method for preparing easily soluble high-fiber sorghum flour includes the following steps: S1. Remove impurities from 1000g of sorghum grains, soak them in 2000g of 2wt.% salt water at 30℃ for 24 hours, then rinse them with clean water, mix them with 1000g of water, grind them at 15000 rpm for 2 minutes, and then grind them at 25000 rpm for 3 minutes to obtain a slurry. S2. Add 100g of defatted soybean flour to the slurry, adjust the pH to 5.0, add laccase, lignin peroxidase, α-amylase, β-amylase, isoamylase and maltase and stir evenly. The activities of each enzyme reach 20U / g, 15U / g, 20U / g, 100U / g, 80U / g and 20U / g respectively. Under 45℃, sonicate at 200W for 2h, and then heat to 95℃ for 15min to end the enzymatic hydrolysis. S3. Adjust the pH of the enzymatically hydrolyzed slurry to 7.0, and inoculate with 210g of activated 1×10⁻⁶ mol / L slurry. 8 CFU / mL Bacillus licheniformis culture was transferred to a fermenter, stirred at 200 rpm, aerated at 0.6 L / (L·min), fermented at 37℃ for 36 h, and then sterilized at 121℃ for 15 min and cooled. S4. Mix 2000g of slurry and 50g of fruit fiber, add water and stir to adjust the solid content of the slurry to 20wt.%, homogenize at 30MPa and spray dry, then pass through a 100-mesh sieve to obtain sorghum fine powder; S5. The fine sorghum powder is passed through a fluidized bed, and 5 wt.% of hydroxypropyl methylcellulose is atomized and sprayed in at an atomization pressure of 0.5 MPa to granulate into particles with a particle size of 100-200 μm, thus obtaining easily soluble high-fiber sorghum powder. Example 4

[0027] A method for preparing easily soluble high-fiber sorghum flour includes the following steps: S1. Remove impurities from 1000g of sorghum grains, soak them in 2000g of 2wt.% salt water at 30℃ for 24 hours, then rinse them with clean water, mix them with 1000g of water, grind them at 15000 rpm for 2 minutes, and then grind them at 25000 rpm for 3 minutes to obtain a slurry. S2. Add 100g of defatted soybean flour to the slurry, adjust the pH to 5.0, add laccase, lignin peroxidase, α-amylase, β-amylase, isoamylase and maltase and stir evenly. The activities of each enzyme reach 20U / g, 15U / g, 20U / g, 100U / g, 80U / g and 20U / g respectively. Under 45℃, sonicate at 200W for 2h, and then heat to 95℃ for 15min to end the enzymatic hydrolysis. S3. Adjust the pH of the enzymatically hydrolyzed slurry to 7.0, and inoculate with 105g of activated 1×10⁻⁶ mol / L slurry. 8 CFU / mL Bacillus licheniformis culture was transferred to a fermenter, stirred at 200 rpm, aerated at 0.6 L / (L·min), fermented at 37℃ for 24 h, and then sterilized at 121℃ for 15 min and cooled. S4. Mix 2000g of slurry and 50g of fruit fiber, add water and stir to adjust the solid content of the slurry to 20wt.%, homogenize at 30MPa and spray dry, then pass through a 100-mesh sieve to obtain sorghum fine powder; S5. The fine sorghum powder is passed through a fluidized bed, and 5 wt.% of hydroxypropyl methylcellulose is atomized and sprayed in at an atomization pressure of 0.5 MPa to granulate into particles with a particle size of 100-200 μm, thus obtaining easily soluble high-fiber sorghum powder. Example 5

[0028] A method for preparing easily soluble high-fiber sorghum flour includes the following steps: S1. Remove impurities from 1000g of sorghum grains, soak them in 2000g of 2wt.% salt water at 30℃ for 24 hours, then rinse them with clean water, mix them with 1000g of water, grind them at 15000 rpm for 2 minutes, and then grind them at 25000 rpm for 3 minutes to obtain a slurry. S2. Add 100g of defatted soybean flour to the slurry, adjust the pH to 5.0, add laccase, lignin peroxidase, α-amylase, β-amylase, isoamylase and maltase and stir evenly. The activities of each enzyme reach 20U / g, 15U / g, 20U / g, 100U / g, 80U / g and 20U / g respectively. Under 45℃, sonicate at 200W for 2h, and then heat to 95℃ for 15min to end the enzymatic hydrolysis. S3. Adjust the pH of the enzymatically hydrolyzed slurry to 7.0, and inoculate with 105g of activated 1×10⁻⁶ mol / L slurry. 8 CFU / mL Bacillus licheniformis culture was transferred to a fermenter, stirred at 200 rpm, aerated at 0.6 L / (L·min), fermented at 37℃ for 36 h, and then sterilized at 121℃ for 15 min and cooled. S4. Mix 2000g of slurry and 50g of fruit fiber, add water and stir to adjust the solid content of the slurry to 20wt.%, homogenize at 30MPa and spray dry, then pass through a 100-mesh sieve to obtain sorghum fine powder; S5. The fine sorghum powder is passed through a fluidized bed, and 8 wt.% of hydroxypropyl methylcellulose is atomized and sprayed in at an atomization pressure of 0.5 MPa to granulate the powder into particles with a diameter of 100-200 μm, thus obtaining easily soluble high-fiber sorghum powder. Example 6

[0029] A method for preparing easily soluble high-fiber sorghum flour includes the following steps: S1. Remove impurities from 1000g of sorghum grains, soak them in 2000g of 2wt.% salt water at 30℃ for 24 hours, then rinse them with clean water, mix them with 1000g of water, grind them at 15000 rpm for 2 minutes, and then grind them at 25000 rpm for 3 minutes to obtain a slurry. S2. Add 100g of defatted soybean flour to the slurry, adjust the pH to 5.0, add laccase, lignin peroxidase, α-amylase, β-amylase, isoamylase and maltase and stir evenly. The activities of each enzyme reach 20U / g, 15U / g, 20U / g, 100U / g, 80U / g and 20U / g respectively. Under 45℃, sonicate at 200W for 2h, and then heat to 95℃ for 15min to end the enzymatic hydrolysis. S3. Adjust the pH of the enzymatically hydrolyzed slurry to 7.0, and inoculate with 105g of activated 1×10⁻⁶ mol / L slurry. 8 CFU / mL Bacillus licheniformis culture was transferred to a fermenter, stirred at 200 rpm, aerated at 0.6 L / (L·min), fermented at 37℃ for 36 h, and then sterilized at 121℃ for 15 min and cooled. S4. Mix 2000g of slurry and 40g of fruit fiber, add water and stir to adjust the solid content of the slurry to 20wt.%, homogenize at 30MPa and spray dry, and pass through a 100-mesh sieve to obtain sorghum fine powder; S5. The fine sorghum powder is passed through a fluidized bed, and 5 wt.% of hydroxypropyl methylcellulose is atomized and sprayed in at an atomization pressure of 0.5 MPa to granulate into particles with a particle size of 100-200 μm, thus obtaining easily soluble high-fiber sorghum powder. Example 7

[0030] A method for preparing easily soluble high-fiber sorghum flour includes the following steps: S1. Remove impurities from 1000g of sorghum grains, soak them in 2000g of 2wt.% salt water at 30℃ for 24 hours, then rinse them with clean water, mix them with 1000g of water, grind them at 15000 rpm for 2 minutes, and then grind them at 25000 rpm for 3 minutes to obtain a slurry. S2. Add 100g of defatted soybean flour to the slurry, adjust the pH to 5.0, add laccase, lignin peroxidase, α-amylase, β-amylase, isoamylase and maltase and stir evenly. The activities of each enzyme reach 20U / g, 15U / g, 20U / g, 100U / g, 80U / g and 20U / g respectively. Under 45℃, sonicate at 200W for 2h, and then heat to 95℃ for 15min to end the enzymatic hydrolysis. S3. Adjust the pH of the enzymatically hydrolyzed slurry to 7.0, and inoculate with 105g of activated 1×10⁻⁶ mol / L slurry. 8CFU / mL Bacillus licheniformis culture was transferred to a fermenter, stirred at 200 rpm, aerated at 0.6 L / (L·min), fermented at 37℃ for 36 h, and then sterilized at 121℃ for 15 min and cooled. S4. Mix 2000g of slurry and 50g of fruit fiber, add water and stir to adjust the solid content of the slurry to 10wt.%, homogenize at 30MPa and spray dry, then pass through a 100-mesh sieve to obtain sorghum fine powder; S5. The fine sorghum powder is passed through a fluidized bed, and 5 wt.% of hydroxypropyl methylcellulose is atomized and sprayed in at an atomization pressure of 0.5 MPa to granulate into particles with a particle size of 100-200 μm, thus obtaining easily soluble high-fiber sorghum powder. Comparative Example 1

[0031] The difference between this comparative example and Example 1 is that it is not soaked in salt water, as detailed below: S1. Remove impurities from 1000g of sorghum grains, rinse with clean water, mix with 1000g of water, grind at low speed of 15000 rpm for 2 minutes, and then grind at high speed of 25000 rpm to obtain a slurry for 3 minutes; S2. Add 100g of defatted soybean flour to the slurry, adjust the pH to 5.0, add laccase, lignin peroxidase, α-amylase, β-amylase, isoamylase and maltase and stir evenly. The activities of each enzyme reach 20U / g, 15U / g, 20U / g, 100U / g, 80U / g and 20U / g respectively. Under 45℃, sonicate at 200W for 2h, and then heat to 95℃ for 15min to end the enzymatic hydrolysis. S3. Adjust the pH of the enzymatically hydrolyzed slurry to 7.0, and inoculate with 105g of activated 1×10⁻⁶ mol / L slurry. 8 CFU / mL Bacillus licheniformis culture was transferred to a fermenter, stirred at 200 rpm, aerated at 0.6 L / (L·min), fermented at 37℃ for 36 h, and then sterilized at 121℃ for 15 min and cooled. S4. Mix 2000g of slurry and 50g of fruit fiber, add water and stir to adjust the solid content of the slurry to 20wt.%, homogenize at 30MPa and spray dry, then pass through a 100-mesh sieve to obtain sorghum fine powder; S5. The fine sorghum powder is passed through a fluidized bed, and 5 wt.% of hydroxypropyl methylcellulose is atomized and sprayed in at an atomization pressure of 0.5 MPa to granulate into particles with a particle size of 100-200 μm, thus obtaining easily soluble high-fiber sorghum powder. Comparative Example 2 The difference between this comparative example and Example 1 is that enzymatic hydrolysis is not performed, as detailed below:

[0032] S1. Remove impurities from 1000g of sorghum grains, soak them in 2000g of 2wt.% salt water at 30℃ for 24 hours, then rinse them with clean water, mix them with 1000g of water, grind them at 15000 rpm for 2 minutes, and then grind them at 25000 rpm for 3 minutes to obtain a slurry. S2. Add 100g of defatted soybean flour to the slurry, adjust the pH to 7.0, and inoculate with 105g of activated 1×10 8 CFU / mL Bacillus licheniformis culture was transferred to a fermenter, stirred at 200 rpm, aerated at 0.6 L / (L·min), fermented at 37℃ for 36 h, and then sterilized at 121℃ for 15 min and cooled. S3. Mix 2000g of slurry and 50g of fruit fiber, add water and stir to adjust the solid content of the slurry to 20wt.%, homogenize at 30MPa and spray dry, and pass through a 100-mesh sieve to obtain sorghum fine powder; S4. The fine sorghum powder is passed through a fluidized bed, and 5 wt.% of hydroxypropyl methylcellulose is atomized and sprayed in at an atomization pressure of 0.5 MPa to granulate the powder into particles with a diameter of 100-200 μm, thus obtaining easily soluble high-fiber sorghum powder. Comparative Example 3

[0033] The difference between this comparative example and Example 1 is that laccase and lignin peroxidase are not added, as detailed below: S1. Remove impurities from 1000g of sorghum grains, soak them in 2000g of 2wt.% salt water at 30℃ for 24 hours, then rinse them with clean water, mix them with 1000g of water, grind them at 15000 rpm for 2 minutes, and then grind them at 25000 rpm for 3 minutes to obtain a slurry. S2. Add 100g of defatted soybean flour to the slurry, adjust the pH to 5.0, add α-amylase, β-amylase, isoamylase and maltase and stir evenly. The activities of each enzyme reach 20U / g, 100U / g, 80U / g and 20U / g respectively. Under 45℃, sonicate at 200W for 2h, and then heat to 95℃ for 15min to end the enzymatic hydrolysis. S3. Adjust the pH of the enzymatically hydrolyzed slurry to 7.0, and inoculate with 105g of activated 1×10⁻⁶ mol / L slurry. 8 CFU / mL Bacillus licheniformis culture was transferred to a fermenter, stirred at 200 rpm, aerated at 0.6 L / (L·min), fermented at 37℃ for 36 h, and then sterilized at 121℃ for 15 min and cooled. S4. Mix 2000g of slurry and 50g of fruit fiber, add water and stir to adjust the solid content of the slurry to 20wt.%, homogenize at 30MPa and spray dry, then pass through a 100-mesh sieve to obtain sorghum fine powder; S5. The fine sorghum powder is passed through a fluidized bed, and 5 wt.% of hydroxypropyl methylcellulose is atomized and sprayed in at an atomization pressure of 0.5 MPa to granulate into particles with a particle size of 100-200 μm, thus obtaining easily soluble high-fiber sorghum powder. Comparative Example 4

[0034] The difference between this comparative example and Example 1 is that soybean flour is not added, as detailed below: S1. Remove impurities from 1000g of sorghum grains, soak them in 2000g of 2wt.% salt water at 30℃ for 24 hours, then rinse them with clean water, mix them with 1000g of water, grind them at 15000 rpm for 2 minutes, and then grind them at 25000 rpm for 3 minutes to obtain a slurry. S2. Adjust the pH of the slurry to 5.0, add laccase, lignin peroxidase, α-amylase, β-amylase, isoamylase and maltase and stir evenly. The activities of each enzyme reach 20U / g, 15U / g, 20U / g, 100U / g, 80U / g and 20U / g respectively. Under 45℃, sonicate at 200W for 2h, and then heat to 95℃ for 15min to end the enzymatic hydrolysis. S3. Adjust the pH of the enzymatically hydrolyzed slurry to 7.0, and inoculate with 100g of activated 1×10⁻⁶ ppm. 8 CFU / mL Bacillus licheniformis culture was transferred to a fermenter, stirred at 200 rpm, aerated at 0.6 L / (L·min), fermented at 37℃ for 36 h, and then sterilized at 121℃ for 15 min and cooled. S4. Mix 2000g of slurry and 50g of fruit fiber, add water and stir to adjust the solid content of the slurry to 20wt.%, homogenize at 30MPa and spray dry, then pass through a 100-mesh sieve to obtain sorghum fine powder; S5. The fine sorghum powder is passed through a fluidized bed, and 5 wt.% of hydroxypropyl methylcellulose is atomized and sprayed in at an atomization pressure of 0.5 MPa to granulate into particles with a particle size of 100-200 μm, thus obtaining easily soluble high-fiber sorghum powder. Comparative Example 5

[0035] The difference between this comparative example and Example 1 is that the fermentation time is 40 hours, as detailed below: S1. Remove impurities from 1000g of sorghum grains, soak them in 2000g of 2wt.% salt water at 30℃ for 24 hours, then rinse them with clean water, mix them with 1000g of water, grind them at 15000 rpm for 2 minutes, and then grind them at 25000 rpm for 3 minutes to obtain a slurry. S2. Add 100g of defatted soybean flour to the slurry, adjust the pH to 5.0, add laccase, lignin peroxidase, α-amylase, β-amylase, isoamylase and maltase and stir evenly. The activities of each enzyme reach 20U / g, 15U / g, 20U / g, 100U / g, 80U / g and 20U / g respectively. Under 45℃, sonicate at 200W for 2h, and then heat to 95℃ for 15min to end the enzymatic hydrolysis. S3. Adjust the pH of the enzymatically hydrolyzed slurry to 7.0, and inoculate with 105g of activated 1×10⁻⁶ mol / L slurry. 8 CFU / mL Bacillus licheniformis culture was transferred to a fermenter, stirred at 200 rpm, aerated at 0.6 L / (L·min), fermented at 37℃ for 40 h, and then sterilized at 121℃ for 15 min and cooled. S4. Mix 2000g of slurry and 50g of fruit fiber, add water and stir to adjust the solid content of the slurry to 20wt.%, homogenize at 30MPa and spray dry, and pass through a 100-mesh sieve to obtain sorghum fine powder; S5. The fine sorghum powder is passed through a fluidized bed, and 5 wt.% of hydroxypropyl methylcellulose is atomized and sprayed in at an atomization pressure of 0.5 MPa to granulate into particles with a particle size of 100-200 μm, thus obtaining easily soluble high-fiber sorghum powder. Comparative Example 6

[0036] The difference between this comparative example and Example 1 is that fermentation is not performed, as detailed below: S1. Remove impurities from 1000g of sorghum grains, soak them in 2000g of 2wt.% salt water at 30℃ for 24 hours, then rinse them with clean water, mix them with 1000g of water, grind them at 15000 rpm for 2 minutes, and then grind them at 25000 rpm for 3 minutes to obtain a slurry. S2. Add 100g of defatted soybean flour to the slurry, adjust the pH to 5.0, add laccase, lignin peroxidase, α-amylase, β-amylase, isoamylase and maltase and stir evenly. The activities of each enzyme reach 20U / g, 15U / g, 20U / g, 100U / g, 80U / g and 20U / g respectively. Under 45℃, sonicate at 200W for 2h, and then heat to 95℃ for 15min to end the enzymatic hydrolysis. S3. Mix 2000g of slurry and 50g of fruit fiber, add water and stir to adjust the solid content of the slurry to 20wt.%, homogenize at 30MPa and spray dry, and pass through a 100-mesh sieve to obtain sorghum fine powder; S4. The fine sorghum powder is passed through a fluidized bed, and 5 wt.% of hydroxypropyl methylcellulose is atomized and sprayed in at an atomization pressure of 0.5 MPa to granulate the powder into particles with a diameter of 100-200 μm, thus obtaining easily soluble high-fiber sorghum powder. Comparative Example 7

[0037] The difference between this comparative example and Example 1 is that fruit fiber is not added, as detailed below: S1. Remove impurities from 1000g of sorghum grains, soak them in 2000g of 2wt.% salt water at 30℃ for 24 hours, then rinse them with clean water, mix them with 1000g of water, grind them at 15000 rpm for 2 minutes, and then grind them at 25000 rpm for 3 minutes to obtain a slurry. S2. Add 100g of defatted soybean flour to the slurry, adjust the pH to 5.0, add laccase, lignin peroxidase, α-amylase, β-amylase, isoamylase and maltase and stir evenly. The activities of each enzyme reach 20U / g, 15U / g, 20U / g, 100U / g, 80U / g and 20U / g respectively. Under 45℃, sonicate at 200W for 2h, and then heat to 95℃ for 15min to end the enzymatic hydrolysis. S3. Adjust the pH of the enzymatically hydrolyzed slurry to 7.0, and inoculate with 105g of activated 1×10⁻⁶ mol / L slurry. 8 CFU / mL Bacillus licheniformis culture was transferred to a fermenter, stirred at 200 rpm, aerated at 0.6 L / (L·min), fermented at 37℃ for 36 h, and then sterilized at 121℃ for 15 min and cooled. S4. Mix 2000g of slurry and 50g of fruit fiber, add water and stir to adjust the solid content of the slurry to 20wt.%, homogenize at 30MPa and spray dry, then pass through a 100-mesh sieve to obtain sorghum fine powder; S5. The fine sorghum powder is passed through a fluidized bed, and 5 wt.% of hydroxypropyl methylcellulose is atomized and sprayed in at an atomization pressure of 0.5 MPa to granulate into particles with a particle size of 100-200 μm, thus obtaining easily soluble high-fiber sorghum powder. Comparative Example 8

[0038] The difference between this comparative example and Example 1 is that fluidized bed granulation is not performed, as detailed below: S1. Remove impurities from 1000g of sorghum grains, soak them in 2000g of 2wt.% salt water at 30℃ for 24 hours, then rinse them with clean water, mix them with 1000g of water, grind them at 15000 rpm for 2 minutes, and then grind them at 25000 rpm for 3 minutes to obtain a slurry. S2. Add 100g of defatted soybean flour to the slurry, adjust the pH to 5.0, add laccase, lignin peroxidase, α-amylase, β-amylase, isoamylase and maltase and stir evenly. The activities of each enzyme reach 20U / g, 15U / g, 20U / g, 100U / g, 80U / g and 20U / g respectively. Under 45℃, sonicate at 200W for 2h, and then heat to 95℃ for 15min to end the enzymatic hydrolysis. S3. Adjust the pH of the enzymatically hydrolyzed slurry to 7.0, and inoculate with 105g of activated 1×10⁻⁶ mol / L slurry. 8 CFU / mL Bacillus licheniformis culture was transferred to a fermenter, stirred at 200 rpm, aerated at 0.6 L / (L·min), fermented at 37℃ for 36 h, and then sterilized at 121℃ for 15 min and cooled. S4. Mix 2000g of slurry and 50g of fruit fiber, add water and stir to adjust the solid content of the slurry to 20wt.%, homogenize at 30MPa and spray dry, and pass through a 100-mesh sieve to obtain easily soluble high-fiber sorghum powder. Indicator Test

[0039] The protein and dietary fiber content of the high-fiber sorghum flour obtained in the examples and comparative examples were determined according to GB 5009.5 and GB5009.88; the carbohydrate content was calculated according to the method in GB 28050.

[0040] The results are shown in Table 1. Dietary fiber includes insoluble fiber (from sorghum, soybean, and fruit fiber) and soluble fiber (from HPMC and polysaccharides that may be produced during fermentation). Carbohydrates include starch, sugars, and other polysaccharides. The proportion of dietary fiber decreased after fermentation for more than 36 hours (Comparative Example 5), possibly due to excessive consumption or conversion of fiber by microorganisms. Comparative Example 3, which did not enzymatically hydrolyze lignin, had a higher fiber content, but lignin may affect the taste.

[0041] Table 1. Nutrient composition (dry weight) of high-fiber sorghum flour

[0042] 2. Sensory evaluation The sorghum flour, prepared with warm water, was evaluated in terms of color, taste, and sensory characteristics. The results are shown in Table 2. The sensory evaluation scores of the examples were all higher than those of the comparative examples, with the examples scoring above 89 points. Enzymatic hydrolysis (Comparative Example 2), especially enzymatic hydrolysis of lignin (Comparative Example 3), improved the taste and flavor of the product.

[0043] Table 2 Sensory evaluation scores of high-fiber sorghum flour

[0044] 3. Weigh 5g of the sample into a 50mL beaker. Dissolve the high-fiber sorghum powder in 38mL of water at 25℃-30℃ in several portions into a 50mL centrifuge tube and stopper it. Incubate the centrifuge tube in 30℃ water for 5 minutes, then remove it and shake for 3 minutes. Centrifuge at 4000r / min for 10 minutes to precipitate the insoluble matter. Discard the supernatant and wipe the tube wall clean with a cotton swab. Add 38mL of water at 25℃-30℃, stopper it, and shake to suspend the precipitate. Centrifuge again for 10 minutes, discard the supernatant, and carefully wipe the tube wall clean with a cotton swab. Rinse the precipitate with a small amount of water into a weighing dish (m1) of known mass. First, evaporate the water in the dish to dryness in a boiling water bath, then transfer it to a 100℃ oven and dry to constant weight. Weigh the dish to obtain the mass (m2) and calculate its solubility according to the following formula.

[0045] Where B is the moisture content of the sample, and m is the mass of the sample.

[0046] The solubility results are shown in Table 3. The solubility of Example 1 was 78%, which was much higher than that of all the comparative examples (the solubility range of the comparative examples was 55%~67%). The lowest solubility among the comparative examples was that of Comparative Example 6 (56%), which indicates that fermentation can produce soluble fiber.

[0047] The results show that the enzymatic hydrolysis, fermentation and granulation methods used in Example 1 can effectively improve the solubility of sorghum flour.

[0048] Table 3 Solubility and water-holding capacity of high-fiber sorghum flour

[0049] 4. Analysis and determination of water-holding capacity Accurately weigh 0.20 g of the dried sample to constant weight and place it in a 15 mL centrifuge tube. Quickly add 10 mL of distilled water, stir thoroughly, seal with food-grade plastic wrap, and let stand at room temperature for 12 hours. Then, centrifuge at 4000 rpm for 30 minutes at room temperature. Quickly decant the supernatant, blot away any remaining water (oil) with filter paper, and record the sample mass. Calculate the water-holding capacity using the formula:

[0050] Where: m2—the sum of the mass of the sample after water absorption and the mass of the centrifuge tube, g; m1—the mass of the centrifuge tube, g; m0—the mass of the constant-mass sample, g.

[0051] In food processing, this method can enhance the water-holding capacity of the system and improve the fullness of the product's texture. The results are shown in Table 3. Example 1 had the highest water-holding capacity at 1.65 g / g, among all samples. The lowest water-holding capacity among the comparative examples was Comparative Example 7 (1.20 g / g), only 72.7% of that of Example 1. This indicates that adding fruit fiber can effectively improve water-holding capacity. The improved water-holding capacity reflects an optimization of the number or spatial structure of hydrophilic groups in the product, which is significant for improving the texture and stability of food.

[0052] 5. GI value determination Healthy adult mice (C57BL / 6), half male and half female, with similar weights, were housed in separate cages, with 8 mice per group. They were acclimatized for one week before the experiment, with free access to water and fed a standard diet. During the experiment, the mice were fasted for 10 hours, while still having free access to water. Mice were weighed, and fasting blood glucose was measured by collecting blood from the tip of the tail using the tail-cropping method. The blood glucose level was then measured using a blood glucose meter at a dose of 10 g / kg, prepared as a solution, and administered via gavage. Blood was collected from the tip of the tail at 0, 30, 60, and 120 minutes after gavage and dripped onto blood glucose test strips.

[0053] The results are as follows Figure 1 Except for Comparative Examples 2 and 6, the GI values ​​of the other samples were below 55, classifying them as low-GI products. In particular, the GI value of Example 1 was 40, significantly lower than the other comparative examples. Comparative Example 2 did not undergo enzymatic hydrolysis, indicating that prior hydrolysis of starch into sugars, which are then preferentially fermented, can significantly reduce the glucose content, thereby achieving the goal of lowering the GI value.

[0054] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, without departing from the spirit and technical essence of the present invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the technical solutions of the present invention, shall still fall within the scope of protection of the present invention.

Claims

1. A method for preparing easily soluble high-fiber sorghum flour, characterized in that, Includes the following steps: S1. Remove impurities from sorghum grains, soak them in salt water, rinse them with clean water, mix them with water, grind them at low speed, and then grind them at high speed to obtain a slurry; S2. Add defatted soybean flour to the slurry, adjust the pH value, add compound enzyme and stir evenly, sonicate at constant temperature, and end the enzymatic hydrolysis by heating. S3. Adjust the pH of the enzymatically hydrolyzed slurry, inoculate it with activated Bacillus licheniformis culture, transfer it to a fermentation tank for fermentation, and sterilize and cool it after the fermentation is completed; S4. Mix the pulp and fruit fiber, add water and stir to adjust the solid content of the pulp, homogenize and spray dry, and sieve to obtain sorghum fine powder; S5. The fine sorghum powder is granulated by fluidized bed to obtain easily soluble high-fiber sorghum powder.

2. The method for preparing easily soluble high-fiber sorghum flour according to claim 1, characterized in that: The concentration of the brine in S1 is 1-3 wt.%; the mass ratio of sorghum to brine is 1:(2-4); the soaking temperature is 30-45℃, and the soaking time is 12-36h; the mass ratio of sorghum to water is 1:(1-2); the low-speed grinding speed is 15000-18000 rpm, and the time is 1-3min; the high-speed grinding speed is 20000-25000 rpm, and the time is 2-5min.

3. The method for preparing easily soluble high-fiber sorghum flour according to claim 1, characterized in that: The mass ratio of slurry to defatted soybean flour in S2 is (20-30):1; the pH value is adjusted to 4.5-5.5; the compound enzymes include laccase, lignin peroxidase, α-amylase, β-amylase, isoamylase and maltase; the constant temperature ultrasound temperature is 40-55℃, the ultrasound power is 200-300W, and the time is 2-3h; the heating temperature is 85-95℃, and the duration is 15-20min.

4. The method for preparing easily soluble high-fiber sorghum flour according to claim 3, characterized in that: The enzyme activities of laccase, lignin peroxidase, α-amylase, β-amylase, isoamylase, and maltase in the slurry are 15-20 U / g, 15-20 U / g, 15-20 U / g, 100-200 U / g, 80-200 U / g, and 20-50 U / g, respectively.

5. The method for preparing easily soluble high-fiber sorghum flour according to claim 1, characterized in that: In step S3, the pH is adjusted to 6.5-7.5; the inoculation amount is 5-10 wt.% of the slurry; and the concentration of the Bacillus licheniformis bacterial solution is 1×10⁻⁶. 8 -1×10 9 CFU / mL; fermentation temperature 35-37℃, fermentation time 24-36h, fermentation stirring speed 200-300 rpm, fermentation aeration rate 0.6-1.0L / (L·min); sterilization temperature 121℃, time 15-20min.

6. The method for preparing easily soluble high-fiber sorghum flour according to claim 5, characterized in that: The fermentation temperature was 37℃, the fermentation time was 36h, and the fermentation aeration rate was 0.8L / (L·min).

7. The method for preparing easily soluble high-fiber sorghum flour according to claim 1, characterized in that: The mass ratio of pulp to fruit fiber in S4 is (40-50):1; the solid content is 10-20 wt.%; and the homogenization pressure is 25-35 MPa.

8. The method for preparing easily soluble high-fiber sorghum flour according to claim 1, characterized in that: The fluidized bed granulation conditions in S5 are as follows: 5-8 wt.% of hydroxypropyl methylcellulose is atomized and sprayed in at an atomization pressure of 0.3-0.5 MPa, forming particles with a diameter of 100-200 μm.

9. A soluble high-fiber sorghum powder prepared by the preparation method according to any one of claims 1-8.

10. The application of an easily soluble high-fiber sorghum flour according to claim 9 in solid beverages, premixed powders, meal replacement powders, pasta, baked goods, and functional foods.

Images