A whole wheat flour filled with wheat endogenous protein / wheat bran composite ultrafine powder and its preparation method

Abstract

This invention belongs to the field of whole wheat flour preparation technology, specifically relating to a whole wheat flour prepared by backfilling with wheat endogenous protein / wheat bran composite ultrafine powder and its preparation method. The method modifies wheat bran through ultrafine grinding and synergistic action with wheat endogenous protein using intermolecular interactions, obtaining wheat endogenous protein / wheat bran composite ultrafine powder. This modification treatment improves the whiteness of the wheat bran ultrafine powder, reduces its particle size, increases the soluble dietary fiber content, and improves its water-holding capacity, oil-holding capacity, and swelling capacity. The method provided by this invention utilizes wheat bran coupled with wheat endogenous protein during ultrafine grinding to form wheat endogenous protein / wheat bran composite ultrafine powder based on intermolecular interactions, and high-quality whole wheat flour is prepared by backfilling with this wheat endogenous protein / wheat bran composite ultrafine powder.

Description

Technical Field

[0001] This invention belongs to the field of whole wheat flour preparation technology, specifically relating to a whole wheat flour made by backfilling wheat endogenous protein / wheat bran composite ultrafine powder and its preparation method. Background Technology

[0002] Wheat is one of the three major grain crops. In recent years, the production of wheat and the consumption of wheat flour have shown a year-on-year growth trend, resulting in a large amount of bran being produced every year.

[0003] Bran is the outer layer (including the aleurone layer) of wheat grains that is gradually milled off during the wheat milling process, accounting for about 13-19% of the total weight of wheat grains.

[0004] Wheat bran is rich in dietary fiber, phenolic compounds, minerals, vitamins, and other bioactive components, possessing significant potential application value. Therefore, developing whole wheat flour is an important way to realize the full utilization of wheat bran's components and nutritional functions.

[0005] In existing technologies, whole wheat flour processing mainly falls into two categories: whole grain milling and proportionally added grain milling. During whole grain milling, wheat bran and flour are prone to clumping due to static electricity, increasing the difficulty of subsequent whole wheat flour sieving and grinding, and also resulting in a short shelf life, making it difficult to meet the demands of whole wheat flour processing. Unlike whole grain milling, proportionally added grain milling separates the wheat bran and germ during processing, stabilizes them, and then reassembles them according to the proportions of natural grains to produce whole wheat flour. For example, Chinese Patent (Publication No.: CN107125555B) discloses a whole wheat flour production process for intermediate extraction and processing of gluten materials, including impurity removal, wheat moistening, wheat grain milling, sorting, bran milling, and re-addition. In the middle and later stages of whole wheat flour production, wheat bran containing part of the endosperm is selected as the wheat bran raw material. The wheat bran raw material is pre-treated using extrusion puffing technology, then the wheat bran raw material is milled, and finally the milled wheat bran raw material is re-added and mixed with the flour separated from the wheat grain milling to form whole wheat flour. However, the existing technology has the following problems with the preparation of whole wheat flour by wheat bran re-addition and reorganization: the tough texture of wheat bran makes it difficult to obtain the same particle size as wheat flour using conventional crushing methods. Therefore, the wheat bran raw material milling in this patent adopts a step-by-step milling method, first using a hammer mill to pre-crush the wheat bran, then using a toothed roller mill for coarse crushing, then using an impact mill for fine crushing, and finally using a smooth roller mill for micro-crushing. The existing technology suffers from problems such as complex operating procedures, high energy consumption, and high production costs. Furthermore, gluten proteins are crucial factors determining the gluten network structure and dough formation, playing a decisive role in dough rheological properties and product quality. In current technology, backfilling with wheat bran affects the formation of the wheat flour gluten protein network structure, leading to poor gluten quality in the dough.

[0006] Ultrafine grinding technology significantly improves the edibility, physicochemical properties, and functional characteristics of materials through mechanochemical stress, while enabling the full utilization of all components. After ultrafine grinding, sample particles become finer, their specific surface area increases, and their spatial network structure becomes more porous, significantly increasing the water-holding capacity, swelling capacity, and adsorption capacity of dietary fiber, as well as other physicochemical and functional properties. However, the chemical components in wheat bran are mostly bonded together or exist within the cellulose structure. After ultrafine grinding, the functional and nutrient substances dissolve, leading to problems such as fat oxidation and darkening of color, resulting in unstable product quality, poor processing suitability, and poor practical application effects. To solve these problems, sample stabilization treatment before ultrafine grinding is particularly important. For example, Chinese patent (CN109845958B) discloses a method for stabilizing and improving the quality of wheat bran, including using wheat bran as the main raw material, stabilizing the wheat bran using high-pressure technology, treating the wheat bran with a combination of enzymes (xylanase and cellulase), and then grinding it in an ultrafine grinder. However, this technology has drawbacks such as excessive bran softening, and there is weak data to support whether the modified wheat bran can be recycled into whole wheat products. Furthermore, enzymatic hydrolysis using xylanase and cellulase completely reduces the arabinoxylan content in the bran, significantly diminishing its health benefits. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides whole wheat flour filled with wheat endogenous protein / wheat bran composite ultrafine powder and its preparation method; during the ultrafine grinding process, wheat endogenous protein is coupled with wheat bran to form wheat endogenous protein / wheat bran composite ultrafine powder based on intermolecular interactions, and high-quality whole wheat flour is obtained by filling with wheat endogenous protein / wheat bran composite ultrafine powder.

[0008] This invention is achieved through the following technical solution:

[0009] A method for preparing whole wheat flour filled with wheat endogenous protein / wheat bran composite ultrafine powder, wherein the method modifies wheat bran by ultrafine grinding in conjunction with wheat endogenous protein through intermolecular interactions to obtain wheat endogenous protein / wheat bran composite ultrafine powder; the modification treatment improves the whiteness of wheat bran ultrafine powder, reduces the particle size of wheat bran ultrafine powder, increases the soluble dietary fiber content of wheat bran ultrafine powder, and improves the water holding capacity, oil holding capacity and swelling capacity of wheat bran ultrafine powder;

[0010] The wheat endogenous protein / wheat bran composite ultrafine powder is added back into the bran-free powder to prepare whole wheat flour.

[0011] Furthermore, the method specifically includes:

[0012] (1) Mix the pretreated wheat bran and wheat endogenous protein in a certain proportion to prepare a wheat endogenous protein / wheat bran mixture;

[0013] (2) The wheat endogenous protein / wheat bran mixture is added to an ultra-fine pulverizer and ultra-fine co-pulverized at a certain temperature. After ultra-fine pulverization for a certain time, wheat endogenous protein / wheat bran composite ultra-fine powder is obtained.

[0014] (3) The wheat endogenous protein / wheat bran composite ultrafine powder is added back to the bran-free powder in a certain proportion to prepare whole wheat flour.

[0015] Further, in step (1), the mass fraction of the wheat endogenous protein in the wheat endogenous protein / wheat bran mixture ranges from 1-5%, and the mass fraction of the wheat bran ranges from 95-99%.

[0016] Furthermore, in step (2), the temperature range of the ultrafine grinding process is 4-10℃; the time range of the ultrafine grinding process is 25-30min.

[0017] Furthermore, the types of endogenous wheat proteins include glutenin and / or gliadin.

[0018] Furthermore, the particle size range of the wheat endogenous protein / wheat bran composite ultrafine powder is 8.68-8.84 μm, the mass fraction of soluble dietary fiber in the wheat endogenous protein / wheat bran composite ultrafine powder is 8.05-10.31%, the whiteness ranges from 82.89-83.08%, the water holding capacity ranges from 2.90-2.97 g / g, the oil holding capacity ranges from 1.75-1.82 g / g, and the swelling power ranges from 2.79-3.12 mL / g.

[0019] Further, in step (3), in the whole wheat flour, the mass fraction of the wheat endogenous protein / wheat bran composite ultrafine powder ranges from 20-25%, and the mass fraction of the bran-free powder ranges from 75-80%.

[0020] The wheat endogenous protein / wheat bran composite ultrafine powder and the bran-free powder are placed in a mixer and mixed. The parameters of the mixer are set as follows: powder filling rate of 30-40%, mixing time of 30-40 min, and rotation speed of 40-60 r / min.

[0021] Further, in step (1), the pretreatment steps of the pretreated wheat bran include sieving, ultrasonic cleaning, filtration, superheated steam sterilization, and drying;

[0022] The ultrasonic cleaning step is performed under the following conditions: temperature 50-60℃, power 160-180W, and time 10-20min. The water control conditions in the filtration step are: filtering on a 60-mesh sieve until the moisture content of the wet wheat bran is 35-60%. The superheated steam sterilization process is performed under the following conditions: temperature 110-120℃, and time 30-40min. The drying conditions are: setting the temperature of the constant temperature drying oven to 40-60℃ and drying until the moisture content of the dry wheat bran is 8-12%.

[0023] A whole wheat flour filled with wheat endogenous protein / wheat bran composite ultrafine powder is prepared by the method described above. The whole wheat flour includes wheat endogenous protein / wheat bran composite ultrafine powder and bran-removed powder. In the whole wheat flour, the mass fraction of the wheat endogenous protein / wheat bran composite ultrafine powder ranges from 20-25%, and the mass fraction of the bran-removed powder ranges from 75-80%.

[0024] Furthermore, the moisture content of the whole wheat flour is in the range of 12-14%; the tensile properties of the whole wheat flour are measured, and the corresponding tensile property parameters are: toughness range of 188.33-189.67 mm, extensibility range of 27.33-30.12 mm, and configuration ratio range of 9.91-10.38.

[0025] The whole wheat flour was subjected to a flour quality characteristic test, and the corresponding flour quality characteristic parameters were: formation time range of 1.03-1.25 min, stability time range of 9.23-9.25 min, and protein weakening degree range of 0.60-0.62 N / M.

[0026] Beneficial technical effects of the present invention:

[0027] (1) The whole wheat flour preparation method provided by this invention establishes an in vitro wheat endogenous protein / wheat bran interaction system during the ultrafine grinding process, forming wheat bran-wheat endogenous protein composite ultrafine powder. Under the action of ultrafine grinding, the wheat endogenous protein and dietary fiber in wheat bran rub against the stainless steel roller, generating the same positive charge, which increases the charge repulsion between the powders. Therefore, the prepared wheat bran-wheat endogenous protein composite ultrafine powder is not prone to agglomeration, the particle size is reduced to 8.68 μm, the soluble dietary fiber content is increased to 10.31%, the whiteness is increased to 83.08%, the oil holding capacity is increased to 1.82 g / g, and the swelling capacity is increased to 3.12 mL / g, effectively solving the industry problems such as uneven particle fineness, unstable product quality, and poor gluten quality of dough during the preparation of whole wheat flour by adding wheat bran.

[0028] (2) The whole wheat flour preparation method provided by this invention effectively improves the comprehensive utilization rate of wheat bran, a by-product of wheat processing. The whole wheat flour prepared by the method described in this invention has an increased addition amount of wheat endogenous protein / wheat bran composite ultrafine powder to 20-25% (the highest addition amount of wheat bran in existing whole wheat flour on the market is 15%). Compared with wheat bran ultrafine powder alone, whole wheat flour with wheat endogenous protein / wheat bran composite ultrafine powder has better elasticity, extensibility and gluten strength. The dough formed in a shorter time and has a longer stability time. The strength and kneadability of the dough are also significantly improved.

[0029] (3) This invention addresses the industrial problems existing in the preparation of whole wheat flour by backfilling and recombining wheat bran in the prior art. It aims to efficiently and comprehensively utilize the original functional and nutritional components of wheat bran, a byproduct of wheat processing at different particle sizes, thereby achieving comprehensive utilization of the byproduct and significantly improving the nutritional value of whole wheat flour. Furthermore, this method uses only ultrafine grinding equipment, without the addition of water or other inorganic and organic compounds. It features low equipment investment, simple operation, low energy consumption, low production cost, environmental friendliness, and high-quality products, resulting in significant economic and social benefits. Attached Figure Description

[0030] Figures 1a-1c This is a diagram illustrating the effect of ultrafine grinding and glutenin synergistic effect on the microstructure of wheat bran in an embodiment of the present invention. Figure 1a It is an ultrafine powder, and the grinding time is 5 minutes; Figure 1b To ensure even mixing, the grinding time is 5 minutes. Figure 1c (This is a composite powder; grinding time: 5 minutes).

[0031] Figures 2A-2C This is a diagram illustrating the effect of ultrafine grinding and glutenin synergistic effect on the microstructure of wheat bran in an embodiment of the present invention. Figure 2A It is an ultrafine powder, and the grinding time is 30 minutes; Figure 2B To ensure even mixing, the grinding time is 30 minutes. Figure 2C (This is a composite powder; grinding time: 30 min).

[0032] Figure 3 The figure shows the effect of ultrafine grinding combined with glutenin on the water-holding capacity of wheat bran in the embodiments of the present invention; in the figure, different uppercase letters indicate that the difference in grinding time is significant in the same treatment group (P<0.05), and different lowercase letters indicate that the difference in treatment process is significant in the same time (P<0.05).

[0033] Figure 4The figure shows the effect of ultrafine grinding combined with glutenin on the oil-holding capacity of wheat bran in the embodiments of the present invention; in the figure, different uppercase letters indicate that the difference in grinding time is significant in the same treatment group (P<0.05), and different lowercase letters indicate that the difference in different treatment processes is significant in the same time (P<0.05).

[0034] Figure 5 The figure shows the effect of ultrafine grinding combined with glutenin on the swelling force of wheat bran in the embodiments of the present invention. In the figure, different uppercase letters indicate that there are significant differences in grinding time for the same treatment group (P<0.05), and different lowercase letters indicate that there are significant differences in different treatment processes for the same time (P<0.05). Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0036] Conversely, this invention encompasses any substitutions, modifications, equivalent methods, and solutions made within the spirit and scope of the invention as defined in the claims. Furthermore, to provide a better understanding of the invention, certain specific details are described in detail below. However, those skilled in the art will fully understand the invention even without these detailed descriptions.

[0037] This invention provides an embodiment of a method for preparing whole wheat flour using wheat endogenous protein / wheat bran composite ultrafine powder. The method modifies wheat bran through ultrafine grinding and in conjunction with intermolecular interactions of wheat endogenous protein, obtaining wheat endogenous protein / wheat bran composite ultrafine powder. This modification treatment improves the whiteness of the wheat bran ultrafine powder, reduces its particle size, increases the soluble dietary fiber content, and enhances its water-holding capacity, oil-holding capacity, and swelling capacity.

[0038] The wheat endogenous protein / wheat bran composite ultrafine powder is added back into the bran-free powder to prepare whole wheat flour.

[0039] The method specifically includes:

[0040] (1) Mix the pretreated wheat bran and wheat endogenous protein in a certain proportion to prepare a wheat endogenous protein / wheat bran mixture;

[0041] (2) The wheat endogenous protein / wheat bran mixture is added to an ultra-fine pulverizer and ultra-fine co-pulverized at a certain temperature. After ultra-fine pulverization for a certain time, wheat endogenous protein / wheat bran composite ultra-fine powder is obtained.

[0042] (3) The wheat endogenous protein / wheat bran composite ultrafine powder is added back to the bran-free powder in a certain proportion to prepare whole wheat flour.

[0043] In step (1) of this embodiment, the mass fraction of the wheat endogenous protein in the wheat endogenous protein / wheat bran mixture ranges from 1-5%, and the mass fraction of the wheat bran ranges from 95-99%.

[0044] In step (2) of this embodiment, the temperature range of the ultrafine grinding process is 4-10℃; the time range of the ultrafine grinding process is 25-30min.

[0045] In this embodiment, the types of endogenous wheat proteins include glutenin and / or gliadin.

[0046] Among them, glutenin and / or gliadin are excellent carriers of bioactive molecules. They can bind to resveratrol, quercetin, and curcumin through hydrophobic interactions, thereby improving the stability of bioactive molecules. Furthermore, ultrafine grinding alters the structure and functional properties of glutenin and / or gliadin. Based on the theory of food component interactions, this invention utilizes endogenous wheat proteins to stabilize ultrafine dissolved components that affect the quality characteristics of wheat bran during the ultrafine grinding process, forming a new wheat bran-wheat endogenous protein composite ultrafine powder for backfilling in the preparation of whole wheat flour, thus improving the suitability of wheat bran processing.

[0047] In this embodiment, the particle size range of the wheat endogenous protein / wheat bran composite ultrafine powder is 8.68-8.84 μm, the mass fraction of soluble dietary fiber in the wheat endogenous protein / wheat bran composite ultrafine powder is 8.05-10.31%, the whiteness ranges from 82.89-83.08%, the water holding capacity ranges from 2.90-2.97 g / g, the oil holding capacity ranges from 1.75-1.82 g / g, and the swelling power ranges from 2.79-3.12 mL / g.

[0048] In step (3) of this embodiment, the mass fraction of the wheat endogenous protein / wheat bran composite ultrafine powder in the whole wheat flour ranges from 20-25%, and the mass fraction of the bran-free powder ranges from 75-80%.

[0049] The wheat endogenous protein / wheat bran composite ultrafine powder and the bran-free powder are placed in a mixer for mixing. The parameters of the mixer are set as follows: powder filling rate of 30-40%, mixing time of 30-40 min, and rotation speed of 40-60 r / min. The powder filling rate of the mixer has a significant impact on the mixing effect. If the filling rate is too high, although it can increase the output, the material layer will be thicker, the mixing motion state will change, and the original suitable motion trajectory will be disrupted, which will have an adverse effect on the mixing. If the filling rate is too low, the production rate will not meet the production needs. If the mixing time is too short, the material will not be mixed sufficiently. If the mixing time is too long, separation is likely to occur. The rotation speed of the mixer will affect the mixing state of the material, thereby affecting the mixing uniformity. If the rotation speed is too low, it will be difficult to mix evenly. If the rotation speed is too high, exceeding the critical value, the material will undergo centrifugal motion, which will not achieve the purpose of mixing. Only when the rotation speed is appropriate and the material undergoes a tossing motion can the components come into full contact and achieve a good mixing effect.

[0050] In step (1) of this embodiment, the pretreatment steps of the pretreated wheat bran include sieving, ultrasonic cleaning, filtration, superheated steam sterilization, and drying.

[0051] The ultrasonic cleaning step is performed under the following conditions: temperature 50-60℃, power 160-180W, and time 10-20 minutes. The filtration step involves filtering the wheat bran through a 60-mesh sieve until the moisture content is 35-60%. The superheated steam sterilization process is performed under the following conditions: temperature 110-120℃, and time 30-40 minutes. The drying process involves setting the temperature of the constant temperature drying oven to 40-60℃ and drying until the dry wheat bran has a moisture content of 8-12%. Specifically, the pretreatment step includes:

[0052] (1) Screening: In order to remove wheat residue and other large impurities such as stones and iron wires from the wheat bran, the bran is first screened through a 14-mesh sieve and a 40-mesh sieve, and the wheat bran remaining on the 40-mesh sieve is collected.

[0053] (2) Ultrasonic cleaning: Ultrasonic cleaning is a cleaning method that uses mechanical action, cavitation action and thermal effect to remove dirt. In order to remove dirt and enhance antibacterial effect, take an appropriate amount of wheat bran that has passed through a 40-mesh sieve and put it into an ultrasonic cleaner for cleaning. The parameters of the ultrasonic cleaner are set as follows: temperature is 50-60℃, power is 160-180W, and time is 10-20min.

[0054] (3) Filtration: After ultrasonic cleaning, the wheat bran is simply rinsed and placed on a 60-mesh sieve for filtration to remove water, resulting in wet wheat bran with a moisture content of 35-60%.

[0055] (4) Superheated Steam Sterilization: To inactivate lipase and lipoxygenase in wheat bran and simultaneously sterilize it, the wet wheat bran obtained after ultrasonic cleaning and filtration is placed in a high-pressure steam sterilizer. The parameters of the high-pressure steam sterilizer are set as follows: temperature 110-120℃, time 30-40min. The wheat bran obtained from high-pressure steam sterilization is then placed in a constant temperature drying oven for drying. The temperature of the constant temperature drying oven is set as 40-60℃ to obtain dry wheat bran with a moisture content of 8-12%.

[0056] The following are the specific experimental methods, procedures, and results of this invention:

[0057] To clarify the effect of ultrafine grinding and synergistic effect of wheat endogenous protein on improving the quality characteristics of wheat bran, this invention prepares three types of powders: ultrafine powder, mixed powder, and composite powder.

[0058] Preparation of ultrafine powder: Wheat bran was placed in an ultrafine pulverizer and pulverized for different times (5, 10, 15, 20, 25, 30 min) to obtain 6 kinds of wheat bran ultrafine powder.

[0059] Preparation of the mixed powder: 3% glutenin was added back into 6 different pulverization times (5, 10, 15, 20, 25, 30 min) of wheat bran ultrafine powder and mixed evenly to obtain wheat bran ultrafine powder / protein mixed powder.

[0060] Preparation of composite powder: Wheat bran and 3% glutenin were placed together in an ultrafine grinder and ground for different times (5, 10, 15, 20, 25, 30 min) to obtain 6 kinds of wheat bran / protein ultrafine composite powder.

[0061] Determination of dietary fiber content: The determination of total dietary fiber, soluble dietary fiber and insoluble dietary fiber content shall be carried out in accordance with the "Determination of Dietary Fiber in Food" (GB 5009.88-2014).

[0062] Particle size determination: The Mastersizer 2000 laser particle size analyzer was used to determine the particle size using a wet particle size testing system. The samples were ultrasonically dispersed before measurement.

[0063] Color Analysis: The color of wheat bran can be represented by parameters L*, a*, and b*, which represent the brightness of the wheat bran, corresponding to greenness → redness and blueness → yellowness, respectively. The L*, a*, and b* values ​​of wheat bran powder were determined using a YS3010 spectrophotometer. The basic parameters of the colorimeter were: D65 light source, 8mm diameter measurement area, and 10° observation angle. Before use, the colorimeter was calibrated with a white board and a black board. The standard sample parameters were set to the colorimetric values ​​of a white standard board: (L* = 95.26, a* = -0.89, b* = 1.18). An appropriate amount of sample powder was spread evenly on the table, compacted, and placed under the measuring port of the colorimeter. After stabilizing, the measurement was performed.

[0064] Microstructure determination: The microstructure of wheat bran powder was observed using a SU8020 field emission scanning electron microscope. A suitable amount of wheat bran powder was fixed on the stage, vacuum-sputtered with gold, and then observed under a scanning electron microscope. Specific instrument parameters: accelerating voltage 3KV; magnification 300,000–800,000x.

[0065] Water-holding capacity test: Accurately weigh 1.00 g wheat bran powder (M1) into a beaker, add 50 mL of deionized water, stir magnetically at 25℃ for 30 min, centrifuge at 2500 r / min for 20 min, remove the upper layer of water and weigh the sample mass M2; water-holding capacity of the sample = (M2-M1) / M1×100%.

[0066] Oil holding capacity determination: Take 1.00g of wheat bran powder (W1) into a centrifuge tube, add 20g of edible rapeseed oil, let stand at 37℃ for 1 hour, centrifuge at 3000r / min for 20 minutes, and remove the upper layer of oil. The weight of the sample after centrifugation is W2. The oil holding capacity of the sample = (W2-W1) / W1×100%.

[0067] Expansion force determination: Weigh 0.5g of wheat bran powder into a 15mL graduated cylinder, tap the cylinder wall gently 5-8 times to make the powder surface flat and the interior without gaps, and read the initial volume V1; transfer 10mL of deionized water into the sample, shake to mix, let stand at room temperature for 24h, and read the volume V2 at this time; the expansion force of the sample = (V2-V1) / V1×100%.

[0068] Results and Analysis

[0069] (1) Ultrafine grinding synergistically improves the color of wheat bran with glutenin.

[0070] Table 1. Effects of ultrafine grinding and glutenin synergistic on wheat bran color.

[0071]

[0072]

[0073] Different capital letters in the same column indicate significant differences in different grinding times under the same processing technology (P<0.05), while different lowercase letters in the same column indicate significant differences in different processing technologies under the same grinding time (P<0.05).

[0074] Color is one of the key quality indicators of grain flour, affecting consumer acceptance of various foods. As shown in Table 1, the whiteness of ultrafine powder gradually increases with increasing ultrafine grinding time, showing no significant difference after 15 minutes of grinding; its yellowness and redness gradually decrease with increasing ultrafine grinding time, reaching a minimum at 30 minutes. The whiteness of mixed powder first increases and then decreases with increasing grinding time, reaching a maximum of 82.19% at 25 minutes, with no significant difference after 15 minutes of grinding; the redness and yellowness of mixed powder gradually decrease with increasing time. The whiteness of composite powder gradually increases with increasing ultrafine grinding time, showing a significant difference after 10 minutes of grinding; its yellowness and redness gradually decrease with increasing grinding time.

[0075] Under the same grinding time, and exceeding 25 minutes, the composite powder showed a significant effect and outstanding advantages. When the grinding time exceeded 25 minutes, the whiteness of the composite powder was significantly higher than that of the ultrafine powder and the mixed powder, while its redness and yellowness were lower than those of the ultrafine powder and the mixed powder. This indicates that the composite powder obtained by grinding wheat bran and glutenin together significantly improves the whiteness of wheat bran and reduces its yellowness and redness, which helps to improve the appearance quality of whole wheat products during storage. Studies have found that ultrafine grinding reduces particle size and increases surface area. Light reflection increases with the increase of specific surface area, and the grinding process exposes the internal structure of cellulose and hemicellulose, which affects the color of the sample. Therefore, to investigate the reasons for the color improvement of wheat bran-gluten ultrafine powder, this invention further measured the particle size change.

[0076] (2) Ultrafine grinding synergistically reduces the particle size of wheat bran.

[0077] Table 2. Effects of ultrafine grinding and glutenin synergistic on wheat bran particle size.

[0078]

[0079] Different capital letters in the same column indicate significant differences in different grinding times under the same processing technology (P<0.05), while different lowercase letters in the same column indicate significant differences in different processing technologies under the same grinding time (P<0.05).

[0080] As shown in Table 2, with the extension of ultrafine grinding time, the D of wheat bran ultrafine powder... V10 D V50 D V90 d 4.3 and d 3.2The trend is that it first decreases and then increases, reaching its lowest value at a grinding time of 25 minutes. However, this invention found that the D of mixed powder and composite powder... V10 D V50 D V90 d 4.3 and d 3.2 The value is negatively correlated with the grinding time, and gradually decreases as the grinding time increases.

[0081] Analysis of d under the same grinding time for different processing techniques 4,3 The changes show that the order was: compound powder < homogeneous powder < wheat bran powder, with significant differences at all time points. This indicates that co-grinding glutenin and wheat bran significantly reduces the average particle size of wheat bran. Furthermore, considering all particle size variations, when the ultrafine grinding time exceeds 20 minutes, D... V10 D V50 D V90 d 4.3 and d 3.2 Significant differences were observed under different processing techniques, indicating that co-grinding wheat gluten and wheat bran significantly reduced the particle size of wheat bran and improved powder agglomeration. The study showed that when wheat bran powder was shaken in a stainless steel charging tube, it underwent triboelectric charging. Starch became negatively charged, while other components such as protein and dietary fiber became positively charged, with glutenin being the dominant component. Adding glutenin during ultrafine grinding caused the glutenin and dietary fiber in the wheat bran to rub against the stainless steel rollers under the action of ultrafine grinding, generating the same positive charge. This increased the electrostatic repulsion between the powder particles, making them less prone to agglomeration and significantly reducing particle size.

[0082] (3) Effect of ultrafine grinding and glutenin synergistic effect on dietary fiber content of wheat bran

[0083] Table 3. Dietary fiber content of three powders at different grinding times.

[0084]

[0085] Different capital letters in the same column indicate significant differences in different grinding times under the same processing technology (P<0.05), while different lowercase letters in the same column indicate significant differences in different processing technologies under the same grinding time (P<0.05).

[0086] Table 3 shows that with the extension of ultrafine grinding time, the total dietary fiber and insoluble dietary fiber content of ultrafine powder, mixed powder, and composite powder gradually decreased, while the soluble dietary fiber content of the three powders gradually increased. Comparison of dietary fiber content among the three powders at the same grinding time revealed no significant differences in total dietary fiber, soluble dietary fiber, and insoluble dietary fiber among the three powders when the grinding time was less than or equal to 25 min. However, when the grinding time exceeded 25 min, reaching 30 min, the total dietary fiber and insoluble dietary fiber content of the composite powder were lower than those of the ultrafine powder and mixed powder, while its soluble dietary fiber content was higher than that of the ultrafine powder and mixed powder. This invention found that adding glutenin during the ultrafine grinding of wheat bran to prepare a novel composite powder reduced the particle size of the wheat bran and increased the content of soluble dietary fiber. This may be related to the further destruction of the wheat bran tissue and cells; therefore, the microstructure of the three powders was analyzed.

[0087] (4) Analysis of microscopic morphology results

[0088] To observe the microstructure of wheat bran under different treatment conditions, scanning electron microscopy (SEM) was used at a magnification of 5000x. The SEM images of wheat bran under different treatments are shown below. Figures 1a-1c , Figures 2A-2C As shown in Figures 1 and 2, smooth spherical or elliptical substances and lamellar substances may be starch and coarse protein, while thin sheets with irregular sizes and shapes may be structural features of fibers.

[0089] Wheat bran powder pulverized for 5 minutes has a relatively smooth surface and intact structure. Oval-shaped starch granules can be clearly observed on the surface, and the overall surface is relatively smooth. Figure 1a After wheat bran is ultra-finely ground for 30 minutes, its flaky fibrous structure breaks down, and the size of the spherical starch and protein particles is significantly reduced. Figure 2A After being ultra-finely pulverized for 5 minutes, a sample was mixed with 3% glutenin. Large spherical structures were observed on the surface, and the originally smooth surface developed a porous structure. Figure 1b After being ultra-finely pulverized for 30 minutes, a sample mixed with 3% glutenin showed no obvious spherical material on its surface, and the originally large sheet-like structure was broken down into smaller pieces. Figure 2B Therefore, it can be determined that the spherical substance is starch granules. 3% glutenin was then ultra-finely pulverized for 5 minutes. Figure 1cThe microstructure of the granulated wheat bran did not show large spherical particles; the sheet-like structure was disrupted, resulting in smaller, tightly connected sheets without significant porosity. This is likely due to the interaction and tight bonding between glutenin and the fibrous structure and / or starch in the bran. After 30 minutes of ultrafine grinding, most of the bran cell wall matrix was destroyed, significantly reducing particle size and sheet-like structure. However, each small sheet-like structure was not separated but interconnected, increasing the porosity of the particles. Figures 1a-2A , Figures 1b-2b , Figures 1c-2c The comparison shows that the ultrafine grinding time has a significant impact on the structure of wheat bran. Compared with wheat bran samples ground for 5 minutes, the wheat bran samples ground for 30 minutes have more severe damage to the flaky structure and the particle size is significantly reduced. Figure 1a -bc、 Figure 2A A comparison between -BC shows that adding glutenin after ultrafine grinding also affects the structure of wheat bran. The particles obtained by grinding glutenin together with wheat bran are smaller in size and have more pores between particles.

[0090] The above analysis shows that the structure of wheat bran is severely damaged with prolonged ultrafine grinding time, which is consistent with the results for soluble and insoluble dietary fiber. Adding glutenin during ultrafine grinding causes more severe damage to the wheat bran powder structure than adding glutenin after ultrafine grinding or adding glutenin after ultrafine grinding. This experiment will further explore the changes in the functional properties of wheat bran.

[0091] (5) Effect of ultrafine grinding and glutenin on the water-holding capacity of wheat bran

[0092] Depend on Figure 3 It was found that, under the same grinding time, there was no significant difference in the water-holding capacity of the three powders. Ultrafine grinding, combined with glutenin, kept the water-holding capacity of wheat bran within the range of 2.90-2.97 g / g. This indicates that within the grinding time range of 5-30 min, the addition of glutenin, whether added before or after ultrafine grinding, had no significant effect on the water-holding capacity of wheat bran; its water-holding capacity is mainly related to the grinding time.

[0093] (6) Effect of ultrafine grinding and glutenin on the oil-holding capacity of wheat bran

[0094] The oil-holding capacity of ultrafine powders is closely related to the porous structure of their dietary fiber content. Figure 4It was found that the oil-holding capacity of wheat bran powder first decreased and then increased with increasing grinding time, reaching a minimum of 1.76 g / g at 25 min. The oil-holding capacity of the mixed powder gradually decreased with increasing grinding time, reaching a minimum of 1.47 g / g at 30 min. When the grinding time reached 15 min, the oil-holding capacity of the mixed powder no longer showed a significant change with further increases in grinding time. The oil-holding capacity of the composite powder first decreased and then increased with increasing grinding time, reaching a maximum at 30 min. This may be because the external force of prolonged ultrafine grinding improves the structure of protein and wheat bran, increases the interaction between glutenin and wheat bran, and significantly improves oil-holding capacity.

[0095] A comparison of the oil-holding capacity of three powders under the same grinding time revealed that at grinding times of 5 and 10 minutes, the oil-holding capacity of the composite powder was significantly higher than that of the ultrafine powder. However, when the grinding time exceeded 15 minutes, there was no significant difference in oil-holding capacity between the wheat bran powder and the composite powder. Nevertheless, at all grinding times, the oil-holding capacity of the composite powder was significantly higher than that of the mixed powder, especially after 25 minutes, indicating that adding glutenin during the ultrafine grinding process is more effective than adding protein after grinding. The oil-holding capacity of food is closely related to its ability to prevent fat loss; stronger oil-holding capacity indicates a stronger ability to prevent fat loss and a more significant effect on lowering blood cholesterol. Therefore, the composite powder also has a certain effect on lowering blood cholesterol.

[0096] (7) Effect of ultrafine grinding and glutenin synergistic effect on the swelling power of wheat bran

[0097] Wheat bran dietary fiber absorbs water and swells, creating a feeling of fullness, promoting intestinal peristalsis, and relieving constipation. Figure 5 It was found that the swelling power of the three powders—wheat bran powder, mixed powder, and composite powder—gradually increased with increasing grinding time, indicating that ultrafine grinding can improve the water absorption and swelling properties of wheat bran powder. After ultrafine grinding, the particle size of wheat bran powder continuously decreased, the number of powder particles continuously increased, and the specific surface area increased. Therefore, the contact area between dietary fiber and water during water absorption was also larger, resulting in a larger volume after water absorption and swelling. When the grinding time was less than 20 minutes, there was no significant difference in the swelling power of the three powders. When the grinding time was 20 minutes, the swelling power of the mixed powder was significantly lower than that of wheat bran powder and composite powder, while there was no significant difference between ultrafine powder and composite powder. However, when the grinding time reached 25 minutes, a significant difference appeared between ultrafine powder and composite powder, and at 30 minutes, the swelling power of composite powder was significantly higher than that of ultrafine powder and mixed powder. This may be because when wheat bran and protein are subjected to external force for a long time, the bonds between them are formed, changing the structure of wheat bran, increasing the porosity of wheat bran powder, and improving the swelling power of wheat bran.

[0098] The above results show that, in order to improve the physicochemical and functional properties of wheat bran during processing, this invention couples wheat endogenous proteins using ultrafine grinding technology to form a new wheat bran-wheat endogenous protein composite ultrafine powder based on intermolecular interactions. A systematic study revealed the changes in wheat bran color, particle size, dietary fiber content, and functional properties under ultrafine grinding times (5, 10, 15, 20, 25, 30 min) and different ultrafine grinding processes (ultrafine powder, mixed powder, composite powder). Based on all analytical indicators, this invention clearly demonstrates that ultrafine co-grinding of wheat bran coupled with wheat endogenous proteins can significantly improve the suitability of wheat bran processing. The optimal grinding time range is 25-30 min. At this time, ultrafine grinding, synergistically with glutenin, significantly improves the whiteness of the wheat bran ultrafine powder, with a whiteness range of 82.89-83.08%; and effectively reduces the particle size of the wheat bran to 8.68-8.84 μm. Ultrafine grinding, in conjunction with glutenin, significantly reduced the insoluble dietary fiber content of wheat bran and increased the soluble dietary fiber content, reaching 8.05-10.31%. It also promoted the disruption of the wheat bran cell wall matrix, increased the porosity of the wheat bran, and significantly improved the oil holding capacity and swelling capacity of the wheat bran, with an oil holding capacity range of 1.75-1.82 g / g and a swelling capacity range of 2.79-3.12 mL / g.

[0099] The present invention also provides an embodiment of whole wheat flour backfilled with wheat endogenous protein / wheat bran composite ultrafine powder, wherein the whole wheat flour includes wheat endogenous protein / wheat bran composite ultrafine powder and bran-removed powder, wherein the mass fraction of the wheat endogenous protein / wheat bran composite ultrafine powder in the whole wheat flour ranges from 20-25%, and the mass fraction of the bran-removed powder ranges from 75-80%.

[0100] In this embodiment, the moisture content parameter of the whole wheat flour is in the range of 12-14%;

[0101] The tensile properties of the whole wheat flour were measured, and the corresponding tensile property parameters were: toughness range of 188.33-189.67 mm, extensibility range of 27.33-30.12 mm, and configuration ratio range of 9.91-10.38.

[0102] The whole wheat flour was subjected to a flour quality characteristic test, and the corresponding flour quality characteristic parameters were: formation time range of 1.03-1.25 min, stability time range of 9.23-9.25 min, and protein weakening degree range of 0.60-0.62 N / M.

[0103] To clarify the effect of ultrafine grinding and synergistic effect of wheat endogenous protein on improving the quality characteristics of wheat bran, whole wheat flour was prepared by backfilling ultrafine powder, mixed powder, and composite powder, and its flour properties and tensile properties were evaluated.

[0104] Whole wheat flour preparation using three processes:

[0105] (1) Preparation of whole wheat flour by backfilling wheat bran ultrafine powder (A): Wheat bran with a mass fraction of 100% is put into an ultrafine pulverizer for ultrafine pulverization. The ultrafine pulverization temperature is 4℃ and the pulverization time is 30min. The wheat bran ultrafine powder is then backfilled into the bran-free medium gluten flour, wherein the mass fraction of wheat bran ultrafine powder is 5-25% and the mass fraction of bran-free medium gluten flour is 75-95%.

[0106] (2) Preparation of whole wheat flour by backfilling wheat bran ultrafine powder / protein mixed powder (B): Wheat bran with a mass fraction of 97% is put into an ultrafine pulverizer for ultrafine pulverization. The ultrafine pulverization temperature is 4℃ and the pulverization time is 30min to obtain wheat bran ultrafine powder. Add wheat endogenous protein with a mass fraction of 3% and mix evenly to prepare wheat endogenous protein / wheat bran complex. Backfill the wheat endogenous protein / wheat bran complex powder into the bran-free medium gluten flour, wherein the mass fraction of wheat endogenous protein / wheat bran complex ultrafine powder is 5-25% and the mass fraction of bran-free medium gluten flour is 75-95%.

[0107] (3) Preparation of whole wheat flour by backfilling wheat bran / protein ultrafine composite powder (C): Wheat bran with a mass fraction of 97% and wheat endogenous protein with a mass fraction of 3% are mixed evenly to prepare a wheat endogenous protein / wheat bran mixture; the wheat endogenous protein / wheat bran mixture is placed in an ultrafine pulverizer for ultrafine pulverization. The ultrafine pulverization temperature is set at 4℃ and the pulverization time is 30min to obtain wheat endogenous protein / wheat bran composite ultrafine powder. The wheat endogenous protein / wheat bran composite ultrafine powder is backfilled into de-glutenized medium gluten flour, wherein the mass fraction of wheat endogenous protein / wheat bran composite ultrafine powder is 5-25% and the mass fraction of de-glutenized medium gluten flour is 75-95%.

[0108] Tensile property determination: Following the method described in GB / T14614.4-2005 "Determination of Rheological Properties of Wheat Flour Dough - Bubble Tester Method," various tensile property parameters were obtained, as shown in Table 4. 25g of salt was accurately weighed, dissolved in 1L of distilled water, and added to the water tank of the bubble tester. Sufficient water was ensured in the humidity control device of the bubble tester. 250g of flour was accurately weighed, added to the mixing bowl, and the instrument was allowed to reach its optimal range before starting the constant water addition test. After kneading for 8 minutes, dough sheets were prepared (minimizing deformation during dough sheet preparation). The prepared dough sheets were placed in a proofing box, and after 20 minutes of proofing, the dough sheets were removed for the bubble test.

[0109] Table 4. Meaning of dough stretching parameters and the properties they represent

[0110]

[0111] Determination of dough properties: The thermodynamic properties of the dough were tested using a Chopin mixing apparatus. The standard Chopin protocol was used in this experiment. The dough mass was 75g, and the dough consistency was defined as 1.1 Nm. The procedure was as follows: (1) Isothermal process: maintained at 30℃ for 8 min; (2) Heating process: heated to 90℃ at a rate of 4℃ / min and held for 7 min; (3) Cooling process: cooled to 50℃ at a rate of 4℃ / min and held for 5 min; the total program time was 45 min, with a stirring rate of 80 r / min. Each sample was repeated at least three times.

[0112] Results analysis:

[0113] (1) Wheat bran-glutenin ultrafine powder improves the stretch properties of whole wheat flour

[0114] Table 5. Comparison of tensile properties of novel whole wheat flour prepared by backfilling with the same amount of wheat bran ultrafine powder (A), wheat bran ultrafine powder / protein blend (B), and wheat bran / protein ultrafine composite powder (C).

[0115]

[0116]

[0117] Different capital letters in the same column under the same additive amount indicate significant differences between samples under different processing methods (P<0.05).

[0118] This study compared the tensile properties of novel whole wheat flour prepared by backfilling with the same amount of wheat bran ultrafine powder (A), wheat bran ultrafine powder / protein blend (B), and wheat bran / protein ultrafine composite powder (C). The P-value refers to the pressure that ultimately causes the dough to deform, representing the dough's toughness. The study found that a higher P-value indicates greater dough toughness. Simultaneously, with the same amount of water added, a higher P-value indicates a higher water absorption rate; a higher L-value indicates stronger dough extensibility and a stronger gas-retention capacity of gluten proteins. The P / L ratio, the ratio of dough resistance value P to extensibility L, represents the relationship between toughness and extensibility; a higher P / L value indicates stronger dough elasticity, and vice versa.

[0119] As shown in Table 5, when the addition amount is 5-15%, the P-value and L-value of whole wheat flour with added ultrafine wheat bran powder (A) are significantly lower than those with added ultrafine wheat bran powder / protein blend (B) and ultrafine wheat bran / protein composite powder (C). At this addition amount, the B and C treatment processes have no significant effect on the P-value and L-value of the novel whole wheat flour. It is noteworthy that when the addition amount is 20%, the whole wheat flour obtained by backfilling with ultrafine wheat bran powder (A) cannot form dough. Studies have found that the introduction of insoluble dietary fiber from wheat bran into the dough reduces the intermolecular forces of protein molecules, leading to a poorer gluten network structure, decreased overall dough properties, and reduced dough viscosity and lateral extensibility. However, this invention patent finds that exogenous addition of glutenin helps the B and C treatment processes to form the novel whole wheat flour dough. When the addition amount was 25%, whole wheat flour with wheat bran / protein ultrafine composite powder (C) showed significant advantages in toughness and extensibility, with significantly higher P and L values ​​than whole wheat flour with added wheat bran ultrafine powder / protein blend (B). Similarly, when the addition amount was 25%, the P / L value of whole wheat flour with wheat bran / protein ultrafine composite powder (C) was significantly lower than that of whole wheat flour with added wheat bran ultrafine powder / protein blend (B), indicating better extensibility, which may be related to its soluble dietary fiber content. In the study on the improvement of the physicochemical and functional properties of wheat bran by ultrafine grinding and glutenin, when the grinding time reached 30 min, the total dietary fiber and insoluble dietary fiber of wheat bran / protein ultrafine composite powder (C) were lower than those of ultrafine powder and blend, while its soluble dietary fiber was higher than that of ultrafine powder and blend. Studies have found that grinding disrupts the structure of wheat bran, increasing the content of soluble dietary fiber. This facilitates the interaction between soluble dietary fiber and exogenously added protein during ultrafine grinding, promoting the formation of the gluten protein network and thus improving the toughness, extensibility, and stretchability of the dough formed from the powder. However, the effect of adding protein after grinding is weaker than during the grinding process.

[0120] In summary, when glutenin and wheat bran are ground together to obtain wheat bran / protein ultrafine composite powder, the new whole wheat flour exhibits significant advantages in toughness, extensibility, and stretchability when the amount added to the bran-free medium-gluten flour exceeds 20%.

[0121] (2) Wheat bran-glutenin ultrafine powdering improves the powder properties of whole wheat flour.

[0122] Table 6. Comparison of the powder characteristics of novel whole wheat flour prepared by backfilling with the same amount of wheat bran ultrafine powder (A), wheat bran ultrafine powder / protein mixed powder (B), and wheat bran / protein ultrafine composite powder (C).

[0123]

[0124] Different capital letters in the same column under the same additive amount indicate significant differences between samples under different processing methods (P<0.05).

[0125] The study found that the dough formation time, defined as the time it takes for the dough to reach consistency C1 after mixing flour and water, reflects the speed at which the flour forms a dough. As shown in Table 6, when the addition amount is 5-25%, the formation time of whole wheat flour with added ultrafine wheat bran powder (A) is significantly longer than that of whole wheat flour with added ultrafine wheat bran powder / protein blend (B) and ultrafine wheat bran / protein composite powder (C), indicating that exogenous addition of glutenin helps in the formation of novel whole wheat flour dough under the B and C processing methods. However, at the above addition amounts, the addition of protein during and after ultrafine grinding has no significant effect on the speed of dough formation of the novel whole wheat flour.

[0126] Stability time characterizes the strength and kneadability of dough; a longer stability time indicates a stronger gluten network. As shown in Table 6, when the addition amount is 5-15%, the stability time of whole wheat flour with added ultrafine wheat bran powder (A) is significantly lower than that of whole wheat flour with added ultrafine wheat bran powder / protein blend (B) and ultrafine wheat bran / protein composite powder (C). Notably, when the addition amount is greater than 20%, whole wheat flour with ultrafine wheat bran / protein composite powder shows a significant advantage in stability time, with a significantly longer stability time than whole wheat flour with added ultrafine wheat bran powder / protein blend. This indicates that when the addition amount is greater than 20%, the exogenous addition of glutenin during the ultrafine grinding process contributes to the strength and kneadability of the dough formed by the novel whole wheat flour prepared with ultrafine wheat bran / protein composite powder, and helps to form a strong gluten network.

[0127] Protein attenuation C1-C2 is used to characterize the resistance of flour to mechanical mixing and temperature. A higher value indicates greater protein attenuation and weaker gluten strength in the dough. As shown in Table 6, when the addition amount is greater than 10%, whole wheat flour with bran / protein ultrafine composite powder (C) exhibits a significant advantage, with significantly enhanced gluten strength, superior to whole wheat flour with added bran ultrafine powder (A) and bran ultrafine powder / protein blend (B). When the addition amount is greater than 20%, the gluten strength of the new whole wheat flour dough treated with B and C processes is superior to that with added bran ultrafine powder (A), indicating that exogenous addition of glutenin contributes to its gluten strength.

[0128] In summary, when glutenin and wheat bran are ground together to obtain wheat bran / protein ultrafine composite powder, the new whole wheat flour forms dough faster, with better dough strength and kneadability, and the gluten strength also shows a significant advantage when the amount added to the bran-free medium-gluten flour is greater than 20%. Based on the results of tensile characteristics, it is preferable to add 20-25% of the bran-free medium-gluten flour to increase the utilization rate of wheat bran and improve its nutritional quality characteristics. In this embodiment, the moisture content of the whole wheat flour ranges from 12% to 14%. The tensile properties of the whole wheat flour are measured, and the corresponding tensile property parameters are: toughness range of 188.33-189.67 mm, extensibility range of 27.33-30.12 mm, and configuration ratio range of 9.91-10.38. The flour properties of the whole wheat flour are measured, and the corresponding flour property parameters are: formation time range of 1.03-1.25 min, stability time range of 9.23-9.25 min, and protein weakening degree range of 0.60-0.62 N / M.

[0129] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing whole wheat flour filled with wheat endogenous protein / wheat bran composite ultrafine powder, characterized in that, The method modifies wheat bran by ultrafine grinding and synergistic use of intermolecular interactions to obtain wheat endogenous protein / wheat bran composite ultrafine powder. The modification process improves the whiteness of the wheat bran ultrafine powder, reduces its particle size, increases the soluble dietary fiber content, and enhances its water-holding capacity, oil-holding capacity, and swelling capacity. The wheat endogenous protein / wheat bran composite ultrafine powder was added back into the bran-free powder to prepare whole wheat flour. The method specifically includes: (1) Mix the pretreated wheat bran and wheat endogenous protein in a certain proportion to prepare a wheat endogenous protein / wheat bran mixture; (2) The wheat endogenous protein / wheat bran mixture is added to an ultra-fine pulverizer and ultra-finely pulverized at 4-10 °C for 25-30 min to obtain wheat endogenous protein / wheat bran composite ultra-fine powder; (3) The wheat endogenous protein / wheat bran composite ultrafine powder is added back to the bran-free powder in a certain proportion to prepare whole wheat flour; In step (1), the mass fraction of the wheat endogenous protein / wheat bran mixture is 1-5%, and the mass fraction of the wheat bran is 95-99%. The types of endogenous wheat proteins include: glutenin and / or gliadin; In step (3), the mass fraction of the wheat endogenous protein / wheat bran composite ultrafine powder in the whole wheat flour ranges from 20-25%, and the mass fraction of the bran-free powder ranges from 75-80%.

2. The method for preparing whole wheat flour with backfilled wheat endogenous protein / wheat bran composite ultrafine powder according to claim 1, characterized in that, The particle size range of the wheat endogenous protein / wheat bran composite ultrafine powder is 8.68-8.84 μm, the mass fraction of soluble dietary fiber in the wheat endogenous protein / wheat bran composite ultrafine powder is 8.05-10.31%, the whiteness range is 82.89-83.08%, the water holding capacity range is 2.90-2.97 g / g, the oil holding capacity range is 1.75-1.82 g / g, and the swelling power range is 2.79-3.12 mL / g.

3. The method for preparing whole wheat flour with backfilled wheat endogenous protein / wheat bran composite ultrafine powder according to claim 1, characterized in that, The wheat endogenous protein / wheat bran composite ultrafine powder and the bran-free powder are placed in a mixer and mixed. The parameters of the mixer are set as follows: powder filling rate of 30-40%, mixing time of 30-40 min, and rotation speed of 40-60 r / min.

4. The method for preparing whole wheat flour with backfilled wheat endogenous protein / wheat bran composite ultrafine powder according to claim 1, characterized in that, In step (1), the pretreatment steps of the pretreated wheat bran include sieving, ultrasonic cleaning, filtration, superheated steam sterilization, and drying. The ultrasonic cleaning step conditions are: temperature 50-60 ℃, power 160-180 W, time 10-20 min; the water control conditions in the filtration step are: filter and control water on a 60-mesh sieve until the moisture content of the wet wheat bran is 35-60%; the superheated steam sterilization process conditions are: temperature 110-120 ℃, time 30-40 min; the drying conditions are: set the temperature of the constant temperature drying oven to 40-60 ℃, and dry until the moisture content of the dry wheat bran is 8-12%.

5. A whole wheat flour filled with wheat endogenous protein / wheat bran composite ultrafine powder, prepared by the method described in any one of claims 1-4, characterized in that, The whole wheat flour includes wheat endogenous protein / wheat bran composite ultrafine powder and bran-free powder. In the whole wheat flour, the mass fraction of the wheat endogenous protein / wheat bran composite ultrafine powder ranges from 20-25%, and the mass fraction of the bran-free powder ranges from 75-80%.

6. The whole wheat flour with backfilled wheat endogenous protein / wheat bran composite ultrafine powder according to claim 5, characterized in that, The moisture content of the whole wheat flour ranges from 12% to 14%. The tensile properties of the whole wheat flour were measured, and the corresponding tensile property parameters were: toughness range of 188.33-189.67 mm, extensibility range of 27.33-30.12 mm, and configuration ratio range of 9.91-10.

38. The whole wheat flour was subjected to a flour quality characteristic test, and the corresponding flour quality characteristic parameters were: formation time range of 1.03-1.25 min, stability time range of 9.23-9.25 min, and protein weakening degree range of 0.60-0.62 N / M.

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