Method for prolonging preservation time of wheat bran as well as product and application thereof

Abstract

The invention discloses a method for prolonging the preservation time of wheat bran as well as a product and application thereof. The method comprises the following steps: firstly, pretreating wheat bran by utilizing microwave-vacuum drying, putting the dried wheat bran into an ultrafine grinder for grinding, adding water into the ground wheat bran according to a certain proportion, regulating the particle size uniformity of a wheat bran aqueous solution through high-pressure homogenization, and measuring that the particle size of the wheat bran is less than 10 microns; and adding wheat flour in proportion, and uniformly mixing to obtain the whole wheat dough for use. By utilizing the process, the pretreatment time of the wheat bran can be greatly shortened, the shelf life is prolonged, the problem of rough taste of the wheat bran can be improved while the wheat bran can be massively used, and the processing quantity is greatly increased. When the wheat bran is applied to food, such as steamed buns, bread and noodles, the content of dietary fibers of products can be increased, the rough taste of the wheat bran can be improved, and the wheat bran has important significance for developing high-added-value products of the wheat bran.

Description

Technical Field

[0001] The invention relates to a method for prolonging the storage time of wheat bran, a product and an application thereof, and belongs to the field of wheat bran. Background Art

[0002] Wheat bran is the byproduct left after wheat flour processing, including the seed coat, pericarp, pearly layer and endosperm layer in the structure of wheat grains, accounting for about 15% of the whole wheat grain. Wheat bran is mainly composed of starch, protein, phenolic substances, dietary fiber, vitamins and minerals, among which dietary fiber content accounts for about 40% to 45%, and can be used as a raw material for dietary fiber in food. It is believed to help improve intestinal health, prevent colon cancer and cardiovascular diseases, and is a natural resource with extremely outstanding nutritional value. my country is a major wheat planting and production country. In recent years, the annual output has reached 100 million tons, and wheat bran has reached 2,000 tons. Due to the high biological enzyme activity of wheat bran, it is easy to cause the quality of bran to deteriorate, and the taste is rough when eaten, resulting in the utilization rate of wheat bran in food deep processing is less than 20%, and the economic value is low. At present, wheat bran has broad market prospects in the food processing industry, and has huge future development potential and market advantages.

[0003] With the continuous improvement of self-care awareness, the dietary therapy concept of "preventive treatment" has become a new requirement for people's diet. People have gradually realized the importance of adding or retaining bran in food. The research and development of foods rich in dietary fiber has become a hot topic in the current food processing field. People do not excessively pursue the appearance and taste of food, but further put forward functional requirements. The new demand for high dietary fiber foods of "nutrition, safety, health, and diversity" has become the "new normal" for the development of the food processing industry. The introduction of the concept of "full nutrition" of food has made the development of "whole grain" food a current research hotspot, which also provides a favorable opportunity for the comprehensive utilization of wheat bran in food. The traditional dry heat treatment method has a slow drying speed. During the drying process, the high temperature will cause the wheat bran to lose some nutrients, and the drying process also accelerates the oxidation rate of the wheat bran. Therefore, there is an urgent need for a new drying method that can dry quickly at a lower temperature. Summary of the invention

[0004] Purpose of the invention: The technical problem to be solved by the present invention is to provide a novel and convenient method for prolonging the storage time of wheat bran and its product and application.

[0005] Technical solution: In order to solve the above technical problems, the present invention provides a method for prolonging the storage time of wheat bran, comprising the following steps: putting the wheat bran into a microwave vacuum dryer, setting the vacuum degree to -0.095Mpa, the microwave power to 200W to 400W, the drying time to 3 to 15min, and then drying.

[0006] Preferably, the microwave power is 300W-400W.

[0007] Preferably, the drying time is 6 to 15 minutes.

[0008] Preferably, the drying time is 9 to 15 minutes.

[0009] Preferably, the drying time is 12 to 15 minutes.

[0010] The method further comprises ultrafine grinding the dried wheat bran.

[0011] The invention also provides wheat bran prepared by the method.

[0012] The invention also provides application of the wheat bran in preparing high dietary fiber food.

[0013] Among them, the high dietary fiber foods include whole wheat steamed buns, bread, and high-fiber noodles.

[0014] Wherein, the added amount of the wheat bran is 15% to 30%.

[0015] The particle size of the wheat bran is distributed in the range of 1.5 μm to 95 μm, and the average particle size is 9.7 μm.

[0016] In order to solve the problems that bran has high biological enzyme activity, short shelf life, rough taste, poor edibility, etc., which are not conducive to development and utilization, the present invention proposes to increase the pretreatment link to eliminate the adverse effects caused by bran on the basis of fully recognizing its raw material characteristics. Vacuum drying is a drying method that appropriately heats under negative pressure to reach the boiling point. Since decompression can achieve low-temperature and effective drying, it is a clean and efficient pretreatment technology with advantages such as rapid drying of bran at low temperature and rapid enzyme inactivation. In recent years, it has received widespread attention in the field of food processing. Ultrafine grinding, as a new type of food processing modification method, refers to overcoming the cohesive force inside the crushed material through physical shear extrusion and other technologies, so as to achieve the purpose of greatly reducing the particle size of the material. The material can be crushed into micron or even nanometer powder to increase its specific surface area and porosity. Combined with high-pressure homogenization technology, it can better regulate its particle size uniformity and flexibility.

[0017] The invention can effectively prolong the shelf life and improve the taste of wheat bran by applying the ultrafine grinding technology to the microwave vacuum dried wheat bran.

[0018] The wheat bran has high biological enzyme activity, and the wheat bran lipids are easily oxidized and rancid, which leads to the deterioration of the quality of the wheat bran; the wheat bran is flaky in appearance, and the insoluble fiber makes its texture relatively hard. The many nutrients it is rich in have low solubility, are not easy to be digested and absorbed, and have a rough taste when eaten, and have low utilization rate in deep food processing. The present invention provides a new and convenient drying method-microwave vacuum drying can minimize the damage to its tissue morphology, and retain the original color and shape of the wheat bran to a great extent. The rough taste of wheat bran mainly comes from its dense natural structure of a large amount of insoluble cellulose, which is not easy to be digested and absorbed. Ultrafine grinding can crush the wheat bran to a smaller particle size, and a large amount of cellulose is crushed. Combined with high-pressure homogenization technology, it can better regulate its particle size uniformity and flexibility, and improve its rough taste.

[0019] In the present invention, microwave vacuum drying is used as a pretreatment method to increase the storage period of wheat bran. Whether the wheat bran is subjected to microwave vacuum drying and then ultrafine grinding and high-pressure homogenization treatment has little effect on the quality of the product, but the wheat bran subjected to microwave vacuum drying has better storage stability. It can also be seen from the experimental results of microwave vacuum drying on the fatty acid value, peroxide value and total bacterial count of wheat bran that the storage stability of the product made from the wheat bran subjected to microwave vacuum drying is better than that of the product made from the wheat bran without microwave vacuum drying; and the effect of combining ultrafine grinding with microwave vacuum drying is far better than that of using ultrafine grinding or microwave vacuum drying alone.

[0020] Therefore, the present invention provides a method for efficiently utilizing stabilized wheat bran - microwave-vacuum drying of bran followed by ultrafine grinding combined with high-pressure homogenization technology. The rate of increase of the peroxide value of the bran during microwave vacuum drying is significantly reduced, the microbial colony inactivation effect is obvious, the fatty acid value is significantly reduced, the storage stability of the wheat bran is improved, and the shelf life of the bran is extended. By significantly reducing the crystallinity of the bran after ultrafine grinding combined with high-pressure homogenization, the manufactured product has a better taste and color, and can be added to food in a larger proportion.

[0021] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: green and environmentally friendly processing has become the most important means in the field of food processing. The use of this process can realize the green, rapid and large-scale utilization of wheat bran, and improve the utilization rate of wheat bran in deep food processing. Microwave-vacuum drying can have a good inactivation ability for biological enzymes and improve its storage stability. Ultrafine grinding combined with high-pressure homogenization can improve the rough taste of wheat bran, increase the dissolution rate of nutrients, and be better digested and absorbed by the human body. This processing and utilization method has a vital impact on the future wheat bran processing industry, and provides a good market prospect and economic planning for the future wheat bran processing market. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1The effect of different drying methods of wheat bran on lipase activity at different drying times;

[0023] Figure 2 The effect of different drying methods on the peroxide value of wheat bran at different drying times (a) or storage times (b);

[0024] Figure 3 The effect of different drying methods on the fatty acid value of wheat bran at different drying times (a) or storage times (b);

[0025] Figure 4 The effect of different drying methods of wheat bran on the total bacterial count under different storage time;

[0026] Figure 5 is the particle size distribution of different samples;

[0027] Figure 6 This is the XRD pattern of ultrafinely ground wheat bran;

[0028] Figure 7 The steamed bread is prepared with different amounts of wheat bran added;

[0029] Figure 8 Whole-wheat bread prepared with different amounts of wheat bran added;

[0030] Fig. 9 The high-fiber noodles were prepared with different amounts of wheat bran added;

[0031] Fig.10 The tensile properties of high-fiber noodles. DETAILED DESCRIPTION

[0032] The technical solution of the present invention is further described below in conjunction with the accompanying drawings.

[0033] Example 1 Effect of drying process on wheat bran lipase activity

[0034] 1. Microwave vacuum wheat bran: select a silica gel tray with an outer diameter of 22 cm and an inner diameter of 20 cm, weigh 240 g of wheat bran and spread it flat on the tray, put the wheat bran into a microwave vacuum dryer, set the vacuum degree to -0.095 MPa, and set the microwave power to 200 W (No. MVD1), 300 W (No. MVD2), and 400 W (No. MVD3). The drying time is 0, 3, 6, 9, 12, and 15 min, respectively. After starting the machine, wait until the vacuum degree rises to the target vacuum degree before turning on the microwave. After drying, put it in a drying container and cool it to room temperature for use. The dried wheat bran is obtained.

[0035] 2. Drying wheat bran in the traditional way: select a silica gel tray with an outer diameter of 22 cm and an inner diameter of 20 cm, weigh 240 g of wheat bran and spread it on the tray, put the wheat bran into a hot air drying oven, set it at 45°C, and dry it for 0, 3, 6, 9, 12, and 15 min respectively. After drying, put it into a drying container and cool it to room temperature for use, and the dried wheat bran (No. HWD1) is obtained.

[0036] Lipase activity determination method of wheat bran: referring to the method of “Grain and Oil Inspection-Determination of Lipase Activity of Grains and Oilseeds: GB / T 5523-2008”, the lipase activity of wheat bran was determined by titration method with soybean oil as substrate.

[0037] Conclusion: If Figure 1 As shown in the figure, the lipase activity dropped rapidly from the initial value of 17.94 mg / g to below 14 mg / g within the first 6 minutes of microwave-vacuum drying, especially the lipase activity of MVD3 dropped to 10.61 mg / g, while the lipase activity of the sample treated with hot air drying hardly changed; after 15 minutes of drying, the lipase activity of MVD1, MVD2, and MVD3 all decreased by more than 35%, especially the lipase activity of MVD3 decreased by nearly 50%. However, after 15 minutes of hot air drying, the lipase activity still retained 95%. This shows that microwave-vacuum drying has a good inactivation effect on lipase.

[0038] Example 2 Effect of drying and storage processes on the peroxide value of wheat bran

[0039] The wheat bran was dried according to the method of Example 1.

[0040] Determination method of peroxide value: Determine the peroxide value of wheat bran with reference to the "National Food Safety Standard - Determination of Peroxide Value in Food: GB5009.227-2016".

[0041] Conclusion: If Figure 2 As shown in the figure, the peroxide value of wheat bran increased to varying degrees during microwave-vacuum drying and hot air drying. Among them, the peroxide value of HAD1 increased most significantly (p < 0.05), from 0.008g / 100g to 0.033g / 100g, indicating that the oxidation degree of wheat bran increased during hot air drying and peroxides were produced. After microwave-vacuum drying, the peroxide values ​​of MVD1, MVD2, and MVD3 increased from 0.008g / 100g to 0.011g / 100g, 0.013g / 100g, and 0.014g / 100g, respectively. This result shows that compared with hot air drying, the lipid hydrolysis and oxidation reaction is inhibited to a certain extent during microwave-vacuum drying.

[0042] During the 90-day storage at room temperature and humidity, the peroxide value of the bran showed an upward trend. The peroxide values ​​of WB1 and HAD1 reached 0.31g / 100g and 0.28g / 100g respectively on the 90th day of storage, while the peroxide values ​​of MVD1, MVD2, and MVD3 were 0.195g / 100g, 0.196g / 100g, and 0.193g / 100g respectively after the 90th day of storage. This shows that the peroxide value of the bran treated with microwave-vacuum drying increased less rapidly than that of the bran treated with hot air drying and untreated bran.

[0043] Example 3 Effect of drying and storage processes on the fatty acid value of wheat bran

[0044] The wheat bran was dried and stored according to the method of Example 2.

[0045] Method: The fatty acid value of wheat bran was determined according to “Determination of fatty acid value of milled cereal products: GB / T 15684-2015”.

[0046] Conclusion: If Figure 3 As shown in the data, hot air drying caused the fatty acid value of wheat bran to increase, while the fatty acid value showed a downward trend during microwave-vacuum drying, and there was no significant difference in fatty acid values ​​among MVD1, MVD2, and MVD3 (p>0.05); the microwave-vacuum drying process reduced the fatty acid value because the starch and protein structure of wheat bran was destroyed during the drying process, which reacted with free fatty acids to form complexes.

[0047] During the entire storage period, the fatty acid value of the bran after drying showed an upward trend, and the fatty acid value of the sample treated with microwave-vacuum drying had the slowest growth rate. At the end of storage, the fatty acid values ​​of MVD1, MVD2, MVD3, HAD1, and WB1 were 103.20 mg KOH / 100 g, 104.40 mg KOH / 100 g, 105.34 mg KOH / 100 g, 189.12 mg KOH / 100 g, and 220.26 mg KOH / 100 g, respectively. The fatty acid values ​​of HAD1 and WB1 exceeded the national quality index standard of edible wheat bran (GB / T 42225-2022 wheat bran) of 120 mg KOH / 100 g on the 45th day of storage. In summary, microwave-vacuum drying significantly slowed down the growth trend of the fatty acid value of wheat bran and improved the storage resistance of wheat bran. Among them, WB1 refers to wheat bran (Wheat Bran; WB) that was not dried during storage.

[0048] Example 4 Effect of storage process on total bacterial count of wheat bran

[0049] (1) Preparation of sample homogenate: Take 5 g of sample, add 45 mL of normal saline and place in an oscillator for 5 h to obtain a 1:10 sample homogenate. Take 1 ml of the 1:10 sample homogenate and add 9 mL of normal saline and oscillate to obtain a 1:100 sample homogenate. Prepare 1:1000, 1:10000, and 1:100000 sample homogenates in sequence.

[0050] (2) Preparation of culture medium: When the sterilized PCA culture medium is cooled to about 50°C, pour 15-20 mL into a culture dish and immediately invert and store after cooling and solidification.

[0051] (3) Cultivation: Take 200uL of the sample solution in (1) and add it to the cooled and solidified culture medium. Use a coating rod to evenly apply the sample solution to the surface of the culture medium. Immediately invert and place flat after coating, and culture in a constant temperature incubator at 37±1℃ for 48h. At the same time, take 200uL of physiological saline and add it to three culture dishes as blank controls.

[0052] The calculation formula is as follows:

[0053]

[0054] Where: C represents the average number of colonies grown on the plate at a certain dilution (CFU / g); V represents the volume of the diluent used when coating the plate (mL); M represents the dilution multiple; m represents the sample mass (g).

[0055] Conclusion: The total number of colonies in all samples gradually increased during storage, and the number of microbial colonies in MVD1, MVD2, and MVD3 was always smaller than that in HAD1 and WB1. Figure 4 It can be seen that the initial microbial colony count of WB1 is 5.83log 10 CFU / g, and there was no significant difference in the initial microbial colony count of HAD1 (p>0.05), indicating that the inactivation effect of hot air drying on microorganisms in this experiment was not obvious. After microwave-vacuum drying, the total number of microbial colonies in wheat bran was significantly reduced (p<0.05), and the initial total number of colonies of MVD1, MVD2, and MVD3 was 5,400 log 10 CFU / g, 5.395log 10 CFU / g, 5.380log 10 CFU / g, indicating that the vacuum environment and temperature changes during the drying process inactivated a large number of microbial colonies, confirming that microwave-vacuum drying has a significant effect on microbial inactivation. In summary, the extension of the shelf life of wheat bran is related to the content of microorganisms in it. Microwave-vacuum drying can significantly reduce the total number of colonies and effectively extend its shelf life.

[0056] Example 5 Measurement of Ultrafine Grinding Wheat Bran Particle Size

[0057] The vacuum degree of -0.095Mpa and the microwave power of 400W were selected as the parameters of microwave-vacuum drying of wheat bran. The bran after microwave-vacuum drying was put into the ultrafine pulverizer to prepare ultrafine bran; the ultrafine bran was used as the research object, and the large-particle bran (262.6μm) and small-particle bran (148.00μm) were used as comparisons. Both the large-particle bran and the small-particle bran were only treated with microwave vacuum drying without ultrafine pulverization and high-pressure homogenization.

[0058] Methods: Microtrac laser particle size analyzer was used to analyze the particle size and distribution of wheat bran flour samples.

[0059] Table 1

[0060]

[0061] Conclusion: As shown in Table 1 and Figure 5 As shown in the figure, the average particle size of large-particle bran is 262.6μm, and the average particle size of small-particle bran is 148.0μm; after ultrafine grinding combined with high-pressure homogenization, the average particle size, volume average diameter, and surface area average diameter of the bran are significantly reduced, and the average particle size is reduced from to 9.7μm. From the particle size distribution diagram, it can be seen that the sample particles are concentrated in the area of ​​​​<100μm. This treatment method has good uniformity in the refinement of wheat bran powder and a more concentrated particle size distribution.

[0062] Example 6 Determination of XRD of Ultrafine Grinded Wheat Bran

[0063] Methods: The crystal structure of wheat bran was measured using an X-ray diffractometer (Bruker D2 Phaser, Germany). The Cu-Kα radial was scanned at 40 kV and 30 mA, with a specific scanning angle of 5°-40° and a scanning speed of 5° / min.

[0064] Conclusion: The crystal structure of wheat bran was characterized by X-ray diffraction, and its crystal index (CI) was as follows Figure 6 As shown in Figure 2, CI decreased significantly from 9.06% to 2.86% (p<0.05) with the decrease in the average particle size of wheat bran. The decrease in CI may be due to the conversion of the crystalline region into amorphous cellulose and soluble sugars, which is caused by the destruction of hydrogen bonds in the crystalline regions of cellulose and hemicellulose after strong mechanical action, indicating that part of the insoluble dietary fiber of the sample was converted into soluble dietary fiber, the crystallinity decreased, and the taste was improved.

[0065] Example 7 Preparation of Whole Wheat Steamed Bread

[0066] Preparation of steamed buns: Mix wheat bran and wheat flour in proportion (the total weight of bran and wheat flour is 250g, calculated based on the moisture content of 14%), add 125g water, 2.5g yeast powder, and 5g sugar and mix evenly, use a dough mixer at gear 1 to mix into a dough, and mix at gear 5 for 10min; ferment at 40℃ for 45min, knead the fermented dough vigorously until it is smooth, take a small piece and knead it into a uniform round shape; continue to ferment at 40℃ for 15min, steam for 10min after the steamer is steaming, turn off the heat and cover for 2min, then take out. Figure 7 shown.

[0067] Example 8 Determination of Steamed Bread Color

[0068] Method: The L*, a* and b* of steamed bread were measured using a colorimeter. Among them, L*: represents the brightness of the object, ranging from 0 to 100. 0 represents pure black, and 100 represents pure white, which intuitively reflects the brightness of the color of the object. For example, when the L value is very low, the color will appear black or gray; the higher the L value, the brighter the color.

[0069] a*: represents the red-green color of an object. A positive value indicates that the color is more red, and a negative value indicates that the color is more green. b*: represents the yellow-blue color of an object. A positive value indicates that the color is more yellow, and a negative value indicates that the color is more blue.

[0070] The colors of steamed bread made by mixing wheat bran of different particle sizes with wheat flour at a ratio of 0%, 15%, and 30% are shown in Table 2.

[0071] Table 2

[0072]

[0073]

[0074] Conclusion: With the increase of wheat bran ratio, the L* of steamed bread color decreases, a* and b* increase, that is, the color of steamed bread darkens. When the same proportion of wheat bran is added, the L* of steamed bread and microwave steamed bread made of superfinely crushed wheat bran is smaller, a* and b* are larger, and the color is darker. This is because superfinely crushed wheat bran increases soluble substances. Among them, the letters in the upper right corner of the table indicate significant differences, and different letters indicate significant differences (P < 0.05).

[0075] Example 9 Determination of steamed bread texture

[0076] Method: The texture of steamed bread was analyzed by a texture analyzer. A P / 36R probe was used. The speed before the test was 1 mm / s; the test speed was 1 mm / s; the speed after the test was 1 mm / s; the interval between two compressions was 5 s, the trigger force was 5 g, and the experiment was repeated 6 times.

[0077] Table 3

[0078]

[0079] Conclusion: As shown in Table 3, when steamed bread was made with wheat bran of different particle sizes at a ratio of 0%, 15%, and 30% and wheat flour, it was found that as the proportion of wheat bran increased, the hardness, adhesiveness, and chewiness of the steamed bread increased, while the elasticity, cohesion, and resilience decreased, indicating that as the proportion of wheat bran increased, the quality of steamed bread tended to weaken. When the same proportion of wheat bran was added, the texture of steamed bread made with wheat bran of different particle sizes was not much different.

[0080] Example 10 Preparation of whole wheat bread

[0081] Preparation of bread: bran and wheat flour weigh 250g (based on 14% moisture content), add 150g milk, 40g sugar, 6g salt, and 1 egg; use a dough mixer to mix into a dough at gear 1, and mix at gear 3 for 5min; then add 20g butter and 7.5g yeast at gear 3 and continue mixing for 6min; mix the bran and wheat flour evenly according to the proportion and ferment at 40℃ until the volume doubles (about 50min), squeeze out the air from the dough after fermentation, and let it rise at room temperature for 10min, roll it into a dough after the rising, and ferment it at 40℃ for 50min; preheat the oven and bake at 160℃ for 25min. Figure 8 shown.

[0082] Example 11 Determination of bread color

[0083] Method: The L*, a* and b* of steamed bread were measured by colorimeter.

[0084] Table 4

[0085]

[0086] Conclusion: As shown in Table 4, when wheat bran with different particle sizes was added to wheat flour at a ratio of 0%, 15%, and 30%, it was found that with the increase of the proportion of wheat bran, the L* and b* of the bread color showed a decreasing trend, and a* showed an increasing trend. When the same proportion of wheat bran was added, the L* and b* of the steamed bread and microwave steamed bread made with ultrafinely crushed wheat bran were smaller, a* was larger, and the color was darker, which may be because ultrafine grinding can increase the soluble matter of wheat bran.

[0087] Example 12 Determination of bread texture

[0088] Method: The texture of bread was analyzed by a texture analyzer. A P / 36R probe was used. The speed before the test was 1 mm / s; the test speed was 1 mm / s; the speed after the test was 1 mm / s; the interval between two compressions was 5 s, the trigger force was 5 g, and the experiment was repeated 6 times.

[0089] Table 5

[0090]

[0091] Conclusion: As shown in Table 5, when wheat bran with different particle sizes was added to wheat flour at a ratio of 0%, 15%, and 30%, it was found that with the increase of the proportion of wheat bran, the hardness, adhesiveness, and chewiness of the bread increased, and the elasticity, cohesion, and resilience decreased, indicating that with the increase of the proportion of wheat bran, the quality of the bread tended to weaken, but still maintained a high quality parameter. When the same proportion of wheat bran was added, the texture of bread made with wheat bran of different particle sizes was not much different.

[0092] Example 13 Preparation of high-fiber noodles

[0093] Mix wheat bran and wheat flour in proportion (the total weight of bran and wheat flour is 200g, calculated based on the moisture content of 14%), add 84g water and 2g salt; put into a dough mixer and stir at gear 3 for 5min until the mixture is evenly mixed, then adjust to gear 5 and continue stirring for 5min, press evenly with a rolling pin, stir at gear 5 for another 5min, take out and press flat and let stand for 30min to obtain a high-fiber dough; use a dough press to press repeatedly until the surface of the dough is smooth, and use the dough presser's built-in shredding device to obtain noodles ( Fig. 9 ).

[0094] Example 14 Determination of high fiber noodle quality

[0095] Preparation of noodles: The total weight of bran wheat flour is 200g (based on 14% moisture content), add 84mL water and 2g salt; put it into a noodle mixer and stir at gear 3 for 5 minutes until it is evenly mixed, then adjust to gear 5 and continue stirring for 5 minutes, press it evenly with a rolling pin, stir it at gear 5 for another 5 minutes, take it out, press it flat and let it stand for 30 minutes to obtain a high-fiber dough; use a noodle press to press repeatedly until the surface of the dough is smooth, and use the noodle press's built-in shredding tool to obtain noodles.

[0096] Method: Breakage rate: Take 40 noodles and put them into a pot filled with 50 times boiling water. Put the noodles into the pot and keep the water boiling. After cooking for 2 minutes, pick out the noodles and calculate the breakage rate.

[0097] Cooking water absorption rate and cooking loss rate: weigh about 10g of sample, accurate to 0.1g, put it into a pot with 500mL boiling water, put the noodles into the pot, keep the water boiling, pick out the noodles after cooking for two minutes, soak them in 25℃ deionized water for 30s, use filter paper to absorb excess water on the surface of the noodles, weigh and calculate the cooking water absorption rate; after the noodle soup is left at room temperature, transfer it to a 500mL volumetric flask to make up the volume and mix well, draw 50mL of noodle soup and pour it into a constant weight 250mL beaker, boil and evaporate most of the water, then add 50mL of noodle soup and continue to evaporate until almost dry, transfer it to a 105℃ oven to dry until constant weight, and calculate the cooking loss rate.

[0098] Table 6

[0099]

[0100] Conclusion: From Table 6, we can see that the cooking loss rate of all samples is less than 10%, and the cooking loss rate gradually decreases with the decrease of particle size; the breakage rate of high-fiber noodles made with bran particle sizes of 148.0μm and 9.7μm is small, which can meet the basic requirements of daily consumption, and there is no significant difference in the cooking water absorption rate of noodles.

[0101] Example 15 Determination of high fiber noodle texture

[0102] Shear hardness: Use a texture analyzer with an A / LKB-F probe to measure the shear hardness of noodles. Place six noodles flatly under the probe in sequence. Set the parameters to 2mm / s before measurement, 0.8mm / s during measurement, 2mm / s after measurement, and set the deformation to 90%. The trigger force is 5.0g, and the experiment is repeated six times.

[0103] TPA test: Use P36R probe to measure the texture of noodles. Place six noodles flatly under the probe. Set the parameters to 2mm / s before measurement, 1mm / s during measurement, 2mm / s after measurement, and set the deformation to 75%. Trigger force 5.0g, repeat the experiment six times.

[0104] Table 7

[0105] Conclusion: The shear hardness of all samples with added bran is not much different from that of noodles made from pure flour, and the particle size is 262.6

[0106]

[0107] The shear hardness of high-fiber noodles made from wheat bran with 0.1 μm was significantly lower; with the increase of bran content, the hardness, elasticity and chewiness of the noodles increased, indicating that although the gluten network of noodles weakened with the increase of bran content, the elasticity was maintained well.

[0108] Example 16 Tensile properties of high-fiber noodles

[0109] Method: The maximum tensile length of noodles was measured using a universal testing instrument. The noodles were boiled for 2 minutes and then straightened and fixed on the clamp of the tensile instrument. The measured length was 5.0 cm, the tensile speed was 25 mm / min, and the elongation at break was the ratio of the total length of the noodles when they broke to the measured length of the noodles. The experiment was repeated six times.

[0110] Conclusion: If Fig.10As shown in the figure, the tensile length of noodles after adding wheat bran showed a downward trend, and the downward trend became more obvious as the proportion of wheat bran added increased. As the particle size of wheat bran decreased, when the same proportion of bran was added, the tensile length of noodles increased significantly, and the breaking force also showed an increasing trend. This shows that the smaller the particle size of the added bran, the better its tensile properties.

[0111] In summary, after microwave vacuum drying and then ultrafine grinding combined with high-pressure homogenization, wheat bran improves storage stability and effectively increases shelf life; large-scale dietary fiber in wheat bran is crushed, the overall particles are less than 10μm, the rough taste is improved, and it can be added to food in large proportions. When adding the same proportion of wheat bran with different particle sizes, the texture of steamed bread and bread made from ultrafinely ground bran is not significantly weakened, but the taste is significantly improved. Noodles made from ultrafinely ground bran have better breaking rate and cooking loss rate, and the texture data elasticity and chewiness are also better.

Claims

1. A method for extending the storage time of wheat bran, characterized in that: The following steps are involved: Put the wheat bran into a microwave vacuum dryer with a microwave power of 200W to 400W and a drying time of 3 to 15 minutes.

2. The method according to claim 1, characterized in that: The microwave power is 300W-400W.

3. The method according to claim 1 or 2, characterized in that: The method also comprises super-finely grinding the dried wheat bran.

4. Wheat bran prepared by the method of claim 3.

5. Use of the wheat bran according to claim 4 in preparing high dietary fiber food.

6. The use according to claim 5, characterized in that: The high dietary fiber foods include whole wheat steamed bread, bread, and high-fiber noodles.

7. The use according to claim 5, characterized in that: The added amount of the wheat bran is 15% to 30%.

8. The use according to claim 5, characterized in that: The particle size of wheat bran is distributed in the range of 1.5μm-95μm.

Images