Coarse cereal food processing method based on biological enzyme-physical field coupling

Abstract

The invention discloses a coarse cereal food processing method based on biological enzyme-physical field coupling, and belongs to the technical field of coarse cereal food processing and utilization. The preparation method comprises the following steps: firstly, mixing pure coarse cereal powder with a compound modified material, and premixing to obtain a premix; adding deionized water, a compound flavourzyme solution and carboxymethyl chitosan into the premix for enzymolysis, performing ultrasonic and pulsed electric field cooperative treatment after enzymolysis is finished, performing vacuum concentration after treatment, adding trehalose and modified diatomite, and uniformly mixing to obtain a coupling modified material; then kneading dough, adding food-grade glycerol during dough kneading, rolling, and cutting into strips to obtain noodle blanks; and finally, carrying out gradient drying on the noodle blanks, introducing nitrogen in the drying process, and obtaining the brewing instant coarse cereal noodles after the drying is finished. The method effectively solves the problems of non-uniform rehydration, unstable forming, high storage embrittlement rate, turbid soup and the like of the brewing instant coarse cereal noodles, and meets the industrial production requirements of the brewing instant coarse cereal noodles.

Description

Technical Field

[0001] This invention belongs to the field of whole grain food processing technology, specifically a whole grain food processing method based on biological enzyme-physical field coupling. Background Technology

[0002] As a staple food ingredient with balanced nutrition, whole grains have seen a continuous increase in market demand in recent years due to the popularization of healthy consumption concepts. Whole grain noodles are rich in dietary fiber, protein, and various minerals, combining nutrition and convenience. Instant whole grain noodles, in particular, are well-suited to modern fast-paced lifestyles, requiring no complicated cooking and ready to eat after just one soak. With their core advantages of portability and efficiency, they have become a key research and development area in the industry.

[0003] However, in the industrialization process of instant multigrain noodles, the addition of multigrain powder has introduced processing and quality control challenges. Conventional processing techniques struggle to simultaneously ensure the noodles' shaping stability, rehydration performance, and storage quality, becoming a core bottleneck restricting the large-scale production of instant multigrain noodles. Specific technical issues are as follows: Firstly, there is a challenge in balancing rehydration performance with post-rehydration quality. The rapid rehydration of instant multigrain noodles relies on the synergistic effect of starch pregelatinization and the porous structure resulting from drying. However, the uneven distribution of dietary fiber and starch granules in multigrain powder naturally creates localized dense and loose areas, leading to significant differences in local water absorption and expansion rates during rehydration. This results in a dry core and prolonged rehydration time. Simultaneously, multigrain starch has a weak water-holding capacity, and conventional processes struggle to control the interfacial bonding between starch and dietary fiber. This leads to starch dissolution and fiber bundle detachment after rehydration, causing both cloudy broth and broken noodles, severely impacting the eating experience.

[0004] Secondly, the uneven moisture distribution of the whole grain system makes it easy for micro-cracks to form inside the noodles during the drying process. In addition, the starch retrogradation rate of whole grains is fast, and the micro-cracks continue to expand during storage, resulting in an increase in the brittleness rate of the noodles and a decrease in the product's pass rate.

[0005] Third, there is insufficient consistency in processing and rehydration stability. Instant noodles require strict rehydration stability after drying, but whole grain flour lacks a gluten network and cannot form a continuous elastic structure, resulting in poor dough extensibility and shape retention. This easily leads to uneven noodle thickness and large local differences in toughness during processing such as rolling and cutting. Such processing defects cause inconsistent toughness response when rehydrating dried noodles, ultimately resulting in significant batch-to-batch quality fluctuations.

[0006] Fourth, there is a significant problem of sticking to equipment during processing. Small molecule peptides are produced during the enzymatic hydrolysis of grains, which increases the stickiness of the dough and noodle blanks. During processes such as rolling and cutting, these substances easily stick to the rollers and molds of the equipment, which not only affects processing efficiency but also causes damage to the noodle shape and reduces the yield.

[0007] Therefore, it is of great significance to develop a processing method for instant whole grain noodles that can solve the above-mentioned problems of rehydration, storage and processing stability. Summary of the Invention

[0008] The purpose of this invention is to provide a food processing method for whole grains based on bio-enzyme-physical field coupling, which can effectively solve problems such as uneven rehydration, unstable shaping, poor flavor and taste, high brittleness during storage, and cloudy soup in instant whole grain noodles. It can achieve the effects of rapid and uniform rehydration of noodles, good consistency in processing and shaping, intact shape and no off-odor after rehydration, and good storage stability, which is suitable for the industrial production needs of instant noodles.

[0009] The objective of this invention is achieved through the following technical solution: A method for processing whole grain foods based on bio-enzyme-physical field coupling includes the following steps: S1 Pretreatment: Mix pure grain powder with compound modified material, and obtain premixed material after premixing; The compound modified material is a compound of phosphorylated modified soybean protein and acetylated distarch phosphate; S2 Coupling Modification: Deionized water, compound flavor protease solution and carboxymethyl chitosan are added to the premix for enzymatic hydrolysis; after enzymatic hydrolysis, ultrasonic and pulsed electric field synergistic treatment is performed; after treatment, the mixture is concentrated under reduced pressure, and then trehalose and modified diatomaceous earth are added and mixed evenly to obtain the coupled modified material. The modified diatomaceous earth is obtained by first modifying diatomaceous earth with a silane coupling agent and then mixing it with trehalose; S3 molding: The coupled modified material is directly mixed with dough, and food-grade glycerin is added during the mixing process. After rolling and cutting, noodle blanks are obtained. S4 Drying: The noodle blanks are subjected to gradient drying, with nitrogen gas introduced during the drying process. After drying, the instant mixed grain noodles are obtained.

[0010] Preferably, in step S1, the total amount of the compound modified material added is 2.5% to 5% of the mass of pure grain flour, wherein the amount of phosphorylated modified soybean protein added is 2% to 3% of the mass of pure grain flour, and the amount of acetylated distarch phosphate added is 0.5% to 1% of the mass of pure grain flour.

[0011] Preferably, in step S2, the amount of carboxymethyl chitosan added is 0.1% to 0.2% of the mass of the premix.

[0012] Preferably, in step S2, the enzymatic hydrolysis treatment adopts a segmented addition method, specifically: first, a compound flavor protease solution is added to the premix, and pre-hydrolyzes for 5-7 minutes at 40-43℃ and pH 6.2-6.8; then, carboxymethyl chitosan is added, and enzymatic hydrolysis continues for 10-15 minutes. In this scheme, segmented addition helps to ensure that enzymatic hydrolysis and subsequent component regulation are carried out in a step-by-step and orderly manner, improving the overall homogeneity of the system.

[0013] Preferably, in step S2, the ultrasonic treatment is intermittent, with a power of 220-280W and a frequency of 22-24kHz. The ultrasonic treatment lasts for 30 seconds, followed by a 10-second pause, and is repeated for 8-12 minutes. The pulsed electric field has an electric field strength of 28-35kV / cm, a pulse width of 18-25μs, a frequency of 100-150Hz, and a treatment time of 5-8 minutes. The pulsed electric field is introduced during the first 1-4 minutes of ultrasonic treatment. First, the ultrasonic treatment breaks up the small aggregates of the compound modified material, and then the pulsed electric field promotes the uniform dispersion of the compound modified material and the components of the grain system. In this scheme, intermittent ultrasound can effectively break up the aggregated areas of the grain components and expose active sites, thus improving the enzymatic hydrolysis effect. The synergy between the pulsed electric field and ultrasound promotes the uniform dispersion of the system components, helps maintain the appropriate toughness of the noodles, and helps maintain the appropriate degree of starch gelatinization, which in turn helps maintain the internal pore structure of the system and ensures a stable rehydration rate.

[0014] Preferably, in step S2, the amount of trehalose added is 0.5% to 0.8% of the mass of the premix, the amount of modified diatomaceous earth added is 0.05% to 0.1% of the mass of the premix; in the modified diatomaceous earth, the amount of silane coupling agent added is 1.0% to 1.5% of the mass of the diatomaceous earth, and the amount of trehalose added is 2.0% to 3.0% of the mass of the diatomaceous earth.

[0015] Preferably, in step S3, the amount of glycerol added is 0.3% to 0.5% of the mass of the coupling modifier.

[0016] Preferably, in step S4, the specific parameters of the gradient drying are: first, drying with hot air at 62~65℃ and wind speed of 1.2~1.8m / s for 12~18min, and then drying with hot air at 52~55℃ and wind speed of 1.2~1.8m / s for continuous drying.

[0017] In this method, the initial gentle drying facilitates the steady loss of surface moisture, reducing the risk of internal cracks in the later stage; the subsequent low-temperature drying helps to slow down starch retrogradation, reduce noodle brittleness, and, together with the introduction of nitrogen, helps to reduce oxidation and maintain flavor stability, reduce surface crusting, and improve storage stability.

[0018] Preferably, the pure mixed grain powder is one or more of buckwheat powder, quinoa powder, and millet powder mixed in any proportion.

[0019] Compared with the prior art, the beneficial effects of the present invention are: The process of this invention can effectively improve the processing technology of instant multigrain noodles, as detailed below: In the S1 pretreatment step, the phosphorylated soybean protein in the compound modified material can introduce phosphate groups into the soybean protein molecular structure, enhance the hydrophilicity and charge of the protein molecules, provide protein-based elasticity support for the dough, improve the dispersion uniformity of dietary fiber and starch particles in the grains, and effectively alleviate the aggregation of components. The acetylated distarch phosphate can supplement the emulsifying and water-holding stability of the system. The combination of the two forms a complementary and synergistic effect, which not only retains the dispersion and viscosity-reducing advantages of the protein-based modifier, but also enhances the stability of the system through the starch-based modifier, and more efficiently promotes the uniform mixing of subsequent components, greatly reducing the batch-to-batch fluctuations caused by uneven noodle thickness and large local toughness differences during processing.

[0020] In the S2 coupling modification step, the complex flavor protease degrades the large molecular peptides that produce off-flavors in grains, converting them into small molecular amino acids and short peptides without bitterness, effectively reducing the residual bitterness and beany taste in noodles. Carboxymethyl chitosan can form a uniform lubricating film on the surface of dough particles, moderately reducing the surface stickiness of noodles through physical adsorption and steric hindrance, thereby alleviating the problem of sticking to equipment during the forming process. The synergistic treatment of ultrasound and pulsed electric field can disperse component aggregation areas, expose component active sites, promote the uniform dispersion and gentle binding of starch and dietary fiber, and avoid the imbalance of noodle toughness caused by excessive component aggregation. In the modified diatomaceous earth, after modification with a silane coupling agent, amino functional groups are introduced onto the surface of the diatomaceous earth. Amino groups form hydrogen bonds with water molecules and trehalose molecules, enhancing the porous carrier's ability to capture and slowly release water; at the same time, the introduction of amino groups improves its compatibility with components such as protein and starch in the system, solving the aggregation problem and ensuring that the diatomaceous earth is uniformly dispersed in the dough. Modified diatomaceous earth was mixed with a small amount of trehalose. The trehalose was loaded into the porous structure of the diatomaceous earth, improving its dispersion stability within the system and enhancing the synergistic effect between the modified diatomaceous earth and the trehalose. This improved the carrier's directional adsorption and loading capacity for water molecules. The modified diatomaceous earth, with its porous structure, helped support the internal pore structure of the noodles, mitigating the tendency for pore densification and facilitating rapid and uniform rehydration. It also improved the surface crusting problem of the noodles. The trehalose added separately to the system formed inclusion complexes with starch, effectively inhibiting excessive starch pregelatinization, reducing starch dissolution during rehydration, and thus improving the clarity of the broth.

[0021] In the S3 molding step, food-grade glycerin is added during the dough kneading process. This can effectively alleviate the problems of decreased dough water retention and easy cracking caused by the synergistic effect of compound modified materials and carboxymethyl chitosan. At the same time, it can improve the water retention and extensibility of the dough, reduce product loss during processing, and improve the chewy texture of noodles after rehydration.

[0022] In the S4 drying step, the gradient drying method can avoid excessive starch gelatinization and retrogradation, and can also effectively reduce the difference in moisture gradient inside the noodle blank and the generation of micro-cracks. At the same time, the introduction of nitrogen gas during the drying process can effectively inhibit the oxidation of the system, maintain the stability of the noodle flavor, and ultimately significantly improve the storage stability of the noodles.

[0023] In summary, the process of this invention, through the synergistic design of each step, effectively improves the technical problems existing in the conventional processing of instant noodles, such as uneven rehydration, unstable shaping, high brittleness during storage, and turbid soup. It can achieve the technical effects of stable noodle shaping, fast rehydration, balanced flavor, and stable storage, and is suitable for the industrial production needs of instant noodles. Detailed Implementation

[0024] Example 1 1. Preparation of non-commercially available components.

[0025] (1) Preparation of phosphorylated modified soybean protein: Take food-grade soybean protein isolate (protein content ≥90%), add deionized water to prepare a protein suspension with a mass fraction of 10%, adjust the pH to 7.0, heat the water bath to 45℃ and stir (speed 200r / min); add 3% sodium dihydrogen phosphate of soybean protein isolate, stir at constant temperature for 2h, add a small amount of dilute sodium hydroxide during the reaction to maintain the pH stable at 6.8~7.2; after the reaction, spray dry the system (inlet air temperature 180℃, outlet air temperature 80℃), pulverize and pass through an 80 mesh sieve to obtain phosphorylated modified soybean protein. The characteristic absorption peak of the stretching vibration of the phosphate group P=O appeared at 1240 cm-1 by infrared spectroscopy, indicating that the phosphorylation modification was completed.

[0026] (2) Preparation of modified diatomaceous earth: Take food-grade diatomaceous earth, dry it in an oven at 60℃ until the moisture content is ≤5%, and crush it through a 100-mesh sieve; add deionized water to prepare a suspension with a mass fraction of 5%, stir at 250r / min until uniform, add 1.2% of the mass of food-grade KH550 of diatomaceous earth, and stir at 30℃ for 35min; then add 2.5% of the mass of food-grade anhydrous trehalose of diatomaceous earth, and continue to stir at 30℃ for 25min; after the reaction is completed, filter, wash the filter cake repeatedly with deionized water until the washing liquid is neutral, dry it in an oven at 55℃ to constant weight, crush it through a 100-mesh sieve, and obtain modified diatomaceous earth with a pore size distribution of 1~5μm.

[0027] (3) Preparation of compound flavor protease solution: Take commercially available food-grade compound flavor protease (such as Novozymes Flavorzyme® 500MG, enzyme activity ≥1000 U / g, containing endopeptidase and exopeptidase activity), add deionized water to prepare an enzyme solution with a mass fraction of 1%.

[0028] 2. Processing technology of mixed grain noodles.

[0029] S1 Pretreatment: Take 1000g of pure mixed grain flour (buckwheat flour: quinoa flour: millet flour = 1:1:1, mass ratio), add 2.5% of the mass of pure mixed grain flour of compound modified material (where the mass ratio of phosphorylated modified soybean protein and acetylated distarch phosphate is 4:1, and the two are thoroughly mixed), place it in a double helix mixer, stir and premix at 150r / min for 12min at 28℃ to obtain the premix.

[0030] S2 Coupling Modification: ① Enzymatic hydrolysis: Add 2.5 times the weight of the premix of deionized water and 0.5% of the weight of the premix of compound flavor protease solution to the premix. Under the conditions of 42℃ and pH 6.5, stir at 100r / min for 6min for pre-enzymatic hydrolysis. Then add 0.15% of the weight of the premix of food-grade carboxymethyl chitosan (degree of deacetylation ≥85%) and continue stirring for 12min for enzymatic hydrolysis. After the enzymatic hydrolysis is completed, heat the system to 90℃ and stir at a constant temperature for 5min to complete the enzyme inactivation operation. Then cool it down to 40℃ for later use.

[0031] ② Synergistic treatment with ultrasound and pulsed electric field: The enzyme-inactivated system was subjected to intermittent ultrasound treatment with an ultrasound power of 250W and a frequency of 23kHz. The ultrasound was performed for 30s, paused for 10s, and cyclically for 10min. The pulsed electric field was introduced at the 2-minute mark of the ultrasound treatment with an electric field strength of 32kV / cm, a pulse width of 22μs, and a frequency of 125Hz. The treatment was continued for 6min. After the pulsed electric field ended, the ultrasound treatment was continued for another 10min. During the treatment, the system temperature was maintained at 40℃ and the stirring speed was 80r / min.

[0032] ③ Component addition: After ultrasonic-pulse electric field treatment, the mixture is concentrated under reduced pressure (50-55℃, vacuum degree -0.08 to -0.09 MPa) to remove excess water to a solid content of 75%; 0.65% of food-grade anhydrous trehalose and 0.075% of modified diatomaceous earth by weight of the premix are added to the system, and the mixture is stirred at 120 r / min for 8 min to obtain the coupled modified material.

[0033] S3 Forming: Add 0.4% of food-grade glycerin by weight of the coupling modifier to the coupling modifier, place it in a dough mixer, and knead at 200 r / min for 12 min at 30℃; let the kneaded dough rest and rise for 15 min, and then roll it in a gradient rolling mill (the rolling gaps are 5 mm, 3 mm, and 1.5 mm respectively), and cut it into noodle blanks with a width of 2 mm and a thickness of 1.2 mm by a strip cutter.

[0034] S4 Drying: Immediately transfer the noodle dough to a gradient low-temperature hot air circulating dryer. First, dry with hot air at 63℃ and a wind speed of 1.5m / s for 15 minutes, then reduce the temperature to 53℃ and continue drying with hot air at a wind speed of 1.5m / s. When the temperature drops to 53℃, simultaneously introduce nitrogen gas with a purity ≥99.99% at a flow rate of 0.4m / s. Continue drying until the final moisture content of the noodles reaches 9%, then stop drying and nitrogen gas supply. Cool to room temperature, and then sterilize using food-grade microwave (total bacterial count ≤100CFU / g after sterilization). After sterilization, the finished instant multigrain noodles are obtained.

[0035] Example 2 Based on Example 1, some parameters in the processing technology of multigrain noodles were adjusted as follows, with the exception of those not mentioned, which are the same as in Example 1: S1 Pretreatment: The amount of compound modified material added is 3% of the mass of pure grain flour.

[0036] S2 Coupling Modification: ① Add 0.3% of the compound flavor protease solution and 0.1% of the carboxymethyl chitosan. Pre-hydrolyze at 40℃ and pH 6.2 for 5 min, and continue hydrolysis for 10 min. ② Ultrasonic power 220W, frequency 22kHz, cyclic treatment for 8min; electric field strength 28kV / cm, pulse width 18μs, frequency 100Hz, treatment for 5min; ③ Trehalose addition amount: 0.5%, modified diatomaceous earth addition amount: 0.05%.

[0037] S3 molding: 0.3% glycerol added, kneaded at 28°C for 10 min, proofed for 10 min, and calendering and cutting parameters were the same as in Example 1.

[0038] S4 Drying: First dry at 62℃ and 1.2m / s for 12 minutes, then continue drying at 52℃ and 1.2m / s.

[0039] Example 3 Based on Example 1, the following parameters are adjusted as follows, and any not mentioned are the same as in Example 1: S1 Pretreatment: The amount of compound modified material added is 5% of the mass of pure grain flour.

[0040] S2 Coupling Modification: ① The compound flavor protease solution was added at a concentration of 0.8%, and the carboxymethyl chitosan concentration was added at a concentration of 0.2%, at 43℃; ② Ultrasonic power 280W, frequency 24kHz, cyclic treatment for 12min, pulsed electric field introduced in the 4th minute of ultrasonic treatment, electric field strength 35kV / cm, pulse width 25μs, frequency 150Hz, treatment for 8min; ③ Add 0.8% trehalose and 0.1% modified diatomaceous earth (diatomaceous earth pore size 5μm), and stir for 10 min.

[0041] S3 molding: Glycerin addition 0.5%.

[0042] S4 Drying: First, dry at 65℃ and 1.8m / s for 18 minutes, then continue drying at 55℃ and 1.8m / s.

[0043] Comparative Example 1 Compared to Example 1, in the S1 pretreatment, the compound modified material is replaced with an equal mass of phosphorylated modified soybean protein, while the rest of the process and parameters are the same as in Example 1.

[0044] Comparative Example 2 Compared to Example 1, in the S2 coupling modification, after enzymatic hydrolysis, the mixture is directly concentrated under reduced pressure and trehalose and modified diatomaceous earth are added. The ultrasonic and pulsed electric field treatment steps are removed, and the remaining processes and parameters are the same as in Example 1.

[0045] Comparative Example 3 Compared to Example 1, in the S2 coupling modification, the modified diatomaceous earth is replaced with food-grade unmodified diatomaceous earth of equal mass and pore size, while the rest of the processes and parameters are the same as in Example 1.

[0046] Comparative Example 4 Compared to Example 1, in the S3 molding process, no food-grade glycerin is added, and the dough is directly kneaded. All other processes and parameters are the same as in Example 1.

[0047] Comparative Example 5 Compared to Example 1, in the S4 drying process, the gradient drying and nitrogen introduction are replaced with conventional constant temperature hot air drying at 65°C and 1.5m / s until the moisture content of the noodles is 9%. All other processes and parameters are the same as in Example 1.

[0048] Comparative Example 6 Compared to Example 1, in the S2 coupling modification, the compound flavor protease is replaced with an equal mass of a single food-grade neutral protease (enzyme activity ≥1000 U / g), and the rest of the process and parameters are the same as in Example 1.

[0049] Comparative Example 7 Compared to Example 1, in the S2 coupling modification, carboxymethyl chitosan is not added; only a complex flavor protease is added for enzymatic hydrolysis. The rest of the process and parameters are the same as in Example 1.

[0050] Comparative Example 8 Compared to Example 1, in the S2 coupling modification, the modified diatomaceous earth is replaced with an equal mass of diatomaceous earth modified only by a silane coupling agent (preparation method: same as the modified diatomaceous earth steps in Example 1, except that the "adding trehalose" step is deleted), and the rest of the process and parameters are the same as in Example 1.

[0051] Comparative Example 9 Compared to Example 1, in the S2 coupling modification, food-grade anhydrous trehalose was removed, while the rest of the process and parameters were the same as in Example 1.

[0052] In Examples 1-3 and Comparative Examples 1-9, the proportion of pure grain powder to the total mass of dry noodle raw materials (referring to the total mass of pure grain powder, compound modified material, compound flavor protease, carboxymethyl chitosan, trehalose, modified diatomaceous earth, and food-grade glycerol) is ≥50%.

[0053] Comparative Example 10 Compared to Example 1, in the S1 pretreatment, the compound modified material is replaced with an equal mass of acetylated distarch phosphate, while the rest of the process and parameters are the same as in Example 1.

[0054] Experimental Example To verify the technical effects of the instant multigrain noodles prepared by the process of this invention in terms of rehydration performance, forming quality, flavor and texture, and storage stability, experiments were conducted on Examples 1-3 and Comparative Examples 1-9. All experiments were repeated three times in parallel, with a relative standard deviation (RSD) ≤ 5%. The average value was taken as the final result (as shown in Table 1). Specific test indicators are as follows: 1. Rehydration performance and related testing after rehydration: A unified rehydration experiment will be conducted. First, the rehydration performance test will be completed, and then subsequent tests will be carried out on the rehydrated noodles and rehydrated soup.

[0055] (1) Rehydration time: 200 dried noodles without cracks, sticking, and uniform thickness were randomly selected (the uniform thickness test method is to use vernier calipers to randomly measure the diameter of the noodles at three points in the middle section and at both ends. The diameter deviation of all points is ≤0.1mm, which means the noodles are uniform in thickness). Three parallel samples were set up, with 200 noodles in each sample. The noodles were placed in boiling water at 95℃ and gently stirred with a glass rod until the noodles were completely free of hard cores. The unit is min. (2) Rehydration rate: After rehydration, the noodles were taken out and placed on a drain rack to drain the surface moisture for 10 minutes. The total mass of the rehydrated noodles was weighed and calculated according to the formula: Rehydration rate = [(mass of rehydrated noodles - mass of dry noodles) / mass of dry noodles] × 100% (calculated based on the total mass of 200 dry noodles in each sample). (3) Clarity of broth: The broth from the rehydration experiment was collected and its absorbance at a wavelength of 660nm was measured using a spectrophotometer. The lower the absorbance value, the clearer the broth. (4) Integrity after rehydration: After rehydration, count the number of noodles without breaks, fragments, or intact shape in each batch of 200 rehydrated noodles, and calculate the percentage: Integrity after rehydration = Number of noodles without breaks or fragments / 200 × 100%. (5) Odor of rehydrated broth: No odor, slight odor, obvious odor, severe odor. No odor is the best, and severe odor is the worst. Odor refers to: the slight bitterness or beany smell of the grains themselves.

[0056] 2. Molding quality: (1) Forming quality loss rate: 500g of initial dough from Examples 1-3 and Comparative Examples 1-10 were weighed as test samples and recorded as M1. After rolling and cutting the dough into strips according to the corresponding forming process and the predetermined specifications (width 2mm, thickness 1.2mm), all intact and undamaged noodle blanks were collected and the total mass M2 was weighed. The forming quality loss rate was calculated as follows: (M1−M2) / M1 ×100%. This index directly reflects the quality loss caused by dough sticking to the equipment and the breakage of the blanks during the rolling and cutting process.

[0057] (2) Yield: After calendering and cutting, 200 noodle blanks were selected from the complete and undamaged noodle blanks collected in Examples 1-3 and Comparative Examples 1-9 as test samples, and recorded as the total number of noodle blanks N1; after drying according to the corresponding drying process, the finished dried noodles were screened one by one, and the number of qualified finished noodles N2 with no cracks, no sticking, and uniform thickness (measured by vernier calipers, diameter deviation ≤0.1mm) was counted. The yield was calculated as: Yield = N2 / N1 ×100%. This indicator comprehensively reflects the overall loss of the calendering, cutting, drying and forming process.

[0058] 3. Storage stability: 200 pieces of finished dried noodles that are free from cracks and sticking and have uniform thickness were randomly selected, vacuum-packed, and stored at 25℃ and 60% RH for 90 days. After storage, the number of brittle noodles was counted and the brittleness rate was calculated: Brittleness rate = number of brittle noodles / 200 × 100%. Table 1: Quality test results of the examples and comparative examples Note: "-" in the table indicates that the tested items in this experimental group did not perform well and were not suitable for the production requirements of instant multigrain noodles, so this experiment is not necessary. As can be seen from Table 1: Examples 1-3 effectively solve problems such as uneven rehydration, unstable shaping, poor flavor and texture, high brittleness during storage, cloudy broth, and sticking to processing equipment in instant multigrain noodles, thus meeting the industrial production requirements of instant noodles. Specifically, the rehydration time is ≤2.8 min and the rehydration rate is ≥318%, achieving rapid and uniform rehydration of the noodles; the absorbance of the broth is ≤0.09, effectively solving the problem of cloudy rehydration broth; the shaping quality loss rate is ≤1.5% and the yield is ≥96%, with no obvious sticking to equipment or cracking, effectively improving the shaping quality; the integrity after rehydration is ≥97%, avoiding the problem of broken or scattered noodles during rehydration; the rehydration broth is odorless, ensuring the product's flavor and texture; and the brittleness rate after 90 days of storage is ≤1.5%, effectively solving the problem of high brittleness during storage.

[0059] In Comparative Example 1, replacing the compound modified material with a single phosphorylated modified soybean protein resulted in slight turbidity of the broth and a significant increase in the storage brittleness rate. In Comparative Example 2, the removal of the ultrasonic and pulsed electric field synergistic treatment step prevented the dispersal of component aggregation areas, hindering the gentle binding of starch and dietary fiber. This resulted in a dense internal pore structure and poor performance across all indicators. In Comparative Example 3, replacing the modified diatomaceous earth with unmodified diatomaceous earth led to excessive surface hydrophilicity and high surface energy, causing it to easily aggregate in the system. This prevented uniform dispersion and effective support of the noodle's internal pore structure, resulting in uneven pore distribution, increased starch dissolution during rehydration (manifested as increased broth absorbance and reduced integrity after rehydration), and insufficient pore support loosened the noodle's internal structure, making it prone to microcrack expansion during storage and increasing the storage brittleness rate. In Comparative Example 4, the removal of food-grade glycerin resulted in insufficient dough water retention and extensibility, leading to cracking during rolling and cutting, and reduced forming quality. In Comparative Example 5, the use of conventional constant-temperature hot air drying instead of gradient drying and nitrogen introduction failed to alleviate the internal moisture gradient of the noodles, easily leading to micro-cracks. Furthermore, the lack of nitrogen protection resulted in severe oxidation and loss of the grain flavor, increased storage brittleness, and a significant decline in rehydration performance and forming quality. In Comparative Example 6, replacing the compound flavor protease with a single protease failed to efficiently degrade various large-molecule off-flavor peptides in the grains, resulting in a noticeable off-flavor in the rehydrated broth. In Comparative Example 7, the removal of carboxymethyl chitosan prevented its binding with the small-molecule peptides produced by enzymatic hydrolysis, resulting in excessively sticky noodle surfaces that easily stuck to rollers and equipment during processing, thus reducing forming quality. In Comparative Example 8, replacing the composite modified diatomaceous earth with diatomaceous earth modified only by silane coupling agents resulted in insufficient dispersion stability and water absorption capacity, failing to form a synergistic effect with trehalose in the system, and weakening the pore support effect. In Comparative Example 9, the removal of trehalose failed to effectively inhibit excessive starch pregelatinization, leading to increased starch dissolution during rehydration, resulting in cloudy broth, prolonged rehydration time, and increased storage brittleness. In Comparative Example 10, only acetylated distarch phosphate was used, lacking the protein backbone and dispersing synergistic effect provided by phosphorylated modified soybean protein. The resulting noodles were difficult to shape, prone to sticking and breakage, had slow rehydration speed and low rehydration rate, and the broth was cloudy after cooking, making them prone to brittleness during long-term storage.

Claims

1. A method for processing whole grain foods based on bio-enzyme-physical field coupling, characterized in that, Includes the following steps: S1 Pretreatment: Mix pure grain powder with compound modified material, and obtain premixed material after premixing; The compound modified material is a compound of phosphorylated modified soybean protein and acetylated distarch phosphate; S2 Coupling Modification: Deionized water, compound flavor protease solution and carboxymethyl chitosan are added to the premix for enzymatic hydrolysis; after enzymatic hydrolysis, ultrasonic and pulsed electric field synergistic treatment is performed; after treatment, the mixture is concentrated under reduced pressure, and then trehalose and modified diatomaceous earth are added and mixed evenly to obtain the coupled modified material. The modified diatomaceous earth is obtained by first modifying diatomaceous earth with a silane coupling agent and then mixing it with trehalose; S3 molding: The coupled modified material is directly mixed with dough, and food-grade glycerin is added during the mixing process. After rolling and cutting, noodle blanks are obtained. S4 Drying: The noodle blanks are subjected to gradient drying, and nitrogen gas is introduced during the drying process. After drying, instant mixed grain noodles are obtained.

2. The method for processing coarse grain foods according to claim 1, characterized in that, In step S1, the total amount of the compound modified material added is 2.5% to 5% of the mass of pure grain flour, of which the amount of phosphorylated modified soybean protein added is 2% to 3% of the mass of pure grain flour, and the amount of acetylated distarch phosphate added is 0.5% to 1% of the mass of pure grain flour.

3. The method for processing coarse grain foods according to claim 1, characterized in that, In step S2, the amount of carboxymethyl chitosan added is 0.1% to 0.2% of the mass of the premix.

4. The method for processing coarse grain food according to claim 3, characterized in that, In step S2, the enzymatic hydrolysis treatment adopts a segmented addition method, specifically: first, add the compound flavor protease solution to the premix, pre-hydrolyze for 5-7 minutes at 40-43℃ and pH 6.2-6.8, then add carboxymethyl chitosan and continue enzymatic hydrolysis for 10-15 minutes.

5. The method for processing coarse grain food according to claim 1, characterized in that, In step S2, the ultrasonic treatment is intermittent, with a power of 220~280W and a frequency of 22~24kHz. The ultrasonic treatment lasts for 30 seconds, pauses for 10 seconds, and is repeated for 8~12 minutes. The electric field strength of the pulsed electric field is 28~35kV / cm, the pulse width is 18~25μs, the frequency is 100~150Hz, and the processing time is 5~8 minutes.

6. The method for processing coarse grain foods according to claim 1, characterized in that, In step S2, the amount of trehalose added is 0.5% to 0.8% of the mass of the premix, the amount of modified diatomaceous earth added is 0.05% to 0.1% of the mass of the premix, the amount of silane coupling agent added is 1.0% to 1.5% of the mass of the diatomaceous earth, and the amount of trehalose added is 2.0% to 3.0% of the mass of the diatomaceous earth.

7. The method for processing coarse grain food according to claim 1, characterized in that, In step S3, the amount of glycerol added is 0.3% to 0.5% of the mass of the coupling modifier.

8. The method for processing coarse grain food according to claim 1, characterized in that, In step S4, the specific parameters for gradient drying are as follows: first, dry with hot air at 62~65℃ and wind speed of 1.2~1.8m / s for 12~18min, and then continue drying with hot air at 52~55℃ and wind speed of 1.2~1.8m / s.

9. The method for processing coarse grain food according to claim 1, characterized in that, The pure mixed grain powder is made by mixing one or more of buckwheat flour, quinoa flour, and millet flour in any proportion.

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