Preparation method of alumina-free bean flour based on cooperation of magnetic field and mung bean protein improvement

Abstract

The invention relates to the technical field of food processing, and discloses a preparation method of alumina-free bean flour based on cooperation of a magnetic field and mung bean protein improvement, and the preparation method comprises the following steps: S1, uniformly mixing potato starch, starch acetate, pea protein powder and guar gum, adding distilled water, and stirring to form uniform starch slurry; s2, performing wet extrusion molding on the pulp; s3, performing hot water curing treatment on the extruded vermicelli; s4, cooling the cured vermicelli; s5, performing magnetic field freezing treatment on the cooled vermicelli; and S6, drying after unfreezing to obtain a target product. Wherein the component of the alumina-free bean flour is potato starch; starch acetate; pea protein powder; guar gum; and distilled water. The technical scheme of combining magnetic field freezing and mild drying is adopted, the structural stability and the taste of the potato vermicelli are improved, the moisture distribution and the microstructure are optimized through the action of the low-frequency alternating magnetic field, and ice crystal aggregation is prevented.

Description

Technical Field

[0001] This invention relates to the field of food processing technology, specifically to a method for preparing alum-free potato starch based on magnetic field-assisted modification of mung bean protein. Background Technology

[0002] In modern life, consumers have increasingly higher requirements for food quality, especially for the taste, nutrition and safety of processed foods. As a common food ingredient, the quality of potato vermicelli directly affects the eating experience and consumers' health. Therefore, how to improve the structural stability, elasticity and taste of potato vermicelli during the production process has become a key focus for producers.

[0003] In the existing technology, the production process of potato vermicelli mainly relies on traditional freezing technology and drying methods. Through freezing, the vermicelli can maintain a certain stability in shape, and during the drying process, the moisture in the vermicelli evaporates relatively evenly. The addition of protein powder can enhance the toughness and extensibility of the vermicelli and improve its resistance to breakage during use. At the same time, the use of alum leavening agent can also improve the appearance of the vermicelli to a certain extent, making it look more uniform and beautiful.

[0004] However, existing freezing and drying methods still have some shortcomings, affecting the quality of the final product and the consumer's eating experience. In traditional freezing methods, the formation of ice crystals easily damages the internal structure of the vermicelli, resulting in excessive porosity and affecting its elasticity and texture. In addition, some technologies use inappropriate types and proportions of protein powder, failing to fully utilize its cross-linking effect, leading to unstable vermicelli shape and susceptibility to shrinkage and breakage. More importantly, existing leavening agents, such as alum, while improving appearance, may also leave aluminum residues, affecting food safety, and their drying effect often results in surface hardening while the internal structure remains loose. To address these issues, those skilled in the art propose a method for preparing alum-free potato vermicelli based on magnetic field-assisted modification with mung bean protein. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for preparing alum-free potato starch based on magnetic field-assisted mung bean protein modification, which solves the problems of ice crystal destruction caused by freezing, insufficient protein cross-linking, and aluminum residue caused by leavening agents in existing technologies.

[0006] To achieve the above objectives, the present invention provides the following technical solution: an alum-free potato flour modified based on magnetic field-assisted mung bean protein, comprising the following components in parts by weight:

[0007] Potato starch: 60–70 parts;

[0008] Acetate starch: 20–25 parts;

[0009] Pea protein powder: 5–8 servings;

[0010] Guar gum: 2–3 parts;

[0011] Distilled water: 180–220 parts.

[0012] Potato starch: As a main component, potato starch is one of the fundamental ingredients of this invention, providing the powder's viscosity and structural support. The unique structure of the starch molecular chain allows it to interact better with other components during subsequent processing, forming a good gel structure. The selection and proportioning of starch will affect the final product's taste, water absorption, and subsequent processing performance.

[0013] Acetate starch: Acetate starch has strong cold water solubility and acid resistance, which gives it excellent stability in certain acidic environments. The acetate esterification process imparts stronger hydrophilicity to starch molecules, significantly improving their dispersibility and water absorption in water, thereby improving the texture of the final product.

[0014] Pea protein powder: In this invention, pea protein powder plays a role beyond simply providing protein nutrition; it also improves the overall structure of the product through its interaction with starch and other components. Particularly with the addition of a magnetic field, the hydrophobic interactions and hydrogen bonding between pea protein molecules significantly improve the texture, extensibility, and elasticity of the potato starch. Its high purity and specific amino acid composition (such as high branched-chain amino acid content) ensure excellent functionality.

[0015] Guar gum: As a thickener, guar gum can effectively improve the rheological properties of potato starch and enhance the stability of the slurry. It promotes uniformity during the molding process by increasing the viscosity of the slurry and further strengthens the structure of the potato starch during hot water cooking.

[0016] Distilled water: Distilled water acts as a solvent and interacts with other components to help disperse them evenly, ensuring uniformity and stability during the preparation process.

[0017] Preferably, the pea protein powder is a purified protein powder with a protein mass fraction of not less than 80% and a branched-chain amino acid content of not less than 18%.

[0018] The study specifies the selection criteria for pea protein powder: a protein content of no less than 80% and a branched-chain amino acid content of no less than 18%. The high protein content and specific amino acid composition of pea protein (especially branched-chain amino acids) facilitate stronger interactions with other components under physical and chemical processes, particularly enhancing the cross-linking between protein and starch molecules during slurry formation and cooking. Branched-chain amino acids possess strong hydrophobicity, providing greater stability to their complex structure with starch, making potato starch less prone to water loss during heat processing and maintaining a good texture.

[0019] Preferably, the degree of substitution of the acetate starch is 0.02–0.05, and it has cold water solubility and acid resistance.

[0020] The degree of substitution of starch acetate is 0.02–0.05, a ratio that gives starch acetate good cold water solubility and acid resistance. The key to acetate esterification is altering the hydrophilicity of starch through the introduction of acetic acid molecules, thereby enhancing its solubility and dispersibility in water, especially maintaining high stability in acidic environments. This property allows starch acetate to better integrate with other components during preparation, particularly pea protein and guar gum, forming a more homogeneous structure.

[0021] A method for preparing alum-free potato flour based on magnetic field-assisted mung bean protein modification includes the following steps:

[0022] S1. Mix potato starch, acetate starch, pea protein powder and guar gum evenly, add distilled water and stir to form a uniform starch slurry;

[0023] S2. The slurry is wet-extruded and molded;

[0024] S3. Hot water cooking treatment for extruded vermicelli;

[0025] S4. Cool the cooked vermicelli;

[0026] S5. Perform magnetic freezing treatment on the cooled vermicelli;

[0027] S6. After thawing, dry to obtain the target product.

[0028] First, potato starch, acetate starch, pea protein powder and guar gum are evenly mixed and distilled water is added to form a starch slurry. This step ensures the uniform distribution of each component and lays the foundation for the subsequent extrusion and maturation process. Wet extrusion molding ensures that the potato starch particles are of consistent size and shape.

[0029] The innovation of this invention lies in the cooling and magnetic field freezing treatment after the ripening process. The synergistic effect of the magnetic field during the freezing process can change the structural arrangement of starch and protein molecules, further improving the physical properties of potato starch and enhancing its toughness and extensibility. The application of magnetic field freezing can optimize the structure of potato starch by changing the interaction between water molecules and starch molecules, promoting the uniform distribution of water molecules between molecules.

[0030] In addition, the effect of low-frequency alternating magnetic fields, by changing the molecular structure and the arrangement of aggregates, improves the physical and chemical properties of the final potato starch product, giving it better stability and workability.

[0031] Preferably, the stirring speed during the stirring process is 800–1200 rpm, the stirring time is 10–15 minutes, and the viscosity of the resulting slurry is 500–1200 mPa·s.

[0032] During the mixing process, appropriate mixing speed and time ensure good mixing between the components, avoiding precipitation or stratification. In particular, components such as pea protein and acetate starch have complex molecular structures and may form strong intermolecular forces in water, leading to uneven dispersion. By controlling the mixing speed and viscosity, the uniformity of the slurry is ensured, avoiding bubbles or foam caused by over-mixing, thereby improving the effect of subsequent extrusion and molding. The appropriate viscosity of the slurry helps to form a more uniform noodle structure during wet extrusion, while maintaining good stability during subsequent ripening and cooling.

[0033] Preferably, the nozzle diameter used in the extrusion process is 1.2–1.5 mm, and the slurry is extruded by pressure control, with an extrusion pressure of 0.15–0.30 MPa.

[0034] In this process, by precisely controlling the extrusion pressure, the slurry can be extruded evenly and stably at the nozzle, avoiding irregular shapes or residual air bubbles caused by excessive or insufficient pressure. Matching the nozzle diameter to the slurry viscosity helps control the fineness and surface smoothness of the noodles. In traditional preparation methods, an excessively large nozzle diameter can lead to a rough or uneven surface on the noodles, affecting heat conduction during subsequent drying and the final texture of the product.

[0035] Preferably, the curing process is carried out in hot water at 80–85°C for 2.5–4 minutes; the cooling process is carried out in cold water at 4–8°C for 10–20 minutes.

[0036] During hot water cooking, starch molecules undergo hydration, partially converting into dextrin, which enhances the gelling and elasticity of potato starch. Controlling the cooking temperature and time is crucial; excessively high temperatures can lead to over-hydrolysis of starch, while too short a time may result in incomplete starch expansion, affecting subsequent processing. Controlling the cooling process helps stabilize the interaction between starch and protein molecules; cooling to low temperatures effectively locks in moisture, preventing excessive loss or recrystallization, thus maintaining the structure and shape of the potato starch noodles.

[0037] Preferably, the temperature range of the magnetic field freezing process is -12 to -30°C, the applied magnetic field strength is 3–6 mT, and the processing time is 20–40 minutes.

[0038] During magnetic field freezing, the combined effects of low temperature and magnetic field alter the interactions between water and starch molecules, promoting uniform moisture distribution and freezing. The presence of the magnetic field influences molecular arrangement, particularly the interactions between starch and protein molecules, leading to a more uniform microstructure during freezing and thus improving the quality of the final product. Precise control of the magnetic field strength and freezing time ensures optimized molecular structure during freezing, helping to prevent structural loss or excessive moisture evaporation during subsequent thawing and drying.

[0039] Preferably, the magnetic field is a low-frequency alternating magnetic field with a frequency of 0–100Hz, and the magnetic field lines are parallel to the direction of the vermicelli's extension.

[0040] The application of low-frequency alternating magnetic fields can alter the arrangement of starch and protein molecules during freezing, resulting in a more uniform internal structure of the vermicelli. Particularly during freezing, the alternating magnetic field has a unique regulatory effect on the arrangement of water molecules and molecular chains, reducing ice crystal formation and thus improving the quality of the final product. By controlling the frequency and direction of the magnetic field, the structure of potato starch can be more precisely adjusted, making it more stable in subsequent processing.

[0041] Preferably, the drying is carried out in a hot air drying oven at 35–45°C for 6–10 hours, and the moisture content of the final product is controlled at 16–18%.

[0042] During the drying process, an appropriate temperature and time range can effectively prevent the product surface from becoming over-dryed or the internal moisture from remaining incompletely evaporating. Excessively high drying temperatures may cause the surface to harden prematurely, forming a film that hinders further evaporation of internal moisture; conversely, excessively low temperatures may result in excessively high product humidity, affecting its shelf life and taste. Therefore, a drying temperature range of 35–45℃ not only ensures drying efficiency but also prevents excessive dehydration of the potato starch, maintaining product quality.

[0043] This invention provides a method for preparing alum-free potato flour based on magnetic field-assisted modification of mung bean protein. It has the following beneficial effects:

[0044] 1. This invention adopts a technical solution that combines magnetic field freezing with gentle drying, which improves the structural stability and taste of potato vermicelli. Through the action of a low-frequency alternating magnetic field, the moisture distribution and microstructure are optimized, preventing ice crystals from accumulating. Compared with the existing technology that does not use magnetic field freezing, this invention effectively avoids the problem of ice crystals damaging the vermicelli structure during the freezing process, and significantly improves the toughness and elasticity of the vermicelli.

[0045] 2. This invention introduces pea protein powder as an additive and combines it with precise wet extrusion pressure control, which makes the vermicelli more stable in shape and smoother in surface. Compared with traditional technology, this invention makes the vermicelli less prone to shrinkage and breakage during the drying process through the cross-linking effect of proteins, improves the overall structural compactness, and solves the shortcomings of rough surface and uneven shape of vermicelli in traditional process.

[0046] 3. By eliminating the use of alum leavening agents, this invention avoids the risk of aluminum residue while maintaining good sensory performance and food safety. Compared with existing technologies that use alum, the processing method of this invention ensures a lower aluminum content and guarantees the uniformity of the vermicelli drying through gentle drying, thus solving the problems of loose structure and poor taste that may be caused by alum leavening agents. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the preparation method of the present invention. Detailed Implementation

[0048] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0050] Please see the appendix Figure 1 : Example 1:

[0051] Composition ratio: Potato starch: 70 parts; Acetate starch: 20 parts; Pea protein powder: 5 parts; Guar gum: 2 parts; Distilled water: 200 parts.

[0052] Preparation steps:

[0053] 1. Mixing and stirring: Add the above components to the mixing container in the order of proportions. After adding distilled water, start the stirrer at 1000 rpm for 12 minutes until a uniform starch slurry is formed, ensuring that the components are fully dispersed.

[0054] 2. Extrusion molding: The well-stirred starch slurry is wet-extruded through a 1.4mm diameter nozzle at an extrusion pressure of 0.25MPa to ensure that the noodles are uniform in shape and free of air bubbles.

[0055] 3. Hot water maturation: The extruded vermicelli is placed in 80℃ hot water for maturation for 3 minutes. This ensures that the starch molecules undergo a gelatinization reaction, enhancing the elasticity and toughness of the vermicelli.

[0056] 4. Cooling: After cooking, transfer the vermicelli to cold water at 4°C for 15 minutes to stabilize its structure and shape.

[0057] 5. Magnetic field freezing: After cooling, the vermicelli enters a magnetic field freezing device and is frozen at -25℃. The magnetic field strength is set to 4mT, and the freezing time is 30 minutes. The low-frequency alternating magnetic field is used to improve the structure and texture of the potato vermicelli.

[0058] 6. Thawing and Drying: After thawing, the frozen vermicelli is placed in a 35℃ hot air drying oven for drying. The drying time is 8 hours, and the moisture content of the final product is controlled at 16%. Example 2:

[0059] Composition ratio: Potato starch: 65 parts; Acetate starch: 23 parts; Pea protein powder: 6 parts; Guar gum: 2 parts; Distilled water: 210 parts.

[0060] Preparation steps:

[0061] 1. Mixing and stirring: Add all components to the stirrer according to the above ratio. After adding distilled water, start the stirrer and set the stirring speed to 950 rpm for 15 minutes to ensure that all components are evenly mixed to form a uniform slurry.

[0062] 2. Extrusion molding: Wet extrusion is performed using a 1.3mm diameter nozzle at an extrusion pressure of 0.28MPa to ensure that the noodles have a uniform shape and a smooth surface.

[0063] 3. Hot water maturation: The extruded vermicelli is placed in hot water at 85℃ for maturation for 3.5 minutes to ensure that the starch molecules are completely gelatinized and to improve the gelling properties of the vermicelli.

[0064] 4. Cooling: After cooking, place the vermicelli in 4℃ cold water to cool for 12 minutes to ensure its shape is stable and prevent the surface from drying out and cracking.

[0065] 5. Magnetic field freezing: The cooled vermicelli is then subjected to magnetic field freezing at a temperature of -20℃, a magnetic field strength of 5mT, and a processing time of 35 minutes. This low-frequency alternating magnetic field improves the internal structure of the vermicelli, making it more compact.

[0066] 6. Thawing and drying: After the vermicelli is thawed by magnetic field freezing, it is placed in a 40℃ hot air drying oven for drying for 9 hours. The moisture content of the final product is controlled at 17%. Example 3:

[0067] Composition ratio: Potato starch: 68 parts; Acetate starch: 22 parts; Pea protein powder: 4 parts; Guar gum: 2.5 parts; Distilled water: 190 parts.

[0068] Preparation steps:

[0069] 1. Mixing and stirring: Add potato starch, starch acetate, pea protein powder, and guar gum to a mixer in sequence, then add distilled water and stir. Stir at 1100 rpm for 10 minutes, until the slurry is homogeneous and shows no signs of separation.

[0070] 2. Extrusion molding: The well-stirred starch slurry is extruded through a nozzle with a diameter of 1.2mm. The extrusion pressure is set to 0.23MPa to ensure that the noodles have a regular shape and a smooth surface.

[0071] 3. Hot water cooking: The vermicelli is placed in hot water at 82℃ for 2.8 minutes to ensure that the starch is fully hydrated and forms a gel structure.

[0072] 4. Cooling: Immediately place the cooked vermicelli into 6°C cold water to cool for 14 minutes to maintain its original shape and reduce moisture loss.

[0073] 5. Magnetic Field Freezing: After cooling, the vermicelli enters a magnetic field freezing device and is frozen at a low temperature of -30℃. The magnetic field strength is 3.5mT, and the freezing time is 25 minutes. The low-frequency alternating magnetic field causes the vermicelli to form a uniform microstructure during the freezing process.

[0074] 6. Thawing and drying: After the frozen vermicelli is thawed, it is placed in a hot air drying oven at 36℃ for 7 hours. The moisture content of the final product is controlled at 18%.

[0075] Comparative Example 1: The difference from Example 1 is that no pea protein powder was added; otherwise, they are the same.

[0076] Comparative Example 2: Compared with Example 1, the difference is that the magnetic field freezing treatment step is omitted. That is, the cooled vermicelli is not treated with a magnetic field and is directly thawed and dried. Everything else is the same.

[0077] Comparative Example 3: Compared with Example 2, the difference is that the pea protein powder was replaced with an equal mass of corn protein powder, and all other aspects are the same.

[0078] Comparative Example 4: Compared with Example 2, the difference is that the wet extrusion pressure control was removed and replaced with free gravity extrusion, resulting in a loose vermicelli shape. All other aspects are the same.

[0079] Comparative Example 5: Compared with Example 3, the difference is that 100 mg / kg alum was added to the formulation as a leavening agent, and all other aspects are the same.

[0080] Comparative Example 6: Compared with Example 3, the difference is that the magnetic field freezing step was omitted, the drying temperature was increased to 55°C, and the time was shortened to 4 hours, while the rest were the same.

[0081] Experiment 1:

[0082] Experimental objective:

[0083] This experiment aims to investigate the synergistic effects of adding pea protein powder and magnetic field freezing on the structural stability, elasticity, texture, and microstructure of potato vermicelli.

[0084] Experimental steps:

[0085] 1. Sample preparation:

[0086] Prepare three sets of samples: Example 1, Comparative Example 1, and Comparative Example 2.

[0087] 2. Structural strength test (elastic modulus):

[0088] Compression rebound tests were conducted on each group of vermicelli using a texture analyzer (TA.XTplus). The vermicelli was compressed to 30% thickness, and the rebound peak value was read to calculate the elastic modulus.

[0089] 3. Fracture ductility test:

[0090] The dried vermicelli was placed in a bending test device and bent at a speed of 5 mm / min. The displacement (cm) required before the first breakage was recorded.

[0091] 4. Microstructure observation (SEM):

[0092] After sampling, the noodles were subjected to freeze-fracture and gold sputtering. The cross-section of the noodles was then observed using a scanning electron microscope to assess the distribution of pores and the uniformity of the structure.

[0093] 5. Sensory evaluation:

[0094] Ten participants were invited to participate in a blind test, with the following indicators: elasticity (10 points), smoothness (10 points), and overall taste (10 points). The experimental data are shown in Table 1.

[0095] Table 1: Structural properties and sensory scores of vermicelli

[0096]

[0097] From Table 1, we can obtain:

[0098] The introduction of pea protein powder significantly improves the structural strength and extensibility of vermicelli. From a microstructural perspective, pea protein, through its high content of branched-chain amino acids, participates in hydrophobic interactions and hydrogen bond cross-linking between starch and protein, forming a more dense and uniform network structure. SEM images show that it has a lower pore density and a more compact structure, which is directly reflected in higher elastic modulus and stronger bending extensibility.

[0099] In contrast, the sample without magnetic field freezing treatment (Comparative Example 2), even containing pea protein, still exhibited more porosity and structural irregularities in its microstructure. Due to the lack of low-frequency magnetic field regulation during the freezing process, ice crystal formation was uncontrolled, leading to internal tissue rupture and void accumulation. This mechanism validates the crucial role of magnetic field freezing in inhibiting ice crystal aggregation, optimizing moisture distribution, and maintaining gel structure.

[0100] The protein-free sample (Comparative Example 1) exhibited the worst mechanical and sensory performance. Lacking the support of protein cross-linking, the vermicelli was more prone to shrinkage and breakage during drying, resulting in a loose structure, obvious breakage, and generally low sensory scores. Its powdery texture and poor elasticity indicate that the addition of pea protein is an important factor in maintaining the harmony between structure and taste.

[0101] Experiment 2:

[0102] Experimental objective:

[0103] This experiment aims to evaluate the contribution of protein powder type and extrusion pressure control to the consistency of vermicelli morphology, surface quality, and stable structure.

[0104] Experimental steps:

[0105] 1. Sample preparation:

[0106] Three sets of samples: Example 2, Comparative Example 3, and Comparative Example 4.

[0107] 2. Morphological consistency detection:

[0108] A digital image analysis system was used to photograph each group of 50 rice noodles, measure the diameter uniformity (standard deviation) and curvature changes, and record the proportion of abnormal deformation.

[0109] 3. Surface integrity evaluation:

[0110] The surface roughness of the vermicelli was measured using a laser scanning confocal microscope (CLSM) to assess the number of surface microcracks and the average peak-to-valley height (Ra).

[0111] 4. Structural integrity test (breakage rate):

[0112] After vibrating the sample in a standard vibration device for 30 minutes, the number of broken vermicelli was counted and the breakage rate was calculated.

[0113] 5. Sensory evaluation:

[0114] A group of 10 people was organized to score the results, focusing on appearance uniformity, visual smoothness, and structural compactness (each item is worth 10 points). The experimental data are shown in Table 2.

[0115] Table 2: Test data on the forming quality and surface condition of vermicelli

[0116]

[0117] From Table 2, we can obtain:

[0118] Experiments show that pea protein powder can significantly improve the consistency and structural compactness of vermicelli under standard forming conditions. This is due to its high proportion of branched-chain amino acid structure, which allows for better hydrophobic entanglement and hydrogen bonding with starch chains, thereby strengthening the vermicelli skeleton. Its low swelling properties also help maintain a stable shape during processing and reduce structural disturbances caused by moisture migration.

[0119] In Comparative Example 3, replacing the protein with corn gluten meal resulted in a decrease in the consistency and smoothness of the vermicelli. Corn gluten has a low proportion of branched-chain amino acids and strong protein swelling properties, leading to uneven water adsorption and unstable protein distribution. This results in an inability to effectively support the gel framework, manifested as increased surface roughness, a doubling of the breakage rate, and vermicelli that is more prone to deformation.

[0120] In Comparative Example 4, even though pea protein was retained, the elimination of extrusion pressure control and the use of gravity extrusion resulted in uncontrollable slurry flow rate, making it prone to stringing, cross-sectional shrinkage, or air bubble retention during molding. This type of deformation further caused irregular appearance and structural defects, and even if the protein's effect was present, its advantages could not be demonstrated due to process interference.

[0121] Experiment 3:

[0122] Experimental objective:

[0123] This experiment aims to investigate the effects of adding traditional alum leavening agents and drying processes on the taste, structural integrity, and food safety of potato vermicelli.

[0124] Experimental steps:

[0125] 1. Sample preparation:

[0126] Prepare three sets of samples: Example 3, Comparative Example 5, and Comparative Example 6.

[0127] 2. Aluminum residue detection (alum risk):

[0128] The aluminum ion residue content of the sampled vermicelli was detected by ICP-MS (inductively coupled plasma mass spectrometry), and the unit was mg / kg.

[0129] 3. Drying uniformity test:

[0130] The moisture content of different parts after drying was measured using a water activity meter to assess whether the drying gradient and moisture migration were uniform.

[0131] 4. Observation of fracture and crack:

[0132] The crack rate was statistically analyzed using image analysis, and the fracture force (N) was tested using a three-point bending tester.

[0133] 5. Sensory rating for taste and safety:

[0134] Ten volunteers were invited to conduct a blind taste test, which included: astringency rating, chewing comfort, and overall acceptability (each item on a scale of 10). The experimental data are shown in Table 3.

[0135] Table 3: Data on the Drying Integrity and Aluminum Residue Measurement of Vermicelli

[0136]

[0137] From Table 3, we can obtain:

[0138] While the addition of alum (Comparative Example 5) slightly improved drying uniformity (low coefficient of variation), it significantly led to aluminum residue issues, with aluminum content exceeding food safety standards by nearly 100 times. Alum improves appearance by promoting moisture evaporation and localized bulking, but its interference with the protein-starch structure results in a loose gel system, leading to decreased mechanical properties and reduced breaking strength of the vermicelli. The low astringency score also confirms its negative impact on taste.

[0139] In Comparative Example 6, the magnetic field freezing treatment was removed and the drying temperature was increased to 55°C. Although this accelerated the drying process, it caused significant uneven drying and internal cracking, manifested as high moisture variation and fracture rate. Magnetic field freezing, which normally distributes moisture evenly and controls ice crystal formation, was absent, leading to damage to the internal microstructure. Combined with the rapid drying causing a hardened outer shell effect, the imbalance of the internal and external drying gradients resulted in the accumulation of microcracks.

[0140] In contrast, the combined magnetic field freezing and gentle drying process used in Example 3 effectively ensures structural integrity and food safety. The uniform microstructure formed under the action of a low-temperature magnetic field allows for more balanced moisture migration, resulting in a low crack rate after drying. Combined with an alum-free formula, it avoids the risk of metal residue, while also considering taste and consumer acceptance, demonstrating excellent mechanistic advantages and a balanced product performance.

[0141] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A type of alum-free potato starch modified based on magnetic field-assisted mung bean protein, characterized in that, The components include the following parts by weight: Potato starch: 60–70 parts; Acetate starch: 20–25 parts; Pea protein powder: 5–8 servings; Guar gum: 2–3 parts; Distilled water: 180–220 parts.

2. The alum-free potato starch modified based on magnetic field synergistic with mung bean protein according to claim 1, characterized in that, The pea protein powder is a purified protein powder with a protein mass fraction of not less than 80% and a branched-chain amino acid content of not less than 18%.

3. The alum-free potato starch modified based on magnetic field synergistic with mung bean protein according to claim 1, characterized in that, The degree of substitution of the acetate starch is 0.02–0.05, and it has cold water solubility and acid resistance.

4. A method for preparing alum-free potato starch modified by magnetic field synergy with mung bean protein, applicable to the alum-free potato starch modified by magnetic field synergy with mung bean protein as described in any one of claims 1-3, characterized in that, Includes the following steps: S1. Mix potato starch, acetate starch, pea protein powder and guar gum evenly, add distilled water and stir to form a uniform starch slurry; S2. The slurry is wet-extruded and molded; S3. Hot water cooking treatment for extruded vermicelli; S4. Cool the cooked vermicelli; S5. Perform magnetic freezing treatment on the cooled vermicelli; S6. After thawing, dry to obtain the target product.

5. The method for preparing alum-free potato starch based on magnetic field-assisted mung bean protein modification according to claim 4, characterized in that, The stirring speed during the slurry stirring process is 800–1200 rpm, the stirring time is 10–15 minutes, and the viscosity of the resulting slurry is 500–1200 mPa·s.

6. The method for preparing alum-free potato starch based on magnetic field-assisted mung bean protein modification according to claim 4, characterized in that, The nozzle diameter used in the extrusion process is 1.2–1.5 mm, and the slurry is extruded by pressure control, with an extrusion pressure of 0.15–0.30 MPa.

7. The method for preparing alum-free potato starch based on magnetic field-assisted mung bean protein modification according to claim 4, characterized in that, The curing process is carried out in hot water at 80–85°C for 2.5–4 minutes; the cooling process is carried out in cold water at 4–8°C for 10–20 minutes.

8. The method for preparing alum-free potato starch based on magnetic field-assisted mung bean protein modification according to claim 4, characterized in that, The temperature range of the magnetic field freezing process is -12 to -30°C, the applied magnetic field strength is 3–6 mT, and the processing time is 20–40 minutes.

9. The method for preparing alum-free potato starch based on magnetic field-assisted mung bean protein modification according to claim 8, characterized in that, The magnetic field is a low-frequency alternating magnetic field with a frequency of 0–100Hz, and the magnetic field lines are parallel to the direction of the vermicelli's extension.

10. The method for preparing alum-free potato starch based on magnetic field-assisted mung bean protein modification according to claim 4, characterized in that, The drying is carried out in a hot air drying oven at 35–45°C for 6–10 hours, and the moisture content of the final product is controlled at 16–18%.

Images