Processing method for gradient peeling of saline-alkaline tolerant wheat and application of processing method

Abstract

The invention relates to the technical field of deep processing of agricultural products, and discloses a processing method for gradient peeling of saline-alkali tolerant wheat and application thereof, and the processing method comprises the following steps: raw material screening: selecting Shannong 48 wheat planted in saline-alkali soil with the soil salt content of 0.3-0.5%; cleaning and wetting the wheat: removing impurities through a specific gravity sieve and a magnetic separator, and adding distilled water according to 2.8-3.2% of the mass of the wheat; gradient peeling, wherein three-stage emery roll peeling machines are connected in series to conduct peeling for 3-5 times; and fine grinding: crushing and grinding the peeled wheat by using a hammer type cyclone mill to obtain the wheat flour with the gradient peeling rate. Through step-by-step parameter adjustment of a three-stage emery roll huller in a gradient hulling technology and in combination with negative pressure separation and surface integrity monitoring, the external structure of wheat is accurately peeled, and endosperm damage is reduced. And through emery roll roughness and graded pressure control, protein and antioxidant active substances in endosperm are effectively reserved, starch particle integrity is maintained, and a foundation is laid for flour functionality.

Description

Technical Field

[0001] The present invention relates to the technical field of deep processing of agricultural products, in particular to a processing method for gradient peeling of salt-alkali tolerant wheat and application thereof. Background Art

[0002] Under salt stress, salt-tolerant wheat (such as Shannong 48) activates secondary metabolic pathways, allowing its grains to accumulate high concentrations of polyphenols (30-50% higher than those of conventional wheat) and minerals such as potassium, calcium, and magnesium. These functional components are primarily concentrated in the bran and aleurone layer. However, while refined flour produced by modern milling processes through multi-stage milling and screening offers the advantages of low ash content and high whiteness, excessive removal of the ectoderm results in a 60-75% loss of total phenolics and a 55-70% reduction in antioxidant activity. This nutrient loss is particularly significant in salt-tolerant wheat.

[0003] In addition, salt-alkali stress causes the grains to exhibit heterogeneous hardness distribution and high mineral content, which significantly affects the gluten network formation efficiency and starch gelatinization characteristics. Traditional uniform peeling processes are difficult to adapt to such characteristics, resulting in functional ingredient retention rates fluctuating by more than 30%, and the processed products generally have poor rheological properties, a low proportion of slowly digestible starch, and texture deterioration. At the same time, existing technologies mainly rely on single flour extraction rate control to achieve nutritional enhancement, but ignore the nonlinear relationship between peeling rate and nutrient retention, and lack processing parameter design tailored to the characteristics of salt-alkali-tolerant wheat. Summary of the Invention

[0004] In response to the shortcomings of the existing technology, the present invention provides a processing method for gradient peeling of salt-alkali tolerant wheat and its application, which solves the problems of low wheat nutrient retention rate, insufficient gluten network strength, deterioration of final product texture and poor batch stability in the previous processing of salt-alkali tolerant wheat.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: A method for gradient peeling of salt-alkali tolerant wheat, comprising the following steps:

[0006] S1. Raw material screening: Select Shannong 48 wheat grown in saline-alkali land with a soil salinity of 0.3% to 0.5%;

[0007] S2. Cleaning and tempering the wheat: Remove impurities through a specific gravity screen and magnetic separator, add 2.8% to 3.2% distilled water by weight of the wheat, and temper the wheat at an ambient temperature of 20°C to 25°C and a relative humidity of 70% to 80% for 6 to 24 hours to a moisture content of 13% to 15%;

[0008] S3, gradient peeling: use three-stage sand roller peeling machine in series to perform 3 to 5 peelings; control the total peeling rate from 0% to 10.43%, the peeling environment temperature from 20℃ to 30℃, and the relative humidity from 50% to 70%;

[0009] S4. Fine grinding: The peeled wheat is crushed and ground using a hammer cyclone mill to obtain wheat flour with a gradient peeling rate.

[0010] By adopting the above technical solution: through the step-by-step parameter adjustment of the three-stage emery roller peeling machine in the gradient peeling technology (emery roller gap 0.3-1.2mm, speed 1100-1900rpm), combined with negative pressure separation and surface integrity monitoring (residual epidermis ≤5%), the external structure of wheat is accurately peeled off and endosperm damage is reduced. The roughness of the emery roller (Ra value 0.8-1.2μm) and the graded pressure (-50Pa to -100Pa) are controlled to effectively retain protein (16.2-18.5%) and antioxidant active substances (DPPH scavenging rate 35%-68%) in the endosperm, while maintaining the integrity of starch granules (damage rate ≤8%), laying the foundation for flour functionality. At the same time, based on the staged peeling rate regulation (peeling rate of 1.5%-5% in three stages), a quantitative relationship model between peeling rate and flour parameters is established. By spraying water (moisture content 14.0% ± 0.5%) and intermittent stirring (15 minutes / 45 minutes pause), the moisture gradient between the wheat cortex and endosperm is balanced, the gluten network extensibility is improved (stable time 1.8-2.3 minutes), and the dynamic rheological properties of the dough (G' / G" = 0.85-1.15) are enhanced, ensuring the flour's resistance to mechanical shear and extensibility in subsequent processing.

[0011] Preferably, the parameters of each level of the three-stage emery roller peeling machine in S3 are:

[0012] First stage: sand roller gap 0.8 to 1.2 mm, speed 1100 to 1300 rpm;

[0013] Second level: sand roller gap 0.5 to 0.8 mm, speed 1400 to 1600 rpm;

[0014] Level 3: Sand roller gap 0.3 to 0.5 mm, speed 1700 to 1900 rpm;

[0015] After each stage of peeling, the bran is separated by a negative pressure airflow of 4 to 6 m / s, and the surface integrity of the grains is monitored by visual inspection or mechanical inspection to ensure that the residual amount of wheat skin on each grain is ≤5%.

[0016] Preferably, the S3 gradient peeling controls the peeling rate in stages.

[0017] The peeling rate in the first stage is 1.5% to 3%.

[0018] The second stage peeling rate is 2.5% to 4.5%,

[0019] The peeling rate in the third stage is 3% to 5%;

[0020] After each stage of peeling, a spray water replenishing device was used to adjust the moisture content to 14.0% ± 0.5%.

[0021] Preferably, the sand mesh number of the three-stage sand roller peeling machine in S3 is 60 to 80 mesh, the surface roughness Ra value of the sand roller is 0.8 μm to 1.2 μm, and the pressure inside the machine is maintained at -50 Pa to -100 Pa by a negative pressure fan.

[0022] Preferably, the distilled water in S2 is sprayed by an ultrasonic atomizer with an atomization particle size of 50 μm to 100 μm, with a spray rate of 2 L / min to 5 L / min, and a spiral stirrer is used to intermittently operate at a speed of 10 rpm to 15 rpm, with an operating cycle of 15 minutes on / 45 minutes off.

[0023] Preferably, in the S4 hammer cyclone mill crushing, the hammer linear speed is 28 to 32 m / s, the rotation speed is 1500 to 2500 rpm, the grinding time is 3 to 5 minutes, the material is classified through a 200-300 mesh vibrating screen, and the grinding temperature is controlled to be ≤40°C.

[0024] Preferably, a functional flour is prepared by the above-mentioned salt-alkali tolerant wheat gradient peeling processing method, comprising the following indicators:

[0025] Protein content 16.2%-18.5%;

[0026] DPPH free radical scavenging rate 35% to 68%;

[0027] Fat content 1.06% to 2.13%;

[0028] Dynamic rheological properties: The ratio of storage modulus G' to loss modulus G" at a frequency of 0.1 Hz is 0.85 to 1.15.

[0029] Preferably, the total starch content is 55.58% to 64.43%; the gelatinization characteristics are: peak viscosity 744 to 1596 cP, and disintegration value 142 to 188 cP.

[0030] Preferably, a high-activity steamed bun is made by the high-activity steamed bun preparation method, with a specific volume of 3.1 to 3.3 mL / g; a hardness of 1926 to 4634 g; and an elasticity of 0.40 to 0.49.

[0031] Preferably, the diameter of the surface pores is 0.5mm to 2.0mm, and the pore distribution uniformity is ≥90%; the thickness of the steamed bun skin is 0.2mm to 0.5mm, and the hardness ratio of the core to the skin is 1.5:1 to 2.0:1.

[0032] The present invention provides a method for gradient peeling of salt-alkali-tolerant wheat and its application, which has the following beneficial effects:

[0033] 1. This invention utilizes a gradient peeling technique using three emery rollers with step-by-step parameter adjustment (emery roller gap 0.3-1.2mm, rotation speed 1100-1900rpm), combined with negative pressure separation and surface integrity monitoring (residual epidermis ≤ 5%), to precisely exfoliate the wheat's outer structure and minimize endosperm damage. Control of emery roller roughness (Ra value 0.8-1.2μm) and graded pressure (-50Pa to -100Pa) effectively preserves endosperm protein (16.2-18.5%) and antioxidant activity (DPPH scavenging rate 35%-68%) while maintaining starch granule integrity (damage rate ≤ 8%), laying the foundation for flour functionality.

[0034] 2. The present invention establishes a quantitative relationship model between the peeling rate and the flour parameters based on staged peeling rate regulation (peeling rate of 1.5%-5% in three stages); through spraying water (water content 14.0%±0.5%) and intermittent stirring (15 minutes / stop 45 minutes), the moisture gradient between the wheat cortex and endosperm is balanced, the gluten network extensibility is improved (stable time 1.8-2.3 minutes), and the dynamic rheological properties of the dough are improved (G' / G"=0.85-1.15), thereby ensuring the mechanical shear resistance and extensibility of the flour in subsequent processing.

[0035] 3. The present invention adopts a hammer cyclone mill for crushing (hammer linear speed 28-32 m / s) in combination with a vibrating screen for classification (200-300 mesh), and limits the grinding temperature (≤40°C) and time (3-5 minutes) to reduce the influence of mechanical thermal effects on starch gelatinization (ΔH ≥ 8.5 J / g) and protein denaturation, thereby achieving flour median particle size control (D50 = 18-25 μm). In combination with particle surface damage inhibition (crystallization ≥ 75%), the flour gelatinization properties and disintegration stability are significantly improved.

[0036] 4. The present invention optimizes the pore formation (pore diameter 0.5-2.0 mm) and gluten-starch network cross-linking degree during steaming of steamed buns through the high-protein matrix (16.2-18.5%) and uniform particle size distribution (D50 = 18-25 μm) of gradient peeled flour; the skin thickness (0.2-0.5 mm) and core skin hardness ratio (1.5:1-2.0:1) are achieved through the regulation of steam thermal gradient (surface cooling rate 8-10 ° C / mm) and moisture migration, so that the specific volume (3.1-3.3 mL / g) and elasticity (0.40-0.49) of steamed buns are adapted to the needs of different eating scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The present invention is a flow chart of a method for gradient peeling of salt-alkali tolerant wheat. DETAILED DESCRIPTION

[0038] The following will clearly and completely describe the technical solution of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0039] Please see the attached Figure 1 The embodiment of the present invention provides a method for gradient peeling of salt-alkali tolerant wheat, comprising the following steps:

[0040] S1. Raw material screening: Select Shannong 48 wheat grown in saline-alkali land with a soil salinity of 0.3% to 0.5%;

[0041] S2. Cleaning and tempering the wheat: Remove impurities through a specific gravity screen and magnetic separator, add 2.8% to 3.2% distilled water by weight of the wheat, and temper the wheat at an ambient temperature of 20°C to 25°C and a relative humidity of 70% to 80% for 6 to 24 hours to a moisture content of 13% to 15%;

[0042] S3, gradient peeling: use three-stage sand roller peeling machine in series to perform 3 to 5 peelings; control the total peeling rate from 0% to 10.43%, the peeling environment temperature from 20℃ to 30℃, and the relative humidity from 50% to 70%;

[0043] S4. Fine grinding: The peeled wheat is crushed and ground using a hammer cyclone mill to obtain wheat flour with a gradient peeling rate.

[0044] Specifically, by selecting Shannong 48 wheat grown in saline-alkali land with a soil salt content of 0.3% to 0.5%, the raw materials with salt-alkali resistance are screened out, thereby ensuring the quality of raw materials for subsequent processing and improving the retention rate of functional components in flour; by using a specific gravity screen and a magnetic separator to remove impurities, and adding distilled water at 2.8% to 3.2% of the wheat mass, the wheat is tempered for 6 to 24 hours at an ambient temperature of 20°C to 25°C and a relative humidity of 70% to 80%, so that the moisture content reaches 13% to 15%, thereby removing impurities and adjusting the moisture content of wheat, thereby improving the processing performance of wheat and providing preparation for subsequent The invention provides the effect of providing suitable conditions for continuous peeling and grinding; by adopting a three-stage sand roller peeling machine to carry out peeling for 3 to 5 times in series, controlling the total peeling rate from 0% to 10.43%, and the peeling environment temperature from 20℃ to 30℃ and the relative humidity from 50% to 70%, it plays the role of selectively removing the wheat epidermis in stages, thereby retaining the functional components inside the wheat and avoiding the loss of nutrients due to excessive peeling; by crushing and grinding the peeled wheat with a hammer cyclone mill, a gradient peeling rate wheat flour is obtained, which plays the role of evenly crushing the wheat into flour particles, thereby improving the quality and processing performance of flour and meeting the needs of different terminal products.

[0045] Please see the attached Figure 1 The parameters of each level of the three-stage sand roller peeling machine in S3 are:

[0046] First stage: sand roller gap 0.8 to 1.2 mm, speed 1100 to 1300 rpm;

[0047] Second level: sand roller gap 0.5 to 0.8 mm, speed 1400 to 1600 rpm;

[0048] Level 3: Sand roller gap 0.3 to 0.5 mm, speed 1700 to 1900 rpm;

[0049] After each stage of peeling, the bran is separated by a negative pressure airflow of 4 to 6 m / s, and the surface integrity of the grains is monitored by visual inspection or mechanical inspection to ensure that the residual amount of wheat skin on each grain is ≤5%.

[0050] Specifically, the first stage of coarse peeling: the wider gap (0.8-1.2mm) and low speed (1100-1300rpm) sand roller design play the role of preliminary peeling of the hard epidermis of wheat, avoiding damage to the endosperm due to excessive friction, thereby reducing endosperm breakage and retaining the integrity of the bran; the second stage of mid-section fine peeling: narrowing the gap of the sand roller (0.5-0.8mm) and increasing the speed (1400-1600rpm) to directionally remove the endosperm and part of the germ, thereby achieving the effect of accurately retaining functional ingredients (such as polyphenols and dietary fiber); the third stage of fine peeling: further narrowing the gap (0.3-0.5mm) and high speed (1700-1900rpm) sand roller, play the role of thoroughly removing residual epidermis and microbial contamination, while controlling friction heat through dynamic speed, thereby The effect of improving flour purity and preventing heat damage is achieved; through the air flow separation technology with a negative pressure wind speed of 4 to 6m / s, a directional airflow is formed after each stage of peeling, which plays a role in efficiently separating the shed bran and wheat grains, reducing the probability of bran debris sticking back, thereby reducing the risk of subsequent grinding contamination and improving the peeling efficiency by 20%-30%; among them, visual inspection: using a high-resolution camera (pixel ≥ 5 million) to scan the surface of the grain, and analyzing the residual area of ​​the epidermis through image algorithm to dynamically feedback the peeling rate, thereby ensuring that the epidermis residue is ≤5% and the endosperm damage rate is ≤0.5%; mechanical inspection: using a contact probe to measure the surface roughness of the grain (Ra value ≤1.5μm), which plays a role in quantifying the degree of epidermal peeling, thereby achieving a peeling process stability error of ±0.2%.

[0051] Please see the attached Figure 1 , S3 gradient peeling controls the peeling rate in stages,

[0052] The peeling rate in the first stage is 1.5% to 3%.

[0053] The second stage peeling rate is 2.5% to 4.5%,

[0054] The peeling rate in the third stage is 3% to 5%;

[0055] After each stage of peeling, a spray water replenishing device was used to adjust the moisture content to 14.0% ± 0.5%.

[0056] Specifically, the first stage of low-intensity peeling (1.5%-3%) is designed with a relatively low peeling rate to preferentially peel off the outer hard bran, avoiding thermal damage to the endosperm caused by rapid peeling, thereby achieving the effect of protecting the activity retention rate of salt stress-induced proteins (such as LEA proteins) in the endosperm of salt-alkali-tolerant wheat by ≥90%; the second stage of adaptive peeling (2.5%-4.5%) adjusts the parameters according to the surface state of the grains after the first stage of peeling, and plays a role in the targeted removal of pollutants in the endosperm, thereby achieving a 15%-25% increase in the recovery rate of functional components (such as ferulic acid and arabinoxylan). The third stage of precise peeling (3%-5%) matches the optimal peeling amount based on the accumulated data of the first two stages, which plays a role in targeted removal of the remaining epidermis, thereby achieving an endosperm exposure area of ​​≥95% and an epidermal mechanical damage rate of ≤0.3%; Atomized water spray module: sprays droplets with a particle size of 10-50μm at a pressure of 0.5-1.0MPa and a spray rate of 2-5mL / (kg·s), which plays a role in uniformly penetrating the wheat grain cortex, thereby dynamically restoring the bound water lost during the peeling process and maintaining the interface bonding strength between the endosperm and the cortex at 0.8-1.2N / mm 2 effect; Moisture closed-loop control: Real-time feedback of moisture content is provided by a near-infrared sensor (detection accuracy ±0.3%), which accurately compensates for the evaporation of moisture during peeling, thereby ensuring that the starch granule breakage rate is ≤8% and the gluten network formation degree is ≥85% during the subsequent grinding process.

[0057] Please see the attached Figure 1 The sand mesh number of the three-stage sand roller peeling machine in S3 is 60 to 80 mesh, the surface roughness Ra value of the sand roller is 0.8μm to 1.2μm, and the pressure inside the machine is maintained at -50Pa to -100Pa by a negative pressure fan.

[0058] Specifically, the three-stage sand roller peeling machine has a sand mesh size of 60 to 80 meshes, which balances the peeling efficiency and grain protection, thereby achieving the effect of removing the wheat husk while reducing the mechanical damage to the endosperm; the sand roller surface roughness Ra value of 0.8μm to 1.2μm optimizes the friction and contact area, thereby improving the peeling uniformity and reducing the grain breakage rate; the negative pressure fan maintains the pressure in the machine at -50Pa to -100Pa, which plays a role in directional airflow to separate bran and grains, thereby improving the peeling efficiency, reducing the back-sticking phenomenon and improving the working environment.

[0059] Please see the attached Figure 1 The distilled water in S2 is sprayed through an ultrasonic atomizer with a particle size of 50μm to 100μm, with a spray rate of 2L / min to 5L / min, and a spiral stirrer is used to run intermittently at a speed of 10rpm to 15rpm, with an operating cycle of 15 minutes on / 45 minutes off.

[0060] Specifically, 50-100 μm droplets are formed through high-frequency ultrasonic oscillation (20kHz-100kHz), which evenly adsorb into the pores of the wheat epidermis, thereby simulating the penetration of natural dew, with an epidermal wetting coverage rate of ≥95%. The spray rate is adjusted from 2L / min to 5L / min to adjust the wheat moistening process, dynamically matching the wheat water absorption capacity with the epidermal water absorption rate (0.3-0.8g / (g·h)), thereby preventing surface water accumulation and promoting uniform water penetration into the kernel core. The 0-15 rpm speed design combined with the spiral blade inclination angle of 30°-45° gently pushes the wheat kernel layer, thereby eliminating moisture gradients (internal / surface moisture content deviation ≤ 0.5%) and avoiding mechanical friction heating (temperature fluctuation ≤ 2°C). The intermittent mode of 15 minutes of operation / 45 minutes of rest balances moisture diffusion (Fick's law penetration rate) and static infiltration, thereby achieving an overall moisture content range of ≤ 0.8% and a stable endosperm-cortex interface bonding force of 1.0-1.5N / mm. 2 effect.

[0061] Please see the attached Figure 1 In the S4 hammer cyclone mill, the hammer linear speed is 28 to 32 m / s, the rotation speed is 1500 to 2500 rpm, the grinding time is 3 to 5 minutes, and the material is classified through a 200-300 mesh vibrating screen, and the grinding temperature is controlled to be ≤40°C.

[0062] Specifically, the linear speed of 28-32m / s (corresponding to the kinetic energy of the hammer tip of 1.5-2.0kJ / kg) is combined with the rotation speed of 1500-2500rpm to play the role of high-frequency shearing and centrifugal impact in parallel, thereby achieving the effect of breaking the wheat endosperm particles in the form of "layered peeling" (starch granule retention rate ≥90%, protein matrix integrity ≥85%); by matching the hammer impact angle (30°-45°) with the linear speed, the crushing force is directionally controlled, thereby reducing the breakage of starch molecular chains caused by excessive crushing (grape The sugar polymerization degree DP≥25 is increased by 20%); after the effective crushing threshold time (about 2 minutes), the time is extended to 5 minutes to play a role in finely controlling the particle size, thereby achieving the effect of achieving a narrow distribution characteristic with a median particle size D50 of 18-25μm and a span (Span value) ≤1.2; short-time high-frequency crushing combined with forced air cooling makes the unit mass power consumption ≤1.5kWh / t, thereby inhibiting starch gelatinization (gelatinization degree ≤12%) and maintaining gluten extractability (SDS-PAGE band intensity error ≤5%); the trapezoidal screen with an opening rate of 45%-55% and a double eccentric shaft vibration drive is used to selectively separate coarse particles (>45μm) that do not meet the standards, thereby achieving the effect of target particle size (15-38μm) accounting for ≥90% and ash content ≤0.55% in the finished powder; through screening accuracy control, the enrichment of nano-scale active particles related to salt and alkali resistance (such as sodium / potassium transporter protein complex, with a size of about 80-150nm) in fine powder is increased by 30-45%; by grinding temperature ≤4 The 0℃ control system makes the material residence time ≤35 seconds, which blocks the accumulation of frictional heat (heat loss rate ≥150kJ / (m2·s)), thereby maintaining the stability of the disulfide bond conformation of gluten protein (free thiol content ≤4μmol / g). The retention rate of temperature-sensitive substances (such as γ-tocopherol) in low-temperature grinding is ≥92%, which is significantly improved compared with conventional grinding (retention rate 70-80%), thereby achieving the effect of extending the shelf life of flour by 40%-60% (peroxide value IP ≤3meq / kg).

[0063] Please see the attached Figure 1 A functional flour prepared by the above-mentioned gradient peeling method of salt-alkali tolerant wheat includes the following indicators:

[0064] Protein content 16.2%-18.5%;

[0065] DPPH free radical scavenging rate 35% to 68%;

[0066] Fat content 1.06% to 2.13%;

[0067] Dynamic rheological properties: The ratio of storage modulus G' to loss modulus G" at a frequency of 0.1 Hz is 0.85 to 1.15.

[0068] Specifically, the protein content is 16.2% to 18.5%, ensuring the formation of the gluten network and dough elasticity; the DPPH free radical scavenging rate is 35% to 68%, reflecting the antioxidant capacity of the flour; the fat content is 1.06% to 2.13%, providing the aroma and taste of the flour; and at a frequency of 0.1 Hz, the ratio of the storage modulus G' to the loss modulus G" is 0.85 to 1.15, ensuring the stability and processing performance of the dough.

[0069] Please see the attached Figure 1 , total starch content 55.58% to 64.43%; gelatinization characteristics: peak viscosity 744 to 1596 cP, disintegration value 142 to 188 cP.

[0070] Specifically, the high total starch content (55.58%-64.43%) works synergistically with the functional ingredients (polyphenols and dietary fiber) retained by gradient peeling, which not only ensures the dough formability (tensile resistance ≥350BU) but also gives the final product antioxidant activity (DPPH scavenging rate 35%-68%). The gelatinization properties (peak viscosity and disintegration value) are matched with dynamic rheology (G' / G"=0.85-1.15), making the dough both elastic and extensible (extensibility ≥60mm), suitable for multiple process requirements such as baking and steaming.

[0071] Please see the attached Figure 1 A high-activity steamed bun is made by the above-mentioned high-activity steamed bun preparation method, with a specific volume of 3.1 to 3.3 mL / g; a hardness of 1926 to 4634 g; and an elasticity of 0.40 to 0.49.

[0072] Specifically, the specific volume reflects the softness of the steamed bun, with higher values ​​indicating fluffier buns. High specific volume indicates a fine structure, uniform pores, and a softer texture. Hardness measures the force required to chew the bun; a moderate hardness ensures the bun is neither too hard nor too soft, resulting in a pleasant mouthfeel. Elasticity refers to the bun's ability to return to its original shape after being compressed; higher elasticity means the bun is chewier and has a better texture.

[0073] Please see the attached Figure 1 The diameter of the surface pores is 0.5mm to 2.0mm, and the uniformity of pore distribution is ≥90%; the thickness of the steamed bun skin is 0.2mm to 0.5mm, and the hardness ratio of the core to the skin is 1.5:1 to 2.0:1.

[0074] Specifically, through gradient fermentation temperature control (30℃→38℃) and step-by-step adjustment of relative humidity (80%→85%), the yeast gas production rate (5-8mL / min·g) and gluten extensibility are balanced, thereby achieving the effect of precise control of surface pore diameter (0.5-2.0mm) and distribution uniformity ≥90%, so that a continuous honeycomb structure is formed inside the steamed bun, which significantly improves the fluffiness (specific volume 3.1-3.3mL / g) and chewing resilience (elasticity 0.40-0.49); through steam thermal field gradient design (surface cooling rate 8-10℃ / mm) and epidermal cross-linking strengthening (glutenin disulfide bond density ≥4μmol / g), the starch gelatinization gradient distribution and water migration inhibition are driven, thereby achieving the effect of epidermal thickness 0.2-0.5mm and core / skin hardness ratio 1.5:1-2.0:1, giving the steamed bun skin flexibility and crack resistance (fracture toughness ≥25J / m 2 ) and the soft and moist texture of the core (adhesion ≥ 0.8mJ), achieving simultaneous improvement in taste layering and shelf life stability (72h hardening rate ≤ 15%).

[0075] Example 1

[0076] 1. Processing method

[0077] 1. Raw material processing:

[0078] Shannong 48 wheat was selected and grown on saline-alkali land with soil pH 8.2-8.5 and salt content 0.35%;

[0079] After cleaning, adjust the moisture content to 14.0±0.5% by spraying.

[0080] 2. Gradient peeling:

[0081] An experimental iron roller peeling machine (model LN-80) was used;

[0082] Peeling rate control:

[0083] 0% (control group): no peeling;

[0084] 3.64%: single-stage peeling (gap 1.0 mm, speed 1200 rpm);

[0085] 7.56%: two-level peeling (first-level gap 1.2mm → second-level gap 0.8mm);

[0086] 10.43%: three-stage peeling (1.2mm / 1100rpm→0.8mm / 1600rpm→0.5mm / 1900rpm);

[0087] After each stage of peeling, the bran is separated by negative pressure wind speed of 5m / s.

[0088] 3. Grinding:

[0089] Hammer cyclone mill parameters: linear speed 30 m / s, grinding time 4 min, 200 mesh sieve classification.

[0090] 2. Characteristics of functional flour

[0091]

[0092] 3. Technical Effect: The aleurone layer was best retained when the peeling rate was 7.56%, and the DPPH clearance rate was increased by 13.6% compared with 0% peeling; the peak viscosity was 1380 cP (an increase of 85.5% compared with the control group).

[0093] Example 2

[0094] 1. Steamed Bun Preparation Process

[0095] 1. Recipe:

[0096] 100g flour with 7.56% peeling rate (13.41% protein, peak viscosity 1380cP);

[0097] 2g yeast, 48mL water (water addition rate 48%).

[0098] 2. Process parameters:

[0099] Mixing: stirring at 50 rpm for 7 minutes;

[0100] Fermentation: 40 min (30°C / 70% RH);

[0101] Proofing: 20min;

[0102] Steaming: 0.15MPa steam pressure / 100℃ / 20min.

[0103] 2. Characteristics of steamed buns

[0104] index Measured value Test standards specific volume 3.21mL / g GB / T20981-2021 hardness 3280g GB / T38133-2019 elasticity 0.44 GB / T38133-2019 Pore ​​diameter 1.2±0.3mm GB / T35869-2018 Epidermal thickness 0.35mm GB / T35869-2018 Core / skin hardness ratio 1.8:1 GB / T38133-2019

[0105] 3. Technical effect: Flour with medium peeling rate makes the pore uniformity of steamed buns reach 92%, and the hardness ratio of the core to the skin is 1.8:1, which optimizes the taste.

[0106] Example 3

[0107] 1. Collaborative implementation of all parameters

[0108] 1. Processing method:

[0109] Wheat moistening: atomization particle size 75μm, spray rate 4L / min, stirring 12.5rpm.

[0110] Peeling:

[0111] Level 3 parameters: 1.0mm / 1200rpm→0.65mm / 1500rpm→0.4mm / 1800rpm;

[0112] Staged peeling rate: 2.25% + 3.5% + 4% = 9.75%;

[0113] Negative pressure inside the machine -75Pa;

[0114] Grinding: linear speed 30 m / s, 250 mesh sieve, temperature 38 °C.

[0115] 2. Flour indicators:

[0116] Protein: 17.35%;

[0117] DPPH clearance rate: 51.5%;

[0118] Peak viscosity: 1170 cP.

[0119] 3. Steamed bun process:

[0120] Mixing dough: add 50% water, stir at 60rpm / 8min

[0121] Fermentation: 35℃ / 75%RH / 55min

[0122] Steaming: 0.15MPa / 100℃ / 20min

[0123] 2. Product Verification

[0124] characteristic Measured value Test standards specific volume 3.30mL / g GB / T20981-2021 hardness 2105g GB / T38133-2019 elasticity 0.47 GB / T38133-2019 Porosity uniformity 95％ GB / T35869-2018

[0125] 3. Technical effect: The gradient peeling synergistic parameters increase the elasticity of steamed bread by 6.8% (compared with the bottoming process), and the peeling is effective in retaining the aleurone layer.

[0126] Comparative Example 1

[0127] 1. Processing method

[0128] 1. Raw materials: same as the saline-alkali land Shannong 48 wheat in Example 1.

[0129] 2. Moistening wheat: Directly soak with 30% water (not atomized), and moisten the wheat for 24 hours (without stirring).

[0130] 3. Peeling:

[0131] Single-stage peeling machine (gap 1.5 mm, speed 1800 rpm);

[0132] The peeling rate is 15.2%.

[0133] 4. Grinding: roller mill (temperature 60℃).

[0134] 2. Results Comparison

[0135]

[0136] 3. Conclusion: The traditional high peeling rate leads to complete peeling of the aleurone layer and significant loss of active ingredients (DPPH scavenging rate decreased by 89.2%).

[0137] Comparative Example 2

[0138] 1. Processing method

[0139] 1. Raw materials: ordinary farmland (soil salinity 0.1%) planted with Jimai 22;

[0140] 2. Process: Same as Example 2;

[0141] 3. Flour: same as in Example 2.

[0142] 2. Results Comparison

[0143]

[0144]

[0145] 3. Conclusion: Under the same processing technology, the wheat grown in non-saline-alkali land lacks adversity induction, resulting in insufficient synthesis of functional components (such as antioxidants), which leads to a significant decline in the quality of flour and steamed bread.

[0146] Comparative Example 3

[0147] 1. Processing method

[0148] 1. Peeling: The three-stage peeling machine operates with the same parameters (gap 1.0mm / speed 1500rpm).

[0149] 2. Default control:

[0150] No stage peeling rate regulation;

[0151] No negative pressure monitoring;

[0152] Grinding temperature 50℃;

[0153] Peeling rate: 8.9% measured.

[0154] 2. Results Comparison

[0155]

[0156] 3. Conclusion: The non-gradient parameter control leads to uneven peeling (excessive residual amount of skin) and deterioration of flour rheological properties.

[0157] 1. Raw materials and flour composition testing

[0158]

[0159] 2. Functional characteristics testing

[0160]

[0161]

[0162] 3. Steamed Bun Quality Inspection

[0163]

[0164] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for gradient peeling of salt-alkali tolerant wheat, characterized in that: The following steps are involved: S1. Raw material screening: Select Shannong 48 wheat grown in saline-alkali land with a soil salinity of 0.3% to 0.5%; S2. Cleaning and tempering the wheat: Remove impurities through a specific gravity screen and magnetic separator, add 2.8% to 3.2% distilled water by weight of the wheat, and temper the wheat at an ambient temperature of 20°C to 25°C and a relative humidity of 70% to 80% for 6 to 24 hours to a moisture content of 13% to 15%; S3, gradient peeling: use three-stage sand roller peeling machine in series to perform 3 to 5 peelings; control the total peeling rate from 0% to 10.43%, the peeling environment temperature from 20℃ to 30℃, and the relative humidity from 50% to 70%; S4. Fine grinding: The peeled wheat is crushed and ground using a hammer cyclone mill to obtain wheat flour with a gradient peeling rate.

2. The method for gradient peeling of salt-alkali-tolerant wheat according to claim 1, wherein: The parameters of each level of the three-stage emery roller peeling machine in S3 are: First stage: sand roller gap 0.8 to 1.2 mm, speed 1100 to 1300 rpm; Second level: sand roller gap 0.5 to 0.8 mm, speed 1400 to 1600 rpm; Level 3: Sand roller gap 0.3 to 0.5 mm, speed 1700 to 1900 rpm; After each stage of dehulling, the bran is separated by a negative pressure airflow of 4 to 6 m / s, and the surface integrity of the grains is monitored by visual inspection or mechanical inspection to ensure that the residual amount of wheat skin on each grain is ≤5%.

3. The method for processing salt-alkali tolerant wheat gradient peeling according to claim 1, wherein: The S3 gradient peeling controls the peeling rate in stages. The peeling rate in the first stage is 1.5% to 3%. The second stage peeling rate is 2.5% to 4.5%, The peeling rate in the third stage is 3% to 5%; After each stage of peeling, a spray water replenishing device was used to adjust the moisture content to 14.0% ± 0.5%.

4. The method for processing salt-alkali tolerant wheat gradient peeling according to claim 1, wherein: The sand mesh number of the three-stage sand roller peeling machine in S3 is 60 to 80 mesh, the surface roughness Ra value of the sand roller is 0.8 μm to 1.2 μm, and the pressure inside the machine is maintained at -50 Pa to -100 Pa by a negative pressure fan.

5. The method for processing salt-alkali tolerant wheat gradient peeling according to claim 1, wherein: The distilled water in S2 is sprayed by an ultrasonic atomizer with an atomization particle size of 50 μm to 100 μm, with a spray rate of 2 L / min to 5 L / min, and a spiral stirrer is used to intermittently operate at a speed of 10 rpm to 15 rpm, with an operation cycle of 15 minutes on / 45 minutes off.

6. The method for gradient peeling of salt-alkali tolerant wheat according to claim 1, wherein: In the S4 hammer cyclone mill, the hammer linear speed is 28 to 32 m / s, the rotation speed is 1500 to 2500 rpm, the grinding time is 3 to 5 minutes, the product is classified through a 200-300 mesh vibrating screen, and the grinding temperature is controlled to be ≤40°C.

7. A functional flour, characterized in that: Prepared by the salt-alkali tolerant wheat gradient peeling processing method according to any one of claims 1 to 6, comprising the following indicators: Protein content 16.2%-18.5%; DPPH free radical scavenging rate 35% to 68%; Fat content 1.06% to 2.13%; Dynamic rheological properties: The ratio of storage modulus G' to loss modulus G" at a frequency of 0.1 Hz is 0.85 to 1.

15.

8. The functional flour according to claim 7, characterized in that: Total starch content: 55.58% to 64.43%; gelatinization properties: peak viscosity: 744 to 1596 cP, disintegration value: 142 to 188 cP.

9. A high-activity steamed bun, characterized in that: The steamed bread is prepared by the high-activity steamed bread preparation method according to claim 7 or 8, with a specific volume of 3.1 to 3.3 mL / g; a hardness of 1926 to 4634 g; and an elasticity of 0.40 to 0.

49.

10. The high-activity steamed bread according to claim 9, characterized in that: The diameter of the surface pores is 0.5mm to 2.0mm, and the pore distribution uniformity is ≥90%; the thickness of the steamed bun skin is 0.2mm to 0.5mm, and the hardness ratio of the core to the skin is 1.5:1 to 2.0:1.

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