A process for the extraction of pea by wet fermentation and air drying

Abstract

The application discloses a kind of pea wet fermentation extraction and airflow drying process, it is related to plant protein deep processing and food powder preparation technical field, including after solid-liquid separation in horizontal screw centrifuge, in protein wet phase conditioning stage, clear fermentation liquor is added to protein wet phase, and paddle stirring mode with paddle end linear velocity not more than 1.9m / s is used, protein wet phase is conditioned, so that clear fermentation liquor is entered drying stage with protein wet phase, and the conditioning protein wet phase is obtained;Through the retention of ungelatinized starch particles, paddle stirring conditioning with paddle end linear velocity not more than 1.9m / s, screw conveying and the cooperation of needle type before drying scattering, it can reduce the formation of dense wet group of protein wet phase, so that the agglomerated particles obtained by airflow drying are more easily dissociated during cold water rehydration.

Description

Technical Field

[0001] This invention relates to the field of plant protein deep processing and food powder preparation technology, and in particular to a wet fermentation extraction and airflow drying process for peas. Background Technology

[0002] With the development of plant protein foods and plant-based beverages, pea protein has become an important raw material in plant protein powder and compound beverage bases due to its stable source, relatively low allergenicity, and good nutritional composition. Currently, most pea protein preparation processes use wet extraction technology, which separates protein components from starch, fiber, and soluble impurities through steps such as soaking, crushing, sieving, centrifugation, and drying. To improve the processing adaptability and flavor of pea raw materials, some processes introduce acidification or lactic acid bacteria fermentation treatment during the soaking stage, and combine it with airflow drying to achieve rapid powdering of the wet protein phase.

[0003] Existing wet extraction processes for peas typically aim to improve protein purity and remove starch and fiber. Soaking liquid, sieve fiber, and centrifugation supernatant are often discharged as by-products or waste. While this type of process is beneficial for protein component separation, if the crushing, sieving, and centrifugation intensity is too high when preparing cold-water reconstituted pea protein powder, starch particles in pea cotyledons are easily over-refined and discharged during the separation process. The wet protein phase is prone to forming dense wet clumps during temporary storage, transportation, and airflow drying feeding stages. The agglomerated particles obtained after drying are not easily disintegrated in cold water. Meanwhile, existing processes typically do not connect the aqueous phase components in the fermentation broth with the pre-drying conditioning process of the protein wet phase after horizontal centrifugation. They also lack continuous control over the fermentation endpoint, cotyledon cleavage degree, starch non-gelatinization state, wet phase conditioning method, and pre-drying dispersibility. This results in a lack of repeatable process connection between the front-end fermentation separation conditions and the final powder rehydration and dispersibility. Summary of the Invention

[0004] This invention provides a wet fermentation extraction and airflow drying process for peas, comprising: The sieved peas were soaked and fermented in the aqueous phase of Lactobacillus plantarum seed liquid to retain starch granules with polarized crosses in the fermented peas, thus obtaining fermented peas and soaking fermentation liquid. Fermented peas are crushed to separate the outer skin from the cotyledon surface and to crack the cotyledons, resulting in a crushed pulp containing skin fiber, protein particles and ungelatinized starch particles. The crushed pulp is centrifuged and screened, so that the bran fibers form an oversize layer on the inside of the screen, and the protein particles and ungelatinized starch particles enter the undersize pulp with the liquid phase. The slurry that passes through the sieve is sent to a horizontal screw centrifuge for solid-liquid separation to obtain a wet protein phase containing protein particles and ungelatinized starch particles; The fermented soybean broth was clarified to obtain a clarified fermented broth containing lactate, phytate, calcium ions and magnesium ions. After solid-liquid separation in a horizontal screw centrifuge, the clarified fermentation broth is added to the protein wet phase during the protein wet phase conditioning stage. The protein wet phase is then conditioned using a paddle stirring method with a blade tip linear velocity of no more than 1.9 m / s. This allows the clarified fermentation broth to enter the drying stage along with the protein wet phase, resulting in a conditioned protein wet phase. The conditioned protein wet phase is conveyed to the feed end of the airflow dryer via a screw conveyor. Before entering the airflow dryer tube, it is dispersed into wet granules by a needle-type dispersing mechanism. Then, it undergoes airflow drying, cooling, and granulation to obtain pea protein powder.

[0005] As a preferred embodiment of the pea wet fermentation extraction and airflow drying process of the present invention, wherein: the Lactobacillus plantarum is Lactobacillus plantarum Lp-HZ55, with accession number CCTCC No. M20221778; During the fermentation process of soaking beans, the pH and titratable acidity (calculated as lactic acid) of the fermentation liquid are measured as the basis for judging the degree of acidification of the fermentation liquid. The proportion of fine pulp and the cross-shaped pattern of polarized light after crushing fermented peas were detected as criteria for judging the degree of pea lysis and the state of starch non-gelatinization. The fermentation endpoint of the peas was determined based on the degree of acidification, the degree of pyrolysis, and the ungelatinized state of the starch, and the fermented peas were separated from the fermentation liquid.

[0006] As a preferred embodiment of the pea wet fermentation extraction and airflow drying process of the present invention, the fermented peas are separated from the soaking fermentation liquid, the fermented peas are drained, and then the drained fermented peas are sent to the crushing process. The crushing process employs either compression crushing or disc crushing to separate the outer skin from the cotyledon surface and to fracture the cotyledons.

[0007] As a preferred embodiment of the pea wet fermentation extraction and airflow drying process of the present invention, wherein the centrifugal sieving includes a stratification stage of the material on the sieve and a continuous sieving stage; In the oversize layering stage, the crushed pulp is first fed into a centrifugal screen, so that the fiber is retained on the inside of the screen to form an oversize layer. During the continuous screening stage, the crushed pulp is fed into a centrifugal screen, allowing protein particles and ungelatinized starch particles to pass through the screen with the liquid phase and enter the slurry below the screen.

[0008] As a preferred embodiment of the pea wet fermentation extraction and airflow drying process of the present invention, the sieved slurry is buffered and temporarily stored before entering the horizontal screw centrifuge, and is stirred by paddle during the buffering and temporary storage process, so that the protein particles and the ungelatinized starch particles enter the horizontal screw centrifuge together with the liquid phase.

[0009] As a preferred embodiment of the pea wet fermentation extraction and airflow drying process of the present invention, the main rotation speed of the horizontal screw centrifuge is 3100-3300 r / min, the differential speed is 10-12 r / min, and the feed rate is 0.75-0.85 m³ / h.

[0010] As a preferred embodiment of the pea wet fermentation extraction and airflow drying process of the present invention, wherein: the pea fermentation liquid is successively subjected to coarse filtration and centrifugation clarification to obtain the clarified fermentation liquid; Before adding the clarified fermentation broth to the protein wet phase, the levels of lactate, phytate, calcium ions, and magnesium ions in the clarified fermentation broth are detected, and the detected clarified fermentation broth is used to condition the protein wet phase obtained after horizontal screw centrifugation.

[0011] As a preferred embodiment of the pea wet fermentation extraction and airflow drying process described in this invention, the conditioning is carried out in a temporary storage tank equipped with double-layered paddles. During conditioning, first start the paddle stirring, then add the clarified fermentation broth along the inner wall of the temporary storage tank to the protein wet phase, and continue to use the paddle stirring method to mix the clarified fermentation broth with the protein wet phase to obtain the conditioned protein wet phase.

[0012] As a preferred embodiment of the pea wet fermentation extraction and airflow drying process of the present invention, the needle-type dispersing mechanism is arranged between the screw conveyor discharge end and the airflow drying tube inlet, so that the conditioning protein wet phase is dispersed into wet granular material before entering the airflow drying tube, and enters the airflow drying tube with the drying airflow.

[0013] The beneficial effects of this invention are: This invention controls the fermentation endpoint of peas, improving the binding state between the outer skin and cotyledons while retaining ungelatinized starch particles with a polarized cross shape. This is beneficial for the subsequent crushing, sieving, and horizontal centrifugation processes, which result in the separation of skin fibers, protein particles, and ungelatinized starch microparticles. By adding the clarified soybean fermentation broth to the protein wet phase after horizontal screw centrifugation, lactate, phytate, calcium and magnesium ions are brought into the airflow drying stage along with the protein wet phase, thus preserving this part of the aqueous phase components more completely and directly bypassing the losses in the front-end crushing, sieving and centrifugation processes. By retaining ungelatinized starch particles, using paddle stirring and conditioning with a blade tip linear velocity of no more than 1.9 m / s, screw conveying, and needle-type dispersing before drying, the formation of dense wet clumps in the wet protein phase can be reduced, making the agglomerated particles obtained from airflow drying easier to dissociate during cold water rehydration. Attached Figure Description

[0014] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a flowchart of the wet fermentation extraction and airflow drying process of peas in Example 1.

[0016] Figure 2 This is a schematic diagram of the rehydration and dissociation of pea protein powder in Example 1. Detailed Implementation

[0017] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0018] In this invention, the oversize layering stage is the pre-layering stage after the centrifugal screen is started. Its purpose is not to complete the screening of all the crushed pulp, but to feed the crushed pulp into the centrifugal screen at a feed rate lower than the normal continuous screening feed rate, so that the bran fibers in the crushed pulp are preferentially retained on the inner side of the screen and form an oversize layer on the inner side of the screen. The oversize layer is mainly composed of pea skin fibers, which can serve as a dynamic filtration layer, trapping longer skin fibers inside the screen while allowing protein particles and ungelatinized starch particles to pass through the screen with the liquid phase and enter the undersize slurry.

[0019] The continuous screening stage refers to the stage after the oversize layer is formed, where the feed rate is increased to a stable level and the crushed slurry is continuously fed in. During this stage, the oversize layer remains inside the screen, the bran fibers continue to be trapped, and the protein particles and ungelatinized starch particles enter the undersize slurry with the liquid phase. The difference between the oversize layering stage and the continuous screening stage is that the former aims to form a layer of fibrous oversize material, using a lower feed rate and a shorter time. The latter aims to continuously separate and break down pulp, using a stable feed rate and ensuring that the oversize layer continuously retains bran fibers and allows protein particles and ungelatinized starch particles to pass through during the screening process.

[0020] In Example 1, the oversize layering stage is initially achieved by feeding at 0.4 m³ / h for 2 min, followed by a continuous screening stage with a stable feed rate of 1.2 m³ / h. In Examples 3 and 4, the low feed rate and stable feed rate can be adjusted according to the solid content of the crushed pulp and the speed of the centrifugal screen, but both should meet the requirement of first forming a layer of fibrous material on the screen and then performing continuous screening.

[0021] Unless otherwise stated, the same batch of drinking water was used in Examples 1 to 4 and each comparative example; The drinking water has a pH of 7.12, a conductivity of 215 μS / cm, a calcium ion content of 18.7 mg / L, and a magnesium ion content of 5.6 mg / L. All groups used the same batch of drinking water during the processes of soaking and fermenting soybeans, resuspending seed liquid, conditioning the clarified fermentation liquid, and rehydrating the powder.

[0022] The basic indicators of the yellow peas used in this embodiment are: moisture content 10.8%, protein content 25.6% (dry basis), starch content 47.2% (dry basis), 100-pea weight 23.4g, and whole pea proportion 98.3%; The above indicators were determined using raw materials after screening in the same batch, and the basic raw material conditions for soaking beans to absorb water, the ratio of crushed fine pulp and the amount of protein wet phase starch retention in the examples were limited.

[0023] The method for preparing Lactobacillus plantarum seed culture is as follows: Lactobacillus plantarum Lp-HZ55 is inoculated into food-grade liquid culture medium and cultured at 37℃ for 18h.

[0024] Each liter of food-grade liquid culture medium contains 20g of glucose, 5g of edible yeast extract, 10g of soybean peptone, 3g of sodium acetate, and 2g of dipotassium hydrogen phosphate. The initial pH of the culture medium is 6.5. After the culture was completed, the bacterial cells were collected by centrifugation at 5000 r / min for 10 min, washed twice with sterile drinking water, resuspended in sterile drinking water, and the viable cell count was adjusted to the value specified in each example.

[0025] The pH of the fermented soybean broth was measured using a pH meter calibrated with standard buffer solutions of pH 4.00 and pH 6.86. The method for detecting titratable acid is as follows: Take 10.0 mL of fermented soybean broth, add 20 mL of deionized water, and titrate with 0.100 mol / L sodium hydroxide standard solution to pH 8.20. The titratable acid is calculated as lactic acid based on the amount of sodium hydroxide standard solution consumed.

[0026] The method for detecting the water absorption rate of peas is as follows: before fermentation, pea samples are randomly selected and the initial mass M0 is measured; after fermentation, the corresponding samples are taken out, drained on a sieve for 5 minutes, and the sample surface is touched three times with absorbent paper to measure the mass M1 after fermentation. The water absorption rate of peas is calculated as (M1 - M0) / M0 × 100%.

[0027] The method for detecting the crushing and fine pulp ratio of fermented peas is as follows: random samples are taken from the upper, middle and lower parts of the fermentation tank, and a total of 20 fermented peas are selected; the fermented peas are placed in a flat plate crushing device, the upper plate descends at a speed of 20 mm / min until the distance between the upper and lower plates is 2.5 mm, and the pressure is maintained for 5 seconds; Collect fracturing samples, add drinking water at a ratio of 1:10 (dry weight of fracturing sample to drinking water), stir at 300 r / min for 60 s, and then pass through an 80 mesh sieve for 2 min. The material that passed through an 80-mesh sieve was collected, and its dry weight was determined by the constant weight drying method at 105℃. The fine slurry ratio is calculated as the percentage of the dry matter mass passing through an 80-mesh sieve relative to the dry matter mass of the fracturing sample.

[0028] The starch content was determined by enzymatic hydrolysis, and the total starch content was converted according to the dry weight of the sample. The starch content measured by enzymatic hydrolysis is used to represent the total amount of starch retained in the wet phase or dry powder of protein, and is not directly equivalent to the content of ungelatinized starch particles. The content of ungelatinized starch particles was quantified using starch particle recovery, starch purity correction, and differential scanning calorimetry. The specific method is as follows: take a wet or dry protein powder sample, weigh it according to the dry basis, add a phosphate buffer solution with pH 7.0 to disperse it, and add 0.5% of the sample mass of food-grade alkaline protease. The food-grade alkaline protease has a labeled enzyme activity of 200,000 U / g and is treated at 50°C for 60 min to remove protein components attached to the surface of starch particles. Then, the solid phase was centrifuged at 5000 r / min for 10 min, the supernatant was discarded, and the obtained solid phase was washed three times with deionized water to obtain the recovered solid phase. After drying the recovered solid phase to constant weight at 40℃, a portion was taken and the mass ratio of starch in the recovered solid phase was determined by enzymatic hydrolysis. Another portion was mixed with water at a dry basis mass ratio of 1:3, sealed and equilibrated for 2 hours, and then detected by differential scanning calorimetry. During the testing, untreated pea starch from the same batch was used as an ungelatinized reference sample, and pea starch gelatinized in a 95℃ water bath for 30 minutes was used as a gelatinized reference sample. Using an empty crucible as a reference, the heating range was 25–110 °C, and the heating rate was 10 °C / min. When the starch gelatinization endothermic peak appears in the recovered solid phase, it confirms that the sample contains ungelatinized starch particles. The content of ungelatinized starch particles is calculated using the following formula: Ungelatinized starch particle content = proportion of the dry mass of the recovered solid phase to the dry mass of the sample × proportion of starch mass in the recovered solid phase × gelatinization endothermic enthalpy of the recovered solid phase as calculated based on the dry mass of starch ÷ gelatinization endothermic enthalpy of the ungelatinized reference sample as calculated based on the dry mass of starch. The result is expressed in g / 100g dry basis. Polarizing microscopy was used to confirm the morphology and polarization cross pattern of starch particles in the recovered solid phase, while differential scanning calorimetry was used to confirm and quantify the proportion of ungelatinized starch. The total starch content determined by enzymatic hydrolysis, the mass ratio of starch in the recovered solid phase, the results of polarized light microscopy observation, and the results of differential scanning calorimetry are used together to distinguish between the total starch content and the content of ungelatinized starch particles.

[0029] Lactate was detected by high performance liquid chromatography using an organic acid analytical column, with a mobile phase of 5 mmol / L sulfuric acid aqueous solution, a flow rate of 0.6 mL / min, a column temperature of 45 ℃, and a detection wavelength of 210 nm. Phytate was detected by ion chromatography using an anion exchange column and a conductivity detector. Calcium and magnesium ions were detected using inductively coupled plasma atomic emission spectrometry. In this invention, the calcium and magnesium ions in the clarified fermentation liquid do not only come from drinking water, but also mainly from the leaching of pea raw materials during the soaking and fermentation process and the release of phytate system under acidic conditions. The calcium and magnesium ion content in drinking water is used to define the basic background of the water quality used in each embodiment. The calcium and magnesium ion content in the clarified fermentation liquid is based on the actual measured value after the soybean fermentation is completed and clarified.

[0030] The method for detecting cold water dispersion time is as follows: Take 10.0g of pea protein powder and add it to a 300mL transparent glass beaker containing 200mL of drinking water at 20℃, and stir magnetically at 300r / min. The beaker was placed under a fixed light source with an illuminance of 1000 lx, and the camera device was positioned 25 cm from the side of the beaker to continuously capture images; Image analysis software was used to identify undispersed powder particles with an equivalent diameter of not less than 1.0 mm on the liquid surface and the inner wall of the beaker. The time during which no undispersed powder clumps are detected for 10 consecutive seconds is recorded as the cold water dispersion time.

[0031] The method for detecting the D90 particle size after rehydration is as follows: after completing the cold water dispersion test, continue stirring until 5 minutes after adding the powder, and then take the dispersion for laser particle size analysis. No ultrasonic treatment was performed before testing. All samples were tested using the same circulation flow rate and refractive index parameters. Each sample was tested in parallel three times and the average value was taken.

[0032] The method for testing the sedimentation rate after standing for 30 minutes is as follows: transfer the rehydrated dispersion to a graduated cylinder of the same size and let it stand for 30 minutes. Use a pipette to slowly remove the liquid above the sediment, leaving a 5 mm liquid layer above the sediment. The remaining sediment was transferred to a pre-weighed container and dried at 105°C to constant weight. The settling rate after 30 minutes of standing is calculated as the percentage of the dry mass of the settling material to the dry mass of the powder.

[0033] The method for detecting the proportion of lactate and phytate entering the aqueous phase in the initial stage of rehydration is as follows: after the powder is rehydrated for 5 min, take 20 mL of dispersion, centrifuge at 5000 r / min for 10 min, take the supernatant and filter it through a 0.22 μm aqueous phase filter membrane to determine the mass of lactate and phytate; The total mass of lactate and phytate in the dry powder was determined by extracting the dry powder and water at a mass ratio of 1:20 at 25°C with shaking for 30 min, repeating the extraction twice, and combining the extracts for determination. The proportion of the component entering the aqueous phase is calculated as the percentage of the corresponding component's mass in the supernatant after 5 minutes of rehydration to the total mass of the corresponding component in the dry powder.

[0034] The D50 of agglomerated particles was detected using a dry laser particle size analyzer. No mechanical grinding was performed before detection. The dry dispersion pressure was 0.15 MPa. Each sample was tested in parallel three times and the average value was taken. Rehydration observation was performed using an image counting method under a 100x optical microscope; Take one drop of the dispersion after rehydration for 5 minutes and place it on a glass slide. Observe 5 fields of view randomly under a 100x optical microscope. Use image analysis software to count the number of aggregated particles with an equivalent diameter of not less than 150 μm in each field of view and calculate the average number in each field of view.

[0035] Examples 1, 3, and 4 use 500L temporary storage tanks with the same structure; The storage tank has an inner diameter of 900mm, and both layers of blades are four-bladed oblique blades with a blade diameter of 500mm, a blade inclination angle of 45°, and an axial distance of 250mm between the upper and lower layers of blades. Example 1 uses a blade rotation speed of 60 r / min, which corresponds to a blade tip linear velocity of 1.57 m / s; Example 3 uses a blade rotation speed of 50 r / min, which corresponds to a blade tip linear velocity of 1.31 m / s; Example 4 uses a blade rotation speed of 70 r / min, which corresponds to a blade tip linear velocity of 1.83 m / s; In this invention, paddle stirring and conditioning refers to mixing the protein wet phase and the clarified fermentation broth with a paddle tip linear velocity of no more than 1.9 m / s under the above-mentioned double-layer paddle structure; This conditioning method does not mean that the wet protein phase is completely free from shearing. Rather, it limits the linear velocity at the blade tip, allowing the clarified fermentation broth to disperse into the wet protein phase while reducing the further fragmentation of ungelatinized starch particles and minimizing the formation of dense wet clumps in the wet protein phase. Whether the above conditioning method meets the requirements of this invention can be determined by the mass ratio of wet agglomerates with an equivalent diameter of not less than 10 mm after conditioning, the cold water dispersion time of the dried powder, the D90 particle size after rehydration, the sedimentation rate after standing for 30 min, and the gelatinization endothermic enthalpy of the recovered starch particles.

[0036] A needle-type dispersing mechanism is provided at the feed end of the airflow dryer. The rotor diameter of the needle-type dispersing mechanism is 160mm, and 12 dispersing needles are evenly arranged along the circumference of the rotor. The minimum gap between the end of the dispersing needle and the inner wall of the housing is 8mm. Examples 1, 3, and 4 use disintegration mechanism speeds of 650 r / min, 560 r / min, and 760 r / min, respectively, corresponding to rotor outer edge linear velocities of 5.45 m / s, 4.69 m / s, and 6.37 m / s, respectively.

[0037] In this invention, the endpoint of pea fermentation is not determined solely by fermentation time, but is determined by the pH of the fermentation liquid, the titratable acidity (calculated as lactic acid), the proportion of fine pulp after crushing fermented peas, and whether starch particles still exhibit a polarized cross under a polarizing microscope. pH and titratable acid are used to reflect the degree of acidification of the fermentation liquid of peas. The proportion of fine pulp passing through an 80-mesh sieve after cracking is used to reflect the binding state of the fermented pea skin and cotyledons and the degree of cotyledon rupture. Polarized cross is used to confirm that the starch granules have not undergone excessive gelatinization. When all of the above indicators are met, fermented peas can form a separate state of skin fiber, protein particles and ungelatinized starch particles during subsequent crushing, while avoiding over-fermentation that would damage the starch particle structure.

[0038] It should be noted that this invention does not rely solely on the polarized cross pattern at the end of the pea fermentation process to directly determine the rehydration performance of the final pea protein powder. In this invention, the polarized cross state is used as a criterion for pre-front structure retention to confirm that the starch granules in the pea cotyledons still retain an ungelatinized crystalline structure at the end of the pea fermentation process. The fine pulp ratio is used to determine the binding state between the outer bark and cotyledons, as well as the degree of cotyledon cleavage. Only when the degree of acidification, the ratio of fine pulp, and the polarization cross state are all satisfied can fermented peas more easily form a broken pulp containing skin fibers, protein particles, and ungelatinized starch particles during subsequent crushing, rather than forming an over-gelatinized or over-crushed pulp. In subsequent processes, whether ungelatinized starch particles are retained and enter the drying stage through the protein wet phase is confirmed by sampling and testing of the sieved slurry, protein wet phase, conditioned protein wet phase, and dried powder. Specifically, the total starch content in the wet protein phase was determined by enzymatic hydrolysis, and the presence of starch particles with polarized crosses was observed by polarizing microscope. The presence of starch gelatinization endothermic peaks in the dried powder was further confirmed by starch particle recovery and differential scanning calorimetry, and the content of ungelatinized starch particles was calculated. Therefore, the polarized cross state is used in this invention to define the end point of fermentation of soybeans and the initial retention state of ungelatinized starch particles. The subsequent rehydration performance is determined by the retention of ungelatinized starch particles, conditioning of clarified fermentation liquid, stirring and conditioning of paddle blades with a linear velocity of no more than 1.9 m / s at the blade tip, screw conveying, and needle-type dispersing before drying. When ungelatinized starch microparticles are located between adjacent protein particles in aggregated particles, they can form interparticle support gaps during the drying process; During rehydration, lactate and phytate enter the aqueous phase, weakening the binding state at the contact point of adjacent protein particles. Water can then enter the interior of aggregated particles through the gaps around the ungelatinized starch particles, thereby promoting the dissociation of aggregated particles. Therefore, the polarized cross pattern confirms that the starch particles were not destroyed at the front end, rather than simply equating the microscopic state at the end of soaking with the final rehydration performance.

[0039] In this invention, ungelatinized starch particles can still be detected after crushing, sieving, horizontal screw centrifugation, screw conveying, and airflow drying, mainly based on the following continuous control: No heat treatment is performed during the soybean soaking and fermentation stage; The temperature of the crushed material should be controlled below 35℃. The slurry that is screened out is only temporarily buffered by a low-speed paddle buffer before entering the horizontal screw centrifuge. Horizontal screw centrifuges are used for solid-liquid separation. The material stays in the machine for a short time and is not cooked or gelatinized. During wet-phase conditioning of protein, the material temperature should be controlled at 27–28℃. The screw conveyor is only used to transport the wet phase of the conditioning protein to the feed end of the airflow dryer, and is not equipped with a steam jacket heating. Although the inlet hot air temperature is relatively high, the material enters the airflow drying tube in a wet particle state. The moisture evaporates and takes away the heat. The residence time of the material in the drying tube is 6 to 7 seconds, and the drying outlet temperature is controlled at 72 to 84°C. After drying, the material is fluidized and cooled to below 35°C; Therefore, this invention does not rely solely on process estimation to conclude that the starch particles are not gelatinized, but confirms this in two stages: the wet protein phase, the dry powder phase, and the starch particle recovery and differential scanning calorimetry detection, respectively. When the screening accuracy is increased, the intensity of horizontal screw centrifugation is increased, or high-speed shear conditioning is used, the number of ungelatinized starch particles in the wet phase that can enter the subsequent drying stage with the protein particles decreases, or the interparticle support structure formed around the starch particles is destroyed. This ultimately results in a prolonged cold water dispersion time, an increased D90 particle size after rehydration, and an increased sedimentation rate.

[0040] Example 1, referring to Figure 1 and Figure 2 ; This embodiment applies to the preparation of instant pea protein powder, and the resulting pea protein powder is used for cold-water reconstituted plant protein drinks. Select 100kg of whole, mold-free, and insect-free yellow peas. After removing broken particles, sand, and light impurities by a vibrating screen, send them into a bean fermentation tank. Add 250 kg of drinking water to the fermentation tank for soaking beans and inoculate with Lactobacillus plantarum Lp-HZ55 seed culture; Lactobacillus plantarum Lp-HZ55 is deposited at the China Center for Type Culture Collection (CCTCC), located at Luojia Mountain, Bayi Road, Wuchang District, Wuhan City, Hubei Province, China. The accession number is CCTCC No. M 20221778, and the deposit date is November 14, 2022. This plant lactobacillus is used for the aqueous fermentation of soaked peas, which makes the fermentation liquid of soaked peas form an acidified aqueous phase containing lactate, and adjusts the binding state between the outer skin and cotyledons of peas in conjunction with the water absorption process of peas; The viable bacterial count at the time of seed culture inoculation was 1.0 × 10⁻⁶. 8 CFU / mL, inoculum volume is 3% of the soaking water volume; Soak beans at 32℃ and let them ferment for 16 hours. During the fermentation process, samples were taken every 4 hours to test the pH and titratable acidity of the fermentation liquid. At the end of fermentation, the pH of the fermentation broth was 5.18, the titratable acid (calculated as lactic acid) was 7.9 g / L, and the water absorption rate of the peas was 116%. The fermented peas were tested according to the aforementioned method for cracking and determining the proportion of fine pulp. The proportion of fine pulp passing through an 80-mesh sieve was 8.6%. The fractured samples were stained with iodine and observed under a polarizing microscope. Starch granules with polarized crosses were visible in all five randomly observed fields of view, indicating that the samples still contained ungelatinized starch granules after fermentation. After fermentation, the fermented peas are separated from the fermentation liquid. The separated fermented peas are drained of surface liquid for 5 minutes and then sent to an extruder. The roller spacing of the extrusion crusher is 1.2 mm, and the crushing pressure is 0.35 MPa. During crushing, the outer skin separates from the cotyledon surface, and the cotyledons are crushed, thus forming a crushed pulp containing skin fibers, protein particles, and ungelatinized starch particles.

[0041] The crushed slurry is fed into a centrifugal screen with a 120-mesh screen and a screen cylinder rotation speed of 900 r / min. First, at 0.4m 3 Feed at 1.2m / h for 2 minutes to allow the leather fibers to form a layer on the inside of the screen, then feed at 1.2m / h for 2 minutes. 3 A stable feed rate of / h allows protein particles and ungelatinized starch particles to pass through the screen with the liquid phase and enter the slurry below the screen. The slurry that passes through the sieve is temporarily stored in a buffer tank. The buffer tank is stirred by a paddle at a speed of 45 r / min, and the storage time is 10 min. The slurry that passes through the screen is then fed into a horizontal screw centrifuge. The main unit of the centrifuge rotates at 3200 r / min, the differential speed is 12 r / min, and the feed rate is 0.8 m³ / min. 3 / h, the supernatant and wet protein phase are separated; The wet phase solids content of the protein was 32.6%; The protein wet phase sample was washed and dispersed with water, and the starch content was determined by enzymatic hydrolysis. The starch content in the protein wet phase was found to be 2.8 g / 100 g dry basis. Another wet protein sample was stained with iodine and observed under a polarizing microscope. Starch granules with polarized crosses were visible in five randomly observed fields of view, indicating that the starch granules still contained ungelatinized starch granules. Separately, the fermented soybean broth was coarsely filtered through a 100-mesh sieve and then centrifuged at 5000 r / min for 8 min to obtain a clarified fermented broth. Lactate was detected by high performance liquid chromatography, phytate by ion chromatography, and calcium and magnesium ions by inductively coupled plasma atomic emission spectrometry. The samples were then used for conditioning in a temporary storage tank.

[0042] The wet phase of protein obtained by horizontal decanter centrifugation was directly sent to a 500L temporary storage tank. The temporary storage tank was equipped with double-layered blades, the blade speed was 60r / min, and the material temperature was controlled at 28℃. First, start the paddle agitator, then add the clarified fermentation broth at 8% of the protein wet phase mass along the inner wall of the temporary storage tank within 3 minutes, and continue stirring for 15 minutes to obtain the conditioned protein wet phase. In this process, a double-layer blade agitation with a blade tip linear velocity of 1.57 m / s is used for conditioning; The wet phase of the conditioning protein is conveyed into the feed end of the airflow dryer via a screw conveyor. The feed load of the airflow dryer is 45 kg / h, and the speed of the dispersing mechanism at the feed end is 650 r / min, which disperses the wet phase of the conditioning protein into wet granular material before it enters the airflow dryer tube. The inlet temperature of the airflow drying tube is 145℃, the outlet temperature is 78℃, the drying airflow velocity is 18m / s, and the material residence time in the drying tube is 6s. The dried material is collected by a cyclone separator and cooled to below 35°C in a fluidized bed cooler. After being granulated by passing through a 40-mesh sieve, it is packaged to obtain instant pea protein powder. The moisture content of the powder was determined by the constant weight drying method at 105℃. Comparative Example 1 was the same as Example 1 except that an equal amount of drinking water was used instead of the clarified fermentation liquid in the temporary storage tank. Comparative Example 2A was the same as Example 1 except that the centrifugal sieve mesh was changed from 120 mesh to 160 mesh. Comparative Example 2B was identical to Example 1 except that the main speed of the horizontal screw centrifuge was adjusted from 3200 r / min to 3600 r / min. Other raw material amounts, soybean soaking and fermentation conditions, crushing conditions, centrifugation and sieving conditions, amount of clarified fermentation liquid added, temporary storage and stirring conditions, airflow drying conditions and post-treatment conditions were the same. Comparative Example 3 was the same as Example 1 except that the clarified fermentation liquid was sprayed into the pea slurry after fermentation and before entering the extrusion crusher. The amount added during spraying is the same as the amount added to the temporary storage tank in Example 1. After spraying, a paddle mixer is used to mix at 60 r / min for 3 min. All the mixed material is sent to the extrusion crusher without further liquid discharge. Each test subject underwent three parallel trials, and the values ​​listed in Table 1 are the average values ​​of the three parallel trials; Table 1: Detection results of Example 1 and Comparative Examples 1 to 3 pH at the end of fermentation of soaked beans 5.18 5.19 5.17 5.18 5.18 Titratable acid, expressed as lactic acid (g / L) 7.9 7.8 7.9 7.9 7.9 Protein wet phase solids content (%) 32.6 32.8 32.5 32.7 32.7 Starch content (g / 100g dry basis) 2.8 2.7 0.9 1.2 2.6 Lactate content in clarified fermentation broth (g / L) 8.4 8.4 8.3 8.4 8.4 Phytate content in clarified fermentation broth (g / L) 1.15 1.15 1.13 1.14 1.14 Calcium ion content (mg / L) 214 214 211 212 213 Magnesium ion content (mg / L) 112 112 109 110 111 Moisture content of the dried powder (%) 5.4 5.5 5.3 5.4 5.6 Aggregated particle D50 (μm) 118 154 161 157 146 Cold water dispersion time (s) 43 94 109 101 82 D90 particle size (μm) after rehydration 84 208 221 213 171 Settling rate (%) after standing for 30 minutes 4.9 15.8 17.5 16.9 12.2 The percentage of lactate ions entering the aqueous phase during the initial stage of rehydration (%) 78.1 31.6 63.2 66.5 53.2 The percentage of phytate groups entering the aqueous phase during the initial rehydration stage (%) 61.4 24.8 45.3 48.6 40.1 Number of aggregated particles with an equivalent diameter of not less than 150 μm (particles / field of view) after 5 min of rehydration. 1.6 8.8 10.4 9.7 6.3 Observation of rehydration under a 100x optical microscope There are fewer large agglomerates and the dispersion is more uniform. Numerous large particle aggregates are visible. Numerous dense aggregated particles are visible. Numerous large particle aggregates are visible. Visible local aggregates As can be seen from Table 1, the pH, titratable acid and protein wet phase solids content at the end of fermentation of soybeans in Example 1 and each comparative example are similar, indicating that the basic material state of each group before entering the subsequent separation and drying process is basically the same. The cold water dispersion time of the pea protein powder obtained in Example 1 was 43s, the D90 particle size after rehydration was 84μm, and the sedimentation rate after standing for 30min was 4.9%, all of which were lower than those of the comparative examples. This indicates that retaining ungelatinized starch particles in the wet phase of the protein and adding clarified fermentation liquid to the temporary storage tank stage after horizontal decanter separation and stirring and conditioning with a paddle tip linear velocity of no more than 1.9m / s is beneficial for the dispersion of the powder in cold water after air drying. Comparative Example 1 used an equal amount of drinking water instead of the clarified fermentation broth in a temporary storage tank. Its starch content was 2.7 g / 100 g dry basis, which was similar to that of Example 1, but the cold water dispersion time was extended to 94 s, the D90 particle size increased to 208 μm after rehydration, and the sedimentation rate increased to 15.8%. Retaining only ungelatinized starch particles is insufficient to achieve the dispersion effect of Example 1; After the clarified fermentation broth is subjected to protein wet phase conditioning in the temporary storage tank stage, the resulting powder has better rehydration and dispersibility. Comparative Example 2A only changed the centrifuge screen mesh from 120 mesh to 160 mesh, and Comparative Example 2B only changed the speed of the horizontal screw centrifuge main unit from 3200 r / min to 3600 r / min; Both groups reduced the starch content in the wet phase of the protein, with Comparative Example 2A showing a reduction of 0.9 g / 100 g dry basis and Comparative Example 2B showing a reduction of 1.2 g / 100 g dry basis. Correspondingly, the cold water dispersion times for Comparative Example 2A and Comparative Example 2B were 109 s and 101 s, respectively, and the D90 particle sizes after rehydration were 221 μm and 213 μm, respectively, with sedimentation rates of 17.5% and 16.9%, respectively. Therefore, by improving the screening accuracy or increasing the strength of the horizontal screw separator, the amount of ungelatinized starch particles entering the protein wet phase along with the protein particles is reduced, and the powder obtained by airflow drying is more likely to form large particle agglomerates that are not easily dispersed after rehydration. Comparative Example 3 involved spraying the clarified fermentation broth onto the fermented pea slurry before it entered the extruder. Its starch content was 2.6 g / 100 g dry basis, which was similar to Example 1. However, the cold water dispersion time was 82 s, the D90 particle size after rehydration was 171 μm, the sedimentation rate was 12.2%, and the proportions of lactate and phytate entering the aqueous phase at the initial stage of rehydration were 53.2% and 40.1%, respectively, which were lower than those in Example 1. The timing of adding the clarified fermentation broth affects the conditioning effect; When added before crushing, its components undergo crushing, centrifugal sieving and horizontal screw separation processes, making it difficult to directly act on the wet protein phase as when added in the temporary storage tank stage. In Example 1, after the clarified fermentation broth was centrifuged in a horizontal screw centrifuge, a protein wet phase was added, and conditioning was completed under low-speed impeller stirring. At the initial stage of rehydration, the proportions of lactate and phytate entering the aqueous phase reached 78.1% and 61.4%, respectively. The combination of shorter cold water dispersion time, smaller D90 particle size after rehydration and lower sedimentation rate indicates that there is a process coordination relationship between the retention of ungelatinized starch microparticles, the addition of clarified fermentation broth in the temporary storage tank stage, and the paddle stirring and conditioning steps with a paddle tip linear velocity of no more than 1.9 m / s. The pea protein powder prepared by this process, after rehydration for 5 minutes, had an average of 1.6 agglomerated particles with an equivalent diameter of not less than 150 μm per field of view. The cold water dispersion time was 43 s, the D90 particle size after rehydration was 84 μm, and the sedimentation rate after standing for 30 minutes was 4.9%.

[0043] Example 2: In this example, a grinding disc crusher is used instead of the extrusion crusher in Example 1. The millstone crusher includes two millstones rotating in opposite directions. Fermented peas are fed between the two millstones by a feed screw. Under the limited gap between the millstones, they are subjected to squeezing and friction, which causes the pea skin to separate from the cotyledon surface and the cotyledons to be crushed to form a crushed pulp containing skin fiber, protein particles and ungelatinized starch particles. Take 100 kg of yellow peas that were screened in the same batch as in Example 1, and treat them under the same soaking and fermentation conditions as in Example 1. Ferment at 32°C in an aqueous phase for 16 hours. The fermentation endpoint pH was 5.20, the titratable acid (calculated as lactic acid) was 7.8 g / L, and the proportion of fine pulp passing through an 80-mesh sieve after fracturing was 8.9%. Fermented pea samples were subjected to iodine staining and polarized light microscopy. Iodine staining revealed starch granules, and polarized light microscopy also revealed starch granules with polarized crosses. After fermentation, the fermented peas are separated from the fermentation liquid. The fermented peas are drained for 5 minutes and then sent to a grinding mill. The grinding disc crusher uses a food-grade stainless steel grinding disc with a diameter of 300mm, a moving grinding disc speed of 720r / min, a grinding disc gap of 1.1mm, and a feed rate of 180kg / h. No additional water is added during the crushing process, and the temperature of the crushed material is controlled below 35℃. After crushing, a crushed pulp containing bran fiber, protein particles, and ungelatinized starch microparticles is obtained. The proportion of fine pulp passing through an 80-mesh sieve after crushing is 10.2%. The crushed pulp then enters a centrifugal sieve with a 120-mesh screen and a sieve cylinder rotation speed of 900 r / min. The feed rate is first 0.4 m³ / h for 2 min, and then 1.2 m³ / h for a stable feed rate, so that the bran fiber enters the material above the sieve, while the protein particles and ungelatinized starch particles enter the slurry below the sieve. The slurry that passes through the sieve is temporarily buffered and then fed into a horizontal decanter centrifuge. The main speed of the horizontal decanter centrifuge is 3200 r / min, the differential speed is 12 r / min, and the feed rate is 0.8 m³ / h to obtain a wet protein phase. The fermented soybean broth was coarsely filtered through a 100-mesh sieve and centrifuged at 5000 r / min for 8 min to obtain a clarified fermented broth. The clarified fermentation broth was added to a temporary storage tank at 8% of the wet phase protein mass, and conditioned for 15 min under double-layer impeller stirring at 60 r / min. The conditioning protein wet phase is conveyed into the airflow dryer feed end via a screw conveyor. The airflow dryer feed load is 45 kg / h, the dispersing mechanism speed is 650 r / min, the airflow dryer inlet temperature is 145℃, the outlet temperature is 78℃, and the airflow velocity is 18 m / s. After drying, it is separated by cyclone separation, fluidized cooling, and granulated by a 40-mesh sieve to obtain pea protein powder. Referring to Example 2-1, extrusion crushing was used with a roller gap of 1.2 mm and a crushing pressure of 0.35 MPa. The other conditions were the same as in this embodiment. Comparative Example 2-2 uses high-speed shear crushing with a crusher head rotation speed of 2800 r / min, and the other conditions are the same as in this embodiment. The high-speed shear crusher uses a four-blade cutter head with a diameter of 120mm, the minimum gap between the cutter head and the inner wall of the shell is 10mm, and the feed rate is 180kg / h; Comparative Examples 2-3 used grinding discs with a grinding disc gap of 0.4 mm for crushing, and the other conditions were the same as in this embodiment; Comparative Examples 2-4 used grinding discs with a grinding disc gap of 2.2 mm for crushing, and the other conditions were the same as in this embodiment; The temperature of the material after crushing in each crushing group is controlled below 35℃; Each test subject underwent three parallel trials, and the values ​​listed in Table 2 are the average values ​​of the three parallel trials; The fibrous fiber retention rate in the oversize material is calculated as the percentage of the dry weight of the fibrous fiber in the oversize material to the dry weight of the fibrous fiber in the crushed pulp. The dry weight of the fibrous fiber is obtained by washing with water to remove protein and starch and then drying to constant weight. The protein recovery rate of the undersize slurry is calculated as the percentage of the dry protein mass in the undersize slurry to the dry protein mass in the crushed slurry. The protein content is determined by the Kjeldahl nitrogen determination method and calculated according to the nitrogen conversion factor. The proportion of fine pulp that passes through an 80-mesh sieve after crushing is calculated as the percentage of the dry matter mass passing through the 80-mesh sieve to the dry matter mass of the crushed pulp. The starch content was detected using the same method as in Example 1. The starch content was determined by enzymatic hydrolysis, and the ungelatinized state was confirmed by iodine staining and polarizing microscopy. At least 5 fields of view were randomly selected during the observation under the polarizing microscope. The detection methods for cold water dispersion time, D90 particle size after rehydration, sedimentation rate after standing for 30 minutes, and rehydration observation under a 100x optical microscope are the same as those in Example 1. Table 2: Alternative Examples and Comparative Test Results of Grinding Disc Crushing pH at the end of fermentation of soaked beans 5.2 5.18 5.19 5.2 5.19 Breaking conditions Grinding disc gap 1.1mm Roller spacing 1.2mm, pressure 0.35MPa Cutter head speed 2800 r / min Grinding disc gap 0.4mm Grinding disc gap 2.2mm Temperature of the material after crushing (°C) 32.6 31.8 34.7 34.2 31.5 Fiber retention rate in the sieve residue (%) 91.6 92.8 63.4 72.5 94.1 Protein recovery rate of sieved slurry (%) 86.9 87.5 83.1 80.6 73.8 Starch content in wet protein phase (g / 100g dry basis) 2.7 2.8 1.1 0.8 3.4 The percentage of fine pulp passing through an 80-mesh sieve after crushing (%) 10.2 9.4 28.7 31.5 6.8 Protein wet phase solids content (%) 32.4 32.6 31.8 31.5 30.9 Moisture content of the dried powder (%) 5.5 5.4 5.6 5.5 5.7 Cold water dispersion time (s) 46 43 104 112 88 D90 particle size (μm) after rehydration 91 84 219 235 168 Settling rate (%) after standing for 30 minutes 5.5 4.9 16.9 18.1 11.6 Observation of rehydration under a 100x optical microscope Larger aggregated particles are less Larger aggregated particles are less Numerous fine, dense aggregates are visible. Visible dense aggregates It is evident that the particles were not sufficiently dispersed. Number of aggregated particles with an equivalent diameter of not less than 150 μm (particles / field of view) after 5 min of rehydration. 1.9 1.6 9.6 11.2 6.7 Table 2 shows that the fibrous retention rate, protein recovery rate and starch content of the oversize material in Example 2 and Reference Example 2-1 are similar, as are the cold water dispersion time, D90 particle size after rehydration and sedimentation rate. Therefore, under the conditions of this embodiment, the grinding disc with a grinding disc gap of 1.1 mm can obtain a crushed slurry state similar to that of extrusion crushing, and can be connected to subsequent centrifugal screening, horizontal screw centrifugation, temporary storage conditioning and airflow drying processes. After high-speed shear crushing, the fiber retention rate of the material on the sieve in Comparative Example 2-2 decreased to 63.4%, the proportion of fine pulp passing through the 80-mesh sieve increased to 28.7%, and the cold water dispersion time was extended to 104 s. The proportion of shredded leather fibers in this group was relatively high, and the centrifugal sieve's retention effect on leather fibers decreased. After the powder was rehydrated, a lot of fine and dense agglomerates were visible. Comparative Examples 2-3 used a 0.4 mm grinding disc gap, increased the fine slurry ratio to 31.5%, reduced the starch content in the wet protein phase to 0.8 g / 100 g dry basis, and had a higher cold water dispersion time and D90 particle size after rehydration than Example 2; The gap between the grinding discs in this group is too small, the cotyledons are ground too finely, the number of ungelatinized starch particles entering the wet phase of the protein is reduced, and the rehydration and dispersion of the powder after drying is slower. Comparative Examples 2-4 used a 2.2mm grinding disc gap. The retention rate of fibrous material in the oversize was relatively high, but the protein recovery rate of the undersize slurry dropped to 73.8%, and the cold water dispersion time was 88s. The high starch content in this group does not indicate that it has formed a state of uniformly accompanying protein particles into the wet phase, but is related to insufficient cotyledon cleavage and coarse particle entrainment. In this embodiment, with a grinding disc gap of 1.1 mm, a moving grinding disc speed of 720 r / min, and a feed rate of 180 kg / h, the proportion of fine pulp passing through an 80-mesh sieve after crushing is 10.2%, the bran fiber retention rate in the oversize material is 91.6%, the protein recovery rate of the undersize slurry is 86.9%, and the starch content in the wet protein phase is 2.7 g / 100 g dry basis. The resulting powder had a cold water dispersion time of 46 s, a D90 particle size of 91 μm after rehydration, and a sedimentation rate of 5.5% after standing for 30 min.

[0044] Example 3: This example uses fermentation conditions with a lower degree of acidification than Example 1, and reduces the amount of clarified fermentation liquid added, the temporary conditioning time, and the inlet temperature of the airflow drying. Except for the conditions explicitly adjusted in this embodiment, the raw material screening, ungelatinized starch particle detection method, rehydration dispersion detection method, powder moisture detection method, and post-processing method are the same as in Example 1; Take 100 kg of yellow peas after sieving and impurity removal, add 240 kg of drinking water, and inoculate with the same Lactobacillus plantarum seed culture as in Example 1, with a viable count of 8.0 × 10⁻⁶ at inoculation. 7 CFU / mL, inoculum volume is 2.0% of the soaking water volume; The peas were soaked and fermented at 30℃ for 12 hours. At the end of the fermentation, the pH of the fermentation liquid was 5.38, the titratable acid (calculated as lactic acid) was 5.6 g / L, and the water absorption rate of the peas was 101%. Fermented pea samples were crushed and sieved through an 80-mesh sieve according to the method described in Example 1. The proportion of fine pulp passing through the 80-mesh sieve was 6.9%. Starch granules can be seen after iodine staining, and starch granules with polarized crosses can still be observed under a polarizing microscope; After fermentation, the fermented peas are separated from the fermentation liquid. The fermented pea liquid is fed into an extrusion crusher after 5 minutes. The roller gap is 1.3 mm, the crushing pressure is 0.30 MPa, and the temperature of the crushed material is 31.5℃, resulting in a crushed slurry containing skin fiber, protein particles and ungelatinized starch particles. The crushed slurry is fed into a centrifugal screen with a screen mesh of 120 mesh and a screen cylinder rotation speed of 850 r / min. First, the feed rate is 0.35 m³ / h for 2 min, and then the feed rate is 1.0 m³ / h for a stable feed, so that the bran fiber enters the material above the screen, and the protein particles and ungelatinized starch particles enter the slurry below the screen. The slurry that is sieved is put into a buffer tank, stirred at 40 r / min for 8 min, and then sent to a horizontal screw centrifuge. The main unit of the horizontal decanter centrifuge rotates at 3100 r / min, the differential speed is 11 r / min, and the feed rate is 0.75 m³ / h, yielding a wet protein phase with a solids content of 31.2%. The fermented soybean broth was first filtered through a 100-mesh coarse filter and then centrifuged at 4800 r / min for 8 min to obtain a clarified fermented broth. Lactate in the clarified fermentation broth was detected by high performance liquid chromatography, phytate was detected by ion chromatography, and calcium and magnesium ions were detected by inductively coupled plasma atomic emission spectrometry. The test results were as follows: lactate content 5.9 g / L, phytate content 0.82 g / L, calcium ion content 176 mg / L, and magnesium ion content 91 mg / L. The wet protein phase was fed into a 500L temporary storage tank. The temporary storage tank was equipped with double-layered paddles, with a rotation speed of 50r / min and a material temperature of 27℃. The clarified fermentation broth was added along the tank wall at 4% of the protein wet phase mass over 2 minutes, and stirring was continued for 8 minutes to obtain the conditioned protein wet phase. The conditioning protein wet phase is conveyed into the airflow dryer feed end via a screw conveyor. The airflow dryer feed load is 38 kg / h, the dispersing mechanism speed is 560 r / min, the airflow dryer inlet temperature is 132℃, the outlet temperature is 72℃, the airflow velocity is 15 m / s, and the material residence time is 7 s. After drying, the material is separated by cyclone separation, fluidized cooling and granulated by a 40-mesh sieve to obtain pea protein powder; Comparative Example 3-1 was the same as this example except that an equal amount of drinking water was used instead of the clarified fermentation liquid in the temporary storage tank. Comparative Example 3-2 is the same as this embodiment except that the centrifugal sieve mesh is adjusted to 160 mesh. Comparative Example 3-3 replaced the conditioning method of 50 r / min paddle stirring in the temporary storage tank for 8 min with online stator-rotor high-speed shear homogenizer circulation for 3 min. The high-speed shear homogenizer has a rotor diameter of 80mm, a stator-rotor gap of 1.5mm, a rotation speed of 1800r / min, and a circulation flow rate of 1.0m³ / h. During the processing, jacket cooling is used to maintain the material temperature at 27±1℃. The other conditions are the same as in this embodiment. This comparative example is used to compare the effects of a paddle stirring temporary conditioning method with a blade tip linear velocity of no more than 1.9 m / s and an online stator-rotor high-speed shearing cycle conditioning method on the rehydration performance of powder. Its conditioning equipment, rotation speed and processing time are different from those in Example 3. Comparative Examples 3-4 are the same as this embodiment except that the dispersing mechanism at the feed end of the airflow dryer is removed, so that the wet phase of the conditioning protein is directly fed into the airflow dryer tube after being conveyed by the screw. Each test subject underwent three parallel trials, and the values ​​listed in Table 3 are the average values ​​of the three parallel trials; The cold water dispersion time, D90 particle size after rehydration, sedimentation rate after standing for 30 min, the proportion of lactate and phytate entering the aqueous phase at the initial stage of rehydration, and the observation method under a 100x optical microscope were the same as in Example 1. Comparative Example 3-1 did not add clarified fermentation broth. The proportions of lactate and phytate entering the aqueous phase in Table 3 are calculated based on the total amount of detectable lactate and phytate in the dry powder of this group, and are used to reflect the release of soluble components in the early stage of powder rehydration. Table 3: Examples and Comparative Test Results of Low Boundary Process pH at the end of fermentation of soaked beans 5.38 5.39 5.38 5.37 5.38 Titratable acid, expressed as lactic acid (g / L) 5.6 5.5 5.6 5.6 5.5 Lactate content in clarified fermentation broth (g / L) 5.9 5.9 5.8 5.9 5.9 Phytate content in clarified fermentation broth (g / L) 0.82 0.82 0.81 0.82 0.82 Calcium ion content (mg / L) 176 176 174 176 175 Magnesium ion content (mg / L) 91 91 90 91 91 Amount of clarified fermentation broth added (as a percentage of the wet phase protein mass, %) 4 0 4 4 4 Temporary conditioning method 50 r / min paddle stirring for 8 min 50 r / min paddle stirring for 8 min 50 r / min paddle stirring for 8 min Online high-speed shearing of stator and rotor for 3 minutes 50 r / min paddle stirring for 8 min Airflow drying inlet temperature (°C) 132 132 132 132 132 Rotational speed of the dispersing mechanism (r / min) 560 560 560 560 0 Protein wet phase solids content (%) 31.2 31.3 31.1 31.2 31.2 Starch content (g / 100g dry basis) 2.2 2.1 0.8 1.9 2.1 Moisture content of the dried powder (%) 5.8 5.9 5.7 5.8 6 Aggregated particle D50 (μm) 126 168 176 189 205 Cold water dispersion time (s) 58 121 137 146 155 D90 particle size (μm) after rehydration 112 245 261 276 292 Settling rate (%) after standing for 30 minutes 6.8 18.7 20.4 21.6 23.2 The percentage of lactate ions entering the aqueous phase during the initial stage of rehydration (%) 70.5 28.4 58.2 49.6 55.8 The percentage of phytate groups entering the aqueous phase during the initial rehydration stage (%) 54.2 20.7 41.3 35.9 39.8 Observation of rehydration under a 100x optical microscope Larger aggregated particles are less Numerous large particle aggregates are visible. Numerous dense aggregates are visible. Fine aggregates are visible after shearing. Numerous large aggregated particles are visible. Number of aggregated particles with an equivalent diameter of not less than 150 μm (particles / field of view) after 5 min of rehydration. 2.8 11.7 13.1 14.4 16.0 Note: No clarified fermentation broth was added to the protein wet phase in Comparative Example 3-1. The lactate, phytate, calcium and magnesium ion contents of the clarified fermentation broth listed in the table are the test values ​​of the same batch of soybean fermentation broth after clarification, and are only used to indicate the composition of the same batch of clarified fermentation broth. Compared with Example 1, this example reduces the degree of fermentation acidification, the amount of clarified fermentation broth added, the temporary storage conditioning time, and the inlet temperature of the airflow drying. In Table 3, the powder moisture content of Example 3 was 5.8%, the cold water dispersion time was 58s, the D90 particle size after rehydration was 112μm, and the sedimentation rate after standing for 30min was 6.8%. Under the above low boundary conditions, pea protein powder that can be dispersed in cold water was still obtained. Comparative Example 3-1 did not add clarified fermentation broth to the temporary storage tank. The cold water dispersion time was 121 s. After rehydration, the D90 particle size was 245 μm, and the sedimentation rate was 18.7%. With similar starch content, the rehydration and dispersion data of this group were weaker than those of Example 3; Comparative Example 3-2: The sieve was adjusted to 160 mesh, the starch content was reduced to 0.8 g / 100 g dry basis, the cold water dispersion time was 137 s, and the D90 particle size after rehydration was 261 μm. This set of data corresponds to a decrease in the amount of ungelatinized starch particles entering the wet protein phase after the sieving conditions were changed; After high-speed shear conditioning, the cold water dispersion time of Comparative Example 3-3 was 146 s, the D90 particle size after rehydration was 276 μm, the sedimentation rate after standing for 30 min was 21.6%, and the proportions of lactate and phytate entering the aqueous phase at the initial stage of rehydration were 49.6% and 35.9%, respectively. This group is used to compare the differences in powders obtained under two treatment methods: low-speed blade tempering and high-speed shear tempering. In Comparative Examples 3-4, the dispersing mechanism at the feed end of the airflow dryer was eliminated, and the wet phase of the conditioning protein was directly fed into the airflow dryer tube after being conveyed by the screw. The aggregated particles had a D50 of 205 μm, a D90 of 292 μm after rehydration, and a sedimentation rate of 23.2% after standing for 30 minutes. After the feed-end dispersing mechanism was removed in Comparative Examples 3-4, the D50 of the agglomerated particles increased from 126 μm in Example 3 to 205 μm, the D90 particle size after rehydration increased from 112 μm to 292 μm, and the sedimentation rate after standing for 30 min increased from 6.8% to 23.2%. The above results show that, under the low boundary conditions of this embodiment, the obtained powder can still be dispersed in cold water, and the various rehydration indicators are better than those of Comparative Examples 3-1 to 3-4.

[0045] Example 4: This example uses fermentation conditions with a higher degree of acidification than Example 1, and increases the amount of clarified fermentation liquid added, the content of protein wet phase solids, and the feed load of airflow drying. Except for the conditions explicitly adjusted in this embodiment, the raw material screening, source of Lactobacillus plantarum seed liquid, detection method for ungelatinized starch particles, ion detection method, rehydration dispersion detection method, powder moisture detection method, and post-processing method are the same as in Example 1; In this embodiment, the airflow drying feed load is the mass of the conditioning protein wet phase entering the airflow drying feed end per unit time; Take 100 kg of sieved yellow peas, add 260 kg of drinking water, and inoculate with the same Lactobacillus plantarum seed culture as in Example 1. The viable count of the seed culture at the time of inoculation was 1.2 × 10⁻⁶. 8 CFU / mL, inoculum volume is 4.0% of the soaking water volume; The peas were fermented at 34℃ for 20 hours. At the end of the fermentation, the pH of the fermentation liquid was 4.94, the titratable acid (calculated as lactic acid) was 10.4 g / L, and the water absorption rate of the peas was 128%. Fermented pea samples were crushed and sieved through an 80-mesh sieve according to the method described in Example 1. The proportion of fine pulp passing through the 80-mesh sieve was 10.7%. Starch granules are visible when iodine is stained, and can still be observed with a polarized cross under a polarizing microscope. After fermentation, separate the fermented peas from the fermentation liquid. After 5 minutes of fermentation, the pea slurry was fed into an extrusion crusher. The roller gap of the extrusion crusher was 1.0 mm, the crushing pressure was 0.42 MPa, and the temperature of the crushed material was 34.0℃, resulting in a crushed slurry containing skin fiber, protein particles and ungelatinized starch particles. The crushed slurry is fed into a centrifugal screen with a screen mesh of 120 mesh and a screen cylinder rotation speed of 950 r / min. The feed rate is 0.45 m³ / h for 2 minutes, and then the feed rate is 1.3 m³ / h for a stable period of time. The slurry that is sieved is put into a buffer tank, stirred at 50 r / min for 12 min, and then sent to a horizontal screw centrifuge. The main unit of the horizontal decanter centrifuge rotates at 3300 r / min, the differential speed is 10 r / min, and the feed rate is 0.85 m³ / h, yielding a wet protein phase. The protein wet phase solids content was 36.4%, and the starch content in the protein wet phase, determined by enzymatic hydrolysis, was 3.3 g / 100 g dry basis. Iodine staining and polarized light microscopy revealed that the starch microparticles still contained ungelatinized starch microparticles with polarized crosses. The fermented soybean broth was sequentially filtered through a 100-mesh coarse filter and then centrifuged for clarification. The centrifugation radius was 14 cm, the rotation speed was 5200 r / min, and the centrifugation time was 8 min to obtain the clarified fermented broth. The analysis revealed that the lactate content in the clarified fermentation broth was 10.8 g / L, the phytate content was 1.43 g / L, the calcium ion content was 249 mg / L, and the magnesium ion content was 131 mg / L. The wet phase of protein was fed into a 500L temporary storage tank. The temporary storage tank was equipped with double-layer blades with a blade speed of 70 r / min and a material temperature of 30℃. Add the clarified fermentation broth along the inner wall of the temporary storage tank at 12% of the protein wet phase mass over 5 minutes, and continue stirring for 20 minutes to obtain the conditioned protein wet phase. The wet-phase solids content of the conditioning protein was 32.7%; The double-layer blades did not stop rotating during the conditioning period; Subsequently, a 30-minute screw conveying test was conducted. Every 5 minutes, the wet phase of the conditioning protein discharged within 1 minute was continuously collected at the discharge end of the screw conveyor and weighed. The instantaneous conveying volume was calculated based on the collected mass. The instantaneous conveying capacity measured in the six tests was 54.2 kg / h, 53.8 kg / h, 55.1 kg / h, 54.7 kg / h, 56.1 kg / h and 55.4 kg / h, respectively. No feeding interruption or blockage occurred during the test. The wet phase of the conditioning protein is conveyed into the feed end of the airflow dryer via a screw conveyor. The feed load of the airflow dryer is 55 kg / h, and the speed of the dispersing mechanism at the feed end is 760 r / min. The inlet temperature of the airflow dryer was set to 158℃, the airflow velocity was 21m / s, the material residence time in the airflow dryer tube was about 5s, and the outlet temperature was recorded as 84℃. The dried material is collected by a cyclone separator, cooled to below 35°C in a fluidized bed cooler, granulated through a 40-mesh sieve, and then packaged to obtain pea protein powder. The dried pea protein powder was subjected to ungelatinized starch state testing. The powder was dispersed in water at 20°C and then observed under a polarizing microscope, with five fields of view observed randomly. Take another 10g of powder and add it to 100mL of phosphate buffer solution with a pH of 8.0. Add 0.5% of the powder mass of food-grade alkaline protease. The alkaline protease is labeled with an enzyme activity of 200,000 U / g. After treatment at 50℃ for 60 min, centrifuge at 5000 r / min for 10 min, discard the supernatant, and wash the obtained solid phase three times with deionized water to recover starch particles. After the recovered starch microparticles were dried to constant weight at 40℃, they were mixed with water at a dry basis mass ratio of 1:3, sealed and equilibrated for 2 hours, and then detected by differential scanning calorimetry. The test simultaneously included untreated pea starch as an ungelatinized reference sample and pea starch gelatinized in a 95℃ water bath for 30 minutes as a gelatinized reference sample. Using an empty crucible as a reference, the heating range was 25–110 °C, and the heating rate was 10 °C / min. When the starch particles to be recovered show an endothermic peak of starch gelatinization, it is confirmed that the dried powder still contains ungelatinized starch particles. The D50 of agglomerated particles was detected using a dry laser particle size analyzer. No mechanical grinding was performed before detection. The dry dispersion pressure was 0.15 MPa. Each sample was tested in parallel three times and the average value was taken. The cold water dispersion time, D90 particle size after rehydration, sedimentation rate after standing for 30 min, the proportion of lactate and phytate entering the aqueous phase at the initial stage of rehydration, and the observation method under a 100x optical microscope were the same as in Example 1. Comparative Example 4-1 was the same as Example 4 except that the soaking and fermentation time of the beans was extended from 20 hours to 24 hours. Comparative Example 4-2 was the same as Example 4 except that the amount of clarified fermentation broth added was increased from 12% to 16% of the protein wet phase mass. Comparative Example 4-3 only reduced the differential speed of the horizontal screw centrifuge from 10 r / min to 6 r / min, while the other conditions were the same as in Example 4; Comparative Example 4-4 only increased the feed load of the airflow dryer from 55 kg / h to 70 kg / h, kept the inlet temperature and airflow velocity of the airflow dryer the same as in Example 4, recorded the outlet temperature as the detection value, and the other conditions were the same as in Example 4. Each test subject underwent three parallel trials, and the values ​​listed in Table 4 are the average values ​​of the three parallel trials; In Example 4 and Comparative Examples 4-1 to 4-4, the inlet temperature and airflow velocity of the airflow dryer were controlled as equipment setting parameters, and the outlet temperature of the airflow dryer was recorded as a detection value during the material drying process. Table 4: Examples and Comparative Test Results of High Boundary Processes Soaking and fermentation time for beans (h) 20 24 20 20 20 pH at the end of fermentation of soaked beans 4.94 4.68 4.94 4.94 4.94 Titratable acid, expressed as lactic acid (g / L) 10.4 13.1 10.4 10.4 10.4 The percentage of fine pulp passing through an 80-mesh sieve (%) 10.7 19.8 10.8 10.7 10.7 Lactate content in clarified fermentation broth (g / L) 10.8 13.5 10.8 10.8 10.8 Phytate content in clarified fermentation broth (g / L) 1.43 1.58 1.43 1.43 1.43 Calcium ion content (mg / L) 249 263 249 249 249 Magnesium ion content (mg / L) 131 139 131 131 131 The amount of clarified fermentation broth added, as a percentage of the wet phase protein mass (%) 12 12 16 12 12 Differential speed of horizontal decanter centrifuge (r / min) 10 10 10 6 10 Protein wet phase solids content (%) 36.4 36.2 36.3 40.6 36.4 Conditioned protein wet phase solids content (%) 32.7 32.6 31.5 36.4 32.7 Starch content in wet protein phase (g / 100g dry basis) 3.3 2.4 3.2 3.5 3.3 Airflow dryer feed load (kg / h) 55 55 55 55 70 Airflow drying inlet temperature (°C) 158 158 158 158 158 Airflow drying outlet temperature (°C) 84 83 80 87 75 Moisture content of the dried powder (%) 5.2 5.5 5.6 6.3 6.8 Starch content in dried powder (g / 100g dry basis) 2.9 2 2.8 3.1 2.9 Observation results of polarizing microscope The polarized crosshair is visible in all 5 fields of view. 4 visible polarizing crosshairs The polarized crosshair is visible in all 5 fields of view. The polarized crosshair is visible in all 5 fields of view. The polarized crosshair is visible in all 5 fields of view. Endothermic peak temperature of starch gelatinization (°C) 71.6 71.4 71.5 71.7 71.6 The endothermic enthalpy of starch gelatinization, expressed as the dry weight of the recovered starch (J / g). 8.3 6.9 8 8.4 8.2 Aggregated particle D50 (μm) 132 169 161 184 198 Cold water dispersion time (s) 49 87 78 103 117 D90 particle size (μm) after rehydration 96 176 158 207 236 Settling rate (%) after standing for 30 minutes 5.8 11.9 10.6 14.8 18.1 The percentage of lactate ions entering the aqueous phase during the initial stage of rehydration (%) 82.4 69.7 73.1 67.3 64.9 The percentage of phytate groups entering the aqueous phase during the initial rehydration stage (%) 65.7 52.8 57.6 49.5 46.8 Number of aggregated particles with an equivalent diameter of not less than 150 μm (particles / field of view) after 5 min of rehydration. 2.1 6.9 5.8 8.7 10.9 Observation of rehydration under a 100x optical microscope Larger aggregated particles are less Numerous irregularly aggregated particles are visible. Visible localized dense aggregates of particles Numerous dense, large particles are visible. Numerous large aggregated particles are visible. In Table 4, polarized crosses can be observed in all five polarized light microscope fields of the dried powder in Example 4. The gelatinization endothermic peak temperature of the recovered starch particles is 71.6℃ and the gelatinization endothermic enthalpy is 8.3J / g, indicating that ungelatinized starch particles are still retained in the powder after airflow drying. The resulting powder had a moisture content of 5.2%, a cold water dispersion time of 49 s, a D90 particle size of 96 μm after rehydration, and a sedimentation rate of 5.8%. After extending the soaking and fermentation time of soybeans in Comparative Example 4-1, the proportion of fine pulp passing through an 80-mesh sieve increased to 19.8%, and the starch content in the dried powder decreased to 2.0 g / 100 g dry basis. The results of polarizing microscopy showed that starch particles with polarizing crosses were visible in 4 out of 5 randomly observed fields of view, and the dispersion time in cold water was extended to 87 s. After increasing the amount of clarified fermentation broth added in Comparative Example 4-2, the wet phase solids content of the conditioning protein decreased from 32.7% to 31.5%, the outlet temperature of the airflow dryer decreased to 80℃, the powder moisture content increased to 5.6%, and the D90 particle size after rehydration was 158μm. After reducing the differential speed of the horizontal screw centrifuge in Comparative Example 4-3, the solid content of the wet protein phase increased to 40.6%, the starch content in the wet protein phase was 3.5 g / 100 g dry basis, the solid content of the wet protein phase in the conditioning protein phase was 36.4%, and the outlet temperature of the airflow dryer was 87℃. With the conditioning, dispersing, and airflow drying conditions unchanged, the moisture content of the dried powder was 6.3%, the cold water dispersion time was 103 s, the D90 particle size after rehydration was 207 μm, and the sedimentation rate after standing for 30 min was 14.8%. When the feed load of the airflow dryer is increased to 70 kg / h, the outlet temperature drops to 75℃, the powder moisture content rises to 6.8%, the D50 of agglomerated particles increases to 198 μm, and the D90 particle size increases to 236 μm after rehydration. Many large aggregates of particles can be seen under a 100x optical microscope.

[0046] Verification Example 1 This verification example uses the pea protein powder obtained in Example 1 as verification sample 1; Three control samples were set up: Control sample 1-1 was prepared under the same conditions as in Example 1, except that the same mass of drinking water was used instead of the clarified fermentation liquid in the temporary storage tank. The preparation conditions for control samples 1-2 were the same as those in Example 1, except that the centrifuge sieve mesh was changed from 120 mesh to 160 mesh. Except for adding the clarified fermentation broth after fermenting the pea slurry and before it enters the extruder, the preparation conditions for control samples 1-3 were the same as in Example 1. The amount of water added during spraying, the mixing method, and the treatment method without separate drainage are the same as those in Comparative Example 3 in Example 1; Each control sample was modified only by whether the clarified fermentation broth was added, the mesh size of the centrifuge sieve, or the timing of the addition of the clarified fermentation broth. Weigh 5.00g of each sample and add them to a 250mL glass beaker containing 100mL of drinking water of the same batch at 20℃. Stir at 300r / min using a 30mm diameter paddle stirrer. Each sample was set up in three independent rehydration containers for 30s, 120s and 300s. Stirring was stopped and samples were taken immediately after the corresponding time was reached to avoid repeated sampling of the same container and causing changes in the material-liquid ratio. Three parallel experiments were conducted at each time point; A portion of the dispersion was directly used for laser particle size analysis, and the D90 particle size after rehydration was recorded. Another part was centrifuged at 5000 r / min for 5 min, and the supernatant was filtered through a 0.45 μm filter membrane. The contents of lactate and phytate were detected by high performance liquid chromatography and ion chromatography, respectively. The total extractable lactate in the dry powder was determined after extraction with water at 40℃ for 60 min, and the total extractable phytate in the dry powder was determined after extraction with 0.5 mol / L hydrochloric acid for 2 h. The proportions of lactate and phytate entering the aqueous phase at each time point are calculated as the percentage of the corresponding component mass in the supernatant at that time point relative to the total extractable mass of the corresponding component in the dry powder. Take agglomerated particles from each sample and place them in a transparent rehydration observation tank. Use a 200x digital microscope to record the particle changes within 300 seconds after adding the same batch of drinking water at 20°C. For each sample, 30 aggregated particles were randomly observed, and the location where the aggregated particles first showed visible separation was recorded. When the first separation occurs at the contact point between adjacent particles that can be identified before the addition of water, it is recorded as separation along the contact point; The separation ratio along the contact position is calculated as the percentage of the number of aggregated particles that first separate along the contact position relative to the total number of aggregated particles observed. After rehydration for 300 seconds, the number of aggregated particles with an equivalent diameter greater than 200 μm was counted in 10 random fields of view for each sample. The settling rate was tested after standing for 30 minutes according to the method described in Example 1. Table 5: Results of component entry into the aqueous phase and dissociation of aggregated particles during rehydration process Percentage of lactate ions entering the aqueous phase in 30 seconds (%) 42.6 14.3 33.4 27.8 Percentage of lactate ions entering the aqueous phase at 120s (%) 66.8 24.7 53.7 44.5 Percentage of lactate ions entering the aqueous phase after 300s (%) 78.1 31.6 63.2 53.2 Percentage of phytate groups entering the aqueous phase in 30 seconds (%) 26.9 10.1 20.5 17.2 Percentage of phytate ions entering the aqueous phase at 120s (%) 48.7 18.6 36.8 31.6 Percentage of phytate ions entering the aqueous phase after 300 seconds (%) 61.4 24.8 45.3 40.1 D90 particle size (μm) after 30s rehydration 205 338 352 309 D90 particle size (μm) after rehydration for 120 s 124 264 284 226 D90 particle size (μm) after rehydration for 300 s 84 208 221 171 Percentage of initial separation at the contact point (%) 82 31 36.7 54.3 Number of aggregated particles larger than 200 μm per field of view after 300 s 2.3 14.6 16.2 9.1 Settling rate (%) after standing for 30 minutes 4.9 15.8 17.5 12.2 The results showed that 42.6% lactate and 26.9% phytate had entered the aqueous phase after 30 seconds of rehydration in sample 1. After the rehydration time was extended to 300s, the proportions of the two entering the aqueous phase reached 78.1% and 61.4%, respectively, while the D90 particle size decreased from 205μm to 84μm; In the microscopic recording, 82.0% of the aggregated particles first separated from the pre-identifiable particle contact sites, and after 300 s, there were 2.3 aggregated particles larger than 200 μm in each field of view; Control sample 1-1 retained sieving and drying conditions similar to those of validation sample 1, but no clarified fermentation broth was added to the temporary storage tank; At 300 s, the proportions of lactate and phytate entering the aqueous phase of this sample were 31.6% and 24.8%, respectively, with a D90 particle size of 208 μm. The initial separation proportion along the contact point was 31.0%. In control samples 1-2, the centrifuge sieve mesh was simply adjusted to 160 mesh, which reduced the number of ungelatinized starch particles entering the wet protein phase. Although the proportions of 300s lactate and phytate entering the aqueous phase reached 63.2% and 45.3%, respectively, the D90 particle size was still 221 μm, and the initial separation ratio along the contact position was 36.7%. After the soluble components in this group enter the aqueous phase, the aggregated particles still retain a large rehydrated particle size; The control samples 1-3 only changed the timing of adding the clarified fermentation broth. The ratio of lactate and phytate entering the aqueous phase at 300s, the initial separation ratio along the contact position, and the D90 particle size after rehydration were all between the verification sample 1 and the control sample 1-1. The time series listed in Table 5 shows that the process of lactate and phytate entering the aqueous phase in sample 1 occurred during the same rehydration stage as the reduction in particle size of aggregated particles and the separation of particle contact sites.

[0047] Verification Example 2 This verification example uses the pea protein powder obtained in Example 1 as verification sample 2; Three control samples were set up: Control sample 2-1 was prepared under the same conditions as in Example 1, except that the same mass of drinking water was used instead of the clarified fermentation liquid in the temporary storage tank. The preparation conditions for control sample 2-2 were the same as those in Example 1, except that the centrifuge sieve mesh was changed from 120 mesh to 160 mesh. Except for the conditioning treatment, the preparation conditions for control samples 2-3 were the same as those in Example 1. After adding the clarified fermentation broth to the protein wet phase, the first 3 minutes of the conditioning process were changed to use an online stator-rotor high-speed shear homogenizer for circulation treatment, followed by 12 minutes of stirring with double-layer blades at 60 r / min, so that the total conditioning time was kept at 15 minutes. The high-speed shear homogenizer has a rotor diameter of 80mm, a stator-rotor gap of 1.5mm, a rotation speed of 1800r / min, and a circulation flow rate of 1.0m³ / h. Jacketed cooling is used during the processing to keep the material temperature at 28±1℃; Agglomerated particles whose dry laser particle size distribution results fall within 20% above or below their respective D50 values ​​are selected from each sample. Thirty aggregated particles were randomly selected from each sample for cross-sectional structure and component location detection. Aggregated particles used for polarizing microscopy and Raman imaging were embedded in low-temperature curing resin, cured without vacuum, and then cut into sections with a thickness of 8 μm. Starch particles in the cross-section were observed using a polarizing microscope. Starch particles with a clear polarized cross are classified as ungelatinized starch particles; Micro Raman imaging was used to detect adjacent cross sections with a scanning step of 1 μm, and Raman spectra of pea protein, natural pea starch, sodium lactate and sodium phytate standards were collected as references. Protein regions, starch regions, lactate-related regions, and phytate-related regions were identified by standard spectral fitting. The boundary between two identifiable protein particles and the 2μm range on both sides are defined as the protein particle contact area. The 2μm range outside the edge of the ungelatinized starch particles is defined as the surface region of the starch particles; Protein regions more than 10 μm away from the particle contact area and the starch particle surface area are defined as non-contact areas. Each sample should have at least 100 protein particle contact areas and 100 starch particle surface areas counted. The agglomerated particles used for calcium and magnesium element distribution detection were brittlely fractured after being cooled with liquid nitrogen for 2 minutes. The natural fracture surface was selected for carbon sputtering, and elemental surface scanning was performed using a scanning electron microscope combined with an energy dispersive spectroscopy (EDS). The enrichment coefficient of calcium and magnesium in the contact area is calculated as the ratio of the average elemental signal intensity in the contact area to the average elemental signal intensity in the non-contact area. The enrichment coefficients of calcium and magnesium on the starch surface are calculated as the ratio of the average elemental signal intensity in the surface region of starch particles to the average elemental signal intensity in the non-contact region. The interstitial distribution of ungelatinized starch particles is defined as the percentage of ungelatinized starch particles located between two adjacent protein particles to the total number of ungelatinized starch particles observed. The positive rate of lactate and phytate contact areas is calculated as the percentage of the number of contact areas that detected the corresponding standard spectral characteristics to the total number of contact areas counted. The positive rates of lactate and phytate starch surfaces were calculated using the same method. The proportion of pore area in the cross section of agglomerated particles was determined using image analysis software, and was calculated as the percentage of pore area in the cross section to the total cross section area of ​​agglomerated particles. Table 6: Detection results of cross-sectional structure, component distribution and elemental enrichment of aggregated particles Percentage of ungelatinized starch particles in interparticle space (%) 78.4 75.9 25.7 44.1 The percentage (%) of starch particles with polarized crosses within the interstitial spaces. 91.2 90.8 89.4 88.6 Percentage of pore area in cross-section of agglomerated particles (%) 18.6 14.7 8.9 9.7 Positive rate (%) of lactate contact area 74.2 16.8 60.5 47.6 Positive rate (%) of phytate-contact areas 67.8 18.6 55.1 42.8 positive rate of lactate starch surface (%) 69.5 14.9 23.7 38.9 Positive rate of phytate starch surface (%) 63.1 16.2 21.4 34.7 Calcium contact area enrichment coefficient 2.35 1.16 1.91 1.54 Magnesium contact region enrichment coefficient 2.08 1.11 1.74 1.45 Calcium element starch surface enrichment coefficient 2.12 1.13 1.32 1.48 Magnesium enrichment coefficient on starch surface 1.94 1.09 1.28 1.4 In the verification sample 2, 78.4% of the ungelatinized starch microparticles were located between adjacent protein particles, 91.2% of the starch microparticles in the interstitial space had a polarized cross shape, and the proportion of pore area in the cross section of the aggregated particles was 18.6%. The positive rates of lactate and phytate in the protein particle contact area were 74.2% and 67.8%, respectively, and the positive rates in the starch particle surface area were 69.5% and 63.1%, respectively. The enrichment coefficients of calcium and magnesium in the contact area were 2.35 and 2.08, respectively, and the enrichment coefficients of calcium and magnesium in the surface area of ​​starch particles were 2.12 and 1.94, respectively. The control sample 2-1 did not have the clarified fermentation broth added. The interstitial distribution ratio of ungelatinized starch particles was still 75.9%, but the positive rates of lactate and phytate in the contact area and the surface area of ​​starch particles were both less than 20%, and the enrichment coefficients of calcium and magnesium were close to 1. Compared with control sample 2-2, which only had its centrifugal sieve mesh adjusted to 160 mesh, the proportion of ungelatinized starch particles in the interstitial distribution decreased to 25.7%, and the proportion of agglomerated particle cross-sectional pore area decreased to 8.9%. The positive rates of lactate and phytate in the contact area of ​​this sample were still higher than those of the control sample 2-1, but the positive rates of lactate and phytate on the surface of starch particles were 23.7% and 21.4%, respectively. Control samples 2-3 were subjected to high-speed shear conditioning. The interparticle distribution ratio of ungelatinized starch was 44.1%, the cross-sectional pore area ratio was 9.7%, and the positive rates of lactate and phytate contact areas, as well as the enrichment coefficients of calcium and magnesium, were all lower than those of verification sample 2. The material temperature remains constant during high-speed shearing, therefore the difference in detection is not attributed to temperature rise; The results of cross-sectional inspection, micro Raman imaging, and elemental surface scanning in Table 6 show that the ungelatinized starch particles in the verification sample 2 are mainly distributed between adjacent protein particles. Lactate and phytate showed high positive rates in the protein particle contact area and the surface area of ​​ungelatinized starch particles, while calcium and magnesium showed high enrichment coefficients in the above areas.

[0048] Verification Example 3 This verification example illustrates the effect of blade tip linear velocity on the wet phase conditioning state of protein and the rehydration performance of dried powder. This verification example uses the same yellow pea raw materials, soaking and fermentation conditions, fermented pea crushing conditions, centrifugation and sieving conditions, horizontal screw centrifugation conditions, clarified fermentation liquid preparation conditions, clarified fermentation liquid addition amount, airflow drying conditions, and post-treatment conditions as in Example 1, only changing the rotation speed of the double-layer blades in the temporary storage tank. The amount of clarified fermentation broth added to each group was 8% of the wet phase mass of the protein. The clarified fermentation broth was added along the inner wall of the temporary storage tank within 3 minutes, and then conditioning was continued for 15 minutes after addition. During the conditioning process, the same temporary storage tank jacket was used for temperature control. At the beginning of conditioning, the wet phase temperature of the protein was controlled at 28℃, and at the end of conditioning, the material temperature was controlled at 28-30℃. When the blade speed is increased to 80 r / min and 90 r / min, the temperature of the material at the end of the conditioning process is still controlled by jacket cooling to not exceed 30°C, so as to eliminate the influence of the temperature rise during the conditioning process on the state of the ungelatinized starch particles. The temporary storage tank used in this verification example has an inner diameter of 900 mm, and both layers of blades are four-bladed oblique blades with a blade diameter of 500 mm, a blade inclination angle of 45°, and an axial distance of 250 mm between the upper and lower layers of blades. The blade tip linear velocity is calculated based on the blade tip circumferential velocity. When the blade rotation speed is 50 r / min, 60 r / min and 70 r / min, the corresponding blade tip linear velocities are 1.31 m / s, 1.57 m / s and 1.83 m / s, respectively. When the blade rotation speed is 80 r / min and 90 r / min, the corresponding blade tip linear velocities are 2.09 m / s and 2.36 m / s, respectively. The method for detecting the proportion of wet pellets with an equivalent diameter of not less than 10 mm after conditioning is as follows: After conditioning, immediately take 500g of the conditioning protein wet phase sample from the top, middle and bottom of the temporary storage tank, place it gently on a stainless steel sieve with a pore size of 10mm, let it stand for 30s without vibration, collect the wet clumps left on the sieve surface and weigh them. The proportion of wet flocs with an equivalent diameter of not less than 10 mm after conditioning is calculated as the percentage of the wet floc mass on the sieve surface to the total sample mass. The endothermic enthalpy of gelatinization of recovered starch microparticles, cold water dispersion time, D90 particle size after rehydration, sedimentation rate after standing for 30 min, and number of agglomerated particles with an equivalent diameter of not less than 150 μm after rehydration for 5 min were all tested according to the methods described above in this instruction manual. Each test subject underwent three parallel trials, and the values ​​listed in Table 7 are the average values ​​of the three parallel trials. Table 7: Effect of blade tip linear velocity on conditioning state and rehydration performance Blade rotation speed (r / min) 50 60 70 80 90 Blade tip linear velocity (m / s) 1.31 1.57 1.83 2.09 2.36 The amount of clarified fermentation broth added, as a percentage of the wet phase protein mass (%) 8 8 8 8 8 Conditioning time (min) 15 15 15 15 15 Temperature of material at the end of conditioning (°C) 28.6 28.7 28.9 29.2 29.5 Percentage of wet clumps ≥10mm after conditioning (%) 3.6 3.9 5.2 13.7 21.5 Starch content in wet protein phase (g / 100g dry basis) 2.8 2.8 2.7 2.6 2.5 Content of ungelatinized starch particles in dried powder (g / 100g dry basis) 2.31 2.34 2.23 1.71 1.48 Endothermic enthalpy (J / g) of gelatinization of recovered starch particles 8.1 8.3 8 6.4 5.8 Aggregated particle D50 (μm) 121 118 126 153 176 Cold water dispersion time (s) 45 43 49 76 93 D90 particle size (μm) after rehydration 88 84 96 164 201 Settling rate (%) after standing for 30 minutes 5.1 4.9 5.8 11.6 14.9 Number of aggregated particles with an equivalent diameter of not less than 150 μm (particles / field of view) after 5 min of rehydration. 1.8 1.6 2.3 6.9 9.4 Observation of rehydration under a 100x optical microscope Larger aggregated particles are less Larger aggregated particles are less A small number of aggregated particles are visible. Numerous aggregated particles are visible. Numerous dense, large particles are visible. As shown in Table 7, under the same amount of clarified fermentation broth added and the same conditioning time, when the blade tip linear velocity is 1.31–1.83 m / s, the mass ratio of wet agglomerates with an equivalent diameter of not less than 10 mm after conditioning is 3.6%–5.2%, the content of ungelatinized starch particles in the dried powder is 2.23–2.34 g / 100 g dry basis, the endothermic enthalpy of gelatinization of recovered starch particles is 8.0–8.3 J / g, the cold water dispersion time of the obtained powder is 43–49 s, the D90 particle size after rehydration is 84–96 μm, and the sedimentation rate after standing for 30 min is 4.9%–5.8%. Comparative Example 7-1: The blade rotation speed was increased to 80 r / min, and the blade tip linear velocity was 2.09 m / s; Comparative Example 7-2 increased the blade rotation speed to 90 r / min, and the blade tip linear velocity was 2.36 m / s; Both groups maintained the same amount of clarified fermentation broth added, conditioning time, airflow drying conditions, and post-treatment conditions. However, after conditioning, the proportion of wet agglomerates with an equivalent diameter of not less than 10 mm increased to 13.7% and 21.5%, respectively. The content of ungelatinized starch particles in the dried powder decreased to 1.71 g / 100 g dry basis and 1.48 g / 100 g dry basis, respectively. The endothermic enthalpy of gelatinization of recovered starch particles decreased to 6.4 J / g and 5.8 J / g, respectively. The cold water dispersion time was extended to 76 s and 93 s, respectively. After rehydration, the D90 particle size increased to 164 μm and 201 μm, respectively. The above results indicate that when the blade tip linear velocity exceeds 1.9 m / s, although the clarified fermentation broth can still be added to the protein wet phase, strong mechanical disturbance can easily cause the protein wet phase to form a dense wet mass with a higher proportion, and reduce the retention state of ungelatinized starch particles in the dried powder, resulting in prolonged cold water dispersion time of the powder, increased particle size after rehydration, and increased sedimentation rate. Therefore, the present invention limits the blade tip linear velocity during the protein wet phase conditioning stage to no more than 1.9 m / s, in order to ensure that the clarified fermentation broth is dispersed into the protein wet phase while reducing the damage to the ungelatinized starch particles and the loose structure of the wet phase during the conditioning process.

Claims

1. A process for wet fermentation extraction and airflow drying of peas, characterized in that, include: The sieved peas were soaked and fermented in the aqueous phase of Lactobacillus plantarum seed liquid to retain starch granules with polarized crosses in the fermented peas, thus obtaining fermented peas and soaking fermentation liquid. Fermented peas are crushed to separate the outer skin from the cotyledon surface and to crack the cotyledons, resulting in a crushed pulp containing skin fiber, protein particles and ungelatinized starch particles. The crushed pulp is centrifuged and screened, so that the bran fibers form an oversize layer on the inside of the screen, and the protein particles and ungelatinized starch particles enter the undersize pulp with the liquid phase. The slurry that passes through the sieve is sent to a horizontal screw centrifuge for solid-liquid separation to obtain a wet protein phase containing protein particles and ungelatinized starch particles; The fermented soybean broth was clarified to obtain a clarified fermented broth containing lactate, phytate, calcium ions and magnesium ions. After solid-liquid separation in a horizontal screw centrifuge, the clarified fermentation broth is added to the protein wet phase during the protein wet phase conditioning stage. The protein wet phase is then conditioned using a paddle stirring method with a blade tip linear velocity of no more than 1.9 m / s. This allows the clarified fermentation broth to enter the drying stage along with the protein wet phase, resulting in a conditioned protein wet phase. The conditioned protein wet phase is conveyed to the feed end of the airflow dryer via a screw conveyor. Before entering the airflow dryer tube, it is dispersed into wet granules by a needle-type dispersing mechanism. Then, it undergoes airflow drying, cooling, and granulation to obtain pea protein powder.

2. The pea wet fermentation extraction and airflow drying process as described in claim 1, characterized in that: The Lactobacillus plantarum mentioned is Lactobacillus plantarum Lp-HZ55, with accession number CCTCC No. M 20221778; During the fermentation process of soaking beans, the pH and titratable acidity (calculated as lactic acid) of the fermentation liquid are measured as the basis for judging the degree of acidification of the fermentation liquid. The proportion of fine pulp and the cross-shaped pattern of polarized light after crushing fermented peas were detected as criteria for judging the degree of pea lysis and the state of starch non-gelatinization. The fermentation endpoint of the peas was determined based on the degree of acidification, the degree of pyrolysis, and the ungelatinized state of the starch, and the fermented peas were separated from the fermentation liquid.

3. The pea wet fermentation extraction and airflow drying process as described in claim 1, characterized in that: After the fermented peas are separated from the fermentation liquid, the fermented peas are drained and then sent to the crushing process. The crushing process employs either compression crushing or disc crushing to separate the outer skin from the cotyledon surface and to fracture the cotyledons.

4. The pea wet fermentation extraction and airflow drying process as described in claim 1, characterized in that: The centrifugal sieving includes a stratification stage of the material on the screen and a continuous sieving stage; In the oversize layering stage, the crushed pulp is first fed into a centrifugal screen, so that the fiber is retained on the inside of the screen to form an oversize layer. During the continuous screening stage, the crushed pulp is fed into a centrifugal screen, allowing protein particles and ungelatinized starch particles to pass through the screen with the liquid phase and enter the slurry below the screen.

5. The pea wet fermentation extraction and airflow drying process as described in claim 1, characterized in that: The slurry under sieve is buffered and temporarily stored before entering the horizontal screw centrifuge, and is stirred by a paddle during the buffering process so that the protein particles and the ungelatinized starch particles enter the horizontal screw centrifuge together with the liquid phase.

6. The pea wet fermentation extraction and airflow drying process as described in claim 1, characterized in that: The main unit speed of the horizontal screw centrifuge is 3100-3300 r / min, the differential speed is 10-12 r / min, and the feed rate is 0.75-0.85 m³ / h.

7. The pea wet fermentation extraction and airflow drying process as described in claim 1, characterized in that: The fermented bean broth was sequentially subjected to coarse filtration and centrifugation for clarification to obtain the clarified fermented broth; Before adding the clarified fermentation broth to the protein wet phase, the levels of lactate, phytate, calcium ions, and magnesium ions in the clarified fermentation broth are detected, and the detected clarified fermentation broth is used to condition the protein wet phase obtained after horizontal screw centrifugation.

8. The pea wet fermentation extraction and airflow drying process as described in claim 1, characterized in that: The conditioning is carried out in a temporary storage tank equipped with double-layered blades; During conditioning, first start the paddle stirring, then add the clarified fermentation broth along the inner wall of the temporary storage tank to the protein wet phase, and continue to use the paddle stirring method to mix the clarified fermentation broth with the protein wet phase to obtain the conditioned protein wet phase.

9. The pea wet fermentation extraction and airflow drying process as described in claim 1, characterized in that: The needle-type dispersing mechanism is located between the screw conveyor discharge end and the airflow drying tube inlet, so that the conditioning protein wet phase is dispersed into wet granular material before entering the airflow drying tube, and then enters the airflow drying tube with the drying airflow.

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