A method for increasing the protein content of a sand particle gluten meal

Abstract

The application discloses a method for improving the protein content of sand-like wheat gluten, and belongs to the technical field of plant protein processing. The method first establishes a moisture gradient difference between the surface layer and the interior of the particles through one-time drying and static balance, and then performs annular airflow drying, so that the interior of the particles develops a micro-fissure network due to the thermal shrinkage difference between gluten and starch. Subsequently, the particles are subjected to multiple pressurization-holding-instantaneous pressure release cycle treatments under pressure changes, and the pressure difference between the gas inside and outside the fissures is used to selectively strip the loosened internal impurities. Finally, the impurities are separated through winnowing. The method is a physical treatment throughout, and can significantly improve the protein content of sand-like wheat gluten without substantially damaging the macroscopic morphology of the particles, and has the dual advantages of high product purity and good particle function.

Description

Technical Field

[0001] This application belongs to the field of plant protein processing technology, and in particular relates to a method for increasing the protein content of gluten. Background Technology

[0002] Gluten powder, also known as active gluten powder, is a powdered product made from wheat flour. After washing to remove water-soluble components such as starch, it is dried and pulverized. Its protein content (dry basis) is usually 75-85%. It has good viscoelasticity, film-forming properties and water absorption properties, and is widely used in flour quality improvement, aquatic feed binder and plant-based meat production.

[0003] Granulated wheat gluten is an important product form of wheat gluten. Unlike conventional powdered wheat gluten, granulated wheat gluten omits the grinding process during production, or directly produces granules with a particle size of 0.5-3mm from semi-dry gluten through granulation and sieving. This physical form gives it unique advantages in aquatic feed (especially high-end shrimp and crab feed) and pet food: the granular form slows down the hydration rate in water, providing more durable water resistance and binding properties, while reducing dust pollution and feed loss associated with powdered products. However, the physical form of granulated wheat gluten also presents a difficult technical challenge: limited protein content.

[0004] In conventional gluten production processes, the separation of gluten and starch mainly relies on centrifugation and multi-stage washing. While this process can efficiently remove surface-attached impurities that are free outside the gluten network, it is almost powerless against granular embedded starch and pentosans that are tightly wrapped in the particle core by the three-dimensional network of gluten protein. In the production of powdered products, the subsequent pulverization process can forcibly destroy the gluten network and expose these internal impurities. Although further separation is not possible, at least a homogeneous distribution of impurities is achieved, resulting in a relatively stable protein content.

[0005] Unlike conventional gluten production, granulated gluten undergoes no pulverization process to preserve its granule shape. This means that a large amount of starch and pentosans are locked inside the gluten particles, leading to two consequences: first, low protein content: the protein content of the granulated product is often only around 80%, which is insufficient to meet the high-protein requirements of high-end feeds; second, difficulty in modification: existing technologies utilize enzymes (such as cellulase and pentosanase) or chemical reagents to further increase the protein content of gluten, but these methods all require liquid-phase systems. Liquid-phase treatment of already formed granules not only destroys the particle shape but also requires secondary drying, resulting in extremely high energy consumption and low yield, making it uneconomical for industrial use. Patent CN102669419A discloses a production method for wheat gluten protein pellet feed and gravel-type feed. It adopts a process of drying, humidifying, pelleting, and drying. It utilizes the stickiness of wheat gluten powder semi-finished product when it comes into contact with water vapor. The material is forcibly agglomerated into clumps through mechanical extrusion. The role of high-pressure steam (0.5-0.7 MPa) is to gelatinize starch and increase viscosity, with the aim of making the pellets more compact and less prone to disintegration. However, it does not solve the problem of how to remove impurities encapsulated inside.

[0006] In summary, the core challenge of existing technologies lies in how to effectively remove non-protein impurities encapsulated within the particles while preserving their physical integrity, thereby substantially increasing the protein content of gluten powder. Summary of the Invention

[0007] The purpose of this application is to provide a method for increasing the protein content of gluten powder, so as to solve the technical problem in the existing production of gluten powder that the inability to break down the particles leads to the residue of non-protein impurities and low protein content.

[0008] To achieve the above objectives, the technical solution adopted in this application is: to provide a method for increasing the protein content of gluten, specifically including the following steps: (i) Gradient control of moisture: After drying the wet gluten once, let it stand to obtain pre-dried material. Then, dry the pre-dried material a second time to obtain semi-finished granules. (ii) Pulse processing: The semi-finished particles are loaded into a sealed pressure-resistant container, the door is closed, compressed air is introduced to increase the pressure, and the quick exhaust valve is opened. During the pressure change, the internal gas of the semi-finished particles expands and is released. The pulse processing is repeated to obtain the semi-finished product. The semi-finished product is then processed to obtain the finished gluten powder.

[0009] In one embodiment, The moisture content of the wet gluten in step (1) is 50-70%.

[0010] In one embodiment, The temperature for the first drying step (1) is 60-80 ℃, and the temperature for the resting step is 15-30 ℃, with a time of 20-40 min.

[0011] In one embodiment, The surface moisture content of the pre-dried material in step (1) is 20-25%.

[0012] In one embodiment, The secondary drying in step (1) is carried out at a temperature of 80-100 ℃ for 10-30 min.

[0013] In one embodiment, The surface moisture content of the semi-finished granules in step (1) is 5-15%.

[0014] In one embodiment, The pressure for pressurization in step (ii) is 0.45-0.50 MPa, and the pressure holding time is 20-25 s.

[0015] In one embodiment, Step (ii) The time to open the quick-release valve is 0.3 s.

[0016] In one embodiment, The number of times the repeated pulse processing is described in step (ii) is three.

[0017] In one embodiment, The specific steps of the post-processing described in step (II) are as follows: the semi-finished product is sent to the air classifier through a vibrating screen, and the air speed is controlled at 5 m / s to remove the fine powder and debris blown off the surface.

[0018] This application provides a method for increasing the protein content of wheat gluten, which has the following advantages compared with the prior art: 1. This application is based on selective peeling of cracks induced by thermal shrinkage difference and gas explosion. During the drying process, due to the significant difference in thermal shrinkage coefficients between gluten protein and residual starch, a large number of crack networks are generated inside the particles. At this time, the gluten protein network becomes more rigid and less binding due to partial thermal denaturation, while the starch particles become loose due to water loss and shrinkage. High-pressure gas penetrates into the particle interior along these micro-cracks. When the pressure is released instantaneously, the high-pressure gas expands rapidly and generates a micro-explosion effect. The stress generated by this micro-explosion effect can blow the loose starch and pentosan particles from the cracks to the particle surface, while the continuous phase gluten protein skeleton with high elasticity and toughness is preserved. 2. Unlike the forced crushing of pulverizing or grinding, the physical action of this invention does not macroscopically destroy the overall structure of the particles. Therefore, the processed product still meets the requirements of sandy gluten powder for particle size (0.5-3 mm) and morphology, and retains its application advantages as an aquatic feed ingredient. 3. This process is rich in content and does not involve the addition of any chemical reagents. It only uses compressed air as the working medium, and there is no wastewater or exhaust gas emission. The core equipment consists of conventional chemical pressure vessels and valves. The modification cost is low, the operation is highly flexible, and it can be seamlessly integrated with existing gluten powder production lines. Detailed Implementation

[0019] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, this application will be further described in detail. It should be understood that the specific embodiments described herein are only for explaining this application and are not intended to limit this application.

[0020] Performance testing methods: Protein content (dry basis): determined according to the Kjeldahl method in GB 5009.5-2016 "National Food Safety Standard - Determination of Protein in Food", with a conversion factor of 5.7; Particle integrity rate: Take 100 g of finished product, place it on a 2.0 mm standard sieve, and vibrate it on a vibrating sieve for 3 minutes with an amplitude of 1.5 mm. Calculate the percentage of the mass of the material on the sieve to the total mass of the sample. Water absorption rate: determined according to the method in GB / T 21924-2008 "Vitamin Gluten".

[0021] Example 1 A method for increasing the protein content of gluten powder specifically includes the following steps: (I) Gradient control of moisture content: 100 kg of wet gluten with a moisture content of 60% was placed in a 70 ℃ hot air circulating oven for a first drying time of 30 min to reduce the moisture content to 33%. It was then removed and placed in a clean environment at 25 ℃ for 30 min to obtain pre-dried material. The surface moisture content was measured to be 22% and the internal moisture content to be 32%. The pre-dried material was then sent to a ring airflow dryer for a second drying. The hot air temperature was set at 90 ℃ and the drying time was 20 min to obtain semi-finished granules. The surface moisture content was measured to be 10.2%. (II) Pulse treatment: The semi-finished granules are loaded into a sealed pressure-resistant container, the door is closed, compressed air is introduced to increase the pressure to 0.45 MPa, and the pressure is maintained for 25 s. Then the quick discharge valve is opened for 0.3 s. During the pressure change, the material undergoes internal gas expansion and release. The pulse treatment cycle is repeated three times to obtain the semi-finished product. The semi-finished product is sent to an air classifier through a vibrating screen. The air speed is controlled at 5 m / s to remove the fine powder and debris blown off the surface, and the finished granulated gluten powder is obtained. The protein content (dry basis) is measured to be 88.5%, the particle integrity is 95.2%, and the water absorption rate is 158%.

[0022] Example 2 The difference between this embodiment and Example 1 is that the drying temperature is 60 ℃, while the rest of the operation is the same, and the finished product granular gluten powder is obtained; the protein content (dry basis) is 85.2%, the particle integrity is 96.8%, and the water absorption rate is 162%.

[0023] Example 3 The difference between this embodiment and Example 1 is that the drying temperature is 80 ℃, while the rest of the operation is the same, and the finished product granulated gluten powder is obtained; the protein content (dry basis) is 87.8%, the particle integrity is 92.0%, and the water absorption rate is 152%.

[0024] Example 4 The difference between this embodiment and Example 1 is that the secondary drying temperature is 80 ℃, while the other operations are the same, and the finished product, granulated gluten powder, is obtained. The protein content (dry basis) is 86.3%, the particle integrity is 95.8%, and the water absorption rate is 161%.

[0025] Example 5 The difference between this embodiment and Embodiment 1 is that the secondary drying temperature is 100 ℃, while the other operations are the same, and the finished product, granulated gluten powder, is obtained. The protein content (dry basis) is 89.1%, the particle integrity is 90.5%, and the water absorption rate is 146%.

[0026] Example 6 The difference between this embodiment and Embodiment 1 is that the pulse treatment pressure is 0.50 MPa, while the other operations are the same, and the finished product, granulated gluten powder, is obtained. The protein content (dry basis) is measured to be 89.2%, the particle integrity is 92.8%, and the water absorption rate is 154%.

[0027] Example 7 The difference between this embodiment and Embodiment 1 is that the holding time of the pulse treatment is 20 s, while the other operations are the same, and the finished product gluten powder is obtained; the protein content (dry basis) is measured to be 87.3%, the particle integrity is 95.5%, and the water absorption rate is 157%.

[0028] Example 8 The difference between this embodiment and Example 1 is that the standing temperature is 15 ℃ and the time is 40 min, while the rest of the operation is the same, and the finished product gluten powder is obtained; the protein content (dry basis) is 87.5%, the particle integrity is 95.8%, and the water absorption rate is 160%.

[0029] Example 9 The difference between this embodiment and Example 1 is that the standing temperature is 30 ℃ and the time is 20 min, while the rest of the operation is the same, and the finished product granular gluten powder is obtained; the protein content (dry basis) is 86.8%, the particle integrity is 93.5%, and the water absorption rate is 155%.

[0030] Comparative Example 1 The difference between this embodiment and Embodiment 1 is that the pulse treatment pressure was adjusted to 0.30 MPa, the holding time was 15 s, and the number of cycles was two. The other operations were the same, and the finished product, granulated gluten powder, was obtained. The protein content (dry basis) was measured to be 83.7%, the particle integrity was 97.5%, and the water absorption rate was 165%.

[0031] Comparative Example 2 The difference between this embodiment and Embodiment 1 is that the pulse treatment pressure was adjusted to 0.60 MPa, the holding time was 45 s, and the number of cycles was four. The other operations were the same, and the finished product, granulated gluten powder, was obtained. The protein content (dry basis) was measured to be 89.8%, the particle integrity was 88.3%, and the water absorption rate was 150%.

[0032] Comparative Example 3 The difference between this embodiment and Embodiment 1 is that the pulse treatment pressure was adjusted to 0.50 MPa, the holding time was 30 s, and the number of cycles was three. The other operations were the same, and the finished product, granulated gluten powder, was obtained. The protein content (dry basis) was measured to be 88.9%, the particle integrity was 93.5%, and the water absorption rate was 155%.

[0033] As can be seen from Examples 1, 6-7, and Comparative Examples 1-3, there is an optimal range for pressure parameters. If the pressure is too low, the gas penetration depth is limited, and the protein content is only increased by 3.1 percentage points compared to Comparative Example 4. If the pressure is too high, although the protein content is as high as 89.8%, the particle integrity rate drops to 88.3%, indicating that excessive expansion stress begins to tear the continuous phase rib skeleton and damage the product morphology. The parameters of Examples 1 and 6-7 achieve the best balance between product purity and morphological integrity.

[0034] Comparative Example 4 The difference between this embodiment and Embodiment 1 is that the wet gluten raw material is directly fed into an annular airflow dryer (90 ℃, dried to 10% moisture content), and then subjected to conventional sieving to obtain the finished granulated gluten powder; the protein content (dry basis) was measured to be 80.6%, the particle integrity was 98.0%, and the water absorption rate was 168%.

[0035] Compared with the conventional process of Comparative Example 1, the protein content (dry basis) of Example 1 increased from 80.6% to 88.5%, an increase of 7.9 percentage points. This demonstrates that the low-pressure pulsed airflow penetration and instantaneous back pressure release technology can effectively overcome the encapsulation and binding of gluten protein and selectively remove embedded starch impurities that cannot be reached by conventional washing.

[0036] Comparative Example 5 The difference between this embodiment and Embodiment 1 is that the material after the first drying is not allowed to stand, but is directly dried a second time to obtain the finished grain gluten powder; the protein content (dry basis) was measured to be 82.2%, the particle integrity was 96.8%, and the water absorption rate was 163%.

[0037] As can be seen from Examples 1, 8-9, and Comparative Example 5, the process of Comparative Example 5 lacks surface shrinkage stress, resulting in poor development of the internal crack network of particles, making it difficult for high-pressure gas to penetrate, and the protein increase is extremely small, only 1.6 percentage points.

[0038] This application provides a method for increasing the protein content of gluten powder, comprising the following steps: (I) Gradient moisture control: After drying wet gluten once, it is allowed to stand to obtain pre-dried material, and the pre-dried material is dried a second time to obtain semi-finished granules; (II) Pulse treatment: The semi-finished granules are loaded into a sealed pressure-resistant container, the door is closed, compressed air is introduced to increase the pressure, and the quick exhaust valve is opened. During the pressure change, the internal gas of the semi-finished granules expands and is released. The pulse treatment is repeated to obtain the semi-finished product; the semi-finished product is then post-processed to obtain finished gluten powder; the method first involves... A moisture gradient difference between the surface and interior of the granules is established through a drying and settling equilibrium process. Then, annular airflow drying is performed, causing the granules to develop a micro-crack network due to the difference in thermal shrinkage between gluten protein and starch. Subsequently, the granules undergo multiple pressurization-holding-instantaneous depressurization cycles under pressure changes, using the pressure difference between the inside and outside of the cracks to selectively remove loosened internal impurities. Finally, the impurities are separated by air classification. This method is a physical process throughout, which can increase the protein content (dry basis) of gluten powder from about 80% to over 88% without significantly damaging the macroscopic morphology of the granules. It has the dual advantages of high product purity and intact granule function.

[0039] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0040] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for increasing the protein content of wheat gluten, characterized in that, Specifically, the following steps are included: (i) Gradient control of moisture: After drying the wet gluten once, let it stand to obtain pre-dried material. Then, dry the pre-dried material a second time to obtain semi-finished granules. (ii) Pulse processing: The semi-finished particles are loaded into a sealed pressure-resistant container, the door is closed, compressed air is introduced to increase the pressure, and the quick exhaust valve is opened. During the pressure change, the internal gas of the semi-finished particles expands and is released. The pulse processing is repeated to obtain the semi-finished product. The semi-finished product is then processed to obtain the finished gluten powder.

2. The method for increasing the protein content of gluten flour according to claim 1, characterized in that, The moisture content of the wet gluten in step (1) is 50-70%.

3. The method for increasing the protein content of gluten flour according to claim 1, characterized in that, The temperature for the first drying step (1) is 60-80 ℃, and the temperature for the resting step is 15-30 ℃, with a time of 20-40 min.

4. The method for increasing the protein content of gluten flour according to claim 1, characterized in that, The surface moisture content of the pre-dried material in step (1) is 20-25%.

5. The method for increasing the protein content of gluten flour according to claim 1, characterized in that, The secondary drying in step (1) is carried out at a temperature of 80-100 ℃ for 10-30 min.

6. The method for increasing the protein content of gluten flour according to claim 1, characterized in that, The surface moisture content of the semi-finished granules in step (1) is 5-15%.

7. The method for increasing the protein content of gluten flour according to claim 1, characterized in that, The pressure for pressurization in step (ii) is 0.45-0.50 MPa, and the pressure holding time is 20-25 s.

8. The method for increasing the protein content of gluten flour according to claim 1, characterized in that, Step (ii) The time to open the quick-release valve is 0.3 s.

9. The method for increasing the protein content of gluten flour according to claim 1, characterized in that, The number of times the repeated pulse processing is described in step (ii) is three.

10. A method for increasing the protein content of gluten flour according to claim 1, characterized in that, The specific steps of the post-processing described in step (II) are as follows: the semi-finished product is sent to the air classifier through a vibrating screen, and the air speed is controlled at 5 m / s to remove the fine powder and debris blown off the surface.