A method for dry preparation of soy protein

Abstract

The application discloses a method for preparing soybean protein by dry method, and belongs to the technical field of plant protein extraction. The method comprises the following steps: (1) coarsely crushing soybean meal; (2) finely crushing the soybean meal by using an ultramicro grinder under the condition of controlling the rotating speed of a grading wheel; and (3) classifying the crushed material by using an air flow classifier for one time and two times to obtain fine components with high protein content. The method adopts pure dry physical treatment, does not need to use any chemical solvent or water, is green and environment-friendly, has small protein denaturation, good functional characteristics, and the highest protein content can reach 58.63%, and is suitable for high value-added applications in the fields of food and feed, etc. The method provides a feasible scheme for industrialized dry production of soybean protein, and also expands a new idea for the development of plant-based protein.

Description

Technical Field

[0001] This invention belongs to the field of plant protein extraction technology, specifically relating to a method for extracting soybean protein from soybean meal using a pure dry physical process. Specifically, it combines ultrafine grinding with dry separation technology to achieve efficient extraction and purification of soybean protein. Background Technology

[0002] Soybeans are one of the world's most traded agricultural products, and soybean meal is a major byproduct of soybean extraction and processing. Its primary use is as the most widely applied plant-based protein feed in my country. Soybean meal contains approximately 40% to 50% protein, making it a plant-based protein resource with significant development potential. However, current soybean protein extraction methods mostly employ wet processes, requiring large amounts of acid and alkaline solutions. This not only damages the natural structure and functional properties of the protein but also generates substantial amounts of wastewater, causing environmental pollution. Furthermore, the subsequent dehydration and drying steps are energy-intensive.

[0003] Ultrafine grinding can separate smaller protein particles (1-3 μm) from larger starch particles (approximately 20 μm) and cell wall fibers in soybean meal, while air classification can further enrich proteins based on differences in particle size and aerodynamic properties. However, the classifier rotation speed in ultrafine grinding and the process parameters of air classification directly affect the product particle size, yield, and protein content. Improper parameter control can easily lead to insufficient protein separation or excessively low yield. Therefore, optimizing the process parameters for dry preparation of soybean protein is crucial for improving the purity and yield of soybean protein.

[0004] Dry separation technology, especially ultrafine grinding combined with airflow classification, separates components based on differences in particle size, density, and shape through physical means. It offers advantages such as solvent-free operation, low energy consumption, and good preservation of the natural protein structure, and has shown promising application prospects in the field of plant protein enrichment in recent years. However, a mature process scheme and parameter optimization are still lacking for the systematic and efficient application of this technology to the extraction and enrichment of soybean protein. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a dry method for preparing soybean protein. This method is simple, environmentally friendly, produces minimal protein denaturation, and exhibits good functional properties. By optimizing the process parameters of ultrafine grinding and airflow classification, efficient enrichment of soybean protein can be achieved, resulting in high-purity, stable soybean protein.

[0006] This invention is achieved through the following technical solution: A method for dry preparation of soy protein, comprising the following steps: (1) Coarsely grind soybean meal (SM) to a particle size of 1-3 mm to obtain coarsely ground soybean meal powder (CCSMP). (2) The coarsely crushed soybean meal powder is fed into an ultra-fine pulverizer and ultra-finely pulverized at a grading wheel speed of 10,800~12,000 rpm to obtain mechanically pulverized soybean meal powder (MCSMP). (3) The material obtained in step (2) is passed through an air classifier and air classified once under the conditions of classifier wheel speed of 10,500~16,500 rpm, fan frequency of 45 Hz and secondary air opening of 1 / 2 to collect fine components (FF). (4) The fine fraction with the highest protein content obtained in step (3) is subjected to secondary airflow classification under the conditions of a classifier speed of 15,000~18,000 rpm, a fan frequency of 45 Hz, and a secondary air opening of 1 / 2, to further enrich the protein and obtain a fine fraction with a higher protein content.

[0007] Preferably, the speed of the grading wheel in step (2) is 12,000 rpm.

[0008] Preferably, the speed of the grading wheel in step (3) is 13,500 rpm.

[0009] Preferably, the speed of the grading wheel in step (4) is 16,500 rpm.

[0010] The method is carried out entirely under dry conditions, without the use of any solvents or water, and is a purely physical processing procedure. Attached Figure Description

[0011] Figure 1 This is a process flow diagram for preparing soybean protein using ultrafine grinding and airflow classification according to the present invention.

[0012] Figure 2 This is a graph showing the relationship between the average particle size, yield, and protein content of soybean meal powder after ultrafine grinding under different grading wheel speeds.

[0013] Figure 3 This is a graph showing the relationship between the average particle size, yield, and protein content of the fine components obtained after one airflow classification of different ultrafine pulverized samples and the rotational speed of the classifier.

[0014] Figure 4 This is a graph showing the relationship between the average particle size, yield, and protein content of the fine components obtained after secondary airflow classification, using the product from the primary classification as raw material, and the rotational speed of the classifier. Detailed Implementation

[0015] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0016] Example 1:

[0017] Soybean meal was coarsely pulverized to a particle size of 1-3 mm to obtain CCSMP. With a fixed feeding frequency of 5 Hz (approximately 2 kg / h), the CCSMP was fed into a CSM120-H ultrafine pulverizer, and the classifying wheel speed was set to 10,800 rpm for ultrafine pulverization to obtain mechanically pulverized soybean meal powder MC1. Subsequently, MC1 was fed into an FW120 air classifier, and the classifying wheel speed was set to 13,500 rpm, the fan frequency to 45 Hz, and the secondary air opening to 1 / 2 for primary air classification, collecting the fine component FF. 1-3 The protein content of this fine component is approximately 54.71%, D 50 The particle size was 11.1 μm, and the yield was 75.02%.

[0018] Example 2:

[0019] The steps of Example 1 were repeated, but the classifier speed in the ultrafine grinding stage was set to 12,000 rpm to obtain MC2. MC2 was then classified under the same airflow classification conditions (13,500 rpm, 45 Hz, 1 / 2 opening) to obtain the fine component FF. 1-3 The protein content reached 56.93%, D 50 The particle size was 9.02 μm, and the yield was 69.73%.

[0020] Example 3:

[0021] The steps of Example 2 were repeated, but the speed of the classifier wheel was increased to 16,500 rpm during the first airflow classification, while other conditions remained unchanged. The protein content of the resulting fine fraction was 55.78%, and the yield was 41.83%, indicating that excessively high speed may cause protein and non-protein components to aggregate and adhere, which is not conducive to protein enrichment.

[0022] Example 4:

[0023] The first-stage fraction FF obtained in Example 2 1-3 Using this as raw material, it is fed back into an FW120 air classifier. The classifier wheel speed is set to 16,500 rpm, the fan frequency to 45 Hz, and the secondary air opening to 1 / 2 for secondary air classification, collecting the fine component FF. 2-2 This component has a protein content as high as 58.63%, D 50 The particle size was 5.23 μm, but the yield was low at 21.24%.

[0024] The above embodiments demonstrate that by optimizing the process parameters of ultrafine grinding and airflow classification, the present invention can efficiently enrich soybean protein under dry conditions, obtain products with high protein content, and provide a green and efficient solution for the high-value utilization of soybean protein.

Claims

1. A method for dry preparation of soybean protein, characterized in that, The process includes the following steps: (1) coarsely grinding soybean meal to a particle size of 1-3 mm to obtain coarsely ground soybean meal powder; (2) feeding the coarsely ground soybean meal powder into an ultra-fine pulverizer and performing ultra-fine pulverization at a classifying wheel speed of 10,800-12,000 rpm to obtain mechanically ground soybean meal powder; (3) passing the material obtained in step (2) through an air classifier and performing primary air classification at a classifying wheel speed of 10,500-16,500 rpm, a fan frequency of 45 Hz, and a secondary air opening of 1 / 2 to collect fine components; (4) preferably selecting the primary air classification fine component with the highest protein content obtained in step (3) and performing secondary air classification at a classifying wheel speed of 15,000-18,000 rpm, a fan frequency of 45 Hz, and a secondary air opening of 1 / 2 to further enrich the protein.

2. The method according to claim 1, characterized in that: The preferred speed of the grading wheel in step (2) is 12,000 rpm.

3. The method according to claim 1, characterized in that: The preferred speed of the grading wheel in step (3) is 13,500 rpm.

4. The method according to claim 1, characterized in that: The preferred speed of the grading wheel in step (4) is 16,500 rpm.

5. The method according to claim 1, characterized in that: The method is carried out entirely under dry conditions, without the use of any solvents or water.

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