JPS6319145B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved dry method for enriching soybean protein.

Defatted soybeans have a high protein content of 45 to 50% and are widely used in feed and food, but with the recent spread of processed foods, soybean flour with a particularly high protein content is desired. In order to obtain such high-protein soybean flour, the protein content is increased by starting from defatted soybeans and applying various operations. Defatted soybeans themselves consist of a seed coat and an endosperm, and the endosperm contains a high protein content portion called the protein body bound by a carbohydrate portion rich in fiber. In prior art methods for enriching soybean protein content, defatted soybeans are pulverized to some extent and then the process is simply repeated, either dry or wet, to increase the soybean protein content.

As a result of various studies, the present inventors purposefully carried out the above-mentioned crushing operation based on the relationship between the crushing operation (including classification) intended to increase the soybean protein content of defatted soybeans and the botanical composition of soybeans. As a result of consideration, we have completed the present invention.

That is, according to the present invention, when defatted soybeans are pulverized, pulverization for recovering the protein body of soybeans and pulverization for increasing the protein content in the thus obtained recovered product are physically performed. The starting point is the technological recognition that the characteristics should be completely different. More specifically, in the first step of the present invention, defatted soybeans are crushed into particles with a particle size of 30 μm.
The following should be 70 to 95% and the particle size should be 25 to 25% by classification.
This method involves the process of separating the soybeans with a diameter of 35 μm or less, and in this case, the grinding process involves removing the seed coat from the defatted soybean and mechanically destroying the endosperm to cleave the protein body part from the carbohydrate part in the endosperm. This is an important objective, and for this purpose it is essential to carry out impact crushing. On the other hand, the second step in the present invention is to scrape off the adhering carbohydrates from the protein body particles collected in the second step, around which carbohydrate moieties remain attached, mainly by friction between the protein body particles. is an important objective, and for this purpose it is important to perform a fluid energy mill process. Of course, the carbohydrate portion that could not be pulverized in the first step can be easily pulverized to approximately 5 μm or less in particle size through this pulverization.

As used herein, "defatted soybeans" may include not only soybeans from which soybean oil has been extracted by ordinary solvent treatment, but also soybeans from which soybean oil has been extracted by cold pressing. In addition, this defatted soybean is NSI
(Nitrogen Solubility Index) is 50 or more, especially 70
The above are preferred.

In carrying out the method of the present invention, first of all, defatted soybeans are ground to a particle size of 70 to 95% of 30 μm or less.
By pulverizing in this manner, the endosperm portion is appropriately pulverized into protein body units. It is important that the equipment used for crushing preserves the protein body in the endosperm, and for this purpose an impact type crusher is used. Specific examples of such types of crushers include hammer mills, axial flow mills, rotary disk mills, and the like. The grinding conditions are not constant depending on the type of mill, but for example, in the case of a rotary disk type mill, a circumferential speed of 100 to 250 m/sec is desirable.

If the raw material is defatted soybeans containing a large amount of soybean seed coat, the raw material is crushed in advance using an impact crusher to make 70 to 90% of the particles have a particle size of 800 μm or less, and then passed through a sieve with an opening of 600 to 1000 μm. It is preferable for the subsequent operation to use a sieve to remove the part of the soybean seed coat that has a large particle size.

The pulverized product thus obtained is then classified. The device used for the classification operation is preferably a dry air classifier, examples of which include a free swirl type air classifier and a forced air classifier. Classification is performed using these devices to separate particles with particle sizes of 25 to 35 μm or less, and remove non-protein particles such as fine soybean seed coats.

Next, the defatted soybean powder mainly composed of protein bodies obtained by the above treatment is pulverized to a particle size of 70 to 95% of 20 μm or less. If the particle size after pulverization is coarser than the above range, the carbohydrate moiety adhering to the protein body cannot be completely removed, and the carbohydrate moiety with a large particle size also remains without being pulverized. Furthermore, if the particle size after pulverization is too fine, the protein body will be pulverized, resulting in excessive mixing of the protein-rich portion and the carbohydrate portion, making it impossible to separate the two.

The best pulverizing means to use is a pulverizer that has both a pulverizing action and an abrasive action that can scrape off carbohydrates attached around the protein body and make it finer. , a fluid energy mill such as a jet-o-mizer mill is used. The grinding conditions when using these devices vary depending on the type of machine, but for example, in the case of a jet mill, a pressure of 3 to 7 kg/cm ² is preferred.

The thus obtained pulverized product is classified, and a fraction having a particle size of 5 μm or more in 80% or more is separated. This treatment allows the removal of fine carbohydrate fractions resulting from grinding. If desired, defatted soybean powder with even higher protein content can be obtained by repeating the above-described crushing and classification operations.
The degree of pulverization at this time may be the same as the degree of pulverization described above. Regarding classification, it is desirable to set a cut point smaller than the size of the protein body in the classification before the final classification operation, and to set a cut point close to the size of the protein body in the final classification operation.

By incorporating the process of the present invention into the conventional dry process, defatted soybean flour can be obtained with significantly higher yields and a higher protein content than could have been expected from the prior art.

Next, the present invention will be explained by examples. In the examples, protein content is expressed as % based on dry weight.

Example 1 8.5 kg of defatted soybeans (protein content 55.5%) was supplied to a rotating disc mill (Contraplex 250CW, manufactured by Alpine) at a processing rate of 62.7 kg/hour, with the main rotor at 11,900 rpm and the secondary rotor at 5,860 rpm. It was crushed with Finely ground defatted soybean powder (particle size 30μm
Using a forced air classifier (Model Multiplex 100MZR, manufactured by Alpine) at an air volume of 44 m ³ /hour (converted to atmospheric pressure) and 8000 rpm, 8.3 kg of fine powder (less than 30 μm) was separated.
98.5%, protein content 58.1%).

The fine powder section was processed using a jet mill (Aeroplex).
200AS, manufactured by Alpine) at a processing rate of 8.7 kg/hour and pulverized at a pressure of 5 kg/cm ² . Next, this material is subjected to air separation using the above-mentioned classifier at an air flow rate of 37 m ³ /hour and 18,000 rpm to separate 6.7 kg of coarse powder. The soybean powder thus obtained has a size of 95% below 20 μm and a protein content of 58.8%.

Example 2 This example shows the production of high-protein defatted soybean powder by an all-dry method using the method of the invention as a part of its structure.

Defatted soybeans (protein content 53.4%, NSI 84.5) were processed using a rotary disc mill (free crusher M-2, manufactured by Nara Kikai Co., Ltd.)
The powder was supplied at a processing rate of 60 kg/hour and pulverized at 6000 rpm. Obtained defatted soybean powder (particle size 784μm or less)
90.3%) was sieved through a sieve with an opening of 784 μm to remove coarse soybean seed coat.

9 kg of the material that passed through the sieve (protein content 56.0%) was transferred to a rotary disk mill (Contraplex 250CW,
(manufactured by Alpine) at a processing rate of 120 kg/hour, main rotor 11900 rpm and slave rotor 5860 rpm.
It was crushed under the following conditions. Finely pulverized defatted soybean powder (84.0% particle size of 30 μm or less) was subjected to air separation using a forced air classifier (Multiplex 100MZR model, manufactured by Alpine) at an air volume of 44 m ³ /hour (atmospheric pressure equivalent) and 8000 rpm to form a fine powder. Separate 7.6Kg. (30μm or less
93.0%, protein content 57.5%).

The fine powder section was processed using a jet mill (Aeroplex).
200AS, manufactured by Alpine) at a processing rate of 10 kg/hour and pulverized at a pressure of 5 kg/cm ² . Next, this material is subjected to air separation using the above-mentioned classifier at an air flow rate of 37 m ³ /hour and 18,000 rpm to separate 5.7 kg of coarse powder (95.0% below 20 μm, protein content 58.8%).

The coarse powder fraction obtained in the above treatment was fed to the above-mentioned diet mill at a processing rate of 20 kg/hour, and the pressure was 5 kg/m ²
The air volume is 40m ³ /hour,
Perform wind selection at 15,000 rpm and separate 3.5 kg of coarse powder (97% below 20 μm, protein content 64.5%). Furthermore, the coarse powder classification was re-processed into a jet mill with a processing amount of 10
Supplied at a rate of Kg/hour, crushed at a pressure of 5Kg/cm ² and air volume
Wind selection is carried out under the conditions of 42 m ³ /hour and 13000 rpm, and 2 kg of coarse powder is separated. The final product, soybean powder, has a particle diameter of 97.0% below 20μm and a protein content of 68.1%.
%.

Claims (1)

[Claims] 1. In order to enrich the protein content of defatted soybeans, the defatted soybeans are pulverized by impact to a particle size of 30 μm or less.
95% and a step of separating particles with a particle size of 25 to 35 μm or less by classification, and a fluid energy mill treatment of the sampled sections to reduce particles of 20 μm or less to 80 to 95%.
% finely pulverized and classified to have a particle size of 5 μm or more (80%)
A method for enriching the protein content of defatted soybeans, characterized by including a combination with a step of fractionating the above classifications.