JPS6319144B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for removing seed coats from defatted soybeans.

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. Prior art methods for enriching soybean protein content have involved grinding defatted soybeans to some extent and then simply repeating the process, either dry or wet, to increase the soybean protein content.

The purpose of the present invention is to partially improve such a soybean enrichment method, and more specifically, instead of simply pulverizing defatted soybeans, the present invention first performs a first-stage pulverization to preserve as much of the seed coat as possible. A step of coarsely pulverizing the endosperm, a step of removing the seed coat portion, and a second step in which the coarsely pulverized endosperm is finely pulverized to the extent that the protein body is preserved to recover the protein body portion. This is a method for removing seed coats from soybean proteins.

Conventionally, to remove the seed coat, the defatted soybean is simply crushed appropriately and then the seed coat is separated by wind selection, etc., and the interaction between the seed coat and the endosperm, as well as the interaction between the protein body part and the carbohydrate part, is investigated. There is no concept of removing as much of the seed coat as possible from defatted soybeans by carrying out two-stage crushing in consideration of the above.

According to the invention, after the first stage of comminution, the seed coat part is removed in a relatively large size due to its elasticity. Of course, some of the seed coat is crushed to a certain extent and intervenes in the second stage of crushing, but even in this case, the seed coat is less likely to be crushed than the endosperm, and the mixed seed coat has a lubricating function due to its elasticity. Therefore, it also helps to prevent destruction of the protein body itself during the second stage of grinding. After the second stage of pulverization, the product obtained by air selection to collect a predetermined fraction is in a state in which carbohydrate moieties remain attached to the periphery of the protein body. The defatted soybean from which the seed coat has been removed by the method of the present invention can be further processed dryly or wetly or in a combination thereof to increase the soybean protein content.

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, such raw material defatted soybeans include NSI (Nitrogen Solubility).
Index) of 50 or more, particularly preferably 70 or more.

The present invention will be explained in more detail for each step as follows.

First, defatted soybeans are crushed and 70 to 90% of them have a particle size.
The thickness should be 800μm or less. If the particle size after pulverization is coarser than the above range, the endosperm portion will not be sufficiently pulverized and the difference in particle size from the soybean seed coat will be small, making it impossible to selectively remove the seed coat in the subsequent sieving operation. If the particle size after pulverization is smaller than the above range, the seed coat portion in the raw material will be pulverized too much and will have a particle size comparable to that derived from the protein portion, making it difficult to separate the two. For the purpose of crushing, impact crushing should be used to coarsely crush the endosperm while preserving the soybean seed coat, and specifically, a hammer mill, axial flow mill, rotary disc mill, etc. An example of this is an impact crushing device. The grinding conditions when using these devices vary depending on the model, but for example, in a rotary disk type mill, a peripheral speed of 30 to 60 m/sec is desirable.

The pulverized material obtained in this way is then opened.
Sieve through a 600 to 1000 μm sieve to remove large soybean seed coats.

The defatted soybeans obtained by the above treatment are further pulverized so that 70 to 95% of the defatted soybeans have a particle size of 30 μm or less. By pulverizing in this manner, the endosperm portion is appropriately pulverized into protein body units, while the seed coat portion remains with a relatively large particle size because it is difficult to be pulverized. It is important that the equipment used for pulverization preserves the protein body in the endosperm and pulverizes the seed coat in such a way that it is relatively difficult to crush it.
For this purpose, an impact crusher is used. Examples of impact crushers include hammer mills, axial flow mills, and rotary disc mills. 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.

The pulverized material obtained in this way is screened to determine the particle size.
Collect items smaller than 25-35 μm. The equipment used for the wind selection operation is preferably a dry air classifier, examples of which include a free-vortex air classifier and a forced air classifier. When classification is performed using these devices to separate particles with a particle size of 25 to 35 μm or less, defatted soybean flour is obtained in which non-protein particles such as fine soybean hulls have been substantially removed.

Examples of the invention are given below, in which all protein contents are based on dry weight.

Example 1 Defatted soybean (protein content 53.4%, NSI 84.5) 10Kg
Rotating disk type mill (free crusher M-2, Nara Kikai Co., Ltd.)
(manufactured by) at a processing rate of 60 kg/hour, 6000 rpm
It was crushed with Obtained defatted soybean powder (particle size 784μm
90.3%) is sieved through a sieve with an opening of 784 μm to remove the coarse soybean seed coat, and the soybean seed coat that passes through the sieve (yield 90.3%, protein content 56.0%) is passed through a rotary disc mill (Contraplex 250CW/Alpine). supplied to the main rotor at a rate of 120 kg/hour.
Grinding was carried out under the conditions of 11,900 rpm and a secondary rotor of 5,860 rpm.
Finely ground defatted soybean powder (particle size 30μm or less 80.0
%) using a forced air classifier (Multiplex 100MZR type/
(manufactured by Alpine) at an air volume of 44 m ² /hour (converted to atmospheric pressure) and 8000 rpm to separate the fine powder.
The obtained fine powder classification was 90.0% below 30 μm, the yield based on raw materials was 76.3%, and the protein content was 57.5%.
Contains virtually no soybean seed coat.

Example 2 Defatted soybean (protein content 52.1%, NSI93.9) 10Kg
Rotary disk type mill (free crusher M-2, Nara Kikai Co., Ltd.)
(made in Japan) at a processing rate of 51.4 kg/hour.
Milled at 6000 rpm. The resulting defatted soybean powder (particle size 784 μm or less, 88.5%) was sieved through a sieve with an opening of 680 μm to remove coarse soybean seed coats, and the portion that passed through the sieve (yield 85.0%, protein content 55.5%) was rotated. The powder was supplied to a disc mill (Contraplex 250CW, manufactured by Alpine) at a processing rate of 62.7 kg/hour, and pulverized under the conditions of a main rotor of 11,900 rpm and a secondary rotor of 5,860 rpm. Finely ground defatted soybean powder (particle size 30μm
below 93.3%) forced air classifier (Multiplex
100MZR model, manufactured by Alpine) at an air flow rate of 44 m ³ /hour (atmospheric pressure equivalent) and 8000 rpm, and at that time, the fine powder was separated. The resulting defatted soybean flour has 98.5% of its size of 30 μm or less, a yield based on raw materials of 82.6%, a protein content of 58.1%, and is substantially free of seed coat.

Reference Example This example is an example of an operation for increasing the protein content by processing the defatted soybean obtained according to the present invention from which the seed coat has been substantially removed.

The defatted soybeans obtained in Example 1 were placed in a diet mill (Aeroplex 200AS, manufactured by Alpine) at a processing amount of 10
It is supplied at a rate of kg/hour and pulverized at a pressure of 5 kg/cm ² . Next, this material is air-separated using a forced air classifier at an air flow rate of 37 m ³ /hour and 18,000 rpm to separate the coarse powder (98% below 20 μm, yield based on raw material)
57.4%, protein content 58.8%).

The coarse powder fraction obtained in the above treatment was fed to the diet mill at a processing rate of 20 kg/hour, and the pressure was increased to 5 kg/hour.
cm ² and then air-separated using the classifier at an air flow rate of 40 m ³ /hour and 15,000 rpm to separate the coarse powder (20 μm
Below 97%, yield based on raw materials 35.0%, protein content 64.5
%).

Furthermore, the coarse powder classification was processed into a jet mill with a processing amount of 10
The powder is supplied at a rate of 1 kg/hour, pulverized at a pressure of 5 kg/cm ² , and subjected to air selection at an air flow rate of 42 m ³ /hour and 13,000 rpm to separate the coarse powder portion. The resulting soybean powder is 20μm
The particle size distribution is below 97.0%, and the yield based on raw materials is 20.0%.
And the protein content is 68.1%.

Claims (1)

[Claims] 1. Shock crush defatted soybeans so that 70-90% of them have a particle size of 800 μm or less, separate 600-1000 μm or less using a sieve, and further 70-95% of the
A method for removing the seed coat of defatted soybeans, which comprises impact-pulverizing the seed coats of defatted soybeans to particles of 30 μm or less, and then separating particles with particle sizes of 25 to 35 μm or less by air selection.