Soy protein concentrate technology

Soy protein concentrate production line

Soy protein concentrate (SPC) is a protein concentrate made from soybeanssoybeanAs a raw material, through processing techniques such as crushing, peeling, extraction, separation, washing, and drying, the oil and low molecular weight soluble non protein components (mainly soluble sugars, ash content, etc.) in soybeans are removedprolaminA soy protein product containing 65% (dry basis) or more protein (N × 6.25) is produced after mixing with various odor substances.

Using low-temperature meal as raw material, the protein content is increased to 65% -70% by removing soluble sugars, ash, and other soluble trace components from low-temperature meal. Production process: Ethanol washing method.

Production process of soy protein concentrate:

Soybean cleaning and low-temperature pressing process

1. Cleaning process:

In order to obtain high-quality oil, it is necessary to clean the raw materials from the warehouse to remove secondary seeds, bad seeds, and other impurities in the raw materials. The separated parts, such as secondary seeds and bad seeds, can be mixed with the separated skin parts for use as raw materials in boilers or pressed separately into feed oil or industrial oil.
This process uses equipment such as permanent magnet tubes, specific gravity stone removal machines, and vibrating cleaning screens to remove sediment, stones, tiles, metals, and other impurities, avoiding strong friction that can cause greater damage to the equipment and extending its service life. Clean up impurities such as stems, leaves, bark, artemisia, hemp rope, etc., to avoid darkening the color of the crude oil, increasing sediment, and increasing refining consumption. Excessive impurities in cake and meal can reduce their utility value. If impurities occupy a certain volume, it can also increase the burden on equipment. At the same time, impurities such as artemisia and hemp fibers in oil can easily wrap around the rotating shaft of equipment, affecting process efficiency, increasing power consumption, and even blocking the import and export of equipment, causing production accidents and equipment failures.

The impurity content index after cleaning should be less than 0.5%, and the useful oil content index in the cleaned waste material should be less than 1.5%.

2. Grading: Use a grading sieve to separate immature particles, moldy particles, broken particles, and other imperfect particles, which can be used to produce secondary oil and sold separately.

3 Drying/Cooling: A hot air flow dryer can be used for drying equipment. After drying, the moisture content should be controlled between 5% and 6%. Then quickly use cold air to lower the temperature of the oil particles to below 40 ℃.
4. Crushing/Peeling: The crusher can be a toothed roller crusher, with the purpose of peeling off the outer skin. After crushing, the outer skin is sucked out using a wind separator or a suction flat screen.
5 low temperatureoil extraction，The pressing efficiency of the oil press and the stability of the equipment are the key factors in the oil pressing process. Using a cold oil press for pressing,It has the characteristic of low-temperature pressing, and the obtained oil has a rich aroma.

Oil puffing machines can also be used, and the resulting puffing material has the characteristics of low temperature, large volume, and easy leaching.

6. Crushing of Bean Cake

Low temperature leaching section of soybean cake

Using soybean cake as raw material and n-pentane as leaching solvent for defatting, wet meal is obtained; Wet soybean meal enters the distillation line for vacuum low-temperature desolvation to obtain low-temperature soybean meal. The leaching temperature is 15-35 ℃, the leaching time is 20-35 minutes, and the leaching frequency is 3 times. The residual oil rate of soybean meal is reduced to below 1%; The vacuum degree for desolvation of wet soybean meal is 73kPa~86kPa, the desolvation temperature is 40-60 ℃, and the desolvation time is 0.5h~1h. The residual oil rate of the low-temperature soybean meal produced can reach below 1%, the residual solvent is below 200mg/kg, and the NSI value of soybean meal protein exceeds 80%.

Low temperature soybean meal to concentrate protein section

The soluble protein in low denatured defatted soybean meal (powder) can dissolve in water, but cannot dissolve in ethanol, and the solubility of soluble protein is the lowest when the ethanol concentration is 50% -60% (volume fraction). On the contrary, ethanol affects the oligosaccharides in soybean meal (powder). Some odor components and pigments have good solubility. Therefore, it is possible to choose an appropriate concentration of ethanol solution to treat defatted soybean meal (powder), and then separate (and recover ethanol) and dry it to obtain soy protein concentrate with good color and aroma. And this method of production results in less protein loss. However, due to the action of ethanol, protein denaturation is severe, and the nitrogen solubility index of the product is generally below 10%; There is still 0.25% -1.0% (volume fraction) of ethanol remaining in the final product, which is difficult to remove, thus limiting the scope of product use to a certain extent.

After being crushed to a fineness of 50-100 mesh by a hammer mill, the low denatured defatted soybean meal is sent into the leaching tank by a buried scraper conveyor. Simultaneously, pump 60% -65% (volume fraction) ethanol solution from the dilute ethanol tank into the leaching tank, so that the mass ratio of soybean meal powder to ethanol solution is 1:7. Multiple leaching tanks can be equipped for alternating use. Stir thoroughly and soak at 50 degrees for 30 minutes. At this point, most of the soluble sugars, ash content, and some trace components in the soybean meal powder will dissolve in the ethanol solution. After a leaching process, the ethanol solution is extracted from the high-level liquid outlet pipe on the tank using a diaphragm pump and sent to the distillation kettle for ethanol recovery.

To obtain products with light color and less odor, use a pump to80%-90%Ethanol with a volume fraction is sent from the concentrated ethanol storage tank to the leaching tank for secondary leaching. The soaking temperature is 70 degrees Celsius, and the stirring soaking time is 30 minutes. After the second leaching is completed, the ethanol solution is discharged from the high-level liquid outlet pipe on the tank to the dilute ethanol storage tank. The ethanol leaching solution can be used for the first leaching.

The slurry material after secondary leaching is discharged from the discharge port of the leaching tank and sent to the horizontal spiral sedimentation separator by a diaphragm pump. The separated ethanol extract flows into the distillation kettle for ethanol recovery. Two distillation kettles are also equipped for alternate use.

The material discharged from the horizontal spiral sedimentation separator has a moisture content of approximately70%After being transferred into the vacuum dryer, saturated steam with a pressure of 0.4 MPa is introduced into the jacket of the cylinder wall under the flipping of the continuous screw belt mixer, indirectly heating the material. The dryer is evacuated by a vacuum device to achieve an absolute pressure of 21.3-7.9KPa (vacuum degree of 80-93.3KPa). The maximum heating temperature of the material shall not exceed 80 ℃, the drying time shall be 1 hour, and the moisture content shall be below 7%. After unloading, soybean protein concentrate is crushed by a turbine crusher. The product yield is about 50% of low denatured defatted soybean meal.

Ethanol and water vapor extracted from the vacuum dryer are condensed into liquid by the condenser and then flow into the distillation kettle for ethanol recovery. The ethanol vapor from the distillation kettle is recovered by the condenser and injected into the dilute ethanol storage tank. Pump dilute ethanol into the high-level tank and feed it into the distillation tower, with a distillation concentration of80-95%Ethanol with a volume fraction for recycling. The concentrated slurry released from the distillation kettle, also known as soybean oligosaccharides, can be used as feed and refined as a basic raw material for functional foods.

It is worth noting that although the recovered ethanol is colorless and transparent, it containsIt has a strange odor and is difficult to separate. Gas chromatography analysis shows that the recovered ethanol can be detected10-15Impurities. To remove the odor components from the recovered ethanol, the following method can be used for efficient separation.

Dilute a portion or all of the recovered ethanol with water to achieve ethanol concentration40%(Extraction is carried out below (volume and fraction), with tower A being a water extraction evaporation tower (filling tower), and tower B being an ethanol recovery tower (filling tower or shed tower can be used). The tower can be heated using a distiller or by blowing steam directly into it.

Ethanol recovery containing odor components: from the supply port1Enter the upper part of the separation section of tower A, and extract water from the oil separator installed in the upper part of the distillation section, diluting ethanol to below 40% (volume fraction). At this point, the temperature of the extracted water and oil-water separator is heated to 80-95 ℃. Once the recovered ethanol is diluted, a portion of the odorous components, i.e. oil that is insoluble in water, are separated into layers and separated by the oil separator6Exclude from the system. The diluted recovered ethanol flows into the separation section, where the off odor component is separated as a low boiling point component. At the same time as the ethanol aqueous solution flows in, it becomes the discharged liquid from tank A with improved purity, which is supplied through a conduit for azeotropic distillation in tower B to become refined ethanol for circulation. The odor components separated in the separation section rise with ethanol vapor and come into convective contact with extraction water in distillation section 4. Under this concentration condition, ethanol with lower volatility is selectively absorbed by water. Under reflux conditions, the concentration section 3 concentrates the distillate to the degree of azeotropic composition with ethanol. Thus, the lowest boiling odor component and ethanol are simultaneously discharged from the system as distillate and removed. In addition, in water with a boiling point higher than ethanol, the odor components are insoluble and stratify in separator 6, removing the oil layer from the system. For the recovery of ethanol from raw materials, a difference of 5% or less is recommended based on the amount of ethanol used as the standard. The reflux ratio is 5-50. A higher reflux ratio is more ideal.

BThe tower effluent contains a small amount of high boiling point impurities, but there is no noticeable odor. Add refined ethanol to the recovered ethanol mentioned above, which can be used as a raw material and incorporated into the extraction solution for recycling

Quality standard for soy protein obtained (feed grade)

1) Protein content (N * 6.25): ≥ 65% (dry basis)

2） 水分 ：7-9%

3) Fat:<0.8%

4) Particle size: 50 mesh (90% pass)

Quality standard for soy protein obtained (food grade)

1) Color: milky white, light yellow

2) Odor: The inherent odor of concentrated protein, with no other odors.

3) Protein content (N * 6.25): ≥ 65%

4） 水分 ：7-9%

5) Fat:<0.8%

6) Ash content:<6.0%

7) Required total fiber content:<4%

8 ） NSI: 5 - 10%

9) Particle size: 100 mesh (90% pass)