Method for preparing fermentation concentrated protein by using low-temperature meal

Abstract

The invention relates to the technical field of fermented protein feed processing, in particular to a method for preparing fermented protein concentrate by using low-temperature meal, which comprises the following steps: adding the low-temperature meal, fermentation extraction water and lactobacillus acidophilus into a fermentation extraction tank, adjusting the pH value, and performing liquid fermentation extraction to obtain a fermentation extraction mixture; pre-extruding and extruding the fermented and extracted mixture in sequence to obtain low-moisture protein and residue-containing mixed liquid; centrifuging the residue-containing mixed solution to obtain a clear mixed solution and low-moisture protein; the method comprises the following steps: mixing low-moisture-content proteins, adding bacillus subtilis, carrying out solid fermentation to obtain a fermented concentrated protein crude product, drying, and carrying out superfine grinding to obtain the fermented concentrated protein; performing microfiltration on the clear mixed liquid, and performing evaporation concentration to obtain concentrated syrup; and secondary steam generated by drying and secondary water vapor generated by evaporation are recycled. The method provided by the invention does not generate wastewater, and the obtained fermented protein concentrate has low antinutritional factor content, has protein content of more than or equal to 65%, and can be used as a substitute of animal high-protein feed raw materials such as fish meal.

Description

Technical Field

[0001] The invention relates to the technical field of fermented protein feed processing, and in particular to a method for preparing fermented concentrated protein by using low-temperature meal. Background Art

[0002] With the rapid development of the aquaculture industry, the demand for feed, especially protein feed raw materials, has increased. The supply of animal high-protein feed raw materials such as fish meal is insufficient and expensive. In order to reduce the dependence on high-protein feed raw materials such as fish meal and improve the utilization rate of protein feed, the relevant research on high concentrated protein has been gradually carried out.

[0003] Generally, the protein content of concentrated protein on the market is high, generally ≥65%. It is divided into acid-based concentrated protein and alcohol-based concentrated protein according to the processing method. Acid-based concentrated protein is a concentrated protein that uses hot water to extract soluble sugars in plant meal under acidic conditions to increase the protein content. Hydrochloric acid is generally used to adjust the pH value. During the production process, not only a large amount of sewage is generated, but also some anti-nutritional factors cannot be decomposed. In addition, acid-based concentrated protein is generally food-grade concentrated protein, with high production costs and strict standards. It is rarely used in the feed industry as a high-protein feed raw material. Alcohol-based concentrated protein is a concentrated protein obtained by extracting soluble sugars in plant meal at the isoelectric point of protein using a certain concentration of ethanol aqueous solution to increase the protein content. During the production process, the protein undergoes alcohol denaturation and the degree of hydrolysis is reduced. Feed-grade concentrated protein can replace part of animal high-protein feed raw materials, but alcohol-based concentrated protein has poor palatability in feed applications. In addition, whether it is acid-based protein concentrate or alcohol-based protein concentrate, there is no fermentation step in the production process, large molecular proteins cannot be degraded, the protein hydrolysis degree is low, the digestion utilization rate is low, and it does not have a sour aroma. It is not an ideal substitute for animal high-protein feed raw materials, and it cannot adapt to the arrival of the antibiotic-free feed era.

[0004] Fermented protein feed does not require the addition of antibiotics, which is in line with the general trend of "antibiotic ban" in feed. The fermented protein feed on the market now generally uses high-temperature fermented meal as one of the main raw materials. However, the high-temperature fermented meal produced by a single strain or mixed strains through a single fermentation process also has some disadvantages: (1) The protein content is relatively low (generally the protein content is around 45%-55%, rarely exceeding 60%), which cannot be called fermented concentrated protein and has no application potential to replace animal high-protein feed raw materials; (2) The soluble sugar is not completely removed, which affects the quality of the feed; (3) The raw material is high-temperature meal. Although a part of the macromolecular protein is degraded during the fermentation process, which improves the digestibility and utilization rate, most of the protein molecules in the high-temperature meal are thermally denatured during the production process, resulting in a low overall hydrolysis degree and unsatisfactory digestibility and utilization rate. Summary of the invention

[0005] Aiming at the technical problems that the macromolecular proteins in the acid-process concentrated protein and the alcohol-process concentrated protein in the prior art are not easy to degrade, the protein hydrolysis degree is low, the digestion utilization rate is low, and antibiotics need to be added, while the fermented high-temperature meal has the low protein content and the soluble sugar is not completely removed, the present invention provides a method for preparing fermented concentrated protein by using low-temperature meal. The low-temperature meal is used as a raw material, and a process combining liquid fermentation extraction and solid fermentation is adopted. The protein content of the obtained fermented concentrated protein is ≥65%, which can be used to replace animal high-protein feed raw materials such as fish meal, and at the same time has the advantages of low anti-nutritional factor content, high protein hydrolysis degree and sour aroma.

[0006] The technical solution of the present invention is: A method for preparing fermented concentrated protein using low-temperature meal, comprising the following steps: (1) adding low-temperature meal, fermentation extraction water and Lactobacillus acidophilus into a fermentation extraction tank, wherein the mass ratio of low-temperature meal to fermentation extraction water is 1:3-1:4, and Lactobacillus acidophilus is added at a ratio of 2wt%-4wt% of the low-temperature meal, and then adjusting the pH to 4.5-5.5, and fermenting and extracting the liquid at 35°C for 12-18 hours while stirring to obtain a fermentation extraction mixture; (2) pre-extruding the fermentation extraction mixture to obtain a moisture-containing protein and residue mixed solution with a moisture content of 65%-68%, and further extruding the moisture-containing protein with a moisture content of 65%-68% to obtain a low moisture-containing protein and residue mixed solution with a moisture content of ≤58%; (3) mixing the residue-containing mixed solution obtained by pre-extrusion and extrusion, and then centrifuging to obtain a clear mixed solution and low-moisture protein; (4) adding the low moisture content protein obtained in step (3) to the low moisture content protein with a moisture content of ≤58% obtained in step (2), adding Bacillus subtilis at a ratio of 2wt%-3wt% of the low moisture content protein after mixing, and then entering into a shallow continuous solid fermentation tank for solid fermentation at 35°C for 60-72 hours to obtain a crude fermentation concentrated protein; (5) conveying the crude fermented concentrated protein to a horizontal disc dryer for drying, and then ultrafine grinding to obtain a fermented concentrated protein in powdery form; (6) The clear mixed liquid in step (3) is microfiltered and then evaporated and concentrated in a falling film triple effect evaporator to obtain a concentrated syrup by-product with a concentration of ≥50%; the secondary steam generated by the horizontal disc dryer and the secondary water vapor generated by the falling film triple effect evaporator are recycled.

[0007] Furthermore, the low-temperature meal in step (1) is one of soybean low-temperature meal, peanut low-temperature meal, rapeseed low-temperature meal, and cottonseed low-temperature meal; and the viable count of Lactobacillus acidophilus is 100 billion CFU / g.

[0008] Furthermore, the temperature of the water used for fermentation extraction in step (1) is 45-50°C.

[0009] Furthermore, in step (1), the pH is adjusted by adding citric acid.

[0010] Furthermore, in step (2), a single-screw variable pitch pre-extruder is used for pre-extrusion, and a double-screw variable pitch extruder is used for extrusion.

[0011] Furthermore, the viable count of Bacillus subtilis in step (4) is 100 billion CFU / g Furthermore, in step (5), the moisture content of the fermented concentrated protein crude product after drying is reduced to below 12%.

[0012] Furthermore, the evaporation concentration in step (6) is carried out in a negative pressure environment, and the negative pressure vacuum is -0.09 MPa.

[0013] Furthermore, the secondary steam generated by the horizontal disc dryer in step (6) is used as a heat source for the falling film triple-effect evaporation system; the secondary water vapor generated by the falling film triple-effect evaporation system enters the condensation system to condense into process water, and then enters the fermentation extraction tank to be used as fermentation extraction water.

[0014] Furthermore, the tail gas generated by the condensation system in step (6) is discharged into the air after being photoelectrically decomposed.

[0015] The beneficial effects of the present invention are: The present invention provides a method for preparing fermented concentrated protein using low-temperature meal. The low-temperature meal is used as a raw material, and the fermentation is carried out in a combination of liquid fermentation extraction and solid fermentation. Pre-extrusion and extrusion are combined in the two fermentations to fully remove the residue-containing mixed liquid to obtain low-moisture protein, and then solid fermentation is carried out; after solid fermentation, a horizontal disc dryer is used for drying and dehydration, and the secondary steam generated is used as a heat source for a falling film triple-effect evaporation system; the secondary water vapor generated by evaporation and concentration enters a condensation system to condense to obtain process water, and then enters a fermentation extraction tank for use as fermentation extraction water. The method provided by the present invention does not generate wastewater during the preparation process, and is energy-saving and environmentally friendly. The fermented concentrated protein prepared by the method provided by the present invention has a protein content of ≥65%, a low anti-nutritional factor content, a high degree of protein hydrolysis, and a sour aroma, and can be used as an ideal substitute for animal high-protein feed raw materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1The present invention is a process flow chart of preparing fermented concentrated protein from low-temperature soybean meal in the embodiment. DETAILED DESCRIPTION

[0018] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0019] The strain information used in the following examples: Lactobacillus acidophilus, with a viable count of 100 billion CFU / g, was purchased from Shandong Yihao Biotechnology Co., Ltd.; Bacillus subtilis, model NJYBGJ-100, with a viable count of 100 billion CFU / g, was purchased from Shandong Yihao Biotechnology Co., Ltd.

[0020] Example 1 A method for preparing fermented concentrated protein using low-temperature meal, the process flow is shown in Figure 1 , specifically including the following steps: (1) adding soybean low-temperature meal into a fermentation extraction tank by a variable frequency auger, adding 50°C fermentation extraction water and Lactobacillus acidophilus at the same time, the mass ratio of soybean low-temperature meal to fermentation extraction water being 1:3, and Lactobacillus acidophilus being added at a ratio of 2wt% of soybean low-temperature meal, and then adding citric acid into the fermentation extraction tank by a quantitative pump, adjusting the pH value to 4.5, and fermenting and extracting the mixture at 35°C for 12 hours while stirring; (2) The fermentation extraction mixture is quantitatively conveyed to a single-screw variable pitch pre-extruder through a screw pump, and a wet protein (i.e., wet-based protein) and a residue-containing mixed liquid with a moisture content of 65% are obtained through pre-extrusion. The wet protein is further conveyed to a double-screw variable pitch extruder through a quantitative auger, and a low-moisture protein and residue-containing mixed liquid with a moisture content of ≤58% is obtained through extrusion. The residue-containing mixed liquids obtained twice are conveyed to a temporary storage tank for temporary storage; (3) The residue-containing mixed liquid in the temporary storage tank is quantitatively transported to a horizontal centrifuge by a screw pump for centrifugation to obtain a clear mixed liquid and low-moisture protein. The clear mixed liquid is microfiltered to remove fine particles therein; (4) adding the low moisture content protein obtained in step (3) to the low moisture content protein with a moisture content of ≤58% obtained in step (2), and then conveying it to a paddle-type culture mixer through a quantitative auger, adding Bacillus subtilis at a ratio of 2 wt% of the low moisture content protein, and then conveying it to a shallow continuous solid fermentation tank through a quantitative auger after mixing for solid fermentation at 35° C. for 72 hours to obtain a crude fermentation concentrated protein; (5) The crude fermented concentrated protein is quantitatively fed into a horizontal disc dryer for drying. After drying, the moisture content is reduced to below 12%. The crude product is then transported to an ultrafine grinding machine system for ultrafine grinding to obtain a fermented concentrated protein with a sour aroma and a powdery texture. The proportion of particles with a particle size greater than 80 mesh exceeds 90%. (6) The clear mixed liquid after microfiltration in step (3) enters a falling film triple-effect evaporation system, and is evaporated and concentrated in a negative pressure environment (vacuum degree is -0.09 MPa) to obtain a concentrated syrup by-product with a concentration of ≥50%; the falling film triple-effect evaporation system uses the secondary steam generated by the horizontal disc dryer as a heat source; the secondary water vapor evaporated by the falling film triple-effect evaporation system enters a condensation system, and the process water obtained by condensation enters a fermentation extraction tank for recycling as fermentation extraction water; the tail gas generated by the condensation system is discharged into the air after being photoelectrically decomposed by a water absorption tower.

[0021] After testing, the protein content of the fermented concentrated protein is 66%; the anti-nutritional factor content is: soybean globulin ≤8 mg / kg, β-conglycinin ≤5 mg / kg, trypsin inhibitor ≤3 mg / kg, stachyose ≤0.3%.

[0022] Example 2 A method for preparing fermented concentrated protein using low-temperature meal, comprising the following steps: (1) adding soybean low-temperature meal into a fermentation extraction tank by a variable frequency auger, adding 45°C fermentation extraction water and Lactobacillus acidophilus at the same time, the mass ratio of soybean low-temperature meal to fermentation extraction water being 1:4, and Lactobacillus acidophilus being added at a ratio of 4wt% of soybean low-temperature meal, and then adding citric acid into the fermentation extraction tank by a quantitative pump, adjusting the pH value to 5.5, and fermenting and extracting at 35°C for 18 hours while stirring to obtain a fermentation extraction mixture; (2) The fermentation extraction mixture is quantitatively conveyed to a single-screw variable pitch pre-extruder through a screw pump, and a wet protein (i.e., wet-based protein) and a residue-containing mixed liquid with a moisture content of 68% are obtained through pre-extrusion. The wet protein is further conveyed to a double-screw variable pitch extruder through a quantitative auger, and a low-moisture protein and residue-containing mixed liquid with a moisture content of ≤58% is obtained through extrusion. The residue-containing mixed liquids obtained twice are conveyed to a temporary storage tank for temporary storage; (3) The residue-containing mixed liquid in the temporary storage tank is quantitatively transported to a horizontal centrifuge by a screw pump for centrifugation to obtain a clear mixed liquid and low-moisture protein. The clear mixed liquid is microfiltered to remove fine particles therein; (4) adding the low moisture content protein obtained in step (3) to the low moisture content protein with a moisture content of ≤58% obtained in step (2), and then conveying it to a paddle-type culture mixer through a quantitative auger, adding Bacillus subtilis at a ratio of 3 wt% of the low moisture content protein, and then conveying it to a shallow continuous solid fermentation tank through a quantitative auger after mixing for solid fermentation at 35° C. for 60 hours to obtain a crude fermentation concentrated protein; (5) The crude fermented concentrated protein is quantitatively fed into a horizontal disc dryer for drying. After drying, the moisture content is reduced to less than 10%. Then, the crude fermented concentrated protein is transported to an ultrafine grinding machine system for ultrafine grinding to obtain a fermented concentrated protein with a sour aroma and a powdery texture. Among them, particles with a particle size greater than 100 mesh account for more than 90%; (6) The clear mixed liquid after microfiltration in step (3) enters a falling film triple-effect evaporation system, and is evaporated and concentrated in a negative pressure environment (vacuum degree is -0.09 MPa) to obtain a concentrated syrup by-product with a concentration of ≥55%; the falling film triple-effect evaporation system uses the secondary steam generated by the horizontal disc dryer as a heat source; the secondary water vapor evaporated by the falling film triple-effect evaporation system enters a condensation system, and the process water obtained by condensation enters a fermentation extraction tank for recycling as fermentation extraction water; the tail gas generated by the condensation system is discharged into the air after being photoelectrically decomposed by a water absorption tower.

[0023] The protein content of the fermented concentrated protein was tested to be 67%; the anti-nutritional factor content was: soybean globulin ≤8 mg / kg, β-conglycinin ≤5 mg / kg, trypsin inhibitor ≤3 mg / kg, and stachyose ≤0.3%.

[0024] Although the present invention has been described in detail with reference to the accompanying drawings and in combination with the preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, a person of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and these modifications or substitutions shall be within the scope of the present invention. Any person of ordinary skill in the art may easily think of changes or substitutions within the technical scope disclosed by the present invention, and these shall be within the scope of protection of the present invention.

Claims

1. A method for preparing fermented concentrated protein using low-temperature meal, characterized in that: The following steps are involved: (1) adding low-temperature meal, fermentation extraction water and Lactobacillus acidophilus into a fermentation extraction tank, wherein the mass ratio of low-temperature meal to fermentation extraction water is 1:3-1:4, and Lactobacillus acidophilus is added at a ratio of 2wt%-4wt% of the low-temperature meal, and then adjusting the pH to 4.5-5.5, and fermenting and extracting the liquid at 35°C for 12-18 hours while stirring to obtain a fermentation extraction mixture; (2) pre-extruding the fermentation extraction mixture to obtain a moisture-containing protein and residue mixed solution with a moisture content of 65%-68%, and further extruding the moisture-containing protein with a moisture content of 65%-68% to obtain a low moisture-containing protein and residue mixed solution with a moisture content of ≤58%; (3) mixing the residue-containing mixed solution obtained by pre-extrusion and extrusion, and then centrifuging to obtain a clear mixed solution and low-moisture protein; (4) adding the low moisture content protein obtained in step (3) to the low moisture content protein with a moisture content of ≤58% obtained in step (2), adding Bacillus subtilis at a ratio of 2wt%-3wt% of the low moisture content protein after mixing, and then entering into a shallow continuous solid fermentation tank for solid fermentation at 35°C for 60-72 hours to obtain a crude fermentation concentrated protein; (5) conveying the crude fermented concentrated protein to a horizontal disc dryer for drying, and then ultrafine grinding to obtain a fermented concentrated protein in powdery form; (6) The clear mixed liquid in step (3) is microfiltered and then evaporated and concentrated in a falling film triple effect evaporator to obtain a concentrated syrup by-product with a concentration of ≥50%; the secondary steam generated by the horizontal disc dryer and the secondary water vapor generated by the falling film triple effect evaporator are recycled.

2. The method for preparing fermented concentrated protein using low-temperature meal according to claim 1, characterized in that: The low-temperature meal in step (1) is one of soybean low-temperature meal, peanut low-temperature meal, rapeseed low-temperature meal, and cottonseed low-temperature meal; and the viable bacterial count of Lactobacillus acidophilus is 100 billion CFU / g.

3. The method for preparing fermented concentrated protein using low-temperature meal according to claim 1, characterized in that: In step (1), the pH is adjusted by adding citric acid.

4. The method for preparing fermented concentrated protein using low-temperature meal according to claim 1, characterized in that: In step (2), a single-screw variable pitch pre-extruder is used for pre-extrusion, and a double-screw variable pitch extruder is used for extrusion.

5. The method for preparing fermented concentrated protein using low-temperature meal according to claim 1, characterized in that: The viable bacterial count of Bacillus subtilis in step (4) is 100 billion CFU / g.

6. The method for preparing fermented concentrated protein using low-temperature meal according to claim 1, characterized in that: In step (5), the moisture content of the fermented concentrated protein crude product is reduced to below 12% after drying.

7. The method for preparing fermented concentrated protein using low-temperature meal according to claim 1, characterized in that: The evaporation concentration in step (6) is carried out in a negative pressure environment, and the negative pressure vacuum is -0.09 MPa.

8. The method for preparing fermented concentrated protein using low-temperature meal according to claim 1, characterized in that: In step (6), the secondary steam generated by the drying in the horizontal disc dryer is used as the heat source of the falling film triple-effect evaporation system; the secondary water vapor generated by the falling film triple-effect evaporation system enters the condensation system to condense to obtain process water, and then enters the fermentation extraction tank to be used as fermentation extraction water.

9. The method for preparing fermented concentrated protein using low-temperature meal according to claim 8, characterized in that: The tail gas generated by the condensation system in step (6) is discharged into the air after being photoelectrically decomposed.

Images