Extraction process and application of cottonseed peptide and cottonseed fiber

Abstract

The invention relates to an extraction process and application of cottonseed peptide and cottonseed fiber, and the separation of cottonseed hull, cottonseed fiber and cottonseed protein is realized by carrying out matched processes such as sulfurous acid aqueous solution extraction, impact type needle mill pulping, gravity curved sieve and pressure curved sieve screening, countercurrent washing and the like on cottonseed meal and / or cottonseed protein powder. According to the method, the cottonseed protein is promoted to be converted into water-soluble cottonseed protein from a state of being combined with cottonseed hulls and cottonseed fibers, the cottonseed fibers are obtained through dehydration and drying, the cottonseed protein is further subjected to hydrolysis and composite enzymolysis to obtain enzymolysis peptide liquid, and the cottonseed peptide (cottonseed enzymolysis protein) is obtained through concentration and spray drying, so that the extraction rate of the cottonseed protein is remarkably increased and is 42.6-50.2%. The content of oligopeptide with the molecular weight lower than 1000 Daltons of cottonseed enzymolysis protein exceeds 82%, the content of free gossypol is lower than 400 mg / kg, the removal rate reaches up to 85% or above, and the prepared cottonseed peptide is completely water-soluble, clear, transparent and free of bitter taste and can be safely used in the fields of feed, food, biological materials, cosmetics, medicines and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of biological peptide preparation, and particularly relates to an extraction process and application of cottonseed peptide and cottonseed fiber. Background Art

[0002] Existing technical solutions are divided into two technical routes: from cottonseed meal or cottonseed protein powder to purified cottonseed concentrated protein and then to cottonseed peptides (referred to as the two-step cottonseed peptide technical route); and from cottonseed meal or cottonseed protein powder directly to cottonseed peptides (referred to as the one-step cottonseed peptide technical route). In the existing technical solutions, the biosynthesis of cottonseed protein in cottonseed meal or cottonseed protein powder is symbiotic and mutually entrained with fat, cottonseed fiber, ash, water, etc. in the cell wall of cottonseed kernels, and is wrapped in cotton husks and cottonseed fibers. There is a problem of unifying the stirring intensity and separation coefficient to completely separate the cottonseed protein entrained in cotton husks and cottonseed fibers. There is no specific technical solution for completely separating the cottonseed protein entrained in cotton husks and cottonseed fibers, and it needs to be solved urgently; in the two-step cottonseed peptide technical route, soaking cottonseed meal or In the laboratory, the separation of residue and liquid from cottonseed protein powder mostly adopts the high-speed centrifugation separation method with a speed of about 4000r / min, and there is no industrial residue-liquid separation scheme; in the one-step cottonseed peptide technical route, the separation of residue and liquid from cottonseed meal or cottonseed protein powder enzymatic hydrolysate mostly adopts the high-speed centrifugation separation method with a speed of about 4000r / min, and there is no industrial residue-liquid separation scheme; both the two-step cottonseed peptide technical route and the one-step cottonseed peptide technical route need to solve the problem of recovering cottonseed protein or cottonseed peptide in the separation residue to improve the overall yield. Patent application CN102206290A discloses a method for extracting cottonseed oligosaccharides and cottonseed protein oligopeptides from cottonseed meal. The method uses a microfiltration membrane for impurity removal and concentration, and then spray-drying, alkali dissolution, enzymatic hydrolysis, decolorization, centrifugation, and then uses a microfiltration membrane and a nanofiltration membrane for impurity removal and concentration to obtain cottonseed protein oligopeptides. The prepared oligopeptides (200~1000Dal) have a content of more than 90%, but the protein peptide extraction rate of this method is lower than 46%, and the extraction rate is not high. The microfiltration membrane and nanofiltration membrane have large losses, and the membrane needs to be replaced regularly. The process is complicated, uneconomical, and the production cost is high. It is difficult to achieve industrial production using microfiltration membranes and nanofiltration membranes, and the production speed is slow. In summary, the current technology is mostly aimed at the research on the component extraction process of cottonseed protein, and there are still deficiencies in specific industrial production. Summary of the invention

[0003] In view of the problems existing in the above-mentioned prior art, the present invention provides a process for extracting cottonseed peptides and cottonseed fibers. The content of oligopeptides with a molecular weight of less than 1000 Daltons in the prepared cottonseed peptides exceeds 82%. The cottonseed peptides are fully water-soluble, clear and transparent, have no bitterness, and have a low content of free cottonphenol. They can be safely used in animal feed, food packaging materials, bioplastics, food functional additives, biological culture media and enzyme synthesis, biodegradable materials, and cosmetics. The following is the specific invention content of the present invention: In a first aspect, the present invention provides a process for extracting cottonseed peptides and cottonseed fibers, comprising the following steps: S1. Extraction with sulfurous acid aqueous solution Soaking cottonseed meal and / or cottonseed protein powder in a sulfurous acid aqueous solution with a concentration of 0.05-2.5% for extraction, with a solid-liquid ratio of 1 g: 3-20 mL, an extraction time of 2-12 hours, and an extraction temperature of 40-65° C., to obtain a cottonseed meal soaking liquid; S2, cottonseed hull, cottonseed fiber, cottonseed protein separation The cottonseed meal soaking liquid obtained in step S1 is pumped into a 1# impact pin mill by a centrifugal pump, and the cottonseed protein mixed in the cottonseed hull and cottonseed fiber is further released and transferred into the aqueous solution through high-speed collision (rotating speed of 3000-5000 r / min, time of about 60-90 min), so as to obtain a coarsely ground cottonseed meal soaking liquid; then the coarsely ground cottonseed meal soaking liquid is sent into a coarse grinding pit, and is pumped into a 1# two-stage series gravity curved screen by a centrifugal pump, and passes through the gravity curved screen with a gap of 30-50 mm (larger than the size of wet large cotton hull) and 30-10 mm (larger than the size of wet medium and small cotton hull) in sequence, so that the sieve material is wet cotton hull (the wet cotton hull is mixed with water in a mass ratio of 1:3-6, and sent to a cottonseed hull temporary storage tank with a stirrer, and the cottonseed protein remaining in the wet cotton hull is transferred into the aqueous solution with water, so as to reduce the cottonseed protein content in the wet cotton hull and improve the cottonseed protein yield), and the sieve material is cottonseed protein liquid containing cottonseed fiber; Further, the cottonseed protein liquid containing cottonseed fiber is sent to the 2# impact pin mill, and the cottonseed protein mixed in the cottonseed fiber is further released and transferred into the aqueous solution through high-speed collision (rotation speed is 3000-5000 r / min, time is about 100-120min), so as to obtain finely ground cottonseed fiber protein liquid; then the finely ground cottonseed fiber protein liquid is sent to the fine grinding pit, and pumped to the 1# pressure curved screen by a centrifugal pump, the sieve gap of the 1# pressure curved screen is 100-150μm (smaller than the size of wet cottonseed fiber), and the sieve-surface material is wet cottonseed fiber, and the sieve-surface material is cottonseed protein liquid I; The cottonseed meal soaking liquid obtained in step S1 is sequentially processed through a 1# impact pin mill and a 1# two-stage series gravity curved screen to obtain wet cotton husk and cottonseed protein liquid containing cottonseed fiber, wherein the sieve gaps of the 1# two-stage series gravity curved screen are 30-50 mm and 30-10 mm respectively; then the cottonseed protein liquid containing cottonseed fiber is sequentially processed through a 2# impact pin mill and a 1# pressure curved screen with a sieve gap of 100-150 μm to sieve to obtain wet cottonseed fiber and cottonseed protein liquid I; then Then, the wet cottonseed fiber is sent to the 2# pressure curved screen group for countercurrent washing, wherein the 2# pressure curved screen group comprises 1st to 6th pressure curved screens (each pressure curved screen comprises 1 120° pressure curved screen, 1 cottonseed fiber tank for oversize, 1 cottonseed fiber tank centrifugal pump, 1 cottonseed protein washing liquid tank for undersize, and 1 cottonseed protein washing liquid centrifugal pump), the screen gaps of the 1st and 6th pressure curved screens are 30-50 μm, and the screen gaps of the 2nd to 5th pressure curved screens are 60-150 μm; The wet cottonseed fiber is added from the first-stage pressure curved screen by a first-stage cottonseed fiber centrifugal pump, and the first-stage pressure curved screen is used to wash and screen the wet cottonseed fiber, and the wet cottonseed fiber is temporarily stored in the second cottonseed fiber tank, and the wet cottonseed fiber is temporarily stored in the first-stage cottonseed protein washing liquid tank. The cottonseed fibers are washed and screened sequentially through the first to sixth pressure curved screens. The screened materials obtained after washing and screening through each pressure curved screen are cottonseed fibers, and the screened materials are cottonseed protein washing liquid. The screened materials enter the next pressure curved screen for washing and screening to obtain cottonseed protein separated from the cottonseed fibers. Finally, the washed and screened cottonseed fibers are pumped out of the pressure curved screen group from the sixth cottonseed fiber temporary storage tank (the first-level cottonseed fibers with the highest cottonseed protein concentration gradually enter the sixth-level cottonseed fiber temporary storage tank from the first level, so the cottonseed protein concentration in the sixth-level cottonseed fibers is the lowest), and then dehydrated and dried to obtain dry cottonseed fibers. The 2nd to 5th level pressure curved screens mainly play a washing role. The washing process of each level of pressure curved screen is to use the cottonseed protein washing liquid obtained by screening the next level of pressure curved screen to wash the screened material obtained by screening the previous level of pressure curved screen. The initial washing liquid is clean water, which is added from the 6th level pressure curved screen (from the 6th level underscreen cottonseed protein washing liquid tank to the 5th level overscreen cottonseed fiber tank, and pumped into the 6th level pressure curved screen surface for screening by the 5th level cottonseed fiber tank centrifugal pump). The screened material of the 5th level pressure curved screen is washed and screened to obtain the screened material as the 6th level cottonseed protein. The white washing liquid enters the fifth-stage cottonseed protein washing liquid tank for temporary storage, and the screened material is the sixth-stage cottonseed fiber which enters the sixth-stage cottonseed fiber tank for temporary storage. The cottonseed protein washing liquid is sequentially transported to the first-stage pressure curved screen through the sixth-stage pressure curved screen, and the screened material of the previous-stage pressure curved screen is washed and screened at the same time. The finally obtained cottonseed protein washing liquid is pumped out from the first-stage cottonseed protein washing liquid tank (according to the countercurrent principle, it gradually flows back from the sixth-stage cottonseed protein washing liquid tank to the first-stage cottonseed protein washing liquid tank, so the cottonseed protein concentration in the first-stage cottonseed protein washing liquid is the highest), and then concentrated to obtain cottonseed protein liquid II; S3, cottonseed protein hydrolyzate The cottonseed protein liquid I and the cottonseed protein liquid II obtained in the collecting step S2 are mixed and separated by a disc-type high-speed centrifuge or a horizontal spiral sedimentation centrifuge, the liquid phase is the clean cottonseed protein liquid, and the solid phase is the cottonseed fiber residue. The clean cottonseed protein liquid is concentrated to a concentration of 15-25wt%, and then subjected to high-temperature hydrolysis (hydrolysis temperature is 70-121°C, hydrolysis pH is 4.5-9.0, and hydrolysis time is 8s-45min), cooled, and then flocculated under acidic conditions near the isoelectric point (the flocculation is to adjust the pH to 3.0-6.5 for flocculation precipitation, the flocculation temperature is 5-75°C, and the flocculation time is 5-60min) to obtain cottonseed protein, and the cottonseed protein is washed, filtered, and vacuum dehydrated to obtain cottonseed protein cake and dehydrated protein liquid; S4, cottonseed protein hydrolysis The cottonseed protein cake obtained in step S3 is re-dissolved in water to prepare a mixed liquid with a concentration of 1-50wt%, heated to 60-121°C and maintained for 10-45min, then cooled to 30-65°C, the pH is adjusted to 3-10.5, alkaline protease, neutral protease, acidic protease, free cottonyphenol decomposing enzyme, keratinase and flavor protease are added in sequence for enzymolysis, the amount of enzyme added is 0.1-15wt%, the composite ratio of alkaline protease, neutral protease, acidic protease, free cottonyphenol decomposing enzyme, keratinase and flavor protease is 10-15:3-5:3-5:2-4:1-2:0.5-3, the enzymolysis time is 0.5-12h, the enzymolysis temperature is 35-65°C, and heating is inactivated to obtain an enzymolysis peptide liquid; S5, concentration, drying The enzymatic peptide liquid obtained in step S4 is concentrated to a concentration of 10-50wt%, and then filtered to remove impurities and solid particles. The liquid is spray-dried and heat-exchanged with hot air at 170-210°C. The inlet air temperature of the spray-drying is 120-190°C, and the exhaust air temperature is 50-90°C. Cottonseed peptide dry powder is collected.

[0004] Furthermore, the structure of the 1# two-stage series gravity curved screen described in the present invention mainly includes a shell, a raw material receiver, a screen material receiver and a frame for fixing the screen surface, etc. The gravity curved screen has a special cutting and screening function, a large production capacity and is not easy to be blocked. The working principle of the gravity curved screen is: the liquid-solid mixture is spread on the entire screen surface, and when the material moves along the curved gravity curved screen surface (the curvature of the screen surface includes but is not limited to 50°~60°), centrifugal force and inertial force are generated. The centrifugal force of fine particles is greater than the inertial force. Under the action of centrifugal force, the liquid and fine particles leak from the screen holes, and under the action of inertial force, the residue on the screen slides down along the screen surface.

[0005] Furthermore, the 1# pressure curved screen and the 2# pressure curved screen group described in the present invention are high-efficiency screens that rely on pressure to screen wet materials. The pressure curved screen structure mainly includes a shell, a feeder, a screen, a receiver for under-screen materials, a funnel for receiving under-screen materials, and a frame for fixing the screen surface. The screen surface is a key component of the pressure curved screen. The curvature of the screen surface includes but is not limited to 120°~300°. During operation, the wet material is discharged from the nozzle (the nozzle diameter is 1 / 2~3 / 4 inch, and the nozzle flow rate is 9.1~20.5 m 3 / h) is ejected, and a high feed injection speed is converted from the pressure to generate a tangential force. The oversize material is discharged from the slag outlet, and the undersize liquid material enters the undersize material receiving funnel (slurry outlet).

[0006] Furthermore, the cottonseed peptide yield and the dry cottonseed fiber yield obtained by the cottonseed peptide and cottonseed fiber extraction process of the present invention are 42-50.2%, and 48-58%.

[0007] In a second aspect, the present invention also provides a cottonseed peptide, wherein the cottonseed peptide extraction rate exceeds 40%, the content of oligopeptides with a molecular weight below 1000 Dalton exceeds 82%, the free gossypol content is less than 400 mg / kg, the moisture content is less than 5.5%, the crude protein content is higher than 65%, the crude ash content is lower than 11.5%, and the acid-soluble protein content (accounting for the crude protein content) exceeds 62%.

[0008] In a third aspect, the present invention further provides a dry cottonseed fiber, wherein the dry cottonseed fiber is obtained by dehydrating and drying wet cottonseed fiber obtained by the cottonseed peptide and cottonseed fiber extraction process of the present invention.

[0009] In a fourth aspect, the present invention also provides the use of cottonseed peptides in animal feed, food packaging materials, bioplastics, functional foods, biological culture media and enzyme synthesis, biodegradable materials, cosmetics and medicines.

[0010] The invention adopts a sulfurous acid aqueous solution to extract cottonseed meal and cottonseed protein powder, and aims to wet the cottonseed meal with water to swell cottonseed hulls, cottonseed fibers and cottonseed proteins, and the sulfurous acid aqueous solution extracts cottonseed proteins mixed in cottonseed hulls and cottonseed fibers into the aqueous solution, so that the cottonseed proteins in the cottonseed meal and cottonseed protein powder are transformed from the state of being combined with cottonseed hulls and cottonseed fibers into water-soluble cottonseed proteins, thereby realizing the water-soluble extraction of cottonseed proteins.

[0011] The present invention separates cottonseed hulls, cottonseed fibers, and cottonseed proteins from cottonseed meal and cottonseed protein powder, and separates cottonseed hulls from cottonseed protein liquid containing cottonseed fibers by a 1# impact pin mill and a 1# two-stage series gravity curved screen; separates wet cottonseed fibers from cottonseed protein liquid by a 2# impact pin mill and a 1# pressure curved screen; and further reduces cottonseed proteins in cottonseed fibers by a 2# pressure curved screen group combined with a countercurrent washing process, and separates cottonseed fibers from cottonseed proteins. The separation process can achieve maximum separation of cottonseed hulls, cottonseed fibers, and cottonseed proteins, and obtains higher purity and yield of cottonseed fibers and cottonseed proteins, and has higher application value.

[0012] The cottonseed peptide is prepared by enzymatic hydrolysis using a composite enzyme consisting of alkaline protease, neutral protease, acidic protease, cottonpol decomposing enzyme, keratinase and flavor protein protease, and the synergistic effect of multiple enzymes is utilized to maximize the different advantages of the enzyme cleavage sites of various enzymes. The compounding of different types of proteases often has a synergistic effect, which is not only beneficial to shortening the enzymatic hydrolysis time and improving the hydrolysis degree, but also can obtain an enzymatic hydrolyzate with better molecular weight composition and distribution.

[0013] Compared with the prior art, the present invention has the following beneficial effects: The present invention uses a sulfurous acid aqueous solution to extract cottonseed peptides from cottonseed meal and cottonseed protein powder raw materials, and can convert the cottonseed protein of the cottonseed meal and cottonseed protein powder raw materials from a state of being combined with cottonseed hulls and cottonseed fibers into water-soluble cottonseed proteins, thereby achieving the maximum water-soluble extraction of cottonseed proteins. The present invention uses processes such as 1# impact pin mill, 1# two-stage series gravity curved screen, 2# impact pin mill, 1# pressure curved screen, 2# pressure curved screen group combined with countercurrent washing, etc., to achieve the maximum separation of cottonseed fibers and cottonseed proteins, and improve the purity and yield of cottonseed fibers and cottonseed proteins. The present invention adopts a composite enzyme to enzymolyze cottonseed meal and cottonseed protein powder raw materials to prepare cottonseed peptides. The composite enzyme used for enzymolysis is thorough, and the acid-soluble protein content of the cottonseed peptide product is increased, wherein the acid-soluble protein (oligopeptide) content is more than 60%, and the acid-soluble protein (oligopeptide) content with a molecular weight lower than 1000 Dalton is higher than 82%. The obtained cottonseed peptide is fully water-soluble, clear and transparent, has no bitterness, and has a fresh and sweet taste. The free cottonpol content is lower than 400 mg / kg and the removal rate is as high as 85%. The cottonseed peptide is safe and has no toxic side effects. The cottonseed peptide can be widely used in animal feed, food packaging materials, bioplastics, food functional additives, biological culture media and enzyme synthesis, biodegradable materials, cosmetics and other fields. DETAILED DESCRIPTION

[0014] The experimental methods in the following examples of the present invention, where no specific conditions are specified, are usually carried out under conventional conditions or under conditions recommended by the manufacturers. The various commonly used chemical reagents used in the examples are all commercially available products.

[0015] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0016] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present invention. In addition, in the following description, the description of known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0017] The alkaline protease, neutral protease, acid protease, keratinase and flavor protease used in the examples of the present invention were all purchased from Shandong Longkote Enzyme Preparation Co., Ltd.; the 1# impact pin mill, 2# impact pin mill, 1# two-stage series gravity curved screen, 1# pressure curved screen and 2# pressure curved screen group used in the examples of the present invention were all purchased from Yixing Yidian Machinery Equipment Co., Ltd.; The free cottonyphenol decomposing enzyme is a protein liquid expanded by a self-selected bacterial strain, wherein the self-selected bacterial strain is diluted and separated from corrupt cottonseed meal, and the bacterial strain is obtained by comparing the fluorescence area of ​​the free cottonyphenol decomposition circle. After expansion by a slant, a shake bottle, and a primary seed tank, it is expanded in a fermenter for about 36 hours, and the centrifuged bacterial body is obtained when the wet weight is within 5-15%. The bacterial body is further broken by ultrasonic or by high-pressure homogenizer to obtain a protein liquid, and the free cottonyphenol decomposing enzyme is obtained after rotary evaporation drying or concentrated spray drying.

[0018] Example 1 Preparation of cottonseed peptide and cottonseed fiber The preparation steps of cottonseed peptide and cottonseed fiber in this embodiment are as follows: S1. Extraction with sulfurous acid aqueous solution Soaking cottonseed meal and / or cottonseed protein powder in a 0.25% sulfuric acid aqueous solution for extraction, with a solid-liquid ratio of 1 g:10 mL, an extraction time of 10 h, and an extraction temperature of 60° C., to obtain a cottonseed meal soaking liquid; S2, cottonseed hull, cottonseed fiber, cottonseed protein separation The cottonseed meal soaking liquid obtained in step S1 is pumped to a 1# impact pin mill for treatment (rotating speed of 3000 r / min, time of 90 min) by a centrifugal pump to obtain a coarsely ground cottonseed meal soaking liquid, and then the coarsely ground cottonseed meal soaking liquid is sent to a coarse grinding pit, and pumped to a 1# two-stage series gravity curved screen by a centrifugal pump, and sequentially passes through a 1# series gravity curved screen with a gap of 50 mm (larger than the size of wet large cotton husk) and 30 mm (larger than the size of wet medium and small cotton husk) (the arc of the screen surface is 60°), and the sieve-surface material is wet cotton husk, and the sieve-surface material is cottonseed protein liquid containing cottonseed fiber, the wet cotton husk is mixed with water in a mass ratio of 1:5, and sent to a cottonseed husk temporary storage tank with a stirrer, and the cottonseed protein remaining in the wet cotton husk is transferred to the aqueous solution with water, and combined with the cottonseed protein liquid containing cottonseed fiber in the sieve-surface material; Furthermore, the combined cottonseed protein liquid containing cottonseed fiber is sent to the 2# impact pin mill for treatment (rotation speed of 3000 r / min, time of 100 min) to obtain finely ground cottonseed fiber protein liquid, and then the finely ground cottonseed fiber protein liquid is sent to the fine grinding pit and pumped to the 1# pressure curved screen by a centrifugal pump. The 1# pressure curved screen has a sieve gap of 100 μm (smaller than the wet cottonseed fiber size), a sieve surface curvature of 120°, a feed pressure of 0.28~0.42 Mpa, a nozzle diameter of 1 / 2 inch, and a nozzle flow rate of 9.1~11 m 3 / h, the sieve-surface material is the wet cottonseed fiber, and the sieve-surface material is the cottonseed protein liquid I; Further, the wet cottonseed fiber is sent to a wet cottonseed fiber temporary storage tank, and is pumped into a 2# pressure curved screen group by a centrifugal pump for countercurrent washing of the cottonseed fiber. The 2# pressure curved screen group comprises 1 to 6 pressure curved screens (each pressure curved screen comprises a pressure curved screen with a screen surface arc of 120°, a cottonseed fiber trough for oversize, a cottonseed fiber trough centrifugal pump, a cottonseed protein washing liquid trough for undersize, and a cottonseed protein washing liquid centrifugal pump), the sieve gap of the 1st pressure curved screen is 30 μm, the sieve gap of the 2nd to 5th pressure curved screens is 60 μm, the sieve gap of the 6th pressure curved screen is 50 μm, the feed pressure is 0.28-0.42 Mpa, the nozzle diameter is 1 / 2 inch, and the nozzle flow rate is 9.1-11 m 3 / h; The wet cottonseed fiber is added from the first-stage pressure curved screen by a first-stage cottonseed fiber centrifugal pump, washed and screened by the first-stage pressure curved screen to obtain a sieve-surface material as the first-stage cottonseed fiber, which enters the second cottonseed fiber tank for temporary storage, and a sieve-substance as the first-stage cottonseed protein washing liquid enters the first-stage cottonseed protein washing liquid tank for temporary storage, and sequentially passes through the first to sixth-stage pressure curved screens for graded washing and screening, and the sieve-surface material obtained after washing and screening by each stage of the pressure curved screen is the cottonseed fiber, and the sieve-substance is the cottonseed protein washing liquid, and the sieve-surface material enters the next-stage pressure curved screen for washing and screening to obtain cottonseed protein separated from the cottonseed fiber, and finally the washed and screened cottonseed fiber is pumped out of the pressure curved screen group from the sixth-stage cottonseed fiber temporary storage tank (the first-stage cottonseed fiber with the highest cottonseed protein concentration gradually enters the sixth-stage cottonseed fiber temporary storage tank from the first stage, so the cottonseed protein concentration in the sixth-stage cottonseed fiber is the lowest), and then dehydrated and dried to obtain dry cottonseed fiber; The 2nd to 5th level pressure curved screens mainly play a washing role. The washing process of each level of pressure curved screen is to use the cottonseed protein washing liquid obtained by screening the next level of pressure curved screen to wash the screened material obtained by screening the previous level of pressure curved screen. The initial washing liquid is clean water, which is added from the 6th level pressure curved screen (from the 6th level underscreen cottonseed protein washing liquid tank to the 5th level overscreen cottonseed fiber tank, and pumped into the 6th level pressure curved screen surface for screening by the 5th level cottonseed fiber tank centrifugal pump). The screened material of the 5th level pressure curved screen is washed and screened to obtain the screened material as the 6th level cottonseed protein. The white washing liquid enters the fifth-stage cottonseed protein washing liquid tank for temporary storage, and the screened material is the sixth-stage cottonseed fiber which enters the sixth-stage cottonseed fiber tank for temporary storage. The cottonseed protein washing liquid is sequentially transported to the first-stage pressure curved screen through the sixth-stage pressure curved screen, and the screened material of the previous-stage pressure curved screen is washed and screened at the same time. The finally obtained cottonseed protein washing liquid is pumped out from the first-stage cottonseed protein washing liquid tank (according to the countercurrent principle, it gradually flows back from the sixth-stage cottonseed protein washing liquid tank to the first-stage cottonseed protein washing liquid tank, so the cottonseed protein concentration in the first-stage cottonseed protein washing liquid is the highest), and then concentrated to obtain cottonseed protein liquid II; S3, cottonseed protein hydrolyzate The cottonseed protein liquid I and the cottonseed protein liquid II obtained in the collecting step S2 are mixed and separated by a disc-type high-speed centrifuge (or a horizontal spiral sedimentation centrifuge), the liquid phase is the clean cottonseed protein liquid, and the solid phase is the cottonseed fiber residue. The clean cottonseed protein liquid is concentrated to a concentration of 15wt%, and then high-temperature hydrolysis (hydrolysis temperature is 90°C, hydrolysis pH is 5.6, and hydrolysis time is 25min), cooling is performed in sequence, and then the pH is adjusted to 4.0-6.5 for flocculation (flocculation temperature is 45°C, and flocculation time is 45min) to obtain cottonseed protein, and the cottonseed protein is vacuum dehydrated, washed with water, and then vacuum dehydrated to obtain cottonseed protein cake and dehydrated protein liquid; S4, cottonseed protein hydrolysis The cottonseed protein cake obtained in step S3 is dissolved in water to prepare a mixed liquid with a concentration of 5wt%, heated to 90°C and maintained for 45min, then cooled to 45°C, the pH is adjusted to 8.5, alkaline protease, neutral protease, acidic protease, free cottonyphenol decomposing enzyme, keratinase and flavor protease are added in sequence for enzymolysis, the total enzyme addition amount in the mixed liquid is 0.9wt%, the composite ratio of the alkaline protease, neutral protease, acidic protease, free cottonyphenol decomposing enzyme, keratinase and flavor protease is 15:5:5:4:2:3, the enzymolysis time is 8h, the enzymolysis temperature is 40°C, and the enzymolysis peptide liquid is obtained by heating and inactivation; S5, concentration, drying The enzymatic peptide liquid obtained in step S4 is concentrated to a concentration of 40wt%, and then filtered to remove impurities and solid particles. The liquid is spray-dried and heat-exchanged with 170°C hot air. The inlet air temperature of the spray drying is 190°C and the exhaust air temperature is 80°C. Cottonseed peptide dry powder is collected.

[0019] Example 2 Preparation of cottonseed peptide and cottonseed fiber The preparation steps of cottonseed peptide and cottonseed fiber in this embodiment are as follows: S1. Extraction with sulfurous acid aqueous solution Soaking cottonseed meal and / or cottonseed protein powder in a 0.5% sulfurous acid aqueous solution for extraction, with a solid-liquid ratio of 1 g:8 mL, an extraction time of 8 h, and an extraction temperature of 55° C., to obtain a cottonseed meal soaking liquid; S2, cottonseed hull, cottonseed fiber, cottonseed protein separation The cottonseed meal soaking liquid obtained in step S1 is pumped to a 1# impact pin mill for treatment (rotating speed of 3000 r / min, time of 90 min) by a centrifugal pump to obtain a coarsely ground cottonseed meal soaking liquid, and then the coarsely ground cottonseed meal soaking liquid is sent to a coarse grinding pit, and pumped to a 1# two-stage series gravity curved screen by a centrifugal pump, and sequentially passes through a 1# series gravity curved screen with a gap of 50 mm (larger than the size of wet large cotton husk) and 30 mm (larger than the size of wet medium and small cotton husk) (the arc of the screen surface is 60°), and the sieve-surface material is wet cotton husk, and the sieve-surface material is cottonseed protein liquid containing cottonseed fiber, the wet cotton husk is mixed with water in a mass ratio of 1:5, and sent to a cottonseed husk temporary storage tank with a stirrer, and the cottonseed protein remaining in the wet cotton husk is transferred to the aqueous solution with water, and combined with the cottonseed protein liquid containing cottonseed fiber in the sieve-surface material; Furthermore, the combined cottonseed protein liquid containing cottonseed fiber is sent to the 2# impact pin mill for treatment (rotation speed of 3000 r / min, time of 100 min) to obtain finely ground cottonseed fiber protein liquid, and then the finely ground cottonseed fiber protein liquid is sent to the fine grinding pit and pumped to the 1# pressure curved screen by a centrifugal pump. The 1# pressure curved screen has a sieve gap of 100 μm (smaller than the wet cottonseed fiber size), a sieve surface curvature of 120°, a feed pressure of 0.28~0.42 Mpa, a nozzle diameter of 1 / 2 inch, and a nozzle flow rate of 9.1~11 m 3 / h, the sieve-surface material is the wet cottonseed fiber, and the sieve-surface material is the cottonseed protein liquid I; Further, the wet cottonseed fiber is sent to a wet cottonseed fiber temporary storage tank, and is pumped into a 2# pressure curved screen group by a centrifugal pump for countercurrent washing of the cottonseed fiber. The 2# pressure curved screen group comprises 1 to 6 pressure curved screens (each pressure curved screen comprises a pressure curved screen with a screen surface arc of 120°, a cottonseed fiber trough for oversize, a cottonseed fiber trough centrifugal pump, a cottonseed protein washing liquid trough for undersize, and a cottonseed protein washing liquid centrifugal pump), the sieve gap of the 1st pressure curved screen is 30 μm, the sieve gap of the 2nd to 5th pressure curved screens is 60 μm, the sieve gap of the 6th pressure curved screen is 50 μm, the feed pressure is 0.28-0.42 Mpa, the nozzle diameter is 1 / 2 inch, and the nozzle flow rate is 9.1-11 m 3 / h; The wet cottonseed fiber is added from the first-stage pressure curved screen by a first-stage cottonseed fiber centrifugal pump, washed and screened by the first-stage pressure curved screen to obtain a sieve-surface material as the first-stage cottonseed fiber, which enters the second cottonseed fiber tank for temporary storage, and a sieve-substance as the first-stage cottonseed protein washing liquid enters the first-stage cottonseed protein washing liquid tank for temporary storage, and sequentially passes through the first to sixth-stage pressure curved screens for graded washing and screening, and the sieve-surface material obtained after washing and screening by each stage of the pressure curved screen is the cottonseed fiber, and the sieve-substance is the cottonseed protein washing liquid, and the sieve-surface material enters the next-stage pressure curved screen for washing and screening to obtain cottonseed protein separated from the cottonseed fiber, and finally the washed and screened cottonseed fiber is pumped out of the pressure curved screen group from the sixth-stage cottonseed fiber temporary storage tank (the first-stage cottonseed fiber with the highest cottonseed protein concentration gradually enters the sixth-stage cottonseed fiber temporary storage tank from the first stage, so the cottonseed protein concentration in the sixth-stage cottonseed fiber is the lowest), and then dehydrated and dried to obtain dry cottonseed fiber; The 2nd to 5th level pressure curved screens mainly play a washing role. The washing process of each level of pressure curved screen is to use the cottonseed protein washing liquid obtained by screening the next level of pressure curved screen to wash the screened material obtained by screening the previous level of pressure curved screen. The initial washing liquid is clean water, which is added from the 6th level pressure curved screen (from the 6th level underscreen cottonseed protein washing liquid tank to the 5th level overscreen cottonseed fiber tank, and pumped into the 6th level pressure curved screen surface for screening by the 5th level cottonseed fiber tank centrifugal pump). The screened material of the 5th level pressure curved screen is washed and screened to obtain the screened material as the 6th level cottonseed protein. The white washing liquid enters the fifth-stage cottonseed protein washing liquid tank for temporary storage, and the screened material is the sixth-stage cottonseed fiber which enters the sixth-stage cottonseed fiber tank for temporary storage. The cottonseed protein washing liquid is sequentially transported to the first-stage pressure curved screen through the sixth-stage pressure curved screen, and the screened material of the previous-stage pressure curved screen is washed and screened at the same time. The finally obtained cottonseed protein washing liquid is pumped out from the first-stage cottonseed protein washing liquid tank (according to the countercurrent principle, it gradually flows back from the sixth-stage cottonseed protein washing liquid tank to the first-stage cottonseed protein washing liquid tank, so the cottonseed protein concentration in the first-stage cottonseed protein washing liquid is the highest), and then concentrated to obtain cottonseed protein liquid II; S3, cottonseed protein hydrolyzate The cottonseed protein liquid I and the cottonseed protein liquid II obtained in the collecting step S2 are mixed and separated by a disc-type high-speed centrifuge (or a horizontal spiral sedimentation centrifuge), the liquid phase is the clean cottonseed protein liquid, and the solid phase is the cottonseed fiber residue. The clean cottonseed protein liquid is concentrated to a concentration of 18wt%, and then high-temperature hydrolysis (hydrolysis temperature is 121°C, hydrolysis pH is 7.8, and hydrolysis time is 20s), cooling, and then adjusting the pH to 4.0-6.5 for flocculation (flocculation temperature is 25°C, flocculation time is 25min) to obtain cottonseed protein, and the cottonseed protein is vacuum dehydrated, washed with water, and then vacuum dehydrated to obtain cottonseed protein cake; S4, cottonseed protein hydrolysis The cottonseed protein cake obtained in step S3 is dissolved in water to prepare a mixed liquid with a concentration of 10wt%, heated to 90°C and maintained for 45min, then cooled to 45°C, the pH is adjusted to 8.5, alkaline protease, neutral protease, acidic protease, free cottonyphenol decomposing enzyme, keratinase and flavor protease are added in sequence for enzymolysis, the total enzyme addition amount in the mixed liquid is 1.5wt%, the composite ratio of the alkaline protease, neutral protease, acidic protease, free cottonyphenol decomposing enzyme, keratinase and flavor protease is 12:4:4:3:1.3:1.0, the enzymolysis time is 10h, the enzymolysis temperature is 45°C, and the mixture is heated and inactivated to obtain an enzymolysis peptide liquid; S5, concentration, drying The enzymatic peptide liquid obtained in step S4 is concentrated to a concentration of 45wt%, and then filtered to remove impurities and solid particles. The liquid is spray-dried and heat-exchanged with 175°C hot air. The inlet air temperature of the spray drying is 190°C and the exhaust air temperature is 85°C. Cottonseed peptide dry powder is collected.

[0020] Example 3 Preparation of cottonseed peptide and cottonseed fiber The preparation steps of cottonseed peptide and cottonseed fiber in this embodiment are as follows: S1. Extraction with sulfurous acid aqueous solution Soaking cottonseed meal and / or cottonseed protein powder in a 1.2% sulfurous acid aqueous solution for extraction, with a solid-liquid ratio of 1 g:16 mL, an extraction time of 6 h, and an extraction temperature of 50° C., to obtain a cottonseed meal soaking liquid; S2, cottonseed hull, cottonseed fiber, cottonseed protein separation The cottonseed meal soaking liquid obtained in step S1 is pumped to a 1# impact pin mill for treatment (rotating speed of 3000 r / min, time of 90 min) by a centrifugal pump to obtain a coarsely ground cottonseed meal soaking liquid, and then the coarsely ground cottonseed meal soaking liquid is sent to a coarse grinding pit, and pumped to a 1# two-stage series gravity curved screen by a centrifugal pump, and sequentially passes through a 1# series gravity curved screen with a gap of 50 mm (larger than the size of wet large cotton husk) and 30 mm (larger than the size of wet medium and small cotton husk) (the arc of the screen surface is 60°), and the sieve-surface material is wet cotton husk, and the sieve-surface material is cottonseed protein liquid containing cottonseed fiber, the wet cotton husk is mixed with water in a mass ratio of 1:5, and sent to a cottonseed husk temporary storage tank with a stirrer, and the cottonseed protein remaining in the wet cotton husk is transferred to the aqueous solution with water, and combined with the cottonseed protein liquid containing cottonseed fiber in the sieve-surface material; Furthermore, the combined cottonseed protein liquid containing cottonseed fiber is sent to the 2# impact pin mill for treatment (rotation speed of 3000 r / min, time of 100 min) to obtain finely ground cottonseed fiber protein liquid, and then the finely ground cottonseed fiber protein liquid is sent to the fine grinding pit and pumped to the 1# pressure curved screen by a centrifugal pump. The 1# pressure curved screen has a sieve gap of 100 μm (smaller than the wet cottonseed fiber size), a sieve surface curvature of 120°, a feed pressure of 0.28~0.42 Mpa, a nozzle diameter of 1 / 2 inch, and a nozzle flow rate of 9.1~11 m 3 / h, the sieve-surface material is the wet cottonseed fiber, and the sieve-surface material is the cottonseed protein liquid I; Further, the wet cottonseed fiber is sent to a wet cottonseed fiber temporary storage tank, and is pumped into a 2# pressure curved screen group by a centrifugal pump for countercurrent washing of the cottonseed fiber. The 2# pressure curved screen group comprises 1 to 6 pressure curved screens (each pressure curved screen comprises a pressure curved screen with a screen surface arc of 120°, a cottonseed fiber trough for oversize, a cottonseed fiber trough centrifugal pump, a cottonseed protein washing liquid trough for undersize, and a cottonseed protein washing liquid centrifugal pump), the sieve gap of the 1st pressure curved screen is 30 μm, the sieve gap of the 2nd to 5th pressure curved screens is 60 μm, the sieve gap of the 6th pressure curved screen is 50 μm, the feed pressure is 0.28-0.42 Mpa, the nozzle diameter is 1 / 2 inch, and the nozzle flow rate is 9.1-11 m 3 / h; The wet cottonseed fiber is added from the first-stage pressure curved screen by a first-stage cottonseed fiber centrifugal pump, washed and screened by the first-stage pressure curved screen to obtain a sieve-surface material as the first-stage cottonseed fiber, which enters the second cottonseed fiber tank for temporary storage, and a sieve-substance as the first-stage cottonseed protein washing liquid enters the first-stage cottonseed protein washing liquid tank for temporary storage, and sequentially passes through the first to sixth-stage pressure curved screens for graded washing and screening, and the sieve-surface material obtained after washing and screening by each stage of the pressure curved screen is the cottonseed fiber, and the sieve-substance is the cottonseed protein washing liquid, and the sieve-surface material enters the next-stage pressure curved screen for washing and screening to obtain cottonseed protein separated from the cottonseed fiber, and finally the washed and screened cottonseed fiber is pumped out of the pressure curved screen group from the sixth-stage cottonseed fiber temporary storage tank (the first-stage cottonseed fiber with the highest cottonseed protein concentration gradually enters the sixth-stage cottonseed fiber temporary storage tank from the first stage, so the cottonseed protein concentration in the sixth-stage cottonseed fiber is the lowest), and then dehydrated and dried to obtain dry cottonseed fiber; The 2nd to 5th level pressure curved screens mainly play a washing role. The washing process of each level of pressure curved screen is to use the cottonseed protein washing liquid obtained by screening the next level of pressure curved screen to wash the screened material obtained by screening the previous level of pressure curved screen. The initial washing liquid is clean water, which is added from the 6th level pressure curved screen (from the 6th level underscreen cottonseed protein washing liquid tank to the 5th level overscreen cottonseed fiber tank, and pumped into the 6th level pressure curved screen surface for screening by the 5th level cottonseed fiber tank centrifugal pump). The screened material of the 5th level pressure curved screen is washed and screened to obtain the screened material as the 6th level cottonseed protein. The white washing liquid enters the fifth-stage cottonseed protein washing liquid tank for temporary storage, and the screened material is the sixth-stage cottonseed fiber which enters the sixth-stage cottonseed fiber tank for temporary storage. The cottonseed protein washing liquid is sequentially transported to the first-stage pressure curved screen through the sixth-stage pressure curved screen, and the screened material of the previous-stage pressure curved screen is washed and screened at the same time. The finally obtained cottonseed protein washing liquid is pumped out from the first-stage cottonseed protein washing liquid tank (according to the countercurrent principle, it gradually flows back from the sixth-stage cottonseed protein washing liquid tank to the first-stage cottonseed protein washing liquid tank, so the cottonseed protein concentration in the first-stage cottonseed protein washing liquid is the highest), and then concentrated to obtain cottonseed protein liquid II; S3, cottonseed protein hydrolyzate The cottonseed protein liquid I and the cottonseed protein liquid II obtained in the collecting step S2 are mixed and separated by a disc-type high-speed centrifuge (or a horizontal spiral sedimentation centrifuge), the liquid phase is the clean cottonseed protein liquid, and the solid phase is the cottonseed fiber residue. The clean cottonseed protein liquid is concentrated to a concentration of 23wt%, and then high-temperature hydrolysis (hydrolysis temperature is 75°C, hydrolysis pH is 4.6, and hydrolysis time is 40min), cooling, and then adjusting the pH to 4.0-6.5 for flocculation (flocculation temperature is 10°C, flocculation time is 10min) to obtain cottonseed protein, and the cottonseed protein is vacuum dehydrated, washed with water and then vacuum dehydrated to obtain cottonseed protein cake; S4, cottonseed protein hydrolysis The cottonseed protein cake obtained in step S3 is dissolved in water to prepare a mixed liquid with a concentration of 45wt%, heated to 90°C and maintained for 45min, then cooled to 45°C, the pH is adjusted to 8.5, alkaline protease, neutral protease, acidic protease, free cottonyphenol decomposing enzyme, keratinase and flavor protease are added in sequence for enzymolysis, the total enzyme addition amount in the mixed liquid is 4wt%, the composite ratio of the alkaline protease, neutral protease, acidic protease, free cottonyphenol decomposing enzyme, keratinase and flavor protease is 10:3:3:2:1:0.5, the enzymolysis time is 12h, the enzymolysis temperature is 55°C, and the mixture is heated and inactivated to obtain an enzymolysis peptide liquid; S5, concentration, drying The enzymatic peptide liquid obtained in step S4 is concentrated to a concentration of 49 wt %, and then filtered to remove impurities and solid particles. The liquid is spray-dried and heat-exchanged with 180° C. hot air. The inlet air temperature of the spray-drying is 190° C., and the exhaust air temperature is 90° C. to collect and obtain cottonseed peptide dry powder.

[0021] Test Example 1: Cottonseed peptide, cottonseed fiber physical and chemical properties and cottonseed fiber testing and results This test example tests the physical and chemical properties of the cottonseed peptides and cottonseed fibers prepared in Examples 1 to 3, and the test method is as follows: Table 1: Physical and chemical properties of cottonseed peptides and determination method of cottonseed fiber extraction rate

[0022] The results obtained according to the test method in Table 1 are shown in Table 2: Table 2: Physical and chemical properties of cottonseed peptides and cottonseed fiber extraction rate test results

[0023] As can be seen from the results in Table 2, the present invention adopts sulfurous acid to extract cottonseed protein, and uses gravity curved screen to separate cottonseed hulls, pressure curved screen to separate cottonseed fiber and cottonseed protein, cottonseed protein is hydrolyzed and enzymolyzed by complex enzymes, and cottonseed protein hydrolysate is concentrated and then spray-dried to obtain a cottonseed peptide with a proportion of oligopeptides less than 1000 Dalton exceeding 82%, a free cottonyphenol content of less than 400 mg / kg and a removal rate of up to 85%, an extraction rate of up to 50.2%, and a cottonseed fiber extraction rate of up to 48.1-55.4%. The prepared cottonseed peptide can be golden yellow, has no bitterness, and has a fresh and sweet taste. It can be widely used in animal feed, functional food, biological culture medium and enzyme synthesis, biodegradable materials, cosmetics and pharmaceuticals, and is safe and has no toxic side effects.

[0024] Comparative Example 1 The difference between the extraction process of this comparative example and that of Example 3 is that the composite enzyme used in the enzymatic hydrolysis process in the preparation step S4 is different, the total enzyme addition amount is the same, and the composite enzyme formula is: the composite ratio of alkaline protease, neutral protease, free cottonyphenol decomposing enzyme, and keratinase is 11:3.5:3.5:2.5; the remaining steps are consistent with Example 3.

[0025] Comparative Example 2 The difference between the extraction process of this comparative example and that of Example 3 is that the composite enzyme used in the enzymatic hydrolysis process in the preparation step S4 is different, the total enzyme addition amount is the same, and the composite enzyme formula is: the composite ratio of alkaline protease, neutral protease, acidic protease, free cottonyphenol decomposing enzyme, keratinase, and flavor protease is 5:5:10:3:2:0.5, and the remaining steps are consistent with Example 3.

[0026] Comparative Example 3 The difference between the extraction process of this comparative example and that of Example 3 is that the sieve gaps of the 1# two-stage series gravity curved sieve in step S2 are 40 mm (larger than the size of wet large cotton hulls) and 20 mm (larger than the size of wet small and medium cotton hulls), respectively, the sieve gap of the 1# pressure curved sieve is 80 μm (smaller than the size of wet cottonseed fiber), the first-stage sieve surface of the 2# pressure curved sieve group is 30 μm, the sieve gaps of the 2nd to 5th stage pressure curved sieves are 50 μm, and the sieve gap of the 6th stage pressure curved sieve is 35 μm, and the remaining steps are consistent with Example 3.

[0027] Comparative Example 4 The difference between the extraction process of this comparative example and that of Example 3 is that the countercurrent washing process of step S2 only performs the first-stage pressure curved sieve screening process, omitting the second to sixth-stage pressure curved sieve screening steps, and the remaining steps are consistent with Example 3.

[0028] Comparative Example 5 The extraction process of this comparative example is different from that of Example 3 in that an aqueous solution of sodium sulfite is used for leaching instead of an aqueous solution of sulfurous acid, and the remaining steps are the same as those of Example 3.

[0029] Test Example 2: Physical and Chemical Properties of Cottonseed Peptide and Cottonseed Fiber and Results This test example tests the physical and chemical properties of the cottonseed peptides prepared in Comparative Examples 1 to 5 and the cottonseed fiber extraction rate. The test method is the same as that of Test Example 1. The test results are shown in Table 3. Table 3: Physical and chemical properties of cottonseed peptides and cottonseed fiber extraction rate test results

[0030] As can be seen from the results in Table 3, by adjusting the extraction solution, the composition and ratio of the composite enzyme, adjusting the process parameters such as the gravity curved screen and the pressure curved screen, the crude protein content, acid-soluble protein content, free gossypol content, extraction rate, molecular weight distribution, appearance, taste, etc. of the cottonseed enzymatic protein (cottonseed peptide) product are greatly affected. Among them, Comparative Examples 1 and 2 use composite enzyme compositions or ratios different from those in Example 3 for enzymatic hydrolysis, and the acid-soluble protein content in the obtained cottonseed peptides is reduced by about 2-5%, while the proportion of oligopeptides less than 1000 Daltons in Comparative Example 1 is reduced by 9.5%, and the oligopeptide content in Comparative Example 2 is low. It can be seen that the composition and content of the composite enzyme in the preparation process of the present invention are very critical to the oligopeptide; Comparative Examples 3 and 4 adjust the curved screen process parameters and the countercurrent washing procedure in the preparation process, and it is found that the sieve gaps of the gravity curved screen and the pressure curved screen cause the cottonseed peptide extraction rate to decrease, and the protein content decreases to a certain extent; Comparative Example 5 uses sodium sulfite for extraction, and the cottonseed peptide and acid-soluble protein content are significantly reduced, and part of the pigment cannot be removed.

[0031] To simplify the description, the above-mentioned embodiments only express several implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. Without contradiction, technicians in this field can combine and combine the different embodiments and features of different embodiments described in this specification. Under the premise of not departing from the concept of the present invention, the several improvements made belong to the protection scope of the present invention.

Claims

1. A process for extracting cottonseed peptides and cottonseed fibers, characterized in that: The following steps are involved: S1. Extraction with sulfurous acid aqueous solution soaking cottonseed meal and / or cottonseed protein powder in a sulfurous acid aqueous solution to obtain a cottonseed meal soaking liquid; S2, cottonseed fiber, cottonseed protein separation The cottonseed meal soaking liquid obtained in step S1 is sequentially processed through a 1# impact pin mill and a 1# two-stage series gravity curved screen to obtain wet cotton hulls and cottonseed protein liquid containing cottonseed fibers, wherein the sieve gaps of the 1# two-stage series gravity curved screen are 30-50 mm and 30-10 mm respectively; then the cottonseed protein liquid containing cottonseed fibers is sequentially processed through a 2# impact pin mill and a 1# pressure curved screen with a sieve gap of 100-150 μm, and sieved to obtain wet cottonseed fibers and cottonseed protein liquid I; then the wet cottonseed fibers are sent to a 2# pressure curved screen group for countercurrent washing, wherein the 2# pressure curved screen group comprises 1 to 6 levels of pressure curved screens, wherein the sieve gaps of the 1st and 6th levels of pressure curved screens are 30-50 μm, and the sieve gaps of the 2nd to 5th levels of pressure curved screens are 60-150 μm; The wet cottonseed fiber is added from the first-stage pressure curved screen, and is washed and screened through the first to sixth-stage pressure curved screens in sequence. After washing and screening through each stage of the pressure curved screen, the screened material is the cottonseed fiber, and the screened material is the cottonseed protein washing liquid. Finally, the washed and screened cottonseed fiber is output from the sixth-stage pressure curved screen, and then dehydrated and dried to obtain dry cottonseed fiber. The washing process of each level of pressure curved screen is to use the cottonseed protein washing liquid obtained by screening the next level of pressure curved screen to wash the screened material obtained by screening the previous level of pressure curved screen. The initial washing liquid is clean water, which is added from the 6th level of pressure curved screen. The screened material of the 5th level of pressure curved screen is washed to obtain the 6th level of cottonseed protein washing liquid, which is passed through the 6th level to the 1st level of pressure curved screen in sequence and the screened material of the previous level of pressure curved screen is washed. The finally obtained cottonseed protein washing liquid is output from the 1st level of pressure curved screen and then concentrated to obtain cottonseed protein liquid II. S3, cottonseed protein post-processing The cottonseed protein liquid I and the cottonseed protein liquid II obtained in step S2 are mixed and sequentially subjected to hydrolysis, flocculation, washing and dehydration to obtain cottonseed protein cakes; the cottonseed protein cakes are redissolved in water and then enzymatically hydrolyzed with a composite enzyme to obtain enzymatic peptide liquid; the enzymatic peptide liquid is spray-dried and heat-exchanged with hot air to collect cottonseed peptides.

2. The process for extracting cottonseed peptides and cottonseed fibers according to claim 1, characterized in that: The mass concentration of the sulfurous acid aqueous solution in step S1 is 0.05-2.5%, and the material-liquid ratio is 1 g:3-20 mL.

3. The process for extracting cottonseed peptides and cottonseed fibers according to claim 1, characterized in that: In step S2, the rotation speed of the 1# impact pin mill and the 2# impact pin mill is 3000-5000 r / min; the screen surface curvature of the 1# two-stage series gravity curved screen is 50°-60°; the screen surface curvature of the 1# pressure curved screen and the 2# pressure curved screen group is 120°-300°, the feed pressure is 0.18-0.42 Mpa, the nozzle diameter is 1 / 2-3 / 4 inch, and the nozzle flow rate is 9.1-20.5 m 3 / h.

4. The process for extracting cottonseed peptides and cottonseed fibers according to claim 1, characterized in that: In the step S3, the hydrolysis temperature is 70-121° C., the hydrolysis time is 8 s-45 min, the hydrolysis pH is 4.5-9.0, the flocculation is to adjust the pH to 3.0-6.5 for flocculation precipitation, the flocculation temperature is 5-75° C., and the flocculation time is 5-60 min.

5. The process for extracting cottonseed peptides and cottonseed fibers according to claim 1, characterized in that: In step S3, the composite enzyme is a mixture of alkaline protease, neutral protease, acidic protease, free cottonyphenol decomposing enzyme, keratinase and flavor protease, and the mass ratio of the alkaline protease, neutral protease, acidic protease, free cottonyphenol decomposing enzyme, keratinase and flavor protease is 10-15:3-5:3-5:2-4:1-2:0.5-3.

6. The process for extracting cottonseed peptides and cottonseed fibers according to claim 1, characterized in that: The amount of the complex enzyme added in step S3 is 0.1-5 wt %.

7. The process for extracting cottonseed peptides and cottonseed fibers according to claim 1, characterized in that: In step S3, the inlet air temperature of the spray drying is 120-190°C, the exhaust air temperature is 50-90°C, and the hot air temperature is 170-210°C.

8. Use of the cottonseed fiber obtained by the extraction process of the cottonseed peptide and cottonseed fiber according to any one of claims 1 to 7 in animal feed, functional food, biodegradable materials and cosmetics.

9. The cottonseed peptide obtained by the extraction process of cottonseed peptide and cottonseed fiber according to any one of claims 1 to 7, characterized in that: The crude protein content of the cottonseed peptide exceeds 65%, the acid-soluble protein content in the crude protein exceeds 62%, the content of oligopeptides with a molecular weight lower than 1000 Dalton in the cottonseed peptide exceeds 82%, and the free cottonpol content is lower than 400 mg / kg.

10. Use of the cottonseed peptide according to claim 9 in animal feed, functional food, biological culture medium and enzyme synthesis, cosmetics and medicine.

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