High-quality rapeseed protein and rapeseed dietary fiber as well as synchronous preparation method and application thereof

Abstract

The invention belongs to the technical field of comprehensive utilization of rapeseed cakes, and particularly relates to high-quality rapeseed protein and rapeseed dietary fiber as well as a synchronous preparation method and application thereof. The rapeseed cake meal is firstly subjected to coarse grinding pretreatment, crushing and sieving are not needed, and more energy conservation and environmental protection are achieved. And dispersing the roughly ground rapeseed meal in a good solvent by adopting a good solvent washing and scale control synchronous sieving technology, passing through a scale-controllable sieve, washing oversize products by using the good solvent, and finally synchronously obtaining a protein crude extract and dietary fibers so as to realize convenient preparation of the rapeseed dietary fibers. Furthermore, the rapeseed protein crude extract is subjected to weak acid enrichment after being subjected to homogenization treatment, so that the protein yield is increased. And a weak acid synchronous gradient membrane separation technology is further adopted, and the problem of too slow concentration or equipment blockage caused by rapid aggregation is prevented by regulating and controlling the structural characteristics and aggregation behavior of the protein, so that the protein concentration degree is improved, and the rapeseed protein with high yield and high quality is finally obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of comprehensive utilization of rapeseed meal, and specifically relates to high-quality rapeseed protein and rapeseed dietary fiber, and a synchronous preparation method and application thereof. Background Art

[0002] Rapeseed meal is a byproduct of rapeseed oil extraction, which is rich in protein (~40%), has a reasonable amino acid composition, high nutritional value, and can increase the protein level in plant-based foods. Therefore, as a high-quality sustainable plant protein source, the relevant products of Burcon and DSM have been approved by FDA and EFSA as recognized safe new food resource raw materials. Rapeseed protein is gradually shifting from animal to human nutrition market, with huge development potential.

[0003] At the same time, with the improvement of living standards, the degree of food refinement is getting higher and higher, resulting in the increasing incidence of diseases related to insufficient dietary fiber intake, such as colorectal cancer, constipation, intestinal polyps, etc. As the seventh type of nutrient, dietary fiber has the functions of promoting intestinal peristalsis and treating constipation. Rapeseed meal contains rich dietary fiber (~30%), which has great potential in meeting the effective supply of dietary fiber.

[0004] Therefore, the deep processing technology of rapeseed meal and the simultaneous processing technology of protein and dietary fiber in rapeseed meal have become technical challenges that urgently need to be broken through.

[0005] However, the main problem hindering the high value-added application of rapeseed meal is that rapeseed meal contains toxic or anti-nutritional substances such as glucosinolates and phytic acid. In addition, problems such as protein denaturation or dietary fiber loss may be encountered during the simultaneous extraction process. In particular, during the extraction process, the structure of protein and dietary fiber may be destroyed or the functionality may be reduced due to high energy input or improper chemical treatment.

[0006] Therefore, it is of great significance to develop a synchronous preparation method that can improve the quality and extraction rate of rapeseed protein and rapeseed dietary fiber based on the content and functional properties of rapeseed protein and rapeseed dietary fiber in rapeseed meal. Summary of the invention

[0007] In view of this, in order to solve the problems existing in the prior art, the present invention pre-grinds the defatted rapeseed meal, and then adopts a good solvent washing synchronous scale-controlled screening technology, disperses the coarsely ground rapeseed meal in a good solvent and passes it through a scale-controllable sieve, and then washes the sieve material with a good solvent, and finally obtains rapeseed protein crude extract and rapeseed dietary fiber synchronously, and further homogenizes the rapeseed protein crude extract, weak acid enrichment, and solid-liquid separation, and then uses weak acid synchronous gradient membrane separation technology to obtain rapeseed protein with both high quality and high yield. The present invention not only effectively improves the continuity of the synchronous preparation process of rapeseed protein and rapeseed dietary fiber, improves the quality and yield of rapeseed protein and rapeseed dietary fiber, but also is more energy-saving and environmentally friendly compared to the existing methods of preparing rapeseed protein and rapeseed dietary fiber separately, and conforms to the concepts of moderation, greenness, and low carbon.

[0008] In order to achieve the above object, the present invention adopts the following technical solution:

[0009] A method for simultaneously preparing high-quality rapeseed protein and rapeseed dietary fiber, comprising the steps of dispersing coarsely ground defatted rapeseed cake with a good solvent and then sieving the cake, then washing and sieving the cake with a good solvent, thereby simultaneously obtaining a rapeseed protein crude extract and rapeseed dietary fiber, and then further processing the rapeseed protein crude extract to obtain rapeseed protein.

[0010] After sieving, the undersize is the rapeseed protein crude extract, and the oversize is the rapeseed dietary fiber. In addition, considering the actual use and storage requirements of the rapeseed dietary fiber, the oversize obtained by the present invention is dried to obtain the rapeseed dietary fiber of common specifications.

[0011] It is worth noting that in order to improve the extraction rate of rapeseed protein and rapeseed dietary fiber, destroying the cell wall of rapeseed meal and increasing the specific surface area of ​​the powder is an effective way. The existing technology uses ultrafine grinding technology to assist the deep processing of rapeseed meal. However, ultrafine grinding technology will lead to high energy consumption on the one hand, and on the other hand, it will be limited in one-time processing capacity due to the small design of the grinding chamber, which is not suitable for large-scale production needs. In addition, the material agglomeration caused by ultrafine grinding will affect the quality stability and consistency of the final product.

[0012] In order to avoid the above problems and meet the needs of green and environmentally friendly production, the present invention changes the pretreatment idea, performs coarse grinding on the defatted rapeseed meal, does not require crushing and screening, saves energy, and is more environmentally friendly. The extraction rate of rapeseed protein and rapeseed dietary fiber, the preservation of natural structure, and the improvement of functional characteristics are ensured by good solvent washing and synchronous scale control screening technology.

[0013] Furthermore, the present invention adopts good solvent washing and synchronous scale-controlled screening technology to quickly disperse the protein in the good solvent and control the screening scale, and can simultaneously obtain the crude protein extract and rapeseed dietary fiber, and can very conveniently separate the soluble and insoluble rapeseed dietary fiber from the rapeseed cake.

[0014] Furthermore, the good solvent is a 100-500 mM salt solution, and the salt of the good solvent is selected from a combination of one or more of CaCl2 and MgCl2.

[0015] It is worth noting that, since phytic acid can chelate with divalent metal ions under weak acid conditions to obtain rapeseed protein with low phytic acid content, the present invention selects a combination of one or more of CaCl2 and MgCl2 as a good solvent. The concentration of the good solvent is limited to 100-500mM in order to avoid salting out reaction blocking the membrane. In particular, the present invention uses a good solvent to disperse and dissolve most of the protein, and the good solvent rinse can wash the protein more completely off the sieve to increase the yield of rapeseed protein.

[0016] Furthermore, the mesh size of the sieving is 60-200 meshes.

[0017] It is worth noting that if the mesh number is <60, the gap is too large and some rapeseed dietary fiber will enter the sieve, which is not conducive to the enrichment of rapeseed dietary fiber and the subsequent extraction and separation of protein; if the mesh number is >200, the gap is too small, the protein is suspended in the good solvent, and larger protein particles cannot pass through, which is not conducive to the subsequent improvement of protein extraction rate. Only when the mesh number is appropriate and the good solvent is washed simultaneously, can it be beneficial to the simultaneous separation of protein and rapeseed dietary fiber and improve the extraction rate of each product.

[0018] In addition, the conventional rapeseed dietary fiber extraction methods such as chemical separation method and enzyme-assisted extraction method require the use of organic reagents, high temperature, high pressure, enzyme or equipment-assisted extraction. The present invention only requires the rapeseed meal to be coarsely ground and then dispersed and sieved with a good solvent to obtain the rapeseed dietary fiber, which is more energy-saving and easy to operate than the conventional methods. Compared with the yield of the rapeseed dietary fiber chemical separation method (about 60%), the yield of the rapeseed fiber in the synchronous preparation method disclosed in the present invention is about 67%, which has a higher yield and economic benefits.

[0019] Furthermore, the present invention adopts a synchronous preparation method of rapeseed protein and rapeseed dietary fiber. The synchronous process used has strong continuity, energy conservation and environmental protection, and is more in line with the concept of moderation, greenness and low carbon.

[0020] Furthermore, the method for further processing the crude rapeseed protein extract is:

[0021] The crude rapeseed protein extract is homogenized and then enriched with weak acid, and the pH is controlled at 5.0-7.0. Centrifugation is then performed, and the supernatant is further separated into solid and liquid. The liquid is retained and concentrated using weak acid synchronous gradient membrane separation technology to obtain a highly concentrated protein solution. The pH value of the highly concentrated protein solution is then adjusted to 7 and freeze-dried to obtain high-quality rapeseed protein.

[0022] It is worth noting that homogenizing the crude extract of rapeseed protein is helpful for breaking protein particles. Weak acid enrichment is used and the pH of the system is controlled to be 5.0-7.0. This is mainly because glucosinolates are easily hydrolyzed under weak acid conditions, and the protein is weakly bound to phytic acid, which is more conducive to protein enrichment and separation from substances such as phytic acid and glucosinolates, thereby improving the yield and the quality of protein. In addition, the gradient membrane separation of the present invention, which maintains a weak acid environment, is conducive to the removal of toxic or anti-nutritional substances such as glucosinolates, phytic acid, pigments, polyphenols, etc., and can control the structural characteristics and aggregation behavior of the protein, thereby facilitating the improvement of the color, edible quality and functional characteristics of rapeseed protein.

[0023] Furthermore, the gradient concentration and purification method is:.

[0024] The liquid after solid-liquid separation is moved into the sample processing chamber and begins to be concentrated using membrane separation technology, and the pH of the treatment system is maintained between 5.0 and 7.0. After the liquid volume is concentrated to 1 / 2 of the initial volume, good solvent a is added to the sample processing chamber to replenish the liquid volume to the initial volume, and the concentration is continued; after the liquid volume in the sample chamber is concentrated to 1 / 2 of the initial volume again, good solvent b is added to the sample processing chamber to replenish the liquid volume to the initial volume, and the concentration is continued; after the liquid volume in the sample chamber is concentrated to 1 / 2 of the initial volume again, good solvent c is added to the sample processing chamber to replenish the liquid volume to the initial volume, and the concentration is continued; after the liquid volume in the sample chamber is concentrated to 1 / 2 of the initial volume again, good solvent d is added to the sample processing chamber to replenish the liquid volume to the initial volume, and the concentration is continued; repeat the above steps until the concentration of the good solvent added to the sample processing chamber is in the range of 20 to 40 mM at a certain time, after the liquid in the sample processing chamber is concentrated to 1 / 2 of the initial volume again, ultrapure water is added to replenish the liquid volume in the sample processing chamber to the initial volume, and the concentration is continued to 1 / 8 of the initial volume to obtain a highly concentrated liquid.

[0025] It is worth noting that the present invention utilizes gradient concentration to control the removal rate of salt ions, thereby controlling the protein structural characteristics and aggregation behavior, preventing problems such as slow concentration or equipment blockage caused by rapid aggregation, thereby improving the degree of protein concentration, and ultimately obtaining rapeseed protein with both high yield and high quality.

[0026] Furthermore, the concentration of the good solvent a is 40% to 60% of the good solvent, the concentration of the good solvent b is 20% to 30% of the good solvent, the concentration of the good solvent c is 10% to 15% of the good solvent, and the concentration of the good solvent d is 5% to 8% of the good solvent.

[0027] In some embodiments, when the initial good solvent concentration used is 500mM, after the liquid volume in the sample chamber is concentrated to 1 / 2, 200-300mM good solvent is added to make up the liquid volume to the initial volume; after the liquid volume in the sample chamber is concentrated to 1 / 2 again, 100-150mM good solvent is added to make up the liquid volume to the initial volume; after the liquid volume in the sample chamber is concentrated to 1 / 2 again, 50-75mM good solvent is added to make up the liquid volume to the initial volume; after the liquid volume in the sample chamber is concentrated to 1 / 2 again, 25-40mM good solvent is added to make up the liquid volume to the initial volume; after the liquid volume in the sample chamber is concentrated to 1 / 2 again, ultrapure water is added to make up the liquid volume to the initial volume, and the concentration is continued to 1 / 8 of the initial volume to obtain a highly concentrated liquid.

[0028] Furthermore, the membrane molecular weight of the membrane separation is 5-30 kDa.

[0029] The present invention applies membrane separation technology to gradient concentration and purification treatment. On the one hand, it can purify and concentrate the dissolved protein liquid in rapeseed cake and remove toxic or anti-nutritional substances such as glucosinolates, polyphenols and phytic acid; on the other hand, it can also effectively control the protein retention size, structural characteristics and aggregation behavior, thereby improving the yield and quality of the target protein.

[0030] Furthermore, the preparation method also includes weak acid enrichment of the rapeseed protein crude extract, adding activated carbon for treatment, and then centrifuging.

[0031] It is worth noting that the present invention adds activated carbon treatment after weak acid enrichment treatment, which can adsorb bad coloring substances to make rapeseed protein have a high whiteness value on the one hand, and can also simultaneously adsorb part of phytic acid and glucosinolates in rapeseed protein on the other hand. Compared with other oilseed cake deep processing technologies that only use activated carbon as a decolorizer, the present invention aims at the characteristic problem that rapeseed meal contains toxic or anti-nutritional substances such as glucosinolates, polyphenols and phytic acid, and adds activated carbon to remove glucosinolates and phytic acid, which can effectively improve the high added value application of rapeseed cake.

[0032] In summary, in order to solve many problems in traditional technologies, for example, in the traditional rapeseed protein extraction process, rapeseed cake usually needs to be crushed with a grinder and sieved to obtain rapeseed meal powder. This process will generate a lot of energy consumption, and the rapeseed cake will generate a lot of dust after crushing, causing environmental pollution. The traditional alkali extraction and acid precipitation method for extracting rapeseed protein has the disadvantages of low extraction rate, poor color, high content of anti-nutritional factors, and the functional characteristics of the prepared rapeseed protein are biased. For another example, the existing rapeseed dietary fiber extraction technology mostly requires the use of organic reagents or high temperature and high pressure conditions, and the extraction process is complicated and energy-intensive.

[0033] The present invention firstly performs a rough grinding pretreatment on the rapeseed meal, and does not need to be crushed and screened, which is more energy-saving and environmentally friendly. Then, a good solvent washing and synchronous scale control screening technology is adopted, and the coarsely ground rapeseed meal is dispersed in a good solvent and passed through a scale-controllable sieve, and then the sieve material is washed with a good solvent, and finally, a rapeseed protein crude extract (screen material) and rapeseed dietary fiber (screen material) are obtained synchronously, so as to realize the convenient preparation of rapeseed dietary fiber. Then, the rapeseed protein crude extract is homogenized to break the protein particles, and then weak acid enrichment is performed to improve the protein yield. The liquid after solid-liquid separation is further separated by weak acid synchronous gradient membrane separation technology, and the protein structural characteristics and aggregation behavior are regulated to prevent the problem of slow concentration or equipment blockage caused by rapid aggregation, thereby improving the protein concentration degree, and finally obtaining rapeseed protein with high yield and high quality.

[0034] And, the second object of the present invention is to provide a rapeseed protein or rapeseed dietary fiber obtained by the preparation method as described above.

[0035] It is worth noting that the rapeseed protein obtained by the preparation method disclosed in the present invention has a high recovery rate and high protein purity, good color, and low content of anti-nutritional factors such as glucosinolates and phytic acid, compared with the rapeseed protein obtained by the traditional alkali dissolution and acid precipitation method, which meets the EU edible rapeseed protein standard, has good foaming and solubility, and has good industrial application capabilities. The rapeseed dietary fiber prepared synchronously not only has fewer extraction steps, but is also more environmentally friendly than the existing preparation process, and has great industrial advantages in terms of yield and purity among similar products.

[0036] And, the third object of the present invention is to provide a use of the above rapeseed protein or rapeseed dietary fiber in dietary protein or fiber supplements, food ingredients, foaming agents, and rapeseed protein / fiber-based foods.

[0037] It is worth noting that, considering that the rapeseed protein disclosed in the present invention has good color, low content of anti-nutritional factors such as glucosinolates and phytic acid, good edible quality, and combined with the resource advantages of rapeseed meal, the rapeseed protein is a good source of dietary protein supplement. In particular, the rapeseed protein prepared by the present invention has a foaming property of up to 302%, which is higher than that of plant proteins such as soy protein and pea protein, and comparable to sodium caseinate from animal sources. In addition, rapeseed protein replaces egg white as a foaming agent for cake products, and as a plant-based food, which is friendly to vegetarians and people with egg allergies, and has excellent food application advantages.

[0038] Compared with the prior art, the synchronous preparation method of high-quality rapeseed protein and rapeseed dietary fiber disclosed in the present invention utilizes good solvent washing synchronous scale control screening technology. On the one hand, the protein is quickly dispersed in the good solvent and the screening scale is controlled. While obtaining the protein pre-rough extract and rapeseed dietary fiber simultaneously, the soluble and insoluble rapeseed dietary fiber can be separated from the rapeseed meal very conveniently; on the other hand, the continuity of the synchronous process is improved, energy-saving and environmentally friendly, and in line with the concept of moderation, greenness, and low carbon. In addition, the present invention also utilizes gradient membrane separation technology to further process the homogenized and weakly acid enriched rapeseed protein crude extract. Under weakly acid conditions, gradient membrane separation is beneficial to the removal of small molecules such as glucosinolates and phytic acid, and the structure and aggregation behavior of the protein can be controlled, which is beneficial to the preparation of high-quality rapeseed protein. In addition, weakly acid enrichment coupled with activated carbon treatment can not only effectively remove components such as pigments and polyphenols, but also be beneficial to the separation of toxic or anti-nutritional substances such as glucosinolates and phytic acid, and can effectively regulate the protein structure, which is beneficial to the improvement of subsequent protein functional properties. The obtained high-yield and high-quality rapeseed protein and rapeseed dietary fiber have great application potential in the fields of dietary protein or fiber supplements, food ingredients, foaming agents, and rapeseed protein / fiber-based foods. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] 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, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0040] Figure 1 The present invention is a schematic diagram of the process of the simultaneous preparation method of high-quality rapeseed protein and rapeseed dietary fiber.

[0041] Figure 2 This is the appearance of the rapeseed protein of Comparative Example 1 and Experimental Examples 1-7 in Experimental Example 3 of the present invention. DETAILED DESCRIPTION

[0042] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] The word "embodiment" used here as an "exemplary" does not necessarily mean that any embodiment described is superior to or better than other embodiments. Unless otherwise specified, the performance index tests in the embodiments of this application are performed using conventional test methods in the art. It should be understood that the terms described in this application are only used to describe specific implementation methods and are not used to limit the content disclosed in this application.

[0044] Unless otherwise specified, the technical and scientific terms used in this document have the same meanings as commonly understood by ordinary technicians in the technical field to which this application belongs; other experimental methods and technical means not specifically specified in this application refer to experimental methods and technical means commonly used by ordinary technicians in this field.

[0045] In order to better illustrate the content of the present application, numerous specific details are provided in the specific examples below. It should be understood by those skilled in the art that the present application can also be implemented without certain specific details. In the embodiments, some methods, means, instruments, equipment, etc. well known to those skilled in the art are not described in detail in order to highlight the main purpose of the present application.

[0046] Under the premise of no conflict, the technical features disclosed in the embodiments of the present application can be combined arbitrarily, and the resulting technical solutions belong to the contents disclosed in the embodiments of the present application.

[0047] The invention discloses a high-quality rapeseed protein and rapeseed dietary fiber and a synchronous preparation method and application thereof, and belongs to the technical field of comprehensive utilization of rapeseed meal. The invention firstly performs a rough grinding pretreatment on the rapeseed meal, and does not need to be crushed and screened, which is more energy-saving and environmentally friendly. Then, a good solvent washing synchronous scale control screening technology is adopted, and the coarsely ground rapeseed meal is dispersed in a good solvent and passed through a scale-controllable sieve, and then the sieve material is washed with a good solvent, and finally, a rapeseed protein crude extract (screen material) and rapeseed dietary fiber (screen material) are obtained synchronously, so as to realize the convenient preparation of rapeseed dietary fiber. Then, the rapeseed protein crude extract is homogenized to break the protein particles, and then weak acid enrichment is performed to improve the protein yield. The liquid after solid-liquid separation is further subjected to weak acid synchronous gradient membrane separation technology, and the protein structural characteristics and aggregation behavior are regulated to prevent the problem of slow concentration or equipment blockage caused by rapid aggregation, thereby improving the protein concentration degree, and finally obtaining rapeseed protein with both high yield and high quality.

[0048] In order to better understand the present invention, the present invention is further specifically described below through the following examples, but it should not be understood as a limitation of the present invention. Some non-essential improvements and adjustments made by technicians in this field based on the above invention content are also considered to fall within the protection scope of the present invention.

[0049] Example 1

[0050] The defatted rapeseed meal was coarsely ground in a mortar and then dispersed in a 100 mM calcium chloride aqueous solution at a ratio of 1:8 (w / v), stirred at room temperature (25°C) for 30 min, sieved with a 200-mesh sieve, and then rinsed with the same volume of calcium chloride aqueous solution. The material below the sieve was the crude protein extract, and the material above the sieve was the crude rapeseed dietary fiber extract.

[0051] Then the crude protein extract was homogenized at 13800rpm for 2min to make it more evenly dispersed, and the pH was controlled to 5.8 with HCl. After stirring at room temperature for 60min, it was centrifuged at 10000g for 30min to collect the supernatant. The supernatant was further separated into solid and liquid and the liquid was collected. The liquid after solid-liquid separation was then transferred to the sample chamber of the membrane separation device, and the filtrate was concentrated using weak acid synchronous gradient membrane separation technology. The membrane used was MWCO 10KDa. The membrane was prepared, and after concentrating to 1 / 2 of the initial volume of the filtrate, 50 mM calcium chloride solution was added to the sample chamber to the initial volume of the filtrate, and then concentrated to 1 / 2 of the initial volume of the filtrate, 25 mM calcium chloride solution was added to the initial volume of the filtrate, and then concentrated to 1 / 2 of the initial volume of the filtrate, ultrapure water was added to the initial volume of the filtrate, and the highly concentrated solution was taken out after concentrating to 1 / 8 of the initial volume of the filtrate, and its pH was adjusted to 7.0 and freeze-dried for 72 hours to obtain rapeseed protein isolate, which is Example 1.

[0052] Example 2

[0053] The defatted rapeseed meal was coarsely ground in a mortar and then dispersed in a 100 mM calcium chloride aqueous solution at a ratio of 1:8 (w / v), stirred at room temperature (25°C) for 30 min, sieved with a 60-mesh sieve, and then rinsed with the same volume of calcium chloride aqueous solution. The material below the sieve was the crude protein extract, and the material above the sieve was the crude rapeseed dietary fiber extract.

[0054] Then the crude protein extract was homogenized at 13800rpm for 2min to make it more evenly dispersed, and the pH was controlled to 5.8 with HCl, stirred at room temperature for 30min, and 1% activated carbon was added and stirred for 30min, then centrifuged at 10000g for 30min, and the supernatant was collected. The supernatant was further separated into solid and liquid, and the liquid was collected. The filtrate was then transferred to the sample chamber of the membrane separation device, and the filtrate was concentrated using weak acid synchronous gradient membrane separation technology. The membrane used was MWCO 10KDa. The membrane was prepared, and after concentrating to 1 / 2 of the initial volume of the filtrate, 50 mM calcium chloride solution was added to the sample chamber to the initial volume of the filtrate, and then concentrated to 1 / 2 of the initial volume of the filtrate, 25 mM calcium chloride solution was added to the initial volume of the filtrate, and then concentrated to 1 / 2 of the initial volume of the filtrate, and ultrapure water was added to the initial volume of the filtrate. After concentrating to 1 / 8 of the initial volume of the filtrate, the highly concentrated solution was taken out, the pH value was adjusted to 7.0, and then freeze-dried for 72 hours to obtain rapeseed protein isolate, which is Example 2.

[0055] Example 3

[0056] The defatted rapeseed meal was coarsely ground in a mortar and then dispersed in a 100 mM calcium chloride aqueous solution at a ratio of 1:8 (w / v), stirred at room temperature (25°C) for 30 min, sieved with a 200-mesh sieve, and then rinsed with the same volume of calcium chloride aqueous solution. The material below the sieve was the crude protein extract, and the material above the sieve was the crude rapeseed dietary fiber extract.

[0057] Then the crude protein extract was homogenized at 13800rpm for 2min to make it more evenly dispersed, and the pH was controlled to 5.0 with HCl, stirred at room temperature for 30min, and 1% activated carbon was added and stirred for 30min, then centrifuged at 10000g for 30min, and the supernatant was collected. The supernatant was further separated into solid and liquid, and the liquid was collected. The filtrate was then transferred to the sample chamber of the membrane separation device, and the filtrate was concentrated using weak acid synchronous gradient membrane separation technology. The membrane used was MWCO 10KDa. The membrane was prepared, and after concentrating to 1 / 2 of the initial volume of the filtrate, 50 mM calcium chloride solution was added to the sample chamber to the initial volume of the filtrate, and then concentrated to 1 / 2 of the initial volume of the filtrate, 25 mM calcium chloride solution was added to the initial volume of the filtrate, and then concentrated to 1 / 2 of the initial volume of the filtrate, ultrapure water was added to the initial volume of the filtrate, and the highly concentrated solution was taken out after concentrating to 1 / 8 of the initial volume of the filtrate, and the pH thereof was adjusted to 7.0 and freeze-dried for 72 hours to obtain rapeseed protein isolate, which is Example 3.

[0058] Example 4

[0059] The defatted rapeseed meal was coarsely ground in a mortar and then dispersed in a 100 mM magnesium chloride aqueous solution at a ratio of 1:8 (w / v), stirred at room temperature (25°C) for 30 min, sieved with a 200-mesh sieve, and then rinsed with the same volume of magnesium chloride aqueous solution. The material below the sieve was the crude protein extract, and the material above the sieve was the crude rapeseed dietary fiber extract.

[0060] Then the crude protein extract was homogenized at 13800rpm for 2min to make it more evenly dispersed, and the pH was controlled to 7.0 with HCl, stirred at room temperature for 30min, and 1% activated carbon was added and stirred for 30min, then centrifuged at 10000g for 30min, and the supernatant was collected. The supernatant was further separated into solid and liquid, and the liquid was collected. The filtrate was then transferred to the sample chamber of the membrane separation device, and the filtrate was concentrated using weak acid synchronous gradient membrane separation technology. The membrane used was MWCO 5KDa. The membrane was prepared, and 50 mM magnesium chloride solution was added to the sample chamber to the initial volume of the filtrate after concentrating to 1 / 2 of the initial volume of the filtrate, and 25 mM magnesium chloride solution was added to the initial volume of the filtrate after concentrating to 1 / 2 of the initial volume of the filtrate, and ultrapure water was added to the initial volume of the filtrate after concentrating to 1 / 2 of the initial volume of the filtrate, until it was concentrated to 1 / 8 of the initial volume of the filtrate, and then the highly concentrated solution was taken out, its pH was adjusted to 7.0, and then freeze-dried for 72 hours to obtain rapeseed protein isolate, which is Example 4.

[0061] Example 5

[0062] The defatted rapeseed meal was coarsely ground in a mortar and then dispersed in a 100 mM calcium chloride aqueous solution at a ratio of 1:8 (w / v), stirred at room temperature (25°C) for 30 min, sieved with a 200-mesh sieve, and then rinsed with the same volume of calcium chloride aqueous solution. The material below the sieve was the crude protein extract, and the material above the sieve was the crude rapeseed dietary fiber extract.

[0063] Then the crude protein extract was homogenized at 13800rpm for 2min to make it more evenly dispersed, and the pH was controlled to 5.8 with HCl, stirred at room temperature for 30min, and 1% activated carbon was added and stirred for 30min, then centrifuged at 10000g for 30min, and the supernatant was collected. The supernatant was further separated into solid and liquid, and the liquid was collected. The filtrate was then transferred to the sample chamber of the membrane separation device and the weak acid was used to separate the supernatant. Step gradient The filtrate was concentrated by membrane separation technology, and the membrane used was MWCO 10KDa. membrane, After concentrating to 1 / 2 of the initial volume of the filtrate, add 50 mM calcium chloride solution to the sample chamber to the initial volume of the filtrate, and then concentrate to 1 / 2 of the initial volume of the filtrate. Add 25 mM calcium chloride solution to the initial volume of the filtrate, and then concentrate to 1 / 2 of the initial volume of the filtrate and add ultrapure water to the initial volume of the filtrate. After concentrating to 1 / 8 of the initial volume of the filtrate, take out the highly concentrated solution, adjust its pH to 7.0, and then freeze-dry for 72 hours to obtain rapeseed protein isolate, which is Example 5.

[0064] Example 6

[0065] The defatted rapeseed meal was coarsely ground in a mortar and then dispersed in a 100 mM calcium chloride aqueous solution at a ratio of 1:8 (w / v), stirred at room temperature (25°C) for 30 min, sieved with a 100-mesh sieve, and then rinsed with the same volume of calcium chloride aqueous solution. The material below the sieve was the crude protein extract, and the material above the sieve was the crude rapeseed dietary fiber extract.

[0066] Then the crude protein extract was homogenized at 13800rpm for 2min to make it more evenly dispersed, and the pH was controlled to 7.0 with HCl, stirred at room temperature for 30min, and 1% activated carbon was added and stirred for 30min, then centrifuged at 10000g for 30min, and the supernatant was collected. The supernatant was further separated into solid and liquid, and the liquid was collected. The filtrate was then transferred to the sample chamber of the membrane separation device, and the filtrate was concentrated using weak acid synchronous gradient membrane separation technology. The membrane used was MWCO 10KDa. The membrane was prepared, and after concentrating to 1 / 2 of the initial volume of the filtrate, 50 mM calcium chloride solution was added to the sample chamber to the initial volume of the filtrate, and then concentrated to 1 / 2 of the initial volume of the filtrate, 25 mM calcium chloride solution was added to the initial volume of the filtrate, and then concentrated to 1 / 2 of the initial volume of the filtrate, ultrapure water was added to the initial volume of the filtrate, and the highly concentrated solution was taken out after concentrating to 1 / 8 of the initial volume of the filtrate, and its pH was adjusted to 7.0 and freeze-dried for 72 hours to obtain rapeseed protein isolate, which is Example 6.

[0067] Example 7

[0068] The defatted rapeseed meal was coarsely ground in a mortar and then dispersed in a 100 mM calcium chloride aqueous solution at a ratio of 1:8 (w / v), stirred at room temperature (25°C) for 30 min, sieved with a 200-mesh sieve, and then rinsed with the same volume of calcium chloride aqueous solution. The material below the sieve was the crude protein extract, and the material above the sieve was the crude rapeseed dietary fiber extract.

[0069] Then the crude protein extract was homogenized at 13800rpm for 2min to make it more evenly dispersed, and the pH was controlled to 5.8 with HCl, stirred at room temperature for 30min, and 1% activated carbon was added and stirred for 30min, then centrifuged at 10000g for 30min, and the supernatant was collected. The supernatant was further separated into solid and liquid, and the liquid was collected. The filtrate was then transferred to the sample chamber of the membrane separation device, and the filtrate was concentrated using weak acid synchronous gradient membrane separation technology. The membrane used was MWCO 30KDa. The membrane was prepared, and after concentrating to 1 / 2 of the initial volume of the filtrate, 50 mM calcium chloride solution was added to the sample chamber to the initial volume of the filtrate, and then concentrated to 1 / 2 of the initial volume of the filtrate, 25 mM calcium chloride solution was added to the initial volume of the filtrate, and then concentrated to 1 / 2 of the initial volume of the filtrate, ultrapure water was added to the initial volume of the filtrate, and the highly concentrated solution was taken out after concentrating to 1 / 8 of the initial volume of the filtrate, and its pH was adjusted to 7.0 and freeze-dried for 72 hours to obtain rapeseed protein isolate, which is Example 7.

[0070] In order to further demonstrate the beneficial effects of the present invention and to better understand the present invention, the properties and application performances of the high-quality rapeseed protein and rapeseed dietary fiber and their simultaneous preparation methods disclosed in the present invention are further illustrated by the following comparative examples and experimental examples, but they should not be construed as limitations on the present invention. The properties of the methods obtained by other measurement experiments conducted by technicians in the field based on the above-mentioned invention content and the applications based on the above-mentioned properties are also deemed to fall within the protection scope of the present invention.

[0071] Comparative Example 1

[0072] The defatted rapeseed meal was crushed and passed through a 100-mesh sieve to obtain defatted rapeseed meal powder. The rapeseed meal powder was dispersed in ultrapure water at a ratio of 1:10 (w / v), stirred at room temperature (25°C) for 2 hours, and the pH value was controlled to 9.0 with NaOH. Then centrifuged at a speed of 10,000g for 30 minutes, and the supernatant was collected. The pH of the supernatant was controlled to 4.5 with HCl, and after standing, it was centrifuged at 10,000g for 30 minutes to collect the precipitate. The precipitate was washed with an appropriate amount of ultrapure water, adjusted to 7.0, and adjusted to 7.0 again after standing overnight to obtain a mixed solution. The mixed solution was freeze-dried for 72 hours to obtain rapeseed protein, which is Comparative Example 1.

[0073] Comparative Example 2

[0074] The defatted rapeseed meal was coarsely ground in a mortar and then dispersed in a 100 mM calcium chloride aqueous solution at a ratio of 1:8 (w / v), stirred at room temperature (25°C) for 30 min, sieved with a 200-mesh sieve, and then rinsed with the same volume of calcium chloride aqueous solution. The material below the sieve was the crude protein extract, and the material above the sieve was the crude rapeseed dietary fiber extract.

[0075] Then the crude protein extract was homogenized at 13800rpm for 2min to make it more evenly dispersed, and the pH was controlled to 5.8 with HCl, stirred at room temperature for 30min, and 1% activated carbon was added and stirred for 30min, then centrifuged at 10000g for 30min, and the supernatant was collected. The supernatant was further separated into solid and liquid, and the liquid was collected. The filtrate was then transferred to the sample chamber of the membrane separation device, and the filtrate was concentrated using membrane separation technology. The membrane used was MWCO 30KDa. The membrane was used, and the highly concentrated liquid was taken out after being concentrated to 1 / 8 of the initial volume of the filtrate. The pH value thereof was adjusted back to 7.0 and then freeze-dried for 72 hours to obtain rapeseed protein isolate, which is Comparative Example 2.

[0076] Experimental Example 1

[0077] Taking the rapeseed protein and rapeseed dietary fiber obtained in Examples 1-7 and the comparative example as examples, the protein content, protein recovery rate, total dietary fiber content and total dietary fiber extraction rate of the products obtained by different methods were compared.

[0078] Among them, the protein content determination method is:

[0079] The protein content of the examples and comparative examples was determined by the Kjeldahl nitrogen method. The nitrogen conversion coefficient was based on the national standard GB5009.5-2010, and the protein conversion coefficient was 5.53.

[0080] Protein recovery determination method:

[0081] It is expressed as the ratio of the protein content in the extracted protein to the mass of the protein contained in the defatted rapeseed meal.

[0082] Dietary fiber content determination method:

[0083] With reference to the national standard GB / T 37492-2019, the fiber content of the examples and comparative examples was determined by an enzymatic weight method.

[0084] Dietary fiber extraction rate determination method:

[0085] It is expressed by the ratio of the mass of the dried residue after sieving to the mass of the defatted rapeseed meal.

[0086] The results are shown in Table 1.

[0087] Table 1 Comparative Examples and Examples 1-7 Protein content, protein recovery rate, dietary fiber content and dietary fiber extraction rate measurement results

[0088]

[0089] The present invention uses a method of directly crushing and sieving rapeseed meal to prepare rapeseed protein, which reduces energy consumption in industrial applications compared with the traditional method of extracting rapeseed protein using crushed rapeseed powder by alkali dissolution and acid precipitation. As shown in Table 1, the protein content of rapeseed protein prepared by Examples 1-7 of the present invention is at a relatively high level. The protein conversion coefficient of the protein powder prepared in the table is 5.53, and the protein content is about 80%, which meets the requirements of concentrated protein or isolated protein in commercially available protein products in my country. In addition, after converting the data in Table 1 according to the conversion coefficient of 6.25, the protein content of the embodiment is about 86.63% to 96.95%, which can be used for comparison with the protein content contained in related products abroad. Example 7 is the same as Comparative Example 2 in the extraction process except for the concentration and purification steps. By comparison, it can be seen that the protein content and recovery rate of Comparative Example 2 are significantly lower than those of Example 7. It can be seen that gradient concentration and purification have significant advantages over direct concentration and purification, and the extracted protein purity is higher. The present invention can simultaneously obtain rapeseed protein and rapeseed dietary fiber through one-step screening, and the content of total rapeseed dietary fiber of the obtained by-product is as high as 67.41%, and the extraction rate is 21.87% to 31.04%.

[0090] Experimental Example 2

[0091] Taking the rapeseed protein obtained in Examples 1-7 and the comparative example as an example, the phytic acid and glucosinolate contents of the products obtained by different methods were compared. The results are shown in Tables 2-3.

[0092] Among them, the detection method of phytic acid is: take 0.05g protein sample and disperse it into 2mL 2.4wt% hydrochloric acid, stir for 1h and centrifuge at 5000g for 15min, add 0.1g NaCl to the supernatant and stir until dissolved, let it stand at low temperature for 1h and centrifuge at 5000g for 15min. Take 0.5mL centrifugal supernatant, add 4.5mL deionized water and 4.0mL color solution in turn. After standing for 20min, measure the absorbance at a wavelength of 500nm. Ferric chloride-sulfosalicylic acid color solution: 0.03% ferric chloride hexahydrate and 0.3% dihydrate-5-sulfosalicylic acid are mixed. A standard curve is drawn with sodium phytate as the standard. The measurement results are shown in Table 2.

[0093] Table 2 Phytic acid content in rapeseed protein of comparative example and examples 1-7

[0094]

[0095]

[0096] Note: For the same index, different letters indicate significant difference, P < 0.05; the same as Tables 3 to 6.

[0097] As can be seen from Table 2, the phytic acid content contained in the rapeseed protein prepared in all embodiments of the present invention is less than 1.5%, which meets the requirements for edible rapeseed protein in the EU COMMISSION IMPLEMENTING DECISION of 1July 2014. Compared with Comparative Example 1, the phytic acid content contained in the rapeseed protein prepared in Examples 1-7 decreased by 44.90% to 72.45%, and the phytic acid content of Examples 2 to 7 after adding activated carbon was further reduced compared with Example 1 without adding activated carbon, which proves that activated carbon can absorb part of the phytic acid in rapeseed protein while adsorbing poor coloring substances to make it have a high whiteness value.

[0098] Furthermore, the method for detecting glucosinolates is: using high performance liquid chromatography, specifically referring to NY / T1582-2007. The determination results are shown in Table 3.

[0099] Table 3 Comparative Examples and Examples 1-7 Content of Glucosinolates in Rapeseed Protein

[0100] sample Glucosinolate content / μmol / g Comparative Example 1 2.90±0.22d Example 1 0.82±0.10c Example 2 0.07±0.01a Example 3 0.35±0.05b Example 4 0.37±0.02b Example 5 0.09±0.01a Example 6 0.32±0.01b Example 7 0.10±0.02a

[0101] As can be seen from Table 3, the glucosinolate content of the examples is less than 1 μmol / g, which meets the EU's requirements for edible rapeseed protein. As can be seen from Table 3, the glucosinolate content of Example 1 is significantly lower than that of the comparative example. After analysis, it is known that glucosinolates will hydrolyze under weak acid conditions, and the isolation of glucosinolates and myrosinase is destroyed during high-speed shearing, and the mutual contact between the two will cause the glucosinolates to hydrolyze and the content to decrease. Furthermore, the glucosinolate content of Examples 2-7 is further reduced, which is due to the adsorption capacity of activated carbon for glucosinolates.

[0102] Experimental Example 3

[0103] Taking the rapeseed proteins obtained in Examples 1-7 and Comparative Example 1 as examples, the whiteness values ​​of products obtained by different methods were compared.

[0104] The whiteness value is determined by using a CR-410 colorimeter. Before the sample is measured, a standard white plate is used for calibration. The color parameters are expressed in L* (brightness), a* (red / green) and b* (yellow / blue) values. The whiteness value (WI) of the protein is calculated as follows:

[0105]

[0106] The results are shown in Table 4 and Figure 2 shown.

[0107] Table 4 Whiteness value determination results of rapeseed protein in Comparative Example 1 and Examples 1-7

[0108] sample L* a* b* WI Comparative Example 1 63.49±0.27a 8.03±0.02h 7.04±0.07d 61.96±0.27a Example 1 74.52±0.11c 4.88±0.01e 12.02±0.06f 71.41±0.12b Example 2 77.07±0.17e 4.52±0.01d 5.15±0.04a 76.07±0.16f Example 3 74.17±0.12b 5.28±0.01f 5.03±0.04a 73.16±0.12c Example 4 74.18±0.29b 5.51±0.01g 5.29±0.03a 73.07±0.27c Example 5 76.31±0.20d 4.23±0.01c 6.37±0.04b 75.11±0.20e Example 6 76.53±0.14d 3.80±0.03b 9.03±0.28e 74.57±0.11d Example 7 74.39±0.24b 3.65±0.02a 6.52±0.11c 73.32±0.25c

[0109] As shown in Table 4, Examples 1-7 of the present invention have relatively high whiteness values, ranging from 71.41 to 76.07. Figure 1 It can be seen that, compared with Comparative Example 1, Examples 1-7 all have good color appearance.

[0110] Experimental Example 4

[0111] Taking the rapeseed proteins obtained in Examples 1-7 and the comparative example as examples, the foaming properties and foam stability of the rapeseed proteins obtained by different methods were compared.

[0112] The foamability and foam stability of the rapeseed protein are determined by:

[0113] Prepare 15 mL of 1% (w / v) protein solution with ultrapure water, adjust the pH to 7.0, shear for 2 min using a high-speed shearing machine (13800 rpm), immediately pour the protein solution together with the foam into a measuring cylinder, read the foam volume; read the foam volume again after standing for 60 min.

[0114] The calculation formulas for foamability and foam stability are as follows:

[0115] Foaming property (%) = V2 / 15*100;

[0116] Foam stability (%) = V 60 / V2*100;

[0117] Where: V2 represents the foam volume in 2 minutes, V 60 Indicates the foam volume at 60 min.

[0118] The measurement results are shown in Table 5.

[0119] Table 5 Rapeseed protein foamability and foam stability of comparative examples and examples 1-7

[0120] Grouping Foaming property / % Foam stability / % Comparative Example 1 148.3±13.4a 78.4±1.1bc Comparative Example 2 227.8±28.9bc 46.8±4.2a Example 1 209.0±8.8bc 75.3±1.6b Example 2 198.3±15.8b 79.3±1.0bcd Example 3 209.0±15.8bc 85.4±2.3de Example 4 214.4±13.1bc 85.9±1.6de Example 5 244.7±10.1c 86.9±2.8e Example 6 235.8±11.6bc 83.2±2.9cde Example 7 301.9±35.1d 78.7±5.6bc

[0121] As shown in Table 5, Examples 1-7 of the present invention have strong foaming properties, which are 1.34 to 2.04 times that of Comparative Example 1. And the foam stability of Example 7 is 1.68 times that of Comparative Example 2. It can be seen that the gradient dilution concentrated protein has better foam stability than the directly concentrated protein.

[0122] Experimental Example 5

[0123] Taking the rapeseed proteins obtained in Examples 1-7 and Comparative Example 1 as examples, the solubility of rapeseed proteins obtained by different methods was compared.

[0124] The solubility of rapeseed protein is determined by:

[0125] A 0.1% protein solution was prepared with ultrapure water, the pH was adjusted to 7.0, and the solution was centrifuged at 4000 r / min and 4° C. for 10 min, and the supernatant was collected. The protein concentration was measured by the Bradford method using BSA as a standard protein, and the absorbance was measured at 595 nm.

[0126] The measurement results are shown in Table 6.

[0127] Table 6 Rapeseed protein solubility of comparative examples and examples 1-7

[0128] Grouping Solubility Comparative Example 1 28.90±1.11a Comparative Example 2 44.48±1.42b Example 1 54.19±2.20cd Example 2 58.17±2.08ef Example 3 56.75±1.95de Example 4 56.38±2.04de Example 5 59.72±2.50f Example 6 55.85±2.16de Example 7 52.55±3.13c

[0129] It can be seen from Table 6 that the solubility of Examples 1-7 of the present invention is significantly higher than that of the comparative example, indicating that the rapeseed protein prepared by the preparation method disclosed in the present invention has good solubility.

[0130] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for synchronously preparing high-quality rapeseed protein and rapeseed dietary fiber, characterized in that: The coarsely ground defatted rapeseed cake is dispersed with a good solvent and then sieved, and then rinsed and sieved with a good solvent to simultaneously obtain rapeseed protein crude extract and rapeseed dietary fiber, and then the rapeseed protein crude extract is further processed to obtain rapeseed protein.

2. The preparation method according to claim 1, characterized in that: The good solvent is a 100-500 mM salt solution, and the salt of the good solvent is selected from one or more combinations of CaCl2 and MgCl2.

3. The preparation method according to claim 1, characterized in that: The mesh number of the sieving is 60-200 meshes.

4. The preparation method according to claim 1, characterized in that: The method for further treating the rapeseed protein crude extract is as follows: After homogenizing the crude rapeseed protein extract, weak acid enrichment is used, and the pH is controlled at 5.0-7.0, centrifugation is performed, and then the supernatant is further separated into solid and liquid, and the liquid is retained and concentrated using weak acid synchronous gradient membrane separation technology to obtain a highly concentrated protein solution. The pH value of the highly concentrated protein solution is then adjusted to 7 and freeze-dried to obtain high-quality rapeseed protein.

5. The preparation method according to claim 4, characterized in that: The method for weak acid synchronous gradient membrane separation and concentration is: The liquid after solid-liquid separation is moved into the sample processing chamber to start concentration using membrane separation technology, and the pH of the treatment system is maintained between 5.0-7.

0. After the liquid volume is concentrated to 1 / 2 of the initial volume, good solvent a is added to the sample processing chamber to replenish the liquid volume to the initial volume, and the concentration is continued; After the volume of the liquid in the sample chamber is concentrated to 1 / 2 of the initial volume again, good solvent b is added to the sample processing chamber to replenish the liquid volume to the initial volume, and the concentration is continued; after the volume of the liquid in the sample chamber is concentrated to 1 / 2 of the initial volume again, good solvent c is added to the sample processing chamber to replenish the liquid volume to the initial volume, and the concentration is continued; after the volume of the liquid in the sample chamber is concentrated to 1 / 2 of the initial volume again, good solvent d is added to the sample processing chamber to replenish the liquid volume to the initial volume, and the concentration is continued; repeat the above steps until the concentration of the good solvent added to the sample processing chamber is in the range of 20 to 40 mM, after the liquid in the sample processing chamber is concentrated to 1 / 2 of the initial volume again, ultrapure water is added to replenish the liquid volume in the sample processing chamber to the initial volume, and the concentration is continued to 1 / 8 of the initial volume to obtain a highly concentrated solution.

6. The preparation method according to claim 5, characterized in that: The concentration of the good solvent a is 40% to 60% of the good solvent, the concentration of the good solvent b is 20% to 30% of the good solvent, the concentration of the good solvent c is 10% to 15% of the good solvent, and the concentration of the good solvent d is 5% to 8% of the good solvent.

7. The preparation method according to claim 5, characterized in that: The membrane molecular weight of the membrane separation is 5-30 kDa.

8. The preparation method according to claim 4, characterized in that: The preparation method also includes enriching the rapeseed protein crude extract with weak acid, adding activated carbon for treatment, and then performing centrifugal treatment.

9. A rapeseed protein or rapeseed dietary fiber obtained by the preparation method according to any one of claims 1 to 8.

10. Use of the rapeseed protein or rapeseed dietary fiber according to claim 9 in dietary protein or fiber supplements, food ingredients, foaming agents, and rapeseed protein / fiber-based foods.

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