Method for extracting cellulose from beer lees

Abstract

To provide a method for extracting cellulose from beer lees capable of elevating purity of extraction of cellulose in beer lees and accurately controlling a polymerization degree of cellulose as required.SOLUTION: A method includes a pretreatment step of washing beer lees raw material with water to obtain a first treated product, an alkaline solution soaking step of soaking the first treated product obtained in the pretreatment step in an alkaline solution to obtain a cellulose mixture, and an acidic solution soaking step of soaking the cellulose mixture obtained in the alkaline solution soaking step in an acidic solution to obtain a cellulose refined product, and is characterized by further including, in at least one of the alkaline solution soaking step or in the acidic solution soaking step, a polymerization degree control step of obtaining an extraction parameter value which is a parameter for extraction of cellulose and controlling the extraction parameter value, thereby controlling a polymerization degree of cellulose.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to cellulose extraction, and in particular to a method for extracting cellulose from brewer's spent grains. [Background technology]

[0002] Brewers' grain is the main by-product of beer production, and is the residue left over after fermenting barley and extracting the soluble carbohydrates from the grain. With an average of 200g of brewers' grain generated per liter of beer brewed, approximately 40 million tons of brewers' grain is generated annually worldwide.

[0003] Because brewers' spent grains are primarily composed of grain husks and seed coats, they are rich in lignin, cellulose, semi-cellulose, protein, lipids, and trace elements, and are sold as inexpensive animal feed. However, most brewers' spent grains are discarded as is, which is not only environmentally unfriendly but also results in economic losses. For this reason, various techniques have been proposed for extracting components contained in brewers' spent grains. For example, Patent Document 1 discloses a technique for recovering proteinaceous and fibrous substances from brewers' spent grains.

[0004] Despite its wide range of applications, cellulose, particularly abundant in brewers' grains, has not been utilized effectively. It can be used to make sucrose fiber, cellulose fiber filler, and cellulose yarn, among other textiles. Furthermore, cellulose is a major component of pulp, allowing it to be used to produce various types of paper, including newspaper, book paper, and wrapping paper. It can also be used as a coating agent for pharmaceutical capsules, improving drug stability and absorption. Brewers' grain cellulose can be used as a filler for plant fibers and to make biodegradable plastics, paper boxes, paper bags, and other products, helping to reduce environmental pollution. Brewers' grain cellulose is a multifunctional natural material widely used in the food, construction, and agriculture industries. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2022-501004 Summary of the Invention [Problem to be solved by the invention]

[0006] However, because the raw material for beer spent grains has not been fully developed and the components of beer spent grains are complex, there are problems such as low purity of the cellulose extracted from beer spent grains, making mass production difficult.

[0007] Therefore, the present invention has been made in consideration of the above-mentioned problems, and an object of the present invention is to provide a method for extracting cellulose from brewers' spent grains, which can increase the purity of cellulose extracted from brewers' spent grains and accurately adjust the degree of polymerization of cellulose as necessary. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, the method for extracting cellulose from brewers' spent grains according to the present invention includes a pretreatment step of washing brewers' spent grains raw material with water to obtain a first treated product, an alkaline solution immersion step of immersing the first treated product obtained in the pretreatment step in an alkaline solution to obtain a cellulose mixture, and an acidic solution immersion step of immersing the cellulose mixture obtained in the alkaline solution immersion step in an acidic solution to obtain a purified cellulose product, and further includes a degree of polymerization adjustment step of obtaining extraction parameter values, which are parameters for extracting cellulose, in at least either the alkaline solution immersion step or the acidic solution immersion step, and adjusting the extraction parameter values ​​to adjust the degree of polymerization of cellulose.

[0009] Here, the extraction parameter value adjusted in the polymerization degree adjusting step is preferably at least one of the solution concentration, the solution amount, the solid-liquid mass ratio, the impregnation temperature which is the temperature of the solution during immersion, and the impregnation time which is the time for immersion.

[0010] Preferably, the alkaline solution in the alkaline solution immersion step is a sodium hydroxide solution, and the acidic solution in the acidic solution immersion step is a peracetic acid solution.

[0011] The concentration of peracetic acid in the peracetic acid solution is preferably 1 to 5%, and the temperature for impregnation in the peracetic acid solution is preferably 60 to 90°C.

[0012] The impregnation time in the peracetic acid solution may be 3 hours to 15 hours, and the solid-liquid mass ratio of the cellulose mixture to the peracetic acid solution may be 1 / 5 to 1 / 20.

[0013] Furthermore, the sodium hydroxide concentration in the sodium hydroxide solution is preferably 0.5 mol / L to 1.0 mol / L.

[0014] Furthermore, the temperature of the alkaline solution in the alkaline solution immersion step may be 80° C. to 120° C., and the time for immersion in the alkaline solution may be 3 hours to 15 hours.

[0015] It is further preferred to include a washing step in which the cellulose mixture obtained in the alkaline solution soaking step is washed to neutral, and in the acidic solution soaking step, the cellulose mixture washed to neutral in the washing step is soaked in an acidic solution, and it is further preferred to include a final washing step in which the purified cellulose product obtained in the acidic solution soaking step is washed to neutral and converted into a cellulose extract. [Effects of the Invention]

[0016] According to the method for extracting cellulose from brewer's spent grains of the present invention, by treating the brewer's spent grains with an alkaline solution and then an acidic solution, impurities in the brewer's spent grains can be removed as much as possible, improving the purity of the extracted cellulose. By adjusting the soaking concentration, soaking temperature, and soaking time of the acidic or alkaline solution, the degree of polymerization of cellulose can be accurately controlled within a set range as needed. Furthermore, the operation method can be simplified, the range of application of cellulose can be expanded, and the accuracy of controlling the degree of polymerization of cellulose can be improved. Furthermore, the degree of polymerization of the extracted cellulose does not meet the product demand during application, reducing the yield rate and saving production costs. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a flowchart showing the steps of a method for extracting cellulose from brewer's spent grains. DETAILED DESCRIPTION OF THE INVENTION

[0018] The method for extracting cellulose from brewer's spent grains according to the present invention will be described in detail below.

[0019] Brewers' spent grain is a major by-product of the beer industry and is composed of cellulose, semi-cellulose, ligsol, insoluble protein, fat, ash, and a small amount of undigested starch. The method for extracting cellulose from brewers' spent grain according to an embodiment of the present invention is a method for increasing the extraction purity of cellulose in brewers' spent grain and accurately adjusting the degree of polymerization of cellulose as needed.

[0020] FIG. 1 is a flow chart showing the steps of a method for extracting cellulose from brewer's spent grains. First, as a pretreatment, the raw material of beer spent grains is washed in a container containing water and dried to obtain a first treated product (step S1).

[0021] An appropriate amount of spent grains is taken and placed in a container containing an appropriate amount of room-temperature deionized water, where it is washed at least three times. The deionized water removes impurities such as ash, soluble amino acids, and some starch from the spent grains. The washed spent grains are then filtered and dried to obtain a solid mass. This is the first processed spent grain. To speed up the drying process and prevent further fermentation and mold growth, the spent grains are dried in an oven or reactor at temperatures between 40°C and 90°C until they reach a certain weight. This avoids the waste of resources caused by the use of excess alkaline solution.

[0022] Next, the first treated material is immersed in a container containing an alkaline solution to perform an alkaline treatment (step S2). During the immersion in the alkaline solution, extraction parameters are adjusted (step S3), and the cellulose mixture is obtained by filtering and drying.

[0023] The first treated brewer's spent grains contain cellulose, a large amount of ligsol, fat, and a small amount of protein. Cellulose impurities are removed by adding sodium hydroxide, sodium sulfite, potassium hydroxide, or other alkaline solution to the first treated brewer's spent grains. Sodium hydroxide solution is preferred as the alkaline solution used here because it is relatively inexpensive to purchase, can remove impurities from the first treated brewer's spent grains, and is advantageous in increasing the purity of the cellulose contained in the brewer's spent grains.

[0024] Through extensive testing, the inventors have found that parameters such as the concentration of the alkaline solution, the immersion time, and the immersion temperature affect the anti-pollution effect of cellulose. Therefore, by adjusting any one of the above parameters or a combination of parameters selected from these, optimal anti-pollution effects can be achieved. Furthermore, the three parameters used to adjust the alkaline solution are designated as a second parameter group, and the cellulose degree of polymerization obtained by adjusting the second parameter group also changes accordingly. The range of change is smaller than the change in cellulose degree of polymerization obtained by adjusting the first parameter group.

[0025] Therefore, the extraction parameter values ​​in step S3 include at least one of the concentration value of the alkaline solution, the soaking temperature value, and the soaking time value. The extraction parameter values ​​may also include the soaking concentration, soaking time, soaking temperature, and solid-liquid mass ratio of the brewers' spent grains in the alkaline solution.

[0026] After filtration, the alkaline solution may remain on the surface of the cellulose mixture. If the brewers' spent grains are soaked in the alkaline solution for too long, the structure of the brewers' spent grains cellulose will be destroyed, which will affect the degree of polymerization of the cellulose extracted. Furthermore, the remaining alkaline solution will also have an effect, making it difficult to accurately control the overall concentration of the solution for the subsequent acid treatment and the concentration during the acid treatment to affect the purity and degree of polymerization of the brewers' spent grains cellulose.

[0027] To avoid residual alkaline solution from being contained in the cellulose mixture, i.e., to avoid prolonged immersion of the cellulose in the residual alkaline solution and a decrease in the degree of polymerization of the cellulose, the cellulose mixture after alkaline solution treatment is washed with deionized water at room temperature to neutralize (pH = 7), filtered, and then dried to produce a mixture of cellulose and ligsol.

[0028] Next, the cellulose mixture is immersed in a container containing an acidic solution to perform an acid treatment (step S4). During the immersion in the acidic solution, extraction parameters are adjusted (step S5).

[0029] The dried cellulose mixture is added to a container containing an acidic solution, which not only functions as an acidic reagent but also serves to remove impurities such as lignin and organic matter from the cellulose mixture and bleach the cellulose mixture.

[0030] Acidic solutions are acidic reagents such as perchloric acetic acid and hypochlorous acid, which have bleaching properties. Hypochlorous acid is unstable, easily decomposed, difficult to store, and has poor bleaching properties. Therefore, increasing the concentration of hypochlorous acid can remove unpleasant flavors. Furthermore, when impregnated with other strong acids, the strong acids can destroy the structure of cellulose in brewers' spent grains or decompose the cellulose. Therefore, in this case, we use peracetic acid at a concentration of 1-5% by mixing a 20% peracetic acid solution with deionized water in a certain ratio, which reduces costs and satisfies the purity required for extracting cellulose from brewers' spent grains without increasing the concentration.

[0031] The soaking parameters of the acid solution, such as soaking concentration, soaking time, and soaking temperature, can affect the purity and degree of polymerization of cellulose in the spent grains. After the soaking is completed, the spent grains with the acid solution are filtered. The acid solution can remove almost all impurities in the cellulose mixture of the spent grains, resulting in a purified cellulose product. In addition, the parameters of the acid solution itself have a significant effect on the degree of polymerization of cellulose, so the degree of polymerization of cellulose in the spent grains can be better controlled.

[0032] Therefore, the extraction parameter values ​​in step S5 include at least one of the concentration value of the acid solution, the soaking temperature value, and the soaking time value. The extraction parameter values ​​may also include the soaking concentration, soaking time, soaking temperature, and solid-liquid mass ratio of the brewers' spent grains in the acid solution.

[0033] At this time, the acidic solution may remain on the surface of the purified cellulose after filtration. If the purified cellulose is immersed in the acidic solution for too long, the cellulose structure may be destroyed. Therefore, it is preferable to wash the purified cellulose with deionized water at room temperature.

[0034] Finally, the purified cellulose is dried to obtain the final cellulose extract. In order to extract as much cellulose as possible from the brewers' spent grains, the brewers' spent grains are soaked in an acidic and alkaline solution during the process, which has the effect of removing all impurities from the brewers' spent grains, minimizing the amount of acidic and alkaline solutions used, eliminating waste of the acidic and alkaline solutions, and reducing production costs.

[0035] In this embodiment, during the cellulose extraction process, the brewer's spent grains are soaked in an alkaline solution and then an acidic solution. In another embodiment, during the cellulose extraction process, the brewer's spent grains may be soaked in an acidic solution and then an alkaline solution. The combined action of the acidic and alkaline solutions can remove all impurities from the brewer's spent grains and improve the cellulose purity. Furthermore, during the acidic and alkaline solution treatments, the degree of polymerization of the extracted cellulose can be controlled within a predetermined range as needed by adjusting the extraction parameter values ​​of the acidic solution and / or the extraction parameter values ​​of the alkaline solution. In other words, the degree of polymerization of cellulose can be controlled to a predetermined value as needed, and the resulting cellulose can be applied to industries where all of the cellulose corresponds to the predetermined value.

[0036] In this embodiment, a sodium hydroxide solution is used, and the soaking parameters for the sodium hydroxide solution are a sodium hydroxide solution with a concentration of 0.5 mol / L to 1.0 mol / L, with a solid-liquid mass ratio of 1 / 5 to 1 / 15. The soaking treatment time is 3 to 15 hours at 80°C to 120°C. To maintain a constant soaking temperature, the brewer's spent grains may be placed in an oven or reaction kettle at 80°C to 120°C, for example. This allows all semi-cellulose and small amounts of protein impurities to be removed from the brewer's spent grains.

[0037] Furthermore, in this embodiment, a peracetic acid solution (peroxoacetic acid solution) is used as the acidic solution in which the brewers' spent grains are soaked. The soaking parameters for the peracetic acid solution are as follows:

[0038] When using a 1-5% concentration peracetic acid solution, the solid-liquid mass ratio of spent grains to peracetic acid solution is 1 / 5-1 / 20. By ensuring that the peracetic acid solution is not spent grains, waste of the peracetic acid solution can be prevented. The minimum amount of peracetic acid solution can achieve the acid soaking effect, removing all lignin and other remaining impurities in the cellulose mixture.

[0039] To enhance the removal of impurities from brewers' spent grains, the soaking temperature should be between 60°C and 90°C with peracetic acid, and the soaking time should be between 3 and 15 hours. To maintain the temperature within the specified range, the acid treatment can be carried out in an oven or reactor at 60°C to 90°C. This ensures optimal removal of lignin and other impurities from the acid solution, maintains the purity of the cellulose in the cellulose refined product, and controls the degree of polymerization of the resulting cellulose.

[0040] In summary, the method for extracting brewer's spent grains cellulose with a controllable degree of polymerization using brewer's spent grains as a raw material, as described in this embodiment, can extract brewer's spent grains cellulose with an increased purity using the above-mentioned cellulose extraction method. Furthermore, the purity of the extracted cellulose can be ensured, and reduction of cellulose due to excessive impurities in the cellulose can be prevented. Extensive experiments have shown that the effect of removing impurities from brewer's spent grains after peralkali treatment and acid treatment is clear, and the cellulose purity can reach 90%.

[0041] Furthermore, the brewers' spent grains are treated by soaking them in a sodium hydroxide solution and a peroxoacetic acid solution, respectively. Parameters such as the concentration of the sodium hydroxide solution and the acetic acid solution, the soaking time, the soaking temperature, and the solid-liquid mass ratio can be adjusted, and the cellulose extracted by combining these parameters varies in degree of polymerization, making it possible to produce cellulose with different degrees of polymerization on demand as needed.

[0042] The cellulose polymer obtained in this embodiment can be accurately controlled within a set range. For example, by adjusting the parameter values ​​of the acidic solution and alkaline solution, the degree of polymerization of cellulose can be controlled within a range of 375 to 836.

[0043] More specifically, cellulose can be produced with different degrees of polymerization required in light industries such as the textile industry, papermaking industry, and medical industry, thereby ensuring the quality of the produced products. For example, when cellulose is used in the spinning industry, the degree of polymerization of cellulose extracted from brewer's spent grains can be controlled within the range required for spinning. Furthermore, when cellulose is used in the papermaking industry, the degree of polymerization of cellulose can be controlled to the degree required for the papermaking industry. Furthermore, the degree of polymerization of cellulose can be controlled within the range required in the advanced medical industry. This reduces the loss of cellulose extracted from brewer's spent grains. Furthermore, this extraction method is simple, and environmental pollution does not occur if the acid solution and alkaline solution after extraction are diluted and the effluent is neutralized.

[0044] Examples of the present invention will be described below.

[0045] According to the above procedure, the washed brewer's spent grains are soaked in a sodium hydroxide solution of a predetermined concentration, and then subjected to alkali treatment under predetermined conditions of soaking time, soaking temperature, and solid-liquid mass ratio to obtain a cellulose mixture. The resulting cellulose mixture is then sequentially soaked in a peracetic acid solution of a predetermined concentration, and each soaking parameter is selected. Acid treatment is then performed at a predetermined soaking time, soaking temperature, and solid-liquid mass ratio to obtain a purified cellulose product. This process removes all impurities from the brewer's spent grains. In this case, the purity of the extracted cellulose reaches 90%, and the degree of polymerization of cellulose is determined by the interaction between the soaking parameters of the peracetic acid solution and the sodium hydroxide solution. By increasing the purity of cellulose extracted from brewer's spent grains and, if necessary, maintaining a constant degree of polymerization of the extracted cellulose, the efficiency of the extracted cellulose can be ensured. Examples are provided in which the extraction parameters for the acidic and alkaline solutions are adjusted as follows:

[0046] Example 1 40 g of brewers' spent grains were soaked in 1 mol / L sodium hydroxide solution at a solid-liquid mass ratio of 1 / 15, filtered and dried after soaking. After soaking, the soaked brewers' spent grains were soaked in 1% peracetic acid at 80°C for 15 hours, and then extracted at a solid-liquid mass ratio of 1 / 20 with a degree of polymerization of cellulose adjusted to 644.62. The cellulose extracted in this way is suitable for the production of printing paper, spinning, flexible membranes, shopping bags, etc.

[0047] Example 2 40g of brewers' spent grains were soaked in 0.5mol / L sodium hydroxide solution at 80°C for 5 hours, with a solid-liquid mass ratio of 1 / 15. The raw material was then soaked in 3% peracetic acid at 60°C for 6 hours, with a solid-liquid mass ratio of 1 / 15. Under these conditions, the brewers' spent grains had a 39% impurity removal effect and a cellulose polymerization degree of 735.75. The cellulose extracted in this way is suitable for preparing high-strength single yarns, multi-filament yarns, ultrafine fibers, and very high-strength films such as surgical sutures, and can be used in the medical industry.

[0048] Example 3 Example 3 differs from Example 1 in that the specific immersion parameter values ​​of the acetic acid solution and the sodium hydroxide solution are adjusted.

[0049] 40g of brewers' spent grains were soaked in a 0.5mol / L sodium hydroxide solution at 80°C for 5 hours, then the solid-liquid mass ratio was 1 / 15. 4% peracetic acid was then added and the mixture was soaked at 80°C for 5 hours, after which the solid-liquid mass ratio was 1 / 20, the impurity removal effect in the brewers' spent grains reached 40%, and the cellulose polymerization degree was adjusted to 613.71. The cellulose extracted in this way is suitable for the production of printing paper, spinning, sucrose fiber, flexible membranes, shopping bags, etc.

[0050] Example 4 In Example 4, the immersion concentration and immersion time of the acetic acid solution were changed, and the immersion concentration and immersion time of the sodium hydroxide solution were also changed.

[0051] 40g of brewers' spent grains were soaked in a 0.5mol / L sodium hydroxide solution at 80°C for 5 hours, and then extracted at a solid-liquid mass ratio of 1 / 15. 5% peracetic acid was then added and the mixture was soaked at 80°C for 5 hours, after which the solid-liquid mass ratio was adjusted to 1 / 5, the impurity removal effect in the brewers' spent grains was 42%, and the cellulose polymerization degree was adjusted to 462.12. The cellulose extracted in this way is suitable for making soft cotton towels, cosmetic cotton pads, toilet paper, short fibers for spun sachet, flexible membranes, and shopping bags.

[0052] Example 5 In Example 5, the immersion time in the acetic acid solution was changed, and the concentration and immersion time of the sodium hydroxide solution were changed.

[0053] 40g of beer grain raw material was soaked in 0.75mol / L sodium hydroxide solution at 80℃ for 10 hours, then mixed with 1% peracetic acid and soaked at 80℃ for 10 hours, and then extracted with a solid-liquid mass ratio of 1 / 10 and a cellulose polymerization degree of 669.66.

[0054] Example 6 In Example 6, the immersion concentration, immersion time, and immersion temperature of the acetic acid solution were changed, and the immersion time of the sodium hydroxide solution was changed.

[0055] 40g of brewers' spent grains were soaked in a 0.5mol / L sodium hydroxide solution at 80°C for 5 hours at a solid-liquid mass ratio of 1 / 15, and then further soaked in 3% peracetic acid at 90°C for 6 hours at a solid-liquid mass ratio of 1 / 5. This resulted in a removal rate of 45% of the impurities in the spent grains, and the cellulose was adjusted to a degree of polymerization of 375.01. The cellulose extracted in this way is suitable for the production of products requiring strong, low-molecular-weight cellulose, such as disposable tableware, biodegradable food packaging, toilet paper, and cotton tissue.

[0056] Example 7 In Example 7, the immersion concentration and immersion time of the peracetic acid solution were changed, and the immersion time of the sodium hydroxide solution was changed.

[0057] 40 g of brewers' spent grains were extracted by soaking 40 g of brewers' spent grains in a 1 mol / L sodium hydroxide solution at 80°C for 10 hours at a solid-liquid mass ratio of 1 / 15. Then, after soaking in 3% peracetic acid at 80°C for 5 hours, the solid-liquid mass ratio was 1 / 5, and the degree of polymerization of the cellulose in the brewers' spent grains was adjusted to 809.43. The cellulose extracted in this manner is suitable for the production of high-strength single yarns, multi-ply yarns, ultrafine fibers, surgical sutures, high-strength membranes, disposable cups, and other products. For these applications, cellulose must have relatively high strength, i.e., it must maintain its structural integrity, and the extracted cellulose meets this requirement.

[0058] Example 8 In Example 8, the immersion time in the acetic acid solution was changed, and the immersion concentration and immersion time in the sodium hydroxide solution were also changed.

[0059] 40 g of brewers' spent grains were immersed in a 0.5 mol / L sodium hydroxide solution at 80°C for 15 hours at a solid-liquid mass ratio of 1 / 5, and then further immersed in 3% peracetic acid at 80°C for 15 hours at a solid-liquid mass ratio of 1 / 20. The degree of polymerization of the cellulose in the brewers' spent grains was adjusted to 559.23, and then extracted. The cellulose extracted in this way is suitable for preparing staple fibers, toilet paper, scouse staple fibers or filaments, filtration membranes, etc.

[0060] Example 9 In Example 9, the immersion time in the acetic acid solution was changed, and the immersion concentration and immersion time in the sodium hydroxide solution were also changed.

[0061] 40g of brewers' spent grains were soaked in a 0.5mol / L sodium hydroxide solution at 80°C for 5 hours at a solid-liquid ratio of 1 / 5 by weight. 2% peracetic acid was then added and soaked at 80°C for 5 hours. The solid-liquid ratio was 1 / 5, the impurity removal rate in the brewers' spent grains was 34%, and the degree of polymerization of cellulose in the brewers' spent grains was adjusted to 708.19. The cellulose extracted in this way is suitable for preparing high-strength single and double yarns, surgical sutures, and very strong membranes. It can also be used in the medical industry to reinforce plastics or as sealing materials, and as friction-resistant insulation materials.

[0062] Example 10 Example 10 is the same as Example 9 except that only the immersion concentration of the peracetic acid solution and the immersion time were changed.

[0063] 40g of brewers' spent grains were soaked in a 0.5mol / L sodium hydroxide solution at 80°C for 5 hours at a solid-liquid mass ratio of 1 / 5. 3% peracetic acid was then added and soaked at 80°C for 5 hours, after which the solid-liquid mass ratio was adjusted to 1 / 20, the removal rate of impurities in the brewers' spent grains was 37%, and the degree of polymerization of cellulose in the brewers' spent grains was adjusted to 836.69. The cellulose extracted in this way is suitable for producing high-strength single yarns, multi-ply yarns, and high-strength membranes for surgical sutures, and can be used in the medical industry.

[0064] Details of the parameter values ​​of the acidic solution and alkaline solution in Examples 1 to 10 are shown in Table 1. The acidic solution is a peracetic acid solution.

[0065] [Table 1]

[0066] Furthermore, a comparison of Example 2 and Example 6 shown in Table 1 reveals that by changing only the immersion temperature in the peracetic acid solution while leaving the other parameters unchanged, it is possible to increase the purity of cellulose while maintaining the effect of removing impurities other than cellulose.

[0067] The weight loss rate of the beer spent grains after impregnation increased from 39% to 45%, and the degree of polymerization of cellulose decreased from 735.75 to 375.01, corresponding to a positive correlation between the concentration of the peracetic acid solution and the temperature. Since the degree of polymerization of cellulose tends to decrease when the impregnation concentration of the acetic acid solution and the temperature are increased simultaneously, the simultaneous increase after combination with the increase in the degree of polymerization is inversely proportional, resulting in a significant decrease. The simultaneous increase or decrease of the impregnation concentration of the acetic acid solution and the impregnation temperature has a significant impact on the degree of polymerization of cellulose.

[0068] Furthermore, comparing Examples 9, 3, and 4 in Table 1, the weight loss rate of the brewers' spent grains material gradually increases with increasing impregnation concentration of the acetic acid solution, while other conditions are held constant. In these cases, the weight loss rates are 34%, 40%, and 42%, respectively. The cellulose degrees of polymerization were adjusted to 708.19, 613.71, and 462.12, indicating that the magnitude of the cellulose degree of polymerization is inversely proportional to the single parameter of the peracetic acid solution concentration, allowing for rapid adjustment of the degree of polymerization. Even a slight increase in the amount of peracetic acid added can prevent the cellulose degree of polymerization from being achieved. Therefore, adjusting the concentration of the peracetic acid solution alone results in significant fluctuations in the degree of polymerization, making it difficult to accurately adjust the cellulose degree of polymerization. This indicates that the cellulose degree of polymerization adjustment is not optimized.

[0069] Comparing Examples 7 and 10, it was found that adjusting only the sodium hydroxide solution soaking concentration and shortening the soaking time allowed for a degree of polymerization (DOP) to be obtained without changing other conditions, with the DOP increasing from 809.43 to 836.69. The DOP of 836.69 obtained by this method is the upper limit for the DOP. Therefore, adjusting only the sodium hydroxide solution soaking concentration and soaking time without changing the peracetic acid solution soaking conditions requires higher precision in adjusting the DOP of cellulose, raising the demands of the cellulose extraction process. Experimental failure due to operational errors can be avoided, leading to increased manpower, time, financial costs, and even manufacturing costs. Therefore, simply changing the SOP concentration and soaking time is not an effective way to adjust the DOP of cellulose.

[0070] Referring to Examples 8 and 9 in Table 1, the cellulose polymerization degree can be increased from 559.23 to 708.19 by reducing the peracetic acid solution soaking concentration from 3% to 2% and shortening the peracetic acid solution and sodium hydroxide solution soaking time from 15 hours to 5 hours. As the ratio of the acidic solution to the alkaline solution soaking time decreases, the peracetic acid concentration decreases, and the cellulose polymerization degree value is inversely proportional to the combination parameters of the peracetic acid soaking concentration and soaking time. Therefore, the polymerization degree can be adjusted to a set value as needed.

[0071] Referring to Table 1, which combines Examples 1 and 7, when the acetic acid concentration increases from 1% to 3%, the acetic acid soaking time is reduced from 15 hours to 5 hours, the sodium hydroxide soaking time is reduced from 15 hours to 10 hours, and the cellulose degree of polymerization is reduced from 644.62 to 809.43. As the acetic acid solution concentration increases and the soaking time decreases, the cellulose degree of polymerization increases significantly. Therefore, the combination of acetic acid solution concentration and soaking time has a significant effect on the cellulose degree of polymerization, while the sodium hydroxide solution soaking time has a small effect on the cellulose degree of polymerization.

[0072] Referring to Table 1 for Examples 4 and 10, when soaking brewers' spent grains, as the concentration of the peracetic acid solution decreases, the soaking time also shortens, and if other conditions remain the same, the degree of polymerization of cellulose tends to increase significantly. The weight loss rate of brewers' spent grains after impregnation decreased from 42% to 37%, and a negative correlation was observed between the increase or decrease of the parameter combining the peracetic acid concentration and soaking time and the degree of polymerization of cellulose.

[0073] Referring to Table 1 for Examples 6 and 10, only the acetic acid soaking temperature and soaking time were changed, while the other parameters remained unchanged. As the soaking time and soaking temperature decreased, the weight loss rate of the brewers' spent grains decreased, from 45% to 37%, respectively, and the degree of cellulose polymerization increased. The cellulose degree of polymerization increased inversely proportionally from 375.01 to 836.69, a common parameter of the acetic acid soaking temperature and soaking time. This allows cellulose to be used in the production of disposable tableware at high speed. It can also be used in the production of high-strength single yarns, multi-ply yarns, and very high-strength surgical sutures. Because strict requirements are placed on testers, the soaking temperature and soaking time in peracetic acid are single adjustments that are effective in controlling the degree of cellulose polymerization, preventing runaway phenomena due to operational errors.

[0074] The inventors discovered that, in Examples 1 and 8, as the concentration of the peracetic acid solution increased and the concentration of the sodium hydroxide solution decreased, the degree of polymerization of cellulose also tended to decrease from 644.62 to 559.23. As the concentration of sodium hydroxide decreased, the degree of polymerization of cellulose decreased, and therefore it is believed that the effect of the sodium hydroxide concentration on the degree of polymerization of cellulose became smaller.

[0075] The higher the concentration of the peracetic acid solution of brewers' spent grains, the longer the soaking time, and the higher the soaking temperature, the easier it is for the cellulose in the brewers' spent grains to soak, and the more effectively the brewers' spent grains are removed, while still ensuring the desired effect of removing impurities. The higher the concentration of the alkaline solution, the higher the soaking temperature, and the longer the soaking time, the more effectively the brewers' spent grains are removed from impurities. Furthermore, by controlling the degree of polymerization of cellulose within a set range according to the user's needs, the utilization rate of the brewers' spent grains cellulose can be increased, preventing the extracted cellulose from being used to produce necessary products, thereby reducing production costs and improving economic efficiency.

[0076] To summarize the above, in this embodiment, after the brewer's spent grains are sequentially soaked in a sodium hydroxide solution and an acetic acid solution, the impurity removal effect of the brewer's spent grains is ensured, and then the parameters such as the soaking concentration, soaking temperature, and soaking time of the acetic acid solution or the sodium hydroxide solution are adjusted, thereby making it possible to obtain the cellulose degree of polymerization value required for the product.

[0077] From the comparison of Examples 1 to 10 above, it was found that the influence of the impregnation concentration of the acetic acid solution on the degree of polymerization of cellulose was relatively significant. However, when only the impregnation concentration of the acetic acid solution was changed, a positive ratio was shown with respect to the excess removal effect, and an inverse ratio was shown between the acetic acid concentration and the degree of polymerization of cellulose, making it difficult to accurately adjust the degree of polymerization of cellulose.

[0078] Furthermore, adjusting only the concentration of the sodium hydroxide solution also affects the degree of polymerization of cellulose. The concentration of the alkaline solution and the degree of polymerization of cellulose are inversely proportional, and the degree of polymerization value changes around the boundary value, making it difficult to accurately adjust the degree of polymerization.

[0079] Therefore, we discovered that by combining the soaking conditions of the peracetic acid solution and the sodium hydroxide solution while ensuring the decontamination effect of the brewer's spent grains, it is possible to combine any of the soaking concentrations, soaking temperatures, and soaking times.

[0080] Furthermore, the degree of polymerization of the cellulose extracted by the method of this embodiment can be ensured to be lower. For example, the degree of polymerization value for cellulose extraction can be accurately adjusted within a wide range of 375 to 830, and can be adjusted to the degree of polymerization required for the product according to actual needs.

[0081] The present invention provides cellulose extracted from brewers' spent grains with a complete structure and performance, which can be used to produce products with different toughness, high strength, and low strength according to product needs, thereby expanding the scope of use of brewers' spent grains cellulose and providing conditions for its industrial production.

[0082] Further comparative tests were conducted to verify that the mutual combination of impregnation parameters for the acidic and alkaline solutions in the present invention significantly affects the extraction purity and degree of polymerization of cellulose. Specific comparative test data are shown in Table 2.

[0083] [Table 2]

[0084] Comparative Example 1 differs from Example 1 in that the cellulose mixture was immersed in an alkaline solution and then in an acidic solution. The acidic solution was nitric acid, the alkaline solution was sodium hydroxide, the concentration of the nitric acid solution was 1%, the immersion time was 5 hours, the immersion temperature was 80°C, and the solid-liquid mass ratio of the brewers' spent grains to the nitric acid solution was 1 / 20, but under these conditions, cellulose could not be extracted from the brewers' spent grains.

[0085] As is well known, nitric acid is a strong acid. The soaking process of beer syrup destroys the cellulose structure in the syrup, leading to breakage of cellulose-based threads and increased susceptibility to hydrolysis, significantly reducing the purity of the cellulose. Even if the extraction purity is not reduced, the destruction of the cellulose results in a relatively poor toughness of the cellulose, making the extracted cellulose unsuitable for industrial applications, reducing the range of cellulose use and the utilization rate of the syrup. Furthermore, nitric acid is highly corrosive, posing safety risks during the process, requiring strict restrictions on operator skill, leading to increased labor costs. The cellulose mixture obtained by sequentially soaking the syrup in strong acid solutions such as sodium hydroxide solution and nitric acid, and then hydrolyzing most of the syrup with peracetic acid, contains a large amount of impurities, making it impossible to spin the resulting cellulose into fibers or to produce tough medical industrial products.

[0086] Comparative Example 2 differs from Example 1 in that the immersion parameter values ​​of the acidic solution exceed the upper limit of the immersion parameter values ​​in the present invention. Also, the alkaline solution is a sodium hydroxide solution, and the immersion parameter values ​​of the alkaline solution also exceed the upper limit of the parameter values ​​in the present invention.

[0087] In Comparative Example 2, 40 g of brewers' spent grains were soaked in a 2 mol / L sodium hydroxide solution at 140°C for 20 hours, and then further soaked in 20% peracetic acid at 100°C for 20 hours, resulting in a solid-liquid mass ratio of 1 / 20. Most of the cellulose in the brewers' spent grains was hydrolyzed with peracetic acid, resulting in a large amount of impurities in the resulting cellulose mixture. Therefore, a cellulose raw material from brewers' spent grains that could be used for thread or other processing could not be obtained.

[0088] As described above, Comparative Example 2 employs the same acidic and alkaline solutions as the present invention, but the impregnation parameters of the acidic and alkaline solutions are outside the set ranges, which damages the structure of the cellulose in the brewers' spent grains and reduces the purity of the extracted cellulose. This results in a decrease in the utilization rate of the extracted cellulose, resulting in a large amount of cellulose being wasted, increasing production costs and lowering the quality.

[0089] In Comparative Example 3, the soaking parameters for the acidic solution were higher than the upper limit of the parameter values ​​of the present invention. The alkaline solution was used under the same conditions as in Example 2, e.g., 40 g of brewers' spent grains were soaked in a 0.5 mol / L sodium hydroxide solution at 80°C for 5 hours. In Comparative Example 3, 10% peracetic acid was used and the soaking was carried out for 20 hours at 100°C. The acidic solution concentration was higher than the maximum of 5% of the acidic solution of the present invention, and the soaking time exceeded the maximum of 5 hours, making it an experiment with a completely excessive amount. As a result, no significant increase in the impurity removal rate was observed. Instead, hydrolysis of the brewers' spent grains cellulose was induced, leading to cleavage of the sugar chains in the brewers' spent grains cellulose, making it impossible to accurately determine the purity and degree of polymerization of the cellulose itself.

[0090] In Comparative Example 4, the concentration of the peracetic acid solution, the soaking temperature, and the soaking time were within the set ranges, while the concentration of the sodium hydroxide solution, the soaking time, and the solid-liquid mass ratio were higher than the upper limits of the set values, specifically compared with Example 2. When 40 g of raw brewers' spent grains were soaked in 2 mol / L sodium hydroxide at 140°C for 20 hours at a solid-liquid mass ratio of 1 / 20, and then soaked in 3% peracetic acid at 80°C for 5 hours at a solid-liquid mass ratio of 1 / 20, the impurity removal effect of the brewers' spent grains was 41%, and the degree of polymerization of cellulose was 701.28.

[0091] Therefore, under the conditions where the concentration of the acetic acid solution, the immersion temperature, and the immersion time are set, the concentration of the sodium hydroxide solution, the immersion time, and the immersion temperature are higher than the upper limit values, but the effect is small. To further verify that the combination of the parameters of the acidic and alkaline solutions of the present invention has a significant effect on the purity of cellulose extracted and the degree of polymerization of cellulose, several experiments were carried out. The specific experimental data are shown in Table 3 below.

[0092] [Table 3]

[0093] As shown in Table 3, in Experimental Examples 3 to 5, when the acetic acid concentration and soaking temperature were kept constant and the concentration of the sodium hydroxide solution was increased, if the soaking time in the acidic solution and the soaking time in the alkaline solution were the same, the degree of polymerization of cellulose was 726.14, but when the soaking time in the acidic solution was shortened and the soaking time in the alkaline solution was lengthened, the degree of polymerization of cellulose increased slightly to 727.69. On the other hand, when the soaking time in the acidic solution was lengthened and the soaking time in the alkaline solution was shortened, the degree of polymerization of cellulose decreased to 598.06.

[0094] Furthermore, with reference to Experimental Examples 1, 2, and 5, the degree of polymerization of cellulose decreased when the acetic acid concentration, sodium hydroxide concentration, and acetic acid immersion time were increased while keeping other values ​​constant. When the acetic acid immersion time was increased from 5 hours to 10 hours, the degree of polymerization of cellulose only decreased slightly, but when the peracetic acid immersion time was increased from 10 hours to 15 hours, the degree of polymerization of cellulose decreased rapidly. At this point, it can be determined that the peracetic acid immersion time had reached its upper limit.

[0095] Furthermore, referring to Experimental Examples 2 and 4, it can be seen that when the peracetic acid concentration was increased, the immersion time in the peracetic acid solution was shortened, and the immersion time in the alkaline solution was lengthened while maintaining the other conditions constant, the degree of polymerization of cellulose increased slightly.

[0096] The method for extracting cellulose from brewers' spent grains according to the present invention has been described above based on an embodiment, but the present invention is not limited to this. Various design modifications are possible as long as the object of the present invention can be achieved and the modifications do not deviate from the gist of the invention, and all of these modifications are included within the scope of the present invention. [Industrial Applicability]

[0097] The method for extracting cellulose from brewers' spent grains according to the present invention is suitable as a method for extracting cellulose from brewers' spent grains.

Claims

1. a pretreatment step of washing the beer spent material with water to obtain a first treated product; an alkaline solution immersion step in which the first treated material obtained in the pretreatment step is immersed in an alkaline solution to obtain a cellulose mixture; an acidic solution immersion step in which the cellulose mixture obtained in the alkaline solution immersion step is immersed in an acidic solution to obtain a purified cellulose product; Furthermore, the method includes a polymerization degree adjustment step of acquiring an extraction parameter value, which is a parameter for extracting cellulose, in at least one of the alkaline solution immersion step and the acidic solution immersion step, and adjusting the extraction parameter value to adjust the polymerization degree of cellulose. A method for extracting cellulose from brewer's spent grains, comprising:

2. The extraction parameter value adjusted in the polymerization degree adjusting step is at least one of the solution concentration, the solution amount, the solid-liquid mass ratio, the impregnation temperature, which is the temperature of the solution during immersion, and the impregnation time, which is the time for immersion.

2. The method for extracting cellulose from brewer's spent grains according to claim 1.

3. The alkaline solution in the alkaline solution immersion step is a sodium hydroxide solution; The acid solution in the acid solution immersion step is a peracetic acid solution.

3. The method for extracting cellulose from brewer's spent grains according to claim 2.

4. The concentration of peracetic acid in the peracetic acid solution is 1 to 5%.

4. The method for extracting cellulose from brewer's spent grains according to claim 3.

5. The temperature for impregnation in the peracetic acid solution is 60°C to 90°C.

4. The method for extracting cellulose from brewer's spent grains according to claim 3.

6. The impregnation time in the peracetic acid solution is 3 to 15 hours.

4. The method for extracting cellulose from brewer's spent grains according to claim 3.

7. The solid-liquid mass ratio of the cellulose mixture to the peracetic acid solution is 1 / 5 to 1 / 20.

4. The method for extracting cellulose from brewer's spent grains according to claim 3.

8. The sodium hydroxide concentration in the sodium hydroxide solution is 0.5 mol / L to 1.0 mol / L.

4. The method for extracting cellulose from brewer's spent grains according to claim 3.

9. The temperature of the alkaline solution in the alkaline solution immersion step is 80°C to 120°C, and the immersion time in the alkaline solution is 3 hours to 15 hours.

3. The method for extracting cellulose from brewer's spent grains according to claim 2.

10. Further, the method includes a washing step of washing the cellulose mixture obtained in the alkaline solution soaking step to neutralize it, In the acid solution immersion step, the cellulose mixture washed to neutrality in the washing step is immersed in an acid solution.

2. The method for extracting cellulose from brewer's spent grains according to claim 1.

11. Furthermore, the method includes a final washing step in which the purified cellulose obtained in the acidic solution soaking step is washed to neutralize it and obtain a cellulose extract. The method for extracting cellulose from brewer's spent grains according to claim 1 or 10.

Images