A method for separating protein and cellulose from beer spent grains

Abstract

The present invention discloses a method for separating protein and cellulose from beer spent grains, comprising: preparing spent grains slurry, subjecting the spent grains slurry to fungal enzymatic fermentation by Aspergillus oryzae, crushing the spent grains slurry after fungal enzymatic fermentation and subjecting it to microwave-assisted extraction to obtain assisted extraction slurry, subjecting the assisted extraction slurry to solid-liquid separation to obtain a liquid extract and a solid residue containing cellulose, injecting sodium chloride into the liquid extract to obtain a saturated liquid, injecting isopropyl alcohol into the saturated liquid, stirring and allowing it to stand to obtain a separated upper organic phase, an intermediate solid phase, and a lower aqueous phase, and transferring the intermediate solid phase to a microwave vacuum drying device for drying to obtain protein. The spent grains produced during the beer production process are fermented, crushed, extracted, and subjected to phase boundary separation to achieve simultaneous collection of protein and cellulose, facilitating conversion into high-value-added protein and cellulose products. This not only improves resource utilization and economic benefits, but also provides solid technical support for the sustainable development of the beer industry.

Description

Technical Field

[0001] The invention relates to the technical field of material separation, in particular to a method for separating protein and cellulose in beer spent grains. Background Art

[0002] Spent grains are produced during the saccharification and filtration steps of the beer brewing process. They are the insoluble part of malt and unmalted grain adjuncts after saccharification. According to statistics, more than 40 million tons of spent grains are produced in the beer production process worldwide each year, of which China produces more than 3 million tons annually. Fresh spent grains have a moisture content of up to 60% to 80% and are rich in various nutrients, such as protein (19-30%), cellulose (30-50%), carbohydrates, minerals and phenolic compounds (such as ferulic acid and p-coumaric acid). However, due to its high humidity and nutrient-rich properties, fresh spent grains are extremely susceptible to microbial contamination and quickly rot and deteriorate, making them difficult to store and transport. Of the large amount of waste generated by the beer brewing industry, 85% comes from spent grains. Due to its huge output and considerable concentration, spent grains have great resource development potential.

[0003] To extend the storage life of spent grains, the industry currently uses drying to reduce their moisture content. While drying effectively slows decay, it consumes significant amounts of heat energy, contradicting current low-carbon, energy-saving, and environmentally friendly goals. Dried spent grains are primarily sold as animal feed. While this allows for rapid disposal of large quantities of waste, its economic value is low and fails to fully tap into the rich protein and cellulose resources found in spent grains.

[0004] Currently, international markets and leading domestic companies typically sell dried spent grains directly as animal feed (primarily for cattle and pigs). This treatment method effectively prevents microbial proliferation and spoilage by quickly converting spent grains into feed. However, this treatment method has low economic added value, fails to fully tap the potential of spent grain resources, and incompletely utilizes them. This is especially true in coastal areas, where the livestock industry is less developed than in inland areas, making the sale and use of spent grains more difficult, leading to a more serious problem of resource waste. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides a method for separating protein and cellulose in beer spent grains, which can achieve efficient separation of protein and collection of cellulose in the same process.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A method for separating protein and cellulose from beer spent grains comprises: a spent grain slurry, wherein the spent grain slurry is subjected to fungal enzymatic fermentation by Aspergillus oryzae, the spent grain slurry after fungal enzymatic fermentation is crushed into target particles of 400 to 600 μm, and microwave-assisted extraction is performed to obtain an assisted extraction slurry, and the assisted extraction slurry is subjected to solid-liquid separation to obtain a liquid extract and a solid residue containing cellulose; sodium chloride is injected into the liquid extract to obtain a saturated liquid, 1:1 isopropanol is injected into the saturated liquid in a volume ratio, and the mixture is stirred and allowed to stand to obtain a separated upper organic phase, an intermediate solid phase, and a lower aqueous phase, and the intermediate solid phase is transferred to a microwave vacuum drying device for drying to obtain protein; the spent grain slurry after fungal enzymatic fermentation facilitates protein decomposition in the spent grains, thereby facilitating subsequent protein extraction and purification steps; the spent grain slurry after fungal enzymatic fermentation is crushed to facilitate subsequent solid-liquid separation of the assisted extraction slurry; the microwave-assisted extraction increases the porosity of the spent grain cell walls, allowing the solvent to penetrate the cells more effectively. The enhanced permeability is conducive to the effective release of protein into the solvent, thereby promoting the extraction process and further releasing the protein in the spent grains slurry after fungal enzymatic hydrolysis and fermentation.

[0008] Preferably, by volume, malt grains and water are respectively injected into a stirring device at a solid-liquid ratio of 2 to 3:1, and stirred at a stirring speed of 60 to 70 r / min for 10 to 15 minutes to form malt grains slurry.

[0009] Preferably, the malt grains slurry is subjected to fungal enzymatic fermentation by 3-6‰ Aspergillus oryzae, based on mass percentage, and the pH value of the fungal enzymatic fermentation is 6.0-8.0, the temperature is 36±2° C., and the time is 35-37 h.

[0010] Preferably, the temperature of the spent grains slurry during the crushing process does not exceed 45° C. to prevent the protein in the spent grains from being denatured and damaged due to excessively high temperatures.

[0011] Preferably, the temperature of microwave-assisted extraction is 55±5° C., the time is 20 to 25 min, and the stirring speed is 70 to 75 r / min.

[0012] Preferably, the auxiliary extraction slurry is filtered through a filtering device, the filter screen of the filtering device is 100-150 μm, and the filtering pressure is 0.3-0.5 MPa.

[0013] Preferably, after the isopropyl alcohol is injected into the saturated liquid, the stirring time is 30 to 35 minutes, the stirring speed is 70 to 75 r / min, and the standing time is 2 to 3 hours.

[0014] Preferably, the upper organic phase is distilled by a distiller at a temperature range of 85±2° C., the isopropyl alcohol vapor obtained by distillation is condensed by a condenser at a temperature of 4° C., and the isopropyl alcohol liquid obtained by condensation is again distilled and condensed to obtain purified isopropyl alcohol, thereby realizing the recovery of isopropyl alcohol.

[0015] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0016] A method for separating protein and cellulose in beer spent grains.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. The present invention achieves the simultaneous collection of protein and cellulose by fermenting, crushing, extracting and phase boundary separation of the spent grains produced in the beer production process, facilitating their conversion into high-value-added protein and cellulose products. This not only improves resource utilization and economic benefits, but also provides solid technical support for the sustainable development of the beer industry.

[0019] 2. The present invention adopts Aspergillus oryzae to perform fungal enzymatic fermentation on the malt grains slurry. Aspergillus oryzae is a strain used in soy sauce brewing. Fungal fermentation is highly safe and does not cause pollution to the environment.

[0020] 3. When performing phase boundary separation on the liquid extract in the auxiliary extraction slurry, the present invention uses sodium chloride that can be directly discharged for salting out, and uses isopropyl alcohol with little harm as a separating agent. The separated organic phase containing isopropyl alcohol is purified by distillation and condensation, and the isopropyl alcohol is recovered and reused, thereby reducing the consumption of organic solvents. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The present invention is a process flow chart for separating protein and cellulose from spent grains. DETAILED DESCRIPTION

[0022] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with examples and drawings. The exemplary embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention.

[0023] 1. Implementation

[0024] This embodiment can convert the spent grains produced during the beer production process into protein and cellulose products with high added value, which not only improves resource utilization and economic benefits, but also provides solid technical support for the sustainable development of the beer industry, effectively solves the problem of insufficient utilization of spent grains resources, and promotes the process of green manufacturing and circular economy.

[0025] Specifically, such as Figure 1 As shown, the method for separating protein and cellulose in beer spent grains comprises the following steps:

[0026] 1. Preparation of spent grain slurry

[0027] Fresh grains are introduced into a stirring device, and water is added according to a solid-liquid ratio of 2 to 3:1, that is, 1 to 3 kg of water is added for every 2 kg of fresh grains, and then stirred at a stirring speed of 60 to 70 r / min for 10 to 15 minutes to form a uniform preliminary mixed slurry - grains slurry slurry.

[0028] 2. Fungal fermentation

[0029] The malt grains slurry was inoculated and subjected to fungal enzymatic fermentation by 3-6‰ Aspergillus oryzae, calculated on a mass per thousand basis, to improve the protein extraction efficiency. The pH value of the fungal enzymatic fermentation was 6.0-8.0, the temperature was 36±2°C, and the time was 35-37h.

[0030] 3. Crushing

[0031] The fermented spent grains slurry is refined by a high-speed grinder set at 6000r / min and a processing time of 15min. At the same time, the temperature is ensured not to exceed 45°C during the grinding process to prevent the protein in the spent grains from being denatured and damaged due to excessively high temperatures. The target particle size is finally reached at 400-600μm. The fermented spent grains slurry is facilitated by grinding for subsequent extraction and separation.

[0032] 4. Microwave-assisted extraction

[0033] The crushed grains slurry is subjected to microwave-assisted extraction treatment through a microwave-assisted extraction system. The microwave-assisted extraction system includes a processing tank, and a microwave heating device and a stirrer provided on the processing tank. Specifically, the power of the microwave heating device is set to 750-800 watts, the extraction temperature is set to 55±5°C, the extraction time is set to 20-25 minutes, and the stirring speed of the stirrer is set to 70-75 r / min. The protein is further released through microwave heating and stirring to form a uniform assisted extraction slurry.

[0034] 5. Preliminary filtration

[0035] The auxiliary extraction slurry is subjected to solid-liquid separation by a filtration device, wherein the filter screen of the filtration device is 100 to 150 microns and the operating pressure is set to 0.3 to 0.5 MPa. The filter screen is used for preliminary filtration to remove insoluble solids, and the filtered liquid extract and the solid residue containing cellulose are collected separately. The solid residue containing cellulose is directly collected for other related applications.

[0036] 6. Phase boundary separation

[0037] Sodium chloride is gradually added to the liquid extract to saturate the solution, and the mixture is fully stirred with a stirrer to obtain a saturated liquid; 1:1 isopropanol is injected into the saturated liquid by volume, and stirred at a stirring speed of 70 to 75 r / min for 30 to 35 minutes, and then allowed to stand for 2 to 3 hours to ensure complete separation of the upper organic phase, the middle solid phase and the lower aqueous phase.

[0038] 8. Phase collection

[0039] The upper organic phase and the lower aqueous phase are respectively discharged into corresponding treatment devices for treatment and discharge, and the middle solid phase is collected by a solid layer collection device and transferred to a microwave vacuum drying device for drying to obtain protein.

[0040] 8.1. Organic solvent recovery

[0041] The upper organic phase is injected into a distiller through a pipeline and distilled at a temperature range of 85±2° C. The isopropyl alcohol vapor obtained by distillation is condensed at a temperature of 4° C. through a condenser. The isopropyl alcohol liquid obtained by condensation is again distilled and condensed to obtain purified isopropyl alcohol. The purified isopropyl alcohol is again separated from the phase boundary and recycled.

[0042] 8.2 Drying

[0043] The collected intermediate solid phase is transferred to a microwave vacuum condensation drying device for drying. The microwave vacuum condensation drying device includes a drying chamber, a microwave heating device and a condenser arranged in the drying chamber. Specifically, during drying, the microwave power is set to 1.0-1.5 kW, the vacuum degree in the drying chamber is set to 45-50 mbar, the temperature is controlled to 60-65°C, the drying time is set to 30-40 minutes, the material thickness is 2-3 cm, and the condenser temperature is -20--30°C to remove moisture and obtain a dried protein product.

[0044] 2. The method proposed in this solution is environmentally friendly, efficient, and economical. This embodiment will discuss the three aspects of technology, benefits, and products, as follows:

[0045] 1.Technological advantages

[0046] 1.1. Significantly improve separation and extraction efficiency

[0047] Fungal fermentation:

[0048] Existing technology: Traditional methods may only perform physical or chemical pretreatment, which has limited separation efficiency, pollutes the environment, and has high economic costs.

[0049] This solution: By introducing Aspergillus oryzae fermentation, the fungus produces a variety of enzymes (such as protease and cellulase) during the fermentation process, which can effectively decompose the protein and cellulose in the spent grains and improve the subsequent extraction efficiency.

[0050] Advantages: While ensuring green and safe conditions, it significantly improves the decomposition rate of protein and cellulose, facilitates subsequent extraction and purification steps, and reduces production costs.

[0051] 1.2. Maintain biological activity

[0052] Gentle phase boundary separation:

[0053] Existing technology: Using strong acids or strong bases for protein precipitation may cause denaturation of certain proteins.

[0054] This solution: When performing phase boundary separation on the liquid extract in the auxiliary extraction slurry, sodium chloride that can be directly discharged is used for salting out, and isopropyl alcohol with little harm is used as a separating agent to separate the protein. The mild operating conditions have little damage to the biological activity of the protein.

[0055] Advantages: A milder separation environment can effectively protect the native structure and functional activity of proteins.

[0056] 2. Efficiency advantage

[0057] 2.1. Improve environmental performance

[0058] Reduce the use of organic solvents:

[0059] Existing technology: Traditional wet separation technology uses a large amount of organic solvents, which may cause significant pollution to the environment.

[0060] This solution optimizes the solvent based on the three-phase distribution method, using isopropyl alcohol, which is safer and has a lower boiling point, to replace tert-butyl alcohol, and sodium chloride, which is greener, more environmentally friendly and cheaper, to replace ammonium sulfate. In the phase boundary separation process, more environmentally friendly organic solvents are used, and solvent use is minimized through recycling.

[0061] Advantages: Reduced emissions of organic solvents, reduced environmental pollution, meets environmental protection requirements, and reduces environmental protection costs.

[0062] 2.2. Simultaneous separation of protein and collection of cellulose

[0063] Double-effect collection:

[0064] Existing technology: In traditional separation processes, the extraction of protein and cellulose is often divided into independent steps, which is not efficient.

[0065] This solution: The preliminary filtration step can collect the solid residue, which is mainly cellulose, while performing protein separation.

[0066] Advantages: Efficiently separate protein and collect cellulose in the same process, simplifying the operation process and improving resource utilization.

[0067] 3. Product advantages

[0068] 3.1 Nutritional richness and functionality of protein extracted from spent grains

[0069] Wide range of application scenarios:

[0070] Existing technology: Traditional protein extraction products usually have low nutritional value and less functionality, which limits their application range.

[0071] This solution: The malt grains protein extracted through Aspergillus oryzae fermentation and mild phase boundary separation not only retains rich nutrients, but also maintains excellent functionality, such as good antioxidant and emulsifying properties. At the same time, Aspergillus oryzae fermentation helps to further improve the bioavailability and digestibility of the protein.

[0072] Advantages: Spent grain protein has high nutritional value and functionality, making it suitable for use in high-quality food additives, nutritional supplements, and functional foods, meeting the needs of a healthy diet. Furthermore, its antioxidant properties can also be used in cosmetics.

[0073] 3.2 High-value utilization of cellulose

[0074] High value utilization:

[0075] Existing technology: Traditional spent grain processing generally discards the remaining residue directly after protein extraction, or only prepares cellulose into basic cellulose products such as pulp or cellulosic ethanol, failing to fully realize its potential in high-performance materials.

[0076] This solution: Through dual-effect collection, the cellulose in the spent grains residue after protein extraction is effectively converted into cellulose nanofibers (CNF). CNF has excellent mechanical properties, low density, good biodegradability and environmental performance, and can be used to prepare high-performance composite materials, environmentally friendly packaging materials and pharmaceutical applications.

[0077] Advantages: Utilizing cellulose as nanomaterials not only increases the added value of resources, but also expands the application areas of cellulose, meets the needs of sustainable development, and brings greater market potential and economic benefits.

[0078] 3. Conclusion

[0079] 1. This solution improves and optimizes existing separation and extraction methods, offering technical and equipment advantages such as cost control, material recycling, high efficiency, and ease of scale-up, thus possessing significant potential for industrial-scale application. Furthermore, the resulting protein possesses diverse functionalities and wide-ranging applications, potentially enabling conversion into high-value-added products. Cellulose can also be prepared into high-value-added cellulose nanofibers.

[0080] 2. This approach utilizes fermentation with specific fungi (such as Aspergillus oryzae). During fermentation, the fungi produce a variety of enzymes (such as proteases and cellulases) that efficiently break down the protein and cellulose in the spent grains, aiding in subsequent extraction and purification steps. This replaces the traditional method of directly adding enzymes, significantly reducing costs. Furthermore, microwave-assisted extraction technology facilitates the separation and extraction of protein and cellulose, resulting in a more functional protein.

[0081] 3. Phase boundary separation uses an isopropanol / sodium chloride system for protein separation. The mild operating conditions minimize damage to protein biological activity. This replaces the use of strong acids or bases for protein precipitation, thus avoiding the potential denaturation of certain proteins. Furthermore, traditional wet separation techniques use large amounts of organic solvents, which can cause significant environmental pollution. Phase boundary separation systems utilize more environmentally friendly organic solvents, optimize their usage, and minimize solvent usage through recovery systems.

[0082] 4. In traditional separation processes, protein and cellulose extraction are often performed in separate, inefficient steps. This initial filtration step allows for simultaneous protein separation and crude cellulose collection, streamlining the process and improving resource utilization.

[0083] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art may make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications should all fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for separating protein and cellulose from beer spent grains, characterized in that: The method comprises: subjecting the spent grains slurry to fungal enzymatic hydrolysis and fermentation by Aspergillus oryzae, crushing the spent grains slurry after fungal enzymatic hydrolysis and fermentation into target particles of 400 to 600 μm, subjecting the slurry to microwave-assisted extraction to obtain assisted extraction slurry, and subjecting the assisted extraction slurry to solid-liquid separation to obtain a liquid extract and a solid residue containing cellulose; Sodium chloride is injected into the liquid extract to obtain a saturated liquid, and 1:1 isopropyl alcohol is injected into the saturated liquid in a volume ratio, and the mixture is stirred and allowed to stand to obtain a separated upper organic phase, an intermediate solid phase, and a lower aqueous phase. The intermediate solid phase is transferred to a microwave vacuum drying device for drying to obtain protein.

2. The method for separating protein and cellulose from beer spent grains according to claim 1, wherein: In terms of volume ratio, the spent grains and water are respectively injected into a stirring device at a solid-liquid ratio of 2 to 3:1, and stirred at a stirring speed of 60 to 70 r / min for 10 to 15 minutes to form the spent grains slurry.

3. The method for separating protein and cellulose from beer spent grains according to claim 1, wherein: The malt grains slurry is subjected to fungal enzymatic fermentation by 3-6‰ Aspergillus oryzae on a mass per thousand basis, with the pH value of the fungal enzymatic fermentation being 6.0-8.0, the temperature being 36±2° C., and the time being 35-37 hours.

4. The method for separating protein and cellulose from beer spent grains according to claim 1, wherein The temperature of the spent grains slurry during the crushing process does not exceed 45°C.

5. The method for separating protein and cellulose from beer spent grains according to claim 1, wherein The microwave-assisted extraction is performed at a temperature of 55±5° C., for a time of 20 to 25 minutes, and at a stirring speed of 70 to 75 r / min.

6. The method for separating protein and cellulose from beer spent grains according to claim 1, wherein: The auxiliary extraction slurry is filtered through a filtering device, the filter screen of the filtering device is 100-150 μm, and the filtering pressure is 0.3-0.5 MPa.

7. The method for separating protein and cellulose from beer spent grains according to claim 1, wherein: The stirring time of the isopropyl alcohol after the saturated liquid is injected is 30 to 35 minutes, the stirring speed is 70 to 75 r / min, and the standing time is 2 to 3 hours.

8. The method for separating protein and cellulose from beer spent grains according to any one of claims 1 to 7, characterized in that: The upper organic phase is distilled by a distiller at a temperature range of 85±2° C., the isopropyl alcohol vapor obtained by distillation is condensed by a condenser at a temperature of 4° C., and the isopropyl alcohol liquid obtained by condensation is again distilled and condensed to obtain purified isopropyl alcohol.

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