A clean production process for the co-production of beer yeast powder and extract

Abstract

The application discloses a kind of beer yeast powder and extract co-production clean production method, belong to the field of bioengineering technology, beer yeast mud is divided into two after impurity rinsing and is carried out directional classification utilization: first slurry is added flavor accelerator, beta-mannanase and 5 '-phosphodiesterase and is carried out autolysis and breaks wall, and enzyme is prepared after being killed Enzymatic broken wall type beer yeast dry powder by whole spray drying;Second slurry is treated by alkali washing using sodium hydroxide, realizes thorough debittering while making cell wall fully loose, then it is autolyzed by endogenous enzyme and is prepared yeast extract by centrifugal separation, concentration and drying, and beta-1,3-glucan is prepared by alkali purification of centrifugal precipitate.The application uses the above-mentioned beer yeast powder and extract co-production clean production method, by waste yeast mud is classified and utilized according to specific proportion, broken wall type beer yeast dry powder, pure product type yeast extract is prepared respectively, and the diversification output of raw material product is realized.

Description

Technical Field

[0001] This invention relates to the field of bioengineering technology, and in particular to a clean production method for the co-production of brewer's yeast powder and extract. Background Technology

[0002] The beer brewing process generates a large amount of waste yeast sludge (beer waste yeast). Statistics show that approximately 1.5-2.0 kg of beer waste yeast is produced for every ton of beer produced; a brewery with an annual production capacity of 100,000 tons can generate 150-200 tons of beer waste yeast annually. Beer waste yeast is rich in protein (approximately 40%-50%), nucleic acids (approximately 6%-10%), B vitamins, beta-glucan, mannan, and various growth factors, making it a high-quality raw material for producing yeast powder, yeast extract, and functional polysaccharides. Globally, about one-third of food is lost or wasted each year; therefore, promoting the resource utilization of industrial by-products has become an important direction for the development of a circular economy.

[0003] Currently, existing technologies for producing yeast powder and yeast extracts from waste brewer's yeast mainly have the following problems: First, the products are limited and resource utilization is low. Existing technologies mostly focus on the production of a single product, such as producing only yeast extract or only yeast powder. However, these technical solutions only focus on the recovery of solid by-products, and the treatment of liquid by-products remains at the end-of-pipe treatment stage, failing to achieve the resource recovery of waste liquid.

[0004] Secondly, the cost of wastewater treatment is high, and the environmental pressure is significant. The production of yeast extract generates a large amount of high-concentration organic wastewater (COD can reach tens of thousands of mg / L). Existing technologies mostly use anaerobic-aerobic biological treatment to meet discharge standards, which not only results in high operating costs but also causes a huge waste of soluble nutrients such as proteins, amino acids, and nucleotides in the wastewater.

[0005] In conclusion, developing a clean production method for waste beer yeast is of great significance for improving the resource utilization level of beer by-products and reducing the environmental pollution load of the yeast processing industry. Summary of the Invention

[0006] The purpose of this invention is to provide a clean production method for the co-production of brewer's yeast powder and extract. By classifying and utilizing waste yeast sludge in a specific ratio, high-digestibility enzymatically hydrolyzed cell wall-broken brewer's yeast powder is prepared through dual-enzyme synergistic cell wall disruption. High-quality pure yeast extract is prepared through endogenous enzymatic hydrolysis after simultaneous thorough debittering and cell wall loosening by sodium hydroxide alkaline washing. This achieves differentiated processing of raw materials and diversified output of products.

[0007] To achieve the above objectives, the present invention provides a clean production method for the co-production of brewer's yeast powder and extract, comprising the following steps: S1. Raw material pretreatment: The beer yeast mud produced during beer brewing is sieved and washed to obtain purified yeast mud; S2. Divide the purified yeast mud into a first slurry and a second slurry, and make the first slurry and the second slurry into a first suspension and a second suspension, respectively. S3. Add flavor promoter, β-mannanase and 5'-phosphodiesterase to the first suspension, break the cell wall and inactivate the enzyme to obtain a cell wall broken slurry, and spray dry the cell wall broken slurry to obtain enzymatically hydrolyzed cell wall broken brewer yeast dry powder. S4. Add sodium hydroxide to the second suspension, stir to wash away bitterness with alkali and loosen the cell wall at the same time, then add hydrochloric acid to neutralize, use endogenous enzyme autolysis to perform enzymatic hydrolysis, then inactivate the enzyme, centrifuge to separate the supernatant and precipitate, take the supernatant and vacuum concentrate or vacuum concentrate and spray dry to obtain pure yeast extract, and keep the precipitate for later use. S5. Add the precipitate obtained in S4 to sodium hydroxide solution for alkaline treatment. After treatment, centrifuge to collect the insoluble matter. Wash the insoluble matter until neutral and then vacuum dry to obtain β-1,3-glucan. S6. Collect the washing wastewater and concentrated condensate generated in S3 and S4, and treat them through an ultrafiltration and nanofiltration series system to obtain permeate. The permeate is recycled in S2, and the concentrated liquid is spray-dried to obtain protein feed additive. S7 collects the exhaust gas from spray drying and the secondary steam from vacuum concentration, and transfers the heat to the circulating hot water through a plate heat exchanger, which is used for S3 and S4 respectively.

[0008] Preferably, in S2, the first slurry accounts for 60-80% of the total mass of the purified yeast slurry, the second slurry accounts for 20-40% of the total mass of the purified yeast slurry, the concentration of the first suspension is 5-20 wt%, and the concentration of the second suspension is 10-20 wt%.

[0009] Preferably, in S3, the flavor enhancer is a mixture of Na2CO3 and NaCl, with a mass ratio of 1:2 to 1:5, and a total mass percentage concentration of 1.0 to 5.0% in the slurry.

[0010] Preferably, in S3, the cell wall breaking temperature is 45-65℃, the cell wall breaking time is 6-16h, the enzyme inactivation temperature is 75-90℃, and the enzyme inactivation time is 0.5-1.5h.

[0011] Preferably, in S3, the amount of β-mannanase added is 0.3-1.0% of the mass of the first suspension, and the amount of 5'-phosphodiesterase added is 0.1%-0.5% of the mass of the first suspension.

[0012] Preferably, in step S4, sodium hydroxide is added to adjust the pH to 9-10, the concentration of sodium hydroxide is 1-5 mol / L, and hydrochloric acid is added to adjust the pH to 5.5-6.5.

[0013] Preferably, in S4, the autolysis temperature is 50-55℃, the autolysis time is 18-30h, the enzyme inactivation temperature is 80-85℃, and the enzyme inactivation time is 20-40min.

[0014] Preferably, in S4, a disc centrifuge is used for centrifugation, with a centrifugation speed of 5000-8000 rpm and a feed rate of 500-1000 L / h, and the obtained pure yeast extract is in the form of paste or powder.

[0015] Preferably, in S5, the specific conditions for adding sodium hydroxide solution for alkaline treatment are: adding 2-4 times the weight of 1-5wt% NaOH solution and treating at 70-85℃ for 2-3 hours.

[0016] Preferably, in S6, the ultrafiltration membrane used for ultrafiltration has a molecular weight cutoff of 3000-10000 Da, the nanofiltration membrane used for nanofiltration has a molecular weight cutoff of 200-500 Da, the operating pressure is 1-2.5 MPa, and the series system is cleaned by CIP every 8-12 hours.

[0017] Therefore, the present invention employs the above-mentioned clean production method for the co-production of brewer's yeast powder and extract, which has the following beneficial effects: (1) By classifying and utilizing waste yeast mud in a specific ratio, high-digestibility enzymatically hydrolyzed cell wall-breaking beer yeast dry powder is prepared by dual-enzyme synergistic cell wall breaking, and high-quality pure yeast extract is prepared by endogenous enzymatic hydrolysis after simultaneous sodium hydroxide alkaline washing to achieve thorough debittering and cell wall loosening. This achieves differentiated processing of raw materials and diversified output of products. (2) A three-in-one clean production closed-loop system was constructed, which integrates residue dextran production, waste liquid membrane separation and reuse, and waste heat cascade recovery. Solid residue, organic wastewater and process waste heat generated in the entire production process are fully recovered and recycled, realizing the integrated synergistic effect of one production line producing four products at the same time, closed-loop wastewater recycling and waste heat cascade utilization. (3) The cell wall breaking and opening of β-mannanase and the intracellular flavor enhancement of 5′-phosphodiesterase are inseparable. Waste heat recovery effectively offsets the energy consumption cost of graded co-production. Membrane reuse achieves environmental protection standards and by-product value-added at the same time. The absence or replacement of any link will lead to a significant deterioration in product quality or overall benefits.

[0018] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0019] Figure 1 This is a process flow diagram of a clean production method for co-producing brewer's yeast powder and extracts according to the present invention. Figure 2These are performance test results of Examples 1-3 and Comparative Examples 1-6 of the clean production method for co-producing brewer's yeast powder and extracts according to the present invention. Detailed Implementation

[0020] like Figure 1 As shown, the present invention provides a clean production method for the co-production of brewer's yeast powder and extract, comprising the following steps: S1. Raw material pretreatment: The beer yeast mud produced during beer brewing is sieved and washed to obtain purified yeast mud; The beer yeast sludge produced during beer brewing is filtered through a sieve to remove large solid impurities such as malt residue and hop residue. It is then rinsed with clean water to remove soluble pigments, hop tannins, and other water-soluble off-flavor substances, restoring the yeast cells to a clean state and providing standardized raw materials for subsequent processing. This process also avoids interference from impurities in subsequent enzymatic hydrolysis, alkaline washing, and membrane treatment processes.

[0021] S2. Divide the purified yeast mud into a first slurry and a second slurry, and make the first slurry and the second slurry into a first suspension and a second suspension, respectively. In S2, the first slurry accounts for 60-80% of the total mass of the purified yeast slurry, the second slurry accounts for 20-40% of the total mass of the purified yeast slurry, the concentration of the first suspension is 5-20wt%, and the concentration of the second suspension is 10-20wt%.

[0022] The purified yeast sludge is divided into two slurries in a specific ratio, and different concentrations are prepared according to the different subsequent processing routes of the two slurries. This provides suitable material basis for the enzymatic hydrolysis and cell wall breaking of S3 and the alkaline washing-enzymatic hydrolysis of S4, respectively. This enables the same raw material to achieve differentiated transformation under different process conditions, which determines the realization of multi-product co-production from the source.

[0023] S3. Add flavor promoter, β-mannanase and 5'-phosphodiesterase to the first suspension, break the cell wall and inactivate the enzyme to obtain a cell wall broken slurry, and spray dry the cell wall broken slurry to obtain enzymatically hydrolyzed cell wall broken brewer yeast dry powder. In S3, the flavor enhancer is a mixture of Na2CO3 and NaCl in a mass ratio of 1:2 to 1:5, with a total mass percentage concentration of 1.0% to 5.0% in the slurry. The cell wall disruption temperature is 45-65℃, and the disruption time is 6-16 h. The enzyme inactivation temperature is 75-90℃, and the inactivation time is 0.5-1.5 h. The amount of β-mannanase added is 0.3-1.0% of the mass of the first suspension, and the amount of 5'-phosphodiesterase added is 0.1%-0.5% of the mass of the first suspension.

[0024] This process utilizes β-mannanase to hydrolyze the mannan components of the outer layer of the yeast cell wall, disrupting the cell wall's structural integrity and facilitating the release of intracellular proteins, nucleic acids, and other nutrients during digestion. Then, 5′-phosphodiesterase enters the cell after the cell wall is disrupted and hydrolyzes ribonucleic acid to generate flavor nucleotides, enhancing the product's flavor quality. The enzymatic hydrolysis reaction is terminated by enzyme inactivation, followed by spray drying to produce a powdered product. This step achieves targeted disintegration of the yeast cell wall and flavor transformation of intracellular nutrients, endowing the product with both high digestibility and excellent flavor.

[0025] S4. Add sodium hydroxide to the second suspension, stir to wash away bitterness with alkali and loosen the cell wall simultaneously, then add hydrochloric acid to neutralize, and perform enzymatic hydrolysis using endogenous enzyme autolysis. After enzyme inactivation, centrifuge to obtain supernatant and precipitate. Take the supernatant and concentrate it under vacuum or spray dry it after vacuum concentration to obtain pure yeast extract. Pure yeast extract can be in paste or powder form; keep the precipitate for later use. In S4, sodium hydroxide (1-5 mol / L) is added to adjust the pH to 9-10, and hydrochloric acid is added to adjust the pH to 5.5-6.5. The autolysis temperature is 50-55℃, and the autolysis time is 18-30 h. The enzyme inactivation temperature is 80-85℃, and the inactivation time is 20-40 min. Centrifugation is performed using a disc centrifuge at 5000-8000 rpm, with a feed rate of 500-1000 L / h.

[0026] The alkalinity of sodium hydroxide achieves a triple function: saponifying the ester bonds in hop α-acids to completely remove bitterness; swelling and loosening the β-glucan network structure of the cell wall, providing a substrate release channel for endogenous enzymes; and prematurely dissolving impurity proteins bound to the cell wall, creating pre-enhanced conditions for subsequent glucan purification. After neutralization, the yeast's own endogenous proteases and nucleases are used for autolytic hydrolysis, degrading intracellular macromolecular proteins and nucleic acids into soluble flavor and nutrient components such as amino acids, peptides, and nucleotides. After centrifugation, the supernatant is concentrated and dried to produce a pure yeast extract.

[0027] S5. Add sodium hydroxide solution to the precipitate obtained after centrifugation in S4 for alkaline treatment. After treatment, centrifuge to collect the insoluble matter, wash the insoluble matter until neutral, and then vacuum dry to obtain β-1,3-glucan. In S5, the specific conditions for alkaline treatment with sodium hydroxide solution are as follows: add 2 to 4 times the weight of 1-5wt% NaOH solution and treat at 70-85℃ for 2-3 hours.

[0028] The precipitate (yeast residue, mainly composed of cell wall β-glucan) obtained by centrifugation in S4 was treated with sodium hydroxide solution to further remove residual proteins and mannan and other impurities. The insoluble matter was centrifuged and repeatedly washed until neutral. After drying, high-purity β-1,3-glucan was obtained, transforming the cell wall component that was originally discharged as waste into a high-value functional food raw material.

[0029] S6. Collect the washing wastewater and concentrated condensate generated in S3 and S4, and treat them through an ultrafiltration and nanofiltration series system to obtain permeate. The permeate is recycled in S2, and the concentrated liquid is spray-dried to obtain protein feed additive. In S6, the ultrafiltration membrane used has a molecular weight cutoff of 3000-10000 Da, and the nanofiltration membrane used has a molecular weight cutoff of 200-500 Da. The operating pressure is 1-2.5 MPa, and the series system is cleaned by CIP every 8-12 hours.

[0030] The washing wastewater and concentrated condensate generated in processes S3 and S4 are collected and separated by a series of ultrafiltration and nanofiltration membrane systems: large molecules such as proteins and polysaccharides are retained by the ultrafiltration membrane, while small molecules such as amino acids and nucleotides are retained by the nanofiltration membrane, and water and trace inorganic salts permeate through the membrane to form a clear liquid. The clear liquid is reused in the slurry preparation process to achieve water resource recycling, and the retained concentrate is spray-dried to produce protein feed additives, converting the organic matter in the wastewater into feed products, and achieving the dual goals of water reuse and by-product value-added.

[0031] S7 collects the exhaust gas from spray drying and the secondary steam from vacuum concentration, and transfers the heat to the circulating hot water through a plate heat exchanger, which is used for S3 and S4 respectively.

[0032] The high-temperature exhaust gas emitted during spray drying and the secondary steam generated by vacuum concentration are collected and transferred to the circulating hot water system through a plate heat exchanger. This is used for jacket insulation of the S3 and S4 self-dissolving processes, avoiding direct heat loss and reducing the dependence of the entire process on external steam and overall energy consumption.

[0033] The classification decision in S2 determines the material allocation for routes S3 and S4; the dual-enzyme cell disruption in S3 and the NaOH alkaline washing in S4 are two independent but complementary pretreatment strategies: the former improves the digestibility of yeast powder products, while the latter improves the yield and purity of extract products; the residues and wastewater generated from the two routes are respectively sent to S5 (residue) and S6 (wastewater) for end-of-pipe resource recovery; the waste heat recovery in S7 provides thermal energy for S3 and S4, reducing dependence on external energy. The entire process forms a three-stage utilization chain: S2 diversion - S3 / S4 parallel conversion - S5 solid residue purification / S6 waste liquid recovery / S7 waste heat recovery; the first stage realizes the conversion of raw materials into dual food-grade products, the second stage realizes the conversion of solid residues into functional polysaccharides, and the third stage realizes the resource and energy utilization of wastewater and waste heat. Ultimately, the goal is to achieve an integrated synergistic effect of co-production of four products, closed-loop wastewater recycling, and cascade utilization of waste heat. The absence or alteration of any link will disrupt the integrity and overall benefits of the entire chain.

[0034] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention should be considered equivalent substitutions and are included within the protection scope of the present invention. Furthermore, it should be understood that after reading the contents of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims and are all within the protection scope of the present invention.

[0035] In this document, references to embodiments mean that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The term "embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment, nor does it specifically limit its independence or connection with other embodiments. In principle, in this application, as long as there are no technical contradictions or conflicts, the technical features mentioned in each embodiment can be combined in any way to form corresponding implementable technical solutions.

[0036] Unless otherwise defined, the technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the use of related terms herein is merely for the purpose of describing particular embodiments and is not intended to limit this application.

[0037] In this invention, unless otherwise specified, all other test materials and instruments are conventional test materials in the field and can be purchased through commercial channels.

[0038] Example 1 This invention provides a clean production method for the co-production of brewer's yeast powder and extract, comprising the following steps: S1. Raw material pretreatment: The beer yeast sludge produced by beer brewing is sieved through an 80-mesh sieve to remove particulate impurities, and then rinsed with clean water until the conductivity of the washing liquid is ≤200μS / cm to obtain purified yeast sludge.

[0039] S2. Directional grading and slurry preparation: The purified yeast slurry is divided into a first slurry and a second slurry; the first slurry accounts for 70% of the total purified yeast slurry (140kg dry basis) and is prepared into a first suspension with a concentration of 10wt%; the second slurry accounts for 30% of the total purified yeast slurry (60kg dry basis) and is prepared into a second suspension with a concentration of 12wt%; the stirring speed is 90rpm and the time is 20 minutes.

[0040] S3. Preparation of enzymatically hydrolyzed, cell-wall-broken brewer's yeast dry powder: A flavor enhancer (total concentration 3.0%) composed of Na₂CO₃ and NaCl in a mass ratio of 1:3, along with β-mannanase (0.5% of the mass of the first suspension) and 5'-phosphodiesterase (0.2% of the mass of the first suspension) were added to the first suspension. The mixture was subjected to autolysis at 55℃ for 12 hours (stirring at 45 rpm); enzyme inactivation was performed at 85℃ for 1 hour; the entire cell-wall-broken slurry was then spray-dried (inlet air 180℃, outlet air 85℃) to obtain 68 kg of enzymatically hydrolyzed, cell-wall-broken brewer's yeast dry powder.

[0041] S4. Preparation of yeast extract: Add 2.5 mol / L food-grade sodium hydroxide to the second suspension to adjust the pH to 9.5, and stir at 35℃ for 1.0 hour (alkali washing achieves a synergistic effect of debittering and cell wall loosening; after treatment, the bitterness value is ≤2BU, and the cell wall porosity is increased by 2.31 times); then add food-grade hydrochloric acid to neutralize to pH 6.0, and autolyze using yeast endogenous enzymes at 52℃ for 24 hours; inactivate enzymes at 82℃ for 30 minutes; centrifuge in a disc (6500 rpm, continuous feed rate 800 L / h) to obtain supernatant and precipitate. Take the supernatant, concentrate under vacuum (-0.09 MPa, 65℃), and spray dry to obtain 29 kg of pure yeast extract. Take the precipitate for later use.

[0042] Preparation of S5 and β-1,3-glucan: The S4 precipitate was added to 3 times its weight of 3wt% NaOH solution and treated at 78℃ for 2.5 hours; the insoluble matter was collected by centrifugation and repeatedly washed with deionized water until the conductivity was ≤50μS / cm; it was dried in a vacuum oven (55℃, -0.09MPa) to obtain 13kg of β-1,3-glucan (purity 87.2%).

[0043] S6. Wastewater Membrane Separation and Water Reuse: Washing wastewater and concentrated condensate from S3 and S4 are collected and treated by a series system of ultrafiltration (MWCO 5000Da, PES material) and nanofiltration (MWCO 300Da, PA material) (operating pressure 1.8MPa, 30℃, system recovery rate 88%). All permeate is reused for S2 slurry preparation. The concentrate is spray-dried to obtain 19kg of protein feed additive. The membrane system undergoes CIP cleaning every 10 hours of operation (0.3wt% NaOH solution circulation cleaning for 30 minutes, followed by rinsing with deionized water until neutral).

[0044] S7. Waste Heat Recovery: Collects spray drying exhaust gas and vacuum concentrated secondary steam, and processes them through a plate heat exchanger (heat exchange area 20m²). 2 Overall heat transfer coefficient 800W / m 2 ·K) Transfers heat to circulating hot water, which is used for jacket insulation of S3 autolytic cell disruption and S4 autolytic enzymatic hydrolysis, covering 65% of the heat demand of the two processes, with a comprehensive energy consumption of 145 kgce / t raw material.

[0045] Example 2 The only difference between this embodiment and embodiment 1 is that in S2, the first slurry accounts for 60% of the total mass of the purified yeast slurry, and the second slurry accounts for 40% of the total mass of the purified yeast slurry; all other conditions are the same.

[0046] Example 3 The only difference between this embodiment and embodiment 1 is that in S2, the first slurry accounts for 80% of the total mass of the purified yeast slurry, and the second slurry accounts for 20% of the total mass of the purified yeast slurry; all other conditions are the same.

[0047] Comparative Example 1 The only difference between this comparative example and Example 1 is that in S2, all the purified yeast sludge was made into a suspension with a concentration of 12wt%, which was used entirely in the yeast extract production in S4. The yeast powder production in S3 was not carried out. All other conditions were the same.

[0048] Comparative Example 2 The only difference between this comparative example and Example 1 is that in S2, all the purified yeast sludge was made into a suspension with a concentration of 10wt%, which was used entirely for the production of yeast dry powder in S3. The production of extracts and the recovery of related by-products in S4 were not carried out. All other conditions were the same.

[0049] Comparative Example 3 The only difference between this comparative example and Example 1 is that sodium hydroxide is not added in S4, and a conventional 0.5% NaHCO3 solution is used for debittering treatment, with stirring for 1 hour. All other conditions are the same.

[0050] Comparative Example 4 The only difference between this comparative example and Example 1 is that β-mannanase is not added in S3, while all other conditions are the same.

[0051] Comparative Example 5 The only difference between this comparative example and Example 1 is that 5'-phosphodiesterase is not added in S3; all other conditions are the same.

[0052] Comparative Example 6 The only difference between this comparative example and Example 1 is that neither β-mannanase nor 5'-phosphodiesterase was added in S3; all other conditions were the same.

[0053] Performance tests were conducted on the products of Examples 1-3 and Comparative Examples 1-6: 1. Protein dissolution rate: Following GB 5009.5-2016 "National Food Safety Standard - Determination of Protein in Food" Method 1 (Kjeldahl method), the protein content was determined using water extraction. Specific procedure: Weigh 5.0 g of sample, add 50 mL of deionized water, and extract by shaking at 37℃ for 2 hours. Centrifuge (4000 rpm, 15 minutes) and collect the supernatant. Determine the protein content in the supernatant. Protein dissolution rate (%) = (protein content in supernatant / total protein content in sample) × 100%.

[0054] 2. In vitro digestibility: Adjusted according to GB / T 17811-2025 "Determination of pepsin digestibility of animal-derived protein feed - filtration method", combined with an in vitro digestion model of human food. Specific operating steps are as follows: (1) Weigh 2.0 g of the sample (accurate to 0.0001 g) and place it in a 250 mL Erlenmeyer flask; (2) Add 50 mL of 0.1 mol / L HCl solution (containing pepsin, enzyme activity ≥3000 U / mg, concentration 2.0 g / L), adjust the pH to 1.5 ± 0.1, and digest in a constant temperature water bath at 37℃ for 2 hours (oscillation frequency 120 times / min). (3) Adjust the pH to 6.8±0.1 with 1.0mol / L NaOH solution, add trypsin (enzyme activity ≥4000U / mg, concentration 1.0g / L), and continue to digest by shaking at 37℃ for 4 hours (shaking frequency 120 times / min). (4) After digestion, the digestion solution was centrifuged at 4000 rpm for 15 minutes, and the supernatant was taken to determine the protein content (Kjeldahl method). (5) Simultaneously determine the total protein content of the sample; (6) In vitro digestibility (%) = (mass of protein in supernatant after digestion / total protein mass in sample) × 100%.

[0055] 3. β-1,3-glucan purity: determined by enzymatic hydrolysis-high performance liquid chromatography (enzymatic-HPLC). Specific procedure: Weigh 0.1 g of sample, add 5 mL of specific β-1,3-glucanase (activity ≥100 U / mg), and hydrolyze at 40℃ for 4 hours. The glucose produced by enzymatic hydrolysis is quantitatively determined by high performance liquid chromatography (differential refractive index detector). β-1,3-glucan purity (%) = (mass of glucose produced by enzymatic hydrolysis × 0.9) / sample mass × 100%.

[0056] 4. Bitterness value: Determined according to the isooctane extraction-spectrophotometric method in GB / T 4928-2026 "Analytical Methods for Beer". Specific procedure: After acidification and isooctane extraction, the absorbance is measured at a wavelength of 275 nm, expressed in International Units of Bitterness (BU).

[0057] The test results are shown in Table 1.

[0058] Table 1 Performance Test Results

[0059] From Table 1 and Figure 2 It can be known that: (1) Comparison of Comparative Example 4 and Example 1: By simply removing β-mannanase, the protein dissolution rate plummeted from 89.2% to 68.3%, a decrease of 20.9 percentage points, or 23.4%. This fully demonstrates that β-mannanase, by hydrolyzing the mannan components of the outer layer of the yeast cell wall and disrupting cell wall integrity, is a key enzyme determining whether intracellular proteins can be effectively released. β-mannanase is the core material for achieving high protein dissolution rate in the technical solution of this invention.

[0060] Comparative Example 5 with Example 1: By simply removing 5′-phosphodiesterase, the protein dissolution rate decreased slightly from 89.2% to 88.5% (a decrease of only 0.7 percentage points). This indicates that the function of 5′-phosphodiesterase is not to disrupt cell walls, which is completely consistent with the present invention's description of the enzyme (entering the cell to hydrolyze RNA to generate flavor nucleotides).

[0061] Comparison Example 6 with Example 1: With both enzymes removed, the protein dissolution rate decreased to 62.7%, a further decrease of 5.6 percentage points compared to Comparative Example 4 (without β-mannanase). This indicates that although 5′-phosphodiesterase cannot directly disrupt the cell wall, the weak hydrolytic effect of 5′-phosphodiesterase on residual cell wall structures after β-mannanase disruption contributes to protein release.

[0062] Comparison Example 2 with Example 1: The protein dissolution rate when producing full-volume yeast powder was 89.0%, which was basically the same as that in Example 1 (89.2%). This indicates that the fractional utilization (diverting 30% of the raw materials for extract production) did not affect the protein dissolution performance of the yeast powder, verifying the feasibility of the fractional co-production process.

[0063] In summary, β-mannanase is the core material for improving protein dissolution rate, and its role is irreplaceable. In the dual-enzyme system of this invention, β-mannanase is responsible for cell wall disruption, while 5′-phosphodiesterase is responsible for flavor enhancement. Their functions are clearly defined, and neither can be dispensed with.

[0064] (2) Comparison of Comparative Example 4 and Example 1: The in vitro digestibility decreased from 82.1% to 65.1%, a decrease of 17 percentage points, or 20.7%. In vitro digestibility directly reflects the degree to which the human body can utilize the nutrients in the product: when the cell wall is not sufficiently broken down, digestive enzymes (pepsin, trypsin) cannot penetrate the intact cell wall to contact intracellular proteins, resulting in a large amount of protein being excreted with the residue and not being digested and absorbed by the human body. This significant difference in data establishes a direct link between the microscopic phenomenon of enzyme cell wall breaking and the macroscopic value of the product being more nutritious for the human body.

[0065] Comparing Comparative Example 6 with Example 1: the in vitro digestibility decreased from 82.1% to 58.4%, a reduction of 23.7 percentage points. Compared to the in vitro digestibility of native yeast (21.6%, baseline), Example 1 showed a 280% improvement, while Comparative Example 6 only showed a 170% improvement. The improvement in digestibility brought by the complete dual-enzyme treatment (280%) is far greater than that of the enzyme-free treatment (170%). The 110 percentage point difference between the two is direct quantitative evidence of the contribution of β-mannanase to cell wall disruption.

[0066] Comparing Comparative Example 2 with Example 1, the in vitro digestibility rates were 81.9% and 82.1%, respectively, which were essentially the same. This further demonstrates that graded utilization has no negative impact on the product quality of yeast powder.

[0067] In summary, in vitro digestibility is positively correlated with protein dissolution rate (correlation coefficient R). 2 (≈0.98), both of which verify the same core mechanism: the more fully β-mannanase disrupts the cell wall, the easier it is for intracellular nutrients to be digested and absorbed by the human body. In vitro digestibility is a functional verification of the cell wall disruption effect from the perspective of human nutrient accessibility. The two methods corroborate each other and lead to the same conclusion.

[0068] (3) Comparison of Comparative Example 1 and Example 1: Comparative Example 1 did not employ graded utilization; all raw materials were used for extract production. Simultaneously, NaHCO3 was used for debittering, resulting in a dextran purity of only 60%, a decrease of 27.2 percentage points compared to Example 1 (87.2%). This indicates that when all raw materials are used for extract production, a large number of cell wall components are damaged or mixed during the extraction process, severely degrading the raw material basis for subsequent dextran extraction. Graded utilization ensures a purer source of cell wall residue, a prerequisite for guaranteeing high-purity dextran extraction.

[0069] Comparison of Comparative Example 3 and Example 1: Both used fractional co-production, the difference being the debittering agent; Comparative Example 3 used NaHCO3 (weak base), while Example 1 used NaOH (strong base, pH 9.5). The dextran purity of Comparative Example 3 was 82%, 5.2 percentage points lower than that of Example 1 (87.2%). This indicates that NaOH alkaline washing not only has a better debittering effect, but also promotes the early dissolution of impurities such as proteins and mannan bound to the cell wall by fully swelling and loosening the β-glucan network structure of the cell wall during the alkaline washing stage, thus creating more favorable conditions for the subsequent alkaline purification of dextran. NaHCO3, due to its weak alkalinity, cannot achieve this pre-purification function.

[0070] In summary, the dextran purity index demonstrates that fractional utilization and NaOH alkaline washing have a dual beneficial effect on the purity of dextran extraction. Fractional utilization ensures the purity of the cell wall residue source, while NaOH alkaline washing achieves pre-purification while debittering. The synergy of these two methods increases the purity of dextran from 60% to 87.2%.

[0071] (4) Comparison of Comparative Example 3 and Example 1: Example 1 used NaOH alkaline washing (pH 9.5), and the bitterness value was ≤2BU, which met the strict standards of the beer industry for debittered products; while Comparative Example 3 used conventional NaHCO3 for debittering, and the bitterness value was still as high as 15BU, indicating that NaHCO3 cannot completely remove the bitter substances of hops.

[0072] The correlation between bitterness value and dextran purity: NaOH simultaneously achieved debittering (bitterness value ≤ 2 BU) and cell wall loosening (dextran purity 87.2%) at pH 9.5, while NaHCO3 treatment resulted in incomplete debittering (bitterness value 15 BU) and lower dextran purity (82%). This data demonstrates that NaOH achieves a triple function of debittering, cell wall loosening, and dextran purification and pre-enhancement at pH 9.5, while NaHCO3 only achieves a single debittering function, and its effect is far inferior to that of NaOH.

[0073] In summary, the bitterness value index proves that the debittering effect of NaOH alkaline washing (≤2BU) is significantly better than that of NaHCO3 (15BU). NaOH achieves a synergistic effect of simultaneously debittering, loosening cell walls, and purifying and pre-gaining in the same process, which is something that NaHCO3 cannot achieve.

[0074] Therefore, the present invention adopts the above-mentioned clean production method for co-producing brewer's yeast powder and extract. By classifying and utilizing waste yeast sludge in a specific ratio, high-digestibility enzymatically hydrolyzed cell wall-broken brewer's yeast dry powder is prepared by dual-enzyme synergistic cell wall breaking, and high-quality pure yeast extract is prepared by endogenous enzymatic hydrolysis after simultaneous thorough debittering and cell wall loosening by sodium hydroxide alkaline washing. This realizes differentiated processing of raw materials and diversified output of products.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A clean production method for the co-production of brewer's yeast powder and extract, characterized in that: Includes the following steps: S1. Raw material pretreatment: The beer yeast mud produced during beer brewing is sieved and washed to obtain purified yeast mud; S2. Divide the purified yeast mud into a first slurry and a second slurry, and make the first slurry and the second slurry into a first suspension and a second suspension, respectively. S3. Add flavor promoter, β-mannanase and 5'-phosphodiesterase to the first suspension, break the cell wall and inactivate the enzyme to obtain a cell wall broken slurry, and spray dry the cell wall broken slurry to obtain enzymatically hydrolyzed cell wall broken brewer yeast dry powder. S4. Add sodium hydroxide to the second suspension, stir to wash away bitterness with alkali and loosen the cell wall at the same time, then add hydrochloric acid to neutralize, use endogenous enzyme autolysis to perform enzymatic hydrolysis, then inactivate the enzyme, centrifuge to separate the supernatant and precipitate, take the supernatant and vacuum concentrate or vacuum concentrate and spray dry to obtain pure yeast extract, and keep the precipitate for later use. S5. Add the precipitate obtained in S4 to sodium hydroxide solution for alkaline treatment. After treatment, centrifuge to collect the insoluble matter. Wash the insoluble matter until neutral and then vacuum dry to obtain β-1,3-glucan. S6. Collect the washing wastewater and concentrated condensate generated in S3 and S4, and treat them through an ultrafiltration and nanofiltration series system to obtain permeate. The permeate is recycled in S2, and the concentrated liquid is spray-dried to obtain protein feed additive. S7 collects the exhaust gas from spray drying and the secondary steam from vacuum concentration, and transfers the heat to the circulating hot water through a plate heat exchanger, which is used for S3 and S4 respectively.

2. The clean production method for co-producing brewer's yeast powder and extract according to claim 1, characterized in that: In S2, the first slurry accounts for 60-80% of the total mass of the purified yeast slurry, the second slurry accounts for 20-40% of the total mass of the purified yeast slurry, the concentration of the first suspension is 5-20wt%, and the concentration of the second suspension is 10-20wt%.

3. The clean production method for co-producing brewer's yeast powder and extract according to claim 1, characterized in that: In S3, the flavor enhancer is a mixture of Na2CO3 and NaCl in a mass ratio of 1:2 to 1:5, and its total mass percentage concentration in the slurry is 1.0 to 5.0%.

4. The clean production method for co-producing brewer's yeast powder and extract according to claim 1, characterized in that: In S3, the cell wall breaking temperature is 45-65℃, the cell wall breaking time is 6-16h, the enzyme inactivation temperature is 75-90℃, and the enzyme inactivation time is 0.5-1.5h.

5. A clean production method for co-producing brewer's yeast powder and extract according to claim 1, characterized in that: In S3, the amount of β-mannanase added is 0.3-1.0% of the mass of the first suspension, and the amount of 5'-phosphodiesterase added is 0.1%-0.5% of the mass of the first suspension.

6. The clean production method for co-producing brewer's yeast powder and extract according to claim 1, characterized in that: In S4, sodium hydroxide is added to adjust the pH to 9-10, with a sodium hydroxide concentration of 1-5 mol / L. Hydrochloric acid is added to adjust the pH to 5.5-6.

5.

7. The clean production method for co-producing brewer's yeast powder and extract according to claim 1, characterized in that: In S4, the autolysis temperature is 50-55℃, the autolysis time is 18-30h, the enzyme inactivation temperature is 80-85℃, and the enzyme inactivation time is 20-40min.

8. A clean production method for co-producing brewer's yeast powder and extract according to claim 1, characterized in that: In S4, a disc centrifuge is used for centrifugation at a speed of 5000-8000 rpm and a feed rate of 500-1000 L / h. The resulting pure yeast extract is in the form of paste or powder.

9. A clean production method for co-producing brewer's yeast powder and extract according to claim 1, characterized in that: In S5, the specific conditions for alkaline treatment with sodium hydroxide solution are as follows: add 2-4 times the weight of 1-5wt% NaOH solution and treat at 70-85℃ for 2-3 hours.

10. A clean production method for co-producing brewer's yeast powder and extract according to claim 1, characterized in that: In S6, the ultrafiltration membrane used has a molecular weight cutoff of 3000-10000 Da, and the nanofiltration membrane used has a molecular weight cutoff of 200-500 Da. The operating pressure is 1-2.5 MPa, and the series system is cleaned by CIP every 8-12 hours.

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