Saccharomyces cerevisiae and production method of saccharomyces cerevisiae culture

Abstract

The invention relates to the technical field of yeast culture preparation, in particular to saccharomyces cerevisiae and a saccharomyces cerevisiae culture production method. The saccharomyces cerevisiae is Saccharomyces cerevisiae and is preserved in the China General Microbiological Culture Collection Center (CGMCC), the strain number is WJ13, and the registration number is CGMCC No.31754. The production method of the saccharomyces cerevisiae culture comprises the following steps: grafting tyrosine and chitosan; preparing composite gel; and adding the composite gel into a culture solution, and culturing to obtain the saccharomyces cerevisiae culture. Tyrosine and chitosan are grafted, after the tyrosine is grafted to the chitosan, the tyrosine grafting can increase the intermolecular crosslinking of the chitosan so as to improve the mechanical strength and stability of the gel scaffold, and the tyrosine grafting can increase the hydrophobicity and affinity of the surface of the chitosan, so that the adhesion and proliferation of the saccharomyces cerevisiae are facilitated; therefore, the content of nutritional ingredients such as small-molecular protein and organic acid in the culture is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of yeast culture preparation, and in particular to brewer's yeast and a brewer's yeast culture production method. Background Art

[0002] Saccharomyces cerevisiae is a single-celled fungus belonging to the genus Saccharomyces that can grow under both aerobic and anaerobic conditions. Under aerobic conditions, it primarily respires, completely oxidizing sugars into carbon dioxide and water. Under anaerobic conditions, it ferments, converting sugars into ethanol and carbon dioxide. Saccharomyces cerevisiae is a microbial organism widely used in the food and beverage industry, particularly in brewing, breadmaking, and the production of fermented foods. A Saccharomyces cerevisiae culture refers to a mixture of Saccharomyces cerevisiae cells and their metabolites cultivated in a specific culture medium. The composition and properties of the culture depend on culture conditions such as medium composition, temperature, pH, aeration rate, and incubation time. Saccharomyces cerevisiae cultures contain a large number of Saccharomyces cerevisiae cells, which are one of the main components of the culture, as well as Saccharomyces cerevisiae metabolites, including ethanol, protein, carbon dioxide, organic acids, amino acids, vitamins, and polysaccharides. Rich in protein, vitamins, and minerals, Saccharomyces cerevisiae cultures are high-quality protein supplements widely used in brewing, animal feed, and seasoning.

[0003] There are two main methods for culturing Saccharomyces cerevisiae culture: solid fermentation and liquid fermentation. Solid fermentation refers to a fermentation process that uses natural substrates as carbon and nitrogen sources, or uses inert substrates as solid supports, and the system has no or nearly no flowing water. Liquid fermentation is a fermentation process in which Saccharomyces cerevisiae is inoculated into a liquid culture medium for fermentation. This method is widely used in industrial production and has high production efficiency and controllability. Solid fermentation has the characteristics of water and energy saving, but the cycle is long, the overall engineering technology is relatively backward, and the degree of automation is low. Therefore, it is rarely used in industry. Liquid fermentation has a shorter cycle and is more suitable for large-scale production. In addition, the fermentation process can be optimized by precisely controlling conditions such as temperature. However, a variety of metabolites are produced during liquid fermentation. Although these metabolites are non-toxic, a large amount of metabolites will squeeze out the proportion of nutrients in the Saccharomyces cerevisiae culture, thereby reducing the proportion of nutrients in the Saccharomyces cerevisiae culture, reducing the nutritional value of the Saccharomyces cerevisiae culture, and thus reducing the economic value of the Saccharomyces cerevisiae culture. Therefore, the present invention provides a Saccharomyces cerevisiae and a method for producing a Saccharomyces cerevisiae culture, which promotes the growth and development of Saccharomyces cerevisiae by adding a composite gel, thereby increasing the proportion of nutrients in the Saccharomyces cerevisiae culture and improving the nutritional and economic value. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the present invention aims to provide a brewer's yeast and a method for producing a brewer's yeast culture.

[0005] A method for producing a saccharomyces cerevisiae culture comprises the following steps: S1: Grafting of tyrosine and chitosan Chitosan is added to a glacial acetic acid solution and stirred to form a chitosan solution, tyrosine is added to an ethanol solution and added to the chitosan solution, stirred, allowed to stand for reaction, and dialyzed to obtain tyrosine-grafted chitosan; S2: Preparation of composite gel Kaolin is crushed and sieved, and added to a sulfuric acid solution, followed by a citric acid solution. After the reaction, the modified kaolin is dried to obtain modified kaolin. Xanthan gum, modified kaolin, and tyrosine-grafted chitosan are dissolved in ultrapure water, cross-linked after the reaction, and then taken out to obtain a composite gel. S3: Add the composite gel to the culture medium to obtain a culture of Saccharomyces cerevisiae The purified brewer's yeast is inoculated into a YPD medium, a composite gel is added into the YPD medium, and the medium is placed in a constant temperature incubator for culture, and is inoculated into a solid fermentation substrate for fermentation, and finally naturally air-dried and crushed to obtain a brewer's yeast culture.

[0006] Among them, the brewer's yeast is Saccharomyces cerevisiae, which was deposited in the General Microbiology Center of China Culture Collection Administration on August 27, 2024. The strain number is WJ13 and the registration number is CGMCC No. 31754.

[0007] Furthermore, step S1 of grafting tyrosine and chitosan comprises the following steps: 1-2 parts by mass of chitosan are added to 45-50 parts by mass of a 2% glacial acetic acid solution, stirred for 10-15 minutes to form a chitosan solution, and then 1-2 parts by mass of tyrosine are added to 45-50 parts by mass of a 60wt% ethanol solution, and added to the chitosan solution, the pH is adjusted to 4-5, stirred for 10-15 minutes, and then allowed to react in a dark environment for 10-11 hours. The product is placed in a dialysis bag and dialyzed in ultrapure water with a pH of 5.5-6 for 24-25 hours, and then dialyzed in ultrapure water with a pH of 7-7.5 for 4-4.5 hours. Finally, it is freeze-dried at -20°C for 12-13 hours to obtain tyrosine-grafted chitosan.

[0008] Furthermore, step S2 of preparing the composite gel comprises the following steps: 10-15 parts by mass of kaolin are put into a high-speed universal grinder and crushed for 1-2 seconds, and sieved through a 200-mesh screen, and added to 15-20 parts by mass of sulfuric acid solution, and then 6-10 parts by mass of citric acid solution are added, and stirred at a speed of 100-120r / min for 20-25min, sealed and allowed to react for 4-5h, and then placed in a high-temperature oven at 95-100℃ for 2-2.5h, and then dried in an oven at 105-110℃ for 12-13h to obtain modified kaolin; the mass fraction 2% xanthan gum, 9% modified kaolin and 3% tyrosine grafted chitosan are dissolved in 20 parts by mass of ultrapure water, magnetically stirred for 20-30 minutes, and then reacted at 40-45°C and 0.1-0.5MPa for 1-2 hours. The product is then immersed in a calcium chloride aqueous solution for cross-linking for 1-1.5 hours, then taken out and freeze-dried at -20°C for 3-4 hours, crushed and immersed in a mixed buffer solution for cross-linking for 20-24 hours. The material-liquid ratio is 1: (8-10) g / mL, and a composite gel is obtained.

[0009] Furthermore, step S3 adds the composite gel to the culture solution for cultivation to obtain a culture of Saccharomyces cerevisiae, comprising the following steps: The purified brewer's yeast was inoculated into a YPD medium, and the composite gel was added to the YPD medium in an amount of 30-40 wt%, and the medium was placed in a constant temperature incubator at 25-30° C. for 12-13 hours, adjusted to 2×10 cfu / mL, and inoculated into a solid fermentation substrate at an addition amount of 1-3 wt% for fermentation. After sealing, the medium was shaken and fermented in an environment of 28-30° C. and 200 r / min for 44-48 hours. Finally, the medium was naturally air-dried and crushed to obtain a brewer's yeast culture.

[0010] Furthermore, the cut-off value of the dialysis bag is 3500Da.

[0011] Furthermore, the concentration of the calcium chloride aqueous solution is 20-25 wt %.

[0012] Furthermore, the concentration of the sulfuric acid solution is 25-30 wt %.

[0013] Furthermore, the mixed buffer solution is prepared by uniformly mixing EDC, NHS and MES in a volume ratio of 1:(1-2):(1-3).

[0014] Compared with the prior art, the present invention has at least the following beneficial effects: 1. The present invention grafts tyrosine onto chitosan. After tyrosine is grafted onto chitosan, the tyrosine grafting increases the intermolecular crosslinking of chitosan, thereby improving the mechanical strength and stability of the gel scaffold. The phenolic hydroxyl groups of tyrosine can react with the amino groups on chitosan, not only strengthening the crosslinking between chitosan molecules but also improving its chemical stability. Simultaneously, after tyrosine grafting, the crosslinking density between chitosan molecules increases, forming a tighter network structure. This structure can effectively disperse external forces and improve the mechanical strength of the material. The crosslinked chitosan is more stable in water and is less susceptible to dissolution or degradation. This allows the composite gel with tyrosine-grafted chitosan to maintain a stable structure in the culture medium environment, extending its service life. Furthermore, tyrosine grafting increases the hydrophobicity and affinity of the chitosan surface, which facilitates the adhesion and proliferation of Saccharomyces cerevisiae. Tyrosine-grafted chitosan can also mimic certain components of the extracellular matrix, providing a better growth environment for Saccharomyces cerevisiae, thereby increasing the content of nutrients such as small molecule proteins and organic acids in the culture.

[0015] 2. The present invention modifies kaolin with sulfuric acid and citric acid. The kaolin modified with the composite acid of sulfuric acid and citric acid has good flocculation properties. The composite acid modification of sulfuric acid and citric acid can change the charge distribution on the surface of the kaolin. Sulfuric acid, as a strong acid, can dissolve some metal oxides on the surface of the kaolin, releasing metal ions and making the kaolin surface charged. Citric acid, as a weak acid, can form complexes with these metal ions and further regulate the surface charge, so that the prepared composite gel can promote the aggregation and sedimentation of brewer's yeast cells. This not only helps to improve fermentation efficiency and enable yeast cells to better contact the substrate during the fermentation process, but also facilitates subsequent separation operations and reduces production costs. Cell aggregation can increase local cell concentration, promote synergy between yeast cells, and improve fermentation efficiency and nutrient content. In addition, the improvement in sedimentation performance is also conducive to the recovery and reuse of yeast cells after fermentation.

[0016] 3. The present invention prepares a composite gel by using xanthan gum, modified kaolin and tyrosine grafted chitosan, and adds the composite gel to a culture medium to culture brewer's yeast. The modified kaolin has good adsorption properties, can adsorb xanthan gum and tyrosine grafted chitosan and provide good flocculation ability. The rheological properties of the modified kaolin loaded with xanthan gum and tyrosine grafted chitosan are also affected by the xanthan gum and tyrosine grafted chitosan and improved, thereby improving the viscosity and stability of the culture medium. In addition, the presence of the modified kaolin also ensures the mechanical strength and stability of the composite gel, so that it can better maintain its structure during the fermentation process, improve the adhesion of brewer's yeast on the composite gel, better form colonies, thereby increasing the number of brewer's yeast in the culture medium, and thus increasing the content of nutrients in the culture. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings, which are incorporated herein and constitute a part of the specification, illustrate embodiments of the present disclosure and, together with the description, further serve to explain the principles of the present disclosure and to enable one skilled in the relevant art to make and use the present disclosure.

[0018] Figure 1 This is an electron microscope image of the composite gel prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0019] The following describes in detail a brewer's yeast and a method for producing a brewer's yeast culture provided by the present invention, with reference to the accompanying drawings and specific examples. It is also noted that, for the purpose of providing a more detailed description, the following examples are best and preferred embodiments, and those skilled in the art may employ alternative methods for implementing certain known techniques. Furthermore, the accompanying drawings are provided solely for the purpose of describing the embodiments in greater detail and are not intended to limit the present invention.

[0020] Example 1: A method for producing brewer's yeast and a brewer's yeast culture comprises the following steps: S1: Grafting of tyrosine and chitosan 1 part by mass of chitosan was added to 45 parts by mass of a 2% glacial acetic acid solution and stirred for 10 minutes to form a chitosan solution. Then, 1 part by mass of tyrosine was added to 45 parts by mass of a 60wt% ethanol solution and added to the chitosan solution. The pH was adjusted to 4 and stirred for 10 minutes. The reaction was then allowed to stand in a dark environment for 10 hours. The product was placed in a dialysis bag and dialyzed in ultrapure water with a pH of 5.5 for 24 hours. The cutoff value of the dialysis bag was 3500Da. The product was then dialyzed in ultrapure water with a pH of 7 for 4 hours. Finally, it was freeze-dried at -20°C for 12 hours to obtain tyrosine-grafted chitosan.

[0021] S2: Preparation of composite gel 10 parts by mass of kaolin were put into a high-speed universal grinder and crushed for 2s, sieved through a 200-mesh sieve, added to 15 parts by mass of a 25wt% sulfuric acid solution, and then added with 6 parts by mass of a citric acid solution. The mixture was stirred at a speed of 100 r / min for 20 minutes, sealed and allowed to react for 4 hours, and then placed in a high-temperature oven at 95°C for 2 hours and dried in an oven at 105°C for 12 hours to obtain modified kaolin. 2% by mass of xanthan gum, 9% by mass of modified kaolin and 3% by mass of tyrosine-grafted chitosan were added. The product was dissolved in 20 parts by mass of ultrapure water, magnetically stirred for 20 minutes, and then reacted at 40°C and 0.1 MPa for 1 hour. The product was then immersed in a 20wt% calcium chloride aqueous solution for cross-linking for 1 hour. It was then taken out and freeze-dried at -20°C for 3 hours. After crushing, it was immersed in a mixed buffer solution for cross-linking for 20 hours. The mixed buffer solution was prepared by mixing EDC, NHS and MES in a volume ratio of 1:1:1. The solid-liquid ratio was 1:8 g / mL, and then freeze-dried to obtain a composite gel. The electron microscope image is shown as follows: Figure 1 shown.

[0022] S3: Add the composite gel to the culture medium to obtain a culture of Saccharomyces cerevisiae The purified Saccharomyces cerevisiae was inoculated into YPD medium, and the composite gel was added to the YPD medium in an amount of 30 wt %, and the medium was cultured in a constant temperature incubator at 25°C for 12 h, adjusted to 2 × 10 cfu / mL, and inoculated into a solid fermentation substrate at an addition amount of 1 wt % for fermentation. After sealing, the medium was shaken and fermented at 28°C and 200 r / min for 48 h, and finally naturally air-dried and crushed to obtain a Saccharomyces cerevisiae culture.

[0023] Among them, the brewer's yeast is Saccharomyces cerevisiae, which was deposited in the General Microbiology Center of China Culture Collection Administration on August 27, 2024. The strain number is WJ13 and the registration number is CGMCC No. 31754.

[0024] Example 2: A method for producing a saccharomyces cerevisiae and a saccharomyces cerevisiae culture, such as Figure 1 As shown, the following steps are included: S1: Grafting of tyrosine and chitosan 2 parts by mass of chitosan were added to 50 parts by mass of a 2% glacial acetic acid solution and stirred for 10 minutes to form a chitosan solution. Then, 2 parts by mass of tyrosine were added to 50 parts by mass of a 60wt% ethanol solution and added to the chitosan solution. The pH was adjusted to 4 and stirred for 10 minutes. The reaction was then allowed to stand in a dark environment for 10 hours. The product was placed in a dialysis bag and dialyzed in ultrapure water with a pH of 5.5 for 24 hours. The cutoff value of the dialysis bag was 3500Da. The product was then dialyzed in ultrapure water with a pH of 7 for 4 hours. Finally, it was freeze-dried at -20°C for 12 hours to obtain tyrosine-grafted chitosan.

[0025] S2: Preparation of composite gel 15 parts by mass of kaolin were put into a high-speed universal grinder and crushed for 2s, sieved through a 200-mesh sieve, added to 20 parts by mass of a 25wt% sulfuric acid solution, and then added with 10 parts by mass of a citric acid solution. The mixture was stirred at a speed of 100 r / min for 20 minutes, sealed and allowed to react for 4 hours, and then placed in a high-temperature oven at 95°C for 2 hours and dried in an oven at 105°C for 12 hours to obtain modified kaolin. 2% by mass of xanthan gum, 9% by mass of modified kaolin and 3% by mass of tyrosine grafted shell were added. The polysaccharide was dissolved in 20 parts by mass of ultrapure water, magnetically stirred for 20 minutes, and then reacted at 40°C and 0.1 MPa for 1 hour. The product was then immersed in a 20wt% calcium chloride aqueous solution for cross-linking for 1 hour, then taken out and freeze-dried at -20°C for 3 hours. After crushing, it was immersed in a mixed buffer for cross-linking for 20 hours. The mixed buffer was prepared by uniformly mixing EDC, NHS and MES in a volume ratio of 1:1:1, with a solid-liquid ratio of 1:10 g / mL, and then freeze-dried to obtain a composite gel.

[0026] S3: Add the composite gel to the culture medium to obtain a culture of Saccharomyces cerevisiae The purified Saccharomyces cerevisiae was inoculated into YPD medium, and the composite gel was added to the YPD medium in an amount of 40 wt %, and cultured in a constant temperature incubator at 25°C for 12 h, adjusted to 2 × 10 cfu / mL, and inoculated into a solid fermentation substrate at an addition amount of 1 wt % for fermentation. After sealing, the culture was shaken and fermented at 28°C and 200 r / min for 48 h, and finally naturally air-dried and crushed to obtain a Saccharomyces cerevisiae culture.

[0027] Among them, the brewer's yeast is Saccharomyces cerevisiae, which was deposited in the General Microbiology Center of China Culture Collection Administration on August 27, 2024. The strain number is WJ13 and the registration number is CGMCC No. 31754.

[0028] Example 3: A method for producing a saccharomyces cerevisiae and a saccharomyces cerevisiae culture, such as Figure 1 As shown, the following steps are included: S1: Grafting of tyrosine and chitosan 1 part by mass of chitosan was added to 45 parts by mass of a 2% glacial acetic acid solution and stirred for 15 minutes to form a chitosan solution. Then, 1 part by mass of tyrosine was added to 45 parts by mass of a 60wt% ethanol solution and added to the chitosan solution. The pH was adjusted to 5 and stirred for 15 minutes. The reaction was then allowed to stand in a dark environment for 11 hours. The product was placed in a dialysis bag and dialyzed in ultrapure water with a pH of 6 for 25 hours. The cutoff value of the dialysis bag was 3500Da. The product was then dialyzed in ultrapure water with a pH of 7.5 for 4.5 hours. Finally, it was freeze-dried at -20°C for 13 hours to obtain tyrosine-grafted chitosan.

[0029] S2: Preparation of composite gel 10 parts by mass of kaolin were put into a high-speed universal grinder and crushed for 2s, sieved through a 200-mesh sieve, added to 15 parts by mass of a 25wt% sulfuric acid solution, and then added with 6 parts by mass of a citric acid solution. The mixture was stirred at a speed of 120r / min for 25min, sealed and allowed to react for 5h, and then placed in a high-temperature oven at 100℃ for 2.5h and dried in a 110℃ oven for 13h to obtain modified kaolin. 2% by mass of xanthan gum, 9% of modified kaolin and 3% of tyrosine were grafted. Chitosan was dissolved in 20 parts by mass of ultrapure water, magnetically stirred for 20 minutes, and then reacted at 45°C and 0.5 MPa for 2 hours. The product was then immersed in a 20wt% calcium chloride aqueous solution for cross-linking for 1.5 hours, then taken out and freeze-dried at -20°C for 4 hours. After crushing, it was immersed in a mixed buffer solution for cross-linking for 24 hours. The mixed buffer solution was prepared by uniformly mixing EDC, NHS and MES in a volume ratio of 1:1:1, with a solid-liquid ratio of 1:8 g / mL, and then freeze-dried to obtain a composite gel.

[0030] S3: Add the composite gel to the culture medium to obtain a culture of Saccharomyces cerevisiae The purified Saccharomyces cerevisiae was inoculated into YPD medium, and the composite gel was added to the YPD medium in an amount of 30 wt %, and cultured in a constant temperature incubator at 28°C for 13 h, adjusted to 2 × 10 cfu / mL, and inoculated into a solid fermentation substrate at an addition amount of 1 wt % for fermentation. After sealing, the culture was shaken and fermented at 28°C and 200 r / min for 44 h, and finally naturally air-dried and crushed to obtain a Saccharomyces cerevisiae culture.

[0031] Among them, the brewer's yeast is Saccharomyces cerevisiae, which was deposited in the General Microbiology Center of China Culture Collection Administration on August 27, 2024. The strain number is WJ13 and the registration number is CGMCC No. 31754.

[0032] Comparative Example 1: Compared with Example 1, the difference of Comparative Example 1 is that step S1 is not performed, and in step S2, tyrosine-grafted chitosan is replaced with chitosan, specifically "S2: preparing composite gel 10 parts by mass of kaolin were put into a high-speed universal grinder and crushed for 2s, sieved through a 200-mesh sieve, added to 15 parts by mass of a 25wt% sulfuric acid solution, and then added with 6 parts by mass of a citric acid solution. The mixture was stirred at a speed of 100 r / min for 20 minutes, sealed and allowed to react for 4 hours, and then placed in a high-temperature oven at 95°C for 2 hours and dried in an oven at 105°C for 12 hours to obtain modified kaolin. 2% by mass of xanthan gum, 9% of modified kaolin and 3% of chitosan were dissolved in 20 parts by mass of ultrapure water and magnetically mixed. The mixture was stirred vigorously for 20 minutes, and then reacted at 40°C and 0.1 MPa for 1 hour. The product was then immersed in a 20wt% calcium chloride aqueous solution for cross-linking for 1 hour. The product was then taken out and freeze-dried at -20°C for 3 hours. After crushing, it was immersed in a mixed buffer for cross-linking for 20 hours. The mixed buffer was prepared by uniformly mixing EDC, NHS and MES in a volume ratio of 1:1:1, with a solid-liquid ratio of 1:8 g / mL, and then freeze-dried to obtain a composite gel. The other steps remained unchanged, and the prepared Saccharomyces cerevisiae culture was recorded as Comparative Example 1.

[0033] Comparative Example 2: Compared with Example 1, the difference of Comparative Example 2 is that in step S2, kaolin is not treated but directly reacted with xanthan gum and tyrosine-grafted chitosan, specifically "S2: Preparation of composite gel 2% xanthan gum, 9% kaolin, and 3% tyrosine-grafted chitosan were dissolved in 20 parts by mass of ultrapure water, magnetically stirred for 20 minutes, and reacted at 40°C and 0.1 MPa for 1 hour. The product was then immersed in a 20wt% calcium chloride aqueous solution for crosslinking for 1 hour, then taken out and freeze-dried at -20°C for 3 hours, crushed, and then immersed in a mixed buffer for crosslinking for 20 hours. The mixed buffer was prepared by uniformly mixing EDC, NHS, and MES in a volume ratio of 1:1:1, with a solid-liquid ratio of 1:8 g / mL, and then freeze-dried to obtain a composite gel. The remaining steps remained unchanged, and the prepared Saccharomyces cerevisiae culture was recorded as Comparative Example 2.

[0034] Comparative Example 3: Compared with Example 1, the difference of Comparative Example 3 is that tyrosine chitosan is not added in step S2, specifically "S2: Preparation of composite gel 10 parts by mass of kaolin were put into a high-speed universal grinder and crushed for 2s, sieved through a 200-mesh sieve, added to 15 parts by mass of a 25wt% sulfuric acid solution, and then added with 6 parts by mass of a citric acid solution. The mixture was stirred at a speed of 100 r / min for 20 minutes, sealed and allowed to react for 4 hours, and then placed in a high-temperature oven at 95°C for 2 hours and dried in an oven at 105°C for 12 hours to obtain modified kaolin. 2% by mass of xanthan gum and 9% by mass of modified kaolin were dissolved in 20 parts by mass of ultrapure water and magnetically stirred for 2 hours. The reaction mixture was stirred for 0 min, and then reacted at 40°C and 0.1 MPa for 1 h. The product was then immersed in a 20 wt% calcium chloride aqueous solution for cross-linking for 1 h. The product was then taken out and freeze-dried at -20°C for 3 h. After being crushed, it was immersed in a mixed buffer for cross-linking for 20 h. The mixed buffer was prepared by uniformly mixing EDC, NHS and MES in a volume ratio of 1:1:1, with a material-liquid ratio of 1:8 g / mL. The composite gel was obtained by freeze-drying. The other steps remained unchanged, and the prepared Saccharomyces cerevisiae culture was recorded as Comparative Example 3.

[0035] Comparative Example 4: Compared with Example 1, the difference of Comparative Example 4 is that no xanthan gum is added in step S2, specifically "S2: preparing composite gel 10 parts by mass of kaolin were put into a high-speed universal grinder and crushed for 2s, sieved through a 200-mesh sieve, added to 15 parts by mass of a 25wt% sulfuric acid solution, and then added with 6 parts by mass of a citric acid solution. The mixture was stirred at a speed of 100 r / min for 20 minutes, sealed and allowed to react for 4 hours, and then placed in a high-temperature oven at 95°C for 2 hours and dried in an oven at 105°C for 12 hours to obtain modified kaolin. 9% by mass of modified kaolin and 3% by mass of tyrosine-grafted chitosan were dissolved in 20 parts by mass of ultrapure water and magnetically stirred. The mixture was stirred for 20 minutes, and then reacted at 40°C and 0.1 MPa for 1 hour. The product was then immersed in a 20wt% calcium chloride aqueous solution for cross-linking for 1 hour. The product was then taken out and freeze-dried at -20°C for 3 hours. After crushing, it was immersed in a mixed buffer for cross-linking for 20 hours. The mixed buffer was prepared by uniformly mixing EDC, NHS and MES in a volume ratio of 1:1:1, with a material-liquid ratio of 1:8 g / mL, and then freeze-dried to obtain a composite gel. The other steps remained unchanged, and the prepared Saccharomyces cerevisiae culture was recorded as Comparative Example 4.

[0036] The brewer's yeast used in the comparative example is Saccharomyces cerevisiae, which was deposited in the General Microbiology Center of China Culture Collection Administration on August 27, 2024, with strain number WJ13 and registration number CGMCC No.31754.

[0037] The nutritional components of Examples 1-4 and Comparative Examples 1-4 were tested, and the proportions of some of the nutritional components are shown in Table 1.

[0038] The proportion of small molecule protein content in the crude protein of Examples 1-4 and Comparative Examples 1-4 was detected and calculated, as shown in Table 2.

[0039] Table 1

[0040] Table 2

[0041] As can be seen from Table 1, the crude protein, ash, and organic acid contents of Examples 1-4 are all higher than those of the comparative example. Crude protein refers to the sum of all nitrogenous compounds in the sample, including true protein and non-protein nitrogenous compounds; ash refers to the total amount of inorganic matter remaining after the organic matter in the sample is completely burned at a certain temperature. The ash content can reflect the content of minerals and inorganic salts in the saccharomyces cerevisiae culture. A higher ash content generally means that the culture contains more minerals, such as calcium, phosphorus, potassium, etc.; the organic acid content refers to the various organic acids produced by saccharomyces cerevisiae during the fermentation process, such as lactic acid, acetic acid, succinic acid, and citric acid. These content indicators can be used to determine the amount of nutrients in the saccharomyces cerevisiae culture. It can be seen that after the composite gel prepared by the raw material combination of the present invention is added to the culture medium, the nutrient content of the saccharomyces cerevisiae culture is higher and has a higher nutritional value.

[0042] It can be seen from Table 2 that the proportion of small molecule proteins in crude protein is greater in the examples than in the comparative examples. Small molecule proteins refer to complete proteins with a smaller molecular weight, which are usually composed of more than 20 amino acids, but have a relatively small molecular weight. They are still complete proteins with specific three-dimensional structures and functions. Small molecule proteins have higher biological activity and rapid absorption and utilization capabilities, and a higher proportion means that brewer's yeast culture is easier to absorb and has a better nutritional supplement effect.

[0043] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A method for producing a saccharomyces cerevisiae culture, characterized in that: The steps include: S1: Tyrosine grafted onto chitosan Chitosan is added to a glacial acetic acid solution and stirred to form a chitosan solution, tyrosine is added to an ethanol solution and added to the chitosan solution, stirred, allowed to stand for reaction, and dialyzed to obtain tyrosine-grafted chitosan; S2: Preparation of composite gel Kaolin is crushed and sieved, and added to a sulfuric acid solution, followed by a citric acid solution. After the reaction, the modified kaolin is dried to obtain modified kaolin. Xanthan gum, modified kaolin, and tyrosine-grafted chitosan are dissolved in ultrapure water, cross-linked after the reaction, and then taken out to obtain a composite gel. S3: Add the composite gel to the culture medium to obtain a culture of Saccharomyces cerevisiae The purified yeast was inoculated into YPD medium, composite gel was added into the YPD medium, and the culture was placed in a constant temperature incubator, and then inoculated into a solid fermentation substrate for fermentation, and finally naturally dried and crushed to obtain a yeast culture. Among them, the brewer's yeast is Saccharomyces cerevisiae, which is preserved in the General Microbiology Center of China Culture Collection Administration of Microorganisms, with strain number WJ13 and registration number CGMCC No.31754.

2. The method for producing a saccharomyces cerevisiae culture according to claim 1, wherein: Step S1: grafting tyrosine onto chitosan, comprising the following steps: 1-2 parts by mass of chitosan are added to 45-50 parts by mass of a 2% glacial acetic acid solution, stirred for 10-15 minutes to form a chitosan solution, and then 1-2 parts by mass of tyrosine are added to 45-50 parts by mass of a 60wt% ethanol solution, and added to the chitosan solution, the pH is adjusted to 4-5, stirred for 10-15 minutes, and then allowed to react in a dark environment for 10-11 hours. The product is placed in a dialysis bag and dialyzed in ultrapure water with a pH of 5.5-6 for 24-25 hours, and then dialyzed in ultrapure water with a pH of 7-7.5 for 4-4.5 hours. Finally, it is freeze-dried at -20°C for 12-13 hours to obtain tyrosine-grafted chitosan.

3. The method for producing a saccharomyces cerevisiae culture according to claim 2, wherein: Step S2 is to prepare a composite gel, comprising the following steps: 10-15 parts by mass of kaolin are put into a high-speed universal grinder and crushed for 1-2 seconds, and sieved through a 200-mesh screen, and added to 15-20 parts by mass of sulfuric acid solution, and then 6-10 parts by mass of citric acid solution are added, and stirred at a speed of 100-120r / min for 20-25min, sealed and allowed to react for 4-5h, and then placed in a high-temperature oven at 95-100℃ for 2-2.5h, and then dried in an oven at 105-110℃ for 12-13h to obtain modified kaolin; the mass fraction 2% xanthan gum, 9% modified kaolin and 3% tyrosine grafted chitosan are dissolved in 20 parts by mass of ultrapure water, magnetically stirred for 20-30 minutes, and then reacted at 40-45°C and 0.1-0.5MPa for 1-2 hours. The product is then immersed in a calcium chloride aqueous solution for cross-linking for 1-1.5 hours, then taken out and freeze-dried at -20°C for 3-4 hours, crushed and immersed in a mixed buffer solution for cross-linking for 20-24 hours. The material-liquid ratio is 1: (8-10) g / mL, and a composite gel is obtained.

4. The method for producing a saccharomyces cerevisiae culture according to claim 3, wherein: Step S3, adding the composite gel to the culture medium for cultivation to obtain a culture of Saccharomyces cerevisiae, comprises the following steps: The purified brewer's yeast was inoculated into a YPD medium, and the composite gel was added to the YPD medium in an amount of 30-40 wt%, and the medium was placed in a constant temperature incubator at 25-30° C. for 12-13 hours, adjusted to 2×10 cfu / mL, and inoculated into a solid fermentation substrate at an addition amount of 1-3 wt% for fermentation. After sealing, the medium was shaken and fermented in an environment of 28-30° C. and 200 r / min for 44-48 hours. Finally, the medium was naturally air-dried and crushed to obtain a brewer's yeast culture.

5. The method for producing a saccharomyces cerevisiae culture according to claim 2, wherein: The cut-off value of the dialysis bag is 3500Da.

6. The method for producing a saccharomyces cerevisiae culture according to claim 3, wherein: The concentration of the calcium chloride aqueous solution is 20-25wt%.

7. The method for producing a saccharomyces cerevisiae culture according to claim 3, wherein: The concentration of the sulfuric acid solution is 25-30wt%.

8. The method for producing a saccharomyces cerevisiae culture according to claim 3, wherein: The mixed buffer was prepared by uniformly mixing EDC, NHS, and MES in a volume ratio of 1:(1-2):(1-3).

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