Yeast, yeast powder, and their use in wheat flour food processing

Abstract

The present invention discloses a yeast, yeast powder, and its use in processing flour-based foods, wherein the yeast is CDLB-YE05 Kazachstania servazzii yeast, preserved at the Institute of Microbiology, Chinese Academy of Sciences, on July 17, 2023, with storage number CGMCC NO. 27948 and storage address at No. 3, Courtyard, No. 1, Beichen West Road, Chaoyang District, Beijing. The CDLB-YE05 Kazachstania servazzii yeast provided by the present invention is used to prepare yeast powder, which is then used in processing flour-based foods to increase the polysaccharide compounds produced by the yeast's propagation metabolism in dough, thereby increasing the viscosity of the food, improving the chewiness of the flour-based foods, and enhancing the flavor and mouthfeel.

Description

Technical Field

[0001] The present invention relates to the technical field of microorganisms, and specifically to yeasts, yeast powders, and their use in the processing of wheat flour foods.

Background Art

[0002] Wheat flour foods are extremely popular foods among Chinese people. For thousands of years, our ancestors have handmade a large number of characteristic wheat flour foods with local flavors and tastes in various places. These wheat flour foods are toothsome and delicious, and some characteristic wheat flour foods in certain regions have already become local traditional delicacies. However, with the progress of industry, in modern society, it is very difficult to create the unique taste and flavor of traditional wheat flour foods in each place with equipment. The research results show that this is because there are differences in the yeast strains obtained by different regions and different people. When different yeast strains are inoculated into the dough, different metabolites such as carbon dioxide, organic acids, alcohols, alcohol compounds, sugar compounds, and ester compounds will be produced during the metabolism of fermented starch. These metabolites are what give the made wheat flour foods different flavors. The more sugar compounds there are, the higher the viscosity of the starch. The more lipid compounds there are, the more fragrant the noodles become and the richer the taste is. This is also the main reason for the toothsome and rich taste of the noodles. In contrast, there is no yeast fermentation process in the production of wheat flour foods by equipment, so it is impossible to create the unique taste of traditional wheat flour foods in each place.

[0003] Therefore, in order to improve the toothsome and fragrant taste of wheat flour foods, it is necessary to quickly provide new yeast strains that can produce sugar compounds and lipid compounds.

Summary of the Invention

[0004] The object of the present invention is to provide yeasts, yeast powders, and their use in the processing of wheat flour foods, which can solve the problem that various wheat flour foods made by conventional processes lack toothsome taste and have a bad taste.

[0005] To achieve the above objective, the first technical solution of the present invention is realized as the yeast CDLB-YE05 Kazachstania servazzii, which was stored at the Institute of Microbiology, Chinese Academy of Sciences on July 17, 2023, with storage number CGMCC NO.27948 and storage address No.3, Building 1, Beichen West Road, Chaoyang District, Beijing.

[0006] Furthermore, the nucleotide sequence of the yeast is as shown in SEQ No. 1.

[0007] The second technical solution of the present invention is obtained by mixing a yeast culture, skim milk powder, and sorbitan monostearate, then freeze-drying and polishing, wherein 60g to 80g of skim milk powder and 9g to 10g of sorbitan monostearate are added per 1kg of yeast culture. The aforementioned yeast culture is realized as a yeast powder prepared from the aforementioned yeast, which is cultured using the aforementioned yeast.

[0008] Furthermore, the yeast powder has a moisture content of 10% or less, a protein content of 4% or more, an ash content of 10% or less, and a yeast cell count of 10 7 It is CFU or higher.

[0009] Furthermore, the yeast culture is The yeast is activated for 16 to 48 hours, then inoculated into a mixed culture medium, mixed uniformly with water, and cultured for 20 to 72 hours under aerobic conditions at 15°C to 35°C to obtain the yeast.

[0010] Furthermore, the mixed culture medium is Weigh out 720 to 880 parts by mass of malt, 90 to 110 parts of soybeans, and 90 to 110 parts of glutinous rice. It is obtained by weighing each substance, baking them at 120°C for 2 hours, then grinding and mixing them.

[0011] A third technical solution of the present invention is realized as the use of the above-mentioned yeast powder in the processing of wheat flour food products.

[0012] Furthermore, as a specific method, In S1, weigh out the following in mass ratios: yeast powder 0.08-0.1, wheat flour 100-110, water 28-30, edible salt 0.1-0.15, and edible alkali 0.1-0.15. In step S2, weighed yeast powder, wheat flour, edible salt, edible alkali, and water are mixed to form a dough, and after fermenting the dough for 3 to 6 hours, a wheat flour food product is manufactured.

[0013] Furthermore, the wheat flour products include noodles, dumplings, wontons, and Chinese rice cakes.

[0014] Compared to the conventional technology, the beneficial effects of the present invention are as follows:

[0015] By preparing yeast powder using the yeast provided by the present invention and using the yeast powder in the processing of wheat flour products, the amount of polysaccharide compounds produced by the proliferation metabolism of the yeast in the wheat flour can be increased, thereby increasing the viscosity of the wheat flour products, improving the texture of the wheat flour products, and making them more palatable. [Brief explanation of the drawing]

[0016] [Figure 1] This shows the colony morphology of the yeast *Kazachstania servazzii* (CDLB-YE05) on potato dextrose agar. [Figure 2] This shows the colony morphology of the yeast *Kazachstania servazzii* (CDLB-YE05) on a wort culture medium. [Figure 3] This is a comparative diagram of the polysaccharide compound content produced by different yeast strains. [Figure 4] (a) Colony form of yeast powder, (b) Colony form of active dried yeast (high sugar type), (c) Colony form of active dried yeast (low sugar type), and (d) Colony form of wine-making yeast species. [Figure 5] This is the standard curve for glucose. [Figure 6] This is a comparison chart of the concentrations of polysaccharide compounds in the samples of each group in Example 4.

Mode for Carrying Out the Invention

[0017] In order to make the object, technical solution and advantages of the present invention more clear, specific examples will be combined below to explain the present invention in more detail. It should be understood that the specific examples described here are only for interpreting the present invention and are not intended to limit the present invention.

[0018] In the description of the present invention, it should be made clear that the orientation or positional relationship indicated by terms such as "vertical", "lateral", "longitudinal", "front", "rear", "left", "right", "upper", "lower", "horizontal", etc. is based on the drawings and is only for facilitating the description of the present invention, and it does not mean that the described device or element must have a specific orientation or position, so it should not be understood as limiting the present invention. In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "attach", "connect", "couple" should be understood in a broad sense. For example, they may be fixedly connected, removably connected, or integrally connected, directly connected, or indirectly connected through an intermediate medium. Those skilled in the art may understand the specific meaning of the above terms in the present invention according to specific situations.

[0019] Example 1 Yeast was isolated, purified, and the obtained yeast was identified.

[0020] 1) Source of sample: Lanzhou ramen dough Among all types of wheat flour foods, Lanzhou ramen is a local cuisine with unique local flavor. As it takes a long time to make by hand and the inoculation number and types of yeast species in the dough are numerous, it has a particularly good texture, as well as a unique taste and aroma.

[0021] 2) Medium: Potato dextrose agar medium (PDA), wort medium The specific components per liter of potato dextrose agar medium were 300.0g of potato (extracted from the leachate powder), 20.0g of glucose, 15.0g of agar, and 0.1g of chloramphenicol.

[0022] The specific components per liter of wort culture medium were 130.0 g of powdered malt extract and 0.1 g of chloramphenicol.

[0023] 3) Reagents and equipment used [Table 1]

[0024] 4) Isolation of a single bacterial strain Weigh 25g of Lanzhou ramen dough, add 225mL of sterile physiological saline to make a 1:10 homogeneous sample solution, and dilute it 10 times to make 10 6 As a homogeneous solution of the gradient sample, For each dilution, 1 mL of the homogeneous sample solution was drawn up and placed in two flat dishes. 20 mL of potato dextrose agar medium cooled to 46°C was weighed and poured into the flat dishes. After cooling and solidification, the mixture was incubated in a fungal incubator at 28°C for 5 days. Colony morphology was observed, and single colonies were selected. Streak culture of the selected single colonies was continuously performed on potato dextrose agar plates, and the morphology of the single colonies was observed until a different single strain was isolated.

[0025] 5) Screening for strains that do not produce gas Prepare 180 mL of wort medium, autoclav it at 115°C for 15 min, then cool it, dispense it into 18 15 mL sterile glass test tubes, remove the air from the Durham tubes, and set the Durham tubes in each test tube with the opening facing downwards. 4) Select a single strain obtained in step 4) and inoculate it into the wort medium in each test tube. Add a permeable filtration membrane to each test tube and seal it. Incubate with shaking at 30±1℃ and a rotation speed of 160 r / min for 72 hours. Observe the turbidity rate and gas production amount during strain growth, and select strains that showed a rapid turbidity rate and did not produce gas.

[0026] 6) Screening for strains that do not produce alcohol 5) The non-gas-producing strains screened in step 5) were diluted 10-fold each. 6 Prepare a homogeneous sample solution with a gradient. For each dilution, draw up 1 mL of the homogeneous sample solution and place it in two sterile flat dishes. Weigh 20 mL of potato dextrose agar medium cooled to 46°C and pour it into the flat dishes. After cooling and solidifying, incubate in a fungal incubator at 28°C for 5 days. Observe the colony morphology and select medium to large single colonies with smooth surfaces and aligned edges. The above medium to large single colonies were inoculated into wort medium and cultured with shaking at 30±1℃ and a rotation speed of 160 r / min for 72 hours to obtain a bacterial suspension. Draw up 1 mL of bacterial solution, add 1 mL of 0.1 mol / L potassium dichromate solution, shake, and observe the color change of the mixture. A strain that did not change color was selected, and the above screening steps were repeated until a yeast strain that did not produce gas or alcohol was selected.

[0027] When a yeast strain that does not produce gas or alcohol was inoculated into a wort medium along with a yeast strain that produces both gas and alcohol obtained through the above process, and the reproductive and metabolic processes were observed, it was found that the yeast strain that does not produce gas or alcohol made the wort medium more viscous and gave it a rose aroma.

[0028] 7) Purification of yeast strains that do not produce gas or alcohol, and genome sequencing. Prepare 100 mL of wort medium in an Erlenmeyer flask, autoclav it at 115°C for 15 min, and then prepare it for use. A yeast strain that does not produce gas or alcohol is suspended in a small amount of wort medium, the suspension is poured into the wort medium in an Erlenmeyer flask, sealed with a permeable filtration membrane, and cultured with shaking at 28±1℃ and a rotation speed of 120 r / min for 48 hours. The wort bacteria suspension was centrifuged, washed, and the resulting bacterial precipitate was rapidly frozen in liquid nitrogen. The sample was placed in a sample tube and sent to the Shenzhen Institute of Metrology and Quality Detection for species identification. It was identified as CDLB-YE05 Kazachstania servazzii yeast by 18sRNA, and the sample was sent to the Wuhan Genetic Sequencing Center of China for genome sequencing. The nucleotide sequence of CDLB-YE05 Kazachstania servazzii yeast is shown in SEQ No. 1 and Table 2.

[0029] [Table 2] JPEG0007854220000003.jpg116170

[0030] 8) Colony morphology of the yeast *Kazachstania servazzii* (CDLB-YE05) CDLB-YE05 Kazachstania servazzii yeast was inoculated onto potato dextrose agar plates and cultured at 28°C for 5 days. Colony morphology was observed, and as shown in Figure 1, the colonies of CDLB-YE05 Kazachstania servazzii yeast were milky white, round, with a smooth surface, opaque and non-reflective, and with evenly spaced edges.

[0031] CDLB-YE05 Kazachstania servazzii yeast was inoculated into wort medium and cultured at 30°C for 2 days. The CDLB-YE05 Kazachstania servazzii yeast cells were cloudy, lacked a pellicle and membrane, had an ester aroma, and were free of unpleasant odors. Microscopic observation of the cell morphology of CDLB-YE05 Kazachstania servazzii yeast revealed that the cells were ascoglobulin-like, as shown in Figure 2.

[0032] 9) Characteristics of the genome of the yeast *Kazachstania servazzii* (CDLB-YE05) The yeast *Kazachstania servazzii* (CDLB-YE05) has a single genome with a total genome sequence length of 13,468,544 bp, containing 5,415 genes. The GC content accounts for 34.25%, gene length accounts for 66.81% of the total genome length, there are a total of 6,260 exons (64.51% of the total genome length), there are a total of 5,415 CDS regions (64.51% of the total genome length), there are a total of 845 introns (2.31% of the total genome length), the total copy number of all types of non-coding RNA (ncRNA) is 1046 reads (0.8106% of the total genome length), and the total length of all types of repetitive sequences is 2,034,046 bp (15.1022% of the total genome length).

[0033] 10) CDLB-YE05 Preservation of Kazachstania servazzii yeast strain Under sterile conditions, single colonies of CDLB-YE05 Kazachstania servazzii yeast were picked using an inoculation loop, inoculated into 250 mL of sterile wort, and uniformly shaken. Afterward, the culture was expanded for 48 hours under constant temperature conditions of 28±1°C. Wort was then taken and examined under a microscope to observe the formation of ascoglobulins in the colony morphology and the distribution of the colonies. If the field of view was filled with ascoglobulin yeast, the expansion culture was successful; otherwise, the culture was continued until expansion was successful, and microscopic examination was performed every 2 hours.

[0034] Under sterile conditions, 250 mL of successfully cultured bacterial culture solution was mixed with 17.5 g of skim milk powder, then freeze-dried. The freeze-dried powder was collected, and the number of colonies of the CDLB-YE05 Kazachstania servazzii yeast was 10. 7 We detected that the levels were larger than CFU and established this as the storage standard.

[0035] The freeze-dried powder of CDLB-YE05 Kazachstania servazzii yeast was dispensed into 0.1g portions into cryopreservation tubes, placed in vacuum-sealed bags, labeled, and then stored at an ultra-low temperature of -80°C.

[0036] The yeast strain CDLB-Y E05Kazachstania servazzii was deposited in the Institute of Microbiology, Chinese Academy of Sciences on July 17, 2023, with deposit number CGMCC NO.27948 and deposit address No.3, Building 1, Beichen West Road, Chaoyang District, Beijing.

[0037] 11) Production status of polysaccharide compounds from the yeast *Kazachstania servazzii* (CDLB-YE05) CDLB-YE05 Kazachstania servazzii yeast was inoculated into wort medium along with four other yeast strains isolated from the dough that produced both gas and alcohol, and cultured for 24 hours. 10 mL of the wort ferment was then weighed out after fermentation at 0h, 4h, 8h, 12h, 16h, 20h, and 24h. The wort fermentation liquid was centrifuged at 3500 r / min for 30 minutes, the microbial cells were discarded, and 1.5 g of trichloroacetic acid was added to the resulting supernatant. After homogeneous suspension, it was left to stand at 4°C for 1 hour. The suspension was centrifuged at 11,000 r / min for 1 minute, the protein precipitate was discarded, and the resulting supernatant was transferred to a dialysis bag approximately 15 cm long. The dialysis bag was then placed in a beaker of distilled water, and after 1 hour of dialysis at 4°C, the extracorporeal dialysate was replaced. Dialysis continued for another 2 hours, the extracorporeal dialysate was replaced again, and dialysis continued for another 3 hours.

[0038] After dialysis was completed, the extracorporeal dialysate was discarded, the solution in the dialysis bag was transferred to a 100 mL volumetric flask, water was added to the final volume, and the experimental sample was obtained.

[0039] Experimental samples were diluted to different gradients, absorbance was measured at 490 nm, and the concentrations of polysaccharide compounds in the different experimental samples were calculated according to the glucose standard curve and regression equation. As shown in Figure 3, the detection results indicate that the CDLB-YE05 Kazachstania servazzii yeast was able to produce more polysaccharide compounds during fermentation in the wort medium compared to the other four yeasts that produced both gas and alcohol isolated from the dough.

[0040] Example 2 The mixed culture medium and yeast culture were prepared using the following steps.

[0041] 1) Preparation of mixed culture medium: 720-880g of malt, 90-110g of soybeans, and 90-110g of glutinous rice were weighed out, and each substance was roasted at 120°C for 2 hours, then crushed and uniformly mixed to obtain a mixed culture medium.

[0042] 2) Preparation of yeast culture: The freeze-dried powder of the CDLB-YE05 Kazachstania servazzii yeast obtained in Example 1 was activated in wort medium for 16-48 hours. Then, it was added to a mixed medium at a 1% inoculum (w / m), and 800-1000 g of mineral water was added per 1 kg of mixed medium and mixed uniformly. Sterile air was introduced at a flow rate of 1 L / min, and the culture was incubated at 15°C-35°C under aerobic conditions for 20-72 hours to obtain the yeast culture.

[0043] The CDLB-YE05 Kazachstania servazzii yeast can grow and reproduce in a mixed medium, and can decompose and convert large molecular proteins and starch granules in the mixed medium to produce ester fragrances and polysaccharide compounds. After culturing for 20 to 72 hours, the produced ester fragrance compounds, polysaccharide compounds, and medium components all constitute a yeast culture, with a total acidity of 30 mL / 100 g or less, a viable cell rate of 55% or more, and a polysaccharide compound content of 1 mg / mL or more as measured by the phenol-sulfuric acid method.

[0044] Examples 3 to 5 below relate to the preparation of yeast powder, and the specific details are as follows.

[0045] Example 3 Yeast powder was prepared using the yeast culture obtained in Example 2, and the specific process is as follows.

[0046] 1000g of yeast culture is mixed with 70g of skim milk powder and 9.5g of sorbitan monostearate, then freeze-dried and polished to obtain yeast powder. The resulting powder should have a moisture content of ≤10%, protein content of ≥4%, ash content of ≤10%, and yeast cell count of ≥10. 7 It was CFU.

[0047] Example 4 Yeast powder was prepared using the yeast culture obtained in Example 2, and the specific process is as follows.

[0048] 1000g of yeast culture was mixed with 60g of skim milk powder and 9g of sorbitan monostearate, then freeze-dried and polished to obtain yeast powder.

[0049] Example 5 Yeast powder was prepared using the yeast culture obtained in Example 2, and the specific process is as follows.

[0050] 1000g of yeast culture was mixed with 80g of skim milk powder and 10g of sorbitan monostearate, then freeze-dried and polished to obtain yeast powder.

[0051] Examples 6-9 below illustrate the use of yeast powder in wheat flour food processing, with specific details as follows.

[0052] Example 6 The yeast powder obtained in Example 3 was used in the processing of wheat flour food products to improve the texture and aroma of the noodles and to improve the chewiness of the noodles. The specific method is as follows.

[0053] In Example 3, 1 g of yeast powder and 1 kg of wheat flour were weighed, and 280 g of water, 1 g of edible salt, and 1 g of edible alkali were added and kneaded. The dough was then fermented at 20°C to 26°C for 4 hours and at 27°C to 30°C for 3 hours, respectively. After processing the fermented dough into noodles, the breaking strength of the cooked noodles was tested. The breaking strength was 15 g or more when the cross-section of the cooked noodles was larger than 2 mm * 2 mm.

[0054] Example 7 In Example 6, the amount of wheat flour added was adjusted to 1.1 kg, and the other process steps were the same as in Example 6.

[0055] Example 8 0.8 g of yeast powder and 1 kg of wheat flour obtained in Example 3 were weighed, and 300 g of water, 1.5 g of edible salt, and 1.5 g of edible alkali were added and kneaded. The dough was then fermented at 20°C to 26°C for 4 hours and at 27°C to 30°C for 3 hours, respectively. The fermented dough was processed into noodles, and the breaking strength of the cooked noodles was tested.

[0056] Example 9 In Example 8, the amount of wheat flour added was adjusted to 1.1 kg, and the other process steps were the same as in Example 8.

[0057] Example 10 is a comparative experiment on the use of yeast powder and other common yeast strains in wheat flour foods, specifically as follows:

[0058] Example 10 After adding the yeast powder prepared in Example 3 and other common yeast strains to wheat flour, the texture of the noodles was determined by detecting the colony growth during fermentation, changes in the polysaccharide compound content, and the breaking strength of the noodles.

[0059] 1) Selected yeast species and their sources

[0060] [Table 3]

[0061] 2) Culture medium: Potato dextrose agar (PDA), wort medium The specific components per liter of potato dextrose agar medium were 300.0g of potato (extracted from the leachate powder), 20.0g of glucose, 15.0g of agar, and 0.1g of chloramphenicol.

[0062] The specific components per liter of wort culture medium were 130.0 g of powdered malt extract and 0.1 g of chloramphenicol.

[0063] 3) Reagents and raw materials

[0064] [Table 4]

[0065] 4) Experimental equipment and facilities [Table 5]

[0066] 5) Experimental Process 5.1 Preparation of yeast culture solution 5.1.1 Activation of bacterial species The yeast powder, active dried yeast (high sugar type), active dried yeast (low sugar type), and wine-brewing yeast strain obtained in Example 3 were each weighed and inoculated into 10 mL of wort medium at a dose of 0.1% (w / v), and fermented aerobically at 30°C for 24 hours.

[0067] 5.1.2 Microscopic Examination of Bacterial Species Microscopic examination was performed on the four activated yeast species, and as shown in Figure 4, (a) is the colony morphology of yeast powder, (b) is the colony morphology of activated dried yeast (high sugar type), (c) is the colony morphology of activated dried yeast (low sugar type), and (d) is the colony morphology of wine-making yeast species.

[0068] 5.1.3 Adjustment of the number of colonies in the bacterial culture solution To ensure consistency in experimental conditions, the number of colonies in different activated yeast strains was adjusted together, and the specific steps were as follows:

[0069] Using fresh wort, the spectrophotometer was zeroed, the OD600 values ​​of different bacterial solutions were measured, and then gradually diluted with fresh wort to adjust the OD600 value to 0.5. The corresponding bacterial solution concentration was approximately 10 7The level was approximately CFU / mL.

[0070] 5.2 Creation of a glucose standard curve 50 mg of standard glucose was weighed into a volumetric flask, an appropriate amount of distilled water was added up to the 500 mL mark, and the flask was shaken uniformly to prepare a 100 μg / mL standard glucose solution. Then, as shown in Table 6, the standard glucose solution, distilled water, 5% phenol solution, and concentrated sulfuric acid were added, the flask was shaken thoroughly, and the mixture was heated in a boiling water bath for 30 minutes. After heating, the flask was removed, shaken uniformly, and cooled. After standing at room temperature for 20 minutes, the absorbance was measured at 490 nm.

[0071] As shown in Figure 5, a standard curve was plotted with glucose concentration on the x-axis and absorbance on the y-axis, and the regression equation was obtained.

[0072] [Table 6]

[0073] 5.3 Inoculation and fermentation of yeast in wheat flour Each ingredient was added according to the proportions in Table 7, resulting in a total of five groups. 500g of wheat flour was weighed into each group, along with 1g each of edible salt and alkali. 5mL of the prepared yeast solution from groups A, B, C, and D, and the blank from group E were weighed and added to 140mL of drinking water. After uniform mixing, the drinking water containing the yeast was gradually added to the wheat flour and stirred uniformly for 30 minutes. The dough was then fermented at a constant temperature of 30°C for 4 hours.

[0074] [Table 7]

[0075] 5.4 Extraction of polysaccharide compounds produced by wheat flour fermentation The specific steps are as follows:

[0076] For the fermentation of the wheat flour, 3g of sample was taken every 0.5 hours, spread evenly, and then partially dried by blowing air at 50°C. The temperature was then gradually increased to 80°C until the sample solidified. After the sample cooled, it was ground and passed through a sieve with a mesh diameter of 0.9 mm. The sieved sample was then uniformly mixed, placed in a wide-mouthed bottle, sealed, and stored.

[0077] 1.0 g of the sieved sample was weighed and placed in a 50 mL stoppered centrifuge tube. 5 mL of water was added to soak the sample, and 20 mL of anhydrous ethanol was gradually added. The mixture was shaken thoroughly to obtain a homogeneous mixture.

[0078] The mixture was ultrasonically extracted for 30 minutes, centrifuged for 10 minutes, washed with 10 mL of ethanol to remove insoluble matter, and then centrifuged again.

[0079] The insoluble substance was gradually transferred to a stoppered Erlenmeyer flask using 30 mL of water, sealed with a breathable airtight membrane, extracted in a boiling water bath for 2 hours, cooled to room temperature, and the filtrate was filtered for use.

[0080] The filtrate was transferred to a dialysis bag approximately 15 cm long, the dialysis bag was placed in a 1000 mL beaker containing distilled water, dialysis was performed at 4°C for 1 hour, the extracorporeal dialysis fluid was replaced, dialysis was continued for 2 hours, the extracorporeal dialysis fluid was replaced again, and finally, dialysis was continued for 3 hours, the extracorporeal dialysis fluid was replaced once more.

[0081] After dialysis was completed, the extracorporeal dialysate was removed, the solution in the dialysis bag was transferred to a 100 mL volumetric flask, water was added to the final volume, and the experimental sample was obtained.

[0082] 5.5 Measurement of Polysaccharide Compounds The experimental samples prepared in 5.4 were taken, diluted to different gradients, and their absorbance was measured at 490 nm. The concentration of polysaccharide compounds in the experimental samples was calculated according to the glucose standard curve and regression equation. As shown in Figure 6, after adding the yeast powder obtained in Example 3, the amount of polysaccharides produced by fermentation in the dough gradually increased as the fermentation time was extended. Since the polysaccharide content is proportional to the viscosity of the noodles, this improved the breaking strength of the noodles and made them chewier.

[0083] 5.6 Measurement of Yeast Count Experimental samples were taken after fermentation for 0.5 hours and 4 hours, and the number of viable yeast cells was measured using the plate counting method. The culture medium used for detection was potato dextrose agar.

[0084] As shown in Table 9, the yeast powder obtained in Example 3 had the fastest growth rate during dough fermentation.

[0085] 5.7 Measurement of noodle breaking force obtained from each sample Dough from different processing groups, fermented for 4 hours, was rolled, re-synthesized, and cut into strips according to a unified manufacturing standard. The cross-sectional size of the noodles was 3.5mm*3.5mm. After boiling the noodles, they were cooled in water for 150 seconds, and the length between the ends of the noodles was fixed at 10cm. The breaking force value when the noodles were pulled was measured using a tension gauge, with 35 measurements taken for each processing group. The original data was recorded as shown in Table 8, and the average value of the remaining data after removing the maximum and minimum values ​​from each group was calculated as shown in Table 9.

[0086] [Table 8]

[0087] [Table 9]

[0088] As described above, when the yeast species in the processed composition of wheat flour food is changed by a single element, the metabolic products of the yeast in the dough change, and the yeast powder provided by the present invention generates a large amount of polysaccharide compounds during metabolism. Considering that the content of polysaccharide compounds in the dough is proportional to its viscosity, adding the above-mentioned yeast powder to the processing of wheat flour food can improve the texture and mouthfeel of the wheat flour food.

[0089] The above are merely preferred specific embodiments of the present invention, and the scope of protection of the present invention is not limited thereto. Any changes or replacements that a person skilled in the art can easily conceive of within the technical scope described in the present invention are all included within the scope of protection of the present invention. Accordingly, the scope of protection of the present invention shall be in accordance with the claims.

Claims

1. This yeast strain is CDLB-YE05 Kazachstania servazzii, and is characterized by being stored at the Institute of Microbiology, Chinese Academy of Sciences on July 17, 2023, with storage number CGMCC NO. 27948 and storage address No. 3, Building 1, Beichen West Road, Chaoyang District, Beijing.

2. The yeast according to claim 1, characterized in that the nucleotide sequence of the yeast is as shown in SEQ No.

1.

3. A method for preparing yeast powder from the yeast described in claim 1, The yeast powder comprises the steps of mixing a yeast culture, skim milk powder, and sorbitan monostearate, followed by freeze-drying and polishing. A method characterized by adding 60g to 80g of skim milk powder and 9g to 10g of sorbitan monostearate per 1kg of the yeast culture.

4. The yeast culture is The method according to claim 3, characterized in that the yeast is activated for 16 to 48 hours, then inoculated into a mixed medium, water is added and the mixture is uniformly stirred, and then cultured for 20 to 72 hours under aerobic conditions at 15°C to 35°C.

5. The mixed culture medium is Weigh out 720 to 880 parts by mass of malt, 90 to 110 parts of soybeans, and 90 to 110 parts of glutinous rice. The method according to claim 4, characterized in that each weighed substance is baked at 120°C for 2 hours, then crushed and mixed.

6. Yeast powder prepared from the yeast strain described in Claim 1, Yeast powder characterized by having a moisture content of 10% or less, a protein content of 4% or more, an ash content of 10% or less, and a yeast cell count of 10⁷ CFU or more.

7. Use of yeast powder according to claim 6 in wheat flour food processing.

8. As a specific method, In the first step, weigh out the following in mass ratios: yeast powder 0.08-0.1, wheat flour 100-110, water 28-30, edible salt 0.1-0.15, and edible alkali 0.1-0.

15. The use of yeast powder in the processing of wheat flour products according to claim 7, characterized in that in the second step, weighed yeast powder, wheat flour, edible salt, edible alkali and water are mixed to form a dough, and the dough is fermented for 3 to 6 hours before a wheat flour product is manufactured.

9. The use of yeast powder in the processing of wheat flour foods according to claim 8, characterized in that the wheat flour food includes noodles, dumplings, wontons, and Chinese rice cakes.

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