Yeast, yeast powder and use thereof in cooked wheaten food processing

Abstract

Disclosed in the present invention are a yeast, yeast powder, and a use thereof in cooked wheaten food processing. The yeast is CDLB-YE05 Kazachstania servazzii, which was preserved at the Institute of Microbiology of the Chinese Academy of Sciences on July 17, 2023, the preservation number is CGMCC NO. 27948, and the preservation address is No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing. By preparing the yeast powder using the CDLB-YE05 Kazachstania servazzii provided in the present invention and using the yeast powder in cooked wheaten food processing, polysaccharide compounds generated by reproduction and metabolism of the saccharomycetes in dough are increased, the viscosity of the food is increased, the cooked wheaten food is more chewy, the fragrance is rich, and the taste is good.

Description

Yeast, yeast powder and application thereof in pasta processing Technical Field

[0001] The invention belongs to the technical field of microorganisms, and in particular relates to a yeast, yeast powder and application thereof in pasta processing. Background Art

[0002] Noodles are a beloved food in China. For thousands of years, our ancestors have handcrafted numerous unique noodles with distinct local flavors and textures. These exceptionally chewy and delicious noodles have become local delicacies. However, with industrial advancements, it's becoming increasingly difficult to recreate the unique texture and flavor of traditional noodles using machines in modern society. This is due to differences in yeast strains found in different regions and populations. When inoculated into dough, these yeasts produce different metabolites during starch fermentation, such as carbon dioxide, organic acids, alcohol, alcohol compounds, sugar compounds, and ester compounds. These metabolites contribute to the distinct flavors of the noodles. More sugar compounds make the starch stickier, while more lipid compounds contribute to the aroma and richer texture of the noodles, which are the primary reasons for their chewiness and rich texture. Machine-made noodles lack the yeast fermentation process, and therefore cannot reproduce the unique texture of traditional noodles.

[0003] Therefore, it is urgent to provide a novel yeast that can produce carbohydrate compounds and lipid compounds to improve the gluten and fragrance of flour foods.

[0004] Summary of the Invention

[0005] The purpose of the present invention is to provide a yeast, yeast powder and application thereof in pasta processing, which solves the problem that various pasta produced by existing processes are not chewy enough and have a bad taste.

[0006] In order to achieve the above-mentioned purpose, the first technical solution of the present invention is implemented as follows: a yeast, the yeast is CDLB-YE05 Ser Kazakhstan yeast, which was deposited in the Institute of Microbiology, Chinese Academy of Sciences on July 17, 2023, with the deposit number CGMCC NO.27948, and the deposit address is No. 3, No. 1 Beichen West Road, Chaoyang District, Beijing.

[0007] Furthermore, the nucleotide sequence of the yeast is shown in SEQ No. 1.

[0008] The second technical solution of the present invention is achieved as follows: a yeast powder prepared from the above yeast, wherein the yeast powder is obtained by mixing yeast culture, skim milk powder, and sorbitan monostearate, followed by freeze-drying and grinding; and 60g to 80g of skim milk powder and 9g to 10g of sorbitan monostearate are added to each kilogram of yeast culture;

[0009] The yeast culture is prepared by culturing the yeast.

[0010] Furthermore, the moisture content of the yeast powder is not more than 10%, the protein content is not less than 4%, the ash content is not more than 10%, and the yeast count is not less than 10 7 CFU.

[0011] Furthermore, the yeast culture is prepared by the following method:

[0012] The yeast is activated for 16 to 48 hours and then inoculated into a mixed culture medium. After adding water and stirring evenly, the culture is carried out under aerobic conditions at 15 to 35° C. for 20 to 72 hours to obtain a yeast culture.

[0013] Furthermore, the mixed culture medium is prepared by the following method:

[0014] Weigh 720-880 parts of malt, 90-110 parts of soybeans, and 90-110 parts of glutinous rice according to their mass;

[0015] The weighed substances were baked at 120° C. for 2 h, crushed and mixed to obtain a mixed culture medium.

[0016] The third technical solution of the present invention is achieved as follows: the yeast powder is used in pasta processing.

[0017] Furthermore, the specific method is:

[0018] S1. Weigh the following ingredients according to the mass ratio: yeast powder 0.08-0.1, wheat flour 100-110, water 28-30, edible salt 0.1-0.15, edible alkali 0.1-0.15;

[0019] S2. Mix the weighed yeast powder, wheat flour, edible salt, edible alkali and water to form a dough, and ferment the dough for 3 to 6 hours to prepare pasta.

[0020] Furthermore, the pasta includes noodles, dumplings, wontons, and cakes.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] By using the yeast provided by the present invention to prepare yeast powder and using the yeast powder in pasta processing, the polysaccharide compounds produced by the reproduction and metabolism of the yeast in flour can be increased, the viscosity of the flour food can be increased, and the flour food can be made more chewy and have a better taste. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG1 shows the colony morphology of CDLB-YE05 Kazakh yeast strain sergi on potato dextrose agar;

[0024] FIG2 shows the colony morphology of CDLB-YE05 Kazakh yeast strain sergi on malt extract medium;

[0025] FIG3 is a comparison of the polysaccharide content produced by different yeasts;

[0026] Figure 4: (a) shows the colony morphology of yeast powder, (b) shows the colony morphology of active dry yeast (high sugar type), (c) shows the colony morphology of active dry yeast (low sugar type), and (d) shows the colony morphology of wine yeast strains;

[0027] Figure 5 is a glucose standard curve;

[0028] FIG6 is a comparison chart of the concentrations of polysaccharide compounds in each group of samples in Example 4. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0030] In the description of the present invention, it should be clarified that the terms "vertical", "transverse", "longitudinal", "front", "rear", "left", "right", "up", "down", "horizontal", etc. indicating orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, which are only for the convenience of describing the present invention, and do not mean that the device or element referred to must have a specific orientation or position, and therefore cannot be understood as a limitation on the present invention. In the description of the present invention, it should be noted that, unless otherwise clearly stipulated and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] Example 1

[0032] Isolate and purify yeast, and identify the obtained yeast.

[0033] 1) Sample source: Lanzhou Ramen Noodles

[0034] Among all types of noodles, Lanzhou ramen is a regional delicacy with unique local characteristics. Because it takes a long time to be handmade and the number and variety of yeast strains inoculated in the dough increase, it is particularly chewy and has a unique taste and aroma.

[0035] 2) Culture medium: potato dextrose agar (PDA), malt wort medium

[0036] The specific components of potato dextrose agar per liter are: 300.0g of potato (from which the extract powder is extracted), 20.0g of glucose, 15.0g of agar, and 0.1g of chloramphenicol.

[0037] The specific components of each liter of malt extract culture medium are: 130.0g of malt extract powder and 0.1g of chloramphenicol.

[0038] 3) Reagents and instruments used

[0039] Table 1 List of reagents and instruments used in Example 1

[0040] 4) Single strain isolation

[0041] Weigh 25g of Lanzhou ramen noodles, add 225mL of sterile saline to make a 1:10 sample solution, and dilute it by 10 times to 10 6 Gradient sample solution;

[0042] At each dilution, take 1 mL of the sample solution and add it to two plates. Then, measure 20 mL of potato dextrose agar cooled to 46°C and inject it into the plates. After cooling and solidifying, place them in a fungal incubator at 28°C for five days.

[0043] Observe the morphology of the colonies and select single colonies from them. Continuously streak the selected single colonies on potato dextrose agar plates for culture, and then observe the morphology of the single colonies until different single strains are isolated.

[0044] 5) Screening for non-gas-producing strains

[0045] Prepare 180 mL of malt extract medium, autoclave at 115°C for 15 min, cool, and dispense into 18 sterile 15 mL glass test tubes. Empty the air from the Duroc tubes and place the Duroc tubes with the opening facing downwards in each test tube.

[0046] Select a single strain obtained in 4) and inoculate it into the wort medium of each test tube. Add a breathable filter membrane to each test tube and seal it. Incubate the culture at 30±1°C and 160 rpm for 72 h. Observe the turbidity rate and gas production of the strain growth, and select the strain with a fast turbidity rate and no gas production.

[0047] 6) Screening for non-alcohol-producing strains

[0048] The non-gas-producing strain screened in 5) was diluted 10-fold to 10 6 For each dilution of the sample solution, pipette 1 mL of the sample solution into two sterile plates. Measure 20 mL of potato dextrose agar cooled to 46°C and inject it into the plates. After cooling and solidification, incubate the plates in a fungal incubator at 28°C for five days. Observe the colony morphology and select medium-to-large single colonies with smooth surfaces and neat edges.

[0049] The above-mentioned medium-sized and large single colonies were inoculated into malt extract medium, and cultured with shaking at 30±1°C and 160 rpm for 72 h to obtain bacterial solution;

[0050] Pipette 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;

[0051] Select the strain that has not changed color and repeat the above screening steps until a yeast strain that produces neither gas nor alcohol is selected.

[0052] The non-gas-producing and non-alcohol-producing yeast strain and the gas-producing and alcohol-producing yeast strain obtained in the above process were inoculated into the malt wort culture medium at the same time, and their reproduction and metabolism were observed. It was found that the non-gas-producing and non-alcohol-producing yeast strain made the malt wort culture medium more viscous and had a rose scent.

[0053] 7) Purification and genome sequencing of non-gas-producing and non-alcohol-producing yeast strains

[0054] Prepare 100 mL of malt extract medium in a triangular flask and sterilize it by autoclaving at 115°C for 15 min before use;

[0055] Add a small amount of malt extract medium to a non-gas-producing and non-alcohol-producing yeast strain and suspend it. Pour the suspension into the malt extract medium in a triangular flask, seal it with a breathable filter membrane, and shake-culture it at 28±1℃ and 120r / min for 48h.

[0056] The bacterial precipitate obtained after centrifugation and washing of the wort bacterial suspension was quickly frozen in liquid nitrogen, placed in a sample tube, and sent to the Shenzhen Institute of Metrology and Quality Inspection for strain identification. It was identified as CDLB-YE05 Kazakhstan yeast by 18sRNA. The sample was sent to the Wuhan Sequencing Center of BGI for genome sequencing. The nucleotide sequence of CDLB-YE05 Kazakhstan yeast is shown in SEQ No. 1 and Table 2.

[0057] Table 2 Nucleotide sequence of CDLB-YE05 Kazakh yeast

[0058] 8) Colony morphology of CDLB-YE05 Kazakh yeast

[0059] CDLB-YE05 Kazakh yeast strains were inoculated on potato dextrose agar plates and cultured at 28°C for 5 days. The colony morphology was observed. As shown in Figure 1, the colonies of CDLB-YE05 Kazakh yeast strains were milky white, round, smooth, opaque, non-reflective, and had neat edges.

[0060] CDLB-YE05 Kazakhstan yeast was inoculated into malt extract medium and cultured at 30°C for 2 days. The cells of CDLB-YE05 Kazakhstan yeast were turbid, sterile, did not produce film, had an ester aroma, and had no unpleasant odor. The cell morphology of CDLB-YE05 Kazakhstan yeast was observed under a microscope, as shown in Figure 2, and the cell morphology was ascospherical.

[0061] 9) Genome characteristics of CDLB-YE05 Kazakh yeast

[0062] CDLB-YE05 Kazakh yeast has a genome with a total length of 13,468,544 bp, 5,415 genes, a GC content of 34.25%, a gene length accounting for 66.81% of the total genome length, 6,260 exons, accounting for 64.51% of the total genome length, 5,415 CDS regions, accounting for 64.51% of the total genome length, 845 introns, accounting for 2.31% of the total genome length, 1046 reads of various types of non-coding RNA (ncRNA) copies, accounting for 0.8106% of the total genome length, and 2,034,046 bp of various types of repetitive sequences, accounting for 15.1022% of the total genome length.

[0063] 10) CDLB-YE05 Kazakh yeast strain collection

[0064] Under a sterile environment, use an inoculating loop to pick a single colony of CDLB-YE05 Kazakh yeast, inoculate it into 250 mL of sterile malt juice, shake it evenly, and then expand it at a constant temperature of 28±1℃ for 48 hours. Pick the malt juice for microscopic examination to observe the production of ascospherical yeast in the colony morphology and the distribution of the colonies. If the field of view is full of ascospherical yeast, the expansion is successful. Otherwise, continue to culture and inspect it under a microscope every 2 hours until the expansion is successful.

[0065] In a sterile environment, add 17.5g of skim milk powder to 250mL of the successfully expanded bacterial liquid, mix well and freeze-dry. Take the freeze-dried powder to test the colony count of CDLB-YE05 Kazakhstan yeast and check if the colony count is greater than 10. 7 CFU is used as the basis for preservation.

[0066] The lyophilized powder of CDLB-YE05 Kazakh yeast was dispensed into cryopreservation tubes at a rate of 0.1 g per tube, placed in vacuum packaging bags, vacuum-sealed, labeled, and stored at -80°C.

[0067] CDLB-YE05 Kazakh yeast strain Serebrensis was deposited at the Institute of Microbiology, Chinese Academy of Sciences on July 17, 2023, with the deposit number CGMCC NO.27948, and the deposit address is No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing.

[0068] 11) Polysaccharide production by CDLB-YE05 Kazakh yeast strain

[0069] CDLB-YE05 Kazakh yeast and four gas-producing and alcohol-producing yeasts isolated from dough were inoculated into wort medium and cultured for 24 h. 10 mL of the wort fermentation liquid at 0 h, 4 h, 8 h, 12 h, 16 h, 20 h, and 24 h were measured respectively.

[0070] The wort fermentation liquid was centrifuged at 3500 r / min for 30 min, the bacteria were discarded, 1.5 g of trichloroacetic acid was added to the obtained supernatant, the mixture was evenly suspended, and the mixture was allowed to stand at 4°C for 1 h.

[0071] The suspension was centrifuged at 11,000 r / min for 1 min, the protein precipitate was discarded, and the supernatant was transferred to a dialysis bag about 15 cm long. The dialysis bag was placed in a beaker filled with distilled water. After dialysis at 4°C for 1 h, the dialysis fluid was replaced. After continuing dialysis for 2 h, the dialysis fluid was replaced again and dialysis was continued for 3 h.

[0072] After the dialysis was completed, the dialysis fluid was discarded, and the solution in the dialysis bag was transferred to a 100 mL volumetric flask, and water was added to make up the volume to obtain the experimental sample.

[0073] The experimental samples were diluted into different gradients, and the absorbance was measured at 490 nm. The concentrations of polysaccharides in different experimental samples were calculated by comparing with the glucose standard curve and regression equation. The test results are shown in Figure 3. Compared with the other four gas-producing and alcohol-producing yeasts isolated from dough, CDLB-YE05 Kazakh yeast can produce more polysaccharides when fermented in malt juice medium.

[0074] Example 2

[0075] Prepare mixed media and yeast cultures using the following procedures.

[0076] 1) Preparation of mixed culture medium:

[0077] 720-880 g of malt, 90-110 g of soybeans, and 90-110 g of glutinous rice were weighed, and each substance was baked at 120° C. for 2 h, then crushed and mixed uniformly to obtain a mixed culture medium.

[0078] 2) Preparation of yeast culture:

[0079] The lyophilized powder of CDLB-YE05 Kazakh yeast obtained in Example 1 was activated in a wort medium for 16 to 48 hours, and then added to a mixed culture medium at a 1% inoculum amount (w / m). 800 g to 1000 g of mineral water was added to each kilogram of the mixed culture medium and stirred evenly. Sterile air was introduced at a flow rate of 1 L / min, and the culture was cultured at 15° C. to 35° C. under aerobic conditions for 20 h to 72 h to obtain a yeast culture.

[0080] CDLB-YE05 Kazakh yeast can grow and reproduce in a mixed culture medium, and can decompose and convert large molecular proteins and starch granules in the mixed culture medium to produce ester aroma and polysaccharide compounds. After culturing for 20 hours to 72 hours, the ester aroma compounds, polysaccharide compounds and culture medium components it produces together constitute the yeast culture, the total acidity of which does not exceed 30mL / 100g, the viable cell rate is not less than 55%, and the polysaccharide compound content measured by the phenol-sulfuric acid method is not less than 1mg / mL.

[0081] The following Examples 3-5 are about the preparation of yeast powder, and the specific contents are as follows:

[0082] Example 3

[0083] Yeast powder was prepared using the yeast culture obtained in Example 2. The specific process was as follows:

[0084] Add 70g skim milk powder and 9.5g sorbitan monostearate to 1000g yeast culture, mix well, freeze-dry, and grind to obtain yeast powder, wherein the moisture content is ≤10%, protein ≥4%, ash ≤10%, and yeast count ≥107 CFU.

[0085] Example 4

[0086] Yeast powder was prepared using the yeast culture obtained in Example 2. The specific process was as follows:

[0087] 60 g of skimmed milk powder and 9 g of sorbitan monostearate were added to 1000 g of yeast culture, mixed evenly, freeze-dried, and ground to obtain yeast powder.

[0088] Example 5

[0089] Yeast powder was prepared using the yeast culture obtained in Example 2. The specific process was as follows:

[0090] 80 g of skimmed milk powder and 10 g of sorbitan monostearate were added to 1000 g of yeast culture, mixed evenly, freeze-dried, and ground to obtain yeast powder.

[0091] The following Examples 6-9 are examples of the application of yeast powder in pasta processing, and the specific contents are as follows:

[0092] Example 6

[0093] The yeast powder prepared in Example 3 is used in noodle processing to improve the taste and aroma of noodles and make the noodles more chewy. The specific method is as follows:

[0094] Weigh 1 g of the yeast powder prepared in Example 3 and 1 kg of flour, add 280 g of water, 1 g of edible salt and 1 g of edible alkali, knead and proof at 20°C to 26°C for 4 h and 27°C to 30°C for 3 h, respectively. After the proofed dough is processed into noodles, the breaking strength of the cooked noodles is tested. When the cross-section of the cooked noodles is greater than 2 mm*2 mm, the breaking force is not less than 15 g.

[0095] Example 7

[0096] The amount of wheat flour added in Example 6 was adjusted to 1.1 kg, and the other process steps were the same as in Example 6.

[0097] Example 8

[0098] Weigh 0.8 g of the yeast powder prepared in Example 3 and 1 kg of flour, add 300 g of water, 1.5 g of edible salt and 1.5 g of edible alkali, knead and proof at 20°C to 26°C for 4 h and 27°C to 30°C for 3 h, respectively. After the proofed dough is processed into noodles, the breaking strength of the cooked noodles is tested.

[0099] Example 9

[0100] The amount of wheat flour added in Example 8 was adjusted to 1.1 kg, and the other process steps were the same as in Example 8.

[0101] Example 10 is a comparative experiment on the application of yeast powder and other common yeasts in pasta, as follows:

[0102] Example 10

[0103] After adding the yeast powder prepared in Example 3 and other common yeasts to flour, the bacterial colony growth status, changes in polysaccharide content, and the breaking strength of noodles during the fermentation process were tested to determine whether the noodles were chewy or not.

[0104] 1) Selected yeast species and their sources

[0105] Table 3 Yeast strains selected

[0106] 2) Culture medium: potato dextrose agar (PDA), malt wort medium

[0107] The specific components of potato dextrose agar per liter are: 300.0g of potato (from which the extract powder is extracted), 20.0g of glucose, 15.0g of agar, and 0.1g of chloramphenicol.

[0108] The specific components of each liter of malt extract culture medium are: 130.0g of malt extract powder and 0.1g of chloramphenicol.

[0109] 3) Reagents and raw materials

[0110] Table 4 List of selected reagents

[0111] 4) Experimental equipment and instruments

[0112] Table 5 List of selected instruments

[0113] 5) Experimental process

[0114] 5.1 Preparation of yeast culture liquid

[0115] 5.1.1 Bacteria Activation

[0116] The yeast powder, active dry yeast (high sugar type), active dry yeast (low sugar type), and wine Saccharomyces cerevisiae strain prepared in Example 3 were weighed separately, inoculated into 10 mL of malt wort medium at a 0.1% (w / v) inoculation rate, and aerobically fermented at 30°C for 24 h.

[0117] 5.1.2 Microscopic examination of bacterial strains

[0118] The four activated yeast strains were examined under a microscope, as shown in FIG4 . FIG4 (a) shows the colony morphology of yeast powder, (b) shows the colony morphology of active dry yeast (high sugar type), (c) shows the colony morphology of active dry yeast (low sugar type), and (d) shows the colony morphology of wine brewing yeast strains.

[0119] 5.1.3 Adjustment of bacterial culture colony count

[0120] In order to ensure the consistency of experimental conditions, the colony counts in different yeast strains after activation were uniformly adjusted. The specific steps are as follows:

[0121] Use fresh wort to adjust the spectrophotometer to zero, measure the OD600 value of different bacterial cultures, and gradually dilute with fresh wort to adjust the OD600 value to 0.5, which corresponds to a bacterial culture concentration of approximately 10 7 CFU / mL or so.

[0122] 5.2 Preparation of glucose standard curve

[0123] Weigh 50 mg of standard glucose into a volumetric flask, add appropriate amount of distilled water to the 500 mL mark, shake well to prepare a 100 μg / mL standard glucose solution, then add standard glucose solution, distilled water, 5% phenol solution, and concentrated sulfuric acid as shown in Table 6, shake well, heat in a boiling water bath for 30 minutes, remove from the flask, shake well, cool, and place at room temperature for 20 minutes before measuring the absorbance at 490 nm.

[0124] With glucose concentration as the horizontal axis and absorbance as the vertical axis, a standard curve was drawn and the regression equation was obtained, as shown in FIG5 .

[0125] Table 6 Formulas of reagents for preparing glucose standard curve

[0126] 5.3 Inoculation of flour with yeast for fermentation

[0127] Various ingredients were added according to the ratio in Table 7, for a total of five groups, of which 500 g of flour, 1 g of edible salt and 1 g of alkali were weighed for each group. 5 mL of the adjusted yeast solution of groups A, B, C, and D and the blank of group E were measured and added to 140 mL of drinking water and mixed evenly. Then, the drinking water containing yeast was slowly added to the flour and stirred evenly for half an hour. The dough was fermented at a constant temperature of 30°C for 4 hours.

[0128] Table 7 Mixing ratio of each yeast solution and flour

[0129] 5.4 Extraction of polysaccharides produced by flour fermentation

[0130] The specific steps are as follows:

[0131] During the flour fermentation process, 3 g of sample was taken every 0.5 h, spread out and evenly distributed, and then dried at 50 ° C with air blower until half dry. Then the temperature was gradually increased to 80 ° C until the sample agglomerated. After cooling, the sample was crushed and sieved with a sieve hole diameter of 0.9 mm. After the sieved sample was mixed, it was placed in a wide-mouth bottle and sealed for storage.

[0132] Weigh 1.0 g of the sieved sample and place it in a 50 mL stoppered centrifuge tube. Add 5 mL of water to soak the sample, then slowly add 20 mL of anhydrous ethanol and shake thoroughly to obtain a uniform mixture.

[0133] The mixture was ultrasonically extracted for 30 min, centrifuged for 10 min, and then the insoluble matter was washed with 10 mL of ethanol and centrifuged again.

[0134] The insoluble matter was transferred into a stoppered conical flask with 30 mL of water, sealed with a breathable sealing film, and extracted in a boiling water bath for 2 h. The mixture was cooled to room temperature and the filtrate was filtered for later use.

[0135] Transfer the filtrate to a dialysis bag about 15 cm long, and place the dialysis bag in a 1000 mL beaker filled with distilled water. After dialyzing at 4°C for 1 hour, replace the dialysis fluid. Then continue to dialyze for 2 hours and replace the dialysis fluid again. Finally, continue to dialyze for 3 hours and replace the dialysis fluid again.

[0136] After the dialysis was completed, the dialysis fluid was discarded, and the solution in the dialysis bag was transferred to a 100 mL volumetric flask, and water was added to make up the volume to obtain the experimental sample.

[0137] 5.5 Determination of polysaccharides

[0138] The experimental samples prepared in 5.4 were diluted into different gradients, and the absorbance was measured at 490 nm. The concentration of polysaccharide compounds in the experimental samples was calculated by comparing with the glucose standard curve and the regression equation. As shown in Figure 6, after adding the yeast powder prepared in Example 3, the polysaccharide content produced by fermentation in the dough gradually increased with the extension of fermentation time. Since the polysaccharide content is proportional to the viscosity of the noodles, the breaking strength of the noodles was increased, and the noodles were more chewy.

[0139] 5.6 Yeast count determination

[0140] The experimental samples fermented for 0.5 h and 4 h were taken and the number of live yeast cells therein was determined by plate count method. The culture medium used for the detection was potato dextrose agar.

[0141] The test results are shown in Table 9. The yeast powder prepared in Example 3 has the fastest reproduction speed during dough fermentation.

[0142] 5.7 Determination of the breaking strength of noodles prepared from each sample

[0143] The dough of different treatment groups after fermentation for 4 hours was rolled, compounded, and cut into strips according to a unified standard. The cross-sectional size of the noodles was 3.5 mm*3.5 mm. The noodles were boiled for 150 seconds and then cooled in cold water. The length of the noodles at both ends was fixed at 10 cm. The breaking force of the noodles when they were broken was measured with a tensile tester. Different treatment groups were measured 35 times, and the original data were recorded, as shown in Table 8. The average value of the remaining data after removing the highest and lowest values ​​in each group was calculated, as shown in Table 9.

[0144] Table 8 Specific data of breaking strength of noodles in different treatment groups

[0145] Table 9 Average breaking strength of noodles in each treatment group

[0146] In summary, when the yeast species in the wheat pasta processing formula is changed by a single factor, the metabolic products of the yeast in the dough will change. The yeast powder provided by the present invention will produce a large amount of polysaccharide compounds during the metabolism process. Given that the content of polysaccharide compounds in the dough is proportional to its viscosity, adding the above-mentioned yeast powder during pasta processing can improve the chewiness and taste of the pasta.

[0147] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A yeast, characterized in that: The yeast is CDLB-YE05 Kazakhstan yeast, which was deposited at the Institute of Microbiology, Chinese Academy of Sciences on July 17, 2023, with the deposit number CGMCC NO.27948, and the deposit address is No. 3, Yard No. 1, Beichen West Road, Chaoyang District, Beijing.

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

1.

3. A yeast powder prepared from the yeast according to claim 1 or 2, characterized in that: The yeast powder is obtained by mixing yeast culture, skimmed milk powder and sorbitan monostearate, followed by freeze drying and grinding; and 60g to 80g of skimmed milk powder and 9g to 10g of sorbitan monostearate are added to each kilogram of yeast culture; The yeast culture is obtained by culturing the yeast.

4. A yeast powder according to claim 3, characterized in that: The moisture content of the yeast powder is not more than 10%, the protein content is not less than 4%, the ash content is not more than 10%, and the yeast count is not less than 10 7 CFU.

5. The yeast powder according to claim 3, characterized in that: The yeast culture is prepared by the following method: The yeast is activated for 16 hours to 48 hours, then inoculated into a mixed culture medium, water is added and stirred evenly, and then cultured under aerobic conditions at 15° C. to 35° C. for 20 hours to 72 hours to obtain a yeast culture.

6. The yeast powder according to claim 5, characterized in that: The mixed culture medium is prepared by the following method: Weigh 720-880 parts of malt, 90-110 parts of soybeans, and 90-110 parts of glutinous rice according to mass; The weighed substances were baked at 120° C. for 2 h, crushed and mixed to obtain a mixed culture medium.

7. Use of the yeast powder according to any one of claims 3 to 6 in pasta processing.

8. The use of yeast powder in pasta processing according to claim 7, characterized in that: The specific method is: S1. Weigh the following according to the mass ratio: yeast powder 0.08-0.1, wheat flour 100-110, water 28-30, Edible salt 0.1~0.15, edible alkali 0.1~0.15; S2. Mix the weighed yeast powder, wheat flour, edible salt, edible alkali and water to form dough, and ferment the dough for 3 hours to 6 hours to prepare pasta.

9. The use of yeast powder in pasta processing according to claim 8, characterized in that: The pasta includes noodles, dumplings, wontons and cakes.

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