A yeast strain for quickly fermenting sugar-free noodles and its application

Abstract

The present invention provides a yeast strain for making quick-rising sugar-free dough and its application. The Saccharomyces cerevisiae AMCC31248 strain provided herein is deposited with the China Center for Type Culture Collection (CCTCC) and has a deposit number of CCTCC NO: M 20211686. The Saccharomyces cerevisiae AMCC31248 strain provided herein exhibits excellent fermentation performance in sugar-free dough and can rapidly ferment sugar-free dough.

Description

Technical Field

[0001] The present invention relates to the field of microorganisms, and in particular to a yeast strain for quick-rising sugar-free noodles and applications thereof. Background Art

[0002] From the discovery of commercial baker's yeast to the formalization of yeast production technology, and now to the development of active dry yeast, yeast products have become increasingly diverse and of ever-improving quality, enabling their application in a wide range of pasta dishes. Fermented pasta, as a traditional staple food, holds a crucial place in the general diet. Statistics show that approximately half of my country's population relies primarily on pasta, with the majority consisting of unsweetened fermented doughs such as steamed buns and dumplings. From a health perspective, unsweetened or low-sugar pasta is increasingly popular with consumers.

[0003] In pasta production, the fermentation process of dough plays a crucial role, not only affecting the product's softness, taste, and nutritional value, but also determining how quickly the dough rises. The stronger the yeast's fermentation ability, the faster the dough rises, shortening the fermentation cycle, accelerating the pasta production process, and improving industrial production efficiency. Therefore, developing a strain of Saccharomyces cerevisiae with excellent fermentation properties in sugar-free dough is of vital practical significance. Summary of the Invention

[0004] During the pasta-making process, the ambient temperature is often too high, causing the yeast to rise too quickly during the dough mixing process, resulting in poor product quality. To lower the temperature of the dough, cold water is often added. However, yeast cells enter a state of shock when exposed to low temperatures, affecting their normal growth. Therefore, there is an urgent need for yeast to be resistant to cold osmotic shock.

[0005] Therefore, in order to solve the problems in the prior art of low efficiency and poor resistance to cold osmotic shock in fermenting sugar-free dough with brewer's yeast, the present invention provides a fast-rising yeast strain for sugar-free dough with resistance to cold osmotic shock.

[0006] In a first aspect, the present invention provides a Saccharomyces cerevisiae strain, wherein the Saccharomyces cerevisiae strain is:

[0007] Saccharomyces cerevisiae AMCC31248 strain (Saccharomyces cerevisiae AMCC31248) was deposited in the China Center for Type Culture Collection (CCTCC) with a deposit number of CCTCC NO: M 20211686.

[0008] In a second aspect, the present invention provides a fermentation preparation method of a brewer's yeast inoculant, the method comprising the following steps: culturing the brewer's yeast strain.

[0009] Preferably, the preparation method comprises the following steps:

[0010] (1) amplifying and culturing the Saccharomyces cerevisiae strain;

[0011] (2) adding the product obtained in step (1) into a liquid culture medium and fermenting and culturing the mixture at 26-32°C.

[0012] In a third aspect, the present invention provides a bacterial agent containing the Saccharomyces cerevisiae AMCC31248 strain.

[0013] Preferably, the bacterial agent is obtained by the fermentation preparation method.

[0014] In a fourth aspect, the present invention also provides the use of the Saccharomyces cerevisiae strain or the bacterial agent in fermentation.

[0015] In a fifth aspect, the present invention also provides the use of the brewer's yeast strain and the bacterial agent in dough.

[0016] In a sixth aspect, the present invention provides a dough containing the brewer's yeast strain or the bacterial agent.

[0017] Preferably, the dough contains flour and the Saccharomyces cerevisiae strain in a mass ratio of 100:0.5-5.

[0018] In a seventh aspect, the present invention also provides a method for preparing the dough, comprising the following steps: kneading the dough with water at 0-35°C.

[0019] In the present invention, the water at 0°C can be ice at 0°C, an ice-water mixture at 0°C, or liquid water at 0°C.

[0020] In the dough preparation process of the present invention, water, flour and brewer's yeast can be added in any order, such as first mixing the flour and yeast, and then adding 0-35°C water to knead the dough, or first adding flour to 0-35°C water and then adding brewer's yeast, or first adding brewer's yeast to 0-35°C water and then adding flour.

[0021] In an eighth aspect, the present invention further provides a noodle product obtained by the dough preparation method.

[0022] Preferably, the flour products are steamed buns, dumplings, bread, biscuits, noodles, pot stickers, etc.

[0023] The Saccharomyces cerevisiae AMCC31248 strain provided by the invention has good fermentation performance in sugar-free dough, can quickly ferment the sugar-free dough, and has good resistance to cold osmotic shock.

[0024] Culture collection information

[0025] The brewer's yeast AMCC31248 strain (Saccharomyces cerevisiae AMCC31248) provided by the present invention was deposited in the China Center for Type Culture Collection (CCTCC) on December 29, 2021, with the deposit number CCTCC NO: M20211686, and the deposit address: Wuhan University, Wuhan, China, Postal Code: 430072; Telephone: 027-68754052.

[0026] The Saccharomyces cerevisiae AMCC30010 strain used in the present invention was deposited in the China Center for Type Culture Collection (CCTCC) on March 29, 2022, with a deposit number of CCTCC NO: M2022340. The deposit address is: Wuhan University, Wuhan, China, Postal Code: 430072; Telephone: 027-68754052.

[0027] The Saccharomyces cerevisiae AMCC32101 strain provided by the present invention was deposited in the China Center for Type Culture Collection (CCTCC) on March 29, 2022, with a deposit number of CCTCC NO: M2022341. The deposit address is: Wuhan University, Wuhan, China, Postal Code: 430072; Telephone: 027-68754052. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Shown is a colony map of the Saccharomyces cerevisiae AMCC31248 strain;

[0029] Figure 2 Shown is a diagram of sporulation of the Saccharomyces cerevisiae strain AMCC31248;

[0030] Figure 3 Shown are the growth curves of the parent and new strains in wort medium. DETAILED DESCRIPTION

[0031] The present invention uses the cerevisiae AMCC30010 strain and the cerevisiae AMCC32101 strain as parents, and obtains the cerevisiae AMCC31248 strain provided by the present invention through a microhybridization method.

[0032] The Saccharomyces cerevisiae AMCC30010 strain is a Saccharomyces cerevisiae strain bred by Angel Yeast Co., Ltd. The original strain was collected from Yichang City, Hubei Province. Through optical microscopy, the cell morphology of the Saccharomyces cerevisiae strain is oval, budding, and the single colonies grown on the solid plate are spherical with a slightly raised center, milky white, smooth surface, and neat edges. Morphological observation and molecular biological identification under a high-power microscope determined that it is a Saccharomyces cerevisiae strain, which is a food attribute. It was deposited in the China Center for Type Culture Collection (CCTCC) on March 29, 2022, with the deposit number CCTCC NO: M 2022340.

[0033] The Saccharomyces cerevisiae AMCC32101 strain is a Saccharomyces cerevisiae strain bred by Angel Yeast Co., Ltd. The original strain was collected from Ulanqab City, Inner Mongolia Autonomous Region. Through optical microscopy, the cell morphology of the Saccharomyces cerevisiae strain is oval, budding, and the single colonies grown on the solid plate are spherical with a slightly raised center, milky white, smooth surface, and neat edges. Morphological observation and molecular biological identification under a high-power microscope determined that it is a Saccharomyces cerevisiae strain, which is a food attribute. It was deposited in the China Center for Type Culture Collection (CCTCC) on March 29, 2022, with the deposit number CCTCC NO: M2022341.

[0034] The cerevisiae AMCC31248 strain provided by the present invention has good fermentation performance in sugar-free dough and can quickly ferment the sugar-free dough.

[0035] The production of some sugar-free bread, soda crackers, steamed buns, etc. is mainly based on the fermentation of unsweetened dough. Most of the flour is starch, which is converted into maltose under the action of amylase in the flour. Therefore, the ability of yeast to utilize maltose determines the speed of the unsweetened dough rising. The maltose utilization enzyme system of yeast includes maltose hydrolase and maltose permease. Yeast with high maltose utilization ability is called fast-fermenting yeast.

[0036] Sugar-tolerant yeast refers to yeast that has a higher tolerance to sucrose in sugary dough, that is, its growth and fermentation performance in sugary bread is higher than that of ordinary yeast.

[0037] Low-sugar-tolerant yeast is used in dough systems with around 7% sucrose, while high-sugar-tolerant yeast is used in dough systems with higher sucrose concentrations, up to 25%. Sucrose is generally not directly usable by microorganisms, but Saccharomyces cerevisiae contains sucrose hydrolase, which acts on β-1,2-glycosidic bonds, hydrolyzing sucrose into D-glucose and D-fructose. Glucose and fructose then enter the glycolysis pathway for utilization by the yeast. Simultaneously, the rapid breakdown of sucrose produces glucose and fructose, increasing the osmotic pressure surrounding the yeast cells. The yeast cell membrane is a selectively semipermeable membrane. External concentrations can affect yeast cell activity. When cells are exposed to high osmotic pressure, water and protoplasm within the cell leak out of the membrane, leading to cell dehydration and even cell death. Therefore, the hyperosmotic environment faced by Saccharomyces cerevisiae in high-sugar doughs affects its growth and fermentation performance. Therefore, the gas production capacity of sugar-free yeast is determined by the activity of maltose-utilizing enzymes, while the gas production capacity of sugar-tolerant yeast is determined by the activity of sucrase.

[0038] The sources of the reagents and instruments used in the examples of the present invention are shown in Tables 1 and 2 below.

[0039] Table 1 Reagent information

[0040] Reagents Manufacturers for sale Yeast extract powder Angel Yeast Peptone Angel Yeast glucose Sinopharm Shanghai trial agar Huixing Potassium acetate Sinopharm Shanghai trial

[0041] Table 2 Instrument information

[0042] instrument model Manufacturers for sale Constant temperature shaker ZWYR-2102C Shanghai Smart City Biochemical incubator SPX-150BⅢ Tianjin Test Clean bench SKJH-1109 Shanghai Sukun analytical balance ME4002E METTLER TOLEDO pH meter PB-10 Sartorius Constant temperature water bath HH-2 Jiangsu Guohua centrifuge DL-5200B Anting, Shanghai Fast Moisture Meter MJ33 METTLER TOLEDO PCR instrument C1000 BIO-RAD Gel imaging system <![CDATA[Gel Doc TM XR + ]]> BIO-RAD electrophoresis apparatus EPS-300 Shanghai Tianneng optical microscope CX43 OLYMPUS Fully automatic growth curve analyzer BioscreenC OY Growth Curves Yeast micromanipulator MSM 400 SINGER

[0043] The formula of the spore production medium used in the embodiment of the present invention is: 1% potassium acetate, 0.1% yeast extract powder, 0.05% glucose, and 2% agar.

[0044] In the embodiment of the present invention, each strain of Saccharomyces cerevisiae was activated using YPD solid culture medium, the formula of which was: 1% yeast extract powder, 2% peptone, 2% glucose, and 2% agar.

[0045] In the embodiment of the present invention, each strain of Saccharomyces cerevisiae was cultured in YPD liquid culture medium, and the formula of YPD liquid culture medium was: 1% yeast extract powder, 2% peptone, and 2% glucose.

[0046] Example 1 Strain construction and identification

[0047] The parent strains, Saccharomyces cerevisiae AMCC30010 and Saccharomyces cerevisiae AMCC32101, were activated and induced to produce spores. After enzymatic hydrolysis, single spores were picked using a yeast micromanipulator. The spores from the two different parents were placed in contact and then incubated at 30°C. The spore morphology was observed, and after successful hybridization, the spores were further incubated at 30°C. This was the first-generation strain. The resulting first-generation strain was then hybridized with Saccharomyces cerevisiae AMCC30010 to obtain the second-generation strain, which was then tested for spore production. Hybrid strains were selected for subsequent screening.

[0048] The growth curves of the hybrid new strains obtained by hybridization were determined using the fully automatic growth curve analyzer Bioscreen C, and the hybrid strains with growth efficiency higher than that of the parents and ranked in the top 20 were selected.

[0049] A shake flask fermentation test was conducted on the 20 hybrid strains with higher growth efficiency than that of their parents. The net dry weight of the strains and the fermentation activity of their fresh yeast in a 0% sugar dough system were used as screening indicators. Hybrid strains whose yeast milk net dry weight could reach 95-105% of that of any parent and whose 0% sugar dough fermentation activity could reach 95%-150% of that of any parent were selected.

[0050] The hybrid strains screened in the above steps are then cultured in a 45 L fermentation tank, and the obtained yeast cells are prepared into active dry yeast. The fermentation activity of the active dry yeast in a 0% sugar dough system is measured, and new strains are selected that have no obvious abnormalities during the dry yeast preparation process and whose 0% sugar dough fermentation activity of the active dry yeast can reach 95%-120% of that of either parent.

[0051] Finally, the hybrid strains selected from the above steps were screened for resistance to cold osmotic shock. Using 0°C crushed ice, a 0% sugar dough containing active dry yeast from the hybrid strains was prepared. The dough proofing time was measured, and the hybrid strain with the shortest proofing time was selected as the target strain, thereby screening for hybrid strains with resistance to cold osmotic shock.

[0052] The above screening yielded a hybrid strain, designated AMCC31248, which exhibited high fermentation activity in 0% sugar dough and good resistance to cold osmotic shock. The strain was identified, yielding the following results:

[0053] The strain cells were observed to be oval in shape and reproduced by budding under an optical microscope. The single colonies grown on the solid plate were spherical with a slightly raised center, milky white in color, loose in texture, easily picked up by the inoculation loop, with a smooth, dry surface and neat edges. Figure 1 Shown is the colony map of the heterozygous strain AMCC31248.

[0054] The spore production of the hybrid strain AMCC31248 was examined under the microscope. Figure 2 As shown in the figure, there are many spores in the microscope field and the spores are relatively full, indicating that it has the ability to produce spores, that is, it is a heterozygous strain.

[0055] The resulting hybrid strain AMCC31248 was named Saccharomyces cerevisiae AMCC31248. The Saccharomyces cerevisiae AMCC31248 strain was deposited in the China Center for Type Culture Collection (CCTCC) on December 29, 2021, with a deposit number of CCTCC NO: M 20211686.

[0056] Example 2 Growth efficiency determination

[0057] The Saccharomyces cerevisiae AMCC31248 strain obtained in Example 1 and the parent strains Saccharomyces cerevisiae AMCC30010 and Saccharomyces cerevisiae AMCC32101 were inoculated into malt extract medium (purchased from Haibo Biotechnology) and cultured at 30°C for 48 h. The OD values of each strain at different times were determined by high-throughput analysis using the fully automatic growth curve analyzer Bioscreen C. 600 Value, with time (h) as the horizontal axis, the corresponding OD 600 The value is the vertical axis, the growth curve is drawn, the experimental data is analyzed and the growth efficiency of the strain is calculated according to the following formula.

[0058] Growth efficiency = (OD2-OD1) / (t2-t1)

[0059] OD1: OD corresponding to the strain at t1 600 value;

[0060] OD2: OD corresponding to the strain at t2 600 value;

[0061] t1: the starting time of the logarithmic growth phase;

[0062] t2: The end of the logarithmic growth phase.

[0063] The growth curve of Saccharomyces cerevisiae AMCC31248 is shown in the figure Figure 3 As shown, it can be seen that the strain can grow rapidly in the wort medium. Table 3 below shows the growth efficiency of the parent strain and the Saccharomyces cerevisiae AMCC31248 strain.

[0064] Table 3 Growth efficiency data of parent and new strains

[0065]

[0066] As can be seen from Table 3 above, the growth efficiency of the obtained Saccharomyces cerevisiae AMCC31248 strain is significantly higher than that of the parent strains Saccharomyces cerevisiae AMCC30010 and Saccharomyces cerevisiae AMCC32101.

[0067] Example 3 Fresh yeast fermentation activity detection

[0068] Saccharomyces cerevisiae AMCC31248 obtained in Example 1 was inoculated into a shake flask containing fermentation medium and cultured at 30°C. The precipitate collected after centrifugation was yeast milk. The yeast milk was weighed and its water content was determined. The net dry weight (g / L) of each strain in the shake flask was calculated according to the following formula:

[0069] Net dry weight (g / L) = weight of yeast milk × (1-water content)

[0070] Dough was prepared according to the 0% sugar dough system shown in Table 4 to test the fermentation activity of Saccharomyces cerevisiae AMCC31248. The mass of yeast milk required to be added to the Saccharomyces cerevisiae AMCC31248 strain and the parent strains Saccharomyces cerevisiae AMCC30010 and Saccharomyces cerevisiae AMCC32101 was calculated and weighed. Flour, salt, and water were weighed according to the dough recipe shown and mixed uniformly in a dough mixer to make raw dough. The total volume of carbon dioxide gas produced by yeast fermentation of 280 g of dough prepared according to the system shown in Table 4 at 30°C for 1 hour, i.e., the fermentation activity of the strain, was directly measured using an SJA fermentation instrument. The results are expressed in milliliters (mL).

[0071] Table 4 0% sugar dough system

[0072]

[0073] The relative percentages of net dry weight in Table 5 were calculated according to the following formula:

[0074] Net dry weight relative percentage (%) = (net dry weight of hybrid new strain / net dry weight of parent strain) * 100%

[0075] The relative percentage of dough fermentation activity of the Saccharomyces cerevisiae AMCC31248 strain compared to the parent strain in Table 6 was calculated according to the following formula:

[0076] Relative percentage of dough fermentation activity (%) = dough fermentation activity of hybrid new strain / dough fermentation activity of parent strain*100%

[0077] As shown in Table 5, the net dry weight of the Saccharomyces cerevisiae AMCC31248 strain was 95.7% and 109.9% of that of the parent strains Saccharomyces cerevisiae AMCC30010 and Saccharomyces cerevisiae AMCC32101, respectively. As shown in Table 6, the 0% sugar dough fermentation activity of the fresh yeast of the Saccharomyces cerevisiae AMCC31248 strain exceeded that of the two parent strains, with an advantage of about 10%.

[0078] Table 5 Net dry weight data of parent and new strains

[0079]

[0080] Table 6 Fermentation activity data of fresh yeast in 0% sugar dough system

[0081]

[0082] Example 4 Active Dry Yeast Fermentation Activity Detection

[0083] After activation and culture, the Saccharomyces cerevisiae AMCC31248 strain was scaled up in a 45-L fermenter. Active dry yeast was then obtained through separation, washing, filter pressing, and drying. Flour, salt, water, and the prepared active dry yeast were weighed according to the dough recipe shown in Table 7. The SJA method was used to determine the total amount of carbon dioxide produced during a one-hour fermentation of 280 g of dough prepared using the system shown in Table 7, representing the dough fermentation activity of the active dry yeast.

[0084] Table 7 0% sugar dough system

[0085]

[0086] Because the parent strain AMCC32101 exhibited significant drying difficulties during the active dry yeast preparation process and corresponding fermentation activity data were unavailable, only the dry yeast activity of the parent strain AMCC30010 was used as a control. The Saccharomyces cerevisiae strain AMCC31248 showed no significant abnormalities during the dry yeast preparation process. Specific data for the fermentation activity of its active dry yeast on 0% sugar dough are shown in Table 8. The relative percentage of fermentation activity in Table 8 was calculated as follows:

[0087] Relative percentage of fermentation activity = (fermentation activity of hybrid new strain / fermentation activity of parent strain AMCC 30010) * 100%

[0088] Table 8 Fermentation activity data of active dry yeast in 0% sugar dough system

[0089]

[0090] The results showed that compared with the parent Saccharomyces cerevisiae AMCC30010 strain, the active dry yeast of Saccharomyces cerevisiae AMCC31248 strain still had an 11.5% advantage in dough fermentation activity under 0% sugar conditions, indicating that Saccharomyces cerevisiae AMCC31248 strain has a certain degree of desiccation resistance.

[0091] Example 5 Active Dry Yeast Cold Osmotic Shock Resistance Test

[0092] Prepare the dough according to the dough recipe shown in Table 9 by pouring crushed ice at 0°C into a dough mixer. Add active dry yeast and mix at low speed. Then add flour and salt and continue mixing until evenly combined. Shape 400g of dough and place in a proofer to ferment. Control the temperature at 38±1°C and the humidity at 85-90%. Record the time it takes for the dough to reach the desired height (the fermentation time).

[0093] Table 9 Cold osmotic shock dough system

[0094]

[0095] The fermentation time of the dough corresponding to the Saccharomyces cerevisiae AMCC31248 strain and the parent Saccharomyces cerevisiae AMCC30010 strain is shown in Table 10. The relative percentage calculation method of the fermentation time in Table 10 is as follows:

[0096] Relative percentage of fermentation time = (fermentation time of hybrid new strain / fermentation time of parent strain AMCC30010) * 100%

[0097] Table 10 Fermentation time data of active dry yeast in cold osmotic shock dough system

[0098]

[0099] The results showed that the fermentation time of the Saccharomyces cerevisiae AMCC31248 strain was only 70.0% of that of the parent Saccharomyces cerevisiae AMCC30010 strain, with a 30% advantage, indicating that under the same conditions, the Saccharomyces cerevisiae AMCC31248 strain can ferment dough faster and has excellent resistance to cold osmotic shock.

[0100] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A quick-growing sugar-free noodle yeast strain with cold osmotic shock resistance, characterized in that: The fast-growing sugar-free noodles yeast strain with cold osmotic shock resistance is: Saccharomyces cerevisiae AMCC31248 strain (Saccharomyces cerevisiae) AMCC31248 was deposited in China Center for Type Culture Collection (CCTCC) with a deposit number of CCTCC NO: M20211686.

2. A fermentation method for preparing a brewer's yeast inoculum, characterized in that: The method comprises the following steps: culturing the brewer's yeast strain for making quick-growing sugar-free noodles with cold osmotic shock resistance according to claim 1.

3. The preparation method according to claim 2, characterized in that The preparation method comprises the following steps: (1) amplifying and culturing the quick-rising sugar-free noodles with cold osmotic shock resistance described in claim 1 using a Saccharomyces cerevisiae strain; (2) adding the product obtained in step (1) into a liquid culture medium and fermenting and culturing the mixture at 26-32°C.

4. A bacterial agent, characterized in that The bacterial agent contains the Saccharomyces cerevisiae AMCC31248 strain for quick-rising sugar-free noodles with cold osmotic shock resistance as claimed in claim 1.

5. The microbial agent according to claim 4, characterized in that The bacterial agent is prepared by the fermentation preparation method according to claim 2 or 3.

6. Use of the quick-rising sugar-free dough yeast strain having cold osmotic shock resistance according to claim 1 or the bacterial agent according to claim 4 or 5 in sugar-free dough.

7. A dough, characterized in that: The dough contains the quick-rising sugar-free yeast strain for noodles with cold osmotic shock resistance according to claim 1 or the bacterial agent according to claim 4 or 5.

8. The dough according to claim 7, characterized in that The dough contains flour and the fast-rising sugar-free yeast strain for noodles with cold osmotic shock resistance in a mass ratio of 100:0.5-5.

9. The method for preparing the dough according to claim 7 or 8, characterized in that: The preparation method comprises the following steps: kneading flour with water at 0-35°C.

10. A noodle product prepared by the dough preparation method according to claim 9. The noodle product according to claim 10 , which is steamed buns, dumplings, bread, biscuits, noodles or pot stickers.

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