Fresh-keeping noodles and preparation process thereof

Abstract

The application belongs to the technical field of food processing, and particularly relates to a fresh-keeping noodle and a preparation process thereof. The fresh-keeping noodle comprises the following preparation steps: (1) dough mixing and fermentation to obtain a primary fermented dough; (2) yeast activation, kneading of the primary fermented dough to a smooth surface, addition of activated yeast, secondary fermentation, and obtaining of a secondary fermented dough; (3) calendering, strip making, quantitative cutting, noodle boiling, and post-dipping metering packaging of the secondary fermented dough to obtain the fresh-keeping noodle. The dipping liquid comprises lactic acid, alcohol, and water. The alcohol plays a sterilization role, inhibits excessive water absorption of the noodles during the dipping process, and is beneficial to maintaining the toughness of the noodles. The lactic acid in the dipping liquid can adjust the pH and inhibit the growth of microorganisms in the noodles. The secondary fermentation consumes oxygen in the dough, forms a low-oxygen environment, inhibits the growth of spoilage bacteria, ensures the quality stability of the noodles during storage, and cooperatively improves the shelf life of the noodles.

Description

Technical Field

[0001] This invention belongs to the field of food processing technology, and in particular relates to a fresh-keeping noodle and its preparation process. Background Technology

[0002] Noodle products are a traditional food in my country. With the development of the times, the variety of noodle products has also increased. Among them, noodles are loved by consumers for their convenience. In particular, udon noodles and cart noodles are more popular than traditional dried noodles because of their chewy and smooth texture. However, as consumers have higher and higher requirements for instant food products, the demands for noodles in terms of convenience, functionality, and taste are increasing. How to stand out is a problem that manufacturers urgently need to solve.

[0003] In existing technologies, yeast is generally added to dough for fermentation. The carbon dioxide gas produced by the yeast creates various small pores in the dough, thus improving its flavor.

[0004] For example, CN11333741A discloses a *Saccharomyces cerevisiae* strain KXMR006, with accession number GDMCC No. 61665. This *Saccharomyces cerevisiae* strain KXMR006 exhibits strong fermentation power, good gas production, rapid fermentation speed, low acid production, strong environmental adaptability, and rapid reproduction. It also discloses a starter culture containing the *Saccharomyces cerevisiae* strain KXMR006, and the application of the *Saccharomyces cerevisiae* strain KXMR006 or the starter culture in the preparation of hollow noodles. This application utilizes *Saccharomyces cerevisiae* to accelerate fermentation and shorten fermentation time, but does not alter the texture or nutritional value of the noodles.

[0005] For example, CN109169765BA discloses a high-fiber bread fermentation process, including the following steps: S1, by weight, mix and stir 300-400 parts wheat flour, 60-80 parts oat flour, 30-50 parts rye flour, 10-15 parts white sugar, 350-435 parts water, 80-95 parts bread improver, 25-30 parts apple pulp, 4.6-7 parts dry yeast, and 8-15 parts lactic acid bacteria; S2, ferment the prepared dough at room temperature for 1-1.5 hours, and then ferment at a fermentation temperature of 6-10℃ for 12-15 hours. After extruding the dough, let it rest for 20-30 minutes; S3, mix 180-280g of wheat flour, 20-45g of oat flour, 15-25g of salt, 13-20g of white sugar, 55-60g of apple pulp, and 200-255g of water, then add this mixture to the dough from step S2 and mix again; S4, ferment the dough from step S3 at a fermentation temperature of 0-4℃ for 2-3 hours; S5, proof the dough from step S4 after its second fermentation at a proofing temperature of 27-45℃, a humidity of 80-85%, and a proofing time of 60-100 minutes. This application utilizes the synergistic fermentation of lactic acid bacteria and yeast to give the bread a unique flavor; however, the fermentation time is too long, requiring at least two days, making it unsuitable for industrial production.

[0006] In view of this, the present invention is hereby proposed. Summary of the Invention

[0007] The purpose of this invention is to provide a fresh-keeping noodle and its preparation process. The fresh-keeping noodle provided by this invention has a unique aroma and taste, and has a short fermentation time, resulting in a long shelf life.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] In a first aspect, embodiments of the present invention provide a process for preparing fresh-keeping noodles, comprising the following preparation steps:

[0010] (1) Activate selenium-enriched yeast, Lactobacillus helveticus and Acetobacter pasteurization, mix flour, flavor additives and activated selenium-enriched yeast, Lactobacillus helveticus and Acetobacter pasteurization, and carry out a first fermentation to obtain a first fermented dough.

[0011] (2) Activate the Pichia pastoris, then knead the first fermented dough until the surface is smooth, add the activated Pichia pastoris, and carry out a second fermentation to obtain a second fermented dough;

[0012] (3) The secondary fermented dough is rolled, cut into strips, cut into quantitative portions, cooked, soaked, and then metered and packaged to obtain fresh noodles.

[0013] In a preferred embodiment, in step (1), the selenium-enriched yeast is prepared using the following method:

[0014] Saccharomyces cerevisiae was inoculated into a liquid culture medium, sodium selenite stock solution was added, and after culturing and washing, selenium-enriched yeast was obtained.

[0015] In a preferred embodiment, the liquid culture medium is yeast extract peptone glucose medium, and the concentration of sodium selenite in the liquid culture medium is 10-30 mg / L.

[0016] In a preferred embodiment, the culture temperature is 25-35°C and the culture time is 18-24 hours.

[0017] In a preferred embodiment, in step (1), the activation temperature is 25-35°C and the time is 5-15 min.

[0018] In a preferred embodiment, in step (1), the mass ratio of the flour to the flavor additive is 100:(1-4).

[0019] In a preferred embodiment, in step (1), the amount of activated selenium-enriched yeast, based on live cells, is 1 × 10⁻⁶ per 100g of flour. 9 -2×10 11 The dosage of CFU, activated Lactobacillus helveticus, is 1×10⁻⁶. 9 -2×10 11 CFU, the dosage of activated *Acetobacter pasteurellosis* is 1×10⁻⁶. 9 -2×10 11 CFU.

[0020] In a preferred embodiment, in step (1), the temperature of the primary fermentation is 25-30°C and the time is 15-45 min.

[0021] This invention utilizes selenium-enriched yeast, *Lactobacillus helveticus*, and *Acetobacter pasteurization* to achieve a qualitative leap in dough structure. First, the dough undergoes a primary fermentation process using these three yeasts. The selenium-enriched yeast utilizes the sugars in the flour for fermentation and metabolism, primarily through glycolysis, breaking down glucose and other sugars to produce carbon dioxide gas and a small amount of alcohol. The carbon dioxide gas forms numerous tiny bubbles within the dough, causing it to gradually expand and laying the foundation for a loose, porous structure. While *Lactobacillus helveticus* does not primarily produce gas during fermentation, it breaks down some sugars and proteins in the flour, producing organic acids such as lactic acid, as well as small-molecule peptides and amino acids. The production of these substances regulates the dough's pH, making it more suitable for the growth and fermentation of the selenium-enriched yeast, indirectly helping to maintain the stability of yeast gas production and allowing the dough to expand steadily. Simultaneously, the small molecules produced also help improve the dough's extensibility and other physical properties, enabling it to better maintain its shape and contain gas during fermentation. Furthermore, *Acetobacter pastoris* is an aerobic bacterium that can utilize substances such as alcohol (produced by selenium-enriched yeast fermentation) and sugars present in the dough for oxidative metabolism, producing organic acids such as acetic acid. In this process, on the one hand, its growth and metabolic activities also consume oxygen, creating a relatively more favorable anaerobic environment for yeast fermentation, allowing the selenium-enriched yeast to better exert its gas-producing function; on the other hand, the produced acetic acid and other organic acids can work together with lactic acid and other substances produced by *Lactobacillus helveticus* to further regulate the pH value of the dough, bringing the dough's acid-base environment to a more balanced state conducive to the overall fermentation process, ensuring that the dough can continue to expand fully, making the internal structure of the pasta more porous.

[0022] This invention significantly enhances the nutritional value of dough by combining these three microbial communities. Selenium-enriched yeast, rich in selenium, is incorporated into the dough through fermentation, making it an excellent carrier of selenium. Selenium is an essential trace element with numerous health benefits, including antioxidant properties, enhanced immunity, and prevention of cardiovascular diseases. This allows fermented dough to not only meet dietary needs but also provide additional essential nutrients. Lactobacillus helveticus, a probiotic, survives in the dough during fermentation. Even after subsequent cooking processes (such as steaming and baking), some of the probiotics and their beneficial metabolites remain. When people consume these dough products, these probiotics can regulate the balance of the intestinal flora, promote intestinal health, enhance digestive function, and play a positive role in the health of the digestive system. The advantages of *Acetobacter pasteurellium* are that the acetic acid and other organic acids produced during its fermentation, as well as other active substances that may be involved in the metabolism, can help the human body digest and absorb nutrients in food to a certain extent. For example, it can promote the dissolution and absorption of minerals. Furthermore, acetic acid itself has certain antibacterial and bactericidal effects, which can also play a role in the storage of pasta and other products, thus indirectly ensuring the nutritional safety of food.

[0023] The three microbial communities in this invention contribute to the unique flavor of the dough. The small amount of alcohol produced during the fermentation of selenium-enriched yeast, along with volatile substances (such as esters) with distinctive aromas formed during its metabolism, imparts a unique fermented fragrance to the dough, giving it a rich yeast aroma and enhancing its flavor quality. Lactobacillus helveticus, due to its production of lactic acid and other organic acids, adds a subtle sourness to the dough. This sourness is not abrupt but rather blends harmoniously with other flavor compounds, making the flavor of the dough richer and more layered. Furthermore, the small-molecule peptides and amino acids produced by Lactobacillus helveticus metabolism also possess different flavor characteristics, further enriching the overall flavor of the dough, such as a milky or umami taste. The acetic acid produced by Acetobacter pasteurization imparts a distinct vinegar aroma to the dough, which intertwines and harmonizes with the fermented aroma produced by the yeast and the sour aroma from the lactobacillus. When these three elements work together, they create a complex and unique flavor combination, giving fermented pasta a distinctive texture and taste experience, unlike the simple flavor produced by fermentation with a single strain of bacteria.

[0024] Therefore, the present invention can significantly improve the texture, flavor, nutritional value and other properties of dough during a single fermentation.

[0025] In a preferred embodiment, the preparation method of the flavor additive in step (1) is as follows:

[0026] Steep yerba mate tea leaves in 80-100℃ water for 30-60 seconds, then dry and grind them to obtain a flavor additive.

[0027] In a preferred embodiment, the particle size of the flavor additive is 100-300 μm.

[0028] This invention incorporates yerba mate tea leaves as a flavoring additive into dough, accelerating fermentation and increasing its nutritional value. Yerba mate tea contains polyphenols, which have antioxidant properties and can regulate the redox potential within the dough to some extent, creating a more favorable environment for the fermentation of the aforementioned microorganisms. This facilitates better fermentation activities, accelerates fermentation, and ensures more complete dough fermentation. Furthermore, the coarse fiber and other components in yerba mate tea increase the dough's toughness and extensibility, making it less prone to cracking during fermentation and helping to maintain its shape and structure. The integrity of the dough structure allows fermented pasta to have a better appearance and taste. Mate tea itself contains polyphenols with a unique flavor and aroma. During dough fermentation, these flavor compounds infuse into the dough, adding a distinctive flavor and a richer taste profile to the fermented pasta. Furthermore, mate tea is rich in nutrients such as carbohydrates, proteins, fats, vitamins, minerals, and amino acids. Adding mate tea during dough fermentation allows these nutrients to be incorporated into the pasta, increasing its nutritional value and enabling people to ingest more beneficial components while consuming it.

[0029] In a preferred embodiment, in step (2), the activation temperature is 25-35°C and the time is 5-15 min.

[0030] In a preferred embodiment, in step (2), the temperature of the secondary fermentation is 15-25°C and the fermentation time is 4-8 hours.

[0031] In a preferred embodiment, in step (2), the amount of activated Pichia pastoris, based on live cells, is 1 × 10⁻⁶ per 100g of flour. 9 -2×10 11 CFU.

[0032] Based on the above technical solutions, this invention limits the secondary fermentation temperature to 5 to 15 degrees Celsius. At this temperature, the fermentation of selenium-enriched yeast, Lactobacillus helveticus, and Acetobacter pasteurella stops due to the low temperature, thus preventing the production of excessive lactic acid or acetic acid that would result in a sour dough taste. Furthermore, this invention utilizes Pichia pastoris for secondary fermentation. Under low-temperature conditions, the growth and metabolism of Pichia pastoris slow down. They have more time to carry out various biochemical reactions meticulously, producing a richer variety and more suitable amount of flavor metabolites, rather than fermenting rapidly and relatively extensively at high temperatures, producing only relatively conventional and large quantities of single major metabolites. When fermenting at low temperatures, Pichia pastoris produces volatile compounds such as alcohols and esters. These substances endow the dough with a unique fermentation aroma, giving the prepared pasta a rich fragrance that can stimulate people's sense of smell and taste, increase appetite, and further enhance the aroma of the dough. Moreover, these alcohol and ester aromas further mix with the phenolic aroma of yerba mate tea to form a unique fragrance. In addition, due to the slow fermentation speed at low temperatures, as mentioned above, yerba mate tea further increases the fermentation speed of Pichia pastoris.

[0033] In a preferred embodiment, in step (3), the preservative solution used for immersion comprises: 1%-2% lactic acid, 10%-20% alcohol, and the remainder being water, by weight.

[0034] In a preferred embodiment, in step (3), the immersion temperature is 20-30°C and the immersion time is 40-60 seconds.

[0035] In this invention, the alcohol in the preservative solution not only has a sterilizing effect, but also inhibits the noodles from absorbing too much water during soaking, which would cause them to become soft and help maintain their chewy texture. Furthermore, the lactic acid in the preservative solution can regulate the pH and inhibit the growth of microorganisms in the noodles. In addition, the Pichia pasta, which undergoes secondary fermentation, consumes oxygen in the dough during the early stages of fermentation, creating a low-oxygen environment. This also helps inhibit the growth of aerobic spoilage bacteria, further ensuring the quality stability of the pasta during storage and reducing the possibility of spoilage. In other words, this synergistically improves the shelf life of the noodles.

[0036] Secondly, embodiments of the present invention provide a fresh-keeping noodle obtained by the preparation process of the fresh-keeping noodle described above.

[0037] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0038] 1. This invention utilizes selenium-enriched yeast, *Lactobacillus helveticus*, and *Acetobacter pasteurella* to achieve a qualitative leap in dough structure. Firstly, the invention employs these three yeasts for a primary fermentation of the dough. The selenium-enriched yeast utilizes the sugars in the flour for fermentation and metabolism, primarily through glycolysis to break down glucose and other sugars, producing carbon dioxide gas and a small amount of alcohol. The carbon dioxide gas forms numerous tiny bubbles within the dough, causing it to gradually expand and laying the foundation for a loose, porous structure. While *Lactobacillus helveticus* does not primarily produce gas during fermentation, it decomposes some sugars and proteins in the flour, producing lactic acid and other organic acids, as well as small-molecule peptides and amino acids. The production of these substances regulates the pH of the dough, making it more suitable for the growth and fermentation of the selenium-enriched yeast, indirectly helping to maintain the stability of yeast gas production and allowing the dough to expand steadily. Simultaneously, the small-molecule substances produced also help improve the dough's extensibility and other physical properties, enabling it to better maintain its shape and contain gas during fermentation. Furthermore, *Acetobacter pastoris* is an aerobic bacterium that can utilize substances such as alcohol (produced by selenium-enriched yeast fermentation) and sugars present in the dough for oxidative metabolism, producing organic acids such as acetic acid. In this process, on the one hand, its growth and metabolic activities also consume oxygen, creating a relatively more favorable anaerobic environment for yeast fermentation, allowing the selenium-enriched yeast to better exert its gas-producing function; on the other hand, the produced acetic acid and other organic acids can work together with lactic acid and other substances produced by *Lactobacillus helveticus* to further regulate the pH value of the dough, bringing the dough's acid-base environment to a more balanced state conducive to the overall fermentation process, ensuring that the dough can continue to expand fully, making the internal structure of the pasta more porous.

[0039] This invention significantly enhances the nutritional value of dough by combining these three microbial communities. Selenium-enriched yeast, rich in selenium, is incorporated into the dough through fermentation, making it an excellent carrier of selenium. Selenium is an essential trace element with numerous health benefits, including antioxidant properties, enhanced immunity, and prevention of cardiovascular diseases. This allows fermented dough to not only meet dietary needs but also provide additional essential nutrients. Lactobacillus helveticus, a probiotic, survives in the dough during fermentation. Even after subsequent cooking processes (such as steaming and baking), some of the probiotics and their beneficial metabolites remain. When people consume these dough products, these probiotics can regulate the balance of the intestinal flora, promote intestinal health, enhance digestive function, and play a positive role in the health of the digestive system. The advantages of *Acetobacter pasteurellium* are that the acetic acid and other organic acids produced during its fermentation, as well as other active substances that may be involved in the metabolism, can help the human body digest and absorb nutrients in food to a certain extent. For example, it can promote the dissolution and absorption of minerals. Furthermore, acetic acid itself has certain antibacterial and bactericidal effects, which can also play a role in the storage of pasta and other products, thus indirectly ensuring the nutritional safety of food.

[0040] The three microbial communities in this invention contribute to the unique flavor of the dough. The small amount of alcohol produced during the fermentation of selenium-enriched yeast, along with volatile substances (such as esters) with distinctive aromas formed during its metabolism, imparts a unique fermented fragrance to the dough, giving it a rich yeast aroma and enhancing its flavor quality. Lactobacillus helveticus, due to its production of lactic acid and other organic acids, adds a subtle sourness to the dough. This sourness is not abrupt but rather blends harmoniously with other flavor compounds, making the flavor of the dough richer and more layered. Furthermore, the small-molecule peptides and amino acids produced by Lactobacillus helveticus metabolism also possess different flavor characteristics, further enriching the overall flavor of the dough, such as a milky or umami taste. The acetic acid produced by Acetobacter pasteurization imparts a distinct vinegar aroma to the dough, which intertwines and harmonizes with the fermented aroma produced by the yeast and the sour aroma from the lactobacillus. When these three elements work together, they create a complex and unique flavor combination, giving fermented pasta a distinctive texture and taste experience, unlike the simple flavor produced by fermentation with a single strain of bacteria.

[0041] 2. This invention incorporates yerba mate tea leaves as a flavoring additive into the dough, accelerating fermentation and increasing its nutritional value. Yerba mate tea leaves contain polyphenols, which have antioxidant properties and can regulate the redox potential within the dough to some extent, creating a more favorable environment for the fermentation of the aforementioned microorganisms. This helps the microorganisms to better carry out fermentation activities, accelerating the fermentation process and ensuring more complete dough fermentation. Furthermore, the coarse fiber and other components in yerba mate tea leaves can increase the dough's toughness and extensibility, making it less prone to cracking during fermentation and helping to maintain the dough's shape and elasticity. The structural integrity of yerba mate gives fermented pasta a better appearance and texture. Yerba mate itself contains polyphenols with a unique flavor and aroma. During dough fermentation, these flavor compounds infuse into the dough, adding a distinctive flavor and a richer taste profile to the fermented pasta. Furthermore, yerba mate is rich in nutrients such as carbohydrates, proteins, fats, vitamins, minerals, and amino acids. Adding yerba mate during dough fermentation allows these nutrients to be incorporated into the pasta, increasing its nutritional value and enabling people to ingest more beneficial components while consuming it.

[0042] 3. This invention limits the temperature of the secondary fermentation to prevent the production of excessive lactic or acetic acid, which would result in a sour taste in the dough. This invention utilizes Pichia pastoris for secondary fermentation. Under low-temperature conditions, the growth and metabolism of Pichia pastoris slow down. They have more time to carry out various biochemical reactions meticulously, producing a richer variety and more suitable amount of flavor metabolites, rather than the rapid and relatively extensive fermentation at high temperatures, which only produces more conventional and numerous single major metabolites. During low-temperature fermentation, Pichia pastoris produces volatile compounds such as alcohols and esters. These substances endow the dough with a unique fermented aroma, giving the prepared bread a rich fragrance that stimulates the sense of smell and taste, increases appetite, and further enhances the aroma of the dough. Furthermore, these alcohol and ester aromas further mix with the phenolic aroma of yerba mate tea, forming a unique fragrance. In addition, due to the slow fermentation speed at low temperatures, as mentioned earlier, yerba mate tea further increases the fermentation speed of Pichia pastoris.

[0043] 4. The alcohol in the preservative solution of this invention not only has a sterilizing effect, but also inhibits the noodles from absorbing too much water during soaking, which would cause them to become soft and help maintain their chewy texture. In addition, the lactic acid in the preservative solution can regulate the pH and inhibit the growth of microorganisms in the noodles. Furthermore, the Pichia pasta, which is undergoing secondary fermentation, consumes oxygen in the dough during the early stage of fermentation, creating a low-oxygen environment. This also helps to inhibit the growth of aerobic spoilage bacteria, further ensuring the quality stability of the pasta during storage and reducing the possibility of spoilage. In other words, it synergistically improves the shelf life of the noodles. Detailed Implementation

[0044] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] Unless otherwise specified, all reagents mentioned in this embodiment are commercially available.

[0046] The brewing yeast, with product number GDMCC No. 62110, was purchased from Angel Yeast Co., Ltd.

[0047] Lactobacillus helveticus, GDMCC No. 62536, was purchased from Shanghai Jimi Biotechnology Co., Ltd.

[0048] Acetobacter pasteurellum, with the code GDMCC No. 62536, was purchased from Shanghai Yiyan Biotechnology Co., Ltd.

[0049] Pichia pastoris, product number CGMCC No.17607, was purchased from Thermo Fisher Scientific.

[0050] Example 1

[0051] This embodiment provides a preparation process for fresh-keeping noodles, including the following preparation steps:

[0052] (1) Inoculate brewer's yeast into yeast extract peptone glucose medium, add sodium selenite mother liquor to make the concentration of sodium selenite in the medium 15mg / L, culture at 30℃ for 20h and then wash to obtain selenium-enriched yeast. Activate selenium-enriched yeast, Lactobacillus helveticus and Acetobacter pasteurellium at 30℃ for 10min. Mix high-gluten flour purchased from Jinshahe, flavor additives and activated selenium-enriched yeast, Lactobacillus helveticus and Acetobacter pasteurellium into dough and carry out a first fermentation at 30℃ for 35min to obtain a first fermented dough.

[0053] The mass ratio of flour to flavor additives is 100:2, and the amount of activated selenium-enriched yeast, calculated as live cells, is 1.9 × 10⁻⁶ per 100g of flour. 10 The dosage of CFU, activated Lactobacillus helveticus, is 2.3 × 10⁻⁶. 10 The dosage of CFU and activated Acetobacter pasteurellium was 1.2 × 10⁻⁶. 9 CFU;

[0054] The preparation method of the flavor additive is as follows:

[0055] Yerba mate leaves are soaked in 95°C water for 60 seconds, then removed, dried, ground, and sieved until the particle size is less than 200μm to obtain a flavor additive.

[0056] (2) Activate the Pichia pastoris at 30℃ for 10 minutes. Then knead the first-fermented dough until smooth, add the activated Pichia pastoris, and the amount of activated Pichia pastoris per 100g of flour, based on live cells, is 1.8 × 10⁻⁶. 11 CFU is used for a second fermentation at a temperature of 15℃ for 6 hours to obtain a second-fermented dough.

[0057] (3) The second fermented dough is rolled, cut into strips, cut into quantitative portions, cooked, soaked, and then packaged to obtain fresh noodles;

[0058] The preservative solution used for immersion includes, by weight, 1% food-grade lactic acid, 10% food-grade alcohol, and the remainder water; the immersion temperature is 25°C, and the immersion time is 50 seconds.

[0059] Example 2

[0060] This embodiment provides a preparation process for fresh-keeping noodles, including the following preparation steps:

[0061] (1) Inoculate brewer's yeast into yeast extract peptone glucose medium, add sodium selenite mother liquor to make the concentration of sodium selenite in the medium 15mg / L, culture at 30℃ for 20h and then wash to obtain selenium-enriched yeast. Activate selenium-enriched yeast, Lactobacillus helveticus and Acetobacter pasteurellium at 30℃ for 10min. Mix high-gluten flour purchased from Jinshahe, flavor additives and activated selenium-enriched yeast, Lactobacillus helveticus and Acetobacter pasteurellium into dough and carry out a first fermentation at 30℃ for 35min to obtain a first fermented dough.

[0062] The mass ratio of flour to flavor additives is 100:3, and the amount of activated selenium-enriched yeast, calculated as live cells, is 1.8 × 10⁻⁶ per 100g of flour. 10 The dosage of CFU, activated Lactobacillus helveticus, is 2.3 × 10⁻⁶. 10 The dosage of CFU and activated Acetobacter pasteurellium was 1.1 × 10⁻⁶. 9 CFU;

[0063] The preparation method of the flavor additive is as follows:

[0064] Yerba mate leaves are soaked in 95°C water for 60 seconds, then removed, dried, ground, and sieved until the particle size is less than 200μm to obtain a flavor additive.

[0065] (2) Activate the Pichia pastoris at 30℃ for 10 minutes. Then knead the first-fermented dough until smooth, add the activated Pichia pastoris, and the amount of activated Pichia pastoris per 100g of flour, based on live cells, is 1.9 × 10⁻⁶. 11 CFU is used for a second fermentation at a temperature of 15℃ for 6 hours to obtain a second-fermented dough.

[0066] (3) The second fermented dough is rolled, cut into strips, cut into quantitative portions, cooked, soaked, and then packaged to obtain fresh noodles;

[0067] The preservative solution used for immersion includes, by weight, 1% food-grade lactic acid, 10% food-grade alcohol, and the remainder water; the immersion temperature is 25°C, and the immersion time is 50 seconds.

[0068] Comparative Example 1

[0069] Compared to Example 1, the only difference is that, except for the absence of selenium-enriched yeast, the amount of *Lactobacillus helveticus* used per 100g of flour is 3.25 × 10⁻⁶. 10 The dosage of CFU and Acetobacter pasteurellium was 1.07 × 10⁻⁶. 10 CFU.

[0070] Comparative Example 2

[0071] Compared to Example 1, the only difference is that, except for the absence of *Lactobacillus helveticus*, the amount of selenium-enriched yeast used per 100g of flour is 3.05 × 10⁻⁶. 10 CFU, the dosage of *Acetobacter pastoris* was 1.27 × 10⁻⁶. 10 CFU.

[0072] Comparative Example 3

[0073] Compared to Example 1, the only difference is that, except for the absence of *Acetobacter pasteurella*, the amount of selenium-enriched yeast used per 100g of flour is 1.96 × 10⁻⁶. 10 The dosage of CFU and Lactobacillus helveticus is 2.36 × 10⁻⁶. 10 CFU.

[0074] Comparative Example 4

[0075] Compared to Example 1, the only difference is that no secondary fermentation is performed, and the primary fermentation time is changed to 6 hours.

[0076] Comparative Example 5

[0077] The only difference from Example 1 is that no flavor additives are added.

[0078] Comparative Example 6

[0079] The only difference from Example 1 is that the preservative solution in step (3) is replaced with an equal amount of water.

[0080] Performance testing

[0081] Considering health, reliability, and concern for the experiment, 50 people were selected and trained on the purpose of the experiment and the evaluation method. The noodles made in the embodiments of the present invention and Comparative Example 6 were cooked in sequence, and then sensory evaluation was carried out. The order of tasting was as follows: after eating the first sample, write an evaluation of the sample, then rinse your mouth with water and then eat the next sample for evaluation.

[0082] The sensory evaluation here assesses the overall palatability, flavor, taste, chewiness, and chewiness of each embodiment and comparative example using a 5-point rating scale (5 points - very good; 4 points - good; 3 points - average; 2 points - poor; 1 point - very poor). The results are shown in Table 1.

[0083] Next, the noodles prepared in Examples 1 and 2, as well as Comparative Examples 1 to 6, were refrigerated at a temperature of 2°C. In the refrigeration test, the appearance of mold indicated spoilage; each test group was tested in parallel four times. The average spoilage time for each group was then calculated, and the results are shown in Table 1.

[0084] Table 1 Performance Test Results

[0085]

[0086]

[0087] The performance test results above show that the taste, flavor, and chewy texture of the noodles in Examples 1-2 are the most popular, especially Example 2, which has the most outstanding overall performance. This is mainly due to the synergistic effect between the various strains of bacteria in this invention, as well as the enhanced texture and aroma of the noodles through primary and secondary fermentation. The comparative examples, however, did not employ the necessary technical solutions, resulting in significantly inferior performance compared to the examples. This further demonstrates the irreplaceable nature of the specific technical solution in this application for achieving the desired technical effect and solving the technical problem.

[0088] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A process for preparing fresh-keeping noodles, characterized in that, The preparation steps include the following: (1) Activate selenium-enriched yeast, Lactobacillus helveticus and Acetobacter pasteurization, mix flour, flavor additives and activated selenium-enriched yeast, Lactobacillus helveticus and Acetobacter pasteurization, and carry out a first fermentation to obtain a first fermented dough. The temperature of the first fermentation is 25-30℃ and the time is 15-45min. (2) Activate the Pichia pastoris, then knead the first fermented dough until the surface is smooth, add the activated Pichia pastoris, and carry out a second fermentation to obtain a second fermented dough. The temperature of the second fermentation is 15℃ and the fermentation time is 6h. (3) The secondary fermented dough is rolled, cut into strips, cut into quantitative portions, cooked, and then soaked and packaged to obtain fresh noodles. The fresh liquid used for soaking includes: 1%-2% lactic acid, 10%-20% alcohol, and the remainder is water by weight. In step (1), the selenium-enriched yeast is prepared using the following method: Saccharomyces cerevisiae was inoculated into a liquid culture medium, sodium selenite stock solution was added, and after culturing and washing, selenium-enriched yeast was obtained. The liquid culture medium is yeast extract peptone glucose medium, and the concentration of sodium selenite in the liquid culture medium is 10-30 mg / L; In step (1), the amount of activated selenium-enriched yeast used is 1×10⁻⁶ per 100g of flour, based on live cells. 9 -2×10 11 The dosage of CFU, activated Lactobacillus helveticus, is 1×10⁻⁶. 9 -2×10 11 CFU, the dosage of activated *Acetobacter pasteurellosis* is 1×10⁻⁶. 9 -2×10 11 CFU; In step (1), the preparation method of the flavor additive is as follows: soak yerba mate tea leaves in water at 80-100℃ for 30-60 seconds, then dry and grind them to obtain the flavor additive. In step (2), the amount of activated Pichia pastoris relative to 100g of flour, calculated as live cells, is 1×10⁻⁶. 9 -2×10 11 CFU.

2. The preparation process of the fresh-keeping noodles according to claim 1, characterized in that, The culture temperature is 25-35℃, and the culture time is 18-24h.

3. The preparation process of the fresh-keeping noodles according to claim 1, characterized in that, In step (1), the activation temperature is 25-35℃ and the time is 5-15 min; And / or, in step (1), the mass ratio of the flour to the flavor additive is 100:(1-4).

4. The preparation process of the fresh-keeping noodles according to claim 3, characterized in that, The particle size of the flavor additive is 100-300 μm.

5. The preparation process of the fresh-keeping noodles according to claim 1, characterized in that, In step (2), the activation temperature is 25-35℃ and the time is 5-15min.

6. The preparation process of the fresh-keeping noodles according to claim 1, characterized in that, In step (3), the immersion temperature is 20-30℃ and the immersion time is 40-60 seconds.

7. A fresh-keeping noodle obtained by the preparation process of the fresh-keeping noodle as described in any one of claims 1-6.

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