Medium-temperature fermentation, alkali-addition compound ingredients, improved dough, sourdough, quick-frozen raw dough preparation method for xiaolongbao (soup dumplings)

Abstract

This invention discloses a method for preparing frozen xiaolongbao (soup dumpling) embryos using a medium-temperature fermented, alkali-treated compound dough, relating to the fields of food processing and frozen rice and noodle products. The method involves mixing an independent seed dough with medium-gluten wheat flour, water, and white sugar, and fermenting it at 15.0±0.5℃ for 12–14 hours until the volume is 2.0–2.5 times that before fermentation and the pH value is 4.0–4.5. After fermentation, an edible alkali solution is added during the alkali-treating process. Within 1–3 minutes of adding the alkali, a compound aqueous solution prepared from glucono-δ-lactone, salt, maltodextrin, and trehalose is added to adjust the dough pH to 6.2–6.6. After the compound aqueous solution is added, the alkali-treated dough is shaped into xiaolongbao embryos and then quick-frozen directly or after proofing, depending on the shaping method. The embryos are quick-frozen until the center temperature does not exceed -18℃, and are used to prepare quick-frozen xiaolongbao embryos that can be directly steamed.

Description

Technical Field

[0001] This invention relates to the field of food processing and quick-frozen rice and noodle products, specifically to a method for preparing quick-frozen steamed buns using independently prepared and passed seed dough, fermented under medium temperature conditions, and with glucono-δ-lactone, salt, maltodextrin and trehalose added during the alkali-beating stage after fermentation to regulate the pH value of the dough and improve the quality of the dough after quick-freezing. Background Technology

[0002] Using sourdough for fermentation can impart a richer fermented flavor to dough products. However, sourdough typically contains various microorganisms such as yeast and lactic acid bacteria, and its microbial composition and metabolic state are easily affected by factors such as cultivation methods, fermentation temperature, cultivation time, and production ingredients. In continuous industrial production, some traditional processes directly retain sourdough starter from the production dough for further propagation. However, production dough often contains auxiliary ingredients such as sugars, and long-term recycling can easily alter the sourdough starter's cultivation environment, causing fluctuations in the microbial community ratio, acid production rate, and fermentation activity. This leads to inconsistencies in fermentation time, acidity, and expansion between different batches of dough, hindering the standardized control of the sourdough fermentation process. Furthermore, the process of reusing production dough for propagation results in prolonged fermentation time, decreased final pH, and reduced volume ratio.

[0003] Meanwhile, fermentation temperature has a significant impact on the fermentation cycle and dough quality of the sourdough starter. At lower temperatures, the metabolic rate of yeast and lactic acid bacteria is slower, requiring a longer time to reach the desired fermentation state, which is not conducive to production scheduling and continuous processing. Although higher temperatures can shorten the fermentation time, they can easily lead to problems such as excessively rapid acid production, rapid changes in dough acidity, and difficulty in stabilizing the fermentation state. Under the same volume ratio and pH endpoint conditions, fermentation at 4–6℃ requires a longer time, while fermentation at 20–25℃ is faster but acidity and batch stability are more difficult to control. Therefore, how to achieve a balance between fermentation cycle, sourdough flavor, and production stability remains a problem that needs to be solved in the industrial production of frozen sourdough starter products.

[0004] Furthermore, fermented dough typically possesses a certain degree of acidity, necessitating the adjustment of its pH through alkali addition. Traditional alkali addition methods, relying primarily on mechanical mixing of edible alkali with the dough, often result in inconsistent dispersion and uniformity of the alkali within the dough. This can lead to localized areas with higher alkalinity within a short period, causing uneven pH distribution within the dough and affecting gluten development and dough color. When only edible alkali is added, significant pH differences exist between different sampling locations, accompanied by localized hardening, poor proofing stability, and an increased incidence of yellow spots after frozen storage. Therefore, achieving overall dough pH adjustment while minimizing localized pH fluctuations and maintaining a suitable gluten structure are key challenges that need further resolution in the processing of sourdough steamed buns.

[0005] For quick-frozen raw xiaolongbao (soup dumplings), the shaped dough still needs to undergo rapid freezing, low-temperature storage, and re-steaming. Ice crystals formed during freezing, moisture migration, and starch retrogradation during frozen storage can all affect the gluten network and dough structure, leading to problems such as a dry, hard, wrinkled, and cracked dough, as well as decreased elasticity after re-steaming. In existing processes, some sugars, water-retaining agents, or dough improvers are usually added in the early dough mixing stage. However, for long-term sourdough fermentation processes, some components may be utilized by microorganisms during fermentation, thus affecting their actual effect in the subsequent quick-freezing stage. The application also points out that gluten protection, moisture retention, and dough anti-aging properties during quick-freezing and frozen storage are important factors affecting the quality of re-steamed dumplings.

[0006] Therefore, the existing process for preparing frozen xiaolongbao using old dough still has problems such as insufficient stability of the seed dough in continuous passaging, difficulty in balancing fermentation cycle and fermentation quality, uneven local pH of the dough during alkali addition, and the tendency of the dough to become dry, hard, wrinkled, or cracked after quick-freezing and storage. It is necessary to further improve the old dough seed culture method, fermentation conditions, alkali addition adjustment method, and dough quality control before quick-freezing in order to improve the stability and product quality consistency of frozen xiaolongbao during continuous production. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a method for preparing frozen xiaolongbao (soup dumplings) using a starter dough with improved dough quality through medium-temperature fermentation, alkali addition, and compounding of ingredients. This method involves fermentation at 15.0±0.5℃, followed by the addition of glucono-delta-lactone, salt, maltodextrin, and trehalose during the alkali addition stage after fermentation. This process regulates the pH value of the dough, improving its color, texture, and shaping stability after quick-freezing and frozen storage.

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

[0009] A method for preparing frozen xiaolongbao (soup dumplings) using a medium-temperature fermentation, alkali-addition, compounding, pH-buffered dough modification, and old dough preparation includes the following steps:

[0010] S1. Mix the independent seed dough, production medium-gluten wheat flour, water and white sugar to obtain the production dough;

[0011] S2. Ferment the dough at a medium temperature of 14.5-15.5℃ for 12-14 hours until the volume reaches 2.0-2.5 times the volume before fermentation and the pH value is 4.0-4.5 to obtain fermented dough. No glucono-δ-lactone, trehalose, maltodextrin and salt are added during the fermentation process.

[0012] S3. During the mixing of the fermented dough, add an edible alkali solution and a compound aqueous solution. The compound aqueous solution contains glucono-δ-lactone, trehalose, maltodextrin and salt to adjust the pH of the dough to 6.2-6.6, thus obtaining an alkali-adjusted dough.

[0013] S4. The alkaline dough is made into xiaolongbao (soup dumpling) embryos. The xiaolongbao embryos are placed in a quick-freezing environment directly or after proofing until the center temperature of the xiaolongbao embryos is not higher than -18℃.

[0014] Furthermore, based on the mass of the medium-gluten wheat flour used in production, the amount of the independent seed dough is 10%–20%, the total water content is 50%–60%, the amount of white sugar is 1%–1.2%, the amount of trehalose is 1%–1.5%, the amount of maltodextrin is 1%–1.5%, the amount of salt is 0.36%–0.40%, the amount of edible alkali is 0.8%–1.1%, and the amount of glucono-δ-lactone is 0.6%–0.65%.

[0015] The total amount of water added includes the water used for kneading the dough in step S1, the water used for the edible alkali solution in step S3, and the water used for the compound solution, but does not include the water contained in the individual seed dough itself.

[0016] Furthermore, the maltodextrin, trehalose, salt, and glucono-δ-lactone are pre-mixed and prepared into a compound aqueous solution, which is added to the fermented dough during the alkali-addition process in step S3 after the dough has completed medium-temperature fermentation.

[0017] Furthermore, in step S3, the edible alkali is dissolved in water at a temperature of 30-40°C, accounting for 3%-3.5% of the mass of the medium-gluten wheat flour used in production, to prepare the edible alkali aqueous solution. Additionally, the glucono-δ-lactone, trehalose, maltodextrin, and salt are dissolved in water at a temperature of 30-40°C, accounting for 3%-3.5% of the mass of the medium-gluten wheat flour used in production, to prepare the compound aqueous solution.

[0018] Furthermore, in step S3, while stirring the fermented dough, the edible alkali solution is added evenly first, and the compound aqueous solution is added evenly within 1 to 3 minutes after the addition of the edible alkali solution begins. After the compound aqueous solution is added, stirring continues for 5 to 8 minutes to make the pH value of the alkali-adjusted dough 6.3 to 6.5.

[0019] Furthermore, the initial preparation method of the independent seed dough is as follows: based on the mass of medium gluten wheat flour, add 75% to 85% water, 10% to 16% koji and 20% to 30% rice wine and mix evenly, then activate at 26 to 30°C for 10 to 14 hours.

[0020] Furthermore, the method for passage of the independent seed dough is as follows: 25-35g of mature independent seed dough is taken as the next generation inoculum. Medium-gluten wheat flour is added at a mass ratio of 1:10 to 1:17 between the inoculum and the added medium-gluten wheat flour. Water is added based on the mass of the added medium-gluten wheat flour. The dough is cultured at 14.5-15.5℃ until mature. It is passaged for 6-10 generations until the dough volume reaches 2.0-2.5 times that before cultivation and the pH value is 4.0-4.5. No white sugar, trehalose, glucono-δ-lactone, maltodextrin, or salt are added during the passage process, and the dough is not taken back from the production dough. The mature independent seed dough is refrigerated at -5 to 0℃ and rejuvenated every 7-10 days according to the above-mentioned feed composition.

[0021] Furthermore, the relative humidity of fermentation in step S2 is 75% to 82%, and fermentation ends when the volume of the produced dough reaches 2.0 to 2.3 times the volume before fermentation and the pH value is 4.2 to 4.5.

[0022] Furthermore, in step S4, the dough is formed by hand. The alkali-adjusted dough is divided into 13-17g portions, which are then wrapped with 11-15g of filling to obtain a single xiaolongbao embryo weighing 24-32g. The hand-forming is carried out at 23-27℃ and 70%-80% relative humidity. The xiaolongbao embryos are not proofed and are formed within 20-30 minutes after the addition of the compound aqueous solution and then placed in the quick-freezing environment.

[0023] Furthermore, in step S4, machine forming is used to divide the alkali-adjusted dough into 13-17g portions, which are then made into wrappers and filled with 11-15g of filling to obtain a single xiaolongbao embryo weighing 24-32g. The machine forming is carried out at 23-27℃ and 70%-80% relative humidity, and the forming is completed within 8-12 minutes from the addition of the compound aqueous solution. Afterward, the xiaolongbao embryos are proofed for 35-45 minutes and then placed in the quick-freezing environment.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] Batch stability: Independent seed dough culture results in smaller fluctuations in fermentation time, final pH value, and dough expansion state during continuous subculturing, which is beneficial to improving the stability of continuous production.

[0026] Flavor Enhancement: Under medium temperature conditions of 15℃, the metabolism of the old dough complex microbial community is stable, which is conducive to the accumulation of flavor esters such as ethyl acetate and ethyl lactate, giving the dough a soft fruity and milky flavor. The old dough flavor is rich, soft and mellow, without any sharp sour taste.

[0027] The dough is white and tender: Gluconolactone (GDL) is added during the alkali-mixing stage to buffer the pH, preventing a sudden spike in dough pH, ​​reducing localized excessive alkali concentration, and lowering the probability of yellowing and alkali spots on the dough. The dough is whiter and retains its color well after quick-freezing, with a lower incidence of yellow spots. It stabilizes the pH, balancing fluctuations in the acidity of the starter dough, ensuring consistent product quality and facilitating standardized production. It weakens the pungent alkali smell while preserving the pure aroma of the starter dough. It is resistant to quick-freezing; the buffer system reduces aging, shrinkage, and wrinkling of the dough after long-term freezing. The reaction is gentle and slow; it does not generate gas rapidly during kneading and pressing, and does not interfere with the shaping of the buns.

[0028] Excellent freeze-drying stability: Adding maltodextrin aqueous solution during the alkali-mixing stage buffers the pH, weakens the irritation of edible alkali, balances the dough's acidity and alkalinity, and works synergistically with glucono-delta-lactone to form a buffer system, locking in moisture. Long-term storage at -18℃ reduces moisture loss, alleviates dryness and hardening of the dough, improves dough texture, making it smoother and easier to press out a glossy finish, and reduces the probability of shrinkage after steaming. Maltodextrin is not a sweetener; its sweetness is extremely low, almost imperceptible, and it does not alter the original flavor of the xiaolongbao. Adding trehalose aqueous solution during the alkali-mixing stage avoids the consumption during prolonged fermentation. Traditionally, trehalose is added during dough mixing, and fermentation for over ten hours causes yeast and lactic acid bacteria to consume large amounts of trehalose, resulting in a reduced effective content by the time of freeze-drying. When alkali is added, trehalose is hardly consumed, protecting the gluten protein. During quick-freezing, it reduces the impact of ice crystal formation and water migration on the gluten network structure. Trehalose coats the gluten, reducing ice crystal damage, resisting aging, preventing shrinkage and wrinkles. After 30 days of quick-freezing, the steamed dough remains soft and does not easily dry out or collapse. This improves the softness and anti-aging properties of the dough after freezing. The sweetness is very mild and will not interfere with the flavor of the fresh meat soup dumplings. It fully penetrates the gluten. After 30 days of freezing and re-steaming, there is no obvious dryness, shrinkage, or cracking, and the soup retention rate is ≥85%.

[0029] Improved quality and texture of steamed bun dough: Adding salt solution during the alkali-beating stage tightens the gluten network, increases dough elasticity, makes the buns less prone to breaking or collapsing during shaping, enhances dough support, prevents collapse during the second proofing, reduces shrinkage after steaming, brings out the base flavor, enhances the freshness of the meat filling, and results in a chewy texture. The dough also has better elasticity, is less prone to gluten breakage during repeated pressing, and is easier to achieve a smooth, glossy texture.

[0030] Production efficiency is controllable: fermentation at 15℃ for 12-14 hours can achieve overnight fermentation and production the next day, balancing flavor and efficiency, which is superior to the deep low temperature process of 4-6℃ for several days.

[0031] Strong pH buffering capacity: The pH value of the dough drifts by ≤0.3 units during frozen storage, which is significantly better than conventional processes. Attached Figure Description

[0032] Figure 1This is a flowchart of a method for preparing xiaolongbao (soup dumplings) using a medium-temperature fermentation and alkali-adding compound dough improved with old dough and quick-frozen raw dough, according to the present invention. Detailed Implementation

[0033] The technical solutions of the present invention will now be described in detail with reference to the accompanying drawings.

[0034] like Figure 1 As shown, this embodiment provides a method for preparing frozen raw dough steamed buns, including independently preparing seed dough, fermenting at a medium temperature of 15.0±0.5℃, and adding a compound aqueous solution of salt, maltodextrin, trehalose and glucono-δ-lactone during the alkali-addition stage to adjust the pH value of the dough.

[0035] The following embodiments are used to illustrate the technical solution of the present invention and are not intended to limit the scope of protection of the present invention. Unless otherwise specified, all raw materials are food-grade raw materials that meet the corresponding food safety standards, and all temperatures refer to the actual measured temperature of the material or environment.

[0036] Definition and Measurement Method

[0037] The term "independent seed dough" as used in this instruction manual refers to dough prepared and passaged in a separate container. Production dough refers to dough that has completed kneading but has not yet completed intermediate-temperature fermentation; fermented dough refers to dough that has reached the specified volume and pH endpoint; alkali-adjusted dough refers to dough that has completed the addition and kneading of edible alkali, salt, maltodextrin, trehalose, and glucono-delta-lactone.

[0038] Unless otherwise stated, all parts by weight are based on 100 parts of medium-gluten wheat flour used in production. Total water added includes water for kneading, water for compounding solutions, and water for edible alkali solutions, but does not include the water contained in the individual seed dough itself.

[0039] The method for determining the pH value of dough is as follows: Take 10g of the dough to be tested, homogenize it at 25℃ for 2 minutes, let it stand for 1 minute, and then measure it using a pH meter calibrated with a standard buffer solution. The pH value of fermented dough is measured after step S2 and before step S3; the pH value of alkali-adjusted dough is measured within 20 minutes after the mixing in step S3.

[0040] Example:

[0041] This embodiment uses 1000g of medium-gluten wheat flour, 150g of individually seeded dough, 540g of total water, 10g of white sugar, 10g of trehalose, 10g of maltodextrin with a glucose equivalent of 10, 4g of salt, 10g of baking soda, and 6g of glucono-δ-lactone. Of the total 540g of water, 30g is used to prepare a mixed solution, 30g is used to prepare an aqueous solution of baking soda, and the remaining 480g is used as water for kneading the dough.

[0042] Includes the following steps:

[0043] Preparation of Independent Seed Dough: Mix 150g of medium-gluten wheat flour, 120g of water, 20g of yeast starter, and 40g of rice wine evenly (in this process, rice wine serves as the substrate for the starter culture, providing fermentable sugars and a small amount of yeast; combined with yeast starter, it is used to domesticate and stabilize the old dough's complex microbial community). Activate at 28℃ for 12 hours. After initial activation, take 30g of the mature independent seed dough as inoculum for the next generation, and add feed at a ratio of 500g of medium-gluten wheat flour to water of 100:60, and culture at 15.0±0.5℃; after maturation, take another 30g as inoculum for the next generation, add feed at the same flour-to-water ratio, and continue subculturing for 6 generations. During subculturing, do not add white sugar, trehalose, glucono-δ-lactone, maltodextrin, or salt, and do not reclaim dough from the production dough. Refrigerate the mature independent seed dough at -5~0℃ for later use, and rejuvenate it every 7~10 days with the above-mentioned feed composition.

[0044] Among them, the fermented melon koji is a naturally enriched solid-state fermentation koji, made during the hottest days of summer (from the Dragon Boat Festival to the hottest period of summer). It is made by mixing ripe melon (fragrant melon, cantaloupe) with wheat flour / corn flour / yellow millet flour, wrapping it in jute leaves, and allowing it to ferment naturally and be dried in the shade for a long time to obtain dried koji blocks. The jute leaves provide a microenvironment that absorbs wild microorganisms from the environment. There are complex mixed microorganisms such as wild yeast, lactic acid bacteria, a small amount of mold, and Bacillus in the air and on the surface of the melon peel. Compared with sweet wine koji, the fermented melon koji has a higher proportion of lactic acid bacteria and a different type of yeast, so the aroma and acidity characteristics of the fermented koji are different.

[0045] The rice wine is made by fermenting a mixture of sweet wine koji and glutinous rice. The sweet wine koji is a saccharification-type solid-state fermentation koji, with Rhizopus as the core microorganism and a small amount of yeast. It differs significantly from fermented rice wine koji: fermented rice wine koji has a higher proportion of lactic acid bacteria, making it suitable for sourdough starter; sweet wine koji has a strong Rhizopus content, which excels at converting starch into glucose, with yeast then producing a small amount of ethanol. The fermentation products include glucose, maltose, a small amount of ethanol, organic acids, and amino acids.

[0046] Medium-temperature fermentation step: Place the dough in a clean fermentation container and ferment for 12–14 hours at 15.0 ± 0.5℃ and 75% relative humidity. Fermentation is stopped when the dough volume reaches 2.0 times its initial volume and the pH value is measured to be 4.2 as described above. No glucono-delta-lactone, salt, maltodextrin, or trehalose are added during fermentation.

[0047] Alkali adjustment steps: Dissolve 10g of edible alkali in 30g of water at 35℃ to prepare an edible alkali solution; separately, dissolve 6g of glucono-delta-lactone, 10g of trehalose, 10g of maltodextrin with a glucose equivalent of 10, and 4g of salt in 30g of water at 35℃ to prepare an aqueous solution. While stirring the fermented dough, first evenly add the edible alkali solution, and then evenly add the aqueous solutions of glucono-delta-lactone, trehalose, maltodextrin, and salt within 2 minutes after the initial addition of the edible alkali solution. After the addition of the solutions is complete, continue stirring for 6 minutes to obtain the alkali-adjusted dough. Within 20 minutes after the stirring is completed, the pH value of the alkali-adjusted dough is measured to be 6.4 using the aforementioned method.

[0048] Shaping and quick-freezing steps: Divide the alkali-treated dough into 15g portions, make wrappers, and wrap each wrapper with 13g of filling to obtain a 28g xiaolongbao (soup dumpling) embryo. Hand-wrapped xiaolongbao embryos do not need proofing, while machine-wrapped xiaolongbao embryos require proofing. From the time the aqueous solution of glucono-delta-lactone, trehalose, maltodextrin, and salt is added, hand-wrapped xiaolongbao must be shaped within 25 minutes and immediately placed in the quick-freezing environment; machine-wrapped xiaolongbao must be shaped within 10 minutes, then proofed for 40 minutes before being placed in the quick-freezing environment. Both hand-wrapping and machine-wrapping are carried out at room temperature of 25.0℃ and relative humidity of 75%.

[0049] Place the raw xiaolongbao dough in a -45℃ flash-freeze environment for 60 minutes, until the center temperature does not exceed -18℃. Package immediately after flash-freezing and store frozen at a temperature not exceeding -18℃. When ready to eat, do not thaw; simply steam directly in a steaming environment until cooked.

[0050] When implementing the above-mentioned raw materials, the total amount of water added can be adjusted according to the water absorption rate of medium-gluten wheat flour, the season, and the activity of the independent seed dough. However, the requirements for fermentation endpoint volume, fermentation endpoint pH value, glucono-δ-lactone, trehalose, maltodextrin, salt addition point, adjustment of alkali dough pH value, and time for entering the quick-freezing environment should be met at the same time.

[0051] Comparative Example 1:

[0052] This comparative experiment demonstrates the beneficial effects of the technical solution of this invention and shows that it cannot be replicated simply by adjusting the total amount of edible alkali added. The simultaneous addition of glucono-delta-lactone during the alkali-making process has key functions including dynamically and slowly adjusting pH and improving the uniform distribution of acid-base space within the dough. These two elements synergistically improve the color of the dough for frozen xiaolongbao (soup dumplings) and reduce alkali spot defects. This distinguishing feature is the key innovation of this invention compared to existing traditional alkali-making processes. Three comparative experiments were conducted: the addition stage of glucono-delta-lactone and pH control.

[0053] 1. Add glucono-δ-lactone when kneading the dough, and after fermentation, only add baking soda.

[0054] 2. Do not add glucono-delta-lactone when kneading the dough; after fermentation, only add baking soda.

[0055] 3. Do not add anything during fermentation, but add gluconate-δ-lactone when adding baking soda.

[0056] All of the aforementioned conditions were kept consistent: water, flour, individual seed dough, temperature, and humidity were all kept consistent.

[0057] The fixed reference conditions are as follows:

[0058] Flour: 5000g Qitai winter wheat flour

[0059] Water: 2700g

[0060] Individually Seed Dough: 750g

[0061] Fermentation conditions: constant temperature 15℃, humidity 82%, fixed fermentation time; dough pH uniformly set to 4.50 before alkali application.

[0062] Sodium carbonate (edible alkali): 52.36g

[0063] GDL uniform dosage: 30.8g

[0064] The mixing speed, mixing time, number of rolls, wrapping, second proofing, -45℃ air-cooling quick-freezing, and -18℃ frozen storage are all consistent.

[0065] pH detection method: Measured after the dough has been homogenized for 2 minutes.

[0066] Group A: Add GDL during the dough kneading stage, and only add baking soda after fermentation.

[0067] Ingredient addition order: flour + separate seed dough + water + 30.8g GDL → kneading → fermentation at 15℃ → add only 52.36g baking soda to make alkali.

[0068] 1. After kneading (before fermentation), pH: 5.72

[0069] 2. Fermentation endpoint (before alkali addition): pH 4.50 (mandatory uniform endpoint)

[0070] Mechanism: GDL undergoes slow hydrolysis upon early contact with water, slightly altering the fermentation microenvironment in the early stages; the metabolic pathways of lactic acid bacteria and yeast are slightly shifted; the composition of organic acids changes, with a slight increase in the content of ethyl acetate and ethyl lactate, which are fruity flavor compounds. The total acid production is ultimately artificially controlled to the same pH of 4.50.

[0071] 3. After adding the alkali and kneading the dough, the overall pH of the dough is 6.48.

[0072] Local pH values ​​at three points: 6.31, 6.55, 6.62

[0073] Local pH range: 0.31

[0074] 4. Dough texture: Slightly elastic, with tight gluten and low stickiness.

[0075] 5. Steamed bun machine operation: Smooth operation, less prone to sticking to the hopper; slightly lower rate of broken skin.

[0076] 6. Second proofing: The expansion rate is slightly slower.

[0077] 7. The epidermis of the quick-frozen embryo: smooth with very few tiny dark spots.

[0078] 8. Storage at -18℃ for 7 days: Yellowing rate ≈ 2.2%, Cracking rate ≈ 3.1%.

[0079] 9. Re-steaming: The surface is translucent; the pores are fine and even; the dough has a slightly mellow fermented fruit aroma; there is no obvious alkaline taste.

[0080] Group B: No GDL added throughout the entire process; only baking soda added at the end of fermentation.

[0081] Ingredient addition order: flour + separate seed dough + water → kneading → fermentation at 15℃ → add only 52.36g of baking soda to make alkali.

[0082] 1. After kneading (before fermentation), pH: 6.13

[0083] 2. Fermentation endpoint (before alkali addition): pH 4.50 (mandatory uniform endpoint)

[0084] Mechanism: Traditional sourdough fermentation relies on the natural metabolism of microorganisms to produce acid; relying solely on mechanical stirring to disperse edible alkali powder can easily create instantaneous localized high-alkalinity micro-zones, burning localized gluten proteins.

[0085] 3. After adding the alkali and kneading the dough, the overall pH of the dough is 6.49.

[0086] Local pH values ​​at three points: 6.22, 6.58, 6.77

[0087] Local pH range: 0.55

[0088] 4. Dough feel: Normal elasticity; some small areas are a bit hard.

[0089] 5. Steamed bun machine operation: Normal; occasionally a few pieces of dough are broken.

[0090] 6. Secondary fermentation: Unstable expansion rate

[0091] 7. The surface of the embryo after quick-freezing: generally smooth, with a few small yellow spots or hidden dangers.

[0092] 8. Storage at -18℃ for 7 days: Yellowing rate ≈ 8.7%, Cracking rate ≈ 7.4%

[0093] 9. Re-steaming: Occasionally, small yellow spots are visible on the surface; the pores are uneven in size; the aroma of old wheat is prominent, while the fruit aroma is weak.

[0094] Group C: Do not add GDL when kneading the dough; after fermentation, add baking soda and GDL simultaneously when adding lye.

[0095] Ingredient addition order: flour + separate seed dough + water → kneading → fermentation at 15℃ → simultaneously add 52.36g edible alkali and 30.8g GDL to make alkali.

[0096] 1. After kneading (before fermentation), pH: 6.14

[0097] 2. Fermentation endpoint (before alkali addition): pH 4.50 (mandatory uniform endpoint)

[0098] Mechanism: GDL does not participate in long-term fermentation; it only slowly releases a small amount of gluconic acid during the alkali mixing stage, buffering the local strong alkali peak at the moment of alkali addition; it smooths the pH difference inside the dough; it hardly changes the final overall pH of the dough, mainly optimizing pH uniformity, protecting gluten, and reducing the probability of yellow spots after quick-freezing.

[0099] 3. After adding the alkali and kneading the dough, the overall pH of the dough is 6.47.

[0100] Local pH values ​​at three points: 6.38, 6.49, 6.56

[0101] Local pH range: 0.18

[0102] 4. Dough texture: Soft and even, with well-developed gluten and optimal extensibility.

[0103] 5. Steamed bun machine operation: optimal performance, smooth operation, and minimal breakage.

[0104] 6. Secondary proofing: Stable expansion and best consistency.

[0105] 7. Quick-frozen embryo epidermis: Excellent smoothness, almost no dark spots.

[0106] 8. Stored at -18℃ for 7 days: Yellowing rate ≈ 1.3%, Cracking rate ≈ 2.0%

[0107] 9. Re-steaming: The skin is white and translucent; the air holes are uniform; the texture is soft and chewy; the original flavor of the old dough is the main flavor, with a moderate fruity aroma.

[0108] The summary data table is as follows:

[0109]

[0110] Comparative Example 2:

[0111] A comparative experiment was conducted to assess the contribution of the compound components during the alkali treatment stage. The following four formulation groups were set up:

[0112] 1. A compound of edible alkali, gluconate-δ-lactone, and trehalose;

[0113] 2. A compound of edible alkali, glucono-δ-lactone, and maltodextrin;

[0114] 3. Add baking soda, gluconate-δ-lactone, and salt;

[0115] 4. A compound preparation consisting of edible alkali, gluconate-δ-lactone, trehalose, maltodextrin, and salt.

[0116] The extensibility, toughness, and shaping properties of four groups of dough were determined, and the hardness, elasticity, chewiness, moisture loss rate, shrinkage rate, wrinkling rate, cracking rate, and juice retention rate of the dough after steaming were measured. The roles of trehalose, maltodextrin, salt, and glucono-δ-lactone were determined, and the synergistic effects of adding maltodextrin, trehalose, and salt when adding baking soda were identified.

[0117] The experiment is as follows:

[0118] Flour: 5000g; Individually sized seed dough: 750g; Water: 2700g

[0119] Fermentation: 15.0±0.5℃, humidity 82%; at the end of fermentation (before adding alkali), the dough pH was 4.50, edible alkali (sodium carbonate): 52.36g; glucono-delta-lactone (GDL): 30.8g.

[0120] All materials are added simultaneously during the alkali-removal process.

[0121] Group 1: GDL + Trehalose (50g);

[0122] Group 2: GDL + maltodextrin (50g);

[0123] Group 3: GDL + Salt (20g);

[0124] Group 4: GDL + 50g trehalose + 50g maltodextrin + 20g salt.

[0125] The entire process is standardized: alkali mixing speed, mixing time, number of pressing passes, and wrapping; quick freezing at -45℃; frozen storage at -18℃ for 30 days; and re-steaming conditions are standardized.

[0126] The four sets of comparative data are shown in the following table:

[0127]

[0128] The functions and synergistic effects of each component are analyzed as follows:

[0129] Group 1: GDL and trehalose have a strong synergistic effect. GDL: releases weak acid slowly during the alkali-addition stage, eliminating local strong alkali peaks, reducing the pH difference within the dough, and minimizing the burning effect of strong alkali on the gluten. Trehalose: a protein protectant, reducing the mechanical damage to the gluten network caused by ice crystals during freezing; inhibiting starch retrogradation; binding free water, reducing the rate of water migration. Advantages: moderate tensile resistance, best extensibility; smooth forming on the machine; in Group 1, the combination of GDL and trehalose shows superior performance in extensibility, freeze-cracking resistance, moisture retention, and softness after re-steaming, but there are still shortcomings in dough toughness and mechanical processing stability during continuous machine processing. The re-steamed dough is soft and has good elasticity. Disadvantages: lack of gluten-strengthening components, slightly weaker resistance to mechanical shearing, and average stability during large-scale, long-term continuous machine processing; relatively high raw material procurement costs.

[0130] Group 2: GDL + maltodextrin have a moderate synergistic effect. GDL buffers local alkaline peaks. Maltodextrin fills gluten gaps, moderately retains water, and improves dough elasticity; it also inhibits some starch retrogradation; and its cost is lower than trehalose. Advantages: High cost-effectiveness; good dough elasticity; excellent stability in large-scale continuous production. Disadvantages: Weaker extensibility than the trehalose group; weaker anti-aging properties during long-term frozen storage than trehalose; greater increase in hardness after re-steaming.

[0131] Group 3: The synergistic effect of GDL and salt is weak. GDL: buffers local alkaline peaks. Salt: strengthens gluten disulfide bonds, increases gluten tensile resistance, tightens the gluten network; reduces dough extensibility. Advantages: lowest raw material cost, dough with sufficient gluten strength. Disadvantages: significantly reduced extensibility; dough structure is too dense; worst performance in terms of water loss, shrinkage, wrinkling, and cracking during frozen storage; filling juices are more easily lost through dough gaps.

[0132] Group 4: GDL + trehalose + maltodextrin + salt achieves the best multi-element synergistic effect.

[0133] 1. Trehalose is responsible for protein protection, water retention, and resistance to starch retrogradation, ensuring extensibility and softness;

[0134] 2. Maltodextrin is responsible for filling the gaps in gluten, improving toughness, optimizing the stability of mass production, and controlling production costs;

[0135] 3. Salt is responsible for properly cross-linking the gluten, giving the dough the right elasticity, and preventing the dough from becoming too soft and collapsing;

[0136] 4. GDL is responsible for eliminating localized strong alkaline peaks during alkali application, reducing pH dispersion, minimizing localized gluten burn, and reducing the risk of yellow spots during quick-freezing.

[0137] The three binary compound groups mentioned above all have different performance focuses, making it difficult to simultaneously take into account the dough's extensibility, toughness, freeze-thaw resistance, water retention, and continuous forming stability. Trehalose, maltodextrin, salt, and GDL are all added simultaneously during the alkali-removing process after the old dough has completed its full 15°C medium-temperature fermentation. This can simultaneously take into account extensibility, toughness, gluten strength, freeze-thaw resistance, water retention, and production cost, achieving a multi-dimensional performance balance that cannot be achieved by single components or two compound groups.

[0138] Comparative Example 3:

[0139] A continuous subculturing stability experiment was conducted on independently cultivated seed dough. Three independent subculturing lines were established, including an independently cultivated seed dough group and a group where dough (fermented but not alkali-treated) was taken from the production dough (sugar was added each time to increase fermentation speed) and cyclically subcultured. Each group underwent at least 10 subculturing generations. The fermentation time, endpoint pH, volume ratio, and amount of alkali required to reach the specified volume and pH endpoint for each generation were recorded. The mean, standard deviation, and coefficient of variation for each indicator were calculated. Changes in the number of lactic acid bacteria and yeast, as well as the dominant bacterial population, were detected, demonstrating that independently cultivated seed dough can reduce batch fluctuations in continuous production processes.

[0140] I. Experimental Setup

[0141] Group A: Independent seed dough group (passaged system without added sugar, trehalose, or maltodextrin), parallel lines: A-1, A-2, A-3.

[0142] Group B: Production dough return and passaging group (samples are production dough that has completed fermentation and has not been alkali-treated; white sugar is added during the fermentation stage of each batch of production dough to accelerate the process, and the sugar content accumulates with each passaging), parallel lines: B-1, B-2, B-3.

[0143] Culture conditions: 15.0±0.5℃, relative humidity 82%; Fermentation endpoint: number of passages: 10 consecutive generations; Detection items: fermentation time, endpoint pH, volume ratio; Optional: yeast, lactic acid bacteria colony count, dominant microbial community

[0144] II. Group A (Independent Seed Dough) Data from Generations 1-10 (Average of 3 Lines)

[0145] The table is as follows:

[0146]

[0147] The statistical results of Group A's 10 generations are shown in the table below:

[0148]

[0149] Microbial community conclusions: The number of yeasts and lactic acid bacteria fluctuated very little, the dominant species remained stable, and there was no directional drift.

[0150] III. Data for Group B (dough produced without alkali after fermentation, taken back for generational transfer, sugar accumulation) from generations 1 to 10 (average of 3 lines) are shown in the table below:

[0151]

[0152] The statistical results of Group B across 10 generations are shown in the table below:

[0153]

[0154] Microbial community conclusions: When fermented dough that has not yet been alkali-treated is used as a seed source for back-subculturing, residual sugars accumulate in each generation of dough, lactic acid bacteria continue to proliferate and multiply, while yeast gradually declines. With the increase in the number of subculturing, the fermentation time is significantly prolonged, the dough pH drops rapidly, the volume ratio decreases, the microbial community exhibits obvious directional drift, the subculturing system is unstable, and it cannot be used as a sourdough starter for a long time.

[0155] IV. Experimental Conclusions

[0156] Group B uses a method of re-extracting and subculturing the starter from the sugar-added dough (fermented but not alkali-treated). The exogenous sugar continuously accumulates in the starter system, causing a drift in the proliferation characteristics of yeast and lactic acid bacteria. With each subculturing, the fermentation time is continuously extended, the pH at the end of fermentation continues to decrease, and the fermentation expansion volume continues to decrease. The amount of edible alkali required to neutralize the acidity continues to increase. The coefficients of variation of various indicators are significantly higher, resulting in large batch fluctuations during continuous industrial production and making it difficult to control the product quality stably.

[0157] Group A adopted an independent seed dough system, isolating exogenous sugars, trehalose, maltodextrin and other auxiliary materials in the production formula throughout the process, and the microbial community had a stable living environment. After 10 consecutive generations of subculturing, there was no significant drift in fermentation time, endpoint pH and volume ratio, and the coefficient of variation of each indicator was less than 1%. The number of yeast and lactic acid bacteria was stable, and the dominant microbial community did not shift significantly.

[0158] This study demonstrates that an independent seed dough system can significantly reduce batch fluctuations in the continuous industrial production of frozen xiaolongbao (soup dumplings) using sourdough, ensuring long-term product quality stability.

[0159] Comparative Example 4:

[0160] Comparative experiments were conducted at different fermentation temperatures. Three groups were established: a low-temperature fermentation group (4–6℃), a medium-temperature fermentation group (15℃), and a fermentation group (20–25℃). For each group, reaching the same volume ratio and pH endpoint was used as the fermentation termination condition. The time required to reach the endpoint was recorded, and the specific volume, texture, color, and sensory quality of the dough and steamed products were compared. Ethyl acetate, ethyl lactate, organic acids, and other volatile flavor compounds were detected using headspace solid-phase microextraction combined with gas chromatography-mass spectrometry.

[0161] I. Experimental Objective

[0162] Three constant-temperature fermentation groups (low temperature, medium temperature, and high temperature) were set up, with the same volume ratio and pH as the fermentation endpoint. The fermentation time, dough physicochemical indicators, and finished product quality were compared. Volatile flavor compounds were detected by GC-MS to verify that 15℃ medium-temperature fermentation has the optimal balance in terms of production cycle, unique flavor of old dough, and overall quality of frozen xiaolongbao.

[0163] II. Experimental Grouping

[0164] All groups used the same flour, separate seed dough, and water content; separate seed dough was used to avoid passage drift interference in this experiment.

[0165] Group 1: Low-temperature fermentation group; Constant temperature: 4-6℃;

[0166] Group 2: Mesophilic fermentation group; Constant temperature: 15.0±0.5℃;

[0167] Group 3: Higher temperature fermentation group. Constant temperature: 20-25℃.

[0168] The criteria for determining the fermentation endpoint are as follows:

[0169] Once the dough expands to an initial volume ratio of 2.2 and the dough pH reaches 4.50, fermentation is immediately terminated, and the process proceeds to subsequent steps including alkali addition, dough pressing, wrapping, -45℃ air-cooling quick-freezing, -18℃ frozen storage, and re-steaming.

[0170] III. Testing Items

[0171] ① Fermentation kinetic parameters

[0172] Record the parameters of each group of doughs during the fermentation process to reach the preset fermentation endpoint (volume ratio 2.2 times, pH=4.50).

[0173] Specific tests include: fermentation time required to reach the fermentation endpoint, pH at the fermentation endpoint (before adding alkali), and volume ratio at the fermentation endpoint.

[0174] ② Raw dough indicators (raw dough after alkali addition, all auxiliary ingredients are mixed and relaxed, before wrapping)

[0175] The physicochemical, rheological, microbiological, and machine processing properties of the dough after alkali adjustment were determined.

[0176] Specific tests include: final pH of the dough after alkali treatment, dough moisture content, maximum gluten tensile resistance, gluten extensibility, stretch ratio, dough hardness, dough viscosity, and dough surface color. , , Yeast colony count, lactic acid bacteria colony count, sensory evaluation of machine forming (whether it sticks to the machine, dough extensibility, whether it tears during continuous wrapping, whether it collapses).

[0177] ③ Quick-frozen and re-steamed finished product indicators

[0178] After the dough is wrapped, it is quick-frozen at -45℃ and stored at -18℃. The quality of the finished buns is then measured after they are steamed until fully cooked.

[0179] Specific tests include: finished product specific volume, dough hardness, dough elasticity, dough chewiness, and surface color. , , Sensory comprehensive score.

[0180] ④ Flavor compound detection (headspace solid-phase microextraction-gas chromatography-mass spectrometry SPME-GC-MS)

[0181] Volatile components of dough were extracted, and characteristic flavor compounds were qualitatively and quantitatively detected.

[0182] Specific tests include: relative content of ethyl acetate, relative content of ethyl lactate, and total relative content of short-chain volatile organic acids. Other detected volatile flavor compounds such as alcohols and aldehydes are also recorded.

[0183] The data table is as follows:

[0184]

[0185] IV. Brief description of the phenomena and mechanisms in each group

[0186] 1. Low temperature group: 4-6℃;

[0187] Lactic acid bacteria and yeast have low metabolic rates. Fermentation time is extremely long (about 34 hours), resulting in excessively long factory production cycles and difficulties in scheduling; less ester flavor compounds are produced; the finished product is relatively dense; advantages: the microbial community is not easily out of control; disadvantages: production efficiency is too low, the flavor is weak, and it is not suitable for mass production.

[0188] 2. 15℃ medium temperature group;

[0189] The metabolic rates of yeast and lactic acid bacteria are matched, resulting in balanced growth; the fermentation time is moderate (approximately 14.5 hours), facilitating factory scheduling; ethyl acetate and ethyl lactate (fruit-flavored esters) are produced in large quantities, resulting in a full and mellow aroma of the fermented dough; the concentration of organic acids is moderate, preventing a pungent sour taste; after quick-freezing and re-steaming, the dough is soft, elastic, and has an ideal specific volume, with a clean white color, achieving the highest sensory score; the microbial community is not easily disturbed by overheating, ensuring good batch stability.

[0190] 3. Higher temperature group: 20-25℃;

[0191] Fermentation is fast and takes little time; however, if the bacterial colony proliferates too quickly, the lactic acid bacteria will produce too much acid, resulting in an unpleasant sour taste; if the ester production is below 15°C, the dough is prone to fermentation going out of control, and the pH is difficult to control precisely; after freezing, the dough ages faster, and the overall quality of the finished product declines.

[0192] VI. Experimental Conclusions

[0193] Under the conditions of the same volume ratio and the same pH as the fermentation endpoint:

[0194] Fermentation at low temperatures of 4-6℃ takes too long, has low production efficiency, and results in insufficient formation of characteristic fruity esters.

[0195] Fermentation at 20-25℃ is faster than at higher temperatures, but it can easily lead to excessive organic acids, flavor imbalance, and reduced batch stability.

[0196] The 15℃ medium-temperature fermentation takes into account the appropriate production cycle and promotes the enrichment of characteristic sourdough fruit flavor substances such as ethyl acetate and ethyl lactate; the quick-frozen and re-steamed finished product has the best overall quality in terms of specific volume, texture, color and sensory characteristics, and is most suitable for the industrial continuous production of sourdough quick-frozen raw dough xiaolongbao.

[0197] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. These embodiments are merely descriptions of preferred embodiments and are not intended to limit the scope or concept of the invention. The specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. Such combinations, as long as they do not violate the spirit of the present invention, should also be considered as part of this disclosure. To avoid unnecessary repetition, the present invention will not further describe the various possible combinations.

[0198] This invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this invention and without departing from the design idea of ​​this invention, all modifications and improvements made by those skilled in the art to the technical solutions of this invention should fall within the protection scope of this invention. The technical content for which protection is sought in this invention has been fully described in the claims.

Claims

1. A method for preparing frozen xiaolongbao (soup dumplings) using a medium-temperature fermented alkali-treated compound dough, characterized in that... Includes the following steps: S1. Mix the independent seed dough, production medium-gluten wheat flour, water and white sugar to obtain the production dough; S2. Ferment the dough at a medium temperature of 14.5-15.5℃ for 12-14 hours until the volume reaches 2.0-2.5 times the volume before fermentation and the pH value is 4.0-4.5 to obtain fermented dough. No glucono-δ-lactone, trehalose, maltodextrin and salt are added during the fermentation process. S3. During the mixing of the fermented dough, add an edible alkali solution and a compound aqueous solution. The compound aqueous solution contains glucono-δ-lactone, trehalose, maltodextrin and salt to adjust the pH of the dough to 6.2-6.6, thus obtaining an alkali-adjusted dough. S4. The alkaline dough is made into xiaolongbao (soup dumpling) embryos. The xiaolongbao embryos are placed in a quick-freezing environment directly or after proofing until the center temperature of the xiaolongbao embryos is not higher than -18℃.

2. The method for preparing frozen xiaolongbao (soup dumplings) using a medium-temperature fermentation, alkali-addition, compound feeding, pH-buffered dough modification, and old dough modification, as described in claim 1, is characterized in that... Based on the mass of the medium-gluten wheat flour used in production, the amount of the independent seed dough is 10%–20%, the total water content is 50%–60%, the amount of white sugar is 1%–1.2%, the amount of trehalose is 1%–1.5%, the amount of maltodextrin is 1%–1.5%, the amount of salt is 0.36%–0.40%, the amount of edible alkali is 0.8%–1.1%, and the amount of glucono-δ-lactone is 0.6%–0.65%. The total amount of water added includes the water used for kneading the dough in step S1, the water used for the edible alkali solution in step S3, and the water used for the compound solution, but does not include the water contained in the individual seed dough itself.

3. The method for preparing frozen xiaolongbao (soup dumplings) using a medium-temperature fermentation, alkali-addition, compounding, pH-buffered dough modification, and improved dough as described in claim 2, is characterized in that... The maltodextrin, trehalose, salt, and glucono-δ-lactone are pre-mixed and prepared into a compound aqueous solution. The compound aqueous solution is added to the fermented dough during the alkali-addition process in step S3 after the dough has completed medium-temperature fermentation.

4. The method for preparing frozen xiaolongbao (soup dumplings) using a medium-temperature fermentation, alkali-addition, compounding, pH-buffered dough modification, and improved dough as described in claim 3, is characterized in that... In step S3, the edible alkali is dissolved in water at a temperature of 30-40°C, accounting for 3%-3.5% of the mass of the medium-gluten wheat flour used in production, to prepare the edible alkali aqueous solution. Additionally, glucono-δ-lactone, trehalose, maltodextrin, and salt are dissolved in water at a temperature of 30-40°C, accounting for 3%-3.5% of the mass of the medium-gluten wheat flour used in production, to prepare the compound aqueous solution.

5. The method for preparing frozen xiaolongbao (soup dumplings) using a medium-temperature fermentation, alkali-addition, compound feeding, pH-buffered dough modification, and old dough modification, as described in claim 4, is characterized in that... In step S3, while stirring the fermented dough, the edible alkali solution is added evenly first, and the compound aqueous solution is added evenly within 1 to 3 minutes after the addition of the edible alkali solution. After the compound aqueous solution is added, stirring is continued for 5 to 8 minutes to make the pH value of the alkali-adjusted dough 6.3 to 6.

5.

6. The method for preparing frozen xiaolongbao (soup dumplings) using a medium-temperature fermentation, alkali-addition, compound feeding, pH-buffered dough modification, and old dough modification, as described in claim 1, is characterized in that... The initial preparation method of the independent seed dough is as follows: based on the mass of medium gluten wheat flour, add 75% to 85% water, 10% to 16% koji and 20% to 30% rice wine and mix evenly, then activate at 26 to 30°C for 10 to 14 hours.

7. The method for preparing frozen steamed buns using a medium-temperature fermentation, alkali-addition, compound feeding, pH-buffered dough modification, and old dough modification according to claim 6, characterized in that... The method for passage of the independent seed dough is as follows: Take 25-35g of mature independent seed dough as the next generation inoculum, add medium-gluten wheat flour according to the mass ratio of the inoculum to the supplemented medium-gluten wheat flour of 1:10-1:17, and add 55%-65% water based on the mass of the supplemented medium-gluten wheat flour. Cultivate at 14.5-15.5℃ until mature, and passage continuously for 6-10 generations until the dough volume reaches 2.0-2.5 times that before cultivation and the pH value is 4.0-4.

5. During the passage process, no white sugar, trehalose, glucono-δ-lactone, maltodextrin and salt are added, and the dough is not taken back from the production dough. The mature independent seed dough is refrigerated at -5 to 0℃ and rejuvenated every 7-10 days according to the above-mentioned feed composition.

8. The method for preparing frozen steamed buns using a medium-temperature fermentation, alkali-addition, compound feeding, pH-buffered dough modification, and old dough modification, as described in claim 1, is characterized in that... The relative humidity of fermentation in step S2 is 75% to 82%, and fermentation ends when the volume of the produced dough reaches 2.0 to 2.3 times the volume before fermentation and the pH value is 4.2 to 4.

5.

9. The method for preparing frozen steamed buns using a medium-temperature fermentation, alkali-addition, compound feeding, pH-buffered dough modification, and old dough modification, as described in claim 1, is characterized in that... Step S4 involves hand-shaping the dough, dividing it into 13-17g portions, making wrappers, and then wrapping 11-15g of filling inside to obtain a single xiaolongbao embryo weighing 24-32g. The hand-shaping is carried out at 23-27℃ and 70%-80% relative humidity. The xiaolongbao embryos are not proofed and are formed within 20-30 minutes after the addition of the compound aqueous solution and then placed in the quick-freezing environment.

10. The method for preparing frozen steamed buns using a medium-temperature fermentation, alkali-addition, compound feeding, pH-buffered dough modification, and old dough modification, as described in claim 1, is characterized in that... Step S4 involves machine forming, dividing the alkali-treated dough into 13-17g portions, making wrappers, and then wrapping 11-15g of filling inside to obtain a single xiaolongbao embryo weighing 24-32g. The machine forming is carried out at 23-27℃ and 70%-80% relative humidity, and the forming is completed within 8-12 minutes from the addition of the compound aqueous solution. The xiaolongbao embryos are then proofed for 35-45 minutes and placed in the quick-freezing environment.

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