A fermented bread and its fermentation method

Abstract

This application discloses a fermented bread and its fermentation method, relating to the field of food fermentation technology. The fermented bread provided by this application achieves synergistic effects of flavor enhancement, nutrient conversion, and texture improvement through staged solid-state fermentation and wet micronization. It effectively addresses the problems of thin flavor profiles, low resistant starch conversion rate, and dependence on exogenous additives faced by bread fermentation processes under the requirements of flavor complexity, starch digestibility, and clean labeling. It solves the technical pain points of traditional direct sourdough methods, such as limited single lactic acid bacteria metabolites, excessive sourness affecting palatability, and low starch hydrolysis efficiency; and enzyme preparation methods, such as rapid decay of exogenous enzyme activity, single enzymatic hydrolysis products failing to generate rich flavor precursors, and lack of clean labeling attributes. Compared to existing technologies, this fermented bread has the outstanding characteristics of rich natural fermentation flavor, improved nutrient digestibility, and soft and stable texture.

Description

Technical Field

[0001] This application relates to the field of food fermentation technology, and in particular to a fermentation method for fermented bread. Background Technology

[0002] As the consumer market evolves towards health and functionality, the industry is placing more stringent demands on the nutritional value, flavor profile, and texture of fermented bread. High-quality fermented bread must maintain its softness and texture stability for at least 72 hours under room temperature storage conditions, while effectively achieving deep conversion of starch raw materials to improve digestibility and flavor complexity. However, traditional bread fermentation processes have limitations in terms of natural flavor enhancement and nutrient conversion efficiency. The generation pathway of volatile flavor compounds during fermentation is singular, insufficient starch hydrolysis leads to high levels of resistant starch residue, and the limited variety of fermentation byproducts affects the bread's aroma profile and persistence. Therefore, developing a fermentation raw material pretreatment technology that combines natural flavor enhancement, deep starch conversion, and dough texture optimization has become a key direction for improving bread quality and health attributes. According to baking industry research data, the baked goods market continues to expand, with pre-packaged staple bread accounting for over 70% of the demand for enhanced natural fermented flavor and clean labeling, requiring compliance with technical requirements of no artificial flavors, no bread improvers, and no added sucrose. However, existing bread fermentation aids are unable to achieve synergistic effects in flavor enhancement, nutrient conversion, and texture improvement. As a result, industrialized bread products in the actual market generally suffer from problems such as thin flavor, insufficient aftertaste, rapid aging rate, and reliance on chemical additives, which seriously restricts the development of bread products towards high-end and clean label products.

[0003] To address the technical challenge of synergistically enhancing natural flavor and starch conversion in bread fermentation, the industry has developed various technical approaches, including the direct sourdough method and the enzyme addition method. The direct sourdough method involves adding a single lactic acid bacteria, such as *Lactobacillus plantarum*, to flour for prolonged acidification and fermentation. The lactic acid produced by these bacteria imparts a sour and aromatic flavor to the bread, while also partially degrading starch and gluten, improving digestibility. However, this technology relies on a single lactic acid bacteria for fermentation, with lactic acid as the primary metabolic product. The variety of volatile flavor compounds is limited, making it difficult to create a complex and rich fermented aroma. Furthermore, high lactic acid content results in an overly sour taste, requiring a compromise between flavor complexity and palatability. Additionally, the hydrolysis efficiency of lactic acid bacteria on starch is relatively low, with a resistant starch conversion rate of only 5%–10%, leading to limited nutritional enhancement. Moreover, the sourdough preparation cycle is as long as 20 days. The 30-hour production cycle limits the flexibility of industrial production. The enzyme addition method involves directly adding industrial enzymes such as α-amylase, xylanase, and lipase during dough preparation. This accelerates starch decomposition to produce reducing sugars, extending the softness of bread during its shelf life and improving dough workability. However, the exogenous enzymes added in this technology rapidly lose activity during dough fermentation and baking. The enzymatic hydrolysis products have a simple composition and cannot generate rich flavor precursors. Furthermore, enzyme residues affect the clean label properties. In addition, the enzymatic hydrolysis process mainly destroys starch molecules by random cleavage, lacking gradient and directionality, making it difficult to achieve a balance between softness and chewiness.

[0004] To address the aforementioned technical shortcomings, there is an urgent need to improve existing technologies. Summary of the Invention

[0005] To address the problems of limited flavor complexity, insufficient starch conversion, and reliance on chemical additives for texture improvement in existing bread fermentation processes, this invention provides a fermented bread and its fermentation method. The fermentation method combines staged solid-state fermentation, wet micronization, and dough preparation and steaming. This constructs a bread quality improvement system from three dimensions: starch gradient conversion, synergistic generation of flavor microorganisms, and natural texture improvement. This enhances the bread's flavor complexity, nutrient digestibility, and soft texture stability, avoiding the problems of single flavor and reliance on exogenous additives in traditional fermentation techniques. It also extends the bread's shelf life at room temperature, meeting consumer demand for natural flavors, clean labels, and healthy staple foods. Furthermore, the fermented bread production method provided by this invention offers precise and controllable process parameters, good batch consistency, requires no additional sucrose or artificial bread improvers, is easy to operate, and meets the needs of industrialized staple bread production.

[0006] The present invention provides a fermentation method for fermented bread, comprising the following steps:

[0007] After steaming, millet is mixed with yeast and subjected to staged solid-state fermentation to obtain millet fermented product. The staged solid-state fermentation includes saccharification fermentation at 28-32°C and 80-95% humidity for 12-24 hours, followed by flavor fermentation at 22-26°C and 65-80% humidity for 12-36 hours.

[0008] The millet fermentation product was subjected to wet micronization treatment to obtain fermented millet slurry;

[0009] The fermented millet paste, flour, yeast and water are mixed and kneaded into a dough. After shaping and proofing, the dough is steamed to obtain the fermented bread.

[0010] In this invention, the starter culture is a composite fermentation agent containing multiple microorganisms such as Rhizopus and yeast. The optimal saccharification temperature for Rhizopus is 28-32℃. Within this temperature range, the activity of the saccharifying enzymes secreted by Rhizopus reaches its peak, efficiently hydrolyzing the fully gelatinized amylopectin and amylose in steamed millet to produce reducing sugars such as glucose and maltose, as well as low-molecular-weight dextrin. Simultaneously, Rhizopus mycelia grow vigorously on the surface and shallow layers of the millet grains, forming a loose mycelial network structure, increasing oxygen microcirculation within the fermentation system, and providing a good interface for subsequent facultative anaerobic metabolism by yeast. Maintaining humidity at 80%-95% during the saccharification and fermentation stage effectively prevents excessive evaporation of moisture from the surface of the millet grains, which could lead to Rhizopus inactivation, while also avoiding premature proliferation of anaerobic bacteria due to humidity saturation, which could interfere with the saccharification process. During the flavor fermentation stage, the temperature is lowered to 22-26℃. This temperature range is the optimal aroma-producing temperature for yeast in the starter culture, rather than its optimal proliferation temperature. Under lower temperatures, the yeast's metabolic pathway shifts towards the synthesis of esters and higher alcohols. Esters such as ethyl acetate and ethyl lactate impart fruity and creamy notes to the fermented product, while aromatic alcohols such as phenylethanol contribute a rose-like aroma. Furthermore, these alcohols undergo esterification reactions with organic acids during subsequent distillation, forming a multi-layered, complex fermentation aroma. The reduced temperature gradient also inhibits excessive saccharification by Rhizopus, preventing the outer layer of millet grains from being completely decomposed into monosaccharides, which would lead to structural collapse and excessive acidity in the fermented product. It also preserves some incompletely decomposed starch granules in the inner layer of the fermented product, creating a gradient structure with decreasing saccharification levels from the outside in. During the flavor fermentation stage, humidity is reduced to 65%-80%. This moderate reduction in humidity favors the shift of yeast's facultative anaerobic metabolism towards ester synthesis. Simultaneously, the low humidity environment limits the growth of psychrophilic molds and other microorganisms, maintaining the microbial purity of the fermentation system.

[0011] In this invention, after staged solid-state fermentation, millet forms a gradient fermentation structure with a fully saccharified outer layer and an inner layer retaining some starch granules. The wet micronization process uses a colloid mill or a wet ultrafine pulverizer, utilizing the high-speed shearing force between the stator and rotor to pulverize the whole fermented millet grains into a fermented millet slurry with a fineness of 80-200 mesh in the presence of moisture. Compared to dry grinding, the presence of moisture in wet micronization acts as a lubricant and coolant, preventing excessively high local temperatures during grinding from damaging the flavor compounds and residual enzyme activity produced during fermentation. Secondly, under wet conditions, the gradient structure of millet fermentation products is finely dispersed rather than homogenized and broken down. The fully saccharified outer layer forms a continuous liquid phase rich in reducing sugars and flavor compounds, while the incompletely decomposed starch granules in the inner layer form discrete micron-sized starch fragments. The two form a heterogeneous microstructure of sweet liquid phase and starch fragments in the slurry. This structure plays a dual role in the subsequent dough system, providing natural flavor slow release and textural support. Thirdly, wet micronization finely disperses the dietary fiber in millet bran and germ, forming a micro-nano fiber network that can replace chemical emulsifiers and colloids in retaining water and stabilizing the gluten network.

[0012] In this invention, the fermented millet paste serves as a natural flavor base and dough improver, achieving the technical effect of clean labeling. The abundant reducing sugars generated by Rhizopus saccharification in the fermented millet paste undergo Maillard reactions with amino acids in the dough during steaming, producing the golden color and caramelized aroma of the bread crust. This imparts a natural sweetness and rich fermented aroma to the bread without the need for added sucrose. The organic acids in the fermented millet paste (mainly lactic acid, pH range 4.5-5.5) have a mild softening effect on gluten proteins, prolonging the formation time of the gluten network, thus improving the dough's extensibility during proofing. After steaming, the bread's core texture is delicate and uniform, with increased softness. The trace amounts of saccharifying enzymes and yeast metabolites remaining in the fermented millet paste continue to act on the starch in the flour during dough proofing, further producing reducing sugars and flavor precursors. This allows the bread to maintain a soft and moist texture for 24-72 hours after steaming, delaying starch retrogradation. The finely dispersed millet dietary fiber in fermented millet paste has high water-holding capacity, which can retain free water in the dough, reduce water loss during steaming and the accumulation of condensation on the surface of the bread.

[0013] In this invention, the mass ratio of millet to yeast is limited to (100~300):1. Within this range, the initial inoculation amount of Rhizopus and yeast is sufficient to quickly establish a dominant microbial community during the saccharification and fermentation stage, inhibiting the growth of miscellaneous bacteria in the environment. At the same time, it avoids excessive yeast addition leading to excessively rapid fermentation rate, uncontrolled saccharification, and excessive acid production, which would affect the flavor balance of the fermented millet paste.

[0014] In this invention, the moisture content of the steamed millet is limited to 55%~65%. This moisture content range provides suitable water activity for solid-state fermentation of millet. Below 55%, the starch gelatinization in the center of the millet grains is insufficient, making it difficult for Rhizopus hyphae to penetrate the grain interior, saccharification is limited to the surface, and the gradient structure of the fermented product is not obvious. Above 65%, excessive free water between the millet grains leads to decreased aeration of the fermentation system, inhibiting the aerobic growth of Rhizopus and increasing the risk of anaerobic bacteria growth.

[0015] In this invention, the mass ratio of fermented millet paste, flour, yeast, and water is limited to (40~60):(40~60):(0.5~1.5):(10~25). A fermented millet paste ratio of 40~60 parts ensures significant flavor contribution and texture improvement, while a flour ratio of 40~60 parts maintains the structural integrity of the gluten network, guaranteeing the volume and elasticity of the steamed bread. The yeast addition of 0.5~1.5 parts assists in dough proofing and gas production, compensating for fluctuations in yeast activity in the fermented millet paste and ensuring consistent proofing rates between batches. The water addition is adjusted according to the flour's water absorption rate and the moisture content of the fermented millet paste to achieve a final dough with moderate hardness.

[0016] In this invention, the proofing conditions are limited to a temperature of 34-38°C, a humidity of 80%-90%, and a time of 40-70 minutes. This temperature range is ideal for yeast gas production, ensuring that the dough expands fully within a reasonable time. The 80%-90% humidity prevents the dough surface from drying and cracking, ensuring a smooth and even surface on the bread after steaming.

[0017] In this invention, the steaming process is limited to steaming over high heat in boiling water for 18-25 minutes. Steaming over boiling water ensures that the dough is quickly heated and shaped after being placed in the pot, while steaming over high heat causes the internal moisture of the bread to vaporize and expand rapidly, forming a uniform porous structure. The steaming time of 18-25 minutes ensures that the bread is fully cooked without excessive moisture loss.

[0018] Preferably, the millet is steamed using atmospheric pressure steam for 20-35 minutes. Atmospheric pressure steam steaming is a simple process with low equipment requirements. The 20-35 minute steaming time ensures that the starch in the center of the millet grains is fully gelatinized while maintaining the grains' integrity and preventing breakage, thus providing a complete grain shape and good air permeability for subsequent solid-state fermentation.

[0019] Preferably, the yeast is a sweet wine yeast with a Rhizopus viable count ≥1×10⁻⁶. 5 CFU / g, yeast viable count ≥1×10⁻⁶ 6 CFU / g. The sweet wine starter has Rhizopus and yeast as the dominant microbial groups, with low bacterial content. The fermentation process is mainly saccharification to produce sweetness and aroma, with acid production as a secondary process. The resulting fermented millet paste has a sweet and refreshing flavor, making it suitable as a natural flavor base for bread.

[0020] Preferably, the fermentation method for the fermented bread further includes the following steps before the wet micronization treatment:

[0021] The millet fermentation product was subjected to solid-liquid separation to obtain fermentation broth and fermented millet grains;

[0022] The fermentation broth was vacuum concentrated to 1 / 3 to 1 / 2 of its original volume at 40-55°C to obtain a concentrated fermentation broth.

[0023] After the fermented millet grains undergo the wet micronization process, they are combined with the fermentation concentrate to obtain the fermented millet slurry.

[0024] This step further enriches the liquid flavor compounds and soluble sugars produced during fermentation through vacuum concentration, increasing the concentration of flavor compounds in the concentrate to 2-3 times that of the original solution. Simultaneously, the low-temperature vacuum concentration at 40-55℃ avoids the loss of heat-sensitive flavor compounds and browning caused by high-temperature evaporation. Combining the concentrate with the wet-processed micronized millet slurry results in a fermented millet slurry with a higher flavor intensity, contributing more significantly to the bread flavor when added to the dough in the same amount.

[0025] Preferably, the stirring method for the saccharification and fermentation is as follows: stirring is performed every 4-6 hours, with each stirring lasting 3-8 minutes; no stirring is performed during the flavor fermentation stage, and the mixture is kept still. Stirring every 4-6 hours during the saccharification and fermentation stage refreshes the oxygen supply between the millet grains, promotes the uniform growth of Rhizopus mycelium, and simultaneously exchanges the positions of surface-grown grains with internal grains, ensuring uniform fermentation. A stirring time of 3-8 minutes is sufficient to achieve uniform displacement; excessive stirring may damage the Rhizopus mycelium. Keeping the mixture still during the flavor fermentation stage maintains the microaerobic or anaerobic environment required for yeast metabolism, preventing the introduction of excessive oxygen through stirring, which could cause yeast metabolism to shift to respiration and reduce the synthesis of flavor compounds such as esters.

[0026] Preferably, before mixing the millet with the yeast, the steamed millet is cooled and dispersed to form discrete granules, and then cooled to 28-35°C. Cooling to 28-35°C lowers the temperature of the millet particles to the suitable growth temperature range for Rhizopus and yeast in the yeast, avoiding inactivation of the inoculum due to high-temperature inoculation. Dispersing the millet particles increases their contact area with air, improving air permeability and facilitating the aerobic growth of Rhizopus and the uniform adhesion of mycelia to the particle surface. The dispersed granular morphology after dispersion provides an ideal material state basis for subsequent staged solid-state fermentation.

[0027] A second aspect of the present invention provides a fermented bread, which is made by the fermentation method of any of the preceding claims.

[0028] This fermented bread uses fermented millet paste obtained through wet micronization of millet fermentation material as a natural flavor base and dough improver. No additional sucrose, glucose or artificial sweeteners are added. The flavor comes from the complex aroma of esters, alcohols and organic acids produced by the multi-strain solid-state fermentation of yeast. The sweetness comes from the reducing sugars produced by Rhizopus saccharification of millet starch and Maillard reaction products. The bread core has a delicate and soft texture and a significantly slowed aging rate during its shelf life.

[0029] In summary, this invention provides a fermented bread and its fermentation method. The fermentation method utilizes the optimal metabolic temperature difference between Rhizopus and yeast in a multi-strain yeast system through staged solid-state fermentation. In the saccharification fermentation stage, Rhizopus is activated at 28-32℃ to efficiently saccharify millet starch, forming the sweet base. In the flavor fermentation stage, yeast is guided at 22-26℃ to synthesize esters and higher alcohols, forming a complex fermented aroma, simultaneously achieving uniform flavor dispersion and natural texture improvement. This invention, through the synergistic effect of staged solid-state fermentation and wet micro-processing, constructs a bread quality improvement system from three dimensions: starch gradient conversion, synergistic generation of flavor microorganisms, and natural texture improvement. It solves the problems of thin flavor layers, insufficient starch nutrient conversion, and reliance on chemical additives for texture improvement in traditional bread fermentation processes. This results in bread with excellent performance in terms of natural flavor, nutritional digestibility, and soft and stable texture, meeting consumer demand for naturally fermented flavored staple bread and clean-label products. Detailed Implementation

[0030] 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.

[0031] The raw materials used in the embodiments and comparative examples of this invention are all commercially available products and have not undergone further purification or processing. Specifically, the millet is commercially available new-harvest millet from the current year, and the yeast is commercially available sweet wine yeast (Rhizopus viable count ≥1×10⁻⁶). 5 CFU / g, yeast viable count ≥1×10⁻⁶ 6 (CFU / g), the flour is a blend of commercially available high-gluten wheat flour and low-gluten wheat flour in a mass ratio of 2:1, and the yeast is commercially available high-activity dry yeast.

[0032] Example 1

[0033] This embodiment provides a fermented bread and its fermentation method, specifically including the following:

[0034] The fermentation method for the fermented bread includes the following steps:

[0035] After steaming, millet is mixed with yeast and fermented in stages to obtain millet fermented product. The staged solid-state fermentation includes saccharification fermentation at 28°C and 80% humidity for 24 hours, followed by flavor fermentation at 22°C and 65% humidity for 36 hours.

[0036] The fermented millet material is subjected to wet micronization to obtain fermented millet paste;

[0037] Fermented millet paste, flour, yeast, and water are mixed and kneaded into dough. After shaping and proofing, the dough is steamed to obtain fermented bread.

[0038] The ratio of millet to yeast is 100:1, and the moisture content of the steamed millet is 55%. The wet micronization process uses a colloid mill to produce a fermented millet paste with a fineness of 80 mesh. The ratio of fermented millet paste, flour, yeast, and water is 40:60:0.5:10. The proofing process is carried out at 34℃ and 80% humidity for 40 minutes. The steaming process involves steaming over high heat in boiling water for 18 minutes.

[0039] The millet is steamed using normal pressure steam for 20 minutes to ensure that the millet is fully gelatinized and the grains remain intact.

[0040] The stirring method for the saccharification and fermentation is as follows: stirring is performed once every 4 hours, and each stirring time is 3 minutes; no stirring is performed during the flavor fermentation, and the mixture is kept still.

[0041] Before mixing the millet with the yeast, the process also includes cooling and breaking up the steamed millet to make it into discrete granules, and then cooling it to 28°C.

[0042] Before the wet micronization process, the following steps are also included: solid-liquid separation of the millet fermentation material to obtain fermentation broth and fermented millet particles; vacuum concentration of the fermentation broth at 40°C to 1 / 3 of its original volume to obtain fermentation concentrate; wet micronization of the fermented millet particles, followed by merging with the fermentation concentrate to obtain fermented millet slurry.

[0043] Example 2

[0044] This embodiment provides a fermented bread and its fermentation method, specifically including the following:

[0045] The fermentation method for the fermented bread includes the following steps:

[0046] After steaming, millet is mixed with yeast and fermented in stages to obtain millet fermented product. The staged solid-state fermentation includes saccharification fermentation at 32℃ and 95% humidity for 12 hours, followed by flavor fermentation at 26℃ and 80% humidity for 12 hours.

[0047] The fermented millet material is subjected to wet micronization to obtain fermented millet paste;

[0048] Fermented millet paste, flour, yeast, and water are mixed and kneaded into dough. After shaping and proofing, the dough is steamed to obtain fermented bread.

[0049] The ratio of millet to yeast is 300:1, and the moisture content of the steamed millet is 65%. The wet micronization process uses a wet ultrafine pulverizer to produce a fermented millet paste with a fineness of 200 mesh. The ratio of fermented millet paste, flour, yeast, and water is 60:40:1.5:25. The proofing process is carried out at 38℃ and 90% humidity for 70 minutes. The steaming process involves steaming over high heat in boiling water for 25 minutes.

[0050] The millet is steamed using normal pressure steam for 35 minutes to ensure that the millet is fully gelatinized and the grains remain intact.

[0051] The stirring method for the saccharification and fermentation is as follows: stirring is performed once every 6 hours, and each stirring time is 8 minutes; no stirring is performed during the flavor fermentation, and the mixture is kept still.

[0052] Before mixing the millet with the yeast, the process also includes cooling and breaking up the steamed millet to make it into discrete granules, and then cooling it to 35°C.

[0053] Before the wet micronization process, the following steps are also included: solid-liquid separation of the millet fermentation material to obtain fermentation broth and fermented millet particles; vacuum concentration of the fermentation broth at 55°C to 1 / 2 of its original volume to obtain fermentation concentrate; wet micronization of the fermented millet particles, followed by merging with the fermentation concentrate to obtain fermented millet slurry.

[0054] Example 3

[0055] This embodiment provides a fermented bread and its fermentation method, specifically including the following:

[0056] The fermentation method for the fermented bread includes the following steps:

[0057] After steaming, millet is mixed with yeast and fermented in stages to obtain millet fermented product. The staged solid-state fermentation includes saccharification fermentation for 18 hours at 30°C and 88% humidity, followed by flavor fermentation for 24 hours at 24°C and 72% humidity.

[0058] The fermented millet material is subjected to wet micronization to obtain fermented millet paste;

[0059] Fermented millet paste, flour, yeast, and water are mixed and kneaded into dough. After shaping and proofing, the dough is steamed to obtain fermented bread.

[0060] The ratio of millet to yeast is 200:1, and the moisture content of the steamed millet is 60%. The wet micronization process uses a colloid mill to produce a fermented millet paste with a fineness of 140 mesh. The ratio of fermented millet paste, flour, yeast, and water is 50:50:1.0:18. The proofing process is carried out at 36℃ and 85% humidity for 55 minutes. The steaming process involves steaming over high heat in boiling water for 22 minutes.

[0061] The millet is steamed using normal pressure steam for 28 minutes to ensure that the millet is fully gelatinized and the grains remain intact.

[0062] The stirring method for the saccharification and fermentation is as follows: stirring is performed once every 5 hours, and each stirring time is 5 minutes; during the flavor fermentation, stirring is not performed, and the mixture is kept still.

[0063] Before mixing the millet with the yeast, the process also includes cooling and breaking up the steamed millet to make it into discrete granules, and then cooling it to 32°C.

[0064] Before the wet micronization process, the following steps are also included: solid-liquid separation of the millet fermentation material to obtain fermentation broth and fermented millet particles; vacuum concentration of the fermentation broth at 48°C to 1 / 2.5 of its original volume to obtain fermentation concentrate; wet micronization of the fermented millet particles, followed by merging with the fermentation concentrate to obtain fermented millet slurry.

[0065] Comparative Example 1

[0066] This comparative example provides a fermented bread and its fermentation method, specifically including the following:

[0067] After steaming, millet is mixed with yeast and subjected to conventional constant temperature solid-state fermentation to obtain millet fermented product; wherein, conventional constant temperature solid-state fermentation is carried out at 30°C and 88% humidity for 42 hours (the total time is the same as in Example 3).

[0068] The remaining steps and parameters are the same as in Example 3.

[0069] Comparative Example 2

[0070] This comparative example provides a fermented bread and its fermentation method, specifically including the following:

[0071] Millet was first saccharified and fermented at 30°C and 88% humidity for 18 hours, and then flavored at 24°C and 72% humidity for 24 hours to obtain millet fermented material (fermentation steps are the same as in Example 3). The millet fermented material was dried and then dry-pulverized to 140 mesh to obtain fermented millet flour. The fermented millet flour, flour, yeast and water were mixed and kneaded into dough (the proportions of each component are the same as in Example 3). After shaping and proofing, the dough was steamed to obtain fermented bread.

[0072] Comparative Example 3

[0073] This comparative example provides a fermented bread and its fermentation method, specifically including the following:

[0074] Millet was pulverized and sieved through a 100-mesh sieve to obtain millet flour, which was set aside. Lactobacillus plantarum powder was dissolved in sterile water under sterile conditions and activated and cultured on MRS medium to obtain lactic acid bacteria solution. The supernatant medium was discarded by centrifugation, and the bacterial sludge was retained and washed with physiological saline. Sterile water of the same volume as the supernatant medium was added to obtain lactic acid bacteria fermentation product. The lactic acid bacteria fermentation product and millet flour were mixed at a mass ratio of 1:1 and cultured at 37℃ for 24 hours to obtain millet sour dough. The millet sour dough, flour, yeast and water were mixed at a mass ratio of 50:50:1.0:18 and kneaded into dough (the amount of flour and yeast was the same as in Example 3). The dough was proofed at 37℃ for 60 minutes and then steamed over high heat for 22 minutes.

[0075] Comparative Example 4

[0076] This comparative example provides a fermented bread and its fermentation method. The only difference from Example 3 is that the bread is turned over once every 5 hours during the flavor fermentation, and each turning time is 5 minutes. That is, the same intermittent turning operation is used for both saccharification fermentation and flavor fermentation.

[0077] Sensory quality, textural properties, and storage stability of the fermented breads in Examples 1-3 and Comparative Examples 1-4 were tested, and the results are shown in Table 1.

[0078] The flavor complexity score detection in the sensory quality detection specifically includes the following steps:

[0079] After steaming and naturally cooling to room temperature, bread samples were sensory evaluated by 10 trained sensory evaluators. The evaluation dimensions included fermentation aroma layering, ester aroma intensity, alcohol aroma intensity, organic acid harmony, and overall flavor persistence. Each item was scored from 0 to 10, with 0 indicating no feature and 10 indicating a highly significant feature. The sum of the scores for each item was taken as the total flavor complexity score, with a maximum score of 50.

[0080] The sensory quality testing, specifically the sweetness naturalness score testing, includes the following steps:

[0081] The 10 sensory evaluators chewed and tasted the bread samples to evaluate whether the sweetness had a natural aftertaste derived from starch saccharification, in order to distinguish it from the single sweetness of added sucrose. A scoring system of 0 to 10 was used, with 0 indicating a harsh and monotonous sweetness with no aftertaste, and 10 indicating a mellow and natural sweetness with a long-lasting aftertaste. The average score was taken.

[0082] The sensory quality testing, specifically the bread crumb texture score testing, includes the following steps:

[0083] The bread samples were cut horizontally in the middle, and the 10 sensory evaluators visually observed the uniformity of the pores, the consistency of the pore wall thickness, and the presence of large pores in the cross-section of the bread core. A scoring system of 0 to 10 was used, with 0 indicating a coarse texture and uneven pore size, and 10 indicating an extremely fine texture and uniform, spongy pores. The average score was taken.

[0084] The hardness testing in the textural property testing specifically includes the following steps:

[0085] Two hours after steaming and naturally cooling to room temperature, the bread samples were cut into cubes with sides of 25 mm from the bread core. TPA tests were performed using a texture analyzer with a P / 36R cylindrical probe. The speed was 1.0 mm / s before testing, 1.0 mm / s during testing, and 1.0 mm / s after testing. The compression ratio was 50%, and the trigger force was 5 g. The hardness value (unit: g) was recorded. Each group of samples was tested in parallel for 6 times, and the average value was taken.

[0086] The elasticity test in the textural property detection specifically includes the following steps:

[0087] In the above TPA test, the elastic value was recorded. The elasticity was the ratio of the recovery height after the second compression to the deformation amount after the first compression. Each group of samples was tested in parallel for 6 times, and the average value was taken.

[0088] The storage stability test, specifically the 72-hour softness retention rate test, includes the following steps:

[0089] After steaming, the bread is naturally cooled to room temperature, then sealed in a food-grade airtight bag and stored in a constant temperature and humidity chamber at 25°C and 60% relative humidity for 72 hours. Afterward, the hardness value is measured according to the hardness test method described above. Simultaneously, a sample from the same batch that has been steamed and cooled for 2 hours is measured to determine its initial hardness value. The 72-hour softness retention rate is calculated using the formula: "Softness retention rate (%) = (1 - (72h hardness - initial hardness) / initial hardness) × 100%". A higher softness retention rate indicates a smaller increase in hardness during storage and better anti-aging properties.

[0090] Table 1 Product Performance Test Results

[0091] Flavor complexity score (out of 50) 42 45 48 25 44 20 35 Fermented aroma layers 8.5 9.0 9.5 5.0 8.8 4.0 7.0 Ester aroma intensity 8.0 8.8 9.2 4.5 8.5 3.5 6.5 Alcohol aroma intensity 8.2 9.0 9.5 5.0 8.8 4.0 7.0 Organic acid harmony 8.5 9.0 9.8 5.5 9.0 4.5 7.5 Overall flavor persistence 8.8 9.2 10.0 5.0 8.9 4.0 7.0 Sweetness naturalness rating (out of 10) 8.5 9.0 9.5 6.0 8.8 5.0 9.0 Bread crumb texture score (out of 10) 8.8 9.2 9.5 7.5 6.5 7.0 8.5 Initial hardness (g) 1850 1720 1680 2050 1950 2200 1780 elasticity 0.88 0.91 0.92 0.82 0.85 0.80 0.90 72-hour softness retention rate (%) 85 90 92 72 78 65 89

[0092] The technical solutions provided by the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for fermenting bread, characterized in that, Includes the following steps: After steaming, millet is mixed with yeast and subjected to staged solid-state fermentation to obtain millet fermented product. The staged solid-state fermentation includes saccharification fermentation at 28-32°C and 80-95% humidity for 12-24 hours, followed by flavor fermentation at 22-26°C and 65-80% humidity for 12-36 hours. The millet fermentation product was subjected to wet micronization treatment to obtain fermented millet slurry; The fermented millet paste, flour, yeast and water are mixed and kneaded into a dough. After shaping and proofing, the dough is steamed to obtain the fermented bread.

2. The fermentation method for fermented bread according to claim 1, characterized in that, The mass ratio of millet to yeast is (100~300):1, and the moisture content of the millet after steaming is 55%~65%.

3. The fermentation method for fermented bread according to claim 1, characterized in that, The wet micronization process involves using a colloid mill or a wet ultrafine pulverizer to obtain fermented millet slurry with a fineness of 80-200 mesh.

4. The fermentation method for fermented bread according to claim 1, characterized in that, The mass ratio of the fermented millet paste, flour, yeast, and water is (40~60):(40~60):(0.5~1.5):(10~25), and the flour is wheat flour; and / or The proofing process is carried out for 40-70 minutes at a temperature of 34-38°C and a humidity of 80-90%; and / or The steaming process involves placing the food in a pot of boiling water and steaming it over high heat for 18-25 minutes.

5. The fermentation method for fermented bread according to claim 1, characterized in that, The millet is steamed using normal pressure steam for 20-35 minutes to ensure that the millet is fully gelatinized and the grains remain intact.

6. The fermentation method for fermented bread according to claim 1, characterized in that, The yeast starter is a sweet wine yeast starter with a Rhizopus viable count ≥1×10⁻⁶. 5 CFU / g, yeast viable count ≥1×10⁻⁶ 6 CFU / g.

7. The fermentation method for fermented bread according to claim 1, characterized in that, Prior to the wet micronization process, the following steps are also included: The millet fermentation product was subjected to solid-liquid separation to obtain fermentation broth and fermented millet grains; The fermentation broth was vacuum concentrated to 1 / 3 to 1 / 2 of its original volume at 40-55°C to obtain a concentrated fermentation broth. After the fermented millet grains undergo the wet micronization process, they are combined with the fermentation concentrate to obtain the fermented millet slurry.

8. The fermentation method for fermented bread according to claim 1, characterized in that, The stirring method for the saccharification and fermentation is as follows: stir once every 4 to 6 hours, and each stirring time is 3 to 8 minutes; no stirring is performed during the flavor fermentation, and the mixture is kept still.

9. The fermentation method for fermented bread according to any one of claims 1 to 8, characterized in that, Before mixing the millet with the yeast, the process also includes cooling and breaking up the steamed millet to make it into discrete granules, and then cooling it to 28~35℃.

10. A fermented bread, characterized in that, It is made by the fermentation method of any one of claims 1 to 9.