Gluten-free bread based on lactic acid bacteria fermented sour dough and preparation method of gluten-free bread

Abstract

The invention relates to gluten-free bread based on lactic acid bacteria fermented sour dough and a preparation method of the gluten-free bread, and belongs to the technical field of food processing. The gluten-free bread based on lactic acid bacteria fermented sour dough is prepared from the following raw material components in parts by weight: 8 to 40 parts of chickpea sour dough, 0 to 32 parts of chickpea powder, 99 to 101 parts of rice powder, 19 to 21 parts of corn starch, 125 to 135 parts of water, 0.5 to 1.5 parts of salt, 9 to 11 parts of sugar, 2 to 4 parts of yeast, 4 to 6 parts of inulin and 1 to 3 parts of baking powder. The chickpea sour dough prepared through pre-fermentation is used as a biological improver, the internal structure of the bread is constructed, the texture is improved, aging is delayed, and the nutritional value is increased. According to the method, on the premise of not depending on exogenous chemical additives, the sensory quality and the nutritional value of the gluten-free bread are synchronously improved, the comprehensive quality of the bread is systematically optimized, and therefore the multiple purposes of label cleaning, structure improving and nutrient enrichment are achieved.

Description

Technical Field

[0001] This invention relates to a gluten-free bread based on lactic acid bacteria fermented sourdough and its preparation method, belonging to the field of food processing technology. Background Technology

[0002] Gluten intolerance is an autoimmune disease caused by the ingestion of gluten protein, requiring patients to strictly avoid gluten-containing grains and their products. Gluten-free bread, as a staple food alternative for this population, often faces technical bottlenecks in commercial production due to the lack of a gluten network, resulting in low volume, coarse texture, and poor taste. Due to the lack of a gluten protein network, gluten-free bread generally suffers from poor gas-holding capacity, loose texture, easy collapse, and a rough, hard texture. Current technologies mostly rely on exogenous hydrophilic colloids (such as xanthan gum and HPMC) to simulate gluten function, but this method often has limited effectiveness, cannot fully replicate the complex rheological properties of gluten, and may result in an unnatural taste. Furthermore, current gluten-free bread formulas are primarily composed of refined starch, resulting in insufficient levels of core nutrients such as dietary fiber and protein. Simultaneously, existing improvement schemes often require the use of multiple exogenous additives (such as colloids, emulsifiers, enzymes, and acidity regulators), which contradicts consumers' pursuit of clean labels and natural foods.

[0003] Therefore, it is of great significance to develop a method that can significantly improve the texture and effectively enhance the nutritional quality of gluten-free bread through natural biotechnology without relying on or with reduced reliance on multiple chemical additives, so as to produce high-quality gluten-free bread with excellent sensory quality, balanced nutrition and clean label. Summary of the Invention

[0004] To address the technical problems existing in the production of gluten-free bread, such as structural collapse, nutritional imbalance, and excessive use of exogenous additives, this invention provides a gluten-free bread based on lactic acid bacteria fermented sourdough and its preparation method. This invention uses pre-fermented chickpea sourdough (CSD) as a biomodifier, replacing the original chickpea flour in the formula in different proportions. It utilizes natural metabolites such as organic acids, microbial extracellular polysaccharides, and modified proteins produced during sourdough fermentation to construct the bread's internal structure, improve texture, delay aging, and enhance nutritional value. This method achieves simultaneous improvement in the sensory quality and nutritional value of gluten-free bread without relying on exogenous chemical additives (such as hydrocolloids and emulsifiers), systematically optimizing the overall quality of the bread, thereby achieving multiple goals such as clean labeling, structural improvement, and nutritional fortification.

[0005] A gluten-free bread based on lactic acid bacteria fermented sourdough, comprising the following ingredients by weight: 8-40 parts chickpea sourdough, 0-32 parts chickpea flour, 99-101 parts rice flour, 19-21 parts corn starch, 125-135 parts water, 0.5-1.5 parts salt, 9-11 parts sugar, 2-4 parts yeast, 4-6 parts inulin, and 1-3 parts baking powder.

[0006] Preferably, by weight, the gluten-free bread comprises the following ingredients: 15-17 parts chickpea sourdough, 23-25 ​​parts chickpea flour, 99-101 parts rice flour, 19-21 parts corn starch, 125-135 parts water, 0.5-1.5 parts salt, 9-11 parts sugar, 2-4 parts yeast, 4-6 parts inulin, and 1-3 parts baking powder.

[0007] In the above technical solution, the chickpea sourdough is prepared by the following method: chickpea flour is mixed with distilled water, inoculated with a suspension of Lactobacillus plantarum and mixed thoroughly, and then allowed to ferment.

[0008] Furthermore, the mass ratio of chickpea flour to distilled water is 1.0:3.0~3.5.

[0009] Furthermore, the fermentation conditions are as follows: fermentation at 36-38°C for 0.3-0.4 h.

[0010] Furthermore, the concentration of the *Lactobacillus plantarum* suspension is 10. 6 ~10 8 CFU / mL, inoculation amount is 5%~7%.

[0011] Furthermore, the *Lactobacillus plantarum* bacterial suspension was prepared as follows: *Lactobacillus plantarum* LB-1 was inoculated into MRS liquid medium and cultured at 36-38℃ for 24-25 h. After continuous subculturing to the stationary phase, the cells were collected by centrifugation at 4000-4100 × g for 5-6 min, washed twice with sterile distilled water, and resuspended to obtain a concentration of 10%. 6 ~10 8 CFU / mL bacterial suspension.

[0012] Another object of the present invention is to provide a method for preparing the above-mentioned gluten-free bread, wherein chickpea sourdough, chickpea flour, rice flour, corn starch, water, salt, sugar, yeast, inulin, and baking powder are mixed evenly in a certain proportion to obtain a batter; the batter is then transferred to a baking mold, agitated to release air, proofed, and baked to obtain the bread.

[0013] Preferably, the ingredients are mixed using a dough mixer for 4 to 6 minutes.

[0014] Furthermore, the proofing conditions are as follows: proofing for 15 to 25 minutes at a temperature of 37 to 39°C and a relative humidity of 80% to 90%.

[0015] Preferably, the proofing conditions are 20 minutes of proofing at a temperature of 38°C and a relative humidity of 85%.

[0016] Furthermore, the baking conditions are baking at 185~195℃ for 25~35 min.

[0017] Preferably, the baking conditions are baking at 190°C for 30 minutes.

[0018] The beneficial effects of this invention are: (1) Optimization of specific volume and internal structure: By controlling the amount of chickpea sourdough (CSD) added within a specific range, the specific volume of bread can be effectively increased. The synergistic effect of functional components (modified protein, dietary fiber, etc.) in CSD and fermentation metabolites (extracellular polysaccharide EPS, organic acids) jointly constructs a stable three-dimensional support network, which significantly enhances the gas holding capacity of the dough; at the same time, the gas generation and stabilization efficiency in the method described in this invention achieves the best balance, so that the internal pore structure of the bread after baking is uniform and dense, and the texture is soft, effectively overcoming the defects of traditional gluten-free bread that is rough and easy to collapse.

[0019] (2) Reduced baking loss rate: The acidification effect of CSD and the improvement of starch-protein network by other components enhance the water retention and structural integrity of dough, thereby reducing the loss of moisture and flavor substances during baking and reducing the baking loss rate of bread.

[0020] (3) Achieving nutritional fortification and clean labeling to meet the needs of healthy consumption: Chickpeas are rich in protein, dietary fiber, vitamins and minerals. By adding them in the form of CSD, not only are these basic nutrients retained, but the fermentation process can also produce beneficial metabolites. In addition, this invention uses the multifunctional metabolites (such as EPS as a natural colloid and organic acids as a natural modifier) ​​generated by CSD, a natural biological modifier, to improve the quality of bread. This makes it possible to reduce or eliminate the use of exogenous hydrophilic colloids (such as xanthan gum), emulsifiers, enzymes and other chemical additives in the formula, which meets the market's pursuit of "clean label" and natural food.

[0021] In summary, this invention provides an efficient, natural, and multifunctional method for preparing gluten-free bread by introducing a specific proportion of chickpea sourdough (CSD) to replace part of the original chickpea flour. This method not only significantly improves upon the shortcomings of gluten-free bread, such as small volume, poor texture, and nutritional imbalance, but also greatly aligns with the industry trend towards clean labeling, demonstrating a very broad application prospect. Attached Figure Description

[0022] Figure 1 The graph shows the specific volume results of gluten-free bread obtained in Examples 1-5 and Comparative Example 1.

[0023] Figure 2 The graph shows the baking loss rate of gluten-free bread obtained in Examples 1-5 and Comparative Example 1.

[0024] Figure 3 The images show the AF results of gluten-free bread obtained in Examples 1-5 and Comparative Example 1.

[0025] Figure 4 The diagram shows the structural diagrams of the gluten-free bread cores obtained in Examples 1-5 and Comparative Example 1. Detailed Implementation

[0026] The following non-limiting embodiments are intended to enable those skilled in the art to more fully understand the invention, but do not limit the invention in any way.

[0027] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; the reagents and materials described are commercially available unless otherwise specified.

[0028] Example 1 A method for preparing gluten-free bread based on lactic acid bacteria fermented sourdough includes the following steps: (1) Preparation of chickpea sourdough: Lactobacillus plantarum LB-1 was inoculated into MRS liquid medium (de Man, Rogosa and Sharpe medium) and cultured at 37℃ for 24 h. After continuous subculturing to the stationary phase, the cells were collected by centrifugation at 4000 × g for 5 min, washed twice with sterile distilled water, and resuspended to obtain a concentration of 10. 7 The bacterial suspension at CFU / mL (verified by plate count method) was prepared by mixing chickpea flour and distilled water at a mass ratio of 4:13, inoculating with 6% (v / w) of the above bacterial suspension and mixing thoroughly, and fermenting at 37°C for 24 h.

[0029] (2) Mixing ingredients: Take 8 g of chickpea sourdough, 32 g of chickpea flour, 100 g of rice flour, 20 g of corn starch, 130 g of water, 1 g of salt, 10 g of sugar, 3 g of yeast, 5 g of inulin and 2 g of baking powder and mix them in a dough mixer for 5 minutes to get a batter. (3) Preparation of gluten-free bread: The batter was transferred to a baking mold, and after being shaken to release the air, it was placed in a proofing box and proofed for 20 min at 38℃ and 85% relative humidity. After proofing, it was baked in an industrial oven at 190℃ for 30 min to obtain gluten-free bread with a chickpea sourdough content of 5% of the total amount of chickpea sourdough, chickpea flour, rice flour and corn starch.

[0030] Example 2 The difference between this embodiment and embodiment 1 is that in step (2), 16 g of chickpea sourdough, 24 g of chickpea flour, 100 g of rice flour, 20 g of corn starch, 130 g of water, 1 g of salt, 10 g of sugar, 3 g of yeast, 5 g of inulin, and 2 g of baking powder are used. The remaining operations are the same as in embodiment 1. Finally, gluten-free bread is obtained with the amount of chickpea sourdough added accounting for 10% of the total amount of chickpea sourdough, chickpea flour, rice flour and corn starch.

[0031] Example 3 The difference between this embodiment and embodiment 1 is that in step (2), 25 g of chickpea sourdough, 15 g of chickpea flour, 100 g of rice flour, 20 g of corn starch, 130 g of water, 1 g of salt, 10 g of sugar, 3 g of yeast, 5 g of inulin, and 2 g of baking powder are used. The remaining operations are the same as in embodiment 1. Finally, gluten-free bread is obtained with the amount of chickpea sourdough added accounting for 15% of the total amount of chickpea sourdough, chickpea flour, rice flour and corn starch.

[0032] Example 4 The difference between this embodiment and embodiment 1 is that in step (2), 32 g of chickpea sourdough, 8 g of chickpea flour, 100 g of rice flour, 20 g of corn starch, 130 g of water, 1 g of salt, 10 g of sugar, 3 g of yeast, 5 g of inulin, and 2 g of baking powder are used. The remaining operations are the same as in embodiment 1. Finally, gluten-free bread is obtained with the amount of chickpea sourdough added accounting for 20% of the total amount of chickpea sourdough, chickpea flour, rice flour and corn starch.

[0033] Example 5 The difference between this embodiment and embodiment 1 is that in step (2), 40 g of chickpea sourdough, 0 g of chickpea flour, 100 g of rice flour, 20 g of corn starch, 130 g of water, 1 g of salt, 10 g of sugar, 3 g of yeast, 5 g of inulin, and 2 g of baking powder are used. The remaining operations are the same as in embodiment 1. Finally, gluten-free bread is obtained with the amount of chickpea sourdough added accounting for 25% of the total amount of chickpea sourdough, chickpea flour, rice flour and corn starch.

[0034] Comparative Example 1 The difference between this comparative example and Example 1 is that in step (2), 0 g of chickpea flour, 140 g of rice flour, 20 g of corn starch, 130 g of water, 1 g of salt, 10 g of sugar, 3 g of yeast, 5 g of inulin, and 2 g of baking powder are used. All other operations are the same as in Example 1, and gluten-free bread with 0% chickpea sourdough is finally obtained.

[0035] The effect of different amounts of sourdough added on the specific volume of gluten-free bread: The specific volume of the gluten-free breads obtained in Examples 1-5 and Comparative Example 1 was determined using the following method: According to GB / T20981—2007 "Bread", a sample of bread to be tested was weighed and placed in a container of a certain volume. Small granular filler (millet or rapeseed) was added to the container, completely covering the bread sample and shaking to compact it. The filler was leveled with a ruler, the bread was removed, and the filler volume was measured in a graduated cylinder. The volume of the bread was obtained by subtracting the volume of the filler from the volume of the container. The specific volume of the bread was calculated using the formula S=V / m, where S is the specific volume of the bread (mL / g), V is the volume of the bread (mL), and m is the mass of the bread (g). The results are shown below. Figure 1 It can be seen that the amount of chickpea sourdough (CSD) added is a key factor affecting the specific volume of gluten-free bread. An addition of 10% allows the bread to reach its peak specific volume (2.22 mL / g), at which point chickpea protein, dietary fiber, and fat form an optimal synergistic effect with the metabolic activity of *Lactobacillus plantarum* LB-1. On one hand, at this ratio, chickpea protein and fiber effectively construct a stable bread framework and optimize the dough's gas-holding capacity; on the other hand, CO2, organic acids, and extracellular polysaccharides (EPS) produced by the strain's metabolism jointly promote efficient gas generation and stable gas encapsulation. If the addition amount is too low, the functional components and microorganisms will not interact sufficiently; if it is too high, the structure may be weakened due to excessive acidification or fermentation. Therefore, an addition amount of 10% is key to achieving the optimal balance between gas production and gas-holding efficiency, thereby obtaining maximum specific volume, a fine texture, and a soft consistency.

[0036] The effect of different amounts of sourdough added on the baking loss rate of gluten-free bread: The baking loss rate of the gluten-free breads obtained in Examples 1-5 and Comparative Example 1 was determined using the following method: After baking, the bread was cooled to room temperature for 1 hour and its mass was measured using an electronic balance. This mass was recorded as the bread weight. The dough weight was also directly weighed using an electronic balance and recorded. The baking loss rate (%) was the ratio of the bread weight to the dough weight before baking. Results are shown below. Figure 2It can be seen that the baking loss rate first decreases and then increases with the increase of CSD addition. When the addition amount is 10%, the baking loss rate is the lowest (5.98%), showing the best baking performance. The reason for this may be that an appropriate amount (10%) of CSD, through its acidification effect, effectively improves the network structure of starch and protein in the dough, enhances the gas retention and water retention of the dough, thereby reducing the loss of moisture and volatile substances during baking.

[0037] The effect of different amounts of sourdough added on the color of gluten-free bread: The color of the gluten-free breads obtained in Examples 1-5 and Comparative Example 1 was measured using the following method: a high-precision spectrophotometer was used to measure the color of the crust (top center of the bread) and the core. The results are shown in Table 1. It can be seen that, in terms of color, as the amount of chickpea sourdough (CSD) added increases, the overall brightness of the gluten-free bread decreases, and the bread color gradually deepens. Among them, the 10% addition amount showed the most balanced performance: the bread core and crust maintained a high brightness, with L values ​​of 43.93 and 44.88, respectively, while moderately enhancing the yellow tone (b value of the crust reached 4.91) and controlling the increase of the red tone (a value of the crust was only 0.32). This color effect is mainly due to the optimal balance between the natural pigments in chickpeas, the fermentation metabolites of sourdough, and the Maillard reaction during baking at this addition ratio, which both preserves the brightness and enhances the visual appeal of the golden color of the product.

[0038] Table 1. Effects of different amounts of chickpea sourdough dough added on the color of gluten-free bread.

[0039] The effect of different amounts of sourdough added on the crumb structure of gluten-free bread: The core structure of the gluten-free breads obtained in Examples 1-5 and Comparative Example 1 was measured using the following method: A scanner was used to scan the cross-section of the bread core, and ImageJ software was used to process the scanned images to obtain a binary representation of the bread core and related parameters. The area fraction (AF) represents the percentage of the pore area to the total cross-sectional area. Results are shown below. Figure 3 and Figure 4The results show that the amount of chickpea sourdough added has a significant impact on the surface area fraction (AF%) of gluten-free bread. As the addition amount increases from 5% to 10%, the AF value rises from 32.682% to 40.810%, indicating that an appropriate amount of CSD can improve the dough network structure and gas retention. However, when the addition amount continues to increase to 15%, 20%, and 25%, the AF value decreases to 37.230%, 35.428%, and 28.483%, respectively. This trend is because excessive CSD leads to excessive acidity and compositional imbalance in the system, thereby weakening the stability of the starch-colloid network and resulting in a decrease in gas retention. Therefore, a 10% addition amount of sourdough is the optimal ratio for forming a uniform and fine pore structure.

Claims

1. A gluten-free bread based on lactic acid bacteria fermented sourdough, characterized in that: By weight, it includes the following ingredients: 8-40 parts chickpea sourdough, 0-32 parts chickpea flour, 99-101 parts rice flour, 19-21 parts corn starch, 125-135 parts water, 0.5-1.5 parts salt, 9-11 parts sugar, 2-4 parts yeast, 4-6 parts inulin, and 1-3 parts baking powder.

2. The gluten-free bread according to claim 1, characterized in that: By weight, it includes the following ingredients: 15-17 parts chickpea sourdough, 23-25 ​​parts chickpea flour, 99-101 parts rice flour, 19-21 parts corn starch, 125-135 parts water, 0.5-1.5 parts salt, 9-11 parts sugar, 2-4 parts yeast, 4-6 parts inulin, and 1-3 parts baking powder.

3. The gluten-free bread according to claim 1, characterized in that: The chickpea sourdough is prepared by mixing chickpea flour with distilled water, inoculating with a suspension of Lactobacillus plantarum and mixing thoroughly, and allowing it to ferment.

4. The gluten-free bread according to claim 3, characterized in that: The mass ratio of chickpea flour to distilled water is 1.0:3.0~3.

5.

5. The gluten-free bread according to claim 3, characterized in that: The fermentation conditions are 36-38℃ for 0.3-0.4 h.

6. The gluten-free bread according to claim 3, characterized in that: The concentration of the *Lactobacillus plantarum* suspension is 10. 6 ~10 8 CFU / mL, inoculation amount is 5%~7%.

7. The gluten-free bread according to claim 6, characterized in that: The *Lactobacillus plantarum* bacterial suspension was prepared as follows: *Lactobacillus plantarum* LB-1 was inoculated into MRS liquid medium and cultured at 36-38℃ for 24-25 h. After continuous subculturing to the stationary phase, the cells were collected by centrifugation at 4000-4100 × g for 5-6 min, washed twice with sterile distilled water, and resuspended to obtain a concentration of 10%. 6 ~10 8 CFU / mL bacterial suspension.

8. A method for preparing gluten-free bread according to any one of claims 1 to 7, characterized in that: Mix chickpea sourdough, chickpea flour, rice flour, cornstarch, water, salt, sugar, yeast, inulin, and baking powder in the specified proportions to obtain a batter; transfer the batter to a baking mold, agitate to release air, let it rise, and then bake.

9. The preparation method according to claim 8, characterized in that: The proofing conditions are as follows: proofing for 15 to 25 minutes at a temperature of 37 to 39°C and a relative humidity of 80% to 90%.

10. The preparation method according to claim 8, characterized in that: The baking conditions are as follows: baking at 185~195℃ for 25~35 minutes.

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