A gluten-free bread and a method for preparing the same

Abstract

This invention discloses a gluten-free bread and its preparation method, belonging to the field of fermented grain product processing technology. The gluten-free bread of this invention comprises, by weight, 90-100 parts rice flour, 0-10 parts rice protein, 1-4 parts edible colloid, 0.5-3 parts yeast, 0-10 parts white sugar, 0-2 parts salt, 3-10 parts oil, and 75-100 parts water; wherein the rice protein has a protein content of 70-90%, and the edible colloid includes hydroxypropyl methylcellulose (HPMC) and propylene glycol alginate (PGA). This invention utilizes hydroxypropyl methylcellulose, propylene glycol alginate, and rice protein to form a gluten-free dough with fermentation extensibility and structural stability, preparing gluten-free bread with good sensory properties and texture, overcoming the disadvantages of small specific volume and unstable tissue structure in gluten-free bread.

Description

Technical Field

[0001] This invention relates to a gluten-free bread and its preparation method, belonging to the field of fermented grain product processing technology. Background Technology

[0002] Gluten gives bread its good gas-holding capacity and texture, and is a major component contributing to its appealing appearance and taste. However, gluten can cause intestinal immune disorders in people with celiac disease, and a strict gluten-free diet is currently the only recognized effective treatment for celiac disease. Therefore, gluten-free bread provides a staple food option for people with celiac disease.

[0003] Commonly used gluten-free ingredients include rice flour and cereal starches, which are characterized by the absence of gluten protein. However, when using these gluten-free ingredients to make bread, the dough cannot form a network structure during processing, making it difficult to shape and resulting in poor gas retention, ultimately leading to bread that easily collapses. Furthermore, the high starch content in gluten-free ingredients causes a less dense bread crumb structure, resulting in bread that is prone to crumbling. The poor sensory quality of existing gluten-free bread reduces consumer acceptance. Therefore, improving the shapeability and sensory quality of gluten-free bread is key to its industrialization. Summary of the Invention

[0004] To improve the appearance and texture of gluten-free bread, this invention provides a gluten-free bread and its preparation method, aiming to improve the gas-holding capacity and stability of gluten-free dough, and obtain gluten-free bread with large specific volume, stable texture and good taste.

[0005] First, the present invention provides a gluten-free bread, which comprises, by weight, 90-100 parts rice flour, 0-10 parts rice protein, 1-4 parts edible colloid, 0.5-3 parts yeast, 0-10 parts white sugar, 0-2 parts salt, 3-10 parts oil, and 75-100 parts water.

[0006] Preferably, the rice flour is japonica rice flour, and the proportion is preferably 95-100 parts.

[0007] Preferably, the rice protein content is 70-90%, and the rice protein content is preferably 0-5 parts.

[0008] Preferably, the edible colloid comprises hydroxypropyl methylcellulose (HPMC) and propylene glycol alginate (PGA), wherein the mass ratio of propylene glycol alginate to hydroxypropyl methylcellulose is (0-1.0):(1.0-3.0).

[0009] Preferably, the oil is a vegetable oil.

[0010] Preferably, by weight, the bread comprises 95-97 parts rice flour, 3-5 parts rice protein, 1.2-3 parts edible colloid, 1-2 parts yeast, 3-6 parts white sugar, 0.5-1.5 parts salt, 6-8 parts oil, and 80-97.5 parts water.

[0011] Secondly, the present invention provides a method for preparing gluten-free bread, comprising the following steps: kneading, dividing and shaping, proofing the dough and baking.

[0012] Preferably, the kneading process involves mixing rice flour, rice protein, edible colloid, yeast, sugar, and salt from the gluten-free bread ingredient powder evenly, adding water, kneading at low speed for 1-3 minutes, kneading at medium speed for 2-4 minutes, adding oil, and then kneading at high speed for 3-5 minutes to obtain a gluten-free dough.

[0013] Preferably, the low-speed kneading refers to a kneading speed of 45-65 r / min, more preferably 1-2 min, and more preferably 2 min; the medium-speed kneading refers to a kneading speed of 80-100 r / min, more preferably 2-3 min, and more preferably 3 min; the high-speed mixing refers to a kneading speed of 110-130 r / min, more preferably 4 min.

[0014] Preferably, the segmentation and shaping refers to dividing the gluten-free dough obtained after kneading into dough pieces of 50-180g each, shaping them, and placing them into molds of corresponding sizes.

[0015] Preferably, the dough proofing involves placing the shaped dough into a fermentation box, and the proofing conditions are as follows: temperature 30-40℃, relative humidity 80-100%, and time 40-70 min; more preferably, the temperature is 35-38℃, relative humidity is 85-95%, and time is 45-60 min.

[0016] Preferably, the baking involves placing the proofed dough in an oven at an upper heat temperature of 150–190°C and a lower heat temperature of 160–200°C for 25–40 minutes; more preferably, the upper heat temperature is 160–170°C, the lower heat temperature is 165–175°C, and the baking time is 30–35 minutes.

[0017] The beneficial effects of this invention are:

[0018] First, this invention provides a gluten-free bread and its preparation method, resulting in a gluten-free bread with a simple preparation process and good sensory and texture qualities. The addition of colloids and rice protein improves the workability of the dough and makes it easier to shape; it also improves the sensory qualities of the gluten-free bread, such as its specific volume, and enhances its texture qualities, such as its elasticity and cohesiveness.

[0019] Secondly, this invention improves the texture of gluten-free bread by adding rice protein. Rice protein has low allergenicity, good emulsifying, foaming and bubble stability, which can improve the elasticity, cohesiveness and other texture characteristics of gluten-free bread, improve the color and nutritional quality of gluten-free bread, and has lower allergenicity compared with commonly used soy protein and animal protein.

[0020] Third, based on HPMC as a gluten network structure, this invention adds PGA. PGA can play a good stabilizing and emulsifying role, which can be used to improve the resilience and rigidity of gluten-free bread, stabilize the gel network structure formed by hydroxypropyl methylcellulose in gluten-free bread, and ultimately enhance the texture strength of gluten-free bread, further improving the sensory and textural quality of gluten-free bread. Attached Figure Description

[0021] Figure 1 This is a cross-sectional view of gluten-free bread with different colloids added in Example 1 of the present invention, wherein Xt is xanthan gum, CMC is sodium carboxymethyl cellulose, KGM is konjac gum, PGA is propylene glycol alginate, and HPMC is hydroxypropyl methyl cellulose.

[0022] Figure 2 The images show scanning electron microscope (SEM) cross-sections of gluten-free breads with different colloid additions in Example 1 of this invention. 1, 2, 3, 4, 5 and 6 represent gluten-free breads with rice protein added at the following amounts: control with no colloid addition, 3 parts xanthan gum, 1 part sodium carboxymethyl cellulose, 3 parts konjac gum, 3 parts propylene glycol alginate and 2 parts hydroxypropyl methylcellulose, respectively.

[0023] Figure 3 This is a cross-sectional view of gluten-free bread with different protein additions in Example 2 of the present invention, when the addition amount is optimized.

[0024] Figure 4 The fermentation rheological characteristic curves of bread with different amounts of rice protein added in Example 2 of the present invention are shown. Control, RP1, RP2, RP3, RP4 and RP5 are the rice protein added amounts of 0 parts, 2 parts, 3 parts, 4 parts and 5 parts, respectively.

[0025] Figure 5 The curves for Mixolab bread with different water additions in Example 3 of this invention are shown.

[0026] Figure 6 This is a cross-sectional view of two gluten-free breads made by combining HPMC with different proportions of PGA in Example 4 of the present invention.

[0027] Figure 7 Cross-sections of gluten-free bread with PGA additions of 0, 0.2, 0.5, and 1.0 parts. Detailed Implementation

[0028] Method for determining the water absorption rate of dough:

[0029] The optimal water absorption rate of the dough was determined using Mixolab. The test parameters were as follows: target torque value C1 was 0.5 Nm, kneading speed was 120 r / min, dough mass was 90 g, and the test consisted of three stages: the first stage was kneading at a constant temperature of 30℃ for 8 min; the second stage involved increasing the temperature to 90℃ at a rate of 4℃ / min, maintaining it at 90℃ for 7 min, and then decreasing the temperature to 50℃ at a rate of 4℃ / min; the third stage involved maintaining the temperature at 50℃ for 10 min. The optimal water absorption rate of the dough was determined when the torque value during the first stage of kneading was approximately equal to the target torque value C1.

[0030] Methods for determining fermentation rheological properties:

[0031] Using the aforementioned technical solution, gluten-free dough was obtained. 200g of dough was spread evenly in the fermentation tank of a fermentation rheometer and fermented for 180 minutes under the preferred fermentation temperature conditions. The fermentation characteristics were then measured using the fermentation rheometer.

[0032] Specific volume determination method:

[0033] Referring to AACC10-05, the volume of bread was determined using the millet displacement method, and its mass was measured. The specific volume is the ratio of its volume to its mass (mL / g).

[0034] Methods for determining textural properties:

[0035] The bread was sliced ​​into uniform thicknesses using a slicer, and 30mm diameter circles were cut out. Total textural analysis (TPA) of the bread was then performed using a texture analyzer. The data were processed to obtain textural parameters such as hardness, elasticity, and cohesion. The test conditions were as follows: P35 probe, compression mode, pre-test speed, test speed, and post-test speed all 1mm / s, compression ratio 50%, time interval between two compressions 5s, and trigger force 5g.

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the embodiments of this invention will be further described in detail below with reference to the accompanying drawings. However, the scope of protection of this invention is not limited thereto. Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods; unless otherwise specified, the reagents and materials used in the following embodiments are commercially available.

[0037] Example 1: Selection of Colloids

[0038] This embodiment provides a recipe for preparing gluten-free bread, with the following ingredient powder proportions by weight percentage: 100 parts rice flour, 1-3 parts edible colloid, 2 parts yeast, 5 parts white sugar, 1 part edible salt, 5 parts corn oil, and 90 parts water.

[0039] Mix the above ingredients, except for corn oil and water, evenly to make a mixed powder; add 90 parts of water to the mixed powder, stir at a low speed of 60 r / min for 1 min, stir at a medium speed of 90 r / min for 2 min, then add 5 parts of corn oil and stir at a high speed of 120 r / min for 4 min to obtain a dough.

[0040] The dough is divided and shaped into 90g portions, and then placed into molds.

[0041] After shaping and molding the dough, place it in a proofing box at 38°C and 90% relative humidity for 50 minutes. Then bake it in an oven with top and bottom heat of 170°C and 180°C respectively for 25 minutes. After baking, unmold the bread and cool it at room temperature for 120 minutes to obtain the gluten-free bread.

[0042] The edible colloids included xanthan gum (Xt), carboxymethyl cellulose (CMC), konjac gum (KGM), propylene glycol alginate (PGA), and hydroxypropyl methyl cellulose (HPMC), with corresponding optimized addition amounts of 3 parts, 1 part, 3 parts, 3 parts, and 2 parts, respectively.

[0043] The resulting bread cross-section is as follows Figure 1 As shown in Table 1, the bread quality indicators are as follows. It can be concluded that the selected colloids have the following effect on improving the specific volume of bread: HPMC > PGA > CMC > KGM > Xt. Furthermore, HPMC can significantly improve the specific volume and porosity of bread. Figure 2 SEM results of the gluten-free bread with the added colloids showed that a relatively ordered gel network structure was only found in the gluten-free bread with HPMC. Furthermore, PGA can significantly improve the elasticity, resilience, and other texture qualities of bread; therefore, this invention preferably uses HPMC and PGA to improve the quality of gluten-free bread.

[0044] Table 1. Specific volume and textural properties of gluten-free breads with different colloid additions.

[0045]

[0046] Note: Xt is xanthan gum, CMC is sodium carboxymethyl cellulose, KGM is konjac gum, PGA is propylene glycol alginate, and HPMC is hydroxypropyl methylcellulose. Different letters in the same column represent significant differences (p < 0.05).

[0047] Example 2: Protein Selection

[0048] This embodiment provides a recipe for preparing gluten-free bread. The ingredients are as follows by weight percentage: 95 parts rice flour, 0-10 parts egg white, 2 parts hydroxypropyl methylcellulose, 0.2 parts propylene glycol alginate, 2 parts yeast, 5 parts white sugar, 1 part salt, 5 parts corn oil, and 95 parts water.

[0049] Mix all the ingredients except corn oil and water thoroughly to make a mixed powder;

[0050] Add 95 parts water to the mixed powder, stir at a low speed of 60 r / min for 1 min, stir at a medium speed of 90 r / min for 2 min, then add 5 parts corn oil and stir at a high speed of 120 r / min for 4 min to obtain the dough;

[0051] The dough is divided and shaped into 90g portions, and then placed into molds.

[0052] After shaping and molding the dough, place it in a proofing box at 38°C and 90% relative humidity for 50 minutes. Then bake it in an oven with top and bottom heat of 170°C and 180°C respectively for 25 minutes. After baking, unmold the bread and cool it at room temperature for 120 minutes to obtain the gluten-free bread.

[0053] The proteins mentioned are whole egg protein, egg white protein, and rice protein (RP), and the resulting bread cross-section is as follows: Figure 3 As can be seen, whole egg protein significantly reduced the specific volume of gluten-free bread, while egg white protein and rice protein significantly increased it. However, the gluten-free bread with added egg white protein had a weaker texture and could not form uniform air pockets. In contrast, the gluten-free bread with added rice protein had a texture closer to that of wheat bread; therefore, rice protein was the preferred choice.

[0054] Different gluten-free breads were prepared using different amounts of rice protein added according to the formula of this embodiment. The specific volume and texture changes (Table 1) and fermentation rheological properties of the gluten-free breads with different amounts of rice protein added are shown. Figure 4 As shown in Table 3, 3 parts of rice protein can improve the texture and quality of gluten-free bread without significantly reducing its specific volume. Further increasing the amount of rice protein added will lead to a decrease in the bread's specific volume. The main reason for this phenomenon is that increasing the amount of rice protein will weaken the gel network structure of HPMC to some extent, weakening the dough's skeletal structure and reducing its gas-holding capacity, thus causing a decrease in the bread's specific volume. Therefore, the preferred amount of rice protein added is 3 parts.

[0055] Table 2. Specific volume and textural properties of bread with different amounts of rice protein added.

[0056]

[0057] Note: Control, RP1, RP2, RP3, RP4 and RP5 represent the amount of rice protein added: 0, 2, 3, 4 and 5 parts, respectively.

[0058] Table 3. Fermentation rheological properties of bread with different rice protein addition levels.

[0059]

[0060] Example 3: Determining the Amount of Water Added

[0061] This embodiment provides a recipe for preparing gluten-free bread, with the following ingredient powder proportions by weight percentage: 95 parts rice flour, 3 parts rice protein, 2 parts hydroxypropyl methylcellulose, 2 parts yeast, 5 parts white sugar, 1 part edible salt, 5 parts corn oil, and 75-100 parts water.

[0062] Mix the above raw material powders, excluding corn oil and water, evenly to make a mixed powder;

[0063] Add a certain amount of water to the mixed powder, stir at a low speed of 60 r / min for 1 min, stir at a medium speed of 90 r / min for 2 min, then add 5 parts of corn oil and stir at a high speed of 120 r / min for 4 min to obtain the dough;

[0064] The dough is divided and shaped into 90g portions, and then placed into molds.

[0065] After shaping and molding the dough, place it in a proofing box at 38°C and 90% relative humidity for 50 minutes. Then bake it in an oven with top and bottom heat of 170°C and 180°C respectively for 35 minutes. After baking, unmold the bread and cool it at room temperature for 120 minutes to obtain the gluten-free bread.

[0066] The amount of water added is a crucial factor affecting bread quality. Too little water results in incomplete dough absorption, hindering the formation of a good gluten network, leading to high dough viscosity, limited fermentation and expansion, and a smaller bread volume. Too much water results in excessive moisture in the bread core after baking, making cooling and shaping difficult, resulting in a softer bread texture that is prone to collapse and deformation. Mixolab can be used to determine the optimal water absorption rate of bread dough. For wheat flour dough, the optimal water absorption rate is the amount of water required to achieve a dough torque of 1.1 Nm. However, for gluten-free dough, which lacks gluten proteins and relies on exogenous additives to simulate a gluten-like network structure, the water absorption rate at a dough torque of 1.1 Nm may not necessarily represent the optimal water absorption rate.

[0067] When the water addition amounts were 75 parts, 85 parts, 95 parts, and 95 parts, the kneading curves of the bread with different water addition amounts were measured as follows: Figure 5As shown, when the water content is 75 parts, the torque during dough formation is approximately 1.1 Nm. However, the specific volume results of bread prepared with different water contents indicate that the bread has the highest specific volume when the water content is 95 parts. Figure 6 As shown, the bread looks best at this point.

[0068] Example 4: Effect of Propylene Glycol Alginate Addition on the Quality of Gluten-Free Bread

[0069] This embodiment provides an optimized formula for preparing gluten-free bread. The proportions of the raw materials are as follows (by weight percentage): rice flour, 95 parts; rice protein, 5 parts; HPMC, 2 parts; PGA, 0.2-1.0 parts; yeast, 2 parts; white sugar, 5 parts; edible salt, 1 part; corn oil, 5 parts; and water, 95 parts.

[0070] Mix the above raw material powders, excluding corn oil and water, evenly to make a mixed powder;

[0071] Add 95 parts water to the mixed powder, stir at a low speed of 60 r / min for 1 min, stir at a medium speed of 90 r / min for 2 min, then add 5 parts corn oil and stir at a high speed of 120 r / min for 4 min to obtain the dough;

[0072] The dough is divided and shaped into 90g portions, and then placed into molds.

[0073] The shaped dough was placed in a proofing box at 38°C and 90% relative humidity for 50 minutes, then baked in an oven at 170°C and 180°C for 35 minutes. After baking, the bread was unmolded and cooled at room temperature for 120 minutes to obtain the gluten-free bread.

[0074] When the PGA addition amounts were 0.2 parts, 0.5 parts, and 1.0 parts, the cross-sectional images and quality indicators of the gluten-free bread were as follows: Figure 7 As shown in Table 4, PGA possesses both hydrophilic and lipophilic properties, which is beneficial for improving the stability of the system. As in Example 1, PGA cannot form a gel network structure in the gluten-free bread like HPMC, and its use alone does not improve the specific volume of the gluten-free bread. However, in the presence of HPMC, it can enhance the formation of the gel network structure within the bread, thereby increasing the specific volume. When the addition amount is ≥0.5 parts, the specific volume is significantly improved. Simultaneously, the textural properties data show that PGA increases the elasticity, resilience, and cohesion of baked goods. When the addition amount is ≥0.5 parts, both elasticity and cohesion are significantly improved, resulting in a significant improvement in the texture of the bread. Adding amounts greater than 0.5 parts do not further improve the bread quality; therefore, the preferred addition amount of PGA is 0.5 parts.

[0075] Table 4. Specific volume and textural properties of gluten-free breads blended with HPMC and different proportions of PGA.

[0076]

[0077] Note: Different letters in the same column represent significant differences (p < 0.05).

[0078] Example 5:

[0079] This embodiment provides an optimized formula for gluten-free bread and its preparation method. The raw materials, ingredients, and water content are as follows: rice flour, 95 parts; rice protein, 5 parts; HPMC, 2 parts; PGA, 0.5 parts; yeast, 2 parts; white sugar, 5 parts; salt, 1 part; corn oil, 5 parts; and water, 95 parts.

[0080] Mix the above raw material powders, excluding corn oil and water, evenly to make a mixed powder;

[0081] Add 95 parts water to the mixed powder, stir at a low speed of 45 r / min for 2 min, stir at a medium speed of 100 r / min for 2 min, then add 5 parts corn oil and stir at a high speed of 110 r / min for 4 min to obtain dough; divide the dough into 90g portions and place them into molds;

[0082] The shaped dough was placed in a proofing box at 38°C and 90% relative humidity for 50 minutes, then baked in an oven at 170°C and 180°C for 25 minutes. After baking, the bread was unmolded and cooled to room temperature for 120 minutes to obtain the gluten-free bread.

[0083] The resulting gluten-free bread has a large specific volume, uniform bread pores, dense internal structure, significantly reduced hardness, and improved elasticity and cohesion, resulting in a soft and chewy bread.

[0084] Example 6:

[0085] This embodiment provides an optimized formula for gluten-free bread and its preparation method. The raw materials, ingredients, and water content are as follows: rice flour, 97 parts; rice protein, 3 parts; HPMC, 1.5 parts; PGA, 1 part; yeast, 1.2 parts; white sugar, 6 parts; salt, 1.5 parts; corn oil, 7 parts; and water, 100 parts.

[0086] Mix the above raw material powders, excluding corn oil and water, evenly to make a mixed powder;

[0087] Add 100 parts of water to the mixed powder, stir at a low speed of 65 r / min for 2 min, stir at a medium speed of 100 r / min for 3 min, then add 5 parts of corn oil and stir at a high speed of 130 r / min for 4 min to obtain dough; divide the dough into 90g portions and place them into molds;

[0088] The shaped dough was placed in a proofing box at 35°C and 95% relative humidity for 60 minutes, then baked in an oven at 165°C and 175°C for 35 minutes. After baking, the bread was unmolded and cooled to room temperature for 120 minutes to obtain the gluten-free bread.

[0089] The resulting gluten-free bread has a large specific volume, uniform bread pores, dense internal structure, significantly reduced hardness, and improved elasticity and cohesion, resulting in a soft and chewy bread.

[0090] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A gluten-free bread, characterized by, The gluten-free bread, by weight, comprises the following components: 95-97 parts rice flour, 3-5 parts rice protein, 2 parts hydroxypropyl methylcellulose, 0.5 parts propylene glycol alginate, 1-2 parts yeast, 3-6 parts white sugar, 0.5-1.5 parts salt, 6-8 parts oil, and 95-97.5 parts water; or the gluten-free bread comprises the following components: 95-97 parts rice flour, 3-5 parts rice protein, 1.5 parts hydroxypropyl methylcellulose, 1 part propylene glycol alginate, 1-2 parts yeast, 3-6 parts white sugar, 0.5-1.5 parts salt, 6-8 parts oil, and 95-97.5 parts water.

2. The gluten-free bread according to claim 1, characterized in that, The protein content of the rice protein is 70-90%.

3. The method for preparing gluten-free bread according to claim 1 or 2, characterized in that, The method includes the following steps: kneading the dough, dividing and shaping it, proofing the dough, and baking it.

4. The method for preparing gluten-free bread according to claim 3, characterized in that, The kneading process involves mixing rice flour, rice protein, hydroxypropyl methylcellulose, propylene glycol alginate, yeast, white sugar, and salt from the gluten-free bread flour mix, adding water, kneading at low speed for 1–3 minutes, kneading at medium speed for 2–4 minutes, adding oil, and then kneading at high speed for 3–5 minutes to obtain a gluten-free dough.

5. The method for preparing gluten-free bread according to claim 3, characterized in that, The segmentation and shaping refers to dividing the gluten-free dough obtained after kneading into dough balls of 50-180 g in size, shaping them, and placing them into molds of corresponding sizes.

6. The method for preparing gluten-free bread according to claim 3, characterized in that, The dough proofing process involves placing the shaped dough into a fermentation box, with the following proofing conditions: temperature of 30–40 °C, relative humidity of 80–100%, and time of 40–70 min.

7. The method for preparing gluten-free bread according to claim 3, characterized in that, The baking process involves placing the proofed dough into an oven at an upper heat temperature of 150–190°C and a lower heat temperature of 160–200°C for 25–40 minutes.

8. The method for preparing gluten-free bread according to claim 7, characterized in that, The upper heat temperature is 160-170℃, the lower heat temperature is 165-175℃, and the baking time is 30-35 minutes.

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