A bread digestibility improver and its application in the production of enzymolysis-resistant whole-wheat bread

Abstract

The present invention discloses a bread digestibility improver and its application in the production of enzymolysis-resistant whole-wheat bread, and the field of whole-wheat bread processing. The present invention disperses gluten under alkaline conditions so that the protein chain is fully unfolded and then β-glucan is added, and a highland barley gluten / β-glucan complex is formed by molecular self-assembly to obtain a bread digestibility improver. The obtained bread digestibility improver is mixed with whole-wheat flour and gluten, and the enzymolysis-resistant whole-wheat bread is obtained through the steps of kneading, fermentation, molding, proofing, baking, etc. The present invention regulates the digestibility of starch in whole-wheat bread by adding a bread digestibility improver, greatly improves the resistant starch content in whole-wheat bread, and the obtained bread has a good taste and high nutritional value.

Description

Technical Field

[0001] The invention belongs to the field of whole-wheat bread processing, and particularly relates to a bread digestibility improver and application thereof in the production of enzymolysis-resistant whole-wheat bread. Background Art

[0002] With economic development and social progress, the concept of healthy eating is becoming increasingly popular. People are looking for more natural, sugar-free, and fat-free foods to achieve healthy eating and weight loss. Against this backdrop, baked goods made with whole-wheat flour, such as whole-wheat bread, are gaining popularity among consumers.

[0003] Whole-wheat bread has high nutritional value and is rich in dietary fiber, minerals, vitamins, oligosaccharides, and other bioactive ingredients. However, it suffers from low specific volume, high hardness, rough texture, and high blood sugar levels. These issues have attracted the interest of numerous cereal researchers, and current research focuses on improving whole-wheat bread through the selection and processing of raw materials, optimization of formulations and processing techniques, and the addition of functional biological ingredients such as proteins, hydrophilic colloids, enzymes, and phenolics. Chinese Patent CN 107439633A discloses a composite improver for whole-wheat bread, a whole-wheat bread composition, and whole-wheat bread preparation methods. These improve the quality of whole-wheat bread by adding improvers such as wheat flour, sodium stearoyl lactylate, and α-amylase. Chinese Patent CN 113907112A discloses a bread improver, whole-wheat bread, and a method for preparing whole-wheat bread. By adding emulsifiers, enzyme preparations, and antioxidants, whole-wheat bread has a natural light brown color, a good texture, and a high elasticity.

[0004] Although the above invention can improve the quality of whole wheat bread, it still lacks a method for effectively regulating the GI value of whole wheat bread. In view of the fact that starch is the main factor causing postprandial blood sugar fluctuations, reducing the digestibility of starch is one of the feasible methods to reduce the GI value of food. Studies have shown that non-starch components can inhibit the digestibility of starch, especially protein and β-glucan. Therefore, the present invention adds β-glucan and highland barley protein, so that the two interact with starch to reduce the GI value, thereby forming a low-GI bread suitable for diabetic patients with better sensory properties and texture properties, thereby supplementing the types of food suitable for diabetic patients and effectively solving the problems of severe shortage of low-GI food types on the market and the single product form. Summary of the Invention

[0005] In response to existing technical problems, the present invention provides a bread digestibility improver and its application in the production of enzymolysis-resistant whole-wheat bread. Through the synergistic effect of gluten and β-glucan, the starch digestibility of whole-wheat bread is effectively reduced, the resistant starch content is increased, the nutritional value is improved, and the taste and quality of whole-wheat bread are improved.

[0006] The present invention aims to provide a bread digestibility improver comprising gluten and β-glucan;

[0007] The preparation method of the bread digestibility improver comprises the following steps: dispersing gluten under alkaline conditions to fully unfold the protein chains, adding β-glucan, and forming a gluten / β-glucan complex through molecular self-assembly to form the bread digestibility improver.

[0008] In some embodiments of the present invention, the gluten in the bread digestibility improver is one or more of highland barley, wheat, and oats; and the β-glucan is one or more of highland barley β-glucan, oat β-glucan, and yeast β-glucan.

[0009] In some embodiments of the present invention, the β-glucan is one or more of high, medium and low molecular weight; wherein low molecular weight refers to 1×10 4 -8×10 4 Da, medium molecular weight refers to 1×10 5 -2×10 5 Da, high molecular weight refers to 3×10 5 -5×10 5 Da. Low molecular weight β-glucan is preferred.

[0010] In some embodiments of the present invention, the weight ratio of gluten to β-glucan is 7:2.5.

[0011] In some embodiments of the present invention, the pH range for the opening of the gluten molecular chains is 9.0-10.5, with pH 10.0 being the optimal.

[0012] Another object of the present invention is to provide an enzymolysis-resistant whole-wheat bread, the raw material formula of which includes the above-mentioned bread digestibility improver, whole-wheat flour and gluten flour.

[0013] In some embodiments of the present invention, the formula of the enzymolysis-resistant whole wheat bread is 50-100 parts of whole wheat flour, 10-30 parts of gluten flour, 2-10 parts of bread digestibility improver, 1-3 parts of yeast, and 60-100 parts of distilled water.

[0014] In some embodiments of the present invention, the mass ratio of whole wheat flour, gluten flour, bread digestibility improver, and yeast is 72:21:9.5:1.5.

[0015] In some embodiments of the present invention, the method for preparing the enzymolysis-resistant whole-wheat bread comprises the following steps:

[0016] (5) Dough preparation: weigh the raw materials according to the recipe of enzyme-resistant whole wheat bread into a dough mixer, add appropriate amount of warm water and stir into a uniform dough, and let the dough ferment;

[0017] (6) Shaping: Divide the dough into small pieces, roll them into balls, remove gas and repair damaged tissues;

[0018] (7) Proofing: Place the kneaded dough into a proofing box and let it rise;

[0019] (8) Baking: Place the proofed dough on a baking tray and bake the bread.

[0020] Furthermore, in step (1), the mixing time in the dough mixer is 10-15 minutes, the dough is fermented at 30-35° C. for 30-45 minutes, and the proofing humidity is 70%-90%.

[0021] Furthermore, in step (3), the proofing temperature is set to 30-35° C., the proofing time is set to 70-90 min, and the proofing humidity is set to 70%-90%.

[0022] Furthermore, in step (4), the proofed dough is placed on a baking tray, baked at a temperature of 150-170° C. for 20-30 minutes, and finally cooled to room temperature to obtain enzymolysis-resistant whole wheat bread.

[0023] Beneficial effects of the present invention:

[0024] The bread digestibility improver of the present invention addresses the shortcomings of whole-wheat bread, such as a high glycemic index, poor baking quality, and poor palatability. Through the synergistic effects of gluten, β-glucan, and wheat flour, the present invention can improve the baking quality of whole-wheat bread, reduce the hardness and chewiness of whole-wheat bread, and increase the specific volume of whole-wheat bread. Simultaneously, it can reduce the content of rapidly digestible starch in whole-wheat bread and increase the content of slowly digestible starch and resistant starch, significantly reducing the GI value of whole-wheat bread, making it suitable for consumption by patients with hyperglycemia. This provides a new approach for preparing whole-wheat bread with high baking quality and a low glycemic index. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Effects of different digestibility improvers on the specific volume of whole wheat bread.

[0026] Figure 2 Effects of different digestibility improvers on the in vitro digestibility of whole wheat bread. DETAILED DESCRIPTION

[0027] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] Example 1

[0029] Preparation of digestibility improver: 7 parts of gluten were dissolved in sodium hydroxide solution at pH=10.0, and after the protein chains were fully unfolded, 2.5 parts of low molecular weight β-glucan (molecular weight 2×10 4 Da), stirred for 30 minutes to form a gluten / β-glucan complex through molecular self-assembly, and dried for 24 hours to form a bread digestibility improver. The bread sample with the digestibility improver added was used as the composite test group of Example 1.

[0030] The enzymolysis-resistant whole-wheat bread is prepared from the following components in parts by mass: 72 parts of whole-wheat flour, 21 parts of wheat flour, 9.5 parts of a digestibility improver, and 1.5 parts of yeast.

[0031] (1) Dough preparation: weigh the raw materials according to the recipe of enzyme-resistant whole wheat bread in a dough mixer, add 80 parts of distilled water and stir into a uniform dough, and ferment at a temperature of 30-35°C and a humidity of 70%-90% for 30-45 minutes;

[0032] (2) Shaping: Divide the dough into small pieces, roll them into balls, remove gas and repair damaged tissues;

[0033] (3) Proofing: Place the kneaded dough into a proofing box and let it rise;

[0034] (4) Baking: Place the proofed dough on a baking tray, bake at 150-170°C for 20-30 minutes, and finally cool to room temperature to obtain enzymatically resistant whole wheat bread.

[0035] Example 2

[0036] Medium molecular weight β-glucan (molecular weight 1×10 5 Da) as the modifier, that is, except for the molecular weight of the modifier, the rest are the same as in Example 1.

[0037] Example 3

[0038] High molecular weight β-glucan (molecular weight 3×10 5 Da) as the modifier, that is, except for the molecular weight of the modifier, the rest are the same as in Example 1.

[0039] Comparative Example 1

[0040] The only difference from Example 1 is that no whole wheat flour and bread digestibility improver are added, and the amount of whole wheat flour is adjusted accordingly; the rest is the same as Example 1.

[0041] Comparative Example 2

[0042] The only difference from Example 1 is that no bread digestibility improver is added and the amount of whole wheat flour is adjusted accordingly; the rest is the same as Example 1.

[0043] Comparative Example 3

[0044] The only difference from Example 1 is that only gluten is added without adding β-glucan, and the amount of whole wheat flour is adjusted accordingly; the rest is the same as Example 1.

[0045] Comparative Example 4

[0046] The only difference from Example 1 is that only β-glucan is added, gluten is not added, and the amount of whole wheat flour is adjusted accordingly; the rest is the same as Example 1.

[0047] Comparative Example 5

[0048] The only difference from Example 1 is that the improving agents gluten and β-glucan are not pre-self-assembled but directly physically mixed for use (7 parts gluten + 2.5 parts β-glucan). Other aspects are the same as Example 1.

[0049] In the above examples and comparative examples, whole wheat flour was purchased from Kunshan Yihai Kerry Food Industry Co., Ltd., yeast was purchased from Lesaffre Group of France, gluten powder was purchased from Dongguan Yihai Kerry Starch Co., Ltd., gluten protein was purchased from Xi'an Guohao Biotechnology Co., Ltd., and β-glucan was purchased from Shaanxi Zelang Biotechnology Co., Ltd.

[0050] Test 1: Determination of pore characteristics

[0051] The bread was sliced ​​with a slicer, and the middle section was selected for image scanning. Image J software was used to analyze the texture structure of the central region of the bread slice image and calculate the pore density, average pore size, and porosity.

[0052] Test 2: Determination of specific volume

[0053] Refer to GB / T 209812007 and use the millet substitution method to determine the volume of bread (mL). The formula for calculating the specific volume of bread is as follows: specific volume of bread (mL / g) = volume of bread (mL) / weight of bread (g)

[0054] Test 3: Determination of TPA characteristics

[0055] Take a whole wheat bread sample and cut the bread into slices with a thickness of about 2 cm using a bread slicer. Place the slices flat on the test table of the texture analyzer. The speed before the test is 3.00 mm / s, the test speed is 1.00 mm / s, and the speed after the test is 5.00 mm / s. The compression ratio is 40% and the interval time is 10 s.

[0056] Test Example 4: Determination of Glycemic Index by In Vitro Simulated Digestion

[0057] Transfer 0.6 g of freeze-dried bread sample (passed through a 100-mesh sieve) to a 50 ml centrifuge tube. Add 10 ml of pepsin solution to each tube, vortex mix, shake in a water bath, add 10 ml of sodium acetate buffer, vortex, and incubate at 37°C for 10 minutes. After incubation, terminate the reaction with anhydrous ethanol and add a mixed enzyme solution (saccharifying enzyme + pancreatic enzyme). Glucose equivalents were measured at 10, 20, 40, 60, 90, 120, 150, and 180 minutes. The starch hydrolysis rate of the sample during digestion was calculated based on the measured glucose equivalents.

[0058] Hydrolysis rate (%) = Gt × 0.9 / TS × 100%,

[0059] The hydrolysis area (HI) is the integral area of ​​the hydrolysis curve, and eGI is calculated according to the following equation:

[0060] eGI=8.198+0.862HI.

[0061] (1) The results of the effects of the digestibility improvers on the pore characteristics of whole wheat bread in the examples and comparative examples are shown in Table 1.

[0062] Table 1 Pore characteristics of whole wheat bread obtained in various examples and comparative examples

[0063]

[0064] As shown in Table 1, the addition of gluten can reduce the average pore area of ​​bread and increase porosity and pore density, indicating that the addition of gluten improves the pore characteristics of bread and makes the bread structure more delicate. However, as shown in Comparative Example 4, the addition of β-glucan increases the average pore area of ​​bread, reduces porosity, makes pore size uneven, and reduces pore density, which destroys the gluten protein network structure and causes deterioration of bread quality. Compared with the comparative example, the average pore area of ​​Examples 1, 2, 3 and Comparative Example 5 is reduced, and the porosity and pore density are increased. When gluten and β-glucan are added simultaneously, the presence of gluten can weaken the adverse effect of β-glucan on the pore distribution of bread. Moreover, due to the filling effect of gluten, the air cells in the bread are divided into more small air cells, thereby increasing the pore density of the bread and improving the quality of whole wheat bread. The improvement effect of gluten and β-glucan on the pores of whole wheat bread after pre-self-assembly is better than that without self-assembly.

[0065] (2) In addition, Figure 1 It can be seen that compared with the blank control group of Comparative Example 1, the bread improver can increase the specific volume of whole wheat bread. Examples 1, 2, and 3 increase the specific volume of whole wheat bread by 41.67%, 48.61%, and 39.35%, respectively. As the molecular weight of β-glucan increases, the specific volume of whole wheat bread shows a trend of first increasing and then decreasing, among which the improvement effect of Example 2 is the best. Moreover, compared with Comparative Examples 2, 3, 4, and 5, each Example greatly increases the specific volume of whole wheat bread. The improvement effect of the composite improver on the specific volume of whole wheat bread is better than that of the single improver. The improvement effect of the improver on the specific volume of whole wheat bread after pre-self-assembly is greater than that of the improver without self-assembly. Compared with Comparative Examples 2, 3, 4, and 5, the specific volume of Example 1 increases by 2.34%, 30.21%, 61.90%, and 16.79%. The addition of the gluten / β-glucan complex can strengthen the gluten network structure and promote a more complete and continuous development of the gluten network, thereby increasing the specific volume of whole wheat bread.

[0066] (3) The results of the effects of the digestibility improvers on the texture properties of whole wheat bread in the examples and comparative examples are shown in Table 2.

[0067] Table 2 Texture characteristics of whole wheat bread obtained in each embodiment and comparative example

[0068]

[0069] As shown in Table 2, compared with the blank control group of Comparative Example 1, the hardness of the whole wheat bread of Examples 1, 2, and 3 decreased by 51.5%, 55.6%, and 42.4%, respectively, and the chewiness decreased by 47.42%, 50.98%, and 37.41%. As the molecular weight of β-glucan increases, the hardness and chewiness of whole wheat bread show a trend of first decreasing and then increasing. Among them, Example 2 has lower hardness and chewiness, making the bread texture soft and of good quality. Compared with Comparative Example 5, the pre-self-assembled gluten / β-glucan improver reduces the hardness and chewiness of whole wheat bread to an appropriate range, and the taste is better. The addition of bread improvers can significantly reduce the hardness and chewiness of whole wheat bread, which may be because the gluten / β-glucan complex can increase the water absorption of the dough, and the gluten / β-glucan complex can compete with the starch in the dough for water, which limits the leaching of amylose in the flour and reduces the hardness of the bread.

[0070] (4) The results of the effects of the digestibility improvers on the in vitro starch digestibility of whole wheat bread in various examples and comparative examples are shown in Tables 3 and Figure 2 shown.

[0071] Table 3 In vitro starch digestibility results of whole wheat bread obtained from each embodiment and comparative example

[0072]

[0073]

[0074] From Table 3 and Figure 2 It can be seen that the addition of gluten / β-glucan composite modifier can reduce the content of rapidly digestible starch (RDS) and slowly digestible starch (SDS), increase the content of resistant starch (RS), and reduce the eGI value in whole wheat bread. Compared with Comparative Example 1, Examples 1, 2, and 3 reduced the eGI value of whole wheat bread by 11.9%, 7.6%, and 7.9%, respectively, among which low molecular weight β-glucan had the best effect in reducing the eGI value. Compared with Comparative Examples 2, 3, and 4, the effect of the composite modifier on increasing the RS of whole wheat bread and reducing the eGI value is better than the addition of a single modifier. Compared with Comparative Example 5, it can be seen that the gluten / β-glucan modifier that has been pre-self-assembled has a better inhibitory effect on the digestion of starch in whole wheat bread than that without self-assembly. The main reason for the inhibition of starch digestion in whole-wheat bread may be that the gluten / β-glucan complex can assist the formation and development of the gluten network, enhance the wrapping of gluten protein around starch, and strengthen the gluten network structure, thereby forming a more solid and stable physical embedding around starch and inhibiting starch gelatinization.

[0075] This demonstrates that the compound improver has an excellent effect on whole-wheat bread, significantly increasing its specific volume while also reducing its hardness and chewiness, resulting in a bread product with a better taste. Furthermore, in an in vitro simulated digestion test, the compound improver significantly reduced the content of rapidly digestible and slowly digestible starches, increased the content of resistant starch, and significantly lowered the eGI value of whole-wheat bread.

[0076] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for preparing a bread digestibility improver, characterized in that: The following steps are involved: Gluten is dispersed under alkaline conditions to fully unfold the protein chains, and then β-glucan is added to form a gluten / β-glucan complex through molecular self-assembly to form a bread digestibility improver.

2. The method according to claim 1, characterized in that The gluten is one or more of highland barley, wheat, and oats; the β-glucan is one or more of highland barley β-glucan, oat β-glucan, and yeast β-glucan.

3. The method according to claim 1, wherein The β-glucan is one or more of high, medium and low molecular weight; wherein low molecular weight refers to 1×10 4 -8×10 4 Da, medium molecular weight refers to 1×10 5 -2×10 5 Da, high molecular weight refers to 3×10 5 -5×10 5 Da.

4. The method according to claim 1, wherein The weight ratio of gluten to β-glucan is 7:2.

5.

5. The method according to claim 1, wherein The pH range in which the gluten molecular chains open is 9.0-10.

5.

6. The bread digestibility improver prepared by the method according to any one of claims 1 to 5.

7. An enzymolysis-resistant whole wheat bread, characterized in that: The formula comprises the following raw materials: the bread digestibility improver according to claim 6, whole wheat flour and gluten.

8. The enzymolysis-resistant whole-wheat bread according to claim 7, characterized in that The formula of the enzymolysis-resistant whole-wheat bread is 50-100 parts of whole-wheat flour, 10-30 parts of gluten, 2-10 parts of bread digestibility improver, 1-3 parts of yeast and 60-100 parts of distilled water.

9. The enzymolysis-resistant whole wheat bread according to claim 8, characterized in that The preparation method of the enzymolysis-resistant whole-wheat bread comprises the following steps: (1) Dough preparation: weigh the raw materials according to the recipe of enzyme-resistant whole wheat bread into a dough mixer, add appropriate amount of warm water and stir into a uniform dough, and then ferment the dough; (2) Shaping: Divide the dough into small pieces, roll them into balls, remove gas and repair damaged tissues; (3) Proofing: Place the kneaded dough into a proofing box to let it rise; (4) Baking: Place the proofed dough on a baking tray and bake the bread.

10. The enzymolysis-resistant whole-wheat bread according to claim 9, characterized in that In step (1), the mixing time in the dough mixer is 10-15 minutes, the dough is fermented at 30-35° C. for 30-45 minutes, and the fermentation humidity is 70%-90%; in step (3), the proofing temperature is 30-35° C., the proofing time is 70-90 minutes, and the proofing humidity is 70%-90%; in step (4), the proofed dough is placed on a baking tray, baked at a temperature of 150-170° C. for 20-30 minutes, and finally cooled to room temperature to obtain enzymolysis-resistant whole wheat bread.

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