High-quality highland barley bread with low glycemic index and preparation method and application thereof

Abstract

The invention discloses high-quality highland barley bread with a low glycemic index as well as a preparation method and application of the high-quality highland barley bread. The invention provides highland barley composite flour. The highland barley composite flour comprises black highland barley flour, vital gluten, wheat flour and rye flour. The invention also provides highland barley bread which is prepared by taking the highland barley composite powder as a main raw material and utilizing an enzyme preparation and an intermediate fermentation process. The addition amount of the black highland barley powder in the highland barley composite powder reaches 60%, postprandial blood sugar can be effectively controlled, the glycemic index is 49.7, the specific volume is 4.03 mL / g, and the hardness is 605 g. Experiments prove that the low-GI bread can reduce the fasting blood glucose by 46.3% and the serum insulin by 33.0%, and is beneficial to maintaining the blood glucose level. The highland barley bread provided by the invention is helpful for expanding the consumption market of bread, and meets the requirements of people on diversified food consumption and nutrition and health.

Description

Technical Field

[0001] This invention belongs to the field of food processing technology, specifically relating to a high-quality barley bread with a low glycemic index, its preparation method, and its application. Background Technology

[0002] The glycemic index (GI) is a physiological indicator that assesses the intensity of postprandial blood glucose fluctuations caused by food, reflecting the characteristics of the body's metabolic response after food intake. Currently, low-GI breads face challenges such as the difficulty in achieving both high GI value and good taste, and the high cost of functional ingredients. Therefore, developing high-quality low-GI bread is of great significance for industry development and meeting people's health needs.

[0003] In recent years, the reduction of glycemic index (eGI) and functional evaluation of bread have become emerging research hotspots. The main methods for reducing eGI include ingredient substitution, formulation design, and the addition of functional components. For example, after replacing wheat flour in a bread formulation with chickpea flour, red chicory flour, and three types of resistant starch, the estimated glycemic index (eGI) of the new formulation dropped to below 55, but the bread volume was only 2.58 mL / g and the hardness significantly increased (Pasqualoni et al., Foods, 2024, 13:2488). Liu Danting et al. replaced 45% of the wheat flour with oat flour and soy flour to obtain a soy-oat bread with an eGI of 42.1 (Liu Danting et al., Light Industry Science and Technology, 2025, 41:15-21). Li Lingling et al. improved the sensory quality of potato bread by optimizing the ratio of main ingredients and sweeteners and using a sponge fermentation process, achieving an eGI of 49.3 in in vitro simulated digestion (Li Lingling et al., Agricultural Product Processing, 2025, 8:58-61). Shi Yonglei et al. reduced the eGI of bread from 81.8 to 52.1 by using low-dose 60Co-γ ray irradiation of wheat flour combined with active substances in tea (Chinese Patent No.: ZL202310298828.9). Microbial segmented fermentation can prepare low-GI sourdough bread with a shelf life of up to 21 days (Chinese Patent No.: ZL202510483906.1). All of these efforts focus on improving bread formulations and processes to achieve a low-GI result, but high-quality results have not yet been achieved. Furthermore, the GI values ​​lack support from postprandial blood glucose concentration data and there are issues with the complexity and high cost of raw materials.

[0004] highland barley ( Hordeum vulgare var. coelesteBarley (Linnaeus) is a cereal crop belonging to the genus *Hordeum* of the Poaceae family. Based on color, it can be classified into white barley, black barley, and variegated barley, among others. Proanthocyanidins B1 and p-coumaric acid derived from barley grains have the effect of regulating glucose absorption and improving glycogen synthesis, and can synergistically regulate glucose metabolism through the IRS-1 / PI3K / Akt pathway (Liue et al, *Molecular Nutrition and Food Research*, 2021, 65:2100454).

[0005] However, whole-grain bread made primarily from barley has a low gluten protein content, making it difficult to form a gluten network structure. This results in poor dough extensibility and plasticity, making the bread prone to collapsing. Therefore, when making bread with high barley content, it is necessary to add extra gluten powder to aid dough shaping. The formation of the gluten network structure depends on the water absorption, swelling, and cross-linking polymerization of proteins. Adding gluten powder increases the amount of water needed during bread making. The water content for wheat bread is typically 55% to 65%, while for bread with high barley content, the water content needs to be increased to over 70%. Excessive water content causes the dough to break or stick together easily, resulting in uneven internal structure, slow fermentation, and increased moisture content, which promotes mold growth and affects the bread's shelf life.

[0006] The aforementioned issues limit the application of highland barley flour in bread, with commercially available bread products generally containing less than 30% highland barley flour. Single-factor experiments by Zhang Shuo et al. showed that adding 0.1% β-glucanase resulted in better specific volume, elasticity, and porosity of highland barley bread, and increased the volatile flavor compounds of esters and alcohols in the bread crumb (Zhang Shuo et al., Food Industry Technology, 2023, 44:11-19). Zhang Haiyue et al. used highland barley compound flour, wheat flour, compound prebiotic powder, and gluten as the main ingredients to produce a low-GI highland barley bread; however, the amount of highland barley flour added in this bread formula was less than 25%, and the product had a relatively high hardness, affecting palatability (Chinese Patent No.: ZL202411715608.2).

[0007] In summary, existing low-GI breads made primarily from barley suffer from problems such as high production difficulty, poor sensory quality, high raw material costs, and limited efficacy. Therefore, this invention is proposed. Summary of the Invention

[0008] The purpose of this invention is to provide a low-GI, high-quality barley bread with a GI value as low as 49.7, which falls into the category of low-GI foods. This bread also has the advantages of simple production process, good sensory characteristics, low raw material cost, and significant efficacy.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] In a first aspect, the present invention provides a highland barley compound powder, comprising the following components: 100 parts by weight of black highland barley powder, 25-35 parts by weight of wheat gluten, and 25-35 parts by weight of wheat flour and rye flour. The mass ratio of wheat flour to rye flour is 1:(1-3).

[0011] Preferably, the mass ratio of wheat flour to rye flour is 1:1.

[0012] Secondly, the present invention provides a barley bread made from the following raw materials: 100 parts by weight of the aforementioned barley compound powder and 0.1-0.3 parts by weight of enzyme preparation.

[0013] The enzyme preparation is composed of maltose amylase, lipase and β-glucanase in a mass ratio of (60-65):1:(1200-1300).

[0014] The ingredients also include: 45-70 parts by weight of water, 10-20 parts by weight of whole egg liquid, 6-12 parts by weight of butter, 1-2 parts by weight of yeast, 0.5-1 part by weight of salt, 1-2 parts by weight of sugar, and 4-16 parts by weight of sugar alcohol.

[0015] Thirdly, the present invention provides a method for preparing the barley bread, comprising the following steps: S1. Prepare the starter dough and let it ferment; S2. Add the fermented starter dough to the main dough mix to make the main dough; S3. Let the main dough rest and relax, divide and shape it, let it rise, and then bake it to get barley bread.

[0016] In step S1, the starter dough includes the following ingredients: black barley flour, wheat flour, yeast, maltose amylase, and β-glucanase; The mass ratio of black highland barley flour to wheat flour is (4-8):1; The mass ratio of yeast to wheat flour is (0.07-0.09):1; Based on the sum of the masses of black barley flour and wheat flour, the amount of maltose amylase added is 140-160 mg / kg; the amount of β-glucanase added is 2900-3100 mg / kg. The fermentation conditions are: fermentation for 20-40 minutes at a relative humidity of 80% and a temperature of 30℃.

[0017] In step S2, the raw materials of the main dough mixing powder include: black barley flour, wheat gluten, wheat flour, rye flour, yeast, maltose amylase, β-glucanase, and lipase. The mass ratio of black barley flour, gluten flour, wheat flour and rye flour is (4-8):(3-5):1:(1-3). Based on the sum of the masses of black barley flour, wheat gluten, wheat flour, and rye flour, the amount of maltose amylase added is 100-120 mg / kg, the amount of β-glucanase added is 2100-2300 mg / kg, and the amount of lipase added is 2-4 mg / kg. In step S3, the conditions for proofing are: proofing for 90-120 minutes at a relative humidity of 80% and a temperature of 38°C. The baking conditions are: top heat temperature 170-190℃, bottom heat temperature 190-210℃, and baking time 20-30 minutes.

[0018] Fourthly, the present invention provides a dietary product that helps with blood sugar management, the raw material of which includes the aforementioned highland barley compound powder.

[0019] The blood glucose management includes one of the following: weight loss, lowering fasting blood glucose, lowering serum insulin, lowering cholesterol, improving oral glucose tolerance, and improving insulin sensitivity.

[0020] Compared with the prior art, the beneficial effects achieved by the present invention are: (1) The barley bread provided by this invention contains 60% black barley flour, which can effectively control postprandial blood glucose. The glycemic index is 49.7 (belonging to the category of low GI foods), the volumetric weight is 4.03 mL / g, and the hardness is 605 g. It has the function of low postprandial blood glucose response and maintaining postprandial blood glucose dynamic balance. It also has a good flavor and can enrich the staple food choices of diabetic people. Among them, the proportion of barley flour in the bread raw material compound powder exceeds 60%, which can effectively reduce the starch intake in daily diet and is rich in dietary fiber. Dietary fiber can slow down the absorption of glucose in the intestine and has the effect of maintaining blood glucose homeostasis.

[0021] (2) This invention improves the specific volume, hardness, and chewiness of barley bread by optimizing the bread formula and using a sponge fermentation process, in conjunction with β-glucanase, maltose amylase, and lipase. During dough fermentation, the synergistic effect of β-glucanase and maltose amylase degrades large carbohydrate molecules into smaller fragments, enhances the cross-linking between proteins, makes the gluten network structure denser, gives low-GI bread higher softness and resilience, improves the sensory quality of bread, increases specific volume by 97.4%, reduces hardness by 83.7%, and reduces chewiness by 80.2%.

[0022] (3) The raw material cost of the barley bread provided by the present invention is low and suitable for industrial production; at the same time, it also promotes the industrial application of barley. Attached Figure Description

[0023] Figure 1 This is a comparison chart of the appearance of the bread in Test Example 3.

[0024] Figure 2 This is a curve showing the change in blood glucose concentration after a meal in the human body.

[0025] Figure 3 Effects of low-GI bread on glucose tolerance and insulin sensitivity in diabetic mice; A: OGTT results, B: ITT results.

[0026] Figure 4 The effect of low-GI bread on liver and epididymal fat weight in diabetic mice. Detailed Implementation

[0027] The present invention will be further described below with reference to specific embodiments, but the present invention is not limited to the following embodiments.

[0028] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0029] Unless otherwise specified, all reagents, materials, instruments, etc. used in the following examples are commercially available.

[0030] In the quantitative experiments in the following examples, at least three replicate experiments were set up, and the average value of the results was taken.

[0031] Materials used in the embodiments of this invention: Black highland barley flour: Commercially available from Qinghai Xindingxiang Grain and Oil Co., Ltd. The black highland barley flour contains 62.3% carbohydrates, 10.8% protein, 1.9% fat, and 5.8% β-glucan.

[0032] Rye flour: Commercially available from Xinxiang Xinliang Grain and Oil Processing Co., Ltd. The rye flour contains 58.2% carbohydrates, 12.8% protein, 2.3% fat, and 12.2% dietary fiber.

[0033] High-gluten wheat flour: Commercially available from Xinxiang Xinliang Grain and Oil Processing Co., Ltd. The wheat flour contains 71.5% carbohydrates, 12.7% protein, and 1.3% fat.

[0034] Gluten powder: Commercially available from Henan Gaobao Industrial Co., Ltd. Gluten powder contains 15.9% carbohydrates, 75.0% protein, and 2.0% fat.

[0035] β-glucanase (BGS type): purchased from Ningxia Xiasheng Industrial Group Co., Ltd., with a specific enzyme activity of 140,000 U / g.

[0036] Maltose amylase: purchased from Novozymes (China) Biotechnology Co., Ltd., model Novamyl 3D BG, 10000 MANU / g.

[0037] Lipase: Purchased from Shandong Longket Enzyme Preparation Co., Ltd., with a specific enzyme activity of 100,000 U / g.

[0038] Yeast powder: High-sugar tolerant, high-activity dry yeast, purchased from Hubei Angel Yeast Co., Ltd., with 30 billion live bacteria / g.

[0039] Sensory evaluation of low-GI bread follows the standard GB / T 20981-2021 "General Rules for Bread Quality". Specifically, the sample is placed in a clean, dry white porcelain dish and observed for shape and color under natural light; it is cut open using the quartering method to observe the cross-sectional structure and impurities; and the taste and texture are evaluated. The total score is 100 points, with 30 points for structure, 20 points for texture, 20 points for aroma, 20 points for color, and 10 points for shape.

[0040] Example 1 This embodiment provides a highland barley compound powder, which is composed of the following components: 300 g of black highland barley powder, 100 g of wheat gluten, 50 g of wheat flour, and 50 g of rye flour.

[0041] Example 2 This embodiment provides a highland barley compound powder, which is composed of the following components: 300 g of black highland barley powder, 100 g of gluten powder, 25 g of wheat flour, and 75 g of rye flour.

[0042] Example 3 This embodiment provides a barley bread, the preparation steps of which are as follows: (1) Weigh 500 g of the highland barley compound powder, 5.5 g of sugar, 4.5 g of salt and 5.5 g of yeast obtained in Example 1 and make them into mixed powder; (2) Add 285 g of water and 55 g of whole egg liquid to the mixed powder, mix at low speed for 3 min, then mix at high speed for 3 min until the dough is basically formed, add 32.5 g of butter and beat to form a dough; (3) Let stand and relax for 20 minutes; (4) Divide the dough into 150 g portions, shape and plate them; (5) After being placed in the pan, the dough was proofed for 60 min at a relative humidity of 80% and a temperature of 38℃. (6) Bake and cool to room temperature to obtain the low-GI bread product. The baking temperature is 180°C for the top heat and 200°C for the bottom heat, and the baking time is 25 min.

[0043] Example 4 The difference from Example 3 is that the barley compound powder is the barley compound powder obtained in Example 2.

[0044] Comparative Example 1 The difference from Example 1 is that the 100g of wheat flour does not contain rye flour.

[0045] Comparative Example 2 The difference from Example 1 is that 75g of wheat flour and 25g of rye flour are used.

[0046] Comparative Example 3 The difference from Example 3 is that the barley compound powder is the same as that obtained in Comparative Example 1.

[0047] Comparative Example 4 The difference from Example 3 is that the barley composite powder is the same as that obtained in Comparative Example 2.

[0048] Test Example 1: The effect of rye flour addition in low-GI bread The quality of the barley bread obtained in Examples 3 and 4, and Comparative Examples 3 and 4 was tested, and the results are as follows.

[0049] Table 1. Effect of wheat flour to rye flour ratio on bread quality

[0050] As shown in the table above, with the increase of rye flour addition, the bread volume shrinks and the bread texture becomes denser. This may be due to insufficient gluten, resulting in a harder dough that cannot form a tight gluten network structure, which is not conducive to the bread's expansion during baking. When the ratio of wheat flour to rye flour is 50:50, the bread volume does not shrink significantly, and the appropriate addition of rye flour can effectively control the absorption and metabolism of sugar, making it more suitable for people with high blood sugar. Therefore, a 50:50 ratio of wheat flour to rye flour is preferred for making bread.

[0051] Test Example 2: Enzyme Preparations Improve the Quality of Low-GI Bread This test example prepares a low-GI bread. The preparation steps are as follows: (1) Weigh 500 g of the highland barley compound powder prepared in Example 1, 5.5 g of sugar, 4.5 g of salt, and 5.5 g of yeast; add 0-125 mg / kg maltose amylase (0, 50, 75, 100, 125 mg / kg), 0-6 mg / kg lipase (0, 1, 2, 4, 6 mg / kg), or 0-3000 mg / kg β-glucanase (0, 1500, 2000, 2500, 3000 mg / kg) respectively, and stir into a mixed powder; (2) Add 285 g of water and 55 g of whole egg liquid to the mixed powder, mix at low speed for 3 min, then mix at high speed for 3 min, add 32.5 g of butter and beat to form a dough; (3) Let stand and relax for 20 minutes; (4) Divide the dough into 150 g portions, shape and plate them; (5) The dough after being placed in the pan should be proofed for 60 min at a relative humidity of 80% and a temperature of 38℃; (6) Baking and cooling at room temperature, wherein the upper heat temperature is 180℃, the lower heat temperature is 200℃, and the baking time is 25min.

[0052] The effects of a single enzyme preparation on bread quality are shown in Table 2.

[0053] Table 2. Effects of a single enzyme preparation on bread quality.

[0054] Table 2 shows that maltose amylase, lipase, and β-glucanase all improved the specific volume and texture of bread, with β-glucanase showing the best effect. Higher hardness indicates that the bread is less prone to deformation and has a firmer texture. Compared to the untreated group, the bread with added maltose amylase, lipase, and β-glucanase showed the largest reductions in hardness of 25.0%, 24.7%, and 57.3%, respectively. Chewability is one of the important indicators of bread quality, determining its texture and eating experience. The chewiness of bread with added maltose amylase or β-glucanase was significantly lower than that of untreated bread, with maximum reductions of 24.3% and 52.1%, respectively. Regarding specific volume, elasticity, and resilience, all three enzyme preparations improved the textural properties of the bread compared to the untreated bread.

[0055] Example 5 The difference from Example 3 is that in step (1), maltose amylase, lipase and β-glucanase are added by weight of barley compound powder, and the amounts added are 125 mg / kg, 2 mg / kg and 2500 mg / kg respectively.

[0056] Comparative Example 5 The difference from Example 3 is that, based on the weight of the highland barley compound powder, maltose amylase, lipase and β-glucanase were added, with the addition amounts being 75 mg / kg, 2 mg / kg and 1500 mg / kg respectively.

[0057] Comparative Example 6 The difference from Example 3 is that, based on the weight of the highland barley compound powder, maltose amylase, lipase and β-glucanase were added, with the addition amounts being 75 mg / kg, 4 mg / kg and 2000 mg / kg respectively.

[0058] Comparative Example 7 The difference from Example 3 is that, based on the weight of the highland barley compound powder, maltose amylase, lipase and β-glucanase were added, with the addition amounts being 75 mg / kg, 6 mg / kg and 2500 mg / kg respectively.

[0059] Comparative Example 8 The difference from Example 3 is that, based on the weight of the highland barley compound powder, maltose amylase, lipase and β-glucanase were added, with the addition amounts being 100 mg / kg, 6 mg / kg and 1500 mg / kg respectively.

[0060] Comparative Example 9 The difference from Example 3 is that, based on the weight of the highland barley compound powder, maltose amylase, lipase and β-glucanase were added, with the addition amounts being 100 mg / kg, 2 mg / kg and 2000 mg / kg respectively.

[0061] Comparative Example 10 The difference from Example 3 is that, based on the weight of the highland barley compound powder, maltose amylase, lipase and β-glucanase were added, with the addition amounts being 100 mg / kg, 4 mg / kg and 2500 mg / kg respectively.

[0062] Comparative Example 11 The difference from Example 3 is that, based on the weight of the highland barley compound powder, maltose amylase, lipase and β-glucanase were added, with the addition amounts being 125 mg / kg, 4 mg / kg and 1500 mg / kg respectively.

[0063] Comparative Example 12 The difference from Example 3 is that, based on the weight of the highland barley compound powder, maltose amylase, lipase and β-glucanase were added, with the addition amounts being 125 mg / kg, 6 mg / kg and 2000 mg / kg respectively.

[0064] The effects of compound enzyme preparations on bread quality are shown in Table 3.

[0065] Table 3. Effects of compound enzyme preparations on bread quality

[0066] Note: Wheat bread was used as a positive control to demonstrate the technical effects of the compound enzyme preparation described in this invention in increasing the specific volume of low-GI bread, reducing hardness, and improving texture.

[0067] Table 3 shows that the compound enzyme preparation has significant advantages compared to Test Example 2, which used a single enzyme preparation. The maltose amylase in the compound enzyme preparation can delay starch retrogradation, the lipase can enhance the elasticity and toughness of the dough, and the β-glucanase can enhance gluten strength. Furthermore, it can be seen that breads with the combined addition levels of maltose amylase, lipase, and β-glucanase of 125 mg / kg, 2 mg / kg, and 2500 mg / kg are closest to the control wheat bread in terms of specific volume, hardness, and resilience. Therefore, the combined addition levels of maltose amylase, lipase, and β-glucanase of 125 mg / kg, 2 mg / kg, and 2500 mg / kg are preferred for improving bread quality.

[0068] Example 6 This embodiment provides a low-GI barley bread, the preparation steps of which are as follows: (1) Weigh 175 g of starter dough compound powder (the ratio of black barley flour to wheat flour is 150:25) and 2 g of yeast; add 150 mg / kg of maltose amylase and 3000 mg / kg of β-glucanase based on the weight of the starter dough compound powder, and stir to form starter dough mixture powder; (2) Add 125 g of water to the starter dough mixture, mix at low speed for 3 min, and then mix at high speed for 3 min to obtain the starter dough; (3) The starter dough was fermented for 30 min at a relative humidity of 80% and a temperature of 30℃; (4) Weigh 325 g of main dough compound powder (the ratio of black barley flour, wheat gluten, wheat flour and rye flour is 150:100:25:50), 5.5 g of sugar, 4.5 g of salt, 20 g of erythritol, 20 g of sorbitol and 3.5 g of yeast; add 110 mg / kg of maltose amylase, 3.1 mg / kg of lipase and 2200 mg / kg of β-glucanase based on the weight of the main dough compound powder to make the main dough mixed powder; (5) Add the starter dough to the main dough mix, then add 160 g of water and 55 g of whole egg liquid, mix at low speed for 3 minutes, then mix at high speed for 3 minutes until the dough is basically formed, add 50 g of butter and beat to form a dough. (6) Let it stand and relax for 20 minutes; (7) Divide the dough into 150g portions, shape and plate them; (8) The dough after being placed in the pan should be proofed for 60 min at a relative humidity of 80% and a temperature of 38℃; (9) Bake and cool to room temperature to obtain the low-GI bread product. The baking temperature is 180°C for the upper heat and 200°C for the lower heat, and the baking time is 25 min.

[0069] Comparative Example 13 The difference from Example 3 is that high-gluten wheat flour is used instead of highland barley compound flour, the amount of sugar added is 40 g, and no whole egg liquid is added.

[0070] Test Example 3: The Effect of Low-GI Bread Fermentation Methods The preparation of low-GI bread using the sponge fermentation method is as described in Example 6 above.

[0071] The method for making low-GI bread by direct fermentation is as described in Example 5.

[0072] The method for making wheat bread is as described in Comparative Example 13.

[0073] The relevant experimental results are shown in Figure 1 Tables 4 and 5.

[0074] Table 4. Effects of fermentation method on bread texture properties

[0075] Note: Wheat bread was used as a positive control to demonstrate the technical effects of the sponge fermentation method described in this invention in improving the specific volume of low-GI bread, reducing hardness, and improving texture.

[0076] like Figure 1 As shown, the low-GI bread prepared by the sponge fermentation method has significantly better specific volume and texture than the low-GI bread prepared by direct fermentation. Specifically, it has uniform and fine internal pores, uniform crust color, and intact overall shape.

[0077] As shown in Table 4, the hardness and chewiness of low-GI bread fermented using the sponge method were reduced by 12.4% and 11.5% respectively compared to direct fermentation. This is because the sponge method can increase the water absorption of the dough, improve the mixing stability and fermentation stability of the dough, and thus improve the texture of the bread.

[0078] Table 5. Effects of fermentation method on the sensory quality of bread

[0079] Note: Wheat bread was used as a positive control to demonstrate the technical effectiveness of the sponge fermentation method described in this invention in improving the sensory quality of low-GI bread.

[0080] As shown in Table 5, the low-GI bread produced by the sponge fermentation method has sensory qualities such as shape, flavor, and texture that are closer to the control wheat bread, and has a higher overall sensory evaluation score. Therefore, the sponge fermentation method is preferred to improve bread quality.

[0081] Example 7 The difference from Example 6 is that the proofing time is 90 minutes.

[0082] Example 8 The difference from Example 6 is that the proofing time is 120 minutes.

[0083] Test Example 4: The Effect of Proofing Time on Low-GI Bread Dough The experimental results are shown in Tables 6 and 7.

[0084] Table 6. Effect of proofing time on bread textural properties

[0085] As shown in Table 6, compared to bread with a proofing time of 60 min, the specific volume of the bread reached 4.03 mL / g with a proofing time of 90 min. This is because sufficient proofing time allows the gluten protein network structure of the dough to stretch, resulting in good gas retention and sufficient yeast gas production, which is beneficial for the rapid expansion of the bread volume in the early stage of baking. When the bread proofing time was 120 min, the specific volume of the bread decreased slightly, possibly because excessive yeast gas production damaged the gluten network structure, causing the bread to collapse slightly. In terms of texture, the low-GI bread with a proofing time of 90 min showed the best performance in terms of hardness, elasticity, chewiness, and resilience.

[0086] Table 7. Effects of proofing time on the sensory quality of bread

[0087] As shown in Table 7, the low-GI bread with a proofing time of 90 minutes had the highest total sensory evaluation score. Sufficient fermentation optimized the bread's texture, making it soft, elastic, and forming uniform pores and a clear pattern. Therefore, a proofing time of 90 minutes is preferred for producing low-GI bread products.

[0088] Test Example 5: Determination of the GI value of low-GI bread The bread making method adopts the method of Example 7.

[0089] The study included 12 healthy volunteers, comprising 6 women and 6 men, aged 18-60 years, with a BMI of 18.5-24.0 kg / m². 2The participants had regular eating habits, no family history of metabolic diseases or chronic illnesses, and no recent gastrointestinal digestive diseases or medication use. For 12 hours prior to the experiment, participants fasted and abstained from water. During the first week, participants consumed 20.0 g of anhydrous glucose (20.0 g of available carbohydrates); during the second week, they consumed 75.0 g of low-GI bread (20.0 g of available carbohydrates) at the same time. Postprandial blood glucose concentrations were measured at 15, 30, 45, 60, 90, and 120 minutes after the start of the meal. During the experiment, participants fasted and abstained from water, but engaged in light physical activity. A postprandial blood glucose concentration curve was plotted with time on the x-axis and the change in blood glucose concentration on the y-axis.

[0090] from Figure 2 It can be seen that the postprandial blood glucose fluctuation of low-GI bread is significantly smaller than that of glucose, specifically manifested in a slow rise and slow fall in blood glucose, resulting in a relatively stable postprandial blood glucose trend. Within 120 minutes, the blood glucose response curve for glucose consumption rises in the first 30 minutes and then steadily declines to a stable fasting blood glucose level; the blood glucose response curve for low-GI bread rises gently in the first 30 minutes and then declines, with overall fluctuations significantly more stable than glucose, and a smaller impact on blood glucose. The GI value of the bread is 49.7.

[0091] Test Example 6: Evaluation of the blood sugar management function of low-GI bread The methods for making wheat bread and low-GI bread were the same as those for Comparative Example 13 and Example 7, respectively.

[0092] Four-week-old male C57BL6 / J mice were selected. The temperature was maintained at 25±5℃, the humidity at 50±10%, and the lighting was kept in a 12-hour light-dark cycle (8:00-20:00 for daytime). After one week of acclimatization, six mice were randomly selected as the normal control group and fed a low-fat control diet with 10% fat energy (3.8 kcal / g). The remaining mice were fed a high-fat diet with 60% fat energy (5.2 kcal / g).

[0093] The experiment lasted 13 weeks. After 5 weeks of high-fat diet feeding, mice were intraperitoneally injected with streptozotocin (0.03 g / kg) for 3 consecutive days, 24 hours apart. The control group was injected with an equal volume of 0.1 mol / L citrate buffer (pH = 4.4). Two weeks after the injection, fasting blood glucose levels were measured by tail vein sampling. A blood glucose level higher than 11.1 mmol / L was considered a successful model of type 2 diabetes. The diabetic mice were randomly divided into 5 groups of 6 mice each: model group, metformin group (0.2 g / kg), wheat bread group (1 g / kg), low-GI bread low-dose group (1 g / kg), and low-GI bread high-dose group (2 g / kg). The control and model groups were administered physiological saline by gavage for 6 consecutive weeks. Body weight was measured weekly during the gavage period, and fasting blood glucose was measured every two weeks. In week 13, oral glucose tolerance test (OGTT) and insulin tolerance test (ITT) were performed. At the end of the experiment, mice were fasted for 12 hours. After blood collection by enucleation, they were euthanized by cervical dislocation. The liver and epididymal adipose tissue were quickly dissected and weighed. Blood was centrifuged to determine the levels of glucose (GLU), insulin (INS), total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C).

[0094] A high-fat diet easily disrupts metabolism and leads to weight gain. As shown in Table 8, compared with the normal group, the body weight of mice in the 6-week model group increased by 46.0%; while the high-dose low-GI bread group and the positive control metformin group significantly inhibited the increase in body weight, reducing it by 10.7% and 10.9% respectively compared with the model group. Repeated low-dose injections of streptozotocin partially damage the pancreatic β-cell function of mice, and combined with a high-calorie diet, ultimately lead to hyperglycemia. As shown in Table 9, compared with the normal group, the fasting blood glucose of the 6-week model group increased by 229.5%; the fasting blood glucose of mice given low-GI bread by gavage decreased by up to 46.3%, and metformin also significantly reduced fasting blood glucose in mice. OGTT is one of the most direct ways to assess the body's glucose metabolism capacity and reflects the severity of diabetes. Compared with the normal group, the area under the OGTT curve of mice in all other groups was significantly increased, indicating that the type 2 diabetes mouse model was successfully established. Among them, the high-dose low-GI bread group and the metformin group both showed efficacy in improving impaired glucose tolerance in mice, as evidenced by a 16.5% and 28.6% reduction in the area under the OGTT curve compared to the model group, respectively. Figure 3(A). ITT was used to assess insulin sensitivity in diabetic individuals and determine the hypoglycemic effect of the samples. In normal mice, blood glucose concentration decreased to 50.1% of that at 0 min after insulin injection at 30 min. Compared with the model group, blood glucose concentrations at all time points were lower in the low-GI bread low-dose group, the low-GI bread high-dose group, and the metformin group, with significant decreases in the area under the curve of 20.5%, 38.6%, and 31.4%, respectively, indicating that low-GI bread intervention improved insulin sensitivity in mice. Figure 3 (B)

[0095] Table 8. Effects of low-GI bread on body weight in diabetic mice.

[0096] Table 9. Effects of low-GI bread on fasting blood glucose in diabetic mice.

[0097] Liver quality and epididymal fat quality provide direct pathological evidence of metabolic abnormalities in diabetic mice.

[0098] Depend on Figure 4 It was found that the liver weight and epididymal fat weight in both the low-GI bread low-dose and high-dose groups were significantly lower than those in the model group, and these two indicators showed significant improvement compared to the wheat bread group. Serum biochemical analysis can monitor the dynamic balance of glucose and lipid metabolism in real time, and diabetic patients exhibit characteristic disorders of multiple indicators, such as elevated blood glucose and abnormal blood lipid profiles.

[0099] Table 10 Effects of low-GI bread on serum biochemical parameters in diabetic mice

[0100] As shown in Table 10, the serum GLU and INS levels in the model group were higher than those in the normal group, indicating that diabetes leads to abnormal blood glucose homeostasis. The serum GLU and INS levels in both the low-GI bread and high-dose groups were lower than those in the model group and the wheat bread group, with the high-dose group showing the most significant effect, exhibiting a 37.6% reduction in GLU levels compared to the model group. Regarding blood lipids, compared to the model group, gavage administration of low-GI bread improved the levels of TC, TG, HDL-C, and LDL-C in diabetic mice, with a decrease in TC, TG, and LDL-C levels, while HDL-C levels increased by 12.1% compared to the model group. In conclusion, the low-GI bread prepared in this invention exerts its hypoglycemic function by improving insulin resistance and regulating lipid metabolism in diabetic mice.

[0101] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A highland barley composite powder, characterized in that, It comprises the following components: 100 parts by weight of black barley flour, 25-35 parts by weight of wheat gluten, and 25-35 parts by weight of wheat flour and rye flour. The mass ratio of wheat flour to rye flour is 1:(1-3).

2. The highland barley composite powder according to claim 1, characterized in that, The mass ratio of wheat flour to rye flour is 1:

1.

3. A type of barley bread, characterized in that, It is prepared from the following raw materials: 100 parts by weight of the highland barley compound powder as described in claim 1 or 2, and 0.1-0.3 parts by weight of the enzyme preparation.

4. The barley bread according to claim 3, characterized in that, The enzyme preparation is composed of maltose amylase, lipase and β-glucanase in a mass ratio of (60-65):1:(1200-1300).

5. The barley bread according to claim 3, characterized in that, The ingredients also include: 45-70 parts by weight of water, 10-20 parts by weight of whole egg liquid, 6-12 parts by weight of butter, 1-2 parts by weight of yeast, 0.5-1 part by weight of salt, 1-2 parts by weight of sugar, and 4-16 parts by weight of sugar alcohol.

6. A method for preparing barley bread according to any one of claims 3-5, characterized in that, Includes the following steps: S1. Prepare the starter dough and let it ferment; S2. Add the fermented starter dough to the main dough mix to make the main dough; S3. Let the main dough rest and relax, divide and shape it, let it rise, and then bake it to get barley bread.

7. The preparation method according to claim 6, characterized in that, In step S1, the starter dough includes the following ingredients: black barley flour, wheat flour, yeast, maltose amylase, and β-glucanase; The mass ratio of black highland barley flour to wheat flour is (4-8):1; The mass ratio of yeast to wheat flour is (0.07-0.09):1; Based on the sum of the masses of black barley flour and wheat flour, the amount of maltose amylase added is 140-160 mg / kg; the amount of β-glucanase added is 2900-3100 mg / kg. The fermentation conditions are: fermentation for 20-40 minutes at a relative humidity of 80% and a temperature of 30℃.

8. The preparation method according to claim 6, characterized in that, In step S2, the raw materials of the main dough mixing powder include: black barley flour, wheat gluten, wheat flour, rye flour, yeast, maltose amylase, β-glucanase, and lipase. The mass ratio of black barley flour, gluten flour, wheat flour and rye flour is (4-8):(3-5):1:(1-3). Based on the sum of the masses of black barley flour, wheat gluten, wheat flour, and rye flour, the amount of maltose amylase added is 100-120 mg / kg, the amount of β-glucanase added is 2100-2300 mg / kg, and the amount of lipase added is 2-4 mg / kg. In step S3, the conditions for proofing are: proofing for 90-120 minutes at a relative humidity of 80% and a temperature of 38°C. The baking conditions are: top heat temperature 170-190℃, bottom heat temperature 190-210℃, and baking time 20-30 min.

9. A dietary product that aids in blood sugar management, characterized in that, Its raw materials include: the highland barley compound powder as described in claim 1 or 2.

10. The dietary product according to claim 9, characterized in that, The blood glucose management includes one of the following: weight loss, lowering fasting blood glucose, lowering serum insulin, lowering cholesterol, improving oral glucose tolerance, and improving insulin sensitivity.

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