Low-GI highland barley bread and preparation method thereof

Abstract

The invention belongs to the technical field of food, and discloses low-GI highland barley bread and a preparation method thereof. The low-GI highland barley bread is characterized by comprising the following raw materials in percentage by weight: 12%-28% of highland barley compound powder, 10%-24% of wheat flour, 0.6%-1% of stachyose compound prebiotic powder, 10%-13% of vital gluten, 6%-9% of a sweetening agent, 0.3%-0.5% of a modifying agent, 0.03%-0.15% of a preservative, 0.3%-0.5% of an emulsifying agent, 1%-2% of glycerol and 6%-8% of eggs. 4%-5% of butter, 1%-2% of yeast, 25%-30% of water and 0.4%-0.5% of salt. The low-GI highland barley bread prepared from the highland barley compound powder provided by the invention not only can meet the nutritional requirements of consumers for staple food bread products, but also better meets the health demands of the consumers for stabilizing and controlling sugar.

Description

Technical Field

[0001] The invention belongs to the technical field of food, and particularly relates to low GI highland barley bread and a preparation method thereof. Background Art

[0002] Bread is one of the most popular baked products among consumers. Most breads on the market are made from refined wheat flour without bran and other components. Although this gives bread a soft texture and a beautiful appearance, it has a fast blood sugar rise and a high glycemic index (GI). Long-term consumption of this type of bread can not only lead to excessive intake of refined carbohydrates, but also lead to a lack of dietary fiber, vitamins, minerals and other nutrients, leading to the occurrence of various chronic diseases such as diabetes and obesity due to unbalanced dietary nutrient intake.

[0003] In recent years, with the deepening of research, the health benefits of cereal bran have gradually attracted people's attention. Bran is a nutritious byproduct formed during the processing of cereals, containing a large amount of dietary fiber, protein, carbohydrates, B vitamins, minerals, plant compounds, etc. Taking wheat bran as an example, it is rich in dietary fiber, with a content of up to 63%. Dietary fiber includes soluble and insoluble. Soluble dietary fiber is mainly β-glucan, and insoluble dietary fiber is mainly cellulose, lignin and xylan, etc., which have pharmacological effects such as lowering blood sugar, lowering blood lipids, anti-oxidation, anti-virus, and regulating immunity. Studies have shown that insoluble dietary fiber can also promote gastrointestinal peristalsis and digestion, accelerate the metabolism of nutrients and the excretion of toxic substances in the human body. In addition, wheat bran also contains active substances such as phenolic acid, which can directly and effectively reduce the glycemic ability of cereal raw materials by inhibiting the activity of starch digestive enzymes.

[0004] At present, research on the use of grain flour to partially replace refined wheat flour to prepare slow-glycemic bread has gradually emerged. Commonly used grain flour raw materials mainly come from bulk grains such as highland barley, oats, and buckwheat. Among them, highland barley is the main food crop in plateau areas, with a reasonable nutritional structure, and is a high-quality source of healthy staple food. Highland barley has relatively high protein content, cellulose content and vitamin content, while relatively low sugar and fat content; it also contains oleic acid, linoleic acid, linolenic acid, etc., which have cholesterol-lowering effects. Studies have shown that both protein and dietary fiber can reduce the GI value of food by delaying the digestion of starch. In addition, the β-glucan contained in highland barley not only has the effects of lowering blood lipids, lowering cholesterol and preventing cardiovascular diseases, but also has the effects of regulating blood sugar and improving immunity. Studies have found that highland barley β-glucan, as a soluble dietary fiber, can delay the digestion and absorption of carbohydrates by increasing the viscosity of the food digestive system, thereby reducing the digestion rate of starch and the GI value of food. It is a high-quality raw material for the development of low-GI products. However, the raw materials for industrial production of highland barley flour currently include highland barley core flour and whole barley flour. The application characteristics of whole barley flour are relatively poor, and the products made from it have problems such as rough texture and poor flavor; the application characteristics of highland barley core flour are relatively good, but it lacks the rich nutrients in the bran. Therefore, through the reasonable compounding of refined highland barley core flour and bran flour, it may be possible to achieve a balance between processing characteristics and nutritional and health attributes. Research on the digestibility characteristics of bran and grain flour raw materials mainly focuses on the effects of adding grain bran from different sources on starch digestion in grain flour, the effects of grain bran digestion on human intestinal health, and the effects of different processing techniques or particle size on the structure, physical and chemical properties and functional properties of grain bran.

[0005] Different processing techniques such as ultrafine grinding, dry heat process, microwave, extrusion, etc. can also affect the antioxidant activity of bran and its functional properties such as water holding, swelling, oil binding capacity and nitrite ion absorption capacity. In addition, the powder properties of bran of different particle sizes obtained after ultrafine grinding, the rheological properties after digestion, and the content of active ingredients such as dietary fiber and polyphenols are significantly different, indicating that the processing and application characteristics and functional properties of bran of different particle sizes are different. However, there is no research on the influence of bran particle size on starch digestion in cereals. The particle size of bran raw materials currently produced industrially is mainly fixed at 40 mesh (particle size 380μm), and the bran particle size is relatively large, which not only lacks processing characteristics and flavor, but also limits the role of functional characteristics.

[0006] For example, Chinese patent CN109362836A discloses a black highland barley cake, which includes the following raw materials in parts by weight: 55-65 parts of black highland barley flour, 10-15 parts of walnut kernel flour, 20-25 parts of highland barley malt flour, 15-25 parts of wheat bran flour, 5-8 parts of fungus powder, 4-6 parts of kudzu root powder, 5-7 parts of fish bone powder, 8-11 parts of honey, 9-14 parts of butter tea, 3-5 parts of corn oil, 0.5-1 parts of honeysuckle extract, 2-4.5 parts of starch syrup, 2-3.5 parts of sorbitol liquid, 4-5.5 parts of baking soda, and 1.5-2.5 parts of soda ash. The invention selects natural ingredients and reasonably matches them, giving full play to their respective advantages, complementing and promoting each other, making the effect of fusion more excellent, making the black barley cake of the invention nutritious and easy to be absorbed by the human body after consumption; unique flavor, suitable for a wide range of consumer groups; can be eaten as a staple food for a long time without getting angry, constipation, etc.; fine texture, soft taste, good flavor, good quality. However, the millet bran particle size of the invention is screened by 80-90 mesh, and the particle size is relatively large, which affects the flavor.

[0007] Another example is Chinese patent CN115997889A, which provides a noodle with blood sugar regulating effect and a preparation method thereof, which relates to the field of food. The noodle comprises the following raw material components by weight: 8-15 parts of wheat bran, 20-30 parts of white kidney bean powder, 20-30 parts of highland barley powder, 20-28 parts of soybean powder, 10-20 parts of sorghum powder, 10-25 parts of quinoa powder, 3-8 parts of mushroom powder, 20-28 parts of egg liquid, 8-12 parts of gluten powder, 10-20 parts of dietary polysaccharides, and 21-27 parts of water. The noodles provided by the invention meet the low GI index, can significantly reduce the dissolution and absorption of glucose in the noodles, inhibit the increase of blood sugar after meals and reduce fat intake, have outstanding blood sugar regulating effects, expand the range of products for patients with high blood sugar and high blood lipids, and are suitable for patients with high blood sugar and high blood lipids to eat as a staple food for a long time, improving the sub-health status of people with three highs. The ingredients are reasonably matched, combined with conditioning, comprehensive nutrition, and strong satiety. However, the invention also has the problem that the bran particle size is relatively large.

[0008] Therefore, research on the effect of bran particle size on the digestibility of cereal flour is urgently needed and should provide a certain theoretical basis for the production of industrial bran raw materials. Summary of the invention

[0009] Based on the problems existing in the prior art, the present invention aims to provide a low GI highland barley bread and a preparation method thereof. The low GI highland barley bread prepared from the highland barley composite powder provided by the present invention can not only meet the nutritional needs of consumers for staple bread products, but also meet the health demands of consumers for stabilizing and controlling blood sugar.

[0010] In order to achieve the above object, the present invention adopts the following technical solutions:

[0011] On the one hand, the present invention provides low GI highland barley bread, which comprises the following raw materials by weight percentage: 12%-28% highland barley compound flour, 10%-24% wheat flour, 0.6%-1% prebiotic powder, 10%-13% gluten powder, 6%-9% sweetener, 0.3%-0.5% improver, 0.1%-0.15% preservative, 0.3%-0.5% emulsifier, 1%-2% glycerol, 6%-8% eggs, 4%-5% butter, 1%-2% yeast, 25%-30% water and 0.4%-0.5% salt.

[0012] Preferably, the low GI highland barley bread comprises the following raw materials by weight percentage: 20.3% highland barley compound flour, 17.18% wheat flour, 0.65% prebiotic powder, 11.12% gluten powder, 7.79% sweetener, 0.32% improver, 0.13% preservative, 0.44% emulsifier, 1.11% glycerol, 7.31% egg, 4.17% butter, 1.11% yeast, 27.93% water, and 0.44% salt.

[0013] Preferably, the highland barley compound powder comprises the following raw materials by weight percentage in the highland barley compound powder: 75%-85% highland barley powder, 15%-25% wheat bran powder;

[0014] Preferably, the highland barley compound powder comprises the following raw materials by weight: 80% highland barley powder and 20% wheat bran powder;

[0015] Preferably, the mass ratio of highland barley flour to wheat bran flour in the highland barley composite flour is 4:1;

[0016] Preferably, the particle size of the wheat bran powder is 100-220 mesh, preferably 160-220 mesh, and more preferably 160 mesh.

[0017] Preferably, the sweetener comprises the following raw materials: maltitol, trehalose and sorbitol;

[0018] Preferably, the sweetener comprises the following raw materials by weight percentage: 2%-3% maltitol, 2%-3% trehalose and 2%-3% sorbitol;

[0019] Preferably, the sweetener comprises the following raw materials by weight percentage: 2.92% maltitol, 2.09% trehalose and 2.78% sorbitol.

[0020] Preferably, the preservative is selected from one or two of sodium benzoate, whey fermentation powder, potassium sorbate or calcium propionate; preferably calcium propionate and whey fermentation powder.

[0021] Preferably, the emulsifier is selected from one of mono- and di-glycerol fatty acid esters, soybean lecithin, polyglycerol fatty acid esters, sucrose fatty acid esters or glycerol monostearate; preferably mono- and di-glycerol fatty acid esters.

[0022] Preferably, the prebiotic powder is stachyose composite prebiotic powder.

[0023] As a preferred embodiment, the low GI highland barley bread comprises the following raw materials by weight percentage: 20.3% highland barley compound flour, 17.18% wheat flour, 0.65% stachyose composite prebiotic powder, 11.12% gluten, 2.92% maltitol, 2.09% trehalose and 2.78% sorbitol, 0.32% improver, 0.03% calcium propionate, 0.1% whey fermentation powder, 0.44% mono- and di-glycerol fatty acid esters, 1.11% glycerol, 7.31% eggs, 4.17% butter, 1.11% yeast, 27.93% water, and 0.44% salt.

[0024] On the other hand, the present invention also provides a method for preparing low GI highland barley bread, comprising the following steps:

[0025] (1) Weighing materials: weigh highland barley composite flour, wheat flour, stachyose composite prebiotic powder, gluten powder, improver, preservative, and emulsifier according to the formula proportion, mix evenly, and obtain raw material A for later use; weigh sweetener, glycerin, egg, water, and salt according to the formula proportion, mix evenly, and obtain raw material B for later use;

[0026] (2) Kneading: Mix raw material A and raw material B, knead the dough, and stir from low speed to high speed for 10-15 minutes. After the dough is formed into a film, add butter with a specific gravity of the formula, continue to stir evenly, and try to form a glove film. Control the dough temperature ≤28°C;

[0027] (3) Shaping: Divide the dough into 65g pieces each and knead them into European-style buns;

[0028] (4) Proofing: Place in a proofing box at 32°C and 80% humidity for 80-90 minutes;

[0029] (5) Baking: Place the proofed dough into an oven at an upper temperature of 155-160° C. and a lower temperature of 150-155° C., bake for 30 minutes, and place the dough out of the oven for 10-20 minutes to obtain the bread.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The present invention first compares the processing and digestion characteristics of the composite powder obtained by compounding bran powder with highland barley powder of different particle sizes, determines the optimal particle size of bran powder, and obtains the slowly digestible highland barley composite powder. Then, the slowly digestible highland barley composite powder is used as the basic formula, and the gluten and wake-up characteristics of the coarse grain bread are improved by optimizing the composition of other ingredients and processes, and maltitol, trehalose, and sorbitol are used to replace the sucrose used in traditional bread making and reasonably compounded to make the bread sweetness suitable and not easy to cause dental caries. The product appropriately reduces the content of protein and oil on the basis of ensuring excellent texture characteristics, and increases dietary fiber, so that the product is more in line with the nutritional needs of diabetic people. In addition, the product is specially added with composite prebiotic powder, which not only helps intestinal health, but also is more conducive to stabilizing postprandial blood sugar. After the product is baked, it has a soft mouthfeel without losing gluten, original wheat color, wheat flavor, soft and chewy, and suitable sweetness, which meets the national dietary preferences, and the GI value is ≤55, which belongs to low GI food. Protein ≥12g / 100g is considered a high-protein food; dietary fiber ≥6g / 100g is considered a high-dietary fiber food. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is the solubility diagram of highland barley powder with different particle sizes;

[0033] Figure 2 This is the expansion diagram of highland barley compound powder with different particle sizes;

[0034] Figure 3 This is the color difference diagram of low GI highland barley bread at different particle sizes;

[0035] Figure 4 This is the color difference diagram of low GI highland barley bread with different addition amounts;

[0036] Figure 5 This is the curve of hydrolysis rate of highland barley compound powder in vitro;

[0037] Figure 6 This is a blood glucose response curve (*p<0.05 means a significant difference, **p<0.01 means an extremely significant difference). DETAILED DESCRIPTION

[0038] The technical scheme of the present invention is clearly and completely described below with specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention. The materials, reagents, etc. used, if not otherwise specified, are reagents and materials available from commercial sources.

[0039] Unless otherwise defined, all professional and scientific terms used herein have the same meanings as those known to those skilled in the art. For example, "percentage" as described in the text refers to "percentage by weight".

[0040] In addition, any methods and materials similar or equivalent to those described herein can be applied to the methods of the present invention. The preferred implementation methods and materials described herein are for demonstration purposes only.

[0041] Basic comparative example 1: a highland barley compound powder

[0042] The components include:

[0043] According to the proportion in the highland barley compound flour, 80% highland barley flour and 20% 40 mesh wheat bran flour.

[0044] Basic Example 1 A kind of highland barley compound powder

[0045] The components include:

[0046] According to the proportion in the highland barley compound flour, 80% highland barley flour and 20% 100 mesh wheat bran flour.

[0047] Basic Example 2 A kind of highland barley composite powder

[0048] The components include:

[0049] According to the proportion in the highland barley compound flour, 80% highland barley flour and 20% 160 mesh wheat bran flour.

[0050] Basic Example 3 A kind of highland barley composite powder

[0051] The components include:

[0052] According to the proportion in the highland barley compound flour, 80% highland barley flour and 20% 220 mesh wheat bran flour.

[0053] Effect verification:

[0054] Test Example 1 Solubility, swelling, gelatinization characteristics and in vitro digestion and hydrolysis rate test

[0055] (1) Solubility and swelling test

[0056] First, wheat bran powder of 40-220 mesh (68 μm-380 μm) was sieved, and 80% of highland barley powder and 20% of wheat bran powder were compounded according to the proportion in highland barley compound powder to obtain compound powder. Then, 3.0 g of highland barley compound powder of different particle sizes and single highland barley powder (control group) were weighed to measure their solubility and swelling during gelatinization.

[0057] First, record the mass of the centrifuge tube and the mass of the sample in the centrifuge tube, accurately add 90 mL of distilled water to the centrifuge tube and shake to mix, stir and heat the sample in a water bath at 55°C, 75°C, and 95°C for 30 minutes, take it out and cool it to room temperature, then centrifuge it at 5000r / min for 10 minutes. Then pour the supernatant into an aluminum box that has been dried to constant weight, evaporate it in a boiling water bath, and then dry it in a constant temperature drying oven at 105°C to constant weight, and weigh the mass; invert the centrifuge tube with the supernatant removed on filter paper to drain, and weigh the mass. Calculate the solubility and swelling of the sample according to the following calculation formula:

[0058]

[0059]

[0060] Where: m0 is the sample mass, g; m1 is the centrifuge tube mass, g; m2 is the centrifuge tube mass after removing the supernatant, g; m3 is the supernatant mass after drying to constant weight, g.

[0061] Depend on Figure 1 It can be seen that the solubility of highland barley powder is closely related to temperature. When the temperature rises from 55℃ to 75℃, the solubility of all particle size powders decreases. When the temperature rises from 75℃ to 95℃, the solubility of the powder increases again. This may be because the temperature gradually increases, the protein gradually denatures, and its solubility decreases; and when the temperature rises from 75℃ to 95℃, the protein denaturation weakens its interaction with water, loses its inhibitory effect on starch dissolution, and starch hydrolysis gradually increases, and then the solubility gradually increases.

[0062] In addition, the solubility of highland barley powder under different particle sizes also changes. As the particle size decreases, the solubility of the compound increases first and then decreases. It may be that the powder with smaller particle size is in more complete contact with water molecules, and is more likely to absorb water and swell during heating. More amylose and small amylopectin particles break free from the constraints, escape from the swollen starch particles and dissolve in water, resulting in increased solubility. As the particle size decreases to 220 mesh, the solubility decreases instead.

[0063] Depend on Figure 2 It can be seen that the expansion degree of highland barley compound powder is positively correlated with temperature. As the temperature increases, the expansion degree of the compound powder gradually increases, which may be caused by the increase in the water absorption capacity of the cereal powder with the increase in temperature. In addition, the expansion degree of the compound powder is also positively correlated with the particle size. The smaller the particle size, the smaller the expansion degree of the compound powder. This phenomenon is more obvious under high temperature conditions. This may be because the components in the cereal powder with smaller particle size have relatively lower water absorption capacity.

[0064] Solubility and swelling are important indicators that reflect the interaction between starch and water. The factors that affect the solubility of compound powder solution are: ① Starch absorbs water and swells, and starch molecules gradually precipitate and dissolve in water, causing the solubility to increase; ② Protein will also partially dissolve in water as the temperature rises, but when the temperature is higher than the protein denaturation temperature, it denatures, the molecular spatial structure is destroyed, the internal hydrophobic group is exposed, and the molecules precipitate, causing the protein solubility to decrease; ③ The interaction between protein and water will hinder starch from absorbing water, and have a certain inhibitory effect on starch dissolution. The solubility increases with the increase of temperature, because the interaction between protein and water weakens and loses the inhibitory effect on starch dissolution. The particle size has a certain effect on the solubility and swelling of highland barley compound powder, which is manifested as the solubility first increases and then decreases with the decrease of particle size, while the swelling gradually decreases. It shows that particle size may have a certain effect on the gelatinization and digestibility of cereal flour.

[0065] (2) Gelatinization characteristics test

[0066] Weigh 3.5g highland barley compound powder, add it to a special aluminum can filled with 25mL distilled water, stir it thoroughly with a rotating paddle, and quickly place it in a rapid viscosity tester (RVA). Test conditions: The initial stirring speed is 960r / min, and then maintained at 160r / in until the end of the experiment. The temperature is maintained at 50℃ for the first 1min, then increased to 95℃ at a rate of 12℃ / min, maintained at 95℃ for 2min, then decreased to 50℃ at a rate of 12℃ / min, and maintained at 50℃ for 2min. The whole process lasted 13min.

[0067] As shown in Table 1, the indicators of the gelatinization characteristics of highland barley compound powder at different particle sizes show that the peak viscosity, minimum viscosity, final viscosity, disintegration value and recovery value of the 220-mesh compound powder are lower than those of the compound powders of other particle sizes. During the gelatinization process, the starch granule swelling degree, starch paste thermal stability, cold paste stability and coagulation are lower than those of the compound powders of other particle sizes, indicating that under the same gelatinization conditions, the 220-mesh compound powder has the lowest gelatinization degree.

[0068] As the particle size increases, the viscosity of the system shows a trend of first increasing and then decreasing. There are many factors that affect the viscosity of the system. In addition to the structure and properties of the starch itself, moisture and temperature are the main influencing factors, the viscous polysaccharides in the cereal flour will also affect the viscosity of the system. The viscosity of the 160-mesh compound flour is the highest. On the one hand, it is due to its high degree of gelatinization. On the other hand, it also shows that the polysaccharide content in the 160-mesh bran compound flour is relatively high, resulting in a higher viscosity of the 160-mesh compound flour system than other groups. Studies have shown that soluble polysaccharides in cereal flour can increase the viscosity of the system, delay the digestion of starch and the release of glucose, thereby reducing the digestion rate of starch.

[0069] Table 1

[0070]

[0071] Note: Different letters in the same column indicate significant differences (p<0.05).

[0072] (3) In vitro digestion and hydrolysis rate test

[0073] The test was highland barley compound powder, whose available carbon content was 68.48%. Weigh 292 mg of highland barley compound powder containing 200 mg of available carbon, add 2.5 mL of water, gelatinize in boiling water for 10 min (note that water should be added first, then powder, and vortex mixed during gelatinization), and then quickly cool to room temperature. The blank group was 200 mg of water.

[0074] Table 2 shows the results of in vitro digestion and hydrolysis rate of highland barley compound powder at different particle sizes. The hydrolysis rates of bran compound powders with different mesh sizes were compared at 0 min. The hydrolysis rate of 160-mesh compound powder was the lowest, indicating that after gelatinization, its reducing sugar content was relatively low. As the digestion time increased, the 100-mesh, 160-mesh and 220-mesh compound powder samples all reached the maximum digestibility at 40 min of digestion, and then remained stable, and there was no significant difference in the maximum digestibility.

[0075] Table 2

[0076]

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

[0078] Example 1 A low GI highland barley bread

[0079] Including the following raw materials:

[0080] According to the proportion in the highland barley compound flour, 20% of 100-mesh wheat bran flour was added, and the remaining formula contents were shown in Table 3.

[0081] Table 3

[0082] Ingredients Proportion (%) wheat flour 24.00 Highland barley compound powder (different wheat bran powder particle size) 12.48 Stachyose compound prebiotic powder 0.65 Improver 0.32 Gluten 11.12 Mono- and di-glycerol fatty acid esters 0.44 Calcium Propionate 0.03 Whey fermented powder 0.10 Salt 0.44 Maltitol 2.92 Trehalose 2.09 yeast 1.11 water 27.93 Sorbitol 2.78 glycerin 1.11 egg 7.81 butter 4.67 total 100.00

[0083] Example 2 A low GI highland barley bread

[0084] Including the following raw materials:

[0085] According to the proportion in the highland barley compound flour, 20% of 160 mesh wheat bran flour was added, and the remaining formula contents were shown in Table 4.

[0086] Table 4

[0087] Ingredients Proportion (%) wheat flour 17.18 Highland barley compound powder (different wheat bran powder particle size) 20.30 Stachyose compound prebiotic powder 0.65 Improver 0.32 Gluten 11.12 Mono- and di-glycerol fatty acid esters 0.44 Calcium Propionate 0.03 Whey fermented powder 0.10 Salt 0.44 Maltitol 2.92 Trehalose 2.09 yeast 1.11 water 27.93 Sorbitol 2.78 glycerin 1.11 egg 7.31 butter 4.17 total 100.00

[0088] Example 3 A low GI highland barley bread

[0089] Including the following raw materials:

[0090] According to the proportion in the highland barley compound flour, 20% of 220 mesh wheat bran powder was added, and the remaining formula contents were as shown in Table 5.

[0091] Table 5

[0092] Ingredients Proportion (%) wheat flour 10.21 Highland barley compound powder (different wheat bran powder particle size) 27.27 Stachyose compound prebiotic powder 0.65 Improver 0.32 Gluten 11.12 Mono- and di-glycerol fatty acid esters 0.44 Calcium Propionate 0.03 Whey fermented powder 0.10 Salt 0.44 Maltitol 2.92 Trehalose 2.09 yeast 1.11 water 27.93 Sorbitol 2.78 glycerin 1.11 egg 7.31 butter 4.17 total 100.00

[0093] Comparative Example 1: A low GI highland barley bread

[0094] Low GI highland barley bread

[0095] Including the following raw materials:

[0096] According to the proportion in the highland barley compound flour, 20% of 40 mesh wheat bran powder, the remaining formula contents are shown in Table 3.

[0097] Effect verification:

[0098] Test Example 2 Property test of low GI highland barley bread made from highland barley flour compounded with wheat bran flour of different particle sizes

[0099] The addition amount of highland barley powder was fixed at 20.3%, and the effects of highland barley powder A (40 mesh), B (100 mesh), C (160 mesh), and D (220 mesh) of different particle sizes on bread quality were weighed. The reference formula of bread is shown in Table 3, and the bread making process is as follows. The evaluation indicators include bread pore distribution, specific volume, texture, color difference, etc.

[0100] The above bread recipe is prepared according to the following process:

[0101] (1) Weighing materials: weigh highland barley composite flour, wheat flour, stachyose composite prebiotic powder, gluten powder, improver, mono- and di-glycerol fatty acid esters, and calcium propionate according to the formula proportion, mix evenly, and obtain raw material A for later use; weigh maltitol, trehalose, sorbitol, glycerol, egg, water, and salt according to the formula proportion, mix evenly, and obtain raw material B for later use;

[0102] (2) Kneading: Mix raw material A and raw material B, knead the dough, and stir from low speed to high speed for 10 minutes. After the dough is formed into a film, add butter with a specific gravity of the formula, continue to stir evenly, and try to form a glove film. Control the dough temperature to be ≤28°C;

[0103] (3) Shaping: Divide the dough into 65g pieces each and knead them into European-style buns;

[0104] (4) Proofing: Place in a proofing box at 32°C and 80% humidity for 80 minutes;

[0105] (5) Baking: Put the proofed dough into an oven with an upper heating temperature of 155° C. and a lower heating temperature of 150° C., bake for 30 minutes, and leave it out of the oven for 10 minutes to obtain the low GI highland barley bread.

[0106] (I) Determination of specific volume of bread

[0107] Refer to GB / T 20981-2007, i.e. millet filling method.

[0108] The bread was pre-treated as above, and weighed after being placed at room temperature, recorded as W (accurate to 0.01g). Fill the container with millet and scrape the surface of the container with a ruler, pour the required millet into the measuring cylinder, record the volume as V1, put the bread into the container, fill the excess part with millet and scrape it flat, measure the remaining millet volume V2, repeat 3 times and take the average.

[0109] The calculation formula is as follows:

[0110]

[0111] Where:

[0112] P--specific volume of bread (mL / g);

[0113] V1--container volume (mL);

[0114] V2--bread volume (mL);

[0115] W--bread mass (g).

[0116] As shown in Table 6, as the particle size of wheat bran powder decreases, the specific volume of bread shows an overall upward trend. This is because the bran itself can have a certain shearing effect on the fascia of the dough in the dough, thereby reducing the gluten of the dough, and then the proofing effect becomes worse and the specific volume becomes smaller. This effect can be gradually weakened as the particle size of wheat bran powder decreases. According to the specific volume results, the specific volume of the bread of 160 mesh compound flour and 220 compound flour is relatively high, while the specific volume of the bread of 160 mesh compound flour can reach 4, indicating that the 160 mesh compound flour has the least effect on the gluten of the dough and the state of the bread.

[0117] Table 6

[0118] sample specific volume A <![CDATA[3.49±0.14 ab ]]> B <![CDATA[3.38±0.18 b ]]> C <![CDATA[4.04±0.09 a ]]> D <![CDATA[3.71±0.18 ab ]]>

[0119] Note: Different letters in the same column indicate significant differences (p<0.05).

[0120] (II) Bread texture characteristics

[0121] The puncture test method is used to measure hardness, viscosity and elasticity. The probe is a 6mm diameter cylindrical probe with a puncture depth of 10mm. The maximum force used during the puncture is hardness (N), and the maximum force required for the probe to rise is viscosity (N); elasticity is the opposite of viscosity. The probe is a P / 36 cylindrical probe; the operating mode is the TPA scheme; the probe induction force is 5g; the pre-test rate is 1mm / s, and the test and post-test rates are both 0.5mm / s; the target mode is strain 50%.

[0122] As can be seen from Table 7, compared with the 40-mesh compound flour bread, the hardness of the 100-mesh, 160-mesh and 220-mesh compound flour breads was significantly reduced, but there was no significant difference among the groups. Therefore, as the bran particle size decreases, the dough is easier to form a gluten network structure, the softness increases, and the hardness of the bread decreases.

[0123] The addition of bran of different particle sizes has little effect on the elasticity and chewiness of bread.

[0124] Adhesion refers to the work that must be done to overcome the attraction between the probe and the sample when they touch. When cohesion is greater than adhesion, the probe will not retain the sample. Since adhesion is much less than cohesion, there is no problem of sticking to the teeth in each group of bread.

[0125] Table 7

[0126]

[0127] Note: Different letters in the same column indicate significant differences (p<0.05).

[0128] (III) Bread color difference measurement

[0129] The color of bread was measured by a fully automatic colorimeter. The colorimeter needed to be preheated for 30 minutes before use. The bread was cooled and the center and surface of the bread were crushed with a grinder. After the white board was calibrated, 5g of the sample was weighed and placed in a transparent sample pool to measure the color. The measurement was repeated 3 times. The colorimeter is a color detection instrument that uses the CIE-L*a*b* color space to evaluate the color based on the three parameters of L*, a* and b*. Among them, the L* value indicates the black and white (brightness), and the larger the L* value, the brighter it is; a* and b* indicate the color direction, and the a* value indicates the change between red and green, and the larger the value, the redder it is; +a* value indicates the red direction, and -a* value indicates the green direction; b* value indicates the change between yellow and blue, and the larger the value, the yellower it is. +b* is the yellow direction, and -b* is the blue direction.

[0130] Color not only represents the quality of bread, but also determines consumers' acceptance of the product. Figure 3It can be seen that as the bran particle size decreases, the L* value of the bread crumb gradually increases, and the color of the bread crumb is brighter, indicating that the lower the bran particle size, the lighter the color of the bread crumb, and there are significant differences between different groups. Compared with the bread made from 40 mesh compound flour, the reduction of bran particle size significantly decreases the a* of the bread crumb and significantly increases the b*, indicating that the red color is getting lighter and the yellow color is getting heavier, but there is no significant difference between the breads made from 100-220 mesh compound flours.

[0131] Example 4 A low GI highland barley bread

[0132] Including the following raw materials:

[0133] According to the proportion in the highland barley compound flour, the addition amount of 160 mesh wheat bran powder is 15%, and the remaining formula contents are shown in Table 8.

[0134] Table 8

[0135]

[0136] Example 5 A low GI highland barley bread

[0137] Including the following raw materials:

[0138] According to the proportion in the highland barley compound flour, the addition amount of 160 mesh wheat bran powder is 20%, and the remaining formula contents are shown in Table 8.

[0139] Example 6 A low GI highland barley bread

[0140] Including the following raw materials:

[0141] According to the proportion in the highland barley compound flour, the addition amount of 160 mesh wheat bran flour is 25%, and the remaining formula contents are shown in Table 8.

[0142] Comparative Example 2: A low GI highland barley bread

[0143] Including the following raw materials:

[0144] According to the proportion in the highland barley compound flour, the addition amount of 160 mesh wheat bran powder is 10%, and the remaining formula contents are shown in Table 8.

[0145] Effect verification:

[0146] Test Example 3 Property test of low GI highland barley bread made from highland barley flour compounded with different addition amounts of wheat bran flour

[0147] The addition amount of highland barley flour was fixed at 20.3%, the optimal particle size of wheat bran flour was 160 mesh, and the addition amount of wheat bran flour in highland barley flour was set to 10%, 15%, 20% and 25% respectively according to the proportion in highland barley flour. The effect of the addition ratio of bran in the flour on the quality of bread was tested. The reference formula of bread is shown in Table 8 above, and the process is as follows. The evaluation indicators include bread pore distribution, specific volume, texture, color difference, etc.

[0148] The above bread recipe is prepared according to the following process:

[0149] (1) Weighing materials: weigh highland barley composite flour, wheat flour, stachyose composite prebiotic powder, gluten powder, improver, preservative, and emulsifier according to the formula proportion, mix evenly, and obtain raw material A for later use; weigh sweetener, glycerin, egg, water, and salt according to the formula proportion, mix evenly, and obtain raw material B for later use;

[0150] (2) Kneading: Mix raw material A and raw material B, knead the dough, and stir from low speed to high speed for 15 minutes. After the dough is formed into a film, add butter with a specific gravity of the formula, continue to stir evenly, and try to form a glove film. Control the dough temperature to be ≤28°C;

[0151] (3) Shaping: Divide the dough into 65g pieces each and knead them into European-style buns;

[0152] (4) Proofing: Place in a proofing box at 32°C and 80% humidity for 80-90 minutes;

[0153] (5) Baking: Place the proofed dough into an oven with an upper heating temperature of 160° C. and a lower heating temperature of 155° C., bake for 30 minutes, and leave it out of the oven for 20 minutes to obtain the bread.

[0154] (I) Determination of specific volume of bread

[0155] The test method is the same as that of Test Example 2. The results are shown in Table 9. As shown in Table 9, the specific volume of bread made with different addition amounts of wheat bran flour is distributed around 4, and there is no significant difference. The addition amount of wheat bran flour has no significant effect on the specific volume of bread.

[0156] Table 9

[0157] sample Specific volume (mL / g) 10% wheat bran flour added to bread <![CDATA[4.33±0.07 a ]]> 15% wheat bran flour added to bread <![CDATA[3.96±0.15 a ]]> 20% wheat bran flour added to bread <![CDATA[4.31±0.08 a ]]> 25% wheat bran flour added bread <![CDATA[4.14±0.11 a ]]>

[0158] Note: Different letters in the same column indicate significant differences (p<0.05).

[0159] (II) Bread texture characteristics

[0160] The test method is the same as that of Test Example 2. The results are shown in Table 10. As can be seen from Table 10, with the increase of the amount of bran added, the overall hardness of the bread tends to decrease, indicating that the addition of wheat bran powder with a particle size of 160 mesh will increase the softness of the bread and reduce the hardness.

[0161] The chewiness of bread is related to hardness, elasticity and cohesion. With the addition of wheat bran flour, the chewiness of bread showed an overall downward trend. Compared with the addition of 10%, the addition of 20% and 25% significantly decreased (p < 0.05). This shows that the addition of wheat bran flour does not lead to poor dough extensibility. The bread texture is still fluffy, but the chewiness is reduced.

[0162] Adhesion refers to the work that must be done to overcome the attraction between the probe and the sample when they touch. When cohesion is greater than adhesion, the probe will not retain the sample. Since adhesion is much less than cohesion, there is no problem of sticking to the teeth in each group of bread.

[0163] Table 10

[0164]

[0165]

[0166] Note: Different letters in the same column indicate significant differences (p<0.05).

[0167] (III) Bread color difference measurement

[0168] The test method is the same as that of Test Example 2. The results obtained are as follows Figure 4 shown. Figure 4 It can be seen that when the addition amount of bran in highland barley flour is between 10% and 25%, it has almost no effect on the L* and b* values ​​of bread. Compared with the addition amount of 10%, the a* of the bread crumb of the bread with the addition amount of 15%-25% significantly decreased and increased, indicating that the red color is getting lighter. Overall, the addition amount of wheat bran flour has little effect on the color of the bread crumb.

[0169] In summary, the effect of different amounts of wheat bran powder added on the quality of bread is that when the amount of wheat bran powder added is between 15% and 25%, the quality of bread shows a slight downward trend as the amount of wheat bran powder added increases, but there is no obvious difference overall. Considering the dietary fiber content of the bread formula, the amount of wheat bran powder added is determined to be a higher level of 20%.

[0170] Test Example 4: Verification of slow digestion of highland barley powder in vitro

[0171] Based on the above experimental results, the optimal particle size of wheat bran powder in highland barley powder was determined to be 160 mesh, and the appropriate amount of bran added was 20%, that is, the composition of the optimal highland barley powder was determined. Highland barley powder without bran was used as the control group, and the slow digestion characteristics of highland barley powder were verified through in vitro digestion experiments. Figure 5 As shown, compared with single highland barley powder (control group), the in vitro hydrolysis rate of highland barley powder was relatively low, and its final hydrolysis rate (69.04%) was significantly lower than that of single highland barley powder in the control group (79.14%) (P < 0.05).

[0172] Test Example 5 Determination of GI value of low GI highland barley bread

[0173] (1) GI test refers to ISO 26642:2010 and WS / T 652-2019. 12 healthy subjects who meet the criteria were selected according to the screening requirements. The subjects fasted for 10-14 hours from dinner the day before the experiment to the morning of the experiment, and collected two fasting blood samples at the test site. After the blood collection was completed, they ate the highland barley bread prepared in Example 2. The time was counted from the start of the subject's meal. The test substance and a cup of 250 mL of warm water were consumed within 5-10 minutes, and blood samples were collected at 15, 30, 45, 60, 90 and 120 minutes after the meal. The blood samples were centrifuged and the supernatant was taken to measure blood sugar on a biochemical analyzer. The subjects underwent a total of five experiments, three times with glucose water, one time with highland barley bread, and one time with white bread of the control group. The bread test was performed between the two glucose tests. The blood sugar change curves within 2 hours after the human body consumed the samples and glucose were drawn respectively. The incremental area under the curve (IAUC) within 2 hours after a person consumes 50 g of glucose is defined as 100, and the GI value of bread is calculated according to the following formula.

[0174] GI=I mean = Test food IAUC / reference food glucose IAUC×100

[0175] (2) GI test results

[0176] like Figure 6 As shown in the figure, the blood glucose response curve is a direct representation of the blood glucose fluctuation after eating a certain food. Comparing the blood glucose fluctuation curves of glucose, highland barley bread and the control group white bread after eating the same amount of AC, the blood glucose response caused by the two groups of bread is smaller than that of glucose, and the blood glucose fluctuation of highland barley bread is smaller than that of the control group white bread.

[0177] According to the blood glucose response curve, the reference food glucose and the control group white bread rose to the peak within the first 30 minutes, and the low GI barley bread slowly rose to the blood glucose peak 45 minutes after the meal, and its blood glucose peak was 79% of the reference food glucose and 89% of the blood glucose peak of the control group white bread; then the blood glucose level began to decline after the meal. Compared with glucose and the control group white bread, the downward trend of the blood glucose response curve of eating low GI barley bread was also very slow, which was conducive to stabilizing blood sugar.

[0178] The IAUC value of each subject 2 hours after eating the reference food glucose and the two groups of test food bread was calculated by the geometric method. The GI value of glucose was defined as 100, and the GI value of the control group white bread was calculated to be 77. GI 面包 =I 面包 =54, SE=4, SD=14 (as shown in Table 11).

[0179] Table 11

[0180]

[0181] After analysis, the valid data range of this test should be within the range of 53.80±2×13.90, that is, the GI value should be within the range of 26.00-81.60. The above 12 data all meet the requirements of the valid data range. Therefore, the GI value of low GI barley bread is I bread = 53.80, and the final GI value is revised to 54. Compared with ordinary white bread (GI = 77), the GI value of low GI barley bread is reduced by about 42.9%. Replacing daily white bread with low GI barley bread can greatly reduce daily post-meal blood sugar fluctuations.

Claims

1. A low GI highland barley bread, characterized in that: The invention comprises the following raw materials by weight percentage: 12%-28% highland barley compound flour, 10%-24% wheat flour, 0.6%-1% prebiotic powder, 10%-13% gluten powder, 6%-9% sweetener, 0.3%-0.5% improver, 0.03%-0.15% preservative, 0.3%-0.5% emulsifier, 1%-2% glycerol, 6%-8% egg, 4%-5% butter, 1%-2% yeast, 25%-30% water and 0.4%-0.5% salt.

2. The low GI highland barley bread according to claim 1, characterized in that: The highland barley compound powder comprises the following raw materials according to the weight percentage in the highland barley compound powder: 75%-85% highland barley powder and 15%-25% wheat bran powder.

3. The low GI highland barley bread according to claim 2, characterized in that: The highland barley compound powder comprises the following raw materials according to the weight percentage in the highland barley compound powder: 80% highland barley powder and 20% wheat bran powder.

4. The low GI highland barley bread according to claim 3, characterized in that: The particle size of the wheat bran powder is 100-220 meshes.

5. The low GI highland barley bread according to claim 1, characterized in that: Calculated by weight percentage, the sweetener comprises the following raw materials: 2%-3% maltitol, 2%-3% trehalose and 2%-3% sorbitol.

6. The low GI highland barley bread according to claim 5, characterized in that: Calculated by weight percentage, the sweetener includes the following raw materials: 2.92% maltitol, 2.09% trehalose and 2.78% sorbitol.

7. The low GI highland barley bread according to claim 1, characterized in that: The preservative is selected from one or two of sodium benzoate, whey fermentation powder, potassium sorbate or calcium propionate.

8. The low GI highland barley bread according to claim 1, characterized in that: The emulsifier is selected from one of mono- and di-glycerol fatty acid esters, soybean lecithin, polyglycerol fatty acid esters, sucrose fatty acid esters or glycerol monostearate.

9. The low GI highland barley bread according to claim 1, characterized in that: The prebiotic powder is stachyose composite prebiotic powder.

10. The low GI highland barley bread according to claim 1 or any one of claims 5 to 9, characterized in that: The low GI highland barley bread comprises the following raw materials by weight percentage: 20.3% highland barley compound flour, 17.18% wheat flour, 0.65% stachyose composite prebiotic powder, 11.12% gluten, 2.92% maltitol, 2.09% trehalose and 2.78% sorbitol, 0.32% improver, 0.03% calcium propionate, 0.1% whey fermentation powder, 0.44% mono- and di-glycerol fatty acid esters, 1.11% glycerol, 7.31% eggs, 4.17% butter, 1.11% yeast, 27.93% water and 0.44% salt.

11. The method for preparing low GI highland barley bread according to any one of claims 1 to 10, characterized in that: The steps include: (1) Weighing materials: weigh highland barley flour, wheat flour, prebiotic flour, gluten flour, improver, preservative, and emulsifier according to the formula proportion and mix them evenly to obtain raw material A for later use; weigh sweetener, glycerin, egg, water, and salt according to the formula proportion and mix them evenly to obtain raw material B for later use; (2) Kneading: Mix raw material A and raw material B, knead the dough, and stir from low speed to high speed for 10-15 minutes. After the dough is formed into a film, add butter with a specific gravity of the formula, continue to stir evenly, and try to form a glove film. Control the dough temperature ≤28°C; (3) Shaping: Divide the dough into 65g pieces each and knead them into European-style buns; (4) Proofing: Place in a proofing box at 32°C and 80% humidity for 80-90 minutes; (5) Baking: Place the proofed dough into an oven at an upper temperature of 155-160° C. and a lower temperature of 150-155° C., bake for 30 minutes, and place the dough out of the oven for 10-20 minutes to obtain the bread.

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