A low gi baked product based on microencapsulated tea polyphenols and a method of making the same

Abstract

This invention discloses a low-GI baked product based on microencapsulated tea polyphenols and its preparation method, belonging to the field of food processing technology. The low-GI baked product is made from raw materials comprising the following weight percentages: 60%-80% wheat flour, 5%-15% soy protein isolate, 3%-8% white sugar, 0.5%-2.5% guar gum, 3%-10% wheat fiber, 2%-6% oat β-glucan, 0.5%-1.5% edible salt, and 1.0%-4.0% microencapsulated tea polyphenols. The microencapsulated tea polyphenols use RS4, sodium caseinate, and acetylated konjac glucomannan as composite wall materials. Through microencapsulation technology, effective protection and flavor masking of tea polyphenols are achieved, resulting in a baked product with a stable GI value below 55, possessing both a soft and delicate texture and pure flavor. The premixed powder exhibits good storage and transportation stability, and the process is compatible with existing industrial production lines, significantly improving the overall quality of the low-GI baked product.

Description

Technical Field

[0001] This invention relates to the field of food processing technology, and in particular to a low-GI baked product based on microencapsulated tea polyphenols and its preparation method. Background Technology

[0002] With the increasing prevalence of metabolic diseases such as diabetes and obesity, consumers are increasingly demanding baked goods with a low glycemic index (GI). Traditional baked goods such as toast are mostly made with refined wheat flour, and their GI values ​​are generally greater than 70, making them unsuitable for people who need to control their blood sugar.

[0003] The core mechanism for lowering the GI value of food lies in slowing down the digestion and absorption of carbohydrates. Existing technologies have developed various methods to reduce the GI value of baked goods, mainly including: using dietary fiber or hydrocolloids to construct physical barriers that hinder the contact between digestive enzymes and starch; using proteins and soluble fiber to slow down gastric emptying; using natural polyphenols such as tea polyphenols to inhibit the activity of α-amylase and α-glucosidase; and using processing methods to induce starch retrogradation to form resistant starch.

[0004] However, existing low-GI baked goods and their preparation technologies still have many shortcomings in terms of industrialization and product quality that are difficult to balance.

[0005] First, existing technologies lack scientific synergy in the application of functional ingredients. Most solutions simply mix various blood sugar-lowering components, resulting in limited and unstable blood sugar-lowering effects, failing to achieve the desired low-GI target. Meanwhile, while natural amylase inhibitors such as tea polyphenols possess significant enzymatic inhibitory activity, they are extremely sensitive to heat and oxygen, degrading significantly under high baking temperatures. When added directly, their retention rate is typically less than 40%, almost completely losing their intended function. Furthermore, tea polyphenols themselves have a strong bitter taste, and direct addition severely damages the product's flavor.

[0006] Secondly, there is a significant contradiction between the excessive addition of functional ingredients and the sensory quality of the product. The large amounts of bran and insoluble fiber introduced to lower the glycemic index (GI) result in a rough, dry texture; the addition of high-protein ingredients leads to a dense texture and poor elasticity; and improper use of colloidal ingredients can cause unpleasant mouthfeel, such as stickiness. These sensory defects severely reduce consumer acceptance of the product.

[0007] Furthermore, the formulation of highly functional ingredients significantly alters the rheological properties of the dough. The dough exhibits abnormal water absorption, poor fermentation tolerance, and excessive stickiness, making it difficult to integrate with existing industrial production lines. Large-scale production often requires additional adjustments to process parameters or even equipment modifications, significantly increasing production difficulty and costs.

[0008] Finally, the product lacks stability during storage. High-fiber, high-protein premixed powders, due to the significant differences in the hygroscopicity of their components, are prone to layering, clumping, and loss of flowability during storage and transportation. Meanwhile, finished toast, with its high water activity, is more susceptible to starch retrogradation during its shelf life, leading to rapid deterioration in taste. Active ingredients also continuously diminish with prolonged storage, meaning the product's sugar-lowering function cannot be guaranteed within the stated shelf life.

[0009] Therefore, a technical solution is needed that can systematically resolve the above contradictions, achieving stable low GI values ​​while taking into account the sensory quality of the product, its suitability for industrial production, and its stability during storage and transportation. Summary of the Invention

[0010] This application provides a low-GI baked goods product based on microencapsulated tea polyphenols and its preparation method, solving the systemic technical problems in existing low-GI baked goods, such as the easy degradation and inactivation of active ingredients like tea polyphenols during processing and storage, the difficulty in masking bitterness, the rough and hard texture of products due to the addition of hypoglycemic functional ingredients such as high fiber and high protein, the deterioration of dough processing performance making it difficult to adapt to industrial continuous production, and the poor stability of premixed powder and finished products during storage and transportation, and the attenuation of hypoglycemic function. It provides a low-GI baked goods product and its preparation method with a stable GI value below 55, while also having a soft and delicate texture, pure flavor, excellent process adaptability, and long-term storage stability.

[0011] This application provides a low-GI baked goods product based on microencapsulated tea polyphenols, which is made from the following raw materials in parts by weight: 100 parts low-GI baking premix powder, 5-10 parts butter, 1-2 parts high-activity dry yeast, and 40-50 parts drinking water. The low-GI baking premix consists of the following components by weight percentage: Wheat flour 60%-80%; Soy protein isolate 5%-15%; White sugar 3%-8%; Guar gum 0.5%-2.5%; Wheat fiber 3%-10%; Oat beta-glucan 2%-6%; Edible salt content: 0.5%-1.5%; Microencapsulated tea polyphenols: 1.0%-4.0%; The sum of the weight percentages of the above components is 100%.

[0012] Furthermore, the wall material of the microencapsulated tea polyphenols is composed of RS4, sodium caseinate and acetylated konjac glucomannan in a mass ratio of 4-6:2-3:2-3.

[0013] Furthermore, the mass ratio of the wall material is 5:2.5:2.5.

[0014] Furthermore, the preparation method of the microencapsulated tea polyphenols includes the following steps: (1) Preparation of wall material solution: Weigh RS4, sodium caseinate and acetylated konjac glucomannan according to the proportion, dissolve them in pure water at 60-70℃, stir until completely dissolved, prepare a wall material solution with a mass fraction of 25%-35%, and cool to room temperature; (2) Preparation of core material solution: Dissolve tea polyphenols in pure water to prepare a core material solution with a mass fraction of 15%-25%, and add citric acid to adjust the pH to 4.0-5.0; (3) Emulsification and homogenization: Under high-speed shearing conditions of 10,000-12,000 rpm, the core material solution is slowly added to the wall material solution and sheared for 5-10 min to obtain the initial emulsion; then, it is homogenized under high pressure of 25-40 MPa 2-3 times to form a uniform O / W emulsion. (4) Spray drying: The obtained emulsion is spray dried with an inlet air temperature of 160-180℃, an outlet air temperature of 80-90℃, and an atomizer speed of 20000-30000 rpm. After drying, the emulsion is collected.

[0015] Furthermore, the low-GI baking premix is ​​prepared by a dry mixing process, including the following steps: (1) Pretreatment: Wheat flour and soy protein isolate are passed through a 60-mesh sieve; (2) Premixing: Guar gum, edible salt and wheat flour in a ratio of 10 times their total weight are premixed to obtain premix A; oat β-glucan, wheat fiber and some wheat flour are premixed to obtain premix B; (3) Overall mixing: Put the remaining basic powder into the mixer, add premix B and premix A in sequence, and finally add microencapsulated tea polyphenols, and mix for 25-35 min; (4) Sieving and packaging: Pass through an 80-mesh sieve and use aluminum foil composite bags for nitrogen filling or vacuum packaging to obtain premixed powder.

[0016] Furthermore, the low-GI baked product is toast.

[0017] A method for preparing low-GI roasted products based on microencapsulated tea polyphenols includes the following steps: (1) Ingredients: By weight, 100 parts of the prepared premixed powder, 5-10 parts of butter, 1-2 parts of high-activity dry yeast, and 40-50 parts of drinking water; (2) Mixing: Mix the premixed powder and dry yeast evenly, add water and mix into a dough, then add softened butter and mix until the gluten is fully developed; (3) Fermentation: The conditions for the first fermentation are a temperature of 30-40℃, a relative humidity of 75%-85%, and a time of 40-60 min, until the dough volume expands to 2 times; the conditions for the second fermentation are a temperature of 35-38℃, a relative humidity of 80%-90%, and a time of 50-70 min, until the dough ferments to 8-9 / 10 of the mold's capacity. (4) Baking: Bake at 180-190℃ for the top heat and 170-180℃ for the bottom heat for 25-35 minutes. After cooling, you will get low-GI baked goods.

[0018] Furthermore, step (2) mixing adopts a two-step method: first, dry mix the premixed powder with the dry yeast, add water and mix at low speed for 3 minutes to form a dough, then add softened butter and mix at high speed for 5-7 minutes until the gluten is fully developed, and control the final temperature of the dough at 26-27℃.

[0019] An application of low-GI baked goods based on microencapsulated tea polyphenols, specifically in the preparation of foods with a GI ≤ 55.

[0020] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages: Existing technologies often rely on a single mechanism for lowering blood sugar, which is easily affected by individual differences and dietary combinations, resulting in large fluctuations in the glycemic index (GI). This invention constructs a triple blood sugar-lowering mechanism through a synergistic formulation, utilizing physical barriers, gel barriers, and enzyme inhibition barriers: wheat fiber breaks down starch clumps to form a physical barrier; guar gum, oat β-glucan, soy protein isolate, and hydrophilic components of the microcapsule wall material form a high-viscosity gel barrier, delaying gastric emptying and enzyme diffusion; microencapsulated tea polyphenols are released in the intestine to inhibit α-amylase and α-glucosidase activity, blocking starch breakdown at its source. This triple barrier covers the entire process of carbohydrate digestion and absorption, resulting in a stable blood sugar-lowering effect. Human trials have verified that the GI value of the toast product of this invention is consistently between 42 and 45, significantly lower than that of ordinary white toast (GI≥70).

[0021] Tea polyphenols are extremely sensitive to heat and oxygen, with a retention rate of less than 40% under high-temperature baking without protection. Furthermore, the direct addition of their bitterness severely degrades the product's flavor. This invention uses RS4, sodium caseinate, and acetylated konjac glucomannan as a composite wall material, employing high-pressure homogenization and spray drying to microencapsulate tea polyphenols. This wall material system exhibits excellent thermal stability and oxygen barrier properties, increasing the retention rate of tea polyphenols to over 85% after baking at 180℃. Simultaneously, the wall material remains intact in the mouth, completely masking the bitterness of the tea polyphenols and presenting only a pure wheat and soybean protein aroma, thus solving the dilemma of not being able to simultaneously achieve functionality and flavor.

[0022] High fiber and high protein content can damage the gluten network, resulting in a rough, dry, and inelastic texture. This invention achieves synergistic optimization of texture through a precise blend of soy protein isolate, wheat fiber, guar gum, and β-glucan: soy protein isolate strengthens the gluten network, improving softness and elasticity; wheat fiber forms a microporous structure while building a sugar-lowering barrier, enhancing fluffiness; and hydrophilic colloids provide a smooth and delicate texture. The product's texture measurement shows a hardness of approximately 1200g and an elasticity of approximately 0.92, with a soft and delicate texture, free from roughness and stickiness, approaching the quality of premium traditional white toast.

[0023] High-fiber, high-activity premixed powders are prone to stratification and clumping during storage and transportation due to significant differences in the hygroscopicity of their components; unprotected active ingredients experience accelerated degradation; and the high water activity of the finished product due to water-retaining components leads to accelerated starch retrogradation during shelf life. This invention reduces the overall moisture absorption rate of the system through microencapsulation, ensures high component uniformity through a dry premixing process, and isolates the product from the external environment using nitrogen-filled aluminum foil or vacuum packaging. The hydrophilic colloid of the microcapsule wall material forms a long-lasting water-retaining network with guar gum and soy protein in the formula, delaying starch retrogradation. The premixed powder remains loose and fluid even after long-term storage and transportation, with minimal activity degradation; the finished toast retains good softness and elasticity even after 7 days of sealed storage at room temperature, and its sugar-reducing function remains stable.

[0024] High-functionality ingredients significantly alter the rheological properties of dough, leading to abnormal water absorption, weakened gluten, and a narrow fermentation window, making it difficult to match the fixed-rhythm industrial production. This invention solves the problem of weighing multiple components on-site by providing an integrated premixed powder product; the soy protein isolate and colloids in the formula synergistically optimize the dough's extensibility and surface tack, preventing it from sticking to the rollers and breaking on continuous dough forming machines; precise proportions provide the dough with a wide and controllable fermentation window, stably matching the fixed-rhythm of tunnel proofing chambers. The solution is fully compatible with existing industrial production lines, requiring no additional equipment modifications.

[0025] Existing solutions often focus on a single function and have a limited nutritional composition. This invention, however, is rich in high-quality plant protein, soluble fiber, insoluble fiber, and active tea polyphenols, providing more comprehensive nutrition. All raw materials are common food-grade commodities, and microencapsulation significantly improves the utilization rate of tea polyphenols. Attached Figure Description

[0026] Figure 1 This is a blood glucose response curve of one of the subjects in this invention. Detailed Implementation

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to limit the invention; the term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0028] Example 1: Preparation of microencapsulated tea polyphenols. This example represents the optimal wall material ratio. 1. The specific preparation steps are as follows: (1) Wall material solution: Weigh 50g of RS4, 25g of sodium caseinate and 25g of acetylated konjac glucomannan, dissolve them in 300g of pure water at 65℃, stir thoroughly until completely dissolved, and cool to 25℃ to obtain the wall material solution.

[0029] (2) Core material solution: Weigh 30g of tea polyphenols (catechin content ≥98%), dissolve in 170g of purified water, add 0.5g of citric acid to adjust the pH to 4.5, and obtain the core material solution.

[0030] (3) Microencapsulation process: Under high-speed shearing at 10,000 rpm, the core material solution is slowly added to the wall material solution, and shearing is continued for 8 minutes to obtain the primary emulsion. Then, it is homogenized twice under high pressure at 30 MPa to form a uniform O / W emulsion. Finally, it is spray dried, with the inlet air temperature controlled at 175℃, the outlet air temperature at 85℃, and the atomizer speed at 25,000 rpm. After drying, the microcapsule powder is collected and passed through a 100-mesh sieve to obtain the final product.

[0031] 2. Effects: (1) Micromorphology: The prepared microcapsules are spherical with uniform particle size distribution.

[0032] (2) Encapsulation rate: The encapsulation rate of tea polyphenols was 92.3% as determined by high performance liquid chromatography (HPLC).

[0033] (3) Thermal stability: When the microcapsule powder was placed in an oven at 180℃ and heated for 10 min, the tea polyphenol retention rate was 86.7%.

[0034] (4) Yield: The yield of this batch was 91.5%.

[0035] Example 2: Preparation of low-GI premixed powder and baked goods toast. This example is a preferred formula. 1. The specific preparation steps are as follows: (1) Premixed powder formula (weight percentage): 70% wheat flour, 9% soy protein isolate, 5% white sugar, 1.2% guar gum, 6% wheat fiber, 4% oat β-glucan, 1% edible salt, and 3.8% microencapsulated tea polyphenols prepared in Example 1 (the net content of tea polyphenols at this amount is 1.0%).

[0036] (2) Premixed powder preparation process: First, guar gum and edible salt are premixed with 7.2g of wheat flour to obtain premix A; then, wheat fiber and oat β-glucan are premixed with 14g of wheat flour to obtain premix B. Then, all the remaining powders are put into a mixer, and premix B, premix A and microencapsulated tea polyphenols are added in sequence, and the mixture is mixed for a total of 30min. Finally, the mixture is passed through an 80-mesh sieve and packaged with nitrogen.

[0037] (3) Toast ingredients: Take 300g of the above premixed powder, 24g of butter, 4.5g of high-activity dry yeast, and 138g of drinking water.

[0038] (4) Toast preparation process: Mix the premixed flour and dry yeast evenly, add water and stir for 3 minutes to form a dough, then add softened butter and stir at high speed until the gluten is fully developed, with a final dough temperature of 26.5℃. Then, perform a first fermentation at 38℃ and 80% relative humidity for 55 minutes. After fermentation, divide and round the dough, let it rest at room temperature for 18 minutes, and then shape and mold it. Then, perform a second fermentation at 37℃ and 85% relative humidity for 65 minutes until the mold is 8-9 / 10 full. Finally, bake in the oven at 185℃ for the top heat and 175℃ for the bottom heat for 32 minutes. After baking, tap the mold to release the bread, and let it cool to obtain low-GI toast.

[0039] 2. Effects: (1) GI value: The human blood glucose test was conducted in accordance with the "WS / T 652-2019 Method for Determination of Glycemic Index of Foods". The GI value of the toast in this example was 42.

[0040] (2) Tea polyphenol retention rate: HPLC analysis showed that the tea polyphenol retention rate in the baked toast was 87.4%.

[0041] (3) Sensory evaluation: The taste score (softness, elasticity) was 8.7 / 10 and the flavor score (acceptability) was 8.9 / 10.

[0042] (4) Texture analysis: The texture analyzer (TPA) was used to measure the hardness of the toast at 1200g and the elasticity at 0.92, which is comparable to the indicators of high-quality commercially available white toast.

[0043] (5) Shelf life test: After the toast was sealed and stored at room temperature for 5 days, there was no significant change in texture and hardness, and it was acceptable.

[0044] Example 3: Verification of proportion adjustment; 1. The specific preparation steps are as follows: (1) Premixed powder formula (weight percentage): 75% wheat flour, 8% soy protein isolate, 4% white sugar, 1.5% guar gum, 5.5% wheat fiber, 3.5% oat β-glucan, 1.2% edible salt, and 1.3% microencapsulated tea polyphenols prepared in Example 1 (the net content of tea polyphenols at this amount is 0.4%).

[0045] (2) Preparation process: The preparation process of the premixed powder and toast is completely the same as that in Example 2.

[0046] 2. Effects: (1) GI value: The measured GI value of the toast is 45, which still meets the low GI food standard (GI≤55).

[0047] (2) Tea polyphenol retention rate: The retention rate after roasting was 87.2%.

[0048] (3) Sensory evaluation: The product has a slightly firmer texture than that of Example 2, but is still soft, with a moderate sweetness. This proves that the formula of the present invention can be flexibly adjusted within a limited range of proportions while maintaining its effectiveness.

[0049] Comparative Example 1 (unencapsulated tea polyphenols); 1. The specific preparation steps are as follows: Unencapsulated tea polyphenols with an equal net content (1.0%) were directly added to replace the microencapsulated tea polyphenols in Example 2, while all other raw materials, formulation ratios, and preparation processes remained unchanged.

[0050] 2. Effects: (1) Tea polyphenol retention rate: only 36.5% after roasting.

[0051] (2) Sensory evaluation: The product has a distinct tea astringency, slight browning in color, taste score 7.0 / 10, flavor score 7.5 / 10.

[0052] (3) GI value: When the product's GI value increases to 50, the blood sugar lowering effect decreases significantly.

[0053] This comparative example fully demonstrates the necessity of microencapsulation technology for protecting the activity of tea polyphenols, masking off-flavors, and ultimately achieving efficient and stable blood sugar reduction.

[0054] Comparative Example 2 (ordinary high-gluten flour without encapsulated tea polyphenols); 1. The specific preparation steps are as follows: (1) Toast ingredients: 300g of ordinary high-gluten flour was used to replace the premixed powder of this invention, and other ingredients were replaced in equal amounts, namely 300g of high-gluten flour, 24g of butter, 4.5g of dry yeast, and 138g of drinking water. No tea polyphenols or other functional ingredients were added.

[0055] (2) Preparation process: The stirring, fermentation and baking processes are completely the same as those in Example 2.

[0056] 2. Effects: Sensory evaluation: The resulting toast received a texture score of 7.8 / 10 and a flavor score of 8.1 / 10.

[0057] GI value: The product's GI value is 71, which does not meet the standards for low-GI foods.

[0058] This comparative example demonstrates that using the low-GI premixed powder of the present invention to replace traditional high-gluten flour is significantly effective in reducing the GI value of the product.

[0059] The blood glucose response curve of one of the subjects in this invention is shown in the figure below. Figure 1 As shown, the GI values ​​and tea polyphenol retention rates (%) of each embodiment and comparative example are shown in Tables 1 and 2 below: Table 1 GI Values Table 2. Retention rate of tea polyphenols (%) This invention uses a compound low-GI premixed flour instead of traditional high-gluten flour, which can effectively reduce the GI value of toast products; the compound premixed flour in the preferred ratio has a lower GI value than the non-preferred ratio.

[0060] Products made with premixed powder containing microencapsulated tea polyphenols have a significantly lower GI value than premixed powder products containing unencapsulated tea polyphenols.

[0061] Based on the polyphenol retention results of the examples and comparative examples, microencapsulation technology is key to ensuring the high activity of tea polyphenols during the roasting process, with a retention rate significantly higher than that of the group where unencapsulated tea polyphenols were directly added. Differences in the proportions of the premixed powder formulation had no significant impact on the thermal stability of the microencapsulated tea polyphenols.

[0062] Example 4: Long-term storage, transportation and continuous industrial production of low-GI premixed powder under high temperature and high humidity conditions; This embodiment simulates the entire industrial application scenario of low-GI premixed powder from raw material storage and transportation to continuous production in a central factory under extreme high temperature and humidity conditions in South China during summer, in order to verify the comprehensive performance of the present invention.

[0063] 1. The specific preparation steps are as follows: (1) Premixed powder formula (weight percentage): wheat flour 70%, soy protein isolate 9%, white sugar 5%, guar gum 1.2%, wheat fiber 6%, oat β-glucan 4%, edible salt 1%, microencapsulated tea polyphenols prepared in Example 1 3.8% (net content of tea polyphenols 1.0%). The formula and preparation process are the same as in Example 2.

[0064] (2) Simulation conditions for industrialized storage and transportation: The premixed powder is vacuum-packed in aluminum foil composite bags, each weighing 25 kg net. After packaging, it is placed in a constant temperature and humidity test chamber, set at 30℃ and 80% relative humidity, simulating the summer environment of a premixed powder production workshop in a central factory in South China (represented by Dongguan, Guangdong). Under these conditions, it is left to stand for 14 days to simulate the waiting period for production orders within the factory. Afterward, the premixed powder is transferred to a simulated vibration table in a regular van and vibrated continuously for 48 hours at the same temperature (30℃) to simulate 800 km long-distance ambient temperature transportation. After the transportation simulation, the premixed powder is stored in a constant temperature and humidity chamber at 33℃ and 90% relative humidity for 4 weeks to simulate ambient temperature raw material storage after arriving at the destination (represented by Nanning, Guangxi) central kitchen. The total storage and transportation cycle is 5 weeks.

[0065] (3) Conditions for industrialized production of toast: Using the premixed powder that has undergone the above storage and transportation process, mass production verification was carried out on a continuous industrial toast production line.

[0066] Ingredients: 100kg premixed powder, 8kg butter, 1.5kg high-activity dry yeast, 46kg drinking water.

[0067] Mixing: Using a vacuum dough mixer, first dry mix the premixed powder and dry yeast at low speed for 1 minute, then add water and mix at low speed for 3 minutes until the dough is formed. Then add the softened butter and mix at high speed for 6 minutes until the gluten is fully developed. The final temperature of the dough should be controlled at 26-27℃.

[0068] Continuous dough pressing and shaping: The dough undergoes degassing, sheeting, and rolling processes using a continuous dough pressing and shaping machine. The production line speed is matched to the main line's capacity target of 500 kg of premixed flour / hour. Observe the adhesion of the dough to the rollers and the continuity of the dough strip.

[0069] Fermentation: A tunnel-type proofing chamber is used. The primary proofing zone is set at 38℃ and 80% relative humidity, with a residence time of 55 minutes. The secondary proofing zone is located after shaping and molding, with a set temperature of 37℃ and 85% relative humidity, and a residence time of 65 minutes. The total fermentation time is controlled within 120±5 minutes (including transfer time), matching the fixed industrial cycle.

[0070] Baking: Use a rotary hot air oven at 185°C (top heat) and 175°C (bottom heat) for 32 minutes. After baking, allow to cool naturally to room temperature before slicing and individually sealing and packaging.

[0071] (4) Finished product shelf life test: Sealed packaged toast products were placed in a 25°C constant temperature incubator to simulate room temperature shelf life. Samples were taken on days 1, 4, and 7 to test their textural properties, sensory quality, and GI value.

[0072] 2. Effects: (1) Storage and transportation stability of premixed powder: After a total of 5 weeks of simulated storage and transportation under high temperature, high humidity, and vibration, the premixed powder remained in a loose powder state upon unpacking, with no visible clumping or stratification. The tapped density changed by less than 3% compared to the initial state, allowing it to pass smoothly through the pneumatic conveying system. High-performance liquid chromatography (HPLC) analysis showed that the retention rate of microencapsulated tea polyphenols in the premixed powder was 85.8% (less than 1 percentage point decrease compared to the 86.7% retention rate of freshly prepared microcapsule powder in Example 1), indicating that the microcapsule wall material provided extremely effective protection for the core material under long-term high temperature and high humidity conditions, ensuring the functional efficacy of the final product.

[0073] (2) Adaptability to industrial processing: During operation of the continuous dough forming machine, the dough exhibited good extensibility and moderate surface stickiness, with no sticking to the rollers or breakage of the dough strip throughout the process. The dough strip surface was smooth and of uniform thickness. In the tunnel-type proofing chamber, the dough proofed stably with consistent fermentation height, completing proofing entirely within the 120-minute cycle time set by the production line. This demonstrated excellent fermentation tolerance and a wide processing time window, verifying the perfect adaptability of this formula to high-speed continuous production lines.

[0074] (3) Overall quality of finished toast: The finished toast had a GI value of 43, which was basically the same as the freshly prepared toast in Example 2 (GI=42), proving that the product's sugar-lowering effect was not affected after the entire rigorous storage, transportation and industrial production process.

[0075] After roasting, the tea polyphenol retention rate was 86.9%, which was the same as that in Example 2 (87.4%).

[0076] Sensory evaluation: The finished toast has a uniform golden color and a fine internal texture. The results of a blind taste test by 10 people showed that the texture score (softness, elasticity) was 8.6 / 10, the flavor score (acceptability) was 8.8 / 10, and there was no bitterness or other off-flavors. The results were not significantly different from those of Example 2.

[0077] (4) The quality maintenance during the shelf life is shown in Table 3 below: Table 3. Quality changes of toast during room temperature shelf life in Example 4. As shown in the table above, the GI value of the toast remained stable at 43-44 within a 7-day shelf life at room temperature, without any significant increase. Although the texture hardness increased slightly, it remained within the acceptable range for consumers, and the elasticity remained good. All sensory scores remained above 8.4 points, with no significant flavor degradation. This fully demonstrates that the long-lasting water-retention and active controlled-release system constructed by microencapsulated tea polyphenols and hydrophilic colloids in this invention solves the core industry problem of high-fiber, low-GI baked goods easily aging, drying out, and functionally degrading during shelf life.

[0078] This application example illustrates that the low-GI baked goods based on microencapsulated tea polyphenols and the preparation method thereof provided by this invention, under the simulated extreme high temperature and humidity long-distance storage and transportation environment in South China during summer, as well as the actual scenario of continuous large-scale production in a central factory, demonstrate excellent industrial application potential in terms of raw material stability, processing technology adaptability, finished product blood sugar reduction effect, sensory quality, and quality maintenance at room temperature for up to 7 days. This is something that no existing single blood sugar reduction technology or simple ingredient compounding scheme can achieve.

[0079] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A low-GI baked product based on microencapsulated tea polyphenols, characterized in that, Made from the following ingredients by weight: 100 parts low-GI baking premix, 5-10 parts butter, 1-2 parts high-activity dry yeast, and 40-50 parts drinking water; The low-GI baking premix consists of the following components by weight percentage: Wheat flour 60%-80%; Soy protein isolate 5%-15%; White sugar 3%-8%; Guar gum 0.5%-2.5%; Wheat fiber 3%-10%; Oat beta-glucan 2%-6%; Edible salt content: 0.5%-1.5%; Microencapsulated tea polyphenols: 1.0%-4.0%; The sum of the weight percentages of the above components is 100%.

2. The low-GI baked goods based on microencapsulated tea polyphenols according to claim 1, characterized in that, The wall material of the microencapsulated tea polyphenols is composed of RS4, sodium caseinate and acetylated konjac glucomannan in a mass ratio of 4-6:2-3:2-3.

3. The low-GI baked goods based on microencapsulated tea polyphenols according to claim 2, characterized in that, The mass ratio of the wall material is 5:2.5:2.

5.

4. The low-GI baked goods based on microencapsulated tea polyphenols according to claim 1, characterized in that, The preparation method of the microencapsulated tea polyphenols includes the following steps: (1) Preparation of wall material solution: Weigh RS4, sodium caseinate and acetylated konjac glucomannan according to the proportion, dissolve them in pure water at 60-70℃, stir until completely dissolved, prepare a wall material solution with a mass fraction of 25%-35%, and cool to room temperature; (2) Preparation of core material solution: Dissolve tea polyphenols in pure water to prepare a core material solution with a mass fraction of 15%-25%, and add citric acid to adjust the pH to 4.0-5.0; (3) Emulsification and homogenization: Under high-speed shearing conditions of 10,000-12,000 rpm, the core material solution is slowly added to the wall material solution and sheared for 5-10 min to obtain the initial emulsion; then, it is homogenized under high pressure of 25-40 MPa 2-3 times to form a uniform O / W emulsion. (4) Spray drying: The obtained emulsion is spray dried with an inlet air temperature of 160-180℃, an outlet air temperature of 80-90℃, and an atomizer speed of 20000-30000 rpm. After drying, the emulsion is collected.

5. The low-GI baked goods based on microencapsulated tea polyphenols according to claim 1, characterized in that, The low-GI baking premix is ​​prepared by a dry mixing process, including the following steps: (1) Pretreatment: Wheat flour and soy protein isolate are passed through a 60-mesh sieve; (2) Premixing: Guar gum, edible salt and wheat flour in a ratio of 10 times their total weight are premixed to obtain premix A; oat β-glucan, wheat fiber and some wheat flour are premixed to obtain premix B; (3) Overall mixing: Put the remaining basic powder into the mixer, add premix B and premix A in sequence, and finally add microencapsulated tea polyphenols, and mix for 25-35 min; (4) Sieving and packaging: Pass through an 80-mesh sieve and use aluminum foil composite bags for nitrogen filling or vacuum packaging to obtain premixed powder.

6. The low-GI baked goods based on microencapsulated tea polyphenols according to claim 1, characterized in that, The low-GI baked product is toast.

7. A method for preparing a low-GI roasted product based on microencapsulated tea polyphenols as described in any one of claims 1-6, characterized in that, Includes the following steps: (1) Ingredients: By weight, 100 parts of the prepared premixed powder, 5-10 parts of butter, 1-2 parts of high-activity dry yeast, and 40-50 parts of drinking water; (2) Mixing: Mix the premixed powder and dry yeast evenly, add water and mix into a dough, then add softened butter and mix until the gluten is fully developed; (3) Fermentation: The conditions for the first fermentation are a temperature of 30-40℃, a relative humidity of 75%-85%, and a time of 40-60 min, until the dough volume expands to 2 times; the conditions for the second fermentation are a temperature of 35-38℃, a relative humidity of 80%-90%, and a time of 50-70 min, until the dough ferments to 8-9 / 10 of the mold's capacity. (4) Baking: Bake at 180-190℃ for the top heat and 170-180℃ for the bottom heat for 25-35 minutes. After cooling, you will get low-GI baked goods.

8. The method for preparing low-GI roasted products based on microencapsulated tea polyphenols according to claim 7, characterized in that, Step (2) Mixing adopts a two-step method: first, dry mix the premixed powder with the dry yeast, add water and mix at low speed for 3 minutes to form a dough, then add the softened butter and mix at high speed for 5-7 minutes until the gluten is fully developed. The final temperature of the dough is controlled at 26-27℃.

9. The application of a low-GI baked product based on microencapsulated tea polyphenols as described in any one of claims 1-6, characterized in that, Application in the preparation of food with GI≤55.

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