A composition of white kidney bean full component utilization and its preparation method and application

Abstract

The application discloses a composition for full-component utilization of white kidney beans and a preparation method and application thereof, and the composition is prepared by separating and extracting white kidney beans to obtain alpha-amylase inhibitors (alpha-AI), and the alpha-AI is double-embedded by using self-source wall materials, so that the inhibitory activity is improved to more than 10000 U / g, all components in the composition are derived from the white kidney beans, the utilization rate of raw materials is improved to 95%, full extraction and efficient utilization of the white kidney beans are realized. In addition, the combination of the self-source wall materials and the double-embedded structure improves the stability of the composition, so that the composition still has an activity of more than 85% at 90 DEG C, and can adapt to various processing environments. The composition further adds dietary fibers, is suitable for adjusting postprandial blood glucose level, can be mixed with rice flour or other auxiliary materials to prepare food with a low glycemic index (GI), and is suitable for low GI food development, weight management, intestinal improvement and the like.

Description

Technical Field

[0001] This invention relates to the field of nutrition and health technology, and in particular to a composition utilizing all components of white kidney beans, its preparation method, and its application. Background Technology

[0002] White kidney beans, scientifically known as Common Beans, are rich in nutrients. Scholars both domestically and internationally have isolated nearly a hundred compounds from white kidney beans, among which α-amylase inhibitors (α-AI) have attracted the most attention. α-AI specifically inhibits the activity of α-amylase in human saliva and the intestines, hindering or delaying the hydrolysis and digestion of starch in food. This reduces calorie intake, regulates postprandial blood sugar, and increases the variety and quantity of beneficial bacteria in the gut, while exhibiting good safety. It is widely used in regulating postprandial blood sugar levels, improving gut health, and developing low-GI foods. White kidney beans are also rich in protein, dietary fiber, starch, and minerals, making them a highly nutritious resource with high protein, low fat, high potassium, and low sodium content. Containing various beneficial bioactive substances, they represent a promising resource for processing and utilization.

[0003] However, due to the generally low α-AI content in white kidney beans, extraction using traditional methods yields only 3%–5%, and it is difficult to fully utilize byproducts (starch, dietary fiber, etc.), resulting in significant raw material waste, high production costs, and expensive market prices. Furthermore, the main component of α-AI is glycoprotein; high temperatures during processing and application can damage its structure, leading to a loss of amylase inhibitory activity and reduced efficacy. Proteases in human gastric juice also affect the amylase inhibitory activity of α-AI. Therefore, the activity levels of α-AI products on the market vary considerably, and its unstable performance severely hinders its market promotion and application. α-AI also suffers from other problems in actual production and subsequent processing, such as unpleasant odor and poor water solubility, causing inconvenience and unpleasant taste for consumers.

[0004] Based on the above problems, a composition that fully utilizes the components of white kidney beans, its preparation method, and its application can be developed to reduce raw material waste, improve the utilization rate of white kidney beans, and enhance the inhibitory activity and stability of α-AI on amylase. Summary of the Invention

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: A composition utilizing all components of white kidney beans includes microencapsulated α-AI and insoluble dietary fiber derived from white kidney beans, wherein the microencapsulated α-AI accounts for 20%-70% and the insoluble dietary fiber accounts for 30%-80%. The microencapsulated α-AI is encapsulated once with hydroxypropyl porous starch from white kidney beans and then encapsulated a second time with water-soluble dietary fiber from white kidney beans. The microencapsulated α-AI has a double-layer encapsulation structure: the inner layer is hydroxypropyl porous starch derived from white kidney beans; the outer layer is water-soluble dietary fiber derived from white kidney beans. The insoluble dietary fiber, white kidney bean α-AI, and the embedding wall material are all derived from white kidney beans.

[0006] Furthermore, the α-amylase inhibitory activity of the microencapsulated α-AI is 10,000-20,000 U / g; the activity retention rate of the microencapsulated α-AI is ≥90% after treatment at 90℃ for 30 min.

[0007] Furthermore, the encapsulation rate of the microencapsulated α-AI is 60%-85%.

[0008] Furthermore, the degree of hydroxypropyl substitution of the hydroxypropyl porous starch is 0.05-0.2.

[0009] A method for preparing a composition as described in any of the preceding claims, comprising the following steps: White kidney beans were directionally separated and extracted to obtain white kidney bean α-AI, water-soluble dietary fiber, white kidney bean starch and insoluble dietary fiber; Enzymatic hydrolysis and etherification of white kidney bean starch yielded hydroxypropyl porous starch with an open porosity of 40%-60%. The encapsulation process is carried out in an ethanol system: the temperature is first raised to 55-65℃ to expand the pores of the white kidney bean hydroxypropyl porous starch; white kidney bean α-AI is added and stirred, and then the temperature is lowered to 30-40℃ to shrink the pores and form an encapsulation structure. The ethanol is removed under negative pressure to obtain the encapsulation product. Water-soluble dietary fiber was added under 50-65W ultrasound conditions for secondary encapsulation to obtain microencapsulated α-AI; The microencapsulated α-AI was mixed evenly with insoluble dietary fiber to obtain a composition that utilizes all components of white kidney bean.

[0010] Further, the targeted separation and extraction includes: S1: Grind white kidney beans through a 425µm sieve, prepare a solution with water at a material-to-liquid ratio of 1:7-10, extract at 50-60℃ for 1-2 hours, and then perform a separation at a speed of 4000-7000 r / min to obtain solid and liquid phases respectively. S2: The liquid phase is subjected to secondary separation and membrane separation. The secondary separation speed is 12000-16000 r / min. For membrane separation, the supernatant is first passed through 0.2µm microfiltration, and then through a 60kDa ultrafiltration membrane and a 10kDa ultrafiltration membrane. The effluent (molecular weight less than 10kDa, used as secondary embedding wall material, whose main component is water-soluble dietary fiber) and the retentate (molecular weight 10kDa-60kDa) are collected respectively. The retentate is concentrated under negative pressure until the solid content is 15-25% to obtain white kidney bean α-AI. S3: Centrifuge the solid phase described in S1 to obtain insoluble dietary fiber and white kidney bean starch.

[0011] It should be noted that the secondary encapsulation wall material and white kidney bean starch are dried separately for subsequent processing. For the dehydration of white kidney bean starch, a scraper centrifuge can be used to dehydrate the white kidney bean starch slurry and air-dry it. The secondary encapsulation wall material is spray-dried with an inlet air temperature of 180-220℃ and an outlet air temperature of 70-110℃. After spray drying, the water-soluble dietary fiber content in the secondary encapsulation wall material can reach over 85%, and the water content is less than 5%. In addition, insoluble dietary fiber can also be dried and mixed with microencapsulated α-AI. By adding multiple dietary fibers, the nutritional diversity of the composition is increased, making it suitable for applications such as regulating postprandial blood glucose levels and developing low-GI foods, thus diversifying its application scenarios.

[0012] It should be noted that the extraction rate of the main product, white kidney bean α-AI, is about 8%-10%, the extraction rate of water-soluble dietary fiber is about 10-12%, the extraction rate of insoluble dietary fiber is about 10%-12%, and the extraction rate of white kidney bean starch is about 40%-45%.

[0013] Furthermore, the white kidney bean starch undergoes enzymatic hydrolysis and etherification treatment, specifically as follows: Starch was prepared into a starch slurry with a mass concentration of 20%-40%. 0.05%-0.08% (relative to the dry weight of starch) of CaCl2 was added, and the pH was adjusted to 5-6. Then, 0.2%-2% (relative to the dry weight of starch) of pullulanase (enzyme activity of 2000 U / g) was added, and enzymatic hydrolysis was carried out for 1-3 hours. After enzymatic hydrolysis, starch with a porous surface was obtained. When the porosity of the starch was 40%-60%, 5%-10% (relative to the dry weight of starch) of Na2SO4 and 0.8-1.2% (relative to the dry weight of starch) of NaOH were added. After stirring evenly, 5-8% (relative to the dry weight of starch) of propylene oxide was added under nitrogen protection, and the etherification reaction was carried out at 30-35℃ for 8-12 hours. After the reaction was completed, the pH was adjusted to 5.5-7 with 5% dilute hydrochloric acid. After washing with a hydrocyclone, dehydration and drying, and sieving, hydroxypropyl porous starch of white kidney bean was obtained.

[0014] It should be noted that the addition of pullulanase to enzymatically hydrolyze white kidney bean starch creates numerous irregularly arranged pores on the surface of the starch granules, forming a porous structure. Simultaneously, pullulanase debranching further transforms it into high-amylose white kidney bean starch, where molecules readily form an ordered arrangement, resulting in resistant starch. Higher resistant starch content contributes to stabilizing blood sugar and lowering cholesterol and blood lipids. Under weakly alkaline conditions, propylene oxide undergoes a hydroxypropyl etherification reaction with white kidney bean starch, improving its film-forming properties, hydrophilicity, anti-aging properties, and freeze-thaw stability. These properties are beneficial for subsequent encapsulation as a primary wall material with white kidney bean α-AI, and also enhance the processing adaptability of the encapsulated microencapsulated α-AI, resulting in improved performance in areas such as water solubility, good tableting, good flowability, low moisture absorption, low-temperature stability, and acid resistance.

[0015] Furthermore, the ethanol concentration is 30%-50%.

[0016] Furthermore, the negative pressure is -0.05MPa to -0.09MPa.

[0017] Specifically, the encapsulation is performed once in the ethanol system: Add a 30%-50% ethanol solution to the white kidney bean hydroxypropyl porous starch, and heat it to 55℃-65℃ at a rate of 5℃ / min to expand the pores of the white kidney bean hydroxypropyl porous starch, and maintain the temperature for 10-20 min; then add white kidney bean α-AI, and stir and mix at a speed of 120-400 r / min for 5-20 min, and then cool it to 30℃-40℃ at a rate of 5℃ / min to shrink the pores and form an embedded structure, and maintain the temperature for 20-30 min; Ethanol was removed under vacuum pressure of -0.05MPa to -0.09MPa until the ethanol content was less than 3%, thus obtaining a primary encapsulation product.

[0018] Specifically, the secondary encapsulation process involves adding water-soluble dietary fiber to the primary encapsulation product, incubating it under ultrasonic power of 50-65W for 10-25 minutes, and then performing secondary encapsulation to obtain microencapsulated α-AI.

[0019] It should be noted that this invention uses an ethanol solution as a solvent to pretreat hydroxypropyl porous starch from white kidney beans. First, the temperature is raised to expand the pores of the hydroxypropyl porous starch, allowing it to accommodate a larger amount of white kidney bean α-AI, thereby increasing its inhibitory activity against α-amylase to over 10000 U / g. After adding white kidney bean α-AI, the mixture is stirred at low speed to ensure that the α-AI is fully integrated into the pores of the white kidney bean hydroxypropyl porous starch without damaging the pore structure. After thorough encapsulation, the temperature is lowered to shrink the pores, thus firmly embedding the white kidney bean α-AI within the pores. Once stable, due to the volatile nature of ethanol, negative pressure is applied to remove the ethanol from the system. Ethanol is chosen as the solvent because white kidney bean hydroxypropyl porous starch is more prone to gelatinization in aqueous solutions under high temperatures, while ethanol does not easily gelatinize it and has safe antibacterial properties. This not only reduces the microbial content of the product but also facilitates its removal, further ensuring product safety.

[0020] Furthermore, the white kidney bean starch accounts for 30%-60%, the white kidney bean α-AI accounts for 30%-65%, and the water-soluble dietary fiber accounts for 10%-20%.

[0021] It should be noted that when the porosity of white kidney bean hydroxypropyl porous starch is 40%-60%, to ensure the effectiveness and encapsulation rate of the first-stage encapsulation, a 50% ratio of white kidney bean hydroxypropyl porous starch and a 40% ratio of white kidney bean α-AI are preferred for the first-stage encapsulation. If too much white kidney bean hydroxypropyl porous starch is used, the purity of white kidney bean α-AI will decrease, resulting in low amylase inhibitory activity in the microencapsulated product. If too little white kidney bean hydroxypropyl porous starch is used, white kidney bean α-AI cannot be completely encapsulated, leading to poor product stability and decreased acid and heat resistance. Furthermore, water-soluble dietary fiber, a polysaccharide, can be used as a wall material for secondary encapsulation of the first-stage product. Because polysaccharides can only be digested and absorbed in the intestines and will not disintegrate in the stomach, this improves the targeted release of microencapsulated α-AI. A 10% ratio of water-soluble dietary fiber is preferred to achieve a better encapsulation effect, thereby improving the heat resistance and processing stability of the microencapsulated α-AI.

[0022] Application of compositions utilizing all components of white kidney beans as described in any of the preceding items in the preparation of low-GI foods.

[0023] Specifically, a low-GI rice noodle prepared from a composition utilizing all components of white kidney beans as described in any of the preceding claims, comprising, by weight percentage, 0.5-3% microencapsulated α-AI, 3-5% insoluble dietary fiber, and 90-95% rice flour; The microencapsulated α-AI is mixed evenly with insoluble dietary fiber in a certain proportion, and then mixed with rice flour. After humidification, steaming, shaping and aging, low-GI white kidney bean rice noodles are prepared.

[0024] As can be seen from the above technical solutions, the present invention has the following beneficial effects: 1. This invention utilizes white kidney bean-derived materials in a closed-loop manner. Water-soluble dietary fiber and white kidney bean starch are directionally separated and extracted from white kidney beans as wall materials to encapsulate white kidney bean α-AI, with an encapsulation rate of over 60%. The composition of this invention also contains insoluble dietary fiber derived from white kidney beans, achieving a utilization rate of over 95% for white kidney beans. This fully utilizes white kidney beans, effectively solves the problem of raw material waste, and greatly reduces production costs.

[0025] 2. The key to this invention lies in controlling the porosity of hydroxypropyl porous starch and combining it with an encapsulation mechanism of heating to expand pores and cooling to shrink them, allowing white kidney bean α-AI to enter the pores and form a stable encapsulation structure. Then, water-soluble dietary fiber forms an outer protective layer, significantly improving its heat resistance and processing stability. Furthermore, hydroxypropyl-modified white kidney bean starch has better hydrophilicity, improving the product's water solubility. Moreover, the modified white kidney bean hydroxypropyl porous starch has a high amylose content, making it easier for it to combine with white kidney bean α-AI. Utilizing intermolecular attraction, α-AI is firmly adsorbed within the pores of the white kidney bean hydroxypropyl porous starch, further enhancing the encapsulation effect.

[0026] 3. By limiting the encapsulation ratio of white kidney bean α-AI, white kidney bean hydroxypropyl porous starch and water-soluble dietary fiber, this invention not only reduces the emulsification encapsulation time, making the preparation process more efficient and simple, but also maintains more than 85% activity at 90℃ through a double-layer encapsulation structure, which can adapt to high-temperature processing environments. This ensures that it can effectively inhibit the digestion and absorption of starch in multiple scenarios, thus ensuring the effect of controlling sugar and lipids. Attached Figure Description

[0027] Figure 1 A schematic diagram of the process for directional separation and extraction from white kidney beans; Figure 2 Electron micrograph of α-AI from white kidney bean without embedding treatment; Figure 3a Electron microscopy image of the microcapsule α-AI after embedding in Comparative Example 7; Figure 3b Here is an electron microscope image of the microencapsulated α-AI from Example 4; Figure 4 Comparative diagram of the dissolution of unencapsulated white kidney bean α-AI, microencapsulated α-AI of Comparative Example 7, and microencapsulated α-AI of Example 4 in water. Detailed Implementation

[0028] The present invention will be further described below with reference to embodiments.

[0029] This invention provides a composition utilizing all components of white kidney beans, comprising microencapsulated α-AI and insoluble dietary fiber; wherein the microencapsulated α-AI is first encapsulated with hydroxypropyl porous starch derived from white kidney beans and then secondarily encapsulated with water-soluble dietary fiber derived from white kidney beans.

[0030] Preferably, the components in the composition, by mass percentage, comprise 20%–70% microencapsulated α-AI and 30%–80% insoluble dietary fiber; The α-amylase inhibitory activity of microencapsulated α-AI is 10,000-20,000 U / g; the encapsulation efficiency of microencapsulated α-AI is 60%-85%.

[0031] This invention also provides an application of a composition utilizing all components of white kidney beans in the preparation of low-GI foods. Specifically, a low-GI rice noodle prepared from a composition utilizing all components of white kidney beans includes, by weight percentage, 0.5-3% microencapsulated α-AI, 3-5% insoluble dietary fiber, and 90-95% rice flour. The microencapsulated α-AI and insoluble dietary fiber are mixed evenly according to the specified ratio, then mixed with rice flour, and after conditioning, steaming, shaping, and aging, low-GI white kidney bean rice noodles are prepared.

[0032] It should be noted that the embodiments of the present invention only provide low-GI rice noodles prepared by this composition. Taking this as an example, it does not limit other applications in food. For example, the composition of the present invention can be mixed with wheat flour to make bread, steamed buns, noodles, etc., and can also be mixed with other auxiliary materials to make other functional foods. Example 1

[0033] This embodiment provides a low-GI rice noodle, which, by weight percentage, comprises 0.5% microencapsulated α-AI, 5% insoluble dietary fiber, and 94.5% rice flour. Example 2

[0034] This embodiment provides a low-GI rice noodle, which, by weight percentage, comprises 1.5% microencapsulated α-AI, 5% insoluble dietary fiber, and 93.5% rice flour. Example 3

[0035] This embodiment provides a low-GI rice noodle, which, by weight percentage, comprises 3% microencapsulated α-AI, 4% insoluble dietary fiber, and 93% rice flour. Example 4

[0036] This embodiment provides a method for preparing a composition utilizing all components of white kidney beans, comprising the following steps: Step one involves the directional separation and extraction of white kidney beans. Specifically, the white kidney beans are first pulverized and passed through a 425µm sieve. A solution is prepared with water at a material-to-liquid ratio of 1:7 and extracted at 50℃ for 2 hours. A first separation is then performed at a speed of 4000 r / min, yielding solid and liquid phases. The liquid phase undergoes a second separation at a speed of 16000 r / min. The supernatant is first microfiltered through a 0.2µm sieve, then sequentially ultrafiltered through a 60kDa ultrafiltration membrane and a 10kDa ultrafiltration membrane. The effluent and retentate are collected separately. The retentate is concentrated under negative pressure until the solid content reaches 25%, yielding white kidney bean α-AI. Finally, the solid phase is centrifuged using a disc centrifuge to obtain insoluble dietary fiber and white kidney bean starch.

[0037] Step two involves enzymatic hydrolysis and etherification of white kidney bean starch. Specifically, 50g of white kidney bean starch is weighed and prepared into a 30% starch slurry. 0.05% (relative to the dry weight of starch) of CaCl2 is added, and the pH is adjusted to 5.5. Then, 2% (relative to the dry weight of starch) of pullulanase (enzyme activity of 2000U / g) is added, and the mixture is hydrolyzed for 1 hour to obtain starch with a porous surface. When the open porosity of the starch reaches 60%, 5% (relative to the dry weight of starch) of Na2SO4 and 0.8% (relative to the dry weight of starch) of NaOH are added. After stirring evenly, 7% (relative to the dry weight of starch) of propylene oxide is added under nitrogen protection, and the etherification reaction is carried out at 40℃ for 12 hours. After the reaction is completed, the pH is adjusted to 6.5 with 5% dilute hydrochloric acid. After washing and dehydration by a hydrocyclone, modified white kidney bean hydroxypropyl porous starch is obtained.

[0038] The hydroxypropyl porous starch of white kidney beans was pretreated by adding a 30% ethanol solution and heating to 55°C at a rate of 5°C / min, holding for 20 min. Then, 160 ml of white kidney bean α-AI (25% solids content) was added for primary encapsulation. After stirring at a low speed of 300 rpm, the temperature was lowered to 25°C at a rate of 5°C / min, holding for 30 min. The ethanol was then removed under a vacuum of -0.05 MPa until the ethanol content was below 3%, yielding the primary encapsulation product. Next, 10 g of water-soluble dietary fiber was added, and the mixture was incubated under 55 W ultrasonic power for 25 min for secondary encapsulation to obtain microencapsulated α-AI.

[0039] Step 3: Mix the microencapsulated α-AI with insoluble dietary fiber evenly and dry to obtain a composition that utilizes all components of white kidney bean.

[0040] The effluent collected in step one was spray-dried at an inlet air temperature of 220℃ and an outlet air temperature of 110℃. After spray drying, its composition was determined, and the results are as follows:

[0041] As shown in the table, after spray drying, the collected effluent contains over 85% water-soluble dietary fiber and less than 5% water, as well as high levels of potassium and calcium. The main component of the effluent is water-soluble dietary fiber, which can be used as a wall material for encapsulating primary encapsulated products. Because the surface of the primary encapsulated product is uneven, secondary encapsulation not only improves the flowability of microencapsulated α-AI but also further enhances its stability, making it more suitable for subsequent processing. Furthermore, the high potassium and calcium content, extracted from natural plants, can supplement the body's daily mineral needs and increase the nutritional content of the composition.

[0042] By selectively separating and extracting white kidney beans, in addition to the main product white kidney bean α-AI, white kidney bean starch, water-soluble dietary fiber, and insoluble dietary fiber were also separated and recycled. This fills the gap in existing technologies that do not re-extract white kidney bean residue, enabling the extraction of white kidney beans to achieve full recovery and reuse. Example 5

[0043] This embodiment provides a method for preparing a composition utilizing all components of white kidney beans. The specific steps are the same as in Example 4, except that the pullulanase concentration is different during enzymatic hydrolysis in step two, and the amount of propylene oxide used is different during etherification. The details are as follows: Step two involves enzymatic hydrolysis and etherification of white kidney bean starch. Specifically, 50g of white kidney bean starch is weighed and prepared into a 30% starch slurry. 0.05% (relative to the dry weight of starch) of CaCl2 is added, and the pH is adjusted to 5.5. Then, 1.2% (relative to the dry weight of starch) of pullulanase (enzyme activity of 2000U / g) is added, and the solution is hydrolyzed for 3 hours to obtain starch with a porous surface. When the porosity of the starch reaches 45%, 5% (relative to the dry weight of starch) of Na2SO4 and 0.8% (relative to the dry weight of starch) of NaOH are added to adjust the solution to a weakly alkaline state. Under nitrogen protection, 5% (relative to the dry weight of starch) of propylene oxide is added, and the etherification reaction is carried out at 40°C for 12 hours. After the reaction is completed, the modified white kidney bean hydroxypropyl porous starch is obtained by washing and dehydration using a hydrocyclone. Example 6

[0044] This embodiment provides a method for preparing a composition utilizing all components of white kidney beans. The specific steps are the same as in Example 4, except that the parameters for the one-time encapsulation of white kidney bean hydroxypropyl porous starch and white kidney bean α-AI in step two are different, as follows: Step 2: Pre-treat the hydroxypropyl porous starch of white kidney beans by adding a 30% ethanol solution, heating to 65°C at a rate of 5°C / min, holding for 10 min, then adding 160 ml of white kidney bean α-AI (solid content of 25%) for a first encapsulation, stirring at a low speed of 300 r / min, then cooling to 30°C at a rate of 5°C / min, holding for 25 min; removing the ethanol under a vacuum of -0.05 MPa until the ethanol content is below 3%, obtaining the first encapsulation product. Comparative Example 1

[0045] Compared with Example 4, the difference lies in the steps and parameters for the directional separation and extraction of white kidney beans, specifically: Step one involves the directional separation and extraction of white kidney beans. Specifically, the white kidney beans are first pulverized and passed through a 425µm sieve. A solution is prepared with water at a material-to-liquid ratio of 1:7 and extracted at 50℃ for 2 hours. A first separation is then performed at a speed of 4000 r / min, yielding solid and liquid phases. The liquid phase undergoes a second separation at a speed of 16000 r / min. The supernatant is first microfiltered through a 0.2µm sieve, then sequentially ultrafiltered through a 50kDa ultrafiltration membrane and a 20kDa ultrafiltration membrane. The effluent and retentate are collected separately. The retentate is concentrated under negative pressure until the solid content reaches 25%, yielding white kidney bean α-AI. Finally, the solid phase is centrifuged using a disc centrifuge to obtain insoluble dietary fiber and white kidney bean starch.

[0046] The effluent collected in step one was spray-dried at an inlet air temperature of 220℃ and an outlet air temperature of 110℃. After spray drying, its composition was determined, and the results are as follows:

[0047] As shown in the table, after the collected effluent was sprayed dry, the contents of water-soluble dietary fiber, potassium, and calcium all decreased. Due to the different pore sizes of the ultrafiltration membrane, the molecular weight of the white kidney bean α-AI retained was 20kDa-50kDa. The effluent also contained some ash and impurities that could not be separated. When used as a wall material, the low content and purity of water-soluble dietary fiber resulted in poor encapsulation effect, which in turn affected the inhibitory activity of microencapsulated α-AI on amylase. Comparative Example 2

[0048] Compared with Example 4, there are differences in the enzymatic hydrolysis and etherification treatment of white kidney bean starch in step two, specifically: Add 5% (relative to the dry weight of starch) of Na2SO4 and 0.8% (relative to the dry weight of starch) of NaOH. After stirring evenly, add 3% (relative to the dry weight of starch) of propylene oxide under nitrogen protection. Etherify the mixture at 40°C for 12 hours. After the reaction is complete, wash and dehydrate the mixture using a hydrocyclone to obtain modified white kidney bean hydroxypropyl porous starch. Comparative Example 3

[0049] Compared to Example 4, when white kidney bean hydroxypropyl porous starch is encapsulated with white kidney bean α-AI in a single step, there is no subsequent cooling treatment step, as detailed below: Hydroxypropyl porous starch from white kidney beans was pretreated by adding a 30% ethanol solution and heating to 55°C at a rate of 5°C / min, holding for 20 min. Then, 160 ml of white kidney bean α-AI (25% solids content) was added for primary encapsulation, and the mixture was stirred at a low speed of 90 r / min. Ethanol was removed under a vacuum of -0.05 MPa until the ethanol content was below 3%, yielding the primary encapsulation product. Then, 10 g of water-soluble dietary fiber was added, and the mixture was incubated under 55 W ultrasonic power for 25 min for secondary encapsulation to obtain microencapsulated α-AI. Comparative Example 4

[0050] Compared with Example 4, the difference is that there is no secondary embedding process, as detailed below: The hydroxypropyl porous starch of white kidney beans was pretreated by adding a 30% ethanol solution and heating it to 55°C at a rate of 5°C / min, holding it for 20 min. Then, 160 ml of white kidney bean α-AI (solid content of 25%) was added for one encapsulation. After stirring at a low speed of 90 r / min, the temperature was lowered to 25°C at a rate of 5°C / min, and held for 30 min. The ethanol was removed under a vacuum of -0.05 MPa until the ethanol content was less than 3%, thus obtaining microencapsulated α-AI. Comparative Example 5

[0051] Compared to Example 4, the difference lies in the ratio of white kidney bean α-AI, white kidney bean hydroxypropyl porous starch, and water-soluble dietary fiber during encapsulation, as detailed below: 70g of white kidney bean starch was weighed and prepared into a 30% starch slurry. This slurry was then subjected to enzymatic hydrolysis and etherification. Modified white kidney bean hydroxypropyl porous starch was pretreated by adding a 30% ethanol solution and heating to 55℃ at a rate of 5℃ / min, holding for 20 min. Then, 160ml of white kidney bean α-AI (25% solids content) was added for primary encapsulation. The mixture was stirred at a low speed of 90r / min and then cooled to 25℃ at a rate of 5℃ / min, holding for 30 min. Ethanol was removed under a vacuum of -0.05MPa until the ethanol content was below 3%, yielding the primary encapsulation product. 10g of water-soluble dietary fiber was then added, and the mixture was incubated under 55W ultrasonic power for 25 min for secondary encapsulation, resulting in microencapsulated α-AI. Comparative Example 6

[0052] Compared to Example 4, the difference lies in the ratio of white kidney bean α-AI, white kidney bean hydroxypropyl porous starch, and water-soluble dietary fiber during encapsulation, as detailed below: 20g of white kidney bean starch was weighed and prepared into a 30% starch slurry. This slurry was then subjected to enzymatic hydrolysis and etherification. Modified white kidney bean hydroxypropyl porous starch was pretreated by adding a 30% ethanol solution and heating to 55℃ at a rate of 5℃ / min, holding for 20 min. Then, 160ml of white kidney bean α-AI (25% solids content) was added for primary encapsulation. The mixture was stirred at 90 rpm and then cooled to 25℃ at a rate of 5℃ / min, holding for 30 min. Ethanol was removed under a vacuum of -0.05MPa until the ethanol content was below 3%, yielding the primary encapsulation product. 10g of water-soluble dietary fiber was then added, and the mixture was incubated at 55W ultrasonic power for 25 min for secondary encapsulation, resulting in microencapsulated α-AI. Comparative Example 7

[0053] Compared with Example 4, the difference is that commercially available porous corn starch was selected, and it was enzymatically hydrolyzed and etherified in the manner of Example 4, and then used as a wall material for primary encapsulation of white kidney bean α-AI. Comparative Example 8

[0054] Compared with Example 4, the porosity of white kidney bean starch in step two did not reach 40%, specifically: Step two involves enzymatic hydrolysis and etherification of white kidney bean starch. Specifically, 50g of white kidney bean starch is weighed and prepared into a 30% starch slurry. 0.05% (relative to the dry weight of starch) of CaCl2 is added, and the pH is adjusted to 5.5. Then, 2% (relative to the dry weight of starch) of pullulanase (enzyme activity of 2000U / g) is added, and the mixture is hydrolyzed for 1 hour to obtain starch with a porous surface. When the porosity of the starch reaches 35%, 5% (relative to the dry weight of starch) of Na2SO4 and 0.8% (relative to the dry weight of starch) of NaOH are added. After stirring evenly, 7% (relative to the dry weight of starch) of propylene oxide is added under nitrogen protection, and the etherification reaction is carried out at 40°C for 12 hours. After the reaction is completed, the pH is adjusted to 6.5 with 5% dilute hydrochloric acid. After washing and dehydration by a hydrocyclone, modified white kidney bean hydroxypropyl porous starch is obtained. Test Example 1

[0055] Examples 1-3 and regular rice noodles (without added white kidney bean α-AI) were tested for glycemic index (GI) according to WS / T 652-2019 "Methods for Determination of Glycemic Index of Foods". A total of 11 subjects were included, with a mean age of (27.7±5.4) years and a BMI of (21.2±2.0) kg / m². 2The fasting blood glucose level was (5.08±0.42) mmol / L.

[0056] (1) Definitions involved Glycemic Index (GI): This is a characteristic of carbohydrates in food, referring to the ability of digestible carbohydrates in food to raise blood sugar levels.

[0057] Increased area under the curve: Area under the curve above the fasting blood glucose level.

[0058] Standard deviation: It is the square root of the arithmetic mean of the squared deviations of all measurements from the mean of a population. It reflects the degree of dispersion among individuals within a group.

[0059] Standard error: the ratio of the standard deviation of each measurement to the square root of the number of participants.

[0060] Where s indicates the standard deviation of a measurement, and n indicates the number of subjects.

[0061] (2) Determination of GI value Measurement Method: Three food trials were conducted, with each trial spaced 72 hours apart. The rice noodle test was scheduled between two glucose tests. For three days prior to the test, subjects maintained a regular sleep schedule and normal diet. The day before the test, high-fiber and high-sugar foods were avoided for dinner. Fasting began before 10 PM. On the day of the test, strenuous exercise was avoided. The test began after subjects sat quietly for 10 minutes. Fasting blood glucose concentrations were measured twice. Eating was required to be completed within 5-10 minutes, with timing starting from the first bite. Blood samples were collected at 15, 30, 45, 60, 90, and 120 minutes post-meal, using an indwelling needle to collect venous blood from the back of the hand / elbow. Consistency of blood sampling sites was ensured throughout the testing period. Blood glucose concentration was measured using the hexokinase method. A glycemic response curve was plotted with time (t) on the x-axis and blood glucose concentration (ct) on the y-axis. The area under the glycemic response curve (IAUC) was calculated using a geometric method. The formula for calculating the glycemic index (GI) of rice is as follows:

[0062]

[0063] In the formula: GI n - GI value obtained from individual subjects; At-meter IAUC value; A ref - The average of two glucose IAUC measurements taken from the same individual; n - The final number of subjects included; GI - The GI value of the rice noodles.

[0064] The table below shows the average GI values ​​of low-GI rice noodles and regular rice noodles prepared in Examples 1-3.

[0065] As shown in the table above, the low-GI rice noodles prepared in Examples 1-3 have a significantly lower GI value compared to ordinary rice noodles purchased from the market. This is because ordinary rice noodles have a higher starch content, resulting in faster digestion and a higher glycemic index. The low-GI rice noodles in Examples 1-3 of this invention contain a composition in which microencapsulated α-AI, rich in amylase inhibitors, can greatly slow down the digestion and absorption of carbohydrates, thus preventing a significant rise in blood sugar levels and effectively stabilizing blood sugar fluctuations. Test Example 2

[0066] The microencapsulated α-AI prepared in Examples 4-6 differed from that in Comparative Examples 1-7 in terms of encapsulation effect and heat resistance. The encapsulation effect was reflected by the inhibitory activity of the microencapsulated α-AI against α-amylase, and the test results were expressed as inhibitory activity (U / g). The heat resistance of the microencapsulated α-AI was tested by heating it at 90°C for 30 min, and the activity retention value (%) was calculated. The water solubility of the microencapsulated α-AI was tested according to GB5413.29-2010 "Determination of Solubility of Infant Foods and Dairy Products", and the test results were expressed as sample solubility rate (%). Specific data are shown in the table below:

[0067]

[0068]

[0069] The α-amylase inhibitory activities of the microencapsulated α-AI prepared in Examples 4-6 were all above 10,000, and they exhibited excellent heat resistance at 90°C, with an activity retention value of over 85% and a solubility of over 99%, meaning they could be basically completely dissolved in water.

[0070] In Comparative Example 1, during the directional separation and extraction, the collected effluent contained low levels of water-soluble dietary fiber and had low purity, resulting in poor secondary encapsulation and consequently affecting the inhibitory activity of microencapsulated α-AI against α-amylase. In Comparative Example 2, after etherification treatment of white kidney bean starch, the high viscosity of the hydroxypropyl porous starch was unfavorable for encapsulating white kidney bean α-AI, leading to poor encapsulation and a significant decrease in inhibitory activity and heat resistance against α-amylase. In Comparative Example 3, during the initial encapsulation of white kidney bean α-AI... Firstly, heating expands the pores of the hydroxypropyl porous starch from white kidney beans, allowing more α-AI from the white kidney beans to be embedded within the pores. However, no subsequent cooling process was performed, resulting in unstable embedding. Consequently, most of the α-AI from the white kidney beans detached from the pores and became inactive due to the high temperature, thus reducing both α-amylase inhibitory activity and heat resistance. Comparative Example 4, lacking a secondary embedding process, also suffered from reduced α-amylase inhibitory activity due to the ineffective embedding. Comparative Example 5, with its high proportion of hydroxypropyl porous starch from white kidney beans, showed a better effect on... In proportion 6, the proportion of hydroxypropyl porous starch from white kidney beans was low. Data in the table shows that excessive hydroxypropyl porous starch reduced the purity of white kidney bean α-AI, significantly impacting its inhibitory activity. Conversely, insufficient hydroxypropyl porous starch prevented complete encapsulation of white kidney bean α-AI, significantly affecting heat resistance; therefore, heating at 90℃ for 30 minutes resulted in poor activity retention. In contrast, proportion 7 used ordinary porous starch, which, after enzymatic hydrolysis and etherification, was used for a single encapsulation of white kidney bean α-AI. The α-amylase inhibitory activity and heat resistance of the microencapsulated α-AI obtained were much lower than those of Example 4, indicating that the hydroxypropyl porous starch of white kidney bean is not only more suitable as a primary encapsulation wall material for encapsulating α-AI of white kidney bean, which greatly improves the encapsulation effect and stability, but also enables the recycling and reuse of white kidney bean residue, greatly reducing economic costs. In contrast, the 8-hydroxypropyl porous starch of the comparative example did not reach an opening rate of 40%, resulting in a reduction in the amount of white kidney bean α-AI that could be encapsulated, and thus a significant decrease in α-amylase inhibitory activity.

[0071] Figure 2 The image shows an electron microscope image of white kidney bean α-AI without embedding treatment. The white kidney bean α-AI in the image has an irregular shape, uneven size, and uneven edges, which will result in poor flowability and poor water solubility. Figure 3a The image shows an electron micrograph of microencapsulated α-AI encapsulated after enzymatic hydrolysis and etherification of porous corn starch in Comparative Example 7. As can be seen from the image, the edges are slightly smooth, and the distribution is relatively uniform. Figure 2 Slight improvement, but the shape remains irregular; Figure 3b The image shows an electron microscope image of the microencapsulated α-AI prepared in Example 4. The microencapsulated α-AI shows significant improvement overall, with smooth edges, regular shape, and uniform distribution, indicating that white kidney bean hydroxypropyl porous starch is the best material for primary encapsulation.

[0072] in addition, Figure 4 The graph shows a comparison of water solubility tests, where tube a represents the microencapsulated α-AI from Example 4, tube b represents the microencapsulated α-AI from Comparative Example 7, and tube c represents untreated white kidney bean α-AI. As can be seen from the graph, when 10g of each sample was dissolved in 10ml of water, the microencapsulated α-AI prepared in Example 4 exhibited the best solubility, the highest solution transparency, and the sample was almost completely dissolved in water.

[0073] Note that the above embodiments are merely preferred embodiments of the present invention and the technical principles applied thereto, and are not intended to limit the invention. Those skilled in the art can make various obvious changes, readjustments, and substitutions to the technical solutions described in the foregoing embodiments based on the ideas of the embodiments of the present invention without departing from the protection scope of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A composition utilizing all components of white kidney beans, characterized in that, It includes microencapsulated α-AI and insoluble dietary fiber derived from white kidney beans, wherein the microencapsulated α-AI accounts for 20%–70% and the insoluble dietary fiber accounts for 30%–80%; The microencapsulated α-AI is first encapsulated with hydroxypropyl porous starch derived from white kidney beans and then second encapsulated with water-soluble dietary fiber derived from white kidney beans.

2. The composition according to claim 1, characterized in that, The α-amylase inhibitory activity of the microencapsulated α-AI is 10,000-20,000 U / g; the activity retention rate of the microencapsulated α-AI is ≥90% after treatment at 90℃ for 30 min.

3. The composition according to claim 1, characterized in that, The encapsulation rate of the microencapsulated α-AI is 60%-85%.

4. The composition according to claim 1, characterized in that, The degree of hydroxypropyl substitution of the hydroxypropyl porous starch is 0.05-0.

2.

5. A method for preparing the composition according to any one of claims 1-4, characterized in that, include: White kidney beans were directionally separated and extracted to obtain white kidney bean α-AI, water-soluble dietary fiber, white kidney bean starch and insoluble dietary fiber; The white kidney bean starch was subjected to enzymatic hydrolysis and etherification to obtain white kidney bean hydroxypropyl porous starch with an open porosity of 40%–60%. The encapsulation process is carried out in an ethanol system: the temperature is first raised to 55-65℃ to expand the pores of the white kidney bean hydroxypropyl porous starch; white kidney bean α-AI is added and stirred, and then the temperature is lowered to 30-40℃ to shrink the pores and form an encapsulation structure. The ethanol is removed under negative pressure to obtain the encapsulation product. Water-soluble dietary fiber was added under 50-65W ultrasound conditions for secondary encapsulation to obtain microencapsulated α-AI; The microencapsulated α-AI was mixed evenly with insoluble dietary fiber to obtain a composition that utilizes all components of white kidney bean.

6. The method for preparing the composition according to claim 5, characterized in that, The targeted separation and extraction includes: S1: After crushing, slurrying, and extracting white kidney beans, a single separation is performed to obtain solid and liquid phases respectively; S2: The liquid phase is subjected to secondary separation and membrane separation, the molecular weight of the effluent is less than 10kDa, and the molecular weight of the retentate is between 10kDa and 60kDa. The membrane separation process involves first passing the supernatant through a 0.2µm microfiltration membrane, and then sequentially through a 60kDa ultrafiltration membrane and a 10kDa ultrafiltration membrane. The main component of the effluent is water-soluble dietary fiber, and the retentate is concentrated under negative pressure to contain 15-25% solids, which is white kidney bean α-AI. S3: The solid phase described in S1 is centrifuged to obtain insoluble dietary fiber and white kidney bean starch, respectively.

7. The method for preparing the composition according to claim 5, characterized in that, The ethanol concentration is 30%-50%.

8. The method for preparing the composition according to claim 5, characterized in that, The negative pressure is -0.05MPa to -0.09MPa.

9. The method for preparing the composition according to claim 5, characterized in that, The white kidney bean starch accounts for 30%-60%, the white kidney bean α-AI accounts for 30%-65%, and the water-soluble dietary fiber accounts for 10%-20%.

10. Use of the composition according to any one of claims 1-9 in the preparation of low-GI foods.

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