Method for preparing low-GI rice noodles from white kidney bean-mulberry leaf composite extract

Abstract

The invention discloses a method for preparing low-GI rice noodles from a white kidney bean-mulberry leaf composite extract, which comprises the following steps of: firstly, extracting functional components in white kidney beans and mulberry leaves by adopting a water extraction method, adding Arabic gum and resistant dextrin into a white kidney bean-mulberry leaf composite extracting solution, regulating acid, and performing glycosylation and embedding treatment; uniformly mixing rice flour, high amylose, fiber powder, konjac glucomannan, mono-glycerol fatty acid ester, diglycerol fatty acid ester and the white kidney bean-mulberry leaf compound extracting solution; and finally, humidifying, cooking, extruding and forming to obtain the low-GI rice noodles. According to the invention, the glucogenic index of the rice noodles is reduced by adding the white kidney bean-mulberry leaf composite extract, the heat resistance of functional components in the composite extract is improved through glycosylation and embedding treatment, and the loss of the activity of the white kidney bean-mulberry leaf composite extract in the high-temperature cooking process of the rice noodles is reduced; meanwhile, in order to improve the flavor and taste of the low-GI rice noodles, the konjac glucomannan and other auxiliary materials are added, so that the low-GI rice noodles are rich in elasticity and better in taste and boiling fastness.

Description

Technical Field

[0001] The invention relates to the field of health and nutrition, and in particular to a method for preparing low-GI rice noodles using a white kidney bean-mulberry leaf composite extract. Background Art

[0002] Rice noodles are a traditional Chinese snack that is widely loved by the public. They are rich in carbohydrates, cook quickly and evenly, are resistant to boiling and do not become mushy, are refreshing and tender, and the soup is not turbid after cooking. They are easy to digest and are particularly suitable for casual fast food.

[0003] With the improvement of modern living standards, dietary imbalance and lack of physical activity, the incidence of chronic metabolic diseases represented by obesity and diabetes among Chinese residents has shown an increasing trend year by year. According to the "China Residents' Nutrition and Chronic Disease Health Report (2020)", the prevalence of diabetes in China has reached 11.9%, making it the country with the largest population of diabetes in the world. my country's "Dietary Guidelines for Adult Diabetes", the American ADA and the European Diabetes Association's Dietary Management Guidelines all state that dietary intervention is an effective and feasible way to prevent chronic metabolic diseases such as diabetes and obesity. Studies have shown that low glycemic index (GI) foods can reduce insulin secretion, relieve insulin resistance, stabilize postprandial blood sugar and delay hunger, and are ideal foods for obese and diabetic people.

[0004] Most of the staple food in my country is refined rice products. Rice noodles have a high starch content. Starch needs to be hydrolyzed by human digestive enzymes and converted into glucose before it can be absorbed by the body. If the starch is hydrolyzed too quickly, the glucose content in the body will increase rapidly, which will have a great impact on blood sugar control. Based on this, rice noodles with a low glycemic index have become a research hotspot today.

[0005] The white kidney bean extract isolated from white kidney bean contains α-amylase inhibitor (α-AI), which can delay the hydrolysis and digestion of starch in food, reduce calorie intake, regulate blood sugar after meals, etc. At present, patent number CN107318926A discloses a method for preparing sugar-controlled biscuits, which uses white kidney bean extract as the main ingredient, and mainly relies on the α-amylase inhibitor in the white kidney bean extract to slow down the digestion and absorption of starch, thereby achieving the purpose of sugar control. However, the effective ingredient of white kidney bean extract is glycoprotein, which has the performance defect of poor heat resistance. The study of "Extraction and Performance Study of α-amylase Inhibitors in White Kidney Beans, Food Science and Technology, 2017" by Chi Yongnan et al. shows that when the temperature exceeds 70°C, the amylase inhibitory activity of white kidney bean extract will decrease. The performance defect of thermal instability of white kidney bean extract seriously limits its application in food processing. In addition, the inhibitory effect of white kidney bean extract on amylase occurs in the small intestine. The main component of white kidney bean extract is glycoprotein. During the digestion process of the human body, the protease in the gastric juice will cause its inhibitory activity to be lost, resulting in a decrease in its efficacy. Therefore, the sugar-controlled biscuits of this patent have low inhibitory activity on amylase, the sugar-controlled effect is not ideal, and the taste and flavor are poor.

[0006] Patent CN112155157A also discloses a mixed bean rice noodle, which is prepared by mixing rice flour and mixed bean flour with water, and then steaming to completely gelatinize the starch, and recrystallize the starch to form digestion-resistant starch, thereby achieving the purpose of low GI. However, the rice noodles prepared by this preparation method have increased cooking loss, a hard texture, and a small reduction in the glycemic index.

[0007] Therefore, finding a low GI rice noodle that can solve the above-mentioned technical problems becomes an important topic studied by those skilled in the art. Summary of the invention

[0008] The invention discloses a method for preparing low GI rice noodles by using a white kidney bean-mulberry leaf composite extract, which is used to solve the technical problems that the existing low GI rice noodles have poor heat resistance and poor taste and flavor.

[0009] To achieve this object, the present invention adopts the following technical solutions:

[0010] A method for preparing low GI rice noodles using a white kidney bean-mulberry leaf composite extract, comprising:

[0011] The first step is to extract the crushed white kidney bean and mulberry leaf with water, and obtain the white kidney bean-mulberry leaf composite extract with an α-amylase inhibitory activity of ≥6000U / g after separation, purification and concentration;

[0012] In the second step, gum arabic and resistant dextrin are added to the white kidney bean-mulberry leaf composite extract, and the mixture is subjected to glycosylation embedding treatment after acidification. In order to improve the heat resistance of the white kidney bean extract, the present invention performs glycosylation embedding treatment on the white kidney bean-mulberry leaf composite extract, connects sugar chains to proteins in a specific manner, changes the protein configuration, and further improves the stability of the white kidney bean extract, thereby obtaining a white kidney bean-mulberry leaf composite extract having an activity retention value of ≥80% when heated and kept at 90°C for 30 minutes.

[0013] The third step is to evenly mix the rice flour, high-amylose starch, fiber powder, konjac powder and mono- and diglycerol fatty acid esters with the white kidney bean-mulberry leaf composite extract according to a certain proportion, and extrude the mixture after steaming to finally obtain low GI rice noodles with the white kidney bean-mulberry leaf composite extract.

[0014] It should be noted that white kidney bean extract contains α-amylase inhibitors, which can specifically inhibit the activity of α-amylase in human saliva and intestines, reduce the digestion rate and amount of starch in food from the source, and achieve the purpose of lowering blood sugar and reducing fat. Mulberry leaf extract contains α-glucose enzyme inhibitors, which can block the decomposition of maltose and maltotriose by α-glucosidase, thereby reducing the production of glucose. Mulberry leaf extract can also regulate the release of insulin to a certain extent, promote the synthesis of glycogen from blood sugar, and thus lower blood sugar levels. In summary, the white kidney bean-mulberry leaf composite extract can inhibit the decomposition of starch into glucose from multiple dimensions, further enhancing the ability to lower blood sugar and reduce fat.

[0015] Furthermore, the crushed white kidney beans and mulberry leaves are subjected to water extraction, specifically:

[0016] Step 1, crushing and sieving white kidney beans and mulberry leaves, and then mixing them in a mass ratio of 1:0.1-1;

[0017] Step 2, adding 8 to 15 times the mass of pure water, soaking in a water bath at 45 to 65° C. for 1 to 3 hours, centrifuging at a speed of 3500 to 5000 r / min, and taking the supernatant;

[0018] Step three, centrifuging the supernatant for a second time at a speed of 8000-16000 r / min to obtain a separated and purified white kidney bean-mulberry leaf composite extract supernatant.

[0019] As a preferred technical solution, the present invention performs two centrifugal operations on white kidney beans and mulberry leaves, first removes macromolecular starch and fiber ineffective in the white kidney bean-mulberry leaf extract by low-speed centrifugation, and then further separates and purifies the extract by high-speed centrifugation. The current extraction methods include alcohol precipitation, acid precipitation, ammonium sulfate, enzyme method, dialysis, ion exchange chromatography, etc., but the yield of alcohol precipitation and acid precipitation is not high; the ammonium sulfate method requires a large amount of reagents and is not environmentally friendly; the enzyme method will cause activity loss in the enzyme inactivation link; dialysis and ion exchange methods are difficult to mass industrial production. This method adopts a physical water extraction method to separate the extract, intercept and separate substances of different molecular weights, achieve the purpose of purification and concentration, and further improve the purity of the white kidney bean-mulberry leaf composite extract on the basis of maintaining the complete spatial structure of the glycoprotein α-amylase inhibitor, and has the advantages of mild conditions, energy saving and environmental protection, and good separation effect.

[0020] Furthermore, the concentration is specifically:

[0021] The white kidney bean-mulberry leaf composite extract clear solution is vacuum concentrated at -0.04 to -0.08 MPa and 50 to 75° C. When the solid content is 10% to 25%, the α-amylase inhibition activity of the white kidney bean-mulberry leaf composite extract is ≥6000 U / g.

[0022] It should be noted that when the solid content is between 10% and 25%, the α-amylase inhibition activity of the obtained white kidney bean-mulberry leaf composite extract is ≥6000U / g. If the solid content is too high, the viscosity of the system is too high, which is not conducive to the mixing and embedding of subsequent materials. At the same time, if the solid content is too low, it will also affect the embedding treatment time and efficiency, thereby affecting the heat resistance of the white kidney bean-mulberry leaf composite extract.

[0023] Furthermore, the white kidney bean-mulberry leaf composite extract is added with gum arabic and resistant dextrin, and the glycosylation embedding treatment is performed after acid adjustment, specifically:

[0024] Step 1, adding gum arabic and resistant dextrin in a ratio of 1:0.5-3 into 70-100°C pure water, stirring at high speed and heating for 30-60 minutes, and then cooling to 40-60°C to obtain an embedding solution; it should be noted that the mass concentration of the aqueous solution of gum arabic is 20%-40%, and the mass concentration of the aqueous solution of resistant dextrin is 25%-45%.

[0025] Step 2, adjusting the embedding solution to a pH of 4.8 to 6.5 using a citric acid solution;

[0026] Step three, taking 5-30% of the acid-adjusted embedding solution according to the mass of the white kidney bean-mulberry leaf composite extract, adding it to the white kidney bean-mulberry leaf composite extract, performing glycosylation embedding treatment, reacting for 10-35 minutes, and obtaining a white kidney bean-mulberry leaf composite extract having an activity retention value ≥80% when heated and kept at 90°C for 30 minutes.

[0027] Furthermore, the concentration of the citric acid solution is 1 mol / L.

[0028] Furthermore, the white kidney beans are crushed and sieved to a mesh size of 30 to 100 meshes; and the mulberry leaves are crushed and sieved to a mesh size of 10 to 60 meshes.

[0029] Furthermore, the high-amylose starch, fiber powder, konjac powder, rice flour and mono- and di-glycerol fatty acid esters are uniformly mixed with the white kidney bean-mulberry leaf composite extract according to a certain proportion, specifically:

[0030] The raw material liquid is prepared by preparing a high-amylose starch content of 5-10%, a fiber powder content of 3-10%, a konjac powder content of 0.5-3%, a mono- and di-glycerol fatty acid ester content of 0.01-0.05%, and a rice powder content of 65-85%, adding pure water and mixing evenly;

[0031] Then, the raw material liquid is added into the white kidney bean-mulberry leaf composite extract liquid with a content of 0.5-10%.

[0032] As a preferred technical solution, the effect is best when the content of white kidney bean-mulberry leaf composite extract is 1-3%; the content of rice flour, high amylose starch, fiber powder, konjac flour and mono- and diglycerol fatty acid esters can be adaptively adjusted within their content range. It should be noted that the content described here is the mass percentage of each component to the whole.

[0033] Furthermore, the high-amylose starch is high-amylose corn starch; and the fiber powder is any one or more combinations of sugarcane fiber, oat fiber, inulin, coconut powder and flaxseed powder.

[0034] The invention also discloses a low GI rice noodle, which is the low GI rice noodle prepared by the white kidney bean-mulberry leaf composite extract according to the method.

[0035] It can be seen from the above technical solutions that the present invention has the following beneficial effects:

[0036] 1. The low GI rice noodles prepared by the present invention are added with a white kidney bean-mulberry leaf composite extract, wherein the α-amylase inhibitor contained in the white kidney bean can inhibit the conversion of starch into maltose and maltotriose, and the glucose enzyme inhibitor contained in the mulberry leaf can block the conversion of maltose, maltotriose, etc. into glucose. Through the synergistic effect of the two functional ingredients, the speed of starch hydrolysis into glucose is greatly slowed down, thereby achieving the purpose of sugar control; at the same time, the present invention adopts a one-step method to extract the two functional ingredients, and the process effect can achieve an α-amylase inhibition activity of ≥6000U / g, which is not only simple and convenient to operate, but also has a higher extraction rate and is more suitable for industrial production.

[0037] 2. In order to solve the problem of poor heat resistance of α-amylase inhibitors, the present invention glycosylates and encapsulates α-amylase inhibitors through gum arabic and resistant dextrin, thereby greatly improving its heat resistance, so that the low GI rice noodles prepared by the present invention can maintain a high activity retention value of the effective ingredients after high-temperature cooking.

[0038] 3. In order to improve the edible quality of low GI rice noodles, the present invention enhances the elasticity and boiling resistance of low GI rice noodles by adding konjac flour and mono- and di-glycerol fatty acid esters; while ensuring the flavor and taste of the rice noodles, high-amylose starch and fiber powder are also added to increase satiety and provide a higher dietary fiber content. DETAILED DESCRIPTION

[0039] The present invention will be further described below in conjunction with the embodiments.

[0040] It should be noted that the following example is only a specific implementation method of the technical solution of the present invention. Taking the total mass of the raw materials and the white kidney bean-mulberry leaf composite extract as 300g as an example, the specific addition amounts of high-amylose starch, fiber powder, konjac flour, rice flour, mono- and diglycerol fatty acid esters and the white kidney bean-mulberry leaf composite extract are given. In actual preparation and production, the numerical values ​​can be adjusted according to specific circumstances, and the present invention does not limit the specific addition amount values.

[0041] Example 1

[0042] The present invention provides an embodiment: a method for preparing low GI rice noodles with a white kidney bean-mulberry leaf composite extract, comprising:

[0043] S1. The crushed white kidney bean and mulberry leaf are subjected to water extraction, specifically: the white kidney bean and mulberry leaf are crushed and sieved, and then mixed in a mass ratio of 1:0.1; then 8 times the mass of pure water is added, and after soaking in a 65°C water bath for 1 hour, centrifuged at a speed of 3500r / min, and the supernatant is taken; finally, the supernatant is centrifuged for a second time at a speed of 10000r / min to obtain a separated and purified white kidney bean-mulberry leaf composite extract clear liquid.

[0044] S2. The separated and purified white kidney bean-mulberry leaf composite extract supernatant is concentrated, specifically: the white kidney bean-mulberry leaf composite extract supernatant is vacuum concentrated at -0.04MPa and 60°C. When the solid content is 10%, the α-amylase inhibition activity of the white kidney bean-mulberry leaf composite extract is 6307U / g.

[0045] S3. Add gum arabic and resistant dextrin to the white kidney bean-mulberry leaf composite extract, adjust the acidity and perform glycosylation embedding treatment, specifically: add gum arabic and resistant dextrin in a ratio of 1:0.5 to 80°C pure water, stir at high speed and heat for 45 minutes, then cool to 45°C to obtain embedding solution; then adjust the embedding solution to pH 5 with citric acid solution; finally, take 17.7g of the white kidney bean-mulberry leaf composite extract, and then take embedding solution according to 10% of the mass of the white kidney bean-mulberry leaf extract, that is, take 1.77g of embedding solution, mix the white kidney bean-mulberry leaf composite extract and the embedding solution, perform glycosylation embedding treatment, and after reacting for 15 minutes, obtain 19.47g of the white kidney bean-mulberry leaf composite extract having an activity retention value of 85.7% when heated and kept at 90°C for 30 minutes.

[0046] S4. Mix the raw material liquid and the white kidney bean-mulberry leaf composite extract, specifically: prepare: the high amylose content is 5%, i.e. 15g of high amylose corn starch; the fiber powder content is 3%, i.e. 9g of sugarcane fiber; the konjac powder content is 0.5%, i.e. 1.5g of konjac powder; the mono- and di-glycerol fatty acid ester content is 0.01%, i.e. 0.03g of mono- and di-glycerol fatty acid ester, and the rice flour content is 85%, i.e. 255g of rice flour; after mixing evenly, add pure water to obtain the raw material liquid; then add the raw material liquid to the white kidney bean-mulberry leaf composite extract obtained in S3. It should be noted that the content of the white kidney bean-mulberry leaf composite extract is 6.49%.

[0047] S5. The mixed raw material liquid and white kidney bean-mulberry leaf composite extract are humidified, steamed, and extruded to obtain low GI rice noodles.

[0048] Preferably, the fiber powder may also be any one or more combinations of oat fiber, inulin, coconut powder and flaxseed powder.

[0049] Example 2

[0050] As a preferred technical solution, the effect is best when the content of white kidney bean-mulberry leaf composite extract is 1-4%; the content of high-amylose starch, fiber powder, konjac powder, rice flour and mono- and di-glycerol fatty acid esters can be adaptively adjusted within their content range. It should be noted that the content here is the mass percentage of each component to the whole.

[0051] This embodiment provides a method for preparing low GI rice noodles using a white kidney bean-mulberry leaf composite extract, comprising:

[0052] S1. The crushed white kidney bean and mulberry leaf are subjected to water extraction, specifically: the white kidney bean and mulberry leaf are crushed and sieved, and then mixed in a mass ratio of 1:0.6; then 10 times the mass of pure water is added, and after soaking in a 65°C water bath for 1.5 hours, centrifuged at a speed of 4500r / min, and the supernatant is taken; finally, the supernatant is centrifuged for a second time at a speed of 13000r / min to obtain a separated and purified white kidney bean-mulberry leaf composite extract clear liquid.

[0053] S2. The separated and purified white kidney bean-mulberry leaf composite extract supernatant is concentrated, specifically: the white kidney bean-mulberry leaf composite extract supernatant is vacuum concentrated at -0.06MPa and 60°C. When the solid content is 17%, the α-amylase inhibition activity of the white kidney bean-mulberry leaf composite extract is 8225U / g.

[0054] S3. Add gum arabic and resistant dextrin to the white kidney bean-mulberry leaf composite extract, adjust the acidity and perform glycosylation embedding treatment, specifically: add gum arabic and resistant dextrin in a ratio of 1:1.5 to 80°C pure water, stir at high speed and heat for 45 minutes, then cool to 40°C to obtain embedding solution; then adjust the embedding solution to pH 5 with citric acid solution; finally, take 4g of the white kidney bean-mulberry leaf composite extract, and then take embedding solution according to 25% of the mass of the white kidney bean-mulberry leaf composite extract, that is, take 1g of embedding solution, mix the two and perform glycosylation embedding treatment, react for 20 minutes, and obtain 5g of the white kidney bean-mulberry leaf composite extract having an activity retention value of 83.6% when heated and kept at 90°C for 30 minutes.

[0055] S4. Mix the raw material liquid and the white kidney bean-mulberry leaf composite extract, specifically: the high-amylose content is 8%, i.e. 24g of high-amylose corn starch; the fiber powder content is 6%, i.e. 18g of oat fiber powder; the konjac powder content is 1.3%, i.e. 3.9g of konjac powder; the mono- and di-glycerol fatty acid ester content is 0.03%, i.e. 0.09g of mono- and di-glycerol fatty acid ester, and the rice flour content is 83%, i.e. 249g of rice flour; after mixing evenly, pure water is added to obtain the raw material liquid; and the raw material liquid is added to the white kidney bean-mulberry leaf composite extract obtained in S3. It should be noted that the content of the white kidney bean-mulberry leaf composite extract is 1.67%.

[0056] S5. The mixed raw material liquid and white kidney bean-mulberry leaf composite extract are humidified, steamed, and extruded to obtain low GI rice noodles.

[0057] Example 3

[0058] This embodiment provides a method for preparing low GI rice noodles using a white kidney bean-mulberry leaf composite extract, comprising:

[0059] S1. The crushed white kidney bean and mulberry leaf are subjected to water extraction, specifically: the white kidney bean and mulberry leaf are crushed and sieved, and then mixed in a mass ratio of 1:1; 15 times the mass of pure water is added, and after soaking in a 65°C water bath for 3 hours, centrifuged at a speed of 5000r / min, and the supernatant is taken; finally, the supernatant is centrifuged for a second time at a speed of 16000r / min to obtain a separated and purified white kidney bean-mulberry leaf composite extract clear liquid.

[0060] S2. The separated and purified white kidney bean-mulberry leaf composite extract supernatant is concentrated, specifically: the white kidney bean-mulberry leaf composite extract supernatant is vacuum concentrated at -0.06MPa and 60°C. When the solid content is 17%, the α-amylase inhibition activity of the white kidney bean-mulberry leaf composite extract is 9826U / g.

[0061] S3. Add gum arabic and resistant dextrin to the white kidney bean-mulberry leaf composite extract, adjust the acidity and perform glycosylation embedding treatment, specifically: add gum arabic and resistant dextrin in a ratio of 1:3 to 100°C pure water, stir at high speed and heat for 60 minutes, then cool to 60°C to obtain embedding solution; then adjust the embedding solution to pH 5 with citric acid solution; finally, take 4g of the white kidney bean-mulberry leaf composite extract, and then take embedding solution according to 10% of the mass of the white kidney bean-mulberry leaf composite extract, that is, take 0.41g of embedding solution, mix the two and perform glycosylation embedding treatment, react for 20 minutes, and obtain 4.41g of the white kidney bean-mulberry leaf composite extract having an activity retention value of 82.1% after heating and keeping at 90°C for 30 minutes.

[0062] S4. Mix the raw material liquid and the white kidney bean-mulberry leaf composite extract, specifically: prepare: the high amylose content is 8%, i.e. 24g of high amylose corn starch; the fiber powder content is 6%, i.e. 18g of oat fiber powder; the konjac powder content is 1.5%, i.e. 4.5g of konjac powder; the mono- and di-glycerol fatty acid ester content is 0.03%, i.e. 0.09g of mono- and di-glycerol fatty acid ester, and the rice flour content is 83%, i.e. 249g of rice flour; after mixing evenly, add pure water to obtain the raw material liquid; then add the raw material liquid to the white kidney bean-mulberry leaf composite extract obtained in S3. It should be noted that the content of the white kidney bean-mulberry leaf composite extract is 1.47%.

[0063] S5. The mixed raw material liquid and white kidney bean-mulberry leaf composite extract are humidified, steamed, and extruded to obtain low GI rice noodles.

[0064] Example 4

[0065] This embodiment provides a method for preparing low GI rice noodles with white kidney bean-mulberry leaf composite extract, which is consistent with the steps of embodiment 3, except that the content of white kidney bean-mulberry leaf composite extract in S4 is different, as follows:

[0066] S3. Add gum arabic and resistant dextrin to the white kidney bean-mulberry leaf composite extract, adjust the acidity and perform glycosylation embedding treatment, specifically: add gum arabic and resistant dextrin in a ratio of 1:3 to 100°C pure water, stir at high speed and heat for 60 minutes, then cool to 60°C to obtain embedding solution; then adjust the embedding solution to pH 5 with citric acid solution; finally, take 8.32g of the white kidney bean-mulberry leaf composite extract, and then take embedding solution according to 25% of the mass of the white kidney bean-mulberry leaf composite extract, that is, take 2.09g of embedding solution, mix the white kidney bean-mulberry leaf composite extract and the embedding solution, perform glycosylation embedding treatment, and after reacting for 20 minutes, obtain 10.41g of the white kidney bean-mulberry leaf composite extract having an activity retention value of 89.3% when heated and kept at 90°C for 30 minutes.

[0067] S4. Mix the raw material liquid and the white kidney bean-mulberry leaf composite extract, specifically: prepare: the high amylose content is 8%, i.e. 24g of high amylose corn starch; the fiber powder content is 6%, i.e. 18g of oat fiber powder; the konjac powder content is 1.5%, i.e. 4.5g of konjac powder; the mono- and di-glycerol fatty acid ester content is 0.03%, i.e. 0.09g of mono- and di-glycerol fatty acid ester; the rice flour content is 81%, i.e. 243g of rice flour; after mixing evenly, add pure water to obtain the raw material liquid; then add the raw material liquid to the white kidney bean-mulberry leaf composite extract obtained in S3. It should be noted that the content of the white kidney bean-mulberry leaf composite extract is 3.47%.

[0068] Example 5

[0069] This example provides a method for preparing low GI rice noodles with white kidney bean-mulberry leaf composite extract, which is consistent with the steps of Example 4, except that the time and temperature of the glycosylation embedding treatment in S3 are different, as follows:

[0070] S3. Add gum arabic and resistant dextrin to the white kidney bean-mulberry leaf composite extract, adjust the acidity and perform glycosylation embedding treatment, specifically: add gum arabic and resistant dextrin in a ratio of 1:3 to 100°C pure water, stir at high speed and heat for 60 minutes, and then cool to 60°C to obtain an embedding solution; then adjust the embedding solution to pH 5 with citric acid solution; finally, take 8.32g of the white kidney bean-mulberry leaf composite extract, and then take embedding solution according to 25% of the mass of the white kidney bean-mulberry leaf composite extract, that is, take 2.09g of embedding solution, mix the white kidney bean-mulberry leaf composite extract and the embedding solution, perform glycosylation embedding treatment, and after reacting for 35 minutes, obtain 10.41g of the white kidney bean-mulberry leaf composite extract having an activity retention value of 91.2% when heated and kept at 90°C for 30 minutes.

[0071] Example 6

[0072] This embodiment provides a method for preparing low GI rice noodles with a white kidney bean-mulberry leaf composite extract, which is consistent with the steps of Example 4, except that the solid content in S2 is different, as follows:

[0073] S2. The separated and purified white kidney bean-mulberry leaf composite extract supernatant is concentrated, specifically: the white kidney bean-mulberry leaf composite extract supernatant is vacuum concentrated at -0.06MPa and 60°C. When the solid content is 25%, the α-amylase inhibitory activity of the white kidney bean-mulberry leaf composite extract is 9792U / g, and the activity retention value after heating and keeping warm at 90°C for 30 minutes is 81.6%.

[0074] Comparative Example 1

[0075] Compared with Example 4, the difference is that mulberry leaves are not added in step S1, which is as follows:

[0076] S1. The crushed white kidney beans are subjected to water extraction, specifically: after the white kidney beans are crushed and sieved, 15 times the mass of pure water is added, and the mixture is extracted in a 65°C water bath for 3 hours, and then centrifuged at a speed of 5000r / min to obtain the supernatant; finally, the supernatant is centrifuged for a second time at a speed of 16000r / min to obtain a separated and purified white kidney bean-mulberry leaf composite extract clear liquid.

[0077] Comparative Example 2

[0078] Compared with Example 4, the difference is that white kidney beans are not added in step S1, which is as follows:

[0079] S1. The crushed mulberry leaves are subjected to water extraction, specifically: after the mulberry leaves are crushed and sieved, 10 times the mass of pure water is added, and the mixture is extracted in a 65°C water bath for 3 hours, and then centrifuged at a speed of 5000r / min to obtain the supernatant; finally, the supernatant is centrifuged for a second time at a speed of 16000r / min to obtain a separated and purified white kidney bean-mulberry leaf composite extract clear liquid.

[0080] Comparative Example 3

[0081] Compared with Example 4, the difference is that no secondary centrifugation is performed in step S1, which is as follows:

[0082] S1. The crushed white kidney bean and mulberry leaf are subjected to water extraction, specifically: the white kidney bean and mulberry leaf are crushed and sieved, and then mixed in a mass ratio of 1:1; then 15 times the mass of pure water is added, and the mixture is soaked in a 65°C water bath for 3 hours, and then centrifuged at a speed of 5000r / min, and the supernatant is taken to obtain a separated and purified white kidney bean-mulberry leaf composite extract clear liquid.

[0083] Comparative Example 4

[0084] Compared with Example 4, the difference is that the solid content in S2 is too low, as follows:

[0085] S2. The separated and purified white kidney bean-mulberry leaf composite extract supernatant is concentrated, specifically: when the white kidney bean-mulberry leaf composite extract supernatant is vacuum concentrated at -0.06MPa and 60°C to a solid content of 8%, the α-amylase inhibitory activity of the white kidney bean-mulberry leaf composite extract is measured to be 3827U / g, and the activity retention value after heating and keeping warm at 90°C for 30 minutes is 55.1%.

[0086] Comparative Example 5

[0087] Compared with Example 4, the difference is that the solid content in S2 is too high, as follows:

[0088] S2. The separated and purified white kidney bean-mulberry leaf composite extract supernatant is concentrated, specifically: when the white kidney bean-mulberry leaf composite extract supernatant is vacuum concentrated at -0.06MPa and 60°C to a solid content of 29%, the amylase inhibition activity of the white kidney bean-mulberry leaf composite extract is 2918U / g, and the activity retention value after heating and keeping warm at 90°C for 30 minutes is 47.8%.

[0089] Comparative Example 6

[0090] Compared with Example 4, the difference is that the glycosylation embedding treatment of S3 is not performed.

[0091] Comparative Example 7

[0092] Compared with Example 4, the difference is that in step S3, only gum arabic is used for glycosylation embedding treatment, which is as follows:

[0093] S3. Adding gum arabic to the white kidney bean-mulberry leaf composite extract, adjusting the acidity and performing glycosylation embedding treatment, specifically: adding gum arabic to 100°C pure water, stirring at high speed and heating for 60 minutes, and then cooling to 60°C to obtain an embedding solution; then adjusting the embedding solution to a pH of 5 with a citric acid solution; finally taking 8.32g of the white kidney bean-mulberry leaf composite extract, and then taking an embedding solution according to 25% of the mass of the white kidney bean-mulberry leaf composite extract, that is, taking 2.09g of the embedding solution, mixing the white kidney bean-mulberry leaf composite extract and the embedding solution, performing glycosylation embedding treatment, and reacting for 20 minutes to obtain 10.41g of the white kidney bean-mulberry leaf composite extract having an activity retention value of 65.3% when heated and kept at 90°C for 30 minutes.

[0094] Comparative Example 8

[0095] Compared with Example 4, the difference is that in step S3, only resistant dextrin is used for glycosylation embedding treatment, which is as follows:

[0096] S3. Add resistant dextrin to the white kidney bean-mulberry leaf composite extract, adjust the acidity and perform glycosylation embedding treatment, specifically: add resistant dextrin to 100°C pure water, stir at high speed and heat for 60 minutes, and then cool to 60°C to obtain embedding solution; then adjust the embedding solution to pH 5 with citric acid solution; finally, take 8.32g of the white kidney bean-mulberry leaf composite extract, and then take embedding solution according to 25% of the mass of the white kidney bean-mulberry leaf composite extract, that is, take 2.09g of embedding solution, mix the white kidney bean-mulberry leaf composite extract and the embedding solution, perform glycosylation embedding treatment, and after reacting for 20 minutes, obtain 10.41g of white kidney bean-mulberry leaf composite extract having an activity retention value of 70.9% when heated and kept at 90°C for 30 minutes.

[0097] Comparative Example 9

[0098] Compared with Example 4, the difference is that the proportion of gum arabic and resistant dextrin in step S3 is smaller, as follows:

[0099] S3. Add gum arabic and resistant dextrin to the white kidney bean-mulberry leaf composite extract, adjust the acidity and perform glycosylation embedding treatment, specifically: add gum arabic and resistant dextrin in a ratio of 1:5 to 100°C pure water, stir at high speed and heat for 60 minutes, and then cool to 60°C to obtain an embedding solution; then adjust the embedding solution to pH 5 with citric acid solution; finally, take 8.32g of the white kidney bean-mulberry leaf composite extract, and then take embedding solution according to 25% of the mass of the white kidney bean-mulberry leaf composite extract, that is, take 2.09g of embedding solution, mix the white kidney bean-mulberry leaf composite extract and the embedding solution, perform glycosylation embedding treatment, and after reacting for 20 minutes, obtain 10.41g of the white kidney bean-mulberry leaf composite extract having an activity retention value of 74.2% when heated and kept at 90°C for 30 minutes.

[0100] Comparative Example 10

[0101] Compared with Example 4, the difference is that in step S3, the high-speed stirring and heating for 45 minutes are not cooled, as follows:

[0102] S3. Add gum arabic and resistant dextrin to the white kidney bean-mulberry leaf composite extract, adjust the acidity and perform glycosylation embedding treatment, specifically: add gum arabic and resistant dextrin in a ratio of 1:3 to 100°C pure water, stir at high speed and heat for 60 minutes to obtain an embedding solution; then adjust the embedding solution to pH 5 with citric acid solution; finally, take 8.32g of the white kidney bean-mulberry leaf composite extract, and then take embedding solution according to 25% of the mass of the white kidney bean-mulberry leaf composite extract, that is, take 2.09g of embedding solution, mix the white kidney bean-mulberry leaf composite extract and the embedding solution, perform glycosylation embedding treatment, and after reacting for 20 minutes, obtain 10.41g of the white kidney bean-mulberry leaf composite extract having an activity retention value of 43.4% when heated and kept at 90°C for 30 minutes.

[0103] Comparative Example 11

[0104] Compared with Example 4, the difference is that konjac flour and mono- and diglycerol fatty acid esters are not added in step S4, which is specifically as follows:

[0105] S4. Mix the raw material liquid and the white kidney bean-mulberry leaf composite extract, specifically: prepare a high-amylose starch content of 8%, a fiber powder content of 6%, and a rice flour content of 83%, add pure water and mix evenly to obtain the raw material liquid; then add the raw material liquid into the white kidney bean-mulberry leaf composite extract with a content of 3%.

[0106] Test Example 1

[0107] Rice noodle sensory evaluation:

[0108] This study evaluated the color, smell, state, and cooking properties of rice noodles based on the scoring rules of DBS41008-2016 "Food Safety Local Standard Rice Noodles and Rice Vermicelli", formulated sensory quality evaluation scoring rules, and conducted a comprehensive evaluation of the low GI rice noodles prepared in Example 4 and Comparative Example 11.

[0109] It should be noted that the color, smell and state testing method is to take an appropriate amount of sample and place it in a white porcelain plate, observe its color and state under natural light, and smell its odor; the cooking test method is to take an appropriate amount of sample and cook it in boiling water for 5 to 10 minutes, and taste its taste.

[0110] An evaluation team consisting of 10 people related to food professions conducted sensory scoring on the rice noodles before and after cooking according to the sensory evaluation scoring criteria. The evaluation was repeated three times for each sample, and the average value of the score was used as the result of the quality sensory evaluation. The final calculation result was rounded to an integer.

[0111] The specific results are shown in the table below:

[0112]

[0113]

[0114] As shown in the above table, the comprehensive sensory score of the low GI rice noodles prepared with a white kidney bean-mulberry leaf composite extract prepared in Example 4 is higher than that of Comparative Example 11, indicating that the konjac gum and mono- and diglycerol fatty acid esters in Example 4 can greatly improve the taste, flavor, elasticity and rice flour loss rate of the low GI rice noodles, and improve the problems of the low GI rice noodles added with the white kidney bean-mulberry leaf composite extract.

[0115] Test Example 2

[0116] The GI values ​​of Examples 1-6 and ordinary rice noodles purchased from the market were tested according to WS / T 652-2019 "Method for Determination of Glycemic Index of Foods". There were 11 subjects with an average age of (27.7±5.4) years and a BMI of (21.2±2.0) kg / m 2 , the fasting blood glucose value was (5.08±0.42)mmol / L.

[0117] (1) Some definitions involved

[0118] Glycemic Index (GI): It is the property of carbohydrates in food, which refers to the ability of digestible carbohydrates in food to cause blood sugar to rise in the human body.

[0119] Increased AUC: The area under the curve above the fasting blood glucose level.

[0120] Standard deviation: It is the square root of the arithmetic mean of the squared deviations of the measured values ​​of the population from their mean, which reflects the degree of dispersion between individuals in the group.

[0121] Standard error: It is the ratio of the standard deviation of each measurement value to the square root of the number of participants (more than 10 data):

[0122]

[0123] Where s represents the standard deviation of the measurements, and n represents the number of subjects.

[0124] (2) Determination of GI value

[0125] Determination method: 3 trial tests, each test interval is 72h, and the rice noodle test is arranged between 2 glucose tests. Within 3 days before the test, the subjects have a regular work and rest schedule and a normal diet. Avoid high dietary fiber and high sugar foods for dinner on the day before the test, start fasting before 22:00, avoid strenuous exercise on the day of the test, and start the test after the subjects sit quietly for 10 minutes. First, measure the fasting blood glucose concentration twice. The eating time is required to be completed within 5 to 10 minutes. The time starts from the time of the first bite of food. Blood samples are collected at 15 minutes, 30 minutes, 45 minutes, 60 minutes, 90 minutes and 120 minutes after the meal. The back of the hand / elbow vein blood is collected by placing an indwelling needle. The blood collection site is kept consistent during the measurement cycle. The blood glucose concentration is determined by the hexokinase method. The blood glucose response curve is drawn with the measurement time (t) as the horizontal axis and the blood glucose concentration (ct) as the vertical axis. The area under the blood glucose response curve (IAUC) is calculated by the geometric method. The GI value of instant rice is calculated as follows:

[0126]

[0127]

[0128] Where: GI n -GI value derived by individual subjects; At-IAUC value of rice noodles; A ref -The average value of 2 glucose IAUC measurements from the same individual; n-the final number of subjects included; GI-GI value of rice noodles.

[0129] The following table shows the average GI values ​​of the low GI rice noodles prepared in Examples 1-6.

[0130]

[0131] The following table shows the average GI value after eating ordinary rice noodles:

[0132]

[0133]

[0134] As shown in the table above, the low GI rice noodles prepared with a white kidney bean-mulberry leaf composite extract prepared in Example 1-6 have a significantly lower GI value after consumption compared to ordinary rice noodles purchased on the market. Ordinary rice noodles usually have a higher starch content and a faster digestion rate, which generally makes their blood sugar levels higher. The low GI rice noodles prepared in Example 1-6, under the action of the white kidney bean-mulberry leaf composite extract, greatly slow down the digestion rate of carbohydrates, making the blood sugar level rise more steadily, thereby reducing blood sugar fluctuations.

[0135] Test Example 3

[0136] GI value test of Example 1 and Comparative Examples 1-11:

[0137] The test method and calculation formula are the same as those of Test Example 2.

[0138] The following table shows the average GI values ​​of rice noodles prepared from Example 1 and Comparative Examples 1-11.

[0139]

[0140]

[0141] As shown in the above table, the low GI rice noodles prepared with a white kidney bean-mulberry leaf composite extract prepared in Example 1 have a lower GI value than those of Comparative Examples 1-10, which not only proves that the low GI rice noodles prepared in the embodiment of the present invention greatly slow down the digestion rate of carbohydrates under the joint action of the white kidney bean-mulberry leaf composite extract, but also shows that different preparation process operations are also influencing factors causing GI value fluctuations.

[0142] It is worth mentioning that Comparative Example 6 did not perform glycosylation on the white kidney bean-mulberry leaf composite extract, and its GI value was the highest, indicating that the glycosylation and encapsulation treatment of the white kidney bean-mulberry leaf composite extract in the technical scheme of the present invention plays an important role in improving its heat resistance and stability, thereby retaining more α-amylase inhibitory activity, thereby ensuring that the prepared rice noodles have a lower GI value.

[0143] Test Example 4

[0144] α-amylase inhibitory activity and activity retention value test of Examples 1-6 and Comparative Examples 1-11:

[0145] The α-amylase inhibitory activity of the white kidney bean-mulberry leaf composite extract obtained in Examples 1-6 and Comparative Examples 1-11 was tested, and the test results were measured in terms of inhibitory activity (U / g); and the white kidney bean-mulberry leaf composite extract was heated and kept warm at 90° C. for 30 minutes to perform a heat resistance test, and the test results were measured in terms of activity retention value (%), as shown in the following table:

[0146] The following table shows the α-amylase inhibitory activity and activity retention value of Examples 1-6 and Comparative Examples 1-11

[0147]

[0148]

[0149] As can be seen from the above table, the α-amylase inhibitory activities of Examples 1-6 are all ≥6000U / g, among which the α-amylase inhibitory activity of Example 4 is the highest at 10962U / g, indicating that the higher the centrifugal speed, the higher the purity of the obtained white kidney bean-mulberry leaf composite extract, and the higher the corresponding α-amylase inhibitory activity; the activity retention value of Example 5 is the highest at 91.3%, indicating that the higher the content of gum arabic and resistant dextrin, the higher the activity retention value of the α-amylase inhibitor, and the stronger its heat resistance; and appropriately extending the glycosylation embedding time can also improve the activity retention value to a certain extent.

[0150] The α-amylase inhibitory activity and activity retention value of Comparative Example 1 are lower than those of Examples 1-6, indicating that the low GI rice noodles prepared by adding a single white kidney bean extract have poor starch digestion and absorption inhibition and heat resistance; the α-amylase inhibitory activity and activity retention value of Comparative Example 3 indicate that when water extraction of white kidney beans and mulberry leaves is performed, the purity of the white kidney bean-mulberry leaf composite extract is affected without secondary centrifugation, resulting in a decrease in α-amylase inhibitory activity; Comparative Examples 4-5 indicate that when concentrating the white kidney bean-mulberry leaf composite extract clear liquid, a suitable solid content range should be selected. The solid content of Comparative Example 4 is too low, which will affect the embedding treatment time and efficiency, and further affect the heat resistance of the white kidney bean-mulberry leaf composite extract, so the α-amylase inhibitory activity and activity retention value of Comparative Example 4 are both low. The solid content of Comparative Example 5 is too high, resulting in too high viscosity of the system, which is not conducive to the mixing and embedding of subsequent materials, resulting in lower α-amylase inhibitory activity and activity retention value of Comparative Example 5 than that of Comparative Example 4; Comparative Example 6 shows that glycosylation and embedding treatment of the white kidney bean-mulberry leaf composite extract is the key to maintaining a high α-amylase inhibitory activity and activity retention value. If glycosylation and embedding treatment are not performed, the α-amylase inhibitory activity and activity retention value of the white kidney bean-mulberry leaf composite extract will be greatly reduced; Comparative Examples 7-9 show that the higher the content of gum arabic and resistant dextrin as embedding liquid, the higher the activity retention value of the α-amylase inhibitor, and selecting an appropriate addition ratio is also beneficial to improving the α-amylase inhibitory activity and activity retention value; Comparative Example 10 shows that when preparing the embedding liquid, the operation of first heating and stirring and then cooling and stirring is beneficial to improving the subsequent embedding rate of the white kidney bean-mulberry leaf composite extract, thereby improving the α-amylase inhibitory activity and activity retention value.

[0151] Test Example 5

[0152] Test of dietary fiber content of rice noodles:

[0153] According to GB 5009.88-2023 "National Food Safety Standard Determination of Dietary Fiber in Food", the dietary fiber content of the low GI rice noodles prepared with a white kidney bean-mulberry leaf composite extract in Example 1-4 and ordinary rice noodles purchased from the market were determined.

[0154] The following table shows the dietary fiber content of Examples 1-4 and common rice noodles purchased from the market:

[0155]

[0156]

[0157] As can be seen from the above table, the low GI rice noodles prepared with a white kidney bean-mulberry leaf composite extract prepared in Example 1-4 effectively increased the dietary fiber content in the low GI rice noodles compared to ordinary rice noodles purchased on the market, which not only enhanced the sense of fullness, but also provided a higher dietary fiber nutritional value.

[0158] Note that the above embodiments are only preferred embodiments of the present invention and the technical principles used, but not limiting thereof. For those skilled in the art, various obvious changes, readjustments and substitutions can be made to the technical solutions described in the above embodiments according to the ideas of the embodiments of the present invention without departing from the protection scope of the present invention. Therefore, the contents of this specification should not be understood as limiting the present invention.

Claims

1. A method for preparing low GI rice noodles using a white kidney bean-mulberry leaf composite extract, characterized in that: include: The crushed white kidney beans and mulberry leaves are subjected to water extraction, and after separation, purification and concentration, a white kidney bean-mulberry leaf composite extract having an α-amylase inhibitory activity of ≥6000U / g is obtained; Adding gum arabic and resistant dextrin to the white kidney bean-mulberry leaf composite extract, adjusting the acidity and performing glycosylation embedding treatment to obtain a white kidney bean-mulberry leaf composite extract having an activity retention value of ≥80% when heated and kept at 90° C. for 30 minutes; Rice flour, high-amylose starch, fiber powder, konjac powder and mono- and di-glycerol fatty acid esters are uniformly mixed with the white kidney bean-mulberry leaf composite extract according to a certain proportion, and then low GI rice noodles containing the white kidney bean-mulberry leaf composite extract are obtained through moisture conditioning, steaming and extrusion molding.

2. The method for preparing low GI rice noodles using the white kidney bean-mulberry leaf composite extract according to claim 1, characterized in that: The crushed white kidney beans and mulberry leaves are subjected to water extraction, specifically: Step 1, crushing and sieving white kidney beans and mulberry leaves, and then mixing them in a mass ratio of 1:0.1-1; Step 2, adding 8 to 15 times the mass of pure water, soaking in a water bath at 45 to 65° C. for 1 to 3 hours, centrifuging at a speed of 3500 to 5000 r / min, and taking the supernatant; Step three, centrifuging the supernatant for a second time at a speed of 8000-16000 r / min to obtain a separated and purified white kidney bean-mulberry leaf composite extract supernatant.

3. The method for preparing low GI rice noodles using the white kidney bean-mulberry leaf composite extract according to claim 2, characterized in that: The concentration is specifically: The white kidney bean-mulberry leaf composite extract clear liquid is vacuum concentrated at -0.04 to -0.08 MPa to make its solid content 10% to 25%, and the α-amylase inhibition activity of the white kidney bean-mulberry leaf composite extract is ≥6000 U / g.

4. The method for preparing low GI rice noodles with the white kidney bean-mulberry leaf composite extract according to claim 1, characterized in that: The white kidney bean-mulberry leaf composite extract is added with gum arabic and resistant dextrin, and the acid is adjusted and then subjected to glycosylation embedding treatment, specifically: Step 1, adding gum arabic and resistant dextrin in a ratio of 1:0.5-3 into 70-100° C. pure water, stirring at high speed and heating for 30-60 minutes, and then cooling to 40-60° C. to obtain an embedding solution; Step 2, adjusting the embedding solution to a pH of 4.8 to 6.5 using a citric acid solution; Step three, taking 5-30% of the acid-adjusted embedding solution according to the mass of the white kidney bean-mulberry leaf composite extract, adding it to the white kidney bean-mulberry leaf composite extract, performing glycosylation embedding treatment, reacting for 10-35 minutes, and obtaining a white kidney bean-mulberry leaf composite extract having an activity retention value ≥80% when heated and kept at 90°C for 30 minutes.

5. The method for preparing low GI rice noodles with the white kidney bean-mulberry leaf composite extract according to claim 4, characterized in that: The concentration of the citric acid solution is 1 mol / L.

6. The method for preparing low GI rice noodles with the white kidney bean-mulberry leaf composite extract according to claim 2, characterized in that: The white kidney beans are crushed and sieved with a mesh number of 30 to 100 meshes; the mulberry leaves are crushed and sieved with a mesh number of 10 to 60 meshes.

7. The method for preparing low GI rice noodles with the white kidney bean-mulberry leaf composite extract according to claim 1, characterized in that: The high-amylose starch, fiber powder, konjac powder, rice flour and mono- and di-glycerol fatty acid esters are uniformly mixed with the white kidney bean-mulberry leaf composite extract according to a certain proportion, specifically: In percentage by mass: 5-10% of high-amylose starch, 3-10% of fiber powder, 0.5-3% of konjac powder, 0.01-0.05% of mono- and diglycerol fatty acid esters, 65-85% of rice flour, and 0.5-10% of the white kidney bean-mulberry leaf composite extract are prepared and then mixed evenly.

8. The method for preparing low GI rice noodles with the white kidney bean-mulberry leaf composite extract according to claim 1, characterized in that: The high-amylose starch is high-amylose corn starch; the fiber powder is any one or more combinations of sugarcane fiber, oat fiber, inulin, coconut powder and flaxseed powder.

9. A low GI rice noodle with white kidney bean-mulberry leaf composite extract, characterized in that: The low GI rice noodles prepared by the method for preparing low GI rice noodles using the white kidney bean-mulberry leaf composite extract according to any one of claims 1-8.

Images