Preparation method and application of mixed bean and coarse cereal premixed flour with low GI, low purine and high antioxidant activity

Abstract

The invention provides a preparation method and application of low-GI, low-purine and high-antioxidant-activity mixed bean and coarse cereal premixed flour, and belongs to the technical field of foods.The preparation method comprises the following steps that 1, low-GI screening is conducted, specifically, ideal components meeting requirements are screened out by measuring the eGI value; 2, screening with high antioxidant activity: screening out components meeting the requirements by measuring the antioxidant capacity; step 3, compounding the components which meet the requirements; in the step 1, the ideal components meeting the requirements are screened out by measuring the eGI value, namely the free glucose content, the amylose and amylopectin content, the fast digestible starch content, the slow digestible starch content and the resistant starch content of all the components are measured, and screening is conducted through an in-vitro simulated digestion experiment. The mixed bean and coarse cereal premixed flour has the beneficial effects that the GI value and the purine content of the mixed bean and coarse cereal premixed flour are reduced and the mixed bean and coarse cereal premixed flour has antioxidant activity by screening the mixed beans and the coarse cereal flour and adjusting the formula of the mixed bean and coarse cereal flour.

Description

Technical Field

[0001] The invention belongs to the technical field of food, and specifically relates to a preparation method and application of a low-GI, low-purine and high-antioxidant activity miscellaneous bean and miscellaneous grain premix powder. Background Art

[0002] In the prior art, the research on miscellaneous bean and miscellaneous grain premix powder mainly focuses on GI value and sensory evaluation, while there is less research on the total purine and antioxidant capacity of miscellaneous bean and miscellaneous grain premix powder and the products prepared therefrom.

[0003] Traditional premixed powders have complex ingredients and multiple functions. Consumers may be intolerant to one or more of the multiple functions, which makes the applicable population of premixed powders more demanding. In addition, due to the different dietary fiber, antioxidant capacity and polysaccharide content in various bean and grain powders, their compounding effects often vary. In the existing technology of low-GI bean and grain premixed powders, only the raw material powder with low GI value is selected, while the purine content in beans is ignored. Foods with high purine content are not suitable for diabetic patients with high uric acid.

[0004] In addition to the above two aspects, this application adds research on the antioxidant capacity and total purine content of miscellaneous bean and grain premix powder. By screening raw powder with GI value and antioxidant capacity, different proportions of raw powder and wheat flour are compounded to make miscellaneous bean and grain premix powder, and the effects of different raw powders on the fermentation characteristics, sensory evaluation, GI value, antioxidant capacity and total purine content of steamed bread are investigated. It is expected to prepare a miscellaneous bean and grain premix powder with low GI, low purine and high antioxidant activity, and apply it to specific staple food products. Summary of the invention

[0005] The present invention overcomes the shortcomings of the prior art and provides a method for preparing a low GI, low purine and high antioxidant activity miscellaneous bean and miscellaneous grain premix powder. The method achieves the technical effects of reducing the GI value and purine content of the miscellaneous bean and miscellaneous grain premix powder and having antioxidant activity by screening miscellaneous beans and miscellaneous grain powders and adjusting the formula of the miscellaneous bean and miscellaneous grain powders.

[0006] In order to solve the above technical problems, the present invention is achieved through the following technical solutions: A method for preparing a low GI, low purine and high antioxidant activity mixed bean and grain premix powder, the components of which include cooked soybean powder, cooked black bean powder, cooked white kidney bean powder and cooked wheat germ powder; The steps include: Step 1: Low GI screening: Screen out ideal ingredients that meet the requirements by measuring the eGI value; Step 2: Screening of high antioxidant activity: Screen out components that meet the requirements by measuring antioxidant capacity; Step 3: Compound the components that meet the requirements.

[0007] Furthermore, screening out ideal components that meet the requirements by measuring the eGI value in step 1 refers to screening by measuring the free glucose content, amylose and amylopectin content, rapidly digestible starch, slowly digestible starch and resistant starch content of each component, and conducting an in vitro simulated digestion experiment.

[0008] Furthermore, the method for determining the free glucose content is as follows: 1) Prepare 1 mg / mL glucose standard solution Prepare glucose standard solutions with concentrations of 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, and 0.7, make up to 2 mL with distilled water, add 2 mL DNS reagent respectively, heat in a boiling water bath for 6 min, cool to room temperature, and make up to 25 mL with distilled water; measure the absorbance at a wavelength of 540 nm, and draw a glucose standard curve with glucose concentration as the horizontal axis and absorbance as the vertical axis; Add 20 mL of distilled water and a rotor to 1 g of the tested grain powder, and gelatinize in a boiling water bath for 30 min; after cooling to 37°C, add 3 mL of invertase, and incubate in a 37°C water bath for 30 min. Take 0.5 mL of the supernatant and add 2 mL of anhydrous ethanol, centrifuge and take the supernatant, and use the DNS method to measure the glucose content.

[0009] Furthermore, The determination method of amylose and amylopectin is as follows: Determination of the measurement wavelength and reference wavelength of amylose and amylopectin 1) Drawing of amylose absorption curve: Accurately transfer 3 mL of the above amylose standard solution into a 25 mL volumetric flask, add 15 mL of distilled water, adjust the pH to about 3 with 1 mol / L glacial acetic acid solution, add 0.25 mL of iodine reagent, continue to add distilled water to dilute to the scale, and shake well; after standing for 15 min, use distilled water as a control, scan in the 400~1000 nm band with a double-beam spectrophotometer to draw the amylose absorption curve; 2) Drawing of amylopectin absorption curve: Accurately transfer 3 mL of the above amylopectin standard solution into a 25 mL volumetric flask, and draw the amylopectin absorption curve according to the operation method for drawing the amylose absorption curve; 3) Determination of the measurement wavelength and reference wavelength of amylose and amylopectin: The absorption curves of the two starch standard solutions are superimposed and plotted in the same coordinate system. Based on the principle that a certain solute in the solution absorbs at two wavelengths, the absorption difference between the two wavelengths is proportional to the concentration of the solute, the measurement wavelength and reference wavelength are determined by the isosbestic point elimination method; 4) Drawing of dual-wavelength amylose and amylopectin standard curves: Dual-wavelength amylose standard curve: Accurately pipette 0, 0.15, 0.45, 0.75, 1.05, 1.35, and 1.65 mL of the above amylose standard solution into 6 25 mL volumetric flasks, add 15 mL of distilled water, adjust the pH to about 3 with 1 mol / L glacial acetic acid solution, add 0.25 mL of iodine reagent, continue to add distilled water to dilute to the scale, and shake well; after standing for 15 min, use distilled water as a control, measure Aλ1 and Aλ2 at wavelengths λ1 and λ2, respectively, and draw a dual-wavelength standard curve with △A=Aλ2-Aλ1 as the ordinate, amylose mass as the abscissa, and absorbance as the ordinate; Dual-wavelength amylopectin standard curve: Accurately pipette 0, 1, 1.25, 1.5, 1.75, 2, and 2.25 mL of the above amylopectin standard solution into 6 25 mL volumetric flasks, add 15 mL of distilled water, adjust the pH to about 3 with 1 mol / L glacial acetic acid solution, add 0.25 mL of iodine reagent, continue to add distilled water to dilute to the scale, and shake well; after standing for 15 min, use distilled water as a control, measure Aλ3 and Aλ4 at wavelengths of λ3 and λ4, respectively, and use △A 支 =Aλ3-Aλ4 as the ordinate, the mass of amylopectin (mg) as the abscissa, and a dual-wavelength standard curve was drawn; Preparation and content determination of sample solution: weigh 1 g of raw powder and place it in a 50 mL centrifuge tube, add 5 mL of anhydrous ethanol, and vortex to wet the sample; add 10 mL of 1 mol / L sodium hydroxide solution, mix well, heat in a boiling water bath for 10 min, take out, cool to room temperature, add distilled water to dilute to the scale, shake well, and centrifuge; accurately transfer 1.0 mL of two supernatants each into a 25 mL volumetric flask (one as the sample blank control solution and the other as the sample determination solution), and operate according to the amylose standard curve operation method; wherein, 0.25 mL of iodine reagent is added to the sample determination solution, and no iodine reagent is added to the sample blank control solution, and both are diluted to the scale with distilled water and shake well; after standing for 15 min, use each sample blank solution as a control to determine the absorbance values ​​Aλ1, Aλ2, Aλ3 and Aλ4 at λ1, λ2, λ3, and λ4, respectively, and obtain △A 直 =Aλ2-Aλ1 and △A 支 =Aλ4-Aλ3; the starch mass corresponding to the corresponding △A value is obtained on the standard curves of amylose and amylopectin respectively, and the content of amylose and amylopectin in the raw powder sample can be calculated. The sum of the two is the total starch content; Step 3: Determination of the content of each component of starch Take 1 g of sample and add 10 mL of deionized water, gelatinize in boiling water for 30 min, balance the temperature in a water bath at 37°C, put in a rotor and 10 mL of pepsin-guar gum solution, shake in a water bath at 37°C for 30 min, add 5 mL of pH=5.2 sodium acetate buffer, shake the contents evenly, and balance in a water bath at 37°C for 3 min; add 5 mL of mixed enzyme, which is the zero time of incubation without interruption; take out the supernatant at 20 min and 120 min respectively, take 0.5 sample and put it in 2 mL of anhydrous ethanol solution, inactivate the enzyme in a boiling water bath, and terminate the reaction; measure the glucose content by DNS method; Step 4: In vitro simulated digestion experiment 1) Simulate oral digestion: weigh an appropriate amount of raw material powder, put it in a 100 mL conical flask, add 5 mL of α-amylase solution, and stir in a 37 ℃ water bath; 2) Simulated gastric digestion: After oral digestion, add 0.05 g pepsin (1:30,000) in 6 mL of 0.1 mol / L pH 6.9 PBS solution, adjust the pH to 1.5 with HCl, and shake in a constant temperature water bath (37 °C, 120 r / min) for 30 min; 3) After gastric digestion, add 10 mL of pH 6.9 PBS, adjust the pH to 6.9 with 0.1 mol / L NaOH solution, add 1 mL of mixed enzyme solution, dilute to 100 mL with distilled water, and then transfer to a 100 mL conical flask with a glass rod, and shake in a water bath at constant temperature (37 °C, 120 r / min) to simulate intestinal digestion; take 0.5 mL of sample solution into a test tube at 30, 60, 90, 120, 150, and 180 min, add 2 mL of anhydrous ethanol, centrifuge at 4000 r / min for 5 min, and take the supernatant; transfer 1 mL of the test solution into a test tube, add water to 2 mL, add 2 mL of DNS colorimetric solution, heat the test tube in a boiling water bath for 6 min, cool in ice water, and transfer to 25 mL volumetric flask, make up to volume and shake well, measure the absorbance at a wavelength of 540nm with a UV spectrophotometer, and record the data; refer to the glucose standard curve and calculate the reducing sugar content of the sample according to the regression equation.

[0010] Furthermore, screening out components that meet the requirements by measuring antioxidant capacity in step 2 refers to screening by measuring the total flavonoid content, total score content, DPPH scavenging ability, and ABTS scavenging ability in each component.

[0011] Furthermore, the method for determining the antioxidant capacity is as follows: 1) Preparation of sample extract: weigh 2.0 g sample powder into a 50 mL centrifuge tube, add 16 mL methanol-hydrochloric acid solution (1% HCl), extract at 24°C for 24 h, centrifuge at 4 000 r / min for 15 min, take the supernatant, and store in a dark place. This is the mother solution to be tested. 2) Determination of total phenol content: prepare 20 mg / mL gallic acid stock solution, and prepare 0, 0.4, 0.8, 1.2, 1.6, 2.4 mg / mL working solutions respectively; take 1.0 mL of working solution and react with 2.5 mL of Folin phenol reagent and 2.5 mL of 15% Na2CO3 solution, dilute to 10 mL with distilled water, mix evenly, place in 40℃ water for heating, take out after 30 min away from light, cool to room temperature, measure absorbance at 760 nm, and draw standard curve; replace the standard solution with 1 mL of sample solution, and calculate the total phenol content in the sample according to the above steps; 3) Determination of total flavonoids content: prepare 0.2 mg / mL rutin standard solution, prepare 0, 0.1, 0.2, 0.3, 0.4, 0.5, 1.0, 1.5, 2.0, 2.5 mL rutin standard solution in stoppered test tubes, add 1.0 mL of 2.5 g / 100 mL AlCl3 solution and 9.82 g / 100 mL potassium acetate solution, respectively, dilute to 25 mL with 30% ethanol, measure the absorbance at 415 nm within 30 min, and draw a standard curve; replace the rutin standard solution with 1 mL of sample solution, and calculate the total flavonoids content of the sample according to the above steps; 4) Determination of DPPH free radical scavenging ability: Take 0.5 mL of sample solution, add 2.5 mL of DPPH ethanol solution (0.1 mmol / L), shake slowly for 30 min in the dark, and measure the absorbance at 517 nm. The scavenging rate of DPPH free radicals is calculated as follows: DPPH free radical scavenging rate (%) = [1−[(A2 −A1) / A0 ]]×100 Wherein, A2 represents the absorbance after 0.5 mL sample solution is mixed with 2.5 mL DPPH ethanol solution; A1 represents the absorbance after 0.5 mL sample solution is mixed with 2.5 mL ethanol; A0 represents the absorbance after 2.5 mL DPPH solution is mixed with 0.5 mL ethanol; 5) ABTS +Free radical scavenging ability: Preparation of ABTS working solution: Take 5 mL of ABTS solution (7 mmol / L) and mix with 88 μL of potassium persulfate (K2S2O8) solution (40 mmol / L), place it at room temperature in the dark for 24 h, dilute it with 80% ethanol to an absorbance of about 0.7 at 734 nm, and make it into ABTS working solution; Determination method: Take 0.3 mL of sample solution and 2.7 mL of ABTS working solution, mix them thoroughly, react at room temperature in the dark for 10 min, and measure the absorbance at 734 nm; ABTS + The free radical scavenging rate was calculated according to the formula: ABTS + Free radical scavenging rate (%) = [ 1−[(A2 −A1 ) / A0] ]×100 Where A2 represents the absorbance after 0.3 mL of sample solution and 2.7 mL of ABTS working solution are mixed; A1 represents the absorbance after 0.3 mL of sample solution and 2.7 mL of 80% ethanol are mixed; A0 represents the absorbance after 2.7 mL of ABTS working solution and 0.3 mL of 80% ethanol are mixed.

[0012] Furthermore, in step 3, the components that meet the requirements are compounded, which means that 100 g of the miscellaneous beans and grains premix powder contains 1%-5% of cooked soybean powder, 1%-5% of cooked black bean powder, 2%-8% of cooked white kidney bean powder and 5%-20% of cooked wheat germ powder.

[0013] Furthermore, the eGI of cooked soybean flour is 19, the eGI of cooked black soybean flour is 32, and the eGI of cooked wheat germ flour is 29.

[0014] Furthermore, the total flavonoid contents of the cooked soybean powder, cooked black soybean powder, cooked white kidney bean powder and cooked wheat germ powder are 0.015, 0.015, 0.013 and 0.014 mg / g, the total phenol contents are 2.07, 1.39, 0.83 and 0.97 mg / g, and the DPPH scavenging abilities are 76.52%, 87.7%, 24.78%, 91.05%, ABTS + The free radical scavenging abilities were 99.22%, 98.77%, 73.85% and 98.83%; Furthermore, the physical and chemical properties, dough fermentation characteristics and edible quality of the mixed bean and grain powder were studied through single-factor experiments and orthogonal experiments, and the proportion of the components of each bean and grain was adjusted to facilitate the uniform mixing of the raw material powders and the function of each raw material, which helps to reduce the GI value and purine content of the mixed bean and grain powder and improve its antioxidant capacity.

[0015] The invention discloses an application of a low GI, low purine and high antioxidant activity mixed bean and grain premix powder. The low GI, low purine and high antioxidant activity mixed bean and grain premix powder is applied in diabetic food, which can slow down the increase of blood sugar level, increase antioxidant capacity, reduce insulin sensitivity, and help maintain a good blood sugar level. The mixed bean and grain premix powder is more suitable for people with diabetes and high uric acid.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention obtains the optimal addition amount of the miscellaneous bean and miscellaneous grains flour through single factor experiments and orthogonal experiments, and comprehensively evaluates the quality of the miscellaneous bean and miscellaneous grains flour based on the physicochemical properties, tensile properties, powder properties, sensory evaluation, total purine content, GI value and antioxidant capacity of the miscellaneous bean and miscellaneous grains steamed bread.

[0017] The present invention takes into account the problem of purine content in beans and optimizes the compounding ratio of miscellaneous grains and bean powders to maintain the total purine content of the miscellaneous bean and miscellaneous grain premix powder at a relatively low level. The prepared miscellaneous bean and miscellaneous grain powder is suitable for consumption by patients with diabetes and gout comorbidities, and has relatively high economic benefits and broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are used to provide a further understanding of the present invention and are used together with the embodiments of the present invention to explain the present invention, but do not constitute a limitation of the present invention. In the accompanying drawings: Figure 1 is the glucose standard curve; Figure 2 It is the free glucose content in miscellaneous beans and grains; Figure 3 is the amylose standard curve; Figure 4 It is the content of amylose in miscellaneous bean and grain powder; Figure 5 is the pullulan standard curve; Figure 6 It is the amylopectin content in miscellaneous bean and grain flour; Figure 7 It is the hydrolysis curve of miscellaneous grain and bean powder; Figure 8 It is the eGI of mixed bean and grain flour; Fig. 9 is the gallic acid standard curve; Fig.10 is the total phenol content in mixed bean and grain flour; Fig.11 is the rutin standard curve; Fig.12 is the total flavonoid content in mixed bean and grain powder; Fig.13 It is the DPPH free radical scavenging ability of miscellaneous bean and grain powder; Fig.14 It is the ABTS+ free radical scavenging ability of mixed bean and grain powder. DETAILED DESCRIPTION

[0019] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0020] In addition to studying the above two aspects, the present application adds research on the antioxidant capacity and total purine content of miscellaneous bean and miscellaneous grain premix powder. By screening raw powders with GI values ​​and antioxidant capacity, the raw powders in different proportions are compounded with wheat flour to make miscellaneous bean and miscellaneous grain premix powders, and the effects of different raw powders on the fermentation characteristics, sensory evaluation, GI value, antioxidant capacity and total purine content of steamed bread are investigated, in order to prepare a miscellaneous bean and miscellaneous grain premix powder with low GI, low purine and high antioxidant activity, and apply it to specific staple food products.

[0021] Specifically, in the present application, in a method for preparing a low GI, low purine and high antioxidant activity miscellaneous bean and miscellaneous grain premix powder, the components used include cooked soybean powder, cooked black bean powder, cooked white kidney bean powder and cooked wheat germ powder; The steps include: Step 1: Low GI screening: Screen out ideal ingredients that meet the requirements by measuring the eGI value; Step 2: Screening of high antioxidant activity: Screen out components that meet the requirements by measuring antioxidant capacity; Step 3: Compound the components that meet the requirements.

[0022] That is, the overall idea is to screen out suitable components and then compound them.

[0023] like Figures 1 to 14 As shown, wherein the step 1 of screening out ideal components that meet the requirements by measuring the eGI value refers to screening by measuring the free glucose content, amylose and amylopectin content, rapidly digestible starch, slowly digestible starch and resistant starch content of various components, and performing in vitro simulated digestion experiments.

[0024] Preferably, the eGI of cooked soybean powder is 19, the eGI of cooked black soybean powder is 32, and the eGI of cooked wheat germ powder is 29.

[0025] The method for determining the free glucose content is as follows: 1) Prepare 1 mg / mL glucose standard solution Prepare glucose standard solutions with concentrations of 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, and 0.7, make up to 2 mL with distilled water, add 2 mL DNS reagent respectively, heat in a boiling water bath for 6 min, cool to room temperature, and make up to 25 mL with distilled water; measure the absorbance at a wavelength of 540 nm, and draw a glucose standard curve with glucose concentration as the horizontal axis and absorbance as the vertical axis; Add 20 mL of distilled water and a rotor to 1 g of the tested grain powder, and gelatinize in a boiling water bath for 30 min; after cooling to 37°C, add 3 mL of invertase, and incubate in a 37°C water bath for 30 min. Take 0.5 mL of the supernatant and add 2 mL of anhydrous ethanol, centrifuge and take the supernatant, and use the DNS method to measure the glucose content.

[0026] The determination method of amylose and amylopectin is as follows: Determination of the measurement wavelength and reference wavelength of amylose and amylopectin 1) Drawing of amylose absorption curve: Accurately transfer 3 mL of the above amylose standard solution into a 25 mL volumetric flask, add 15 mL of distilled water, adjust the pH to about 3 with 1 mol / L glacial acetic acid solution, add 0.25 mL of iodine reagent, continue to add distilled water to dilute to the scale, and shake well; after standing for 15 min, use distilled water as a control, scan in the 400~1000 nm band with a double-beam spectrophotometer to draw the amylose absorption curve; 2) Drawing of amylopectin absorption curve: Accurately transfer 3 mL of the above amylopectin standard solution into a 25 mL volumetric flask, and draw the amylopectin absorption curve according to the operation method for drawing the amylose absorption curve; 3) Determination of the measurement wavelength and reference wavelength of amylose and amylopectin: The absorption curves of the two starch standard solutions are superimposed and plotted in the same coordinate system. Based on the principle that a certain solute in the solution absorbs at two wavelengths, the absorption difference between the two wavelengths is proportional to the concentration of the solute, the measurement wavelength and reference wavelength are determined by the isosbestic point elimination method; 4) Drawing of dual-wavelength amylose and amylopectin standard curves: Dual-wavelength amylose standard curve: Accurately pipette 0, 0.15, 0.45, 0.75, 1.05, 1.35, and 1.65 mL of the above amylose standard solution into 6 25 mL volumetric flasks, add 15 mL of distilled water, adjust the pH to about 3 with 1 mol / L glacial acetic acid solution, add 0.25 mL of iodine reagent, continue to add distilled water to dilute to the scale, and shake well; after standing for 15 min, use distilled water as a control, measure Aλ1 and Aλ2 at wavelengths λ1 and λ2, respectively, and draw a dual-wavelength standard curve with △A=Aλ2-Aλ1 as the ordinate, amylose mass as the abscissa, and absorbance as the ordinate; Dual-wavelength amylopectin standard curve: Accurately pipette 0, 1, 1.25, 1.5, 1.75, 2, and 2.25 mL of the above amylopectin standard solution into 6 25 mL volumetric flasks, add 15 mL of distilled water, adjust the pH to about 3 with 1 mol / L glacial acetic acid solution, add 0.25 mL of iodine reagent, continue to add distilled water to dilute to the scale, and shake well; after standing for 15 min, use distilled water as a control, measure Aλ3 and Aλ4 at wavelengths of λ3 and λ4, respectively, and use △A 支 =Aλ3-Aλ4 as the ordinate, the mass of amylopectin (mg) as the abscissa, and a dual-wavelength standard curve was drawn; Preparation and content determination of sample solution: weigh 1 g of raw powder and place it in a 50 mL centrifuge tube, add 5 mL of anhydrous ethanol, and vortex to wet the sample; add 10 mL of 1 mol / L sodium hydroxide solution, mix well, heat in a boiling water bath for 10 min, take out, cool to room temperature, add distilled water to dilute to the scale, shake well, and centrifuge; accurately transfer 1.0 mL of two supernatants each into a 25 mL volumetric flask (one as the sample blank control solution and the other as the sample determination solution), and operate according to the amylose standard curve operation method; wherein, 0.25 mL of iodine reagent is added to the sample determination solution, and no iodine reagent is added to the sample blank control solution, and both are diluted to the scale with distilled water and shake well; after standing for 15 min, use each sample blank solution as a control to determine the absorbance values ​​Aλ1, Aλ2, Aλ3 and Aλ4 at λ1, λ2, λ3, and λ4, respectively, and obtain △A 直 =Aλ2-Aλ1 and △A 支 =Aλ4-Aλ3; the starch mass corresponding to the corresponding △A value is obtained on the standard curves of amylose and amylopectin respectively, and the content of amylose and amylopectin in the raw powder sample can be calculated. The sum of the two is the total starch content; Step 3: Determination of the content of each component of starch Take 1 g of sample and add 10 mL of deionized water, gelatinize in boiling water for 30 min, balance the temperature in a water bath at 37°C, put in a rotor and 10 mL of pepsin-guar gum solution, shake in a water bath at 37°C for 30 min, add 5 mL of pH=5.2 sodium acetate buffer, shake the contents evenly, and balance in a water bath at 37°C for 3 min; add 5 mL of mixed enzyme, which is the zero time of incubation without interruption; take out the supernatant at 20 min and 120 min respectively, take 0.5 sample and put it in 2 mL of anhydrous ethanol solution, inactivate the enzyme in a boiling water bath, and terminate the reaction; measure the glucose content by DNS method; Step 4: In vitro simulated digestion experiment 1) Simulate oral digestion: weigh an appropriate amount of raw material powder, put it in a 100 mL conical flask, add 5 mL of α-amylase solution, and stir in a 37 ℃ water bath; 2) Simulated gastric digestion: After oral digestion, add 0.05 g pepsin (1:30,000) in 6 mL of 0.1 mol / L pH 6.9 PBS solution, adjust the pH to 1.5 with HCl, and shake in a constant temperature water bath (37 °C, 120 r / min) for 30 min; 3) After gastric digestion, add 10 mL of pH 6.9 PBS, adjust the pH to 6.9 with 0.1 mol / L NaOH solution, add 1 mL of mixed enzyme solution, dilute to 100 mL with distilled water, and then transfer to a 100 mL conical flask with a glass rod, and shake in a water bath at constant temperature (37 °C, 120 r / min) to simulate intestinal digestion; take 0.5 mL of sample solution into a test tube at 30, 60, 90, 120, 150, and 180 min, add 2 mL of anhydrous ethanol, centrifuge at 4000 r / min for 5 min, and take the supernatant; transfer 1 mL of the test solution into a test tube, add water to 2 mL, add 2 mL of DNS colorimetric solution, heat the test tube in a boiling water bath for 6 min, cool in ice water, and transfer to 25 mL volumetric flask, make up to volume and shake well, measure the absorbance at a wavelength of 540nm with a UV spectrophotometer, and record the data; refer to the glucose standard curve and calculate the reducing sugar content of the sample according to the regression equation.

[0027] Screening out components that meet the requirements by measuring antioxidant capacity in step 2 refers to screening by measuring the total flavonoid content, total score content, DPPH scavenging capacity, and ABTS scavenging capacity in each component.

[0028] The specific method for determining the antioxidant capacity is as follows: 1) Preparation of sample extract: weigh 2.0 g sample powder into a 50 mL centrifuge tube, add 16 mL methanol-hydrochloric acid solution (1% HCl), extract at 24°C for 24 h, centrifuge at 4 000 r / min for 15 min, take the supernatant, and store in a dark place. This is the mother solution to be tested. 2) Determination of total phenol content: prepare 20 mg / mL gallic acid stock solution, and prepare 0, 0.4, 0.8, 1.2, 1.6, 2.4 mg / mL working solutions respectively; take 1.0 mL of working solution and react with 2.5 mL of Folin phenol reagent and 2.5 mL of 15% Na2CO3 solution, dilute to 10 mL with distilled water, mix evenly, place in 40℃ water for heating, take out after 30 min away from light, cool to room temperature, measure absorbance at 760 nm, and draw standard curve; replace the standard solution with 1 mL of sample solution, and calculate the total phenol content in the sample according to the above steps; 3) Determination of total flavonoids content: prepare 0.2 mg / mL rutin standard solution, prepare 0, 0.1, 0.2, 0.3, 0.4, 0.5, 1.0, 1.5, 2.0, 2.5 mL rutin standard solution in stoppered test tubes, add 1.0 mL of 2.5 g / 100 mL AlCl3 solution and 9.82 g / 100 mL potassium acetate solution, respectively, dilute to 25 mL with 30% ethanol, measure the absorbance at 415 nm within 30 min, and draw a standard curve; replace the rutin standard solution with 1 mL of sample solution, and calculate the total flavonoids content of the sample according to the above steps; 4) Determination of DPPH free radical scavenging ability: Take 0.5 mL of sample solution, add 2.5 mL of DPPH ethanol solution (0.1 mmol / L), shake slowly for 30 min in the dark, and measure the absorbance at 517 nm. The scavenging rate of DPPH free radicals is calculated as follows: DPPH free radical scavenging rate (%) = [1−[(A2 −A1) / A0 ]]×100 Wherein, A2 represents the absorbance after 0.5 mL sample solution is mixed with 2.5 mL DPPH ethanol solution; A1 represents the absorbance after 0.5 mL sample solution is mixed with 2.5 mL ethanol; A0 represents the absorbance after 2.5 mL DPPH solution is mixed with 0.5 mL ethanol; 5) ABTS +Free radical scavenging ability: Preparation of ABTS working solution: Take 5 mL of ABTS solution (7 mmol / L) and mix with 88 μL of potassium persulfate (K2S2O8) solution (40 mmol / L), place it at room temperature in the dark for 24 h, dilute it with 80% ethanol to an absorbance of about 0.7 at 734 nm, and make it into ABTS working solution; Determination method: Take 0.3 mL of sample solution and 2.7 mL of ABTS working solution, mix them thoroughly, react at room temperature in the dark for 10 min, and measure the absorbance at 734 nm; ABTS + The free radical scavenging rate was calculated according to the formula: ABTS + Free radical scavenging rate (%) = [ 1−[(A2 −A1 ) / A0] ]×100 Where A2 represents the absorbance after 0.3 mL of sample solution and 2.7 mL of ABTS working solution are mixed; A1 represents the absorbance after 0.3 mL of sample solution and 2.7 mL of 80% ethanol are mixed; A0 represents the absorbance after 2.7 mL of ABTS working solution and 0.3 mL of 80% ethanol are mixed.

[0029] Among them, in step 3, the components that meet the requirements are compounded, which means that 100 g of the miscellaneous beans and grains premix powder contains 1%-5% of cooked soybean powder, 1%-5% of cooked black bean powder, 2%-8% of cooked white kidney bean powder and 5%-20% of cooked wheat germ powder.

[0030] Preferably, the total flavonoids content of cooked soybean powder, cooked black soybean powder, cooked white kidney bean powder and cooked wheat germ powder is 0.015, 0.015, 0.013 and 0.014 mg / g, the total phenol content is 2.07, 1.39, 0.83 and 0.97 mg / g, and the DPPH scavenging capacity is 76.52%, 87.7%, 24.78%, 91.05%, ABTS + The free radical scavenging abilities were 99.22%, 98.77%, 73.85% and 98.83%; Furthermore, in the present application, the physical and chemical properties, dough fermentation characteristics and edible quality of the mixed bean and grain powder are studied through single-factor experiments and orthogonal experiments, and the proportions of the components of each mixed bean and grain powder are adjusted to facilitate the uniform mixing of the raw material powders, facilitate the function of each raw material, and help reduce the GI value and purine content of the mixed bean and grain powder and improve its antioxidant capacity.

[0031] The present application also proposes the use of a low GI, low purine and high antioxidant activity premixed bean and grain powder. The use of the above-mentioned low GI, low purine and antioxidant activity premixed bean and grain powder in diabetic food can slow down the increase in blood sugar level and increase antioxidant capacity, reduce insulin sensitivity, and help maintain a better blood sugar level. It is more suitable for people with diabetes and high uric acid.

[0032] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. However, any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a low GI, low purine and high antioxidant activity mixed bean and grain premix powder, characterized in that: The ingredients include cooked soybean powder, cooked black soybean powder, cooked white kidney bean powder and cooked wheat germ powder; The steps include: Step 1: Low GI screening: Screen out ideal ingredients that meet the requirements by measuring the eGI value; Step 2: Screening of high antioxidant activity: Screen out components that meet the requirements by measuring antioxidant capacity; Step 3: Compound the components that meet the requirements.

2. The method for preparing a low GI, low purine and high antioxidant activity miscellaneous bean and miscellaneous grain premix according to claim 1, characterized in that: Screening out ideal components that meet the requirements by measuring the eGI value in step 1 refers to screening by measuring the free glucose content, amylose and amylopectin content, rapidly digestible starch, slowly digestible starch and resistant starch content of each component, and conducting an in vitro simulated digestion experiment.

3. The method for preparing a low GI, low purine and high antioxidant activity miscellaneous bean and miscellaneous grain premix according to claim 2, characterized in that: The method for determining the free glucose content is as follows: 1) Prepare 1 mg / mL glucose standard solution Prepare glucose standard solutions with concentrations of 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, and 0.7, make up to 2 mL with distilled water, add 2 mL DNS reagent respectively, heat in a boiling water bath for 6 min, cool to room temperature, and make up to 25 mL with distilled water; measure the absorbance at a wavelength of 540 nm, and draw a glucose standard curve with glucose concentration as the horizontal axis and absorbance as the vertical axis; Add 20 mL of distilled water and a rotor to 1 g of the tested grain powder, and gelatinize in a boiling water bath for 30 min; after cooling to 37°C, add 3 mL of invertase, and incubate in a 37°C water bath for 30 min. Take 0.5 mL of the supernatant and add 2 mL of anhydrous ethanol, centrifuge and take the supernatant, and use the DNS method to measure the glucose content.

4. The method for preparing a low GI, low purine and high antioxidant activity miscellaneous bean and miscellaneous grain premix according to claim 2, characterized in that: The determination method of amylose and amylopectin is as follows: Determination of the measurement wavelength and reference wavelength of amylose and amylopectin 1) Drawing of amylose absorption curve: Accurately transfer 3 mL of the above amylose standard solution into a 25 mL volumetric flask, add 15 mL of distilled water, adjust the pH to about 3 with 1 mol / L glacial acetic acid solution, add 0.25 mL of iodine reagent, continue to add distilled water to dilute to the scale, and shake well; after standing for 15 min, use distilled water as a control, scan in the 400~1000 nm band with a double-beam spectrophotometer to draw the amylose absorption curve; 2) Drawing of amylopectin absorption curve: Accurately transfer 3 mL of the above amylopectin standard solution into a 25 mL volumetric flask, and draw the amylopectin absorption curve according to the operation method for drawing the amylose absorption curve; 3) Determination of the measurement wavelength and reference wavelength of amylose and amylopectin: The absorption curves of the two starch standard solutions are superimposed and plotted in the same coordinate system. Based on the principle that a certain solute in the solution absorbs at two wavelengths, the absorption difference between the two wavelengths is proportional to the concentration of the solute, the measurement wavelength and reference wavelength are determined by the isosbestic point elimination method; 4) Drawing of dual-wavelength amylose and amylopectin standard curves: Dual-wavelength amylose standard curve: Accurately pipette 0, 0.15, 0.45, 0.75, 1.05, 1.35, and 1.65 mL of the above amylose standard solution into 6 25 mL volumetric flasks, add 15 mL of distilled water, adjust the pH to about 3 with 1 mol / L glacial acetic acid solution, add 0.25 mL of iodine reagent, continue to add distilled water to dilute to the scale, and shake well; after standing for 15 min, use distilled water as a control, measure Aλ1 and Aλ2 at wavelengths of λ1 and λ2, respectively, and draw a dual-wavelength standard curve with △A=Aλ2-Aλ1 as the ordinate, amylose mass as the abscissa, and absorbance as the ordinate; Dual-wavelength amylopectin standard curve: Accurately pipette 0, 1, 1.25, 1.5, 1.75, 2, and 2.25 mL of the above amylopectin standard solution into 6 25 mL volumetric flasks, add 15 mL of distilled water, adjust the pH to about 3 with 1 mol / L glacial acetic acid solution, add 0.25 mL of iodine reagent, continue to add distilled water to dilute to the scale, and shake well; after standing for 15 min, use distilled water as a control, measure Aλ3 and Aλ4 at wavelengths of λ3 and λ4, respectively, and use △A 支 =Aλ3-Aλ4 is the ordinate, the mass of amylopectin is the abscissa, and a dual-wavelength standard curve is drawn; Preparation and content determination of sample solution: weigh 1 g of raw powder and place it in a 50 mL centrifuge tube, add 5 mL of anhydrous ethanol, and vortex to wet the sample; add 10 mL of 1 mol / L sodium hydroxide solution, mix well, heat in a boiling water bath for 10 min, take it out, cool to room temperature, add distilled water to dilute to the scale, shake well, and centrifuge; accurately transfer two portions of supernatant, 1.0 mL each, and place them in a 25 mL volumetric flask, and operate according to the standard curve operation method of amylose; wherein, 0.25 mL of iodine reagent is added to the sample determination solution, and no iodine reagent is added to the sample blank control solution, and both are diluted to the scale with distilled water and shake well; after standing for 15 min, use each sample blank solution as a control to measure the absorbance values ​​Aλ1, Aλ2, Aλ3 and Aλ4 at λ1, λ2, λ3, and λ4, respectively, and obtain △A 直 =Aλ2-Aλ1 and △A 支 =Aλ4-Aλ3; the starch mass corresponding to the corresponding △A value is obtained on the standard curves of amylose and amylopectin respectively, and the content of amylose and amylopectin in the raw powder sample can be calculated. The sum of the two is the total starch content; Step 3: Determination of the content of each component of starch Take 1 g of sample and add 10 mL of deionized water, gelatinize in boiling water for 30 min, balance the temperature in a water bath at 37°C, put in a rotor and 10 mL of pepsin-guar gum solution, shake in a water bath at 37°C for 30 min, add 5 mL of pH=5.2 sodium acetate buffer, shake the contents evenly, and balance in a water bath at 37°C for 3 min; add 5 mL of mixed enzyme, which is the zero time of incubation without interruption; take out the supernatant at 20 min and 120 min respectively, take 0.5 sample and put it in 2 mL of anhydrous ethanol solution, inactivate the enzyme in a boiling water bath, and terminate the reaction; measure the glucose content by DNS method; Step 4: In vitro simulated digestion experiment 1) Simulate oral digestion: weigh an appropriate amount of raw material powder, put it in a 100 mL conical flask, add 5 mL of α-amylase solution, and stir in a 37 ℃ water bath; 2) Simulated gastric digestion: After oral digestion, add 0.05 g pepsin (1:30000) in 6 mL of 0.1 mol / L pH 6.9 PBS solution, adjust the pH to 1.5 with HCl, and shake in a constant temperature water bath for 30 min; 3) After gastric digestion, add 10 mL of pH 6.9 PBS, adjust the pH to 6.9 with 0.1 mol / L NaOH solution, add 1 mL of mixed enzyme solution, dilute to 100 mL with distilled water, and then transfer to a 100 mL conical flask with a glass rod to simulate intestinal digestion in a water bath with constant temperature shaking; take 0.5 mL of sample solution in a test tube at 30, 60, 90, 120, 150, and 180 min, add 2 mL of anhydrous ethanol, centrifuge at 4000 r / min for 5 min, and take the supernatant; transfer 1 mL of the test solution into a test tube, add water to 2 mL, add 2 mL of DNS colorimetric solution, heat the test tube in a boiling water bath for 6 min, cool it in ice water, transfer it to a 25 mL volumetric flask, dilute to volume and shake well, measure the absorbance at a wavelength of 540 nm with a UV spectrophotometer, and record the data; refer to the glucose standard curve and calculate the reducing sugar content of the sample according to the regression equation.

5. The method for preparing a low GI, low purine and high antioxidant activity miscellaneous bean and miscellaneous grain premix according to claim 2, characterized in that: Screening out components that meet the requirements by measuring antioxidant capacity in step 2 refers to screening by measuring the total flavonoid content, total score content, DPPH scavenging capacity, and ABTS scavenging capacity in each component.

6. The method for preparing a low GI, low purine and high antioxidant activity miscellaneous bean and miscellaneous grain premix according to claim 5, characterized in that: The specific method for determining the antioxidant capacity is as follows: 1) Preparation of sample extract: weigh 2.0 g sample powder into a 50 mL centrifuge tube, add 16 mL methanol-hydrochloric acid solution, extract at 24°C for 24 h, centrifuge at 4 000 r / min for 15 min, take the supernatant, and store in a dark place. This is the mother solution to be tested. 2) Determination of total phenol content: prepare 20 mg / mL gallic acid stock solution, and prepare working solutions of 0, 0.4, 0.8, 1.2, 1.6, and 2.4 mg / mL respectively; take 1.0 mL of working solution and react with 2.5 mL of Folin phenol reagent and 2.5 mL of 15% Na2CO3 solution, dilute to 10 mL with distilled water, mix evenly, place in 40℃ water for heating, take out after 30 min away from light, cool to room temperature, measure absorbance at 760 nm, and draw standard curve; replace the standard solution with 1 mL of sample solution, and calculate the total phenol content in the sample according to the above steps; 3) Determination of total flavonoids content: prepare 0.2 mg / mL rutin standard solution, prepare 0, 0.1, 0.2, 0.3, 0.4, 0.5, 1.0, 1.5, 2.0, 2.5 mL rutin standard solution in stoppered test tubes, add 1.0 mL of 2.5 g / 100 mL AlCl3 solution and 9.82 g / 100 mL potassium acetate solution, respectively, dilute to 25 mL with 30% ethanol, measure the absorbance at 415 nm within 30 min, and draw a standard curve; replace the rutin standard solution with 1 mL of sample solution, and calculate the total flavonoids content of the sample according to the above steps; 4) Determination of DPPH free radical scavenging ability: Take 0.5 mL of sample solution, add 2.5 mL of DPPH ethanol solution (0.1 mmol / L), shake slowly for 30 min in the dark, and measure the absorbance at 517 nm. The scavenging rate of DPPH free radicals is calculated as follows: DPPH free radical scavenging rate (%) = [1−[(A2−A1) / A0 ]]×100 Wherein, A2 represents the absorbance after 0.5 mL sample solution is mixed with 2.5 mL DPPH ethanol solution; A1 represents the absorbance after 0.5 mL sample solution is mixed with 2.5 mL ethanol; A0 represents the absorbance after 2.5 mL DPPH solution is mixed with 0.5 mL ethanol; 5) ABTS + Free radical scavenging ability: Preparation of ABTS working solution: Take 5 mL of ABTS solution (7 mmol / L) and mix with 88 μL of potassium persulfate (K2S2O8) solution (40 mmol / L), place at room temperature in the dark for 24 h, dilute with 80% ethanol to an absorbance of about 0.7 at 734 nm to become ABTS working solution; Determination method: Take 0.3 mL of sample solution and 2.7 mL of ABTS working solution and mix thoroughly, react at room temperature in the dark for 10 min, and measure the absorbance at 734 nm; ABTS + The free radical scavenging rate was calculated according to the formula: ABTS + Free radical scavenging rate (%) = [ 1−[(A2−A1 ) / A0] ]×100 Where A2 represents the absorbance after 0.3 mL of sample solution and 2.7 mL of ABTS working solution are mixed; A1 represents the absorbance after 0.3 mL of sample solution and 2.7 mL of 80% ethanol are mixed; A0 represents the absorbance after 2.7 mL of ABTS working solution and 0.3 mL of 80% ethanol are mixed.

7. The method for preparing a low GI, low purine and high antioxidant activity miscellaneous bean and miscellaneous grain premix according to claim 2, characterized in that: In step 3, the components that meet the requirements are compounded, which refers to 1%-5% of cooked soybean powder, 1%-5% of cooked black bean powder, 2%-8% of cooked white kidney bean powder and 5%-20% of cooked wheat germ powder in 100 g of miscellaneous beans and grains premix.

8. The method for preparing a low GI, low purine and high antioxidant activity miscellaneous bean and miscellaneous grain premix according to claim 2, characterized in that: The eGI of cooked soybean flour is 19, the eGI of cooked black soybean flour is 32, and the eGI of cooked wheat germ flour is 29.

9. The method for preparing a low GI, low purine and high antioxidant activity miscellaneous bean and miscellaneous grain premix according to claim 5, characterized in that: The total flavonoid contents of the cooked soybean powder, cooked black soybean powder, cooked white kidney bean powder and cooked wheat germ powder are 0.015, 0.015, 0.013 and 0.014 mg / g, the total phenol contents are 2.07, 1.39, 0.83 and 0.97 mg / g, and the DPPH scavenging abilities are 76.52%, 87.7%, 24.78%, 91.05%, ABTS + The free radical scavenging abilities were 99.22%, 98.77%, 73.85% and 98.83%; Furthermore, the physical and chemical properties, dough fermentation characteristics and edible quality of the mixed bean and grain powder were studied through single-factor experiments and orthogonal experiments, and the proportion of the components of each bean and grain was adjusted to facilitate the uniform mixing of the raw material powders and the function of each raw material, which helps to reduce the GI value and purine content of the mixed bean and grain powder and improve its antioxidant capacity.

10. An application of low GI, low purine and high antioxidant activity mixed bean and grain premix powder, characterized in that: Applying the above-mentioned low GI, low purine and antioxidant-active mixed bean and grain premix powder in diabetic food can slow down the increase in blood sugar level, increase antioxidant capacity, reduce insulin sensitivity, and help maintain a better blood sugar level. It is more suitable for people with diabetes and high uric acid.

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