Preparation of insoluble dietary fiber from bean dregs and application thereof in crisp biscuits
By using high-speed homogenization and coarse Neurospora fermentation to modify the insoluble dietary fiber in soybean residue, the problems of high glycemic index and low resource utilization of soybean residue in shortbread biscuits have been solved, achieving health improvement of shortbread biscuits and efficient utilization of resources.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NORTHEAST AGRICULTURAL UNIVERSITY
- Filing Date
- 2026-04-02
- Publication Date
- 2026-06-05
AI Technical Summary
Traditional shortbread cookies have a high glycemic index, and the modification effect of insoluble dietary fiber in soybean residue is not good, resulting in low resource utilization and a lack of research on multi-method combined modification.
A method for modifying insoluble dietary fiber in soybean residue using high-speed homogenization combined with fermentation by Neurospora crassa includes enzymatic hydrolysis and fermentation steps, pH adjustment, high-speed homogenization and high-pressure sterilization, inoculation with Neurospora crassa for fermentation, and freeze-drying before application in shortbread biscuits.
It significantly reduces the glycemic index of shortbread biscuits, increases the SDF content and particle size of insoluble dietary fiber, enhances its adsorption capacity, improves the texture and taste of biscuits, and achieves efficient utilization of resources.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of by-product deep processing technology, specifically relating to the preparation of insoluble dietary fiber from soybean residue and its application in shortbread biscuits. Background Technology
[0002] Shortbread cookies are loved by consumers of all ages for their crumbly and delicate texture. However, traditional shortbread cookies are mainly made of low-gluten flour, high proportion of fat and sugar, and generally have a high glycemic index (GI). Long-term consumption can easily lead to blood sugar fluctuations, which is contrary to the growing health needs of modern consumers.
[0003] Dietary fiber is listed as the "seventh essential nutrient." Based on its water solubility, it can be divided into soluble dietary fiber (SDF) and insoluble dietary fiber (IDF). It has functions such as regulating gut microbiota, enhancing intestinal motility, regulating blood sugar and lipid metabolism, and reducing the risk of cardiovascular disease. It can also effectively lower the glycemic index of food by slowing down the digestion and absorption of carbohydrates, thus playing a positive role in blood sugar control. Furthermore, its excellent water-holding and oil-holding properties can optimize the texture and taste of biscuits.
[0004] Soybean residue is a major byproduct of soybean product (such as tofu and soy milk) production. In my country, the annual output of wet soybean residue exceeds 20 million tons, but its utilization rate is very low. Oxidation of soybean residue produces aldehydes and ketones, resulting in an unpleasant beany odor that limits its edible value. Using it solely as animal feed would lead to a serious waste of resources. Although soybean residue contains abundant dietary fiber (50%), the majority (approximately 90%) is in the form of IDF (individual fibroblast fiber), which has a dense structure, making it difficult to expose internal hydroxyl and carboxyl groups. This negatively impacts the physicochemical and functional properties of IDF. Therefore, it is necessary to modify IDF to improve its physicochemical and functional properties and broaden its practical applications.
[0005] However, current methods for modifying dietary fiber are relatively limited, resulting in poor modification effects and limited improvement in the physicochemical properties of dietary fiber. Combining methods, building upon single methods, can further disrupt the structure of dietary fiber and has great potential for improving its physicochemical properties. However, research on the effects of combined modification is currently scarce. This article presents a method for modifying insoluble dietary fiber from soybean residue using high-speed homogenization combined with *Neurospora crassa* fermentation, addressing a problem that needs to be solved by those skilled in the art. Furthermore, it supplements the comparison of the physicochemical effects of DF processed before fermentation versus before enzymatic hydrolysis. Summary of the Invention
[0006] The purpose of this invention is to provide a method for preparing insoluble dietary fiber from soybean residue and its application in shortbread biscuits.
[0007] The following technical solution is proposed: Fresh wet soybean residue is washed, filtered after cleaning, and then placed in an oven to dry, resulting in dried soybean residue; the obtained dried soybean residue is then crushed and sieved.
[0008] Further specify that the wet soybean residue should be washed until the washing liquid is clear.
[0009] Furthermore, the oven temperature is maintained at 60~65℃.
[0010] Further specify that the dried soybean residue should be sieved through a 40-mesh sieve before use.
[0011] 100.0 g of dried and sieved soybean residue was weighed and dispersed in distilled water at a ratio of 1:30 (w / v). The pH was adjusted to 4.5 with 0.1 mol / L HCl and 0.1 mol / L NaOH. 4 g of saccharifying enzyme was added, and the mixture was incubated in a water bath for 30 min at 60℃. The pH was then adjusted to 9.0, and 1 g of alkaline protease was added. The mixture was incubated in a water bath for 60 min at 55℃. The pH was then adjusted to 6.0, and 2 g of thermostable α-amylase was added. The mixture was incubated in a water bath for 40 min at 95℃. The enzyme reaction was terminated by treating the mixture in a boiling water bath for 10 min. After cooling to room temperature, the sample was centrifuged to remove the supernatant. The precipitate was freeze-dried to obtain insoluble dietary fiber from the soybean residue.
[0012] To further specify, the reagents used to adjust the pH in the experiment were 0.1 mol / L HCl and 0.1 mol / L NaOH.
[0013] The heat-resistant α-amylase, alkaline protease, and saccharifying enzyme described in the above technical solution are 4000 U / g, 200 U / mg, and 5000 U / g, respectively, and were all purchased from Shanghai Yuanye Biotechnology Co., Ltd.
[0014] Insoluble dietary fiber from soybean residue is dispersed in distilled water, and then the suspension is homogenized at different speeds. After that, it is sterilized by autoclaving, inoculated with Neurospora crassa for fermentation, and then freeze-dried to obtain insoluble dietary fiber from soybean residue modified by high-speed homogenization and Neurospora crassa fermentation. The specific steps include the following steps.
[0015] 10.0 g of insoluble dietary fiber from soybean residue was accurately weighed and dispersed in distilled water at a ratio of 1:10 (w / v). The mixture was homogenized at 10,000 rpm for 15 min using a high-speed homogenizer. After freeze-drying, the homogenized insoluble dietary fiber from soybean residue was obtained.
[0016] Accurately weigh 10.0 g of insoluble dietary fiber from soybean residue after high-speed homogenization, disperse it in distilled water at a ratio of 1:10 (w / v), add 1 g of sucrose and 0.2 g of yeast extract, then autoclave at 121℃ for 15 min, cool to room temperature and then inoculate.
[0017] Dilute the concentration of the Neurospora crassa spore suspension to 10. 7 Inoculation was performed at a rate of 8% (v / v) using *Neurospora crassa*, and the mixture was cultured and fermented at 30°C and 180 r / min for 2 days. The solution was then freeze-dried to obtain high-speed homogenized soybean residue insoluble dietary fiber modified by *Neurospora crassa* fermentation.
[0018] The strain used in the above experiment was Neurospora crassa CGMCC3.1603.
[0019] Furthermore, the combined modified soybean residue insoluble dietary fiber obtained by the method described above.
[0020] Furthermore, the changes in the content of IDF and SDF in the modified soybean residue insoluble dietary fiber were observed.
[0021] Furthermore, the particle size changes of the modified soybean residue dietary fiber were observed.
[0022] Furthermore, the modified soybean residue dietary fiber has the ability to adsorb glucose, cholesterol, and nitrite in vitro.
[0023] Mix the modified soybean pulp insoluble dietary fiber with granulated sugar, corn oil, and egg liquid until well combined. Then add baking soda and salt and mix well. Finally, add low-gluten wheat flour and mix well, kneading into a smooth dough for later use.
[0024] Furthermore, through single-factor orthogonal experiments and sensory evaluation, the optimal combination was determined: when the dietary fiber content was 4%, the corn oil content was 40%, the egg liquid content was 30%, and the granulated sugar content was 30%, the biscuits had an appealing reddish-yellow color, a complete shape, uniform thickness, a suitable wheat and egg aroma, and a crisp texture.
[0025] Furthermore, the biscuit dough recipe was determined as follows: 96g low-gluten wheat flour, 4g dietary fiber, 40g corn oil, 30g granulated sugar, 30g egg liquid, 2g baking soda, and 1g salt.
[0026] After letting the dough rest for 10 minutes, roll it out with a rolling pin to a thickness of about 5 mm. Use a cookie cutter to press it into shape, then use a scraper to transfer it to a baking tray and spread it out evenly.
[0027] Preheat the oven to 180℃ for 20 minutes, then place the baking tray in the oven and bake at 180℃ for 10 minutes. After baking, let the cookies cool to room temperature before use. Beneficial effects
[0028] This invention involves mixing soybean residue insoluble dietary fiber with distilled water and then homogenizing the mixture at high speed to obtain a treated solution. The treated solution contains modified insoluble dietary fiber. The high-speed homogenization process is performed at 5000-15000 rpm / min for 15 min. This invention uses high-speed homogenization combined with *Neurospora crassa* fermentation to modify soybean residue insoluble dietary fiber, optimizing its physicochemical and functional properties. The modified insoluble dietary fiber exhibits increased SDF content, reduced particle size, and enhanced adsorption capacity for sodium cholate, glucose, and nitrite. This method is safe and efficient, and the prepared modified soybean residue insoluble dietary fiber has broad application prospects. Example results show that, compared to the unmodified fiber, the modified insoluble dietary fiber obtained using this invention exhibits a maximum increase of 480% in SDF content, a maximum reduction of 320% in particle size, a maximum increase of 230% in water and oil holding capacity, a maximum increase of 290% in water and oil holding capacity, a maximum enhancement of 290% in glucose adsorption capacity, and a maximum enhancement of 150% in sodium cholate adsorption capacity. The results of the examples and comparative examples show that the modified insoluble dietary fiber obtained by the modification method of the present invention significantly reduces the glycemic index of shortbread biscuits to below 70, a reduction of 25%, reaching a medium GI level, which can prevent the human body from experiencing a spike in postprandial blood sugar. Attached Figure Description
[0029] Figure 1 This indicates the glucose adsorption capacity of the insoluble dietary fiber in modified soybean residue.
[0030] Figure 2 This indicates the adsorption capacity of modified soybean residue's insoluble dietary fiber sodium cholate.
[0031] Figure 3 This indicates the glycemic index of shortbread cookies. Detailed Implementation Example 1
[0032] 100.0 g of dried and sieved soybean residue was weighed and dispersed in distilled water at a ratio of 1:30 (w / v). The pH was adjusted to 4.5 with 0.1 mol / L HCl and 0.1 mol / L NaOH. 4 g of saccharifying enzyme was added, and the mixture was incubated in a water bath for 30 min at 60℃. The pH was then adjusted to 9.0, and 1 g of alkaline protease was added. The mixture was incubated in a water bath for 60 min at 55℃. The pH was then adjusted to 6.0, and 2 g of thermostable α-amylase was added. The mixture was incubated in a water bath for 40 min at 95℃. The enzyme reaction was terminated by treating the mixture in a boiling water bath for 10 min. After cooling to room temperature, the sample was centrifuged to remove the supernatant. The precipitate was freeze-dried to obtain insoluble dietary fiber from the soybean residue.
[0033] Subsequently, the insoluble dietary fiber from soybean residue was dispersed in distilled water at a ratio of 1:10 (w / v), along with 1g sucrose and 0.2g yeast extract. The mixture was then autoclaved at 121°C for 15 minutes and cooled to room temperature before inoculation. The concentration of the *Neurospora crassa* spore suspension was diluted to 10-1. 7 Inoculation was performed at a concentration of 8% (v / v) using *Neurospora crassa*, and the mixture was fermented at 30°C and 180 r / min on a shaker for 2 days. The solution was then freeze-dried. This yielded *Neurospora crassa* fermented and modified soybean residue insoluble dietary fiber. Example 2
[0034] 100.0 g of dried and sieved soybean residue was weighed and dispersed in distilled water at a ratio of 1:30 (w / v). The pH was adjusted to 4.5 with 0.1 mol / L HCl and 0.1 mol / L NaOH. 4 g of saccharifying enzyme was added, and the mixture was incubated in a water bath for 30 min at 60℃. The pH was then adjusted to 9.0, and 1 g of alkaline protease was added. The mixture was incubated in a water bath for 60 min at 55℃. The pH was then adjusted to 6.0, and 2 g of thermostable α-amylase was added. The mixture was incubated in a water bath for 40 min at 95℃. The enzyme reaction was terminated by treating the mixture in a boiling water bath for 10 min. After cooling to room temperature, the sample was centrifuged to remove the supernatant. The precipitate was freeze-dried to obtain insoluble dietary fiber from the soybean residue.
[0035] 10.0 g of soybean residue dietary fiber was accurately weighed and dispersed in distilled water at a ratio of 1:10 (w / v). The mixture was homogenized at 5000 rpm for 15 min using a high-speed homogenizer. After freeze-drying, the homogenized soybean residue insoluble dietary fiber was obtained.
[0036] The homogenized soybean residue insoluble dietary fiber was then dispersed in distilled water at a 1:10 (w / v) ratio, along with 1g sucrose and 0.2g yeast extract. The mixture was autoclaved at 121°C for 15 min, cooled to room temperature, and then inoculated. The concentration of the Neurospora crassa spore suspension was diluted to 10-1. 7 Inoculation was performed at a concentration of 8% (v / v) using *Neurospora crassa*, and the mixture was fermented at 30°C and 180 r / min on a shaker for 2 days. The solution was then freeze-dried. This yielded *Neurospora crassa* fermented and modified soybean residue insoluble dietary fiber. Example 3
[0037] The same as implementation 2, except that the high-speed homogenization speed is replaced with 10,000 r / min to obtain high-speed homogenized soybean residue insoluble dietary fiber. Example 4
[0038] The same as implementation 3, except that the high-speed homogenization speed is replaced with 15000 r / min to obtain high-speed homogenized soybean residue insoluble dietary fiber. Example 5
[0039] According to the recipe: knead the dough with 96 g of low-gluten wheat flour, 4 g of dietary fiber, 40 g of corn oil, 30 g of granulated sugar, 30 g of egg liquid, 2 g of baking soda, and 1 g of salt.
[0040] After letting the dough rest for 10 minutes, roll it out with a rolling pin to a thickness of about 5 mm. Use a cookie cutter to press it into shape, then use a scraper to transfer it to a baking tray and spread it out evenly.
[0041] Preheat the oven to 180℃ for 20 minutes, then place the baking tray in the oven and bake at 180℃ for 10 minutes. After baking, let the cookies cool to room temperature before use. Comparative Example 1
[0042] 100.0 g of dried and sieved soybean residue was weighed and dispersed in distilled water at a ratio of 1:30 (w / v). The pH was adjusted to 4.5 with 0.1 mol / L HCl and 0.1 mol / L NaOH. 4 g of saccharifying enzyme was added, and the mixture was incubated in a water bath for 30 min at 60℃. The pH was then adjusted to 9.0, and 1 g of alkaline protease was added. The mixture was incubated in a water bath for 60 min at 55℃. The pH was then adjusted to 6.0, and 2 g of thermostable α-amylase was added. The mixture was incubated in a water bath for 40 min at 95℃. The enzyme reaction was terminated by treating the mixture in a boiling water bath for 10 min. After cooling to room temperature, the sample was centrifuged to remove the supernatant. The precipitate was freeze-dried to obtain insoluble dietary fiber from the soybean residue. Comparative Example 2
[0043] Similar to Comparative Example 1, 10.0 g of soybean residue dietary fiber was accurately weighed and dispersed in distilled water at a ratio of 1:10 (w / v). The mixture was homogenized at 5000 rpm for 15 min using a high-speed homogenizer and then freeze-dried to obtain insoluble soybean residue dietary fiber after high-speed homogenization. Comparative Example 3
[0044] Similar to Comparative Example 2, the only difference is that the high-speed homogenization rate was replaced with 10,000 rpm / min to obtain high-speed homogenized modified soybean residue insoluble dietary fiber. Comparative Example 4
[0045] Similar to Comparative Example 3, the only difference is that the high-speed homogenization rate was replaced with 15000 rpm / min to obtain high-speed homogenized modified soybean residue insoluble dietary fiber. Comparative Example 5
[0046] The dried and sieved soybean residue was dispersed in distilled water at a ratio of 1:10 (w / v), with 1 g sucrose and 0.2 g yeast extract added. The mixture was autoclaved at 121°C for 15 min, cooled to room temperature, and then inoculated. The concentration of the *Neurospora crassa* spore suspension was diluted to 10-1.7 Inoculation was performed at a concentration of 8% (v / v) of *Neurospora crassa* cells / mL, and fermentation was carried out at 30°C and 180 r / min on a shaker for 2 days. The solution was then freeze-dried to obtain *Neurospora crassa* fermented and modified soybean residue.
[0047] 100.0 g of modified soybean residue was weighed and dispersed in distilled water at a ratio of 1:30 (w / v). The pH was adjusted to 4.5 with 0.1 mol / L HCl and 0.1 mol / L NaOH. 4 g of saccharifying enzyme was added, and the mixture was incubated in a water bath for 30 min at 60℃. The pH was then adjusted to 9.0, and 1 g of alkaline protease was added. The mixture was incubated in a water bath for 60 min at 55℃. The pH was then adjusted to 6.0, and 2 g of thermostable α-amylase was added. The mixture was incubated in a water bath for 40 min at 95℃. The enzyme reaction was terminated by treating the mixture in a boiling water bath for 10 min. After cooling to room temperature, the sample was centrifuged to remove the supernatant. The precipitate was freeze-dried to obtain insoluble dietary fiber from the soybean residue. Comparative Example 6
[0048] According to the recipe: knead the dough with 100 g low-gluten wheat flour, 40 g corn oil, 30 g granulated sugar, 30 g egg liquid, 2 g baking soda, and 1 g salt.
[0049] After letting the dough rest for 10 minutes, roll it out with a rolling pin to a thickness of about 5 mm. Use a cookie cutter to press it into shape, then use a scraper to transfer it to a baking tray and spread it out evenly.
[0050] Preheat the oven to 180℃ for 20 minutes, then place the baking tray in the oven and bake at 180℃ for 10 minutes. After baking, let the cookies cool to room temperature before use.
[0051] (1) Composition analysis.
[0052] The insoluble dietary fiber (IDF) and soluble dietary fiber (SDF) contents of soybean residue prepared in Examples 1-4 and Comparative Examples 1-5 were determined by enzymatic gravity method (AOAC 991.43).
[0053] Table 1. Content of insoluble dietary fiber components in modified soybean residue.
[0054] Analysis of the table shows that Examples 1-4 have higher SDF content than Comparative Examples 1-5, with more IDF being converted into SDF. The SDF produced by enzymatic hydrolysis followed by fermentation has a higher content than that produced by fermentation followed by enzymatic hydrolysis. Among them, Example 3 has the highest SDF content, which is 480% higher than that of Comparative Example 1. The increase in SDF content gives it better physicochemical activity, such as glucose adsorption capacity and sodium cholate adsorption capacity.
[0055] (2) Particle size analysis.
[0056] The sample was prepared into a 0.1% (w / v) solution with deionized water, and the particle size distribution of the sample was determined using a laser particle size analyzer. The particle size result was expressed as the surface average diameter D. [3,2] (μm) represents the value.
[0057] Table 2. Particle size of insoluble dietary fiber from modified soybean residue.
[0058] sample Particle size (μm) Experimental Example 1 <![CDATA[132.72±7.59 c ]]> Experimental Example 2 <![CDATA[79.92±5.2 e ]]> Experimental Example 3 <![CDATA[40.52±1.2 f ]]> Experiment Example 4 <![CDATA[57.36±6.1 d ]]> Comparative Example 1 <![CDATA[170.42±2.44 a ]]> Comparative Example 2 <![CDATA[145.32±3.21 b ]]> Comparative Example 3 <![CDATA[82.85±6.85 e ]]> Comparative Example 4 <![CDATA[94.12±2.8 d ]]> Comparative Example 5 <![CDATA[141.26±6.41 b ]]> Analysis of the table shows that Examples 1-4 have smaller particle sizes than Comparative Examples 1-5, and the particle size of the product that underwent enzymatic hydrolysis followed by fermentation was smaller than that of the product that underwent fermentation followed by enzymatic hydrolysis. Particle size is crucial for the physicochemical and functional properties of dietary fiber (DF), such as water retention, oil retention, sodium cholate adsorption, and glucose adsorption. Smaller particle size increases the specific surface area, exposing more functional group active sites, thus resulting in better physicochemical activity and adsorption properties. Furthermore, smaller particle size leads to a smoother texture in products containing added dietary fiber.
[0059] (3) Water holding capacity and oil holding capacity.
[0060] Accurately weigh 0.5 g of sample, add 20 mL of deionized water, let stand at 25℃ for 24 h, centrifuge at 10000 × g for 10 min, remove the supernatant, and calculate the water-holding capacity of the sample.
[0061] Accurately weigh 0.5 g of sample, add 20 mL of soybean oil, let stand at 25℃ for 24 h, centrifuge at 10000 × g for 10 min, remove the supernatant, and calculate the oil holding capacity of the sample.
[0062] Analysis of the table shows that Examples 1-4 have higher water-holding and oil-holding capacities than Comparative Examples 1-5. This is because the modification method reduces the particle size of the dietary fiber, making its structure more porous and exposing more active groups. The water-holding and oil-holding capacities of the product prior to enzymatic hydrolysis followed by fermentation are higher than those of the product prior to fermentation followed by enzymatic hydrolysis. Higher water-holding capacity allows for the retention of more moisture in the food, thereby reducing shrinkage caused by dehydration. Higher oil-holding capacity indicates that the dietary fiber can absorb and retain more oil, which has significant application value for foods such as biscuits and bread where oil content needs to be controlled.
[0063] (4) Glucose adsorption capacity.
[0064] Accurately weigh 0.1 g of sample, add 20 mL of 100 mmol / L glucose solution, and shake in a water bath at 37℃ for 2 h. After adsorption equilibrium is reached, centrifuge at 10000 × g for 10 min, and collect 1 mL of supernatant. Determine the glucose content using the dinitrosalicylic acid (DNS) colorimetric method, measuring the absorbance at 540 nm.
[0065] Depend on Figure 1It can be seen that the glucose adsorption capacity of Examples 1-4 is higher than that of Comparative Examples 1-5, proving that the combined modified soybean residue insoluble dietary fiber has a better ability to regulate human blood sugar. The smaller particle size and higher SDF provide more glucose adsorption sites, increasing the glucose adsorption capacity. The glucose adsorption capacity of the product after enzymatic hydrolysis and fermentation is higher than that of the product after fermentation and enzymatic hydrolysis.
[0066] (5) Sodium cholate adsorption capacity.
[0067] Accurately weigh 0.1 g of sample and add 5 mL of 2 mg / mL sodium cholate-phosphate solution. Incubate at 37°C with shaking in a water bath for 2 h. After adsorption equilibrium is reached, centrifuge at 7303 × g for 10 min. Take 1 mL of the supernatant and add 6 mL of 45% sulfuric acid solution and 1 mL of 0.3% furfural solution sequentially. Mix thoroughly and react in a water bath at 65°C for 30 min. After the reaction is complete, cool to 25°C. Analyze the sodium cholate content using the furfural colorimetric method, measuring the absorbance at 620 nm.
[0068] Depend on Figure 2 It can be seen that the sodium cholate adsorption capacity of Examples 1-4 is higher than that of Comparative Examples 1-5, and the sodium cholate adsorption capacity of the first enzymatic hydrolysis followed by fermentation is higher than that of the first fermentation followed by enzymatic hydrolysis. The adsorption capacity of dietary fiber for sodium cholate can benefit human health through multiple mechanisms, especially in the prevention and management of cardiovascular diseases, the improvement of lipid metabolism, and the maintenance of intestinal health. The combined modification of DF cleavage and degradation results in a smaller particle size, exposing more binding groups such as acetyl groups, which makes its binding capacity with sodium cholate stronger.
[0069] (6) Estimated glycemic index (eGI) of biscuits.
[0070] The method for preparing the digestion solution is as follows.
[0071] (1) Simulated oral digestive fluid: Add α-amylase (150U / mL) to oral stock solution (15.1 mmol / L KCl, 3.7 mmol / L KH2PO4, 13.6 mmol / L NaHCO3, 0.15 mmol / L MgCl2(H2O)6 and 0.06 mmol / L (NH4)2CO3) and adjust the pH to 7.
[0072] (2) Simulated gastric digestive fluid: Add pepsin (400 U / mL) to the gastric stock solution (6.9 mmol / L KCl, 0.9 mmol / L KH2PO4, 25 mmol / L NaHCO3, 7.2 mmol / L NaCl, 0.1 mmol / L MgCl2(H2O)6 and 0.5 mmol / L (NH4)2CO3) and adjust the pH to 3.
[0073] (3) Simulate intestinal digestive fluid: Add pancreatic enzyme (400 U / mL) to the intestinal fluid stock solution (6.8 mmol / L KCl, 0.8 mmol / L KH2PO4, 85 mmol / L Na HCO3, 38.4 mmol / L NaCl, 0.33 mmol / L MgCl2∙(H2O)6) and adjust the pH to 7.
[0074] In vitro digestion simulation.
[0075] (1) Mix 10 g of biscuit crumbs (80 mesh) with 10 mL of oral digestive fluid in an Erlenmeyer flask, seal the flask, and place it in a constant temperature shaker at 37°C and 100 r / min for 2 min.
[0076] (2) After oral digestion, add 20 mL of gastric digestion solution to the sample solution and place it in a constant temperature shaker at 37°C and 100 r / min for 2 h.
[0077] (3) After the sample solution was digested in the stomach, 40 mL of intestinal digestion solution was added and shaken in a constant temperature shaker at 37°C and 100 r / min for 3 h. Then the sample solution was mixed with 40 mL of intestinal digestion solution.
[0078] Samples were taken in 1.5 mL increments at 10, 20, 30, 60, 90, 120, and 180 min, inactivated at 95 °C for 5 min, and then centrifuged at 8000 × g at 25 °C for 10 min. The supernatant was collected. Starch was classified as follows: rapidly digestible starch (RDS) that was digested within 20 min; slowly digestible starch (SDS) that was digested between 20 and 120 min; and resistant starch (RS) that was digested after 120 min.
[0079] HI calculation: HI = AUG1 / AUG2 × 100.
[0080] eGI calculation: eGI=8.198+0.862×HI.
[0081] HI stands for hydrolysis index.
[0082] AUG1 is the area enclosed by the hydrolysis rate curve and the horizontal coordinate of starch in the sample.
[0083] AUG2 is the area enclosed by the hydrolysis rate curve and the horizontal coordinate of the standard white bread sample.
[0084] like Figure 3As shown, the addition of starch (DF) significantly affects the glycemic index (eGI) of shortbread cookies. Shortbread cookies with added DF show a significant decrease in eGI, dropping below 70, reaching a medium GI level. Low eGI foods are more likely to induce a feeling of fullness, leading to lower insulin levels. Foods with a glycemic index above 70 are high-glycemic index foods; they are rapidly digested in the gastrointestinal tract, causing a rapid rise in blood sugar. Foods with a glycemic index between 55 and 70 are considered medium GI foods; the starch, which has a lower absorption rate, stays in the gastrointestinal tract for a longer period, allowing the body sufficient time to release and synthesize insulin, preventing a spike in blood sugar.
Claims
1. A method for preparing insoluble dietary fiber from soybean residue and its application in shortbread biscuits, characterized in that, Includes the following steps: (1) Wash, dry, crush and sieve the fresh wet soybean residue to obtain the dried soybean residue. (2) Using dried soybean residue as raw material, insoluble dietary fiber from soybean residue is obtained through enzymatic hydrolysis, enzyme inactivation, centrifugation, and freeze-drying; specifically including the following steps: (2-1) Weigh 100.0 g of dried and sieved soybean residue and disperse it in distilled water at a ratio of 1:30 (w / v). Adjust the pH to 4.5 with 0.1 mol / L HCl and 0.1 mol / L NaOH, add 4 g of saccharifying enzyme, and incubate in a water bath for 30 min at 60℃. Adjust the pH to 9.0, add 1 g of alkaline protease, and incubate in a water bath for 60 min at 55℃. Adjust the pH to 6.0, add 2 g of thermostable α-amylase, and incubate in a water bath for 40 min at 95℃. Terminate the enzyme reaction by treating in a boiling water bath for 10 min, cool to room temperature, centrifuge the sample to remove the supernatant, and freeze-dry the precipitate to obtain soybean residue insoluble dietary fiber. (3) Disperse the insoluble dietary fiber of soybean residue in distilled water, then homogenize the suspension of insoluble dietary fiber of soybean residue at different speeds, then sterilize by autoclaving, inoculate with Neurospora crassa for fermentation, and then freeze-dry to obtain high-speed homogenized Neurospora crassa-assisted fermentation modified soybean residue dietary fiber; specifically including the following steps: (3-1) Accurately weigh 10.0 g of soybean residue dietary fiber and disperse it in distilled water at a ratio of 1:10 (w / v). Use a high-speed homogenizer to homogenize at 10,000 rpm / min for 15 min. After freeze drying, obtain soybean residue insoluble dietary fiber after high-speed homogenization. (3-2) Accurately weigh 10.0 g of insoluble dietary fiber from soybean residue after high-speed homogenization, disperse it in distilled water at a ratio of 1:10 (w / v), add 1 g of sucrose and 0.2 g of yeast extract, then autoclave at 121℃ for 15 min, cool to room temperature, and inoculate. Dilute the concentration of the Neurospora crassa spore suspension to 10. 7 Inoculation was performed at a concentration of 8% (v / v) using *Neurospora crassa*, and the mixture was cultured and fermented at 30°C and 180 rpm for 2 days. The solution was then freeze-dried to obtain high-speed homogenized soybean residue insoluble dietary fiber modified by *Neurospora crassa* fermentation. (4) Mix the modified soybean residue insoluble dietary fiber with granulated sugar, corn oil and egg liquid evenly. Then add baking soda and salt and mix evenly. Finally, add low-gluten wheat flour and mix evenly. Knead into a smooth dough for later use. (4-1) Biscuit dough recipe: 96 g low-gluten wheat flour, 4 g dietary fiber, 40 g corn oil, 30 g granulated sugar, 30 g egg liquid, 2 g baking soda, 1 g salt. (4-2) After letting the dough rest for 10 minutes, roll it out with a rolling pin to a thickness of about 5 mm, press it into shape with a cookie cutter, and transfer it to a baking tray with a scraper and spread it out evenly. (4-3) Preheat the oven to 180℃ for 20 minutes, then place the baking tray in the oven and bake at 180℃ for 10 minutes.
2. The preparation of insoluble dietary fiber from soybean residue according to claim 1 and its application in shortbread biscuits, characterized in that, The thermostable α-amylase, alkaline protease, and saccharifying enzyme were 4000 U / g, 200 U / mg, and 5000 U / g, respectively.
3. Prepare soybean residue insoluble dietary fiber that can reduce the GI of shortbread biscuits using the method described in any one of claims 1-2.