Processing method of high-fiber steamed buns with slow digestion function

Abstract

The invention discloses a processing method of high-fiber steamed buns with a slow digestion function, and belongs to the technical field of food processing. The quality defects that traditional wheat steamed buns are poor in gluten network structure stability, prone to softening and collapsing, prone to aging and the like are overcome. According to the invention, a low-moisture extrusion technology is combined with compound enzyme directional modification to modify the dietary fibers in the lentinus edodes stems, so that the modified lentinus edodes stem dietary fibers are obtained. A traditional steamed bun processing technology and a traditional steamed bun processing formula are optimized, key technological parameters such as extrusion technological parameters, enzymolysis conditions and the addition amount of the modified dietary fibers are optimized, and the high-fiber steamed bun rich in the modified lentinus edodes stem dietary fibers is prepared. As an exogenous nutritional supplement and a texture modifier, the extruded modified dietary fiber not only solves the quality defects of poor gluten network structure stability, easiness in softening, easiness in aging and the like of the traditional wheat steamed bun, but also reduces the digestibility of the wheat steamed bun. The method has a wide application prospect for developing wheat flour derivative products with high fiber and low digestibility.

Description

Technical Field

[0001] The invention belongs to the technical field of food processing, and in particular relates to a processing method for preparing high-fiber steamed buns by extruding modified dietary fiber with low moisture content. Background Art

[0002] Dietary fiber is a functionally active polysaccharide that plays a crucial role in regulating the hydration capacity and viscoelastic properties of dough products. Based on its water solubility, dietary fiber components can be divided into soluble and insoluble dietary fiber. During steamed bread processing, soluble dietary fiber enhances the hydration capacity of the food system through its water-binding properties. This not only promotes intermolecular interactions but also contributes to the formation of a complex gel network matrix. In contrast, insoluble dietary fiber, through its rigid granular structure, directly embeds itself into the starch matrix, hindering the close packing of starch chains. Furthermore, the addition of insoluble dietary fiber may hinder the formation of the gluten protein network and weaken the dough texture. The balance between these two components in the dietary system influences the product quality and consumer acceptance of steamed bread. To achieve sustainable development strategies for the food industry, agricultural by-products (such as bran, fruit pulp, legumes, and other plant resources) have become promising new dietary fiber sources due to their rich dietary fiber content and renewable nature. Given that agricultural and sideline products such as shiitake mushroom stems are usually discarded as waste during traditional processing, high-value utilization can be achieved through modification technology, which provides a feasible technical path for promoting the circular bioeconomy of the food industry.

[0003] Low-moisture extrusion technology is a modification method that combines high-temperature extrusion with puffing effects. It can optimize the composition and functional performance of dietary fiber and promote the efficient conversion of insoluble dietary fiber to soluble dietary fiber. Studies have shown that after extrusion modification, the microstructure of dietary fiber changes significantly, and the original dense layered structure on its surface is transformed into a porous honeycomb network structure, which has a positive effect on the development of functional properties of modified dietary fiber. In addition, synergistically modified dietary fiber can be used to improve the gel properties of natural flour systems due to its excellent thickening and water-holding capacity. At the same time, modified dietary fiber can inhibit the interaction between digestive enzymes and starch matrix through steric hindrance effect, thereby effectively delaying the digestion process of starch.

[0004] Based on this, the present invention innovatively applies extruded modified shiitake mushroom stem dietary fiber to the wheat steamed bun recipe optimization system. This not only provides a new technical path for the deep processing of dietary fiber in the food industry, but also realizes the high-value utilization of edible fungus processing byproducts. Summary of the Invention

[0005] In response to the problems of traditional steamed buns being soft and aging easily and having unbalanced nutritional components, the present invention provides a method for directional regulation of the functional properties of dietary fiber through low-moisture extrusion technology, and realizes the coordinated processing of modified dietary fiber and wheat flour to prepare high-fiber steamed buns.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for processing high-fiber steamed bread with slow digestion function comprises the following steps:

[0008] (1) adjusting the moisture content of shiitake mushroom stem powder to 10-40%, and preparing extruded shiitake mushroom stems under the conditions of an extrusion hot melt temperature of 90-130° C., a screw speed of 150-200 rpm, and a feeding rate of 20-40 g / min;

[0009] (2) dissolving the extruded and puffed shiitake mushroom stems in a phosphate buffer solution with a concentration of 0.05 mol / L, and oscillating and mixing to obtain an extruded and puffed shiitake mushroom stem suspension;

[0010] (3) Add 0.5-2.0 g of α-amylase to the extruded mushroom stem solution, place the mixture at a constant temperature of 60-70° C., and react at an oscillation frequency of 100-300 rpm for 20-40 min; take out and cool to 50-60° C., add 0.1-2.0 g of neutral protease, then place the mixture at 50-60° C. and react at an oscillation frequency of 100-300 rpm for 20-40 min; finally, adjust the pH of the reaction system to 5.0-7.0, add 0.2-1.0 g of glucosidase, then place the mixture at 50-60° C. and react at an oscillation frequency of 100-300 rpm for 20-40 min; keep the pH stable during the enzymatic hydrolysis process, and inactivate the enzyme for 5-15 min after the enzymatic hydrolysis to obtain an enzymatic hydrolyzate;

[0011] (4) Alcohol precipitation purification: collecting the enzymatic hydrolysate from step (3), centrifuging it, and separating the supernatant and the precipitate; washing it with 60-80°C hot water and 90-99% food-grade ethanol for more than three times, respectively, filtering it after washing, collecting the precipitate, and freeze-drying it to obtain the modified Lentinus edodes stem dietary fiber;

[0012] (5) adding modified Lentinus edodes stem dietary fiber to wheat flour and mixing them evenly to form Lentinus edodes stem dietary fiber-wheat mixed flour;

[0013] (6) Mixing the shiitake mushroom stem dietary fiber-wheat mixed flour with the yeast aqueous solution and stirring until a smooth and uniform dough is formed; then forming, proofing and steaming the dough to obtain a high-fiber steamed bun with slow digestion function.

[0014] The preparation method of the mushroom stem powder is as follows: placing the mushroom stem in an oven at 50°C for drying, and then crushing and sieving (80 meshes) to obtain the mushroom stem powder.

[0015] Wherein, the concentration of the phosphate buffer is 0.02-0.1 mol / L, and the pH is 7.0-7.5.

[0016] Wherein, in the step (2), the material-liquid ratio of the extruded and puffed mushroom stems to the phosphate buffer solution is 1:30 to 1:50 g / mL, and the oscillation is carried out at 1000 to 3000 rpm for 10 to 15 minutes.

[0017] Wherein, in the step (3), the α-amylase activity is 2000-8000 U / g, and the pH is 5.0-6.0.

[0018] Wherein, in the step (3), the activity of the neutral protease is 5000-100000 U / g, and the pH is 6.0-7.0.

[0019] Wherein, in the step (3), the activity of glucosidase is 2000-20000 U / g, and the pH is 5.0-7.0.

[0020] Wherein, in the step (4), the centrifugal treatment condition is centrifugation at 2000-5000×g for 10-20 minutes.

[0021] Wherein, in the step (5), the added amount of the modified shiitake mushroom stem dietary fiber is 2 to 15%.

[0022] Wherein, in step (6), the mass percentage concentration of the yeast aqueous solution is 1% to 2%.

[0023] Beneficial effects

[0024] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0025] (1) The present invention utilizes low-moisture extruded modified shiitake mushroom stems. Under high temperature, high pressure, and strong shear conditions, the insoluble dietary fibers such as pectin, cellulose, and lignin within the material are subjected to the synergistic effects of enormous mechanical shear and heat, causing the insoluble components to degrade and restructure, thereby increasing the content of soluble components in the material. The structure of the extruded modified dietary fiber undergoes significant changes. When mixed with wheat flour, it can significantly improve the quality defects of traditional wheat steamed buns, such as low elasticity and poor chewiness. However, unmodified shiitake mushroom stem fibers cannot improve the gluten structure and quality characteristics of wheat steamed buns.

[0026] (2) The present invention adopts a composite enzymatic hydrolysis process, optimizes the action conditions of α-amylase, neutral protease and glucosidase (including reaction temperature, time, pH value and enzyme activity ratio), and constructs an efficient catalytic system with multi-enzyme synergy based on enzyme kinetic characteristics. This technology can specifically degrade non-target components in shiitake mushroom stems, accurately control the ratio of soluble / insoluble components in dietary fiber, and achieve directional modification of the molecular structure of dietary fiber and functional enhancement. Compared with traditional modification treatment technology, the present invention adopts extrusion-composite enzymatic hydrolysis synergistic modification process, which not only significantly improves the functional properties of dietary fiber such as water holding capacity, swelling capacity, and glucose adsorption capacity, but also effectively solves the technical bottlenecks of traditional processes such as uneven dietary fiber components and poor structural stability. Extruded modified dietary fiber can be used in the production of baked goods, partially replacing wheat flour to improve the ductility, water holding capacity and stability of dough. Therefore, in the processing of noodle foods, modified dietary fiber can be used as a structure modifier or leavening agent to improve the quality and processing characteristics of dough.

[0027] (3) This study not only effectively solved the common problems of traditional wheat steamed bread such as poor processing applicability, easy aging, and easy softening by optimizing the processing technology and product formula, but also significantly improved the quality defects of steamed bread caused by the addition of insoluble dietary fiber, such as rough taste, poor color, and reduced texture characteristics. In addition, the digestibility of starch in wheat steamed bread was further reduced, laying the foundation for the application of modified dietary fiber in the processing of wheat-derived foods. The experimental results showed that when unmodified dietary fiber was directly added to wheat flour, the insoluble dietary fiber would hinder the formation of the gluten protein network structure, resulting in a decrease in the elasticity and ductility of the dough. The insoluble dietary fiber made the wheat steamed bread less palatable due to its hard texture and rough taste. In addition, the insoluble dietary fiber would destroy the gluten network structure, resulting in a decrease in CO2 retention capacity, which ultimately manifested as uneven distribution of fermentation holes, reduced specific volume of steamed bread, and dense texture. The above common problems can be solved by adding extruded mushroom stem dietary fiber to improve the quality characteristics and processing applicability of wheat steamed bread.

[0028] The preparation method of the high-fiber steamed buns with slow digestion function of the present invention not only meets the standardization requirements of continuous industrial production, but also effectively reduces the use of chemical reagents, ensuring the safety and reliability of food raw material pretreatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for describing the embodiments or the prior art.

[0030] Figure 1 This is a hardness comparison chart of various embodiments and comparative examples of the present invention;

[0031] Figure 2 This is a comparison chart of the elasticity of various embodiments and comparative examples of the present invention;

[0032] Figure 3 This is a comparison chart of the adhesiveness of various embodiments and comparative examples of the present invention;

[0033] Figure 4 A comparison chart of the chewability of various embodiments and comparative examples of the present invention;

[0034] Figure 5 It is a line graph of the oral-gastric-intestinal digestibility of each embodiment and comparative example of the present invention. DETAILED DESCRIPTION

[0035] In order to make the present invention clearer, the present invention will be further explained in detail with reference to specific examples and drawings. It should be noted that the following examples are only used to illustrate the technical solutions of the present invention and do not constitute any limitation to the present invention. Similarly, all other implementation methods obtained by those skilled in the art based on the concept of the present invention without creative work are within the scope of protection of the claims of the present invention. Without departing from the design principle of the present invention, any equivalent replacement or simple modification of the technical solution of the present invention should be deemed to fall within the scope of protection of the present invention.

[0036] The reagents in this embodiment are all food grade, and the low-moisture extrusion equipment involved is model HM30-IV, purchased from Jinan Hengmai Machinery Co., Ltd.

[0037] Example 1

[0038] To address the quality issues of shiitake mushroom stem dietary fiber, such as a rough texture, poor palatability, and hard texture, when added directly to wheat flour, this example proposes a method for processing high-fiber steamed buns that improves the texture of traditional wheat steamed buns and has a slow-digesting effect. The steamed buns with a slow-digesting effect are primarily prepared by mixing shiitake mushroom stem dietary fiber modified by low-moisture extrusion technology with wheat flour, specifically comprising the following steps:

[0039] (1) Preparation of extruded mushroom stems: The mushroom stems were dried at 40°C, crushed and sieved (80 mesh), and the moisture content was adjusted to 30%. The powder was placed in the feed bin of a low-moisture extrusion equipment and extruded mushroom stems were produced under the following process parameters: an extrusion hot melt temperature of 120°C, a screw speed of 180 rpm, and a feed rate of 30 g / min.

[0040] (2) The squeezed mushroom stems were dissolved in a phosphate buffer solution with a concentration of 0.05 mol / L and a pH of 7.0, with a solid-liquid ratio of 1:40 g / mL. The mixture was shaken at 1000 rpm for 10 min using a vortex shaker to mix evenly.

[0041] (3) A composite enzyme method was used to extract dietary fiber from shiitake mushroom stems, and α-amylase, neutral protease, and glucosidase were added in sequence for step-by-step enzymatic hydrolysis. The specific steps included: adding 1.0 g, 4000 U / g, pH 5.5 α-amylase to the solution obtained in step (2), and placing the mixture in a constant temperature oscillator at a constant temperature of 70°C and an oscillation frequency of 160 rpm for reaction for 35 minutes. After cooling to 60°C, 1.0 g, 50000 U / g, pH 7.0 neutral protease was added, and the mixture was then placed in a constant temperature oscillator at 60°C and 160 rpm for reaction for 30 minutes. The pH of the reaction system was adjusted to 5.5, and 1.0 g, 10000 U / g glucosidase was added, and then placed in a constant temperature oscillator at 60°C and 160 rpm for reaction for 30 minutes. The pH was kept stable during the enzymatic hydrolysis process, and the enzyme was inactivated in a boiling water bath for 10 minutes after enzymatic hydrolysis.

[0042] (4) Alcohol precipitation purification: The enzymatic hydrolysate from step (3) was collected and centrifuged at 3000×g for 15 min to separate the supernatant and precipitate. The supernatant and precipitate were washed with 70°C hot water and 95% ethanol for 6 times, respectively, and then filtered. The precipitate was collected and freeze-dried to obtain the modified Lentinus edodes stem dietary fiber.

[0043] (5) Preparation of Lentinus edodes stem dietary fiber-wheat mixed flour: 10% modified Lentinus edodes stem dietary fiber was added to wheat flour and mixed evenly to form wheat mixed flour.

[0044] (6) Mixing: 160 g of wheat flour mixture was mixed with 100 mL of yeast aqueous solution (1%, w / w), and stirred at medium speed until a smooth and uniform dough was formed.

[0045] (7) Shaping: Cut the dough into 20g pieces and knead them into round shapes.

[0046] (8) Proofing: The dough obtained in step (6) was placed in a proofing box at 37°C and a humidity of 85% for 30 minutes.

[0047] (9) Steaming: Steam the dough fermented in step (7) for 30 minutes to obtain high-fiber steamed buns with slow digestion function.

[0048] Comparative Example 1

[0049] This comparative example is substantially the same as the embodiment, except that: this comparative example adds shiitake mushroom stem dietary fiber that has not been pre-modified by low-moisture extrusion, that is, step 1 is omitted, and the remaining steps and addition amounts are the same as those in embodiment 1.

[0050] Comparative Example 2

[0051] This comparative example is substantially the same as the embodiment, except that no shiitake mushroom stem dietary fiber is added in this comparative example, that is, steps 1 to 5 are omitted, and the remaining steps are the same as those in embodiment 1.

[0052] Detection methods and results

[0053] (1) Color Difference Measurement: The L*, a*, and b* values ​​of Example 1 and Comparative Examples 1-2 of the present invention were measured and recorded using a DS-700D fully automatic colorimeter. Before the formal measurement, calibration was performed using white and black porcelain plates. Samples from different parts of each steamed bun sample were cut and measured three times, and the average value was calculated. The color of the different samples was quantitatively analyzed using the colorimeter. The color difference results of Example 1 and Comparative Examples 1-2 are shown in Table 1.

[0054] Table 1 Color difference analysis of different steamed bread samples

[0055]

[0056] Note: Different lowercase letters in the same column indicate significant differences between different data, P < 0.05. L* value (0 represents black, 100 represents white), a* value (positive value represents red, negative value represents green), and b* value (positive value represents yellow, negative value represents blue).

[0057] The color of Example 1 of the present invention and Comparative Examples 1 to 2 were analyzed using a colorimeter, and the color difference results of the three different steamed bread samples are shown in Table 1. Among them, the L*, a*, and b* values ​​represent black-white, red-green, and yellow-blue, respectively. As can be seen from the table, the L* value of Example 1 is significantly lower than that of Comparative Examples 1 and 2, but the a*, b*, and ΔE* values ​​are higher. This shows that after adding the modified shiitake mushroom stem dietary fiber, the brightness of the wheat steamed bread surface becomes darker, the green value decreases, and the color turns yellow. It can be seen intuitively from the color card in the table that the color of the wheat steamed bread gradually becomes darker, and the color change of Example 1 is the most obvious. This is most likely because the content of polysaccharides, soluble dietary fiber and other substances in the modified shiitake mushroom stem dietary fiber increases, and Maillard reaction occurs with amino compounds during the heating process, thereby reducing the brightness of the steamed bread.

[0058] (2) Texture determination: The steamed bread samples were cut into 1.0cm*1.0cm*1.0cm cubes and their texture characteristics were analyzed using a TMS-Pilot texture analyzer with a 500N weighing sensor. In all experiments, the samples were compressed under a cylindrical probe (75mm in diameter) at a test speed of 60mm / min and a trigger force of 0.75N. The deformation of the sample was half of the original sample height. Each sample was tested 5 to 8 times, and the TL-Pro texture test software was used to record the hardness, elasticity, stickiness and chewiness of the wheat bread samples. The specific results are as follows: Figures 1 to 4 shown.

[0059] Compared with Comparative Example 1, the hardness, stickiness and chewiness of Example 1 increased by 37.55N, 18.01N and 148.78mj respectively. This shows that the addition of extruded modified shiitake mushroom stem dietary fiber can significantly improve the quality defects of traditional wheat steamed bread products such as low elasticity and poor chewiness. It can be seen intuitively from the figure that Comparative Examples 1 and 2 are significantly lower than Example 1 in hardness, elasticity, stickiness and chewiness, among which the texture characteristics of Comparative Example 2 are the worst. In summary, the appropriate addition of edible fungus materials rich in soluble dietary fiber can help improve the quality characteristics of steamed bread and meet consumers' demand for healthy functional staple foods.

[0060] (3) Simulated oral-gastrointestinal digestion in vitro: The three digestion stages of the oral cavity, stomach, and intestine were simulated independently in vitro. The simulated oral solution (SSF), simulated gastric fluid solution (SGF), and simulated intestinal fluid solution (SIF) required for the digestion process were prepared according to Table 2 and stored at 37°C for subsequent use.

[0061] Table 2 Digestive juice formula

[0062]

[0063] a. In vitro simulated oral digestion: Accurately weigh 0.5 g of steamed bread sample, add 4 mL of simulated oral solution to the sample and mix thoroughly using a vortex oscillator. All reagents must be preheated to 37°C and mixed thoroughly before use. Add salivary amylase (150 U / mL) to the mixed solution and add distilled water to make up to 10 mL. Subsequently, place the mixture in a water bath thermostat oscillator (37°C, 160 rpm) and shake for 2 minutes. After the reaction is completed, boil in a boiling water bath for 5 minutes to inactivate the enzyme. After centrifugation (8000×g, 10 min), take 0.1 mL of the supernatant and add 3 mL of GOPOD reagent to detect its glucose concentration.

[0064] b. In vitro simulated gastric digestion: 10 mL of the digestion product obtained after oral digestion was added to 8 mL of simulated gastric solution, pepsin (4000 U / mL), CaCl2 (0.3 M, 5 μL), and HCl (5 M, 0.4 mL). The volume was then adjusted to 20 mL with distilled water. The mixture was then shaken in a thermostatic water bath (37°C, 160 rpm) for 2 h. After the reaction, the enzyme was inactivated in a boiling water bath for 5 min. After centrifugation (8000 × g, 10 min), 0.1 mL of the supernatant was added to 3 mL of GOPOD reagent to measure the glucose concentration.

[0065] c. In vitro simulated intestinal digestion: 20 mL of digestate obtained after gastric digestion was added to 16 mL of simulated intestinal solution, porcine pancreatic α-amylase (200 U / mL), glucosidase (160 U / mL), bile (0.1 M, pH 5.2), CaCl2 (0.3 M, 20 μL), and NaOH (5 M, 0.8 mL). The volume was then adjusted to 40 mL with distilled water. The mixture was then shaken in a thermostatic water bath (37°C, 160 rpm) for 20, 40, 60, 90, 120, and 180 min. Each centrifuge tube was assigned a specific digestion time to ensure consistent digestion volume. After completion of the reaction, the enzymes were inactivated in a boiling water bath for 5 min. After centrifugation (8000 × g, 10 min), 0.1 mL of the supernatant was added to 3 mL of GOPOD reagent to determine the glucose concentration.

[0066] Rapidly digestible starch (RDS), slowly digestible starch (SDS), resistant starch (RS), hydrolysis index (HI), and eGI were calculated according to the following formulas.

[0067]

[0068] RS(%)=1-RDS-SDS (3)

[0069]

[0070] eGI=39.71+0.549×HI (5)

[0071] Where:

[0072] G t —glucose content released by hydrolysis at t min;

[0073] G0, G 20 , G 120- Glucose content released by hydrolysis at 0 min, 20 min, and 120 min;

[0074] WS—total mass of the sample;

[0075] S1—the area enclosed by the hydrolysis rate curve of starch in the sample and the horizontal coordinate axis;

[0076] S2—The area enclosed by the hydrolysis rate curve of the white bread standard sample and the horizontal coordinate axis.

[0077] As shown in Table 3, the content of rapidly digestible starch in Example 1 is significantly lower than that in Comparative Example 1 and Comparative Example 2. In addition, compared with Comparative Example 1, the HI value and eGI value of Example 1 are reduced by 4.58 and 2.72 respectively. Figure 5 As shown, the starch digestibility of Example 1 during oral, gastric, and intestinal digestion was lower than that of Comparative Examples 1 and 2. This indicates that the low-moisture extruded modified Lentinus edodes stem dietary fiber effectively encapsulates or traps more starch granules through its loose, porous honeycomb network structure, thereby delaying the digestion and hydrolysis of starch. In summary, modified Lentinus edodes stem dietary fiber has great potential as an exogenous nutritional supplement for the development of starch-based foods with low digestibility.

[0078] Table 3 Starch composition and glycemic index of different steamed bread samples

[0079]

[0080] Note: Different lowercase letters in the same column indicate significant differences between data (P < 0.05). RDS, SDS, and RS represent rapidly digestible starch, slowly digestible starch, and resistant starch, respectively. HI and GI represent hydrolysis index and glycemic index, respectively.

[0081] (4) Sensory evaluation: The sensory evaluation panel consisted of 30 professionally trained sensory assessors (15 males and 15 females, aged 22-30 years). Different steamed bread samples were randomly placed on white porcelain plates, and the panelists observed the color, appearance, and odor of the steamed bread under natural light. When performing sensory evaluations on different samples, the panelists rinsed their mouths with warm water to minimize interference between samples. The scoring criteria are shown in Table 4, and the final results are expressed as the average value.

[0082] Table 4 Sensory scoring standards

[0083]

[0084] As shown in Table 5, compared to Comparative Example 1, the flavor score for Example 1 increased from 11.53±1.29 to 18.67±0.58, indicating that steamed buns with a unique shiitake mushroom flavor are popular with consumers. Furthermore, Example 1 received high scores for both texture and taste, demonstrating that the addition of modified shiitake mushroom stem dietary fiber has significant potential for improving the texture and sensory properties of steamed buns.

[0085] Table 5 Sensory evaluation of different steamed bread samples

[0086]

[0087] Note: Different lowercase letters in the same column indicate significant differences between different data, P < 0.05

[0088] The above descriptions are only some embodiments of the present invention and do not limit the scope of protection of the present invention. Any equivalent device or equivalent process transformation made by using the contents of the description and drawings of the present invention, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

[0089] Example 2

[0090] To address the quality issues of shiitake mushroom stem dietary fiber, such as a rough texture, poor palatability, and hard texture, when added directly to wheat flour, this embodiment proposes a method for processing high-fiber steamed buns that improves the texture of traditional wheat steamed buns and has a slow-digesting function. The steamed buns with a slow-digesting function are mainly prepared by mixing shiitake mushroom stem dietary fiber modified by low-moisture extrusion technology with wheat flour, and specifically include the following steps:

[0091] (1) Preparation of extruded shiitake mushroom stems: Shiitake mushroom stems were dried at 50°C and crushed, passed through a 100-mesh sieve, and the moisture content was adjusted to 40%. The powder was placed in the feed bin of a low-moisture extrusion machine. The extrusion heat-melting temperature was set at 130°C, the screw speed was set at 150 rpm, and the feed rate was set at 40 g / min to produce extruded shiitake mushroom stems.

[0092] (2) The squeezed mushroom stems were dissolved in a phosphate buffer solution with a concentration of 0.1 mol / L and a pH of 7.5, with a solid-liquid ratio of 1:50 g / mL. The mixture was shaken at 2000 rpm for 15 min using a vortex shaker to mix evenly.

[0093] (3) A composite enzyme method was used to extract dietary fiber from shiitake mushroom stems, and α-amylase, protease, and glucosidase were added in sequence for step-by-step enzymatic hydrolysis. The specific steps included: adding 0.5 g, 8000 U / g, pH 5.0 α-amylase to the solution obtained in step (2), and placing the mixture in a constant temperature oscillator at a constant temperature of 65°C and an oscillation frequency of 100 rpm for reaction for 40 minutes. After cooling to 55°C, 0.1 g, 100,000 U / g, pH 6.0 neutral protease was added, and the mixture was then placed in a constant temperature oscillator at 55°C and 100 rpm for reaction for 40 minutes. The pH of the reaction system was adjusted to 5.0, and 0.2 g, 20,000 U / g glucosidase was added, and the mixture was then placed in a constant temperature oscillator at 55°C and 100 rpm for reaction for 40 minutes. The pH was kept stable during the enzymatic hydrolysis process, and the enzyme was inactivated in a boiling water bath for 15 minutes after enzymatic hydrolysis.

[0094] (4) Alcohol precipitation purification: The enzymatic hydrolysate from step (3) was collected and centrifuged at 5000×g for 20 min to separate the supernatant and precipitate. The supernatant and precipitate were washed three times with 80°C hot water and 95% ethanol, respectively, and then filtered. The precipitate was collected and freeze-dried to obtain the modified Lentinus edodes stem dietary fiber.

[0095] (5) Preparation of Lentinus edodes stem dietary fiber-wheat mixed flour: 15% modified Lentinus edodes stem dietary fiber was added to wheat flour and mixed evenly to form wheat mixed flour.

[0096] (6) Mixing: 160 g of wheat flour mixture was mixed with 100 mL of yeast aqueous solution (2%, w / w), and stirred at medium speed until a smooth and uniform dough was formed.

[0097] (7) Shaping: Cut the dough into 20g pieces and knead them into round shapes.

[0098] (8) Proofing: The dough obtained in step (6) was placed in a proofing box at 37°C and a humidity of 85% for 30 minutes.

[0099] (9) Steaming: Steam the dough fermented in step (7) for 30 minutes to obtain high-fiber steamed buns with slow digestion function.

[0100] Example 3

[0101] To address the quality issues of shiitake mushroom stem dietary fiber, such as a rough texture, poor palatability, and hard texture, when added directly to wheat flour, this embodiment proposes a method for processing high-fiber steamed buns that improves the texture of traditional wheat steamed buns and has a slow-digesting function. The steamed buns with a slow-digesting function are mainly prepared by mixing shiitake mushroom stem dietary fiber modified by low-moisture extrusion technology with wheat flour, and specifically include the following steps:

[0102] (1) Preparation of extruded shiitake mushroom stems: The shiitake mushroom stems were air-dried at 45°C and pulverized, passed through a 60-mesh sieve, and the moisture content was adjusted to 10%. The powder was placed in the feed bin of a low-moisture extrusion equipment. The extrusion heat-melting temperature was set at 90°C, the screw speed was set at 200 rpm, and the feed rate was set at 20 g / min to produce extruded shiitake mushroom stems.

[0103] (2) The squeezed shiitake mushroom stems were dissolved in a phosphate buffer solution with a concentration of 0.02 mol / L and a pH of 7.0, with a solid-liquid ratio of 1:30 g / mL. The mixture was shaken at 3000 rpm for 10 min using a vortex shaker to mix evenly.

[0104] (3) A composite enzyme method was used to extract dietary fiber from shiitake mushroom stems, and α-amylase, protease, and glucosidase were added in sequence for step-by-step enzymatic hydrolysis. The specific steps included: adding 2.0 g, 2000 U / g, pH 6.0 α-amylase to the solution obtained in step (2), and placing the mixture in a constant temperature oscillator at a constant temperature of 60°C and an oscillation frequency of 300 rpm for reaction for 20 minutes. After cooling to 50°C, 2.0 g, 5000 U / g, pH 7.0 neutral protease was added, and the mixture was then placed in a constant temperature oscillator at 50°C and 300 rpm for reaction for 20 minutes. The pH of the reaction system was adjusted to 6.0, and 0.5 g, 2000 U / g glucosidase was added, and then placed in a constant temperature oscillator at 50°C and 300 rpm for reaction for 20 minutes. The pH was kept stable during the enzymatic hydrolysis process, and the enzyme was inactivated in a boiling water bath for 15 minutes after enzymatic hydrolysis.

[0105] (4) Alcohol precipitation purification: The enzymatic hydrolysate from step (3) was collected and centrifuged at 2000×g for 10 min to separate the supernatant and precipitate. The supernatant and precipitate were washed eight times with 60°C hot water and 95% ethanol, respectively, and then filtered. The precipitate was collected and freeze-dried to obtain the modified Lentinus edodes stem dietary fiber.

[0106] (5) Preparation of Lentinus edodes stem dietary fiber-wheat mixed flour: 15% modified Lentinus edodes stem dietary fiber was added to wheat flour and mixed evenly to form wheat mixed flour.

[0107] (6) Mixing: 160 g of wheat flour mixture was mixed with 80 mL of yeast aqueous solution (1.5%, w / w), and stirred at medium speed until a smooth and uniform dough was formed.

[0108] (7) Shaping: Cut the dough into 20g pieces and knead them into round shapes.

[0109] (8) Proofing: The dough obtained in step (6) was placed in a proofing box at 37°C and a humidity of 85% for 30 minutes.

[0110] (9) Steaming: Steam the dough fermented in step (7) for 30 minutes to obtain high-fiber steamed buns with slow digestion function.

Claims

1. A method for processing high-fiber steamed buns with slow digestion function, characterized in that: The following steps are involved: The moisture content of shiitake mushroom stem powder was adjusted to 10-40%, and extruded shiitake mushroom stems were prepared under the conditions of extrusion heat melting temperature of 90-130℃, screw speed of 150-200 rpm, and feeding rate of 20-40 g / min. dissolving the extruded and puffed shiitake mushroom stems in a phosphate buffer solution, and oscillating and mixing the mixture to obtain an extruded and puffed shiitake mushroom stem suspension; 0.5-2.0 g of α-amylase is added to the suspension of extruded shiitake mushroom stems, and the mixture is placed at a constant temperature of 60-70°C and an oscillation frequency of 100-300 rpm for 20-40 min. After being taken out and cooled to 50-60°C, 0.1-2.0 g of neutral protease is added, and the mixture is then placed at a constant temperature of 50-60°C and an oscillation frequency of 100-300 rpm for 20-40 min. Finally, the pH of the reaction system is adjusted to 5.0-7.0, and 0.2-1.0 g of glucosidase is added. The mixture is then placed at a constant temperature of 50-60°C and an oscillation frequency of 100-300 rpm for 20-40 min. The pH is kept stable during the enzymatic hydrolysis process, and the enzyme is inactivated for 5-15 minutes after the enzymatic hydrolysis to obtain an enzymatic hydrolyzate. Alcohol precipitation purification: collect the enzymatic hydrolysate from step (3), centrifuge it, separate the supernatant and the precipitate; wash it with 60-80°C hot water and 90-99% food-grade ethanol for more than 3 times, filter it after washing, collect the precipitate, and freeze-dry it to obtain the modified Lentinus edodes stem dietary fiber; Add modified shiitake mushroom stem dietary fiber to wheat flour and mix evenly to form shiitake mushroom stem dietary fiber-wheat mixed flour; The mixed flour of shiitake mushroom stem dietary fiber and wheat is mixed with a yeast aqueous solution and stirred until a smooth and uniform dough is formed; then the dough is formed, proofed and steamed to obtain a high-fiber steamed bun with slow digestion function.

2. The method for processing high-fiber steamed buns with slow digestion function according to claim 1, characterized in that: The preparation method of the mushroom stem powder comprises the following steps: drying the mushroom stems at a temperature below 50° C., crushing the mushroom stems, and passing the mixture through a 60-100 mesh sieve to obtain the mushroom stem powder.

3. The method for processing high-fiber steamed bread with slow digestion function according to claim 1, characterized in that: The concentration of the phosphate buffer is 0.02-0.1 mol / L, and the pH is 7.0-7.

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4. The method for processing high-fiber steamed buns with slow digestion function according to claim 1, characterized in that: In the step (2), the material-liquid ratio of the extruded mushroom stems to the phosphate buffer solution is 1:30-1:50 g / mL, and the oscillation is carried out at 1000-3000 rpm for 10-15 min.

5. The method for processing high-fiber steamed bread with slow digestion function according to claim 1, characterized in that: In the step (3), the α-amylase activity is 2000-8000 U / g, and the pH is 5.0-6.

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6. The method for processing high-fiber steamed bread with slow digestion function according to claim 1, characterized in that: In the step (3), the activity of the neutral protease is 5000-100000 U / g, and the pH is 6.0-7.

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7. The method for processing high-fiber steamed bread with slow digestion function according to claim 1, characterized in that: In the step (3), the activity of glucosidase is 2000-20000 U / g, and the pH is 5.0-7.

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8. The method for processing high-fiber steamed bread with slow digestion function according to claim 1, characterized in that: In the step (4), the centrifugal treatment is performed at 2000-5000 × g for 10-20 min.

9. The method for processing high-fiber steamed bread with slow digestion function according to claim 1, characterized in that: In the step (5), the amount of modified shiitake mushroom stem dietary fiber added is 2-15%.

10. The method for processing high-fiber steamed bread with slow digestion function according to claim 1, characterized in that: In the step (6), the mass percentage concentration of the yeast aqueous solution is 1% to 2%.

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