Method for preparing anti-digestible long-shaped rice flour through cooperation of double-enzyme method and extrusion treatment

Abstract

The invention discloses a method for preparing anti-digestible long-shaped rice flour by utilizing a double-enzyme method in cooperation with extrusion treatment, and belongs to the technical field of functional food. The method for preparing anti-digestible long-shaped rice flour through cooperation of a double-enzyme method and extrusion treatment comprises the following steps: fully mixing long-shaped rice flour raw materials with medium-temperature alpha-amylase and pullulanase, carrying out primary extrusion debranching through a double-screw extruder, collecting the debranching long-shaped rice flour, and drying and crushing the long-shaped rice flour; and fully mixing the obtained debranched long-shaped rice flour with monoglyceride, and performing secondary extrusion by using a twin-screw extruder to realize the formation of the anti-digestible long-shaped rice flour in the secondary extrusion. According to the method, high-concentration long-shaped rice flour and high-efficiency preparation of digestion-resistant long-shaped rice flour in a short time are realized, and the problems of complex preparation process, low raw material concentration, long preparation time and low compounding efficiency of a starch-lipid compound are solved; the content of the RS5 type resistant starch is increased, and a theoretical basis and actual guidance are provided for continuous industrial production of the resistant starch.

Description

Technical Field

[0001] This invention belongs to the field of functional food technology, specifically relating to a method for preparing resistant indigo rice flour using a dual-enzyme synergistic extrusion process. Background Technology

[0002] In recent years, with the increasing awareness of healthy eating, functional foods have become an important direction for nutritional and food science research. Grains, as one of the world's most important foods, are not only a major source of carbohydrates but also a valuable source of dietary fiber, protein, minerals, and vitamins. However, due to their original starch structure, traditional grains and their products generally have a high glycemic index (GI) during digestion, which is detrimental to blood sugar control in diabetic patients. To improve the nutritional value of grains and their products, grain flour can be modified to obtain resistant grain flour, which can then be used to prepare low-GI grain products. Therefore, enhancing the resistantness of grains through specific processing techniques has become crucial for improving their nutritional value and functionality.

[0003] Rice flour contains proteins, lipids, polyphenols, and other substances. Developing RS5-type resistant starch through specific processing techniques is a suitable modification method. The formation of RS5-type resistant starch typically depends on the complexation of starch with lipids or other components (such as polyphenols). Amylose, as a polysaccharide with a highly regular molecular structure, has a relatively compact and stable molecular chain, easily forming complexes with small molecules such as lipids, thereby effectively reducing starch digestibility and converting it into resistant starch. However, most common grains, such as rice, wheat, and corn, naturally contain relatively low levels of amylose, limiting their ability to form RS5-type resistant starch. Increasing the amylose content has become an important way to improve the digestibility of grain flour. Appropriate processing techniques, especially physical (e.g., high-temperature, high-pressure treatment) or biological (e.g., enzymatic methods), can effectively increase the proportion of amylose in grains, thereby promoting the formation of RS5-type resistant starch in grain flour.

[0004] Traditional debranching methods not only produce low amylose content but also require further investigation into their applicability to cereal flours such as rice flour. For example, patent CN201910237245.9 discloses a method for preparing high amylose content, using a twin-screw extruder at an ultra-high speed of 1200 r / min to debranch corn starch. While this method utilizes high temperature and pressure to break down the starch molecule branches and increases the amylose content to some extent, the efficiency is low. Furthermore, rice flour contains some proteins, lipids, and polyphenols, which bind with the starch during extrusion, further limiting the debranching efficiency. Patent CN 119969532 A discloses a method for preparing debranched cereal flour-monoglyceride complexes using enzymatic hydrolysis and synergistic extrusion processing. A certain amount of pullulanase is added during the first extrusion debranching process, and the first extrusion temperature is set to a temperature compatible with both the optimal temperature of pullulanase and the gelatinization temperature of indica rice flour. This effectively increases the yield of amylose, but the amylose content at this point is 49.63%, and the content of resistant starch formed by subsequent compounding with monoglycerides is 43.27%, indicating significant room for improvement. In conclusion, further increasing the amylose content of indica rice flour, thereby increasing the yield of resistant starch, is of great significance for the production of RS5 type resistant starch. Summary of the Invention

[0005] To address the aforementioned problems, the purpose of this invention is to improve the resistance to digestion of indica rice flour and provide a more nutritionally balanced functional ingredient for the development of low-GI foods. To this end, a distributed extrusion method (extrusion debranching-extrusion compounding method) is proposed to achieve efficient and continuous industrial production of resistant-digestible grain flour. Extrusion is a temperature-controlled, high-shear, short-time, low-cost industrial continuous thermomechanical production technology with advantages of multifunctionality and high yield. This application achieves effective debranching of the grain flour through a first extrusion with the addition of medium-temperature α-amylase and pullulanase. Then, the debranched indica rice flour is mixed with monoglycerides and subjected to a second extrusion. The resistant-digestible indica rice flour is obtained in the second extrusion. By separating debranching and compounding into two steps, the resistance to digestion of indica rice flour is significantly improved, realizing the extrusion preparation of resistant-digestible indica rice flour.

[0006] To achieve the above objectives, the present invention first provides a method for preparing resistant-digestible indica rice flour using a dual-enzyme synergistic extrusion process, the method comprising the following steps:

[0007] (1) Mix the rice flour with medium-temperature α-amylase and pullulanase thoroughly, and add the mixture to the feeding end of a twin-screw extruder. After extrusion, collect the debranched rice flour, dry it in a drum, pulverize it and sieve it to obtain debranched rice flour.

[0008] (2) Mix the debranched indica rice flour obtained in step (1) with monoglycerides, add it to the feeding end of a twin-screw extruder, collect the extruded resistant indica rice flour after extrusion, dry it in a drum and then pulverize it.

[0009] In one embodiment of the present invention, the pullulanase is added at an amount of 60-100 U / g (w / w, based on dry cereal flour), and the pullulanase activity is 1000-2000 U / g.

[0010] In one embodiment of the present invention, the amount of the mesophilic α-amylase added is 1‰-3‰ (w / w, based on dry cereal flour), and the enzyme activity of the mesophilic α-amylase is 400-500 KNU-B / g.

[0011] In one embodiment of the present invention, in step (1), the moisture content of the material during extrusion is 50-60%.

[0012] In one embodiment of the present invention, in step (1), the rotational speed of the twin-screw extruder is 100-250 rpm; the temperatures of the six temperature zones of the extruder are respectively: zone 1 60-70℃, zone 2 60-70℃, zone 3 60-70℃, zone 4 60-70℃, zone 5 60-70℃, and zone 6 90-110℃.

[0013] In one embodiment of the present invention, the drum drying temperature in step (1) is 130-150°C, and the powder is passed through a 60-mesh sieve.

[0014] In one embodiment of the present invention, the monoglyceride in step (2) includes at least one of glyceryl monolaurate, glyceryl monopalmitate, glyceryl monostearate, glyceryl monooleate, glyceryl monolinoleate, glyceryl monobenzyl oleate, and glyceryl monolinolenic acid, preferably glyceryl monostearate.

[0015] In one embodiment of the present invention, the amount of monoglyceride added in step (2) is 2 to 8% of the mass of debranched indica rice flour.

[0016] In one embodiment of the present invention, in step (2), the moisture content of the material during extrusion is 40-50%.

[0017] In one embodiment of the present invention, in step (2), the rotational speed of the twin-screw extruder is 100-250 rpm; the temperatures of the six temperature zones of the extruder are as follows: Zone 1 temperature 40-50℃, Zone 2 temperature 60-70℃, Zone 3 temperature 80-90℃, Zone 4 temperature 80-90℃, Zone 5 temperature 100-110℃, and Zone 6 temperature 110-120℃.

[0018] In one embodiment of the present invention, the drum drying temperature in step (2) is 130-150°C, and the powder is passed through a 60-mesh sieve.

[0019] A second objective of this invention is to provide an resistant-digestible rice flour prepared according to the above method.

[0020] A third objective of this invention is to provide an application of the above-mentioned resistant indigo rice flour in the field of food preparation.

[0021] In one embodiment of the present invention, the application includes using the above-mentioned resistant indica rice flour to prepare food that helps improve high blood sugar and gut health, and prevent diabetes and colon cancer.

[0022] Beneficial effects:

[0023] (1) The two-step extrusion method of the present invention for preparing resistant indica rice flour utilizes extrusion technology and dual-enzyme method in synergy, and significantly reduces the digestibility of starch in indica rice flour through two extrusions.

[0024] (2) In the two-step extrusion process for preparing resistant indica rice flour, the present invention adds mesophilic α-amylase and pullulanase during the first extrusion step. The mesophilic α-amylase rapidly dilutes the starch, significantly reducing the viscosity of the system, allowing the starch to be fully debranched and increasing the amylose content. During the second extrusion, the debranched indica rice flour then reacts with dissolved monoglycerides to form resistant indica rice flour. This method is simple and efficient, and can efficiently complete the formation of thermally stable resistant indica rice flour under high starch concentration and in a short time. It overcomes the problems of complex preparation processes, high system viscosity, low debranching efficiency, long reaction time, and low complexation efficiency in existing technologies, and enables continuous production.

[0025] (3) The yield of the resistant indica rice flour prepared by the present invention is high, and with the increase of lipid addition and the adjustment of moisture, the content of resistant starch in the complex can reach up to 61.65%, which is much higher than the content of resistant starch in ordinary indica rice flour.

[0026] (4) This invention will provide a theoretical basis and practical guidance for the continuous industrial production of resistant cereal powder, and provide feasible strategies and methods for the industrial production of resistant starch and the development of low glycemic index foods. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the preparation process of the resistant indigo rice flour of the present invention. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] The twin-screw extruder used in this invention is from Shandong Zhennuo Intelligent Equipment (Shandong) Co., Ltd., model AHT36-28D. This extruder has a total of 6 heating zones.

[0030] The debranching enzyme used in this embodiment of the invention is pullulanase (enzyme activity of 10000 U / g), which was purchased from Jiangsu Boli Biological Products Co., Ltd.

[0031] The amylase used in this embodiment of the invention is a mesophilic α-amylase (enzyme activity of 480 KNU-B / g), purchased from Beijing Gaoruisen Technology Co., Ltd.

[0032] The rice flour used in this embodiment of the invention was purchased from Anhui Fengshuo Agricultural Technology Co., Ltd.

[0033] The monoglyceride used in this embodiment of the invention is glyceryl monostearate, which was purchased from Linyi Lusen Chemical Co., Ltd.

[0034] Example 1

[0035] A method for preparing resistant indigo rice flour using a dual-enzyme synergistic extrusion process, the method specifically comprising the following steps:

[0036] (1) Mix rice flour with medium-temperature α-amylase and pullulanase at 2‰ of the dry weight of rice flour (based on the dry weight of rice flour) thoroughly (based on the dry weight of rice flour), add to the feed end of a twin-screw extruder, set the material moisture content to 60wt%, the screw speed to 150rpm, and set the temperatures of zones I, II, III, IV, V and VI of the extruder (AHT36-28D) to 60, 65, 65, 65, 65 and 95℃ respectively, and start extrusion. Collect the debranched rice flour and dry it in a drum at 130℃. After pulverizing, pass it through a 60-mesh sieve to obtain debranched rice flour.

[0037] (2) The debranched indica rice flour extruded in step (1) is mixed with 2% glyceryl monostearate (based on the dry weight of the debranched indica rice flour) and added to the feeding end of a twin-screw extruder. The feed moisture content is set to 50 wt%. The temperatures of zones I, II, III, IV, V and VI of the extruder are set to 40, 60, 80, 80, 100 and 120°C, respectively. The screw speed is 150 rpm. Extrusion is started. The extruded debranched indica rice flour-glyceryl monostearate complex is collected, dried and pulverized.

[0038] Example 2

[0039] A method for preparing resistant indigo rice flour using a dual-enzyme synergistic extrusion process, the method specifically comprising the following steps:

[0040] (1) Mix the rice flour with 2‰ medium-temperature α-amylase and 60U / g pullulanase (based on the dry weight of the rice flour) thoroughly, add it to the feed end of a twin-screw extruder, set the material moisture content to 60wt%, the screw speed to 150rpm, and set the temperatures of the extruder (AHT36-28D) zones I, II, III, IV, V and VI to 60, 65, 65, 65, 65 and 95℃ respectively, and start extrusion. Collect the debranched rice flour and dry it in a drum at 130℃. After pulverizing, pass it through a 60-mesh sieve to obtain debranched rice flour.

[0041] (2) The debranched indica rice flour extruded in step (1) is mixed with 4% glyceryl monostearate (based on the dry weight of the debranched indica rice flour) and added to the feeding end of a twin-screw extruder. The feed moisture content is set to 50 wt%. The temperatures of zones I, II, III, IV, V and VI of the extruder are set to 40, 60, 80, 80, 100 and 120°C, respectively. The screw speed is 150 rpm. Extrusion is started, and the extruded debranched indica rice flour-monoglycerate complex is collected, dried and pulverized.

[0042] Example 3

[0043] A method for preparing resistant indigo rice flour using a dual-enzyme synergistic extrusion process, the method specifically comprising the following steps:

[0044] (1) Mix the rice flour with 2‰ medium-temperature α-amylase and 60U / g pullulanase (based on the dry weight of the rice flour) thoroughly, add it to the feed end of a twin-screw extruder, set the material moisture content to 60wt%, the screw speed to 150rpm, and set the temperatures of the extruder (AHT36-28D) zones I, II, III, IV, V and VI to 60, 65, 65, 65, 65 and 95℃ respectively, and start extrusion. Collect the debranched rice flour and dry it in a drum at 130℃. After pulverizing, pass it through a 60-mesh sieve to obtain debranched rice flour.

[0045] (2) The debranched indica rice flour extruded in step (1) is mixed with 6% glyceryl monostearate (based on the dry weight of the debranched indica rice flour) and added to the feeding end of a twin-screw extruder. The feed moisture content is set to 50 wt%. The temperatures of zones I, II, III, IV, V and VI of the extruder are set to 40, 60, 80, 80, 100 and 120°C, respectively. The screw speed is 150 rpm. Extrusion is started. The extruded debranched indica rice flour-glyceryl monostearate complex is collected, dried and pulverized.

[0046] Example 4

[0047] A method for preparing resistant indigo rice flour using a dual-enzyme synergistic extrusion process, the method specifically comprising the following steps:

[0048] (1) Mix the rice flour with 2‰ medium-temperature α-amylase and 60U / g pullulanase (based on the dry weight of the rice flour) thoroughly, add it to the feed end of a twin-screw extruder, set the material moisture content to 60wt%, the screw speed to 150rpm, and set the temperatures of the extruder (AHT36-28D) zones I, II, III, IV, V and VI to 60, 65, 65, 65, 65 and 95℃ respectively, and start extrusion. Collect the debranched rice flour and dry it in a drum at 130℃. After pulverizing, pass it through a 60-mesh sieve to obtain debranched rice flour.

[0049] (2) The debranched indica rice flour extruded in step (1) is mixed with 8% glyceryl monostearate (based on the dry weight of the debranched indica rice flour) and added to the feeding end of a twin-screw extruder. The feed moisture content is set to 50 wt%. The temperatures of zones I, II, III, IV, V and VI of the extruder are set to 40, 60, 80, 80, 100 and 120°C, respectively. The screw speed is 150 rpm. Extrusion is started. The extruded debranched indica rice flour-glyceryl monostearate complex is collected, dried and pulverized.

[0050] Example 5

[0051] A method for preparing resistant indigo rice flour using a dual-enzyme synergistic extrusion process, the method specifically comprising the following steps:

[0052] (1) Mix the rice flour with 2‰ medium-temperature α-amylase and 60U / g pullulanase (based on the dry weight of the rice flour) thoroughly, add it to the feed end of a twin-screw extruder, set the material moisture content to 60wt%, the screw speed to 150rpm, and set the temperatures of the extruder (AHT36-28D) zones I, II, III, IV, V and VI to 60, 65, 65, 65, 65 and 95℃ respectively, and start extrusion. Collect the debranched rice flour and dry it in a drum at 130℃. After pulverizing, pass it through a 60-mesh sieve to obtain debranched rice flour.

[0053] (2) The debranched indica rice flour extruded in step (1) is mixed with 6% glyceryl monostearate (based on the dry weight of the debranched indica rice flour) and added to the feeding end of a twin-screw extruder. The feed moisture content is set to 40 wt%. The temperatures of zones I, II, III, IV, V and VI of the extruder are set to 40, 60, 80, 80, 100 and 120°C, respectively. The screw speed is 150 rpm. Extrusion is started. The extruded debranched indica rice flour-monoglycerate complex is collected, dried and pulverized.

[0054] Example 6

[0055] A method for preparing resistant indigo rice flour using a dual-enzyme synergistic extrusion process, the method specifically comprising the following steps:

[0056] (1) Mix the rice flour with 2‰ medium-temperature α-amylase and 60U / g pullulanase (based on the dry weight of the rice flour) thoroughly, add it to the feed end of a twin-screw extruder, set the material moisture content to 60wt%, the screw speed to 150rpm, and set the temperatures of the extruder (AHT36-28D) zones I, II, III, IV, V and VI to 60, 65, 65, 65, 65 and 95℃ respectively, and start extrusion. Collect the debranched rice flour and dry it in a drum at 130℃. After pulverizing, pass it through a 60-mesh sieve to obtain debranched rice flour.

[0057] (2) The debranched indica rice flour extruded in step (1) is mixed with 6% glyceryl monostearate (based on the dry weight of the debranched indica rice flour) and added to the feeding end of a twin-screw extruder. The feed moisture content is set to 30 wt%. The temperatures of zones I, II, III, IV, V and VI of the extruder are set to 40, 60, 80, 80, 100 and 120°C, respectively. The screw speed is 150 rpm. Extrusion is started. The extruded debranched indica rice flour-glyceryl monostearate complex is collected, dried and pulverized.

[0058] Example 7

[0059] A method for preparing resistant indigo rice flour using a dual-enzyme synergistic extrusion process, the method specifically comprising the following steps:

[0060] (1) Mix the rice flour with 2‰ medium-temperature α-amylase and 60U / g pullulanase (based on the dry weight of the rice flour) thoroughly, add it to the feed end of a twin-screw extruder, set the material moisture content to 60wt%, the screw speed to 150rpm, and set the temperatures of the extruder (AHT36-28D) zones I, II, III, IV, V and VI to 60, 65, 65, 65, 65 and 95℃ respectively, and start extrusion. Collect the debranched rice flour and dry it in a drum at 130℃. After pulverizing, pass it through a 60-mesh sieve to obtain debranched rice flour.

[0061] (2) The debranched indica rice flour extruded in step (1) is mixed with 6% glyceryl monostearate (based on the dry weight of the debranched indica rice flour) and added to the feeding end of a twin-screw extruder. The feed moisture content is set to 20 wt%. The temperatures of zones I, II, III, IV, V and VI of the extruder are set to 40, 60, 80, 80, 100 and 120°C, respectively. The screw speed is 150 rpm. Extrusion is started. The extruded debranched indica rice flour-glyceryl monostearate complex is collected, dried and pulverized.

[0062] Comparative Example 1

[0063] Indica rice flour was thoroughly mixed with pullulanase at a concentration of 60 U / g (based on the dry weight of the indica rice flour), and fed into the feed end of a twin-screw extruder. The material moisture content was set to 60 wt%, the screw speed to 150 rpm, and the temperatures of zones I, II, III, IV, V, and VI of the extruder (AHT36-28D) were set to 60, 65, 65, 65, 65, and 95℃, respectively. Extrusion was then started, and the debranched indica rice flour was collected and dried in a drum at 130℃. After pulverization, it was passed through a 60-mesh sieve to obtain debranched indica rice flour.

[0064] Comparative Example 2

[0065] Indica rice flour was thoroughly mixed with pullulanase at a concentration of 100 U / g (based on the dry weight of the indica rice flour), and fed into the feed end of a twin-screw extruder. The material moisture content was set to 60 wt%, the screw speed to 150 rpm, and the temperatures of zones I, II, III, IV, V, and VI of the extruder (AHT36-28D) were set to 60, 65, 65, 65, 65, and 95℃, respectively. Extrusion was then started, and the debranched indica rice flour was collected and dried in a drum at 130℃. After pulverization, it was passed through a 60-mesh sieve to obtain debranched indica rice flour.

[0066] Comparative Example 3

[0067] Indica rice flour was thoroughly mixed with pullulanase at a concentration of 1000 U / g (based on the dry weight of the indica rice flour), and fed into the feed end of a twin-screw extruder. The material moisture content was set to 60 wt%, the screw speed to 150 rpm, and the temperatures of zones I, II, III, IV, V, and VI of the extruder (AHT36-28D) were set to 60, 65, 65, 65, 65, and 95℃, respectively. Extrusion was then started, and the debranched indica rice flour was collected and dried in a drum at 130℃. After pulverization, it was passed through a 60-mesh sieve to obtain debranched indica rice flour.

[0068] Comparative Example 4

[0069] Indica rice flour was thoroughly mixed with 2‰ medium-temperature α-amylase and 60 U / g pullulanase (based on the dry weight of the indica rice flour), and fed into the feed end of a twin-screw extruder. The material moisture content was set to 60 wt%, the screw speed was set to 150 rpm, and the temperatures of zones I, II, III, IV, V, and VI of the extruder (AHT36-28D) were set to 60, 65, 65, 65, 65, and 95℃, respectively. Extrusion was then started, and the debranched indica rice flour was collected and dried in a drum at 130℃. After pulverization, it was passed through a 60-mesh sieve to obtain debranched indica rice flour.

[0070] Table 1. Amylose content, rapidly digestible starch, and the combined content of slowly digestible starch and resistant starch in the samples.

[0071]

[0072] (Note: Different letters a, b, c indicate significant differences between the data groups, p < 0.05)

[0073] The amylose content in the samples was determined using the Megazyme amylose and amylopectin assay kit. As shown in Table 1, the amylose content in the indica rice flour was 22.38%, while the amylose content in Comparative Example 4 was 70.71%, an increase of 215.95%. The gelatinization temperature of starch granules in rice flour is between 60-80℃. In this study, the temperature was set at 65℃ during the first extrusion. At this temperature, the starch began to gelatinize, forming a gel-like starch solution. Medium-temperature α-amylase randomly sheared the α-1,4 glycosidic bonds in the starch, rapidly reducing the viscosity of the gel-like starch solution and providing a good liquefaction environment for pullulanase debranching. Simultaneously, pullulanase specifically hydrolyzed the α-1,6 glycosidic bonds at the branch points of amylopectin, cleaving the entire branch structure and exposing the internal α-1,4 glycosidic bonds, providing more binding sites for α-amylase. These two processes complement each other, allowing the starch to gelatinize and be fully debranched in the extrusion chamber, resulting in more amylose. In contrast, the amylose content of indica rice flour extruded and debranched using pullulanase alone was 52.06%, demonstrating the greater advantage of dual-enzyme treatment. Furthermore, in Comparative Example 3, even with pullulanase added at 1000 U / g, the resulting amylose content was only comparable to that of Comparative Example 4, further highlighting the effectiveness of combined dual-enzyme treatment in improving amylose yield.

[0074] The resistant starch content in the samples of each embodiment was determined using the Englyst in vitro simulated digestion method. The results are shown in Table 1. Table 1 shows that the content of slow-digesting starch + resistant starch initially increases and then decreases with increasing glyceryl monostearate content. The highest content of slow-digesting starch + resistant starch in the complex (61.65%) was achieved when the glyceryl monostearate content was 6%. As the glyceryl monostearate content increased to 8%, the lipid content in the complex became excessive. Excess lipids exhibited a self-aggregation effect, leading to a decrease in the lipid content that combined with the starch in the rice flour. Consequently, the resistant starch content decreased instead of increasing. Simultaneously, the moisture content of the material also significantly affected the formation of slow-digesting starch and resistant starch during the extrusion compounding process. Lower moisture levels limited the migration and distribution of lipid molecules, thus hindering the formation of the starch-lipid complex and consequently affecting the increase in the content of slow-digesting starch and resistant starch.

[0075] The method for preparing resistant indica rice flour of the present invention employs a two-stage extrusion combined with dual-enzyme treatment to achieve increased amylose content and formation of resistant indica rice flour with high cereal flour concentration and short processing time. The resistant starch content can reach 61.65%, providing a new raw material (cereal flour) and a feasible method for the industrial production of RS5 type resistant starch. This method is simple to operate, highly efficient, and can be applied to the continuous industrial production of RS5 type resistant starch.

[0076] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing resistant-digestible indica rice flour using a dual-enzyme synergistic extrusion process, characterized in that, The method includes the following steps: (1) Mix rice flour with medium-temperature α-amylase and pullulanase thoroughly, and add the mixture to the feeding end of a twin-screw extruder. After extrusion, collect the debranched rice flour, dry it in a drum, pulverize it and sieve it to obtain debranched rice flour. (2) The debranched indica rice flour obtained in step (1) is mixed with monoglyceride and added to the feeding end of a twin-screw extruder. After extrusion, the extruded debranched indica rice flour-monoglyceride complex is collected, dried in a drum, and then pulverized.

2. The method according to claim 1, characterized in that, Based on dry indica rice flour, the amount of pullulanase added is 60-100 U / g, and the enzyme activity of pullulanase is 1000-10000 U / g.

3. The method according to claim 1, characterized in that, Based on dry-base indica rice flour, the amount of mesophilic α-amylase added is 1‰-3‰, and the enzyme activity of the mesophilic α-amylase is 400-500 KNU-B / g.

4. The method according to claim 1, characterized in that, In step (1), the moisture content of the material during extrusion is 40-60%, the rotation speed of the twin-screw extruder is 100-250 rpm, the temperatures of the six temperature zones of the extruder are 60-70℃ in zone 1, 60-70℃ in zone 2, 60-70℃ in zone 3, 60-70℃ in zone 4, 60-70℃ in zone 5, and 90-110℃ in zone 6, the temperature of the drum drying is 130-150℃, and the material is pulverized and passed through a 60-mesh sieve.

5. The method according to claim 1, characterized in that, The monoglycerides mentioned in step (2) include at least one of glyceryl monolaurate, glyceryl monopalmitate, glyceryl monostearate, glyceryl monooleate, glyceryl monolinoleate, glyceryl monobenzyl oleate, and glyceryl monolinolenic acid, preferably glyceryl monostearate.

6. The method according to claim 1, characterized in that, The amount of monoglyceride added in step (2) is 2-8% of the mass of debranched indica rice flour.

7. The method according to claim 1, characterized in that, In step (2), the material moisture content is 40-50% during extrusion, and the rotation speed of the twin-screw extruder is 100-250 rpm. The temperatures of the six temperature zones of the extruder are as follows: Zone 1 temperature 40-50℃, Zone 2 temperature 60-70℃, Zone 3 temperature 80-90℃, Zone 4 temperature 80-90℃, Zone 5 temperature 100-110℃, Zone 6 temperature 110-120℃, and the roller drying temperature is 130-150℃. After crushing, the material passes through a 60-mesh sieve.

8. The resistant indica rice flour prepared by the method according to any one of claims 1 to 7.

9. The application of the resistant indwelling rice flour according to claim 8 in the field of food preparation.

10. The application according to claim 9, characterized in that, The applications include using resistant indica rice flour to prepare foods that help improve high blood sugar and gut health, and prevent diabetes and colon cancer.

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