Extruded recombinant rice with uniform porous structure and preparation method thereof

Abstract

The present application provides a kind of extruded recombined rice with uniform porous structure and its preparation method, the extruded recombined rice with uniform porous structure is prepared by extrusion molding after mixing raw materials, freeze-drying, the raw materials include japonica rice powder and special Gu residue powder, the mass ratio of japonica rice powder and special Gu residue powder is 80-90:10-20, the content of dietary fiber in special Gu residue powder is greater than 40%, the mass ratio of soluble dietary fiber and insoluble dietary fiber is 1:7-11, the recombined rice has uniform porous structure inside, has good water absorption performance, has good cooking characteristics, and the cooking quality is equivalent to that of original rice, solves the problems of poor rehydration, large surface viscosity and poor taste of recombined rice.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of food processing, in particular to an extruded recombined rice with uniform porous structure and a preparation method thereof. BACKGROUND

[0002] Radix Puerariae is the tuber of Pueraria lobata (Willd.) Ohwi, which has been cultivated for more than a thousand years in China, Japan and other countries, and is now mainly distributed in tropical and temperate regions. There are 15-20 species of Pueraria worldwide, and 6 of them have medicinal value, among which P. lobata and P. thomsonii Benth are more common. Radix Puerariae is rich in starch, protein, dietary fiber and flavonoids, and has high medicinal and edible value. Therefore, it is listed in the first batch of "dual-purpose medicinal and edible products" list. Modern medicine shows that flavonoids are the main effective components of Radix Puerariae, and the content of flavonoids in P. lobata is 30-80 mg / g, which is about 10 times that of P. thomsonii. Studies have shown that flavonoids have the effects of lowering blood pressure, blood lipids and blood sugar, antiarrhythmia, proliferating osteocytes, anti-inflammatory, protecting liver, protecting nerves and anticonvulsant, and have been applied to the clinical treatment of cardiovascular system, diabetes, liver damage and other diseases.

[0003] At present, P. thomsonii is mainly used for Radix Puerariae starch processing, which removes the crude fiber in Radix Puerariae and greatly improves the edible taste, but the active ingredients including flavonoids are greatly reduced during the processing. In commercially available Radix Puerariae starch, almost no flavonoids including daidzin, genistin, and genistein and puerarin can be detected; while in hand-made Radix Puerariae starch, all the above active substances can be detected, but the retention rate of flavonoids in the raw material is less than 5%. P. lobata is mainly used for the preparation of Radix Puerariae tea and starch in food utilization, and the active substances in Radix Puerariae are dissolved in water to realize the utilization of active substances in Radix Puerariae. In the preparation process of Radix Puerariae starch, the starch in Radix Puerariae is extracted through crushing, washing and filtering, and the active substances in Radix Puerariae are lost with water during the washing process, while the dietary fiber is discarded as a byproduct, which greatly causes the waste of Radix Puerariae resources.

[0004] Extrusion is a multifunctional, low-cost and efficient processing method which integrates mixing, shaping and continuous maturation. During the process, the material undergoes various changes, such as starch gelatinization, starch denaturation, and degradation of various macromolecular substances into small molecules, thereby improving the quality of the product. In recent years, more and more studies have prepared restructured rice products with different nutrients through extrusion, such as low glycemic index, high fiber and selenium-rich restructured rice. In the preparation of restructured rice, it is found that although the shape of the commercially available restructured rice is similar to that of the original rice, the starch is gelatinized during the extrusion process and becomes a hard gel particle during the subsequent cooling process, resulting in a tight structure inside. During cooking, it is difficult for water to penetrate, so the restructured rice has poor rehydration, high surface viscosity, and poor taste. SUMMARY

[0005] To solve the problems in the background art, the present application provides an extruded restructured rice with uniform porous structure and a preparation method thereof, which has a uniform porous structure, good water absorption performance, good cooking characteristics, and cooking quality comparable to that of original rice, solving the problems of poor rehydration, high surface viscosity, and poor taste of restructured rice.

[0006] The technical solution of the present application to solve the above technical problems is as follows:

[0007] In a first aspect, the present application provides an extruded restructured rice with uniform porous structure, which is prepared by mixing raw materials, extruding and shaping, and freeze-drying. The raw materials include japonica rice powder and special-tuned guber residue powder, and the mass ratio of the japonica rice powder to the special-tuned guber residue powder is 80-90:10-20. The content of dietary fiber in the special-tuned guber residue powder is greater than 40%, and the mass ratio of soluble dietary fiber to insoluble dietary fiber is 1:7-11.

[0008] The principle of the present application is as follows:

[0009] After traditional restructured rice is extruded and gelatinized, it forms a hard rice grain, and it is difficult for water to quickly penetrate into the interior of the rice grain in a short time, which causes the restructured rice to be soft on the outside and hard on the inside. Although prolonging the soaking time can improve the water absorption rate of the restructured rice, it can cause the external viscosity to be too large and the taste to decrease. In the present application, soluble dietary fiber and insoluble dietary fiber are added to the restructured rice in a target ratio of guber residue powder, and the restructured rice is prepared by combining the shaping and freeze-drying technology. A uniform porous structure is formed in the restructured rice, which has good water absorption performance. Compared with commercially available restructured rice, the cooking time is reduced, the water absorption rate, the cooking loss rate and the surface viscosity of the restructured rice are reduced, the hardness is improved, the taste of the restructured rice is improved, and the problems of poor rehydration, high surface viscosity and poor taste of the restructured rice are solved.

[0010] The applicant's research has found that the ratio of soluble dietary fiber to insoluble dietary fiber has a significant impact on the water absorption rate, cooking time, and textural quality of the reconstituted rice obtained from it. Through in-depth analysis of the properties of insoluble dietary fiber (IDF) and soluble dietary fiber (SDF), the applicant discovered that soluble dietary fiber has colloidal properties and a high water absorption rate, while insoluble dietary fiber, while having water absorption properties, is insoluble in water. After extensive research and exploration, the applicant discovered that preparing reconstituted rice with specially blended kudzu vine residue powder and polished japonica rice ingredients at a certain ratio (a weight ratio of soluble dietary fiber to insoluble dietary fiber of 1:7-11) can fully utilize the properties of IDF and SDF. Based on the synergistic effect of SDF and IDF, the reconstituted rice obtained thereby has optimal texture, porosity, and pore size, resulting in the reconstituted rice having optimal textural properties and cooking quality after cooking.

[0011] Although kudzu root residue generally contains a large amount of kudzu root dietary fiber, the ratio of soluble dietary fiber to insoluble dietary fiber in the kudzu root residue obtained through conventional processing does not meet the ratio requirements of the reconstituted rice of the present invention. The present invention specifically adjusts the ratio of SDF and IDF in kudzu root residue powder before use. Based on a certain ratio of specially adjusted kudzu root residue powder and polished round-grained rice, the extruded reconstituted rice prepared thereby has a uniform porous structure, a cross-sectional porosity of 15% to 25%, an average pore diameter of 50 to 150 μm, and a moderate porosity and pore size. It has good water absorption and good cooking properties. The surface viscosity and hardness of the reconstituted rice after cooking are moderate, and the cooking quality is comparable to that of the original rice. Compared with commercially available reconstituted rice, not only is the dietary fiber content greatly increased, changing the nutritional structure of traditional rice, which is mainly starch, but the cooking quality and taste are also greatly improved, becoming closer to that of the original rice.

[0012] Beneficial effects:

[0013] The reconstituted rice obtained by the present invention has a uniform porous structure, a cross-sectional porosity of 15% to 25%, and an average pore size of 50 to 150 μm. The porosity and pore size are moderate, resulting in good water absorption and excellent cooking properties. The reconstituted rice after cooking has moderate surface viscosity and hardness, and its cooking quality is comparable to that of the original rice. Furthermore, compared to commercially available reconstituted rice, not only is its dietary fiber content significantly increased, changing the traditional starch-based nutritional structure of rice, but its cooking quality and taste are also significantly improved, becoming closer to that of the original rice.

[0014] Moreover, kudzu residue, as one of the main by-products in kudzu root processing, is generally discarded directly. The present invention creatively mixes the kudzu residue and applies it to extruded reconstituted rice, thereby realizing the comprehensive utilization of kudzu root processing by-products with low cost and high economic value, and can be implemented on a large scale.

[0015] According to the above scheme, the dietary fiber content of the recombinant rice is 6.5wt%-15wt%.

[0016] According to the above scheme, the particle size of the special adjusted gorgon powder is 50-150μm, the water holding capacity is 1-5g / g, and the water absorption expansion capacity is 2-6mL / g.

[0017] According to the above scheme, the special adjusted gorgon powder is prepared by the following method: the by-product gorgon of gorgon root starch extraction is crushed, washed with water, and ground to obtain gorgon powder with a particle size of 50-150μm, the soluble dietary fiber extracted in the water washing process is compounded with the gorgon powder to obtain the adjusted gorgon powder meeting the target requirements.

[0018] The gorgon is crushed and washed to remove most of the starch, and the obtained gorgon powder contains rich dietary fiber, the content of which is between 40wt% and 65wt%, and the content of gorgon root flavonoids is 1-8mg / g.

[0019] According to the above scheme, the cross-sectional porosity of the extruded recombinant rice is 15%-25%, and the average pore size is 50-150μm.

[0020] According to the above scheme, the raw material further includes gorgon root concentrated juice, and the mass ratio of the gorgon root concentrated juice to the japonica rice powder is 5-15:80-90, and the content of gorgon root flavonoids in the gorgon root concentrated juice is 20-60mg / mL.

[0021] The gorgon root concentrated juice is rich in gorgon root flavonoids, including gorgonin, daidzin, daidzein, genistin, etc., and the mass ratio of gorgonin, daidzin, daidzein and genistin is 20-25:10-15:5-10:1-12, and the addition of gorgon root concentrated juice in the recombinant rice can increase the content of active substances and antioxidant performance in the recombinant rice, and significantly improve the nutritional value of the recombinant rice.

[0022] According to the above scheme, the gorgon root concentrated juice comes from the crushing and pressing section of the gorgon powder processing stage and is obtained by filtering and concentrating.

[0023] According to the above scheme, the content of gorgon root flavonoids in the recombinant rice is 2-5mg / g, and the antioxidant DPPH is 35-70mgTECA / g.

[0024] According to the above scheme, the weight parts of each raw material component are as follows: japonica rice powder 80-90 parts, special adjusted gorgon powder 10-20 parts, and gorgon root concentrated juice 5-15 parts.

[0025] In a second aspect, the application provides a preparation method of the extruded recombined rice with uniform porous structure. Raw materials are mixed uniformly, water is added to adjust the moisture content of the materials to 25-30%, the materials are formed again in a screw extruder, the molten materials after extrusion are cut into rice grains, then the water content is reduced to below 8% by freezing at below-15°C and using conventional drying methods, to obtain the extruded recombined rice with uniform porous structure.

[0026] According to the above scheme, the freezing temperature is between-15°C and-80°C.

[0027] According to the above scheme, the screw rotation speed of the extruder is 20-40 Hz, the extrusion temperature is 90-110°C, and the feeding speed is 20-50 kg / h.

[0028] The application has the following beneficial effects:

[0029] The recombined rice provided by the application has uniform porous structure, moderate porosity and pore size, good water absorption performance, good cooking characteristics, cooking quality comparable to that of original rice, and low cooking loss rate, solving the problems of poor rehydration, large surface viscosity and poor taste of recombined rice. Compared with commercially available recombined rice, the dietary fiber content is greatly improved, the nutritional structure of traditional rice mainly based on starch is changed, and the cooking quality and taste are greatly improved, and the recombined rice is more similar to the original rice.

[0030] The comprehensive utilization of the processing by-products of ginseng roots is realized, and the cost is low and the economic value is high, so that large-scale implementation can be realized.

[0031] In the application, the special ginseng residue powder is added to the recombined rice, and then the recombined rice with uniform porous structure is prepared by freezing and coupling drying technology after extrusion molding, the preparation method is simple and easy to operate, the raw materials are simple and easy to obtain, and large-scale implementation can be realized. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 Figures A1, A2 and A3 are photographs and cross-sectional electron micrographs of the original rice, and figures B1, B2 and B3 are photographs and cross-sectional electron micrographs of commercially available recombined rice;

[0033] Figure 2 Figures A1, A2 and A3 are photographs and cross-sectional electron micrographs of the recombined rice prepared in Example 4, and figures B1, B2 and B3 are photographs and cross-sectional electron micrographs of the recombined rice prepared in Example 2. DETAILED DESCRIPTION

[0034] The principles and characteristics of the application are described below in combination with the drawings and specific examples, and the examples are only used to explain the application and are not used to limit the scope of the application.

[0035] It should be noted that in the description of the embodiments of the present application, the description of the term "some specific embodiments" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the illustrative description of the above-mentioned terms does not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0036] The present application provides a kind of extruded recombined rice with uniform porous structure, which is prepared by mixing raw materials and then extruding, freeze-drying, the raw materials include japonica rice powder and special tune Guba residue powder, the mass ratio of japonica rice powder and special tune Guba residue powder is 80-90:10-20, the content of dietary fiber in the special tune Guba residue powder is greater than 40%, and the mass ratio of soluble dietary fiber and insoluble dietary fiber is 1:7-11.

[0037] Preferably, the dietary fiber content of the recombined rice is 6.5wt%-15wt%.

[0038] Preferably, the particle size of the special tune Guba residue powder is 50-150 μm, the water holding capacity is 1-5 g / g, and the water absorption swelling capacity is 2-6 mL / g.

[0039] Preferably, the special tune Guba residue powder is prepared by the following method: the by-product Guba residue of Gegen starch extraction is crushed, washed with water, and pulverized to obtain Guba residue powder with a particle size of 50-150 μm, the soluble dietary fiber extracted in the water washing process is compounded with the Guba residue powder to obtain the special tune Guba residue powder.

[0040] Preferably, the cross-sectional porosity of the recombined rice is 15%-25%, and the average pore size is 50-150 μm.

[0041] In some specific embodiments, the raw materials further include Gegen concentrated juice, the mass ratio of the Gegen concentrated juice to japonica rice powder is 5-15:80-90, and the content of Gegen flavones in the Gegen concentrated juice is 20-60 mg / mL.

[0042] Preferably, the Gegen concentrated juice is obtained by filtering and concentrating from the crushing and pressing section of the Gegen powder processing stage.

[0043] Preferably, the content of Gegen flavones in the recombined rice is 2-5 mg / g, and the antioxidant DPPH is 35-70 mg TECA / g.

[0044] Preferably, the weight parts of each raw material component are as follows: japonica rice powder 80-90 parts, special tune Guba residue powder 10-20 parts, and Gegen concentrated juice 5-15 parts.

[0045] The present invention provides a method for preparing the extruded recombinant rice with a uniform porous structure. The method comprises the following steps: uniformly mixing raw materials, adding water to adjust the moisture content of the materials to 25% to 30%, performing secondary molding of the materials in a screw extruder, cutting the extruded molten materials into rice grains, and then freezing the materials at a temperature below -15°C and then using a conventional drying method to reduce the moisture content to below 8%, thereby obtaining the extruded recombinant rice with a uniform porous structure.

[0046] Preferably, the freezing temperature is between -15°C and -80°C.

[0047] Preferably, the extruder screw speed is 20-40 Hz, the extrusion temperature is 90-110° C., and the feed rate is 20-50 kg / h.

[0048] Based on the above embodiments, the present invention is further described in the following specific examples. It should be understood that these examples are intended to illustrate the present invention only and are not intended to limit the scope of the present invention. Experimental methods in the following examples, where specific conditions are not specified, generally follow the conditions recommended by the manufacturer. Unless otherwise stated, percentages and parts are calculated by mass.

[0049] Example 1

[0050] The preparation method of the extruded recombinant rice with a uniform porous structure in this embodiment is as follows:

[0051] The kudzu root juice from the crushing and pressing stages of kudzu powder processing was concentrated to obtain kudzu root concentrated juice, in which the total content of kudzu root flavonoids was 25 mg / mL, and the composition ratio of puerarin, daidzein, daidzein and genistin in the kudzu root flavonoids was 20:10:5:3; the final by-product kudzu residue from kudzu starch extraction was crushed, washed and pulverized to prepare kudzu residue powder, with a dietary fiber content of 65 g / 100 g, a total flavonoid content of 2 mg / g, and a particle size of 125 μm; the soluble dietary fiber extracted during the washing process was compounded with the kudzu residue powder to obtain specially formulated kudzu residue powder, with a ratio of soluble dietary fiber (SDF) to insoluble dietary fiber (IDF) of 1:8, a water holding capacity of 2 g / g, and a water absorption swelling capacity of 3 mL / g.

[0052] The raw materials for preparing reconstituted rice consist of 15 parts of kudzu root flavonoid-rich concentrated juice, 10 parts of specially formulated kudzu residue powder rich in dietary fiber, and 80 parts of polished rice flour. The reconstituted rice is produced using a single-screw extruder. During extrusion, the material moisture content is 30%, the screw speed is 34 Hz, the feed rate is 25 kg / h, and the extrusion temperature is 110°C. After extrusion, the molten material is cut into rice grains. The wet reconstituted rice is frozen at -15°C and then dried using conventional methods to reduce the moisture content to below 8%.

[0053] Example 2

[0054] The preparation method of the extruded recombinant rice with a uniform porous structure in this embodiment is as follows:

[0055] The kudzu root juice from the crushing and pressing stages of kudzu powder processing was concentrated to obtain kudzu root concentrated juice, in which the total content of kudzu root flavonoids was 40 mg / mL, and the composition ratio of puerarin, daidzein, daidzein and genistin in the kudzu root flavonoids was 23:11:7:1; the final by-product kudzu residue from kudzu starch extraction was crushed, washed and pulverized to prepare kudzu residue powder, with a dietary fiber content of 55 g / 100 g, a total flavonoid content of 6 mg / g, and a particle size of 50 μm; the soluble dietary fiber extracted during the washing process was compounded with the kudzu residue powder to obtain specially formulated kudzu residue powder, in which the ratio of soluble dietary fiber (SDF) to insoluble dietary fiber (IDF) was 1:10, the water holding capacity of the specially formulated kudzu residue powder was 4 g / g, and the water absorption swelling capacity was 6 mL / g.

[0056] The raw materials for preparing reconstituted rice consist of 5 parts of puerarin-rich kudzu root concentrate, 20 parts of specially formulated kudzu residue powder rich in dietary fiber, and 90 parts of polished rice flour. The reconstituted rice is produced using a single-screw extruder. During extrusion, the material moisture content is 25%, the screw speed is 30 Hz, the feed rate is 44 kg / h, and the extrusion temperature is 90°C. After extrusion, the molten material is cut into rice grains. The wet reconstituted rice is frozen at -15°C and then dried using conventional methods to reduce the moisture content to below 8%.

[0057] Example 3

[0058] The preparation method of the extruded recombinant rice with a uniform porous structure in this embodiment is as follows:

[0059] The kudzu root juice from the crushing and pressing stages of kudzu powder processing was concentrated to obtain kudzu root concentrated juice, in which the total content of kudzu root flavonoids was 28 mg / mL, and the composition ratio of puerarin, daidzein, daidzein and genistin in the kudzu root flavonoids was 20:13:5:4; the kudzu residue, the final by-product from kudzu starch extraction, was crushed, washed and pulverized to prepare kudzu residue powder, with a dietary fiber content of 42 g / 100 g, a total flavonoid content of 8 mg / g, and a kudzu residue particle size of 80 μm; the soluble dietary fiber extracted during the washing process was compounded with the kudzu residue powder to obtain specially formulated kudzu residue powder, with a ratio of soluble dietary fiber (SDF) to insoluble dietary fiber (IDF) of 1:10, a water holding capacity of 3 g / g, and a water absorption swelling capacity of 6 mL / g.

[0060] The raw material for preparing the recombined rice is composed of 9 parts of puerariae radix concentrated juice rich in puerariae radix flavones, 18 parts of special pueraria residue powder rich in dietary fiber, and 85 parts of japonica rice powder. The recombined rice is prepared by using a single screw extruder. During the extrusion process, the water content of the material is 27%, the screw rotation speed of the extruder is 50 Hz, the feeding speed is 33 kg / h, and the extrusion temperature is 100°C. After the extrusion, the molten material is cut into rice grains. The wet recombined rice is frozen at -15°C and then dried by using a conventional drying method to reduce the water content to below 8%.

[0061] Example 4

[0062] The preparation method of the extruded recombined rice with a uniform porous structure in this example is as follows:

[0063] The puerariae radix concentrated juice is obtained by concentrating the puerariae radix juice from the crushing and pressing section of the puerariae radix powder processing stage. The total content of puerariae radix flavones in the concentrated juice is 55 mg / mL. The composition ratio of puerarin, daidzin, daidzein, and genistin in the puerariae radix flavones is 23:12:7:2. The pueraria residue, which is the final by-product from the extraction of puerariae radix starch, is made into pueraria residue powder after crushing, water washing, and pulverization. The dietary fiber content of the pueraria residue powder is 56 g / 100 g, the total flavone content is 6 mg / g, and the particle size of the pueraria residue powder is 80 μm. The soluble dietary fiber extracted during the water washing process is compounded with the pueraria residue powder to obtain special pueraria residue powder. The ratio of soluble dietary fiber (SDF) to insoluble dietary fiber (IDF) in the special pueraria residue powder is adjusted to 1:8 after compounding. The water holding capacity of the special pueraria residue powder is 5 g / g, and the water absorption swelling capacity is 2 mL / g.

[0064] The raw material for preparing the recombined rice is composed of 9 parts of puerariae radix concentrated juice rich in puerariae radix flavones, 18 parts of special pueraria residue powder rich in dietary fiber, and 85 parts of japonica rice powder. The recombined rice is prepared by using a single screw extruder. During the extrusion process, the water content of the material is 27%, the screw rotation speed of the extruder is 50 Hz, the feeding speed is 33 kg / h, and the extrusion temperature is 100°C. After the extrusion, the molten material is cut into rice grains. The wet recombined rice is frozen at -15°C and then dried by using a conventional drying method to reduce the water content to below 8%.

[0065] Example 5

[0066] In this example, the raw material is not added with puerariae radix concentrated juice, and the other conditions are the same as in Example 4.

[0067] Comparative Example 1

[0068] In this comparative example, the raw material is not added with pueraria residue powder, and the other conditions are the same as in Example 4.

[0069] Comparative Example 2

[0070] The difference from Example 2 is that the dietary fiber content of the kudzu vine residue powder used is 60 g / 100 g, the total flavonoids content is 3 mg / g, and the particle size of the kudzu vine residue powder is 120 μm; the ratio of soluble dietary fiber (SDF) to insoluble dietary fiber (IDF) in the kudzu vine residue powder is 1:20, the water holding capacity of the kudzu vine residue powder is 3 g / g, and the water absorption expansion capacity is 5 mL / g. Other aspects are the same as Example 2.

[0071] Comparative Example 3

[0072] The difference from Example 2 is that the dietary fiber content of the kudzu vine residue powder used is 60 g / 100 g, the total flavonoids content is 3 mg / g, and the particle size of the kudzu vine residue powder is 115 μm; the ratio of soluble dietary fiber (SDF) to insoluble dietary fiber (IDF) in the kudzu vine residue powder is 1:0.5, the water holding capacity of the kudzu vine residue powder is 10 g / g, and the water absorption expansion capacity is 4 mL / g. Other details are the same as in Example 2.

[0073] The commercially available recombinant rice, original rice and the recombinant rice prepared in Example 2 and Example 4 of the present invention were subjected to microscopic characterization. The results are as follows: Figure 1 and Figure 2 shown.

[0074] Figure 1 Figures A1, A2, and A3 are photos and cross-sectional electron micrographs of the original rice, respectively; and Figures B1, B2, and B3 are photos and cross-sectional electron micrographs of the commercially available recombinant rice, respectively. The commercially available recombinant rice and the original rice are transparent. The cross-section of the original rice has a rough surface, and the small particles are rice starch particles. There are a few pores between these particles, which are conducive to the infiltration of water molecules. Steaming gives it a good quality. The cross-section of the commercially available recombinant rice is smooth and compact, making it difficult for water to penetrate into the interior of the recombinant rice. Therefore, in order to allow water to penetrate the interior of the recombinant rice and reduce the "sandwich" problem, the steaming time is usually extended to allow it to absorb enough water, resulting in a high water absorption rate and expansion rate, which in turn leads to a lower hardness and a higher viscosity.

[0075] Figure 2 Figures A1, A2, and A3 show the morphology of the recombinant rice prepared in Examples 2 and 4 of the present invention, with Figures A1, A2, and A3 respectively showing a photograph and an electron micrograph of the recombinant rice prepared in Example 4, and Figures B1, B2, and B3 respectively showing a photograph and an electron micrograph of the recombinant rice prepared in Example 2. The recombinant rice in Examples 2 and 4 is brown due to the addition of kudzu root concentrate, and the color deepens with increasing flavonoid content in the kudzu root concentrate. The cross-section of the extruded recombinant rice exhibits numerous pores, primarily due to the dietary fiber in the specially formulated kudzu residue powder and freeze-drying. These porous structures serve as channels for water to penetrate the recombinant rice, improving its rehydration properties and surface viscosity.

[0076] The active substance content and pore structure of the recombinant rice prepared in Examples 1-5, Comparative Examples 1-3, commercially available recombinant rice and original rice were measured, and the results are shown in Table 1.

[0077] Table 1 Active substance content and pore parameters of recombinant rice and original rice

[0078]

[0079]

[0080] The cooking properties and texture properties of the recombinant rice prepared in Examples 1-5, Comparative Examples 1-3, commercially available recombinant rice and original rice were measured, and the measurement methods are as follows:

[0081] Cooking time: A certain amount of rice sample was placed in water at 95°C, and the timing was started at the same time. A little was taken out every certain time, and whether there was a white core was observed by cutting it open. After the white core disappeared, the time required was recorded, which was the cooking time of the rice sample.

[0082] Cooking properties: 5 g of sample (M0) was weighed in a constant weight centrifuge tube (M1), 25 ml of distilled water over 90°C was added, and it was cooked for the above cooking time. After cooking, it was cooled to room temperature and centrifuged at 4000 r / min for 10 min. The supernatant was discarded, and the total mass of the centrifuge tube and the precipitate (M2) was weighed. Then the centrifuge tube and the precipitate were dried to constant weight in an oven at 105°C (M3). The water absorption rate and the loss rate were calculated according to the following formula,

[0083]

[0084]

[0085] According to the above method, 20 g of sample (M0) was cooked, and the rice grains and rice soup were separated by centrifugation. The volume V0 and V1 of the recombinant rice before and after cooking were measured by the millet displacement method, and the swelling rate was calculated according to the following formula,

[0086]

[0087] Texture measurement: About 10 g of sample rice was weighed into an aluminum box, 15 ml of distilled water was added, and it was placed in a preheated steamer for 15 min. After the fire was turned off, it was steamed for another 5 min. After cooking, it was cooled to room temperature and wrapped with tin paper to prevent water loss. Four full and undamaged rice grains were selected for measurement on the texture analyzer platform. TPA probe model: P / 36R; pre-measurement speed: 1 mm / s, measurement speed: 2 mm / s, post-measurement speed: 1 mm / s; trigger force: 5 g; compression strength: 50%; time interval: 5 s.

[0088] The results of cooking properties and texture tests are shown in Table 2 below:

[0089] Table 2 Cooking and texture properties of different recombined rice

[0090]

[0091] From the data in Table 1 and Table 2, it can be seen that the addition of the concentrated geng root juice can improve the content of active substances and the antioxidant property of the recombined rice, and the ratio of soluble dietary fiber and insoluble dietary fiber can affect the pore structure including porosity and pore size, and the addition of the specially adjusted geng residue powder can improve the pore structure of the recombined rice while improving the content of dietary fiber, thereby regulating the water absorption performance and the cooking quality of the recombined rice.

[0092] Compared with the commercially available recombined rice, the recombined rice of the present application has a shorter cooking time, a low cooking loss rate, better cooking and texture properties, and better quality. From the data of the examples and the comparative examples in Table 1 and Table 2, it can be seen that the addition of the specially adjusted geng residue powder and the ratio of soluble dietary fiber and insoluble dietary fiber in the specially adjusted geng residue powder can greatly affect the texture, porosity and pore size of the recombined rice, thereby affecting the water absorption performance, the cooking properties, the cooking loss rate, the texture properties of the cooked rice, and the hardness and taste of the recombined rice. When the ratio of soluble dietary fiber and insoluble dietary fiber in the specially adjusted geng residue powder is between 1:7 and 1:11, and the ingredients such as japonica rice are combined and dried by the freezing coupling drying technology, the prepared recombined rice has good water absorption performance, optimal texture, porosity and pore size, and optimal cooking quality and texture properties.

[0093] The above description is only the preferred embodiments of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An extruded recombinant rice having a uniform porous structure, characterized in that: The raw materials are mixed, extruded, and freeze-dried to obtain the product. The raw materials include polished rice flour and specially prepared kudzu vine residue powder. The mass ratio of the polished rice flour to the specially prepared kudzu vine residue powder is 80-90:10-20. The content of dietary fiber in the specially prepared kudzu vine residue powder is greater than 40%, and the mass ratio of soluble dietary fiber to insoluble dietary fiber is 1:7-11.

2. The extruded recombinant rice having a uniform porous structure according to claim 1, characterized in that: The dietary fiber content of the extruded recombinant rice is 6.5 wt% to 15 wt%.

3. The extruded recombinant rice with a uniform porous structure according to claim 1, characterized in that: The specially prepared kudzu residue powder has a particle size of 50 to 150 μm, a water holding capacity of 1 to 5 g / g, and a water absorption expansion capacity of 2 to 6 mL / g.

4. The extruded recombinant rice having a uniform porous structure according to claim 1, characterized in that: The specially formulated kudzu residue powder is prepared by the following method: kudzu residue, a byproduct of kudzu starch extraction, is crushed, washed, and pulverized to obtain kudzu residue powder with a particle size of 50 to 150 μm; and soluble dietary fiber extracted during the washing process is compounded with the kudzu residue powder to obtain the specially formulated kudzu residue powder.

5. The extruded recombinant rice with a uniform porous structure according to claim 1, characterized in that: The cross-sectional porosity of the extruded recombinant rice is 15% to 25%, and the average pore diameter is 50 to 150 μm.

6. The extruded recombinant rice having a uniform porous structure according to any one of claims 1 to 5, characterized in that: The raw materials further include kudzu root concentrated juice, the mass ratio of the kudzu root concentrated juice to polished rice flour is 5-15:80-90, and the content of kudzu root flavonoids in the kudzu root concentrated juice is 20-60 mg / mL.

7. The extruded recombinant rice having a uniform porous structure according to claim 6, characterized in that: The kudzu root concentrated juice comes from the crushing and pressing process of kudzu powder processing and is obtained through filtering and concentration.

8. The extruded recombinant rice with a uniform porous structure according to claim 6, characterized in that: The content of kudzu root flavonoids in the recombinant rice is 2-5 mg / g, and the antioxidant DPPH is 35-70 mg TECA / g.

9. The method for preparing extruded recombinant rice having a uniform porous structure according to any one of claims 1 to 8, characterized in that: The raw materials are mixed uniformly, water is added to adjust the moisture content of the materials to 25% to 30%, the materials are secondary molded in a screw extruder, the molten materials after extrusion are cut into rice grains, and then frozen below -15°C and dried to reduce the moisture content to below 8%, thereby obtaining the extruded reconstituted rice with a uniform porous structure.

10. The preparation method according to claim 9, characterized in that The screw speed of the extruder is 20-40 Hz, the extrusion temperature is 90-110° C., the feeding speed is 20-50 kg / h; and the freezing temperature is between -15° C. and -80° C.

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