Wuchang instant pure rice and double screw extrusion preparation method thereof

Abstract

The application discloses a kind of Wuchang pure rice instant rice and its double-screw extrusion preparation method, belong to the field of grain deep processing.The instant rice is only raw material with Wuchang rice flower fragrance broken rice, is made into by pure physical process such as smashing, precision moisture loss type, double-screw segmented extrusion gelatinization (sleeve 3-4 area 85~110 DEG C, 5-6 area 40~50 DEG C, 7-8 area 61~108 DEG C, end plate pressure 39.4~65.5 Bar, screw rotation speed 250~340 rpm), granulation, gradient drying shaping), without adding any auxiliary material.Product starch ripening degree is greater than or equal to 95%, boiling water is rehydrated for 5~8 minutes, cooking rice rate is greater than or equal to 2.8:1, finished product moisture content is 9.0%~10.0%, bulk density is 690~830 g / L, grain is neat, after brewing, cooking, frying, grain is distinct, quick-frozen reheating is stable, suitable for whole scene such as family instant food, pre-cooked fried rice, group meal and outdoor meal replacement, realize broken rice high-value utilization.

Description

Technical Field

[0001] This invention belongs to the field of food processing technology, specifically relating to a Wuchang pure rice instant rice and its twin-screw extrusion preparation method. Background Technology

[0002] With consumers' increasing demand for healthy eating and convenient cooking, the production of ready-to-eat rice products from broken rice has become an important development direction in the field of grain deep processing. Wuchang Daohuaxiang No. 2 rice, due to its unique aroma, taste, and high amylose content, has long been considered a representative of high-quality japonica rice. However, a large amount of broken rice generated during processing is difficult to sell as commercial rice due to its incomplete appearance, and is usually used at a low price for animal feed or brewing, resulting in a serious waste of high-end rice resources. To increase the added value of broken rice, existing technologies mostly employ twin-screw extrusion processes to reconstitute it into ready-to-eat rice grains, thereby achieving efficient resource utilization and product functional upgrades.

[0003] In related technologies, CN103519056B discloses a method for producing moisturizing instant rice. It uses broken rice as raw material, which is pre-cooked (gelatinization degree 40-60%), dried, pulverized, and then extruded using a twin-screw extruder. The resulting product has a certain chewiness, but it does not solve the problems of slow rehydration speed and structural collapse after high-temperature reheating. CN115812908A proposes a fast-cooking functional rice that improves nutrition and taste by adding various auxiliary materials such as selenium-enriched rice, high-amylose corn starch, inulin, and glyceryl monostearate. While this enhances functionality, it introduces non-rice components, which may raise consumer concerns about "artificial rice." Similarly, CN109170589A and CN112690403A both incorporate modified starch, guar gum, monoglycerides, or soy protein into broken rice base materials to enhance formability and anti-aging capabilities, while CN119586722A further introduces whole grains such as highland barley and quinoa to expand application scenarios. Although the above solutions improve the processing performance or nutritional composition of instant rice to some extent, they generally suffer from dependence on exogenous auxiliary materials and deviate from the essence of "pure rice," making it difficult to meet the current market's strong demand for clean labels and natural ingredients.

[0004] More critically, existing twin-screw extrusion processes generally lack precise and coordinated control of temperature, pressure, moisture, and screw speed. Traditional equipment often employs overall constant temperature or simple zone heating, failing to accurately control different stages of starch gelatinization (such as preheating and mixing, shearing gelatinization, and cooking and shaping). This results in uneven material cooking, with starch maturity typically below 85%. This not only leads to long brewing times (often exceeding 10 minutes) and an undercooked texture, but also makes the product prone to sticking, clumping, and loss of texture during subsequent steaming, cooking, or quick-freezing and reheating, severely impacting the eating experience and industrial suitability. Furthermore, commercially available recycled rice generally suffers from low yield (typically only 1:2.0~1:2.3) and large batch-to-batch quality fluctuations, making it difficult to meet the comprehensive requirements of stability, processing resistance, and high yield for all scenarios such as pre-prepared meals, group meals, and outdoor meal replacements. Therefore, how to achieve a balance of high degree of cooking, rapid rehydration, high cooking yield, and excellent reheat stability using only Wuchang Daohuaxiang broken rice as raw material without adding any food additives, auxiliary materials, or other grains has become a technical bottleneck that urgently needs to be overcome in this field. Summary of the Invention

[0005] The technical problem to be solved by this invention is to provide a method for preparing Wuchang pure rice instant rice and its twin-screw extrusion, which solves the problem of how to achieve high degree of cooking, fast rehydration, high cooking yield and excellent reheating stability by using only Wuchang Daohuaxiang broken rice as raw material without adding any food additives, auxiliary materials and other grains, through a purely physical process.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: Wuchang pure rice instant rice, which is made from broken rice produced by processing Daohuaxiang rice in Wuchang production area as the only raw material, and is made by pure physical twin-screw extrusion process without adding any food additives, auxiliary materials, other grains and starch colloids. Wuchang pure rice instant rice has the following performance indicators: Starch maturity ≥95%; The time for complete rehydration after steeping in boiling water is 5-8 minutes. The rice yield from steaming is ≥2.8:1, with a rice-to-water ratio of 1:2.8. The moisture content of the finished product is 9.0%~10.0%; The bulk density of the finished product is 690~830 g / L; The product is a regular elongated oval shape, with a length of 5 mm to 7 mm and a diameter of 2 mm to 3 mm.

[0007] Furthermore, Wuchang Pure Rice instant rice is distinct in grain after soaking, steaming, and frying, without becoming mushy or sticky. After quick-freezing and reheating, its taste and flavor do not significantly diminish. It is suitable for all scenarios, including home instant food, pre-made fried rice, group meals, and outdoor meal replacements.

[0008] Furthermore, the preparation method of Wuchang pure rice instant rice includes the following steps: (1) Raw material acceptance: Select Wuchang Daohuaxiang No. 2 broken rice that meets the requirements of GB / T 1354-2018 and GB 2715-2016, free from mold, insects, and odor, and the source of raw materials is traceable; (2) Washing and removing impurities: Wash the broken rice twice with clean water to remove sand, metal, chaff and other impurities; (3) Grinding: Grind the washed broken rice to 80-100 mesh to obtain uniform and fine rice flour; (4) Loss-in-weight precision moisture conditioning: Rice flour is quantitatively fed using a loss-in-weight feeder, and pure water is added simultaneously and precisely. The dry powder feeding rate is controlled at 10.2~12.5 kg / h, and the pure water addition flow rate is 40~55 mL / min, so that the overall moisture content of the material is controlled at 19%~22%. (5) Twin-screw segmented extrusion gelatinization: The conditioned material is fed into a twin-screw extruder. A segmented sleeve temperature control system is used to control the screw speed to 250~340 rpm, the main machine relative torque to 31%~42%, and the main machine power to 1.4~1.6 kW. Among them, the temperature of the preheating and mixing section in the sleeve 3-4 zone is 85℃~110℃, the temperature of the shearing and gelatinization section in the sleeve 5-6 zone is 40℃~50℃, the material temperature in the maturation and forming section in the sleeve 7-8 zone is 61℃~108℃, the end plate temperature is 69℃~78℃, and the end plate extrusion pressure is 39.4~65.5 Bar. (6) Pelletizing: The material is extruded through a porous rice grain mold and cut by a rotating cutter to produce regular rice grains that are 5-7 mm long and oval. (7) Gradient drying and shaping: A two-stage drying process is adopted. First, the product is pre-dried in a fluidized bed at 40℃~50℃ for 15~20min, and then deeply dried in a hot air dryer at 60℃~70℃. The final product moisture content is controlled at 9.0%~10.0%. (8) Cooling and sieving: After drying, the granules are cooled to room temperature and finely sieved to remove broken grains and powder, and the broken rice rate of the finished product is controlled to be ≤5.0%; (9) Metal detection and vacuum packaging: After passing the metal detector test, the finished product is vacuum sealed in food-grade composite packaging.

[0009] Furthermore, in step (3), the pulverization mesh size is 100 mesh.

[0010] Furthermore, in step (4), the dry powder feeding rate is 10.2 kg / h, the pure water addition flow rate is 42 mL / min, and the overall moisture content of the material is adjusted to 21%.

[0011] Furthermore, in step (5), the screw speed of the twin-screw extruder is 339 rpm, the temperature of the preheating and mixing section in the 3-4 zone of the sleeve is 110℃, the temperature of the shearing and gelatinization section in the 5-6 zone of the sleeve is 50℃, the material temperature of the curing and forming section in the 7-8 zone of the sleeve is 108℃, the end plate temperature is 78℃, and the end plate extrusion pressure is 39.4 Bar.

[0012] Furthermore, the sleeve of the twin-screw extruder is divided into eight independent temperature control zones along the material conveying direction from the feed end to the discharge die end. Among them, the sleeve zone 3-4 corresponds to the front area of ​​the sleeve near the feed inlet, the sleeve zone 5-6 corresponds to the middle area of ​​the sleeve, and the sleeve zone 7-8 corresponds to the rear area of ​​the sleeve near the discharge die.

[0013] Furthermore, in the two-stage drying process in step (7), the fluidized bed pre-drying temperature is 40℃, the drying time is 20 min, and the hot air dryer deep drying temperature is 60℃.

[0014] Furthermore, the starch obtained in step (7) has a cooking degree of ≥95%, a complete rehydration time of 5~8 minutes after being soaked in boiling water, a cooking yield of ≥2.8:1, and a bulk density of 690~830 g / L.

[0015] Furthermore, the metal detector detection standard in step (9) is: Fe ≥ 1.0 mm, non-ferrous metals ≥ 2.0 mm.

[0016] The beneficial effects of this invention are as follows: First, the product uses 100% pure Wuchang fragrant rice as raw material, processed entirely using physical methods without any food additives or auxiliary materials, completely eliminating consumers' cognitive resistance to "artificial rice" and "reconstituted rice." The product concept is clean, resulting in high market acceptance and strong competitiveness. Second, this invention simultaneously meets the two core scenarios of household instant hot water cooking and industrial production of pre-made fried rice. It is convenient to prepare, resistant to overcooking, and stable after quick-freezing and reheating, making it fully adaptable to all channels including families, restaurants, group meals, and pre-made dishes, with significant industrial application value. Third... The product yield is ≥2.8:1, which is more than 30% higher than that of ordinary rice, significantly reducing the raw material costs of ready-made dishes and catering channels, resulting in significant cost reduction and efficiency improvement; Fourth, this invention precisely binds the complete set of segmented temperature control, pressure, speed and moisture collaborative process parameters of the ALFU-30 equipment, forming a dual patented technology barrier of "product formula + equipment process", which is difficult to imitate; Fifth, this invention transforms the originally low-priced broken Wuchang rice into high-value-added instant food products, effectively extending the entire industrial chain of Wuchang rice, with significant economic and social benefits. Attached Figure Description

[0017] Figure 1 This is a schematic diagram showing the positional structure of each sleeve in the twin-screw extruder of the present invention.

[0018] Label Explanation: 1. Sleeve 3; 2. Sleeve 4; 3. Sleeve 5; 4. Sleeve 6; 5. Sleeve 7; 6. Sleeve 8. Detailed Implementation

[0019] To explain in detail the technical content, objectives, and effects of the present invention, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0020] Example 1.

[0021] The raw material is selected from Wuchang fragrant rice of the current year, which is washed, impurities removed, and then pulverized to 80 mesh. An MSDF-20 loss-in-weight feeder is used, with a dry powder feeding rate of 12.5 kg / h and a water flow rate of 55 mL / min, adjusting the material moisture content to 22%. The moisture-conditioned material is then fed into an ALFU-30 twin-screw extruder. Figure 1 The section distribution is shown, with the screw speed set at 250 rpm, sleeve zone 3-4 temperature at 85℃, sleeve zone 5-6 temperature at 40℃, material temperature in sleeve zone 7-8 at 61℃, end plate temperature at 69℃, and end plate pressure at 65.5 Bar. After the material is extruded through the die and granulated, it is pre-dried in an OTW fluidized bed at 45℃ for 18 min, and then deeply dried in a BDDA hot air dryer at 65℃ to a moisture content of 9.32%. After cooling and sieving, it is vacuum packaged. The test results of the obtained product are: starch maturity 95.5%, boiling water brewing time 7 min, rice yield 2.88:1, bulk density 789 g / L, broken rice rate 3.5%, and stable without sticking after quick-freezing and reheating.

[0022] Example 2.

[0023] The raw material is selected from Wuchang fragrant rice of the current year, which is washed, impurities removed, and then pulverized to 100 mesh. An MSDF-20 loss-in-weight feeder is used, with a dry powder feeding rate of 10.2 kg / h and a water flow rate of 42 mL / min, adjusting the material moisture content to 21%. The moisture-conditioned material is then fed into an ALFU-30 twin-screw extruder, combined with… Figure 1As shown, the screw speed was set at 339 rpm, the temperature in sleeve zones 3-4 was 110℃, the temperature in sleeve zones 5-6 was 50℃, the material temperature in sleeve zones 7-8 was 108℃, the end plate temperature was 78℃, and the end plate pressure was 39.4 Bar. After the material was extruded through the die and granulated, it was pre-dried in an OTW fluidized bed at 40℃ for 20 min, and then deeply dried in a BDDA hot air dryer at 60℃ to a moisture content of 9.18%. After cooling and sieving, it was vacuum packaged. The test results of the obtained product were: starch maturity 97.2%, boiling water brewing time 6 min, rice yield 2.98:1, bulk density 828 g / L, broken rice rate 3.0%, rich rice aroma, distinct grains, resistant to frying without breaking, and no sticking after quick freezing and reheating, which is the optimal implementation scheme.

[0024] Example 3.

[0025] The raw material is selected from Wuchang fragrant rice of the current year, which is washed, impurities removed, and then pulverized to 100 mesh. An MSDF-20 loss-in-weight feeder is used, with a dry powder feeding rate of 11.0 kg / h and a water flow rate of 48 mL / min, adjusting the material moisture content to 20%. The moisture-conditioned material is then fed into an ALFU-30 twin-screw extruder, referring to... Figure 1 The section definition was as follows: screw speed 300 rpm, sleeve zone 3-4 temperature 95℃, sleeve zone 5-6 temperature 45℃, sleeve zone 7-8 material temperature 85℃, end plate temperature 72℃, and end plate pressure 50.0 Bar. After extrusion and pelletizing, the material was pre-dried in an OTW fluidized bed at 50℃ for 15 min, then deeply dried in a BDDA hot air dryer at 70℃ to a moisture content of 10.2%. After cooling and sieving, it was vacuum-packed. The product test results showed: starch maturity 96.1%, boiling water steeping time 8 min, rice yield 2.90:1, bulk density 697 g / L, broken rice rate 2.7%, no mushy soup, and intact grains.

[0026] Performance test tables for the above three sets of embodiments.

[0027] The Wuchang pure rice instant rice and its preparation method provided by this invention can be widely used in the fields of instant food processing, pre-prepared vegetable production, group meal delivery, and outdoor meal replacement. The product uses Wuchang fragrant broken rice as raw material, realizing the high-value utilization of broken rice resources, with significant economic and social benefits, and is suitable for large-scale promotion and application in the food industry.

[0028] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent modifications made based on the content of the present invention specification and drawings, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A type of Wuchang pure rice instant rice, characterized in that, Wuchang Pure Rice Instant Rice uses broken rice from the processing of Wuchang fragrant rice as its sole raw material. It is made through a pure physical twin-screw extrusion process without adding any food additives, auxiliary materials, other grains, or starch colloids. Wuchang pure rice instant rice has the following performance indicators: Starch maturity ≥95%; The time for complete rehydration after steeping in boiling water is 5-8 minutes. The rice yield from steaming is ≥2.8:1, with a rice-to-water ratio of 1:2.

8. The moisture content of the finished product is 9.0%~10.0%; The bulk density of the finished product is 690~830 g / L; The product is a regular elongated oval shape, with a length of 5 mm to 7 mm and a diameter of 2 mm to 3 mm.

2. The Wuchang pure rice instant rice according to claim 1, characterized in that, Wuchang Pure Rice instant rice is distinct in grain after soaking, steaming, or frying, without becoming mushy or sticky. After quick-freezing and reheating, its taste and flavor do not significantly diminish. It is suitable for all scenarios, including home instant food, pre-made fried rice, group meals, and outdoor meal replacements.

3. A method for preparing Wuchang pure rice instant rice as described in claim 1 or 2, characterized in that, Includes the following steps: (1) Raw material acceptance: Select Wuchang Daohuaxiang No. 2 broken rice that meets the requirements of GB / T 1354-2018 and GB 2715-2016, free from mold, insects, and odor, and the source of raw materials is traceable; (2) Washing and removing impurities: Wash the broken rice twice with clean water to remove sand, metal, chaff and other impurities; (3) Grinding: Grind the washed broken rice to 80-100 mesh to obtain uniform and fine rice flour; (4) Loss-in-weight precision moisture conditioning: Rice flour is quantitatively fed using a loss-in-weight feeder, and pure water is added simultaneously and precisely. The dry powder feeding rate is controlled at 10.2~12.5 kg / h, and the pure water addition flow rate is 40~55 mL / min, so that the overall moisture content of the material is controlled at 19%~22%. (5) Twin-screw segmented extrusion gelatinization: The conditioned material is fed into a twin-screw extruder. A segmented sleeve temperature control system is used to control the screw speed to 250~340 rpm, the main machine relative torque to 31%~42%, and the main machine power to 1.4~1.6 kW. Among them, the temperature of the preheating and mixing section in the sleeve 3-4 zone is 85℃~110℃, the temperature of the shearing and gelatinization section in the sleeve 5-6 zone is 40℃~50℃, the material temperature in the maturation and forming section in the sleeve 7-8 zone is 61℃~108℃, the end plate temperature is 69℃~78℃, and the end plate extrusion pressure is 39.4~65.5 Bar. (6) Pelletizing: The material is extruded through a porous rice grain mold and cut by a rotating cutter to produce regular rice grains that are 5-7 mm long and oval. (7) Gradient drying and shaping: A two-stage drying process is adopted. First, the product is pre-dried in a fluidized bed at 40℃~50℃ for 15~20 min, and then deeply dried in a hot air dryer at 60℃~70℃. The final product moisture content is controlled at 9.0%~10.0%. (8) Cooling and sieving: After drying, the granules are cooled to room temperature and finely sieved to remove broken grains and powder, and the broken rice rate of the finished product is controlled to be ≤5.0%; (9) Metal detection and vacuum packaging: After passing the metal detector test, the finished product is vacuum sealed in food-grade composite packaging.

4. The preparation method according to claim 3, characterized in that, In step (3), the particle size of the powder is 100 mesh.

5. The preparation method according to claim 3, characterized in that, In step (4), the dry powder feeding rate is 10.2 kg / h, the pure water addition flow rate is 42 mL / min, and the overall moisture content of the material is adjusted to 21%.

6. The preparation method according to claim 3, characterized in that, In step (5), the screw speed of the twin-screw extruder is 339 rpm, the temperature of the preheating and mixing section in the 3-4 zone of the sleeve is 110℃, the temperature of the shearing and gelatinization section in the 5-6 zone of the sleeve is 50℃, the material temperature of the maturation and forming section in the 7-8 zone of the sleeve is 108℃, the end plate temperature is 78℃, and the end plate extrusion pressure is 39.4 Bar.

7. The preparation method according to claim 3, characterized in that, The sleeve of the twin-screw extruder is divided into eight independent temperature control zones along the material conveying direction from the feed end to the discharge die. Among them, the sleeve zone 3-4 corresponds to the front area of ​​the sleeve near the feed inlet, the sleeve zone 5-6 corresponds to the middle area of ​​the sleeve, and the sleeve zone 7-8 corresponds to the rear area of ​​the sleeve near the discharge die.

8. The preparation method according to claim 3, characterized in that, In step (7), the two-stage drying process involves a fluidized bed pre-drying temperature of 40°C and a drying time of 20 min, while the hot air dryer deep drying temperature is 60°C.

9. The preparation method according to claim 3, characterized in that, The starch obtained in step (7) has a cooking degree of ≥95%, a complete rehydration time of 5~8 minutes after being soaked in boiling water, a cooking yield of ≥2.8:1, and a bulk density of 690~830 g / L.

10. The preparation method according to claim 3, characterized in that, The metal detector detection standard in step (9) is: Fe ≥ 1.0 mm, non-ferrous metals ≥ 2.0 mm.

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