Recombinant rice rich in whey protein and preparation method thereof

Abstract

The invention belongs to the technical field of food processing, and relates to recombinant rice rich in whey protein and a preparation method thereof. Comprising the following steps: step A, mixing raw materials: uniformly mixing 60-80 parts by mass of corn starch, 20 parts by mass of potato starch, 25-30 parts by mass of tartary buckwheat powder and 10-15 parts by mass of whey protein, adding 30-50 parts by mass of water, stirring and mixing, and standing for balancing moisture to obtain a soft material; step B, extruding and granulating: feeding the soft material into a twin-screw extruder, extruding and granulating, and cutting and forming to obtain semi-dry rice grains with the diameter of 2-4mm; and C, drying: transferring the half-dry rice grains into a fluidized bed, and drying until the water content of the rice grains is 13.5% or below, so as to obtain the recombinant rice rich in whey protein. The invention provides a multi-technology collaborative innovative solution, and the technical bottleneck that the mechanical strength and the reconstitution property are difficult to collaboratively optimize in the processing of the recombinant rice is emphatically broken through on the premise of controlling the cost and not using additives.

Description

Technical Field

[0001] The present invention belongs to the technical field of food processing, relates to the application of whey protein in the staple food field of Chinese people, and particularly relates to a cereal product with high protein nutritional value and convenient to eat and its preparation method. Background Art

[0002] In the field of instant rice products, rehydrated rice and restructured rice are two major technical routes. Rehydrated rice is made from refined rice through a cooking and dehydration process. Although it has the advantages of rapid rehydration, portability, and long shelf life, its inherent defects are significant: the single raw material leads to the lack of protein and dietary fiber, and the processing process exacerbates the loss of vitamins and minerals. Long-term consumption is likely to cause nutritional imbalance; in order to maintain low moisture, it needs to be dried at high temperature multiple times, resulting in increased starch retrogradation, and the product shows a hardening of the texture and instability of rehydration, typically manifested as a half-cooked state with soft outside and hard inside or over-pasting, and the rehydration time needs to be precisely controlled for 5 - 10 minutes, seriously affecting the user experience.

[0003] Restructured rice technology realizes nutritional fortification through composite starch, protein, and dietary fiber, and has potential in the field of functional foods with low GI and high protein. However, there is currently no national standard, and its industrialization faces multiple technical barriers: First, the raw material cost constraint is prominent, and adding non-rice-based auxiliary materials significantly increases the production cost; second, there is a contradiction in temperature sensitivity in the extrusion molding process - high-temperature puffing causes the rice grains to be loose and brittle, while low-temperature pressing can maintain a tight structure but will prolong the drying cycle and accelerate starch retrogradation; more critically, it is difficult for the product to balance the contradiction between rehydration efficiency and structural stability. Restructured rice with a loose structure rehydrates quickly but is fragile during storage and transportation and easily disintegrates after rehydration, while restructured rice with a tight structure has high mechanical strength but requires a long time for rehydration, which is contrary to the convenience requirements of instant products. The above contradiction between mechanical strength and rehydration has become the main bottleneck restricting the development of the restructured rice industry. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method of restructured rice rich in whey protein for the above problems.

[0005] Another purpose of the present invention is to provide a restructured rice rich in whey protein.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions:

[0007] A preparation method of a restructured rice rich in whey protein includes the following steps:

[0008] Step A, raw material mixing: By mass, mix 60 - 80 parts of corn starch, 20 parts of potato starch, 25 - 30 parts of tartary buckwheat powder, and 10 - 15 parts of whey protein evenly, add 30 - 50 parts of water, stir and mix, and let stand to balance the moisture to obtain soft material;

[0009] Step B, extrusion granulation: Feed the soft material into a twin-screw extruder, perform extrusion granulation and cutting to form semi-dry rice grains with a diameter of 2-4 mm.

[0010] Step C, drying: Transfer the semi-dry rice grains to a fluidized bed for drying until the water content of the rice grains is below 13.5%, thus obtaining a recombinant rice rich in whey protein.

[0011] A preparation method of a recombinant rice rich in whey protein, comprising the following steps:

[0012] Step A, raw material mixing: By mass, mix 70 parts of corn starch, 20 parts of potato starch, 25 parts of tartary buckwheat powder and 15 parts of whey protein evenly, add 40 parts of water, stir and mix, and let stand for 15 min at 20 °C to balance the moisture, obtaining a soft material.

[0013] Step B, extrusion granulation: Feed the soft material into a twin-screw extruder, set the temperature of the conveying section at 55 °C, the melting section at 80 °C, the kneading section at 90 °C, and the die head at 110 °C, adjust the screw speed to 130 rpm, and the extrusion pressure to 10 MPa, perform extrusion granulation and cutting to form semi-dry rice grains with a diameter of 2-3 mm.

[0014] Step C, drying: Transfer the semi-dry rice grains to a fluidized bed for drying, the temperature of the hot air in the fluidized bed is 65 °C, the humidity is RH20%, the air flow rate is 1.2 m / s, dry until the water content of the rice grains is below 13.5%, thus obtaining a recombinant rice rich in whey protein.

[0015] In the above preparation method of the recombinant rice rich in whey protein, in Step B, the temperature of the conveying section does not exceed 60 °C, the melting section temperature is 75-85 °C, the kneading section temperature is 85-90 °C, the extrusion pressure is 8-12 MPa, and the die head temperature is 105-125 °C. There is an interaction relationship among the residence time of the feed material, the die head temperature, the die head shape, the die head filter screen pore size, the screw speed, and the extrusion pressure. After setting the die head temperature, it is mainly achieved by adjusting the screw speed. If the set parameters cannot be achieved by adjusting the screw speed, the filter screen needs to be replaced and the die head filter screen pore size needs to be adjusted to reach the process parameters.

[0016] In the above preparation method of the recombinant rice rich in whey protein, in Step A, the static balance of moisture is carried out by standing for 10-30 min at 15-30 °C. The balance time can be extended under low temperature conditions, but limited by the soft material not sticking to the hand.

[0017] In the above preparation method of the recombinant rice rich in whey protein, in Step A, the corn starch, potato starch, and whey protein powder all pass through an 80-mesh sieve.

[0018] In the preparation method of the above-mentioned recombinant rice rich in whey protein, in step A, the corn starch is ordinary edible corn starch, and high amylose corn starch cannot be used. The potato starch is ordinary potato starch without undergoing denaturation treatment. The whey protein specification is WPC80, that is, whey protein with a protein content of about 80%. It can also be prepared by blending with whey protein isolate WPI. When using whey protein isolate, 15 - 20 of monosaccharides or disaccharides need to be added to it to reduce its protein content to 75 - 85%. The tartary buckwheat powder is tartary buckwheat after hulling and is ultra-finely pulverized to pass through a 200 - 400 mesh sieve.

[0019] In the preparation method of the above-mentioned recombinant rice rich in whey protein, in step B, the residence time of the soft material in the twin-screw extruder is between 150 - 250 s. The residence time of the soft material in the twin-screw extruder needs to be controlled, and the control means is to control the screw speed and the feeding amount. For example, a tracer is added to the material, and the screw speed is 90 - 200 rpm.

[0020] In the preparation method of the above-mentioned recombinant rice rich in whey protein, in step C, the temperature of the hot air in the fluidized bed is 60 - 70 °C, the humidity is RH15% - 40%, and the air flow rate is 0.8 - 1.5 m / s.

[0021] In the preparation method of the above-mentioned recombinant rice rich in whey protein, in step C, the transfer of the semi-dry rice grains to the fluidized bed drying operation should be carried out quickly. Attention should be paid to avoiding the adhesion caused by the accumulation of rice grains and avoiding intermittent feeding. Therefore, the transfer of the semi-dry rice grains is a blow-in feeding or mechanical feeding.

[0022] The recombinant rice prepared according to the preparation method of the above-mentioned recombinant rice rich in whey protein.

[0023] In existing food processing, thermal-induced gelation and pressure gelation, as physical modification means, have been applied in the texture regulation of meat products. Thermal-induced gelation drives the unfolding and recombination of protein / polysaccharide molecules through heat energy to form a three-dimensional elastic network dominated by hydrogen bonds and hydrophobic interactions; pressure gelation, on the other hand, forces the molecular chains to crosslink tightly with the help of mechanical pressure to construct a rigid structure strengthened by covalent bonds. The synergy of these two technologies can achieve multi-dimensional crosslinking at the molecular level and increase the mechanical strength of food. However, the puffing process in traditional recombinant rice processing will completely destroy such gel networks, resulting in the loss of structural integrity.

[0024] Based on this, the present invention proposes a solution: achieving precise control of phase change through critical puffing technology, constructing a microporous structure while maintaining the integrity of the gel network, and combining fluidized bed rapid dehydration to prevent starch retrogradation. This technical system effectively avoids defects such as puffing damage, starch retrogradation, and structure-function imbalance in traditional processes, and opens up a new path for the development of recombinant rice products rich in high-quality protein and having excellent mechanical strength and instant solubility characteristics.

[0025] Compared with the existing technologies, the advantages of the present invention are as follows:

[0026] The present invention proposes an innovative solution with multi-technology collaboration, which focuses on breaking through the technical bottleneck that it is difficult to synergistically optimize the mechanical strength and rehydration property in the processing of recombinant rice without using additives and while controlling costs, as follows.

[0027] 1. Whey protein is a by-product of the cheese industry and is a high-quality protein with a relatively low price. The prices of the main raw materials, corn starch and potato starch, are both lower than that of rice flour. The produced recombinant rice has a cost advantage.

[0028] 2. The product does not use any food additives. The texture is regulated through the self-assembly of natural ingredient molecules, which conforms to the trend of clean label. The synergistic effect of whey protein and buckwheat protein improves the amino acid score of the product, and the protein nutritional value far exceeds the cereal protein in natural rice. At the same time, it is rich in dietary fiber, vitamins and flavonoid active substances from tartary buckwheat, and is suitable for long-term consumption as a staple food.

[0029] 3. Tartary buckwheat originally has a bitter taste. The extrusion gelatinization process entraps the flavonoid substances in tartary buckwheat. Combining with the sweetening effect of the lactose in whey protein, the bitterness of the raw materials is completely eliminated; simultaneously, the natural color of grains is imparted to the product through the Maillard reaction.

[0030] 4. Solve the industry problems of traditional recombinant rice being fragile and slow to rehydrate, and propose a non-additive strengthening strategy based on the interaction between natural proteins and polysaccharide molecules. Through the synergistic effect of the thermally induced gel and pressure gel of whey protein and starch, a three-dimensional cross-linked network is constructed to improve the mechanical strength of the product. Combining with the critical expansion process, the microscopic pore structure is precisely regulated, and finally the synergy between the mechanical strength and rapid rehydration of the product is achieved.

[0031] 5. Adopt a segmented temperature control strategy for the twin-screw extrusion granulator, and each stage completes different tasks. In the melting section, the starch gelatinizes and the whey protein molecules unfold, forming a primary gel skeleton through hydrogen bonding and hydrophobic interaction. In the kneading section, the whey protein denatures, and using the pressure of twin-screw extrusion, the covalent cross-linked network is strengthened and a stable gel is formed, increasing the mechanical strength of the product.

[0032] 6. Introduce the critical expansion technology. By precisely controlling the extrusion pressure and temperature, the internal moisture of the material is in a metastable state - only 30 - 45% of the free water vaporizes, forming a microvoid structure. This unique pore structure (pore size range 50 - 200 μm) avoids the problem of loose tissue caused by traditional high-temperature expansion, retains the structural integrity of the gel network, and provides a rapid penetration channel for the subsequent rehydration process.

[0033] 7. Fluidized bed flash drying is adopted to control the retrogradation of wet starch, maintain the stability of the gelatinized state, reduce the retrogradation degree of starch, and improve the taste.

[0034] 8. The starch has been gelatinized during the twin-screw extrusion process and does not need to be gelatinized again before consumption. While maintaining high mechanical strength, the final product can be rehydrated by soaking in warm water at 80 °C for more than 3 minutes, and the integrity of the grains after rehydration reaches 95%, completely solving the technical problem of the fragility of traditional recombined rice.

[0035] 9. Whey protein and tartary buckwheat protein completely replace gluten, and the product is naturally gluten-free, meeting the staple food needs of people with celiac disease and gluten intolerance.

[0036] 10. Directly using rice flour or wheat flour cannot achieve critical expansion because the viscosity of wheat starch, gluten, and amylopectin in rice is too high and will clog the die head. Using whey protein, buckwheat flour, and corn starch with lower viscosity under high-temperature conditions and adapting potato starch to adjust processing characteristics can prevent clogging of the die head.

[0037] Other advantages, objectives, and features of the present invention will be partially reflected by the following description and partially understood by those skilled in the art through the research and practice of the present invention. Detailed implementation manners

[0038] The present invention will be further described below in conjunction with the detailed implementation manners.

[0039] Example 1

[0040] A preparation method of recombined rice rich in whey protein, comprising the following steps:

[0041] Step A, raw material mixing: Weigh 70 parts of corn starch, 20 parts of potato starch, 15 parts of WPC80 whey protein, and 25 parts of tartary buckwheat flour. The tartary buckwheat flour is dehulled tartary buckwheat and is ultra-finely pulverized to pass through a 200-400 mesh sieve. After mixing, it passes through an 80 mesh sieve, add 40 parts of water, and mix evenly. Let it stand at 20 °C for 15 minutes to obtain soft material.

[0042] Step B, extrusion granulation: Feed the soft material into a twin-screw extruder, set the temperature of the conveying section at 55 °C, the temperature of the melting section at 80 °C, the temperature of the kneading section at 90 °C, and the temperature of the die head at 110 °C. Adjust the screw speed to 130 rpm. At this time, the extrusion pressure is 10 MPa. Extrusion granulation and cutting are carried out to obtain semi-dry rice grains with a diameter of 2-3 mm.

[0043] Control the residence time of the soft material in the twin-screw extruder between 150-250 s, and the control means is to control the screw speed and the feeding amount.

[0044] Step C, Drying: Transfer the semi-dry rice grains to a fluidized bed for drying. The temperature of the hot air in the fluidized bed is 65°C, the humidity is RH20%, the air flow rate is 1.2 m / s. Dry until the water content of the rice grains is below 13.5%, and a recombinant rice rich in whey protein is obtained.

[0045] Control Example 1

[0046] Control of Different Formulations

[0047] Prepare raw materials according to the formulation in Table 1. First, mix the powdery solids evenly, pass through an 80-mesh sieve, and then add water and mix well. Let it stand for 15 min at 20°C to balance the moisture and obtain soft materials. Feed the soft materials into a twin-screw extruder, set the temperature of the conveying section at 55°C, the melting section at 80°C, the kneading section at 90°C, and the die head at 110°C. Adjust the screw speed to 130 rpm. At this time, the extrusion pressure is 10 MPa. Extrude and pelletize, cut and form to obtain semi-dry rice grains with a diameter of 2 - 3 mm. Transfer the semi-dry rice grains to a fluidized bed for drying. The temperature of the hot air in the fluidized bed is 65°C, the humidity is RH20%, the air flow rate is 1.2 m / s. Dry until the water content of the rice grains is below 13.5%, and the product is obtained.

[0048] Table 1 Formulation Verification Test

[0049]

[0050] For the products obtained under different formulations, conduct rehydration tests according to the method in Appendix A of GB / T 31323, measure the proportion of small broken rice according to the method of GB / T 5503, and conduct sensory tests according to Table 2. Take 10 whole products, conduct extrusion tests with a texture analyzer, measure the compressive strength at the time of crushing and calculate the average value. The results are shown in Table 3.

[0051] Table 2 Sensory Test Table of Recombinant Rice

[0052]

[0053]

[0054] Table 3 Experimental Result Table of Products with Different Formulations

[0055]

[0056] The results show that Formulation 1 can produce qualified products with good flavor. The products of Formulation 2, Formulation 6, Formulation 8, and Formulation 10 are all too loose. The product of Formulation 3 has good rehydration, but the taste is slightly bitter. Formulation 4 cannot be extruded and formed smoothly. The rehydration of Formulation 5 and Formulation 7 is poor. Formulation 9 cannot be produced continuously.

[0057] Control Example 2

[0058] Comparison of Different Processes

[0059] Weigh 70 parts of corn starch, 20 parts of potato starch, 15 parts of WPC80 whey protein, and 25 parts of ultrafine tartary buckwheat powder. After mixing, pass through an 80-mesh sieve, add 40 parts of water, and mix evenly. Let it stand for 15 minutes at 20°C to obtain soft material.

[0060] Feed the soft material into a twin-screw extruder, set the process parameters according to Table 4 for extrusion granulation, and then transfer the semi-dry rice grains to a fluidized bed for drying. The temperature of the hot air in the fluidized bed is 65°C, the humidity is RH20%, the air flow rate is 1.2 m / s, and dry until the water content of the rice grains is below 13.5% to obtain the product. Conduct a sensory inspection on the produced product according to Table 2, and the results are shown in Table 4.

[0061] Table 4 Process Parameter Table of Twin-Screw Extruder

[0062]

[0063] The results show that Plan 1 can produce products that meet the sensory requirements. When the die head temperature is high and the extrusion pressure is high, the product undergoes excessive puffing and is incomplete after rehydration; when the die head temperature is low and the extrusion pressure is low, it will cause the product to be difficult to rehydrate; inappropriate temperatures in the melting section and mixing section will both cause the product structure to be loose.

[0064] Control Example 3

[0065] Comparison of Different Processes

[0066] Weigh 70 parts of corn starch, 20 parts of potato starch, 15 parts of WPC80 whey protein, and 25 parts of ultrafine tartary buckwheat powder. After mixing, pass through an 80-mesh sieve, add 40 parts of water, and mix evenly. Let it stand for 15 minutes at 20°C to obtain soft material.

[0067] Feed the soft material into a twin-screw extruder, set the temperature of the conveying section at 55°C, the temperature of the melting section at 80°C, the temperature of the mixing section at 90°C, and the die head temperature at 110°C. Adjust the screw speed to 130 rpm. At this time, the extrusion pressure is 10 MPa. Conduct extrusion granulation and cutting to obtain semi-dry rice grains with a diameter of 2 - 3 mm.

[0068] Transfer the semi-dry rice grains to a fluidized bed for drying, set the fluidized bed process parameters according to Table 5 and dry until the water content of the rice grains is below 13.5% to obtain the product. Conduct a sensory inspection on the produced product according to Table 2, and the results are shown in Table 5.

[0069] Table 5 Process Parameter Table of Fluidized Bed

[0070]

[0071] The results show that when the hot air temperature is too high, the surface of the rice grains dries rapidly, resulting in uneven humidity inside and outside. When the hot air temperature is too low, the drying time is prolonged and the taste after rehydration is poor. When the wind speed is high, the rice grains collide with each other, resulting in a relatively high proportion of broken rice. When the wind speed is low, drying cannot be carried out smoothly.

[0072] Detection Example 1

[0073] For the recombined rice obtained in Example 1, the degree of gelatinization was determined with reference to the method in Appendix B of GB / T 31323. The results showed that the degree of gelatinization was 90.02%.

[0074] For the recombined rice obtained in Example 1, the proportion of small broken rice was determined with reference to the method of GB / T 5503. The results showed that the small broken rice rate was 3.5%.

[0075] 1) Measuring the rehydration time: Weigh 100 g of the recombined rice sample obtained in Example 1 and put it into a glass beaker. Add 500 mL of hot water at 80 °C to the beaker, and place the beaker in a water bath at 80 °C. Gently stir with a glass rod and start timing with a stopwatch. After 2 minutes, take a spoonful every 1 minute and taste whether there is an undercooked feeling. If there is no undercooked feeling, record the time, which is the rehydration time.

[0076] The test showed that it was not undercooked after soaking for 6 minutes. That is, the rice was rehydrated after soaking in 80 °C hot water for 6 minutes.

[0077] 2) Rehydration test: For the recombined rice obtained in Example 1, the rehydration test was carried out with reference to the method in Appendix A of GB / T 31323. The water addition temperature was 90 °C and the soaking time was 15 min. After reaching the specified time, a palatability test was carried out.

[0078] It was shown that the cooked rice after 15 min of rehydration remained smooth, non-sticky, without a feeling of being too hard or too soft or having residue, and was not undercooked. Then, the rice grains were fished out and spread on a tray, and the proportion of intact rice grains was observed and counted. It was shown that the integrity of the rice grains exceeded 95% after 15 min of rehydration.

[0079] It shows that the rehydrated rice obtained in Example 1 has a relatively short rehydration time, and after being soaked in hot water for a long time, it can still maintain the taste and the integrity of the rice grains.

[0080] 3) Nutritional examination:

[0081] The amino acid score of the recombined rice in Example 1 was evaluated with reference to the standards of FAO and WHO, with rice, wheat flour, and a certain brand of oats as controls. The results are shown in Table 6.

[0082] Table 6 Comparison of amino acid scores of recombined rice, rice, and breakfast cereals

[0083]

[0084] Note: The content of essential amino acids is sourced from "Chinese Food Composition Table".

[0085] It can be seen that for the recombinant rice obtained in Example 1, its amino acid score reaches 95 points, which is superior to rice, wheat, and oats. Since the protein in the recombinant rice mainly comes from whey protein and buckwheat, the combination of plant protein and animal protein gives the product a relatively high amino acid score.

[0086] 4) Similarity check

[0087] Twenty-four students were invited to use the paired comparison method to compare the similarities in vision, smell, taste, and touch among the rehydrated recombinant rice (A), ordinary red rice (B), and a certain brand of instant rice (C) after rehydration and give a score from 1 to 10. The results are shown in Table 7. Table 7 Paired comparison results

[0088] Combination method Scoring AB combination 5.47±1.20 BC combination 4.13±1.55 AC combination 5.43±1.29

[0089] It shows that compared with commercially available instant rice, the rehydrated recombinant rice is more similar to ordinary red rice.

[0090] Example 2

[0091] A preparation method of a recombinant rice rich in whey protein, comprising the following steps:

[0092] Step A, raw material mixing: Weigh 60 parts of corn starch, 20 parts of potato starch, 10 parts of WPC80 whey protein, and 30 parts of tartary buckwheat powder. The tartary buckwheat powder is dehulled tartary buckwheat and is ultrafinely ground to pass through a 200 - 400 mesh sieve. After mixing, it passes through an 80 mesh sieve, add 30 parts of water, and mix evenly. Let it stand at 30°C for 10 min to obtain soft material.

[0093] Step B, extrusion granulation: Feed the soft material into a twin-screw extruder. Set the temperature of the conveying section at 55°C, the melting section at 75°C, the kneading section at 85°C, and the die head temperature at 105°C. Adjust the screw speed to 90 rpm. At this time, the extrusion pressure is 12 MPa. Extrusion granulation and cutting are carried out to obtain semi-dry rice grains with a diameter of 2 - 4 mm.

[0094] Step C, drying: Transfer the semi-dry rice grains to a fluidized bed for drying. The temperature of the hot air in the fluidized bed is 60°C, the humidity is RH15%, the air flow rate is 0.8 m / s, and dry until the water content of the rice grains is below 13.5%, thus obtaining a recombinant rice rich in whey protein.

[0095] Example 3

[0096] A preparation method of a recombinant rice rich in whey protein, comprising the following steps:

[0097] Step A, raw material mixing: Weigh 80 parts of corn starch, 20 parts of potato starch, 12 parts of WPC80 whey protein, and 25 parts of tartary buckwheat powder. The tartary buckwheat powder is the dehulled tartary buckwheat and is ultrafinely pulverized to pass through a 200 - 400 mesh sieve. After mixing, it is passed through an 80 - mesh sieve, and 50 parts of water are added and mixed evenly. It is left standing at 15°C for 30 min to obtain soft materials.

[0098] Step B, extrusion granulation: Feed the soft materials into a twin - screw extruder. Set the temperature of the conveying section at 55°C, the temperature of the melting section at 85°C, the temperature of the kneading section at 90°C, and the temperature of the die head at 125°C. Adjust the screw speed to 100 rpm. At this time, the extrusion pressure is 8 MPa. Extrusion granulation and cutting are carried out to obtain semi - dry rice grains with a diameter of 2 - 4 mm.

[0099] Step C, drying: Transfer the semi - dry rice grains to a fluidized bed for drying. The temperature of the hot air in the fluidized bed is 60°C, the humidity is RH15%, and the air flow velocity is 0.8 m / s. Dry until the water content of the rice grains is below 13.5%, and thus obtain a kind of recombinant rice rich in whey protein.

[0100] The specific embodiments described herein are merely illustrative of the spirit of the present invention. Those skilled in the art of the present invention can make various modifications or supplements or use similar ways to replace the described specific embodiments, but will not deviate from the spirit of the present invention.

Claims

1. A method for preparing recombinant rice rich in whey protein, characterized in that: The following steps are involved: Step A, mixing raw materials: by weight, 60-80 parts of corn starch, 20 parts of potato starch, 25-30 parts of buckwheat flour and 10-15 parts of whey protein are mixed evenly, 30-50 parts of water are added, the mixture is stirred, and the mixture is allowed to stand to balance the moisture to obtain a soft material; Step B, extrusion granulation: feeding the soft material to a twin-screw extruder, extruding granulation, cutting and shaping, and obtaining semi-dry rice grains with a diameter of 2-4 mm; Step C, drying: transferring the semi-dried rice grains to a fluidized bed for drying until the water content of the rice grains is below 13.5%, thereby obtaining a recombinant rice rich in whey protein.

2. A method for preparing recombinant rice rich in whey protein, characterized in that: The following steps are involved: Step A, mixing raw materials: by weight, 70 parts of corn starch, 20 parts of potato starch, 25 parts of buckwheat flour and 15 parts of whey protein are mixed evenly, 40 parts of water are added, stirred and mixed, and allowed to stand at 20° C. for 15 minutes to balance the moisture to obtain a soft material; Step B, extrusion granulation: feeding the soft material to a twin-screw extruder, setting the conveying section temperature to 55°C, the melting section temperature to 80°C, the mixing section temperature to 90°C, the die head temperature to 110°C, adjusting the screw speed to 130rpm, the extrusion pressure to 10MPa, extrusion granulation, cutting and shaping, and obtaining semi-dry rice grains with a diameter of 2-3mm; Step C, drying: transferring the semi-dried rice grains to a fluidized bed for drying, wherein the hot air temperature in the fluidized bed is 65° C., the humidity is RH20%, and the air flow velocity is 1.2 m / s, and the rice grains are dried until the moisture content is below 13.5%, thereby obtaining a recombinant rice rich in whey protein.

3. The method for preparing the recombinant rice rich in whey protein according to claim 1, characterized in that: In step B, the temperature of the conveying section does not exceed 60°C, the temperature of the melting section is 75-85°C, the temperature of the mixing section is 85-90°C, the extrusion pressure is 8-12MPa, and the die head temperature is 105-125°C.

4. The method for preparing the recombinant rice rich in whey protein according to claim 1, characterized in that: In step A, the moisture balance is achieved by standing at 15-30°C for 10-30 minutes.

5. The method for preparing the recombinant rice rich in whey protein according to claim 1 or 2, characterized in that: In step A, corn starch, potato starch and whey protein powder are all sieved through an 80-mesh sieve.

6. The method for preparing the recombinant rice rich in whey protein according to claim 1 or 2, characterized in that: In step A, the corn starch is common edible corn starch, the potato starch is common potato starch, the whey protein specification is WPC80, and the tartary buckwheat flour is hulled Tatar buckwheat, which is ultrafinely ground to pass through a 200-400 mesh sieve.

7. The method for preparing the recombinant rice rich in whey protein according to claim 1 or 2, characterized in that: In step B, the residence time of the soft material in the twin-screw extruder is between 150-250s, and the screw speed is 90-200rpm.

8. The method for preparing the recombinant rice rich in whey protein according to claim 1, characterized in that: In step C, the temperature of the hot air in the fluidized bed is 60-70° C., the humidity is RH15%-40%, and the air flow velocity is 0.8-1.5 m / s.

9. The method for preparing the recombinant rice rich in whey protein according to claim 1 or 2, characterized in that: In step C, the semi-dried rice grains are transferred to a blow-in feeder or a mechanical feeder.

10. Recombinant rice obtained by the preparation method of the recombinant rice rich in whey protein according to any one of claims 1 to 9.

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