A method for flavor directional regulation and preservation treatment of composite coarse cereal crust

Abstract

The application discloses a kind of compound rice crust flavor directional regulation and fresh-keeping treatment method of coarse grain, comprising the following steps: S1: selecting compound and mixing evenly, low-temperature baking enzyme, crushing screening, obtain mixed powder of coarse grain;S2: flavor regulator and fresh-keeping composite agent are added to mixed powder of coarse grain, adjust moisture content after high-speed mixing;S3: extruding material is adjusted, tableting, granulating, and get crust blank;S4: crust blank is sent into multilayer belt dryer, and three-stage gradient drying treatment is used to realize flavor solidification;S5: semi-finished product crust is vacuum cooling treatment, and is sealed with nitrogen filling packaging using high-barrier aluminum foil bag.The application realizes nutrition fortification by scientific compound of coarse grain, accurately directs crust flavor by flavor regulation system, realizes natural and efficient preservation by multi-link collaborative preservation technology, and the prepared crust is nutritionally balanced, flavor level is rich, taste is crisp, is healthy and safe and quality is stable, is suitable for industrialized continuous production.

Description

Technical Field

[0001] This invention relates to the field of food processing technology, specifically to a method for targeted flavor control and preservation of multigrain composite rice crust, which is particularly applicable to the industrial production of nutritionally fortified rice crust in the snack food industry. It can achieve precise control of rice crust flavor and long-term preservation, thereby improving product quality and market competitiveness. Background Technology

[0002] Rice crust, a traditional snack, is loved by consumers of all ages for its crispy texture and rich flavor. Traditional rice crust production primarily uses rice as a single ingredient, involving soaking, steaming, pressing, frying, and seasoning. While it offers a crispy texture, it has significant limitations: 1. Limited nutritional value: Rice is low in dietary fiber, protein, B vitamins, and minerals; 2. Limited flavor: Traditional rice crust relies heavily on single seasonings to enhance flavor, easily leading to an unbalanced flavor profile and poor texture, affecting the product's overall taste; 3. Poor preservation: Traditional rice crust... Rice crackers are often produced using high-temperature frying, resulting in high oil content and susceptibility to oxidation and spoilage. Furthermore, ordinary packaging makes it difficult to prevent the absorption of oxygen, water vapor, and other external factors, causing the rice crackers to easily become damp, soft, and moldy, resulting in a short shelf life of only 3-6 months. This severely impacts the product's storage, transportation, and sales. 4. Insufficient health benefits: High-temperature frying not only leads to excessive oil content but may also produce harmful substances such as acrylamide. Additionally, some manufacturers add chemical preservatives such as BHA and BHT to extend shelf life, posing potential health risks with long-term consumption.

[0003] Therefore, in response to the problems of single nutritional content, unbalanced flavor, poor preservation effect, short shelf life, insufficient health benefits, and unstable quality in existing technologies for multigrain rice crusts, a multigrain composite rice crust processing method is proposed to solve the above problems. This method can achieve directional flavor control, is natural and safe, has good preservation effect, long shelf life, balanced nutrition, stable quality, and is suitable for industrial production. Summary of the Invention

[0004] This invention aims to overcome the shortcomings of existing technologies and provide a method for targeted flavor control and preservation of multigrain composite rice crusts. It solves the technical problems of traditional rice crusts and existing multigrain rice crusts, such as nutritional deficiencies, flavor imbalances, easy oxidation and spoilage, softening due to moisture, short shelf life, insufficient health benefits, and unstable quality. It achieves precise targeted flavor control, natural and efficient preservation, balanced nutritional enhancement, and stable improvement in product quality. At the same time, it simplifies the process, reduces production costs, is suitable for continuous industrial production, and meets consumers' demand for healthy, delicious, and long-lasting fresh snacks.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A method for targeted flavor regulation and preservation of multigrain rice crust, comprising: S1. Multigrain compounding and pretreatment: By weight, 40-50 parts brown rice, 15-25 parts oats, 10-20 parts buckwheat, 10-15 parts millet, and 5-10 parts corn flour are selected as raw materials; wherein, brown rice is rich in dietary fiber, B vitamins and minerals, which can enhance the product's nutrition and rich taste; oats are rich in β-glucan, which has the effects of lowering blood lipids and enhancing satiety, while also improving the crispness of the rice crust; buckwheat is rich in rutin, which is nutritious and can add a unique flavor to the rice crust; millet has a delicate texture, which can neutralize the roughness of the multigrains and improve the palatability of the product; corn flour can increase the stickiness of the rice crust, making it easier to shape, while also enhancing the grain aroma of the product.

[0006] First, pre-treat each grain raw material: select brown rice, oats, buckwheat, and millet that are free from mold, insects, impurities, and have normal color, rinse them 2-3 times with deionized water to remove surface dust, impurities, and some residual pesticides, and then place them in a forced-air drying oven to dry them at 60-70℃ until the moisture content is ≤12%. After drying, cool them to room temperature for later use; select food-grade corn flour that is free from mold and odor and use it directly.

[0007] The pre-treated brown rice, oats, buckwheat, millet, and corn flour are mixed evenly and placed in a hot air drying oven for low-temperature baking to inactivate enzymes. The baking temperature is controlled at 80-90℃ and the baking time is 15-20 minutes. During the baking process, the mixture is turned over every 5 minutes to ensure that the mixed grains are heated evenly and to fully inactivate the activity of enzymes such as lipase and peroxidase. Inactivation of lipase can prevent the oil in the mixed grains from hydrolyzing and oxidizing, reducing the generation of spoilage and off-flavors. Inactivation of peroxidase can delay the oxidation and deterioration of the mixed grains and preserve their natural color and flavor.

[0008] After baking, the mixed grains are fed into a universal grinder and ground to 80-100 mesh. After grinding, the mixture is sieved to remove impurities and coarse particles, resulting in a mixed grain powder with uniform particle size. This particle size of mixed grain powder can ensure sufficient subsequent extrusion and cooking, avoid the sticky texture of rice crust caused by excessively fine particles, and facilitate the uniform dispersion of flavor regulators and preservatives.

[0009] Preferably, after low-temperature baking to inactivate enzymes, the lipase activity of the mixed grain powder is ≤10 U / g, the peroxidase activity is ≤5 U / g, the moisture content is ≤10%, and the bulk density is 0.5~0.6 g / cm³, to ensure the stability of subsequent processing and product quality.

[0010] S2, Flavor-oriented conditioning: Add flavor regulators and preservatives to the mixed grain powder obtained in step S1, and mix them evenly using a high-speed mixer at a speed of 300-400 r / min for 10-15 min to ensure that the flavor regulators and preservatives are fully integrated with the mixed grain powder and to avoid local concentrations that are too high or too low, which would affect the flavor regulation and preservation effect.

[0011] Preferably, the flavor modifier comprises the following components in parts by weight: 0.1-0.3 parts of disodium inosinate, 0.5-1.0 parts of yeast extract, and 0.2-0.5 parts of natural spice powder; the disodium inosinate is a compound of disodium 5'-inosinate (IMP) and disodium 5'-guanylate (GMP) in a 1:1 weight ratio, which can synergistically enhance the umami flavor of the rice crust with the flavor substances of the grains themselves, significantly improving the umami flavor of the rice crust, and the umami flavor is long-lasting, avoiding the abrupt umami flavor and thin taste caused by using only MSG; the yeast extract is rich in flavor substances such as amino acids and peptides, which can enhance the richness and umami layers of the rice crust, while also masking the rough odor of the grains, thus improving the flavor. For product palatability, the preferred yeast extract has a protein content ≥80% and a moisture content ≤6% to ensure flavor. The natural spice powder is made from one or more of Sichuan pepper, star anise, cinnamon, and bay leaves, with the blending ratio adjustable according to market demand. It provides the rice crust with a natural spice flavor, enriching the flavor profile and avoiding the off-flavors of artificial flavorings. The preparation method of the natural spice powder is as follows: select natural spices that are free from mold and off-flavors, clean them, and dry them at 55-65℃ until the moisture content is ≤8%. After drying, pulverize them to 100-120 mesh, sieve them, and seal them for later use. This particle size ensures that the spice flavor is fully released without affecting the texture of the rice crust.

[0012] The preservation compound consists of the following components in parts by weight: 0.05-0.15 parts rosemary extract, 0.03-0.08 parts tea polyphenols, and 0.02-0.05 parts ε-polylysine hydrochloride. Both rosemary extract and tea polyphenols are natural antioxidants. The rosemary extract has a rosmarinic acid content ≥5%, and the tea polyphenols have a catechin content ≥90%. The two work synergistically to effectively inhibit the oxidation and deterioration of the oil in the rice crust, preserving the product's natural flavor and color. ε-polylysine hydrochloride is a natural antibacterial agent with a purity ≥95%, which can effectively inhibit the growth of harmful microorganisms such as Escherichia coli and mold, extending the product's shelf life. The combination of these three components replaces traditional chemical preservatives, improving product health and synergistically enhancing the preservation effect. The preferred weight ratio of rosemary extract, tea polyphenols, and ε-polylysine hydrochloride is 3:2:1 to 5:3:1 to ensure a balance between antioxidant and antibacterial effects.

[0013] After mixing, slowly add deionized water to the material while stirring, adjusting the moisture content to 22%–26%. Too high a moisture content will cause the material to stick together during subsequent extrusion and ripening, making shaping difficult and prolonging drying time, thus increasing flavor loss. Too low a moisture content will result in insufficient extrusion and ripening, leading to a hard texture and insufficient crispness in the rice crust. After stirring evenly, let it stand for 20–30 minutes to condition. During this period, maintain an ambient temperature of 20–25℃ and a relative humidity of 50–60% to prevent moisture absorption or loss. This conditioning allows moisture to fully penetrate the grain particles, ensuring uniformity during subsequent extrusion and ripening. It also allows the flavor modifiers and preservatives to fully function, achieving initial targeted adsorption and solidification of the flavor.

[0014] S3, Extrusion Curing and Forming: The conditioned material obtained in step S2 is fed into a twin-screw extruder for extrusion curing. A stainless steel twin-screw extruder with a length-to-diameter ratio of 28:1 to 32:1 is selected. The barrel is made of stainless steel to avoid material contamination. The die is rectangular, and its size matches the size of the rice crust blank. The extrusion curing process parameters are strictly controlled as follows: barrel zone 1 temperature 120–130℃, zone 2 temperature 130–140℃, die temperature 135–140℃, screw speed 180–220 r / min, die pressure 2.5–3.5 MPa, and feed rate 20–30 km / h. kg / h; zoned temperature control in the barrel ensures gradual cooking of materials, avoiding local overheating that leads to scorching and flavor loss, while also improving the gelatinization degree of grain starch; coordinated control of screw speed and feed rate ensures uniform residence time of materials in the barrel, ensuring sufficient cooking and avoiding problems such as undercooking and sticking; control of die pressure ensures smooth extrusion of materials, while maintaining uniform density of the rice crust dough and improving taste.

[0015] After extrusion and maturation, the material is immediately fed into a tablet press for tableting. The tablet thickness is controlled at 0.8–1.2 mm. If the thickness is too thick, it will lead to insufficient drying, resulting in a hard texture and easy absorption of moisture. If the thickness is too thin, the tablet will be brittle and affect the product shape. After tableting, the material is fed into a pelletizer for pelleting. The pellet size is 2.5–3.5 cm × 2.5–3.5 cm, resulting in uniformly shaped tablet blanks. Both the tableting and pelleting processes are carried out in a sterile environment to avoid material contamination and ensure product hygiene and safety.

[0016] Preferably, after extrusion and curing, the degree of gelatinization of the rice crust dough is ≥90%. The increase in the degree of gelatinization ensures that the rice crust has a crispy texture and is easy to digest. The bulk density is 0.35~0.45 g / cm³ and the hardness is 15~20 N, which ensures the morphological stability of the rice crust dough and the feasibility of subsequent processing.

[0017] S4, Gradient Drying and Flavor Curing: The rice crust raw material obtained in step S3 is fed into a multi-layer belt dryer for three-stage gradient drying. The core purpose of gradient drying is to remove moisture from the rice crust while retaining flavor substances to the maximum extent, avoiding flavor loss, darkening of color and deterioration of taste caused by high-temperature drying.

[0018] The specific drying parameters are as follows: The first stage of drying is controlled at a temperature of 50–55℃, a drying time of 30–40 min, and a wind speed of 1.5–2.0 m / s. This stage is low-temperature slow drying, which mainly removes free moisture from the surface of the rice crust dough, while allowing flavor substances to be gradually adsorbed and initially solidified, avoiding rapid evaporation of moisture that would cause flavor substances to be lost with water vapor. The second stage of drying is controlled at a temperature of 60–65℃, a drying time of 20–25 min, and a wind speed of 2.0–2.5 m / s. This stage is medium-temperature drying, which mainly removes bound moisture inside the rice crust, further solidifies flavor substances, and improves the crispness of the rice crust. The third stage of drying is controlled at a temperature of 70–75℃, a drying time of 10–15 min, and a wind speed of 2.5–3.0 m / s. This stage is high-temperature fast drying, which quickly reduces the moisture content of the rice crust to the target value, while further improving crispness and ensuring the stable preservation of flavor substances.

[0019] During the gradient drying process, the thickness of the rice crust dough is 1-2 cm, and the spacing between adjacent dough pieces is ≥1 cm to ensure uniform drying and avoid local over-drying or under-drying. After the gradient drying is completed, the final moisture content of the rice crust is reduced to 3.5-5.0%. Too high a moisture content will cause the rice crust to become damp and moldy, affecting its preservation effect; too low a moisture content will cause the rice crust to be too crispy and brittle, affecting the product shape. After drying, the crispness of the rice crust is ≥8.5 kgf, the flavor substance retention rate is ≥92%, the color is golden yellow to light brown, and there are no scorch spots, ensuring the product's taste and flavor quality.

[0020] S5, Vacuum Cooling and Packaging: The semi-finished rice crust obtained in step S4 is immediately transferred to a vacuum cooling machine for vacuum cooling. The principle of vacuum cooling is to utilize the rapid evaporation of moisture and heat absorption in a vacuum environment to achieve rapid cooling of the rice crust, avoiding the reabsorption of moisture, loss of flavor, and microbial contamination caused by traditional natural cooling or forced air cooling. The process parameters for vacuum cooling are controlled as follows: vacuum degree 0.08~0.09 MPa, cooling time 8~12 min, cooling to rice crust temperature ≤25℃. If the rice crust temperature is too high, the temperature inside the bag will rise after packaging, accelerating oil oxidation and microbial growth; if the temperature is too low, condensation will form on the surface of the rice crust, making it susceptible to moisture and softening.

[0021] After cooling, the semi-finished rice crackers are sent to a sterile workshop and sealed in nitrogen-filled high-barrier aluminum foil bags. The high-barrier aluminum foil bags are food-grade, with a thickness of 0.12–0.15 mm, an oxygen permeability ≤5 cm³ / (m²·24h·atm), and a water vapor permeability ≤3 g / (m²·24h). This effectively blocks the influence of external factors such as oxygen, water vapor, and light, preventing the rice crackers from oxidizing, becoming damp, or discoloring. During nitrogen-filled sealing, the nitrogen purity is ≥99.9%, the filling pressure is 0.1–0.15 MPa, and the residual oxygen content inside the bag after packaging is ≤1.0%. Nitrogen effectively isolates the air, further inhibiting oil oxidation and microbial growth, extending the product's shelf life. Each bag of rice crackers weighs 20–50 g, conforming to the consumption habits of snack foods. After packaging, vacuum leak testing is performed to ensure no air leakage and prevent packaging damage that could lead to loss of freshness.

[0022] After packaging, the finished product undergoes inspection, including sensory, physicochemical, and microbiological indicators. Sensory indicators: uniform color, no scorch marks or mold, crisp texture, rich aroma, no off-flavors or bitterness. Physicochemical indicators: moisture content 3.5–5.0%, acid value ≤3.0 mg / g, peroxide value ≤0.25 g / 100g, oil content ≤8%. Microbiological indicators: total bacterial count ≤1000 CFU / g, coliform bacteria ≤30 MPN / 100g, mold ≤25 CFU / g, pathogenic bacteria (Salmonella, Staphylococcus aureus) must not be detected. Qualified finished products have a shelf life of ≥12 months at room temperature. Unqualified products are reworked or scrapped to ensure product quality meets national standards and market demands.

[0023] Compared with the prior art, the beneficial effects of this invention are as follows: 1. This invention uses a scientific blend of brown rice, oats, buckwheat, millet, and corn flour. The nutritional components of each grain complement each other, resulting in a product rich in dietary fiber, protein, B vitamins, and minerals. This solves the problem of the limited nutritional value of traditional rice crackers and meets consumers' demand for healthy and nutritious snacks. The entire process involves no high-temperature frying, avoiding the generation of harmful substances during frying. Furthermore, a natural preservative compound replaces chemical preservatives, further enhancing the product's healthiness and aligning with modern health-conscious food consumption trends.

[0024] 2. This invention constructs a flavor-oriented regulation system that combines flavor modifiers and process parameters. Through the scientific combination of disodium inosinate, yeast extract, and natural spice powder, the umami, richness, and natural spice flavor of the rice crust are precisely regulated, avoiding the problems of flavor imbalance and prominent off-flavors caused by single seasonings. Through processes such as low-temperature enzyme inactivation and gradient drying, the natural flavor of the grains and the effective components of the flavor modifiers are preserved to the maximum extent, resulting in a rich, harmonious, and natural flavor profile in the rice crust, with a crispy and mellow taste, free from artificial flavorings and the rough taste of grains, thus improving the product's palatability and market competitiveness.

[0025] 3. This invention employs a multi-stage synergistic preservation technology combining natural preservative compound, gradient drying, vacuum cooling, and high-barrier nitrogen-filled packaging. Rosemary extract, tea polyphenols, and ε-polylysine hydrochloride work synergistically to exert antioxidant and antibacterial effects, effectively inhibiting oil oxidation and deterioration and the growth of harmful microorganisms. Gradient drying precisely controls the moisture content of the rice crust, preventing excessive moisture and mold growth. Vacuum cooling rapidly lowers the temperature, preventing moisture regain and flavor loss. High-barrier nitrogen-filled packaging effectively blocks the influence of external oxygen, water vapor, and other factors, extending the product's shelf life at room temperature to ≥12 months. This solves the core problems of easy oxidation, moisture absorption, and short shelf life of rice crust in existing technologies, reducing losses during storage and transportation, and improving the product's market liquidity.

[0026] 4. This invention has precisely refined the process parameters for each processing stage. From grain pretreatment and extrusion cooking to gradient drying and vacuum cooling, the parameters for each stage have been optimized to ensure stable product quality. Low-temperature enzyme inactivation effectively inactivates lipase and peroxidase, delaying the oxidation of raw materials and preserving natural color and flavor. Twin-screw extrusion cooking improves starch gelatinization, ensuring that the rice crust is crispy and easy to digest. Gradient drying reduces the loss of flavor substances, improves crispness and flavor retention rate, and the final rice crust has a uniform color, crispy texture, rich aroma, crispness ≥8.5 kgf, flavor substance retention rate ≥92%, stable quality, and meets the quality requirements of industrial production. Attached Figure Description

[0027] Figure 1 This is a flowchart illustrating the overall process of a method for targeted flavor regulation and preservation of mixed grain rice crust proposed in this invention. Figure 2 This is a flowchart of step S1 of a method for directional regulation and preservation of flavor in a mixed grain rice crust proposed in this invention. Figure 3 This is a flowchart of step S2 of the method for directional regulation and preservation of flavor of mixed grain rice crust proposed in this invention. Figure 4This is a flowchart of step S3 of a method for targeted flavor regulation and preservation of mixed grain rice crust proposed in this invention. Figure 5 This is a flowchart of step S4 of a method for targeted flavor regulation and preservation of mixed grain rice crust proposed in this invention. Figure 6 This is a flowchart of step S5 of the method for targeted flavor regulation and preservation of mixed grain rice crust proposed in this invention. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Example

[0029] Reference Figure 1-6 As shown, a method for targeted flavor regulation and preservation of mixed grain rice crust includes the following steps: S1. Mixed Grain Blending and Pretreatment: By weight, select 45 parts brown rice, 20 parts oats, 15 parts buckwheat, 12 parts millet, and 8 parts corn flour. Select brown rice, oats, buckwheat, and millet that are free from mold, insects, and impurities. Rinse them three times with deionized water to remove surface dust and impurities, and place them in a forced-air drying oven. Dry them at 65℃ until the moisture content is 10%, and then cool them to room temperature for later use. Select food-grade corn flour that is free from mold and odor. Mix the above raw materials evenly, place them in a hot air drying oven, and bake them at 85℃ for 18 minutes to inactivate enzymes. Turn them over every 5 minutes. After baking, grind them to 90 mesh, sieve to remove impurities, and obtain mixed grain powder. The lipase activity of the mixed grain powder is 8 U / g, the peroxidase activity is 3 U / g, the moisture content is 9%, and the bulk density is 0.55 g / cm³.

[0030] S2. Flavor-oriented conditioning: Add flavor regulators and preservatives to the mixed grain powder obtained in step S1. Flavor regulators: 0.2 parts of disodium inosinate (IMP:GMP=1:1), 0.8 parts of yeast extract (82% protein content, 5% moisture content), and 0.3 parts of Sichuan pepper micro powder (110 mesh). Preservatives: 0.1 parts of rosemary extract (6% rosmarinic acid content), 0.05 parts of tea polyphenols (92% catechin content), and 0.03 parts of ε-polylysine hydrochloride (96% purity). Mix evenly using a high-speed mixer at a speed of 350 r / min for 12 min. After mixing evenly, slowly add deionized water to the material while stirring, adjusting the moisture content to 24%. After stirring evenly, allow the mixture to stand at 22℃ and 55% relative humidity for 25 min to obtain the conditioned material.

[0031] S3. Extrusion Curing and Molding: The conditioned material obtained in step S2 is fed into a stainless steel twin-screw extruder with a length-to-diameter ratio of 30:1. The extrusion curing parameters are: barrel zone 1 temperature 125℃, zone 2 temperature 135℃, die temperature 138℃, screw speed 200 r / min, die pressure 3.0 MPa, and feed rate 25 kg / h. After extrusion curing, the material is extruded through a rectangular die and immediately fed into a tablet press for tableting. The tablet thickness is 1.0 mm, and then it is granulated into 3.0 cm × 3.0 cm rice crust blanks. The rice crust blanks have a gelatinization degree of 93%, a bulk density of 0.40 g / cm³, and a hardness of 18 N. The tableting and granulation processes are carried out in a sterile environment with a cleanliness level of 100,000.

[0032] S4. Gradient Drying and Flavor Curing: The rice crust raw material obtained in step S3 is fed into a multi-layer belt dryer and subjected to three-stage gradient drying: the first stage drying temperature is controlled at 52℃, the air velocity is 1.8 m / s, and the drying time is 35 min; the second stage drying temperature is controlled at 62℃, the air velocity is 2.2 m / s, and the drying time is 22 min; the third stage drying temperature is controlled at 72℃, the air velocity is 2.8 m / s, and the drying time is 12 min; after the gradient drying is completed, the moisture content of the rice crust is 4.2%, the crispness is 8.8 kgf, the flavor substance retention rate is 94%, the color is golden yellow, and there are no scorch marks.

[0033] S5. Vacuum Cooling and Packaging: The semi-finished rice crust obtained in step S4 is immediately transferred to a vacuum cooler for vacuum cooling treatment. The vacuum degree is controlled at 0.085 MPa, the cooling time is 10 min, and the temperature is cooled to 22℃. Then, it is sent to a sterile workshop and packaged in nitrogen-filled and sealed 0.13 mm thick high-barrier aluminum foil bags. The nitrogen purity is 99.95%, the nitrogen filling pressure is 0.12 MPa, each bag weighs 30 g, the residual oxygen content in the bag after packaging is 0.8%, and there is no leakage during vacuum leak testing. Finished product inspection: Sensory indicators are qualified; Physicochemical indicators: Moisture 4.2%, Acid value 0.42 mg / g, Peroxide value 0.18 g / 100g, Oil content 7.2%; Microbiological indicators: Total bacterial count 850 CFU / g, Coliform bacteria 25 MPN / 100g, Mold 20 CFU / g, no pathogenic bacteria detected; qualified finished products remained stable in quality after 12 months of storage at room temperature, with no deterioration, mold, or softening, and the physicochemical and microbiological indicators still met national standards. Example

[0034] Reference Figure 1-6 As shown, a method for targeted flavor regulation and preservation of mixed grain rice crust includes the following steps: S1. Mixed Grain Blending and Pretreatment: By weight, select 40 parts brown rice, 25 parts oats, 10 parts buckwheat, 15 parts millet, and 10 parts corn flour. Select brown rice, oats, buckwheat, and millet that are free from mold, insects, and impurities. Rinse them twice with deionized water to remove surface dust and impurities, and place them in a forced-air drying oven. Dry them at 60℃ until the moisture content is 11%, and then cool them to room temperature for later use. Select food-grade corn flour that is free from mold and odor. Mix the above raw materials evenly, place them in a hot air drying oven, and bake them at 80℃ for 20 minutes to inactivate enzymes. Turn them over every 5 minutes. After baking, grind them to 80 mesh, sieve to remove impurities, and obtain mixed grain powder. The lipase activity of the mixed grain powder is 9 U / g, the peroxidase activity is 4 U / g, the moisture content is 9.5%, and the bulk density is 0.52 g / cm³.

[0035] S2. Flavor-oriented conditioning: Add flavor regulators and preservatives to the mixed grain powder obtained in step S1. Flavor regulators: 0.1 parts of disodium inosinate (IMP:GMP=1:1), 1.0 part of yeast extract (80% protein content, 6% moisture content), and 0.5 parts of star anise and cinnamon powder (100 mesh, 1:1 weight ratio). Preservatives: 0.05 parts of rosemary extract (5% rosmarinic acid content), 0.08 parts of tea polyphenols (90% catechin content), and 0.02 parts of ε-polylysine hydrochloride (95% purity). Mix evenly using a high-speed mixer at a speed of 300 r / min for 15 min. After mixing evenly, slowly add deionized water to the material while stirring, adjusting the moisture content to 22%. After stirring evenly, allow the mixture to stand at 20℃ and 50% relative humidity for 30 min to obtain the conditioned material.

[0036] S3. Extrusion Curing and Molding: The conditioned material obtained in step S2 is fed into a stainless steel twin-screw extruder with a length-to-diameter ratio of 28:1. The extrusion curing parameters are: barrel zone 1 temperature 120℃, zone 2 temperature 130℃, die temperature 135℃, screw speed 220 r / min, die pressure 2.5 MPa, and feed rate 20 kg / h. After extrusion curing, the material is extruded through a rectangular die and immediately fed into a tablet press for tableting. The tablet thickness is 0.8 mm, and then it is granulated into 2.5 cm × 2.5 cm rice crust blanks. The rice crust blanks have a gelatinization degree of 91%, a bulk density of 0.35 g / cm³, and a hardness of 15 N. The tableting and granulation processes are carried out in a sterile environment with a cleanliness level of 100,000.

[0037] S4. Gradient Drying and Flavor Curing: The rice crust raw material obtained in step S3 is fed into a multi-layer belt dryer and subjected to three-stage gradient drying: the first stage drying temperature is controlled at 50℃, the air velocity is 1.5 m / s, and the drying time is 40 min; the second stage drying temperature is controlled at 60℃, the air velocity is 2.0 m / s, and the drying time is 25 min; the third stage drying temperature is controlled at 70℃, the air velocity is 2.5 m / s, and the drying time is 15 min; after the gradient drying is completed, the moisture content of the rice crust is 3.5%, the crispness is 8.6 kgf, the flavor substance retention rate is 93%, the color is golden yellow, and there are no scorch marks.

[0038] S5. Vacuum Cooling and Packaging: The semi-finished rice crust obtained in step S4 is immediately transferred to a vacuum cooler for vacuum cooling treatment. The vacuum degree is controlled at 0.08 MPa, the cooling time is 12 min, and the temperature is cooled to 23℃. Then, it is sent to a sterile workshop and packaged in nitrogen-filled and sealed 0.12 mm thick high-barrier aluminum foil bags. The nitrogen purity is 99.92%, the nitrogen filling pressure is 0.1 MPa, each bag weighs 20 g, the residual oxygen content in the bag after packaging is 0.9%, and there is no leakage during vacuum leak testing. Finished product inspection: Sensory indicators are qualified; Physicochemical indicators: Moisture 3.5%, Acid value 0.38 mg / g, Peroxide value 0.15 g / 100g, Oil content 6.8%; Microbiological indicators: Total bacterial count 780 CFU / g, Coliform bacteria 20 MPN / 100g, Mold 18 CFU / g, no pathogenic bacteria detected; qualified finished products remained stable in quality after 12 months of storage at room temperature, with no deterioration, mold, or softening, and the physicochemical and microbiological indicators still met national standards. Example

[0039] Reference Figure 1-6 As shown, a method for targeted flavor regulation and preservation of mixed grain rice crust includes the following steps: S1. Mixed Grain Blending and Pretreatment: By weight, select 50 parts brown rice, 15 parts oats, 20 parts buckwheat, 10 parts millet, and 5 parts corn flour. Select brown rice, oats, buckwheat, and millet that are free from mold, insects, and impurities. Rinse them three times with deionized water to remove surface dust and impurities, and place them in a forced-air drying oven. Dry them at 70℃ until the moisture content is 10.5%, and then cool them to room temperature for later use. Select food-grade corn flour that is free from mold and odor. Mix the above raw materials evenly, place them in a hot air drying oven, and bake them at 90℃ for 15 minutes to inactivate enzymes. Turn them over every 5 minutes. After baking, grind them to 100 mesh, sieve to remove impurities, and obtain mixed grain powder. The lipase activity of the mixed grain powder is 7 U / g, the peroxidase activity is 2 U / g, the moisture content is 8.8%, and the bulk density is 0.58 g / cm³.

[0040] S2. Flavor-oriented conditioning: Add flavor regulators and preservatives to the mixed grain powder obtained in step S1. Flavor regulators: 0.3 parts of disodium inosinate (IMP:GMP=1:1), 0.5 parts of yeast extract (85% protein content, 4.5% moisture content), and 0.2 parts of bay leaf powder (120 mesh). Preservatives: 0.15 parts of rosemary extract (7% rosmarinic acid content), 0.03 parts of tea polyphenols (95% catechin content), and 0.05 parts of ε-polylysine hydrochloride (98% purity). Mix evenly using a high-speed mixer at a speed of 400 r / min for 10 min. After mixing evenly, slowly add deionized water to the material while stirring, adjusting the moisture content to 26%. After stirring evenly, allow the mixture to stand at 25℃ and 60% relative humidity for 20 min to obtain the conditioned material.

[0041] S3. Extrusion Curing and Molding: The conditioned material obtained in step S2 is fed into a stainless steel twin-screw extruder with a length-to-diameter ratio of 32:1. The extrusion curing parameters are: barrel zone 1 temperature 130℃, zone 2 temperature 140℃, die temperature 140℃, screw speed 180 r / min, die pressure 3.5 MPa, and feed rate 30 kg / h. After extrusion curing, the material is extruded through a rectangular die and immediately fed into a tablet press for tableting. The tablet thickness is 1.2 mm, and then it is granulated into 3.5 cm × 3.5 cm rice crust blanks. The rice crust blanks have a gelatinization degree of 95%, a bulk density of 0.45 g / cm³, and a hardness of 20 N. The tableting and granulation processes are carried out in a sterile environment with a cleanliness level of 100,000.

[0042] S4. Gradient Drying and Flavor Curing: The rice crust raw material obtained in step S3 is fed into a multi-layer belt dryer and subjected to three-stage gradient drying: the first stage drying temperature is controlled at 55℃, the air velocity is 2.0 m / s, and the drying time is 30 min; the second stage drying temperature is controlled at 65℃, the air velocity is 2.5 m / s, and the drying time is 20 min; the third stage drying temperature is controlled at 75℃, the air velocity is 3.0 m / s, and the drying time is 10 min; after the gradient drying is completed, the moisture content of the rice crust is 5.0%, the crispness is 9.0 kgf, the flavor substance retention rate is 95%, the color is golden yellow, and there are no scorch marks.

[0043] S5. Vacuum Cooling and Packaging: The semi-finished rice crust obtained in step S4 is immediately transferred to a vacuum cooler for vacuum cooling treatment. The vacuum degree is controlled at 0.09 MPa, the cooling time is 8.0 min, and the temperature is cooled to 24℃. Then, it is sent to a sterile workshop and packaged in nitrogen-filled and sealed 0.15 mm thick high-barrier aluminum foil bags. The nitrogen purity is 99.98%, the nitrogen filling pressure is 0.15 MPa, each bag weighs 50 g, the residual oxygen content in the bag after packaging is 0.7%, and there is no leakage during vacuum leak testing. Finished product inspection: Sensory indicators are qualified; Physicochemical indicators: Moisture 5.0%, Acid value 0.45 mg / g, Peroxide value 0.20 g / 100g, Oil content 7.5%; Microbiological indicators: Total bacterial count 920 CFU / g, Coliform bacteria 28 MPN / 100g, Mold 22 CFU / g, no pathogenic bacteria detected; qualified finished products remained stable in quality after 12 months of storage at room temperature, with no deterioration, mold, or softening, and the physicochemical and microbiological indicators still met national standards.

[0044] Comparative Example 1 (without using the flavor control system of this invention): Using the same raw materials and process as in Example 1, the only difference was that the flavor modifier was replaced with 0.3 parts of monosodium glutamate and 0.1 parts of artificial Sichuan pepper flavoring, while the other steps and parameters remained unchanged. The resulting rice crust had an abrupt umami flavor, lacked richness, had a harsh spicy flavor, and contained an artificial flavoring odor, resulting in a single flavor profile. According to the test, the flavor substance retention rate was only 78%, and after being stored at room temperature for 6 months, it showed a slight off-odor and a deteriorated taste.

[0045] Comparative Example 2 (without using the preservation system of this invention): Using the same raw materials and process as in Example 1, the only difference is that the preservative compound is removed and the packaging is changed to ordinary plastic packaging (without nitrogen filling), while the other steps and parameters remain unchanged. The resulting rice crust, after being stored at room temperature for 3 months, showed obvious oxidation and deterioration, darkened in color, softened in texture, and exceeded the total bacterial count (1500 CFU / g), making it inedible and with a shelf life of only 3 months.

[0046] Comparative Example 3 (without gradient drying): Using the same raw materials and process as in Example 1, the only difference was that gradient drying was replaced with single-temperature drying at 65°C for 65 minutes, while the other steps and parameters remained unchanged. The resulting rice crust had uneven moisture distribution, with some areas showing obvious scorch marks and others being under-dried. Its crispness was only 7.2 kgf, and the flavor retention rate was only 80%, resulting in inconsistent taste and unstable quality.

[0047] Table 1 compares the key parameters of raw materials and processes with their testing performance. Whole grains (by weight) Brown rice 45g, oats 20g, buckwheat 15g, millet 12g, corn flour 8g Brown rice 40g, oats 25g, buckwheat 10g, millet 15g, corn flour 10g Brown rice 50g, oats 15g, buckwheat 20g, millet 10g, corn flour 5g Same as Example 1 Same as Example 1 Same as Example 1 Flavor System Disodium inosinate, yeast extract, and Sichuan pepper powder Disodium inosinate, yeast extract, star anise and cinnamon powder Disodium inosinate, yeast extract, bay leaf powder MSG, artificial Sichuan pepper flavoring Same as Example 1 Same as Example 1 Preservation system Rosemary extract, tea polyphenols, ε-polylysine hydrochloride Rosemary extract, tea polyphenols, ε-polylysine hydrochloride Rosemary extract, tea polyphenols, ε-polylysine hydrochloride Same as Example 1 No preservatives, ordinary plastic packaging (non-nitrogen-filled) Same as Example 1 Drying method Three-stage gradient drying Three-stage gradient drying Three-stage gradient drying Three-stage gradient drying Three-stage gradient drying Single 65℃ constant temperature drying for 65 min Finished product moisture content (%) 4.2 3.5 5.0 4.2 4.2 Local unevenness, overall 4.2 Crispyness (kgf) 8.8 8.6 9.0 8.8 8.8 7.2 Flavor compound retention rate (%) 94 93 95 78 94 80 Acid value (mg / g) 0.42 0.38 0.45 0.42 Increased after storage 0.42 Peroxide value (g / 100g) 0.18 0.15 0.2 0.18 Significantly increased after storage 0.18 Total bacterial count (CFU / g) 850 780 920 850 Initially 850, 1500 after 3 months 850 Sensory properties of the finished product Golden brown with no burnt spots, rich and complex flavor. Light brown with no burnt spots, and a natural spicy flavor. Golden brown with no burnt spots, rich in flavor The umami flavor is abrupt, the artificial flavor is strong, and the overall taste is one-dimensional. It appears normal initially, but later becomes darker and softer. Uneven moisture content, burnt spots, poor taste Shelf life (at room temperature) Stable quality for 12 months Stable quality for 12 months Stable quality for 12 months It spoiled and its taste deteriorated after 6 months. Within just 3 months, the food deteriorated beyond acceptable limits. Quality remained inconsistent throughout the 12-month period. Table 2 compares the microbiological properties and storage performance of the finished products: Coliform bacteria (MPN / 100g) 24.3 25 Initially 25, later exceeded the standard 25 Mold (CFU / g) 20 20 Initially 20, later exceeded the standard 20 Pathogenic bacteria None detected Not detected Increased risk of late detection Not detected Store status for 12 months No spoilage, mold, or softening It deteriorated after 6 months Severely spoiled in 3 months Defects in taste and appearance persist. I. Comparative Analysis of Flavor Regulation System Effects (Example 1 and Comparative Example 1): Flavor profile: This invention uses a compound system of disodium inosinate, yeast extract, and natural spice powder, resulting in a rice crust with a rich and mellow umami flavor, natural aroma, and full-bodied flavor. In contrast, when Comparative Example 1 was replaced with monosodium glutamate and artificial flavorings, the umami flavor was harsh and abrupt, with a noticeable artificial flavoring odor and a monotonous flavor. Flavor retention: Example 1 showed a flavor substance retention rate of 94%, compared to only 78% in Comparative Example 1. The natural compound flavor system can effectively lock in flavor components and reduce processing losses.

[0048] Storage stability: Example 1 showed no flavor deterioration after 12 months of storage at room temperature; Comparative Example 1 showed rancidity and taste decline after only 6 months, indicating poor storage resistance of the artificial flavoring system; Conclusion: The flavor-directed regulation formula of this invention significantly improves flavor, taste, flavor retention rate and flavor stability compared to traditional monosodium glutamate and artificial flavorings.

[0049] II. Comparative Analysis of the Effects of Composite Preservation System and Nitrogen-Filled Packaging (Example 1 and Comparative Example 2): Antioxidant effect: In Example 1, a composite preservative of rosemary extract, tea polyphenols, and ε-polylysine hydrochloride was used, and the product was sealed in a high-barrier aluminum foil bag filled with nitrogen. The acid value and peroxide value of the finished product remained stable throughout the process. In Comparative Example 2, the preservative was removed and ordinary packaging was used. The oil oxidized rapidly and deteriorated in a short time.

[0050] Antibacterial effect: In Example 1, the microbial indicators met the standards for 12 months; in Comparative Example 2, the total number of colonies exceeded the standard limit after 3 months of storage, accompanied by mold, softening of the texture, and loss of edible value.

[0051] Shelf life: A complete preservation and nitrogen-filled packaging system maintained a stable shelf life of 12 months; without preservation measures, ordinary packaging only lasted 3 months, a significant difference. Conclusion: The combination of plant extracts and biological preservatives with high-barrier nitrogen-filled packaging can simultaneously achieve antioxidant and antibacterial effects, which is the core key to extending the shelf life of multigrain rice crackers.

[0052] III. Comparative Analysis of Gradient Drying Process Effects (Example 1 and Comparative Example 3): Appearance and form: Three-stage gradient drying results in a gradual temperature rise, with a uniform color and no scorch marks in the finished product; single constant temperature drying has problems such as local overheating and scorch marks, and local insufficient drying, resulting in uneven moisture distribution of the material.

[0053] Texture characteristics: The crispness of the finished product after gradient drying is 8.8 kgf, and the texture is crisp and uniform; the crispness of the product after constant temperature drying is reduced to 7.2 kgf, and the texture becomes hard and inconsistent.

[0054] Flavor Preservation: Gradient drying achieved a 94% retention rate of flavor compounds, while constant-temperature drying only achieved 80%. High-temperature, long-duration single-stage baking resulted in significant loss of volatile flavor compounds. Conclusion: The three-stage gradient drying process balances drying efficiency, finished product taste, appearance, and flavor preservation, making it far superior to the traditional single-stage constant-temperature drying process.

[0055] IV. Comparative Analysis of Different Grain Compounds and Processing Parameters (Examples 1 / 2 / 3): The three sets of embodiments adjusted the proportion of mixed grains, enzyme inactivation parameters, extrusion parameters, and types of spices, and the overall quality of the finished products was excellent. The changes in the raw material ratio mainly altered the basic flavor, color, and hardness of the finished products, and all physicochemical and microbiological indicators were qualified. After slight adjustments to the process parameters, the degree of gelatinization, crispness, and flavor retention fluctuated within a small range, indicating strong process adaptability and high stability. All three sets of products showed no deterioration after 12 months of storage at room temperature, demonstrating that the entire process formula of this invention has good fault tolerance and can flexibly adjust raw materials and parameters according to product positioning (flavor, specifications, and taste).

[0056] In summary, this invention employs a flavor-regulating compound system, relying on natural flavoring ingredients and spices to solve the problems of thin flavors in traditional seasonings and the easy deterioration of artificial flavors; it utilizes a composite preservation system and nitrogen-filled high-barrier packaging to synergistically resist oxidation and inhibit bacteria, extending the product shelf life from 3 months to 12 months, significantly improving product storage resistance; it employs a three-stage gradient drying process to optimize the heating method, improve the appearance and taste of the finished product, and reduce flavor loss; the entire process formula is mature and stable, with a wide range of adjustable parameters, making it valuable for industrial production applications.

[0057] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for targeted flavor regulation and preservation of mixed grain rice crust, characterized in that, Includes the following steps: S1. Mixed Grain Blending and Pretreatment: By weight, select 40-50 parts brown rice, 15-25 parts oats, 10-20 parts buckwheat, 10-15 parts millet, and 5-10 parts corn flour. Mix them evenly and place them in a hot air drying oven for low-temperature baking to inactivate enzymes. The baking temperature is controlled at 80-90℃ and the baking time is 15-20 minutes. During the baking process, turn the mixture over every 5 minutes to ensure even enzyme inactivation. After baking, send the mixed grain mixture into a universal grinder and grind it to 80-100 mesh. After grinding, sieve to remove impurities to obtain a mixed grain powder with uniform particle size. S2. Flavor-oriented conditioning: Add flavor regulator and preservative compound to the mixed grain powder obtained in step S1, and mix evenly using a high-speed mixer at a speed of 300-400 r / min for 10-15 min. The flavor regulator consists of the following components by weight: disodium inosinate 0.1-0.3 parts, yeast extract 0.5-1.0 parts, and natural spice powder 0.2-0.5 parts. The preservative compound consists of the following components by weight: rosemary extract 0.05-0.15 parts, tea polyphenols 0.03-0.08 parts, and ε-polylysine hydrochloride 0.02-0.05 parts. After mixing, slowly add deionized water to the material while stirring, adjust the moisture content of the material to 22%-26%, stir evenly, and let it stand for 20-30 min to obtain the conditioned material. S3. Extrusion Curing and Molding: The conditioned material obtained in step S2 is fed into a twin-screw extruder for extrusion curing. The process parameters for extrusion curing are controlled as follows: barrel zone 1 temperature 120-130℃, zone 2 temperature 130-140℃, die temperature 135-140℃, screw speed 180-220 r / min, die pressure 2.5-3.5 MPa, and feed rate 20-30 kg / h. After extrusion curing, the material is immediately fed into a tablet press for tableting, with the tablet thickness controlled at 0.8-1.2 mm. Then, it is fed into a pelletizer for pelleting, with a pellet size of 2.5-3.5 cm × 2.5-3.5 cm, to obtain the rice crust preform. S4. Gradient Drying and Flavor Curing: The rice crust raw material obtained in step S3 is fed into a multi-layer belt dryer for three-stage gradient drying. The first stage drying temperature is controlled at 50-55℃, the drying time is 30-40 min, and the air velocity is 1.5-2.0 m / s; the second stage drying temperature is controlled at 60-65℃, the drying time is 20-25 min, and the air velocity is 2.0-2.5 m / s; the third stage drying temperature is controlled at 70-75℃, the drying time is 10-15 min, and the air velocity is 2.5-3.0 m / s. After the gradient drying is completed, the final moisture content of the rice crust is reduced to 3.5-5.0%, and the flavor-cured rice crust semi-finished product is obtained. S5. Vacuum Cooling and Packaging: Immediately transfer the semi-finished rice crust obtained in step S4 into a vacuum cooler for vacuum cooling treatment. The vacuum degree is controlled at 0.08-0.09 MPa, and the cooling time is 8-12 minutes, until the rice crust temperature is ≤25℃. After cooling, the semi-finished rice crust is sent to a sterile workshop and packaged in high-barrier aluminum foil bags filled with nitrogen. The nitrogen purity is ≥99.9%, the nitrogen filling pressure is 0.1-0.15 MPa, and the residual oxygen content in the bag after packaging is ≤1.0%. After packaging, the finished product is inspected, and it is put into storage after passing the inspection.

2. The method for targeted flavor regulation and preservation of mixed grain rice crust according to claim 1, characterized in that, In step S1, the brown rice, oats, buckwheat, and millet are all pretreated. The pretreatment steps are as follows: select brown rice, oats, buckwheat, and millet that are free from mold, insects, and impurities, rinse them 2-3 times with deionized water to remove surface dust and impurities, and then place them in a forced-air drying oven to dry them at 60-70℃ until the moisture content is ≤12%. After drying, cool them to room temperature for later use. After low-temperature baking to inactivate enzymes, the lipase activity of the mixed grain powder is ≤10 U / g, and the peroxidase activity is ≤5 U / g. The moisture content of the mixed grain powder is ≤10%, and the bulk density is 0.5-0.6 g / cm³.

3. The method for targeted flavor regulation and preservation of mixed grain rice crust according to claim 1, characterized in that, In step S2, the natural spice powder is one or more of Sichuan pepper, star anise, cinnamon, and bay leaves, and the weight ratio of each component is arbitrary. The preparation method of the natural spice powder is as follows: select natural spices that are free from mold and odor, clean them, dry them at 55-65℃ until the moisture content is ≤8%, pulverize them to 100-120 mesh, sieve them, seal and store them for later use. The disodium inosinate is disodium 5'-inosinate. The compound of (IMP) and disodium 5'-guanylate (GMP) is present in a weight ratio of 1:1; the yeast extract has a protein content ≥80% and a moisture content ≤6%; the rosemary extract has a rosmarinic acid content ≥5%, a catechin content of tea polyphenols ≥90%, and a purity of ε-polylysine hydrochloride ≥95%; in the preservative compound, the weight ratio of rosemary extract, tea polyphenols, and ε-polylysine hydrochloride is 3:2:1 to 5:3:

1.

4. The method for targeted flavor regulation and preservation of mixed grain rice crust according to claim 1, characterized in that, In step S3, the twin-screw extruder has a screw length-to-diameter ratio of 28:1 to 32:1, a barrel made of stainless steel, and a rectangular die head with dimensions matching the size of the rice crust blank. After extrusion and curing, the rice crust blank has a gelatinization degree ≥90%, a bulk density of 0.35 to 0.45 g / cm³, and a hardness of 15 to 20 N.

5. The method for targeted flavor regulation and preservation of mixed grain rice crust according to claim 1, characterized in that, In step S4, during the gradient drying process, the thickness of the rice crust blanks is 1-2 cm, and the spacing between adjacent blanks is ≥1 cm to ensure uniform drying. After gradient drying, the crispness of the rice crusts is ≥8.5 kgf, the flavor substance retention rate is ≥92%, and the color is golden yellow to light brown with no scorch marks.

6. The method for targeted flavor regulation and preservation of mixed grain rice crust according to claim 1, characterized in that, In step S5, the thickness of the high-barrier aluminum foil bag is 0.12-0.15 mm, the oxygen permeability is ≤5 cm³ / (m²·24h·atm), and the water vapor permeability is ≤3 g / (m²·24h). During packaging, the weight of each bag of rice crust is 20-50 g. After packaging, vacuum leak testing is performed to ensure that there is no air leakage.

7. The method for targeted flavor regulation and preservation of mixed grain rice crust according to claim 1, characterized in that, In step S5, the finished product inspection items include: sensory indicators, physicochemical indicators, and microbiological indicators; sensory indicators: uniform color, no scorch marks, no mold, crisp texture, rich aroma, no off-flavors, and no bitterness; physicochemical indicators: moisture content 3.5-5.0%, acid value ≤3.0 mg / g, peroxide value ≤0.25 g / 100g, oil content ≤8%; microbiological indicators: total bacterial count ≤1000 CFU / g, coliform bacteria ≤30 MPN / 100g, mold ≤25 CFU / g, and pathogenic bacteria (Salmonella, Staphylococcus aureus) must not be detected; the finished product that passes the inspection has a shelf life of ≥12 months at room temperature.

8. The method for targeted flavor regulation and preservation of mixed grain rice crust according to claim 1, characterized in that, In step S2, the ambient temperature during the static conditioning process is controlled at 20-25°C and the relative humidity is controlled at 50-60% to prevent the material from absorbing moisture or losing water.

9. The method for targeted flavor regulation and preservation of mixed grain rice crust according to claim 1, characterized in that, In step S3, after extrusion and ripening, the tableting and pelleting processes are carried out in a sterile environment to avoid material contamination.

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