A whole grain food processing method for realizing accurate recombination of texture

Abstract

The application discloses a whole grain food processing method for realizing accurate restructuring of texture, comprising the following steps: a raw material pretreatment and activation process, a targeted enzymatic modification process and a multi-mode field extrusion restructuring process. The application integrates and cooperates the three technologies of "physical pretreatment", "targeted enzymatic modification" and "multi-mode field extrusion" in a program, forming a continuous regulation chain. The technology chain can accurately modify the macromolecular structure of each component in the whole grain in steps, regulate the interaction force therebetween, thereby directionally restructuring the three-dimensional network structure at the molecular and supramolecular levels, and finally realizing the predictable and customizable intelligent conversion from "raw material characteristics" to "final product texture".

Description

Technical Field

[0001] This invention relates to the technical field of functional whole grain foods, specifically to a green and precise processing method that achieves precise textural design and recombination by synergistically regulating the interaction between starch, protein and dietary fiber in whole grains. Background Technology

[0002] Whole grain foods, which retain the bran, germ, and endosperm of the grain, are rich in dietary fiber, vitamins, and minerals, and their health benefits are increasingly favored by consumers. However, the high content of insoluble fiber and fat in the bran poses significant technical challenges to food processing; existing whole grain foods are typically coarse in texture, hard, and prone to oxidation and rancidity, and have poor processing adaptability, making it difficult to provide a pleasant taste while satisfying the requirements of "complete nutrition." This contradiction severely restricts the application and market acceptance of whole grain foods in high-value-added sectors.

[0003] In existing technologies, the main methods for improving the palatability of whole grain foods include:

[0004] (1) Ultrafine physical pulverization method: By pulverizing grains into ultrafine powder with a particle size ≤100 μm, the rough texture is masked by reducing the particle size. However, this physical pulverization method will damage the cell wall structure of grains. When the dietary fiber structure in the grain cell wall is damaged, the vitamins (such as B vitamins) bound in it will be more easily lost with the loss of water. At the same time, the minerals in the cells (such as iron, zinc, etc.) will also be more easily dissolved and lost due to the damage to the cell structure.

[0005] (2) Adding chemical additives: exogenous colloids, emulsifiers, modifiers and other additives can improve texture, but this method goes against the current trend of "clean label" and natural and healthy food consumption and cannot meet the needs of the high-end food market.

[0006] (3) Thermal processing method: Traditional single-screw extrusion puffing or high-temperature baking is used to improve the palatability of food; however, such methods often only bring a single "crispy" texture and cannot achieve systematic and predictable control of the multi-dimensional textural properties of the product, such as crispness, toughness, chewiness, and smoothness; in addition, in the traditional single-screw extrusion puffing process, due to the high temperature and high pressure environment, amino acids and reducing sugars will undergo Maillard reaction, which will then produce acrylamide. The specific generation pathway is that the amino group of amino acids and the carbonyl group of reducing sugar undergo a series of complex reactions at a certain temperature to gradually generate acrylamide.

[0007] Therefore, the food industry urgently needs a green and precise processing technology that can intervene in and reorganize the interaction network of the three core components of whole grains—starch, protein, and dietary fiber—at the molecular level without relying on chemical additives and while preserving nutrients to the maximum extent. This technology can then be used to freely design and achieve diverse ideal textures according to needs. Summary of the Invention

[0008] This invention aims to provide a whole-grain food processing method for achieving precise textural remodeling. It achieves precise textural remodeling of whole grains through the synergistic regulation of starch, protein, and fiber, obtaining diverse textures of whole-grain foods according to specific needs. The core of this invention lies in the programmed integration and synergistic application of three technologies: "physical pretreatment," "targeted enzymatic hydrolysis," and "multi-modal field extrusion," forming a continuous regulatory chain. This technology chain can precisely modify the macromolecular structure of each component in the whole grain step by step, regulating the interaction forces between them, thereby directionally reconstructing its three-dimensional network structure at the molecular and supramolecular levels. Ultimately, this achieves a predictable and customizable intelligent transformation from "raw material characteristics" to "final product texture."

[0009] The above-mentioned objectives of the present invention are achieved through the following technical solutions.

[0010] A method for processing whole grain foods to achieve precise textural restructuring, characterized by comprising the following steps:

[0011] (1) Raw material pretreatment and activation process: The initial moisture content of whole grain raw materials obtained by ordinary crushing is adjusted to 16%~22% by spray wetting method, and then placed under a micro hot air of 60~85℃ for 10~30 minutes to make the starch crystallization zone destruction rate reach 20%~40% to obtain pretreated activated material;

[0012] It should be noted that the whole grain raw materials used in this invention are powders obtained through ordinary grinding, used only to meet the flowability requirements of subsequent extrusion processing. This grinding level only damages about 30% of the grain cell walls, and will not lead to a large loss of nutrients. The core mechanism of this invention in improving palatability does not rely on reducing particle size, but rather on reconstructing the texture network of whole grains at the molecular level through subsequent micro-hot air activation, targeted enzymatic modification, and multi-modal field extrusion recombination, fundamentally solving the problem of the rough texture of whole grains.

[0013] (2) Targeted enzymatic hydrolysis modification process: The pretreated activated material is placed in an environment containing a complex enzyme system and subjected to a short-term, controllable enzymatic hydrolysis reaction to obtain the enzymatically modified material; the conditions of the enzymatic hydrolysis reaction are controlled at a temperature of 40~55 ℃, pH of 4.5~6.5, and a time of 5~20 minutes to obtain the enzymatically modified material.

[0014] The complex enzyme system is composed of at least one amylase and at least one hemicellulase, or of at least one amylase, at least one protease and at least one hemicellulase.

[0015] The complex enzyme system is selected based on the textural characteristics of the target product, and on the correspondence between the enzyme's target site, component molecule modification, and textural formation, with a targeted selection of the type and proportion of enzyme preparations.

[0016] (3) Multi-stage extrusion and recombination process: The enzymatically modified material is fed into a co-rotating twin-screw extruder with three independently temperature-controlled barrel sections. After three-stage controlled extrusion molding, whole grain semi-finished products are obtained. Among them, barrel section I: temperature 80~110 ℃, screw speed 200~400 rpm; barrel section II: temperature 100~130 ℃, screw speed 150~350 rpm, vacuum dehydration system is turned on, vacuum degree is -0.06~ -0.09MPa; barrel section III: temperature 90~120 ℃;

[0017] (4) Post-processing: Drying, baking, crushing or sieving according to product requirements to obtain the final whole grain food.

[0018] This invention achieves precise textural recombination of whole grains through sequential raw material pretreatment and activation, targeted enzymatic hydrolysis modification, and multi-modal extrusion recombination. This allows for the free design and acquisition of whole grain foods with diverse textures according to specific needs. The principle behind each step of this invention is as follows:

[0019] 1. In the raw material pretreatment and activation process, micro-hot air treatment is used to activate whole grain raw materials: The effect of micro-hot air treatment on starch is that the crystalline region of some starch molecules is destroyed and the proportion of amorphous region increases, thereby achieving partial pregelatinization; the effect on protein is that the spatial structure of protein molecules is moderately changed, and some hydrogen bonds and other forces are destroyed, resulting in moderate denaturation of protein; the effect on dietary fiber is that the intermolecular forces of dietary fiber are weakened and the fiber structure is softened, thereby laying the foundation for subsequent deep intermolecular interactions, rather than simple drying or cooking.

[0020] 2. Targeted enzymatic modification processes act like "molecular scissors," aiming to precisely and controllably "cut" the molecular chains of starch, protein, and cellulose. Without producing excessive amounts of small sugars and amino acids, this exposes more hydrophilic / hydrophobic sites, reducing ends, and active groups, fundamentally altering their functional properties. For example, mesophilic α-amylase acts on the amorphous regions of starch, causing the starch molecular chains to break at these locations, producing more short-chain starch molecules. These short-chain starch molecules are more easily dispersed and dissolved in cold water, thus improving the cold water solubility of starch. Neutral proteases act on cereal storage proteins, cleaving the protein molecular chains at specific peptide bonds, turning the protein molecules into shorter peptides with better emulsifying and gelling abilities. Xylanase acts on cell wall cellulose, breaking down cellulose molecular chains, increasing the surface area of ​​the fiber, and improving its water-holding capacity.

[0021] 3. The multi-mold extrusion and recombination process achieves the final assembly and locking of material texture by precisely controlling the temperature field, shear force field and moisture evaporation rate of different barrel sections.

[0022] ① Barrel I zone: High-shear melting and homogenization zone, temperature 80~110 ℃, screw speed 200~400 rpm; different numbers and staggered angles of kneading blocks are configured according to the target texture: 3~5 groups of medium shear (staggered angle 45°) or 0~2 groups of weak shear (staggered angle ≤30°); under the action of shear force, the activated and modified starch, protein and fiber are fully mixed and melted to form a homogeneous biopolymer melt;

[0023] ② Barrel II Zone: Structured network formation zone, temperature 100~130 ℃, screw speed 50 rpm lower than in Barrel I Zone, reducing material moisture to 15%~25%; the kneading block configuration in Barrel II Zone needs to match the shear strength of Barrel I Zone: medium shear system can be configured with 1~2 sets of 45° kneading blocks, low shear system, high elasticity products all use conveying elements, and instant products can be configured with 0~1 sets of 30°~45° kneading blocks; under these conditions, gelatinized starch chains interact with dextrin and non-starch polysaccharides (β-glucan) produced by hydrolysis; at the same time, denatured protein molecules crosslink with fiber fragments through disulfide bonds, hydrophobic interactions, etc., initially forming a composite three-dimensional network framework that supports the product texture;

[0024] ③ Barrel III zone: Texture fine-tuning and final shaping zone, temperature 90~120 ℃. By changing the shape and size of the mold and controlling the cooling rate and pressure expansion degree when the melt exits the mold, the macroscopic morphology of the product, such as particles, strips, and flakes, and the microstructure, such as dense, uniform porous, and layered fiber, are ultimately determined, thereby locking in the required texture properties.

[0025] The three steps described above constitute a tightly linked and synergistic technical system: physical pretreatment is "activation and preparation," targeted enzymatic hydrolysis is "precise modification and empowerment," and multi-modal extrusion is "co-assembly and final shaping." Within the scope defined by this invention, by adjusting the combination of key parameters such as pretreatment temperature-time, enzyme type and ratio, and temperature-shear-moisture ratio in each extrusion zone, the hardness, brittleness, elasticity, cohesiveness, and resilience of the final product can be digitally designed and precisely replicated, much like adjusting a formula.

[0026] Preferably, in step (1), the particle size of the whole grain raw material is 100~500 μm, which meets the flowability requirements of subsequent extrusion processing.

[0027] Preferably, in step (1), the relative humidity of the hot air is adjusted to 40%~70% and the wind speed is 0.5~2 m / s by a closed-loop humidity control system so that the moisture content of the material is maintained at 14%~22% after micro-hot air treatment.

[0028] Preferably, in step (2), the selection principle for the type of enzyme preparation is as follows:

[0029] ①Amylase: Regulates the crispness and solubility of food; specifically: for high-crisp products, select medium-temperature α-amylase to break down long-chain starch into medium-dextrin and promote puffing; for high-elasticity products, select amyloglucosidase to produce a small amount of natural sweetness and retain long-chain starch to maintain its structure; for instant products, select pullulanase to hydrolyze the branching points of amylopectin and improve cold water solubility.

[0030] ② Proteases: Regulate the elasticity and chewiness of food; specifically: for products with high crispness, choose neutral proteases to produce medium peptides and improve emulsification; for products with high elasticity, choose flavor proteases for gentle hydrolysis, preserving the core protein structure to form a gel network; for instant products, add a small amount or none at all to avoid viscosity reduction.

[0031] ③ Hemicellulase: Regulates the smoothness of food; specifically: for high-brittle products, choose xylanase to break down fiber rigidity; for high-elasticity products, choose a small amount of β-glucanase to reduce material viscosity; for instant products, choose cellulase to open up the fiber structure and prevent clumping.

[0032] Preferably, in step (2), the amount of all enzyme preparations added is calculated based on the dry weight of the corresponding component; specifically, the amount of amylase added is 0.02%~0.2% of the dry weight of the total starch in the raw material; the amount of protease added is 0.05%~0.3% of the dry weight of the total protein in the raw material; and the amount of hemicellulase added is 0.01%~0.1% of the total dry weight of the whole grain raw material. The present invention uses the corresponding component dry weight as the basis, which can eliminate the influence of the difference in component content between different raw materials on the degree of enzymatic hydrolysis. The enzyme preparations used in this invention all adopt food-grade standard enzyme activity, such as: mesophilic α-amylase: enzyme activity ≥2000 U / g (GB / T 1886.174-2016); neutral protease: enzyme activity ≥50000 U / g (GB / T 23527.1-2023); xylanase: enzyme activity ≥10000 U / g (GB / T 7300.401-2019); the enzyme activity of other enzyme preparations all meet the corresponding national or industry standards.

[0033] Preferably, in step (2), after the enzymatic hydrolysis reaction is completed, the temperature is rapidly raised to 85 °C and maintained for 2 minutes to completely inactivate the enzyme and obtain the enzymatically modified material.

[0034] Preferably, the length-to-diameter ratio of the twin-screw extruder is (40~60):1.

[0035] Preferably, in step (3), shear strength and moisture content are precisely selected based on the textural properties of the target product:

[0036] ① High-brittleness puffed food: 3-5 sets of staggered 45° mid-shear kneading blocks are set in barrel I, and 1-2 sets of kneading blocks at the same angle can be set in barrel II; the screw speed in barrel I is 250-400 rpm, and the screw speed in barrel II is 200-350 rpm;

[0037] ② High-elasticity nutritional food: Zone I of the barrel is equipped with 0~1 sets of weak shear kneading blocks with a staggered angle ≤30°, and Zone II of the barrel is entirely equipped with conveying elements; the screw speed in Zone I of the barrel is 100~200 rpm, and the screw speed in Zone II of the barrel is 50~150 rpm;

[0038] ③ Cold water instant cereal powder: 1-2 sets of kneading blocks with staggered angles of 30°-45° are set in barrel I, and 0-1 sets of kneading blocks with the same angle can be set in barrel II; the screw speed in barrel I is 200-300 rpm, and the screw speed in barrel II is 150-250 rpm.

[0039] The mechanism by which this invention utilizes shear strength to regulate texture is as follows:

[0040] ① High shear can completely destroy the residual starch crystal zone and fiber aggregates, so that the three major components can be fully dispersed and interact with each other to form a uniform continuous phase melt. When the product is demolded, the moisture evaporates evenly, resulting in strong and uniform expansion, forming a honeycomb structure with thin walls and large pores, giving the product an extremely crispy texture.

[0041] ② Low shear can preserve the complete structure of protein molecules to the greatest extent, avoid excessive breakage of protein molecular chains, and enable proteins to form a continuous and dense three-dimensional network skeleton through disulfide bonds and hydrophobic interactions during extrusion, giving the product good elasticity and chewiness.

[0042] ③Medium shear ensures thorough mixing of components without excessively damaging the molecular structure of starch and fiber, maintaining a suitable chain length distribution for starch and good water retention for fiber, thus giving the product excellent cold water solubility and a smooth mouthfeel.

[0043] Preferably, in step (3), the total residence time of the material in the twin-screw extruder is 15 to 30 seconds, while the residence time in barrel zone II (high temperature zone) is only 5 to 10 seconds.

[0044] Compared with the prior art, the present invention has the following significant advantages:

[0045] 1. Clean label production: The entire process does not rely on any exogenous food colloids, emulsifiers, thickeners or other chemical additives. It achieves the texture target only by controlling the composition of the raw materials themselves, which is in line with the market trend of high-end health foods.

[0046] 2. Precise and controllable texture: This invention breaks through the limitation of the single texture in traditional whole grain processing. Through modular combination of process parameters, it is possible to produce products with different texture profiles, ranging from "extremely crisp" (hardness ≤500 g, crispness ≥80%) to "highly flexible and elastic" (elasticity ≥0.8, chewiness ≥2000 g·s) and then to "smooth and delicate" (cold water dissolution time ≤30s), which can meet the specific needs of diverse scenarios such as snacks, meal replacements, and special dietary foods.

[0047] 3. High nutrient retention: The pretreatment and enzymatic hydrolysis conditions are mild (temperature ≤85 ℃, time ≤30 minutes), avoiding the destruction of heat-sensitive nutrients by high temperatures; the extrusion process is extremely short: the entire process is gentle, and the time spent in the high-temperature zone during extrusion is only 5~10 seconds, which is much shorter than traditional processes; the dietary fiber retention rate is ≥95%, the B vitamin retention rate is ≥80%, and the polyphenol retention rate is ≥75%, achieving a balance between nutrition and taste.

[0048] 4. Low food safety risk: This invention systematically inhibits acrylamide formation from three dimensions: temperature, time, and substrate. The maximum extrusion temperature is only 130 ℃, and it is only maintained briefly in zone II of the barrel. The residence time in the high-temperature zone is only 5-10 seconds. The degree of hydrolysis is strictly controlled at 5%-15% during the targeted enzymatic hydrolysis process to avoid the generation of excessive free reducing sugars and free amino acids. The acrylamide content of the final product is ≤50 μg / kg.

[0049] 5. Wide applicability and good industrialization prospects: This method is applicable to a variety of common whole grain raw materials such as brown rice, black rice, oats, wheat, corn, quinoa, and highland barley. The process route is clear and easy to upgrade based on existing food processing equipment, and it has the potential for large-scale industrialization. Attached Figure Description

[0050] Figure 1 The following are scanning electron microscope (SEM) schematic diagrams (magnification: 500×) of the microstructure of three typical textured whole grain products prepared through Examples 1-3. Among them, (A) shows the open, thin-walled, porous honeycomb structure of high-brittle whole grain puffed snacks; (B) shows the dense, continuous, and uniform protein-fiber network structure of high-elasticity nutrition bars; and (C) shows the instant structure of instant whole grain porridge powder with microporous particles on the surface and loose internal structure. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to embodiments. The following embodiments are for illustrative purposes only and are not intended to limit the invention.

[0052] Example 1: Preparation of high-brittleness whole-grain puffed snacks

[0053] (1) Raw material pretreatment and activation process: Weigh 80 kg of brown rice flour and 20 kg of whole wheat flour (both are conventionally ground, with a particle size of 150~300 μm), mix them evenly, spray them to adjust the initial moisture to 18%, place them in a fluidized bed and treat them with a little hot air for 20 minutes at 75 ℃, 55% relative humidity, and 1.2 m / s wind speed. After the treatment, the moisture content of the material is 16.5%, and the pretreated activated material is obtained.

[0054] (2) Targeted enzymatic hydrolysis modification process: Add compound enzyme solution: medium-temperature α-amylase at 0.05% of total starch dry basis, neutral protease at 0.1% of total protein dry basis, and xylanase at 0.02% of total material dry basis. React at 50 ℃ and pH 6.0 for 10 minutes, then rapidly heat to 85 ℃ and hold for 2 minutes to inactivate the enzymes, to obtain the enzymatically modified material.

[0055] (3) Multi-die extrusion and recombination process: The enzymatically modified material is fed into a co-rotating twin-screw extruder with a length-to-diameter ratio of 50:1. The barrel I zone is 95 ℃, the screw speed is 300 rpm, and 4 sets of kneading blocks with a staggered angle of 45° are configured; the barrel II zone is 125 ℃, the screw speed is 250 rpm, 2 sets of kneading blocks with a staggered angle of 45° are configured, the vacuum degree is -0.08MPa, and the moisture content is reduced to 18%; the barrel III zone uses a circular small-hole mold with a diameter of 1.5 mm, the total residence time of the material is 22 seconds, the residence time in the high-temperature zone is 7 seconds, and the high-temperature melt expands instantaneously to obtain a semi-finished product.

[0056] (4) Post-processing: Dry at 50 ℃ for 1 hour to obtain the finished product.

[0057] The product obtained in this embodiment has the following characteristics: golden color, extremely crisp and light texture, melts in the mouth, and has a rich whole wheat roasted aroma. Its microstructure is a typical thin-walled, large-pore honeycomb structure (e.g., Figure 1 (As shown in A). No leavening agents are required, and the acrylamide content is 32 μg / kg, which meets the requirements of the clean label.

[0058] Comparative Example 1: Preparation of Highly Brittle Whole Grain Puffed Snacks by Traditional Single-Screw Extrusion Puffing

[0059] Using the same raw material ratio as in Example 1, without pretreatment or enzymatic hydrolysis, the raw materials were directly fed into a single-screw extruder at an extrusion temperature of 170 ℃ and a screw speed of 150 rpm. After extrusion and expansion, the finished product was obtained by drying.

[0060] Comparison results: The product has a hardness of 850 g, a brittleness of 65%, and a volume expansion rate of 220%; the retention rate of B vitamins is 42%, the retention rate of polyphenols is 51%; and the acrylamide content is 580 μg / kg, exceeding the national standard limit.

[0061] Example 2: Preparation of High-Elasticity, Chewable Whole Grain Nutritional Bars

[0062] (1) Raw material pretreatment and activation process: The raw materials are 40 kg of brown rice flour, 20 kg of whole oat flour, 20 kg of black rice flour, 10 kg of quinoa flour and 10 kg of chia seed flour (all are conventionally ground, with a particle size of 150~300 μm). After being mixed evenly, the initial moisture content is adjusted to 22% by spraying. The material is then treated with a gentle hot air for 30 minutes at 65 ℃, 65% relative humidity, and 0.8 m / s wind speed. After the treatment, the moisture content of the material is 20%, and the pretreated activated material is obtained.

[0063] (2) Targeted enzymatic hydrolysis modification process: Add compound enzyme solution: starch glucosidase at 0.01% of total starch dry basis and flavor protease at 0.15% of total protein dry basis; react at 45 ℃ and pH 5.5 for 15 minutes, then rapidly heat to 85 ℃ and hold for 2 minutes to inactivate the enzyme, and obtain the enzymatically modified material.

[0064] (3) Multi-die extrusion and reorganization process: fed into a twin-screw extruder with a length-to-diameter ratio of 50:1. Barrel I zone: 85 ℃, screw speed 200 rpm, only one set of weak shear kneading blocks with a staggered angle of 30° is configured; Barrel II zone: 110 ℃, screw speed 150 rpm, all using conveying elements, vacuum degree -0.06MPa, moisture retention 25%; Barrel III zone uses a narrow and flat die with a width of 10 mm and a height of 5 mm, the total material residence time is 28 seconds, the residence time in the high temperature zone is 9 seconds, and after extrusion, it is cooled and formed into a rod blank.

[0065] (4) Post-processing: Baking at 60 ℃ for 2 hours to obtain high elastic whole grain nutrition bars.

[0066] The product obtained in this embodiment has the following characteristics: dense and elastic texture, strong chewiness, no crumbling, and long-lasting satiety. Texture analyzer testing showed: hardness 1200 g, elasticity 0.85, and chewiness 2600 g. s. The microstructure is a dense, continuous protein, fibrous network structure ( Figure 1 B). No leavening agents or chemical additives are required, meeting clean label requirements. Suitable as a sports nutrition meal replacement or healthy snack.

[0067] Comparative Example 2: Preparation of Whole Grain Nutrition Bars Using Traditional Processes

[0068] Using the same raw material ratio as in Example 2, without pretreatment or enzymatic hydrolysis, the mixture was directly mixed and 10% maltose syrup was added as a binder. After pressing and molding, the finished product was obtained by baking.

[0069] Comparison results: Product hardness 2100 g, elasticity 0.52, chewiness 1100 g It has a dry, hard texture that easily crumbles; it contains exogenous binders, which does not meet the requirements for cleanliness labels; the retention rate of B vitamins is 58%, and the retention rate of polyphenols is 62%.

[0070] Example 3: Preparation of a smooth-textured, quick-dissolving whole-grain instant porridge powder that dissolves rapidly in cold water

[0071] (1) Raw material pretreatment and activation process: The raw materials are 40 kg of whole corn flour, 30 kg of brown rice flour and 30 kg of whole barley flour (all are conventionally ground, with a particle size of 150~300 μm). After being mixed evenly, the initial moisture content is adjusted to 16% by spraying and wetting. The material is then treated with a small amount of hot air for 15 minutes at 80℃, 45% relative humidity and 1.5 m / s wind speed. After the treatment, the moisture content of the material is 14.5%, and the pretreated activated material is obtained.

[0072] (2) Targeted enzymatic hydrolysis modification process: Add compound enzyme solution: cellulase at 0.05% of the total dry basis of the material and pullulanase at 0.01% of the total dry basis of starch; react at 55 ℃ and pH 5.0 for 12 minutes, then rapidly heat to 85 ℃ and hold for 2 minutes to inactivate the enzyme, and obtain the enzymatically modified material.

[0073] (3) Multi-die extrusion and recombination process: The material is moistened to 30% (wet basis) and fed into a co-rotating twin-screw extruder with a length-to-diameter ratio of 50:1. The barrel I zone is 90 ℃, the screw speed is 250 rpm, and two sets of kneading blocks with a staggered angle of 30° are configured; the barrel II zone is 100 ℃, the screw speed is 200 rpm, one set of kneading blocks with a staggered angle of 30° is configured, the vacuum degree is -0.07MPa, and the moisture content is controlled at about 22%; the barrel III zone is connected to a 40 ℃ low-temperature granulation die, the total residence time of the material is 20 seconds, the residence time in the high-temperature zone is 6 seconds, and uniform columnar granules are obtained by extrusion.

[0074] (4) Post-processing: The extrudate is instantly dried into porous particles by cold air and then lightly crushed and passed through an 80-mesh sieve.

[0075] The product obtained in this embodiment has the following characteristics: the powder dissolves and gelatinizes in room temperature water or cold milk within 22 seconds, and after mixing, it forms a uniform, smooth, and porridge-like consistency without any rough particles, with a naturally released sweetness. The microstructure of the particles is porous and sponge-like (e.g., Figure 1 (As shown in C), which greatly improves the convenience of eating and the taste experience.

[0076] Comparative Example 3: Preparation of Whole Grain Instant Porridge Powder by Traditional Extrusion Method

[0077] Using the same raw material ratio as in Example 3, without pretreatment or enzymatic hydrolysis, the raw materials were directly fed into a twin-screw extruder at an extrusion temperature of 150 ℃ and a screw speed of 300 rpm. After extrusion, the raw materials were dried, pulverized, and passed through an 80-mesh sieve to obtain the finished product.

[0078] Comparative results: The cold water dissolution time was 120 s, and a large number of undissolved particles remained after mixing, resulting in a rough texture; the retention rate of B vitamins was 45%, and the retention rate of polyphenols was 48%; the acrylamide content was 210 μg / kg, which is more than 6 times that of Example 3.

Claims

1. A method for processing whole grain foods to achieve precise textural recombination, characterized in that, Includes the following steps: (1) Raw material pretreatment and activation process: The initial moisture content of whole grain raw materials obtained by ordinary crushing is adjusted to 16%~22% by spray wetting method, and then placed under a micro hot air of 60~85℃ for 10~30 minutes to make the starch crystallization zone destruction rate reach 20%~40% to obtain pretreated activated material; (2) Targeted enzymatic hydrolysis modification process: The pretreated activated material is placed in an environment containing a complex enzyme system and subjected to a short-term, controllable enzymatic hydrolysis reaction to obtain the enzymatically modified material; the conditions of the enzymatic hydrolysis reaction are controlled at a temperature of 40~55 ℃, pH of 4.5~6.5, and a time of 5~20 minutes to obtain the enzymatically modified material. The complex enzyme system is composed of at least one amylase and at least one hemicellulase, or of at least one amylase, at least one protease and at least one hemicellulase. The complex enzyme system is selected based on the textural characteristics of the target product, and on the correspondence between the enzyme's target site, component molecule modification, and textural formation, with a targeted selection of the type and proportion of enzyme preparations. (3) Multi-mode extrusion and recombination process: The enzymatically modified material is fed into a co-rotating twin-screw extruder with three independently temperature-controlled barrel sections, and is extruded and formed in three stages to obtain whole grain semi-finished products; The barrel is divided into three zones: Zone I: temperature 80~110 ℃, screw speed 200~400 rpm; Zone II: temperature 100~130 ℃, screw speed 150~350 rpm, vacuum dehydration system is turned on, vacuum degree is -0.06~ -0.09MPa; Zone III: temperature 90~120 ℃. (4) Post-processing: Drying, baking, crushing or sieving according to product requirements to obtain the final whole grain food.

2. The whole grain food processing method according to claim 1, characterized in that, In step (2), the selection principle for enzyme preparations is as follows: ①Amylase: Regulates the crispness and solubility of food; specifically: for high-crisp products, select medium-temperature α-amylase to break down long-chain starch into medium-dextrin and promote puffing; for high-elasticity products, select amyloglucosidase to produce a small amount of natural sweetness and retain long-chain starch to maintain its structure; for instant products, select pullulanase to hydrolyze the branching points of amylopectin and improve cold water solubility. ② Proteases: Regulate the elasticity and chewiness of food; specifically: for products with high crispness, choose neutral proteases to produce medium peptides and improve emulsification; for products with high elasticity, choose flavor proteases for gentle hydrolysis, preserving the core protein structure to form a gel network; for instant products, add a small amount or none to avoid viscosity reduction. ③ Hemicellulase: Regulates the smoothness of food; specifically: for high-brittle products, choose xylanase to break down fiber rigidity; for high-elasticity products, choose β-glucanase to reduce material viscosity; for instant products, choose cellulase to open up the fiber structure and prevent clumping.

3. The whole grain food processing method according to claim 2, characterized in that, In step (2), the amount of all enzyme preparations added is calculated based on the dry weight of the corresponding component; specifically, the amount of amylase added is 0.02% to 0.2% of the dry weight of total starch in the raw material; the amount of protease added is 0.05% to 0.3% of the dry weight of total protein in the raw material; and the amount of hemicellulase added is 0.01% to 0.1% of the total dry weight of whole grain raw material.

4. The whole grain food processing method according to claim 3, characterized in that, In step (2), after the enzymatic hydrolysis reaction is completed, the temperature is rapidly raised to 85 °C and maintained for 2 minutes to completely inactivate the enzyme and obtain the enzymatically modified material.

5. The whole grain food processing method according to claim 4, characterized in that, In step (3), shear strength and moisture content are precisely selected based on the textural properties of the target product: ① High-brittleness puffed food: 3-5 sets of staggered 45° mid-shear kneading blocks are set in barrel I, and 1-2 sets of kneading blocks at the same angle are set in barrel II; the screw speed in barrel I is 250-400 rpm, and the screw speed in barrel II is 200-350 rpm; ② High-elasticity nutritional food: Zone I of the barrel is equipped with 0~1 sets of weak shear kneading blocks with a staggered angle ≤30°, and Zone II of the barrel is entirely equipped with conveying elements; the screw speed in Zone I of the barrel is 100~200 rpm, and the screw speed in Zone II of the barrel is 50~150 rpm; ③ Cold water instant cereal powder: 1~2 sets of kneading blocks with staggered angles of 30°~45° are set in barrel I, and 0~1 sets of kneading blocks with the same angle are set in barrel II; the screw speed in barrel I is 200~300 rpm, and the screw speed in barrel II is 150~250 rpm.

6. The whole grain food processing method according to claim 5, characterized in that, The length-to-diameter ratio of the twin-screw extruder is (40~60):

1.

7. The whole grain food processing method according to claim 6, characterized in that, In step (3), the total residence time of the material in the twin-screw extruder is 15 to 30 seconds, while the residence time in barrel II zone is only 5 to 10 seconds.

8. The whole grain food processing method according to claim 7, characterized in that, In step (1), the relative humidity of the hot air is adjusted to 40%~70% and the wind speed is 0.5~2 m / s by a closed-loop humidity control system so that the moisture content of the material is maintained at 14%~22% after micro-hot air treatment.

9. The whole grain food processing method according to claim 8, characterized in that, In step (1), the particle size of the whole grain raw material is 100~500 μm.

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