Red glutinous rice tea drink condiment and preparation method thereof

Abstract

The present invention discloses a red glutinous rice tea drink condiment and a preparation method thereof, and relates to the technical field of food processing, the condiment is of a three-layer structure from inside to outside: a core layer is red glutinous rice particles subjected to 15%-35% pre-gelatinization treatment, and is coated with a pea protein isolate or chickpea protein isolate film accounting for 1.5%-4% of the dry weight of the red glutinous rice particles; the middle layer is crystal syrup of which the solid content is 75-85 degrees Brix, and the crystal syrup contains 0.05-0.3% of osmanthus fragrans extract, honeysuckle extract or ammonium glycyrrhizinate; the outer layer is hydrophobic powder of modified cassava resistant starch and microcrystalline cellulose (the mass ratio is 2: 1-4: 1), and the coating amount accounts for 5%-12% of the total mass of the core layer and the middle layer. The three-layer structure is synergistic: the core layer is coated by 15%-35% pre-gelatinization and vegetable protein film, so that the soft and glutinous taste is kept, and water is locked; 75-degree Brix-85-degree Brix crystal syrup in the middle layer is matched with the herbal extract, so that the fresh and sweet flavor is given; hydrophobic powder on the outer layer is anti-sticking and moisture-proof, and the texture change rate is 1t after normal-temperature sealing for 72 hours; the resistant starch is contained, functionality is improved, the tea drink is suitable for multiple tea drinks, the process is controllable, uniformity is kept, and the cost is reduced through normal-temperature storage.

Description

Technical Field

[0001] This invention relates to the field of food processing technology, specifically to a black glutinous rice tea topping and its preparation method. Background Technology

[0002] With the upgrading of consumption in the tea beverage industry, consumers' demand for tea beverage toppings has shifted from a single "taste supplement" to a multi-dimensional synergy of "nutrition, taste, flavor, and stability." Among them, black glutinous rice, rich in anthocyanins, dietary fiber, and minerals, possesses both natural nutritional properties and a soft, chewy texture, making it an important alternative to traditional toppings such as tapioca pearls and coconut jelly, with its market penetration rate increasing year by year. However, existing black glutinous rice tea beverage toppings still have many shortcomings in technical design and industrial application that urgently need to be addressed. These shortcomings directly restrict the stability of product quality and market expansion potential, specifically in the following aspects:

[0003] Firstly, the pretreatment and structural protection design of black glutinous rice grains are insufficient. In traditional processes, black glutinous rice is often cooked under normal pressure or used directly after soaking, which makes it impossible to precisely control the degree of pregelatinization. If the cooking time is too long (e.g., more than 20 minutes), the degree of pregelatinization can easily exceed 40%, resulting in excessive softness and loss of chewiness after brewing, and even a "mushy soup" phenomenon. If the cooking time is insufficient (e.g., less than 5 minutes), the degree of pregelatinization is less than 10%, resulting in a noticeable hard core inside the grains and a hard texture. At the same time, existing products do not have an effective barrier structure on the outer layer of black glutinous rice grains, so the moisture inside the grains is easily lost slowly during storage, resulting in a dry and hard texture. It is also easier for it to interpenetrate with the outer flavoring ingredients (such as syrup). For example, the sugar in the syrup seeps into the glutinous rice, increasing the sweetness of the glutinous rice itself and masking its original grain aroma, while the moisture in the glutinous rice dilutes the syrup, causing the syrup layer to become less viscous and more fluid, further aggravating the adhesion problem during subsequent storage.

[0004] Secondly, the formulation and preparation process of the flavoring syrup layer lack scientific rigor. Currently, most glutinous rice toppings use ordinary syrup (with a solid content of 65°Brix-70°Brix). The glass transition temperature of syrup in this solid content range is relatively low (usually below 25°C). When stored at room temperature (especially in summer or in the high-humidity environment of the south), it is easy to change from a glassy state to a highly elastic state, causing the toppings to stick together and clump together. In severe cases, it can even form large agglomerates that need to be manually broken up before use. This not only affects the consumer experience but also increases the sorting costs in industrial production. In addition, there are obvious defects in the way natural herbal extracts (such as osmanthus and honeysuckle) are added: some processes add them directly during the high-temperature stage of syrup boiling (such as above 110°C), which causes the volatile flavor substances in the extracts (such as linalool in osmanthus and chlorogenic acid in honeysuckle) to volatilize or degrade due to high temperature, losing their original flavor and activity; other processes add them at room temperature, which causes the extracts to not dissolve fully in the syrup, resulting in flavor stratification (strong flavor on the surface and tasteless inside), and significant flavor differences between batches, making it difficult to ensure product uniformity.

[0005] Thirdly, the outer protective design and functional compatibility are severely lacking. The outer layer of existing products mostly uses ordinary corn starch, sucrose powder, or skim milk powder. These materials have weak hydrophobicity and are prone to rapid moisture absorption in environments with relative humidity exceeding 60%, causing the surface of small materials to become sticky and clump together. The shelf life is usually only 3-5 days, and cold chain transportation and storage (temperature 0℃-4℃) are necessary, which significantly increases logistics and warehousing costs and restricts the promotion of products in lower-tier markets and normal temperature channels. Meanwhile, the existing outer layer lacks functional ingredient design, failing to meet consumers' demand for healthy toppings. For example, consumers are currently paying attention to dietary fiber intake and blood sugar control, but the existing outer layer does not introduce functional ingredients such as resistant starch, making it difficult to adapt to low-sugar and sugar-controlled tea beverage products. Furthermore, the coating uniformity in the preparation process is poor. For instance, the atomization pressure is not optimized during spray coating (often below 0.1MPa or above 0.5MPa), resulting in uneven syrup spraying (local over-thickness or missed spraying). Or, the rotation speed is too high during roller coating (above 30rpm), causing powder to fall off. The final product particle size deviation exceeds ±0.8mm, which easily leads to problems such as settling and clumping or floating and not dissolving during brewing, seriously affecting the drinking experience.

[0006] Fourth, existing technologies lack a systematic solution, with defects at each stage compounding each other. For example, improper pretreatment of glutinous rice particles leads to textural instability, further exacerbating the adhesion of the syrup layer; insufficient hydrophobicity of the outer layer accelerates water penetration, worsening the interpenetration problem between the particles and the syrup layer; and the lack of optimization of process parameters (such as spray pressure, drum speed, and drying temperature) results in low product uniformity and a pass rate of less than 80%, significantly increasing production costs. These problems collectively cause existing glutinous rice tea toppings to fail to meet market demands in terms of taste, flavor stability, functionality, and industrial adaptability, becoming a key bottleneck restricting its further development. Therefore, a technical solution for glutinous rice tea toppings that can address the aforementioned technical deficiencies is urgently needed. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a black glutinous rice tea topping and its preparation method. This invention features a three-layer structure for synergistic effect: the core layer is pregelatinized at 15%-35% and coated with a plant protein membrane to maintain a soft and glutinous texture and lock in moisture; the middle layer contains 75°Brix-85°Brix crystalline syrup with herbal extracts to impart a sweet flavor; the outer layer is a hydrophobic powder for non-sticking and moisture protection, with a textural change rate of <5% after 72 hours of sealing at room temperature. It contains resistant starch for added functionality, is suitable for various tea drinks, has a controllable process to ensure uniformity, reduces costs with room temperature storage, and significantly improves the drinking experience and application value.

[0008] To solve the above-mentioned technical problems, this invention provides the following technical solution: a black glutinous rice tea topping and its preparation method. This topping utilizes a synergistic design of a three-layer composite structure—core layer, middle layer, and outer layer—with each layer complementing and supporting the others to form a complete technical solution, as detailed below:

[0009] The core layer, serving as the matrix for the toppings, bears the basic functions of providing texture and moisture barrier. Specifically, it involves the synergistic effect of pregelatinization control and plant protein membrane coating. The specific process is as follows:

[0010] Raw material selection: Select whole and undamaged glutinous rice grains with a particle size distribution controlled within the range of 1.5mm-3.5mm, of which particles with a size of 2.0mm±0.3mm account for no less than 70%. This particle size range can ensure the chewy texture and avoid the problems of too small particles easily disintegrating and too large particles being difficult to coat, thus laying the foundation for subsequent multi-layer coating.

[0011] Pregelatinization treatment: Soak the black glutinous rice in 2-3 times its weight of soft water at 25℃-35℃ for 2-4 hours. Soft water can avoid the calcium and magnesium ions in hard water from affecting the subsequent adhesion of the protein film. After soaking, drain the black glutinous rice and pass saturated steam with a dryness of not less than 0.95 through it. Treat it under a pressure of 0.15MPa-0.25MPa for 8-15 minutes. This pressure and time parameter can accurately control the degree of gelatinization of the black glutinous rice starch between 15% and 35%. Too low a degree of gelatinization will result in hard particles and poor taste. Too high a degree of gelatinization will cause the starch to easily absorb water and swell, leading to collapse. After pregelatinization treatment, immediately transfer the black glutinous rice to an ice-water mixture at 0℃-4℃ and cool it for 30-90 seconds. The rapid temperature drop will cause the starch molecules to solidify quickly and form a stable crystal structure, reducing water absorption during the subsequent soaking process.

[0012] Plant protein membrane coating: Preheat the quenched glutinous rice granules to 45℃-60℃. This temperature range improves the fluidity of the protein solution and ensures uniform coating. Place the preheated granules in a rotating coating pan with a heating jacket. Spray a 3%-8% aqueous solution of plant protein isolate while the pan is rotating. Pea protein isolate or chickpea protein isolate is selected, as both have good film-forming and barrier properties, and no beany odor, so they will not affect the flavor of the tea. While spraying the protein solution, a cross-linking agent is simultaneously added. The amount of cross-linking agent added is 0.5%-1.5% of the dry weight of the plant protein isolate. Tannic acid or transglutaminase is selected. If tannic acid is used, it needs to be dissolved in water beforehand. In the case of edible ethanol, the volume of edible ethanol shall not exceed 2% of the volume of the aqueous solution of plant protein isolate. Ethanol can improve the solubility of tannic acid and can evaporate quickly without leaving any odor. If it is transglutaminase, it can be sprayed in powder form at the same time. The cross-linking agent can make the protein membrane form a dense network structure and improve the barrier performance. Finally, the coating amount of plant protein membrane is controlled to be 1.5%-4% of the dry weight of the glutinous rice grains. If the coating amount is too low, the barrier performance will be insufficient, and if it is too high, the grains will be too hard. After coating, dry under hot air conditions of 50℃-65℃ until the moisture content of the glutinous rice grains does not exceed 18%. If the moisture content is too high, the grains will easily absorb moisture, and if it is too low, the grains will become brittle and affect the taste.

[0013] The middle layer wraps around the outside of the core layer, achieving the effect of flavor carrier + adhesion between the core layer and the outer layer. The specific process is as follows:

[0014] Syrup ingredient ratio: Weigh out 40-60 parts by weight of white sugar, 10-25 parts by weight of trehalose, 5-15 parts by weight of maltitol solution, and 20-30 parts by weight of water. White sugar provides the basic sweetness and crystallinity of the syrup. Trehalose can raise the glass transition temperature of the syrup and prevent crystallization during storage. Maltitol solution can lower the freezing point of the syrup and prevent hardening during low-temperature storage. The synergistic ratio of the three ingredients can ensure that the syrup forms a stable crystalline structure in subsequent processes.

[0015] Syrup preparation and flavor addition: Mix the above raw materials and heat to 105℃±2℃ to boil and concentrate until the syrup solids content reaches 75°Brix-85°Brix. If the solids content is too low, the syrup will easily absorb moisture, and if it is too high, it will be too hard after crystallization and have a bitter taste. After concentration, cool the syrup to 80℃±5℃. At this time, add 0.05%-0.3% of natural herbal extract, such as osmanthus extract, honeysuckle extract or ammonium glycyrrhizate. 80℃±5℃ is the optimal temperature for adding herbal extracts: if the temperature is too high, the flavor substances will volatilize, and if the temperature is too low, the extracts will not dissolve evenly. After adding the extracts, stir evenly and keep warm at 70℃±5℃ for later use. This temperature can maintain the fluidity of the syrup and facilitate subsequent spraying operations.

[0016] Fluidized bed coating crystallization: The core material is placed in a fluidized bed, and the fluidizing gas temperature is set to 65℃-75℃. This temperature ensures that the core particles remain fluidized during syrup spraying, preventing particle agglomeration. The heated syrup is then atomized and sprayed through a nozzle, with the atomization pressure controlled at 0.2MPa-0.4MPa and the atomizing disc rotation speed at 8000rpm-15000rpm. These parameters allow the syrup to form 10-20μm droplets, uniformly covering the core surface without significant dripping. After spraying, the fluidization process is maintained while the inlet gas temperature is slowly reduced to 35℃-45℃. This temperature range is the optimal crystallization temperature for the syrup, promoting the formation of fine and uniform crystals. This not only locks the flavor compounds firmly within the crystal network but also provides a good adhesive foundation for the subsequent adhesion of the outer powder layer. Once the syrup has completely crystallized and solidified, the intermediate layer is formed.

[0017] The outer layer wraps around the middle layer, which improves moisture resistance and optimizes compatibility with tea beverage systems. The specific process is as follows:

[0018] Preparation of hydrophobic powder: Modified cassava resistant starch and microcrystalline cellulose are mixed in a mass ratio of 2:1 to 4:1. Modified cassava resistant starch is prepared by esterification with octenyl succinic anhydride: Ordinary cassava starch is prepared into a 30%-40% suspension, and the pH of the suspension is adjusted to 9.5-10.5. Alkaline conditions can promote the esterification reaction between octenyl succinic anhydride and starch. 1%-3% of octenyl succinic anhydride by dry weight of starch is added, and the reaction is carried out at 35℃-45℃ for 4-6 hours. Too low a reaction temperature will lead to incomplete reaction. High pH levels can easily cause starch gelatinization. After the reaction, the pH of the suspension is adjusted to 6.0-7.0. After washing, drying, and pulverizing, the solution is passed through a 200-mesh sieve. The 200-mesh sieve ensures that the modified starch has a uniform particle size, which is convenient for subsequent coating. Microcrystalline cellulose with an average particle size of 50μm-80μm is selected. This particle size can form tiny pores in the powder layer, which does not affect the taste of the particles and can further improve the hydrophobicity. After the two are mixed, the modified cassava resistant starch mainly provides hydrophobicity, while the microcrystalline cellulose improves the structural stability of the powder layer and prevents the powder from falling off.

[0019] Roller coating: Transfer the material with the intermediate layer to the roller coating machine. Under room temperature conditions, set the roller speed to 10rpm-20rpm. Too low a speed will result in uneven powder adhesion, while too high a speed will easily cause the material to break. Spread the hydrophobic powder on the surface of the material in 2-4 times. After each application of powder, continue rolling for 2-5 minutes. The interval between two consecutive applications of powder should be 2-5 minutes. Spreading the powder in multiple applications can avoid particle agglomeration caused by applying powder all at once and ensure that the powder adheres evenly. Finally, control the coating amount of the outer layer to be 5%-12% of the total mass of the core layer and the intermediate layer. Too low a coating amount will result in insufficient moisture resistance, while too high a coating amount will result in a rough texture of the particles.

[0020] The preparation process of the above three-layer structure is as follows: core layer preparation, intermediate layer construction, and outer layer coating. Each step is seamlessly connected through precise control of material temperature and moisture content: after drying, the moisture content of the core layer is controlled below 18% to ensure uniform adhesion of the intermediate syrup; after crystallization of the intermediate layer, the material temperature is reduced to 35℃-45℃ to prevent the outer powder from clumping due to high temperatures; the outer coating is carried out at room temperature to ensure the stability of the powder layer. The complete process is as follows:

[0021] Core layer preparation: material selection and soaking → pregelatinization treatment → rapid cooling → plant protein membrane coating and drying;

[0022] Intermediate layer construction: Syrup preparation → Fluidized bed coating and crystallization;

[0023] Outer coating: hydrophobic powder preparation → roller coating.

[0024] Compared with existing technologies, this black glutinous rice tea topping and its preparation method have the following beneficial effects:

[0025] I. This invention, through 15%-35% pregelatinization treatment and plant protein membrane coating, retains the core texture of soft and chewy texture while locking in internal moisture; the middle layer of crystallized syrup (75°Brix-85°Brix) combines with natural herbal extracts to form a sweet and refreshing flavor layer, which is not easily flowable after crystallization and solidification; the outer layer of hydrophobic powder (a combination of modified cassava resistant starch and microcrystalline cellulose) can effectively block external moisture, prevent the small pieces from absorbing moisture and sticking together, and prevent the syrup from dissolving and losing too quickly during brewing. The three elements work together to ensure that the texture change rate of the small pieces is less than 5% within 72 hours when stored at room temperature in a sealed container. Whether added to hot or cold drinks, the particles can maintain their integrity, achieving the effect of being soft and chewy without becoming mushy, retaining the flavor, and not sticking together.

[0026] Second, the outer layer of this invention uses modified cassava resistant starch as a functional component, combined with the dispersing effect of microcrystalline cellulose, so that the ingredients not only meet the needs of healthy eating, but also disperse quickly during brewing, without clumping or settling, making it suitable for various tea beverage forms such as milk tea, fruit tea, and pure tea; the plant protein membrane has both barrier properties and edibility, which can prevent the core layer and middle layer components from penetrating each other, and enhance the nutritional value of the ingredients; the precise ratio of natural herbal extracts achieves a unique flavor while avoiding masking the aroma of the tea beverage itself, satisfying the flavor preferences of different consumer groups.

[0027] Third, in the preparation process of this invention, the pressure and temperature control of pregelatinization, the control of rapid cooling time, the adjustment of atomization parameters for fluidized bed coating (pressure of 0.2MPa-0.4MPa, atomization disk speed of 8000rpm-15000rpm), and the operation of 2-4 times powdering in roller coating ensure the uniformity of coating of the core layer, middle layer, and outer layer, and the high consistency of product particle size and texture. The protective effect of the outer hydrophobic powder and the storage conditions of room temperature sealing and light protection eliminate the need for cold chain transportation of small materials, reducing storage and logistics costs. At the same time, natural herbal extracts are added when the syrup is cooled to 80℃±5℃ to avoid high temperature damage to active ingredients. The plant protein film is solidified with the assistance of cross-linking agents, which further improves the structural stability and ensures the quality control of the product throughout the entire chain of production, storage, and consumption.

[0028] Other advantages, objectives and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination or study, or may be learned from the practice of the invention. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0030] Figure 1 A flowchart illustrating the overall preparation process of black glutinous rice tea toppings and their preparation methods;

[0031] Figure 2 A flowchart illustrating the preparation process of the core layer for a black glutinous rice tea topping and its preparation method;

[0032] Figure 3 A flowchart of the intermediate layer construction for the black glutinous rice tea topping and its preparation method;

[0033] Figure 4 Flowchart of outer coating and stability verification of black glutinous rice tea topping and its preparation method. Detailed Implementation

[0034] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0035] Example 1: Osmanthus-flavored black glutinous rice tea topping

[0036] Core layer preparation:

[0037] Selection and soaking: Select 10kg of whole, undamaged glutinous rice, with 75% of the grains having a diameter of 2.0mm±0.3mm. Soak in 25kg of soft water at 30℃ for 3 hours, stirring once every hour during the soaking period to ensure even soaking.

[0038] Pregelatinization treatment: After soaking, the glutinous rice is drained, and the moisture content of the grains is about 45%. It is placed in a horizontal steaming tank, and saturated steam with a dryness of 0.96 is introduced. The pressure is set to 0.2MPa and the treatment is carried out for 12 minutes.

[0039] Rapid cooling: Quickly transfer the pregelatinized hot glutinous rice to a mixing tank containing 50 kg of ice water at 2°C, start stirring at 50 rpm for 60 seconds, then remove and drain with a sieve until no water droplets drip from the surface. At this point, the moisture content of the grains is about 42%.

[0040] Plant protein membrane coating: The quenched glutinous rice granules were preheated to 50°C and transferred to a rotating coating pan with a heating jacket at 30 rpm. 4 kg of a 5% pea protein isolate aqueous solution was prepared, containing 0.2 kg of pea protein isolate. Simultaneously, 0.002 kg of tannic acid was dissolved in 0.04 kg of edible ethanol, with the volume of edible ethanol being 1% of the volume of the pea protein isolate aqueous solution. The hot air in the coating pan was turned on, and the hot air temperature was set to 55°C. While the granules were rotating, the pea protein isolate aqueous solution was sprayed while the tannic acid ethanol solution was added, continuing this process for 30 minutes. After the pea protein isolate aqueous solution was completely sprayed, the granules continued to rotate and the hot air supply was maintained until the moisture content of the glutinous rice granules reached 15%, yielding approximately 10.8 kg of core material.

[0041] Middleware layer construction:

[0042] Syrup preparation: Weigh out 5 kg of granulated sugar, 1.8 kg of trehalose, 1 kg of maltitol solution, and 2.5 kg of water by weight, mix them, and pour them into a sugar-boiling pot. Heat to 105°C, start stirring, and concentrate at 80 rpm for 30 minutes. Measure the syrup solids content with a handheld refractometer; when it reaches 80°Brix, stop heating. Cool the syrup to 75°C, add 0.015 kg of osmanthus extract, stir for 5 minutes until homogeneous, and maintain the temperature at 70°C for later use.

[0043] Fluidized bed coating crystallization: 10.8 kg of core material was transferred into a top-spray fluidized bed (model LBF-5), with the inlet air temperature set at 70℃ and the fluidizing air volume at 1200 m³ / h. The insulated syrup was then pumped into the atomizing nozzle using a peristaltic pump, with the atomization pressure set at 0.3 MPa, the atomizing disc rotation speed at 12000 rpm, and the spraying rate at 0.2 kg / min, for a total of 10.315 kg of syrup sprayed. After spraying, the inlet air temperature was gradually reduced, allowing the material temperature to slowly drop to 40℃. The fluidized state was maintained for 30 minutes until the syrup was completely crystallized and solidified, yielding approximately 21.1 kg of material with an intermediate layer.

[0044] Outer coating:

[0045] Preparation of hydrophobic powder: Weigh 1.6 kg of modified cassava resistant starch and 0.53 kg of microcrystalline cellulose in a mass ratio of 3:1, pour them into a three-dimensional mixer, mix at 150 rpm for 10 minutes to obtain 2.13 kg of hydrophobic coating powder.

[0046] Powder Coating: 21.1 kg of material with the intermediate layer was transferred into a roller coating machine (model BY-100). The roller speed was set to 15 rpm, and the operation was carried out at room temperature (25℃). Hydrophobic coating powder was applied in three applications, 0.71 kg each time. After each application, the roller was continuously rolled for 3 minutes, with a 3-minute interval between each application. After all applications were completed, the roller was rolled for another 10 minutes to ensure even powder adhesion, yielding approximately 23.2 kg of Osmanthus-flavored glutinous rice topping.

[0047] Finished product testing: The finished product has 98% particle integrity and no powder shedding on the surface; after 72 hours of sealed storage at room temperature, the change rate of texture hardness is 3.2%; after soaking in milk tea for 6 hours, the particle integrity is 92% and the milk tea is clear; after 30 days of sealed storage at room temperature, the osmanthus flavor retention rate is 85%.

[0048] Example 2: Honeysuckle-flavored glutinous rice tea topping

[0049] Core layer preparation:

[0050] Selection and soaking: Select 10kg of whole, undamaged glutinous rice, of which 72% have a particle size of 2.0mm±0.3mm. Soak in 20kg of soft water at 25℃ for 4 hours.

[0051] Pregelatinization treatment: After soaking, drain the glutinous rice, which has a moisture content of about 46%, and place it in a horizontal steaming tank. Pass saturated steam with a dryness of 0.95 through it, set the pressure to 0.15 MPa, and process for 15 minutes.

[0052] Rapid cooling: Transfer the pregelatinized hot glutinous rice to a mixing tank containing 50 kg of 0°C ice water mixture, stir at 50 rpm for 90 seconds, remove and drain until no water droplets drip from the surface. At this point, the moisture content of the grains is about 43%.

[0053] Plant protein membrane coating: The quenched glutinous rice granules were preheated to 45°C and transferred to a rotating coating pan with a heating jacket, rotating at 30 rpm. 3.3 kg of a 3% chickpea protein isolate aqueous solution was prepared, containing 0.099 kg of chickpea protein isolate. 0.000495 kg of transglutaminase powder was added, with the transglutaminase addition amount being 0.5% of the dry weight of the chickpea protein isolate. The hot air of the coating pan was turned on, and the temperature was set to 50°C. The chickpea protein isolate aqueous solution was sprayed while the granules were rotating, and the transglutaminase powder was sprayed simultaneously. This process was continued for 25 minutes. After spraying, drying continued until the moisture content of the granules reached 16%, yielding approximately 10.6 kg of core material.

[0054] Middleware layer construction:

[0055] Syrup preparation: Weigh out 4 kg of white sugar, 2.5 kg of trehalose, 0.5 kg of maltitol solution, and 2 kg of water by weight, and mix them in a sugar-boiling pot. Heat to 103℃, stir and concentrate for 25 minutes at a speed of 80 rpm, and measure the solid content with a handheld saccharimeter to 75°Brix. Stop heating. Cool to 75℃, add 0.005 kg of honeysuckle extract, stir for 5 minutes until homogeneous, and maintain the temperature at 70℃ for later use.

[0056] Fluidized bed coating crystallization: 10.6 kg of core material was transferred into a top-spray fluidized bed, with the inlet air temperature set at 65℃ and the fluidizing air volume at 1100 m³ / h. The insulated syrup was then pumped into the atomizing nozzle using a peristaltic pump, with the atomizing pressure set at 0.2 MPa, the atomizing disc rotation speed at 8000 rpm, and the spraying rate at 0.18 kg / min, for a total of 9.005 kg of syrup sprayed. After spraying, the inlet air temperature was reduced to 35℃, and fluidization was maintained for 30 minutes until the syrup crystallized and solidified, yielding approximately 19.6 kg of material with an intermediate layer.

[0057] Outer coating:

[0058] Preparation of hydrophobic powder: Weigh 1.2 kg of modified cassava resistant starch and 0.6 kg of microcrystalline cellulose in a mass ratio of 2:1, pour them into a three-dimensional mixer, mix at 150 rpm for 10 minutes to obtain 1.8 kg of hydrophobic coating powder.

[0059] Powder coating: 19.6 kg of material with the intermediate layer was transferred into a roller coating machine. The speed was set to 10 rpm, and the hydrophobic coating powder was applied in two batches at room temperature (25℃), with 0.9 kg of powder applied each time. After each application, the roller was rolled for 2 minutes, with a 2-minute interval between each application. After the powder application was completed, the roller was rolled for another 8 minutes to obtain approximately 21.4 kg of honeysuckle-flavored glutinous rice topping.

[0060] Finished product testing: 97% of the finished product particles are intact, and there is no powder shedding on the surface; after 72 hours of sealed storage at room temperature, the change rate of texture hardness is 4.5%; after soaking in milk tea for 6 hours, the particle integrity is 90%, and there is no turbidity in the milk tea; after 30 days of sealed storage at room temperature, the honeysuckle flavor retention rate is 80%.

[0061] Example 3: Licorice-flavored glutinous rice tea topping

[0062] Core layer preparation:

[0063] Selection and soaking: Select 10kg of whole, undamaged glutinous rice, of which 80% have a particle size of 2.0mm±0.3mm. Soak in 30kg of soft water at 35℃ for 2 hours.

[0064] Pregelatinization treatment: After soaking, the glutinous rice is drained and the moisture content is about 44%. It is placed in a horizontal steaming tank, and saturated steam with a dryness of 0.98 is introduced. The pressure is set to 0.25MPa and the treatment is carried out for 8 minutes.

[0065] Rapid cooling: Transfer the pregelatinized hot glutinous rice to a mixing tank containing 50 kg of ice water at 4°C. Stir at 50 rpm for 30 seconds, then remove and drain until no water droplets drip from the surface. At this point, the moisture content of the grains is about 40%.

[0066] Plant protein membrane coating: Preheat the quenched glutinous rice granules to 60°C and transfer them to a rotating coating pan with a heating jacket at 30 rpm. Prepare 3 kg of an 8% pea-chickenbean mixed protein aqueous solution (pea protein isolate to chickpea protein isolate mass ratio 1:1, totaling 0.24 kg of protein). Dissolve 0.0036 kg of tannic acid in 0.06 kg of edible ethanol (volume of edible ethanol is 2% of the volume of the mixed protein aqueous solution). Turn on the hot air of the coating pan, set the temperature to 65°C, and spray the mixed protein aqueous solution while the granules are rotating, simultaneously spraying in the tannic acid-ethanol solution. Continue this process for 35 minutes. After spraying, continue drying until the granule moisture content reaches 14%, yielding approximately 10.7 kg of core material.

[0067] Middleware layer construction:

[0068] Syrup preparation: Weigh out 6 kg of white sugar, 1 kg of trehalose, 1.5 kg of maltitol solution, and 3 kg of water by weight, and mix them in a sugar-boiling pot. Heat to 107°C, stir and concentrate for 35 minutes at a speed of 80 rpm, and measure the solid content with a handheld saccharimeter. If it reaches 85°Brix, stop heating. Cool to 85°C, add 0.03 kg of ammonium glycyrrhizate, stir for 5 minutes until homogeneous, and maintain the temperature at 75°C for later use.

[0069] Fluidized bed coating crystallization: 10.7 kg of core material was transferred into a top-spray fluidized bed, with the inlet air temperature set at 75℃ and the fluidizing air volume at 1300 m³ / h. The insulated syrup was then pumped into the atomizing nozzle using a peristaltic pump, with the atomization pressure set at 0.4 MPa, the atomizing disc rotation speed at 15000 rpm, and the spraying rate at 0.22 kg / min, for a total of 11.53 kg of syrup sprayed. After spraying, the inlet air temperature was reduced to 45℃, and fluidization was maintained for 30 minutes until the syrup crystallized and solidified, yielding approximately 22.2 kg of material with an intermediate layer.

[0070] Outer coating:

[0071] Preparation of hydrophobic powder: Weigh 2.16 kg of modified cassava resistant starch and 0.54 kg of microcrystalline cellulose in a mass ratio of 4:1, pour them into a three-dimensional mixer, and mix at 150 rpm for 10 minutes to obtain 2.7 kg of hydrophobic coating powder.

[0072] Powder coating: 22.2 kg of material with the intermediate layer was transferred into a roller coating machine. The speed was set to 20 rpm, and the hydrophobic coating powder was applied in 4 batches at room temperature (25℃), with 0.675 kg of powder applied each time. After each application, the roller was rolled for 5 minutes, with a 5-minute interval between each application. After the powder application was completed, the roller was rolled for another 12 minutes to obtain approximately 24.9 kg of licorice-flavored glutinous rice topping.

[0073] Finished product testing: The finished product has 99% particle integrity and no powder shedding on the surface; after 72 hours of sealed storage at room temperature, the change rate of texture hardness is 2.8%; after soaking in milk tea for 6 hours, the particle integrity is 93% and the milk tea is clear; after 30 days of sealed storage at room temperature, the licorice flavor retention rate is 88%.

[0074] Example effect verification:

[0075] The finished products from the three embodiments described above were tested for four core indicators: textural stability, flavor retention, moisture resistance, and system compatibility. The testing methods and results are shown in the table below.

[0076] detection indicators Detection methods Example 1 Example 2 Example 3 Texture stability (72h) The hardness change rate was determined using a texture analyzer (model TA-XT2i) under the following conditions: P / 50 probe and a test speed of 1 mm / s. 3.2% 4.5% 2.8% Flavor retention (30 days) A blind tasting was conducted by a panel of 10 professional judges, who scored the flavors on a 10-point scale (10 points being the initial flavor score). 8.5 points 8.0 points 8.8 points Moisture resistance After being placed at 25℃ and 65% relative humidity for 7 days, the adhesion rate (the percentage of adhered particles to the total particles) was calculated. 2.1% 3.5% 1.8% System adaptability Add the toppings to the low-sugar milk tea (5° Brix), let it sit at 25°C for 2 hours, and observe the separation. No layering No layering No layering

[0077] The above test results show that the finished products of the three embodiments can all achieve the design goals of the present invention, and all indicators are significantly better than those of the prior art products. Under the same test conditions, the texture change rate of the prior art products generally exceeds 15% after 72 hours, the flavor blind score is about 5.0 points after 30 days, the adhesion rate exceeds 15% after 7 days, and obvious stratification occurs within 2 hours when placed in low-sugar milk tea.

[0078] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A topping for black glutinous rice tea, characterized in that, This small component, from the inside out, includes: The core layer consists of pregelatinized glutinous rice grains coated with a plant protein membrane; The middle layer, which wraps around the outside of the core layer, is a crystalline syrup layer containing natural herbal extracts; The outer layer, which wraps around the middle layer, is a hydrophobic powder layer rich in resistant starch; The core layer contains glutinous rice grains with a pregelatinization degree of 15%-35%, and the plant protein membrane is selected from at least one of pea protein isolate or chickpea protein isolate, with the coating amount of the plant protein membrane being 1.5%-4% of the dry weight of the glutinous rice grains. The intermediate layer contains crystalline syrup with a solid content of 75°Brix to 85°Brix, and the natural herbal extract is selected from at least one of osmanthus extract, honeysuckle extract, or ammonium glycyrrhizate, with a mass percentage of 0.05%-0.3% in the intermediate layer. The outer layer contains hydrophobic powder composed of a mixture of modified cassava resistant starch and microcrystalline cellulose, with a mass ratio of (2:1) to (4:1), and the coating amount of the outer layer is 5%-12% of the total mass of the core layer and the intermediate layer.

2. The black glutinous rice tea topping according to claim 1, characterized in that, The particle size of the glutinous rice grains in the core layer is between 1.5 mm and 3.5 mm, of which the proportion of particles with a particle size in the range of 2.0 mm ± 0.3 mm is not less than 70%. The pregelatinization process includes: steaming soaked glutinous rice at a pressure of 0.15MPa-0.25MPa for 8-15 minutes, followed by immediate quenching in an ice-water mixture for 30-90 seconds; the plant protein membrane is formed by tumbling and stirring glutinous rice particles with a 3%-8% aqueous solution of plant protein isolate at 45°C-60°C, while simultaneously spraying in a crosslinking agent accounting for 0.5%-1.5% of the dry weight of the plant protein isolate, wherein the crosslinking agent is tannic acid or transglutaminase, and then drying under hot air conditions at 50°C-65°C until the moisture content is ≤18%.

3. The blood glutinous rice tea topping according to claim 2, characterized in that, The steam used in the steam treatment is saturated steam with a dryness of not less than 0.95; the temperature of the ice-water mixture is maintained between 0°C and 4°C; when the crosslinking agent is tannic acid, it is added by dissolving it in a small amount of edible ethanol and then spraying it in, and the volume of the edible ethanol does not exceed 2% of the volume of the plant protein isolate aqueous solution.

4. The black glutinous rice tea topping according to claim 1, characterized in that, The intermediate layer of crystallized syrup is made from the following raw materials in parts by weight: 40-60 parts white sugar, 10-25 parts trehalose, 5-15 parts maltitol solution, 20-30 parts water, and the natural herbal extract. The preparation process of the crystallized syrup includes: mixing white sugar, trehalose, maltitol solution and water, heating to 105℃±2℃ to dissolve and concentrate to the target solid content, cooling to 80℃±5℃ and adding the natural herbal extract, stirring evenly and maintaining the temperature at 70℃±5℃ for coating operation.

5. The blood glutinous rice tea topping according to claim 4, characterized in that, The coating of the intermediate layer is achieved by placing the material with the core layer in a fluidized bed and spraying the crystallized syrup onto the surface of the material in an atomized form under the condition that the fluidized gas temperature is 65°C to 75°C. The spraying rate is controlled so that the surface of the material is uniformly wetted but there is no obvious dripping. After the spraying is completed, the fluidized state is maintained and the temperature is slowly reduced to 35°C to 45°C to promote the crystallization and solidification of the syrup on the surface of the core layer.

6. The black glutinous rice tea topping according to claim 1, characterized in that, The preparation method of the modified cassava resistant starch in the outer layer includes: preparing a 30%-40% suspension of ordinary cassava starch, adjusting the pH to 9.5-10.5, adding 1%-3% of octenyl succinic anhydride by weight of starch, reacting at 35℃-45℃ for 4-6 hours, adjusting the pH to 6.0-7.0 after the reaction, washing, drying, pulverizing and passing through a 200-mesh sieve; the average particle size of the microcrystalline cellulose is 50μm-80μm; the outer layer is applied in a roller coating machine at room temperature, by spreading the hydrophobic powder onto the surface of the material with the core layer and the intermediate layer in 2-4 times, and rolling at low speed for 2-5 minutes after each powder application to achieve uniform adsorption.

7. A method for preparing a black glutinous rice tea topping, applicable to the black glutinous rice tea topping described in any one of claims 1-6, characterized in that, The preparation method includes the following steps: S1: Core layer preparation: S101. Selection and soaking: Select whole, undamaged glutinous rice and soak it in soft water at a temperature of 25℃-35℃ for 2-4 hours, which is 2-3 times its weight. S102. Pregelatinization treatment: Drain the soaked glutinous rice, place it in a steaming equipment, introduce saturated steam, and treat it for 8-15 minutes at a pressure of 0.15MPa-0.25MPa. S103. Rapid cooling: Quickly transfer the pregelatinized hot glutinous rice to an ice-water mixture at 0°C to 4°C, stir continuously for 30 to 90 seconds, then remove and drain until no water droplets drip from the surface. S104. Plant protein membrane coating: The glutinous rice granules treated in step S103 are preheated to 45℃-60℃ and placed in a rotating coating pan with a heating jacket. While rotating, a 3%-8% aqueous solution of plant protein isolate is sprayed on, and a crosslinking agent is added at the same time. The final coating amount of plant protein isolate is controlled to be 1.5%-4% of the dry weight of the glutinous rice granules. The mixture is continuously rotated and dried with the assistance of hot air at 50℃-65℃ until the moisture content is ≤18%, thus obtaining the core material coated with a plant protein membrane. S2: Intermediate layer construction: S201. Syrup preparation: Weigh out white sugar, trehalose, maltitol solution and water according to the formula, heat to dissolve, heat to 105℃±2℃ and boil, concentrate until the solid content reaches 75°Brix to 85°Brix to obtain the basic syrup; cool the basic syrup to 80℃±5℃, add natural herbal extract, stir evenly, and keep warm for later use. S202, Fluidized Bed Coating Crystallization: The core material obtained in S1 is placed in a fluidized bed device, fluidization is turned on, and the inlet air temperature is set to 65℃-75℃; the syrup containing herbal extracts prepared in step S201 is atomized through a nozzle and sprayed onto the surface of the fluidized core material, controlling the spraying rate and the amount of syrup to ensure that the core surface is evenly covered; after spraying, the fluidization state is maintained and the inlet air temperature is gradually reduced, so that the material temperature slowly drops to 35℃-45℃. At 45℃, the syrup layer crystallizes and solidifies, forming an intermediate layer; S3: Outer coating: S301. Preparation of hydrophobic powder: Weigh the modified cassava resistant starch and microcrystalline cellulose according to the proportion, mix them evenly, and obtain hydrophobic coating powder. S302, Powder Coating: Transfer the material with the intermediate layer constructed to a roller coating machine. Under the conditions of room temperature and low speed rolling, the hydrophobic coating powder prepared in step S301 is evenly sprinkled into the roller in batches, and the total coating amount is controlled to account for 5%-12% of the total mass of the core layer and the intermediate layer. Roll until the powder is evenly attached to the surface of the material to form the outer layer, which is the finished product of multi-layer composite structure glutinous rice tea topping.

8. The method for preparing a topping for a blood glutinous rice tea according to claim 7, characterized in that, In step S104 of step S1, if the cross-linking agent is tannic acid, it is dissolved in edible ethanol with a volume not exceeding 2% of the volume of the plant protein isolate aqueous solution before being sprayed in; if the cross-linking agent is transglutaminase, it is directly sprayed in its powder form simultaneously and evenly during the spraying of the protein solution.

9. The method for preparing a black glutinous rice tea topping according to claim 7, characterized in that, In step S202 of step S2, the pressure of the atomizing spray is controlled at 0.2MPa-0.4MPa, and the rotation speed of the atomizing disc is 8000rpm-15000rpm; in step S302 of step S3, the rotation speed of the roller coating machine is controlled at 10rpm-20rpm, the powdering interval between each batch is 2-5 minutes, and the roller continues to roll for at least 2 minutes after each powdering before the next operation; the small material prepared by this method, when stored under sealed and light-proof conditions at room temperature, has a textural stability change rate of less than 5% within 72 hours.

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