Leaf-eating grass powder and processing technology

Abstract

This invention relates to the field of edible leaf grass powder processing technology, specifically to an edible leaf grass powder and processing technology, including the following steps: S100: Fresh tender stems and leaves of edible leaf grass are washed and sterilized, and then subjected to blanching, enzyme inactivation, drying, and pulverization to obtain fresh edible leaf grass powder; S200: The fresh edible leaf grass powder is mixed with water according to a set material-liquid ratio, alkali solution is added for purification, and a first solid-liquid separation is performed to obtain the supernatant; then acid solution is added to the supernatant to adjust to the isoelectric point for precipitation, and a second solid-liquid separation is performed to obtain protein precipitate, which is then washed with water to remove acid. This invention effectively overcomes the problems of enzymatic browning and protein thermal denaturation that are prone to occur in traditional edible leaf grass processing by constructing a technical system of precise blanching and enzyme inactivation combined with gentle extraction and purification; combined with microfiltration membrane physical impurity removal and a specific anti-sticking spray drying formula, the purity of the target product and the industrial powder collection rate are greatly improved.

Description

Technical Field

[0001] This invention relates to the field of edible leaf grass powder processing technology, specifically to an edible leaf grass powder and its processing technology. Background Technology

[0002] With increasing public awareness of health and the growing vegetarian population, plant-based proteins are experiencing increasing market demand in the food and nutrition sectors due to their advantages such as being cholesterol-free, low-allergenicity, and environmentally friendly. Leafy greens, as a novel high-protein plant resource, are considered a high-potential source of plant protein, as their stems and leaves are rich in crude protein and have a balanced amino acid composition.

[0003] However, converting leafy greens into high-quality, commercially viable food-grade protein powder still faces many insurmountable technical bottlenecks in existing processing technologies:

[0004] First, enzymatic browning is highly likely to occur, and it is difficult to preserve protein activity simultaneously. Fresh leaves of edible plants contain abundant polyphenols and highly active endogenous enzymes such as polyphenol oxidase. During conventional harvesting, crushing, and water extraction processes, the cell structure is damaged, easily triggering severe enzymatic browning reactions, resulting in a dark or black color of the extracted protein solution and final powder. To inhibit browning, current technologies typically employ prolonged high-temperature boiling to inactivate enzymes, but this inevitably leads to deep, irreversible thermal denaturation of plant proteins, significantly damaging their natural spatial conformation and biological activity. How to completely inactivate endogenous enzymes while maximizing the preservation of protein activity is a pressing problem to be solved in this field.

[0005] Secondly, purification and impurity removal are difficult, resulting in poor sensory quality of the product. In the traditional "alkali extraction and acid precipitation" process, due to the complexity of the leafy herb system, the extract often contains a large amount of free plant pigments, cellulose oligosaccharides, and inorganic salts. Conventional centrifugation and simple water washing are insufficient to completely remove these impurities, leading to high ash content in the resulting protein powder, and inevitably a strong plant-like, earthy, or acidic taste due to acid-base neutralization residue, severely limiting its application in high-end foods.

[0006] Finally, conventional plant proteins have large molecular weights, limiting their bioavailability. Plant proteins extracted using traditional processes are mostly high-molecular-weight proteins, whose solubility and absorption rate in the human intestine remain limited for groups with specific medical nutritional needs or weak intestinal digestive function. Existing plant enzymatic hydrolysis processes often suffer from problems such as incomplete cell wall disruption, insufficient exposure of enzymatic hydrolysis sites, or excessive hydrolysis producing bitter peptides, making it difficult to efficiently and effectively prepare deep-processed leafy green protein products rich in highly active small-molecule peptides.

[0007] Therefore, there is an urgent need to develop a new processing technology for leafy grass protein powder to systematically overcome the technical defects mentioned above, such as enzymatic browning, protein thermal denaturation, difficulty in purification and impurity removal, drying sticking to the wall, and low absorption rate of large molecular protein, so as to achieve large-scale standardized production of leafy grass protein powder and small molecule peptides with high purity, high activity, and excellent sensory quality. Summary of the Invention

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] This invention provides a leafy grass powder and its processing technology, comprising the following steps: S100: Fresh tender stems and leaves of leafy grass are washed and sterilized, then subjected to blanching, enzyme inactivation, drying, and pulverization to obtain fresh leafy grass powder; S200: The fresh leafy grass powder is mixed with water according to a set material-liquid ratio, purified by adding alkaline solution, and subjected to a first solid-liquid separation to obtain a supernatant; then acid solution is added to the supernatant to adjust to the isoelectric point for precipitation, followed by a second solid-liquid separation to obtain protein precipitate, which is then washed with water to remove acid; S300: The protein precipitate is re-dissolved in water, filtered to remove impurities and desalted, and then concentrated under reduced pressure to obtain a protein concentrate of a specified concentration; S400: Dextrin is added to the protein concentrate as a drying aid, followed by spray drying to collect dried leafy grass protein powder; S500: The leafy grass protein powder is cooled, sieved, and then an anti-caking agent and an antioxidant are added and mixed evenly, and finally sealed and packaged.

[0010] Further, in step S100, the cleaning and sterilization process includes: using bubble cleaning, followed by ozone sterilization or ultrasonic sterilization, and finally rinsing with sterile water.

[0011] The treatment conditions for blanching and enzyme inactivation are: treatment at 90°C for 15 minutes.

[0012] Further, in step S100, the drying method is low-temperature hot air drying or vacuum drying, until the moisture content is ≤8%;

[0013] The temperature of the low-temperature hot air drying is 55–60℃;

[0014] The pulverization process includes coarse pulverization and ultrafine pulverization, with the fineness of the ultrafine pulverization controlled at 500-1000 mesh.

[0015] Further, in step S200, the set material-liquid ratio is: fresh leafy grass powder and water are mixed in a ratio of 1:25;

[0016] The conditions for purification by adding alkaline solution are as follows: adjust the pH of the extract to 10.0 and carry out stirring extraction at a temperature of 40°C;

[0017] The stirring extraction time is 25 minutes; during the stirring extraction process, ultrasonic treatment is performed for 10 minutes.

[0018] Further, in step S200, the specific operation of adding acid to the supernatant to adjust to the isoelectric point for precipitation is as follows: add acid to adjust the pH to 4.5 and let it stand for 30 minutes;

[0019] Both the first and second solid-liquid separations were performed using centrifugation. The centrifugation conditions were: rotation speed 3500 r / min, centrifugation time 20 minutes.

[0020] The specific operation of the water washing to remove acid is as follows: add deionized water to the protein precipitate obtained by the second solid-liquid separation and wash twice, and then centrifuge again to remove residual acid.

[0021] Further, in step S300, the specific operation of redissolving the protein precipitate with water is as follows: adding deionized water to the protein precipitate and adjusting the pH of the solution to 7.0;

[0022] The filtration, impurity removal, and desalination are carried out using microfiltration or ultrafiltration processes.

[0023] The filter membrane used has a pore size of 0.22 μm to achieve desalination and decolorization.

[0024] The vacuum concentration process is as follows: temperature controlled at 55–60℃, vacuum degree controlled at -0.08MPa;

[0025] The protein concentrate of the specified concentration has a protein mass concentration of 35%.

[0026] Further, in step S400, the specific operation of adding dextrin to the protein concentrate is as follows: add dextrin at 4% of the mass of the protein concentrate.

[0027] Further, in step S400, the process conditions for spray drying are: feed flow rate of 10 mL / min;

[0028] The inlet air temperature of the spray dryer is controlled at 150℃, and the outlet air temperature is controlled at 80–85℃.

[0029] Further, in step S500, the specific conditions for cooling and sieving are as follows: after cooling at room temperature, sieve using a 100-120 mesh screen.

[0030] Further, in step S500, the specific ratio of the added anti-caking agent to the antioxidant is as follows: based on 100kg of the final product of leafy grass protein powder, the added anti-caking agent is 0.3-0.5kg of silicon dioxide, and the added antioxidant is 0.1-0.2kg of vitamin C or rosemary extract.

[0031] The specific operation of the sealed packaging is as follows: nitrogen-filled sealing is used for light-proof and moisture-proof packaging.

[0032] Beneficial effects

[0033] This invention effectively overcomes the challenges of enzymatic browning and protein denaturation that are prone to occur in traditional leafy green processing by constructing a technical system of "precise blanching and enzyme inactivation combined with gentle extraction and purification." Combined with microfiltration membrane physical impurity removal and a specific anti-sticking spray drying formula, it significantly improves the purity of the target product (crude protein ≥80%) and the industrial powder collection rate, while completely removing residual plant acids and earthy odors, giving the protein powder a clear, bright color and excellent sensory qualities. More importantly, this invention innovatively introduces variable-temperature composite targeted enzymatic hydrolysis technology, achieving complete disintegration of the plant's robust cell walls and precise shearing of large protein molecules, successfully producing a high-value-added product with a high content of small-molecule peptides exceeding 86.8%, significantly improving the product's intestinal absorption rate and bioavailability. Attached Figure Description

[0034] Figure 1 This is a flowchart of a leafy herb powder and its processing technology according to the present invention. Detailed Implementation

[0035] To enable those skilled in the art to better understand the present invention, 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. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0036] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but includes other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0037] The present invention will now be described in further detail with reference to the accompanying drawings:

[0038] Example 1:

[0039] As shown in the figure, an edible leaf herb powder and its processing technology include the following steps:

[0040] S100: Fresh stems and leaves of edible grass are washed and sterilized, and then subjected to blanching, enzyme inactivation, drying and pulverization to obtain edible grass powder.

[0041] S200: The fresh powder of the edible grass is mixed with water according to the set material-liquid ratio, and then alkali solution is added for purification and the first solid-liquid separation is performed to obtain the supernatant; then acid solution is added to the supernatant to adjust to the isoelectric point for precipitation, and the protein precipitate is obtained by the second solid-liquid separation and then washed with water to remove acid.

[0042] S300: The protein precipitate is reconstituted with water, filtered to remove impurities and desalt, and then concentrated under reduced pressure to obtain a protein concentrate of a specified concentration;

[0043] S400: Add dextrin as a drying agent to the protein concentrate, then spray dry and collect the dried leafy grass protein powder.

[0044] S500: After cooling and sieving the edible grass protein powder, add anti-caking agent and antioxidant, mix evenly, and finally seal and package.

[0045] Furthermore, the specific implementation process of step S100 is as follows:

[0046] In step S100, the raw material pretreatment stage, the main purpose is to ensure the cleanliness of the edible leaf grass raw material from the source, and to retain the activity of the plant protein to the greatest extent through specific physical and thermal treatment methods, and finally transform it into a high specific surface area powder form that is easy to extract in the future.

[0047] Specifically, before formal production, the initial raw materials are rigorously screened, selecting tender stems and leaves of edible grasses free from yellow leaves and pests to ensure the high quality and pure color of the final protein powder. After selection, the edible grasses undergo deep cleaning and sterilization. In a preferred embodiment of the invention, the cleaning and sterilization process includes the following steps: first, preliminary cleaning is performed using bubble cleaning equipment, effectively removing mud, dust, and some impurities adhering to the surface of the stems and leaves by utilizing the tumbling and bursting action of bubbles; then, ozone sterilization or ultrasonic sterilization is performed, utilizing the strong oxidizing properties of ozone or the cavitation effect of ultrasound to deeply kill bacteria and microorganisms hidden on the surface and in crevices of the material; finally, a thorough rinsing is performed using sterile water to remove any residual sterilization media and prevent secondary contamination.

[0048] After rinsing and draining, the stems and leaves of the edible grass then enter the crucial step of blanching and enzyme inactivation.

[0049] In this invention, through experimental verification, the treatment conditions for blanching and enzyme inactivation are strictly set as follows: treatment at 90°C for 15 minutes.

[0050] This specific combination of temperature and time has a dual and irreplaceable technical effect here:

[0051] On the one hand, 90℃ can quickly and thoroughly inactivate enzymes such as polyphenol oxidase inside leafy grass that easily cause browning of materials, thus fundamentally preventing the protein powder from turning dark or black due to enzymatic browning during subsequent processing (i.e., preventing browning).

[0052] On the other hand, the 15-minute short blanching process, compared to the traditional high-temperature long cooking, can minimize the deep irreversible thermal denaturation of plant proteins (i.e., protein preservation) while inactivating enzymes, laying the foundation for the subsequent extraction of highly active and nutritious protein powder.

[0053] After blanching and enzyme inactivation, the material is in a high-humidity state and needs to be dehydrated and dried. To prevent the aforementioned highly active proteins from denaturing due to heat during drying, this invention abandons the conventional high-temperature baking process and instead adopts low-temperature hot air drying or vacuum drying technology. In a more preferred embodiment, a low-temperature hot air drying device with the inlet air temperature controlled at 55–60℃ is used to continuously dehydrate the blanched material until the moisture content of the material is reduced to 8% or below. Strictly controlling the moisture content below 8% not only gives the material good brittleness, greatly facilitating subsequent pulverization operations, but also effectively inhibits the growth of microorganisms during storage, extending the shelf life of the semi-finished product.

[0054] Finally, the dried leafwort is pulverized to obtain raw material powder. To fully break down the physical barrier of the plant cell wall and promote the dissolution of free and bound proteins within the cells, the pulverization process of this invention involves two stages: coarse pulverization and ultrafine pulverization. Preferably, the final fineness of the ultrafine pulverization is controlled between 500-1000 mesh. When the material fineness reaches this micron level, the plant cell structure of the leafwort is highly disrupted, and the specific surface area of ​​the material increases exponentially. This structural change significantly enhances the hydration capacity of the material in the subsequent "alkali extraction and acid precipitation" steps, allowing the extraction solvent to penetrate the material more fully and rapidly, thereby greatly improving the protein extraction rate. After the above series of refined treatments, a fresh leafwort powder with an initial crude protein content of approximately 48.7% is finally obtained, serving as a standardized material for subsequent core extraction steps.

[0055] Furthermore, the specific implementation process of S200 is as follows:

[0056] After completing the raw material pretreatment in step S100, the protein extraction stage begins. This stage mainly utilizes the difference in solubility of plant proteins under different acidic and alkaline environments, and through a combined process of "alkali extraction and acid precipitation," the target protein is efficiently separated from complex plant fibers and non-protein impurities.

[0057] First, a slurry preparation process is performed, mixing the obtained edible herb powder with water. Through extensive exploration and optimization experiments, the applicant discovered that the material-to-liquid ratio has a decisive impact on the final protein extraction rate and subsequent energy consumption. In a preferred embodiment of the invention, the edible herb powder and water are prepared at a specific ratio of 1:25 (g / mL). If too little water is added (material-to-liquid ratio below 1:20), the system viscosity is too high, which is not conducive to the dissolution and diffusion of protein molecules, resulting in incomplete extraction; if too much water is added (material-to-liquid ratio above 1:30), although the dissolution rate can be slightly improved, it will greatly increase the processing burden and energy consumption of the subsequent concentration and drying stages. The optimal material-to-liquid ratio of 1:25 ensures the highest mass transfer efficiency while also taking into account the economics of industrial production.

[0058] After the pulping process, an alkaline solution (e.g., 1 mol / L NaOH solution) is added to the system for alkaline purification. During this process, the pH of the extract is strictly controlled to 10.0, and constant-temperature stirring extraction is carried out at a mild thermal environment of 40℃ for 25 minutes. Choosing a slightly alkaline environment of pH 10.0 allows most protein molecules in the leafwort to carry the same charge, and the electrostatic repulsion between like charges promotes the protein molecules to unfold and become highly soluble in water. At the same time, the extraction temperature of 40℃ accelerates the thermal motion of molecules, shortens the extraction time, and effectively avoids excessive protein denaturation or amino acid racemization caused by high temperature.

[0059] To further enhance extraction potential, in a preferred embodiment, ultrasonic treatment is performed for 10 minutes during the stirring extraction process. The cavitation effect generated by ultrasound in the liquid produces powerful microjets and localized high pressure, completely tearing apart the remaining plant cell walls and cell membranes, causing the intracellular proteins to be released instantaneously, significantly improving the single-pass extraction rate of the target protein.

[0060] After alkali extraction, the mixture is subjected to a first solid-liquid separation. Specifically, a centrifuge is used at 3500 r / min for 20 minutes to remove the precipitate rich in insoluble solids such as crude fiber and starch, and the supernatant rich in soluble plant protein is collected.

[0061] Subsequently, the crucial isoelectric point precipitation (acid precipitation) step begins. An acid solution (e.g., 1 mol / L HCl solution) is slowly added dropwise to the collected supernatant until the pH of the system precisely drops to 4.5. The applicant discovered that pH 4.5 is precisely the isoelectric point (pI) of the main proteins in *Gnaphalium affine*. At the isoelectric point, the net charge on the surface of protein molecules approaches zero, the electrostatic repulsion between molecules disappears, and hydrophobic interactions become dominant, causing the originally dissolved protein molecules to rapidly aggregate into large-molecule flocs and precipitate. After the addition is complete, the system is allowed to stand for 30 minutes to ensure that the protein flocculation and precipitation reaction is completely completed and the particles grow to a size that is easy to separate.

[0062] Finally, the precipitated liquid underwent a second solid-liquid separation. It was centrifuged at 3500 rpm for 20 minutes. The supernatant at this point was a waste liquid containing water-soluble sugars, some pigments, and salts, while the bottom layer was a high-purity protein precipitate (protein curd). To remove soluble salts (such as NaCl) and residual free acid generated during the aforementioned acid-base neutralization process, an appropriate amount of deionized water was added to the collected protein precipitate for thorough dispersing and washing. This washing process was repeated twice, and centrifugation was performed again after each wash.

[0063] Furthermore, the specific implementation process of S300 is as follows:

[0064] After isoelectric point precipitation and washing in step S200, although the target protein has been initially separated, the protein precipitate (protein curd) still contains trace amounts of pigments, large molecular salts, and excess water. Furthermore, due to its isoelectric point (pH 4.5) state, the protein is in an insoluble aggregated state and cannot be directly used for subsequent fluid drying. Therefore, it is necessary to proceed to step S300 for further purification and concentration.

[0065] First, the obtained protein precipitate is reconstituted. Specifically, an appropriate amount of deionized water is added to the protein precipitate in a specific ratio, and a mild pH adjuster is slowly added dropwise to precisely adjust the pH of the solution to a neutral state of 7.0. The applicant points out that the process of adjusting the pH from the isoelectric point to 7.0 is crucial. In a neutral environment, the surface charge of the leafwort protein molecules redistributes, and the electrostatic repulsion is restored, causing the previously aggregated protein particles to unfurl and dissolve uniformly in the water, forming a stable protein solution. Simultaneously, the neutral environment is extremely mild, minimizing the damage to the amino acid sequence and spatial conformation of the protein caused by strong acids or alkalis, thus maintaining the protein's natural high activity.

[0066] Subsequently, the reconstituted neutral protein solution is pumped into a membrane separation device for filtration, impurity removal, and desalination. In a preferred embodiment of the invention, microfiltration or ultrafiltration is used for deep purification, preferably using a filter membrane with a pore size of 0.22 μm. This high-precision filter membrane acts as a highly efficient "molecular sieve": under a certain pumping pressure, water molecules, as well as small molecule impurities such as soluble inorganic salts (e.g., sodium chloride), tiny plant free pigments, and insufficiently washed oligosaccharides remaining from the preceding acid-base neutralization reaction, can smoothly pass through the membrane pores and be discharged with the permeate (i.e., desalination and depigmentation); while larger molecular weight leafy grass protein molecules are physically retained on the retentate side.

[0067] To put it another way: this physical-level membrane separation and purification process does not introduce any chemical reagents, which not only greatly increases the crude protein content of the final protein powder (up to 80% or more), but also effectively removes plant pigments that may cause the product to appear dark, resulting in a high-quality light green or off-white color in the final product.

[0068] Finally, the filtered and refined protein solution is concentrated under reduced pressure to remove excess water from the system. To prevent thermal coagulation or browning reactions during the concentration and dehydration process of the high-purity protein solution, this invention abandons the traditional concentration method of atmospheric pressure and high-temperature boiling, and strictly defines the processing conditions for reduced pressure concentration as follows: temperature controlled at 55–60℃, and vacuum degree controlled at -0.08MPa. Under the high vacuum state of -0.08MPa, the boiling point of water is significantly reduced, allowing the system to achieve rapid boiling and evaporation of water in a mild thermal environment of 55–60℃. This low-temperature boiling state not only ensures extremely high concentration efficiency, but also acts like a "heat insulation suit" for the plant protein, preventing thermal denaturation of the protein. During the concentration process, the concentration of the solution is monitored in real time until a protein concentrate of the specified concentration is obtained, that is, the protein mass concentration reaches 35%, at which point the concentration is stopped. After repeated testing, the applicant found that a protein concentration of 35% is the "golden concentration" for connecting the subsequent spray drying process: if the concentration is too low (such as below 25%), it will lead to excessive evaporation load during spray drying, greatly increase energy consumption and reduce powder collection rate; if the concentration is too high (such as above 45%), it will cause the viscosity of the liquid to increase sharply, which will easily clog the atomizing nozzle of the spray dryer and affect the continuity of production.

[0069] Furthermore, the specific implementation process of S400 is as follows:

[0070] After obtaining a 35% concentrated protein solution in step S300, the product proceeds to the drying and powdering stage in step S400. Because high-purity plant protein solutions are extremely prone to becoming sticky and adhering to the drying tower walls during heated dehydration (i.e., the "wall-sticking" phenomenon), this not only leads to severe scorching and material denaturation but also significantly reduces the final powder collection rate. To overcome this technical bias, this invention incorporates crucial material preparation before spray drying.

[0071] Specifically, maltodextrin is precisely added to the aforementioned protein concentrate at 4% of the concentrate's mass and stirred thoroughly until completely dissolved. Maltodextrin acts as an excellent drying agent and anti-sticking agent (wall material), rapidly forming a very thin protective film on the surface of the protein droplets during spray atomization. This protective film not only effectively prevents direct adhesion between the droplets and the high-temperature tower wall but also significantly improves the powder's formability and flowability. In a preferred embodiment of this invention, the 4% addition amount is an excellent balance: too low an addition amount will fail to form a complete anti-sticking protective film; too high an addition amount will have the opposite effect, excessively diluting the actual protein content in the finished powder, resulting in the final product's crude protein content failing to meet the expected standard of 80%.

[0072] After preparation, the liquid material is pumped into a spray dryer for atomization drying. In a preferred embodiment of the invention, the spray drying process parameters are strictly set as follows: feed flow rate controlled at 10 mL / min, inlet air temperature set at 150°C, and outlet air temperature controlled at 80–85°C. The feed rate of 10 mL / min perfectly matches this temperature field, ensuring that the liquid material forms uniform micron-sized droplets when passing through the atomizer. The inlet air temperature of up to 150°C provides a strong enthalpy, causing the moisture on the surface of the droplets to vaporize instantly within a fraction of a second. More importantly, because the evaporation of moisture absorbs a large amount of latent heat of vaporization, the actual temperature inside the droplets is much lower than the inlet air temperature; combined with the outlet air temperature of 80–85°C, it ensures that the core temperature of the dried protein powder particles is within the absolutely safe range for plant proteins (usually below 70°C) when leaving the hot air zone. This instantaneous dehydration and "hot outside, cool inside" drying mechanism not only successfully reduced the moisture content of the finished product to below 5%, but also effectively avoided Maillard reaction (browning) and protein thermal denaturation. The final product is a uniformly colored leafy green protein powder with complete activity retention, and the powder collection rate can be stably reached above 33.6%.

[0073] Furthermore, the specific implementation process of S500 is as follows:

[0074] After spray drying, the collected leafy green protein powder still retains some residual heat and needs to be processed and packaged in step S500 to give the product excellent commercial properties and a long shelf life.

[0075] First, the freshly extracted protein powder is allowed to cool naturally to room temperature in a clean, room-temperature environment. The cooled powder is then sieved through a 100–120 mesh vibrating sieve. The purpose of sieving is to break up any tiny, pseudo-clumps that may form during collection, remove any accidentally generated burnt powder or large particles, and ensure a highly uniform particle size distribution in the final product. The 100–120 mesh ultrafine powder structure gives the product excellent solubility and a smooth, creamy texture.

[0076] Subsequently, the sieved protein powder is transferred to a three-dimensional mixer, and the formulated amounts of anti-caking agent and antioxidant are added for homogenization. For every 100 kg of finished leafy green protein powder, precisely add 0.3–0.5 kg of silica as an anti-caking agent and 0.1–0.2 kg of vitamin C or rosemary extract as a natural antioxidant. Silica has a sponge-like microporous structure, which can effectively adsorb free moisture around the powder within a range several times its own weight, thus completely cutting off the physical pathway of moisture absorption and clumping of the protein powder during its long shelf life. Vitamin C or rosemary extract, as food-grade natural antioxidants, can preferentially react with trace amounts of free oxygen in the packaging, scavenging free radicals and effectively blocking the oxidation chain reaction of plant proteins and associated trace lipids, fundamentally preventing the product from developing unpleasant odors such as rancidity in the later stages of storage.

[0077] Finally, the well-mixed finished product is transferred to a fully automated packaging line.

[0078] In this invention, a nitrogen-sealed packaging method is used for light-proof and moisture-proof packaging. By evacuating the composite aluminum foil packaging bag and refilling it with high-purity nitrogen, the residual oxygen level inside the packaging is reduced to an extremely low level. Simultaneously, combined with the 100% light-blocking and water-resistant properties of the aluminum foil material, the highly active plant protein is completely isolated from external light, oxygen, and moisture. This achieves precise parameter control throughout the entire process, from raw materials, extraction, refining, drying to packaging.

[0079] Example 2:

[0080] Advanced process route (enzymatic extraction for preparation of highly active proteins / small molecule peptides):

[0081] To further enhance the added value of plant protein and address the issues of large molecular weight and low absorption rate in the human gut associated with traditional plant proteins, this process utilizes targeted enzymatic hydrolysis technology with specific sequences to break down plant cell wall barriers and precisely cleave large protein molecules into easily absorbed, highly active small peptides. The specific implementation steps are as follows:

[0082] Phase 1: Substrate pretreatment and endogenous enzyme inactivation:

[0083] The prepared dried leafwort powder was mixed thoroughly with deionized water according to a set ratio. The mixture was then treated at a constant temperature of 90°C for 15 minutes. This step aims to completely inactivate the endogenous polyphenol oxidase and other enzymes latent in the dried leafwort powder. The applicant points out that without this inactivation step, endogenous enzymes would proliferate rapidly and cause severe enzymatic browning during the subsequent long and gentle enzymatic hydrolysis process, resulting in a black-colored polypeptide powder with a bitter taste. The 90°C, 15-minute treatment not only achieves complete inactivation but also provides a moderate thermal expansion of the powder, opening a physical pathway for the subsequent addition of external enzymes.

[0084] Phase Two: Complex Enzymatic Hydrolysis A (Deep Cell Wall Disruption and Release):

[0085] After pretreatment, the temperature of the solution is lowered to the optimal operating range of the enzymes, entering the "compound enzymatic hydrolysis A" stage. Cellulase and pectinase are simultaneously added to the solution for synergistic cell wall disruption. The plant cell wall is a robust network interwoven with a cellulose backbone and pectin fillers, which is difficult to completely destroy with a single enzyme. This invention employs a variable-temperature reaction strategy: first, the reaction is carried out at 40–45℃ for 4–5 hours, at which point pectinase activity is highest, degrading the pectin in the cell wall first and exposing the cellulose backbone; then, the system temperature is slowly raised to 50–55℃ and the reaction continues for 2–3 hours, at which point the system switches to the optimal temperature range for cellulase, completely severing the cellulose chains. This variable-temperature synergistic dual-enzymatic hydrolysis technology of "first depolymerizing pectin, then severing the backbone" achieves a "disintegrative" destruction of the leafy plant cell wall, allowing the intracellular binding proteins originally encased in the dense cell wall to be released into the aqueous environment to the maximum extent.

[0086] Third stage: Intermediate separation and water washing purification:

[0087] After completing the enzymatic hydrolysis of compound A, the reaction system was centrifuged to extract a solid precipitate rich in the target protein. To remove the large amounts of water-soluble plant polysaccharides, oligosaccharides, pigments, and inactivated cell-breaking enzymes released during the cell disruption process, the extracted solids were subjected to three consecutive high-efficiency washes and centrifugations using deionized water. This thorough "three-wash" process significantly purified the protein substrate and eliminated steric hindrance interference from non-protein impurities on subsequent proteolytic sites.

[0088] Stage 4: Complex enzymatic hydrolysis of B (initial cleavage under neutral conditions):

[0089] The purified solids were reconstituted with water and then proceeded to the "complex enzymatic hydrolysis B" stage. Neutral protease was added to the system, and the reaction was continued at a constant temperature of 55–60°C for 4–5 hours. In this mild, slightly warm, neutral environment, the neutral protease accurately recognized and cleaved the hydrophobic amino acid peptide bonds in the crude protein of the leafwort, initially depolymerizing the large, insoluble protein with a complex quaternary structure into medium-molecular-weight water-soluble peptides and oligopeptides.

[0090] Phase 5: Alkaline extraction combined with alkaline protease (deep targeted cleavage):

[0091] To further cleave medium and large molecular weight peptides into highly bioactive ultra-low molecular weight small molecule peptides, this process subsequently employs a clever combined treatment of "alkali extraction + alkaline protease". Alkali solution is added to the above-mentioned feed solution to precisely adjust the pH of the system to between 9.5 and 10, while alkaline protease is added, and the reaction continues at 55°C for 2–3 hours.

[0092] This step emphasizes its synergistic innovation: on the one hand, the alkaline environment of pH 9.5-10 causes the polypeptide chain to stretch extremely and electrostatically repel, exposing more deep cleavage sites.

[0093] On the other hand, this pH value is precisely the peak activity of alkaline protease. Under the dual action of "alkaline relaxation" and "highly active shearing," the remaining large peptide molecules are deeply and thoroughly hydrolyzed into small peptide fragments that are easily absorbed directly by the human body.

[0094] Stage 6: Enzyme inactivation, separation, and drying into powder:

[0095] After deep enzymatic hydrolysis, the solution is rapidly heated to above 90°C and maintained for 10-15 minutes to completely denature and inactivate all proteases in the system (i.e., enzyme inactivation), terminating the enzymatic hydrolysis reaction and preventing excessive hydrolysis of peptides into free amino acids that would produce a bitter taste. After enzyme inactivation, the solution is centrifuged at high speed again, and the supernatant extract rich in peptides is collected (if necessary, multiple batches of extracts can be combined for homogenization). Finally, the peptide extract is subjected to the aforementioned vacuum concentration and spray drying processes to obtain highly active edible leafwort peptide powder.

[0096] Experimental results show that the finished product prepared using the advanced enzymatic process described above in this invention contains 86.8% or more small molecule peptides with extremely low molecular weight. This polypeptide powder not only possesses extremely high solubility and reconstitution properties, but its bioavailability and nutritional activity also far exceed those of conventional plant protein powders, making it widely applicable in special medical purpose formula foods or high-end sports nutrition foods.

[0097] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A leafy vegetable powder and processing technology, characterized in that, Includes the following steps: S100: Fresh stems and leaves of edible grass are washed and sterilized, and then subjected to blanching, enzyme inactivation, drying and pulverization to obtain edible grass powder. S200: The fresh powder of the edible grass is mixed with water according to the set material-liquid ratio, and then alkali solution is added for purification and the first solid-liquid separation is performed to obtain the supernatant; then acid solution is added to the supernatant to adjust to the isoelectric point for precipitation, and the protein precipitate is obtained by the second solid-liquid separation and then washed with water to remove acid. S300: The protein precipitate is reconstituted with water, filtered to remove impurities and desalt, and then concentrated under reduced pressure to obtain a protein concentrate of a specified concentration; S400: Add dextrin as a drying agent to the protein concentrate, then spray dry and collect the dried leafy grass protein powder. S500: After cooling and sieving the edible grass protein powder, add anti-caking agent and antioxidant, mix evenly, and finally seal and package.

2. The food leaf grass powder and processing technology according to claim 1, characterized in that, In step S100, the cleaning and sterilization process includes: using bubble cleaning, followed by ozone sterilization or ultrasonic sterilization, and finally rinsing with sterile water. The treatment conditions for blanching and enzyme inactivation are: treatment at 90°C for 15 minutes.

3. The food leaf grass powder and processing technology according to claim 2, characterized in that, In step S100, the drying method is low-temperature hot air drying or vacuum drying, until the moisture content is ≤8%; The temperature of the low-temperature hot air drying is 55–60℃; The pulverization process includes coarse pulverization and ultrafine pulverization, with the fineness of the ultrafine pulverization controlled at 500-1000 mesh.

4. The food leaf grass powder and processing technology according to claim 3, characterized in that, In step S200, the set material-liquid ratio is: fresh leafy grass powder and water are mixed in a ratio of 1:25; The conditions for purification by adding alkaline solution are as follows: adjust the pH of the extract to 10.0 and carry out stirring extraction at a temperature of 40°C; The stirring extraction time is 25 minutes; during the stirring extraction process, ultrasonic treatment is performed for 10 minutes.

5. The food leaf grass powder and processing technology according to claim 4, characterized in that, In step S200, the specific operation of adding acid to the supernatant to adjust to the isoelectric point for precipitation is as follows: add acid to adjust the pH to 4.5 and let it stand for 30 minutes; Both the first and second solid-liquid separations were performed using centrifugation. The centrifugation conditions were: rotation speed 3500 r / min, centrifugation time 20 minutes. The specific operation of the water washing to remove acid is as follows: add deionized water to the protein precipitate obtained by the second solid-liquid separation and wash twice, and then centrifuge again to remove residual acid.

6. The edible leaf grass powder and processing technology according to claim 5, characterized in that, In step S300, the specific operation of redissolving the protein precipitate with water is as follows: adding deionized water to the protein precipitate and adjusting the pH of the solution to 7.0; The filtration, impurity removal, and desalination are carried out using microfiltration or ultrafiltration processes. The filter membrane used has a pore size of 0.22 μm to achieve desalination and decolorization. The vacuum concentration process is as follows: temperature controlled at 55–60℃, vacuum degree controlled at -0.08MPa; The protein concentrate of the specified concentration has a protein mass concentration of 35%.

7. The edible leaf grass powder and processing technology according to claim 6, characterized in that, In step S400, the specific operation of adding dextrin to the protein concentrate is as follows: add dextrin at 4% of the mass of the protein concentrate.

8. The edible leaf grass powder and processing technology according to claim 7, characterized in that, In step S400, the process conditions for spray drying are: feed flow rate of 10 mL / min; The inlet air temperature of the spray dryer is controlled at 150℃, and the outlet air temperature is controlled at 80–85℃.

9. The edible leaf grass powder and processing technology according to claim 8, characterized in that, In step S500, the specific conditions for cooling and sieving are as follows: after cooling at room temperature, sieve using a 100-120 mesh screen.

10. The edible leaf grass powder and processing technology according to claim 8, characterized in that, In step S500, the specific ratio of the added anti-caking agent to the antioxidant is as follows: based on 100kg of the final product of leafy grass protein powder, the added anti-caking agent is 0.3-0.5kg of silicon dioxide, and the added antioxidant is 0.1-0.2kg of vitamin C or rosemary extract. The specific operation of the sealed packaging is as follows: nitrogen-filled sealing is used for light-proof and moisture-proof packaging.

Images