Preparation process of Xanthoceras sorbifolia bunge leaf instant solid tea with high antioxidant activity

Abstract

This invention belongs to the field of food processing technology and discloses a preparation process for a highly antioxidant-active instant solid tea made from *Xanthoceras sorbifolium* leaves. The specific raw materials and proportions of this solid tea include: main ingredient: *Xanthoceras sorbifolium* leaves, harvested annually from June to August, washed, dried, and ready for use; auxiliary ingredients, compound additives: flavoring agent: mogroside or steviol glycoside, 0.5%–2.0%; filler: maltodextrin, added at 10%–30% of the *Xanthoceras sorbifolium* leaf extract powder content; wetting agent: 95% edible alcohol. This invention uses *Xanthoceras sorbifolium* leaves as the core efficacy carrier, specifically enriching its ketone active ingredients. Compared to existing dried teas and coarsely processed teas made solely from *Xanthoceras sorbifolium* leaves, the effective ingredient content is increased by more than 40% (comparative experiment: using the same weight of *Xanthoceras sorbifolium* leaves, after extraction and concentration, the flavonoid content of this invention reaches 19.84 mg / g, while the ketone content dissolved after brewing existing dried tea is only 7.1 mg / g), significantly enhancing core effects such as antioxidant and free radical scavenging.

Description

Technical Field

[0001] This invention belongs to, but is not limited to, the field of food processing technology, and particularly relates to a preparation process for a highly antioxidant-active instant solid tea made from Xanthoceras sorbifolium leaves. Background Technology

[0002] *Xanthoceras sorbifolium* is a rare and precious woody oilseed plant unique to my country. Its leaves are rich in active ingredients such as flavonoids, polyphenols, saponins, and polysaccharides, exhibiting significant antioxidant, lipid-lowering, and blood sugar-lowering pharmacological effects. *Xanthoceras sorbifolium* leaves are rich in nutrients, containing 19.8% protein and 16 types of amino acids, including lysine at 35 mg / kg. The leaves also contain 11 trace elements, including iron, zinc, copper, chromium, barium, manganese, and succinate. Specifically, iron content is 255.5 μg / g, copper is 12 μg / g, and zinc is 21.4 μg / g. The highest organic acid content is 2.61 g / kg. The main active ingredients in *Xanthoceras sorbifolium* leaves include saponins, flavonoids, and polyphenols, with flavonoid content at 3.84% and saponin content at 5.3%. The flavonoids in *Xanthoceras sorbifolium* leaves have antioxidant, antibacterial, and anti-inflammatory effects, which can effectively improve kidney dysfunction, prevent the reabsorption of protein nutrients, promote bladder peristalsis, increase urine output, and excrete large amounts of urea (sodium urate) through urine, thus lowering high uric acid and assisting in the treatment of gout. Simultaneously, the flavonoids and myricetin in *Xanthoceras sorbifolium* leaves have hemostatic, cholesterol-lowering, lipid-clearing, and blood pressure-regulating effects. Furthermore, the saponins in *Xanthoceras sorbifolium* leaves have strong anti-cancer activity and can activate brain cells, enhancing learning and memory abilities. *Xanthoceras sorbifolium* leaves do not contain theophylline or caffeine; drinking them at night will not cause insomnia but rather have a calming effect and improve sleep quality.

[0003] Currently, the development of *Vernicia fordii* leaves is limited to the initial stage of processing them into tea after processing. This tea, steeped in boiling water, has a low content of active ingredients, and its therapeutic effects are not immediately apparent, leading to consumer reluctance to consume it long-term. Therefore, the development and utilization of *Vernicia fordii* leaves has reached a bottleneck. Using *Vernicia fordii* leaves as raw material, it is possible to develop dietary products that can be taken regularly and in measured amounts for the treatment and prevention of gout. These products have a high content of active ingredients, show effects in a short period, are convenient to take, and have no toxic side effects. Existing instant tea preparation processes mostly use a single water extraction and alcohol precipitation method or a direct spray drying method, which has the following drawbacks: low extraction rate of active ingredients; poor product solubility: direct drying easily leads to tea powder absorbing moisture and clumping, resulting in sedimentation after brewing and poor instant solubility; bitter taste: *Vernicia fordii* leaves naturally have a certain bitterness, and current processes do not effectively modify this flavor, leading to low consumer acceptance; insufficient retention of antioxidant activity: traditional high-temperature concentration and drying processes easily destroy heat-sensitive antioxidants. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a preparation process for a highly antioxidant-active instant solid tea made from Xanthoceras sorbifolium leaves.

[0005] This invention is achieved by providing a highly antioxidant-active instant solid tea made from Xanthoceras sorbifolium leaves. The specific ingredients and proportions of this solid tea include:

[0006] Main ingredient: Sapindus mukorossi leaves, harvested from June to August each year, washed and dried for later use;

[0007] Excipients, compound additives:

[0008] Flavoring agents: mogrosides or steviol glycosides, 0.5%–2.0%;

[0009] Filler: Maltodextrin, added at 10%–30% of the content of *Sapindus mukorossi* leaf extract powder;

[0010] Wetting agent: 95% edible alcohol.

[0011] Another object of the present invention is to provide a method for preparing a high antioxidant activity *Xanthoceras sorbifolium* leaf instant solid tea as described in claim 1, the method comprising:

[0012] S1: Add the leaves of *Sapindus mukorossi* directly into boiling water at a material-to-liquid ratio of 1:20 to 1:40 g / mL, and reflux for 60 min;

[0013] S2: Filter while hot and collect the filtrate; the filter residue can be extracted a second time, with a material-to-liquid ratio of 1:10 to 1:20, for 30 minutes.

[0014] S3: The combined filtrate is vacuum concentrated to a thick paste under the conditions of 55-60℃ and 0.075-0.085MPa, with a specific gravity of 1.18-1.20, to obtain the concentrate;

[0015] S4: The concentrate is dried in a vacuum drying oven at 75℃;

[0016] S5: The dry extract is pulverized and then compounded, with maltodextrin added at 10%–30% and mogrosides added at 1%–3%.

[0017] S6: Spray the prepared powder with a wetting agent to make a soft material. The spraying amount is 20% to 30% of the powder. After passing through a 10-mesh sieve, put it in an oven to dry for 60 minutes. After taking it out, place it in a dry place to air dry to room temperature and then sieve it again. Take the particles below 20 mesh and above 40 mesh for later use. Adjust the sealing temperature of the automatic granule packaging machine to 125℃. Package each bag with a net content of 3.5g ± 0.5g to obtain the finished product.

[0018] Based on the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solution to be protected by this invention are as follows:

[0019] This invention utilizes an ultrasonic boiling water direct feeding method to optimize the extraction process, ensuring maximum extraction rate and content of effective components. The intermediate raw material, *Xanthoceras sorbifolium* leaf extract powder obtained through extraction, filtration, concentration, and drying, is used to prepare a "*Xanthoceras sorbifolium* leaf instant solid tea" product with high antioxidant activity, wind-dispelling and dampness-removing, swelling-reducing and pain-relieving functions, which can be developed as a functional food. This fully develops and utilizes *Xanthoceras sorbifolium* leaf resources, breaking through the current bottleneck in resource utilization, and providing a non-toxic and side-effect-free dietary therapy product for sub-healthy individuals.

[0020] First, the instant solid tea formula and preparation process of *Xanthoceras sorbifolium* leaves disclosed in this invention have the following significant advantages and positive effects compared with existing technologies (including traditional *Xanthoceras sorbifolium* leaf tea, ordinary instant tea, and similar medicinal and edible teas). All advantages have been verified by comparative experiments, and the data support is sufficient, as follows:

[0021] I. The formula is highly innovative, with strong synergistic effects and excellent palatability.

[0022] 1. Advantages of core ingredient compatibility: This invention uses the leaves of *Xanthoceras sorbifolium*, a novel food ingredient, as the core efficacy carrier, specifically enriching its ketone active ingredients. Compared with existing dried teas and coarsely processed teas made solely from *Xanthoceras sorbifolium* leaves, the content of effective ingredients is increased by more than 40% (comparative experiment: using the same quality of *Xanthoceras sorbifolium* leaves, after extraction and concentration, the flavonoid content of this invention reaches 19.84 mg / g, while the ketone content dissolved after brewing existing dried tea is only 7.1 mg / g), significantly enhancing core efficacy such as anti-oxidation and free radical scavenging.

[0023] 2. Breakthrough in Flavoring Agent Selection and Synergistic Effects: This invention selects mogroside as the sole flavoring agent, which has three advantages compared to commonly used sucrose, steviol glycosides, and aspartame in existing technologies: First, it is safer, being non-toxic and low in calories (only 1 / 500th the calories of sucrose), avoiding the metabolic problems caused by sucrose and the potential risks of artificial sweeteners; second, it has a superior taste, with a sweetness 300 times that of sucrose, requiring only 1%-4% to achieve the ideal flavor, and relying on its unique triterpenoid skeleton structure, the sweetness is long-lasting without unpleasant aftertaste (comparative experiment: sensory evaluation score 8.6 points, steviol glycoside group scored only 6.2 points due to bitter aftertaste, sucrose group scored 7.3 points due to excessive sweetness); third, it has synergistic effects, with the antioxidant, liver-protective, and metabolic regulating activities of mogroside itself superimposed with the anti-inflammatory and anti-cancer effects of Xanthoceras sorbifolium leaves, giving the product both nutritional and health benefits and flavor optimization value, rather than simply flavor enhancement.

[0024] 3. Precise and controllable formula: This invention clearly defines the optimal ratio of Xanthoceras sorbifolium leaf extract to mogroside as 100:4 (by mass). At the same time, it optimizes the amount of excipients added to ensure a balance between product solubility, stability and efficacy. Compared with existing Xanthoceras sorbifolium leaf tea drinks without a clear ratio, the batch consistency of the product is improved by more than 90%, and there are no problems such as clumping or layering.

[0025] II. Advanced preparation process, high retention rate of effective ingredients and excellent production efficiency

[0026] 1. Optimized Extraction and Concentration Process: This invention employs a combined process of "direct extraction with boiling water - vacuum low-temperature concentration," with a reflux extraction time of 30 minutes. Compared to the existing method of soaking followed by extraction (total time 150 minutes), this shortens the extraction time, increases the retention rate of flavonoids from *Xanthoceras sorbifolium* leaves by 35%, and reduces the loss of antioxidant activity by 42% (comparative experiment: the IC50 values ​​of the extract of this invention for scavenging DPPH and ABTS free radicals are 1.36 μg / mL and 3.17 μg / mL, respectively, demonstrating extremely strong antioxidant properties). Simultaneously, vacuum low-temperature concentration avoids the damage of high temperatures to active ingredients, increasing concentration efficiency by 25% compared to conventional vacuum concentration and reducing energy consumption by 30%.

[0027] 2. Breakthrough in rapid dissolution molding process: This invention uses spray drying to prepare solid powder, optimizing the inlet air temperature to 180℃, the outlet air temperature to 80℃, and the feeding speed to 15mL / min. The resulting product has a moisture content controlled below 6% and excellent solubility (completely dissolves in water at 25℃ within 30s). Compared with the existing freeze-drying molding process, the production cycle is shortened by 60%, and the production cost is reduced by 45%, making it more suitable for large-scale industrial production (comparative experiment: the spray-drying group takes 2.5 hours to produce 1kg of product, while the freeze-drying group takes 6.2 hours. The unit product cost of the spray-drying group is 18.6 yuan lower than that of the freeze-drying group).

[0028] 3. Green and environmentally friendly process: The present invention uses deionized water as solvent in the extraction process, with no organic solvent residue. Compared with the existing process that partially uses ethanol extraction, it avoids the solvent recovery process, reduces pollutant emissions, and the extraction waste liquid can be recycled after simple treatment, increasing the water resource utilization rate by 50%, which meets the requirements of green production.

[0029] Third, the product has clear efficacy, is convenient to take, and is suitable for a wide range of people.

[0030] 1. Fast and stable therapeutic effects: This invention extracts, concentrates, and enriches the effective components, allowing the product to be taken regularly and in measured amounts (recommended 1-2 times daily, 3g each time). Compared to traditional Chinese herb tea made from dried *Xanthoceras sorbifolium* leaves (which has a low dissolution rate of effective components and slow onset of action), the antioxidant effect takes 7-14 days to take effect (comparative experiment: after 14 days of continuous use of this product, the serum SOD activity of the subjects increased by 28.3%, while the traditional dried tea group only increased by 10.5%). It also has an auxiliary effect in lowering uric acid. Clinical preliminary experiments have verified that after 30 days of continuous use, people with high uric acid levels experienced an average reduction of 12.7% in blood uric acid levels.

[0031] 2. Convenient to use and stable to store: This product is an instant solid granule, individually packaged in small sachets. No brewing equipment is needed; it dissolves in warm water, making it suitable for daily office work, travel, and other scenarios. Compared to the inconvenience of carrying and brewing traditional dried tea, its convenience is significantly improved. At the same time, the product has a low moisture content and good sealing properties, and its shelf life can reach 18 months under normal temperature and dry conditions, which is 50% more stable than traditional dried tea (shelf life of 6-12 months).

[0032] 3. Wide range of applicable groups: This product is non-toxic and has no side effects. It is low in calories and high in sweetness, making it suitable for daily antioxidant and anti-aging health care for ordinary healthy people. It is also suitable for special groups such as middle-aged and elderly people, people with high uric acid, and people with high blood lipids and blood sugar. Compared with existing single-target tea drinks (such as mulberry leaf tea which is only suitable for lowering blood sugar), the applicable group is expanded to healthy and sub-healthy groups of all ages, and the market potential is greater.

[0033] IV. Significant Industrial Value, Promoting High-Value Utilization of Xanthoceras sorbifolium Resources

[0034] 1. Expanding the value chain of the *Xanthoceras sorbifolium* industry: Current technologies in the *Xanthoceras sorbifolium* industry mostly focus on fruit processing, with leaves often being discarded or used in a crude manner, resulting in a resource utilization rate of less than 20%. This invention uses *Xanthoceras sorbifolium* leaves as raw material to develop high-value-added instant tea, increasing the resource utilization rate of *Xanthoceras sorbifolium* leaves to over 85%, driving the development of the entire *Xanthoceras sorbifolium* industry chain, and increasing the income of *Xanthoceras sorbifolium* growers by an additional 1200-1500 yuan per mu, resulting in significant economic benefits.

[0035] 2. Driving sustainable development of regional industries: The process of this invention is simple and easy to industrialize, which can drive the transformation and upgrading of local food processing enterprises, form a complete industrial chain of "raw material planting - deep processing - product sales", solve local employment problems, and promote the integrated development of modern agriculture and specialty fruit industry. Compared with the existing scattered processing model of *Vernicia fordii* leaves, the industrial concentration is increased and the sustainable development capacity is enhanced.

[0036] In summary, this invention breaks through existing technological bottlenecks in terms of formulation, process, product, and industry. It is innovative, practical, economical, and environmentally friendly, with strong product competitiveness and broad market application prospects. At the same time, it provides a brand-new approach for the high-value development of Xanthoceras sorbifolium leaf resources.

[0037] Secondly, as supporting evidence of the inventiveness of this invention, it is also reflected in the following important aspects:

[0038] (1) The expected benefits and commercial value of the technical solution of this invention after transformation are as follows:

[0039] This invention achieves high-value utilization of Xanthoceras sorbifolium leaves. Currently, Xanthoceras sorbifolium leaves are mostly discarded as planting byproducts or used only for coarsely processed tea bags, resulting in extremely low added value. This invention, through an integrated process of efficient extraction, flavor improvement, and instant dissolution molding, transforms Xanthoceras sorbifolium leaves into portable, easily soluble, and delicious functional solid tea beverages, increasing product added value by more than 10 times. From a market perspective, this product aligns with the development trend of the health industry and can be positioned as a "medicinal and edible" functional tea beverage, covering multiple consumption scenarios such as office workers, middle-aged and elderly health enthusiasts, and outdoor enthusiasts. It is estimated that after large-scale production, the annual production capacity can reach 100 tons, with an annual output value exceeding 10 million yuan and a return on investment of no less than 30%. Furthermore, this process is compatible with the development of instant tea beverages from other medicinal and edible plant leaves, possessing technological reuse value and enabling further expansion of product lines and enhanced market competitiveness.

[0040] Technology transfer can drive the large-scale development of the *Xanthoceras sorbifolium* planting industry, especially in arid and semi-arid regions suitable for its growth. Furthermore, this product uses natural *Xanthoceras sorbifolium* leaves as raw material, with no added preservatives or artificial colors. It can replace some traditional beverages that are high in sugar and additives, promoting a healthy beverage consumption concept and possessing positive social value.

[0041] (2) The technical solution of this invention fills a technical gap in the industry both domestically and internationally:

[0042] A review of publicly available patent literature, academic papers, and industry reports both domestically and internationally reveals that current research on the application of *Xanthoceras sorbifolium* leaves primarily focuses on the extraction and separation of active ingredients or the preparation of traditional tea bags. No publicly reported mature technical solutions for instant solid tea beverages made from *Xanthoceras sorbifolium* leaves have been found. Internationally, research on *Xanthoceras sorbifolium* is limited in Europe and the United States, with no related technical records for instant tea beverages. Domestically, existing technologies either focus solely on laboratory extraction methods for active ingredients such as flavonoids and polyphenols from *Xanthoceras sorbifolium* leaves without achieving industrialization, or produce tea beverages with defects such as poor solubility, low retention of active ingredients, and bitter taste, failing to meet market demand for high-quality instant tea beverages. This invention, through a combined process of direct boiling water extraction, vacuum low-temperature concentration, spray drying, and wet granulation, achieves the first industrial-scale preparation of instant solid tea beverages made from *Xanthoceras sorbifolium* leaves, filling the technological gap in the high-value transformation of *Xanthoceras sorbifolium* leaves into instant tea beverages both domestically and internationally.

[0043] (3) The technical solution of the present invention solves a technical problem that people have long wanted to solve but have never been able to solve successfully:

[0044] For a long time, the industry has faced two core technical challenges in the process of industrializing the *Vernicia fordii* leaf tea beverage, which it has been eager to solve but has not yet achieved a substantial breakthrough:

[0045] ① The challenge of poor water solubility and insufficient instant solubility of active ingredients: Flavonoids, polyphenols, and other active ingredients often bind to cell walls. During the extraction of these active ingredients, proteins in the leaves can hinder the extraction process because they bind to the target components or form gel-like substances, thus reducing extraction efficiency. Soaking followed by extraction results in low dissolution rates, and the prepared solid tea beverages are prone to sedimentation and stratification when brewed with cold / warm water, failing to meet instant solubility standards and thus hindering consumers' demand for convenient drinking.

[0046] ② The challenge of masking bitterness and harmonizing flavor: The leaves of the Chinese privet contain tannins, which bring a distinct bitter taste. Traditional processing methods mask this by adding a large amount of sucrose, which does not conform to the development trend of healthy beverages. On the other hand, using natural ingredients to mask the taste makes it difficult to balance the relationship between taste and the preservation of active ingredients.

[0047] This invention addresses the aforementioned challenges by using boiling water treatment to disrupt cell structures, including cell walls and protein networks, significantly improving the water solubility of active ingredients and thus increasing the extraction efficiency of effective components. Simultaneously, it innovatively introduces a flavor-enhancing system based on mogrosides, effectively masking bitterness without adding sucrose, thus solving a long-standing technical bottleneck that has hindered the industrialization of *Xanthoceras sorbifolium* leaf tea. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the raw material and formulation of a highly antioxidant-active *Sapindus mukorossi* leaf instant solid tea, provided by an embodiment of the present invention.

[0049] Figure 2 This is a flowchart of a method for preparing a highly antioxidant-active *Sapindus mukorossi* leaf instant solid tea according to an embodiment of the present invention.

[0050] Figure 3 The different methods used to extract flavonoid content from *Sapindus mukorossi* leaves;

[0051] Figure 4 It is the ability of *Sapindus mukorossi* leaf instant solid tea to scavenge DPPH free radicals;

[0052] Figure 5 It is the ability of *Sapindus mukorossi* leaf instant solid tea to scavenge ABTS free radicals. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0054] This invention is not a simple superposition of single processes such as extraction, drying, or granulation of Xanthoceras sorbifolium leaves. Instead, it focuses on the stable release, enrichment, and rapid dissolution of thermosensitive and easily oxidized active ingredients such as polyphenols and flavonoids from Xanthoceras sorbifolium leaves. It holistically designs the process sequence, parameter ranges, and material state transitions of each step, thereby forming a continuous preparation mechanism with inherent synergy. Its core lies in the multi-dimensional synergistic regulation of "temperature—solvent—phase—particle structure," ensuring that the active substances remain in a controlled transfer and stable state throughout the entire process, avoiding the activity decay and functional failure problems commonly found in existing technologies.

[0055] In the pretreatment and reflux extraction stages, *Xanthoceras sorbifolium* leaves are directly immersed in a boiling water system for reflux extraction. High-temperature, short-time reflux creates a stable solvent circulation environment, which on the one hand disrupts the cell wall structure and rapidly releases water-soluble antioxidants, and on the other hand avoids component degradation caused by prolonged high-temperature soaking. The secondary extraction is not a simple repetition, but rather a targeted extraction of residual active ingredients by reducing the material-to-liquid ratio and shortening the extraction time. This ensures that the two filtrates have complementary compositional profiles, providing a homogeneous active substance basis for subsequent concentration.

[0056] In the low-temperature vacuum concentration stage, a specific combination of temperature and vacuum allows for rapid removal of moisture at low boiling points, avoiding polyphenol oxidation and structural damage caused by high temperatures during atmospheric pressure concentration. Simultaneously, the specific gravity of the extract is precisely controlled within a specific range, allowing the extract to transition from a liquid to a semi-solid state, providing a stable phase basis for subsequent drying and compounding. This concentration state is not arbitrarily set but directly affects the porosity and solubility of the powder after spray or vacuum drying.

[0057] After drying and pulverizing, maltodextrin and flavoring agents are introduced into the compounding stage. Their role is not simply to fill or flavor, but to reduce the exposure of active ingredients to air and moisture by forming an encapsulation and dispersion system, while simultaneously improving powder flowability and subsequent granulation stability. During the wetting process for preparing the soft material, a specific proportion of edible alcohol is used as a wetting agent, allowing for controlled adhesion of the powder surface without swelling, effectively preventing premature dissolution or migration of active substances caused by the aqueous medium.

[0058] During wet granulation, drying, and sieving, precise control of the particle size range ensures that the resulting granules possess both porosity and mechanical strength, enabling rapid disintegration and effective dissolution upon brewing, while maintaining morphological stability during storage and transportation. Final packaging and standardization steps are then completed based on this structure, achieving a stable balance between antioxidant activity, rapid solubility, and sensory quality in the finished product.

[0059] This invention achieves continuous and synergistic control of the antioxidant active ingredients in *Xanthoceras sorbifolium* leaves from raw material release and stable enrichment to end-use by integrating the process conditions of extraction, concentration, drying, compounding and granulation. Its technical effect cannot be expected by arbitrary combination of existing technologies, and it has significant integrity and indivisibility.

[0060] like Figure 1 As shown, this embodiment of the invention provides a highly antioxidant-active instant solid tea made from *Xanthoceras sorbifolium* leaves. The specific raw materials and proportions of this solid tea include:

[0061] Main ingredient: Sapindus mukorossi leaves, harvested from June to August each year, washed and dried for later use;

[0062] Excipients, compound additives:

[0063] Flavoring agents: mogrosides or steviol glycosides, 0.5%–2.0%;

[0064] Filler: Maltodextrin, added at 10%–30% of the content of *Sapindus mukorossi* leaf extract powder;

[0065] Wetting agent: 95% edible alcohol.

[0066] like Figure 2 As shown, this embodiment of the invention provides a method for preparing the highly antioxidant-active *Xanthoceras sorbifolium* leaf instant solid tea, the method comprising:

[0067] S1: Add the leaves of *Sapindus mukorossi* directly into boiling water at a material-to-liquid ratio of 1:20 to 1:40 g / mL, and reflux for 60 min;

[0068] S2: Filter while hot and collect the filtrate; the filter residue can be extracted a second time, with a material-to-liquid ratio of 1:10 to 1:20, for 30 minutes.

[0069] S3: The combined filtrate is vacuum concentrated to a thick paste under the conditions of 55-60℃ and 0.075-0.085MPa, with a specific gravity of 1.18-1.20, to obtain the concentrate;

[0070] S4: The concentrate is dried in a vacuum drying oven at 75℃;

[0071] S5: The dry extract is pulverized and then compounded, with maltodextrin added at 10%–30% and mogrosides added at 1%–3%.

[0072] S6: Spray the prepared powder with a wetting agent to make a soft material. The spraying amount is 20% to 30% of the powder. After passing through a 10-mesh sieve, put it in an oven to dry for 60 minutes. After taking it out, place it in a dry place to air dry to room temperature and then sieve it again. Take the particles below 20 mesh and above 40 mesh for later use. Adjust the sealing temperature of the automatic granule packaging machine to 125℃. Package each bag with a net content of 3.5g ± 0.5g to obtain the finished product.

[0073] This invention does not achieve enhanced antioxidant activity through the selection of a single raw material or a single processing method. Instead, it constructs a preparation system with a clear synergistic mechanism, focusing on the continuous technical goal of the complete release, mild enrichment, stable solidification, and rapid resolidification of easily oxidized active ingredients such as polyphenols and flavonoids in the leaves of Xanthoceras sorbifolium.

[0074] First, a boiling water reflux method with a limited solid-liquid ratio is used in the extraction stage. Through a gradient extraction process—one stage with a higher solid-liquid ratio and two stages with a lower ratio—the water-soluble antioxidants in *Xanthoceras sorbifolium* leaves are fully dissolved in a short time, while avoiding structural degradation caused by prolonged high-temperature treatment. This two-stage extraction is not a simple repetitive operation, but rather achieves the synergistic extraction of highly polar and moderately polar active substances by controlling the differences in solute diffusion driving forces, providing a balanced component basis for subsequent enrichment.

[0075] Secondly, during the vacuum concentration stage, a temperature range of 55–60°C and a specific vacuum level are defined to remove the solvent at a lower boiling point, avoiding oxygen exposure and heat-induced oxidation reactions during atmospheric pressure concentration. Simultaneously, by controlling the final specific gravity, the active ingredients are kept in a stable high-solids dispersion system, creating conditions for subsequent drying to form a continuous solid structure. These concentration parameters are not chosen in isolation but are linked to the subsequent drying temperature in a thermal process.

[0076] Furthermore, under vacuum drying conditions at 75°C, the concentrate is rapidly converted into a dry extract, allowing the antioxidant components to move from a liquid-phase confined environment into a low-water-content solid system, significantly reducing the oxidation reaction kinetic rate. This drying method, in synergy with the aforementioned vacuum concentration, creates a dual stable environment of low oxygen and low water activity, thus inhibiting activity decay from a mechanistic perspective.

[0077] In the compounding stage, by introducing a specific proportion of maltodextrin, on the one hand, the active ingredients of Xanthoceras sorbifolium leaves are physically encapsulated and spatially isolated, and on the other hand, the powder flowability and instant solubility are improved. Combined with low doses of mogroside or steviol glycoside for flavoring, the highly active antioxidant components can achieve sensory balance without relying on a high sugar system, thereby avoiding the negative impact of traditional sweetening systems on activity stability.

[0078] Finally, by controlling the granulation process with alcohol wetting and limiting the particle size range, the finished product forms a dense but rapidly disintegrating granular structure, which reduces moisture absorption and oxygen contact during storage and rapidly releases active substances during brewing, achieving a synergistic balance between "storage stability" and "instant solubility".

[0079] This invention constructs an overall technical solution that inhibits oxidation reactions, maintains high antioxidant activity, and takes into account rapid solubility by synergistically combining multiple technical features such as extraction, concentration, drying, compounding, and granulation in terms of process sequence, physical state, and chemical environment. It is significantly different from the simple superposition of single parameters or single excipients in the prior art and has outstanding substantive features and significant progress.

[0080] The core of this invention lies in optimizing the formula ratio and preparation process to achieve a synergistic improvement in the retention rate of effective components, palatability, and production efficiency of Xanthoceras sorbifolium leaf instant solid tea. The specific implementation method is as follows:

[0081] I. Preparation of Raw Materials and Equipment

[0082] (a) Raw material specifications

[0083] 1. Sapindus mukorossi leaves: Select Sapindus mukorossi leaves that are recognized by the National Health Commission in 2023 as directly edible (Announcement No. 5 of 2023). After harvesting, rinse with clean water to remove impurities, place in a 40℃ forced-air drying oven to dry until the moisture content is ≤8%, seal and store in a cool and dry place for later use, ensuring that the initial content of flavonoids is ≥7mg / g.

[0084] 2. Monk fruit glycosides: purity ≥98%, meeting food-grade standards, with a complete triterpenoid skeleton structure, sweetness 300 times that of sucrose, no obvious off-odor, purchased from Mengzhou Huaxing Biochemical Co., Ltd.

[0085] 3. Excipients: Deionized water (conductivity ≤10μ S / cm), used as extraction solvent; maltodextrin (DE value 20-25, food grade), used to adjust product formability, the amount added does not affect the core efficacy and taste.

[0086] (II) Equipment List

[0087] Vacuum low-temperature concentrator (temperature 55~60℃, vacuum degree 0.075~0.085MPa), spray dryer (adjustable inlet / outlet air temperature, atomization pressure 0.3-0.5MPa), high-speed pulverizer (speed ≥8000r / min), forced-air drying oven (temperature range 20-120℃), high-performance liquid chromatograph (HPLC, for the detection of flavonoid content), ultraviolet spectrophotometer (for the detection of antioxidant activity), electronic balance (accuracy 0.001g).

[0088] II. Implementation Steps

[0089] This embodiment represents the optimal preparation scheme for instant solid tea made from Xanthoceras sorbifolium leaves. The formula and process parameters were determined through response surface methodology optimization. The specific steps are as follows:

[0090] Step 1: Raw material pretreatment

[0091] Take 1 kg of prepared Xanthoceras sorbifolium leaves, add 20 L of boiling deionized water (material-to-liquid ratio 1:20, mass-to-volume ratio), stir well, and reflux for 30 min.

[0092] Step 2: Filtration and Clarification

[0093] After extraction, the coarse residue is first removed by filtration through a 200-mesh filter cloth, and the filtrate is collected. Then, the filtrate is centrifuged (5000 r / min, 10 min) to remove fine impurities, and the supernatant is taken as the extract. Finally, a plate and frame filter is used for further clarification to ensure that the extract is free of suspended particles and is ready for use.

[0094] Step 3: Vacuum low-temperature concentration

[0095] The clarified extract was transferred to a vacuum low-temperature concentration device, and the temperature was set to 55~60℃ and the vacuum degree to 0.075~0.085MPa. The extract was concentrated until the volume was 1 / 10 of the original volume (i.e., 2L) to obtain the concentrated extract of Xanthoceras sorbifolium leaves.

[0096] Step 4: Drying

[0097] The concentrated liquid was transferred to a spray dryer, and the optimized process parameters were: inlet air temperature 180℃, outlet air temperature 80℃, atomization pressure 0.4MPa, and feed rate 15mL / min. After drying, the solid powder was collected, which is the extract of Xanthoceras sorbifolium leaf.

[0098] Step 5: Granulation

[0099] The leaf extract powder of *Sapindus mukorossi*, maltodextrin, and mogrosides are thoroughly mixed, sprayed with a certain concentration of ethanol to moisten and granulate, and the humidity is adjusted so that it can be formed into a ball by hand and easily dispersed by light pressure. After forming a soft material, it is extruded and granulated through a 10-mesh screen, placed in an oven to dry at a certain temperature, and then sieved through a standardized process to obtain the finished product.

[0100] Step 6: Post-processing of finished products

[0101] The obtained solid particles were tested and found to have a moisture content of 4.7% and a DPPH free radical scavenging rate of 89.2%. They were then individually packaged in small bags (3g per bag), sealed, and stored in a dry environment at room temperature, with a shelf life of up to 18 months.

[0102] Example 1

[0103] Leaves of *Xanthoceras sorbifolium* harvested from June to August were selected, washed, and dried as raw materials. The processed leaves were then refluxed in boiling water at a ratio of 1:30 for 60 minutes, allowing the leaf cell walls to swell and rupture under hot water conditions, fully releasing water-soluble antioxidant active ingredients into the liquid phase. After hot filtration, the filter residue was subjected to a second extraction at a ratio of 1:15 for 30 minutes to replenish any remaining active ingredients with limited diffusion. The combined extracts were concentrated at 55°C and a vacuum of 0.08 MPa until a specific gravity of 1.19 was achieved. The extract was then dried under negative pressure at 75°C to form a dry extract, which was subsequently compounded and granulated. The resulting product maintained stable antioxidant activity during storage and dissolved rapidly upon reconstitution, indicating that a continuous low-oxygen, low-water-activity pathway significantly protects the activity.

[0104] Example 2

[0105] Based on Example 1, the material-to-liquid ratio for the first extraction was adjusted to 1:20 to enhance the initial diffusion driving force and preferentially release highly polar antioxidant components; the second extraction was still used to compensate for moderately polar components. This staged release mechanism resulted in a more balanced composition of antioxidants in the extract. Subsequent concentration and drying parameters remained consistent, and the resulting dry extract formed a dense granular structure after compounding. Experiments showed that this method can improve the overall retention rate of active ingredients without extending the processing time, demonstrating the synergistic relationship between the extraction stage parameters and the subsequent solidification stage.

[0106] Example 3

[0107] By controlling the final specific gravity at 1.18 during the concentration stage and shortening the high-temperature liquid residence time, the antioxidant components enter the low-reaction-rate solid-state formation stage earlier. Subsequently, the same drying and granulation process was used, and the resulting product exhibited a lower activity decay rate under accelerated storage conditions, indicating that the connection between the concentration endpoint and the drying stage on the time scale is of great significance for inhibiting oxidation reactions.

[0108] Example 4

[0109] Increasing the proportion of carrier material during the compounding process allows the antioxidant components in the dry extract to form a more pronounced physical encapsulation structure. The resulting granules, after drying, exhibit a uniform internal pore distribution, effectively extending the oxygen diffusion path. Test results show that this structure significantly reduces activity loss during long-term storage, while still enabling rapid disintegration and release under hot water dissolution conditions. This demonstrates that stability and rapid solubility are not contradictory but rather unified through structural design.

[0110] Example 5

[0111] In the granulation stage, the material is moistened into a soft mass and then sieved into granules. The particle size is controlled within the range of 10 to 40 mesh, ensuring that each granule possesses both sufficient mechanical strength and a good water contact area. This particle size structure makes the granules less prone to breakage during packaging and transportation. When brewed, water can quickly penetrate into the granules, causing them to disintegrate. This further demonstrates the crucial role of particle structure control in the overall technical solution.

[0112] Example 6

[0113] The above steps are completed in a single continuous process chain without prolonged intermediate exposure or transfer treatment, ensuring that the material remains under controlled oxygen conditions to complete its morphological transformation. The resulting instant solid tea maintains stable antioxidant activity under both room temperature storage and high-temperature brewing conditions, indicating that this technical solution does not rely on a single measure, but rather achieves systematic protection and utilization of the antioxidant activity of *Xanthoceras sorbifolium* leaves through the synergistic combination of multiple stages such as extraction, concentration, drying, compounding, and granulation in terms of physical state and chemical environment.

[0114] Evidence related to the technical effects obtained by the embodiments of the present invention.

[0115] (I) Core Technology Effects

[0116] 1: High antioxidant activity (core innovation of the invention)

[0117] DPPH working solution: Weigh 2.5 mg of DPPH standard, add anhydrous ethanol to dissolve and bring the volume to 100 mL, shake well in the dark to ensure complete dissolution, and set aside for later use.

[0118] Determination of DPPH free radical scavenging rate: Accurately weigh 1g of sample and dissolve it in 30mL of ethanol. Sonicate for 20min, collect the supernatant, repeat 3 times, and dilute to 200mL to obtain a 200μg / mL sample solution stock solution. Dilute to sample solutions with mass concentrations of 20, 40, 60, 80, 10, and 120μg / mL respectively. Accurately pipette 0.2mL of sample solutions with mass concentrations of 20, 40, 60, 80, 10, and 120μg / mL, add 1.8mL of 70% ethanol and 2mL of DPPH working solution respectively, mix well, react in the dark for 30min, and measure the absorbance at a wavelength of 517nm. Use an equal volume of extraction solvent instead of sample solution as a blank control group and measure the absorbance using the same method.

[0119]

[0120] In the formula: A0 is the absorbance value of the blank control; A is the absorbance value of the sample.

[0121] The scavenging effect of Xanthoceras sorbifolium leaf instant solid tea on ABTS free radicals

[0122] ABTS working solution: Accurately weigh the ABTS dilution solution: Weigh 200.0 mg of ABTS and 34.4 mg of potassium persulfate, dissolve in 50.0 mL of water, shake well, and let stand at room temperature in the dark for 24 hours to obtain the ABTS stock solution. Take an appropriate amount of the ABTS stock solution and dilute it with 95% ethanol until the absorbance value is within 0.70 ± 0.02 (visible region 734 nm) to obtain the ABTS dilution solution.

[0123] Determination of ABTS free radical scavenging rate: Accurately pipette 0.1 mL of sample solution with mass concentrations of 20, 40, 60, 80, 100, and 120 μg / mL, add 1.9 mL of 70% ethanol and 2 mL of ABTS working solution respectively, mix well, react in the dark for 6 min, and measure the absorbance at a wavelength of 734 nm. For the blank control group, use the same volume of extraction solvent instead of sample solution and measure the absorbance using the same method.

[0124]

[0125] As attached Figure 4The figure shows the changes in the DPPH free radical scavenging ability of *Xanthoceras sorbifolium* leaf instant solid tea under different mass concentrations. The horizontal axis represents the mass concentration (μg / mL) of the *Xanthoceras sorbifolium* leaf instant solid tea solution, and the vertical axis represents the DPPH free radical scavenging rate (%). The results show that the DPPH free radical scavenging rate increases significantly with increasing sample concentration. The scavenging rate increases significantly in the low concentration range; as the concentration further increases, the scavenging rate continues to increase, but the rate of increase tends to level off, indicating that this instant solid tea has a stable and sustained DPPH free radical scavenging ability, reflecting its good antioxidant activity.

[0126] As attached Figure 5 As shown in the figure, the scavenging ability of *Xanthoceras sorbifolium* leaf instant solid tea against ABTS free radicals under different mass concentrations is presented. The horizontal axis represents the mass concentration of the sample solution (μg / mL), and the vertical axis represents the ABTS free radical scavenging rate (%). The figure shows that with the gradual increase of sample concentration, the ABTS free radical scavenging rate exhibits a relatively stable and continuous upward trend without significant fluctuations, indicating that this instant solid tea has a good concentration-response relationship to ABTS free radicals. (See attached figure.) Figure 4 and attached Figure 5 It can be seen that the prepared Xanthoceras sorbifolium leaf instant solid tea exhibits good scavenging effects in both commonly used free radical systems, demonstrating the stability and reliability of its antioxidant properties.

[0127] IC 50 It is the mass concentration of the sample when the free radical scavenging rate reaches 50%, IC50. 50 The smaller the concentration, the better the antioxidant effect of the sample, and vice versa. The DPPH free radical scavenging rate of *Xanthoceras sorbifolium* leaf instant solid tea showed a significant positive correlation with the mass concentration. As the mass concentration increased from 0.50 μg / mL to 5.00 μg / mL, the scavenging rate steadily increased from 18.60% to 74.00%. Similarly, the ABTS free radical scavenging rate of *Xanthoceras sorbifolium* leaf instant solid tea steadily increased from 7.70% to 73.60% as the mass concentration increased from 0.50 μg / mL to 5.00 μg / mL. This indicates that *Xanthoceras sorbifolium* leaf instant solid tea possesses significant antioxidant activity.

[0128] (ii) The core technology is effective and palatable (a core indicator of marketization)

[0129] Evaluation methods

[0130] A professional sensory evaluation team of 10 people (including food R&D personnel and ordinary consumers, according to the GB / T 10221-2022 sensory evaluation standard) was formed to score the finished product (after reconstitution, 3g / 100mL warm water) from four dimensions: color, aroma, taste and mouthfeel (out of 10 points), and the average score was taken.

[0131] Sensory evaluation evidence

[0132] Key conclusions

[0133] By harmonizing the natural sweetness of mogrosides and combining it with the masking effect of maltodextrin on bitterness, the finished product completely solves the problem of prominent bitterness after compounding and granulating the Xanthoceras sorbifolium leaf extract, and the overall palatability is improved by 28.6% compared with the unflavored control group.

[0134] (III) Core Technology Effects: Functional Synergy and Ingredient Compliance

[0135] 1. Evidence from quantitative detection of functional components (supporting evidence for auxiliary functions)

[0136] All functional excipients in the finished product meet national / industry quality requirements, and the effective components are fully retained. The test results are as follows:

[0137] Vitamin C: Content ≥2.9mg / g (raw material purity ≥99%, retention rate during compounding / drying process ≥96%), with no oxidative loss.

[0138] 2. Evidence of ingredient compliance

[0139] All raw materials used in the finished product are food-grade / new resource food ingredients, complying with the requirements of the "National Food Safety Standard for the Use of Food Additives" (GB 2760-2014), and contain no prohibited ingredients. Testing has confirmed that:

[0140] Heavy metals (lead, arsenic, mercury, cadmium): all below the limits in GB 2762-2022 (lead ≤ 0.1 mg / kg, arsenic ≤ 0.05 mg / kg).

[0141] Microorganisms (total bacterial count, coliform bacteria, mold): all meet the microbial limit requirements of GB / T 29602-2013 "Solid Beverages";

[0142] Food additives: The amount of mogroside used is lower than the maximum usage in GB 2760-2014, and no preservatives, artificial colors, or artificial sweeteners are added.

[0143] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a Xanthoceras sorbifolia Bunge leaf instant solid tea with high antioxidant activity, characterized in that, The method comprises the following steps performed sequentially: Aqueous phase reflux extraction was performed on the leaves of *Xanthoceras sorbifolium* to allow the water-soluble antioxidant active ingredients in the leaves to enter the liquid phase system; The extract was concentrated in a controlled manner under a low oxygen negative pressure environment, so that the antioxidant active ingredients formed a high solids dispersion system under low water activity conditions. The concentrate is dried under limited temperature and negative pressure conditions, so that the antioxidant active ingredients are transformed from a liquid-bound system into a low-reactivity solid system. The dried extract is compounded and granulated to suppress oxygen diffusion and improve resolvation efficiency through physical encapsulation and structural densification. This allows for the simultaneous maintenance of antioxidant activity and improvement of rapid solubility within the same process chain.

2. The production method according to claim 1, characterized by, The aqueous phase reflux extraction adopts a two-stage extraction method. The first stage extraction is used to establish the main release channel of antioxidant active ingredients, and the second stage extraction is used to supplement the release of residual active ingredients with limited diffusion, so as to maintain a synergistic balance of antioxidant substances in the extract.

3. The preparation method according to claim 1, characterized in that, The controlled concentration was carried out at a temperature of 55 to 60 degrees Celsius and a vacuum of 0.075 to 0.085 MPa, with the specific gravity of the concentrate reaching 1.18 to 1.20 as the endpoint control condition to reduce the probability of thermal oxidation reaction.

4. A preparation system for realizing the synergistic promotion of the stability and instant performance of the antioxidant activity of Xanthoceras sorbifolia Bunge leaves, characterized in that, The system includes an extraction module, a negative pressure concentration module, a low-oxygen drying module, and a compound granulation module connected in sequence. Each module continuously regulates the physical state of the materials and oxygen exposure conditions, enabling the antioxidant active ingredients to undergo metamorphic transformation along a low-oxygen, low-water-activity pathway within the system. This results in a stable solid structure that is rapidly re-dissolved and released during use.

5. The preparation system according to claim 4, characterized in that The negative pressure concentration module and the low oxygen drying module are connected in terms of temperature setting, so that the thermal process of the material is continuous and without high temperature abrupt changes, in order to avoid damage to the structure of antioxidant active ingredients.

6. The preparation system according to claim 4, characterized in that, The compound granulation module introduces porous carrier material to form a spatial isolation structure for antioxidant active ingredients, thereby reducing the oxygen diffusion rate during solid-state storage.

7. A Xanthoceras sorbifolia Bunge leaf instant solid tea with high antioxidant activity, characterized in that, The solid tea is formed by solidifying the antioxidant active ingredients of *Sapindus mukorossi* leaves in a low water activity solid matrix. This solid matrix, through physical encapsulation and densification of the particle structure, ensures that the antioxidant active ingredients are in a low-reaction-rate environment during storage and are rapidly released upon reconstitution. Its antioxidant properties and rapid solubility originate from the same structural synergistic mechanism.

8. The instant solid tea of claim 7, wherein, The solid matrix contains a carrier component to improve dissolution kinetics, causing the particles to disintegrate rapidly rather than dissolve slowly upon contact in water.

9. The instant solid tea according to claim 7, characterized in that, The particle size of the solid tea particles is controlled within the range of 10 to 40 mesh to achieve a structural balance between storage stability and brewing release efficiency.

10. The instant solid tea according to claim 7, characterized in that, The antioxidant active ingredients maintain their antioxidant activity by reducing water content and oxygen contact area in the solid matrix.

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