Preparation method of eucommia young tree bark tea

Abstract

The application provides a preparation method of eucommia ulmoides young tree bark tea, and belongs to the technical field of functional tea beverage preparation. The method comprises the following steps: 1) after eucommia ulmoides young tree bark is wilted and cut, steam explosion treatment is performed to obtain broken glue bark; 2) after the composite microbial inoculant is inoculated into the broken glue bark, the inoculant is stacked and fermented for 90-140 h; and 3) after the fermentation is completed, drying, post-ripening and aging are performed to obtain eucommia ulmoides young tree bark tea. The eucommia ulmoides young tree bark is used as a raw material, steam explosion treatment and fermentation treatment are combined, and finally, a complete eucommia ulmoides young bark tea preparation process is established. The preparation method not only realizes efficient utilization of eucommia ulmoides young bark resources, widens the processing way of eucommia ulmoides resources, solves the problems of low utilization rate and low added value of eucommia ulmoides rough bark, but also enriches the types of eucommia ulmoides functional tea products, promotes the transformation and upgrading of the eucommia ulmoides industry to the direction of refinement and high added value, and has important theoretical research significance and practical application value.

Description

Technical Field

[0001] This invention belongs to the field of functional tea beverage production technology, and in particular relates to a method for producing Eucommia ulmoides bark tea. Background Technology

[0002] Eucommia ulmoides ( Eucommia ulmoides Eucommia ulmoides (Oliv.) is a perennial deciduous tree belonging to the Eucommia genus of the Eucommiaceae family. It is the only remaining single-species relict tree species in central my country after the Quaternary glacial period. It is listed as a national second-class protected plant and is known as a "living fossil plant" (Du Hongyan, Du Qingxin. The basis, problems and countermeasures for the high-quality development of my country's Eucommia ulmoides industry [J]. Economic Forest Research, 2020, 38(1): 1-10.). As a traditional and precious Chinese medicinal material and a unique economic forest tree species, Eucommia ulmoides has extremely high comprehensive utilization value. Its roots, bark, leaves, flowers, fruits and wood all contain rich functional components and have important application prospects in the fields of medicine, food and chemical industry.

[0003] Eucommia bark is one of its core medicinal parts, rich in various active medicinal ingredients such as pinoresinol diglucoside, chlorogenic acid, and total flavonoids. It has significant effects on lowering blood pressure, blood lipids, and blood sugar, as well as anti-inflammatory, antioxidant, liver and kidney protection, and inhibiting tumor cell proliferation. It is an important raw material for developing functional foods and medicines.

[0004] The traditional tea processing technology mainly includes four core steps: withering, fixation, rolling, and drying. Its advantages lie in its mature technology, simple operation, good preservation of the raw material's inherent flavor, and suitability for large-scale production. However, it also has drawbacks such as a long processing cycle, insufficient dissolution of active ingredients from the raw materials, easy loss of some heat-sensitive components, and limited product functionality. With the continuous expansion of the market demand for functional tea products, Eucommia tea, as a new type of functional tea beverage, has gradually attracted consumer attention. Currently, there are numerous research reports on the preparation of Eucommia tea using Eucommia leaves and male flowers, and related products (Eucommia male flower tea and Eucommia leaf tea) have been commercialized and achieved good economic benefits. However, there are no reports on the preparation of Eucommia tea using the bark of young Eucommia trees. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a method for producing Eucommia ulmoides bark tea. Using Eucommia ulmoides bark as raw material, and combining steam explosion treatment and fermentation treatment, a complete process flow for preparing Eucommia ulmoides bark tea is finally established. This method not only realizes the efficient utilization of Eucommia ulmoides bark resources and broadens the processing channels of Eucommia ulmoides resources, but also solves the current problems of low utilization rate and low added value of Eucommia ulmoides bark processing. At the same time, it also enriches the categories of functional tea products of Eucommia ulmoides and promotes the transformation and upgrading of the Eucommia ulmoides industry towards refinement and high added value. It has important theoretical research significance and practical application value.

[0006] This invention provides a method for preparing Eucommia ulmoides bark tea, comprising the following steps: 1) After the bark of young Eucommia trees is withered and cut, it is steam-exploded to obtain broken bark; 2) After inoculating the compound microbial agent onto the broken bark, pile it up and ferment for 90-140 hours; 3) After fermentation, the bark of young Eucommia trees is dried and aged to obtain Eucommia ulmoides bark tea; Step 2) During the fermentation process, the pile should be turned over when the core temperature is ≥52℃; The bark of the Eucommia ulmoides saplings is that of one-year-old Eucommia ulmoides saplings.

[0007] Preferably, before the steam explosion treatment in step 1), the bark of the young Eucommia ulmoides tree is sprayed with a catalyst, wherein the catalyst is 2.5%~3.5% dilute hydrochloric acid; and the moisture content of the bark of the young Eucommia ulmoides tree is 25%~35%.

[0008] Preferably, the steam pressure of the steam explosion treatment is 1.9~2.0 MPa, and the pressure stabilization time is 182~183 s.

[0009] Preferably, the compound microbial agent in step 2) includes *Lactobacillus plantarum*, *Saccharomyces cerevisiae*, and *Aspergillus niger*; the effective viable count ratio of *Lactobacillus plantarum*, *Saccharomyces cerevisiae*, and *Aspergillus niger* is (5~7):(2~4):1, and the total viable count of the compound microbial agent is ≥1.0×10¹. 0 CFU / g; the inoculation amount of the compound microbial agent is 0.5~1% of the raw material mass.

[0010] Preferably, in step 2), the moisture content of the broken bark is adjusted to 45%~55% before inoculation with the compound microbial agent.

[0011] Preferably, the fermentation environment temperature in step 2) is 28~32℃, and the relative humidity of the fermentation is 85%~90%.

[0012] Preferably, the drying in step 3) includes three stages: initial drying, tempering, and final drying; the initial drying temperature is 60~65℃ and the time is 20~30min; the tempering temperature is 22~27℃ and the time is 1~2h; the final drying temperature is 50~55℃ and the time is 2~3h.

[0013] Preferably, the pressing is performed before the post-ripening and aging in step 3); the temperature of the post-ripening and aging is 24~26℃, the relative humidity of the post-ripening and aging is 60%~70%, and the post-ripening and aging time is 3~6 months.

[0014] Preferably, the bark of the young Eucommia ulmoides trees is collected from spring to early summer.

[0015] This invention provides a method for producing Eucommia ulmoides bark tea using the aforementioned method.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention uses the young bark of one-year-old Eucommia ulmoides branches as the research object. Compared with the rough bark of Eucommia ulmoides, this raw material has advantages such as thinner thickness, softer texture, lower degree of lignification, higher content of active ingredients, more delicate taste, and lower processing difficulty. Moreover, the content of core active ingredients such as pinoresinol diglucoside and total flavonoids in the young bark is 20% to 30% higher than that in the rough bark.

[0017] This invention is the first to combine steam explosion treatment with fermentation in the preparation of Eucommia ulmoides bark tea. Steam explosion treatment efficiently disrupts the eucommia ulmoides fiber structure, significantly increasing the dissolution rate of functional components and laying the foundation for the smooth progress of subsequent fermentation processes and improved product quality. The synergistic effect of steam explosion treatment and microbial enzymatic hydrolysis successfully breaks down the eucommia ulmoides fiber barrier, resulting in a significantly higher hot water extraction rate of core functional components such as pinoresinol diglucoside and genipinic acid compared to traditional direct slicing and brewing, greatly improving raw material utilization efficiency and product functionality.

[0018] The production method of this invention completely transforms the raw, grassy taste through directional fermentation and post-aging of compound microbial agents, making it mellow, sweet, and with a long aftertaste, forming a stable, mellow, and unique tea aroma and taste; thus transforming the bark of young Eucommia ulmoides trees from a medicinal raw material into a high-grade tea beverage with a unique flavor and charm.

[0019] Furthermore, this invention replaces the traditional natural "sweating" with quantitative inoculation and temperature- and humidity-controlled fermentation, and replaces simple one-time drying with gradient drying and post-ripening. The entire production method of this invention has clearly defined parameters, controllable cycle, and stable quality, and has the capability for industrial-scale production and quality traceability.

[0020] This invention transforms Eucommia bark, which originally had low economic value, into a high-end specialty tea product with unique flavor and health benefits, thus expanding the development direction of the Eucommia industry, creating new economic growth points, and generating significant social and economic benefits. Detailed Implementation

[0021] This invention provides a method for making Eucommia ulmoides bark tea, comprising the following steps: 1) after withering and cutting the bark of Eucommia ulmoides, steam explosion treatment is performed to obtain broken bark; 2) after inoculating the broken bark with a compound microbial agent, the bark is piled up and fermented for 90-140 hours; 3) after fermentation, the bark is dried and aged to obtain Eucommia ulmoides bark tea.

[0022] In this invention, the bark of young Eucommia ulmoides trees is first withered and cut, then subjected to steam explosion treatment to obtain degummed bark. Preferably, one-year-old young Eucommia ulmoides trees are selected, and the bark is collected from spring to early summer, as this period, after sap flow in spring and into early summer, is the accumulation period of active ingredients in Eucommia ulmoides. This invention preferably employs partial ring-shaped or strip-shaped peeling techniques to avoid damaging the xylem, preserve the cambium, and ensure tree regeneration. The thickness of the peeled bark is preferably 2-4 mm. After collecting the bark and before withering, the bark is preferably cleaned, preferably by quickly rinsing with running pure water to remove dirt and sand, and then draining. The withering temperature is 25-30℃, the relative humidity is 65%-75%, and the time is 18-24 hours; preferably, the bark is evenly spread on a bamboo sieve for withering, with a thickness preferably ≤3 cm. In this invention, the withering process is used to control the water loss rate to 15%~20%, making the skin soft and easy to cut later, and to initiate a mild enzymatic reaction, laying the foundation for the formation of flavor precursor substances.

[0023] After the withering process, the present invention performs a cutting process, preferably cutting the material into strips 2-3 mm wide and 10-15 mm long to increase the specific surface area.

[0024] In this invention, after the bark is cut, a steam explosion treatment is performed. Before the steam explosion treatment, the bark of the young Eucommia ulmoides tree is sprayed with a catalyst. The catalyst is preferably 2.5%~3.5% dilute hydrochloric acid, more preferably 2.9%~3.1% dilute hydrochloric acid, and most preferably 2.97% dilute hydrochloric acid. The humidity of the bark sprayed with the catalyst is preferably 25%~35%, more preferably 27%~33%, and most preferably 30%. The invention performs the steam explosion treatment 48 hours after spraying the bark with the catalyst. In this invention, the steam pressure for the steam explosion treatment is preferably 1.9~2.0 MPa, more preferably 1.94~1.98 MPa, and most preferably 1.96 MPa; the pressure stabilization time for the steam explosion is preferably 182~183 s, more preferably 182.25 s. This invention preferably uses a QBS-2008 steam explosion equipment (5L steam explosion solvent, Hebi Zhengdao Bioenergy Co., Ltd.). The steam explosion treatment described in this invention utilizes the physical tearing force generated by the instantaneous depressurization of high-temperature and high-pressure steam, which can strongly destroy the Eucommia ulmoides gum filament network and cell wall structure, forming a porous and loose material morphology, fundamentally solving the component dissolution barrier problem; dilute hydrochloric acid catalysis can further promote the partial hydrolysis of components such as hemicellulose, enhancing the cell wall breaking effect.

[0025] This invention involves obtaining broken bark, inoculating it with a compound microbial agent, and then piling and fermenting it for 90-140 hours. In this invention, the fermentation, through the action of microorganisms and enzymes, transforms the raw, astringent taste, produces flavor substances, and promotes the transformation and dissolution of functional components. Before inoculating the broken bark with the compound microbial agent, the moisture content is adjusted to 45%-55%, preferably 48%-52%, and more preferably 50%. The compound microbial agent preferably includes *Lactobacillus plantarum*, *Saccharomyces cerevisiae*, and *Aspergillus niger*; the ratio of effective viable bacteria of *Lactobacillus plantarum*, *Saccharomyces cerevisiae*, and *Aspergillus niger* is preferably (5-7):(2-4):1, more preferably 6:3:1; and the total viable bacteria count of the compound microbial agent is preferably ≥1.0 × 10¹. 0 CFU / g; all three strains were purchased from the China Industrial Microbial Culture Collection Center, Lactobacillus plantarum CICC accession number: CICC 24936, viable count ≥6.0 × 10⁻⁶. 9 Saccharomyces cerevisiae CICC accession number: CICC 31778, viable count ≥3.0 × 10⁻⁶ 9 Aspergillus niger enzyme CICC accession number CICC 40868, viable count ≥1.0 × 10⁻⁶ 9 In this invention, the inoculation amount of the compound microbial agent is preferably 0.5-1% of the raw material mass. In this invention, the compound microbial agent is preferably activated with warm water and sucrose and then uniformly sprayed for inoculation; in this invention, the temperature of the warm water is 30-40℃, and the amount of warm water is 8-12 times the mass of the compound microbial agent; the amount of sucrose is 8%-12% of the mass of the compound microbial agent. After inoculation with the compound microbial agent, the material is piled up; preferably, a regular trapezoidal pile with a base width of 1-1.4 meters, a top width of 0.7-0.9 meters, and a height of 40-50 centimeters is constructed; preferably, a digital temperature probe is inserted at the center of the pile. In this invention, the fermentation environment temperature is preferably 28-32℃, more preferably 29-31℃, and the relative humidity of the fermentation is 85%-90%. In this invention, the fermentation process involves turning the pile. Preferably, the first turning is performed when the core temperature reaches 50-55°C to release ammonia and replenish oxygen. The entire fermentation cycle is 90-140 hours, with 3-4 turnings preferred. The fermentation endpoint is preferably determined by the following conditions: the fermentation crust turns dark brown or blackish-brown, the grassy smell disappears, and a sweet, mellow, or slightly medicinal aroma emerges, with no sour or musty taste. The Eucommia ulmoides gum fibers further lose elasticity during fermentation, and the material's adhesiveness decreases. The fermentation conditions in this invention create a suitable environment for microbial proliferation and enzymatic reactions. Turning the pile regulates temperature, humidity, and oxygen, guiding the fermentation towards the desired flavor profile.

[0026] This invention obtains Eucommia ulmoides bark tea by drying and post-fermentation after the fermentation process. In this invention, the drying process includes three stages: initial drying, slow rehydration, and final drying. The initial drying temperature is preferably 60-65℃, more preferably 62-64℃, and the time is preferably 20-30 minutes, more preferably 22-28 minutes. The purpose of initial drying is to quickly stop fermentation enzyme activity and fix the color and initial aroma. The slow rehydration temperature is preferably 22-27℃, more preferably 23-26℃, and the time is preferably 1-2 hours. The purpose of slow rehydration is to allow internal moisture to diffuse outwards and balance the moisture content. The final drying temperature is preferably 50-55℃, more preferably 51-54℃, and the time is preferably 2-3 hours. The purpose of final drying is to reduce the moisture content to below 7%, and this stage helps to further develop flavor compounds.

[0027] To facilitate storage and flavor transformation, the post-ripening aging process described in this invention involves pressing the bark into cakes. Specifically, the dried Eucommia bark shreds are steam-softened for 30 seconds and then pressed into cakes using a mold. In this invention, the preferred post-ripening aging temperature is 24-26°C, the preferred relative humidity is 60%-70%, and the preferred aging time is 3-6 months. The post-ripening aging is preferably carried out in a clean, sealed environment, which helps dissipate any residual astringency and results in a more mellow aroma and flavor.

[0028] This invention provides Eucommia ulmoides bark tea prepared by the aforementioned method. The Eucommia ulmoides bark tea has the following characteristics: tightly rolled, dark brown, and oily dry tea leaves; a bright, deep red liquor; a unique aged medicinal aroma with a hint of jujube sweetness; a mellow, sweet taste with low astringency and a long-lasting aftertaste; and soft, evenly brownish-red tea leaves.

[0029] The Eucommia ulmoides bark tea described above benefits from steam explosion and fermentation processes, resulting in a significantly higher hot water extraction rate of core functional components (pinoresinol diglucoside, genipin glycoside, total flavonoids, etc.) compared to traditional sliced ​​tea. The fermentation process may convert some bound glycosides into free forms, potentially enhancing their biological activities such as regulating blood pressure and lipids, and providing antioxidant effects.

[0030] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0031] Example 1

[0032] 1. Raw materials and equipment

[0033] Raw materials: In early May 2024 (early summer), the bark of one-year-old, healthy Eucommia ulmoides saplings was selectively harvested from the Yuanyang Demonstration Base of the Institute of Economic Forestry, Chinese Academy of Forestry. The bark was peeled in strips without damaging the cork layer, preserving the complete cambium layer, and a total of 50 kg of fresh bark with a thickness of about 2 mm was obtained.

[0034] Main equipment: QBS-2008 steam explosion vessel (Hebi Zhengdao Bioenergy Co., Ltd., effective volume 5L).

[0035] SW-CJ-2FD type ultra-clean workbench (for bacterial agent activation and inoculation).

[0036] LRH-250 biochemical incubator (used to control the fermentation chamber environment).

[0037] CT-C-II type hot air circulating oven.

[0038] WSC-80 Tea Cake Press Machine.

[0039] 2. Specific Implementation Steps

[0040] (1) Cleaning and withering

[0041] Freshly harvested Eucommia bark is placed in a washing tank on an automated production line and rinsed for 2 minutes with purified water that meets national drinking water standards to remove surface mud and impurities. After rinsing, it is drained until there is no obvious dripping water.

[0042] The drained bark was evenly spread on a multi-layered stainless steel withering rack (each layer covered with a breathable bamboo sieve), with the thickness controlled at 2.5 cm. The withering rack was then placed in a temperature and humidity controlled withering chamber, with the ambient temperature set at 28°C (±2°C) and the relative humidity at 70% (±5%). Withering continued for 22 hours. Static relationship: The bark was evenly and thinly spread on a breathable carrier, in a constant temperature and humidity environment. Dynamic relationship and effect: Over 22 hours, the bark underwent continuous moisture exchange and slow oxidation with the flowing air. Results: At the end, the average water loss rate was measured to be 18%, the bark changed from stiff to soft, easy to cut, and emitted a fresh grassy smell, indicating that a mild enzymatic reaction had been initiated.

[0043] (2) Slicing and steam explosion to break the gel

[0044] Use a shredder to cut the withered Eucommia bark into uniform strips measuring 2.5 mm wide and 12 mm long. Prepare a 2.97% (by weight) dilute hydrochloric acid solution. Spray the solution evenly onto the Eucommia bark strips using a sprayer, stirring constantly until the overall moisture content of the strips reaches 30%. Place the moistened strips in a clean container and let them soak at room temperature for 48 hours.

[0045] The parameters for steam explosion were optimized through preliminary experiments. Response surface methodology was used in the early stages, selecting three factors: stabilization time, pressure, and concentration. Each factor was set with three levels. The lignocellulose content was used as an indicator. Preliminary experiments were conducted, and the results showed that the optimal steam explosion conditions for Eucommia bark were a stabilization time of 182.25 s, a pressure of 1.96 MPa, and a catalyst hydrochloric acid concentration of 2.97%.

[0046] The moistened fibrous fibers were loaded into the material hopper of the QBS-2008 steam explosion tank, filling it to 80% of the tank's effective volume. The hopper door was closed, and the equipment was started. Saturated steam was introduced into the tank, causing the pressure to steadily rise to 1.96 MPa and maintain this pressure for 182.25 seconds. Subsequently, the explosion valve was opened instantaneously, and the material was injected into the discharge tank through the spray pipe within milliseconds, resulting in a loose, flocculent, or short-fiber dark brown material that did not have a stringy feel when squeezed, indicating that the fibrous network and cell structure of Eucommia ulmoides had been effectively destroyed. The high-temperature, high-pressure steam rapidly penetrated into the interior of the material, causing the moisture to vaporize and the hemicellulose and other components to soften and hydrolyze under acid catalysis; upon instantaneous depressurization, the steam inside the material expanded rapidly, generating a strong shear force.

[0047] (3) Compound microbial agent stacking fermentation

[0048] Microbial agent activation: In a clean bench, take a compound probiotic agent (all three strains were purchased from the China Industrial Microbial Culture Collection Center, Lactobacillus plantarum CICC accession number: CICC 24936, viable count ≥ 6.0 × 10⁻⁶). 9 Saccharomyces cerevisiae CICC accession number: CICC 31778, viable count ≥3.0 × 10⁻⁶ 9 Aspergillus niger enzyme CICC accession number CICC 40868, viable count ≥1.0 × 10⁻⁶ 9 Premixed at a ratio of 6:3:1 for effective live bacteria, with a total live bacteria count ≥1.0 × 10¹ 0 Dissolve 500g of CFU / g in 5 liters of warm water at 35°C, add 50g of sucrose, stir gently, and let stand for 30 minutes to activate.

[0049] Inoculation and composting: Transfer the steam-exploded Eucommia bark filaments to the fermentation workshop, spray with purified water to adjust the moisture content to 50%. Spray the activated bacterial solution evenly onto the filaments using a sprayer and mix thoroughly. Compact the material into a regular trapezoidal pile with a base width of 1.2 meters, a top width of 0.8 meters, and a height of 45 centimeters. Insert a digital temperature probe at the center of the pile.

[0050] Fermentation Management: The fermentation workshop was shut down, and the ambient temperature was maintained at 30°C (±1°C) and the relative humidity at 88% (±2%) using air conditioning and humidification systems. After fermentation started, microbial activity generated heat, and the core temperature of the compost pile continued to rise. Under suitable temperature and humidity conditions, the complex microbial community (Lactobacillus plantarum, Saccharomyces cerevisiae, and Aspergillus niger) synergistically metabolized the nutrients in the material. When the core temperature reached 52°C, the first turning was performed, exchanging the positions of the inner and outer layers of material and appropriately breaking up any clumps. Thereafter, the compost pile was turned whenever the core temperature rose to 52°C again. The entire fermentation cycle lasted 120 hours, with a total of 4 turnings.

[0051] Endpoint Judgment: At the end of fermentation, the material's color changes from brown to a uniform dark brown; the grassy smell completely disappears, replaced by a rich, sweet, and mellow aroma with a faint medicinal fragrance, without any sour or rancid smell; when handled, the Eucommia ulmoides gum fibers completely lose their elasticity, and the material becomes loose and non-sticky. The fermentation process successfully removes the negative flavors of the raw materials and generates pleasant aromatic substances and potential active metabolites.

[0052] (4) Step drying

[0053] Spread the fermentation endpoint material thinly on a drying tray (thickness ≤ 1 cm) and send it into a hot air circulating oven.

[0054] Initial baking: Set the oven temperature to 63°C and bake for 25 minutes. Function and effect: Quickly evaporates surface moisture, completely stops enzyme activity and microbial activity, and "fixes" the color and basic aroma formed during fermentation.

[0055] Slow drying: Remove the initially dried material from the oven and spread it evenly on a clean bamboo mat. Let it air dry at room temperature (25°C) for 1.5 hours. Function and effect: Stopping external heating allows the internal moisture of the tea leaves to slowly migrate to the surface under the drive of the humidity gradient, achieving a balance of moisture inside and outside the leaves.

[0056] Sufficient drying: The tempered material is placed back into the oven and dried at a low temperature of 53°C for 150 minutes. After drying, samples are taken and the moisture content is measured to be 6.5%. Effects and benefits: Thorough drying under mild conditions, with slow moist heat action during this period, promotes further aging and fusion of aroma and flavor.

[0057] (5) Pressing and post-fermentation aging

[0058] After the Eucommia bark has been fully dried, place it in a steamer and steam it for 30 seconds to soften it completely. Quickly and quantitatively add the softened bark into the mold of a tea cake press machine that has been preheated to 80°C, and apply pressure to press it into a round tea cake.

[0059] The pressed tea cakes are placed in odorless, food-grade aluminum foil bags and sealed. They are then placed in a dedicated aging warehouse, where the temperature is maintained at a constant 25°C (±1°C) and the relative humidity at a constant 65% (±5%). Under these conditions, the tea is aged for 5 months. During this period, the residual trace amounts of low-boiling-point astringent components within the tea leaves continue to volatilize or transform. Various aroma substances and flavor components undergo complex non-enzymatic oxidation and polymerization reactions under minute changes in moisture and temperature. Upon brewing and tasting, the astringent taste of the aged tea cakes completely disappears, the aroma is more integrated, and the mellow, medicinal, and jujube-sweet aromas are prominent. The taste becomes extremely mellow, smooth, and sweet.

[0060] 3. Product Feature Analysis

[0061] Control group 1: Steam explosion only, steam explosion was carried out according to the optimized parameters of this invention (1.96 MPa, 182.25 s, 2.97% HCl), without inoculation and fermentation, and directly dried (initial drying → slow tempering → full drying); except for not inoculating and fermenting, all other operations were consistent with those described above (2. Specific implementation steps).

[0062] Control Group 2: Microbial fermentation only, without steam explosion treatment. The compound microbial agent (Lactobacillus plantarum:Saccharomyces cerevisiae:Aspergillus niger = 6:3:1) was directly inoculated according to the present invention, piled for fermentation, and then dried. Except for not performing steam explosion, all other operations were consistent with those described above (2. Specific Implementation Steps).

[0063] This invention utilizes a combination of steam explosion and microbial fermentation. First, steam explosion is performed, followed by inoculation with a compound microbial agent for fermentation. The complete process of this invention is: steam explosion → pile fermentation → stepped drying → pressing and post-fermentation aging. All operations are consistent with the above description (2. Specific implementation steps).

[0064] The Eucommia bark tea cakes prepared above were tested: Sensory quality: The dry tea cake is well-shaped, moderately compressed, and has a dark brown and oily color; take 5 grams of tea, brew with 150 ml of boiling water for 5 minutes, the tea soup is bright red and rich; the taste is mellow and sweet, smooth on the palate, without bitterness or astringency, and has a long aftertaste.

[0065] Table 1 Sensory Quality Analysis

[0066] Functional component content: determined according to national standard methods. Steam explosion combined with fermentation technology significantly increased the content of major functional components such as pinoresinol diglucoside and total flavonoids (Table 2).

[0067] The hot water extraction rates of pinoresinol diglucoside and total flavonoids in the product of this embodiment were determined by HPLC. The results showed that the extraction rates were significantly higher than those of the same batch of Eucommia ulmoides bark (directly brewed with boiling water) that had only undergone fermentation and steam explosion treatment. This further verified the technical effect of the present invention (Table 3).

[0068] Table 2 Content of Functional Components

[0069] Table 3 Leaching rates of main functional components

[0070] Note: The contents of pinoresinol diglucoside, genipinic acid, total flavonoids, and chlorogenic acid were determined by high performance liquid chromatography (HPLC).

[0071] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for producing Eucommia ulmoides bark tea, characterized in that, Includes the following steps: 1) After the bark of young Eucommia trees is withered and cut, it is steam-exploded to obtain broken bark; 2) After inoculating the compound microbial agent onto the broken bark, pile it up and ferment for 90-140 hours; 3) After fermentation, the bark of young Eucommia trees is dried and aged to obtain Eucommia ulmoides bark tea; The bark of the Eucommia ulmoides saplings is that of one-year-old Eucommia ulmoides saplings.

2. The manufacturing method according to claim 1, characterized in that, Step 1) Before the steam explosion treatment, the bark of the young Eucommia ulmoides tree is sprayed with a catalyst, wherein the catalyst is 2.5%~3.5% dilute hydrochloric acid; the moisture content of the bark of the young Eucommia ulmoides tree is 25%~35%.

3. The manufacturing method according to claim 2, characterized in that, The steam pressure for the steam explosion treatment is 1.9~2.0 MPa, and the pressure stabilization time is 182~183 s.

4. The manufacturing method according to claim 1, characterized in that, Step 2) The compound microbial agent includes Lactobacillus plantarum, Saccharomyces cerevisiae, and Aspergillus niger; the effective viable count ratio of Lactobacillus plantarum, Saccharomyces cerevisiae, and Aspergillus niger is (5~7):(2~4):1, and the total viable count of the compound microbial agent is ≥1.0×10¹. 0 CFU / g; the inoculum amount of the compound microbial agent is 0.5~1% of the raw material mass.

5. The manufacturing method according to claim 4, characterized in that, Step 2) Before inoculating the broken bark with the compound microbial agent, adjust the moisture content to 45%~55%.

6. The manufacturing method according to claim 4, characterized in that, Step 2) The fermentation environment temperature is 28~32℃, and the relative humidity of the fermentation is 85%~90%.

7. The manufacturing method according to claim 1, characterized in that, Step 3) The drying process includes three stages: initial drying, tempering, and final drying. The initial drying temperature is 60-65℃ and the time is 20-30 minutes. The tempering temperature is 22-27℃ and the time is 1-2 hours. The final drying temperature is 50-55℃ and the time is 2-3 hours.

8. The manufacturing method according to claim 1, characterized in that, Step 3) Pressing the cakes before the post-ripening and aging process; the post-ripening and aging temperature is 24~26℃, the relative humidity is 60%~70%, and the post-ripening and aging time is 3~6 months.

9. The manufacturing method according to claim 1, characterized in that, The bark of the young Eucommia trees was collected from spring to early summer.

10. Eucommia ulmoides bark tea prepared by the method according to any one of claims 1 to 9.

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