NFC tea juice and preparation method and application thereof

Abstract

The application discloses NFC tea juice and a preparation method and application thereof, and belongs to the technical field of food processing. Fresh tea leaves are used as raw materials, and the NFC tea juice is prepared through the following steps: bubble cleaning, color protection by spraying liquid, superfine crushing, high-shear enzymatic liquefaction and astringency removal, solid-liquid separation, ultra-high temperature instant sterilization and aseptic filling in sequence; and dietary fiber powder is prepared through ultra-micro crushing and drying of wet tea residues; the color protection liquid is composed of citric acid, vitamin C and sodium phytate, and can effectively inhibit browning; the composite enzyme is composed of pectinase, cellulase and tannase, and realizes cell wall crushing, liquefaction and astringency removal under high-shear conditions. The application omits traditional tea making, drying and concentration processes, reduces energy consumption, and the obtained tea juice is bright in color, fresh and sweet in taste, and complete in natural aroma, and does not need external additives, and can be applied to the fields of pure tea beverages, flavored tea, milk tea and baked food, etc.

Description

Technical Field

[0001] This invention relates to the field of food processing technology, specifically to an NFC tea juice, its preparation method, and its application. Background Technology

[0002] Traditional tea beverage production mainly relies on finished dried tea leaves, tea polyphenol powder, or tea paste. Typical processes include dry tea extraction, multi-stage filtration, vacuum concentration, spray drying to produce powder, followed by compounding, sterilization, and bottling. This process has several drawbacks in actual production. First, it is lengthy and energy-intensive, requiring energy-intensive steps such as drying, storage, rehydration, extraction, concentration, and spray drying. The processing cycle is long, and the natural aroma of tea is severely lost in multiple stages of processing, resulting in high production costs. Second, it has low resource utilization. Traditional hot water extraction can only dissolve 30%-40% of the effective components of tea, leaving a large amount of protein, polysaccharides, dietary fiber, and fat-soluble active ingredients in the tea residue, causing waste of raw materials and environmental pollution. Third, it distorts the flavor. Dry tea is prone to oxidation and flavor deterioration during long-term storage, and finished tea beverages need to rely on flavorings, sweeteners, and other additives to modify the taste. Fourth, the astringency removal process is delayed. Traditional processes often use masking agents or physical adsorption to remove the bitterness of the tea soup, which not only increases the processing steps but also easily introduces exogenous additives, affecting the natural properties of the product.

[0003] Therefore, how to eliminate intermediate steps such as tea making, drying, extraction, and concentration, directly utilize fresh tea leaves, achieve waste-free processing of all components, and solve problems such as browning, bitterness, and sedimentation caused by direct processing of fresh leaves, thereby improving the quality of tea beverages, has significant industrial value. Summary of the Invention

[0004] In view of this, the present invention provides an NFC tea juice and its preparation method and application, realizing direct processing of fresh leaves, efficient deastringency removal, full utilization of tea and preservation of flavor.

[0005] The technical solution provided by this invention is as follows: In a first aspect, the present invention provides a method for preparing NFC tea juice, comprising the following steps: S1. Bubbling Cleaning: Put the tea leaves into the bubbling cleaning machine for cleaning; S2. Color protection with spray: Spray the washed tea leaves with color protection solution for 1-3 minutes; S3. Ultrafine grinding: Mix tea leaves with soft water and grind them to a particle size of 50-200 micrometers to obtain tea slurry; S4. High-shear enzymatic hydrolysis liquefaction and deastringency removal: Add a compound enzyme to the tea slurry and carry out enzymatic hydrolysis in a high-shear reactor; S5. Solid-liquid separation: The slurry after enzymatic hydrolysis is separated by pressure filtration to obtain NFC tea juice initial liquid and wet tea residue; S6. Sterilization and storage of tea juice: The initial NFC tea juice is sterilized at ultra-high temperature for 4-10 seconds at a temperature of 135-140℃. It is then cooled to 4-8℃ and aseptically filled to obtain the finished NFC tea juice.

[0006] Preferably, the method further includes step S7. Utilization of tea residue: the wet tea residue is ultra-finely pulverized and dried to obtain dietary fiber powder.

[0007] Preferably, the temperature of the bubbling cleaning in step S1 is 10-15℃, and the cleaning time is 5-10 minutes.

[0008] Preferably, the color-protecting liquid in step S2 is made from the following components: citric acid, vitamin C, sodium phytate, and water; The composition includes citric acid (0.1%-0.5% by mass), vitamin C (0.05%-0.2% by mass), sodium phytate (0.02%-0.1% by mass), and the remainder is water.

[0009] Preferably, in step S3, the mass ratio of tea leaves to soft water is 1:(1-3).

[0010] Preferably, the compound enzyme in step S4 is composed of pectinase, cellulase and tanninase, with a mass ratio of (1-2):(1-2):(2-3); the amount of compound enzyme added is 0.1%-0.5% of the tea mass.

[0011] Preferably, in step S4, the shearing speed is 3000-6000 rpm, the enzymatic hydrolysis temperature is 45-55℃, and the time is 30-90 minutes.

[0012] Secondly, the present invention provides an NFC tea juice prepared by the method described in any of the preceding claims.

[0013] Thirdly, the present invention provides the application of NFC tea juice as described above in the preparation of tea beverages or baked goods.

[0014] The beneficial effects of this invention are as follows: This invention uses fresh tea leaves directly as raw material, omitting high-energy-consuming intermediate steps such as tea making, drying, rehydration, extraction, concentration, and spray drying in traditional processes. The processing flow is greatly shortened, the overall energy consumption is reduced, and the production cost is significantly reduced, while preserving the natural aroma and active ingredients of fresh leaves to the greatest extent.

[0015] This invention employs a low-temperature spraying treatment with a color-protecting solution composed of citric acid, vitamin C, and sodium phytate. This effectively inhibits enzymatic browning and oxidative discoloration of fresh leaves, ensuring the finished NFC tea juice retains its natural, bright color and resists browning and sedimentation during long-term storage. Simultaneously, ultrafine grinding and high-shear enzymatic hydrolysis thoroughly break down the cell walls of the tea leaves. Utilizing the synergistic effect of high-shear intensification and complex enzymes, ester-type catechins are efficiently hydrolyzed, achieving liquefaction and deastringency removal. The resulting tea juice, after UHT sterilization and aseptic filling, exhibits no stratification or sedimentation during long-term storage, offering a fresh, mellow, and sweet taste with no bitter aftertaste, eliminating the need for masking agents. This tea juice can be used directly as a pure tea beverage or in flavored teas, milk teas, baked goods, and various other applications. Furthermore, the tea residue, after ultrafine grinding and drying, is processed into high-dietary-fiber powder, achieving zero-waste utilization of all tea components. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only a part of the embodiments of this invention, not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or as recommended by the manufacturer. Unless otherwise stated, percentages and parts are weight percentages and parts by weight.

[0017] Unless otherwise specified, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should be noted that the terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the exemplary embodiments of this application.

[0018] The technical solution of this invention: a method for preparing NFC tea juice. S1. Bubble cleaning: Put fresh tea leaves into a bubble cleaning machine and clean them with micro-nano bubble water. The cleaning water temperature is controlled at 10-15℃ and the cleaning time is 5-10 minutes. After cleaning, drain the water. The fresh tea leaves are preferably fresh tea leaves or one bud and two or three leaves, and are processed within 4 hours after picking to avoid composting and fermentation. S2. Color protection with liquid leaching: The washed tea leaves are placed on a mesh conveyor belt and sprayed evenly with a color-protecting liquid. The color-protecting liquid is a compound of 0.1%-0.5% citric acid, 0.05%-0.2% vitamin C and 0.02%-0.1% sodium phytate by mass concentration. The spraying time is 1-3 minutes. After the treatment, a low-temperature air shower is used to remove residual droplets from the surface of the tea leaves. S3. Ultrafine grinding: Mix tea leaves and soft water at a mass ratio of 1:(1-3), and then pulverize them into ultrafine powder using a colloid mill or homogenizer until the particle size is 50-200 micrometers to obtain tea slurry. S4. High-shear enzymatic hydrolysis liquefaction and deastringency: The tea slurry is pumped into a high-shear reactor, and a compound enzyme is added for enzymatic hydrolysis. The shear speed is controlled at 3000-6000 rpm, the enzymatic hydrolysis temperature is 45-55℃, and the time is 30-90 minutes. The compound enzyme is composed of pectinase, cellulase and tanninase in a mass ratio of (1-2):(1-2):(2-3), and its addition amount is 0.1%-0.5% of the tea mass.

[0019] S5. Solid-liquid separation: The enzymatically hydrolyzed slurry is subjected to solid-liquid separation using a plate and frame filter press or a horizontal screw centrifuge to obtain NFC tea juice initial liquid and wet tea residue. S6. Sterilization and storage of tea juice: The initial NFC tea juice is sterilized at ultra-high temperature for 4-10 seconds at a temperature of 135-140℃. After sterilization, it is rapidly cooled to 4-8℃ and then aseptically filled to obtain the finished NFC tea juice. S7. Utilization of tea dregs: The separated wet tea residue is processed by ultra-fine grinding and hot air drying to obtain dietary fiber powder, which can be used as a food ingredient.

[0020] The following are specific embodiments of the present invention.

[0021] Example 1 A method for preparing NFC tea juice includes the following steps: S1. Bubble cleaning: Take 10kg of fresh Fuding white tea leaves, put them into a bubbling washing machine, wash them at 10℃ for 8 minutes, and drain the water after washing. S2. Color protection with liquid leaching: After cleaning, place the tea leaves on a mesh conveyor belt, spray the color-protecting liquid evenly, treat for 2 minutes, and then use a low-temperature air shower to remove residual droplets from the surface of the tea leaves. The color-protecting solution is a compound of 0.3% citric acid, 0.1% vitamin C and 0.05% sodium phytate; S3. Ultrafine grinding: Add 20 kg of soft water to the tea leaves and pulverize them using a colloid mill until the particle size is 100 micrometers to obtain tea slurry; S4. High-shear enzymatic hydrolysis liquefaction and deastringency: The tea slurry was pumped into a high-shear reactor, and a compound enzyme was added for enzymatic hydrolysis. The shearing speed was 4500 rpm, the enzymatic hydrolysis temperature was 50℃, and the time was 60 minutes. The compound enzyme is composed of pectinase, cellulase and tanninase in a mass ratio of 2:1:2, and its addition amount is 0.5% of the tea mass.

[0022] S5. Solid-liquid separation: The enzymatically hydrolyzed slurry was subjected to solid-liquid separation using a plate and frame filter press to obtain NFC tea juice initial liquid and wet tea residue; S6. Sterilization and storage of tea juice: The initial NFC tea juice is sterilized at an ultra-high temperature of 137°C for 6 seconds. After sterilization, it is rapidly cooled to 6°C and then aseptically filled to obtain the finished NFC tea juice. S7. Utilization of tea dregs: The separated wet tea residue was subjected to ultra-fine grinding and hot air drying to obtain dietary fiber powder.

[0023] The tea juice obtained in this embodiment is bright green in color, with 4.5% soluble solids, 3200 mg / L of tea polyphenols, and a degradation rate of 89.2% for ester-type catechins. It has a fresh and refreshing taste without astringency. The tea residue yields 1.8 kg of dietary fiber powder with a total dietary fiber content of 72%.

[0024] Example 2 A method for preparing NFC tea juice includes the following steps: S1. Bubble cleaning: Take 10kg of fresh Buddha's Hand tea leaves from Yongchun, Fujian, put them into a bubbling washing machine, wash them at 12℃ for 10 minutes, and drain the water after washing. S2. Color protection with liquid leaching: After cleaning, place the tea leaves on a mesh conveyor belt, spray the color-protecting liquid evenly, treat for 3 minutes, and then use a low-temperature air shower to remove residual droplets from the surface of the tea leaves. The color-protecting solution is a compound of 0.3% citric acid, 0.1% vitamin C and 0.05% sodium phytate; S3. Ultrafine grinding: Add 25 kg of soft water to the tea leaves and pulverize them with a colloid mill until the particle size is 120 micrometers to obtain tea slurry; S4. High-shear enzymatic hydrolysis liquefaction and deastringency: The tea slurry was pumped into a high-shear reactor, and a compound enzyme was added for enzymatic hydrolysis. The shearing speed was 5000 rpm, the enzymatic hydrolysis temperature was 52℃, and the time was 75 minutes. The compound enzyme is composed of pectinase, cellulase and tanninase in a mass ratio of 2:1:2, and its addition amount is 0.5% of the tea mass.

[0025] S5. Solid-liquid separation: The enzymatically hydrolyzed slurry was subjected to solid-liquid separation using a plate and frame filter press to obtain NFC tea juice initial liquid and wet tea residue; S6. Sterilization and storage of tea juice: The initial NFC tea juice is sterilized at an ultra-high temperature of 130°C for 5 seconds. After sterilization, it is rapidly cooled to 5°C and then aseptically filled to obtain the finished NFC tea juice. S7. Utilization of tea dregs: The separated wet tea residue was subjected to ultra-fine grinding and hot air drying to obtain dietary fiber powder.

[0026] The tea juice obtained in this embodiment has a bright yellow-green color, with a unique bergamot and pear aroma, 5.2% soluble solids, a 91.5% degradation rate of ester-type catechins, a mellow and smooth taste, and a distinct sweet aftertaste; 2.0 kg of dietary fiber powder was obtained from the tea residue, with a total dietary fiber content of 70%.

[0027] Example 3 A method for preparing NFC tea juice includes the following steps: S1. Bubble cleaning: Take 10kg of fresh Anxi Tieguanyin leaves, put them into a bubble washing machine, wash them at 10℃ for 8 minutes, and drain the water after washing. S2. Color protection with liquid leaching: After cleaning, place the tea leaves on a mesh conveyor belt, spray the color-protecting liquid evenly, treat for 3 minutes, and then use a low-temperature air shower to remove residual droplets from the surface of the tea leaves. The color-protecting solution is a compound of 0.4% citric acid, 0.15% vitamin C and 0.08% sodium phytate; S3. Ultrafine grinding: Add 20 kg of soft water to the tea leaves and pulverize them with a colloid mill until the particle size is 90 micrometers to obtain tea slurry; S4. High-shear enzymatic hydrolysis liquefaction and deastringency: The tea slurry was pumped into a high-shear reactor, and a compound enzyme was added for enzymatic hydrolysis. The shearing speed was 4800 rpm, the enzymatic hydrolysis temperature was 48℃, and the time was 70 minutes. The compound enzyme is composed of pectinase, cellulase and tanninase in a mass ratio of 1.5:1:2, and its addition amount is 0.5% of the tea mass.

[0028] S5. Solid-liquid separation: The enzymatically hydrolyzed slurry was subjected to solid-liquid separation using a plate and frame filter press to obtain NFC tea juice initial liquid and wet tea residue; S6. Sterilization and storage of tea juice: The initial NFC tea juice is sterilized at an ultra-high temperature of 132°C for 7 seconds. After sterilization, it is rapidly cooled to 8°C and then aseptically filled to obtain the finished NFC tea juice. S7. Utilization of tea dregs: The separated wet tea residue was subjected to ultra-fine grinding and hot air drying to obtain dietary fiber powder.

[0029] The tea liquor obtained in this embodiment is golden and clear, with a typical orchid fragrance and Tieguanyin flavor. The tea polyphenol content is 3450mg / L, the degradation rate of ester-type catechins is 88.7%, the taste is fresh and refreshing, without the bitter aftertaste of traditional Tieguanyin tea, and the floral fragrance is prominent. 1.9kg of dietary fiber powder was obtained from the tea residue, with a total dietary fiber content of 73%.

[0030] Example 4 A method for preparing NFC tea juice includes the following steps: S1. Bubble cleaning: Take 10 kg of fresh cinnamon leaves from Wuyi Mountain, put them into a bubble washing machine and wash them at 15℃ for 10 minutes. After washing, drain the water. S2. Color protection with liquid leaching: After cleaning, the tea leaves are placed on a mesh conveyor belt and sprayed evenly with color-protecting liquid for 4 minutes. After treatment, low-temperature air shower is used to remove residual droplets from the surface of the tea leaves. The color-protecting solution is a compound of 0.35% citric acid, 0.12% vitamin C and 0.06% sodium phytate; S3. Ultrafine grinding: Add 22 kg of soft water to the tea leaves and pulverize them with a colloid mill until the particle size is 110 micrometers to obtain tea slurry; S4. High-shear enzymatic hydrolysis liquefaction and deastringency: The tea slurry was pumped into a high-shear reactor, and a compound enzyme was added for enzymatic hydrolysis. The shearing speed was 5500 rpm, the enzymatic hydrolysis temperature was 53℃, and the time was 85 minutes. The compound enzyme is composed of pectinase, cellulase and tanninase in a mass ratio of 2:1.5:2.5, and its addition amount is 0.4% of the tea mass.

[0031] S5. Solid-liquid separation: The enzymatically hydrolyzed slurry was subjected to solid-liquid separation using a plate and frame filter press to obtain NFC tea juice initial liquid and wet tea residue; S6. Sterilization and storage of tea juice: The initial NFC tea juice is sterilized at an ultra-high temperature of 134°C for 5 seconds. After sterilization, it is rapidly cooled to 7°C and then aseptically filled to obtain the finished NFC tea juice. S7. Utilization of tea dregs: The separated wet tea residue was subjected to ultra-fine grinding and hot air drying to obtain dietary fiber powder.

[0032] The tea juice obtained in this embodiment is bright orange-red in color, retains the unique cinnamon and fruity aroma of the cinnamon variety, has a degradation rate of 93.2% for ester-type catechins, significantly reduces bitterness and astringency, enhances mellowness, and has a distinct rocky flavor; 2.1 kg of dietary fiber powder was obtained from the tea residue, with a total dietary fiber content of 68%.

[0033] Example 5 A method for preparing NFC tea juice includes the following steps: S1. Bubble cleaning: Take 500kg of fresh Anxi Tieguanyin leaves, put them into a bubble washing machine, and wash them at 10℃ for 8 minutes. After washing, drain the water. S2. Color protection with liquid leaching: After cleaning, place the tea leaves on a mesh conveyor belt, spray the color-protecting liquid evenly, treat for 3 minutes, and then use a low-temperature air shower to remove residual droplets from the surface of the tea leaves. The color-protecting solution is a compound of 0.4% citric acid, 0.15% vitamin C and 0.08% sodium phytate; S3. Ultrafine grinding: Add 1000 kg of soft water to the tea leaves and pulverize them with a colloid mill until the particle size is 90 micrometers to obtain tea slurry; S4. High-shear enzymatic hydrolysis liquefaction and deastringency: The tea slurry was pumped into a high-shear reactor, and a compound enzyme was added for enzymatic hydrolysis. The shearing speed was 4800 rpm, the enzymatic hydrolysis temperature was 48℃, and the time was 70 minutes. The compound enzyme is composed of pectinase, cellulase and tanninase in a mass ratio of 1.5:1:2, and its addition amount is 0.5% of the tea mass.

[0034] S5. Solid-liquid separation: The enzymatically hydrolyzed slurry was subjected to solid-liquid separation using a plate and frame filter press to obtain NFC tea juice initial liquid and wet tea residue; S6. Sterilization and storage of tea juice: The initial NFC tea juice is sterilized at an ultra-high temperature of 132°C for 7 seconds. After sterilization, it is rapidly cooled to 8°C and then aseptically filled to obtain the finished NFC tea juice. S7. Utilization of tea dregs: The separated wet tea residue is subjected to ultra-fine grinding and hot air drying until the moisture content is below 8% to obtain dietary fiber powder.

[0035] The dietary fiber powder was added to bread at a ratio of 8% to replace an equal amount of high-gluten flour to make high-fiber tea-flavored bread. Sensory evaluation showed that the tea aroma was natural and the texture was soft.

[0036] Comparative Example A method for preparing NFC tea juice includes the following steps: S1. Preprocessing: Take 10kg of fresh Anxi Tieguanyin tea leaves and process them sequentially through fixation, rolling, and drying to obtain the finished dried tea leaves. S2. Extraction: Soak the dried tea leaves in 95℃ hot water for 30 minutes to obtain a tea infusion mixture; S3. Centrifugation: The tea liquor mixture is centrifuged to remove solid impurities such as tea leaves; S4. Filtering: The supernatant after centrifugation is filtered through multiple stages to further remove fine impurities, yielding the initial tea juice. S6. Concentrated: The initial tea liquid is concentrated under vacuum to increase the concentration of the tea soup; S7. Sterilization: The concentrated tea juice is sterilized and then bottled to obtain the finished tea juice.

[0037] The total processing time for this comparative example exceeded 48 hours, the yield of tea polyphenols was only 42% of the total phenols in fresh leaves, the tea soup had a distinctly bitter taste, requiring the addition of cyclodextrin to mask it, and it lacked the tender green color and fresh aroma of natural fresh leaves.

[0038] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for preparing NFC tea juice, characterized in that, Includes the following steps: S1. Bubbling Cleaning: Put the tea leaves into the bubbling cleaning machine for cleaning; S2. Color protection with spray: Spray the washed tea leaves with color protection solution for 1-3 minutes; S3. Ultrafine grinding: Mix tea leaves with soft water and grind them to a particle size of 50-200 micrometers to obtain tea slurry; S4. High-shear enzymatic hydrolysis liquefaction and deastringency removal: Add a compound enzyme to the tea slurry and carry out enzymatic hydrolysis in a high-shear reactor; S5. Solid-liquid separation: The slurry after enzymatic hydrolysis is separated by pressure filtration to obtain NFC tea juice initial liquid and wet tea residue; S6. Sterilization and storage of tea juice: The initial NFC tea juice is sterilized at ultra-high temperature for 4-10 seconds at a temperature of 135-140℃. It is then cooled to 4-8℃ and aseptically filled to obtain the finished NFC tea juice.

2. The method for preparing NFC tea juice according to claim 1, characterized in that, It also includes step S7. Utilization of tea residue: The wet tea residue is ultra-finely pulverized and dried to obtain dietary fiber powder.

3. The method for preparing NFC tea juice according to claim 1, characterized in that, In step S1, the temperature for bubbling cleaning is 10-15℃, and the cleaning time is 5-10 minutes.

4. The method for preparing NFC tea juice according to claim 1, characterized in that, The color-protecting solution in step S2 is made from the following components: citric acid, vitamin C, sodium phytate, and water; The composition includes citric acid (0.1%-0.5% by mass), vitamin C (0.05%-0.2% by mass), sodium phytate (0.02%-0.1% by mass), and the remainder is water.

5. The method for preparing NFC tea juice according to claim 1, characterized in that, In step S3, the mass ratio of tea leaves to soft water is 1:(1-3).

6. The method for preparing NFC tea juice according to claim 1, characterized in that, In step S4, the compound enzyme consists of pectinase, cellulase and tanninase in a mass ratio of (1-2):(1-2):(2-3); the amount of compound enzyme added is 0.1%-0.5% of the tea mass.

7. The method for preparing NFC tea juice according to claim 1, characterized in that, In step S4, the shearing speed is 3000-6000 rpm, the enzymatic hydrolysis temperature is 45-55℃, and the time is 30-90 minutes.

8. An NFC tea juice, characterized in that, It is prepared by the method for preparing NFC tea juice as described in any one of claims 1-7.

9. The application of the NFC tea juice as described in claim 8 in the preparation of tea beverages or baked goods.