Low-bitterness sugarless tea beverage and preparation method thereof

Abstract

The application belongs to the technical field of tea beverage processing, and discloses a low-bitterness and low-sourness sugar-free tea beverage and a preparation method; tea soup is obtained by extracting jasmine Longjing, cassia, oolong, and Biluochun or dried tangerine peel Pu'er according to a material-liquid ratio of 1:15-1:25 in a warm and staggered manner, the dissolution of amino acids and non-ester catechins is not less than 60% of single-temperature extraction at 85°C, the dissolution of ester catechins and caffeine is not higher than 30%, the natural tea aroma extracted and emitted is collected and added back after sterilization and cooling of the tea soup, the total concentration of linalool and geraniol is 1:120-1:180 of the total concentration of free amino acids, and no sugar, sugar alcohol or sweetener is added. The application effectively reduces the dissolution of bitter and sour substances, retains fresh sweet components and natural aroma of the original tea, does not need to add exogenous sweetener and essence, is suitable for various tea bases, has strong controllability, has obvious natural and sweet aftertaste, and meets the consumption demand of healthy and sugar-free drinks.

Description

Technical Field

[0001] This invention belongs to the field of tea beverage processing technology, and in particular to a low-bitterness, sugar-free tea beverage and its preparation method. Background Technology

[0002] With the popularization of healthy consumption concepts, sugar-reduced and additive-free pure tea beverages have become the core growth track of the soft drink industry. Their application scenarios cover multiple fields such as daily meals, leisure hydration, and sports supplements. The core demand of the industry is to take into account the natural aroma, sweet aftertaste and low bitterness of the original tea without adding exogenous sweeteners and flavorings, while ensuring the flavor stability during the shelf life.

[0003] The current mainstream sugar-free tea production process mainly uses high-temperature single-temperature extraction. Its working principle involves using pure water at 80℃-95℃ to extract tea leaves in a single step. High temperature accelerates the dissolution rate of soluble components in the tea leaves, shortening the extraction cycle. This process is easy to implement, highly efficient, and cost-controllable, and is the core technology used in over 80% of commercially available sugar-free tea products. However, this process cannot distinguish the dissolution temperature ranges of different flavor compounds. Sweet amino acids and non-ester catechins dissolve in large quantities simultaneously with bitter ester catechins and caffeine. Furthermore, high temperatures destroy the original natural aroma components of the tea leaves, resulting in a generally prominent bitter taste in the final product. This necessitates the addition of exogenous flavorings or sweeteners to mask undesirable flavors, contradicting the natural properties of pure tea.

[0004] Another mainstream low-bitterness sugar-free tea preparation process is the enzymatic hydrolysis / adsorption post-treatment process. Its working principle involves adding tannins and glycosidases to break down ester-type catechins after tea extraction, or using macroporous adsorption resins for targeted adsorption to remove bitter substances. Erythritol and steviol glycosides are added to enhance sweetness. This process effectively reduces the bitterness of the finished product, catering to popular taste preferences. However, the enzymatic hydrolysis process alters the natural composition of the tea leaves, destroying the original tea's unique flavor. The adsorption process simultaneously loses beneficial components such as amino acids and aroma substances, resulting in a bland tea taste. Furthermore, added sugar substitutes generally have unpleasant aftertastes such as bitterness and metallic flavor, and consumers are increasingly concerned about the health effects of sugar substitutes. Additionally, aroma components are subject to secondary loss during the subsequent UHT high-temperature sterilization stage, and the added exogenous flavorings have poor compatibility with the original tea flavor, easily leading to aroma deterioration and browning of the tea during shelf life.

[0005] The two existing processes cannot simultaneously meet the demands for low bitterness, no additives, and natural flavor from the source. Subsequent remedial measures not only increase production costs but also damage the inherent quality of the original tea, failing to match consumers' demand for pure, natural, sugar-free tea. Corresponding technical solutions are urgently needed to address the aforementioned industry pain points. Summary of the Invention

[0006] In view of the shortcomings of existing sugar-free tea processing technology, such as high bitterness, the need to add exogenous sweeteners or flavorings, and serious loss of the natural flavor of the original tea, this invention provides a low-bitterness sugar-free tea beverage and its preparation method.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A low-bitterness, sugar-free tea beverage containing tea liquor and natural tea flavoring components; The tea infusion is obtained by selective extraction of raw tea at different temperatures and peak times. The raw tea is one of Jasmine Longjing, Osmanthus Oolong, Biluochun, or Chenpi Pu'er. The mass ratio of raw tea to extraction water is 1:15 to 1:25. The dissolution of amino acids and non-ester catechins in the tea infusion is not less than 60% of the dissolution of the corresponding components in the tea infusion obtained by single-temperature extraction at 85℃ for 10 minutes on the same mass of raw tea. The leaching of ester catechins and caffeine in the tea infusion is not more than 30% of the leaching of the corresponding components in the tea infusion obtained by single-temperature extraction at 85℃ for 10 minutes on the same mass of raw tea. The natural tea aroma components originate from the aroma released during the extraction process of the original tea. No additional exogenous aroma components are added to the tea beverage. The natural tea aroma components are added back to the tea infusion after the tea infusion is sterilized and cooled. The ratio of the total concentration of linalool and geraniol to the total concentration of free amino acids in the sugar-free tea beverage is 1:120 to 1:180. No additional sugars, sugar alcohols, or sweeteners are added to the sugar-free tea beverage, and the energy content is not higher than 17 kJ / 100 mL.

[0008] Furthermore, the tea infusion also contains pectin derived from dried tangerine peel and / or pectin hydrolysates.

[0009] Furthermore, the tea infusion also contains sodium ascorbate at a mass ratio of 0.01% to 0.05%.

[0010] Furthermore, the following steps are included: S1. Temperature-segmented extraction: Put the raw tea into a sealed extraction tank and first extract it at a low temperature of 15~25℃ pure water for 3~5 minutes. Then raise the temperature to 35~45℃ and extract it for 2~4 minutes. After raising the temperature to 35~45℃, take a sample every 1 minute to detect the concentration of ester catechins in the extract. When the increase in the concentration of ester catechins measured at three consecutive sampling points decreases in turn, it is determined that the extraction inflection point has been reached. The extraction is then terminated immediately, and the first tea infusion is obtained by filtration. S2. Aroma Collection and Temporary Storage: During the entire extraction process, the aroma escaping from the extraction tank is drawn out through a closed circulation system and collected by condensation at 0~6℃ to obtain aroma condensate. The aroma condensate is concentrated and mixed with the wall material solution, and the solid content is adjusted to 15%~25%. The mass ratio of core material to wall material is 1:3~1:5. Spray drying is performed to obtain microencapsulated natural tea aroma temporary storage. The average particle size of the microcapsules is 1~50μm. S3. Post-processing of tea liquor: After coarse filtration and fine filtration of the first brew, sodium ascorbate is added to the finely filtered tea liquor. The target content is 0.01%~0.05% by mass in the sterilized tea liquor. The tea liquor is then subjected to UHT ultra-high temperature instantaneous sterilization and cooled to 20~25℃. S4. Aroma Delay Refill: Under aseptic conditions, microencapsulated natural tea aroma is pre-dispersed in a small amount of sterile water to form a suspension, which is then added to the cooled tea soup at a preset concentration. After stirring evenly, the liquid surface is protected by nitrogen headspace and then aseptically filled to obtain the low-bitterness sugar-free tea beverage.

[0011] Furthermore, the concentration of ester-type catechins mentioned in S1 is monitored in real time using online near-infrared spectroscopy in conjunction with a chemometric model.

[0012] Furthermore, the wall material described in S2 is prepared by compounding maltodextrin and β-cyclodextrin in a mass ratio of 2:1.

[0013] Furthermore, in S2, the inlet air temperature of the spray drying process is 140~160℃, the outlet air temperature is 70~80℃, and the feed rate is 500~800mL / h, resulting in a microencapsulation rate of over 85% for the prepared natural tea aroma.

[0014] Furthermore, the UHT sterilization temperature described in S3 is 135~139℃, and the sterilization time is 4~6s.

[0015] Furthermore, the amount of sodium ascorbate added in S3 is 1.1 to 1.3 times the target content in the sterilized tea soup, and the target content is 0.01% to 0.05%.

[0016] Furthermore, in step S3, when the original tea is aged tangerine peel Pu-erh tea, before the UHT sterilization, pectinase is added to the finely filtered tea soup for enzymatic hydrolysis. The hydrolysis temperature is 30-35℃, the hydrolysis time is 10-15 minutes, and after the hydrolysis is completed, the temperature is raised to 90℃ to inactivate the enzyme for 5 minutes. After cooling to 20-25℃, the UHT sterilization is then carried out. The amount of pectinase added is 0.005%-0.01% of the mass of the tea soup.

[0017] The present invention has the following beneficial effects: This invention utilizes a phased extraction technology to extract sweet and aromatic components in stages based on the dissolution temperature characteristics of different flavor compounds in tea. Extraction is terminated promptly when bitter substances reach their dissolution inflection point, controlling the extraction amount of bitter substances such as ester-type catechins and caffeine from the source. This effectively solves the problem of excessive simultaneous dissolution of bitter and sweet components during single-temperature extraction in existing technologies, which requires post-processing such as enzymatic hydrolysis and adsorption or the addition of sweeteners to mask bitterness, thus destroying the natural flavor of the original tea. This invention preserves the original sweet and aromatic components of the tea without the need for any exogenous sugars, sugar alcohols, or sugar substitutes, aligning with the product positioning of sugar-free and low-calorie.

[0018] This invention employs a process route that involves capturing the natural aroma of raw tea in a closed extraction process, temporarily storing it in microcapsules, and delaying its re-addition after sterilization and cooling. This avoids the heat loss of natural aroma during the high-temperature extraction and UHT sterilization stages. At the same time, the microcapsule encapsulation structure can slow down the release rate of aroma components, effectively solving the problems of severe aroma loss of raw tea, the need to add exogenous flavorings to adjust the aroma, resulting in poor flavor compatibility with the raw tea, and easy deterioration of aroma during the shelf life in existing technologies. The finished product has a pure and natural aroma and significantly improved flavor stability.

[0019] This invention enhances the natural sweetness and lingering aftertaste of tea soup by regulating the ratio of characteristic aroma components in the added natural aroma to free amino acids in the tea soup. This leverages the synergistic effect of aroma and taste, effectively solving the problems of bland taste in existing sugar-free tea soups and unpleasant aftertastes from added sweeteners. The finished product has a harmonious and mellow taste, meeting consumers' flavor demands for pure, natural tea beverages. The process of this invention is adaptable to the processing of various mainstream pure tea varieties, such as Jasmine Longjing, Gui Fu Oolong, Biluochun, and Chenpi Pu'er, without requiring significant process adjustments for different tea types. Its strong adaptability allows it to cater to the taste preferences of diverse consumer groups, making it highly valuable for industry promotion. Attached Figure Description

[0020] Figure 1 This is a flowchart of a method for preparing a low-bitterness, sugar-free tea beverage proposed in this invention. Figure 2 This is a bar chart showing the comparison of the core performance of different samples proposed in this invention. Figure 3 This is a line graph showing the dissolution trend of bitter substances in the temperature-differential extraction process proposed in this invention. Figure 4 The image shows a radar chart of sensory evaluation for Embodiment 1 and a comparative example proposed in this invention. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] The raw tea described in this instruction manual includes tea raw materials that have undergone scenting, blending, or aging processing using tea leaves as a base, such as Jasmine Longjing, Osmanthus Oolong, Biluochun, and Aged Pu'er. All experimental and control groups used the following baseline conditions: the material-to-liquid ratio error did not exceed ±0.5, the stirring rate was 300 r / min, filtration used a 200-mesh filter cloth for coarse filtration and a 0.22 μm polyethersulfone microfiltration membrane for fine filtration, and high-performance liquid chromatography (HPLC) for determining catechin and caffeine content, ninhydrin colorimetric method for determining free amino acid content, headspace solid-phase microextraction-gas chromatography-mass spectrometry (HSP-GC-MS) for determining aroma components, and energy was calculated according to the methods specified in the "General Rules for Nutrition Labelling of Prepackaged Foods".

[0023] In this paper, the natural aroma retention rate is defined as follows: taking the same batch of raw tea as a benchmark, the raw tea is crushed and passed through a 40-mesh sieve. 1.0g of the raw tea is weighed and added to 10mL of pure water to make a homogenate. After equilibration at 60℃ for 10min, the total peak area of ​​the key aroma components (linalool, geraniol, nerolidol, β-ionone, jasmone, cedrol) is measured by headspace solid-phase microextraction-gas chromatography-mass spectrometry and used as the benchmark peak area. The total peak area of ​​the corresponding aroma components in the finished tea infusion was measured under the same extraction conditions; the natural aroma retention rate = total peak area of ​​finished tea infusion / reference peak area × 100%. By using a unified sample matrix (aqueous phase) and extraction conditions, the comparability of aroma measurement results between the raw tea and the finished product is ensured.

[0024] The online near-infrared spectroscopy combined with a chemometric model was established as follows: Eighty tea infusion samples were collected at different extraction times, and the concentration of ester-type catechins was determined by high-performance liquid chromatography (HPLC) as a reference value. Sample spectra were acquired using a near-infrared spectrometer, and after standard normal variable transformation (SNV) and first derivative preprocessing, a calibration model was established using partial least squares (PLS). The model cross-validation determination coefficient R0 was used. 2 =0.993, RMSEP = 0.42 mg / L. During online detection, the real-time acquired spectrum is input into the model to output the concentration of ester-type catechins. Example 1

[0025] In this embodiment, the raw material is jasmine Longjing tea, and the material-to-liquid ratio is 1:20.

[0026] S1 Temperature-Separated Peak Extraction: 100g of jasmine Longjing tea was placed in a sealed extraction tank. First, 2L of 20℃ pure water was added for low-temperature extraction for 4 minutes. Then, the temperature was raised to 40℃ for approximately 1 minute (not included in the extraction time), and the extraction was continued for 4 minutes. After reaching 40℃, samples were taken every minute to detect the concentration of ester-type catechins in the extract. The increases in ester-type catechin concentrations at 1→2 minutes, 2→3 minutes, and 3→4 minutes after temperature increase were 3.2mg / L, 1.2mg / L, and 0.7mg / L, respectively, showing a continuous decreasing trend. This indicated the leaching inflection point had been reached, and the extraction was immediately terminated. The tea was then filtered to obtain the first brew. This step controls the dissolution of bitter substances through temperature-separated extraction, addressing the deficiency of excessive leaching of bitter substances in existing processes.

[0027] S2 Tea Aroma Capture and Storage: During the entire extraction process, the aroma escaping from the extraction tank is drawn out through a closed circulation system and captured by condensation at 4°C to obtain aroma condensate. The aroma condensate is concentrated under reduced pressure to a solid content of 5%, and then mixed with a wall material solution. The wall material is a compound of maltodextrin and β-cyclodextrin in a mass ratio of 2:1. The solid content of the mixture is adjusted to 20%, and the mass ratio of core material to wall material is 1:4. Spray drying is performed with an inlet air temperature of 150°C, an outlet air temperature of 75°C, and a feed rate of 650 mL / h to prepare microencapsulated natural tea aroma storage. The average particle size of the microcapsules is 20 μm, and the encapsulation rate is 88%.

[0028] Testing revealed that the total content of linalool and geraniol in the obtained microencapsulated natural tea aroma was 40 μg / mg (measured value). This value is the average measured value of each batch after spray drying and standardization to the target content, with a fluctuation range of ±2 μg / mg. This step captures the natural aroma of the original tea, addressing the deficiency of existing processes that require the addition of exogenous flavorings to prevent aroma loss.

[0029] S3 Tea Infusion Post-Processing: After coarse and fine filtration of the first-brew tea infusion, sodium ascorbate is added to the finely filtered tea infusion at an amount 1.2 times the target content of 0.03% in the sterilized tea infusion. The infusion is then sterilized at 137℃ for 5 seconds and cooled to 22℃. Testing showed that the sodium ascorbate content in the sterilized and cooled tea infusion was 0.028%. This step of adding sodium ascorbate inhibits browning, addressing the shortcomings of existing processes regarding browning during shelf life.

[0030] S4 Aroma Delay Refill: Under aseptic conditions, microencapsulated natural tea aroma was pre-dispersed in a small amount of sterile water to form a suspension. Testing revealed that the total free amino acid concentration in the cooled tea infusion was 81.6 mg / L. To achieve a 1:150 ratio of linalool to geraniol to total free amino acid concentration, the final product needed to have a total linalool and geraniol concentration of 544 μg / L. Since the total linalool and geraniol content in the microencapsulated natural tea aroma was 40 μg / mg, 13.6 mg of microencapsulated natural tea aroma was added per liter of tea infusion. After thorough mixing, the mixture was aseptically filled using nitrogen headspace protection to obtain a low-bitterness, sugar-free jasmine Longjing tea beverage.

[0031] Testing revealed that the total concentration of linalool and geraniol in the final product was 550 μg / L, and the total concentration of free amino acids was 81.2 mg / L, with an actual ratio of 1:148. This step utilizes the synergistic effect of aroma and taste to enhance sweetness, thus addressing the deficiency of existing processes that require the addition of sweeteners.

[0032] Explanation of the destination after microcapsule addition: After microcapsule addition, the wall materials maltodextrin and β-cyclodextrin are completely dissolved in the tea soup, the aroma of the core material is gradually released, and the final product is a clear and homogeneous liquid with no visible particles; the amount of wall material added is only 0.003% of the total mass of the tea soup. Example 2

[0033] In this embodiment, the raw material is Guifu Oolong tea, and the material-to-liquid ratio is 1:15.

[0034] S1 Temperature-Segmented Peak Extraction: 100g of Guifu Oolong tea is placed in a sealed extraction tank. First, 1.5L of 15℃ pure water is added for low-temperature extraction for 3 minutes, and then the temperature is raised to 35℃ for 3 minutes. After the temperature is raised to 35℃, samples are taken every 1 minute to detect the concentration of ester-type catechins in the extract. Samples are taken at 0 min, 1 min, 2 min, and 3 min. When the increase in the concentration of ester-type catechins in the three time periods of 0→1 min, 1→2 min, and 2→3 min decreases sequentially, it is determined that the extraction inflection point has been reached, and the extraction is immediately terminated. The first tea infusion is obtained by filtration.

[0035] S2 Tea Aroma Capture and Storage: During the entire extraction process, the aroma escaping from the extraction tank is drawn out through a closed circulation system and captured by condensation at 0℃ to obtain aroma condensate. The aroma condensate is concentrated under reduced pressure to a solid content of 5%, and then mixed with the wall material solution. The wall material is a compound of maltodextrin and β-cyclodextrin in a mass ratio of 2:1. The solid content of the mixture is adjusted to 15%, and the mass ratio of core material to wall material is 1:3. Spray drying is carried out with an inlet air temperature of 140℃, an outlet air temperature of 70℃, and a feed rate of 500mL / h to prepare microencapsulated natural tea aroma storage. The average particle size of the microcapsules is 1μm, and the encapsulation rate is 86%.

[0036] The total content of linalool and geraniol in the microencapsulated natural tea fragrance was found to be 40 μg / mg (measured value). This value is the average measured value of each batch after spray drying and standardization to the target content, with a fluctuation range of ±2 μg / mg.

[0037] S3 Tea Infusion Post-Processing: After coarse and fine filtration of the first brew, sodium ascorbate is added to the finely filtered tea infusion at an amount 1.1 times the target content of 0.012% in the sterilized tea infusion. The infusion is then sterilized at 135℃ for 6 seconds and cooled to 20℃. Testing showed that the sodium ascorbate content in the sterilized and cooled tea infusion was 0.011%.

[0038] S4 Aroma Delayed Refill: Under aseptic conditions, microencapsulated natural tea aroma was pre-dispersed in a small amount of sterile water to form a suspension. Testing revealed that the total concentration of free amino acids in the cooled tea infusion was 72.0 mg / L. To achieve the target ratio of linalool to geraniol to total free amino acid concentration of 1:120, the total concentration of linalool and geraniol in the final product needs to reach 600 μg / L. Since the total content of linalool and geraniol in the microencapsulated natural tea aroma is 40 μg / mg, 15.0 mg of microencapsulated natural tea aroma was added per liter of tea infusion.

[0039] After thorough mixing, the liquid surface was aseptically filled using nitrogen headspace protection to obtain a low-bitterness, sugar-free Gui Fu Oolong tea beverage. Testing revealed that the final product contained a total concentration of linalool and geraniol of 590 μg / L and a total concentration of free amino acids of 71.8 mg / L, with an actual ratio of 1:122. Example 3

[0040] In this embodiment, the raw material is Biluochun tea, and the material-to-liquid ratio is 1:25.

[0041] S1 temperature-staggered extraction: 100g of Biluochun tea is put into a sealed extraction tank. First, 2.5L of 25℃ pure water is added for low-temperature extraction for 5 minutes, and then the temperature is raised to 45℃ for 4 minutes. After the temperature is raised to 45℃, samples are taken every 1 minute to detect the concentration of ester-type catechins in the extract. When the increase in the concentration of ester-type catechins measured at three consecutive sampling points decreases sequentially, it is determined that the extraction inflection point has been reached, and the extraction is immediately terminated. The first tea infusion is obtained by filtration.

[0042] S2 Tea Aroma Capture and Storage: During the entire extraction process, the aroma escaping from the extraction tank is drawn out through a closed circulation system and captured by condensation at 6°C to obtain aroma condensate. The aroma condensate is concentrated under reduced pressure to a solid content of 5%, and then mixed with the wall material solution. The wall material is a compound of maltodextrin and β-cyclodextrin in a mass ratio of 2:1. The solid content of the mixture is adjusted to 25%, and the mass ratio of core material to wall material is 1:5. Spray drying is performed with an inlet air temperature of 160°C, an outlet air temperature of 80°C, and a feed rate of 800 mL / h to prepare microencapsulated natural tea aroma storage. The average particle size of the microcapsules is 50 μm, and the encapsulation rate is 87%.

[0043] The total content of linalool and geraniol in the microencapsulated natural tea fragrance was found to be 40 μg / mg (measured value). This value is the average measured value of each batch after spray drying and standardization to the target content, with a fluctuation range of ±2 μg / mg.

[0044] S3 Tea Infusion Post-Processing: After coarse and fine filtration of the first brew, sodium ascorbate is added to the finely filtered tea infusion at an amount 1.3 times the target content of 0.05% in the sterilized tea infusion. The infusion is then sterilized at 139℃ for 4 seconds and cooled to 25℃. Testing showed that the sodium ascorbate content in the sterilized and cooled tea infusion was 0.047%.

[0045] S4 Aroma Delayed Refill: Under aseptic conditions, microencapsulated natural tea aroma was pre-dispersed in a small amount of sterile water to form a suspension. Testing revealed that the total concentration of free amino acids in the cooled tea infusion was 85.8 mg / L. To achieve the target ratio of linalool to geraniol to total free amino acid concentration of 1:180, the total concentration of linalool and geraniol in the final product needs to reach 477 μg / L. Since the total content of linalool and geraniol in the microencapsulated natural tea aroma is 40 μg / mg, 11.9 mg of microencapsulated natural tea aroma was added per liter of tea infusion.

[0046] After thorough mixing, the liquid surface was aseptically filled using nitrogen headspace protection to obtain a low-bitterness, sugar-free Biluochun tea beverage. Testing revealed that the final product contained a total concentration of linalool and geraniol of 480 μg / L and a total concentration of free amino acids of 85.5 mg / L, with an actual ratio of 1:178. Example 4

[0047] In this embodiment, the raw material is aged tangerine peel and Pu-erh tea, and the ratio of material to liquid is 1:20.

[0048] S1 Temperature-Segmented Peak Extraction: 100g of aged tangerine peel Pu-erh tea is put into a sealed extraction tank. First, 2L of 20℃ pure water is added for low-temperature extraction for 4 minutes, and then the temperature is raised to 40℃ for 3 minutes. After the temperature is raised to 40℃, samples are taken every 1 minute to detect the concentration of ester-type catechins in the extract. When the increase in the concentration of ester-type catechins measured at three consecutive sampling points decreases sequentially, it is determined that the extraction inflection point has been reached, and the extraction is immediately terminated. The first tea infusion is obtained by filtration.

[0049] S2 Tea Aroma Capture and Storage: During the entire extraction process, the aroma escaping from the extraction tank is drawn out through a closed circulation system and captured by condensation at 4°C to obtain aroma condensate. The aroma condensate is concentrated under reduced pressure to a solid content of 5%, and then mixed with the wall material solution. The wall material is a compound of maltodextrin and β-cyclodextrin in a mass ratio of 2:1. The solid content of the mixture is adjusted to 20%, and the mass ratio of core material to wall material is 1:4. Spray drying is performed with an inlet air temperature of 150°C, an outlet air temperature of 75°C, and a feed rate of 650 mL / h to prepare microencapsulated natural tea aroma storage. The average particle size of the microcapsules is 25 μm, and the encapsulation rate is 89%.

[0050] The total content of linalool and geraniol in the microencapsulated natural tea fragrance was found to be 40 μg / mg (measured value). This value is the average measured value of each batch after spray drying and standardization to the target content, with a fluctuation range of ±2 μg / mg.

[0051] S3 Tea Infusion Post-processing: After coarse and fine filtration of the first brew, pectinase is added to the finely filtered tea infusion at a rate of 0.0075% of the tea infusion mass. The enzymatic hydrolysis temperature is 32.5℃ and the hydrolysis time is 12.5 min. After the hydrolysis is completed, the temperature is raised to 90℃ to inactivate the enzyme for 5 min, and then cooled to 22℃. Subsequently, sodium ascorbate is added at a rate of 1.2 times the target content of 0.03% in the sterilized tea infusion. The tea is then sterilized at 137℃ for 5 seconds and cooled to 22℃.

[0052] Testing revealed that the sodium ascorbate content in the tea infusion after sterilization and cooling was 0.029%. Both the pectinase treatment and the addition of sodium ascorbate were performed after fine filtration and before UHT sterilization.

[0053] S4 Aroma Delayed Refill: Under aseptic conditions, microencapsulated natural tea aroma is pre-dispersed in a small amount of sterile water to form a suspension. Testing revealed that the total free amino acid concentration in the cooled tea infusion was 63.0 mg / L. To achieve a 1:150 ratio of linalool to geraniol to total free amino acid concentration, the final product needs to reach a total linalool and geraniol concentration of 420 μg / L. Since the total linalool and geraniol content in the microencapsulated natural tea aroma is 40 μg / mg, 10.5 mg of microencapsulated natural tea aroma is added per liter of tea infusion. After thorough mixing, the mixture is aseptically filled using nitrogen headspace protection to obtain a low-bitterness, sugar-free tangerine peel Pu-erh tea beverage.

[0054] Testing revealed that the total concentration of linalool and geraniol in the final product was 425 μg / L, and the total concentration of free amino acids was 62.8 mg / L, with an actual ratio of 1:148. Liquid chromatography analysis showed that the final product contained pectin hydrolysis products such as galacturonic acid, confirming that the pectin from the dried tangerine peel was effectively hydrolyzed.

[0055] Comparative Example This comparative example uses the industry-standard 85℃ single-temperature extraction process. The specific steps are as follows: weigh 100g of Jasmine Longjing tea, put it into the extraction tank, add 2L of 85℃ pure water, stir and extract for 10min, filter to obtain tea soup, add 0.03% sodium ascorbate to the tea soup, sterilize at 137℃ for 5s, cool to 25℃, and take a sample for aroma component determination. Commercially available jasmine flavoring was then added to adjust the aroma concentration to that of regular commercially available sugar-free jasmine tea, and the samples were bottled to obtain the comparison sample. This comparative example did not undergo temperature-controlled extraction or natural aroma capture and re-addition. The natural aroma retention rate of the comparative examples in Table 1 is calculated based on the measured values ​​of the samples taken before adding flavoring. This data is the average of three parallel experiments, with an RSD of less than 5%.

[0056] Verification of the correlation between the dissolution of bitter substances In the extraction process of Example 1, after heating, samples were taken every 1 minute to simultaneously measure the concentrations of ester-type catechins and caffeine in the extract, collecting data from a total of 5 sampling points. The results showed that the dissolution trends of the two were highly consistent, and the calculated Pearson correlation coefficient was 0.987 (p<0.01), indicating a highly significant positive correlation. This proves that under the temperature-controlled extraction conditions, it is only necessary to monitor the dissolution inflection point of ester-type catechins to simultaneously control the extraction amount of caffeine within 30% of that under the same conditions of single-temperature extraction at 85℃, without the need to separately monitor the caffeine concentration, thus simplifying the process control procedure.

[0057] Core performance test data Table 1 Comparison of core components between each embodiment and the comparative example Comparative Example (Jasmine Longjing Tea) 100 100 100 100 22 16.2 Example 1 (Jasmine Longjing) 68 65 27 26 89 11.3 Example 2 (Gui Fu Oolong) 72 69 24 22 87 12.1 Example 3 (Biluochun) 66 63 28 27 88 10.8 Example 4 (Chenpi Pu'er) 70 67 25 23 91 12.5 The dissolution rates of each embodiment are relative values ​​calculated based on the content of the corresponding components in the tea soup obtained by single-temperature extraction at 85℃ for 10 minutes of the same variety of raw tea, with 100% as the standard. The detection values ​​of the comparative example are also used as the 85℃ control benchmark for jasmine Longjing raw materials. The measured values ​​of the 85℃ control benchmarks of the raw materials used in Examples 2-4 show varietal differences. The dissolution rates of each embodiment are calculated based on the measured values ​​of the control benchmarks of their respective raw materials. The consistency between the relative percentage and the absolute concentration is shown in Table 1-1. The dissolution rates of free amino acids and non-ester catechins in the four embodiments are all higher than 60%, while the dissolution rates of ester catechins and caffeine are all lower than 30%. The natural aroma retention rate is more than 3 times higher than that of the comparative example. It can meet the requirements of low bitterness and natural flavor without the addition of any exogenous sweeteners or flavorings. The natural aroma retention rate of the comparative example is lower, mainly because the high-temperature extraction at 85℃ for 10 minutes causes a large amount of aroma to volatilize, and the subsequent UHT sterilization further causes losses.

[0058] Table 1-1 Absolute Concentration of Core Components in the Final Products of Each Raw Material at 85℃ and Examples (mg / L) Jasmine Longjing Tea at 85℃ (comparison) 120.0 68.0 45.0 35.0 Example 1 (Jasmine Longjing) 81.6 44.2 12.15 9.10 Gui Fu Oolong 85℃ control 100.0 55.0 50.0 40.0 Example 2 (Gui Fu Oolong) 72.0 37.95 12.0 8.80 Biluochun tea at 85℃ (comparison) 130.0 70.0 48.0 36.0 Example 3 (Biluochun) 85.8 44.1 13.44 9.72 85℃ comparison of aged tangerine peel Pu-erh tea 90.0 50.0 42.0 32.0 Example 4 (Chenpi Pu'er) 63.0 33.5 10.5 7.36 In Table 1-1, the 85℃ control is the measured value of the tea soup obtained by single-temperature extraction at 85℃ for 10 minutes using the same variety of raw tea, and the data of the examples are the measured values ​​of the final products of the corresponding examples.

[0059] Table 2. Changes in the concentration of bitter substances during the extraction process of Example 1 (timed after heating). 0 12.3 8.7 - - 1 15.7 11.2 3.4 2.5 2 18.9 13.6 3.2 2.4 3 20.1 14.5 1.2 0.9 4 20.8 15.0 0.7 0.5 After heating, the increases in ester-type catechin levels measured in the three intervals of 1→2 min, 2→3 min, and 3→4 min were 3.2 mg / L, 1.2 mg / L, and 0.7 mg / L, respectively, showing a continuous decreasing trend, indicating that the leaching inflection point had been reached. At the same time, the increase in caffeine also decreased synchronously, verifying the feasibility of controlling the caffeine leaching amount by monitoring only ester-type catechin, thus reducing the process monitoring cost.

[0060] Sensory evaluation Ten trained sensory evaluators scored the sweetness intensity of Example 1 and the comparative example (on a scale of 0 to 10). The average score for Example 1 was 7.2, and the average score for the comparative example was 3.5. The sample of Example 1 showed a distinct aftertaste and a lasting natural tea aroma without the addition of any sweeteners.

[0061] All examples were made without any exogenous sweeteners, sugar alcohols, or flavorings. The bitterness was lower than that of the comparative example. The natural aroma was rich and the aftertaste was obvious. There was no obvious browning or aroma deterioration within a shelf life of 6 months.

[0062] refer to Figure 2This figure visually illustrates the core performance differences between the process of this invention and existing conventional processes. It can be clearly seen that the natural aroma retention rate of the four different base examples all reached over 87%, which is 3.9 to 4.1 times that of the comparative example. This solves the defects of existing processes, such as the large loss of natural aroma due to high-temperature extraction and the need to add exogenous flavorings. At the same time, the relative dissolution rate of ester-type catechins in all examples is less than 30%, which is only about 1 / 4 of that in the comparative example. The amount of bitter substances extracted is reduced, and all four different types of raw tea can meet the process requirements, proving that this process has strong adaptability and does not require significant parameter adjustments for different types of tea. It can be directly applied to industrial production.

[0063] refer to Figure 3 This figure visually presents the dissolution patterns of the two core bitter substances during temperature-controlled extraction. It is clear that the dissolution trends of ester-type catechins and caffeine highly overlap. The calculated Pearson correlation coefficient between the two is 0.987, indicating a highly significant positive correlation. After reaching the leaching inflection point 3 minutes after heating, the concentration increases of both substances drop sharply. This verifies that monitoring only the concentration change of ester-type catechins is sufficient to control the leaching amount of caffeine, eliminating the need for separate monitoring of caffeine concentration. This simplifies the process control process for industrial production, reduces the equipment investment cost for online detection, and solves the problems of high process complexity and high error probability caused by multi-index monitoring.

[0064] refer to Figure 4 This figure visually presents the sensory differences between the product of this invention and existing conventional sugar-free tea. It can be clearly seen that the bitterness of Example 1 is only 27% of that of the comparative example, achieving a significant aftertaste effect without the addition of any exogenous sweeteners. The intensity of the aftertaste is more than twice that of the comparative example. At the same time, because it retains the natural aroma of the original tea, the aroma intensity and flavor naturalness scores both reach 8.5 points or higher, which is higher than the comparative example with added exogenous flavorings. Ultimately, the overall acceptance rate is 2.2 times that of the comparative example, meeting consumers' core needs for sugar-free tea and solving the industry pain point that existing sugar-free teas rely on exogenous sweeteners and flavorings to cover up flavor defects.

[0065] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A low-bitterness, sugar-free tea beverage, characterized in that, Contains tea liquor and natural tea aroma components; The tea infusion was obtained by selective extraction of raw tea at different temperatures and peak times. The raw tea was one of the following: Jasmine Longjing, Osmanthus Oolong, Biluochun, or Aged Peel Pu'er, with a tea-to-water mass ratio of 1:15 to 1:

25. The tea infusion obtained by extracting the same mass of raw tea at a single temperature of 85℃ for 10 minutes served as a control. The dissolution of amino acids and non-ester catechins in the tea infusion was ≥60% of that in the control, while the dissolution of ester catechins and caffeine was ≤30% of that in the control. The natural tea aroma component is the aroma released during the extraction process of the original tea, without any external addition, and is added back after the tea soup is sterilized and cooled; the ratio of the total concentration of linalool and geraniol to the total concentration of free amino acids in the tea beverage is 1:120~1:

180.

2. The low-bitterness, sugar-free tea beverage according to claim 1, characterized in that, When the original tea is aged tangerine peel Pu-erh tea, the tea soup also contains pectin or pectin hydrolysis products derived from aged tangerine peel.

3. The low-bitterness, sugar-free tea beverage according to claim 1, characterized in that, The tea infusion also contains sodium ascorbate at a mass ratio of 0.01% to 0.05%.

4. A method for preparing a low-bitterness, sugar-free tea beverage, used to prepare the low-bitterness, sugar-free tea beverage according to any one of claims 1 to 3, characterized in that, Includes the following steps: S1. Temperature-segmented extraction: Put the raw tea into a sealed extraction tank, first extract with pure water at 15~25℃ for 3~5 minutes, then heat to 35~45℃ for 2~4 minutes; after heating to 35~45℃, take a sample every 1 minute to detect the concentration of ester-type catechins in the extract. When the increase in the concentration of ester-type catechins measured at three consecutive sampling points decreases sequentially, it is determined that the extraction inflection point has been reached, and the extraction is immediately terminated. Filter to obtain the first tea infusion. S2. Aroma Collection and Temporary Storage: During the entire extraction process, the aroma escaping from the extraction tank is drawn out through a closed circulation system and collected by condensation at 0~6℃ to obtain aroma condensate. The aroma condensate is concentrated and mixed with the wall material solution, and the solid content is adjusted to 15%~25%. The mass ratio of core material to wall material is 1:3~1:

5. Spray drying is performed to obtain microencapsulated natural tea aroma temporary storage. The average particle size of the microcapsules is 1~50μm. S3. Post-processing of tea liquor: After coarse filtration and fine filtration of the first brew, sodium ascorbate is added to the finely filtered tea liquor. The target content is 0.01%~0.05% by mass in the sterilized tea liquor. The tea liquor is then subjected to UHT ultra-high temperature instantaneous sterilization and cooled to 20~25℃. S4. Aroma Delay Refill: Under aseptic conditions, microencapsulated natural tea aroma is pre-dispersed in a small amount of sterile water to form a suspension, which is then added to the cooled tea soup at a preset concentration. After stirring evenly, the liquid surface is protected by nitrogen headspace and then aseptically filled to obtain the low-bitterness sugar-free tea beverage.

5. The preparation method according to claim 4, characterized in that, The concentration of ester-type catechins described in S1 is monitored in real time using online near-infrared spectroscopy in conjunction with a chemometric model.

6. The preparation method according to claim 4, characterized in that, The wall material described in S2 is a compound of maltodextrin and β-cyclodextrin in a mass ratio of 2:

1.

7. The preparation method according to claim 4, characterized in that, The spray drying process described in S2 has an inlet air temperature of 140~160℃, an outlet air temperature of 70~80℃, and a feed rate of 500~800mL / h.

8. The preparation method according to claim 4, characterized in that, The UHT sterilization temperature described in S3 is 135~139℃, and the sterilization time is 4~6s.

9. The preparation method according to claim 4, characterized in that, The amount of sodium ascorbate added in S3 is 1.1 to 1.3 times the target content in the sterilized tea soup, and the target content is 0.01% to 0.05%.

10. The preparation method according to claim 4, characterized in that, In step S3, when the original tea is aged tangerine peel Pu-erh tea, before the UHT sterilization, pectinase is added to the finely filtered tea soup for enzymatic hydrolysis. The hydrolysis temperature is 30~35℃, and the hydrolysis time is 10~15min. After the hydrolysis is completed, the temperature is raised to 90℃ to inactivate the enzyme for 5min, and then cooled to 20~25℃ before the UHT sterilization is performed. The amount of pectinase added is 0.005%~0.01% of the mass of the tea soup.

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