Preparation method of high-quality low-sugar fermented tea beverage

Abstract

The invention provides a preparation method of a high-quality low-sugar fermented tea beverage, which comprises the following steps: with Pu'er tea (tableland tea) extract as a raw material, fermenting by using lactobacillus bulgaricus, extracting, filtering tea juice, adding a sugar source and citric acid, primarily sterilizing after sterile filling, secondarily sterilizing, packaging, sealing, storing and the like. Fermentation conditions are controlled, the taste and nutritional value are improved, and high quality and stability of the product are ensured. Finally, according to the optimal process of the lactobacillus bulgaricus fermented Pu'er tea beverage, the tea-water ratio is 1: 175, the inoculum size is 4%, the sugar adding amount is 5%, the fermentation temperature is 28 DEG C, the fermentation time is 16 hours, the low-sugar fermented tea beverage with unique taste and health attributes is obtained, and the sensory score is 92. The obtained low-sugar fermented tea is excellent in performance, mellow in taste, unique in tea fragrance and fermentation fragrance and rich in nutritional ingredients through response surface analysis and taste testing evaluation, and has the healthy effects of reducing blood fat, promoting steroid excretion and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of microbial fermentation and Pu'er tea processing, and relates to a method for preparing a high-quality low-sugar fermented tea beverage. Background Art

[0002] Kombucha is a fermented tea beverage that is commonly seen on the market. Kombucha is a sweet and sour beverage made by fermenting tea and sucrose as fermentation substrates and the biofilm formed by the symbiosis of bacteria and yeast as the fermentation agent. During the fermentation process, a small amount of alcohol is produced, which is not suitable for the needs of consumers such as pregnant women, children, middle-aged and elderly people, and commuters. Therefore, it is necessary to develop a low-sugar fermented tea beverage.

[0003] Pu'er tea is a preferred low-sugar fermented tea raw material. In the selection of raw materials for Pu'er tea beverages, the difference in sugar content between terraced tea and ancient tree tea mainly stems from the characteristics of Pu'er tea varieties and processing methods. The sugar content of terraced tea (Pu'er tea) is generally higher than that of ancient tree tea (Pu'er tea). In terms of planting density and environment, terraced tea is usually planted in dense tea gardens. The growth environment of tea trees is relatively uniform and is more manually managed, resulting in a more concentrated distribution of nutrients in tea leaves and a relatively stable sugar content. In terms of growth cycle and picking time, due to intensive planting and management, the tea trees of terraced tea have a shorter growth cycle and more frequent picking cycles; young leaves usually contain more soluble sugars, and the sugar content in frequently picked terraced tea leaves is relatively high. In terms of tea processing methods, terraced tea (Pu'er tea) will undergo different processes such as frying, drying, piling, and aging during the processing process, which directly affect the preservation and conversion of sugars in terraced tea leaves. For example, frying and drying can retain the soluble sugars in the tea leaves of Taidi tea (Pu'er tea), so that when brewed or processed into beverages, it shows a higher sugar content. Although pile fermentation and aging do not increase the sugar content in tea leaves, the residual sugars in the pile fermentation and aging process will affect the final sweetness perception, and incompletely fermented tea leaves contain more residual sugars, resulting in a perceived sweetness.

[0004] In terms of chemical composition and taste, compared with aged pu-erh tea, platform tea contains higher initial sugars and amino acids, which not only affect the sweetness and umami of tea, but also dissolve into the tea soup during fermentation or soaking, increasing the sugar content of the final beverage. Liang Zhang (2011) and other scholars showed in the study of Comparison of the chemical constituents of aged pu-erh tea, ripened pu-erh tea, and other teas using HPLC-DAD-ESI-MSn that the catechin content of platform tea is higher, while the gallic acid content is lower. This difference in composition makes the platform tea more bitter in taste and lacks the mellowness and rich layering of the aged pu-erh tea. Hye-Yung Lee (2023) and other scholars mentioned in the article Comparison of the Antioxidant Activity and Useful Ingredient Content of Gimhae Wild Tea and Yunnan Sun-dried Pu'er Tea that the flavor of terraced tea is usually relatively simple and lacks the unique aroma and depth of ancient tree tea; and although the rapid fermentation process of terraced tea improves production efficiency, it leads to the loss of delicate flavor in the tea leaves. This difference in flavor makes terraced tea less attractive than ancient tree tea in the high-end Pu'er tea market. Therefore, the basic production process and flavor basis of Pu'er tea beverages prepared using terraced tea are generally the same as those of conventional Pu'er tea beverages, especially in terms of taste, there is no obvious improvement.

[0005] Whether using terrace tea or ancient tree tea as raw materials, the fermentation process of Pu'er tea beverage is mainly based on imitating traditional pile fermentation. Although the environmental sanitation of fermentation has improved, the entire fermentation process is uncontrollable. For example, there is an existing method for preparing a fermented tea beverage rich in lactobacillus, which mainly involves first extracting tea leaves with water to obtain tea soup, then adding soluble carbohydrates, proliferation factors, inorganic salts, and active protective agents to the tea soup to obtain a tea soup mixture, and finally inoculating lactobacillus into the mixture for fermentation to obtain a fermented tea beverage. The method has the defect that when adding soluble carbohydrates, proliferation factors, inorganic salts, and active protective agents to the tea soup, it is difficult to ensure that these components are evenly distributed, which easily leads to local nutritional imbalance, thereby affecting the growth and fermentation effect of lactobacillus; at the same time, during the fermentation process of this method, maintaining a sterile environment is a challenge, and any contamination of miscellaneous bacteria will change the fermentation process, resulting in a decline in the quality of the fermented tea beverage and even safety issues.

[0006] The Chinese patent (CN202210418268.1 / A method for preparing a fermented tea beverage) discloses a method for preparing a fermented tea beverage using high hydrostatic pressure treatment technology, which combines high hydrostatic pressure treatment with mixed fermentation technology of multiple bacteria to increase the extraction rate of functional substances in tea leaves and improve the taste. However, although high hydrostatic pressure treatment helps to increase the solubility of flavonoids, this treatment may also change the stability or activity of other chemical components, potentially affecting the flavor and health benefits of the final product.

[0007] The Chinese patent (CN201811336999.1 / a method for preparing a lactic acid bacteria fermented tea beverage) discloses a method for preparing a lactic acid bacteria fermented tea beverage. When the tea soup is prepared and sterilized, the combined tea juice is added with a mass fraction of 5-8% fructose syrup, mixed evenly and added to 90-100℃ for sterilization for 30 minutes; and 8-10% white sugar and 0.3-0.5% stabilizer are added to the fermented solution, and canned under sterile conditions. The preparation process after fermentation, adding 8-10% white sugar, directly increases the sweetness of the beverage, affecting the health choices of consumers, especially for those who need to control sugar intake; in addition, too much sugar can easily cover up the natural flavor of tea beverages; although the use of stabilizers can improve the texture and stability of the beverage, 0.3-0.5% stabilizers cannot control the taste of tea beverages and are likely to cause reactions from sensitive consumers. Summary of the invention

[0008] In view of the above defects or improvement needs of the prior art, the present invention uses Pu'er tea (Taiwan tea) extract as raw material, ferments it with Lactobacillus bulgaricus, and produces low-sugar fermented tea beverages with unique taste and health attributes by controlling parameters such as fermentation time, sugar addition, and tea-water ratio. The present invention improves the overall process flow in the preparation method, as well as the key conditions and parameters of each step, especially the various conditions and parameters of each step of the preparation method, including the type and concentration ratio of microorganisms. Compared with the prior art, it can be targeted to access beneficial microorganisms, accurately control the transformation of key material components of Pu'er tea (Taiwan tea), and effectively realize the clean and controllable fermentation process of Pu'er tea (Taiwan tea). The low-sugar fermented tea prepared according to the present invention can increase the excretion of steroids and has a better effect on lowering blood lipids. The main substances are alcohols, esters, aromatics, and heterocyclic compounds containing nitrogen, oxygen, sulfur, etc.

[0009] Therefore, the first purpose of the present invention is to provide a method for preparing a high-quality low-sugar fermented tea beverage; the second purpose of the present invention is to compare the taste and nutritional components of tea beverages under different fermentation times, tea-water ratios and sugar contents, and the optimal process of Lactobacillus bulgaricus fermented Pu'er tea beverage is tea-water ratio (1:175), inoculation amount 4%, sugar addition amount 5%, fermentation temperature 28°C, fermentation time 16h, and the sensory score under this condition is 92. The low-sugar fermented tea beverage made under this parameter has a mellow taste, a unique tea fragrance and fermentation aroma, and is rich in nutrients, which meets the needs of a healthy diet.

[0010] Specifically, the present invention provides a method for preparing a high-quality low-sugar fermented tea beverage, which is generally completed by the following steps:

[0011] S1. Selection of raw materials: Select Pu'er tea (Taiwan tea) with better quality and less impurities;

[0012] S2. Extraction: Take a suitable tea-water ratio of 1:175 and boil in boiling water at 80℃ for 10min;

[0013] S3. Filtration: After extraction, use a filter to filter out the tea residue to obtain a tea extract for later use;

[0014] S4. Prepare tea-water ratio: add 5% sugar (the ratio of white sugar to sugar alcohol is 4:1) and 0.25% citric acid to the filtered tea extract;

[0015] S5. Canning: Filling in glass bottles;

[0016] S6. Sterilization: Sterilize in boiling water bath for 10 minutes;

[0017] S7. Inoculation and fermentation: The activated lactobacillus is inoculated into the canned tea soup in an appropriate proportion (lactobacillus inoculation amount 4%), and the fermentation time is 16 hours;

[0018] S8. Secondary sterilization: heat treatment sterilization to stop the continued fermentation;

[0019] S9. Final processing: mark the production date and batch number of the prepared low-sugar fermented tea; then store the sterilized fermented tea beverage in a cool, dry place at a storage temperature of 4-10°C.

[0020] Furthermore, the present invention provides a method for preparing a high-quality low-sugar fermented tea beverage, and the specific steps are detailed as follows:

[0021] The step of selecting raw materials in S1. requires the following raw material pretreatment process to be performed on the raw materials:

[0022] 1) Raw material collection and preliminary inspection: Collect raw Pu'er tea samples of different grades and specifications; conduct preliminary sensory inspection on the collected tea, including the color, aroma, and shape of the tea; and then conduct preliminary cleaning of impurities in the tea, such as removing stems and withered leaves;

[0023] 2) Quality grading and selection: According to the appearance, aroma, taste and other indicators of the terraced tea leaves, the collected terraced tea leaves are graded into three grades: high, medium and low. The terraced tea leaves with medium to high grades are selected as raw materials for production. This type of tea has better quality but relatively lower price.

[0024] 3) Impurity removal: The selected terraced tea is preliminarily cleaned to remove impurities such as sand and dust on the surface; the tea leaves are then manually sorted to remove obvious stems, withered leaves and other foreign objects; finally, physical methods such as screening and air separation are used to further improve the purity of the terraced tea leaves;

[0025] 4) Storage of Pu'er Tea (Taiwan Tea) Raw Materials: The selected Taiwan Tea leaves should be packaged and sealed to avoid contact with air and light to keep the tea fresh. Check the storage environment of the tea leaves to see if there are adverse factors such as moisture and light; the selected Pu'er Tea (Taiwan Tea) needs to be stored in a dry and light-proof condition to avoid quality degradation;

[0026] 5) Pretreatment of Pu'er tea (Taidi tea) raw materials: Before use, the Taidi tea leaves should be properly pretreated, such as chopping, baking, rolling, etc., to improve the aroma and taste of the tea.

[0027] In the step S2. extraction, a Pu'er tea (Taidi tea) extract is prepared by combining a cooking method and a microwave-assisted extraction method, as follows:

[0028] 1) Weighing Pu'er tea (Taiwan tea) leaves: Prepare an appropriate amount of Pu'er tea (Taiwan tea) leaves, usually 1 portion of tea leaves;

[0029] 2) Weigh the water: Calculate the amount of hot water required according to the tea-water ratio of 1:175, i.e. 1 part of tea corresponds to 175 parts of water; then pour the water into the container and heat it to 80°C;

[0030] 3) Processing Pu'er tea leaves: Break the tea cake into small pieces to increase the contact area between the Pu'er tea leaves and water; rinse the broken Pu'er tea leaves with room temperature water and soak for 5-10 minutes to remove floating impurities;

[0031] 4) Rinse and soak: Rinse the crushed Pu'er tea leaves with room temperature water to remove surface impurities; then soak the Pu'er tea leaves in room temperature water for 5-10 minutes to remove impurities floating on the water surface again;

[0032] 5) Mixing tea leaves and water: Mix the treated tea leaves with weighed water in a microwave-resistant container;

[0033] 6) Combination of steaming and microwave-assisted extraction: First, heat the mixture to 80°C in a heating device and keep the temperature constant; then maintain the temperature at 80°C and steam for 10 minutes; moderate stirring can be performed during the entire steaming process to ensure uniform contact between the Pu'er tea (Taiwan tea) and the water. After steaming, transfer the container to a microwave device and use the microwave device to reheat the mixture to 80°C. The microwave heating time is 2-5 minutes. Be careful to avoid overheating to prevent the degradation of the active ingredients in the Pu'er tea (Taiwan tea).

[0034] 7) Let stand: After turning off the heat, let stand for 2-3 minutes to allow the aroma and flavor of the Pu'er tea (Taidi tea) to fully blend;

[0035] 8) Filtration: Filter out the tea juice, remove the tea residue, and obtain the Pu'er tea (Taiwan tea) extract after cooking.

[0036] The step S3. filtration needs to be performed in batches and separated and packaged, as follows:

[0037] 1) Prepare the filtering equipment: First, use a 100-mesh filter and filter cloth to ensure that they are clean and odor-free to prevent affecting the quality of the tea juice; preheat the filtering equipment before use, place the filter and filter cloth at the outlet of the tea extraction container, and rinse the filtering equipment with a small amount of hot water to reduce temperature loss during filtration;

[0038] 2) Batch filtration: Pour the extracted tea soup slowly into the preheated filtration equipment several times; during the filtration process, keep the temperature of the tea juice between 75-85℃; then slowly pour the tea soup to make it flow evenly through the filter screen and filter cloth to ensure that the tea residue is fully separated to obtain a clear tea extract;

[0039] First filtration: separate most of the tea residue;

[0040] Second filtration: The tea juice after the first filtration is still not clear enough and needs to be filtered again; use the same 100 mesh filter and filter cloth;

[0041] Third filtration: In industrial production, in order to improve efficiency and clarity, a vacuum filter is required; the vacuum degree is between 0.05 and 0.1 MPa to prevent excessive oxidation of the tea juice;

[0042] 3) Collecting tea soup: Pour the filtered tea juice carefully into a clean container to obtain concentrated Pu'er tea juice;

[0043] 4) Tea residue separation: The tea residue remaining on the filter or cloth after filtration should be collected in time;

[0044] 5) Repackaging and storage: Repack the filtered Pu'er tea (Taiwan tea) extract into clean containers; then, the storage temperature should be controlled at 4-10℃ to maintain the quality and stability of the tea juice; the Pu'er tea (Taiwan tea) extract can be stored for several days to several weeks.

[0045] The tea-water ratio in S4 needs to be adjusted according to the appropriate amount obtained from the single factor experiment, as follows:

[0046] 1) Adding sugar source: Weigh 100 ml of Pu'er tea (Taidi tea) extract; prepare 5 g of white sugar and 1.25 g of sugar alcohol, with the ratio of white sugar to sugar alcohol being 4:1; in this process, slowly add the white sugar and sugar alcohol to the tea extract, stirring while adding until they are completely dissolved;

[0047] 2) Adding acidity regulator: weigh 0.25 g of citric acid; then slowly add the citric acid into the sugar-containing Pu'er tea (Taidi tea) juice, and continue stirring until it is completely dissolved;

[0048] 3) Mixing and blending: slowly add white sugar and sugar alcohol into the tea extract, stirring while adding until they are completely dissolved; then slowly add citric acid into the sugary tea juice, and continue stirring until they are completely dissolved; after stirring evenly, a low-sugar tea extract with added sugar source and acidity regulator is obtained.

[0049] S5. Glass bottle filling requires the glass bottles to be aseptically treated before filling, as follows:

[0050] 1) Cleaning and disinfection of glass bottles: First, clean the glass bottles thoroughly with detergent to remove dirt on the inner and outer surfaces; then disinfect the bottles with 75% alcohol or other food-grade disinfectants to ensure sterility; finally, rinse with sterile water and air dry or dry naturally;

[0051] 2) Aseptic filling: On a sterile operating table or in a sterile room, carefully fill the sterilized tea beverage into a pre-sterilized glass bottle; pay attention to the edge control of the glass bottle to prevent overflow and contamination; after completing the aseptic filling, cover the bottle cap in time to ensure good sealing.

[0052] S6. Sterilization requires that the glass bottles be sterilized before filling, as follows:

[0053] 1) Prepare heat treatment equipment: A constant temperature water bath is the preferred equipment, and backup equipment includes sterilization tanks, sterilizers or heat exchangers; before starting sterilization, preheat the equipment to a temperature close to the target temperature (80°C) to ensure temperature stability and consistency during the sterilization process;

[0054] 2) Heating sterilization: Set the equipment to 80°C and prepare for a 26-minute heating treatment; then place the container (such as a glass bottle, a high-temperature plastic container or a stainless steel tank) containing Pu'er tea (Taidi tea) juice in the equipment to ensure that each container is evenly heated; turn on the constant temperature water bath or other heat treatment equipment to start the heating sterilization process, and continuously monitor the temperature of the equipment to maintain it at 80°C and evenly distributed; strictly control the sterilization time to 26 minutes, to allow sufficient time to kill common bacteria and pathogens in the tea juice, while minimizing the impact on the flavor and nutritional components of the tea juice;

[0055] 3) Cooling: After the sterilization time is over, stop heating immediately and remove the container; quickly transfer the sterilized tea juice container to the cooling area, and use a cold water bath or cooling room to quickly lower the temperature to room temperature, usually 20-25°C, to prevent bacterial regrowth and maintain the flavor of the tea juice.

[0056] 4) Post-processing: Take out the sterilized tea beverage container and check if there is any abnormality; transfer the sterilized tea beverage to a sterile container for storage as soon as possible.

[0057] The S7. inoculation fermentation requires the glass bottle to be aseptically treated before filling, specifically as follows: the activated Lactobacillus (Lactobacillus bulgaricus) is inoculated into the canned tea soup according to an appropriate ratio (Lactobacillus inoculation amount 4%), and the fermentation time is 16h;

[0058] 1) Activation of Lactobacillus: preparing a culture medium suitable for the growth of Lactobacillus, inoculating Lactobacillus bulgaricus into the culture medium; then culturing the inoculated culture medium at a suitable temperature (37° C.) for 12-18 hours until the Lactobacillus reaches a highly active state in the logarithmic growth phase;

[0059] 2) Inoculation of tea beverage: Ensure that the tea beverage in the previous step (sterilization) has been cooled to room temperature to avoid high temperature killing lactobacillus; then inoculate the activated Lactobacillus bulgaricus into the tea beverage at a ratio of 4% (i.e., add 4 ml of Lactobacillus bulgaricus suspension to every 100 ml of tea extract); finally, gently stir the tea soup to evenly distribute the Lactobacillus bulgaricus in the tea beverage.

[0060] 3) Fermentation: Transfer the inoculated tea soup to a constant temperature fermentation box, set the temperature to 28°C, and ensure that the fermentation container is well sealed to prevent external contamination; the fermentation time is set to 16 hours, and try to avoid opening the fermentation container frequently during this period; regularly observe the changes in the fermentation process, but avoid interference to ensure the fermentation effect;

[0061] 4) Post-processing: After fermentation is completed, the fermented tea beverage is quickly cooled to room temperature to maintain the quantity and activity of Lactobacillus bulgaricus; after completion, the filtered fermented tea beverage is placed in a clean container and ensured to be well sealed; the container is stored under refrigerated conditions of 4-10°C to maintain the quality of the fermented tea beverage and the activity of the lactobacillus.

[0062] The S8. secondary sterilization requires secondary sterilization (heat treatment sterilization) to terminate the continued fermentation, as follows:

[0063] 1) Sterilization preparation: Select a suitable sterilization equipment heat exchanger; ensure that the equipment is clean and free of residues to avoid affecting the flavor and quality of the tea beverage; and then use heat-resistant containers to hold the fermented tea beverage; the container should be well sealed to prevent external contamination during the sterilization process;

[0064] 2) Heat treatment (sterilization): The heat exchanger is set to 90°C for 5 minutes; the container containing the fermented tea beverage is then placed in a constant temperature water bath or other sterilization equipment to ensure that all containers are heated evenly; the temperature and time are continuously monitored in real time during the sterilization process;

[0065] 3) Immediate cooling: After sterilization, quickly transfer the container to a cooling area; use a cold water bath or air cooling method to quickly lower the temperature of the tea beverage to room temperature (about 20-25°C) to prevent the continued impact of high temperature on the flavor of the tea beverage.

[0066] The S9. final treatment requires packaging and sealing the prepared low-sugar fermented tea, as follows:

[0067] 1) Packaging and sealing: After cooling, check the sealing of the container to ensure there is no leakage; mark the production date and batch number of each container; then store the sterilized fermented tea beverage in a cool and dry place. The recommended storage temperature is 4-10℃.

[0068] Preferably, the water in the tea-water ratio S4. of the present invention is mineral water with a pH value in the range of 6.5-8.5; the total dissolved inorganic matter and total dissolved organic matter of the mineral water must be tested in advance to meet the drinking water standards, and the microbial indicators in the mineral water also need to be tested in advance, including total coliform group, Escherichia coli, total colony count, heavy metal content such as lead, cadmium, mercury, etc. The content should be lower than the limit specified by the health standards, and it must not contain radioactive components.

[0069] Furthermore, the microbiological mechanism of the method for preparing a high-quality low-sugar fermented tea beverage of the present invention using Lactobacillus bulgaricus is as follows:

[0070] In terms of acid tolerance, Lactobacillus bulgaricus can grow at relatively low pH values, which is particularly beneficial to the acidic environment during the fermentation of Pu'er tea (Taiwan tea); the natural acidity of Pu'er tea (Taiwan tea) plus the lactic acid produced by lactic acid fermentation help to further lower the pH value, thereby inhibiting the growth of non-lactic acid bacteria and preventing the tea soup from spoiling.

[0071] In terms of adaptability to low-sugar environments, the natural sugar content in Erhai tea is relatively low, especially during the low-sugar fermentation process, when the source of sugar may be more limited; while Lactobacillus bulgaricus can effectively utilize the limited sugar in tea leaves (such as glucose and fructose) for fermentation, which is particularly important for the production of low-sugar fermented tea beverage products.

[0072] In terms of flavor contribution, during the fermentation process of Pu'er tea (Taidi tea), Lactobacillus bulgaricus not only produces lactic acid, but also produces other metabolites that help improve the flavor of tea, such as alcohols and esters; these metabolites can enhance the taste and aroma of Pu'er tea, giving it a unique sour and aromatic characteristic.

[0073] In terms of antibacterial effect, Lactobacillus bulgaricus lowers the pH value of the fermentation system by producing lactic acid and inhibits the growth of harmful microorganisms, which helps to extend the shelf life of fermented Pu'er tea and improve its safety.

[0074] From the probiotic properties of Lactobacillus bulgaricus, as a probiotic, Lactobacillus bulgaricus contributes to intestinal health in fermented tea beverages; although the activity of the strain may decrease after Pu'er tea fermentation, these probiotics can still provide potential health benefits.

[0075] Compared with the prior art, the beneficial effects of the present invention are as follows: Different from the existing pile fermentation which completely relies on experience and cannot control parameters, the present invention pre-treats the Pu'er tea raw materials at the source of fermentation, and adopts a stable and controllable fermentation production method. At the same time, the Pu'er tea after the fermentation is processed, and the whole process is in a monitorable state, and finally a stable and controllable Pu'er tea can be produced; after obtaining the low-sugar fermented tea, a response surface analysis was carried out to confirm the stability of the preparation method of the present invention.

[0076] Specifically, the preparation method of a high-quality low-sugar fermented tea beverage of the present invention, the mechanism of 4% inoculum of Lactobacillus bulgaricus is as follows: on the one hand, in the initial condition, the inoculum of 4% of high inoculum (i.e., adding 4 ml of activated lactobacillus culture fluid in every 100 ml of tea soup) provides enough bacterial cell quantity, can quickly occupy the fermentation environment, reduce the lag phase, and quickly enter the logarithmic growth phase; the high inoculum can also enhance the adaptability of lactobacillus to the tea soup environment, reduce the competition of other microorganisms, and improve the fermentation efficiency and the stability of the product. On the other hand, in terms of strain growth and metabolism, the high inoculum enables lactobacillus to reproduce rapidly, quickly consumes sugars and generates lactic acid, shortens the duration of the lag phase and the logarithmic growth phase; the metabolic activity of a large amount of lactobacillus accelerates the accumulation of lactic acid, and the pH value is rapidly reduced to the scope that is conducive to the growth of lactobacillus and inhibits harmful bacteria.

[0077] Specifically, the advantages of setting the fermentation time to 16 hours in the preparation method of a high-quality low-sugar fermented tea beverage described in the present invention are as follows: 16 hours of fermentation time can usually cover the logarithmic growth period and part of the stable period of Lactobacillus; during this stage, Lactobacillus is active and metabolites (lactic acid) are generated rapidly. Within 16 hours, Lactobacillus begins to enter the stable period, metabolic activity tends to balance, and the rate of lactic acid production slows down, but it is still accumulating. From the perspective of tea soup quality control, 16 hours of fermentation can ensure that the tea beverage has appropriate acidity and unique fermented flavor; too long fermentation time may lead to excessive acidification and affect the taste; 16 hours of fermentation can retain the beneficial ingredients in the tea soup, such as tea polyphenols and amino acids, while generating lactic acid and other metabolites to increase health functions.

[0078] Specifically, the method for preparing a high-quality low-sugar fermented tea beverage of the present invention has the following advantages at a fermentation temperature of 28°C: the best growth and metabolic activity can be obtained at a temperature of about 8°C, which can ensure that the microorganisms reproduce quickly and the product yield is high during the fermentation process. Under the temperature condition of 28°C, the fermenting microorganisms have a high conversion efficiency for sugar substrates, and can make full use of the raw sugars and convert them into the desired metabolites, such as ethanol, lactic acid, etc.

[0079] Specifically, the method for preparing a high-quality low-sugar fermented tea beverage of the present invention optimizes the fermentation conditions by deeply studying the biochemical reactions in the fermentation process, such as using an intelligent temperature control system, a humidity control device, etc., to achieve precise control of the fermentation process. This helps to improve the stability and quality consistency of the product; establish a strict quality monitoring system to closely monitor each link in the production process to ensure that the product quality meets the standards; and in response to the problem of nutrient loss during the fermentation process, new nutrient fortification technologies can be developed, such as adding specific nutrients or using bioengineering technology to increase the nutrient content in tea. BRIEF DESCRIPTION OF THE DRAWINGS

[0080] Figure 1 This is a process flow chart of a method for preparing a high-quality low-sugar fermented tea beverage according to the present invention;

[0081] Figure 2 This is a chart showing the effect of the amount of lactobacillus added on the sensory score of tea soup when the fermentation time is 12 hours in a method for preparing a high-quality low-sugar fermented tea beverage according to the present invention;

[0082] Figure 3 This is a chart showing the effect of the amount of lactobacillus added on the sensory score of tea soup when the fermentation time is 14 hours in a method for preparing a high-quality low-sugar fermented tea beverage according to the present invention;

[0083] Figure 4 This is a chart showing the effect of the amount of lactobacillus added on the sensory score of tea soup when the fermentation time is 16 hours in a method for preparing a high-quality low-sugar fermented tea beverage according to the present invention;

[0084] Figure 5 This is a chart showing the effect of the amount of lactobacillus added on the sensory score of tea soup when the fermentation time is 18 hours in a method for preparing a high-quality low-sugar fermented tea beverage according to the present invention;

[0085] Figure 6 This is a chart showing the effect of the amount of lactobacillus added on the sensory score of tea soup when the fermentation time is 20 hours in a method for preparing a high-quality low-sugar fermented tea beverage according to the present invention;

[0086] Figure 7 A response surface design and result chart of a low-sugar fermented tea beverage of a method for preparing a high-quality low-sugar fermented tea beverage according to the present invention;

[0087] Figure 8 A quadratic multinomial model and variance analysis charts of each item of the method for preparing a high-quality low-sugar fermented tea beverage according to the present invention;

[0088] Fig. 9 A contour 3D response surface diagram of the interaction between the water-to-tea ratio and the amount of added white sugar in the method for preparing a high-quality low-sugar fermented tea beverage according to the present invention;

[0089] Fig.10 A contour 3D response surface diagram of the interaction between the water-to-tea ratio and the lactobacillus inoculation amount in the method for preparing a high-quality low-sugar fermented tea beverage according to the present invention;

[0090] Fig.11 A contour 3D response surface diagram of the interaction between the water-to-tea ratio and the fermentation time in the method for preparing a high-quality low-sugar fermented tea beverage according to the present invention;

[0091] Fig.12A contour 3D response surface diagram of the interaction between the amount of added white sugar and the amount of lactobacillus inoculation in the method for preparing a high-quality low-sugar fermented tea beverage according to the present invention;

[0092] Fig.13 A 3D response surface diagram of the contour lines of the interaction between the amount of added white sugar and the fermentation time in the method for preparing a high-quality low-sugar fermented tea beverage according to the present invention;

[0093] Fig.14 This is a contour 3D response surface diagram of the interaction between the Lactobacillus inoculation amount and the fermentation time in the method for preparing a high-quality low-sugar fermented tea beverage described in the present invention. DETAILED DESCRIPTION

[0094] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0095] The present invention provides a low-sugar fermented tea beverage production process and optimization method. The purpose of the present invention is to use terraced tea in Pu'er tea as a raw material to prepare a low-sugar fermented tea beverage. Specifically, the fermented tea beverage process is optimized by single factor experiment and response surface method. Pu'er tea extract is used as a raw material, and Lactobacillus bulgaricus is used to ferment it. By controlling the fermentation time, sugar addition, tea-to-water ratio and other parameters, a low-sugar fermented tea beverage with a unique taste and health attributes is produced. The production of fermented tea beverages is mainly based on the reaction of substances such as tea polyphenols and amino acids in tea soup under the action of lactobacillus to produce metabolites with unique flavors. By controlling the fermentation process, the taste and nutritional components of the tea beverage can be adjusted, thereby producing a low-sugar fermented tea beverage suitable for the tastes of different consumers.

[0096] After the low-sugar fermented tea provided by the present invention is prepared, in order to verify the taste and performance of the low-sugar fermented tea, sensory score is used as the main evaluation index, combined with antioxidant activity, multiple groups of measurements and evaluations by professional tasters are carried out. The sensory score of the low-sugar fermented tea beverage of the present invention is 92, the taste is mellow, with a unique tea aroma and fermented aroma, and is rich in nutrients, meeting the needs of a healthy diet.

[0097] Example 1 Preparation method of a low-sugar fermented tea beverage according to the present invention

[0098] In a specific embodiment, the preparation of a high-quality low-sugar fermented tea beverage requires the following steps:

[0099] S1. Select and pre-treat raw materials of Pu'er tea (Taiwan tea): select raw Pu'er tea samples of different grades and specifications, conduct sensory inspection on their color, aroma and shape, and remove impurities such as stems and yellow leaves in the tea leaves; then divide the tea leaves into three grades of high, medium and low according to indicators such as appearance, aroma and taste, and select Pu'er tea (Taiwan tea) of medium to high quality; then perform preliminary cleaning on the selected tea leaves, use screening, air selection and other methods to improve the purity of the tea leaves, and then chop, bake, roll and other processes on the tea leaves before use to improve the aroma and taste;

[0100] S2. Extraction: weigh tea leaves and water, use 175 parts of water for 1 part of tea leaves, and heat the water to 80°C; then process the tea leaves, break the tea cakes and rinse them with room temperature water to remove impurities; then steam and microwave-assisted extraction, set the temperature to 80°C for 10 minutes, and microwave again for 2-5 minutes to avoid overheating; after steaming, let it stand for 2-3 minutes, and filter to obtain the tea juice extract;

[0101] S3. Filtration: Use a 100-mesh filter and filter cloth to filter three times. The first is primary filtration, which mainly filters most of the tea residue; the second layer is to clarify and filter the tea soup; the third is to use a vacuum filter with a vacuum degree between 0.05 and 0.1 MPa to prevent excessive oxidation of the tea juice; after filtration, separate the tea residue: collect the tea residue on the filter or cloth;

[0102] S4 tea ratio: first add sugar source, add 5g of white sugar and 1.25g of sugar alcohol to 100ml of tea extract; then add acidity regulator: add 0.25g of citric acid and stir until completely dissolved;

[0103] S5. Filling in glass bottles: The glass bottles are cleaned with detergent and then disinfected with 75% alcohol to ensure sterility; then the tea beverage is filled into the glass bottles in a sterile environment;

[0104] S6. Sterilization: Use a constant temperature water bath to heat at 80°C for 26 minutes; quickly cool to room temperature after sterilization;

[0105] S7. Inoculation and fermentation: First, Lactobacillus bulgaricus is cultured to a highly active state; after the tea juice is cooled to room temperature, Lactobacillus bulgaricus is inoculated at a ratio of 4%, and then fermented at 28°C for 16 hours;

[0106] S8. Secondary sterilization: heat treatment sterilization, heat treatment at 90 ° C for 5 minutes to prevent further fermentation (terminate fermentation); after sterilization, the low-sugar fermented tea is cooled to room temperature;

[0107] S9. Final treatment: After cooling, check the sealing of the container, mark the production date and batch number of the low-sugar fermented tea, and store it at 4-10℃; at this time, the low-sugar fermented tea can be used as a product after passing the hygiene index test.

[0108] The prepared sugar fermented tea was subjected to multiple groups of measurements and evaluations by professional tasters. The sensory score of the low-sugar fermented tea beverage of the present invention was 92. The low-sugar fermented tea beverage produced under this parameter has a mellow taste, a unique tea aroma and fermented aroma, and is rich in nutrients, meeting the needs of a healthy diet.

[0109] Example 2 (Comparative Example) Specific preparation method of setting "tea-water ratio of 1:150, white sugar: sugar alcohol ratio of 4:1, lactobacillus inoculation amount of 3%, fermentation time of 14h"

[0110] In a specific embodiment, the sensory quality of the low-sugar fermented Pu'er tea beverage of the present invention is specifically tested according to a specific tea-to-water ratio, sugar addition amount, Lactobacillus inoculation amount and fermentation time.

[0111] In this embodiment, the experimental materials include Pu'er tea (Taiwan tea), white sugar, erythritol, and Lactobacillus bulgaricus; the experimental equipment includes a fermentation tank, a constant temperature incubator, an electronic balance, a pH meter, and a sensory scoring table.

[0112] In this embodiment, the basic fermentation conditions are as follows: inoculation amount 4%, sugar addition amount 5%, fermentation temperature 28°C, fermentation time 14h, citric acid addition amount 0.25%; other variable parameters are tea-water ratio of 1:150, white sugar: sugar alcohol ratio of 4:1, and Lactobacillus inoculation amount of 3%.

[0113] The implementation process of this embodiment is completely consistent with the process of embodiment 1, only the ratio and content of the preparation materials are adjusted, and the specific implementation steps are as follows:

[0114] S1. Raw material selection: select Pu'er tea with better quality and less impurities;

[0115] S2. Extraction: prepare tea liquid in a ratio of 1:150 between tea and water; then boil the Pu'er tea liquid in boiling water at 80°C for 10 minutes;

[0116] S3. Filtration: Use a filter to filter out the tea residue to obtain a tea extract for later use;

[0117] S4. Preparation: The filtered tea extract was prepared according to the following ratios;

[0118] 4.1 Sugar addition amount: the ratio of white sugar to sugar alcohol is 4:1, that is, 4% white sugar and 1% sugar alcohol;

[0119] 4.2 Amount of citric acid added: 25% of Pu'er tea liquid;

[0120] S5. Canning and sterilization: Can the prepared tea in glass bottles and sterilize in a boiling water bath for 10 minutes;

[0121] S6. Inoculation and fermentation: The tea liquid was divided into a fermentation tank and inoculated with Lactobacillus bulgaricus at a ratio of 3%; the fermentation tank was then placed in a constant temperature incubator at 28°C for 14 hours;

[0122] S7. Tea liquid preparation is completed: After fermentation is completed, the fermented tea liquid is subjected to multi-dimensional measurements and sensory scoring.

[0123] After the above experimental preparation, an edible low-sugar fermented Pu'er tea was obtained, and the results of multi-dimensional measurements are as follows:

[0124]

[0125] The experimental results show that under the conditions of "tea-to-water ratio of 1:150, white sugar: sugar alcohol ratio of 4:1, lactobacillus inoculation of 3%, and fermentation time of 14h", the low-sugar fermented Pu'er tea beverage has a good taste and color, and the microbial fermentation is relatively ideal, but the acidity and bacterial growth can be further optimized by adjusting the inoculation amount and fermentation time. Specifically, the low-sugar fermented Pu'er tea beverage produced has a moderate pH value, a high number of bacteria, an appropriate lactic acid content, a low dissolved oxygen concentration, a sufficient matrix concentration, a good taste, and a light brown color. The sensory indicators show that the product has a strong flavor, moderate sweetness and sourness, and no toxins and impurities were detected, and the fermentation process was normal. In the end, the sensory score was 70.1 points, showing a high degree of consumer acceptance.

[0126]

[0127]

[0128] This proves that the preparation method of low-sugar fermented Pu'er tea beverage is suitable for the production of Pu'er tea Lactobacillus fermented beverage, and the product quality and safety have reached the expected goals.

[0129] Example 3 (Comparative Example) Specific preparation method with "tea-water ratio of 1:175, white sugar: sugar alcohol ratio of 3:2, lactobacillus inoculation amount of 4%, fermentation time of 16h"

[0130] In a specific embodiment, the sensory quality of the low-sugar fermented Pu'er tea beverage of the present invention is specifically tested according to a specific tea-to-water ratio, sugar addition amount, Lactobacillus inoculation amount and fermentation time.

[0131] In this embodiment, the experimental materials include Pu'er tea (Taiwan tea), white sugar, erythritol, and Lactobacillus bulgaricus; the experimental equipment includes a fermentation tank, a constant temperature incubator, an electronic balance, a pH meter, and a sensory scoring table.

[0132] In this embodiment, the basic fermentation conditions are as follows: inoculation amount 4%, sugar addition amount 5%, fermentation temperature 28°C, fermentation time 16h, citric acid addition amount 0.25%; other variable parameters are tea-water ratio of 1:175, white sugar: sugar alcohol ratio of 3:2, and Lactobacillus inoculation amount of 4%.

[0133] The implementation process of this embodiment is completely consistent with the process of embodiment 1, only the ratio and content of the preparation materials are adjusted, and the specific implementation steps are as follows:

[0134] S1. Raw material selection: select Pu'er tea with better quality and less impurities;

[0135] S2. Extraction: prepare tea liquid in a ratio of 1:175 between tea and water; then boil the Pu'er tea liquid in boiling water at 80°C for 10 minutes;

[0136] S3. Filtration: Use a filter to filter out the tea residue to obtain a tea extract for later use;

[0137] S4. Preparation: The filtered tea extract was prepared according to the following ratios;

[0138] 4.1 Sugar addition amount: the ratio of white sugar to sugar alcohol is 3:2, that is, 3% white sugar and 2% sugar alcohol;

[0139] 4.2 Amount of citric acid added: 25% of Pu'er tea liquid;

[0140] S5. Canning and sterilization: Can the prepared tea in glass bottles and sterilize in a boiling water bath for 10 minutes;

[0141] S6. Inoculation and fermentation: The tea liquid was divided into a fermentation tank and inoculated with Lactobacillus bulgaricus at a ratio of 4%; the fermentation tank was then placed in a constant temperature incubator at 28°C for 16 hours;

[0142] S7. Tea liquid preparation is completed: After fermentation is completed, the fermented tea liquid is subjected to multi-dimensional measurements and sensory scoring.

[0143] After the above experimental preparation, an edible low-sugar fermented Pu'er tea was obtained, and the results of multi-dimensional measurements are as follows:

[0144]

[0145] The experimental results show that under the conditions of "tea-to-water ratio of 1:175, white sugar: sugar alcohol ratio of 3:2, lactobacillus inoculation of 4%, and fermentation time of 16h", the low-sugar fermented Pu'er tea beverage has a good taste and color, and the microbial fermentation is relatively ideal, but the acidity and bacterial growth can be further optimized by adjusting the inoculation amount and fermentation time. Specifically, the low-sugar fermented Pu'er tea beverage produced has a moderate pH value, a high number of bacteria, an appropriate lactic acid content, a low dissolved oxygen concentration, a sufficient matrix concentration, a good taste, and a light brown color. The sensory indicators show that the product has a strong flavor, moderate sweetness and sourness, and no toxins and impurities were detected, and the fermentation process was normal. In the end, the sensory score was 79.8 points, showing a relatively high consumer acceptance.

[0146]

[0147] This proves that the preparation method of low-sugar fermented Pu'er tea beverage is suitable for the production of Pu'er tea Lactobacillus fermented beverage, and the product quality and safety have reached the expected goals.

[0148] Example 4 (Comparative Example) Specific preparation method with "tea-water ratio of 1:200, white sugar:sugar alcohol ratio of 2:3, lactobacillus inoculation amount of 5%, fermentation time of 18h"

[0149] In a specific embodiment, the sensory quality of the low-sugar fermented Pu'er tea beverage of the present invention is specifically tested according to a specific tea-to-water ratio, sugar addition amount, Lactobacillus inoculation amount and fermentation time.

[0150] In this embodiment, the experimental materials include Pu'er tea (Taiwan tea), white sugar, erythritol, and Lactobacillus bulgaricus; the experimental equipment includes a fermentation tank, a constant temperature incubator, an electronic balance, a pH meter, and a sensory scoring table.

[0151] In this embodiment, the basic fermentation conditions are as follows: inoculation amount 4%, sugar addition amount 5%, fermentation temperature 28°C, fermentation time 18h, citric acid addition amount 0.25%; other variable parameters are tea-water ratio of 1:200, white sugar: sugar alcohol ratio of 2:3, and Lactobacillus inoculation amount of 5%.

[0152] The implementation process of this embodiment is completely consistent with the process of embodiment 1, only the ratio and content of the preparation materials are adjusted, and the specific implementation steps are as follows:

[0153] S1. Raw material selection: select Pu'er tea with better quality and less impurities;

[0154] S2. Extraction: prepare tea liquid at a ratio of 1:200 between tea and water; then boil the Pu'er tea liquid in boiling water at 80°C for 10 minutes;

[0155] S3. Filtration: Use a filter to filter out the tea residue to obtain a tea extract for later use;

[0156] S4. Preparation: The filtered tea extract was prepared according to the following ratios;

[0157] 4.1 Sugar addition amount: The ratio of white sugar to sugar alcohol is 2:3, that is, white sugar is 2% and sugar alcohol is 3%;

[0158] 4.2 Amount of citric acid added: 25% of Pu'er tea liquid;

[0159] S5. Canning and sterilization: Can the prepared tea in glass bottles and sterilize in a boiling water bath for 10 minutes;

[0160] S6. Inoculation and fermentation: The tea liquid was divided into a fermentation tank and inoculated with Lactobacillus bulgaricus at a ratio of 5%; the fermentation tank was then placed in a constant temperature incubator at 28°C for 18 hours;

[0161] S7. Tea liquid preparation is completed: After fermentation is completed, the fermented tea liquid is subjected to multi-dimensional measurements and sensory scoring.

[0162] After the above experimental preparation, an edible low-sugar fermented Pu'er tea was obtained, and the results of multi-dimensional measurements are as follows:

[0163]

[0164] The experimental results show that under the conditions of "tea-water ratio of 1:200, white sugar: sugar alcohol ratio of 2:3, lactobacillus inoculation of 5%, and fermentation time of 18h", the low-sugar fermented Pu'er tea beverage has a good taste and color, and the microbial fermentation is relatively ideal, but the acidity and bacterial growth can be further optimized by adjusting the inoculation amount and fermentation time. Specifically, the low-sugar fermented Pu'er tea beverage produced has a moderate pH value, a high number of bacteria, an appropriate lactic acid content, a low dissolved oxygen concentration, a sufficient matrix concentration, a good taste, and a light brown color. The sensory indicators show that the product has a strong flavor, moderate sweetness and sourness, and no toxins and impurities were detected, and the fermentation process was normal. In the end, the sensory score was 86.2 points, showing a relatively high consumer acceptance.

[0165]

[0166] This proves that the preparation method of low-sugar fermented Pu'er tea beverage is suitable for the production of Pu'er tea Lactobacillus fermented beverage, and the product quality and safety have reached the expected goals.

[0167] Conclusion: Under the conditions of tea-water ratio of 1:200, white sugar:erythritol ratio of 2:3, lactobacillus inoculation of 5%, and fermentation time of 18 hours, the sensory score of Pu'er tea low-sugar fermented beverage reached 86.2 points, showing high consumer acceptance. The beverage has moderate sweetness and high acidity, rich tea aroma, refreshing taste, and elegant and translucent color. The microbial fermentation was good, the pH value was 3.9, the bacteria grew vigorously, and no odor appeared. After the process conditions were optimized, the Pu'er tea low-sugar fermented beverage produced performed well in taste and quality, had good market potential, and could be used as a suboptimal preparation solution.

[0168] Example 5 (Comparative Example) Specific preparation method with setting "tea-water ratio of 1:225, white sugar: sugar alcohol ratio of 1:4, lactobacillus inoculation amount of 6%, fermentation time of 20h"

[0169] In a specific embodiment, the sensory quality of the low-sugar fermented Pu'er tea beverage of the present invention is specifically tested according to a specific tea-to-water ratio, sugar addition amount, Lactobacillus inoculation amount and fermentation time.

[0170] In this embodiment, the experimental materials include Pu'er tea (Taiwan tea), white sugar, erythritol, and Lactobacillus bulgaricus; the experimental equipment includes a fermentation tank, a constant temperature incubator, an electronic balance, a pH meter, and a sensory scoring table.

[0171] In this embodiment, the basic fermentation conditions are as follows: inoculation amount 4%, sugar addition amount 5%, fermentation temperature 28°C, fermentation time 20h, citric acid addition amount 0.25%; other variable parameters are tea-water ratio of 1:225, white sugar: sugar alcohol ratio of 1:4, and Lactobacillus inoculation amount of 6%.

[0172] The implementation process of this embodiment is completely consistent with the process of embodiment 1, only the ratio and content of the preparation materials are adjusted, and the specific implementation steps are as follows:

[0173] S1. Raw material selection: select Pu'er tea with better quality and less impurities;

[0174] S2. Extraction: prepare tea liquid in a ratio of 1:225 between tea and water; then boil the Pu'er tea liquid in boiling water at 80°C for 10 minutes;

[0175] S3. Filtration: Use a filter to filter out the tea residue to obtain a tea extract for later use;

[0176] S4. Preparation: The filtered tea extract was prepared according to the following ratios;

[0177] 4.1 Amount of sugar added: The ratio of white sugar to sugar alcohol is 1:4, that is, white sugar is 1% and sugar alcohol is 4%;

[0178] 4.2 Amount of citric acid added: 25% of Pu'er tea liquid;

[0179] S5. Canning and sterilization: Can the prepared tea in glass bottles and sterilize in a boiling water bath for 10 minutes;

[0180] S6. Inoculation and fermentation: The tea liquid was divided into a fermentation tank and inoculated with Lactobacillus bulgaricus at a ratio of 6%; the fermentation tank was then placed in a constant temperature incubator at 28°C for 20 hours;

[0181] S7. Tea liquid preparation is completed: After fermentation is completed, the fermented tea liquid is subjected to multi-dimensional measurements and sensory scoring.

[0182] After the above experimental preparation, an edible low-sugar fermented Pu'er tea was obtained, and the results of multi-dimensional measurements are as follows:

[0183]

[0184] The experimental results show that under the conditions of "tea-water ratio of 1:200, white sugar: sugar alcohol ratio of 2:3, lactobacillus inoculation of 5%, and fermentation time of 18h", the low-sugar fermented Pu'er tea beverage has a good taste and color, and the microbial fermentation is relatively ideal, but the acidity and bacterial growth can be further optimized by adjusting the inoculation amount and fermentation time. Specifically, the low-sugar fermented Pu'er tea beverage produced has a moderate pH value, a high number of bacteria, an appropriate lactic acid content, a low dissolved oxygen concentration, a sufficient matrix concentration, a good taste, and a light brown color. The sensory indicators show that the product has a strong flavor, moderate sweetness and sourness, and no toxins and impurities were detected, and the fermentation process was normal. In the end, the sensory score was 86.6 points, showing a relatively high consumer acceptance.

[0185]

[0186] This proves that the preparation method of low-sugar fermented Pu'er tea beverage is suitable for the production of Pu'er tea Lactobacillus fermented beverage, and the product quality and safety have reached the expected goals.

[0187] Conclusion: Under the conditions of tea-water ratio of 1:225, white sugar: erythritol ratio of 1:4, lactobacillus inoculation of 6%, and fermentation time of 20 hours, the sensory score of Pu'er tea low-sugar fermented beverage reached 86.6 points, showing a certain degree of consumer acceptance. The beverage has low sweetness and high acidity, rich tea aroma, refreshing taste, and light and translucent color. The microbial fermentation was good, the pH value was 3.7, the bacteria grew vigorously, and no odor appeared. Although the acidity under this process condition is high, further optimization needs to be considered to balance the sweet and sour taste and improve consumer acceptance.

[0188] Furthermore, the above-mentioned preparation methods of the present invention are all subjected to single-factor experimental design, which is as follows:

[0189] According to the above five groups of specific embodiments, the present invention uses a single factor experimental design to investigate the influence of various factors on the sensory quality of low-sugar fermented Pu'er tea beverages. Specifically, in determination 1, the inoculation amount is 4%, the sugar addition amount is 5%, the fermentation temperature is 28°C, the fermentation time is 16h, and the citric acid addition amount is 0.25% as the basic fermentation conditions of Pu'er tea beverages, and the inoculation amount of Lactobacillus bulgaricus is 2%, 3%, 4%, 5%, 6%; the white sugar addition amount is 5%, 4%, 3%, 2%, 1%, and the erythritol addition amount is 0%, 1%, 2%, 3%, 4%; the fermentation time is 12, 14, 16, 18, 20h; the tea-water ratio is 1:125, 1:150, 1:175, 1:200, 1:225 as variables to conduct a single factor experiment to investigate the influence of various factors on the sensory quality of low-sugar fermented Pu'er tea beverages.

[0190] Specifically, the single factor experimental design is completely consistent with Examples 1-5, and the specific experimental factors and parameters are as follows:

[0191] (1) Tea:water ratio: 1:125, 1:150, 1:175, 1:200, 1:225;

[0192] (2) Sugar addition (to meet low sugar requirements: sugar addition ≤ 5 g / 100 ml);

[0193] (3) Lactobacillus inoculum amount: 2%, 3%, 4%, 5%, 6%;

[0194] (4) Fermentation time: 12h, 14h, 16h, 18h, 20h.

[0195] Specifically, the following is a table of factors and levels for a single-factor experiment:

[0196]

[0197] Specifically, based on the principle of microbial fermentation, the mechanism for setting the above single-factor experimental parameters is as follows:

[0198] First, the tea-water ratio (g / ml) determines the concentration of the tea soup. For example, a higher tea-water ratio (such as 1:125) means that the tea soup is thicker and contains more tea polyphenols, amino acids and other ingredients; a lower tea-water ratio (such as 1:225) means that the tea soup is thinner. The concentration of tea soup affects the growth environment and metabolic activity of lactic acid bacteria. Higher concentrations of tea polyphenols and other ingredients have a certain inhibitory effect on Lactobacillus bulgaricus, while an appropriate tea-water ratio is conducive to the reproduction of Lactobacillus bulgaricus and the production of metabolites.

[0199] Second, the ratio of white sugar: sugar alcohol (%) determines the type and amount of fermentable sugars during the fermentation process; different sugar ratios have a direct impact on the generation and flavor of fermentation products. The ratio of white sugar (sucrose) and sugar alcohol (such as erythritol) affects the metabolic pathway and products of Lactobacillus bulgaricus. White sugar is easily metabolized by lactic acid bacteria to produce lactic acid, providing sourness and preservative effects; sugar alcohols are not easily metabolized, but can provide sweetness, balance sourness, and enhance taste. Different sugar ratios have a direct impact on the generation and flavor of fermentation products.

[0200] Third, the inoculation amount (%) of Lactobacillus bulgaricus determines the number of bacteria at the beginning of fermentation. For example, a higher inoculation amount (such as 5%) means more lactic acid bacteria, which can quickly dominate the fermentation process; a lower inoculation amount (such as 1%) requires more time to reproduce to reach the same number of bacteria. The appropriate inoculation amount helps to quickly start fermentation, inhibit the growth of miscellaneous bacteria, improve fermentation efficiency and product stability; conversely, too high or too low an inoculation amount will affect the final fermentation effect and product quality.

[0201] Fourth, the fermentation time (h) determines the time for Lactobacillus bulgaricus to carry out glycolysis and other metabolic activities; different fermentation times will result in different types and concentrations of fermentation products. Longer fermentation time (such as 20 hours) can allow Lactobacillus bulgaricus to fully metabolize, produce more lactic acid and other metabolites, and improve the sourness and flavor level; shorter fermentation time (such as 12 hours) produces fewer metabolites and a more single flavor.

[0202] Specifically, based on the Pu'er tea fermentation principle, the mechanism for setting the above single factor experimental parameters is as follows:

[0203] First, in the fermentation of Pu'er tea, a higher tea-to-water ratio (strong tea soup) can retain more tea flavor and nutrients, but may make the tea soup too bitter; a lower tea-to-water ratio (dilute tea soup) has a lighter flavor but a softer taste. Finding the right tea-to-water ratio can balance the concentration and taste of the tea soup, so that the tea beverage fermented with Lactobacillus bulgaricus retains the unique flavor of Pu'er tea and has a soft sour taste.

[0204] Secondly, in the fermentation of Pu'er tea, different sugar ratios not only affect the bacterial metabolism during the fermentation process, but also directly determine the sweet and sour balance of the final beverage and optimize the taste. White sugar increases the fermentation substrate and improves the fermentation efficiency; sugar alcohols provide sweetness and are not fermented.

[0205] Third, in the fermentation of Pu'er tea, the appropriate amount of lactobacillus inoculation can ensure the stability and uniformity of the fermentation process and improve the quality and consistency of the finished product. A reasonable inoculation amount of Lactobacillus bulgaricus can improve the safety and functionality of fermented tea and inhibit undesirable fermentation.

[0206] Fourthly, in the fermentation of Pu'er tea, the fermentation time affects the transformation of the substances contained in the tea and the formation of the flavor. Finding the appropriate fermentation time can fully ferment the polyphenols and amino acids in the tea, forming a unique flavor and taste, and improving the quality of Pu'er tea fermented beverages.

[0207] Furthermore, according to the aforementioned preparation methods of the present invention, single-factor experimental design was carried out, the influence degree of different factors was determined for the single-factor experiment, and four factors, namely, tea-to-water ratio, inoculation amount, sugar addition amount, and fermentation time, were selected as the investigation objects. With sensory score as the evaluation index, a four-factor three-level response surface experiment was designed as an example for all 13 measurements.

[0208] Example 6 (Comparative Example) Comparison of the process and taste of the low-sugar fermented Pu'er tea of ​​the present invention and common Kombucha

[0209] In a specific embodiment, a kombucha having antioxidant, digestive health, antibacterial and antiviral, immune regulation and metabolic regulation mechanisms is prepared according to a typical kombucha method, and the process is compared with the low-sugar fermented Pu'er tea of ​​the present invention.

[0210] Specifically, in one embodiment, the materials required for kombucha include: green tea, black tea and dark tea are selected as three different types of kombucha; in order to be consistent with the sugar source described in the present invention, white sugar is selected as the main nutrient source for fermentation (in fact, kombucha can also use brown sugar or honey); the water source uses mineral water consistent with the present invention; the symbiotic bacteria and yeast strains (SCOBY) are obtained through conventional preparation in accordance with the food industry; the starter liquid is fermented commercially available kombucha to help start the fermentation process; and there are clean glass jars and coffee filter paper.

[0211] Specifically, the preparation steps of three different groups of kombucha are as follows:

[0212] S1. Boil water and brew tea: Heat 1 liter of water in a large pot until it boils, then add 4-6 teaspoons of tea leaves (choose one group each of green tea, black tea and dark tea) and soak for 10-15 minutes; filter out the tea leaves and pour the tea into a clean glass container;

[0213] S2. Add sugar source: Add 1 cup of white sugar to the hot tea and stir until completely dissolved;

[0214] S3. Cooling: Cool the three sweet teas (green tea, black tea, and dark tea) to room temperature to prevent high temperatures from killing the microorganisms in the SCOBY.

[0215] S4. Add SCOBY and starter solution: Gently add SCOBY and 1-2 cups of starter solution. SCOBY and starter solution contain microorganisms with antibacterial, antiviral, immunomodulatory and metabolic regulating effects.

[0216] S5. Fermentation: Cover the container with a cloth and secure it with a rubber band to keep it breathable; place the container in a warm, cool place away from direct sunlight; the fermentation time is usually 7-14 days;

[0217] S6. Tasting and storage: After fermentation is complete, taste the kombucha for sweetness and sourness; pour the kombucha into a clean glass bottle and store in the refrigerator.

[0218] Specifically, the following points need to be noted when preparing the three different groups of kombucha: During the fermentation process, the SCOBY will float on the surface of the tea and grow new cakes, which is normal; fresh tea and sugar should be used each time a new batch of kombucha is made to ensure the activity of the fermentation flora; the taste and appearance of the kombucha should be checked regularly for any off-flavors or unusual colors.

[0219] Furthermore, three types of kombucha (green tea, black tea and dark tea) were subjected to microbial fermentation comparison with the low-sugar fermented Pu'er tea of ​​the present invention, as follows:

[0220]

[0221] Verification conclusion:

[0222] (1) The situation of three different kombucha: All use SCOBY, which includes acetic acid bacteria, lactic acid bacteria and yeast. These microorganisms work together to ferment the sugars in the tea into organic acids (such as acetic acid and lactic acid), ethanol and carbon dioxide. Although the basic composition of SCOBY is the same, the components in different types of tea (such as tea polyphenols and other organic compounds) may affect the growth and metabolic activities of microorganisms. Black tea and dark tea kombucha usually form thicker colloidal biofilms, which is related to their rich tea polyphenol content. Green tea kombucha usually forms a relatively thin biofilm due to its low tea polyphenol content. However, the rich antioxidants in green tea (such as catechins) can be metabolized by SCOBY microorganisms during the fermentation process, further enhancing the antioxidant properties of the beverage;

[0223] (2) The advantages of low-sugar fermented Pu'er tea in the present invention in microbial fermentation: First, low-sugar fermented Pu'er tea is usually fermented using specific lactic acid bacteria (such as Lactobacillus). Compared with SCOBY in kombucha, the use of a single or specific lactic acid bacteria strain can better control the fermentation process, reduce unpredictable fermentation products, and help maintain the consistency of product quality; second, low-sugar fermented Pu'er tea is more conservative in the use of sugar, and a lower sugar content means that the product has lower calories, reducing the calorie burden; third, the fermentation process of lactic acid bacteria can increase the content of probiotics in the beverage, which helps promote intestinal health.

[0224] Furthermore, the taste of three types of Kombucha (green tea, black tea and dark tea) was compared with the low-sugar fermented Pu'er tea of ​​the present invention, as follows:

[0225]

[0226] Verification conclusion:

[0227] (1) Taste analysis of the above four tea beverages: In terms of acidity, the three kombuchas have high acidity, which is suitable for consumers who like sour and refreshing taste; while the low-sugar fermented Pu'er tea has low acidity and is milder. In terms of sweetness, the sweetness of these four drinks is relatively low. Kombucha consumes a lot of sugar during the fermentation process; low-sugar fermented Pu'er tea has lower sweetness due to the less original sugar added. In terms of tea aroma and flavor, the tea aroma of green tea kombucha is the freshest, while the tea aroma of black tea kombucha and black tea kombucha is richer and more complex. Low-sugar fermented Pu'er tea retains the unique aged aroma and fermented flavor of Pu'er tea, and the overall flavor is milder.

[0228] (2) Advantages of the low-sugar fermented Pu'er tea of ​​the present invention: low-sugar fermented Pu'er tea mainly relies on lactobacillus for fermentation, has lower acidity and milder taste, and is suitable for consumers who do not like overly sour taste; the fermentation process is relatively short and mild, retaining the unique aged fragrance and flavor of Pu'er tea, and is suitable for consumers who like the traditional tea fragrance; low-sugar fermented Pu'er tea has less added sugar, and is suitable for consumers who need to control sugar intake, especially for diabetic patients or people who pay attention to healthy diet; the addition of lactobacillus helps promote digestive health and maintain the balance of intestinal flora, which is helpful for sub-healthy people.

[0229] Determination 1 Determination of the optimal tea-water ratio during extraction in the preparation method of the present invention

[0230] In multiple groups of specific embodiments, when extracting tea juice, 5g of Pu'er tea leaves are weighed, and boiling water is added at a tea-water ratio of 1:125, 1:150, 1:175, 1:200, and 1:225, and the tea is boiled and extracted at 80°C for 10 minutes. After the extraction is completed, the tea soup is filtered through a filter to obtain the tea soup. Five Pu'er tea tasters are invited to perform sensory evaluations on the color, aroma, and taste of the obtained tea soup, and the average of the scores is taken as the final score result. The higher the score, the better the quality of the tea extract. The difference in sensory scores of tea extracts with different tea-water ratios and the influence on the quality of the extract.

[0231]

[0232] The data obtained from the sensory evaluation showed that the tea-water ratio had an effect on the color, aroma and taste of the tea extract. Specifically, when the tea-water ratio was 1:175, the extract had the highest sensory score (61.8±1.92), with a difference of a, indicating that it was significantly different from the tea extracts with other tea-water ratios and had the best quality; when the tea-water ratio was 1:150 and 1:200, the extract had a higher sensory score (49.8±1.48 and 51.2±3.63, respectively), with a difference of b, indicating that its quality was good, but it was significantly different from the tea extract with a ratio of 1:175; when the tea-water ratio was 1:125 and 1:225, the extract had a lower sensory score (41.6±1.14 and 39.6±2.97, respectively), with a difference of c, indicating that its quality was poor, and the difference between the two was not significant.

[0233] Furthermore, the effect of the tea-water ratio on the tea concentration is as follows:

[0234]

[0235] Test conclusion 1: By controlling the tea-water ratio, the concentration of tea soup can be adjusted, thereby affecting the content and proportion of tea polyphenols, amino acids and caffeine. The tea soup with a tea-water ratio of 1:175 has a moderate concentration, which can fully extract the effective ingredients in tea leaves and produce the best color, aroma and taste. This balanced concentration makes the tea soup perform best in sensory scores, retaining the unique flavor of Pu'er tea and giving the tea soup a soft and rich taste, which is suitable for a wide range of consumer needs.

[0236] Furthermore, the effect of tea-water ratio on lactic acid bacteria fermentation is as follows:

[0237]

[0238] The optimal tea-water ratio (such as 1:175) can provide moderate tea polyphenols and nutrients, promote the growth and metabolism of Lactobacillus bulgaricus, generate rich fermentation products, bring balanced sourness and rich flavor levels, and ultimately improve the sensory quality of tea soup; however, the tea-water ratio of 1:150 and 1:200 has a better effect, but not as ideal as 1:175; the tea-water ratio of 1:125 and 1:225 has poor fermentation effect and sensory quality of tea soup due to too high or too low concentration. By optimizing the tea-water ratio, the overall quality of Pu'er tea fermented beverages can be significantly improved to meet the taste needs of consumers.

[0239] Furthermore, the influence of tea water on the quality of tea extract is as follows:

[0240]

[0241] The above determinations show that under the condition of high tea-water ratio of 1:125 (i.e., high-concentration tea soup), the concentration of active ingredients such as tea polyphenols is relatively high. Although these ingredients give the tea soup a strong antioxidant capacity and a dark appearance, they also bring a heavier bitterness, which inhibits the growth and metabolism of lactic acid bacteria and affects the production of fermentation products, thereby reducing the sensory score; while under the condition of a lower tea-water ratio (such as 1:150), a more moderate tea soup concentration is provided, and the tea polyphenol concentration is lower than the high tea-water ratio, so the bitterness is reduced, and the aroma and color are improved; and lactic acid bacteria can better carry out metabolic activities at a more appropriate concentration, produce an appropriate amount of fermentation products, and enhance the overall flavor of the tea soup. However, since the aroma and taste of the tea soup did not reach the best balance, the sensory score was still lower than the optimal tea-water ratio (1:175); and at a lower tea-water ratio (such as 1:225), the tea soup concentration is too low, resulting in insufficient concentrations of tea polyphenols and other flavor substances. Although the bitterness is low, the aroma and flavor of the tea soup are not strong enough, the metabolic activity of lactic acid bacteria is low, the amount of fermentation products produced is small, and the overall sensory quality is poor.

[0242] The above determination further proves that different tea-water ratios have a significant effect on the quality of tea extract and the sensory score obtained with a tea-water ratio of 1:175 is the highest. Through the above comprehensive analysis, it can be concluded that under the conditions of a fixed extraction temperature of 80°C and an extraction time of 10 minutes, the optimal extraction tea-water ratio of tea extract is 1:175 (g / ml). At a tea-water ratio of 1:175, the concentrations of tea polyphenols and other active ingredients reach the best balance, which will not excessively inhibit the growth of Lactobacillus bulgaricus, nor will it cause a bland flavor due to insufficient concentration. Lactobacillus bulgaricus can be fully metabolized to produce rich fermentation products such as lactic acid. These metabolites not only bring a refreshing sour taste, but also enhance the aroma and layering of the tea soup. The tea soup presents a balanced color, aroma and taste, and the overall sensory experience is the best, so it has the highest sensory score.

[0243] Determination 2 Determination of the amount of white sugar added in the preparation method of the present invention

[0244] In multiple groups of specific embodiments, under the premise of fixing the tea-water ratio of 1:175 to obtain the tea extract, the Pu'er tea is divided into 5 parts, and 0.25% of citric acid is added to each part, and then white sugar is added to the tea extract according to the different gradients of 5%, 4%, 3%, 2%, and 1% set. Because low-sugar fermented tea beverages require the sugar addition amount to be ≤5g / 100ml, the corresponding erythritol 0%, 1%, 2%, 3%, and 4% are added according to the corresponding white sugar addition amount to adjust its sweet taste. Five Pu'er tea tasters performed sensory scoring of the taste of the obtained tea soup according to Table 4, and then took the average of the scores as the final scoring result. The higher the score, the better the taste of the tea soup. The difference in sensory scoring of the taste of tea soup and the influence of different amounts of white sugar addition on the taste.

[0245]

[0246] Measurement result 1: There was a significant difference in the taste sensory scores between the addition of 1% white sugar and the addition of 4% white sugar, but the taste sensory score of the white sugar addition of 1% was the lowest, which was 8.40, while the taste sensory score of the white sugar addition of 4% was the highest, which was 28.00, and it was significantly different from the taste sensory scores of the white sugar additions of 1%, 2%, 3%, and 5%.

[0247] Furthermore, the expected and differential analysis of the effect of added sugar on taste scores is as follows:

[0248]

[0249] Test conclusion 2: By adjusting the ratio of white sugar and erythritol, the taste and sensory score of tea soup can be significantly affected. Although 5% white sugar provides enough sweetness, the introduction of erythritol reaches the best balance point under the conditions of 3% white sugar and 2% erythritol, which can maintain the rich layers of sweetness without making the sugar content too high. This balance can meet the low-sugar requirements while enhancing the healthy image of the beverage. With the reduction of white sugar and the increase of erythritol, the natural sense of sweetness is improved, but too low sugar content leads to a bland overall taste and a decrease in the score. The best sweetness blending requires finding a balance between taste, healthiness and sensory enjoyment.

[0250] Furthermore, the effects of different amounts of added white sugar on the taste of tea are as follows:

[0251]

[0252] Test result 3: Under the conditions of a fixed tea-water ratio of 1:175 and 0.25% citric acid addition, the optimal amount of white sugar added is 4%, at which the sensory score is the highest (28.00), and the sweet-sour balance of the tea soup is the best. The amount of erythritol added should be controlled at around 1% to provide natural sweetness without increasing excessive sugar intake. Too much or too little sugar addition will affect the overall taste of the tea soup, so maintaining moderate sweetness is an important factor in optimizing the taste of the tea soup.

[0253] Different sugar additions have a significant impact on the taste of tea soup, and the sensory score obtained by adding 4% white sugar is the highest. Through the above comprehensive analysis, it can be concluded that under the premise of a fixed tea-water ratio of 1:175 and a fixed citric acid addition of 0.25%, the optimal amount of white sugar added to the tea soup is 4%, and the amount of erythritol added is 1%, with a balance of sourness and sweetness, a refreshing taste of the tea soup, and a harmonious sourness and sweetness. The sweetness under this ratio is just right, which can balance the sourness in the tea soup and make the overall taste optimal.

[0254] Determination of the amount of Lactobacillus bulgaricus added and the fermentation time in the preparation method of the present invention

[0255] In multiple groups of specific embodiments, under the premise of fixing the tea-water ratio, the amount of white sugar added, the amount of citric acid added, and the fermentation time, the experiment of the effect of the amount of lactobacillus added on the sensory quality of the final product is designed. When the fermentation time is 12h, 14h, 16h, 18h, and 20h, 5 groups of experiments with different amounts of lactobacillus added are respectively carried out, with the sensory score as an indicator, and the average value of the obtained sensory score as the final result, observing the law of the effect of different amounts of lactobacillus added on the sensory score of the finished product under the same fermentation time, so as to determine the best amount of lactobacillus added; observing the law of the effect of the same amount of lactobacillus added on the sensory score of the finished product under different fermentation times and the change of the value, so as to determine the best fermentation time.

[0256] Furthermore, the effect of the amount of lactobacillus added on the sensory score of tea soup under a fermentation time of 12 hours is shown in Figure 1. Figure 1 shows the effect of the amount of lactobacillus added on the sensory score of tea soup under a fermentation time of 12 hours, with the tea-water ratio, the amount of white sugar added, the amount of citric acid added and the fermentation time fixed.

[0257] The fermentation time was 12h, and the effect of the amount of lactobacillus added on the sensory score was as follows: when the amount of lactobacillus added was 2%, the sensory score was about 55; at this time, the number of lactobacilli may not be enough to significantly change the fermentation flavor of the tea soup, resulting in a low score. When the amount of lactobacillus added was 3%, the sensory score increased to nearly 70, indicating that the increase in the number of lactobacilli improved the fermentation process and flavor. When the amount of lactobacillus added was 4%, the sensory score was the highest, about 75; at this amount, the activity and metabolism of lactobacilli were the most moderate, the most abundant fermentation products were generated, the sourness and aroma of the tea soup were improved, and the best flavor balance was achieved. When the amount of lactobacillus added was 5%, the score dropped to about 65; too much lactobacillus may cause too strong sourness or other undesirable fermentation products to accumulate, affecting the overall balance and taste of the tea soup. When the amount of lactobacillus added was 6%, the sensory score further dropped to nearly 50; at this time, the excessive number of lactobacilli may lead to some negative effects in the fermentation process, such as excessive acidification or unpleasant aroma, which significantly reduced the sensory quality of the tea soup.

[0258] Determination conclusion 1: When the fermentation time is fixed at 12h, the sensory score of the tea soup increases with the increase of the amount of lactobacillus added, reaching a peak when the amount is 4%, and then it decreases. The average sensory score of the lactobacillus added at 2% is 50.20; the average sensory score of the lactobacillus added at 3% is 61.20; the average sensory score of the lactobacillus added at 4% is 72.30; the average sensory score of the lactobacillus added at 5% is 60.00; the average sensory score of the lactobacillus added at 6% is 49.40. Under the condition of 12 hours of fermentation, when the lactobacillus added at 4%, the sensory score of the tea soup is the highest, indicating that the fermentation effect is the best under this ratio, and the generated flavor substances are the most abundant and balanced.

[0259] Further, the effect of the amount of lactobacillus added on the sensory score of tea soup under a fermentation time of 14 hours is shown in Figure 2. Figure 2 shows the effect of different amounts of lactobacillus added on the sensory score of tea soup under a fermentation time of 14 hours; the horizontal axis of Figure 2 represents the amount of lactobacillus added (%), and the vertical axis represents the average value of the sensory score.

[0260] When the fermentation time is 14 hours, the sensory score of the tea soup shows a trend of first rising and then falling with the change of the amount of lactobacillus added. Specifically, when the amount of lactobacillus added is 2%, the sensory score is 60.00. This is because at this amount, the number of lactobacilli is small, the fermentation process may not be sufficient, and the fermentation products produced are small, so the sourness and flavor substances of the tea soup are not rich enough, and the sensory score is low. Specifically, when the amount of lactobacillus added is 3%, the sensory score is 69.80. This is because as the amount of lactobacillus added increases, the fermentation is more sufficient, the concentration of sourness and other flavor substances increases, the overall flavor and taste of the tea soup are improved, and the sensory score is significantly improved. Specifically, the amount of lactobacillus added is 4%, and the sensory score is 81.20. This is because the amount of lactobacillus added reaches the optimal balance point; sufficient lactobacillus makes the fermentation process reach the optimal state, generates rich lactic acid and other flavor substances, and the sour-sweet balance and overall taste of the tea soup reach the best, with the highest sensory score. Specifically, when the amount of lactobacillus added is 5%, the sensory score is 68.10. This is because as the amount of lactobacillus added continues to increase, the sensory score of the tea soup begins to decline. The possible reason is that too much lactobacillus leads to excessive fermentation, producing excessive sourness and other undesirable metabolites, which affects the taste balance of the tea soup. Specifically, when the amount of lactobacillus added is 6%, the sensory score is 59.20. This is because at this amount of addition, the sensory score of the tea soup drops to the lowest, close to the starting level. This may be because a high concentration of lactobacillus not only causes excessive acidification, but may also generate unpleasant flavor substances or change the texture of the tea soup, significantly reducing the sensory quality of the tea soup.

[0261] Determination conclusion 2: When the fermentation time is fixed at 14h, the sensory score of the tea soup increases with the increase of the amount of lactobacillus added, reaching a peak when the amount added is 4%, and then decreases. The average sensory score of the lactobacillus added at 2% is 60.00; the average sensory score of the lactobacillus added at 3% is 69.80; the average sensory score of the lactobacillus added at 4% is 81.20; the average sensory score of the lactobacillus added at 5% is 68.10; the average sensory score of the lactobacillus added at 6% is 59.20. Under the condition of a fermentation time of 14 hours, the addition of Lactobacillus at 4% is the best choice. At this time, the sensory score of the tea soup is the highest (81.20), showing the best flavor balance and taste. In actual production, controlling the amount of lactobacillus added can significantly improve the market competitiveness and consumer satisfaction of the product by accurately adjusting the fermentation parameters.

[0262] Further, the effect of the amount of lactobacillus added on the sensory score of tea soup under a fermentation time of 16 hours is shown in Figure 3. According to Figure 3, the effect of different amounts of lactobacillus added on the sensory score of tea soup under a fermentation time of 16 hours; the horizontal axis of Figure 3 represents the amount of lactobacillus added (%), and the vertical axis represents the average value of the sensory score.

[0263] When the fermentation time is 16 hours, the sensory score of the tea soup shows a trend of first rising and then falling with the change of the amount of lactobacillus added. Specifically, when the amount of lactobacillus added is 2%, the sensory score is 70.20. This is because at this amount, the number of lactobacilli is small, and the fermentation process may not be sufficient, resulting in insufficient sourness and fermentation products of the tea soup, and the sensory score is at a low level. Specifically, when the amount of lactobacillus added is 3%, the sensory score is 81.10. This is because with the increase in the amount of lactobacillus added, the fermentation is more sufficient, more lactic acid and other flavor substances are produced, the sourness and aroma of the tea soup are significantly enhanced, and the sensory score is improved. Specifically, when the amount of lactobacillus added is 4%, the sensory score is 91.20. This is because the sensory score of the tea soup reaches the highest at this amount of lactobacillus added. This shows that this amount provides the best fermentation conditions, generates rich lactic acid and other flavor substances, and makes the flavor of the tea soup reach the best balance and richness. Specifically, when the amount of lactobacillus added is 5%, the sensory score is 80.10. This is because the sensory score begins to decrease after further increasing the amount of lactobacillus added; and the excessive amount of lactobacillus leads to excessive fermentation, too strong sour taste or the production of other undesirable flavor substances, which destroys the flavor balance of the tea soup. Specifically, when the amount of lactobacillus added is 6%, the sensory score is 69.00. This is because at this amount of addition, the sensory score drops to the lowest; and then due to the high concentration of lactobacillus, the sour taste is too strong or other undesirable fermentation products accumulate, which significantly reduces the sensory quality of the tea soup.

[0264] Determination conclusion 3: When the fermentation time is fixed at 16h, the sensory score of the tea soup increases with the increase of the amount of lactobacillus added, reaching a peak when the addition amount is 4%, and then it decreases. The average sensory score of the lactobacillus addition amount of 2% is 70.20; the average sensory score of the lactobacillus addition amount of 3% is 81.10; the average sensory score of the lactobacillus addition amount of 4% is 91.20; the average sensory score of the lactobacillus addition amount of 5% is 80.10; the average sensory score of the lactobacillus addition amount of 6% is 69.00. Under the condition of a fermentation time of 16 hours, the addition of 4% lactobacillus is the best choice, with the highest sensory score (91.20), indicating that the flavor balance, sweetness and sourness and overall taste of the tea soup are at their best at this time. A moderate addition amount can promote the metabolic activity of lactic acid bacteria, generate an appropriate amount of fermentation products, and enhance the flavor level and complexity of the tea soup. Excessive addition may lead to the accumulation of undesirable flavor substances and affect the overall sensory quality. The preparation method of the present invention optimizes the sensory quality of the fermented tea beverage by accurately controlling the addition amount of lactobacillus and the fermentation time, thereby improving the market competitiveness and consumer acceptance of the product.

[0265] Further, the effect of the amount of lactobacillus added on the sensory score of tea soup under a fermentation time of 18 hours is shown in Figure 4. Figure 4 shows the effect of different amounts of lactobacillus added on the sensory score of tea soup under a fermentation time of 18 hours; the horizontal axis of Figure 4 represents the amount of lactobacillus added (%), and the vertical axis represents the average value of the sensory score.

[0266] When the fermentation time is 18 hours, the sensory score of the tea soup rises first and then falls with the increase of the amount of lactobacillus added, reaching the highest point when the amount of lactobacillus added is 4%. Specifically, when the amount of lactobacillus added is 2%, the sensory score is 61.20. This is because the low amount of lactobacillus added leads to insufficient fermentation, less lactic acid and other flavor substances are generated, resulting in insufficient sourness and flavor of the tea soup, and a low sensory score. Specifically, when the amount of lactobacillus added is 3%, the sensory score is 71.00. This is because increasing the amount of lactobacillus added makes the fermentation process more complete, generates more flavor substances such as lactic acid, enhances the sourness and aroma of the tea soup, and significantly improves the sensory score. Specifically, when the amount of lactobacillus added is 4%, the sensory score is 80.90. This is because the number of lactobacilli reaches the best balance, the fermentation process is most ideal, and rich lactic acid and other metabolites are generated, so that the sour and sweet balance, aroma and overall flavor of the tea soup reach the best state, and the sensory score is the highest. Specifically, when the amount of lactobacillus added is 5%, the sensory score is 74.10. This is because the sensory score begins to decrease after further increasing the amount of lactobacillus added; excessive lactobacillus may lead to excessive fermentation, excessive sourness or the generation of other undesirable flavor substances, which destroys the overall flavor balance of the tea soup. Specifically, when the lactobacillus addition amount is 6%, the sensory score is 63.10. This is because the high lactobacillus addition further reduces the sensory score because too much lactobacillus leads to extreme fermentation conditions, such as over-acidification, producing unpleasant taste or texture changes, which significantly reduces the sensory quality of the tea soup.

[0267] Determination conclusion 4: When the fermentation time is fixed at 18h, the sensory score of the tea soup increases with the increase of the amount of lactobacillus added, reaching a peak when the amount is 4%, and then decreasing. The average sensory score of the lactobacillus added at 2% is 61.20; the average sensory score of the lactobacillus added at 3% is 71.00; the average sensory score of the lactobacillus added at 4% is 80.90; the average sensory score of the lactobacillus added at 5% is 74.10; the average sensory score of the lactobacillus added at 6% is 63.10. Under the condition of 18 hours of fermentation, when the lactobacillus is added at 4%, the sensory score is the highest (80.90), indicating that the flavor of the tea soup is the best at this time, and the sourness, sweetness, aroma and overall taste are optimal. The addition of an appropriate amount of lactobacillus helps to produce an appropriate amount of lactic acid and other beneficial fermentation products, while too much lactobacillus may lead to over-fermentation, affecting the flavor balance and quality of the tea soup.

[0268] Further, the effect of the amount of lactobacillus added on the sensory score of tea soup under a fermentation time of 20 hours is shown in Figure 5. According to Figure 5, the effect of different amounts of lactobacillus added on the sensory score of tea soup under a fermentation time of 20 hours; the horizontal axis of Figure 5 represents the amount of lactobacillus added (%), and the vertical axis represents the average value of the sensory score.

[0269] When the fermentation time is 20 hours, the sensory score of the tea soup shows a trend of first rising and then falling with the change of the amount of lactobacillus added, reaching the highest point when the amount of lactobacillus added is 4%. Specifically, when the amount of lactobacillus added is 2%, the sensory score is 49.40. This is because the amount of lactobacillus added is low and the fermentation is insufficient, resulting in insufficient production of lactic acid and other fermentation products in the tea soup, insufficient sourness and flavor, and a low sensory score. Specifically, when the amount of lactobacillus added is 3%, the sensory score is 61.10. This is because increasing the amount of lactobacillus added makes the fermentation process more complete, produces more lactic acid and other flavor substances, enhances the sourness and overall flavor of the tea soup, and significantly improves the sensory score. Specifically, when the amount of lactobacillus added is 4%, the sensory score is 69.90. This is because the sensory score reaches the highest when the amount of lactobacillus added is 4%, indicating that the fermentation process is optimal under this amount of addition, and an appropriate amount of lactic acid and other fermentation products are generated, so that the sweet and sour balance and overall flavor of the tea soup reach the best state. Specifically, when the amount of Lactobacillus added was 5%, the sensory score was 63.10. This is because the sensory score began to decrease after the amount of Lactobacillus added was further increased; excessive Lactobacillus may lead to excessive fermentation, excessive sourness or the generation of other undesirable flavor substances, which destroys the overall balance and flavor of the tea soup. Specifically, when the amount of Lactobacillus added was 6%, the sensory score was 56.40. This is because the high amount of Lactobacillus added led to a significant decrease in the sensory score; and because excessive Lactobacillus led to extreme fermentation, excessive acidification or undesirable fermentation products were produced, which significantly affected the sensory quality of the tea soup.

[0270] Determination conclusion 5: When the fermentation time is fixed at 20h, the sensory score of the tea soup increases with the increase of the amount of lactobacillus added, reaching a peak when the amount added is 4%, and then it decreases. The average sensory score of the lactobacillus added at 2% is 49.40; the average sensory score of the lactobacillus added at 3% is 61.10; the average sensory score of the lactobacillus added at 4% is 69.90; the average sensory score of the lactobacillus added at 5% is 63.10; the average sensory score of the lactobacillus added at 6% is 56.40. Under the condition of a fermentation time of 20 hours, the addition of 4% lactobacillus is the best choice, with the highest sensory score (69.90), indicating that the flavor of the tea soup is the best at this time, and the sourness and sweetness and overall taste are optimal; the moderate addition of lactobacillus can balance the production of lactic acid and other fermentation products, and improve the sensory quality of the tea soup. By precisely controlling these parameters, the flavor and market competitiveness of the product can be significantly improved.

[0271] Further, it is known that when lactobacillus addition is 2%, the sensory score values ​​of fermentation duration 12h, 14h, 16h, 18h, 20h are 50.20, 61.20, 72.30, 60.00, 49.40 respectively. The sensory score increases with the increase of fermentation duration, reaches the highest when the fermentation duration arrives 16h, and then decreases therewith. When lactobacillus addition is 3%, the sensory score values ​​of fermentation duration 12h, 14h, 16h, 18h, 20h are 60.00, 69.80, 81.20, 68.10, 59.20 respectively. The sensory score increases with the increase of fermentation duration, reaches the highest when the fermentation duration arrives 16h, and then decreases therewith. When the amount of lactobacillus added was 4%, the sensory scores at fermentation times of 12h, 14h, 16h, 18h, and 20h were 70.20, 81.10, 91.20, 80.10, and 69.00, respectively. The sensory score increased with the increase of fermentation time, reached the highest when the fermentation time reached 16h, and then decreased. When the amount of lactobacillus added was 5%, the sensory score at fermentation times of 12h, 14h, 16h, 18h, and 20h was 61.20, 71.00, 80.90, 74.10, and 63.10, respectively. The sensory score increased with the increase of fermentation time, reached the highest when the fermentation time reached 16h, and then decreased. When the amount of lactobacillus added was 6%, the sensory scores of fermentation time 12h, 14h, 16h, 18h, 20h were 49.40, 61.10, 69.90, 63.10, 56.40 respectively. The sensory score increased with the increase of fermentation time, reaching the highest when the fermentation time reached 16h, and then decreased. The analysis may be due to the long fermentation time, excessive reproduction of lactobacillus, strong metabolic capacity, and excessive acid production, resulting in poor product taste and poor acceptance. When the fermentation time is too short, lactobacillus reproduces less, has weak metabolic capacity, produces less acid, and lacks fermentation flavor. It can be concluded that when the amount of lactobacillus added is fixed and the fermentation time is 16h, the sensory score is the highest and the difference between it and other fermentation times is more significant. Therefore, the optimal fermentation time for selecting low-sugar fermented tea beverage is 16h.

[0272] Based on the above analysis, it can be seen that under the premise of a fixed fermentation time, all five figures show that the sensory score of tea soup increases with the increase in the amount of lactobacillus added, reaching a peak when the addition amount is 4%, and then decreases. The analysis may be due to the fact that the lactic acid bacteria inoculation amount is too low, the acid production is low, and the fermentation flavor is insufficient; while the inoculation amount is too high, the acid production is too much, resulting in poor product taste and poor acceptance. When the fermentation time is fixed and the lactobacillus addition amount is 4%, the sensory score is the highest and the difference between it and other addition amounts is significant. Therefore, the optimal inoculation amount of lactobacillus is selected as 4%.

[0273] Conclusion: The optimal conditions for each single factor were finally determined to be a tea-water ratio of 1:175, 4% added sugar, 4% added lactobacillus, and a fermentation time of 16 h.

[0274] Determination 4 Analysis of the results of the response surface optimization of the optimal process for low-sugar fermented tea beverage in the preparation method of the present invention

[0275] In multiple specific embodiments, the optimal production process parameters of low-sugar fermented tea beverages are determined by response surface optimization method to improve the sensory score and consumer acceptance of the product. The specific response surface experiment uses a central composite design (CCD) to design the experimental scheme; it can effectively evaluate the impact of multiple independent variables on the response variable.

[0276]

[0277] Specifically, this embodiment uses response surface optimization technology to find out the key process parameters that affect the sensory quality of low-sugar fermented tea beverages and determine the best combination. The previous low-sugar fermented Pu'er tea preparation method is completely consistent with Example 1, and 2-5 groups of examples (control examples) are completed according to different ratios. The specific steps of the response surface optimization experiment are as follows:

[0278] S1. Tea soup preparation: Pu'er tea (Taidi tea) was selected, and tea soup was configured according to the tea-water ratio (150, 175, 200 g / ml) of different experimental settings; the tea was brewed with boiling water and kept at a constant temperature for 10 minutes to obtain a basic tea juice;

[0279] S2. Tea preparation: add a set ratio of white sugar (3%, 4%, 5%) and 0.25% citric acid to the tea juice; add different amounts of Lactobacillus strains (3%, 4%, 5%) according to the response surface experimental design and stir evenly;

[0280] S3. Tea soup fermentation: The prepared tea juice was fermented at a set fermentation time (14, 16, 18 hours) and the temperature was controlled at 30°C; the prepared tea soup was used for the next response surface optimization analysis;

[0281] S4. Tea soup data analysis: Use multiple regression analysis and analysis of variance (ANOVA) to analyze the independent variables (process parameters) and obtain the results that affect the response variables (sensory scores) (such as determinations 1-3);

[0282] 4.1 Multiple regression analysis: Establish a mathematical model between sensory score (E) and each process parameter (A, B, C, D);

[0283] 4.2 Analysis of variance (ANOVA): evaluate the significance and goodness of fit of the model and determine which factors significantly affect the sensory scores;

[0284] S5. Response surface optimization of tea soup: Use optimization software (such as Design-Expert or Minitab) to analyze the response surface model and determine the best combination of process parameters that can maximize the sensory score.

[0285] S6. Verification and application of response surface optimization results: verification using laboratory product preparation and small-batch food industry production.

[0286] 6.1 Laboratory verification: Repeat the best parameter combination under laboratory conditions to verify the optimization effect.

[0287] 6.2 Application in production: Apply the optimized process parameters to the production line and continuously monitor the sensory quality and stability of the product during batch production.

[0288] S7. Find the best low-sugar fermentation process for Pu'er tea: Under this process condition, the sensory score of the tea beverage is expected to be the highest, and the sour-sweet balance, flavor and taste of the product are optimal.

[0289]

[0290] Furthermore, the specific steps of multiple regression analysis in the response surface optimization experiment are as follows:

[0291] S1. Collect experimental data: including the independent variables (A, B, C, D) and response variable (E) data of each experimental group; ensure that the data is complete and correct, and prepare for regression analysis;

[0292] S2. Select regression model: According to the characteristics of tea soup data, select an appropriate regression model; the quadratic regression model is often used in this response surface optimization because it can capture the interaction and nonlinear effects between independent variables;

[0293] S3. Regression analysis: Regression analysis was performed using statistical software (Design-Expert).

[0294] You can use the lm() function for regression analysis: model<-lm(E~A+B+C+D+A*B+A*C+A*D+B*C+B*D+C*D+A^2+B^2+C^2+D^2,data=experiment_data)

[0295] S4. Model fitting and evaluation: By analyzing the regression coefficient, R square (R 2 ) and adjusted R square (AdjustedR 2 ) and other indicators to evaluate the goodness of fit of the model;

[0296] S5. Check residual analysis: Ensure that the assumptions of the model (such as independence, normality, and equal variance) are met.

[0297] Furthermore, the specific steps of variance analysis (ANOVA) in the response surface optimization experiment are as follows:

[0298] S1. Generate ANOVA table: Generate an ANOVA table in statistical software, including the variance analysis results between dependent variables and independent variables; you can use the anova() function to generate an ANOVA table: anova_result<-anova(model);

[0299] S2. Key indicators explanation:

[0300] F value: It is used to measure the relative size of the impact of each factor on the response variable; the larger the F value, the more significant the impact of the factor on the response;

[0301] P value: used to test the hypothesis, that is, whether a factor has a significant effect on the response variable; a P value less than 0.05 indicates that the factor has a significant effect on the response variable;

[0302] Significance level (α): usually 0.05 or 0.01, used to judge the significance of P value;

[0303] S3. Interpretation of ANOVA results: Check the P value of each factor to determine which factors and interactions significantly affect the sensory scores; after identifying the significant influencing factors, further optimization can be carried out to exclude insignificant factors or adjust the model to improve accuracy.

[0304] Further, according to the above response surface optimization analysis, Figure 6 is obtained, which shows the design of the response surface experiment and the experimental results of the low-sugar fermented tea beverage. Figure 6 lists multiple experimental conditions and their corresponding sensory scoring results, which are specifically described as follows: First, there are three levels of tea-water ratio: 150g / ml, 175g / ml and 200g / ml; the tea-water ratio affects the concentration of the tea soup, thereby affecting the taste and flavor of the final product. Second, the amount of white sugar added is 3%, 4%, and 5%; the amount of white sugar added determines the sweetness intensity of the tea soup (such as experiments 25 to 29), and also affects the utilization efficiency of sugar during the fermentation process. The amount of lactobacillus added is 3%, 4%, and 5%. Third, the amount of lactobacillus added has an important influence on the type and concentration of the fermentation product, which in turn affects the acidity and overall flavor of the tea soup. Fourth, the fermentation time is 14 hours, 16 hours and 18 hours; the fermentation time determines the time of lactobacillus metabolism, thereby affecting the concentration and type of the fermentation product. Fifth, the sensory scores of tea soup reflect the quality of its overall flavor and taste (such as experiments 25 to 29); the scores ranged from 77 to 81, indicating that there were certain differences in product quality under different experimental conditions.

[0305] As can be seen from Figure 6, the experimental results with the highest sensory scores appeared under multiple conditions, such as Experiment 1, Experiment 4, Experiment 9 and Experiment 15. The common characteristics of multiple groups of experiments are that the tea-water ratio is 150 or 175, the amount of white sugar added is 3% or 4%, the amount of lactobacillus added is 4% or 5%, and the fermentation time is 14 hours or 16 hours. Therefore, Figure 6 provides the optimization direction of low-sugar fermented tea beverages, that is, by adjusting the tea-water ratio, the amount of white sugar and lactobacillus added, and the fermentation time, the sensory quality of the final product can be significantly affected. According to the data in Figure 6, it is most appropriate to produce the product under the conditions of a tea-water ratio of 150-175g / ml, a white sugar addition of 3-4%, a lactobacillus addition of 4%, and a fermentation time of 14-16 hours to obtain the best flavor and taste.

[0306] Furthermore, Design-Expert 8.0 was used to perform regression fitting on the sensory scores in Figure 7, and the quadratic polynomial regression equation was obtained:

[0307] E=90.40-1.50A+0.25B-0.67C-0.42D-0.75AB-0.25AC+0.000AD-0.50BC+0.000BD+0.25CD-5.99A 2 -5.62B 2 -5.99C 2 -5.12D 2

[0308] Therefore, a significance analysis was performed on the response surface model, and the results are shown in Figure 7: It shows the effects of various factors and their interactions in the preparation process of low-sugar fermented Pu'er tea on the sensory scores, and a significance analysis was performed through analysis of variance (ANOVA).

[0309] Specifically, the variance model represents the overall experimental model, including all main effects, interactions, and quadratic effects.

[0310] A:Tea to water ratio B: Added amount of white sugar C: Lactobacillus inoculum D: Fermentation time AB,AC,AD,BC,BD,CD: Interactions among factors <![CDATA[A 2 ,B 2 ,C 2 ,D 2 :Secondary effects of each factor]]>

[0311] Specifically, the variance model represents the overall experimental model, and the key data are as follows:

[0312] The variance model represents the key data of the overall experimental model Mean Square: Indicates the contribution of each factor or interaction to the total variation. Degrees of freedom (df): The parameter used to calculate the F value, usually the number of levels in the experiment minus one. F value: measures the impact of each factor or interaction on the response variable. The larger the F value, the greater the impact of the factor. P value: used to test the significance of each factor or interaction. Generally speaking, a P value less than 0.05 indicates that the factor significantly affects the response variable. Significance: * indicates significant level (P<0.05); ** indicates extremely significant level (P<0.01).

[0313] Furthermore, the following results can be obtained from Figure 7: Model P < 0.0001, indicating that the model is extremely significant. 2 , B 2 , C 2 and D 2The difference in item A was extremely significant (P<0.01), and the difference in item C was significant (P<0.05); the order of influence of each fermentation factor on the sensory score was A>C>D>B, that is, tea-water ratio>Lactobacillus inoculation amount>fermentation time>white sugar addition amount. Correlation coefficient R 2 =0.9778, indicating that the model has a good fit and can well describe the relationship between factors and response values, and can explain 97.78% of the changes. 2 Adj =0.9555, indicating that the experimental error is small and the credibility is high. Therefore, this model can be used to determine the optimal process for low-sugar fermented tea beverages.

[0314] First, in terms of model significance, F value = 43.98, P value < 0.0001: This shows that the overall model is extremely significant, indicating that the selected process parameters and their combination can well explain the variability of sensory scores.

[0315] Second, in terms of main effects, A (tea-water ratio): F value = 28.82, P value < 0.0001, extremely significant. The tea-water ratio significantly affects the sensory score; B (amount of white sugar added): F value = 0.75, P value = 0.3861, not significant. The effect of white sugar addition on the sensory score is not significant; C (Lactobacillus inoculum): F value = 5.33, P value = 0.0317, significant. The Lactobacillus inoculum has a significant effect on the sensory score; D (fermentation time): F value = 2.22, P value = 0.1581, not significant. The effect of fermentation time on the sensory score is not significant.

[0316] Third, in terms of interactions, the P values ​​of **interactions (such as AB, AC, etc.)** were all greater than 0.05, indicating that these interactions had no significant effect on the sensory scores.

[0317] Fourth, in terms of the secondary effect, A 2 ,B 2 ,C 2 ,D 2 The F value and P value show that the quadratic effect has a significant impact on the model, especially the tea-water ratio (A 2 ) and Lactobacillus inoculum (C 2 ), the P values ​​were all <0.0001, which was extremely significant. This means that the quadratic effects of these factors have a significant impact on the changes in sensory scores.

[0318] Conclusion 1: **Tea-to-water ratio (A) and Lactobacillus inoculum amount (C)** are significant factors affecting the sensory score of low-sugar fermented Pu'er tea, especially the effect of tea-to-water ratio is more significant; **White sugar addition amount (B) and fermentation time (D)** have no significant effect on the sensory score. It can be considered that adjusting these parameters within a reasonable range has limited effect on the sensory score of the final product; The quadratic effect in the model significantly affects the sensory score, which indicates that the sensory score is not a simple linear relationship, but is greatly affected by the square effect of these factors.

[0319] Conclusion 2: During the production process, the tea-water ratio and the amount of Lactobacillus inoculum should be optimized, while paying attention to the nonlinear effects of these factors, so as to better control the fermentation process and the quality of the final product.

[0320] Three-dimensional response surface analysis of the effects of water-to-tea ratio (A) and white sugar addition (B) on sensory scores of low-sugar fermented Pu'er tea

[0321] In multiple groups of specific embodiments, response surface optimization analysis is performed to display a contour 3D response surface diagram of the interaction between various factors. Figure 2 The three-dimensional response surface diagram of the water-to-tea ratio (A) and the amount of white sugar added (B) on the sensory score of low-sugar fermented Pu'er tea is shown. The changes in the sensory score are represented by 3D contour lines, which intuitively demonstrates the impact of these two factors on the sensory score.

[0322] Figure 2 The horizontal axis is (A: water-to-tea ratio), which varies between 150 and 200 g / ml, representing the ratio of tea leaves to water, affecting the concentration of the tea soup; Figure 2 The horizontal axis is (A: water-to-tea ratio) The amount of sugar added varies from 3% to 5%, affecting the sweetness and overall flavor of the tea soup; Figure 2 The vertical axis is (sensory score), which indicates the overall sensory quality of the product. The higher the score, the better the sensory quality. Figure 2 The contour lines and color changes indicate the sensory scores, with brighter colors representing higher sensory scores and darker colors representing lower scores. Figure 2 The main observation point in the experiment is the highest point, that is, the highest sensory score area is located at a position where the tea-to-water ratio is about 175g / ml and the amount of white sugar added is about 4%, indicating that under this condition, the flavor of the tea soup is the best and the sensory score is the highest.

[0323] Specifically, Figure 2The trend of the water-to-tea ratio (A) and the amount of white sugar added (B) on the score of low-sugar fermented Pu'er tea is shown. As the tea-to-water ratio increases from 150 to 175g / ml, the sensory score rises, reaches a peak, and then decreases as the tea-to-water ratio continues to increase to 200g / ml; this is because the higher tea-to-water ratio causes the tea soup to be too concentrated, affecting the overall flavor balance. When the amount of white sugar added is between 3% and 4%, the sensory score rises, reaches a peak, and then decreases slightly at 5%. This shows that with the right amount of white sugar added, the sweetness and overall flavor of the tea soup are improved, but excessive sugar can lead to greasy sweetness and affect the score.

[0324] Specifically, Figure 2 The tea-water ratio determines the concentration of the tea soup and the content of tea polyphenols, caffeine and other substances. A moderate tea-water ratio (about 175g / ml) provides a good concentration, which can balance bitterness and umami, making the flavor of the fermented product more prominent. However, too high or too low a tea-water ratio will lead to an unbalanced taste. For example, too strong or too weak tea soup will mask or amplify the flavor of the fermented product, affecting the sensory score.

[0325] Specifically, Figure 2 During the fermentation process, white sugar not only provides sweetness, but also affects the fermentation activity and acid production of lactic acid bacteria. An appropriate amount of sugar (about 4%) can enhance the sweetness and taste of tea soup without affecting the original flavor of the tea. However, excessive sugar (5%) can easily cause the sweetness to mask other flavor components, and even cause excessive sourness or produce unpleasant fermentation flavors during the fermentation process.

[0326] according to Figure 2 Conclusion: The 3D response surface plot provides an intuitive perspective, showing the significant effects of tea-water ratio and white sugar addition on the sensory score of low-sugar fermented Pu'er tea. The best process parameter combination is a tea-water ratio of 175g / ml and a white sugar addition of 4%. Under this condition, the product has the highest sensory score, and the sour-sweet balance, flavor level and overall taste of the tea soup are all at their best. Further process optimization can be carried out based on these results to stably produce high-quality fermented tea beverages.

[0327] 3D response surface analysis of the effects of 6 water / tea ratios (A) and Lactobacillus inoculum (C) on sensory scores of low-sugar fermented Pu'er tea

[0328] In multiple groups of specific embodiments, response surface optimization analysis is performed to display a contour 3D response surface diagram of the interaction between various factors. Figure 3 The 3D response surface of water-to-tea ratio (A) and Lactobacillus inoculum amount (C) on the sensory score of low-sugar fermented Pu'er tea is shown, and the influence of different process parameters on the sensory score is demonstrated through contour lines and 3D surfaces.

[0329] Figure 3The horizontal axis is (A: water-to-tea ratio), with the tea-to-water ratio ranging from 150 to 200 g / ml, indicating the ratio of tea leaves to water, which affects the concentration and composition of the tea soup; Figure 3 The vertical axis is (C: Lactobacillus inoculation amount), and the Lactobacillus inoculation amount ranges from 3% to 5%, which affects the activity of lactic acid bacteria and the generation of fermentation products during the fermentation process; Figure 3 The vertical axis is (sensory score), which indicates the sensory quality score of the product. The higher the value, the better the sensory quality of the product. Figure 3 The contour lines and color changes indicate changes in sensory scores, with brighter colors corresponding to higher sensory scores and darker colors corresponding to lower scores. Figure 3 The main observation point in the experiment is the highest point, that is, the highest sensory score appears at a tea-water ratio of about 175g / ml and a lactobacillus inoculation amount of about 4%. At this time, the flavor of the tea soup is the best and the sensory score is the highest.

[0330] Specifically, Figure 3 The scoring trends of low-sugar fermented Pu'er tea in response to water-to-tea ratio (A) and Lactobacillus inoculum (C) are shown. As the tea-to-water ratio increases from 150 to 175 g / ml, the sensory score rises, reaches a peak, and then decreases as the tea-to-water ratio further increases to 200 g / ml. This is because the higher tea-to-water ratio causes the tea soup to be too concentrated, affecting the overall flavor. When the Lactobacillus inoculum is between 3% and 4%, the sensory score rises, reaches a peak, and then decreases slightly at 5%. An appropriate amount of Lactobacillus inoculum helps optimize the fermentation effect, but too much can lead to over-fermentation or produce undesirable flavors.

[0331] Specifically, Figure 3 The tea-water ratio determines the concentration of tea polyphenols, caffeine and other ingredients in the tea soup. A moderate tea-water ratio (about 175g / ml) helps to maintain the flavor balance of the tea soup and make the flavor of the fermented product stand out. However, a high tea-water ratio will cause the tea soup to be too thick and the bitter taste will be aggravated, affecting the overall sensory score.

[0332] Specifically, Figure 3 During the fermentation process, Lactobacillus will produce lactic acid and other metabolites, which will affect the acidity and flavor of the tea. An appropriate amount of Lactobacillus inoculation (about 4%) will help to produce an appropriate amount of lactic acid, improving the complexity and layering of the flavor of the tea. However, too much Lactobacillus will easily lead to over-acidification or other undesirable fermentation flavors, reducing the sensory score.

[0333] according to Figure 3Conclusion: The best combination of tea-water ratio and lactobacillus inoculum is 175g / ml tea-water ratio and 4% lactobacillus inoculum. Under this combination, the sensory score of the fermented tea beverage is the highest, and the product has a good balance of sweet and sour, rich flavor and complex taste. This data has important reference value for optimizing the production process of low-sugar fermented tea beverages, ensuring that the sensory quality of the products produced is the best.

[0334] 3D response surface analysis of the effects of 7-water-tea ratio (A) and fermentation time (D) on sensory scores of low-sugar fermented Pu'er tea

[0335] In multiple groups of specific embodiments, response surface optimization analysis is performed to display a contour 3D response surface diagram of the interaction between various factors. Figure 4 The 3D response surface of water-to-tea ratio (A) and fermentation time (D) on the sensory score of low-sugar fermented Pu'er tea is shown, and the three-dimensional surface and contour lines are used to show how these two factors affect the sensory score of the product.

[0336] Figure 4 The horizontal axis is (A: water-to-tea ratio), with the tea-to-water ratio ranging from 150 to 200 g / ml, indicating the ratio of tea leaves to water, which directly affects the concentration and flavor of the tea soup; Figure 4 The vertical axis is (D: fermentation time), which varies from 14 hours to 18 hours, affecting the time of the lactic acid bacteria fermentation process and the generation of fermentation products; Figure 4 The vertical axis is (sensory score), which indicates the sensory quality score of the product. The higher the value, the better the sensory quality of the product. Figure 4 The contour lines and color changes reflect changes in sensory scores, with brighter colors (usually at the peak of the graph) indicating higher sensory scores and darker colors indicating lower scores. Figure 4 The main observation point in the experiment is the highest point, that is, the highest sensory score area is located at a tea-to-water ratio of about 175g / ml and a fermentation time of about 16 hours, indicating that under these conditions, the flavor and overall sensory experience of the tea soup are best.

[0337] Specifically, Figure 4 The score trends of low-sugar fermented Pu'er tea in response to water-to-tea ratio (A) and fermentation time (D) are shown. As the tea-to-water ratio increases from 150 to 175 g / ml, the sensory score rises and reaches a peak; then, as the tea-to-water ratio further increases, the score decreases; this is because the excessively high tea-to-water ratio causes the tea soup to be too thick and the bitterness to increase. When the fermentation time increases from 14 hours to 16 hours, the sensory score increases, but the score decreases after more than 16 hours. This shows that a moderate fermentation time is conducive to the formation of flavor, but too long a fermentation time can lead to over-fermentation, generating too much sourness or unpleasant flavors.

[0338] Specifically, Figure 4The tea-water ratio affects the concentration of tea polyphenols, caffeine and other compounds in the tea soup. These components have a significant impact on the bitterness, color and flavor of the tea soup; a moderate tea-water ratio (175g / ml) can balance these components and ensure the complexity and layering of the flavor of the tea soup.

[0339] Specifically, Figure 4 The fermentation time determines the time for lactic acid bacteria to grow and metabolize in the tea soup. A moderate fermentation time (about 16 hours) can produce an appropriate amount of lactic acid and other fermentation products, increasing the acidity and complexity of the tea soup, but not excessively. Too long a fermentation time will lead to over-fermentation, producing too much sourness or unpleasant aroma, affecting the overall quality of the tea soup.

[0340] according to Figure 4 Conclusion: The optimal process parameters are a tea-water ratio of 175 g / ml and a fermentation time of 16 hours. Under these conditions, the sensory score of the product is the highest, and the sour-sweet balance, flavor level and overall taste of the tea soup are at their best. Further process optimization should focus on these key parameters to stably produce high-quality fermented tea beverages.

[0341] 3D response surface analysis of the effect of 8-white sugar addition (B) and Lactobacillus inoculum (C) on the sensory score of low-sugar fermented Pu'er tea

[0342] In multiple groups of specific embodiments, response surface optimization analysis is performed to display a contour 3D response surface diagram of the interaction between various factors. Figure 5 The 3D response surface of the amount of white sugar added (B) and the amount of Lactobacillus inoculation (C) on the sensory score of low-sugar fermented Pu'er tea is shown. Through contour lines and three-dimensional surfaces, we can intuitively see how these two factors affect the sensory score.

[0343] Figure 5 The horizontal axis is (B: amount of added white sugar), ranging from 3% to 5%, which affects the sweetness and overall taste of the tea soup; Figure 5 The vertical axis is (C: Lactobacillus inoculation amount), ranging from 3% to 5%, which affects the activity of lactic acid bacteria and the generation of fermentation products during the fermentation process; Figure 5 The vertical axis is (sensory score), which indicates the sensory score of the product. The higher the value, the better the sensory quality of the product. Figure 5 The contour lines and color changes indicate changes in sensory scores. Brighter colors indicate higher sensory scores, while darker areas indicate lower scores. Figure 5 The main observation point is the highest point, that is, the area with the highest sensory score is located at the position where the addition of white sugar is about 4% and the inoculation amount of Lactobacillus is about 4%, indicating that under these conditions, the sweetness of the tea soup and the fermentation products reach the best balance, and the overall sensory quality is the highest.

[0344] Specifically, Figure 5The trend of the score of low-sugar fermented Pu'er tea in terms of the amount of white sugar added (B) and the amount of Lactobacillus inoculum (C) is shown. As the amount of white sugar added increases from 3% to 4%, the sensory score increases, and then decreases slightly at 5%. This is because the right amount of sugar can enhance the sweetness and taste of the tea soup, but too much sugar may lead to excessive sweetness and mask other flavors. When the amount of Lactobacillus inoculum increases from 3% to 4%, the sensory score increases and reaches a peak; at 5%, the score decreases. This is because the right amount of Lactobacillus can produce appropriate sourness and complex fermentation products, but excessive amounts can lead to over-acidification or the production of unpleasant flavors.

[0345] Specifically, Figure 5 The white sugar in the tea soup acts as a sweetener, which not only adjusts the sweetness of the tea soup, but also provides a carbon source during the fermentation process, affecting the metabolic activity of lactic acid bacteria. An appropriate amount of sugar (about 4%) helps to balance the sourness and sweetness of the tea soup, making the product more acceptable to consumers.

[0346] Specifically, Figure 5 The number of lactobacilli directly affects the acidity of the fermentation process and the types of fermentation products; an appropriate amount of lactobacilli inoculation (about 4%) can produce abundant lactic acid and other organic acids, increasing the acidity and flavor of the tea soup. However, too high an inoculation amount will increase the risk of over-fermentation, leading to an unpleasant taste experience.

[0347] according to Figure 5 Conclusion: The optimal process parameters are 4% white sugar addition and 4% lactobacillus inoculation. At this time, the sensory score of the product is the highest, and the sweet and sour balance, flavor complexity and overall taste of the tea soup are at their best. Further process optimization should focus on these key parameters to ensure the stability of product quality and market competitiveness.

[0348] 3D response surface analysis of the effect of 9-sugar addition (B) and fermentation time (D) on the sensory score of low-sugar fermented Pu'er tea

[0349] In multiple groups of specific embodiments, response surface optimization analysis is performed to display a contour 3D response surface diagram of the interaction between various factors. Figure 6 The 3D response surface of the amount of white sugar added (B) and fermentation time (D) on the sensory score of low-sugar fermented Pu'er tea is displayed, and contour lines and three-dimensional surfaces are used to show how these two factors affect the sensory score.

[0350] Figure 6 The horizontal axis is (B: amount of added white sugar), ranging from 3% to 5%, which affects the sweetness and overall taste of the tea soup; Figure 6 The vertical axis is (D: fermentation time), ranging from 14 hours to 18 hours, which affects the fermentation time of lactic acid bacteria and thus affects the generation of fermentation products; Figure 6The vertical axis is (sensory score), which indicates the sensory score of the product. The higher the value, the better the sensory quality of the low-sugar fermented Pu'er tea product. Figure 6 The contour lines and color changes indicate changes in sensory scores. Brighter colors indicate higher sensory scores, while darker areas indicate lower scores. Figure 6 The main observation point is the highest point, that is, the highest sensory score area appears at the position where the addition of white sugar is about 4% and the fermentation time is about 16 hours, indicating that under these conditions, the sweetness of the tea soup and the fermentation products reach the best balance, and the overall sensory quality is the highest.

[0351] Specifically, Figure 6 The score trends of low-sugar fermented Pu'er tea in response to the amount of added sugar (B) and fermentation time (D) are shown. As the amount of added sugar increases from 3% to 4%, the sensory score increases, and then decreases slightly at 5%; this is because the right amount of sugar can enhance the sweetness and taste of the tea soup, but too much sugar may lead to excessive sweetness and mask other flavors. The sensory score increases as the fermentation time increases from 14 hours to 16 hours, and decreases after more than 16 hours. This suggests that a moderate fermentation time helps to produce an appropriate amount of lactic acid and other fermentation products, but too long a fermentation time may lead to excessive sourness or other undesirable flavors.

[0352] Specifically, Figure 6 The white sugar in the tea not only adjusts the sweetness of the tea, but also provides a carbon source for the fermentation process and affects the activity of lactic acid bacteria. The right amount of sugar (about 4%) can balance the sweetness and sourness of the tea and improve the sensory score. However, too much sugar (5%) makes the tea too sweet and affects the balance of the overall flavor.

[0353] Specifically, Figure 6 The fermentation time determines the growth time of lactic acid bacteria in the tea soup and the accumulation of its metabolites. A moderate fermentation time (about 16 hours) can produce a proper amount of lactic acid, giving the tea soup a good acidity and balanced flavor. However, too long a fermentation time will lead to excessive acidity in the tea soup or produce an unpleasant aroma, reducing the sensory score.

[0354] according to Figure 6 Conclusion: The optimal process parameters are 4% white sugar addition and 16 hours of fermentation time. At this time, the sensory score of the product is the highest, indicating that the sweetness and acidity of the tea soup are optimally balanced, and the flavor and taste are maximized. This data is of great reference value for optimizing the production process of fermented tea beverages and ensuring product stability and market competitiveness. 3D response surface analysis of the effect of 10 Lactobacillus inoculation amount (C) and fermentation time (D) on the sensory score of low-sugar fermented Pu'er tea

[0355] In multiple groups of specific embodiments, response surface optimization analysis is performed to display a contour 3D response surface diagram of the interaction between various factors. Figure 7 The 3D response surface of Lactobacillus inoculation amount (C) and fermentation time (D) on the sensory score of low-sugar fermented Pu'er tea is shown. Through the three-dimensional surface and contour lines, we can intuitively see how these two factors affect the sensory score.

[0356] Figure 7 The horizontal axis is (C: Lactobacillus inoculum amount), ranging from 3% to 5%, indicating the proportion of lactic acid bacteria added during the fermentation process; Figure 7 The vertical axis is (D: fermentation time), ranging from 14 hours to 18 hours, indicating the length of the fermentation process; Figure 7 The vertical axis is (sensory score), which indicates the sensory score of low-sugar fermented Pu'er tea products. The higher the score, the better the sensory quality of low-sugar fermented Pu'er tea products. Figure 7 The contour lines and color changes indicate changes in sensory scores; brighter colors indicate higher sensory scores; darker areas indicate lower scores. Figure 7 The main observation point is the highest point, that is, the area with the highest sensory score appears at a position where the Lactobacillus inoculation amount is about 4% and the fermentation time is about 16 hours; at this time, the flavor and taste of the tea soup reach the best state, and the overall sensory score is the highest.

[0357] Specifically, Figure 7 The score trend of low-sugar fermented Pu'er tea in terms of Lactobacillus inoculation amount (C) and fermentation time (D) is shown. As the Lactobacillus inoculation amount increases from 3% to 4%, the sensory score increases and reaches a peak; then at 5%, the score decreases, indicating that an appropriate amount of Lactobacillus inoculation can optimize the fermentation process, while an excessive amount may lead to excessive acidification or other undesirable flavors. As the fermentation time increases from 14 hours to 16 hours, the sensory score increases, and the score decreases after more than 16 hours, indicating that a moderate fermentation time is conducive to the formation of fermentation products and the optimization of flavor, but too long a time may lead to excessive sourness or other undesirable fermentation phenomena.

[0358] Specifically, Figure 7 The lactobacilli in the tea produce lactic acid and other organic acids through metabolism during the fermentation process. These acidic substances adjust the pH value of the tea and give it a sour taste. An appropriate amount of lactobacilli inoculation (about 4%) can balance the production of fermentation products, making the tea moderately acidic and rich in taste. However, too much lactobacilli will cause the tea to be too sour, masking other flavors and even affecting consumers' taste acceptance.

[0359] Specifically, Figure 7The fermentation time in the tea affects the growth and metabolic activity time of lactic acid bacteria. A moderate fermentation time (about 16 hours) allows lactic acid bacteria to fully exert their effects and produce an appropriate amount of fermentation products, such as lactic acid and other flavor substances, which together enhance the complexity and flavor of the tea soup; however, too long a fermentation time can easily lead to excessive fermentation, produce excessive sourness or other unpleasant flavor substances, and reduce the overall sensory score of the tea soup.

[0360] according to Figure 7 Conclusion: The optimal process parameters are 4% lactobacillus inoculation and 16 hours fermentation time. At this time, the sensory score of the product is the highest, and the sour-sweet balance, flavor level and overall taste of the tea soup are at their best. This data is of great reference value for optimizing the production process of fermented tea beverages and ensuring product quality and market competitiveness.

[0361] Further, according to the relevant data content of determination 5-10, the response surface method and quadratic multinomial regression equation were used to study the effects of lactobacillus inoculation amount, white granulated sugar addition amount, fermentation time and tea-water ratio on the sensory score of low-sugar fermented tea beverage, and it was concluded that AC, AB, AD, BC, BD, CD, had obvious interactions, and AB, AC, BC, CD had the best interaction effect, and the opening of the three-dimensional stereogram response surface was downward, indicating that the response surface had a maximum value and had an optimal formula within the test range. According to the above quadratic multinomial regression equation, when the lactobacillus inoculation amount was 3.94%, the white granulated sugar addition amount was 4.03%, the fermentation time was 15.92h, and the tea-water ratio was 1:173.84, the sensory score of the low-sugar fermented tea beverage reached 90.53. Considering the actual operation of the experiment, the process conditions obtained by the above data analysis were corrected to lactobacillus inoculation amount 4%, white granulated sugar addition amount 4%, fermentation time was 16h, and tea-water ratio was 1:175. Three independent repeated experiments were carried out under the finalized process conditions to verify the prepared low-sugar fermented tea beverage. The average sensory score was 90.33, which was close to the score obtained after model data analysis, proving that the model is reliable.

[0362] Specifically, in terms of interaction significance: AC, AB, AD, BC, BD, CD and other factors have obvious interactions, especially **AB (tea-water ratio and white sugar addition), AC (tea-water ratio and lactobacillus inoculation), BC (white sugar addition and lactobacillus inoculation), CD (lactobacillus inoculation and fermentation time)** and other interactions have the best effect. This means that the combination of these factors has a significant impact on the sensory score.

[0363] Specifically, in terms of response surface characteristics: the three-dimensional response surface plot shows that the opening of the surface is downward, indicating that there is a maximum or optimal point in the model. Within the experimental range, an optimal formula can be found to achieve the highest sensory score.

[0364] Specifically, based on the response surface optimization results, the optimal process parameters were obtained according to the quadratic polynomial regression equation: Lactobacillus inoculation amount 3.94%, white sugar addition amount 4.03%, fermentation time 15.92 hours, tea-water ratio 1:173.84. Under these conditions, the predicted sensory score was 90.53.

[0365] Furthermore, the response surface experimental model of the low-sugar fermented Pu'er tea of ​​the present invention was successfully verified, that is, under the adjusted process conditions, 3 independent repeated experiments were carried out, and the average sensory score obtained was 90.33, which is very close to the 90.53 predicted by the model. This shows that the model has good predictive ability and guiding significance for actual production. In order to simplify the operation and improve repeatability, the optimal parameters were adjusted to integers or easy-to-operate values: Lactobacillus inoculation amount 4%, white sugar addition amount 4%, fermentation time 16 hours, tea-water ratio 1:175.

[0366] Furthermore, the response surface experimental model of low-sugar fermented Pu'er tea of ​​the present invention has the following significance:

[0367] First, the response surface model has the significance of interaction. The interaction between factors is significant, indicating that the change of a single factor is not enough to significantly optimize the sensory score, but the synergistic effect of multiple factors needs to be considered comprehensively. This interaction affects the chemical and microbial reactions during the fermentation process, thereby affecting the flavor and quality of the final product;

[0368] Second, the reliability of the response surface model has been recognized. The response surface model can accurately predict the experimental results, and the results of actual operation verification are very close to the model predictions, which verifies the reliability and applicability of the model;

[0369] Third, for the convenience and consistency of actual production, the optimized parameters were slightly adjusted to ensure that the process was easy to control and stable. The adjusted parameters still achieved high sensory scores in multiple groups of examples, proving the feasibility and practicality of the optimized process conditions for low-sugar fermented Pu'er tea.

[0370] Fourthly, the low-sugar fermented Pu'er tea process provides a scientific basis for the production of high-quality low-sugar fermented tea beverages, ensuring that the products have good sensory quality and market competitiveness. By strictly controlling the process parameters, the stability of the production process and the consistency of the products can be improved, providing support for large-scale production.

[0371] Determination 11 Sensory evaluation of the finished product of low-sugar fermented Pu'er tea beverage prepared by the present invention

[0372] In multiple groups of specific embodiments, the following sensory indicators were obtained through sensory evaluation of the finished product of low-sugar fermented Pu'er tea beverage.

[0373]

[0374] The above chart shows the sensory indicators of low-sugar fermented tea beverages, including the evaluation results of color, aroma, taste and texture. Specifically, the color is yellow-brown and bright. The color of low-sugar fermented Pu'er tea beverage is yellow-brown, which is the typical color of fermented tea beverages. The bright color indicates that the product has good clarity and no obvious impurities or precipitation.

[0375] Specifically, the aroma of low-sugar fermented Pu'er tea beverage is strong, with the fragrance of tea and no peculiar smell; the strong tea aroma indicates that the flavor substances in the fermentation process are well retained and improved, and the absence of peculiar smell indicates that the product quality is good, without pollution or the production of bad fermented substances. Specifically, the taste of low-sugar fermented Pu'er tea beverage is sour and sweet, balanced lactic acid flavor without astringency, and mellow and sweet. In the taste evaluation, the balance of sour and sweet and the balance of lactic acid flavor indicate that the fermentation process is properly controlled, and the acidity is moderate and not excessive. The absence of astringency and mellow sweetness indicate that the bitter components of the product are effectively controlled, leaving a pleasant aftertaste in the mouth of the taster. Specifically, the organizational morphology of low-sugar fermented Pu'er tea beverage is uniform, clear as a whole, and without precipitation. The uniform organizational morphology and clear liquid indicate that the tea beverage maintains good stability during the fermentation and filtration process, without obvious material separation or precipitation. This helps to enhance the visual appeal and drinking experience of low-sugar fermented Pu'er tea beverage products.

[0376] Conclusion of sensory evaluation: The overall performance of low-sugar fermented tea beverages in appearance, flavor, taste and texture is good. These indicators not only reflect the physical and chemical properties of the product, but also reflect the sensory acceptance of the product by consumers. High-quality sensory experience is an important factor for consumers to choose fermented tea beverages. Therefore, these sensory evaluation indicators provide an important reference for product market positioning and consumer feedback.

[0377] Determination of the main physical and chemical indicators of the finished product of the low-sugar fermented Pu'er tea beverage prepared by the present invention

[0378] In multiple groups of specific embodiments, the main physical and chemical indicators of the low-sugar fermented tea beverage were measured to be a tea polyphenol content of 624.3 mg / L, which meets the national standard requirements (tea polyphenol content ≥ 300 mg / kg), a soluble sugar content of 4 g / 100 ml, and DPPH free radical and ABTS+ free radical scavenging rates of 68.82% and 44.18%, respectively.

[0379] In the physical and chemical index evaluation of low-sugar fermented tea beverages, the above key indicators were measured to determine the chemical properties and health benefits of low-sugar fermented Pu'er tea beverage products.

[0380] Specifically, the tea polyphenol content is 624.3 mg / L, which fully meets the national standard requirement of tea polyphenol content ≥ 300 mg / kg. Tea polyphenols are an important functional ingredient in tea, with multiple health benefits such as anti-oxidation and anti-inflammatory. The content of 624.3 mg / L not only exceeds the minimum requirement of the national standard (300 mg / kg), but also shows that the beverage is rich in beneficial tea polyphenol components. This means that low-sugar fermented Pu'er tea beverage products have strong antioxidant capacity, which helps neutralize free radicals in the body and reduce the damage of oxidative stress to health.

[0381] Specifically, the soluble sugar content is 4g / 100ml. The soluble sugar content reflects the sweetness level of the beverage. The soluble sugar content of 4g / 100ml indicates that the beverage has a moderate sweetness, which is consistent with the characteristics of a low-sugar product. This content not only provides a pleasant taste, but also helps control the sugar intake of drinkers, and is suitable for consumers who are concerned about health.

[0382] Specifically, the DPPH free radical scavenging rate was 68.82%. The DPPH free radical scavenging rate is a way to measure antioxidant capacity. The 68.82% scavenging rate indicates that the tea beverage has a strong antioxidant capacity and can effectively scavenge free radicals. Low-sugar fermented Pu'er tea beverage has this ability, which has a positive effect on protecting cells from oxidative damage, delaying aging and preventing diseases.

[0383] Specifically, the ABTS+ free radical scavenging rate was 44.18%. The BTS+ free radical scavenging rate is also an indicator of antioxidant capacity. Although the scavenging rate of 44.18% is lower than the DPPH free radical scavenging rate, it still shows a certain antioxidant activity. The different scavenging rates may reflect the diversity of antioxidant substances in tea beverages and the ability to scavenge different free radicals.

[0384] Conclusions of key physical and chemical indicators: Low-sugar fermented tea beverages not only meet food safety and quality standards, but also have significant health functions, especially in terms of anti-oxidation. The high content of tea polyphenols and significant free radical scavenging ability make it a healthy drink. At the same time, the moderate soluble sugar content also makes it a suitable choice for a wide range of consumers, especially those who are concerned about sugar intake. These data provide strong scientific support for product marketing and consumer education. Determination 13 Hygienic indicators of the finished low-sugar fermented Pu'er tea beverage prepared by the present invention

[0385] Hygiene indicators are important parameters for measuring food safety, including the detection results of microorganisms such as total bacteria, E. coli, mold and pathogenic bacteria. In multiple groups of specific embodiments, the total bacteria count of low-sugar fermented beverages was finally detected to be ≤54 / ml, E. coli ≤1 / ml, mold was not detected, and pathogenic bacteria were not detected.

[0386]

[0387] Specifically, the total bacterial count of the low-sugar fermented Pu'er tea beverage was ≤54 / ml. The total bacterial count is an important indicator for measuring the microbial load of a product. The result of "≤54 / ml" indicates that the number of microorganisms in the product is very low, far below the usual safety limit. This means that the sanitary conditions during the production process are good, effectively controlling bacterial contamination and ensuring the microbial safety of the product.

[0388] Specifically, the detection result of E. coli in low-sugar fermented Pu'er tea beverage is ≤1 / ml. E. coli is one of the commonly used food hygiene indicators, and its presence usually indicates possible fecal contamination. The result of "≤1 / ml" shows that the product has almost no E. coli contamination, and the hygiene control measures in the production process are effective, avoiding the presence of such pathogenic microorganisms. This is of great significance to the safety of consumers.

[0389] Specifically, no mold was detected in the low-sugar fermented Pu'er tea beverage. Mold causes corruption in food and produces toxic metabolites (such as aflatoxin). The result of no detection indicates that the low-sugar fermented Pu'er tea beverage product is not contaminated by mold during the entire production and storage process, ensuring the quality and safety of the low-sugar fermented Pu'er tea beverage product.

[0390] Specifically, no pathogenic bacteria were detected in the low-sugar fermented Pu'er tea beverage. Pathogenic bacteria include Salmonella, Shigella, Listeria and other microorganisms that can cause foodborne diseases. The absence of pathogenic bacteria indicates that the product has effectively avoided pathogen contamination during production, processing and packaging, ensuring the health and safety of the product for consumers.

[0391] Conclusion of hygiene indicators: The low-sugar fermented tea beverage maintains a high standard of hygiene control during the production process, ensuring the microbial safety of the product. The test results of low total bacteria count and absence of E. coli, mold and pathogenic bacteria show that the product not only meets the requirements of food safety regulations, but also provides health and safety protection for consumers. These data are of great significance to consumer trust and product marketing, ensuring that the product maintains high quality and good reputation in a highly competitive market.

Claims

1. A method for preparing a high-quality low-sugar fermented tea beverage, characterized in that: The following steps are involved: S1. Selection of raw materials: Select Pu'er tea (Taiwan tea) with better quality and less impurities; S2. Extraction: Take a suitable tea-water ratio of 1:175 and boil it in boiling water at 80℃ for 10 minutes, and combine it with microwave-assisted extraction for 2-5 minutes; S3. Filtration: After extraction, use a filter to filter out the tea residue to obtain a tea extract for later use; S4. Prepare tea-water ratio: add 5% sugar to the filtered tea extract (the ratio of white sugar to sugar alcohol is 4:1) and 0.25% citric acid; S5. Canning: Filling in glass bottles; S6. Sterilization: Sterilize in boiling water for 10 minutes; S7. Inoculation and fermentation: The activated lactobacillus is inoculated into the canned tea soup in an appropriate proportion (lactobacillus inoculation amount 4%), and the fermentation time is 16 hours; S8. Secondary sterilization: heat treatment sterilization to stop the continued fermentation; S9. Final processing: mark the production date and batch number of the prepared low-sugar fermented tea; then store the sterilized fermented tea beverage in a cool, dry place at a storage temperature of 4-10°C.

2. The method for preparing a high-quality low-sugar fermented tea beverage according to claim 1, characterized in that: In the step of S2. extraction, a Pu'er tea (Taidi tea) extract is prepared by combining a cooking method and a microwave-assisted extraction method: 1) Weighing Pu'er tea (Taiwan tea) leaves: Prepare an appropriate amount of Pu'er tea (Taiwan tea) leaves, usually 1 portion of tea leaves; 2) Weigh the water: Calculate the amount of hot water required according to the tea-water ratio of 1:175, i.e. 1 part of tea corresponds to 175 parts of water; then pour the water into the container and heat it to 80°C; 3) Processing Pu'er tea leaves: Break the tea cake into small pieces to increase the contact area between the Pu'er tea leaves and water; rinse the broken Pu'er tea leaves with room temperature water and soak for 5-10 minutes to remove floating impurities; 4) Rinse and soak: Rinse the crushed Pu'er tea leaves with room temperature water to remove surface impurities; then soak the Pu'er tea leaves in room temperature water for 5-10 minutes to remove impurities floating on the water surface again; 5) Mixing tea leaves and water: Mix the treated tea leaves with weighed water in a microwave-resistant container; 6) Combination of steaming and microwave-assisted extraction: First, heat the mixture to 80°C in a heating device and keep the temperature constant; then maintain the temperature at 80°C and steam for 10 minutes; moderate stirring can be performed during the entire steaming process to ensure uniform contact between the Pu'er tea (Taiwan tea) and the water. After steaming, transfer the container to a microwave device and use the microwave device to reheat the mixture to 80°C. The microwave heating time is 2-5 minutes. Be careful to avoid overheating to prevent the degradation of the active ingredients in the Pu'er tea (Taiwan tea). 7) Let stand: After turning off the heat, let stand for 2-3 minutes to allow the aroma and flavor of the Pu'er tea (Taidi tea) to fully blend; 8) Filtration: Filter out the tea juice, remove the tea residue, and obtain the Pu'er tea (Taiwan tea) extract after cooking.

3. The method for preparing a high-quality low-sugar fermented tea beverage according to claim 1, characterized in that: The S3. filtration step requires batch filtration and separation and packaging: 1) Prepare the filtering equipment: First, use a 100-mesh filter and filter cloth to ensure that they are clean and odor-free to prevent affecting the quality of the tea juice; preheat the filtering equipment before use, place the filter and filter cloth at the outlet of the tea extraction container, and rinse the filtering equipment with a small amount of hot water to reduce temperature loss during filtration; 2) Batch filtration: Pour the extracted tea soup slowly into the preheated filtration equipment several times; during the filtration process, keep the temperature of the tea juice between 75-85℃; then slowly pour the tea soup to make it flow evenly through the filter screen and filter cloth to ensure that the tea residue is fully separated to obtain a clear tea extract; First filtration: separate most of the tea residue; Second filtration: The tea juice after the first filtration is still not clear enough and needs to be filtered again; use the same 100 mesh filter and filter cloth; Third filtration: In industrial production, in order to improve efficiency and clarity, a vacuum filter is required; the vacuum degree is between 0.05 and 0.1 MPa to prevent excessive oxidation of the tea juice; 3) Collecting tea soup: Pour the filtered tea juice carefully into a clean container to obtain concentrated Pu'er tea juice; 4) Tea residue separation: The tea residue remaining on the filter or cloth after filtration should be collected in time; 5) Packaging and storage: Pack the filtered Pu'er tea (Taidi tea) extract into clean containers; then, the storage temperature should be controlled at 4-10℃ to maintain the quality and stability of the tea juice; Pu'er tea (Taiwan tea) extract can be stored for several days to several weeks.

4. The method for preparing a high-quality low-sugar fermented tea beverage according to claim 1, characterized in that: The S7. inoculation fermentation requires the glass bottle to be aseptically treated before filling, specifically as follows: the activated Lactobacillus (Lactobacillus bulgaricus) is inoculated into the canned tea soup according to an appropriate ratio (Lactobacillus inoculation amount 4%), and the fermentation time is 16h; 1) Activation of Lactobacillus: preparing a culture medium suitable for the growth of Lactobacillus, inoculating Lactobacillus bulgaricus into the culture medium; then culturing the inoculated culture medium at a suitable temperature (37° C.) for 12-18 hours until the Lactobacillus reaches a highly active state in the logarithmic growth phase; 2) Inoculation of tea beverage: Ensure that the tea beverage in the previous step (sterilization) has been cooled to room temperature to avoid high temperature killing lactobacillus; then inoculate the activated Lactobacillus bulgaricus into the tea beverage at a ratio of 4% (i.e., add 4 ml of Lactobacillus bulgaricus suspension to every 100 ml of tea extract); finally, gently stir the tea soup to evenly distribute the Lactobacillus bulgaricus in the tea beverage. 3) Fermentation: Transfer the inoculated tea soup to a constant temperature fermentation box, set the temperature to 28°C, and ensure that the fermentation container is well sealed to prevent external contamination; the fermentation time is set to 16 hours, and try to avoid opening the fermentation container frequently during this period; regularly observe the changes in the fermentation process, but avoid interference to ensure the fermentation effect; 4) Post-processing: After fermentation is completed, the fermented tea beverage is quickly cooled to room temperature to maintain the quantity and activity of Lactobacillus bulgaricus; after completion, the filtered fermented tea beverage is placed in a clean container and ensured to be well sealed; the container is stored under refrigerated conditions of 4-10°C to maintain the quality of the fermented tea beverage and the activity of the lactobacillus.

5. The method for preparing a high-quality low-sugar fermented tea beverage according to claim 1, characterized in that: The water in the tea-water ratio S4 is mineral water with a pH value in the range of 6.5-8.

5.

6. A stable and controllable high-quality Pu'er tea according to claims 1-5, characterized in that: The sensory score of the low-sugar fermented tea beverage is 92, the taste is mellow, and it has unique tea fragrance and fermentation aroma.

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