Clausena lansium fermented beverage and preparation method thereof

Abstract

The invention provides a clausena lansium fermented beverage and a preparation method thereof, and belongs to the technical field of beverage preparation. The invention provides a preparation method of a clausena lansium fermented beverage, which comprises the following steps: by taking compound bacteria of lactobacillus plantarum and lactobacillus fermentum as a fermentation inoculant, carrying out pH regulation and sterilization on juice of clausena lansium, fermenting, and then blending and homogenizing to obtain the clausena lansium fermented beverage. The clausena lansium fermented beverage provided by the invention is high in nutritional value, simple to operate, easy to master and suitable for factorization; the clausena lansium fermented beverage has stronger probiotic adaptability, can be retained in intestinal tracts for a longer time, and has longer time of taking effect on human bodies; the clausena lansium fermented beverage has relatively strong antioxidant activity, the content of flavone contained in the clausena lansium fermented beverage is remarkably increased, and the clausena lansium fermented beverage has pleasant fragrance, has relatively strong functionality and has multiple benefits on a human body.

Description

Technical Field

[0001] This invention belongs to the field of beverage preparation technology, specifically relating to a fermented beverage made from yellow peel fruit and its preparation method. Background Technology

[0002] Wampee is a tropical fruit with extremely high nutritional value, possessing properties that aid digestion, quench thirst, nourish the stomach, and relieve asthma. Fermentation of wampee by microorganisms not only breaks down the raw materials, releasing beneficial components and enhancing its nutritional value, but also plays a crucial role in the formation of flavor compounds in the fermented product. Due to its rich content of flavonoids and the different metabolites produced by different fermentation strains, fermented foods can improve the body's microecological environment, boost immunity, lower blood pressure and cholesterol, provide antioxidant effects, and delay aging. However, the deeper applications of wampee are relatively limited. Summary of the Invention

[0003] This invention provides a fermented beverage made from wampee fruit and its preparation method, wherein the fermented wampee fruit beverage has the effects of a functional beverage.

[0004] The present invention provides a method for preparing a fermented beverage of wampee fruit, comprising the following steps: (1) washing and cutting wampee fruit, adding a color-protecting solution and then juicing to obtain wampee fruit juice; (2) Adjust the pH of the yellow peel juice in step (1) to 6.5~7.5 and then sterilize to obtain sterile juice; (3) Inoculate the sterile juice in step (2) with a fermentation agent and ferment it to obtain fermented juice; the fermentation agent includes Lactobacillus plantarum and Lactobacillus fermentum. (4) The fermented juice described in step (3) is blended and homogenized to obtain the fermented yellow peel fruit beverage.

[0005] In a preferred embodiment of the present invention, the color-protecting solution in step (1) comprises vitamin C, calcium chloride and citric acid, and the mass ratio of vitamin C, calcium chloride and citric acid is 2:(1~2):(1~2).

[0006] In a preferred embodiment of the present invention, the weight ratio of the color-protecting solution to the fresh yellow-skinned fruit in step (1) is (1~1.5):1.

[0007] In a preferred embodiment of the present invention, the adjustment in step (2) includes removing the organic acids from the yellow peel juice and then adding an acidic or alkaline solution.

[0008] In a preferred embodiment of the present invention, the sterilization in step (2) includes pasteurization.

[0009] In a preferred embodiment of the present invention, the *Lactobacillus plantarum* in step (3) includes *Lactobacillus plantarum* CGMCC1.16089, the *Lactobacillus fermentum* includes *Lactobacillus fermentum* CGMCC1.15608, and the ratio of viable bacteria of *Lactobacillus plantarum* CGMCC1.16089 to *Lactobacillus fermentum* CGMCC1.15608 is (2~3):1.

[0010] In a preferred embodiment of the present invention, the inoculum amount of the fermentation agent is 1.5-2%.

[0011] In a preferred embodiment of the present invention, the fermentation in step (3) is anaerobic fermentation, with a temperature of 25~30℃ and a time of 3~7 days.

[0012] In a preferred embodiment of the present invention, step (4) of the preparation includes preparing the fermented fruit juice with a stabilizer, wherein the stabilizer is selected from at least one of the following: xanthan gum, CMC-Na and sodium alginate.

[0013] The present invention also provides a fermented beverage of wampee fruit prepared using the above preparation method.

[0014] Beneficial Effects: This invention provides a method for preparing a fermented beverage made from wampee fruit. A compound of *Lactobacillus plantarum* and *Lactobacillus fermentum* is used as the fermentation agent. The wampee fruit juice is pH adjusted and sterilized before fermentation, followed by blending and homogenization to obtain the fermented wampee fruit beverage. The fermentation agent selected in this invention exhibits enhanced adaptability and colonization ability in the intestines, and possesses good antioxidant activity; it also improves the overall taste of the fermented fruit juice.

[0015] The fermented wampee beverage provided by this invention has high nutritional value, is simple and easy to operate, and is suitable for industrial production. The probiotics in the fermented wampee beverage have stronger adaptability, can remain in the intestine for a longer time, and have a longer effective time for the human body. The fermented wampee beverage has strong antioxidant activity, contains significantly increased flavonoid content, and has a pleasant aroma. It has strong functionality and many benefits for the human body. Detailed Implementation

[0016] The present invention provides a method for preparing a fermented beverage of wampee fruit, comprising the following steps: (1) washing and cutting wampee fruit, adding a color-protecting solution and then juicing to obtain wampee fruit juice; (2) Adjust the pH of the yellow peel juice in step (1) to 6.5~7.5 and then sterilize to obtain sterile juice; (3) Inoculate the sterile juice in step (2) with a fermentation agent and ferment it to obtain fermented juice; the fermentation agent includes Lactobacillus plantarum and Lactobacillus fermentum. (4) The fermented juice described in step (3) is blended and homogenized to obtain the fermented yellow peel fruit beverage.

[0017] The preparation method of the present invention includes the following steps: raw material screening → cleaning and cutting → color protection → juicing → pH adjustment → sterilization → inoculation → fermentation → blending → homogenization and filling.

[0018] In preparing the fermented wampee beverage, this invention selects highly ripe fruits free from mold and rot, and refrigerates the pulp after separation. After washing, the wampee is cut into 1-3cm pieces for later use.

[0019] This invention uses a color-protecting solution to protect the color of small pieces of wampee fruit. The color-protecting solution comprises microbial vitamin C, calcium chloride, and citric acid, with a mass ratio of vitamin C, calcium chloride, and citric acid of 2:(1~2):(1~2). This can be 2:1:2, 2:2:1, or 1:1:1. In one embodiment, a 1:1:1 ratio is used, with each component accounting for 0.3% of the fresh fruit weight. The dry weight of each substance in the color-protecting solution accounts for 0.9% of the fresh fruit weight. The weight ratio of the color-protecting solution to the fresh fruit is (1~1.5):1. The color-protecting process involves soaking the fresh fruit pieces in the color-protecting solution and then juicing them together; no water needs to be added during this process.

[0020] This invention adjusts the pH of the obtained wampee juice. In one embodiment, organic acids are first adsorbed, and then an acidic solution such as citric acid or an alkaline solution such as NaOH solution is added to adjust the pH of the juice to 6.5-7.5. The adsorption of organic acids described in this invention can be achieved by adding 3% diatomaceous earth or polyamide resin after juicing, stirring for 20 minutes, and filtering until clear. In one embodiment of this invention, a mixture containing citric acid and ascorbic acid is added to the wampee juice to adjust the pH to 6.5-7.5.

[0021] The present invention involves sterilization after pH adjustment, wherein the sterilization is pasteurization, the sterilization temperature is 65°C, and the sterilization time is 30 minutes; the sterilization method preserves the flavor of the fermented yellow peel juice as much as possible.

[0022] This invention uses a fermentation agent composed of Lactobacillus plantarum and Lactobacillus fermentum for fermentation. The Lactobacillus plantarum in this invention includes Lactobacillus plantarum CGMCC1.16089, and the Lactobacillus fermentum includes Lactobacillus fermentum CGMCC1.15608. The ratio of viable bacteria of Lactobacillus plantarum CGMCC1.16089 to Lactobacillus fermentum CGMCC1.15608 is (2~3):1.

[0023] The fermentation agent of this invention is a bacterial suspension containing the two strains mentioned above. The process involves using an inoculation loop to pick a small number of colonies from the original strain slant under aseptic conditions, streaking them separately onto MRS medium, and incubating them at 37°C for 24 hours. Then, the colonies are picked and separately placed into MRS liquid medium, and incubated at 37°C on a shaker at 80 rpm for 24 hours. The resulting bacterial suspensions are then mixed to obtain the fermentation agent, which contains a total viable count of 10⁻⁶. 9 CFU / mL. The MRS culture medium of this invention comprises the following components at the following concentrations: glucose 2% (m / m), peptone 1% (m / m), yeast extract 0.5% (m / m), sodium acetate 0.5% (m / m), diammonium citrate 0.2% (m / m), dipotassium hydrogen phosphate 0.2% (m / m), manganese sulfate 0.0005% (m / m), magnesium sulfate 0.02% (m / m), Tween-80 1 mL / L medium, and agar 2% (added to solid medium) (m / m). The inoculum amount of the fermentation agent of this invention is 1.5~2%, and anaerobic fermentation is carried out at a temperature of 25~30℃ for 3~7 days.

[0024] After fermentation, the present invention utilizes a stabilizer for formulation. The stabilizer may be selected from at least one of the following: xanthan gum, CMC-Na, and sodium alginate, and the volume of the stabilizer added is 0.15% of the juice volume. In one embodiment of the present invention, a mixture of xanthan gum and CMC-Na is used as the stabilizer, and the mass ratio of xanthan gum to CMC-Na is 1:1.5.

[0025] After preparation, the present invention performs homogenization, which includes heating the prepared fruit juice to 45°C, pouring it into a homogenizer, and homogenizing it at 25~45 MPa for 15 minutes to enhance uniformity and stability.

[0026] The present invention also provides a fermented beverage of wampee fruit prepared using the above preparation method.

[0027] The fermented beverage made from wampee fruit described in this invention can significantly increase the flavonoid content in wampee juice, increase the functional active substances of wampee fruit, produce a pleasant aroma, and has higher intestinal adaptability, thus having broad market prospects.

[0028] To further illustrate the present invention, the following detailed description of a fermented beverage made from yellow peel fruit and its preparation method, in conjunction with embodiments, is provided by the present invention, but should not be construed as limiting the scope of protection of the present invention.

[0029] Example 1 Activation of *Lactobacillus plantarum* and *Lactobacillus fermentum*: A small number of colonies were picked from the original bacterial slant using an inoculation loop under aseptic conditions and streaked onto MRS medium. The culture was then placed in a 37°C incubator for 24 hours. After examination, no contaminating bacteria were observed; the colonies were uniform and abundant, and their morphology visually matched that of *Lactobacillus plantarum* and *Lactobacillus fermentum*. Smears were stained and tested for contamination. Colonies were then picked and placed in MRS liquid medium and incubated at 37°C with a shaker at 80 rpm for 24 hours.

[0030] Example 2 Preparation process of fermented beverage made from yellow peel fruit (Lactobacillus plantarum): 2.1 Selection of raw materials: Select fruits with high maturity and no mold or rot (accounting for 40%~60%), and refrigerate them after separating the pulp for later use.

[0031] 2.2 Cut the yellow-skinned fruit into small pieces of 1-3cm and set aside.

[0032] 2.3 Color protection: Prepare a color protection solution according to the ratio of Vitamin C: Calcium chloride: Citric acid 1:1:1, each accounting for 0.3% of the weight of fresh fruit (total 0.9%). 2.4 Juicing: Fresh fruit weight: Color-protecting solution = 1:1.

[0033] 2.5 Adjust pH: Adjust the pH to between 6.5 and 7.5.

[0034] 2.6 Fermentation: Lactobacillus plantarum and Lactobacillus fermentum seed liquid were inoculated into the prepared fruit juice at an inoculation rate of 1.5-2% of the fruit juice volume ratio. The ratio of Lactobacillus plantarum to Lactobacillus fermentum seed liquid was 3:1. The fermentation temperature was 25-30℃, the initial pH was 6.5-7.5, and the fermentation time was 24h.

[0035] 2.7 Blending: Add xanthan gum and CMC-Na (1:1.5, total addition 0.15%) for blending.

[0036] 2.8 Homogenization: Heat the prepared fruit juice to 45℃, pour it into a homogenizer and homogenize for 15 minutes at 30 MPa to enhance uniformity and stability.

[0037] Comparative Example 1 Except for the fermentation strain being Lactobacillus fermentum, the rest of the contents are the same as in Example 2.

[0038] Comparative Example 2 Except for the fermentation strain being Lactobacillus plantarum, the rest of the contents are the same as in Example 2.

[0039] Comparative Example 3 Except for the ratio of Lactobacillus plantarum to Lactobacillus fermentum seed liquid being 1:1, the other operations were the same as in Example 2.

[0040] Comparative Example 4 Except for the ratio of Lactobacillus plantarum to Lactobacillus fermentum seed liquid being 1:3, the other operations were the same as in Example 2.

[0041] Comparative Example 5 Except for the ratio of Lactobacillus plantarum to Lactobacillus fermentum seed liquid being 5:1, the other operations were the same as in Example 2.

[0042] Comparative Example 6 Except for the ratio of Lactobacillus plantarum to Lactobacillus fermentum seed liquid being 1:5, the other operations were the same as in Example 2.

[0043] Comparative Example 7 Except for the absence of added microbial agents and natural fermentation, the other operations are the same as in Example 2.

[0044] Comparative Example 8 Compared with Example 2, this comparative example uses a 3:1 ratio of Lactobacillus plantarum and Lactobacillus fermentum and ferments for 8 hours, but the other operations are the same as in Example 2.

[0045] Example 3 Determination of total acidity in fermented beverages made from wampee fruit: Pour 100 mL of sample into a 500 mL beaker and incubate in a 45°C water bath for 30 min (or shake under reduced pressure for 5 min) until no bubbles remain. Transfer the treated sample to a 250 mL volumetric flask and dilute to the mark, then mix well. Turn on the pH meter and preheat for 30 min. Calibrate the electrode sequentially using pH 4.01, 7.00, and 9.21 buffer solutions. Place the beaker on a magnetic stirrer and insert the pH electrode (immersed below the liquid surface). Start stirring and add 0.1 mol / L NaOH dropwise using a burette at an initial rate of 2 mL / min. Near the endpoint (pH ≥ 7.0), reduce the addition to 0.1 mL at a time. Record the pH value after each addition until the titration endpoint.

[0046] Total acidity is one of the key parameters for evaluating the quality of fermented beverages. It reflects the progress of the fermentation process and the acidity level of the final product. The total acid content needs to be balanced with other flavor components such as sweetness and aroma. Appropriate acidity can enhance the refreshing sensation, mask off-flavors, and highlight other flavors, making the beverage more harmonious and palatable. Too low an acidity will result in a bland taste, while too high an acidity may be overly pungent and sharp. The total acidity test results are shown in Table 1. In Example 2, the total acid content of the fermented beverage after 24 hours was greater than that of the fermented beverages of Comparative Examples 1, 2, 3, 7, and 8, but less than that of the fermented beverages of Comparative Examples 4, 5, and 6. The total acid content of the fermented beverage in Example 2 is within the reasonable range for fermented beverages.

[0047] Table 1. Total acid determination results (g / 100ml lactic acid)

[0048] Example 4 Determination of total flavonoid content: Accurately weigh the dried, constant-weight rutin standard and dissolve it in 60% or 70% ethanol to prepare a stock solution with a concentration of 0.1 mg / mL. Take several test tubes and accurately add different volumes of the rutin stock solution to each tube, then bring the volume to 5.0 mL with 60% or 70% ethanol. Add 0.3 mL of 5% NaNO2 solution to each tube, shake well, and let stand for 6 minutes. Add 0.3 mL of 10% Al(NO3)3 solution, shake well, and let stand for 6 minutes. Add 4 mL of 4% NaOH solution. Make up to 10 mL with 60% or 70% ethanol, shake well, and let stand for 15 minutes. Using the first tube (0 mL of standard solution, containing only solvent and reagents) as a blank control, measure the absorbance (A) of each standard solution at a wavelength of 510 nm. Plot a standard curve with rutin concentration (mg / L) on the x-axis (X) and absorbance (A) on the y-axis (Y). Take a certain amount of sample, add an appropriate amount of activated carbon, pre-activate and test its non-adsorption of flavonoids, shake or sonicate for 30 minutes, filter or centrifuge to collect the supernatant. Optimize the amount of activated carbon and treatment time to ensure effective decolorization and minimal flavonoid loss. Add an equal volume of organic solvent such as ethanol or acetone to precipitate proteins, centrifuge and collect the supernatant. Dilute the treated sample appropriately with 60% or 70% ethanol so that its absorbance falls within the linear range of the standard curve. Take a certain volume of the diluted sample solution and place it in a test tube. Perform the operation under the exact same conditions and reagent amounts as for plotting the standard curve colorimetric reaction.

[0049] Total flavonoids in fermented beverages are one of the core components responsible for their health benefits. Based on their powerful antioxidant and anti-inflammatory effects, they provide numerous health benefits, including cardiovascular protection, immune regulation, gut microbiota balance, and neuroprotection. Flavonoids are potent antioxidants that effectively scavenge free radicals in the body, such as reactive oxygen species (ROS) and reactive nitrogen species (RNS). Neutralizing free radicals protects cells (including DNA, proteins, and lipids) from oxidative damage, a key mechanism for preventing various chronic diseases (such as cardiovascular disease, cancer, and neurodegenerative diseases) and delaying aging. The total flavonoid content results are shown in Table 2. In Example 2, the total flavonoid content after 24 hours of fermentation was higher than in all other comparative groups. Among the three fermentation methods, *Lactobacillus plantarum* showed a higher total flavonoid content after 24 hours of fermentation, indicating stronger functionality in its fermented beverage.

[0050] Table 2 Total flavonoid content (mgre / L)

[0051] Example 5 Trolox equivalent determination Accurately weigh a certain amount of ABTS powder and place it in a 100mL brown volumetric flask. Add approximately 80mL of ultrapure water and shake or sonicate until completely dissolved. Accurately weigh potassium persulfate and add it to the ABTS solution. Gently shake to ensure dissolution. Dilute to 100mL with ultrapure water. The concentration of ABTS in this solution is approximately 7mM, and the concentration of potassium persulfate is approximately 2.45mM. Place the brown volumetric flask at room temperature (approximately 25°C) in the dark to allow the oxidation reaction to proceed completely, which requires 12-16 hours. At this time, the solution should be a deep blue-green color. The ABTS after complete reaction... + The stock solution is relatively stable at room temperature and in the dark. Take an appropriate amount of the prepared ABTS. + The stock solution was diluted with PBS buffer (pH 7.4). When measured at 734 nm using a 1 cm path length cuvette, the absorbance (Abs) remained stable between 0.70 ± 0.02. The diluted ABTS... + The working solution was equilibrated in a 30°C or 37°C water bath for at least 30 minutes. Accurately weigh Trolox, dissolve it in PBS, transfer it to a 25 mL amber volumetric flask, and dilute to the mark with PBS buffer. This yields a 1.0 mM stock solution. Serially dilute the Trolox stock solution with PBS buffer to prepare at least six concentration points. Thoroughly mix the fermented beverage sample. Based on the expected antioxidant capacity, test the clarified sample with PBS buffer. Preheat the spectrophotometer and set the wavelength to 734 nm. Zero the spectrophotometer with PBS buffer. Add 3.9 mL of preheated ABTS to a cuvette. + Add 0.1 mL of PBS buffer to the working solution. Immediately cap the container and gently invert several times to mix. Timing is precise for 6 minutes after adding PBS, and the absorbance value (Abs_blank) is read. Take another cuvette and add 3.9 mL of ABTS. + Add 0.1 mL of a Trolox standard solution of a specific concentration to the working solution. Mix immediately and read the absorbance value (Abs_standard) at the exact same reaction time as the blank control. Repeat the measurement 2-3 times for each concentration point. Take a cuvette and add 3.9 mL of ABTS. + Add 0.1 mL of appropriately diluted clear sample solution to the working solution. Mix immediately and read the absorbance value (Abs_sample) at the same reaction time. Repeat the measurement 2-3 times for each dilution.

[0052] The main function of Trolox equivalent is to objectively measure, standardize, compare, and evaluate the comprehensive ability of fermented beverages to scavenge free radicals or resist oxidation. It reflects the sum of the combined effects of all natural antioxidants in the beverage, rather than the actual amount of Trolox added. The Trolox equivalent determination results are shown in Table 3. The fermented beverage in Example 2 had the highest Trolox equivalent. In the other comparative groups, changes in conditions could not increase the Trolox equivalent to that of Example 2, proving that Example 2 was the optimal formulation. Based on the Trolox equivalent in the three fermented beverages, it can be concluded that the *Lactobacillus plantarum* fermented beverage has stronger functionality than the other two fermented beverages and is more suitable as a strain for fermenting *Lactobacillus thuringiensis* fruit.

[0053] Table 3 Trolox equivalent (μmol TE / L)

[0054] Example 6 Determination of differential metabolites in three fermented beverages: Chromatographic conditions: Thermo Vanquish (Thermo Fisher Scientific, USA) ultra-high performance liquid chromatography system, using an ACQUITY UPLC® HSS T3 (2.1×100 mm, 1.8 µm) column (Waters, Milford, MA, USA), flow rate of 0.3 mL / min, column temperature of 40 °C, injection volume of 2 μL.

[0055] In positive ion mode, the mobile phase consisted of 0.1% formic acid acetonitrile (B2) and 0.1% formic acid water (A2), with the gradient elution program as follows: 0–1 min, 10% B2; 1–5 min, 10%–98% B2; 5–6.5 min, 98% B2; 6.5–6.6 min, 98%–10% B2; 6.6–8 min, 10% B2.

[0056] In negative ion mode, the mobile phase consisted of acetonitrile (B3) and 5 mM ammonium formate aqueous solution (A3), with the gradient elution program as follows: 0–1 min, 10% B3; 1–5 min, 10%–98% B3; 5–6.5 min, 98% B3; 6.5–6.6 min, 98%–10% B3; 6.6–8 min, 10% B3.

[0057] Mass spectrometry conditions: Thermo Q Exactive Focus mass spectrometer (Thermo Fisher Scientific, USA), electrospray ionization (ESI) source, and data acquisition in both positive and negative ion modes. The positive ion spray voltage was 3.50 kV, the negative ion spray voltage was -2.50 kV, the sheath gas was 40 alb, and the auxiliary gas was 10 alb. The capillary temperature was 325 °C. A first-stage full scan was performed at a resolution of 70,000 m / z, with a first-stage ion scan range of 100–1000 m / z. Second-stage fragmentation was performed using an HCD with a collision energy of 30 eV and a second-stage resolution of 17,500 m / z. The first three ions acquired were fragmented, and unnecessary MS / MS information was removed using dynamic exclusion.

[0058] The results of the determination of differential metabolites in the three fermented beverages are shown in Table 4. The beneficial functional substances are selected based on their status as essential nutrients, antioxidants, key metabolic intermediates, or active substances with clear health benefits. The content of functional metabolites in the differential metabolites determines the strength of the fermented beverage's functionality. Specifically, the fermented beverage of Example 2 had a higher content of beneficial functional metabolites than the other control groups, indicating that the fermented beverage of Example 2 has stronger functionality.

[0059] Table 4. Results of determination of differential metabolites in three fermented beverages

[0060] Example 7 Sensory evaluation of different fermented beverages made from wampee fruit Table 5 Sensory evaluation standards for fermented juices of different wampee fruits

[0061] Table 6 Sensory evaluation results of different fermented juices from wampee fruit

[0062] As shown in Table 6, the sensory evaluation results of different fermented beverages made from yellow peel fruit indicate that the fermented fruit juice prepared with Lactobacillus plantarum and Lactobacillus fermentum greatly enhances the floral and fruity aroma of the juice and reduces the irritating taste. In terms of taste, the combined use of Lactobacillus plantarum and Lactobacillus fermentum can improve the sweetness and umami of the fermented fruit juice, reduce the bitterness, and make the taste and flavor of the fermented fruit juice more mellow and rich, making it more acceptable to the public.

[0063] Based on the above examples and comparative examples, the fermented beverage obtained by mixing Lactobacillus plantarum and Lactobacillus fermentum seed liquid in a 3:1 ratio has a more reasonable total acidity, higher total flavonoid content and Trolox equivalent, and also has more differential metabolites that are beneficial to the human body, indicating that the fermented beverage obtained by this combination of fermentation has stronger functionality and better taste.

[0064] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing a fermented beverage made from wampee fruit, characterized in that, Includes the following steps: (1) Wash and cut the wampee fruit, add color-protecting solution and juice it to obtain wampee juice; (2) Adjust the pH of the yellow peel juice in step (1) to 6.5~7.5 and then sterilize to obtain sterile juice; (3) Inoculate the sterile juice in step (2) with a fermentation agent and ferment it to obtain fermented juice; the fermentation agent includes Lactobacillus plantarum and Lactobacillus fermentum. (4) The fermented juice described in step (3) is blended and homogenized to obtain the fermented yellow peel fruit beverage.

2. The preparation method according to claim 1, characterized in that, The color-protecting solution in step (1) comprises vitamin C, calcium chloride and citric acid, and the mass ratio of vitamin C, calcium chloride and citric acid is 2:(1~2):(1~2).

3. The preparation method according to claim 1 or 2, characterized in that, The weight ratio of the color-protecting solution to the fresh yellow-skinned fruit in step (1) is (1~1.5):

1.

4. The preparation method according to claim 1, characterized in that, The adjustment in step (2) includes removing the organic acids from the yellow peel juice and then adding an acidic or alkaline solution.

5. The preparation method according to claim 1, characterized in that, The sterilization described in step (2) includes pasteurization.

6. The preparation method according to claim 1, characterized in that, In step (3), the *Lactobacillus plantarum* includes *Lactobacillus plantarum* CGMCC1.16089, and the *Lactobacillus fermentum* includes *Lactobacillus fermentum* CGMCC1.15608, and the ratio of viable bacteria of *Lactobacillus plantarum* CGMCC1.16089 to *Lactobacillus fermentum* CGMCC1.15608 is (2~3):

1.

7. The preparation method according to claim 6, characterized in that, The inoculum amount of the fermentation agent is 1.5-2%.

8. The preparation method according to claim 1, characterized in that, The fermentation in step (3) is anaerobic fermentation, with a temperature of 25~30℃ and a time of 3~7 days.

9. The preparation method according to claim 1, characterized in that, Step (4) involves blending the fermented fruit juice with a stabilizer selected from at least one of the following: xanthan gum, CMC-Na and sodium alginate.

10. A fermented beverage made from yellow peel fruit using the preparation method according to any one of claims 1 to 9.

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