Steam water capable of keeping flavor of fresh litchi fruits and preparation process of steam water

Abstract

The invention discloses soda water capable of keeping the flavor of fresh litchi fruits and a preparation technology of the soda water, and belongs to the technical field of beverage processing. The preparation method comprises the following steps: by taking fresh litchis as a raw material, carrying out pretreatment pulping, and then carrying out low-temperature enzymolysis by adopting a pectinase, xylanase and beta-glucosidase composite system, so as to prepare clarified litchi juice; then inoculating a compound yeast liquid composed of Wickerhamomyces anomalus and kiwi yeast for fermentation to prepare a litchi fermentation base liquid; the preparation method comprises the following steps: preparing a base material, homogenizing at low temperature, sterilizing at low temperature, degassing in vacuum, carbonating at low temperature and high pressure, and aseptically filling to obtain a finished product. A full-chain low-temperature processing system is constructed, thermal deterioration of characteristic aroma of litchis is avoided, the flavor plumpness is improved through cooperation of enzymolysis and compound fermentation, and the technical problems that traditional litchi flavored soda water is too heavy in flavor feeling, thin in taste and lack of fresh fruit feeling are solved. The prepared product is natural and full in litchi flavor, prominent in fresh fruit feeling, fine and lasting in bubble, stable and controllable in process and suitable for industrial large-scale production.

Description

Technical Field

[0001] This invention belongs to the field of beverage processing technology, specifically relating to a soft drink that retains the flavor of fresh lychee fruit and its preparation process. Background Technology

[0002] Lychee is a specialty and high-quality fruit of the Lingnan region of my country. Its flesh is sweet and juicy, rich in sugars, vitamins, amino acids, and various volatile flavor compounds, possessing both high nutritional and economic value. It is one of the core economic crops in South my country. However, fresh lychee fruits undergo vigorous physiological metabolism after harvest, making them highly susceptible to browning and rotting. Their shelf life at room temperature is extremely short, severely restricting cross-regional distribution and value-added enhancement in the lychee industry. Therefore, deep processing is the core approach to extending the lychee industrial chain and absorbing fresh fruit production capacity.

[0003] Carbonated beverages are a core category in my country's beverage market, and lychee flavor, with its refreshing sweetness, is highly favored by consumers and is one of the mainstream flavors of carbonated beverages. However, existing lychee-flavored soft drink products and related preparation technologies have significant technical deficiencies: I. Most mainstream commercially available products use artificial flavorings directly, which can only simulate the basic sweet aroma of lychee. They cannot reproduce the unique fresh and fruity aroma, honey sweetness and flavor layers of fresh lychee. They have problems such as excessive artificial flavoring, thin taste, bitter aftertaste and complete lack of fresh fruit flavor, and cannot meet consumers' demand for natural, healthy and authentic beverages.

[0004] Second, a small number of products made from lychee juice generally employ high-temperature enzymatic hydrolysis, high-temperature enzyme inactivation, ultra-high temperature instantaneous sterilization, or pasteurization processes to increase juice yield and achieve commercial sterility. However, the characteristic aroma components of lychee (such as cis-rosine ether and linalool) are mostly heat-sensitive substances. High-temperature processing will cause a large amount of them to volatilize and degrade, while producing unpleasant cooked flavors and Maillard browning. Ultimately, the product completely loses the fresh flavor of fresh lychee and has a severely insufficient fresh fruit taste.

[0005] Third, existing technologies for enhancing the flavor of lychee beverages through fermentation mostly use a single brewing yeast for high-temperature fermentation. The fermentation process easily produces too much alcohol and off-flavors, destroying the original flavor of lychee. Moreover, it is impossible to accurately generate esters and alcohols that match the flavor of fresh lychee fruit, making it difficult to achieve a synergistic enhancement of flavor. At the same time, high-temperature fermentation also causes the deterioration of aroma substances. Summary of the Invention

[0006] To address the shortcomings of existing lychee-flavored soft drinks, such as excessive artificial flavoring, thin taste, flavor degradation due to high-temperature processing, loss of fresh fruit flavor, and poor flavor synergy in fermentation processes, this invention aims to provide a soft drink that retains the flavor of fresh lychee and its preparation process. Through the synergistic action of pectinase, xylanase, and β-glucosidase, the yield and clarity of lychee juice are increased under low-temperature conditions. Simultaneously, hydrolysis releases characteristic aroma precursors bound in lychee, enhancing the flavor fullness of the juice from the source. Furthermore, a complex yeast fermentation system is constructed, using a combination of *Saccharomyces cerevisiae* and *Saccharomyces cerevisiae* to precisely generate esters and alcohols that match the flavor of fresh lychee, supplementing the flavor layers and sweetness, and avoiding the off-flavors and monotonous flavor problems associated with single-yeast fermentation.

[0007] To achieve the above objectives, the present invention discloses the following technical solutions: In a first aspect, the present invention provides a process for preparing a soft drink that retains the flavor of fresh lychee fruit, comprising the following steps: S1. Fresh lychees are pre-treated and pulped to obtain lychee pulp. The lychee pulp is then subjected to compound enzymatic hydrolysis. After enzymatic hydrolysis, the supernatant is collected by centrifugation and filtration to obtain clear lychee juice. S2. The clarified lychee juice obtained in S1 is inoculated into the compound yeast liquid for fermentation. After the fermentation is terminated, it is sterilized to obtain the lychee fermentation base liquid. S3. Mix the clarified lychee juice from S1, the fermented lychee base liquid from S2, sweetener, acidity regulator, compound lychee characteristic flavoring, and drinking water, and stir evenly after adjusting the volume to obtain the blended base liquid. S4. The base liquid is homogenized and sterilized at low temperature, then vacuum degassed. The degassed base liquid is then carbonated and immediately bottled to obtain the soda that retains the flavor of fresh lychee fruit.

[0008] Preferably, in step S1, the process parameters for the compound enzymatic hydrolysis are as follows: the compound enzyme is composed of pectinase, xylanase, and β-glucosidase in a mass ratio of (2-4):(1-3):1; the enzymatic hydrolysis temperature is controlled at 4℃-12℃; the amount of compound enzyme added is 0.2%-0.8% of the total mass of litchi pulp; and the enzymatic hydrolysis time is 8h-24h.

[0009] Preferably, in step S1, the pretreatment includes peeling, washing, removing pits, and crushing; the centrifugation speed is 4000-6000 r / min, the centrifugation time is 10-20 min, and the centrifugation temperature is 4℃-10℃; the filtration uses a 200-400 mesh filter bag for negative pressure filtration.

[0010] Preferably, in step S2, the compound yeast liquid is a combination of abnormal Wickham yeast liquid and strange yeast liquid; The viable count of *Wickham's abnormal yeast* in the compound yeast solution was (5-8) × 10⁻⁶. 8 CFU / mL, viable count of *Saccharomyces cerevisiae* was (1–3) × 10⁻⁶. 8 The inoculation amount of the compound yeast liquid is 5-7 v / v, the fermentation temperature is controlled at 20℃-26℃, and the fermentation time is 24h-36h.

[0011] Preferably, in step S3, the percentage of each raw material by the total mass of the base liquid is as follows: 20%–40% lychee clarified juice, 5%–15% lychee fermentation base liquid, 4%–10% sweetener, 0.1%–0.3% acidity regulator, 0.001%–0.005% compound lychee characteristic flavoring, and the remainder is drinking water.

[0012] More preferably, the sweetener is one or more combinations of white sugar, erythritol, and fructose syrup; The acidity regulator is one or more of citric acid, malic acid, and sodium citrate; The compound lychee characteristic flavoring is composed of cis-rose ether, linalool, geraniol, citral, and hexanal in a mass ratio of (4-6):(2-4):(1-3):1:1.

[0013] Preferably, in step S4, the homogenization temperature is 4℃~10℃, the homogenization pressure is 20~30MPa, and the homogenization process is performed twice.

[0014] Preferably, in step S4, the low-temperature sterilization process is HPP sterilization, with sterilization parameters of 400 MPa and sterilization time of 2-5 min.

[0015] Preferably, in step S4, the vacuum degassing temperature is 4℃~10℃, the vacuum degree is -0.06MPa~-0.08MPa, and the degassing time is 5~10min.

[0016] Preferably, in step S5, the carbonation temperature is 2℃~6℃, the system pressure is 0.4~0.6MPa, and the carbon dioxide dissolution and pressure holding time is 15~30min.

[0017] Secondly, the present invention provides a soft drink that retains the flavor of fresh lychee fruit, the soft drink being prepared using the preparation process described in the first aspect.

[0018] The beneficial effects of this invention are: 1. This invention maximizes the preservation of the flavor of fresh lychee. From compound enzymatic hydrolysis, post-fermentation sterilization, blending, homogenization, sterilization, vacuum degassing to carbonation and filling, the core processes are all carried out at a low temperature below 26℃, and the core flavor preservation process is controlled at a low temperature below 12℃. This completely avoids the destruction of the heat-sensitive aroma substances of lychee by high-temperature processing, eliminates flavor deterioration problems such as cooked taste and browning, and locks in the natural fresh flavor of fresh lychee to the greatest extent. 2. This invention employs a compound enzymatic hydrolysis process in which pectinase, xylanase, and β-glucosidase are combined in a specific ratio, which enhances the flavor fullness and naturalness of lychee juice. The synergistic effect of the three is far superior to that of single enzyme or binary enzyme compound systems, and none of them can be omitted. 3. This invention uses a specific ratio of live bacteria to ferment abnormal Wickham yeast and exotic yeast. The abnormal Wickham yeast can efficiently generate floral and fruity esters to enhance the freshness of lychee, while the exotic yeast can generate higher alcohols to enhance the sweetness and flavor complexity of lychee. The synergistic fermentation of the two can precisely generate trace flavor substances that are highly matched with the flavor of fresh lychee. No high-temperature treatment is required, which avoids the problem of single-yeast fermentation with a single flavor and prominent off-flavors, and further enhances the freshness and fullness of the product, forming a flavor synergy with the original lychee juice. Detailed Implementation

[0019] To better illustrate the objectives, technical solutions, and advantages of this invention, the invention will be further described below with reference to specific embodiments. Those skilled in the art should understand that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0020] Unless otherwise specified, the test methods used in the examples and comparative examples are conventional methods; the materials and reagents used are commercially available unless otherwise specified; and the percentages mentioned in the examples and comparative examples are mass percentages unless otherwise specified.

[0021] I. In this invention Pectinase: Enzyme activity 5000U / g, purchased from Novozymes (China) Biotechnology Co., Ltd.; Xylanase: enzyme activity 12000U / g, purchased from Novozymes (China) Biotechnology Co., Ltd.; β-glucosidase: enzyme activity 20000U / g, purchased from Novozymes (China) Biotechnology Co., Ltd.; Abnormal Wickham yeast: purchased from China General Microbiological Culture Collection Center, accession number CGMCC2.1315; Yeast extract: purchased from China General Microbiological Culture Collection Center, accession number CGMCC 2.5013; All other raw materials are commercially available.

[0022] II. Lychee-flavored soft drinks 1. Examples 1-3 Example 1: The preparation process of lychee-flavored soft drink is as follows: S1. Select lychees that are free from rot and pests. Peel, wash with clean water, remove the pits, crush and pulp to obtain lychee pulp. Add a compound enzyme to the lychee pulp. The compound enzyme is composed of pectinase, xylanase and β-glucosidase in a mass ratio of 3:2:1. The amount added is 0.5% of the total mass of the lychee pulp. Place it in a constant temperature environment of 8℃ for 16 hours for enzymatic hydrolysis. After the enzymatic hydrolysis is completed, centrifuge at 5000r / min for 15 minutes at 6℃ to remove fruit pulp residue. Then filter the supernatant through a 300-mesh food-grade filter bag under negative pressure to obtain clear lychee juice. Store at 4℃ in the dark for later use. S2. Inoculate the clarified lychee juice obtained in S1 into the compound yeast solution at an inoculation rate of 6 v / v%, wherein the compound yeast solution contains 5 × 10⁻⁶ viable bacteria. 8 The abnormal Wickham yeast CFU / mL and viable count were 3 × 10⁻⁶. 8 The *Saccharomyces cerevisiae* was fermented at 24°C under aeration for 24 hours. After fermentation, the cells were removed by centrifugation at 6000 r / min for 12 min, and then sterilized by microfiltration through a 0.22 μm sterile membrane to obtain the litchi fermentation base liquid. S3. Based on a total mass of 100 kg of base liquid, add 6 kg of white sugar, 2 kg of erythritol, 0.15 kg of citric acid, and 0.07 kg of malic acid to drinking water in sequence. Stir until completely dissolved, then add 30 kg of clarified lychee juice from S1 and 10 kg of lychee fermentation base liquid from S2. Stir evenly, then add 0.003 kg of compound lychee characteristic flavoring, and bring the volume to 100 kg. Stir thoroughly for 15 minutes to obtain the base liquid. The compound lychee characteristic flavoring is composed of cis-rose ether, linalool, geraniol, citral, and hexanal in a mass ratio of 5:3:2:1:1. S4. The prepared base liquid is fed into a low-temperature homogenizer and homogenized twice at 8°C and 25MPa. After homogenization, it is fed into an HPP sterilizer with sterilization parameters of 400MPa and sterilization time of 4min. Then it is fed into a vacuum degasser and degassed at 8°C and -0.07MPa for 8min. The degassed base liquid is cooled to 4°C and fed into a carbonation tank. The temperature inside the tank is controlled at 4°C and the pressure at 0.5MPa. The pressure is maintained for 20min to allow carbon dioxide to dissolve completely. Then it is filled and capped in an aseptic environment to obtain the lychee fresh fruit flavored soda of Example 1.

[0023] The difference between the preparation process of the lychee-flavored soft drink in Example 2 and that in Example 1 is as follows: In step S1, the mass ratio of pectinase, xylanase, and β-glucosidase in the complex enzyme is adjusted to 2:1:1. In step S2, the inoculation amount of the compound yeast liquid is adjusted to 7 v / v, and the viable count of the abnormal Wickham yeast is adjusted to 8 × 10⁻⁶. 8 CFU / mL, the viable count of *Saccharomyces cerevisiae* was adjusted to 1×10⁻⁶. 8 CFU / mL; The rest is the same as in Example 1, resulting in the lychee-flavored soft drink of Example 2.

[0024] The difference between the preparation process of the lychee-flavored soft drink in Example 3 and that in Example 1 is as follows: In step S1, the mass ratio of pectinase, xylanase, and β-glucosidase in the complex enzyme is adjusted to 4:3:1. In step S2, the inoculation amount of the compound yeast liquid is adjusted to 5 v / v%, and the viable count of the abnormal Wickham yeast is adjusted to 7 × 10⁻⁶. 8 CFU / mL, the viable count of *Saccharomyces cerevisiae* was adjusted to 2 × 10⁻⁶. 8 CFU / mL; The rest is the same as in Example 1, resulting in the lychee-flavored soft drink of Example 3.

[0025] 2. Comparative Examples 1-7 The difference between the preparation process of the soft drink in Comparative Example 1 and that in Example 1 is: In step S1, the complex enzyme contains only xylanase and β-glucosidase in a mass ratio of 2:1, and the rest is the same as in Example 1, to obtain Comparative Example 1 soda.

[0026] The difference between the preparation process of the soft drink in Comparative Example 2 and that in Example 1 is: In step S1, the complex enzyme contains only pectinase and β-glucosidase in a mass ratio of 3:1, and the rest is the same as in Example 1, to obtain Comparative Example 2 soda.

[0027] The difference between the preparation process of the soft drink in Comparative Example 3 and that in Example 1 is: In step S1, the complex enzyme contains only pectinase and xylanase in a mass ratio of 3:2, and the rest is the same as in Example 1, to obtain Comparative Example 3 soda.

[0028] The difference between the preparation process of the soft drink in Comparative Example 4 and that in Example 1 is: In step S2, the compound yeast solution is adjusted to a separate abnormal Wickham yeast solution, that is, 5 × 10⁶ live bacteria are inoculated into the clarified lychee juice. 8The abnormal Wickham yeast culture with CFU / mL was inoculated at a rate of 6 v / v% and fermented at 24°C under aeration for 24 h. After fermentation, the cells were removed by centrifugation at 6000 r / min for 12 min, and then sterilized by microfiltration through a 0.22 μm sterile membrane to obtain the litchi fermentation base liquid. The rest was the same as in Example 1, resulting in Comparative Example 4 carbonated water.

[0029] The difference between the preparation process of Comparative Example 5 soda and Example 1 is that: In step S2, the compound yeast liquid is adjusted to a separate *Exotic* yeast liquid, that is, 3 × 10⁻⁶ live bacteria are inoculated into the clarified lychee juice. 8 The *Saccharomyces cerevisiae* culture with a concentration of CFU / mL was inoculated at a rate of 6 v / v% and fermented at 24°C under aeration for 24 h. After fermentation, the culture was removed by centrifugation at 6000 r / min for 12 min, and then sterilized by microfiltration through a 0.22 μm sterile membrane to obtain the litchi fermentation base liquid. The rest was the same as in Example 1, resulting in Comparative Example 5 carbonated water.

[0030] The difference between the preparation process of Comparative Example 6 soda and Example 1 is that: In step S2, the viable counts of *Saccharomyces cerevisiae* and *Saccharomyces cerevisiae* in the compound yeast solution are adjusted so that the viable count of *Saccharomyces cerevisiae* is 1 × 10⁻⁶. 8 CFU / mL, viable count of *Saccharomyces cerevisiae* 1×10⁻⁶ 8 The inoculum was the same as in Example 1, and fermented at 24°C under aeration for 24 hours. After fermentation, the cells were removed by centrifugation at 6000 r / min for 12 min, and then sterilized by microfiltration through a 0.22 μm sterile membrane to obtain the litchi fermentation base liquid. The rest was the same as in Example 1, and the resulting Comparative Example 6 carbonated water was obtained.

[0031] The preparation process of the soft drink in Comparative Example 7 is as follows: This comparative example is a commercially available lychee soda with conventional flavorings. The formula is as follows: 8 kg of white sugar, 2 kg of fructose syrup, 0.2 kg of citric acid, 0.05 kg of sodium citrate, 0.08 kg of compound lychee characteristic flavorings, 0.01 kg of caramel color, 0.03 kg of sodium benzoate, and drinking water to a final volume of 100 kg. The soda of Comparative Example 7 was prepared by blending, homogenizing, carbonation, bottling, and sterilization. The compound lychee characteristic flavoring is composed of cis-rose ether, linalool, geraniol, citral, and hexanal in a mass ratio of 5:3:2:1:1.

[0032] III. Performance Testing Twenty professional sensory evaluators (10 men and 10 women, all with professional qualifications in beverage sensory evaluation) were invited to conduct sensory evaluation tests on the lychee sodas prepared in Examples 1-3 and Comparative Examples 1-7. The products were scored from five dimensions: lychee flavor, fresh fruit taste, artificial flavor, fullness of taste, and effervescence. Each item was scored out of 20 points. The scoring criteria are shown in Table 1. The final score for each dimension was the average of the scores given by each evaluator. The results are shown in Table 2.

[0033] Table 1 Sensory Evaluation Scoring Criteria Rating Dimensions 20 points (Excellent) 10 points (medium) 0 points (poor) Lychee flavor It has a pure flavor and completely reproduces the characteristic aroma of fresh lychee, with no off-flavors. It has a basic lychee flavor, but the aroma is not prominent and there is a slight off-odor. It lacks the natural flavor of lychee and has a strong cooked / unpleasant odor. Fresh fruit flavor It has a prominent freshness, with floral and fruity aromas and honey sweetness of fresh lychee, and a refreshing aftertaste. It has a slight fruity flavor, but lacks freshness, and the aftertaste is bland. Completely lacking in fresh fruit flavor, the taste is dull. Fragrance There is no jarring artificial flavoring; the taste is natural and harmonious. It has a slight artificial flavor, but it doesn't affect the overall taste. The artificial flavoring is too strong, the aroma is pungent, and the aftertaste is bitter. Fullness of flavor The sweet and sour balance is well-proportioned, resulting in a rich and full-bodied flavor without any thinness. The sweet and sour ratio is generally balanced, but the texture is somewhat thin. The sweet and sour ratio is unbalanced, the texture is extremely thin, and it is very watery. Bubble state The bubbles are fine and dense, with good persistence, and a mild taste. The bubbles are relatively large, the persistence is average, and the burnt taste is rather strong. Large, easily dissipated bubbles, resulting in a pungent, irritating taste. Table 2 Sensory Evaluation Results

[0034] Results analysis: As shown in Table 2, the lychee sodas prepared in Examples 1-3 of this invention all achieved a comprehensive sensory score of over 86 points, which is much higher than the comprehensive scores of Comparative Examples 1-7. Among them, Example 2 achieved the highest comprehensive score of 88.2 points, which is 57.8% higher than the 55.9 points of the commercially available blended Comparative Example 7. This indicates that the technical solution of this invention can significantly improve the comprehensive sensory quality of lychee sodas and achieve the effect of enhancing the flavor of fresh lychee fruit in sodas.

[0035] The results of Comparative Examples 1-3 show that the ternary complex enzymatic hydrolysis system of pectinase, xylanase and β-glucosidase used in this invention has an irreplaceable synergistic effect. None of them can be omitted. Only by combining the three in the proportions specified in this invention can the optimal effects of juice yield, clarity and aroma release be achieved simultaneously.

[0036] The results of Comparative Examples 4-6 show that the combined fermentation system of Anomalous Wickham yeast and Anomalous yeast used in this invention has a significant synergistic effect. Moreover, within the range of live bacteria count ratio and inoculation amount specified in this invention, a perfect match between fermentation flavor and lychee flavor can be achieved, maximizing the flavor fullness and fresh fruit feel of the product.

[0037] Comparative Example 7 is a commercially available lychee soda with conventional flavorings. Its overall score is only 55.9 points. The scores for lychee flavor, fresh fruit taste, artificial flavor, and fullness of taste are all less than 12 points, which is far lower than the embodiment of the present invention. Only the score for the effervescence is slightly higher. The reason is that it only uses a large amount of artificial flavorings to adjust the flavor, without the flavor support of lychee juice and fermentation base liquid. It has serious problems of excessive artificial flavor, abrupt flavor, and thin taste. It is far from the natural fresh fruit flavor of the product of the present invention, which verifies the excellent effect of the technical solution of the present invention.

[0038] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A preparation process for a soft drink that retains the flavor of fresh lychee fruit, characterized in that, Includes the following steps: S1. Fresh lychees are pre-treated and pulped to obtain lychee pulp. The lychee pulp is then subjected to compound enzymatic hydrolysis. After enzymatic hydrolysis, the supernatant is collected by centrifugation and filtration to obtain clear lychee juice. S2. The clarified lychee juice obtained in S1 is inoculated into the compound yeast liquid for fermentation. After the fermentation is terminated, it is sterilized to obtain the lychee fermentation base liquid. S3. Mix the clarified lychee juice from S1, the fermented lychee base liquid from S2, sweetener, acidity regulator, compound lychee characteristic flavoring, and drinking water, and stir evenly after adjusting the volume to obtain the blended base liquid. S4. The base liquid is homogenized and sterilized at low temperature, then vacuum degassed. The degassed base liquid is then carbonated and immediately bottled to obtain the soda that retains the flavor of fresh lychee fruit.

2. The preparation process according to claim 1, characterized in that, In step S1, the process parameters for the compound enzymatic hydrolysis are as follows: the compound enzyme is composed of pectinase, xylanase, and β-glucosidase in a mass ratio of (2-4):(1-3):1; the enzymatic hydrolysis temperature is controlled at 4℃-12℃; the amount of compound enzyme added is 0.2%-0.8% of the total mass of litchi pulp; and the enzymatic hydrolysis time is 8h-24h.

3. The preparation process according to claim 1, characterized in that, In step S1, the pretreatment includes peeling, washing, removing pits, and crushing; the centrifugation speed is 4000-6000 r / min, the centrifugation time is 10-20 min, and the centrifugation temperature is 4℃-10℃; the filtration uses a 200-400 mesh filter bag for negative pressure filtration.

4. The preparation process according to claim 1, characterized in that, In step S2, the compound yeast liquid is composed of abnormal Wickham yeast liquid and strange yeast liquid; The viable count of *Wickham's abnormal yeast* in the compound yeast solution was (5-8) × 10⁻⁶. 8 CFU / mL, viable count of *Saccharomyces cerevisiae* was (1–3) × 10⁻⁶. 8 The inoculation amount of the compound yeast liquid is 5-7 v / v, the fermentation temperature is controlled at 20℃-26℃, and the fermentation time is 24h-36h.

5. The preparation process according to claim 1, characterized in that, In step S3, the percentages of each raw material by the total mass of the base liquid are as follows: 20%–40% lychee clarified juice, 5%–15% lychee fermentation base liquid, 4%–10% sweetener, 0.1%–0.3% acidity regulator, 0.001%–0.005% compound lychee characteristic flavoring, and the remainder is drinking water.

6. The preparation process according to claim 5, characterized in that, The sweetener is one or more combinations of white sugar, erythritol, and fructose syrup. The acidity regulator is one or more of citric acid, malic acid, and sodium citrate; The compound lychee characteristic flavoring is composed of cis-rose ether, linalool, geraniol, citral, and hexanal in a mass ratio of (4-6):(2-4):(1-3):1:

1.

7. The preparation process according to claim 1, characterized in that, In step S4, the homogenization temperature is 4℃~10℃, the homogenization pressure is 20~30MPa, and the homogenization process is performed twice. The low-temperature sterilization process is HPP sterilization, with sterilization parameters of 400 MPa and sterilization time of 2–5 min.

8. The preparation process according to claim 1, characterized in that, In step S4, the temperature of vacuum degassing is 4℃~10℃, the vacuum degree is -0.06MPa~-0.08MPa, and the degassing time is 5~10min.

9. The preparation process according to claim 1, characterized in that, In step S5, the carbonation temperature is 2℃~6℃, the system pressure is 0.4~0.6MPa, and the carbon dioxide dissolution and pressure holding time is 15~30min.

10. A soft drink that retains the flavor of fresh lychee fruit, characterized in that, The soda is prepared using the preparation process described in any one of claims 1 to 9.

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