A low-alcohol coconut water beverage and a method for preparing the same

Abstract

The application provides a low-alcohol coconut water beverage and a preparation method thereof, and relates to the field of fermented drinks. The preparation method of the low-alcohol coconut water beverage comprises the following steps: taking coconut water, adjusting sugar and acid, sterilizing, inoculating Saccharomyces cerevisiae 1-7-1 and Lactobacillus plantarum A33 to carry out mixed fermentation, centrifuging to obtain supernatant, and obtaining the low-alcohol coconut water beverage. Saccharomyces cerevisiae 1-7-1 and Lactobacillus plantarum A33 are used for mixed fermentation, metabolites which are not easy to obtain through single fermentation are generated while the growth of the strains is promoted, the bad flavor of Lactobacillus plantarum single strain and Saccharomyces cerevisiae single strain fermentation is improved, the fermented drink is endowed with unique taste and flavor and the typicality of coconut aroma is increased, meanwhile, the mixed fermentation also significantly improves the antioxidant activity, and the functionality and nutritional value of the low-alcohol coconut water beverage are improved. The application provides a new method for recycling and improving the added value of old coconut water resources.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fermented drinks, in particular to a low-alcohol coconut water beverage and a preparation method thereof. BACKGROUND

[0002] Cocos nucifera L, commonly known as coconut, is one of the typical tropical energy crop resources in Hainan Province. The main nutritional components in coconut water are soluble sugar, vitamins, minerals, and a small amount of protein and oil. The carbohydrate content of fresh coconut water can reach more than 5%, including glucose, sucrose, fructose, and a small amount of galactose, xylose, and mannose. Coconut water is also rich in essential amino acids needed by the human body, which can maintain normal physiological activities and is beneficial to the growth and development of the human body. Compared with milk, the content of arginine, alanine, etc. in coconut water is more abundant.

[0003] Due to the rich nutrients in coconut water, the chemical composition and taste and flavor of stored natural coconut water can change easily, and it is difficult to transport for a long time. In the food industry, fresh green coconut water can be directly drunk or sterilized to make beverages due to its sweet taste. It can also be used as a fermentation substrate to ferment into fruit wine or fruit vinegar by yeast or acetic acid bacteria. However, the brix of old coconut water is low, and the flavor is light, so the taste is not good when directly drunk. In the prior art, coconut fibers are produced from old coconut water. Coconut fibers are a kind of food with smooth taste made from bacterial cellulose after processing and screening. They can be cut into small pieces and soaked in syrup, and later they are loved by consumers as a dessert.

[0004] With the development of economy and the continuous improvement of people's living standards, the demand for healthy and high-quality beverages has also increased to a certain extent. Fruit wine is an alcoholic beverage made from fruits as raw materials, which retains the nutrients and flavors of fruits and has a variety of good tastes. However, the alcohol content of fruit wine is relatively high, which is not suitable for some people to drink. Low-alcohol beverages can retain all the advantages of fruit wine and have a lower alcohol content, which is more beneficial to health.

[0005] The non-patent document "Kinetics of Yeast DV10 Fermentation of Low-alcohol Coconut Water" discloses a preparation process of low-alcohol coconut water. Yeast DV10 is used to ferment mature coconut water, and the change rules of variables such as cell concentration, substrate concentration, and product concentration with fermentation time are studied. Although the fermented coconut water prepared by this process meets the requirements of low-alcohol, it pays more attention to the kinetics of the fermentation process, and does not pay attention to the improvement of the flavor, sensory, and functionality of the fermented coconut water. The fermented low-alcohol coconut water has certain differences from the typical flavor of coconut water itself through experiments.

[0006] How to prepare a low-alcohol coconut water beverage with better flavor, better sensory and functionality by using old coconut water as raw material, promote the recycling of old coconut water resources and improve its added value, become the technical problem to be solved by the technical personnel in the art. SUMMARY

[0007] Therefore, the technical problem to be solved by the present application is to overcome the defects that the old coconut water directly drunk has bad taste and the sensory of the low-alcohol coconut water prepared by fermentation needs to be improved, so as to provide a low-alcohol coconut water beverage and a preparation method thereof.

[0008] To achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0009] In a first aspect, the present application provides a preparation method of a low-alcohol coconut water beverage, comprising the following steps:

[0010] Take coconut water, adjust sugar and acid, sterilize, inoculate Saccharomyces cerevisiae 1-7-1 and Lactobacillus plantarum A33 for mixed fermentation, centrifuge to obtain supernatant, and obtain the low-alcohol coconut water beverage.

[0011] Further, the inoculation amount of Saccharomyces cerevisiae 1-7-1 is 5x10 6 ~ 6x10 6 cfu / mL, and the inoculation amount of Lactobacillus plantarum A33 is 5x10 6 ~ 6x10 6 cfu / mL, based on the volume of the coconut water.

[0012] The mixed fermentation conditions are as follows: temperature 21~27℃, for example, 21℃, 24℃, 27℃, time 24~36h, for example, 24h, 36h.

[0013] Further, the inoculation amount of Saccharomyces cerevisiae 1-7-1 is 5x10 6 cfu / mL, and the inoculation amount of Lactobacillus plantarum A33 is 5x10 6 cfu / mL, based on the volume of the coconut water.

[0014] The mixed fermentation conditions are as follows: temperature 21℃, time 36h.

[0015] Further, the inoculation amount of Saccharomyces cerevisiae 1-7-1 is 5x10 6 cfu / mL, and the inoculation amount of Lactobacillus plantarum A33 is 5x10 6 cfu / mL, based on the volume of the coconut water.

[0016] Further, the inoculation amount of the seed solution of Saccharomyces cerevisiae 1-7-1 is 2%, and the inoculation amount of the seed solution of Lactobacillus plantarum A33 is 2%.

[0017] Further, the preparation method of the seed solution of Saccharomyces cerevisiae 1-7-1 comprises: taking the glycerol tube preserved Saccharomyces cerevisiae 1-7-1 and inoculating in YEPD liquid medium at an inoculation amount of 2%-5%, culturing for 18-24h per generation, subculturing for 2-3 times, centrifuging at 8000-10000r / min for 8-10min, washing with distilled water for 2-3 times, taking the bacterial slurry and suspending in the same volume of coconut water after sugar and acid adjustment for standby;

[0018] The preparation method of the seed solution of Lactobacillus plantarum A33 comprises: taking the glycerol tube preserved Lactobacillus plantarum A33 and inoculating in YEPD liquid medium at an inoculation amount of 2%-5%, culturing for 22-26h per generation, subculturing for 2-3 times, centrifuging at 8000-10000r / min for 8-10min, washing with distilled water for 2-3 times, taking the bacterial slurry and suspending in the same volume of coconut water after sugar and acid adjustment for standby.

[0019] Further, the preparation method of the seed solution of Saccharomyces cerevisiae 1-7-1 comprises: taking the glycerol tube preserved Saccharomyces cerevisiae 1-7-1 and inoculating in YEPD liquid medium at an inoculation amount of 5%, culturing for 18h per generation, subculturing for 3 times, centrifuging at 8000r / min for 10min, washing with distilled water for 3 times, taking the bacterial slurry and suspending in the same volume of coconut water after sugar and acid adjustment for standby;

[0020] The preparation method of the seed solution of Lactobacillus plantarum A33 comprises: taking the glycerol tube preserved Lactobacillus plantarum A33 and inoculating in YEPD liquid medium at an inoculation amount of 2%-5%, culturing for 22-26h per generation, subculturing for 2-3 times, centrifuging at 8000-10000r / min for 8-10min, washing with distilled water for 2-3 times, taking the bacterial slurry and suspending in the same volume of coconut water after sugar and acid adjustment for standby.

[0021] Further, the coconut water is obtained by breaking the shell of old coconut and taking water;

[0022] The coconut water is filtered before the step of sugar and acid adjustment;

[0023] In the step of sugar and acid adjustment, the sugar degree of the coconut water is adjusted to 13-15°Brix, and the pH value is adjusted to 3.4-3.6;

[0024] Sterilization condition: sterilization at 65-75℃ for 30min;

[0025] Centrifugation condition: speed 8000-10000rpm, temperature 3-5℃, time 5-8min.

[0026] Further, in the step of sugar and acid adjustment, the sugar degree of the coconut water is adjusted to 14°Brix, and the pH value is adjusted to 3.5;

[0027] Sterilization condition: sterilization at 65℃ for 30min;

[0028] Centrifugation condition: 10000rpm, 4℃, 5min.

[0029] In a second aspect, the present application provides a low-alcohol coconut water beverage prepared by the above method.

[0030] The use of lactic acid bacteria alone for fermentation can result in poor flavor and insufficient typicality of coconut aroma. In addition, the growth and reproduction of lactic acid bacteria also face some challenges in the preparation process of coconut water. Saccharomyces cerevisiae has a faster fermentation speed, and can produce various flavor substances such as esters and phenols during fermentation, which can impart rich aroma and taste to the beverage. However, the beverage fermented by Saccharomyces cerevisiae has a strong flavor, which is different from the typical flavor of coconut water, and usually has a high alcohol content, which is not suitable for the preparation of low-alcohol coconut water beverage.

[0031] The technical scheme of the present application has the following advantages:

[0032] The low-alcohol coconut water beverage provided by the present application is prepared by mixed fermentation of Saccharomyces cerevisiae 1-7-1 and Lactobacillus plantarum A33. The inventors found through research that the use of Saccharomyces cerevisiae 1-7-1 and Lactobacillus plantarum A33 for mixed fermentation can produce metabolites that are not easily obtained by single-strain fermentation while promoting the growth of each strain, and can also inhibit the production of undesirable flavor substances during single-strain fermentation, thereby improving the undesirable flavor caused by single-strain fermentation of Lactobacillus plantarum and Saccharomyces cerevisiae, imparting a unique taste and flavor to the fermented beverage and increasing the typicality of coconut aroma. In addition, mixed fermentation can also significantly improve the antioxidant activity, thereby improving the functionality and nutritional value of the low-alcohol coconut water beverage. The present application provides a new method for recycling and increasing the added value of old coconut water resources.

[0033] The inventors found during research that although both use a combination of yeast and lactic acid bacteria, the sensory differences of the coconut water beverages prepared by fermentation are large, and the antioxidant activities are also significantly different. However, when specific strains (Saccharomyces cerevisiae 1-7-1 and Lactobacillus plantarum A33) are used for mixed fermentation, it is unexpectedly found that the obtained product has outstanding sensory quality and antioxidant activity, unique flavor, good typicality, and meets the requirements of low-alcohol beverages, has obvious advantages, and is suitable for large-scale promotion as a low-alcohol coconut water beverage product with excellent sensory quality and strong functionality. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the specific embodiments of the present application or the prior art, the drawings required to be used in the specific embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0035] Figure 1 is a process route map for preparing a low-alcohol coconut water beverage according to Embodiment 1 of the present application;

[0036] Figure 2 is a sensory evaluation result map of coconut water beverages prepared by mixed fermentation of different strains in Experimental Example 1 of the present application, wherein different letters represent significant differences (p<0.05) between different samples;

[0037] Figure 3 is an antioxidant activity value result map of coconut water beverages prepared by mixed fermentation of different strains in Experimental Example 2 of the present application, wherein different letters represent significant differences (p<0.05) between different samples;

[0038] Figure 4 is a graph showing the effect of different inoculation amounts on the sensory score of low-alcohol coconut water beverages in Experimental Example 3 of the present application;

[0039] Figure 5 is a graph showing the effect of different sugar degrees on the sensory score of low-alcohol coconut water beverages in Experimental Example 3 of the present application;

[0040] Figure 6 is a graph showing the effect of different pH values on the sensory score of low-alcohol coconut water beverages in Experimental Example 3 of the present application;

[0041] Figure 7 is a graph showing the effect of different fermentation times on the sensory score of low-alcohol coconut water beverages in Experimental Example 3 of the present application;

[0042] Figure 8 is a graph showing the effect of different temperatures on the sensory score of low-alcohol coconut water beverages in Experimental Example 3 of the present application;

[0043] Figure 9 is a graph showing the changes in pH and total acid of the fermentation liquor at different times in Experimental Example 4 of the present application, wherein 9a is a graph showing the changes in pH, and 9b is a graph showing the changes in total acid;

[0044] Figure 10 is a graph showing the changes in reducing sugar and sugar degree of the fermentation liquor at different times in Experimental Example 4 of the present application, wherein 10a is a graph showing the changes in reducing sugar, and 10b is a graph showing the changes in sugar degree;

[0045] Figure 11 is a graph showing the changes in alcohol content of the fermentation liquor at different times in Experimental Example 4 of the present application. DETAILED DESCRIPTION

[0046] The following examples are provided to better enable those skilled in the art to further understand and practice the application, and are not intended to limit the scope of the application. Any product derived from the application or any product derived from the application in combination with other prior art features that are the same as or similar to the application fall within the scope of the application.

[0047] 1. Strain information

[0048] The strain information involved in the embodiments and experimental examples of the application is shown in Table 1.

[0049] Table 1 Strain information

[0050] Chinese name of strain Latin name of strain Strain number Source of strain Saccharomyces cerevisiae Laboratory preservation 151 Saccharomyces cerevisiae Laboratory preservation Saccharomyces cerevisiae 74-1 Laboratory preservation Saccharomyces cerevisiae Laboratory preservation 71-2 Saccharomyces cerevisiae Laboratory preservation Saccharomyces cerevisiae 1-7-1 Laboratory preservation Saccharomyces cerevisiae Purchased from LAMAN company 21-1 Saccharomyces cerevisiae EC118 Purchased from LAMAN company D254 Saccharomyces cerevisiae DV10 Purchased from LAMAN company Lactolacillus plantarum Laboratory preservation Name Specification Production unit Citric acid Standard product Shanghai Yuan Ye Biological Company A33 Methanol

[0051] The strains involved in Table 1 and preserved in the laboratory are preserved in the Food Biotechnology Laboratory of Hainan University.

[0052] Saccharomyces cerevisiae 151, 74-1, 71-2, 1-7-1, 21-1, the above strains have been disclosed in the master's thesis "Metabolite screening and identification of pure inoculation of pre-fermented coconut water to promote bacterial cellulose synthesis" (Fu Meijuan, 2020) of Hainan University, and the above strains are screened from different batches of naturally fermented coconut water.

[0053] Lactobacillus plantarum A33 has been disclosed in the journal article "Effect of fructooligosaccharides on Lactobacillus plantarum A33 fermented tamarind juice" (Wu Lingfeng et al., Food Science, 2021.), and the strain is screened from natural fermentation broth of Morinda citrifolia.

[0054] 2. Main reagents

[0055] The main reagent information involved in the embodiments and experimental examples of the application is shown in Table 2.

[0056] Table 2 Main reagent information

[0057] Analytically pure Xilong Scientific Co., Ltd. Ferrous sulfate Analytically pure Xilong Scientific Co., Ltd. Hydrogen peroxide Analytically pure Xilong Scientific Co., Ltd. Salicylic acid Analytically pure Xilong Scientific Co., Ltd. Potassium persulfate Analytically pure Xilong Scientific Co., Ltd. Sodium acetate Analytically pure Xilong Scientific Co., Ltd. Ferric chloride Analytically pure Xilong Scientific Co., Ltd. Ethanol Analytically pure Xilong Scientific Co., Ltd. Glucose Analytically pure Xilong Scientific Co., Ltd. Tryptone Analytically pure Huan Kai Microorganism Agar Analytically pure Huan Kai Microorganism Yeast extract powder Analytically pure Huan Kai Microorganism MRS broth dry powder medium Analytically pure Huan Kai Microorganism Figure 1 Figure 2 Figure 2 Figure 3 Figure 4 Figure 4 Figure 5

[0058] 3. Preparation of culture medium

[0059] YEPD liquid medium: glucose 2%, peptone 2%, yeast extract powder 1%, sterilized at 121℃ for 15 min.

[0060] MRS liquid medium: MRS broth powder medium 5.4%, sterilized at 121℃ for 15 min.

[0061] 4. Preparation of seed liquid

[0062] Saccharomyces cerevisiae 1-7-1 seed liquid: Saccharomyces cerevisiae 1-7-1 preserved in a glycerol tube in a-80℃ refrigerator was inoculated into YEPD liquid medium at a 5% inoculation amount, cultured for 18h per generation, subcultured for 3 times, centrifuged at 8000r / min for 10min, washed with distilled water for 3 times, and the bacterial slurry was suspended with an equal volume of the sugar and acid adjusted coconut water for standby;

[0063] Lactobacillus plantarum A33 seed liquid: Lactobacillus plantarum A33 preserved in a glycerol tube in a-80℃ refrigerator was inoculated into MRS liquid medium at a 5% inoculation amount, cultured for 24h per generation, subcultured for 3 times, centrifuged at 8000r / min for 10min, washed with distilled water for 3 times, and the bacterial slurry was suspended with an equal volume of the sugar and acid adjusted coconut water for standby.

[0064] 5. Data processing and analysis

[0065] The data results in the experimental examples are expressed as mean ± standard deviation, and the statistical analysis is performed using IBM SPSS Statistics 26, and the graphs are drawn using Origin 2023 and Graphpad Prism 9.

[0066] If the specific experimental steps or conditions are not specified in the examples, the operations or conditions can be performed according to the conventional experimental steps described in the literature in the art. The raw materials or instruments used are conventional products that can be obtained by purchase, including but not limited to the raw materials or instruments used in the examples of the present application.

[0067] Example 1

[0068] The present example provides a preparation method of a low-alcohol coconut water beverage, and the process route is as shown in Figure 5 The specific steps are as follows:

[0069] (1) Raw material selection: mature old coconuts were selected, the shells were broken, and the coconut water was taken for standby;

[0070] (2) Filtration: the removed coconut water was filtered with gauze;

[0071] (3) Sugar and acid adjustment: the initial sugar content of the coconut water was adjusted to 14°Brix with sucrose, and the initial pH value of the coconut water was adjusted to 3.5 with citric acid;

[0072] (4) Filling: the sugar and acid adjusted coconut water was filled into sterile glass jars;

[0073] (5) Sterilization: the filled coconut water was sterilized at 65℃ for 30min;

[0074] (6) Inoculation: inoculate Saccharomyces cerevisiae 1-7-1 seed liquid and Lactobacillus plantarum A33 seed liquid into sterilized coconut water for mixed fermentation, wherein the inoculation amount of Saccharomyces cerevisiae 1-7-1 seed liquid is 2% (5 x 10 6 cfu / mL of inoculation amount based on the mass of coconut water raw material), and the inoculation amount of Lactobacillus plantarum A33 seed liquid is 2% (5 x 10 6 cfu / mL of inoculation amount based on the mass of coconut water raw material);

[0075] (7) Fermentation: ferment the inoculated coconut water at 21°C for 36h;

[0076] (8) Centrifugation: centrifuge the fermented coconut water at 10000 rpm and 4°C for 5min;

[0077] (9) Canning: can the supernatant after centrifugation to obtain the finished low-alcohol coconut water beverage.

[0078] Experimental Example 1 Sensory evaluation of coconut water beverage prepared by mixed fermentation of different strains

[0079] Different Saccharomyces cerevisiae (151, 74-1, 71-2, 1-7-1, 21-1, D254, EC118, DV10) and Lactobacillus plantarum A33 were mixed to prepare coconut water beverage samples, and Saccharomyces cerevisiae 151, 74-1, 71-2, 1-7-1, 21-1, D254, EC118, DV10 and Lactobacillus plantarum A33 were fermented alone to prepare coconut water beverage samples (inoculation amount 2% when fermented alone), and the preparation method was referred to Example 1.

[0080] According to GBT-2006 General Analysis Method for Grape Wine and Fruit Wine, 15 adults of different ages and genders who had undergone sensory evaluation training were selected, and the coconut water beverage was evaluated according to the sensory evaluation criteria provided in Table 3, and the sensory evaluation results are shown in Table 4. Figure 6

[0081] Table 3 Sensory evaluation criteria

[0082]

[0083] As shown in Table 4, there are significant differences in the sensory evaluation of coconut water beverages fermented by different Saccharomyces cerevisiae alone and mixed with Lactobacillus plantarum. Among them, Saccharomyces cerevisiae 1-7-1 and Lactobacillus plantarum A33 mixed fermentation has the highest sensory score (up to 98 points), which has outstanding effect. Figure 6 ​​

[0084] Antioxidant activity of coconut water beverage prepared by mixed fermentation of different strains

[0085] Coconut water beverage samples were prepared by mixed fermentation of different Saccharomyces cerevisiae strains (1-7-1, 71-2, DV10) and Lactobacillus plantarum A33, and by single fermentation of Saccharomyces cerevisiae strains 1-7-1, 71-2, DV10 and Lactobacillus plantarum A33 (inoculum 2%), respectively. The preparation method was according to Example 1.

[0086] (1) DPPH radical scavenging capacity determination

[0087] Take 50 μL of sample diluent and different concentrations of Trolox (0, 20, 40, 60, 80, 100 μg / mL) and mix with 400 μL of 100 μmol / L DPPH-methanol solution. Let stand at room temperature for 30 minutes in the dark, and measure the absorbance at 517 nm. The result is recorded as A1. In the same system, replace DPPH-methanol solution with ethanol, and record as A2. In the same system, replace the sample with distilled water, and record as A3. Different concentrations of Trolox are used as positive controls and a standard curve is drawn. Each sample is repeated three times, and the average value is taken. The DPPH radical scavenging rate is calculated according to the following formula: DPPH radical scavenging rate = [1-(A1-A2) / A3] x 100%. The final DPPH radical scavenging rate result is expressed in μmol / mL Trolox equivalent.

[0088] (2) ABTS radical scavenging capacity determination

[0089] ABTS + Solution preparation method: mix 7 mmol / L ABTS solution and 2.45 mmol / L potassium persulfate solution at a volume ratio of 1:1, and obtain ABTS + solution by reacting at room temperature for 16 hours in the dark. Dilute the freshly prepared ABTS + solution with distilled water until the absorbance at 734 nm is 0.70 ± 0.02. Take 50 μL of sample diluent and different concentrations of Trolox (0, 20, 40, 60, 80, 100 μg / mL) and mix with 400 μL of freshly diluted ABTS + solution (absorbance at 734 nm is 0.70 ± 0.02). Let stand at room temperature for 30 minutes in the dark, and measure the absorbance at 734 nm, which is recorded as A1. A0 is the absorbance of ABTS +The absorbance value. Different concentrations of Trolox were used as positive control and standard curve was plotted. ABTS radical scavenging rate was calculated according to the following formula: ABTS radical scavenging rate = [(A1-A0) / A0]x100%. The final ABTS radical scavenging rate result was expressed as μmol / mL Trolox equivalent.

[0090] (3) Hydroxyl radical scavenging capacity determination

[0091] 100 μL sample dilution and different concentrations of Trolox (0, 20, 40, 60, 80, 100 μg / mL) were mixed with 100 μL 6 mmol / L FeSO4 solution and 100 μL 2.4 mmol / L H2O2. After 10 min incubation at room temperature, the mixture was incubated with 100 μL 6 mmol / L salicylic acid solution at 30°C for 30 min, and the absorbance value was measured at 510 nm and recorded as A1. Distilled water was used to replace H2O2 in the above process, and the absorbance value was measured at 510 nm and recorded as A2. Distilled water was used to replace sample solution in the above process, and the absorbance value was measured at 510 nm and recorded as A3. Different concentrations of Trolox were used as positive control and standard curve was plotted. Hydroxyl radical scavenging rate was calculated according to the following formula: Hydroxyl radical scavenging rate = [1-(A1-A2) / A3]x100%. The final hydroxyl radical scavenging rate result was expressed as μmol / mL Trolox equivalent.

[0092] (4) Ferric ion reducing ability determination

[0093] A 300 mmol / L sodium acetate solution, a 10 mmol / L TPTZ solution and a 20 mmol / L FeCl3 solution were prepared, and the three solutions were mixed in a volume ratio of 10:1:1 to prepare FRAP reagent, which was preheated in a 37°C water bath. 30 μL sample and Trolox (0, 20, 40, 60, 80, 100 μg / mL) were mixed with 900 μL FRAP reagent. After 30 min incubation at room temperature in the dark, the absorbance was read at 593 nm. FeSO4 standard curve was plotted: 20 mmol / L FeCL3 was replaced by different concentrations of FeSO4 (0, 200, 400, 600, 800, 1000 μmol / L), and the absorbance at 593 nm was measured after preparation according to the preparation method of FRAP reagent 10:1:1, and the standard curve was plotted. The FRAP value was expressed as μmol / mL FeSO4 equivalent.

[0094] Results analysis:

[0095] The results of antioxidant activity determination are shown in Table 1. Figure 7

[0096] ​The DPPH radical scavenging ability of the samples fermented with mixed bacteria of Lactobacillus plantarum and Saccharomyces cerevisiae was higher than that of the samples fermented with Saccharomyces cerevisiae alone, indicating that the addition of Lactobacillus plantarum to mixed fermentation with Saccharomyces cerevisiae would greatly enhance the DPPH radical scavenging ability. Among them, 1-7-1+A33 had the strongest scavenging ability, reaching 33.2 μmol TE / mL.

[0097] The ABTS free radical scavenging ability of the samples fermented with mixed bacteria of Lactobacillus plantarum and Saccharomyces cerevisiae was higher than that of the samples fermented with Saccharomyces cerevisiae alone, indicating that the ABTS free radical scavenging ability can be improved by adding Lactobacillus plantarum to the mixed fermentation of Saccharomyces cerevisiae. The ABTS free radical scavenging ability of the mixed fermentation of 1-7-1+A33 was higher, reaching 47.9 μmol TE / mL.

[0098] The hydroxyl radical scavenging ability of the samples fermented with mixed bacteria of Lactobacillus plantarum and Saccharomyces cerevisiae was higher than that of the samples fermented with Saccharomyces cerevisiae alone, indicating that the hydroxyl radical scavenging ability can be improved by adding Lactobacillus plantarum to the mixed fermentation of Saccharomyces cerevisiae. Among them, 1-7-1+A33 had the strongest scavenging ability, reaching 60.4 μmol TE / mL.

[0099] The iron ion reducing capacity of the samples fermented with a mixture of Lactobacillus plantarum and Saccharomyces cerevisiae was higher than that of the samples fermented with Saccharomyces cerevisiae alone, indicating that the iron ion reducing capacity can be improved by adding Lactobacillus plantarum to the mixed fermentation with Saccharomyces cerevisiae. Among them, the coconut water fermented with the mixed bacteria 1-7-1+A33 had the strongest iron ion reducing capacity, which was 59.7 μmol TE / mL.

[0100] Research has shown that mixed fermentation with Lactobacillus plantarum and Saccharomyces cerevisiae can effectively enhance antioxidant activity. Combining four antioxidant indicators—DPPH free radical scavenging capacity, ABTS free radical scavenging capacity, hydroxyl free radical scavenging capacity, and iron ion reducing capacity—the 1-7-1+A33 mixed fermentation group achieved the best results in all antioxidant indicators, demonstrating the outstanding antioxidant activity of this low-alcohol coconut water beverage.

[0101] Experimental Example 3 Optimization of low-alcohol coconut water beverage fermentation process

[0102] 1. Single-factor experiment

[0103] 1. Effect of different inoculum amounts on sensory scores of low-alcohol coconut water beverages

[0104] The inoculum amount was changed based on the process route provided in Example 1, and sensory evaluation was performed to obtain sensory scores. The results are as follows Figure 7 shown.

[0105] Depend on Figure 8It can be seen that adding different inoculum amounts of Lactobacillus plantarum A33 and Saccharomyces cerevisiae 1-7-1 bacterial cultures significantly affects sensory scores. The sensory scores of low-alcohol coconut water beverages show a trend of first increasing and then decreasing with different inoculum amounts. The 3% inoculum reaches the peak of the sensory scores, and larger or smaller inoculum amounts have a negative impact on the sensory scores. A smaller inoculum amount, due to the low bacterial content, results in incomplete fermentation and does not significantly improve the flavor. A larger inoculum amount ferments faster, consumes more nutrients, and also negatively affects the flavor. Therefore, the optimal inoculum amount is 3%, and two adjacent conditions, 2% and 4%, were selected for response surface optimization.

[0106] 2. Effect of different sugar contents on sensory scores of low-alcohol coconut water beverages

[0107] The initial sugar content was changed based on the process provided in Example 1, and sensory evaluation was performed to obtain sensory scores. The results are as follows: Figure 8 shown.

[0108] Depend on Test number As can be seen, different sugar concentrations significantly influence the response surface sensory scores. The sensory score of the low-alcohol coconut water beverage increases with increasing sugar concentration, reaching its highest score at a sugar concentration of 14°Brix. Coconut water with higher sugar concentrations provides more nutrients for the bacteria to utilize, resulting in a greater flavor profile during fermentation. However, if the sugar concentration is increased above 15°Brix, the osmotic pressure in the wine becomes too high, affecting the activity of the brewer's yeast and, consequently, the fermentation process. Therefore, the optimal sugar concentration of 14°Brix was selected, along with two adjacent conditions, 11°Brix and 12.5°Brix, for response surface optimization.

[0109] 3. Effect of different pH values ​​on sensory scores of low-alcohol coconut water beverages

[0110] The initial pH was changed based on the process provided in Example 1, and sensory evaluation was performed to obtain sensory scores. The results are as follows: Initial sugar content (°Brix) shown.

[0111] Depend on Initial inoculum size (%) It can be seen that the initial pH affects the sensory score of the coconut water low-alcohol beverage. The sensory score reaches its highest at pH 3.5, and there is a downward trend at higher or lower pH levels. A weakly acidic environment plays a positive role in the growth of yeast, while an environment with too high or too low pH is not conducive to the formation of flavor substances. Therefore, the optimal condition is pH 3.5.

[0112] 4. Effects of different fermentation times on sensory scores of low-alcohol coconut water beverages

[0113] The fermentation time was changed based on the process provided in Example 1, and sensory evaluation was performed to obtain sensory scores. The results are as follows: Fermentation time (h) shown.

[0114] As can be seen from Sensory score the fermentation time, the sensory score of low-alcohol coconut water beverage first increased and then decreased. Due to the fermentation of the strain to produce flavor substances, the increase was more obvious from 12h to 24h, and the peak value was at 24h, and then it decreased. It is possible that in the later fermentation, the nutrients in the wine body were consumed, and more metabolic products accumulated, which had a negative impact on the flavor. Therefore, the optimal fermentation time is 24h, and the adjacent two conditions of 12h and 36h are selected for response surface optimization.

[0115] 5. Effect of different temperatures on the sensory score of low-alcohol coconut water beverage

[0116] Based on the process route provided in Example 1, the fermentation temperature was changed, and the sensory evaluation was carried out to obtain the sensory score, and the results are shown in Figure 9 .

[0117] As can be seen from Figure 9 , different temperatures have a certain effect on the sensory score of low-alcohol coconut water beverage. The sensory score first decreases and then increases, and the highest sensory score is obtained at 21℃. The effect of sensory score is not very obvious from 18℃ to 27℃, and the score is the lowest at 30℃. It is because the temperature is too high, the strain activity is too strong, and the fermentation is too fast, resulting in the accumulation of metabolites and poor sensory. Therefore, the optimal condition is 21℃.

[0118] II. Response surface optimization of fermentation process

[0119] Taking the sensory score of low-alcohol coconut water beverage as the response value, the optimal conditions of pH 3.5 and optimal fermentation temperature 21℃ are selected. Based on the process route provided in Example 1, the initial sugar content, initial inoculum size and fermentation time are tested, and the Box-Behnken response surface design in design expert software is used. A total of 17 test groups are designed for three-factor and three-level low-alcohol coconut water beverage fermentation process, and the test results are shown in Table 4.

[0120] Table 4 Response surface test design and results

[0121] Figure 9 Figure 10 Figure 10 Figure 10 Figure 10 1 12.5 3 24 74 2 12.5 3 24 78 3 12.5 2 12 72 4 14 3 36 86 5 12.5 3 24 80 6 12.5 3 24 76 7 11 3 12 70 8 14 4 24 82 9 11 2 24 58 10 12.5 2 36 60 11 12.5 3 24 82 12 12.5 4 36 70 13 11 4 24 78 14 14 2 24 90 15 12.5 4 12 90 16 11 3 36 64 17 14 3 12 78

[0122] The test data is fitted by quadratic polynomial regression analysis, and the multiple quadratic regression equation obtained according to the coded factors is:

[0123] R1 = 75.78 + 8.25A + 7.00B - 8.00C - 7.00AB + 3.50AC - 2.00BC - 0.028A 2

[0124] - 4.00A 2 B + 8.50A2 C. The variance analysis of the equation is shown in Table 5.

[0125] Table 5 Variance analysis of response surface regression model results

[0126]

[0127] **P<0.01, extremely significant; *P<0.05, significant.

[0128] As shown in Table 5, the P value of the model is 0.0043, which is extremely significant, the lack of fit is 0.2066>0.05, which is not significant, and R 2 and R 2 Adj close to 0.9, indicating that the response values in the model can better reflect the relationship between sensory evaluation and each factor, and the model fitting degree is good. The P values of the initial sugar content, initial inoculum amount and fermentation time in the first order term are 0.0007, 0.0101 and 0.0053, respectively, and the P value of the initial sugar content is <0.01, indicating that the influence on the response value in the model is extremely significant. The P value of the initial inoculum amount is <0.05, indicating that the influence on the response value in the model is significant. The P value of the fermentation time is less than 0.01, indicating that the fermentation time has an extremely significant influence on the sensory evaluation in the model. The P value of the interaction between the initial sugar content and the initial inoculum amount in the model is 0.0101<0.05, indicating that the interaction of the two conditions has a significant influence on the sensory score. The P values of other condition interactions are all greater than 0.05, indicating that the influence on the response value is not significant. In the quadratic term, the P value of A 2 B is 0.02<0.05, which is significant, and the P values of other quadratic terms are all greater than 0.05.

[0129] As shown in Table 5, the model is predicted through the test results and variance analysis, so that the better fermentation process of the coconut water low-alcohol beverage can be obtained as follows: the initial sugar content is 14 °Brix, the initial inoculum amount is 2%, the fermentation time is 36 h, the better temperature is 21 ℃, and the better initial pH is 3.5. The model predicts that the sensory score reaches 94 points under the process. The process condition is verified by experiment, and the actual sensory evaluation is 95 points, with an error of less than 1% from the predicted value, indicating that the response surface experiment is reliable for the optimization of the fermentation process parameters. Example 1 is the best embodiment of the present application.

[0130] Experimental Example 4 Fermentation property analysis

[0131] Referring to the preparation method in Example 1, the fermentation liquid at different times (0 h, 9 h, 18 h, 27 h, 36 h) was taken in the fermentation stage for detection of pH, total acid, sugar content, reducing sugar and alcohol content, and the fermentation of Saccharomyces cerevisiae 1-7-1 single strain was taken as a control (the inoculum amount was 2% in single strain fermentation, and the preparation method referred to Example 1).

[0132] pH detection method: Take 3 mL of sample into a test tube, insert the pH electrode into the test tube, and use a pH meter to read the reading.

[0133] The detection method of total acid refers to the indicator method in "GB / T 10538-2006 General analysis method for grape and fruit wine".

[0134] Sugar content detection method: Use a pipette to transfer 400 μL of sample to the sensor, and measure it using a sugar refractometer, expressed in °Brix.

[0135] The detection method of reducing sugar refers to the direct titration method in "GB / T 10538-2006 General Analysis Methods for Grape and Fruit Wine".

[0136] The detection method of alcohol content refers to the alcohol meter method in "GB / T 10538-2006 General analysis method for grape wine and fruit wine".

[0137] Result analysis:

[0138] 1. pH and total acid during fermentation

[0139] Depend on Figure 11 As can be seen, the pH of the fermentation broth from mixed fermentations of 1-7-1 and A33 slowly decreased over time, reaching a minimum of 3.4. The pH of the fermentation broth from single-strain 1-7-1 fermentations initially decreased and then increased, reaching a minimum of 3.42. The pH of the fermentation broth from single-strain A33 fermentations slowly decreased before 27 hours, then decreased more rapidly, reaching a minimum of 3.39. This suggests that the pH decrease during mixed fermentation is primarily due to the production of metabolites, such as lactic acid and other organic acids, by the A33 strain during fermentation. The pH of the mixed fermentation was slightly lower than that of the A33 single-strain fermentation during the early stages. This is because 1-7-1 also produces acids during the early stages. The pH of the fermentation broth from single-strain 1-7-1 fermentations indicates that after 9 hours, the amount of acid produced is less than that of alkaline substances, or almost no acid is produced, resulting in an increase in pH. The rate of decrease in A33 single-strain fermentation increased after 27 hours, likely due to the increased activity and acid production of A33 after 27 hours.

[0140] Depend on Sample b It can be seen that the total acid content of the fermentation broth produced by the mixed fermentation of 1-7-1 and A33 showed a trend of slow and uniform increase, with the highest value being 5.77 g / L; the total acid content of the fermentation broth produced by the single-strain fermentation of 1-7-1 showed a trend of first increasing and then decreasing, with a peak value of 5.54 g / L at 9 h; the total acid content of the fermentation broth produced by the single-strain fermentation of A33 showed a trend of slow and uniform increase before 27 h, and the rate of increase of the total acid content increased after 27 h, with the highest value being 5.98 g / L.

[0141] Depend on AlcoholsFrom Fig. 1 and Fig. 9b, it can be seen that the change trend of pH value and total acid content of the three fermentation liquids is negatively correlated, and the reason for the change trend of total acid content is basically the same as that of pH value.

[0142] 2. Sugar content and reducing sugar content during fermentation

[0143] From Fig. 1 and Fig. 9b, it can be seen that the change trend of pH value and total acid content of the three fermentation liquids is negatively correlated, and the reason for the change trend of total acid content is basically the same as that of pH value. Acids From Fig. 1 and Fig. 9b, it can be seen that the change trend of pH value and total acid content of the three fermentation liquids is negatively correlated, and the reason for the change trend of total acid content is basically the same as that of pH value. From Fig. 1 and Fig. 9b, it can be seen that the change trend of pH value and total acid content of the three fermentation liquids is negatively correlated, and the reason for the change trend of total acid content is basically the same as that of pH value. From Fig. 1 and Fig. 9b, it can be seen that the change trend of pH value and total acid content of the three fermentation liquids is negatively correlated, and the reason for the change trend of total acid content is basically the same as that of pH value.

[0144] From Fig. 1 and Fig. 9b, it can be seen that the change trend of pH value and total acid content of the three fermentation liquids is negatively correlated, and the reason for the change trend of total acid content is basically the same as that of pH value. Aldehydes From Fig. 1 and Fig. 9b, it can be seen that the change trend of pH value and total acid content of the three fermentation liquids is negatively correlated, and the reason for the change trend of total acid content is basically the same as that of pH value. From Fig. 1 and Fig. 9b, it can be seen that the change trend of pH value and total acid content of the three fermentation liquids is negatively correlated, and the reason for the change trend of total acid content is basically the same as that of pH value.

[0145] Ketones From Fig. 1 and Fig. 9b, it can be seen that the change trend of pH value and total acid content of the three fermentation liquids is negatively correlated, and the reason for the change trend of total acid content is basically the same as that of pH value. Esters From Fig. 1 and Fig. 9b, it can be seen that the change trend of pH value and total acid content of the three fermentation liquids is negatively correlated, and the reason for the change trend of total acid content is basically the same as that of pH value. From Fig. 1 and Fig. 9b, it can be seen that the change trend of pH value and total acid content of the three fermentation liquids is negatively correlated, and the reason for the change trend of total acid content is basically the same as that of pH value.

[0146] 3. Change of alcohol content during fermentation

[0147] The Saccharomyces cerevisiae can utilize the sugar substances in the culture medium to convert them into alcohol. From Fig. 1 and Fig. 9b, it can be seen that the change trend of pH value and total acid content of the three fermentation liquids is negatively correlated, and the reason for the change trend of total acid content is basically the same as that of pH value. 1-7-1&A33 mixed strain fermentationAs can be seen, the alcohol content of the fermentation broth of the mixed fermentation of 1-7-1 and A33 showed an upward trend with time, and the alcohol content reached 1.37% at 36h. The alcohol content of the fermentation broth of the single fermentation of 1-7-1 showed an upward trend with time, and the alcohol content reached 1.53% at 36h. It can be seen that the alcohol content of the mixed fermentation is lower than that of the single fermentation of Saccharomyces cerevisiae, which is presumably due to the slight inhibition of the formation of alcohol by Lactobacillus plantarum A33. It can also be seen that the coconut water beverage prepared in Example 1 meets the requirements of low-alcohol beverages.

[0148] Example 5 Analysis of volatile components of low-alcohol coconut water beverage

[0149] A low-alcohol coconut water beverage was prepared according to the preparation method in Example 1, and at the same time, a coconut water beverage fermented by 1-7-1 (inoculum 2% during single fermentation, preparation method according to Example 1), a coconut water beverage fermented by A33 (inoculum 2% during single fermentation, preparation method according to Example 1), a fermentation starting point (i.e. coconut water inoculated in Example 1, fermentation time 0h) and original coconut water (i.e. coconut water filtered with gauze in Example 1) were used as controls.

[0150] The volatile components in the samples were detected by GC-MS method:

[0151] Take 5mL of sample, 10μL of internal standard (2-methyl-3-heptanone, 0.816ppm), and place it in a 20mL glass bottle. Expose the SPME fiber (100μm, Supelco, Inc., Bellefonte, PA) coated with divinylbenzene / carboxylic acid / polydimethylsiloxane (DVB / CAR / PDMS) to the top of the glass bottle at 50℃ for 50min. After equilibration for 5min, continue stirring at 250rpm. Desorb the volatile compounds in the gas chromatography inlet at 250℃ for 5min. Qualitatively analyze the compounds by comparing the mass spectra of MS and NIST II library. Quantify the compounds according to the peak area of the internal standard and the compounds.

[0152] Results analysis:

[0153] After GC-MS detection of the five samples, a total of 82 aroma components were obtained through spectral library comparison and processing, which were divided into six categories: alcohols, aldehydes, ketones, acids and esters. The statistical results of the proportion of each type of aroma component are shown in Table 6. Each aroma substance has a different sensory threshold, which is used to judge the critical value of the aroma substance that can be sensed in the matrix. Odor activity value is the ratio of the concentration of aroma substance to the sensory threshold, which is used to evaluate the contribution of aroma substance to the aroma of coconut water low-alcohol beverage. Aroma substances with odor activity value≥1 have a greater contribution to the overall aroma, and aroma substances with odor activity value>10 are determined as important aroma components. The results of the analysis of the odor activity value of the flavor substances in the beverage are shown in Table 7.

[0154] Table 6 Proportion of flavor substances in beverage

[0155] A33 single strain fermentation 1-7-1 single strain fermentation Fermentation starting point Original coconut water ​ ​ ​ 15.55％ 42.42％ 13.45％ 0.11％ 28.48％ ​ 1.99％ 22.98％ 71.87％ 0.26％ 2.91％ ​ 23.47％ 49.05％ 4.77％ 0.90％ 21.81％ ​ 2.33％ 17.76％ 75.62％ 0.25％ 4.05％ ​ 13.73％ 24.30％ 38.00％ 0.62％ 23.36％

[0156] Table 7 Analysis results of odor active value of flavor substances in beverage

[0157]

[0158]

[0159] Note: - indicates not detected

[0160] As shown in Table 6, the content proportions of alcohols, acids and esters after 1-7-1 and A33 mixed bacteria fermentation are high, accounting for 15.55%, 42.42% and 28.48% respectively. Compared with fermentation starting point, the proportion of aldehydes is greatly reduced, and the proportion of esters is greatly increased. The content of acid and aldehyde substances in A33 single bacteria fermentation is relatively high, accounting for 22.98% and 71.87% of the total amount respectively. The content proportions of alcohol, acid and ester flavor substances in 1-7-1 single bacteria fermentation are high, accounting for 23.47%, 49.05% and 21.81% respectively. In combination with the above results, 1-7-1 and A33 mixed bacteria fermentation can promote the formation of ester flavor substances and improve the flavor of low-alcohol coconut water beverage.

[0161] As shown in Table 7, there are 18 kinds of aroma components contributed more by 1-7-1 and A33 mixed bacteria fermentation, of which 11 are important aroma components, the highest being ethyl octanoate and ethyl decanoate, accounting for 94.83 and 68.94 respectively, and the characteristic flavors are grape, wine and sweet almond flavor; there are only 5 kinds of aroma substances contributed more by A33 single bacteria fermentation, of which 2 are important aroma components, i.e. 2-butyl mercaptan and nonanal, accounting for 34.08 and 49.44 respectively, 2-butyl mercaptan has a sulfur-containing flavor, which is an unpleasant flavor, and nonanal has a fatty and citrus flavor; there are 14 kinds of aroma components contributed more by 1-7-1 single bacteria fermentation, of which 10 are important aroma components, the highest being benzaldehyde and ethyl octanoate, accounting for 103.49 and 72.31 respectively, and the characteristic flavors are honey, chocolate, wine and sweet almond flavor; there are 5 kinds of aroma components contributed more by fermentation starting point, of which 1 is an important aroma component, i.e. nonanal, with an odor active value of 38.09, and the characteristic flavor is fatty and citrus flavor; there are 4 kinds of aroma components contributed more by original coconut water, of which nonanal is an important aroma component, with an odor active value of 20.77, and the characteristic flavor is fatty and citrus flavor. Octanoic acid, nonanoic acid, nonanal and ethyl decanoate are characteristic flavors in the five samples, and they are obviously improved in the case of mixed bacteria fermentation.

[0162] The number of flavor compounds with odor activity value greater than 1 after mixed fermentation of 1-7-1 and A33 is the most, which is 20, and the odor activity value of ester is the highest, so the ester in mixed fermentation contributes more to the flavor, making the beverage have fruit aroma. The odor activity value of 2-butyl mercaptan in A33 single strain fermentation is higher, which is an unpleasant sulfur smell, but it is not found in mixed fermentation. The odor activity value of propylamine alcohol in Saccharomyces cerevisiae 1-7-1 single strain fermentation is higher, which is a strong alcoholic smell, and it is also not found in mixed fermentation, indicating that mixed fermentation can improve the bad flavor of Lactobacillus plantarum single strain and Saccharomyces cerevisiae single strain fermentation. Two kinds of lactone flavor compounds are embodied in mixed fermentation, and the flavor is coconut flavor, indicating that mixed fermentation can improve the typicality of low-alcohol coconut water beverage flavor.

[0163] Obviously, the above examples are only examples for the sake of clarity, and are not limitations on the embodiments. Based on the above description, those skilled in the art can also make other different forms of changes or variations. Here, it is not necessary and impossible to enumerate all the embodiments. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A method of preparing a low-alcohol coconut water beverage, characterized by, The method comprises the following steps: The coconut water is taken, sugar and acid are adjusted, sterilized, inoculated with Saccharomyces cerevisiae 1-7-1 and Lactobacillus plantarum A33 for mixed fermentation, centrifuged to obtain supernatant, and the low-alcohol coconut water beverage is obtained. In the sugar and acid adjusting step, the sugar content of the coconut water is adjusted to 14 °Brix, and the pH value is adjusted to 3.4-3.

6. the inoculum of Saccharomyces cerevisiae 1-7-1 is 5 x 10 6 cfu / mL; the inoculum of Lactobacillus plantarum A33 is 5 x 10 6 cfu / mL; The mixed fermentation conditions are 21-24 ℃ and 24-36 h.

2. The method according to claim 1, wherein the mixed fermentation conditions are 21 ℃ and 36 h.

3. The method according to claim 1, wherein the Saccharomyces cerevisiae 1-7-1 is inoculated in the form of seed liquid, and the preparation method of the Saccharomyces cerevisiae 1-7-1 seed liquid comprises the following steps: taking the glycerol tube preserved Saccharomyces cerevisiae 1-7-1 and inoculating it into YEPD liquid medium at an inoculation amount of 2%-5%, culturing for 18-24 h per generation, subculturing for 2-3 times, centrifuging at 8000-10000 r / min for 8-10 min, washing with distilled water for 2-3 times, and taking the bacterial slurry and suspending it in an equal volume of coconut water after sugar and acid adjustment for standby. The Lactobacillus plantarum A33 is inoculated in the form of seed liquid, and the preparation method of the Lactobacillus plantarum A33 seed liquid comprises the following steps: taking the glycerol tube preserved Lactobacillus plantarum A33 and inoculating it into YEPD liquid medium at an inoculation amount of 2%-5%, culturing for 22-26 h per generation, subculturing for 2-3 times, centrifuging at 8000-10000 r / min for 8-10 min, washing with distilled water for 2-3 times, and taking the bacterial slurry and suspending it in an equal volume of coconut water after sugar and acid adjustment for standby.

4. The method according to claim 3, wherein the preparation method of the Saccharomyces cerevisiae 1-7-1 seed liquid comprises the following steps: taking the glycerol tube preserved Saccharomyces cerevisiae 1-7-1 and inoculating it into YEPD liquid medium at an inoculation amount of 5%, culturing for 18 h per generation, subculturing for 3 times, centrifuging at 8000 r / min for 10 min, washing with distilled water for 3 times, and taking the bacterial slurry and suspending it in an equal volume of coconut water after sugar and acid adjustment for standby. The preparation method of the Lactobacillus plantarum A33 seed liquid comprises the following steps: taking the glycerol tube preserved Lactobacillus plantarum A33 and inoculating it into MRS liquid medium at an inoculation amount of 5%, culturing for 24 h per generation, subculturing for 3 times, centrifuging at 8000 r / min for 10 min, washing with distilled water for 3 times, and taking the bacterial slurry and suspending it in an equal volume of coconut water after sugar and acid adjustment for standby.

5. The method according to claim 1, wherein the coconut water is obtained by taking water from an old coconut after breaking the shell; The coconut water is filtered before sugar and acid adjustment; The sterilization conditions are 65-75 ℃ for 30 min; The centrifugation conditions are 8000-10000 rpm, 3-5 ℃, and 5-8 min.

6. The method according to claim 5, wherein the pH value is adjusted to 3.5 in the sugar and acid adjusting step; The sterilization conditions are 65 ℃ for 30 min; The centrifugation conditions are 10000 rpm, 4 ℃, and 5 min. ​ ​ ​ ​ ​ 7. A low-alcohol coconut water beverage obtainable by the process according to any one of claims 1 to 6.

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