Fermented persimmon fruit beverage containing gamma-aminobutyric acid and plant lactobacillus S3-2 used by fermented persimmon fruit beverage

Abstract

The invention provides a fermented persimmon fruit beverage containing gamma-aminobutyric acid and plant lactobacillus S3-2 used by the fermented persimmon fruit beverage, and belongs to the technical field of food microorganisms. Comprising the following steps: (1) mixing persimmon pulp, pumpkin pulp and water, and adding a color fixative to obtain mixed fruit and vegetable juice; and (2) adding white granulated sugar and a compound stabilizer into the mixed fruit and vegetable juice, sterilizing and cooling, inoculating a leavening agent for constant-temperature fermentation, and sterilizing to obtain the fermented persimmon fruit beverage, the fermentation agent is composed of the plant lactobacillus S3-2 and the streptococcus thermophilus, and the preservation number of the plant lactobacillus S3-2 is CGMCC (China General Microbiological Culture Collection Center) NO.32204. The screened plant lactobacillus S3-2 and streptococcus thermophilus are used as leavening agents to ferment the persimmon fruit drink, the content of total phenols, flavones and GABA in the persimmon fruit drink can be effectively increased, the oxidation resistance is improved, the tannin content is reduced, and the nutritional value of the persimmon fruit drink is remarkably increased.

Description

Technical Field

[0001] The invention belongs to the field of food microorganisms, and in particular relates to a fermented persimmon fruit beverage containing gamma-aminobutyric acid and Lactobacillus plantarum S3-2 used therein. Background Art

[0002] γ-aminobutyric acid (GABA) is a natural, non-protein amino acid with multiple physiological functions such as lowering blood pressure, regulating mood, improving sleep quality and enhancing memory. It is a new type of food functional factor. In 2009, my country approved it as a new resource food and gradually applied it to the food, medicine and other industries. GABA in the human body can be produced by glutamate decarboxylase catalyzing glutamate. With the increase of age and the increase of life pressure, the GABA content gradually decreases, while the GABA content in foods from natural sources is generally low and cannot meet the demand. Therefore, how to efficiently synthesize GABA and develop functional foods rich in GABA to appropriately supplement GABA is a hot topic of general concern among researchers.

[0003] At present, the traditional synthesis pathways of GABA mainly include chemical method and biological method. The chemical method has high cost, serious environmental pollution, and it is easy for residual chemical substances in the raw materials. The reaction is difficult to control and is not suitable for use in food; the biological method is mainly synthesized by plant endogenous enzymes and microbial fermentation broth. Compared with the shortcomings of plant enrichment method, such as cumbersome operation, low yield and instability, the microbial fermentation method has high yield, strong safety and mild conditions, and is an ideal way to enrich GABA.

[0004] Compared with fermented dairy products, fermented plant-based foods are more nutritious and more friendly to people with lactose intolerance and dairy allergies. Persimmon is a traditional fruit in my country, with the world's largest output. It has a unique flavor and high nutritional value, but a short shelf life, difficult storage and transportation, and insufficient post-harvest deep processing technology. By using high-yield γ-aminobutyric acid strains and optimizing stabilizers and fermentation conditions, fermented persimmon fruit beverages with good taste, stable tissue state, and rich in γ-aminobutyric acid can be prepared. This can achieve the diversification of the flavor, taste, and nutritional and health effects of plant-based foods fermented by Lactobacillus plantarum S3-2, and at the same time help to drive the high-value utilization of persimmon fruit, which has broad market value and significance. Summary of the invention

[0005] The object of the present invention is to provide a fermented persimmon fruit beverage rich in gamma-aminobutyric acid.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing a fermented persimmon fruit beverage containing γ-aminobutyric acid, comprising the following steps:

[0008] (1) mixing persimmon pulp, pumpkin pulp and water and adding a color preservative to obtain a mixed fruit and vegetable juice 1;

[0009] (2) adding white sugar and a compound stabilizer to the mixed fruit and vegetable juice 1, sterilizing and cooling, to obtain a mixed fruit and vegetable juice 2;

[0010] (3) inoculating a fermentation agent into the mixed fruit and vegetable juice 2 for constant temperature fermentation, and sterilizing to obtain the fermented persimmon fruit drink;

[0011] The fermentation agent is composed of Lactobacillus plantarum S3-2 and Streptococcus thermophilus in a live cell count ratio of 1.8 to 2.2:1, wherein the preservation number of Lactobacillus plantarum S3-2 is CGMCC NO.32204.

[0012] Preferably, the volume ratio of persimmon pulp, pumpkin pulp and water is 2-4:1:8-9.

[0013] Preferably, the color preservative is citric acid, and the added amount is 0.16-0.20% of the volume of the mixed fruit and vegetable juice.

[0014] Preferably, the compound stabilizer contains the following substances: 0.12-0.18% (w / v) pectin, 0.070-0.080% (w / v) sodium carboxymethyl cellulose and 0.03-0.07% (w / v) guar gum.

[0015] Preferably, the sterilization conditions are 90-95°C for 15-25 min.

[0016] Preferably, the inoculation amount of the fermentation agent is 3-5% of the volume of the mixed fruit and vegetable juice 2, and the bacterial activities of the plant lactobacillus S3-2 and the thermophilic streptococcus are both 10 7 ~10 9 CFU / g.

[0017] Preferably, the constant temperature fermentation condition in step (2) is 35-40° C. for 10-20 h.

[0018] The invention provides a fermented persimmon fruit beverage containing gamma-aminobutyric acid.

[0019] The present invention also provides Lactobacillus plantarum S3-2, which is deposited in the Institute of Microbiology, Chinese Academy of Sciences, General Microbiology Center, China Culture Collection Administration Committee, with the address at No. 3, Yard No. 1, Beichen West Road, Chaoyang District, Beijing. The deposit date is October 14, 2024, and the deposit number is CGMCCNO.32204.

[0020] Beneficial Effects

[0021] The present invention separates 57 suspected lactic acid bacteria strains from fruits such as persimmon, mulberry and blueberry, and screens out a plant lactobacillus S3-2 that can produce high GABA, and the GABA content in the fermentation liquid sample is 369.75 μg / mL.

[0022] The present invention uses centrifugal sedimentation rate as the main investigation index and determines the ratio of the best compound stabilizer: 0.15% pectin + 0.05% guar gum + 0.075% sodium carboxymethyl cellulose. The present invention uses sensory score as an investigation index and determines that the inoculation amount of the best starter is 4%, the fermentation time is 15h, and the initial pH is 4.5. At this time, the product sensory score is 86.73±1.57. After the fermented persimmon fruit beverage provided by the present invention is fermented with a specific combination of starter, the total phenol and flavonoid contents increase by 57.90% and 30.98%, respectively, and the antioxidant capacity is improved; the tannin content is reduced by 68.67%, effectively reducing the astringency; the GABA content increases by 83.12%, and the resulting product has a good organizational state, good juice fluidity, delicate taste, no stratification, precipitation and other phenomena, and significantly improves the nutritional value of persimmon fruit products. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The colony morphology of S3-2 on MRS plate (left) and the bacterial morphology of S3-2 after Gram staining (right);

[0024] Figure 2 is the standard curve of GABA derivatives;

[0025] Figure 3 is the PCR amplification result of strain S3-2;

[0026] Figure 4 is the phylogenetic tree of strain S3-2;

[0027] Figure 5 To study the effects of different fermentation agent combinations on the GABA content in persimmon fruit drinks;

[0028] Figure 6 The effect of different stabilizer addition amounts on the centrifugal sedimentation rate of persimmon fruit beverage fermented by Lactobacillus plantarum S3-2;

[0029] Figure 7 is the change of total phenol content during fermentation;

[0030] Figure 8 The changes of flavonoid content during fermentation;

[0031] Fig. 9 The tannin content changes during the fermentation process.

[0032] Collection Instructions

[0033] Lactobacillus plantarum S3-2, Latin name Lactiplantibacillus plantarum, is deposited in the Institute of Microbiology, Chinese Academy of Sciences, General Microbiology Center, China Culture Collection Administration, at No. 3, Yard No. 1, Beichen West Road, Chaoyang District, Beijing. The deposit date is October 14, 2024, and the deposit number is CGMCC NO.32204. DETAILED DESCRIPTION

[0034] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0035] Example 1

[0036] Strain isolation and purification

[0037] The surface of fresh fruits (persimmons, mulberries and blueberries) was cleaned and sterilized with sodium hypochlorite, homogenized with a sterile beater, and the samples were graded diluted with sterile saline. 1 mL of the dilution was spread on a MRS solid culture medium plate containing 2% calcium carbonate, and incubated inverted at 37°C for 48 h. The colonies were separated and purified by the plate streak method to obtain pure single colonies.

[0038] Results 57 strains with obvious transparent zones in MRS medium were isolated, and the production of GABA in the suspected lactic acid bacteria strains was qualitatively analyzed by paper chromatography, and 6 strains that may produce GABA were selected. Observation of colony and bacterial characteristics showed that on MRS medium, the colonies were mostly milky white, with regular edges and smooth and convex round or oval colonies. Catalase, nitrate reduction, gelatin liquefaction and hydrogen sulfide tests were all negative. Gram staining was positive, and under the microscope (×100) it was short rod-shaped ( Figure 1 (Figure 2) shows the colony morphology and Gram staining results of the S3-2 strain.

[0039] A single colony was inoculated into MRS liquid medium, cultured to the logarithmic phase, and stored in a glycerol tube at -20°C for future use. The isolated strain was inoculated with 2% inoculum into MRS liquid medium containing 1% sodium L-glutamate, and cultured at 37°C for 24 hours to obtain a lactic acid bacteria fermentation broth sample, which was centrifuged at 10,000 r / min for 10 minutes, and the supernatant was retained and filtered through a 0.22 μm filter membrane. The GABA content was detected by OPA pre-column derivatization combined with HPLC.

[0040] The chromatographic conditions are:

[0041] Chromatographic column: (4.6nm×250mm, 5μm); detection wavelength: 228nm; mobile phase A: acetonitrile, mobile phase B: 20mmol / L crystalline sodium acetate solution (glacial acetic acid adjusted to pH=7.3), A:B=21:79 (volume ratio); flow rate: 0.8mL / min; column temperature: 30℃; injection volume: 20μL.

[0042] The standard curve is as follows Figure 2 shown.

[0043] As shown in Table 1, all the fermentation broth samples tested contained GABA, and the content ranged from 111.33 μg / mL to 369.75 μg / mL. Among them, the S3-2 strain produced the highest GABA content.

[0044] Table 1 GABA content in fermentation broth samples of different strains

[0045]

[0046] 3. Determination of growth curve

[0047] The plant lactobacillus S3-2 culture was inoculated into MRS liquid medium at 1% inoculation volume and cultured at 37°C for 24 hours. The absorbance of the fermentation liquid at 600nm was measured by spectrophotometer every 2 hours, and the viable bacteria were counted at the same time. The results showed that the S3-2 strain entered the logarithmic growth phase at 4 hours and the stable phase at 10 hours. The maximum viable bacteria count reached 4.1×10 9 CFU / mL.

[0048] 4. Strain identification

[0049] The S3-2 strain isolated above was commissioned to be identified by 16S rDNA. The bacterial 16S rDNA gene amplification universal primers 27F / 1492R sequence universal primers (primer sequences: 27F (SEQ ID NO.1): AGAGTTTGATCMTGGCTCAG; 1492R (SEQ ID NO.2): GGTTACCTTGTTACGACTT) were used for amplification (the electrophoresis pattern is shown in Figure 1). Figure 3 ), the results showed that the length of the 16S rDNA sequence of the bacteria was 1455bp, see SEQ ID NO.3, the sequence of SEQ ID NO.3 was analyzed for homology with the 16S rDNA in the GenBank database, a phylogenetic evolutionary tree was constructed, and the species relationship of the strain was determined ( Figure 4)。The results showed that the homology between strain S3-2 and Lactiplantibacillus plantarum reached 100%, and it was identified as Lactiplantibacillus plantarum and taxonomically named Lactiplantibacillus plantarum.

[0050] SEQ ID NO.3

[0051] AGGACGAACGCTGGCGGCGTGCCTAATACATGCAAGTCGAACGAACTC

[0052] TGGTATTGATTGGTGCTTGCATCATGATTTACATTTGAGTGAGTGGCGA

[0053] ACTGGTGAGTAACACGTGGGAAACCTGCCCAGAAGCGGGGGATAACA

[0054] CCTGGAAACAGATGCTAATACCGCATAACAACTTGGACCGCATGGTCC

[0055] GAGCTTGAAAGATGGCTTCGGCTATCACTTTTGGATGGTCCCGCGGCGT

[0056] ATTAGCTAGATGGTGGGGTAACGGCTCACCATGGCAATGATACGTAGCC

[0057] GACCTGAGAGGGTAATCGGCCACATTGGGACTGAGACACGGCCCAAA

[0058] CTCCTACGGGAGGCAGCAGTAGGGAATCTTCCACAATGGACGAAAGTC

[0059] TGATGGAGCAACGCCGCGTGAGTGAAGAAGGGTTTCGGCTCGTAAAA

[0060] CTCTGTTGTTAAAGAAGAACATATCTGAGAGTAACTGTTCAGGTATTGA

[0061] CGGTATTTAACCAGAAAGCCACGGCTAACTACGTGCCAGCAGCCGCGG

[0062] TAATACGTAGGTGGCAAGCGTTGTCCGGATTTATTGGGCGTAAAGCGA

[0063] GCGCAGGCGGTTTTTTAAGTCTGATGTGAAAGCCTTCGGCTCAACCGA

[0064] AGAAGTGCATCGGAAACTGGGAAACTTGAGTGCAGAAGAGGACAGTG

[0065] GAACTCCATGTGTAGCGGTGAAATGCGTAGATATATGGAAGAACACCA

[0066] GTGGCGAAGGCGGCTGTCTGGTCTGTAACTGACGCTGAGGCTCGAAA

[0067] GTATGGGTAGCAAACAGGATTAGATACCCTGGTAGTCCATACCGTAAAC

[0068] GATGAATGCTAAGTGTTGGAGGGTTTCCGCCCTTCAGTGCTGCAGCTA

[0069] ACGCATTAAGCATTCCGCCTGGGGAGTACGGCCGCAAGGCTGAAACTC

[0070] AAAGGAATTGACGGGGGCCCGCACAAGCGGTGGAGCATGTGGTTTAA

[0071] TTCGAAGCTACGCGAAGAACCTTACCAGGTCTTGACATACTATGCAAAT

[0072] CTAAGAGATTAGACGTTCCCTTCGGGGACATGGATACAGGTGGTGCAT

[0073] GGTTGTCGTCAGCTCGTGTCGTGAGATGTTGGGTTAAGTCCCGCAACG

[0074] AGCGCAACCCTTATTATCAGTTGCCAGCATTAAGTTGGGCACTCTGGTG

[0075] AGACTGCCGGTGACAAACCGGAGGAAGGTGGGGATGACGTCAAATCA

[0076] TCATGCCCCTTATGACCTGGGCTACACACGTGCTACAATGGATGGTACA

[0077] ACGAGTTGCGAACTCGCGAGAGTAAGCTAATCTCTTAAAGCCATTCTC

[0078] AGTTCGGATTGTAGGCTGCAACTCGCCTACATGAAGTCGGAATCGCTA

[0079] GTAATCGCGGATCAGCATGCCGCGGTGAATACGTTCCCGGGCCTTGTAC

[0080] ACACCGCCCGTCACACACCATGAGAGTTTGTAACACCCAAAGTCGGTGGG

[0081] GTAACCTTTTAGG

[0082] Example 2

[0083] Application of strains in fermented persimmon beverages

[0084] (1) Wash and peel fresh persimmon and pumpkin, blanch in boiling water for 3 minutes, pulp them separately, and then mix them in a volume ratio of persimmon: pumpkin: water = 3:1:9, add 0.18% (w / v) citric acid to protect the color, and pass through an 80-mesh sieve to obtain a mixed fruit and vegetable juice 1;

[0085] (2) adding 4% (w / v) white sugar and a compound stabilizer (0.15% (w / v) pectin, 0.075% (w / v) sodium carboxymethyl cellulose and 0.05% (w / v) guar gum to the mixed fruit and vegetable juice 1 obtained in step (1), adjusting the initial pH to 4.5), sterilizing at 90° C. for 20 min, and cooling to 37° C. to obtain mixed fruit and vegetable juice 2;

[0086] (3) 3% (w / v) of the starter culture (Streptococcus thermophilus: Lactobacillus plantarum S3-2=1:2) was inoculated into the mixed fruit and vegetable juice 2, mixed well, and fermented at 37° C. for 15 h. The resulting product was sterilized at 90° C. for 10 min.

[0087] The microbial indicators of the product were investigated using the dilution plate method according to national standards. The results showed that the number of viable lactic acid bacteria in the persimmon beverage reached 1.36×10 8CFU / mL, no mold, E. coli and yeast were detected, and the microbial indicators were in line with national standards.

[0088] Example 3

[0089] Effects of different starter culture combinations on GABA content in persimmon beverages

[0090] ST+LB group: persimmon: pumpkin: water = 3:1:9, citric acid 0.18% (w / v), white sugar 4% (w / v), compound stabilizer (pectin 0.15% (w / v), sodium carboxymethyl cellulose 0.075% (w / v) and guar gum 0.05% (w / v)), inoculum 3% (Streptococcus thermophilus: Lactobacillus bulgaricus = 1:2);

[0091] ST+S3-2 group: persimmon: pumpkin: water = 3:1:9, citric acid 0.18% (w / v), white sugar 4% (w / v), compound stabilizer (pectin 0.15% (w / v), sodium carboxymethyl cellulose 0.075% (w / v) and guar gum 0.05% (w / v)), inoculation amount 3% (Thermophilic Streptococcus: Lactobacillus plantarum S3-2 = 1:2).

[0092] The GABA content at 0h, 3h, 6h, 9h, 12h and 15h was measured respectively. The results are shown in Table 2 and Figure 5 shown.

[0093] Table 2 GABA content in persimmon drinks of different groups and different fermentation times (μg / mL)

[0094] combination 0h 3h 6h 9h 12h 15h ST+LB 59.15±1.34 60.37±1.22 63.69±1.42 67.86±1.60 74.73±1.41 81.51±1.50 ST+S3-2 59.15±1.34 62.38±1.51 65.79±1.62 73.60±1.59 83.19±1.77 108.32±1.43

[0095] From Table 2 and Figure 5 It can be seen that the GABA content increased after lactic acid bacteria fermentation, and the GABA content showed an overall increasing trend during the fermentation period. Among them, the GABA content of the plant lactobacillus S3-2 group reached 108.32μg / mL at 15h of fermentation, which was 1.83 times the initial content and better than the ST+LB group. This shows that persimmon juice is an effective matrix that can provide good nutrition for plant lactobacillus S3-2 fermentation and increase the GABA content in persimmon fruit beverages.

[0096] Example 4

[0097] Types and dosage of stabilizers

[0098] The experiment selected commonly used stabilizers pectin, guar gum, sodium carboxymethyl cellulose (CMC-Na) and xanthan gum, and added them to the product at 0.05%, 0.10%, 0.15%, 0.20% and 0.25% respectively. The product was prepared according to the process flow of persimmon beverage in Example 2 and refrigerated at 4°C. The centrifugal sedimentation rate was used as the main evaluation index to investigate the effect of the type and amount of a single stabilizer on the stability of the product. The results are as follows: Figure 6 shown.

[0099] The product obtained by fermenting persimmon juice in the experiment is a turbid juice. There are many macromolecular substances in the beverage system. The beverage stability is poor during processing and storage, and the product is prone to precipitation or stratification. The smaller the centrifugal sedimentation rate, the better the product stability. Figure 6 With the increase of pectin addition, the product stability first increased and then tended to be flat, indicating that the beverage obtained when the pectin addition was 0.15% had better stability, so 0.15%-0.20% was selected as the pectin addition to avoid excessive addition resulting in high product viscosity and unpleasant taste; the centrifugal sedimentation rate of sodium carboxymethyl cellulose was the lowest when the addition amount was 0.10%, and when the addition amount was greater than 0.10%, the centrifugal sedimentation rate showed an increasing trend, which may be due to the fact that there were no protein micelles to adsorb the excess sodium carboxymethyl cellulose molecules, making the product stability worse, so 0.05%-0.10% was selected as sodium carboxymethyl cellulose. Addition amount: When the guar gum addition amount is 0.10%, the product stability is the best. After comprehensively considering the cost and stability, 0.05%~0.10% is selected as the addition amount of guar gum; when the xanthan gum addition amount is 0.05%, the corresponding centrifugal sedimentation rate is the lowest, and when the addition amount is higher than 0.05%, the stability gradually deteriorates, indicating that after excessive addition of xanthan gum, the network structure formed by the xanthan gum molecules is destroyed, and with the increase of xanthan gum, the product fluidity deteriorates, and even appears jelly-like when the addition amount is 0.25%, which destroys the product tissue state and deteriorates the taste. Therefore, xanthan gum is not considered as a stabilizer in subsequent experiments.

[0100] In summary, pectin, CMC-Na and guar gum were preliminarily determined as compound stabilizers, and the selection of compound addition ratio was investigated. A 3-factor 3-level experiment was designed, and L 9 (3 3 ) Orthogonal test design table, with centrifugal sedimentation rate as the main evaluation index to obtain the optimal compound stabilizer dosage. The orthogonal test factor levels are shown in Table 3.

[0101] Table 3 Orthogonal experimental design factor levels

[0102]

[0103] Determination of centrifugal sedimentation rate

[0104] The stability of the fermented persimmon product was investigated by centrifugal sedimentation rate. The fermented product was added to a centrifuge tube and weighed. The tube was centrifuged at 6000 r / min for 15 min. The supernatant was removed and the mass of the precipitate was accurately weighed. The centrifugal sedimentation rate was calculated according to the formula.

[0105]

[0106] In the formula, m is the mass of the supernatant discarded after centrifugation;

[0107] m0——the mass of the empty centrifuge tube;

[0108] m1——the mass of centrifuge tube and sample;

[0109] The effect of compound stabilizer on product stability was investigated, and the results are shown in Table 4.

[0110] Table 4 Orthogonal test design and range analysis results

[0111]

[0112] As shown in Table 4, the order of influence of the three stabilizers on product stability is guar gum>pectin>CMC-Na, and the best treatment level is A3B2C3, that is, when the compound stabilizer is 0.15% pectin, 0.075% CMC-Na, and 0.05% guar gum, the product centrifugal sedimentation rate is the lowest, that is, the stability is the best, which is better than the single stabilizer. The experiment prepared persimmon fruit beverage fermented by Lactobacillus plantarum S3-2 according to the above compound stabilizer ratio, and the obtained product has good tissue state, good juice fluidity, delicate taste, and no stratification, precipitation and other phenomena.

[0113] Example 5

[0114] Sensory evaluation of fermented persimmon beverage:

[0115] A 100-point system was used to conduct a comprehensive evaluation from four aspects: product color, flavor, taste and texture. A product evaluation panel of 10 tasters conducted a sensory evaluation and the average value was taken as the final score. The sensory scoring standards are shown in Table 5.

[0116] Table 5 Sensory scoring standards for fermented persimmon beverages

[0117]

[0118] The BOX-Benhnken in Design Expert 8.0.6 was used to carry out a three-factor three-level experimental design (Table 6). The optimal fermentation process parameters were determined by examining the effects of various factors (inoculation size, fermentation time and initial pH) on the sensory score. The experimental results are shown in Table 7.

[0119] Table 6 Experimental factor level design

[0120]

[0121] Table 7 Sensory evaluation results

[0122]

[0123]

[0124] According to the model established in the experiment, the optimal fermentation process parameters were predicted by further fitting analysis of the regression equation, which were 3.87% inoculation amount, 14.74h fermentation time and 4.44 initial pH. The sensory score of the persimmon beverage prepared under these fermentation process parameters was 86.82. Taking into account the actual production conditions, the fermentation process parameters were adjusted as follows: 4.0% inoculation amount, 15h fermentation time and 4.5 initial pH. The feasibility was investigated through specific experiments, and the experiment was repeated 3 times. The results showed that the sensory score of the persimmon beverage produced according to the adjusted fermentation process parameters was 86.73±1.57.

[0125] Example 6

[0126] The changes of total phenolic content, flavonoid content and tannin content of persimmon fruit beverage during fermentation were determined. Figures 7 to 9 shown.

[0127] from Figure 7 It can be seen that the total phenol content during lactic acid bacteria fermentation increases with the extension of fermentation time. During the fermentation period of 9h to 15h, the total phenol content shows a rapid growth trend. After 15h of fermentation, the total phenol content in the persimmon fruit beverage reached 1.04±0.07mg / mL, which was 57.90% higher than before fermentation, indicating that the fermentation agent provided by the present invention can improve the bioavailability and antioxidant activity of phenolic substances in persimmon fruit.

[0128] like Figure 8 It can be seen that the flavonoid content increased significantly before and after lactic acid bacteria fermentation, and the flavonoid content continued to increase with the extension of fermentation time. After 15 hours of fermentation, the flavonoid content in the persimmon fruit beverage reached 0.50±0.08mg / mL, an increase of 30.98% compared with before fermentation.

[0129] from Fig. 9 It can be seen that the tannin content of the persimmon beverage decreased by 68.67% after 15 hours of lactic acid bacteria combined fermentation, indicating that the fermentation agent provided by the present invention can greatly alleviate the astringency of the persimmon beverage and provide a new biological method for removing astringency of persimmon fruit.

[0130] In summary, the present invention provides a strain of Lactobacillus plantarum S3-2, and a persimmon beverage is prepared by fermenting a starter culture composed of Lactobacillus plantarum S3-2 and Streptococcus thermophilus, which can effectively increase the total phenol content, flavonoid content and GABA content in the persimmon beverage, alleviate the astringency of the persimmon beverage, and obtain a high sensory evaluation score.

[0131] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a fermented persimmon fruit beverage containing γ-aminobutyric acid, characterized in that: The following steps are involved: (1) mixing persimmon pulp, pumpkin pulp and water and adding a color preservative to obtain a mixed fruit and vegetable juice 1; (2) adding white sugar and a compound stabilizer to the mixed fruit and vegetable juice 1, sterilizing and cooling, to obtain a mixed fruit and vegetable juice 2; (3) inoculating a fermentation agent into the mixed fruit and vegetable juice 2 for constant temperature fermentation, and sterilizing to obtain the fermented persimmon fruit drink; The fermentation agent is composed of Lactobacillus plantarum S3-2 and Streptococcus thermophilus in a live cell count ratio of 1.8 to 2.2:1, wherein the preservation number of Lactobacillus plantarum S3-2 is CGMCC NO.32204.

2. The preparation method according to claim 1, characterized in that: The volume ratio of the persimmon pulp, pumpkin pulp and water is 2-4:1:8-9.

3. The preparation method according to claim 2, characterized in that: The color preservative is citric acid, and the added amount is 0.16-0.20% (w / v) of the total volume of persimmon pulp, pumpkin pulp and water.

4. The preparation method according to claim 3, characterized in that: The compound stabilizer contains the following substances: 0.12-0.18% (w / v) of pectin, 0.070-0.080% (w / v) of sodium carboxymethyl cellulose and 0.03-0.07% (w / v) of guar gum.

5. The preparation method according to claim 4, characterized in that: The sterilization conditions in step (2) are 90-95° C. for 15-25 min.

6. The preparation method according to claim 5, characterized in that: The inoculation amount of the fermentation agent is 3-5% of the volume of the mixed fruit and vegetable juice 2, and the bacterial activities of the plant lactobacillus S3-2 and the thermophilic streptococcus are both 10 7 ~10 9 CFU / g.

7. The preparation method according to claim 6, characterized in that: The constant temperature fermentation conditions in step (3) are 35-40° C. for 10-20 hours.

8. The fermented persimmon drink prepared by the preparation method according to any one of claims 1 to 7.

9. The Lactobacillus plantarum S3-2 used in the preparation method according to any one of claims 1 to 7, which is deposited at the Institute of Microbiology, Chinese Academy of Sciences, General Microbiology Center, China Culture Collection Administration, No. 3, Yard No. 1, Beichen West Road, Chaoyang District, Beijing, with a deposit date of October 14, 2024 and a deposit number of CGMCCNO.32204.

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