Lactobacillus plantarum MX and application thereof in loquat wine fermentation
By fermenting loquat wine with a mixture of Lactobacillus plantarum MX and yeast, the fermentation conditions were optimized, solving the problems of monotonous flavor and low efficiency of traditional fermentation, and achieving richer aroma and increased yield.
Patent Information
- Application Number
- CN202511024964.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-24
- Publication Date
- 2025-11-18
AI Technical Summary
Existing loquat wine fermentation methods result in a single flavor and insufficient aroma complexity, making it difficult to meet consumer demand. Furthermore, traditional natural fermentation has a long cycle, low yield, and difficulty in guaranteeing flavor and quality.
Loquat pulp was fermented using a mixture of Lactobacillus plantarum MX and yeast. Fermentation conditions, including initial sugar content, temperature, and inoculum ratio, were optimized, and the fermentation process was further optimized through response surface methodology.
It significantly increased the variety and relative content of volatile flavor compounds in loquat wine, enhanced the aroma richness and flavor complexity of the wine, and shortened the fermentation cycle.
Smart Images
Figure CN120966671A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of loquat wine fermentation, specifically to a type of Lactobacillus plantarum MX and its application in loquat wine fermentation. Background Technology
[0002] Loquat has a long history of cultivation and consumption in China, with large annual production and high quality. Its sweet and delicious taste and rich nutritional value make it popular among consumers. However, as a typical climacteric fruit, its post-harvest physiological characteristics make it extremely prone to softening and rotting. Furthermore, it is easily damaged mechanically during transportation and storage, making it difficult to preserve and easily diminishing its commercial value. Although deep processing of loquat into fruit wine can extend the industrial chain and increase added value, the flavor compounds (such as polyphenols and esters) in loquat wine are limited by the metabolic capacity of the fermentation strains, resulting in insufficient aroma complexity and failing to meet consumers' demands for a harmonious balance between fruit and wine aromas. In addition, there are currently few loquat wines on the market, and the brewing methods are traditional. Most are naturally fermented loquat wines, with long fermentation cycles and low yields, making it difficult to guarantee flavor and quality. Some are fermented with commercial yeast, resulting in ordinary and monotonous flavors. The aroma quality of the wine is a crucial factor determining its overall quality and consumer purchasing intentions. Therefore, improving the flavor of loquat wine is of great significance for enhancing the quality of loquat wine products and increasing their added value. Summary of the Invention
[0003] This invention provides a *Lactobacillus plantarum* MX and its application in loquat wine fermentation.
[0004] The technical solution of this invention is:
[0005] This invention provides a novel strain—Lactobacillus plantarum MX, deposited at the China General Microbiological Culture Collection Center (CGMCC), accession number: CGMCC No. 34697, deposit date: May 28, 2025, address: No. 3, No. 1 Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences, 100101, China.
[0006] The application of *Lactobacillus plantarum* MX in loquat wine fermentation specifically includes:
[0007] Lactobacillus plantarum MX and yeast were inoculated into loquat pulp and fermented. The flavor was evaluated after fermentation.
[0008] The inoculation ratio of yeast to Lactobacillus plantarum MX is 1.2 to 1.4:1, with the most preferred ratio being 1.25:1.
[0009] The initial sugar content of the loquat pulp is 22.5-23.5°Bx, with 23°Bx being the most preferred.
[0010] The fermentation temperature is 27.5–28.5°C, with 28°C being the most preferred.
[0011] The fermentation temperature is 7 to 10 days, with the most preferred temperature being 9 days.
[0012] Compared with the prior art, the present invention has the following advantages:
[0013] Approximately 20 volatile flavor compounds were detected in naturally fermented loquat wine ZR. The main volatile flavor components in naturally fermented loquat wine ZR are ethanol, ethyl acetate, acetic acid, isoamyl acetate, phenethyl acetate, phenylethanol, isoamyl alcohol, nonanoic acid, and isobutyric acid.
[0014] The loquat wine MX fermented using the *Lactobacillus plantarum* MX mixed culture of this invention showed approximately 30 volatile flavor compounds, indicating that MX mixed culture fermentation can increase the variety of volatile flavor compounds in loquat wine. The main volatile flavor components in the mixed-fermented loquat wine MX are ethanol, isoamyl alcohol, phenethyl alcohol, ethyl acetate, phenethyl acetate, 2-methylbutyric acid, ethyl 2-methylbutyrate, ethyl benzoate, isobutanol, acetic acid, and 3-hydroxy-2-butanone, etc. Unlike the loquat wines of the ZR and PP4X groups, the MX group loquat wine produced a wider variety and relatively higher content of other esters and other substances. For example, ethyl 2-methylbutyrate may contribute fruity and lipid aromas, while 3-hydroxy-2-butanone (acetoin) may add sweet or roasted aromas. These components contribute to a richer and more complex aroma in the MX group loquat wine. The above results indicate that loquat wine fermented with Lactobacillus plantarum has a richer volatile aroma composition than loquat wine fermented naturally, and can generate more esters and other substances, thus enriching the flavor of the fruit wine. Attached Figure Description
[0015] Figure 1 A flowchart of the loquat wine fermentation process;
[0016] Figure 2 The growth curve of MX;
[0017] Figure 3 The graph shows the effect of sugar content on MX growth;
[0018] Figure 4 The graph shows the effect of pH on MX growth;
[0019] Figure 5 The graph shows the effect of alcohol content on MX growth.
[0020] Figure 6 The graph shows the effect of fermentation temperature on loquat wine.
[0021] Figure 7 The graph shows the effect of fermentation time on loquat wine.
[0022] Figure 8 The graph shows the effect of initial sugar content on loquat wine.
[0023] Figure 9 The graph shows the effect of inoculation ratio on loquat wine.
[0024] Figure 10 The response surface plot shows the effect of the interaction of various factors on sensory ratings.
[0025] Figure 11 This is a cluster diagram of metabolites. Detailed Implementation
[0026] method:
[0027] Sugar tolerance test: The sugar content of MRS liquid medium was adjusted to 17°Bx, 20°Bx, 23°Bx, 26°Bx and 29°Bx using sucrose as raw material. The test strains were then inoculated at a 2% inoculum and cultured in a constant temperature incubator at 37℃. The growth of the strains was recorded.
[0028] Acid tolerance test: The pH of YPD liquid culture medium was adjusted to 2, 2.5, 3, 3.5 and 4 using trifluoroacetic acid as raw material. The test strains were then inoculated at a 2% inoculum and cultured in a 37℃ constant temperature incubator. The growth of the strains was recorded.
[0029] Alcohol tolerance test: The volume fraction of anhydrous ethanol in YPD liquid culture medium was adjusted to 10%, 12%, 14%, 16%, and 18% respectively. The test strains were then inoculated at a 2% inoculum and cultured in a constant temperature incubator at 37℃. The growth of the strains was recorded.
[0030] Flavor test of mixed fermentation with Lactobacillus plantarum: Five strains of Lactobacillus plantarum were mixed with screened yeast for fermentation. Lactobacillus plantarum and yeast were inoculated into loquat pulp at a 1:1 ratio and fermented at 23°Bx for 7 days. Flavor was evaluated after fermentation.
[0031] 3.2.1 Fermentation process flow
[0032] The fermentation process of loquat wine can be found here. Figure 1As shown. Specific operation and key points: Select fresh, intact loquats as raw material, wash and drain them. Remove the pits from the loquats, cut them into small pieces, and soak them in a 0.5% ascorbic acid and 0.5% sodium citrate solution for color preservation. Mix the loquats with sterile water in a 3:1 ratio and pulp. Add 120 mg / kg of pectinase to the pulp and enzymatically hydrolyze it in a 38℃ water bath for 3 hours, then inactivate the enzyme by heat treatment at 80℃ for 5 minutes. Add activated yeast to the treated pulp, add white sugar to adjust the total sugar concentration in the pulp, and then ferment the loquat wine. During fermentation, control the fermentation temperature at around 28℃, and aerate and stir every 12 hours. After 7 days of fermentation, separate the new wine using centrifugation (10000 rpm, 10 minutes), collect the supernatant, clarify and sterilize it, and then sample it and store it at 4℃ for later use.
[0033] 3.2.2 Single-factor experimental design
[0034] (1) Fermentation temperature
[0035] After the loquat pulp was mashed, the initial sugar content of the loquat pulp was adjusted to 23°Bx. 0.5 g / L of starter culture was inoculated, and the pulp was placed in constant temperature incubators at 19℃, 22℃, 25℃, 28℃, and 31℃ respectively. Samples were taken on the seventh day of fermentation, and the alcohol content of the fermented wine was tested. Sensory evaluation was conducted to explore the effect of different temperatures on the quality of loquat wine.
[0036] (2) Fermentation time
[0037] After the loquat pulp was mashed, the initial sugar content of the loquat pulp was adjusted to 23°Bx. 0.5 g / L of starter culture was inoculated, and the pulp was placed in a constant temperature incubator at 28°C. Samples were taken on days 3, 5, 7, 9, and 11 of fermentation to test the alcohol content of the fermented wine and conduct sensory evaluations to explore the impact of different fermentation times on the quality of loquat wine.
[0038] (3) Initial sugar content
[0039] After the loquat pulp was mashed, the initial sugar content of the loquat pulp was adjusted to 18°Bx, 20°Bx, 22°Bx, 24°Bx, and 26°Bx, respectively. Then, 0.5 g / L of inoculum was inoculated and placed in a constant temperature incubator at 28°C. Samples were taken on the 7th day of fermentation, and the alcohol content of the fermented wine was tested. Sensory evaluation was carried out to explore the effect of different initial sugar contents on the quality of loquat wine.
[0040] (4) Yeast inoculation amount
[0041] After the loquat pulp was mashed, the initial sugar content of the loquat pulp was adjusted to 23°Bx. Microbial inoculation was performed at concentrations of 0.1 g / L, 0.3 g / L, 0.5 g / L, 0.7 g / L, and 0.9 g / L, respectively. The mixture was then placed in a constant temperature incubator at 28°C. On the 7th day of fermentation, the alcohol content of the fermented wine was measured, and sensory evaluation was conducted to investigate the effect of different yeast inoculation amounts on the quality of the loquat wine.
[0042] (5) Inoculation ratio
[0043] After the loquat pulp was mashed, the initial sugar content of the loquat pulp was adjusted to 23°Bx. 0.5 g / L of microbial culture was then inoculated, with the ratio of yeast to Lactobacillus plantarum controlled at 3:1, 2:1, 1:1, 1:2, and 1:3, respectively. The mixture was placed in a constant temperature incubator at 28°C. Samples were taken on the seventh day of fermentation, and the alcohol content of the fermented wine was tested. Sensory evaluation was conducted to explore the influence of different inoculation ratios on the quality of loquat wine.
[0044] 3.2.3 Determination of alcohol content
[0045] According to GB / T 15038-2006, the alcohol content of loquat wine is determined using an alcohol meter. Clean the alcohol meter and thermometer, checking for damage and ensuring the graduations are clear. Take an appropriate amount of the loquat wine to be tested (the sample needs to be distilled beforehand to remove non-volatile substances) into a graduated cylinder, avoiding the formation of air bubbles. Slowly place the alcohol meter into the loquat wine in the graduated cylinder. After it stabilizes, read the alcohol meter reading and simultaneously read the thermometer reading. Based on the thermometer and alcohol meter readings, consult the alcohol meter temperature-concentration conversion table to perform temperature correction on the measurement results, obtaining the accurate alcohol content.
[0046] 3.2.4 Sensory evaluation
[0047] Ten food professionals with sensory evaluation experience were selected to conduct a sensory evaluation of the loquat wine. The evaluation was based on three indicators: color and appearance, aroma, and typicality. The maximum score was 100 points, and the average score was taken. The sensory evaluation scoring criteria for loquat wine are shown in Table 1.
[0048] Table 1. Sensory Evaluation Scoring Criteria for Loquat Wine
[0049]
[0050] 3.2.5 Response Surface Design
[0051] Based on the single-factor experiments, three influencing factors were selected: fermentation temperature (°C) (A), initial sugar content (°Bx) (B), and inoculum ratio (C). Sensory scores were used as response values, and response surface experiments were designed using the Box-Behnken central composite design principle. The experimental factors and level codes are shown in Table 2.
[0052] Table 2. Response Surface Experiment Factor Level Table
[0053]
[0054] result
[0055] 1. Selection of Lactobacillus plantarum
[0056] Five strains of *Lactobacillus plantarum* were mixed with selected yeasts for fermentation. Sensory evaluations were then conducted, and the results are shown in Table 3. The loquat wine fermented with YX1 and Mb5 had a lower alcohol content, a weaker aroma and fruitiness, and a sour taste. While the loquat wine fermented with MU2 had a pronounced aroma, its strong sourness masked the fruitiness. The loquat wine fermented with MX and MT had better aroma and fruitiness. However, compared to the other strains, the loquat wine fermented with MX had a distinct aroma and a milder fruitiness. Therefore, MX was selected as the *Lactobacillus plantarum* strain for subsequent fermentation.
[0057] Table 3 Flavor profile of Lactobacillus plantarum mixed fermentation
[0058]
[0059] 2. Growth curve of the strain
[0060] The growth curve of Lactobacillus plantarum MX is shown in the figure. Figure 2 During the first 0-6 hours of cultivation, the strain is in the lag phase. After 6 hours, it enters the logarithmic growth phase, and the cell count increases exponentially. After 20 hours, the strain enters the stationary phase, at which point the cell count reaches its peak and the growth rate slows down. Therefore, 20 hours of cultivation is optimal for preparing *Lactobacillus plantarum* MX seed culture. At this time, the number of MX cells in the culture is considerable and stable, providing a high-quality inoculum for subsequent fermentation and quickly establishing a numerical advantage, ensuring efficient and stable fermentation.
[0061] 2.3.5 Tolerance of the strain
[0062] (1) Sugar tolerance
[0063] This invention compares the viable cell counts of *Lactobacillus plantarum* MX at sugar concentrations of 17°Bx, 20°Bx, 23°Bx, 26°Bx, and 29°Bx. Figure 3 It can be seen that under sugar concentration conditions of 18-26°Bx and 17-29°Bx, the OD value of *Lactobacillus plantarum* MX decreases with increasing sugar concentration. Furthermore, the OD600 of MX decreases sharply at a sugar concentration of 29°Bx, indicating that the growth of MX is significantly inhibited at this point. However, some MX can still grow under these high sugar concentration conditions, indicating that *Lactobacillus plantarum* MX has a certain sugar tolerance.
[0064] (2) Acid resistance
[0065] This invention compares the viable cell counts of *Lactobacillus plantarum* MX under pH conditions of 4, 3.5, 3, 2.5, and 2. (From...) Figure 4 It can be seen that when the pH is between 2 and 4, the OD600 of *Lactobacillus plantarum* MX mainly decreases with decreasing pH. The OD600 value of MX reaches its maximum at pH 4, while it decreases sharply below pH 3, at which point the growth of MX is significantly inhibited. Therefore, within this pH range, the optimal pH for the growth of *Lactobacillus plantarum* MX should be around 4.
[0066] (3) Alcohol resistance
[0067] This invention compares the viable cell counts of *Lactobacillus plantarum* MX under conditions of ethanol volume fractions of 10%, 12%, 14%, 16%, and 18%. Figure 5 It can be seen that the OD value of *Lactobacillus plantarum* MX gradually decreases with increasing ethanol volume fraction. When the ethanol volume fraction is ≤14%, it has little effect on the growth of MX; when the ethanol volume fraction is higher than 14%, the number of MX cells decreases significantly, indicating that growth is inhibited to some extent; when the ethanol volume fraction is 18%, MX is still growing, which shows that it has a strong tolerance to alcohol.
[0068] 3.3.1 Effect of fermentation temperature on loquat wine
[0069] The effects of different fermentation temperatures on the alcohol content and sensory scores of loquat wine are shown in the following results. Figure 6 As shown in the figure, within the temperature range of 19℃-31℃, the alcohol content and sensory evaluation of loquat wine increased with increasing temperature. The rate of increase in alcohol content slowed down at 28℃, reaching its maximum around 31℃. The sensory evaluation, however, peaked at 28℃ and then began to decline slightly. At lower temperatures, the growth and metabolic rates of yeast were lower, resulting in insufficient sugar conversion efficiency, higher residual sugar content, and lower alcohol content. Throughout the temperature range, the increase in alcohol content of loquat wine stemmed from the enhanced metabolic activity of yeast within a suitable temperature range; its glycolysis rate and ethanol synthesis efficiency increased with increasing temperature. The peak sensory evaluation occurred at 28℃, possibly because, within the 19℃-28℃ range, higher temperatures promoted the synthesis of aroma compounds such as esters, and at 28℃, the yeast's esterase activity was higher, resulting in a greater production of aroma compounds. Temperatures exceeding 28°C may lead to the accumulation of byproducts in loquat wine. For example, excessive production of higher alcohols may result in a spicy or bitter taste, or it may lead to the loss of volatile substances and reduce the aroma intensity.
[0070] Taking into account the alcohol content and sensory scores of the loquat wine, fermentation temperatures of 25℃, 28℃, and 31℃ were selected for the next step of the response surface methodology experiment.
[0071] 3.3.2 Effect of fermentation time on loquat wine
[0072] The effects of different fermentation times on the alcohol content and sensory scores of loquat wine are shown in the following results. Figure 7 As shown in the graph, both the alcohol content and sensory evaluation of loquat wine increase over time, but the rate of increase slows down in the later stages. In the early stages of fermentation, the yeast is in its logarithmic growth phase, multiplying rapidly and converting sugar into alcohol with the highest efficiency, resulting in a significant increase in alcohol content. Simultaneously, the abundant aroma compounds produced in the early stages contribute to a rapid improvement in sensory scores. However, as sugar content decreases and alcohol concentration increases, yeast activity is inhibited, leading to a slower increase in alcohol content. Furthermore, the production of flavor compounds decreases, potentially causing a deterioration in flavor.
[0073] Taking into account fermentation alcohol content and sensory evaluation, as well as time cost, a fermentation time of 9 days was selected as the optimal fermentation time.
[0074] 3.3.3 Effect of initial sugar content on loquat wine
[0075] The effects of different initial sugar contents on the alcohol content and sensory scores of loquat wine are shown in the following results. Figure 8 As shown in the figure, the alcohol content of loquat wine initially increases and then decreases with increasing initial sugar content. The alcohol content reaches its highest value at 26°Bx, and then decreases when the sugar content continues to rise to 29°Bx. Sensory scores also show a similar trend of first increasing and then decreasing with changes in initial sugar content. From 17°Bx to 26°Bx, the sensory score gradually increases, reaching a peak at 26°Bx. When the sugar content increases to 29°Bx, the sensory score decreases. At lower sugar contents, yeast focuses on basal metabolism, producing less ethanol and volatile substances. Increasing the initial sugar content provides yeast with sufficient fermentable sugars, significantly increasing ethanol yield. However, excessively high initial sugar contents can lead to abnormal yeast metabolism, producing too much higher alcohols and volatile acids, which are undesirable flavor compounds and affect the flavor and quality of the fruit wine.
[0076] Taking into account the alcohol content and sensory evaluation of loquat wine, initial sugar contents of 20°Bx, 23°Bx, and 26°Bx were selected for the next step of response surface methodology.
[0077] 3.3.5 Effect of inoculum ratio on loquat wine
[0078] The effects of different inoculation ratios of yeasts and *Lactobacillus plantarum* on the alcohol content and sensory evaluation of loquat wine are shown in the following results. Figure 9As shown in the figure, the alcohol content of loquat wine initially increased and then decreased with varying inoculation ratios, with relatively small increases and decreases, reaching a peak at an inoculation ratio of 2:1. The relative decrease in yeast and the relative increase in Lactobacillus plantarum may have led to a reduction in the efficiency of ethanol conversion. Sensory scores also showed an initial increase followed by a decrease with varying inoculation ratios. Sensory scores were higher at 2:1 and 1:1, but decreased slightly after decreasing to 1:2, possibly due to undesirable flavors produced by Lactobacillus plantarum affecting the sensory scores.
[0079] Based on a comprehensive consideration of fermentation alcohol content and sensory evaluation, response surface methodology experiments were conducted using yeast and Lactobacillus plantarum inoculation ratios of 2:1, 1:1, and 1:2.
[0080] 3.3.6 Results of Response Surface Optimization Experiment
[0081] Based on the results of the single-factor experiments, a Box-Bohnken central composite design experiment was conducted, with fermentation temperature (A), initial sugar content (B), and inoculum ratio (C) as independent variables and sensory score (Y) as the response value. A three-factor, three-level response surface analysis was performed, and the experimental results are shown in Table 4.
[0082] Table 4. Experimental results of response surface optimization
[0083]
[0084] Table 4. Experimental results of response surface optimization (continued list)
[0085]
[0086] Using Design Expert 13 software, a quadratic regression equation was fitted to the data in Table 4, yielding a quadratic multinomial regression equation for sensory score (Y) on fermentation temperature (°C) (A), initial sugar content (°Bx) (B), and inoculum ratio (C): Y = -1125.22 + 44.5569A + 50.7028B - 3.97222C + 0.486111AB - 1.33333AC +
[0087] 2.94444BC-0.966667A 2 -1.45278B 2 -10.1333C 2 .
[0088] Table 5 shows that the analysis of variance results indicate that the obtained regression model is highly significant (P<0.01), and the lack-of-fit term is not significant (P>0.05), proving that the obtained model can fully fit the experimental data, the analysis is reliable, and it can predict the experimental values well. The linear term B has a significant effect on sensory scores (P<0.05), while A and C have no significant effect. The interaction term AB has a significant effect on sensory scores (P<0.05), AC has no significant effect, and BC has a highly significant effect (P<0.01). The quadratic terms A2, B2, and C2 all have highly significant effects on sensory scores (P<0.01). The combined results show that the order of influence of the three factors on the sensory scores of loquat wine is: initial sugar content > inoculum ratio > fermentation temperature.
[0089] Table 5. Analysis of Variance in Response Surface Experiments
[0090]
[0091] Table 5. Analysis of variance of response surface experiment (continued list)
[0092]
[0093] Note: * indicates a significant difference; ** indicates an extremely significant difference.
[0094] 3.3.7 Response Surface Optimization Experimental Analysis
[0095] Response surface methodology is a three-dimensional curve that reflects the degree of influence of various factors on the response outcome. It can effectively reflect the intensity of interactions between various factors.
[0096] Interactive analysis of three factors influencing the sensory evaluation of loquat wine was conducted using Design Expert 13 software. The response surface and contour results are shown below. Figure 10 As shown in the figure, the contour lines of AB, AC, and BC are elliptical, and their response surface plots have a slope, indicating that there are interactions between the pairs of factors. The contour lines for fermentation temperature (°C) (A) and initial sugar content (°Bx) (B) are more elliptical, and the response surface plots are steeper, indicating that the interaction between AB has a significant impact on sensory scores. The contour lines for initial sugar content (°Bx) (B) and inoculum ratio (C) are elliptical, and the response surface plots are steep, indicating that the interaction between BC has a highly significant impact on sensory scores. The surfaces for fermentation temperature (°C) (A) and inoculum ratio (C) are less steep than those for AB and BC, also indicating that the interaction between AC has a smaller impact on sensory scores than that between AB and BC. The analysis of the response surface plots and contour lines is consistent with the results of the analysis of variance.
[0097] 3.3.8 Optimal Fermentation Process and Validation
[0098] The results of the response surface methodology (RSM) experiment were analyzed using Design-Expert 13 software. Through regression equation optimization, the optimal fermentation parameters for loquat wine were determined to be: fermentation temperature 28.01℃, initial sugar content 23.53°Bx, and inoculum ratio 1.38. Under these parameters, the predicted theoretical sensory score was 92.78. Based on actual conditions, the parameters were appropriately improved to: fermentation temperature 28℃, initial sugar content 23°Bx, and inoculum ratio 1.25. Under these conditions, three replicate experiments were conducted, and the resulting sensory score for loquat wine was 91.5, which is close to the predicted value. Therefore, the RSM optimization of the fermentation parameters for loquat wine is reliable, and the model can provide a good prediction of the relationship between the fermentation process and sensory score of loquat wine.
[0099] 4.3.2 Determination of volatile flavor compounds
[0100] Although electronic nose analysis showed significant differences in the aroma compounds of naturally fermented loquat wine ZR and mixed-culture fermented loquat wine MX, further analysis of their aroma compounds is still needed to gain a detailed understanding of the volatile flavor compounds in loquat wine.
[0101] GC-MS analysis of the three groups of loquat wines identified over 70 volatile compounds, which were classified into seven categories based on their chemical structure: alcohols, acids, aldehydes, hydrocarbons, esters, ketones, and others. Approximately 20 volatile flavor compounds were detected in the naturally fermented loquat wine ZR, while approximately 30 were detected in the mixed-culture fermented loquat wine MX. This indicates that mixed-culture fermentation in MX can increase the variety of volatile flavor compounds in loquat wine. The relative contents of the main volatile aroma compounds are shown in Table 6. The main volatile flavor components in the naturally fermented loquat wine ZR were ethanol, ethyl acetate, acetic acid, isoamyl acetate, phenethyl acetate, phenylethanol, isoamyl alcohol, nonanoic acid, and isobutyric acid. The main volatile flavor components in the mixed-fermentation loquat wine MX are ethanol, isoamyl alcohol, phenylethanol, ethyl acetate, phenethyl acetate, 2-methylbutyric acid, ethyl 2-methylbutyrate, ethyl benzoate, isobutanol, acetic acid, and 3-hydroxy-2-butanone. Unlike the loquat wines in the ZR and PP4X groups, the MX group produced a wider variety and higher relative abundance of other esters and other substances. For example, ethyl 2-methylbutyrate may contribute fruity and lipid aromas, while 3-hydroxy-2-butanone (acetoin) may add sweet or roasted aromas. These components contribute to a richer and more complex aroma profile in the MX group. These results indicate that loquat wine fermented with Lactobacillus plantarum has a richer volatile aroma composition than naturally fermented loquat wine, producing more esters and other substances, thus enriching the flavor of the fruit wine. This is similar to the findings of many studies on mixed-fermentation fruit wines.
[0102] Table 6. Main volatile compounds in loquat wine
[0103]
[0104] 4.3.2 Volatile Metabolomics Analysis
[0105] Volatile metabolomics was used to analyze loquat wine. Principal component analysis showed good separation of loquat wine samples, low correlation between samples, and significant differences in volatile aroma components. Figure 11 As shown, by comparing the differential metabolites of loquat wine, it was found that the MX group showed a greater upward trend in esters, fatty acids, and ketones compared to the ZR group. These upregulation and downregulation of differential metabolites may be the reason for the differences in flavor among the three groups of loquat wine. KEGG metabolic pathway enrichment analysis showed that, compared to the ZR group, the MX group mainly improved the flavor of loquat wine through ethylbenzene degradation, monoterpene biosynthesis, caprolactam degradation, pyruvate metabolism, butyrate metabolism, sulfur metabolism, and α-linolenic acid metabolism. These results indicate that the addition of *Lactobacillus plantarum* MX is beneficial to the degradation of harmful substances such as xylene and ethylbenzene in loquat wine, and also has a certain effect on improving the flavor of loquat wine.
Claims
1. A type of Lactobacillus plantarum MX, characterized in that, It is deposited at the China General Microbiological Culture Collection Center, accession number: CGMCC No. 34697.
2. The application of *Lactobacillus plantarum* MX as described in claim 1 in loquat wine fermentation.
3. The application as described in claim 2, characterized in that, Specifically, it includes: Lactobacillus plantarum MX and yeast were inoculated into loquat pulp and fermented.
4. The application as described in claim 3, characterized in that, The inoculation ratio of yeast to Lactobacillus plantarum MX is 1.2 to 1.4:
1.
5. The application as described in claim 3, characterized in that, The initial sugar content of the loquat pulp is 22.5–23.5°Bx.
6. The application as described in claim 3, characterized in that, The fermentation temperature is 27.5–28.5°C.
7. The application as described in claim 3, characterized in that, The fermentation temperature is 7 to 10 days.