Litchi fruit wine based on functional microorganism enhancement and preparation method thereof

Abstract

The invention relates to the technical field of fermented wine. The invention provides a microbial fermentation inoculant and litchi fruit wine prepared by using the microbial fermentation inoculant. By adding the microbial fermentation agent and optimizing related fermentation parameters, the expression of key enzyme activity can be better improved, the generation of fruity ester substances is promoted, the flavor of the lychee fruit wine is enhanced by shaping rich-level, coordinated and elegant characteristic flavor substances, and meanwhile, the alcohol yield can also be increased.

Description

Technical Field

[0001] The invention relates to the technical field of fermented wine, and in particular to a lychee wine enhanced by functional microorganisms and a preparation method thereof. Background Art

[0002] As a specialty fruit fermented wine, lychee wine has attracted much attention in the fruit wine market in recent years. However, the lychee wine industry is still facing many technical bottlenecks and quality problems. Existing lychee wines generally have problems such as low fermentation efficiency, unstable flavor, and short shelf life. Among them, the most prominent problem is the low alcohol content caused by insufficient conversion of reducing sugars, which not only affects product quality, but also causes waste of raw materials. This is mainly due to the special physical and chemical properties of lychee fruit and the complex composition of flavor substances, which brings unique challenges to the fermentation process.

[0003] From a process perspective, traditional fermentation methods often have difficulty coping with the complex interactions of high sugar content, special organic acid composition, and trace flavor substances in litchi juice. In particular, during the fermentation process, the osmotic stress caused by the high sugar content environment, the unique acid composition of different litchi varieties, and the fermentation inhibitors that some varieties may contain will affect the metabolic activity of yeast. In addition, the retention and conversion of litchi's unique aromatic substances during the fermentation process is also a difficulty, which is directly related to the flavor characteristics of the final product. In industrial production, the quality differences between different batches of raw materials, the instability of the fermentation process, and the attenuation of flavor during storage all pose challenges to standardized production. Although researchers have tried to solve these problems by optimizing yeast strains, improving fermentation processes, and adding nutrients, the lack of in-depth understanding of the evolution of key flavor substances during the fermentation process has made the effects of these improvement measures often less than ideal.

[0004] Therefore, from the perspective of flavor orientation, studying the fermentation characteristics of different strains and exploring their effects on the quality of fruit wine has important theoretical and practical significance for solving existing technical problems and improving product quality. This not only helps to establish a more scientific production process, but also provides new ideas for the development of differentiated lychee wine products. Summary of the invention

[0005] The purpose of the present invention is to provide a litchi wine, which can better promote the generation of fruity ester substances by adding a microbial fermentation agent composed of brewer's yeast and plant lactobacillus, shape rich and coordinated layers, enhance characteristic flavor substances and strengthen the flavor of the litchi wine.

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

[0007] The invention provides a microbial fermentation agent, which contains saccharomyces cerevisiae and lactobacillus plantarum in a volume ratio of 1.25:(1-1.5).

[0008] The invention provides a litchi wine, which is prepared by utilizing the microbial fermentation agent.

[0009] Preferably, the alcohol content of the litchi wine is 14-16.5% vol.

[0010] The present invention provides a method for preparing the lychee wine, comprising the following steps:

[0011] (1) mixing the pretreated litchi juice with pectinase for enzymolysis to obtain an enzymolysis solution;

[0012] (2) The enzymatic hydrolysate is mixed with the microbial fermentation agent of claim 1 and fermented to obtain the product.

[0013] Preferably, the ratio of the litchi juice and pectinase mixed in step (1) is (0.5-1.5) L: (180-230) mg.

[0014] Preferably, the enzymatic hydrolysis temperature in step (1) is 40-48°C, and the enzymatic hydrolysis time is 1.5-2.5h.

[0015] Preferably, the volume ratio of the enzymatic hydrolysate and the microbial fermentation agent in step (2) is 100:(1.5-3.5).

[0016] Preferably, the fermentation temperature in step (2) is 24-32° C., and the fermentation time is 8-13 days.

[0017] By adopting the above technical solution, the present invention has the following beneficial effects:

[0018] 1. In the technical solution of the present invention, by adding a microbial fermentation agent composed of brewer's yeast and Lactobacillus plantarum in a scientific ratio, it is helpful for the lactic acid fermentation of Lactobacillus plantarum and the alcohol and ester metabolism activities of yeast, jointly promoting the transformation of flavor precursor substances, promoting the generation of fruity ester substances, and shaping a fruit wine flavor with rich layers, coordinated and elegant; it can also significantly increase characteristic flavor substances such as isopentanol and phenylethanol.

[0019] 2. The addition of the microbial fermentation agent in the present invention in combination with scientific fermentation parameter conditions can not only enhance the flavor of litchi wine, but also significantly enrich metabolites such as trigonelline and L-malic acid, so that litchi wine has both health functions and can also increase alcohol production. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1To study the effects of different microbial fermentation inoculum inoculation amounts on the flavor and quality of litchi wine.

[0021] Figure 2 To study the effects of different fermentation temperatures on the flavor and quality of litchi wine;

[0022] Figure 3 To study the effects of different microbial fermentation agents on the volatile components of litchi wine obtained by fermentation.

[0023] Figure 4 To investigate the effects of different microbial fermentation agents on the flavor and quality of fermented litchi wine. DETAILED DESCRIPTION

[0024] The invention provides a microbial fermentation agent containing brewer's yeast and plant lactobacillus.

[0025] In the present invention, the saccharomyces cerevisiae is preferably saccharomyces cerevisiae CICC1398, and the Lactobacillus plantarum is preferably Lactobacillus plantarum CICC20022. The volume ratio of the saccharomyces cerevisiae to Lactobacillus plantarum in the present invention is preferably 1.25:(1-1.5), further preferably 1.25:(1.1-1.35), and further preferably 1.25:1.25.

[0026] In the present invention, the Lactobacillus plantarum CICC20022 can promote the occurrence of malic acid-lactic acid fermentation during the fermentation process, thereby improving the quality of fermented fruit wine. It contains genes encoding multiple enzymes such as β-glucosidase, which can enrich the volatile aroma components of fruit wine.

[0027] The invention provides a litchi wine, which is prepared by utilizing the above-mentioned microbial fermentation agent.

[0028] In the present invention, the alcohol content of the litchi wine is preferably 14-16.5% vol, and further preferably 15-16.3% vol.

[0029] The present invention provides a method for preparing the lychee wine, comprising the following steps:

[0030] (1) mixing the pretreated litchi juice with pectinase for enzymolysis to obtain an enzymolysis solution;

[0031] (2) The enzymatic hydrolysate is mixed with the microbial fermentation agent of claim 1 and fermented to obtain the product.

[0032] In the present invention, the selected lychees are pretreated to obtain lychee juice, and the pretreatment operation is preferably to wash the lychees, peel and de-seed them, and then squeeze the juice. The obtained lychee juice is then mixed with pectinase for enzymolysis to obtain an enzymolysis solution, and the ratio of the lychee juice to the pectinase is preferably (0.5-1.5) L: (180-230) mg, further preferably (0.8-1.3) L: (190-210) mg, and further preferably 1 L: 200 mg. The enzymolysis temperature in the present invention is preferably 40-48°C, further preferably 42-47°C, and further preferably 45°C; the enzymolysis time is preferably 1.5-2.5 h, further preferably 1.8-2.3 h, and further preferably 2 h.

[0033] In the present invention, the enzymatic hydrolysate obtained above is mixed with the microbial fermentation agent for fermentation to obtain the litchi wine. The volume ratio of the enzymatic hydrolysate to the microbial fermentation agent in the present invention is preferably 100:(1.5-3.5), further preferably 100:(2-3), and further preferably 100:2.5.

[0034] In the present invention, the initial pH value of the mixed fermentation of the enzymatic hydrolyzate and the microbial fermentation agent is preferably 4.7-5.2, further preferably 4.9-5.1, and further preferably 5; the initial reducing sugar content of the fermentation is preferably 160-200 g / L, further preferably 170-190 g / L, and further preferably 180 g / L.

[0035] In the present invention, the fermentation temperature is preferably 24-32°C, further preferably 26-30°C, and further preferably 28°C; the fermentation time is preferably 8-13d, further preferably 9-11d, and further preferably 10d.

[0036] 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.

[0037] Example 1

[0038] A microbial fermentation agent contains saccharomyces cerevisiae CICC1398 and lactobacillus plantarum CICC20022 in a volume ratio of 1.25:1.25.

[0039] Example 2

[0040] A microbial fermentation agent contains saccharomyces cerevisiae CICC1398 and lactobacillus plantarum CICC20022 in a volume ratio of 1.25:1.

[0041] Example 3

[0042] A microbial fermentation agent contains saccharomyces cerevisiae CICC1398 and lactobacillus plantarum CICC20022 in a volume ratio of 1.25:1.5.

[0043] Example 4

[0044] A litchi wine, the preparation steps are as follows:

[0045] (1) washing, peeling and removing the core of litchi, and squeezing the litchi juice to obtain litchi juice, then mixing the litchi juice with pectinase in a ratio of 1 L:200 mg, and performing enzymolysis at 45° C. for 2 h to obtain an enzymolysis solution;

[0046] (2) The obtained enzymatic hydrolysate was mixed with the microbial fermentation agent described in Example 1 at a volume ratio of 100:2.5, and after being mixed evenly, the mixture was fermented at 28° C. for 10 days to obtain 16.15% vol litchi wine.

[0047] Example 5

[0048] A litchi wine, the preparation steps are as follows:

[0049] (1) washing, peeling and removing the core of litchi, squeezing the litchi juice to obtain litchi juice, then mixing the litchi juice with pectinase in a ratio of 1.5 L:180 mg, and performing enzymolysis at 40° C. for 2.5 h to obtain an enzymolysis solution;

[0050] (2) The obtained enzymatic hydrolysate was mixed with the microbial fermentation agent described in Example 1 at a volume ratio of 100:1.5, and after being mixed evenly, the mixture was fermented at 24° C. for 13 days to obtain 15.5% vol litchi wine.

[0051] Example 6

[0052] A litchi wine, the preparation steps are as follows:

[0053] (1) washing, peeling and removing the core of litchi, squeezing the litchi juice to obtain litchi juice, then mixing the litchi juice with pectinase in a ratio of 0.5 L:230 mg, and performing enzymolysis at 48° C. for 1.5 h to obtain an enzymolysis solution;

[0054] (2) The obtained enzymatic hydrolysate was mixed with the microbial fermentation agent described in Example 1 at a volume ratio of 100:3.5, and after being mixed evenly, the mixture was fermented at 30° C. for 8 days to obtain 16.5% vol litchi wine.

[0055] Example 7

[0056] A litchi wine, the preparation steps are as follows:

[0057] (1) washing, peeling and removing the core of litchi, and squeezing the litchi juice to obtain litchi juice, then mixing the litchi juice with pectinase in a ratio of 1 L:200 mg, and performing enzymolysis at 45° C. for 2 h to obtain an enzymolysis solution;

[0058] (2) The obtained enzymatic hydrolysate was mixed with the microbial fermentation agent described in Example 2 at a volume ratio of 100:2.5, and after being mixed evenly, the mixture was fermented at 28° C. for 10 days to obtain 16.15% vol litchi wine.

[0059] Example 8

[0060] A litchi wine, the preparation steps are as follows:

[0061] (1) washing, peeling and removing the core of litchi, and squeezing the litchi juice to obtain litchi juice, then mixing the litchi juice with pectinase in a ratio of 1 L:200 mg, and performing enzymolysis at 45° C. for 2 h to obtain an enzymolysis solution;

[0062] (2) The obtained enzymatic hydrolysate was mixed with the microbial fermentation agent described in Example 3 at a volume ratio of 100:2.5, and after being mixed evenly, the mixture was fermented at 28° C. for 10 days to obtain 16.15% vol litchi wine.

[0063] Test Example 1

[0064] The litchis are washed, shelled and cored, and then squeezed to obtain litchi juice, and then pectinase is mixed with the litchi juice at a ratio of 200 mg / L, and enzymolysis is performed at 45°C for 2 hours, and then 2.5% (accounting for the volume percentage of the litchi juice) of a microbial fermentation agent (the ratio of brewer's yeast CICC1398 to lactobacillus plantarum CICC20022 is 1.25:1.25) is inoculated for mixed fermentation, the initial pH value of the fermentation is 5.0, the initial reducing sugar content is 180 g / L, the fermentation is performed under the condition of maintaining 28°C throughout the whole process, and the fermentation time is 10 days. (one)

[0066] Based on the above fermentation process, different microbial fermentation agent inoculation amount groups (1.5%, 2.0%, 2.5%, 3.0% and 3.5%) were set to compare the effects of different microbial fermentation agent inoculation amounts on the flavor and quality of litchi wine.

[0067] For alcohol content and total ester, please refer to GB / T 15038-2006 "General Analysis Methods for Grape and Fruit Wine"; for total acid, please refer to GB12456-2021 "Determination of Total Acid in Food".

[0068] Table 1 Litchi wine flavor evaluation table

[0069]

[0070] The appropriate amount of inoculation helps maintain the balanced activity of esterase, promotes the production of fruity esters, and creates a rich, coordinated and elegant fruit wine flavor. Figure 1 As shown in the figure, the flavor evaluation score was the highest when the inoculation amount was 2.5%, indicating the best quality; when the inoculation amount was greater than 2.5%, the competition between cells per unit volume intensified, resulting in a sharp decrease in available nutrients in the culture medium and an increase in acetic acid content. The excessive accumulation of acetic acid concentration will affect the sensory characteristics of fruit wine. A lower inoculation amount may impose greater environmental pressure on cells in the early stage of fermentation, thereby affecting their metabolic activity, especially the synthesis of higher alcohols, resulting in a decrease in the content of higher alcohols in the final product. Therefore, choosing an inoculation amount of 2.5% can further improve the flavor and quality of fruit wine. (two)

[0072] Based on the above fermentation process, different fermentation temperature groups (24°C, 26°C, 28°C, 30°C and 32°C) were set to study the yeast-related enzyme activities and yeast stress responses at different temperatures, and to compare the effects of different fermentation temperatures on the flavor and quality of litchi wine.

[0073] The results are as follows Figure 2 As shown in the figure, when the fermentation temperature is controlled at 28℃, the alcohol content of litchi wine reaches the highest, about 16%vol. At the same time, the flavor evaluation is also the highest at this temperature, showing the best sensory quality. The total acid of the 28℃ and 32℃ groups is significantly higher than that of the other three groups, and the total ester of the 24℃, 26℃, and 28℃ groups is significantly higher than that of the other two groups.

[0074] Fermentation temperature has a significant effect on yeast reproduction and its sugar metabolism pathway. At 28°C, the activity of key enzymes such as phosphofructokinase (PFK) and pyruvate kinase (PK) is optimally expressed, achieving an efficient balance with the proliferation and activity of yeast cells, thereby increasing alcohol production. In addition, changes in temperature can cause changes in the physiological state of yeast cells. For example, yeast cells under high or low temperature conditions may suffer from oxidative stress or osmotic stress, leading to changes in the intracellular environment such as pH and accumulation of metabolic waste. These changes will further affect the activity and gene expression of multiple enzymes in the cell, thereby interfering with the normal survival of the cell and the production of metabolites. When the fermentation temperature is 28°C, it can not only effectively increase alcohol production, but also significantly improve the flavor, while reducing physiological stress and maintaining the stability of cell metabolism. Therefore, 28°C is the optimal temperature for litchi wine fermentation. (three)

[0076] Based on the above fermentation process, the effects of different microbial fermentation agents on the volatile components in the fermented litchi wine were set. The groups included 2.5% Saccharomyces cerevisiae CICC1398 group, 1.25% Saccharomyces cerevisiae CICC1398+1.25% Lactobacillus plantarum CICC20022, 1.25% Saccharomyces cerevisiae CICC1398+1.25% Lactobacillus buchneri CGMCC1.15607, and 1.25% Saccharomyces cerevisiae CICC1398+1.25% Lactobacillus paracasei CGMCC1.12731.

[0077] The volatile components were detected as follows: 4 mL of sample was injected into a 15 mL headspace extraction bottle, and then 10 μL of internal standard (0.8775 g / L methyl octanoate) was added to the bottle. Then 2 g of NaCl was added to the bottle to promote the release of volatile components. After that, the sample was preheated at 50 ° C for 10 min. After the preheating was completed, the extraction head (DVB / CAR / PDMS 50 / 30 μm) was inserted into the headspace bottle and extracted for 40 min. After the extraction was completed, the extraction head was quickly inserted into the injection port of the GC-MS instrument for thermal desorption for 5 min for subsequent analysis.

[0078] Chromatographic conditions: starting temperature 35°C, maintained for 1 min, increased to 130°C at a rate of 5°C / min, maintained for 1 min, then increased to 180°C at 3°C / min, maintained for 1 min, and finally increased to 230°C at 8°C / min and maintained for 1 min.

[0079] Mass spectrometry conditions: ion source temperature was 230 °C, MS quadrupole temperature was 150 °C, solvent delay time was 3 min, and data acquisition mode was full scan mode.

[0080] The results are as follows Figure 3 As shown in the figure, through mixed bacteria fermentation, the characteristic flavor substances in litchi wine are significantly improved, and the concentrations of isopentanol, isobutanol, and phenylethanol are higher than those of single bacteria. Compared with single bacteria fermentation, the addition of Lactobacillus plantarum CICC20022 can significantly improve the improvement of characteristic flavor substances. The addition of Lactobacillus buchneri CGMCC1.15607 and Lactobacillus paracasei CGMCC1.12731 is also helpful for the improvement of flavor substances, but it is slightly weaker than Lactobacillus plantarum.

[0081] Furthermore, based on the settings of each group, the total acid, total ester, alcohol content and sensory score of the lychee wine prepared by each group were determined.

[0082] The results are as follows Figure 4Different mixed bacteria combinations have different effects on the total acid, total ester, alcohol content and sensory score of litchi wine. Among them, the indicators of brewer's yeast CICC1398 + Lactobacillus plantarum CICC20022 are relatively the best, with a total acid of 4.8g / L, a total ester of 3.65g / L, a sensory score of 90, and an alcohol content of 16.15%vol.

[0083] In summary, it can be seen that the addition of the microbial fermentation agent composed of brewer's yeast and Lactobacillus plantarum in the technical scheme of the present invention and the determination of scientific fermentation parameter conditions can better promote the production of fruity esters and enhance the characteristic flavor. Among them, the enhancement of characteristic flavors such as isopentanol and phenylethanol significantly improves the quality of fruit wine, and also enhances the flavor of litchi wine, creating a rich and coordinated taste.

[0084] 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 microbial fermentation agent, characterized in that: Contains Saccharomyces cerevisiae and Lactobacillus plantarum in a volume ratio of 1.25:(1-1.5).

2. A litchi wine, characterized in that: The method is prepared by using the microbial fermentation agent described in claim 1.

3. The lychee wine according to claim 2, characterized in that: The alcohol content of the lychee wine is 14-16.5% vol.

4. The method for preparing litchi wine according to claim 2 or 3, characterized in that: The steps include: (1) mixing the pretreated litchi juice with pectinase for enzymolysis to obtain an enzymolysis solution; (2) The enzymatic hydrolysate is mixed with the microbial fermentation agent of claim 1 and fermented to obtain the product.

5. The preparation method according to claim 2 or 3, characterized in that: The ratio of the litchi juice and pectinase mixed in step (1) is (0.5-1.5) L: (180-230) mg.

6. The preparation method according to claim 2 or 3, characterized in that: The temperature of the enzymolysis in step (1) is 40-48° C., and the time of the enzymolysis is 1.5-2.5 h.

7. The preparation method according to claim 2 or 3, characterized in that: The volume ratio of the enzymatic hydrolyzate and the microbial fermentation agent mixed in step (2) is 100:(1.5-3.5).

8. The preparation method according to claim 2 or 3, characterized in that: The fermentation temperature in step (2) is 24-32° C. and the fermentation time is 8-13 days.

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