Compound bacteria fermented fruit and vegetable marinade and preparation method thereof

Abstract

The invention discloses a compound bacteria fermented fruit and vegetable marinade and a preparation method thereof, and particularly relates to the technical field of fermentation engineering. The method comprises the following steps: firstly, adding a proper amount of water into raw materials rich in fermentable sugar, sulfur-containing flavored vegetables and prebiotic sources, and beating into paste to serve as fruit and vegetable-based bottom mud; inoculating lactic acid bacteria and saccharomycetes which are subjected to induction culture into the fruit and vegetable-based bottom mud, and performing aerobic fermentation and anaerobic fermentation to obtain a fermentation product; finally, adding common food additives into a fermentation product, performing low-temperature refrigeration and after-ripening, performing heat treatment at 85-95 DEG C for 15-30 seconds, killing viable bacteria, and stopping fermentation; and cooling to room temperature to obtain the compound bacteria fermented fruit and vegetable marinade. According to the method disclosed by the invention, lactic acid bacteria (lactobacillus plantarum and lactobacillus fermentum) and saccharomycetes (Wickerhamomyces anomalus) are subjected to induced culture respectively, so that the lactic acid bacteria and the saccharomycetes are subjected to adaptive pre-domestication based on interaction signals, and the ecological compatibility and metabolism synergistic efficiency of the lactic acid bacteria and the saccharomycetes in a co-fermentation system are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of fermentation engineering technology, specifically to a compound microbial fermented fruit and vegetable pickling sauce and its preparation method. Background Technology

[0002] With the increasing demand from consumers for healthy and natural foods, the traditional practice of using large amounts of chemical additives (such as phosphates, monosodium glutamate, and nitrites) in meat processing is facing challenges. Improving the quality, flavor, and safety of meat products using microbial fermentation technology has become an important research direction in the meat processing industry. Lactic acid bacteria, as a recognized safe strain, are widely used in the development of fermented meat products due to their acid-producing, antibacterial, and texture-improving properties.

[0003] Chinese patent CN113397120A discloses a method for preparing low-temperature processed meat products using lactic acid bacteria fermentation broth. The method involves culturing lactic acid bacteria such as *Lactobacillus plantarum* and *Lactobacillus rhamnosus* in vitro, then adding the fermentation broth (containing organic acids, small peptides, and other metabolites) at a ratio of 5-15% to a marinating solution. The meat is then marinated for a short period (6-10 hours) at 4-10℃. This method improves the textural properties of the meat products to some extent and has a slight deodorizing effect. However, it only uses a non-live fermentation liquid of a single type of lactic acid bacteria, lacking the synergistic effect of other functional microorganisms such as yeast. This results in a limited variety of flavor substances, making it difficult to form a rich and pleasant complex aroma (such as fruit aroma, ester aroma, and alcohol aroma). Moreover, as a passively added additive, the fermentation liquid cannot dynamically respond to changes in the microenvironment of the ingredients during the pickling process, and its control ability is limited. At the same time, its pickling system still relies on additives such as soy sauce and commercially available compound marinades, making it difficult to achieve a truly "zero-additive" or all-natural formula. Finally, due to the lack of targeted control of the microbial community, the flavor consistency between batches is poor, and it is impossible to flexibly customize popular flavors such as honey, black pepper, and teriyaki according to market demand.

[0004] Therefore, there is an urgent need to develop a novel fermented marinade preparation method based on the synergistic effects of multiple microorganisms, using natural fruits and vegetables as a matrix, and possessing flavor designability and functional integration. This method can fully leverage the metabolic potential of microorganisms and meet the diverse consumer demands for clean labels, healthy nutrition, and varied flavors. Summary of the Invention

[0005] Therefore, the present invention provides a compound microbial fermented fruit and vegetable pickle and its preparation method to solve the problems in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: According to one aspect of the present invention, a method for preparing a compound microbial fermented fruit and vegetable pickle includes: Step 1: Preparation of Fruit and Vegetable Substrate Add an appropriate amount of water to fruits rich in fermentable sugars, sulfur-containing flavored vegetables, and prebiotic-based ingredients, blend them into a puree, and use it as a fruit and vegetable base puree. Step 2, Fermentation of Compound Microbial Strains Lactic acid bacteria and yeast, after induction culture, were inoculated into fruit and vegetable substrate mud, and fermented aerobically first and then anaerobically to obtain fermentation products. Step 3, Flavor blending Common food additives are added to the fermentation products, and the mixture is then refrigerated at low temperature for further ripening. A heat treatment at 85-95℃ for 15-30 seconds is then applied to kill live bacteria and terminate the fermentation. The mixture is then cooled to room temperature to obtain the compound bacteria fermented fruit and vegetable pickle.

[0007] Furthermore, in step one, the fruit rich in fermentable sugars is selected from one or more of apples, pears, and pineapples; the sulfur-containing flavor vegetables are selected from one or more of onions, leeks, and garlic; the prebiotic source is selected from pretreated Jerusalem artichokes and / or chicory roots; the Jerusalem artichoke pretreatment method includes heating the Jerusalem artichokes in a water bath at 50-55℃ for 10-15 minutes before use. The purpose is to soften the tissue, facilitate mashing, and inhibit browning in conjunction with the subsequent fermentation system.

[0008] In step one, the ratio of apple, onion, garlic and pretreated Jerusalem artichoke is (40-60):(20-40):(10-30):(5-15), preferably 50:30:20:10; the amount of water added is 10-30% of the total solids; the particle size of the fruit and vegetable substrate mud is ≤200μm and the viscosity is 2000-8000mPa·s (25℃).

[0009] Furthermore, in step two, the lactic acid bacteria are Lactobacillus plantarum and Lactobacillus fermentum; the yeast is Wickham's abnormal yeast, wherein both the lactic acid bacteria and the yeast are used after induction culture.

[0010] Furthermore, the induction culture of lactic acid bacteria includes mixing Lactobacillus plantarum and Lactobacillus fermentum in a certain proportion and inoculating them into a lactic acid bacteria induction medium, anaerobic culture for 18-24 h, taking the culture at the end of the logarithmic phase, and transferring it at an inoculation rate of 2% into a fresh induction medium with a pH reduced by 0.1-0.2 units, and continuously subculturing for 5-7 generations until the initial pH of the medium is reduced to 5.0, thus obtaining the inducible lactic acid bacteria.

[0011] Furthermore, the induction medium is MRS liquid medium with added yeast extract and ethanol. The initial pH of the lactic acid bacteria induction medium is 6.0. A new type of medium is prepared for every 0.1-0.2 units of pH decrease until the pH drops to 5.0.

[0012] In the lactic acid bacteria induction culture medium, the amount of yeast extract added is 0.3-0.8% (w / v), and the amount of ethanol added is 0.5-1.5% (v / v).

[0013] Although MRS medium contains yeast extract, the addition of 0.3-0.8% (w / v) yeast extract is intended to mimic the high concentration of water-soluble nutrients released by yeast autolysis in a co-fermentation system, in conjunction with 0.5-1.5% (v / v) ethanol stress, to selectively screen lactic acid bacteria subgroups resistant to combined stress.

[0014] Furthermore, the induction culture of the yeast includes inoculating *Wickhamia esculenta* into a yeast induction medium, culturing it under microaerobic conditions for 24-28 hours, maintaining the acidic pressure and precursor amino acid concentration of the medium throughout, and continuously subculturing it for 5-7 generations to obtain the induced yeast.

[0015] Furthermore, the yeast induction medium is a mixture of lactic acid and acetic acid, added to YPD liquid medium, and then phenylalanine and leucine are added, with the pH of the medium adjusted to acidity.

[0016] In the yeast induction medium, the total volume concentration of lactic acid and acetic acid is 1.0-2.0% (v / v), and the pH is adjusted to 4.0-4.5; the addition amounts of phenylalanine and leucine are 0.05-0.15% (w / v) and 0.05-0.12% (w / v), respectively.

[0017] Furthermore, in step two, the ratio of live bacteria added to lactic acid bacteria and yeast is 100-10:1.

[0018] Furthermore, in step two, the aerobic fermentation followed by anaerobic fermentation includes aerobic fermentation at 28-30℃ for 18-24 hours without sealing and stirring. After fermentation, the temperature is raised to 35-37℃, sealed, and allowed to stand for anaerobic fermentation for 48-72 hours. During the aerobic fermentation stage, low-speed stirring at 50-150 rpm is used.

[0019] The endpoint of anaerobic fermentation is: the pH value of the fermentation system is stable in the range of 3.8-4.2 and the fluctuation does not exceed 0.1 for 12 hours; and / or the consumption rate of the main sugars (fructose, glucose) exceeds 90%.

[0020] In step three, before heat treatment, the flavor-blended mixture is processed by a colloid mill or a high-pressure homogenizer to make the particle size ≤50μm, forming a uniform sauce.

[0021] Microaerobic conditions: Erlenmeyer flasks containing induction medium and yeast are sealed with a breathable membrane and placed in a 28°C static incubator. The liquid-to-gas ratio is greater than 1:5 (during the initial startup phase, gentle stirring followed by shallow settling); slow air diffusion through the membrane is allowed, but far less efficient than the oxygen transfer of a shaker. The larger space above the liquid surface provides an oxygen buffer. The food additive of this invention is selected from one or more of the following: natural honey, maltose, salt, ginger powder, ground black pepper, mushroom powder, and onion powder.

[0022] The compound microbial fermented fruit and vegetable pickling sauce provided by one aspect of the present invention is prepared by the above-described method.

[0023] The present invention has the following advantages: This invention significantly improves the ecological compatibility and metabolic synergy of lactic acid bacteria (Lactobacillus plantarum + Lactobacillus fermentum) and yeast (Wickham's yeast anomala) in co-fermentation systems by inducing their culture separately, enabling them to undergo adaptive pre-acclimation based on interaction signals. After induction with an acidic medium containing leucine and phenylalanine, the yeast exhibits highly selective synthesis of target esters (such as isoamyl acetate and phenylethyl acetate); the lactic acid bacteria, after acclimation to gradient acidification and microethanol stress, demonstrate more stable acid production.

[0024] The entire system of this invention is based on natural fruits and vegetables such as apples, onions, garlic, and Jerusalem artichokes, with only common kitchen ingredients such as salt, honey, and spices added. It does not use MSG, I+G, synthetic flavorings, or chemical preservatives at all. The ingredient list is simple and transparent, which is in line with the trend of high-end consumption. Detailed Implementation

[0025] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Wickerhamomyces anomalus CICC 32951; Lactobacillus plantarum CICC 25125; Lactobacillus fermentum ATCC 9338, 0813K.

[0027] MRS liquid culture medium: Shandong Top Biotechnology Co., Ltd., MD363.

[0028] Lactic acid bacteria induction medium: MRS liquid medium supplemented with 0.5% (w / v) yeast extract and 1.0% (v / v) ethanol; Yeast extract: Shandong Top Biotechnology Co., Ltd., C0004.

[0029] The initial pH of the lactic acid bacteria induction medium was 6.0. A new type of medium was prepared for every 0.2 units of pH decrease, until the pH dropped to 5.0.

[0030] YPD liquid culture medium: Shandong Top Biotechnology Co., Ltd., M4181.

[0031] Yeast induction medium: Lactic acid and acetic acid are mixed in a 1:1 ratio and added to YPD liquid medium to a final concentration of 1.5% (v / v). Then, 0.1% (w / v) phenylalanine and 0.05% (w / v) leucine are added, and the pH of the medium is adjusted to 4.2.

[0032] Saccharomyces cerevisiae, CICC 32883.

[0033] All strains should be routinely activated to the logarithmic growth phase before use.

[0034] Other ingredients can be purchased from CAS (China's official CAS website).

[0035] Example 1 This embodiment provides a method for preparing a compound microbial fermented fruit and vegetable pickle: Step 1: Induction and culture of bacterial strains Lactobacillus plantarum and Lactobacillus fermentum were mixed in a predetermined ratio (2:1 live bacteria ratio) to form the initial lactic acid bacteria population.

[0036] The initial lactic acid bacteria population was inoculated into a lactic acid bacteria induction medium at a 2% inoculum and anaerobically cultured at 37°C for 18-24 hours. The culture at the end of the logarithmic growth phase was then transferred at a 2% inoculum to a freshly prepared induction medium of the same type with an initial pH reduced by 0.2 units. This process was repeated for 5-7 generations until the initial pH of the final induction medium was reduced to 5.0, resulting in an inducible lactic acid bacteria population that was acid- and microalcohol-tolerant and adapted to the environment of yeast metabolites.

[0037] Directed induction culture of yeast: Wickham's abnormal yeast was used as the initial yeast.

[0038] Inoculate *Saccharomyces cerevisiae* at a 2% inoculum into yeast induction medium and culture at 28°C under static conditions (using a breathable sealing membrane to create microaerobic conditions) for 24-48 hours. Maintaining consistent acidic pressure and precursor amino acid concentration in the medium, subculture for 5-7 generations to obtain acidophilic yeast strains that produce high levels of target esters (phenethyl acetate and isoamyl acetate).

[0039] Step 2, Preparation of Fruit and Vegetable Substrate Slurry Wash the apples, onions, garlic, and Jerusalem artichokes. Heat the Jerusalem artichokes in a 50-55℃ water bath for 10-15 minutes to inactivate the enzymes. Then, add water in a mass ratio of 50:30:20:10 and mix into a uniform paste (solid content 30%, particle size ≤200μm, viscosity 5000mPa·s) to serve as the fermentation substrate.

[0040] Step 3: Co-fermentation of compound microbial strains The induced lactic acid bacteria and yeast were mixed together at a live bacteria ratio of yeast:lactic acid bacteria = 1:10, with the total inoculation amount being 2% of the weight of the fruit and vegetable substrate mud, and then thoroughly mixed.

[0041] First stage (aerobic fermentation): Ferment for 18-24 hours at 28-30℃ in an open container with a rotation speed of 100 rpm to promote yeast proliferation and flavor precursor accumulation.

[0042] The second stage (anaerobic fermentation): raise the temperature to 35-37℃, seal the container, and let it ferment for 48-72 hours to promote the production of acid and the maturation of flavor substances dominated by lactic acid bacteria.

[0043] Fermentation endpoint: When the pH of the fermentation system drops to around 4.0 and remains stable for more than 12 hours, and the reducing sugar consumption rate reaches more than 90%, the fermentation is terminated. The fermentation product has a mellow sour aroma and fruit ester aroma, and the primary fermentation product is obtained.

[0044] Step 4: Flavor blending and post-processing To achieve the desired honey flavor, add salt and honey to the primary fermentation products, mix well, and then refrigerate the prepared marinade at 4°C for 24-48 hours to allow the flavors to meld.

[0045] Heat treatment at 85-95℃ for 15-30 seconds is used to kill live bacteria, terminate fermentation, and stabilize quality. After cooling, it is filled in an aseptic environment to obtain the final product – compound microbial fermented fruit and vegetable pickle.

[0046] Example 2 This embodiment provides a method for preparing a compound microbial fermented fruit and vegetable pickle: Step 1 is the same as in Example 1.

[0047] Step 2, Preparation of Fruit and Vegetable Substrate: Apples, onions, garlic, and pretreated Jerusalem artichokes were mixed in a mass ratio of 40:25:25:10. Water was added to make the solid content 25%, and the mixture was pounded into a mud-like matrix with a particle size ≤200μm and a viscosity of about 4000mPa·s.

[0048] Step 3, Co-fermentation of Compound Microbial Strains: The inoculation ratio was adjusted to yeast:lactic acid bacteria = 1:30 (live bacteria ratio), with a total inoculation amount of 2%. Other procedures were the same as in Example 1.

[0049] Step 4: Flavor blending and post-processing According to the target flavor of black pepper, add salt, ground black pepper, onion powder, and mushroom powder; otherwise, it is the same as in Example 1.

[0050] Example 3 This embodiment provides a method for preparing a compound microbial fermented fruit and vegetable pickle: Step 3, co-fermentation of compound microorganisms: The inoculation ratio is yeast:lactic acid bacteria = 1:100, but the total inoculation amount is reduced to 1%. Aerobic fermentation (28℃, 150rpm) for 24 hours, anaerobic fermentation (35℃) until the pH drops to 4.2, and the total fermentation time is about 70 hours.

[0051] Everything else is the same as in Example 1.

[0052] Comparative Example 1 This comparative example provides a method for preparing a compound microbial fermented fruit and vegetable marinade: Lactobacillus plantarum, Lactobacillus fermentum, and Wickham's yeast were directly activated on slant culture (using the same activation procedure as in Example 1, except without induction treatment, and directly inoculated according to the proportions in Example 1), without any pre-acclimatization or induction steps. The same fruit and vegetable substrate was inoculated at the proportions and total inoculation amount (2%) as in Example 1. The fermentation process parameters were exactly the same as in Example 1.

[0053] Comparative Example 2 This comparative example provides a method for preparing a compound microbial fermented fruit and vegetable marinade: In step three, the inoculated microbial population induced in Example 1 was used, with the same inoculation ratio and total amount. The inoculated fruit and vegetable puree was placed at a constant temperature of 32°C and allowed to stand (basically anaerobic) for 72 hours to ferment until the pH dropped to 4.0.

[0054] Everything else is the same as in Example 1.

[0055] Comparative Example 3 This comparative example provides a method for preparing a compound microbial fermented fruit and vegetable marinade: Replace the abnormal Wickham yeast with common brewer's yeast, otherwise the same as in Example 1.

[0056] Comparative Example 4 This comparative example provides a method for preparing a compound microbial fermented fruit and vegetable marinade: The lactic acid bacteria is Lactobacillus plantarum, and the rest is the same as in Example 1.

[0057] Comparative Example 5 This comparative example provides a method for preparing a compound microbial fermented fruit and vegetable marinade: The lactic acid bacteria is Lactobacillus fermentum, and the rest is the same as in Example 1.

[0058] Comparative Example 6 This comparative example provides a method for preparing a compound microbial fermented fruit and vegetable marinade: Without using yeast, supplement the inoculum by 2%, otherwise the same as in Example 1.

[0059] Experimental Example 1 The physicochemical properties of the primary fermentation products obtained in Examples 1-3 and Comparative Examples 1-6 were tested, and the results were repeated three times. The results are shown in Table 1.

[0060] Total acid (calculated as lactic acid): determined according to national standard methods.

[0061] Isoamyl acetate and phenethyl acetate: Qualitative and quantitative analysis was performed using headspace solid-phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS).

[0062] γ-Aminobutyric acid (GABA) content: determined by high performance liquid chromatography (HPLC).

[0063] Total ester content: The volatile esters in the sample were qualitatively and quantitatively analyzed by headspace solid phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS). The total ester content is the sum of the quantitative results of each ester monomer detected (including but not limited to ethyl acetate, isoamyl acetate, phenylethyl acetate, ethyl hexanoate, etc.).

[0064] Table 1 As shown in Table 1, induced culture significantly enhanced the aroma-producing efficiency of the microbial community. Compared with Comparative Example 1 (without induction), the contents of phenethyl acetate, isoamyl acetate, and total esters in this invention were significantly increased, indicating that the induced culture of lactic acid bacteria and yeast can directionally enhance the metabolic pathways of microorganisms and improve the flavor of the marinade. Comparative Example 2 (single-stage isothermal anaerobic fermentation), although using inducing strains, showed a significant decrease in phenethyl acetate content compared to Example 1, and a severe deficiency in total ester production. This indicates that a two-stage fermentation process is essential for constructing an aroma-producing metabolic environment; without an aerobic initiation period, yeast aroma-producing metabolism is fundamentally inhibited. The two-stage variable-temperature fermentation process of "aerobic followed by anaerobic" creates the optimal environment for the orderly growth and metabolic cooperation of yeast and lactic acid bacteria. Comparative Example 3 used Saccharomyces cerevisiae, which produced a certain amount of isoamyl acetate, but the yield of phenethyl acetate was reduced. This confirms that *Saccharomyces cerevisiae* is irreplaceable in synthesizing elegant floral esters, represented by phenethyl acetate, under specific acidic and precursor environments. In Comparative Examples 4 and 5 (using only a single lactic acid bacteria), although yeast was present, the contents of phenethyl acetate and isoamyl acetate were close to zero (<1 mg / kg), and the total ester content was reduced. This indicates that the specific combination of *Lactobacillus plantarum* and *Lactobacillus fermentum* played a key synergistic role in providing the precursors required for yeast growth and optimizing the fermentation environment. In Comparative Example 6 (without yeast), the key characteristic flavor compounds phenethyl acetate and isoamyl acetate were not detected, and the total ester content was extremely low. Therefore, it can be concluded that the rich fruity and floral flavor compounds in the product of this invention are entirely dependent on the metabolic activity of yeast (*Wickham's abnormal*).

[0065] This invention utilizes a specific microbial community of "Lactobacillus plantarum + Lactobacillus fermentum + Wickham's yeast" and combines it with a three-pronged technical solution of "directed induction and domestication" and "two-stage temperature-controlled fermentation" to successfully achieve the targeted and efficient synthesis of product flavor (especially characteristic esters), while also taking into account functional components. The technical effect is significant and comprehensively superior to existing solutions.

[0066] Experiment Example 2 Sensory evaluations were performed on the primary fermentation products obtained in Examples 1-3 and Comparative Examples 1-6, repeated three times. The results are shown in Table 3.

[0067] Sensory evaluation: Ten trained tasters conducted a blind taste test (out of 10) to score the product's aroma, flavor, harmony, and overall acceptability. See Table 2 for explanations of each indicator.

[0068] Table 2 Table 3 As shown in Table 3, Comparative Example 1 (uninduced) scored significantly lower than Example 1 in all aspects (especially aroma-related indicators), demonstrating that induced culture is indispensable for improving the efficiency of microbial community collaboration and the sensory quality of the final product. Comparative Example 2 (single-stage fermentation) ranked second to last in aroma quality (5.4) and overall acceptability (6.0) among all comparative examples, only higher than Comparative Example 6, which had no yeast at all. This clearly illustrates that the "two-stage fermentation process" lacking aerobic initiation severely damages the product aroma, leading to a sharp drop in consumer acceptance. Comparative Example 3 (using Saccharomyces cerevisiae) had a much lower aroma quality than Example 1, confirming the irreplaceable strain advantage of *Saccharomyces cerevisiae* in generating the characteristic fruity / floral aromas required by this invention. Comparative Examples 4 and 5 (single lactic acid bacteria): Although the taste harmony score was not low, the aroma quality and overall acceptability were low. This indicates that lactic acid bacteria alone can form a harmonious acidity base, but cannot construct an attractive characteristic aroma, resulting in low overall consumer preference. This highlights the crucial role of the lactic acid bacteria complex (plant + fermentation) in supporting yeast aroma production and forming a complete flavor system. Comparative Example 6 (no yeast) presents the most convincing sensory data: aroma quality and overall acceptability are drastically the lowest. This directly and irrefutably proves that without yeast, the product completely loses its core flavor appeal, teetering on the edge of "unacceptable," thus thoroughly negating the use of lactic acid bacteria alone from a market perspective.

[0069] This invention, through a three-pronged technical solution of "complex microbial flora (Lactobacillus plantarum + Lactobacillus fermentum + Wickham's abnormal yeast) - directed induction - two-stage fermentation," successfully transforms advanced technological design into superior sensory qualities that consumers can clearly perceive and highly appreciate. Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A method for preparing a compound microbial fermented fruit and vegetable pickle, characterized in that, The method includes: Step 1: Preparation of Fruit and Vegetable Substrate Add an appropriate amount of water to fruits rich in fermentable sugars, sulfur-containing flavored vegetables, and prebiotic-based ingredients, blend them into a puree, and use it as a fruit and vegetable base puree. Step 2, Fermentation of Compound Microbial Strains Lactic acid bacteria and yeast, after induction culture, were inoculated into fruit and vegetable substrate mud, and fermented aerobically first and then anaerobically to obtain fermentation products. Step 3, Flavor blending Common food additives are added to the fermentation products, and the mixture is then refrigerated at low temperature for further ripening. A heat treatment at 85-95℃ for 15-30 seconds is then applied to kill live bacteria and terminate the fermentation. The mixture is then cooled to room temperature to obtain the compound bacteria fermented fruit and vegetable pickle.

2. The method for preparing a compound microbial fermented fruit and vegetable pickle according to claim 1, characterized in that, In step one, the fruit rich in fermentable sugars is selected from one or more of apples, pears, and pineapples; the sulfur-containing flavored vegetables are selected from one or more of onions, leeks, and garlic; the raw materials for prebiotic sources are selected from pretreated Jerusalem artichokes and / or chicory roots; the method of pretreatment of Jerusalem artichokes includes heating the Jerusalem artichokes in a water bath at 50-55℃ for 10-15 minutes before use.

3. The method for preparing a compound microbial fermented fruit and vegetable pickle according to claim 1, characterized in that, In step two, the lactic acid bacteria are Lactobacillus plantarum and Lactobacillus fermentum; the yeast is Wickham yeast anomala. Both the lactic acid bacteria and the yeast are used after induction culture.

4. The method for preparing a compound microbial fermented fruit and vegetable pickle according to claim 3, characterized in that, The induction culture of lactic acid bacteria includes mixing Lactobacillus plantarum and Lactobacillus fermentum in a certain proportion and inoculating them into a lactic acid bacteria induction medium. After anaerobic culture for 18-24 hours, the culture at the end of the logarithmic phase is taken and transferred to fresh induction medium with a pH reduced by 0.1-0.2 units at an inoculation rate of 2%. The medium is passaged for 5-7 generations until the initial pH of the medium is reduced to 5.0, thus obtaining the induced lactic acid bacteria.

5. The method for preparing a compound microbial fermented fruit and vegetable pickle according to claim 4, characterized in that, The induction medium is MRS liquid medium with added yeast extract and ethanol. The initial pH of the lactic acid bacteria induction medium is 6.

0. A new type of medium is prepared for every 0.1-0.2 units of pH decrease, until the pH drops to 5.

0.

6. The method for preparing a compound microbial fermented fruit and vegetable pickle according to claim 3, characterized in that, The induction culture of the yeast involves inoculating *Wickhamia esculenta* into a yeast induction medium, culturing it under microaerobic conditions for 24-28 hours, maintaining the acidic pressure and precursor amino acid concentration of the medium throughout, and continuously subculturing it for 5-7 generations to obtain the induced yeast.

7. The method for preparing a compound microbial fermented fruit and vegetable pickle according to claim 6, characterized in that, The yeast induction medium is a mixture of lactic acid and acetic acid, added to YPD liquid medium, and then phenylalanine and leucine are added. The pH of the medium is adjusted to be acidic.

8. The method for preparing a compound microbial fermented fruit and vegetable pickle according to claim 1, characterized in that, In step two, the ratio of live bacteria added to live lactic acid bacteria and yeast is 100-10:

1.

9. The method for preparing a compound microbial fermented fruit and vegetable pickle according to claim 1, characterized in that, In step two, the aerobic fermentation followed by anaerobic fermentation includes aerobic fermentation at 28-30℃ for 18-24 hours without sealing and stirring. After fermentation, the temperature is raised to 35-37℃, sealed and left to stand for anaerobic fermentation for 48-72 hours.

10. A compound microbial fermented fruit and vegetable pickling seasoning, characterized in that, The marinade is prepared by any one of the methods described in claims 1-9.

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