Lactic acid bacterial seed solution and method for preparing the same

Abstract

This invention relates to the field of lactic acid bacteria cultivation technology, and more particularly to a lactic acid bacteria seed culture and its preparation method. This invention utilizes citrus processing byproducts to construct a natural culture medium, eliminating the need for additional chemical reagents. This solves the problem of citrus processing byproduct disposal, achieving resource utilization of waste, and reduces the production cost of lactic acid bacteria cultivation. It also avoids the environmental deficiencies and poor cell protection effects of traditional artificially synthesized culture media, balancing the growth requirements of lactic acid bacteria with the feasibility of industrial applications. This model aligns with the concept of green development and promotes a closed-loop system in the citrus processing industry, achieving resource recycling. It not only meets the needs of large-scale lactic acid bacteria cultivation but also contributes to agricultural upgrading, alleviates resource waste and environmental pressure, and offers economic, ecological, and social benefits. It provides a new path for low-cost, green cultivation of lactic acid bacteria and injects new impetus into the sustainable development of the citrus processing industry.

Description

Technical Field

[0001] This invention relates to the field of lactic acid bacteria culture technology, and in particular to a lactic acid bacteria seed liquid and its preparation method. Background Technology

[0002] Currently, the field of lactic acid bacteria cultivation generally faces pain points such as high culture medium costs, poor raw material compatibility, and insufficient bacterial protection. This is because traditional lactic acid bacteria cultivation mostly relies on artificially synthesized culture media, which in turn rely heavily on chemical reagents or purchased raw materials. These media are not only expensive but also have limited composition, making it difficult to meet the needs of large-scale industrial cultivation. Furthermore, they suffer from low bacterial survival rates and poor stress resistance, hindering the achievement of low-cost, sustainable production goals and making it difficult to promote industrial-scale cultivation.

[0003] Against this backdrop, traditional lactic acid bacteria culture methods are no longer adequate to meet the needs of industrial development. Therefore, developing a new lactic acid bacteria culture method to address these issues has been a long-standing challenge for those skilled in the art. Summary of the Invention

[0004] In view of this, the present invention provides a lactic acid bacteria seed liquid and its preparation method. The lactic acid bacteria seed liquid provided by the present invention is low in cost, rich in active substances such as flavonoids and polyphenols, naturally protects lactic acid bacteria and inhibits other bacteria, and the cultured lactic acid bacteria have the advantage of high activity.

[0005] This invention provides a lactic acid bacteria seed culture, comprising a culture medium and lactic acid bacteria inoculated in the culture medium; the culture medium comprises citrus pomace extract and essential oil extract residue; the volume ratio of the citrus pomace extract to the essential oil extract residue is 68~72:28~32; the pH value of the culture medium is 5.5~6.

[0006] Preferably, the culture medium further includes a regulator; the regulator accounts for 0.65~0.67 wt% of the culture medium by mass.

[0007] Preferably, the regulator comprises potassium dihydrogen phosphate, magnesium sulfate, and light calcium carbonate; the mass ratio of potassium dihydrogen phosphate to magnesium sulfate is 2~10:5; and the mass ratio of potassium dihydrogen phosphate to light calcium carbonate is 2~10:50.

[0008] Preferably, the regulator further includes Tween; the mass ratio of potassium dihydrogen phosphate to Tween is 2~10:10.

[0009] Preferably, the lactic acid bacteria are one or more of Lactobacillus plantarum, Lactobacillus casei, and Lactobacillus acidophilus; the viable count of lactic acid bacteria in the lactic acid bacteria seed solution is 2.85 × 10⁻⁶. 8 ~1.5×10 9 CFU / mL.

[0010] The present invention also provides a method for preparing the lactic acid bacteria seed liquid described in the above-mentioned scheme, comprising the following steps: (1) After mixing the citrus pulp and essential oil extract residue, solid-liquid separation and pH adjustment were carried out in sequence to obtain the culture medium; (2) The activated lactic acid bacteria strains are inoculated into the culture medium and cultured to obtain the lactic acid bacteria seed liquid.

[0011] Preferably, the target pH value for pH adjustment is 5.5 to 6.0; and the pH adjustment reagent used is ammonia.

[0012] Preferably, the inoculation amount is 4.5-5.5% by volume.

[0013] Preferably, the equipment used for cultivation includes a constant temperature cultivation device; the cultivation parameters include: a cultivation temperature of 37°C; and a cultivation time of 24~36h.

[0014] Preferably, the culture is carried out under static or shaking conditions; the shaking rate of the shaking table is 100 rpm.

[0015] Compared with the prior art, the present invention achieves the following technical effects: (1) This invention utilizes agricultural waste resources to scientifically, efficiently, economically and environmentally utilize citrus processing by-products (citrus pomace extract and essential oil extraction residue) to prepare lactic acid bacteria seed liquid: The citrus processing industry generates a large amount of citrus processing by-products during the production process. Among them, the yield of citrus pomace extract (residue after juicing citrus peel and pulp) and essential oil extraction residue is considerable (300-500 kg of citrus pomace extract and a large amount of fruit pomace are generated for every 1 ton of fresh citrus processed, and 700-900 kg of distillation residue is generated for every 1 kg of citrus essential oil extracted in the essential oil extraction stage). These by-products are readily available on-site, but are usually discarded directly.

[0016] This invention offers a new approach to solving this problem. These citrus processing byproducts can be used locally without long-distance transportation, reducing transportation costs and avoiding the cost pressure of purchasing raw materials. The invention's research found that essential oil extraction residues are rich in active ingredients such as flavonoids and polyphenols, while citrus pomace extract contains ample carbon sources. The combination of these two provides sufficient nutrition for lactic acid bacteria growth while protecting their activity with the help of natural active ingredients, reducing contamination by other microorganisms. Compared to traditional artificially synthesized culture media, this approach is more environmentally friendly and economical.

[0017] Compared to traditional lactic acid bacteria cultivation methods, this invention utilizes citrus processing byproducts to construct a natural culture medium, eliminating the need for additional chemical reagents. This solves the problem of citrus processing byproduct disposal, achieving resource utilization of waste, and reducing the production cost of lactic acid bacteria cultivation. It also avoids the environmental deficiencies and poor cell protection effects of traditional synthetic culture media, balancing the growth requirements of lactic acid bacteria with the feasibility of industrial applications. This model aligns with the concept of green development and promotes a closed-loop system in the citrus processing industry, achieving resource recycling. It not only meets the needs of large-scale lactic acid bacteria cultivation but also contributes to agricultural upgrading, alleviates resource waste and environmental pressure, and offers economic, ecological, and social benefits. It provides a new path for low-cost, green cultivation of lactic acid bacteria and injects new impetus into the sustainable development of the citrus processing industry.

[0018] (2) The core principle of this invention lies in the synergistic effect of waste resource utilization and low-cost cultivation based on the nutritional characteristics of citrus pomace extrusion liquid and essential oil extraction residue, combined with the growth and metabolism of lactic acid bacteria. The specific principle is as follows: Nutritional matching principle: Citrus pomace extract is naturally rich in soluble reducing sugars, pectin, amino acids, vitamins, and minerals such as potassium, calcium, and magnesium. The essential oil extract residue is rich in active ingredients such as flavonoids and polyphenols. Among them, soluble reducing sugars can directly serve as a carbon source required for the growth of lactic acid bacteria, providing energy for the metabolism of lactic acid bacteria; amino acids can serve as a nitrogen source, meeting the needs of lactic acid bacteria to synthesize biological macromolecules such as proteins and nucleic acids; vitamins, minerals, and pectin degradation products can serve as growth factors for lactic acid bacteria, promoting the proliferation and maintaining the activity of lactic acid bacteria; flavonoids and polyphenols can help protect the activity of lactic acid bacteria and inhibit the growth of miscellaneous bacteria. The types and contents of the above nutrients are highly matched with the growth requirements of lactic acid bacteria, eliminating the need to supplement a large amount of artificially synthesized culture medium, thus reducing the cultivation cost from the source.

[0019] Environmental control principle: Lactic acid bacteria are acidophilic microorganisms, and the suitable pH range for their growth is 6.0~7.0. This invention creates an acidic or alkaline environment conducive to the growth of lactic acid bacteria and inhibits the reproduction of other bacteria by adjusting the pH of citrus processing by-products to the above-mentioned suitable range. At the same time, through solid-liquid separation, insoluble solids such as suspended impurities and pulp fragments in citrus processing by-products are removed, reducing the carriers for other bacteria and lowering the risk of contamination. Pure culture of lactic acid bacteria can be achieved without high-temperature and high-pressure sterilization, which avoids the destruction of natural nutrients in citrus processing by-products by high temperature and reduces the energy consumption and cost of sterilization.

[0020] Resource recycling principle: In response to the resource waste and environmental pollution caused by the direct discharge of citrus processing by-products, this invention transforms citrus processing by-products into the core raw material of lactic acid bacteria seed liquid through process construction, realizing the transformation of "waste-resource". At the same time, combined with the existing utilization methods of citrus pulp, a closed loop of resource utilization of all components of citrus pulp is constructed to achieve the dual goals of efficient resource utilization and environmental governance, which is in line with the development concept of green industry.

[0021] High-efficiency cultivation principle: The proliferation efficiency of lactic acid bacteria is closely related to the cultivation environment and nutrient supply. This invention provides a suitable growth and metabolic environment for lactic acid bacteria by controlling the inoculum size, cultivation temperature, cultivation time, and static or shaking conditions. This promotes the lactic acid bacteria to fully utilize the nutrients in citrus processing by-products, rapidly proliferate, and ensure the acquisition of a stable lactic acid bacteria seed culture with a viable count of 2.85 × 10⁻⁶. 8 ~1.5×10 9 CFU / mL, meeting the needs of industrial production.

[0022] (3) Compared with the prior art, the present invention also has the following advantages: High resource utilization rate: It turns the citrus processing by-products that were originally directly discharged into the market into valuable resources, making full use of their natural nutrients, achieving zero-waste utilization of all components of citrus residue, and eliminating resource waste.

[0023] Significantly reduced cultivation costs: Using citrus processing by-products as the main culture medium, there is no need to add high-priced carbon or nitrogen sources. The cost of the culture medium raw materials is reduced by more than 60% compared to commonly used artificial synthetic culture media, greatly reducing the investment in the industrial production of lactic acid bacteria.

[0024] Significant environmental benefits: It reduces the emission of by-products from citrus processing at the source, lowers the pressure on wastewater treatment, and aligns with the concepts of green processing and circular economy.

[0025] The seed culture exhibits excellent activity: the natural nutrients in the citrus processing byproducts are balanced, and the viable count of the lactic acid bacteria in the cultured seed culture is 2.85 × 10⁻⁶. 8 ~1.5×10 9 With a concentration of CFU / mL, the cells exhibit strong activity and can be directly used for subsequent large-scale fermentation, meeting the needs of industrial production.

[0026] The process is simple and easy to promote: the steps are simple, the operation is convenient, the equipment is highly versatile, no new special equipment is required, it is suitable for supporting the citrus processing industry, and the industrialization prospects are broad. Detailed Implementation

[0027] This invention provides a lactic acid bacteria seed culture, comprising a culture medium and lactic acid bacteria inoculated in the culture medium; the culture medium comprises citrus pomace extract and essential oil extract residue; the volume ratio of the citrus pomace extract to the essential oil extract residue is 68~72:28~32; the pH value of the culture medium is 5.5~6.

[0028] In this invention, the volume ratio of the citrus pomace extract to the essential oil extract residue is preferably 69~71:29~31, and more preferably 70:30.

[0029] In this invention, the culture medium preferably further includes a regulator; the regulator preferably accounts for 0.65~0.67 wt% of the mass of the culture medium.

[0030] In this invention, the regulator preferably includes potassium dihydrogen phosphate, magnesium sulfate, and light calcium carbonate.

[0031] In this invention, the mass ratio of potassium dihydrogen phosphate to magnesium sulfate is preferably 2 to 10:5, more preferably 4 to 8:5, and even more preferably 6:5.

[0032] In this invention, the mass ratio of potassium dihydrogen phosphate to light calcium carbonate is preferably 2~10:50, more preferably 4~8:50, and even more preferably 6:50.

[0033] In this invention, the regulator preferably further includes Tween; the Tween is preferably Tween 80; the mass ratio of potassium dihydrogen phosphate to Tween is preferably 2~10:10, more preferably 4~7:10.

[0034] In this invention, the preferred composition of the culture medium is: 99.35 wt% of citrus pomace extract and essential oil extract residue, 0.1 wt% of potassium dihydrogen phosphate, 0.05 wt% of magnesium sulfate, and 0.5 wt% of light calcium carbonate; the volume ratio of the citrus pomace extract and essential oil extract residue is 70:30.

[0035] In this invention, the preferred composition of the culture medium is: 99.33 wt% of citrus pomace extract and essential oil extract residue, 0.02 wt% of potassium dihydrogen phosphate, 0.05 wt% of magnesium sulfate, 0.5 wt% of light calcium carbonate, and 0.1 wt% of Tween 80; the volume ratio of the citrus pomace extract and essential oil extract residue is 70:30.

[0036] In this invention, the lactic acid bacteria are preferably one or more of Lactobacillus plantarum, Lactobacillus casei, and Lactobacillus acidophilus, more preferably Lactobacillus plantarum and Lactobacillus acidophilus; the viable count of lactic acid bacteria in the lactic acid bacteria seed solution is preferably 2.85 × 10⁻⁶. 8 ~1.5×10 9 CFU / mL.

[0037] The present invention also provides a method for preparing the lactic acid bacteria seed liquid described in the above-mentioned scheme, comprising the following steps: (1) After mixing the citrus pulp and essential oil extract residue, solid-liquid separation and pH adjustment were carried out in sequence to obtain the culture medium; (2) The activated lactic acid bacteria strains are inoculated into the culture medium and cultured to obtain the lactic acid bacteria seed liquid.

[0038] This invention involves mixing citrus pomace extract and essential oil extraction residue (resulting in a mixed waste liquid), followed by sequential solid-liquid separation and pH adjustment to obtain a culture medium. In this invention, the solid-liquid separation is preferably performed via filtration; the pore size of the filter used is preferably no larger than 60 mesh, more preferably 60-80 mesh. This invention removes suspended impurities such as fruit peel fragments and seed residue through solid-liquid separation, yielding a clear liquid for later use.

[0039] In this invention, the target pH value for pH adjustment is preferably 5.5 to 6.0; the pH adjusting reagent is preferably ammonia water; and the ammonia water is preferably industrial-grade ammonia water. This invention fine-tunes the pH value of the mixed waste liquid to the target range, adapting it to the acidic or alkaline environment for lactic acid bacteria growth. The use of ammonia water in this invention avoids the introduction of harmful impurities, ensuring the safety of the lactic acid bacteria seed culture and meeting the requirements for subsequent industrial applications.

[0040] In this invention, the pH adjustment process preferably includes mixing the resulting product with a regulator; the mixing is preferably achieved by stirring. This invention eliminates the need for additional conventional carbon and nitrogen sources such as glucose, peptone, and yeast extract; instead, it selectively adds trace amounts of inorganic salts and other regulators based on the growth requirements of the strain.

[0041] After obtaining the culture medium, the activated lactic acid bacteria strain is inoculated into the culture medium and cultured to obtain the lactic acid bacteria seed culture. In this invention, the inoculation amount is preferably 4.5~5.5% (volume fraction), more preferably 5% (volume fraction).

[0042] In this invention, the cultivation equipment preferably includes a constant temperature cultivation device; the constant temperature cultivation device is preferably a constant temperature incubator; the cultivation parameters preferably include: a cultivation temperature of 37°C; and a cultivation time of 24~36h, more preferably 30h.

[0043] In this invention, the culture is preferably carried out under static or shaking conditions; the shaking rate is preferably 100 rpm. This invention, through shaking, promotes uniform bacterial growth, which is beneficial for obtaining highly active lactic acid bacteria seed culture.

[0044] The method for preparing lactic acid bacteria seed liquid provided by this invention has the following advantages: (1) This invention addresses the current problem of direct discharge of citrus pomace extrusion liquid and essential oil extraction residue. Citrus pomace extrusion liquid and essential oil extraction residue contain rich soluble sugars, organic acids, vitamins, minerals, and active ingredients such as flavonoids and polyphenols. Direct discharge not only causes serious waste of these valuable resources, but also increases the difficulty and cost of sewage treatment due to the high concentration of organic pollutants, and easily pollutes the ecological environment such as water bodies and soil. This invention achieves the reduction, resource utilization and high value of citrus processing by-products by synergistic utilization of citrus pomace extrusion liquid and essential oil extraction residue, thereby reducing environmental pollution from the source and practicing the concept of green environmental protection.

[0045] (2) Solving the problem of high culture medium cost in traditional lactic acid bacteria seed culture. Existing lactic acid bacteria seed culture relies on expensive artificially synthesized raw materials such as glucose and peptone, resulting in high preparation costs and limiting the large-scale development of lactic acid bacteria related industries. This invention uses citrus pomace as the main matrix and compounded with essential oil extract residue to replace some or all of the traditional expensive culture medium components. It makes full use of the natural nutrients and active ingredients in both as carbon sources, nitrogen sources and growth factors required for lactic acid bacteria growth. At the same time, it relies on flavonoids and polyphenols to naturally protect the activity of lactic acid bacteria, greatly reducing the cultivation cost of lactic acid bacteria seed culture and improving the economic benefits of the industry.

[0046] (3) Construct a closed-loop system for the resource utilization of all components of citrus pomace, break the single utilization mode of "only utilizing the pulp and discarding the citrus pomace extrusion liquid and essential oil extraction residue" in the existing citrus pomace processing, realize the synergistic utilization of various components such as citrus pomace pulp, citrus pomace extrusion liquid and essential oil extraction residue, enhance the comprehensive added value of the citrus processing industry, and promote the development of the citrus processing industry towards green, large-scale and high-value direction.

[0047] (4) Ensure that the prepared lactic acid bacteria seed liquid has good quality. While realizing resource utilization and cost reduction, rely on the protective effect of natural active ingredients in the essential oil extraction residue to ensure the proliferation efficiency, activity and stability of lactic acid bacteria, meet the quality requirements of subsequent industrial production for lactic acid bacteria seed liquid, provide technical support for the large-scale production of lactic acid bacteria related products, and ultimately achieve the unity of environmental protection benefits, economic benefits and social benefits.

[0048] In summary, this invention utilizes citrus pomace extract and essential oil extraction residue to prepare lactic acid bacteria seed culture. Using citrus pomace extract from mechanical extrusion and dehydration and essential oil extraction residue as raw materials, the process involves solid-liquid separation to remove impurities and pH adjustment. Without the need for high-temperature and high-pressure sterilization, the extract can be directly used as a culture medium for lactic acid bacteria. Only trace amounts of inorganic salts need to be added as needed, eliminating the need for additional conventional carbon and nitrogen sources. After inoculation with lactic acid bacteria, constant-temperature incubation yields a highly active lactic acid bacteria seed culture. This invention is expected to completely solve the resource waste and environmental pollution problems caused by the discharge of citrus pomace extract and essential oil extraction residue, significantly reducing the preparation cost of lactic acid bacteria seed culture. The resulting lactic acid bacteria seed culture has a high viable count and strong activity, achieving high-value utilization of all components of citrus processing byproducts, and possessing both environmental and economic benefits.

[0049] This invention constructs a natural culture medium system for all citrus by-products, which is rich in active substances such as flavonoids and polyphenols. It naturally protects lactic acid bacteria and inhibits other bacteria, enabling the in-situ, low-cost cultivation of highly active lactic acid bacteria. This realizes the full-chain resource utilization of citrus processing by-products and develops a low-cost preparation process for lactic acid bacteria.

[0050] To further illustrate the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the schemes and embodiments therein.

[0051] Example 1: (1) Treatment of citrus pomace extract and essential oil extraction residue: Collect the citrus pulp extract and essential oil extraction residue generated during the processing of sweet oranges, tangerines, etc., mix them in a ratio of 7:3 (v / v), filter through a 60-mesh filter to remove impurities, take the clear liquid, adjust the pH value to 6.0 with industrial grade ammonia water to obtain the basic culture medium for later use.

[0052] (2) Preparation of culture medium: Add 0.02 wt% potassium dihydrogen phosphate, 0.05 wt% magnesium sulfate, 0.5 wt% light calcium carbonate and 0.1 wt% Tween 80 to the above basic culture medium, and stir thoroughly to obtain the culture medium.

[0053] (3) Inoculation and culture of lactic acid bacteria: The activated Lactobacillus plantarum was inoculated into the culture medium prepared above at a volume fraction of 5%, and then incubated at 37°C for 36 hours to obtain the lactic acid bacteria seed culture.

[0054] (4) Effect detection: The lactic acid bacteria seed culture prepared in this embodiment was tested, and the results showed that the viable count of the lactic acid bacteria seed culture was 2.85 × 10⁻⁶. 8CFU / mL, cell viability meets standards; organic acid content before inoculation: lactic acid 886.81μg / mL, acetic acid 9.77mmol / L; organic acid content after inoculation: lactic acid 1490.966μg / mL, acetic acid 16.054mmol / L, can be directly used for solid-state fermentation or liquid scale-up culture.

[0055] Example 2: (1) Treatment of citrus pomace extract and essential oil extraction residue: Collect the citrus pulp extract and essential oil extraction residue generated during the processing of sweet oranges, tangerines, etc., mix them in a ratio of 7:3 (v / v), filter through a 60-mesh filter to remove impurities, take the clear liquid, adjust the pH value to 6.0 with industrial grade ammonia water to obtain the basic culture medium for later use.

[0056] (2) Preparation of culture medium: Add 0.02 wt% potassium dihydrogen phosphate, 0.05 wt% magnesium sulfate, 0.5 wt% light calcium carbonate, and 0.1 wt% Tween 80 to the above basic culture medium, and stir thoroughly to obtain the culture medium.

[0057] (3) Inoculation and culture of lactic acid bacteria: The activated Lactobacillus acidophilus was inoculated into the culture medium prepared above at an inoculation rate of 5% (volume fraction), and then incubated at 37°C for 36 hours to obtain the lactic acid bacteria seed culture.

[0058] (4) Effect detection: The lactic acid bacteria seed culture prepared in this embodiment was tested, and the results showed that the viable count of the lactic acid bacteria seed culture was 1.5 × 10⁻⁶. 9 CFU / mL, cell viability meets standards; organic acid content before inoculation: lactic acid 886.81μg / mL, acetic acid 9.77mmol / L; organic acid content after inoculation: lactic acid 1654.088μg / mL, acetic acid 15.54mmol / L, can be directly used for solid-state fermentation or liquid scale-up culture.

[0059] Example 3: (1) Treatment of citrus pomace extract and essential oil extraction residue: Collect the citrus pulp extract and essential oil extraction residue generated during the processing of sweet oranges, tangerines, etc., mix them in a ratio of 7:3 (v / v), filter through a 60-mesh filter to remove impurities, take the clarified waste liquid, adjust the pH value to 6.0 with industrial grade ammonia water to obtain the basic culture medium for later use.

[0060] (2) Preparation of culture medium: Add 0.02 wt% potassium dihydrogen phosphate, 0.05 wt% magnesium sulfate, 0.5 wt% light calcium carbonate, and 0.1 wt% Tween 80 to the above basic culture medium, and stir thoroughly to obtain the culture medium.

[0061] (3) Inoculation and culture of lactic acid bacteria: The activated lactic acid bacteria and Lactobacillus acidophilus were inoculated into the culture medium prepared above at an inoculation rate of 2.5% (volume fraction) each, and then incubated at 37°C for 36 hours to obtain a mixed lactic acid bacteria seed culture.

[0062] (4) Effect detection: The lactic acid bacteria seed culture prepared in this embodiment was tested, and the results showed that the viable count of *Lactobacillus plantarum* in the seed culture was 8.35 × 10⁻⁶. 8 CFU / mL, viable count of Lactobacillus acidophilus was 7.95 × 10⁻⁶. 8 CFU / mL, cell viability meets standards; organic acid content before inoculation: lactic acid 886.81μg / mL, acetic acid 9.77mmol / L; organic acid content after inoculation: lactic acid 1745.48μg / mL, acetic acid 15.92mmol / L, can be directly used for solid-state fermentation or liquid scale-up culture.

[0063] The embodiments of the present invention have been described above; however, these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. All other embodiments obtained by those skilled in the art based on the above embodiments of the present invention without inventive effort are within the protection scope of the present invention.

Claims

1. A lactic acid bacteria seed liquid, characterized in that, Includes culture medium and lactic acid bacteria inoculated in the culture medium; The culture medium includes citrus pomace extract and essential oil extraction residue; The volume ratio of the citrus pomace extract to the essential oil extract residue is 68~72:28~32; The pH value of the culture medium is 5.5~6.

2. The lactic acid bacteria seed liquid according to claim 1, characterized in that, The culture medium also includes a regulator; The regulator accounts for 0.65~0.67 wt% of the culture medium.

3. The lactic acid bacteria seed liquid according to claim 2, characterized in that, The regulators include potassium dihydrogen phosphate, magnesium sulfate, and light calcium carbonate; The mass ratio of potassium dihydrogen phosphate to magnesium sulfate is 2~10:5; The mass ratio of potassium dihydrogen phosphate to light calcium carbonate is 2~10:

50.

4. The lactic acid bacteria seed liquid according to claim 2, characterized in that, The regulator also includes Tween; The mass ratio of potassium dihydrogen phosphate to Tween is 2~10:

10.

5. The lactic acid bacteria seed liquid according to claim 1, characterized in that, The lactic acid bacteria are one or more of Lactobacillus plantarum, Lactobacillus casei, and Lactobacillus acidophilus. The viable count of lactic acid bacteria in the lactic acid bacteria seed solution was 2.85 × 10⁻⁶. 8 ~1.5×10 9 CFU / mL.

6. A method for preparing a lactic acid bacteria seed solution, wherein the lactic acid bacteria seed solution is the lactic acid bacteria seed solution according to any one of claims 1 to 5, characterized in that, Includes the following steps: (1) After mixing the citrus pulp and essential oil extract residue, solid-liquid separation and pH adjustment were carried out in sequence to obtain the culture medium; (2) The activated lactic acid bacteria strains are inoculated into the culture medium and cultured to obtain the lactic acid bacteria seed liquid.

7. The preparation method according to claim 6, characterized in that, The target pH value for pH adjustment is 5.5~6.0; The pH adjustment reagent used is ammonia.

8. The preparation method according to claim 6, characterized in that, The inoculation amount is 4.5-5.5% by volume.

9. The preparation method according to claim 6, characterized in that, The equipment used for cultivation includes a constant temperature incubation device; The cultivation parameters include: a cultivation temperature of 37℃ and a cultivation time of 24~36h.

10. The preparation method according to claim 9, characterized in that, The culture was carried out under static or shaking conditions; The shaking table oscillates at a rate of 100 rpm.