Method for fermenting duckweed by using compound probiotic preparation and duckweed fermented product

Abstract

The invention relates to the technical field of microbial fermentation. The invention aims to provide a method for fermenting duckweed by using a compound probiotic preparation. The method comprises the following steps: mixing duckweed bran, corn flour, brown sugar and inorganic salt to obtain a culture medium; adding a compound probiotic preparation consisting of lactic acid bacteria and saccharomycetes into the culture medium, and uniformly mixing to finish inoculation, so as to obtain an inoculated material; sealing and fermenting the inoculated material to obtain a fermented material; and taking out the fermented material to obtain a feed product. Through the synergistic fermentation effect of lactic acid bacteria and saccharomycetes, duckweed cell walls are decomposed, mycoprotein is synthesized, the true protein content of the final fermented feed is increased, amino acid composition is more balanced, the fermented feed is rich in various digestive enzymes, vitamins and growth factors, and the nutritional value of the fermented feed is remarkably improved. The invention also provides a duckweed fermented product.

Description

Technical Field

[0001] This invention relates to the field of microbial fermentation technology, and in particular to a method for fermenting duckweed using a compound probiotic preparation and a fermented duckweed product. Background Technology

[0002] Duckweed is a fast-growing aquatic plant with high protein content. Its dry matter crude protein content can reach 20% to 35%, and it is rich in amino acids, vitamins and a variety of bioactive substances, making it a highly promising unconventional feed ingredient.

[0003] However, there are some problems with the direct use of duckweed as feed. First, duckweed contains certain anti-nutritional factors (such as oxalic acid and saponins) and may be contaminated with heavy metals, which affects the palatability of feed and the health of livestock and poultry. Second, duckweed has a high water content (about 90-95%), making it difficult to store and transport, and it is extremely prone to spoilage. Furthermore, its cell wall structure is complex, resulting in low digestibility and absorption rate when directly fed.

[0004] Currently, research on the feed utilization of duckweed mainly focuses on direct drying and pulverization or silage. Drying is energy-intensive and may destroy some heat-sensitive nutrients; while silage is lower in cost, the quality of silage alone is unstable, its effect on degrading anti-nutritional factors is limited, and the improvement in feed nutritional value is not significant.

[0005] Through the metabolic processes of specific microorganisms, anti-nutritional factors can be degraded, and beneficial substances such as probiotics, organic acids, and enzymes can be synthesized, thereby enhancing the nutritional value, palatability, and shelf life of duckweed. However, there is currently no systematic and mature method for the targeted fermentation of duckweed using probiotic preparations.

[0006] Therefore, providing a processing method that can efficiently and safely enhance the value of duckweed and extend its shelf life, and realize its production as feed, is an urgent problem to be solved. Summary of the Invention

[0007] In order to overcome the shortcomings of the existing technology, the purpose of this invention is to decompose the cell wall of duckweed and synthesize microbial protein through the synergistic fermentation of lactic acid bacteria and yeast, thereby increasing the true protein content of the final fermented feed, making the amino acid composition more balanced, and enriching it with a variety of digestive enzymes, vitamins and growth factors, thus significantly improving the nutritional value of the fermented feed.

[0008] To achieve the above objectives, the present invention provides a method for fermenting duckweed using a compound probiotic preparation, comprising the following steps: S1: Mix duckweed with auxiliary materials to obtain a culture medium, wherein the auxiliary materials include wheat bran, corn flour, brown sugar, and inorganic salts; S2: Add the compound probiotic preparation composed of lactic acid bacteria and yeast to the culture medium, mix evenly to complete the inoculation, and obtain the inoculated material; S3: Seal and ferment the inoculated material obtained in step S2 to obtain the fermented material; S4: Take out the fermented material obtained in step S3 to obtain the feed product.

[0009] Preferably, in step S1, the culture medium comprises, by weight: 70-85 parts duckweed, 10-20 parts wheat bran, 3-5 parts corn flour, 1-2 parts brown sugar, and 1-2 parts potassium dihydrogen phosphate.

[0010] As a further preferred embodiment, in step S1, after the duckweed and auxiliary materials are mixed evenly according to the weight ratio, the moisture content of the materials is adjusted to 55%~65%.

[0011] Preferably, the ratio of live bacteria to live yeast is (2~3):1.

[0012] Preferably, the inoculation amount of the compound probiotic preparation is 0.5% to 3.0% of the total weight of the culture medium.

[0013] Preferably, the total live bacteria count of the compound probiotic preparation is not less than 3.0 × 10⁻⁶. 10 CFU / g, the effective viable count of the lactic acid bacteria is ≥1.0×10⁻⁶. 10 CFU / g, the effective viable count of the yeast is ≥1.0×10⁻⁶. 9 CFU / g.

[0014] Preferably, in step S3, the inoculated material obtained in step S2 is sealed and placed at 25~37℃ for anaerobic or facultative anaerobic fermentation until the pH value of the material stabilizes between 4.0 and 4.5, thus obtaining the fermented material.

[0015] As a further preferred embodiment, in step S3, sealing the inoculated material obtained in step S2 includes: loading the inoculated material obtained in step S2 into a fermentation plastic bag, compacting it layer by layer, removing air, and then sealing it.

[0016] Preferably, step S4 is followed by step S5: step S5 includes drying the feed product obtained in step S4 at a low temperature of 50-60°C until the moisture content is less than 12%, then pulverizing it and passing it through a 40-60 mesh sieve to obtain dry powder feed additive.

[0017] To achieve the above objectives, the present invention also provides a fermented duckweed product, which is obtained by any of the above methods.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: Through the synergistic fermentation of lactic acid bacteria and yeast, the cell walls of duckweed are decomposed and microbial protein is synthesized, resulting in a higher true protein content, a more balanced amino acid composition, and richness in various digestive enzymes, vitamins, and growth factors, thus significantly enhancing the nutritional value of the fermented feed.

[0019] By converting duckweed, which reproduces quickly and has a large biomass, into high-value feed, waste is turned into treasure, the cost of feed raw materials is reduced, and the effect of efficient resource utilization is achieved.

[0020] The fermentation process effectively degrades anti-nutritional factors such as oxalic acid, increases protein content and digestibility, enriches probiotics and beneficial metabolites, and produces safe, nutritious, and palatable high-quality fermented feed. At the same time, it provides an effective way for the high-value utilization of duckweed and the development of new protein feed resources.

[0021] The fermentation process requires no complex equipment, has a simple process, low energy consumption, simple technology, low cost, is easy to promote, and is suitable for promotion and application in small and medium-sized feed mills or farms. Detailed Implementation

[0022] The present invention will now be described in more detail. It should be noted that the following description of the present invention is merely illustrative and not restrictive.

[0023] Where possible, the various embodiments described below can be rearranged to form other embodiments not shown in the following description; the various technical features described below can also be rearranged to form other embodiments not shown in the following description.

[0024] This invention utilizes a method for fermenting duckweed using a compound probiotic preparation, comprising: S1: Mix the pretreated duckweed with wheat bran, corn flour, brown sugar, and inorganic salt in the following weight proportions: 70-85 parts duckweed, 10-20 parts wheat bran, 3-5 parts corn flour, 1-2 parts brown sugar, and 1-2 parts potassium dihydrogen phosphate.

[0025] It should be noted that the duckweed underwent pretreatment before being mixed with the auxiliary materials. Specifically, this included: after collecting fresh duckweed, rinsing it with clean water to remove mud and impurities. Collected duckweed carries both physical and biological impurities; rinsing removes these impurities to reduce competition from other microorganisms during subsequent fermentation, ensuring that lactic acid bacteria and yeast become the dominant flora and reducing the safety risks of fermented feed. Subsequently, it was dehydrated to a moisture content of 70%–80% for later use. Maintaining the duckweed's moisture content within a relatively stable range provides a reliable benchmark for subsequent ingredient calculations, ensuring stable feed quality. This moisture content range allows for precise control of the duckweed's physical state and moisture content, creating a prerequisite for successful solid-state fermentation. Dehydration of the duckweed also addresses the issue that high moisture content in duckweed is detrimental to the growth of facultative anaerobic yeasts, ensuring the stability of subsequent fermentation.

[0026] Dehydration can be achieved through mechanical pressing or centrifugation. Mechanical pressing allows for precise control of the duckweed's moisture content within the desired range. During the pressing process, more nutrients are released from the duckweed cells, accelerating subsequent fermentation and improving efficiency. This method uses relatively simple equipment with low operating costs, making it suitable for feed production. Centrifugation, on the other hand, causes less damage to the duckweed cells and produces more uniform moisture content, promoting consistent fermentation. This method is suitable for developing high-value-added fermented feeds, demonstrating its flexibility and adaptability to different applications, thus enhancing its value.

[0027] Wheat bran provides cellulose, corn flour provides starch, and readily available slow-release carbon sources complement duckweed, creating a loose, porous, and well-aerated solid fermentation substrate. The sucrose and glucose from brown sugar are readily available carbon sources, while potassium dihydrogen phosphate maintains the osmotic pressure balance and enzyme activity of microbial cells, providing an optimal nutritional environment for the growth of the complex probiotics in the later stages of fermentation. By using inexpensive duckweed as the main ingredient and low-cost agricultural by-products as auxiliary materials, high-quality feed can be produced at the lowest possible cost, while ensuring effective fermentation in the later stages.

[0028] S2: Add the compound probiotic preparation consisting of lactic acid bacteria and yeast to the culture medium, mix evenly to complete the inoculation, and obtain the inoculated material.

[0029] It should be noted that compound probiotic preparations can also be prepared in advance for later use. They are composed of lactic acid bacteria and yeast, and the ratio of live lactic acid bacteria to yeast is controlled at (2~3):1, such as 2:1, 2.5:1, 3:1, etc.

[0030] This compound probiotic preparation includes lactic acid bacteria and yeast. Through the synergistic fermentation of lactic acid bacteria and yeast, it provides a fermentation system that progresses from anaerobic to microaerobic, with nutrient interactions ensuring efficient, stable, and safe fermentation. Lactic acid bacteria contribute a sour aroma, while yeast provides a "mellow" or "fruity" aroma, making the fermented feed more palatable. The live bacteria ratio of lactic acid bacteria to yeast is 3:1, with a higher proportion of lactic acid bacteria. The rapidly established acidic environment inhibits the growth of other microorganisms, ensuring the shelf life of the fermented feed. Lactic acid bacteria are the primary component, ensuring a high success rate of fermentation, while yeast plays a supporting role, breaking down fiber, synthesizing microbial protein, and promoting growth factors, comprehensively enhancing the nutritional value of the fermented feed.

[0031] Specifically, the ratio of the inoculum amount of the compound probiotic preparation to the total weight of the culture medium should be controlled between 0.5% and 3.0%, such as 0.5%, 1.2%, 1.6%, 2.3%, 2.8%, and 3.0%. The inoculum amount of the compound probiotic preparation is the weight of the compound probiotic preparation to be added, so that the pH value of fermentation can be stabilized in the range of 4.0 to 4.5. The amount added can be selected according to the reaction conditions. When the raw materials are fresh, of good quality, and the ambient temperature is suitable, an addition amount close to 0.5% can be selected. An addition amount of 0.5% can save costs for feed mills that need to produce on a large scale. When the raw materials are old, the ambient temperature is low, or there are extremely high requirements for the fermentation start-up speed, the inoculum amount can be appropriately increased to 1.5% or 3.0%. Addition amounts exceeding 3.0% do not have clear fermentation effects and are costly; this range can ensure the success rate of fermentation.

[0032] Specifically, when adding the prepared compound probiotic preparation to the culture medium to be fermented, the total viable count of the compound probiotic preparation should not be less than 3.0 × 10⁻⁶. 10 CFU / g, effective viable count of lactic acid bacteria ≥1.0×10⁻⁶ 10 CFU / g, effective viable count of yeast ≥1.0×10⁻⁶ 9 CFU / g. The total live bacteria count of the compound probiotic preparation is not less than 3.0 × 10⁻⁶. 10 CFU / g helps inhibit unwanted bacteria, ensuring the safety and purity of the fermentation process; the effective viable count of lactic acid bacteria is ≥1.0×10⁻⁶. 10 CFU / g, during acidification, the pH value can be controlled to a safe range (4.0~4.5); the effective viable count of yeast is ≥1.0×10⁻⁶. 9 A CFU / g ratio ensures the full synthesis of microbial protein and vitamins, achieving a nutritional improvement effect of increasing crude protein and decreasing crude fiber in fermented feed.

[0033] Specifically, after uniformly mixing duckweed and auxiliary materials according to the weight ratio, adjust the moisture content of the material to 55%~65%, specifically 55%, 58%, 60%, 63%, 65%, etc. If the moisture content is greater than 65%, poor aeration will easily occur, inhibiting yeast and promoting the growth of anaerobic putrefactive bacteria, leading to feed fermentation failure. If the moisture content is less than 55%, insufficient moisture will easily occur, resulting in incomplete fermentation and low nutrient conversion rate. This range of moisture content represents moderate water activity, effectively inhibiting contamination by miscellaneous bacteria, controlling the fermentation process and heat management, and improving the success rate of converting duckweed into high-quality feed.

[0034] S3: Seal and ferment the inoculated material obtained in step S2 to obtain the fermented material. For example, after sealing the inoculated material, place it at 25~37℃ for anaerobic or facultative anaerobic fermentation until the pH value of the material stabilizes between 4.0 and 4.5 to obtain the fermented material. Sealing includes: packing the material into a fermentation plastic bag, compacting it layer by layer, removing air, and then sealing it.

[0035] It should be noted that in the early stage of fermentation, the lactic acid bacteria and yeast in the culture medium can carry out efficient aerobic respiration based on oxygen, reproduce rapidly, and control the situation by sheer numbers; in the middle to late stages, the culture medium is in an anaerobic state and begins to enter the fermentation mode, the lactic acid bacteria begin to produce large amounts of acid, and the yeast carries out alcoholic fermentation and enzyme production, thereby improving the success rate of fermentation.

[0036] After inoculation, the culture medium is first placed in a sealed anaerobic or facultative anaerobic environment. This sealed fermentation environment further inhibits the growth of pathogens, ensuring the safety of the fermented feed. The sealed space is a fermentation plastic bag, which is low-cost and allows for selection of production volume based on scale, increasing flexibility. The three operations of compaction, degassing, and sealing provide a suitable fermentation environment for yeast, preventing spoilage.

[0037] Specifically, the inoculated culture medium is placed at 25–37°C for anaerobic or facultative anaerobic fermentation. Controlling the fermentation temperature range provides optimal conditions for microbial growth, while the fermentation cycle ensures a sufficient and flexible fermentation period, thereby guaranteeing the safety and stability of the wet-based feed.

[0038] S4: Take out the fermented material obtained in step S3 to obtain the feed product.

[0039] Fermentation is terminated when the pH of the fermentation broth stabilizes at 4.0–4.5, and the fermentation medium is removed. pH is a biochemical indicator reflecting the metabolic activity of microorganisms. A pH range of 4.0–4.5 indicates that the lactic acid bacteria have produced sufficient acid, and the fermentation system has reached dynamic equilibrium. Monitoring the pH using a pH sensor and determining the end of fermentation within this range not only enables precise, efficient, and reliable control of the fermentation process but also ensures a high degree of consistency in acidity, flavor, and nutritional composition for each batch of fermented feed.

[0040] The resulting fermented feed can be used directly as wet-based feed without post-processing, reducing manufacturing costs.

[0041] To extend the storage time of fermented feed, step S5 can be further included after step S4: the feed product obtained in step S4 is dried and pulverized at low temperature to obtain a dry powder feed additive. Specifically, the feed product obtained in step S4 can be dried at a low temperature of 50-60℃ until the moisture content is below 12%, pulverized by a pulverizer, and then passed through a 40-60 mesh sieve to obtain a dry powder feed additive.

[0042] The low-temperature drying range of 50-60℃ can maximize the preservation of microbial protein, amino acids, organic acids, etc., making the dried feed a high-protein raw material and functional additive, with a value far exceeding that of ordinary fermented dried duckweed powder.

[0043] Wet-based feeds can only be stored for a short time and are at risk of spoilage. Transportation requires strict storage conditions. Processing wet-based feeds into dry powder feeds not only extends shelf life but also reduces storage space and lowers long-distance transportation costs. The dry powder feed in this embodiment can be used as a feed ingredient or flexibly as a functional additive, achieving secondary value-added processing of fermented feeds.

[0044] The present invention also provides a fermented duckweed product, which is prepared by the above method, and the culture medium can be obtained by mixing purple-backed duckweed, duckweed and auxiliary materials.

[0045] In some embodiments, the duckweed can be either *Lemna minor* or *Lemna minor*. The cell wall structure of *Lemna minor* and *Lemna minor* is not very robust, making them more conducive to microbial decomposition during fermentation, thus significantly improving feed digestibility and utilization. Both *Lemna minor* and *Lemna minor* have high protein content, ensuring the nutritional value of the fermented feed as raw materials. *Lemna minor* and *Lemna minor* reproduce rapidly, are highly adaptable to different environments, and are low-cost, achieving efficient resource utilization. In other embodiments, the duckweed can include both *Lemna minor* and *Lemna minor*. Different species of duckweed have slight differences in nutritional composition, and mixing them can provide nutritional complementarity.

[0046] The principles and effects of the present invention will be further illustrated below through different specific embodiments.

[0047] Example 1 Take 80 kg of treated duckweed, add 15 kg of wheat bran, 4 kg of corn flour, 1.5 kg of brown sugar and 1 kg of potassium dihydrogen phosphate, mix well, spray a small amount of water, and adjust the overall moisture content to 60% to obtain the culture medium.

[0048] Take 2 kg of compound probiotic preparation, wherein the ratio of lactic acid bacteria to yeast is 3:1, and the total live bacteria count is 3.0 × 10⁻⁶. 10 After activating the CFU / g solution with 5L of sterile water for 30 minutes, spray it evenly onto the culture medium and mix thoroughly.

[0049] After inoculation, the material is placed into a fermentation plastic bag, compacted and sealed, and placed in a constant temperature room at 30℃ for 7 days for fermentation.

[0050] After fermentation, a strong sour aroma can be smelled upon opening the bag. The pH value is 4.2, and the product is yellow-green and soft in texture.

[0051] Example 2 Unlike Example 1, the ratio of live lactic acid bacteria to live yeast in this example is 2:1, with a total live count of 3.0 × 10⁻⁶. 10 CFU / g.

[0052] Tests showed that the crude protein content of the fermented feed increased by 12.6% compared to before fermentation, the crude fiber content decreased by 15.6%, the pH value remained stable at 4.6, the lactic acid content increased, and a sour aroma could be detected.

[0053] Example 3 Unlike Example 1, the ratio of live lactic acid bacteria to live yeast in this example is 2.5:1, with a total live count of 3.0 × 10⁻⁶. 10 CFU / g.

[0054] Tests showed that the crude protein content of the fermented feed increased by 15.3% compared to before fermentation, the crude fiber content decreased by 18.8%, the pH value remained stable at 4.4, the lactic acid content increased, and a sour aroma could be detected.

[0055] Example 4 Unlike Example 1, the ratio of live lactic acid bacteria to live yeast in this example is 1:1, with a total live count of 3.0 × 10⁻⁶. 10 CFU / g.

[0056] Tests showed that the crude protein content of the fermented feed increased by 9.5% compared to before fermentation, the crude fiber content decreased by 13.1%, the pH value remained stable at 4.8, and it had a slight alcoholic smell but insufficient sour aroma.

[0057] This shows that if yeast activity is excessive, it affects the dominant position of lactic acid bacteria, resulting in insufficient acid production, and the protein enhancement and fiber degradation effects are significantly lower than the 3:1 ratio.

[0058] Example 5 Unlike Example 1, in this example, 2 kg of a single lactic acid bacteria preparation with a live bacteria count of 3.0 × 10⁻⁶ was weighed. 10 CFU / g.

[0059] Tests showed that the crude protein content of the fermented feed increased by 11.3% compared to before fermentation, the pH value remained stable at 4.3, the fermented feed had a distinct pungent sour smell, and its palatability was poor.

[0060] This shows that the fermentation effect of a single lactic acid bacteria is far less than that of synergistic fermentation of lactic acid bacteria and yeast.

[0061] Example 6 Unlike Example 1, in this example, 0.5 kg of compound probiotic preparation is used.

[0062] Tests showed that the crude protein content of the fermented feed increased by 12.5% ​​compared to before fermentation, the crude fiber content decreased by 16.1%, the pH value stabilized at 4.6, the fermentation started slowly, and a noticeable sour taste appeared only on the third day.

[0063] This shows that although adding 0.5% completes fermentation, the effect is significantly lower than adding 2%, proving that 0.5% is the minimum critical value for effective implementation.

[0064] Example 7 Unlike Example 1, in this example, the overall moisture content was first adjusted to 50%. After testing, the crude protein content of the fermented feed increased by 8.5% compared with that before fermentation, the pH value was stable at 5.2, the fermented feed was relatively dry and hard, and the fermentation was not sufficient.

[0065] Next, the overall moisture content was adjusted to 55%. After testing, the crude protein content of the fermented feed increased by 15.6% compared with that before fermentation, the pH value stabilized at 4.8, and the lactic acid content increased.

[0066] Next, the overall moisture content was adjusted to 65%. After testing, the crude protein content of the fermented feed increased by 6.5% compared with that before fermentation, the pH value was stable at 4.9, it was obviously wet and sticky, with serious clumping, a small amount of seepage at the bottom, and a slight musty smell.

[0067] This shows that the fermentation effect decreases significantly when the water content of the culture medium is below 55% or above 65%, indicating the necessity of a water content range of 55% to 65%.

[0068] Example 8 Based on Example 1, this embodiment dries the product obtained in Example 1 in a drying room at 55°C until the moisture content is 11%, then pulverizes it with a pulverizer and passes it through a 50-mesh sieve to obtain fermented duckweed dry powder feed additive.

[0069] The fermented duckweed powder feed additive tested showed that its crude protein content increased by 18.5% compared to before fermentation, its crude fiber content decreased by 22.1%, its lactic acid content increased significantly, and no pathogenic bacteria such as Salmonella and Escherichia coli were detected.

[0070] Example 9 100 kg of fresh duckweed was collected, washed, and then dehydrated using a screw press to a moisture content of about 75%.

[0071] Take 84 kg of treated duckweed, add 10 kg of wheat bran, 3.5 kg of corn flour, 1.5 kg of brown sugar and 1 kg of potassium dihydrogen phosphate, mix well, spray a small amount of water, and adjust the overall moisture content to 60% to obtain the culture medium.

[0072] Take 3 kg of compound probiotic preparation, wherein the ratio of lactic acid bacteria to yeast is 3:1, and the total live bacteria count is 3.0 × 10⁻⁶. 10 After activating the CFU / g solution with 5L of sterile water for 30 minutes, spray it evenly onto the culture medium and mix thoroughly.

[0073] After inoculation, the material is placed into fermentation plastic bags, compacted and sealed, and placed in a constant temperature room at 28℃ for 12 days for fermentation.

[0074] After fermentation, a strong sour aroma can be smelled upon opening the bag. The pH value is 4.1, and the product is yellow-green and soft in texture.

[0075] Example 10 Based on Example 9, this embodiment dries the product obtained in Example 9 in a drying room at 55°C until the moisture content is 12%, then crushes it with a pulverizer and passes it through a 50-mesh sieve to obtain the duckweed fermented feed product.

[0076] The fermented duckweed feed product tested showed that its crude protein content increased by 16.6% compared to before fermentation, its crude fiber content decreased by 21.2%, its lactic acid content increased significantly, and no pathogenic bacteria such as Salmonella and Escherichia coli were detected.

[0077] Fresh duckweed from the same source as in Example 10 was taken, and without inoculation with inoculum, it was directly placed into bags and sealed, and stored under the same conditions for 12 days. After opening the bags, it was found to be rotten and spoiled, with a foul odor, and could not be used as feed.

[0078] The product obtained in Example 10 was tested and compared with unfermented dried duckweed. The results are shown in the table below:

[0079] As shown in the table above, after adopting the method of this application, the crude protein content of the fermented duckweed product increased, the crude fiber content decreased, and a large amount of lactic acid was accumulated, resulting in a significant improvement in nutritional quality.

[0080] Example 11 Fifty fattening pigs of similar weight were selected and randomly divided into two groups: Experimental group: 5% of the dry powder fermented duckweed feed obtained in Example 7 was added to the basal diet; Control group: fed a basal diet.

[0081] The experiment lasted 45 days, and the results are as follows:

[0082] Therefore, it can be seen that the fermented products prepared by the method of this application can significantly improve the growth performance and health status of animals when used as animal feed.

[0083] Although several specific embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are merely exemplary and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art are within the scope of protection claimed by the present invention.

Claims

1. A method of fermenting lemna with a complex probiotic formulation, characterized in that, It comprises the following steps: S1: mixing duckweed with auxiliary materials to obtain a culture medium, wherein the auxiliary materials comprise bran, corn flour, brown sugar, and inorganic salt; S2: adding a compound probiotic preparation comprising lactic acid bacteria and yeast into the culture medium and mixing uniformly to complete inoculation, thereby obtaining inoculated material; S3: sealing the inoculated material obtained in S2 to perform fermentation, thereby obtaining fermented material; S4: taking out the fermented material obtained in S3 to obtain a feed product.

2. The method of claim 1, wherein the method is characterized by, In S1, the culture medium comprises, by weight: 70-85 parts of duckweed, 10-20 parts of bran, 3-5 parts of corn flour, 1-2 parts of brown sugar, and 1-2 parts of potassium dihydrogen phosphate.

3. The method of claim 2, wherein the method is characterized by, In S1, the duckweed and the auxiliary materials are uniformly mixed according to a weight ratio, and then the water content of the material is adjusted to 55%-65%.

4. The method of claim 1, wherein the method is characterized by, The viable bacterial count ratio of the lactic acid bacteria to the yeast is (2-3):

1.

5. The method of claim 1, wherein the method is characterized by, The inoculation amount of the compound probiotic preparation is 0.5%-3.0% of the total weight of the culture medium.

6. The method of claim 1, wherein the method is characterized by, The total viable bacteria number of the compound probiotic preparation is not less than 3.0x10 10 CFU / g, the effective viable bacteria number of the lactic acid bacteria is ≥1.0x10 10 CFU / g, the effective viable bacteria number of the yeast bacteria is ≥1.0x10 9 CFU / g.

7. The method of claim 1, wherein the method is characterized by, In S3, after the inoculated material obtained in S2 is sealed, it is placed in an anaerobic or facultative anaerobic fermentation environment at 25-37℃ until the pH value of the material stabilizes at 4.0-4.5, thereby obtaining fermented material.

8. The method of claim 1, wherein the method is characterized by, In S3, the sealing of the inoculated material obtained in S2 comprises: loading the inoculated material obtained in S2 into a fermentation plastic bag, compacting layer by layer, excluding air, and then sealing.

9. The method of claim 1 to 8, wherein the method is characterized by, After S4, S5 is further included: drying the feed product obtained in S4 at 50-60℃ to a water content of less than 12%, crushing it with a crusher, and then passing it through a 40-60 mesh sieve to obtain a dry powder feed additive.

10. A Lemna fermentation product, characterized in that, The dry powder feed additive is prepared by any one of the methods in claims 1-9.

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