Selenium-rich product generation process based on cyclic utilization of pruned wild jujube branches

Abstract

The invention discloses a selenium-rich product generation process based on cyclic utilization of pruned wild jujube branches, and relates to the technical field of agricultural waste resource utilization. According to the technology, through a closed circulation system of cutting selenium enrichment, tender leaf harvesting, branch fermentation and fungus residue returning to the field, cutting treatment is conducted on pruned wild jujube branches through a nutrient solution containing 0.1%-0.2% of organic chelated selenium fertilizer, 30-45-degree oblique cutting and 2-4-hour soaking are adopted to promote selenium absorption, and selenium-enriched tender leaves with the selenium content being 0.075-0.3 mg / kg are obtained in cooperation with greenhouse temperature and humidity regulation and control; then branches are smashed into particles of 1-5 mm, 50%-60% of branch scraps, cottonseed hulls and sorghum straw are prepared into a substrate, 0.03%-0.08% of selenium-rich fungus powder is inoculated for edible fungus cultivation, the selenium content of fungus residues is increased to 0.08 mg / kg or above, and the proportion of organic selenium exceeds 85%; and finally, performing high-temperature composting at 55-65 DEG C to stabilize the selenium form, and returning to the field. According to the process, full-chain cyclic utilization of the selenium element is achieved, the selenium absorption efficiency of tender leaves is improved by 20% or above, the conversion rate of organic selenium in the mushroom dregs is remarkably improved, the comprehensive cost is reduced by 30%, meanwhile, incineration pollution is reduced, soil organic matter is increased by 18%-22%, and efficient utilization of resources and ecological protection benefits are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of agricultural waste resource utilization and functional agricultural product development, and in particular to a process for producing selenium-rich products based on the recycling of pruned branches of sour jujube. Background Art

[0002] The cultivation of hawthorn jujube produces a large number of pruned branches each year. Traditionally, these branches are mainly disposed of by incineration or discarding, which not only wastes biomass resources and pollutes the environment, but also leaves the recycling value of selenium untapped. Currently, the development of selenium-rich agricultural products relies on soil application or foliar spraying of selenium fertilizers. However, these methods suffer from low selenium absorption efficiency, a high risk of inorganic selenium residues, and difficulties in cost control. For example, sodium selenite can easily cause excessive selenium levels in the soil, while organic selenium fertilizers are expensive and difficult to promote. At the same time, the development of hawthorn jujube leaves as high-value-added selenium-rich products (such as tea and green powder) lacks efficient technology. Conventional cuttings and seedling cultivation rely on a rooting and planting process, which has a long cycle and unstable selenium absorption efficiency. Existing technologies for resource utilization of Chinese jujube branches are largely limited to primary composting or fuel applications. While some research has explored the use of agricultural and forestry waste in edible fungus cultivation, targeted selenium conversion technologies have yet to achieve breakthroughs. Conventional mushroom residue return to the field uses selenium primarily in an inorganic form, which is easily leached or converted to toxic forms, leading to secondary pollution risks. Furthermore, fermentation processes lack control over the microbial metabolic pathways of selenium, resulting in a generally lower selenium content in mushroom residue than 0.05 mg / kg, failing to meet the standard for selenium-rich organic fertilizers (≥0.1 mg / kg). Furthermore, while existing technologies can increase selenium content in mycelium through the addition of exogenous selenium-enhancing agents, this relies on the cost of purchasing additional strains and fails to form a closed loop with upstream agricultural waste selenium resource utilization. Given these challenges, an innovative process is urgently needed that can achieve efficient selenium absorption and conversion through a low-cost, safe technical approach while also establishing a closed-loop system for Chinese jujube branches: "plant absorption, microbial metabolism, and soil return." The present invention proposes the "selenium absorption of nutrient solution for jujube cuttings + selenium conversion in fungus residue" process, which introduces organic selenium in a targeted manner during the cutting stage and harvests selenium-rich young leaves. It combines the synergistic effect of branch crushing and fermentation with specific microbial flora, breaking through the traditional separation model of selenium-rich production and waste resource utilization, realizing the full-chain recycling of selenium elements, and providing a new path for selenium-rich functional agriculture. Summary of the Invention

[0003] The present invention provides a process for producing a selenium-enriched product based on the recycling of pruned jujube branches. The process comprises the following steps: (a) subjecting the jujube branches to a selenium-containing nutrient solution for cutting and harvesting the selenium-enriched young leaves; (b) crushing and fermenting the harvested branches to form a culture medium for edible fungi; and (c) returning the selenium-containing fungus residue to the field. This process achieves efficient resource utilization of pruned jujube branches and a closed cycle of selenium, addressing the resource waste caused by traditional incineration and the low absorption efficiency and high cost of selenium enrichment technologies.

[0004] Furthermore, 0.1%-0.2% by weight of organic chelated selenium fertilizer is added to the selenium-containing nutrient solution to stabilize the selenium element form through chemical chelation, avoid the risk of inorganic selenium residue, and significantly improve the selenium absorption efficiency of young leaves, ensuring that the selenium content of the finished product meets national standards.

[0005] Furthermore, a 2-4 hour soaking time and a 30-45° oblique cutting angle at the base of the branches were used in the cutting treatment to promote the rapid migration of selenium to the young leaf tissue by expanding the contact area of the xylem and the osmotic pressure difference, shortening the pretreatment period and reducing the amount of nutrient solution used.

[0006] Furthermore, the selenium-rich young leaves are dried at a low temperature of 40-60°C, which can retain the active ingredients of chlorophyll and flavonoids to the maximum extent while ensuring that the selenium content in the leaves reaches a stable level of 0.075-0.3 mg / kg, meeting the processing requirements of selenium-rich tea / green powder.

[0007] Furthermore, the greenhouse environmental control system maintains a temperature of 25-30℃ and a humidity of 70%-80%, and combines drip irrigation to simultaneously supply nitrogen, phosphorus, potassium and selenium, thereby regulating plant cell activity while inhibiting mold growth and ensuring that selenium absorption efficiency is increased by more than 20%.

[0008] Furthermore, the cultivation medium (3) adopts a ratio of 50-60% of jujube branch chips, 15-25% of cottonseed husks, 8-12% of sorghum straw, and 0.5-1.5% of lime. By optimizing the carbon-nitrogen ratio and pore structure, the mycelium colonization efficiency is improved and the degradation of lignocellulose is accelerated, creating a suitable environment for microbial selenium conversion.

[0009] Furthermore, by inoculating 0.03%-0.08% of the total mass of the matrix with selenium-rich bacterial powder (such as selenium-rich yeast or Bacillus), the organic chelated selenium remaining in the branches is converted into bacterial protein selenium through mycelial metabolism, and the selenium content of the bacterial residue is increased to more than 0.08 mg / kg and the proportion of organic selenium exceeds 85%.

[0010] Furthermore, by selecting fungi with strong selenium tolerance such as Hericium erinaceus and Agrocybe edulis, and cultivating them at a cultivation temperature of 20-28°C and a humidity of 65-80%, the mycelium can be efficiently enriched with selenium and the biomass growth is not inhibited, and the single-crop cultivation cycle is shortened to less than 35 days.

[0011] Furthermore, the branches are crushed into 1-5mm particles and fermented for 20-35 days. By controlling the particle size and optimizing the fermentation cycle, the decomposition rate of lignocellulose is increased by more than 40%, while the selenium element bound in the branches is released for use by microorganisms.

[0012] Furthermore, the mushroom residue is composted at 55-65°C for 5-12 days before being returned to the field to completely inactivate pathogens and grass seeds, and stably convert the residual selenium into an organic form that can be used by plants, avoiding soil pollution caused by selenium leaching or accumulation of toxic forms.

[0013] The present invention realizes the closed-loop recycling of selenium resources in jujube branches through the full-chain process of "selenium-enriched cuttings - harvesting of young leaves - fermentation of branches - returning of fungus residue to the field". Through greenhouse environment regulation and directional introduction of organic chelated selenium fertilizer, the selenium absorption efficiency of young leaves is increased by more than 20%, the selenium content is stably up to the national standard requirements, and the low-temperature drying process retains active ingredients such as chlorophyll. After the branches are crushed and fermented, selenium-tolerant bacteria are inoculated to increase the organic selenium conversion rate of the fungus residue, and the selenium content exceeds 0.08 mg / kg. It is then converted into a stable organic state that can be used by plants through high-temperature composting at 55-65°C, eliminating the risk of toxicity while increasing soil organic matter by 18%-22%. This process forms a virtuous cycle of "waste → high-value products → soil improvement" through the recycling of endogenous selenium and the self-sufficiency of fungus residue matrix, and has the multiple benefits of reducing agricultural costs and increasing efficiency, protecting the ecology, and increasing the value of selenium-rich agricultural products. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Generate a process flow diagram for a selenium-enriched product based on the recycling of pruned branches from Ziziphus jujuba.

[0015] Figure 2 The present invention is an operational flow chart of a process for producing selenium-rich products based on the recycling of pruned branches of sour jujube. DETAILED DESCRIPTION

[0016] For ease of understanding of the present application, the present application will be described more fully below. The present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0017] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. In the description of this application, the meaning of "several" is at least one, such as one, two, etc., unless otherwise clearly and specifically defined.

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0019] In this application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0020] In this application, when referring to numerical ranges, unless otherwise specified, the numerical ranges are considered continuous and include the minimum and maximum values of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges subsumed therein.

[0021] Unless otherwise specified, the percentage contents mentioned in this application refer to mass percentage for solid-liquid mixture and solid-solid mixture, and refer to volume percentage for liquid-liquid mixture.

[0022] The percentage concentrations mentioned in this application, unless otherwise specified, refer to the final concentration. Final concentration refers to the percentage of an added ingredient in the system after the addition of that ingredient.

[0023] The temperature parameters in this application, unless otherwise specified, allow for both constant temperature treatment and treatment within a certain temperature range. Constant temperature treatment allows for temperature fluctuations within the precision range of instrument control.

[0024] The "particles" mentioned in this application, or materials with a defined particle size distribution, are not necessarily spherical in shape but may be irregular, primary or secondary. The particle size of irregular particles is the average of their maximum and minimum diameters.

[0025] To make the purpose, technical solutions and advantages of the examples of the present application clearer, the technical solutions in the examples of the present application will be described clearly and completely below. Where specific conditions are not specified in the examples, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially. Example

[0026] During the selenium-enriched cutting treatment, one-year-old jujube cuttings with a diameter of 0.8-1.2 cm were selected and cut at a 40-degree angle at the base to increase the contact area with the wood. The cuttings were then immersed in a nutrient solution containing 0.15% selenomethionine (selenomethionine) for three hours. The greenhouse temperature was maintained at 28±2°C, the humidity at 75±5%, and the pH at 8.5±0.5. Drip irrigation was used to deliver a compound fertilizer with an 18-6-12 ratio of nitrogen, phosphorus, and potassium, along with a 0.1 mg / L selenium solution, ensuring uniform penetration of the nutrient solution into the branches. Three leaves and one heart of young jujube shoots were collected and dried at 60°C. The selenium content of the young leaves was determined to be 0.22 mg / kg.

[0027] In the subsequent stage, the harvested branches were processed into 2 mm particles by a double-shaft crusher and mixed with 55% jujube branch chips, 20% cottonseed husks with a moisture content of ≤12% after pretreatment, 10% sorghum straw crushed to 3-5 mm, and 1.5% lime adjusted to a pH of 6.5-7.0 to form a high-efficiency cultivation medium with a porosity of 35-40%. The number of viable bacteria inoculated was ≥1×10 8 Selenium-enriched Bacillus powder (CFU / g) was added at a rate of 0.06% of the total substrate mass. Hericium erinaceus was cultivated in a constant-temperature incubator at 22±2°C and 75% humidity. After 28 days of fermentation, the selenium content of the residue increased to 0.15 mg / kg. Continuous extraction analysis showed that organic selenium accounted for 90% of the total selenium. The residue was then composted at 60±2°C for 10 days, with the compost turned twice daily. The soil's available selenium (organic selenium) content increased from an initial 0.02 mg / kg to 0.08 mg / kg. Example

[0028] Compared with Example 1, the difference of this embodiment is that the concentration of selenomethionine in the organic chelated selenium nutrient solution is 0.1%, the immersion time is extended to 4 hours, and the angle of the branch base is 30°. The greenhouse environment is set at a temperature of 25±1°C, a humidity of 70±3%, and a pH of 7.0±0.2, and the selenium concentration of drip irrigation is maintained at 0.1 mg / L. The experimental results show that the selenium content of young leaves reaches the national standard lower limit of 0.075 mg / kg.

[0029] During the mushroom cultivation phase, the substrate ratio was adjusted to 50% jujube branch cuttings, 25% cottonseed husks, 12% sorghum straw, and 0.5% lime to control the pH to 6.0-6.5. Hericium erinaceus was cultivated in a constant temperature incubator at 20±1°C and 65±3% humidity. After 28 days of fermentation, the selenium content of the residue was determined by atomic fluorescence spectrometry to be 0.08 mg / kg, and organic selenium content was 82% by continuous extraction. During the composting phase, the soil was treated at 55±2°C for 7 days, increasing the available selenium content to 0.06 mg / kg. Example

[0030] Compared to Example 1, the following parameters were modified in this example: the soaking time was shortened to 2 hours, the shearing angle was increased to 45°, and the greenhouse temperature was raised to 30±2°C, the humidity to 80±5%, and the pH to 10.0±0.5 (strongly alkaline conditions). Experiments showed that the selenium content in young leaves reached as high as 0.30 mg / kg, and the selenium utilization rate in the nutrient solution increased to 32%, indicating that the strongly alkaline environment may promote selenium absorption by enhancing ion exchange.

[0031] Ultrafine grinding of the branches to 1 mm particles increased their specific surface area by 50%, shortening the fermentation cycle to a minimum of 20 days. Inoculation with 0.08% selenium-enriched yeast powder increased the selenium content of the residue to 0.18 mg / kg, with organic selenium accounting for 88%. During the composting phase, high-temperature treatment at 65 ± 2°C for 5 days increased the available selenium content in the soil from an initial 0.02 mg / kg to 0.10 mg / kg.

[0032] Comparative Example 1: (Traditional foliar spraying) A 0.2% sodium selenite inorganic selenium solution was sprayed directly onto the leaves of the wild jujube tree using traditional foliar spraying techniques, without using pruned branches. The results showed that the selenium content in young leaves, as measured by atomic absorption spectrometry, was only 0.04 mg / kg, with an absorption efficiency of 10%.

[0033] Comparative Example 2: (Directly cut branches + inorganic selenium nutrient solution) Straight-cut branches without oblique pruning were soaked in 0.2% sodium selenite nutrient solution for 1 hour, and the greenhouse conditions were the same as in Example 1. The results showed that the selenium content in young leaves was as low as 0.02 mg / kg. The selenium penetration rate was low due to insufficient contact area in the wood. Selenium-enriched fungus powder was not inoculated during the preparation of the fungus residue, and selenium was in the form of inorganic Se. 4+ The effective selenium content is only 0.01 mg / kg, which does not meet the standards of selenium-rich organic fertilizer.

[0034] Comparative Example 3: The difference from Example 1 was that the branches were crushed into 10 mm particles, shortening the fermentation period to 15 days. Results showed that insufficient porosity hindered mycelial extension, reducing mycelial colonization. The selenium content of the residue was only 0.03 mg / kg, with unconverted organic selenium accounting for 60%.

[0035] Table 1: Comparison of key indicators of Example 1, Example 2, Example 3, and Comparative Example 1 index Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Selenium content in young leaves (mg / kg) 0.22 0.075 0.30 0.04 0.02 Selenium content in fungus residue (mg / kg) 0.15 0.08 0.18 - 0.01 Please refer to Table 1. Experimental data show that the optimized selenium-enriched cutting treatment of sour jujube (selenium fertilizer concentration 0.1%-0.2%, oblique shearing 30-45°) increased the selenium content of young leaves from 0.02-0.05 mg / kg to 0.075-0.30 mg / kg compared with the traditional straight-cut selenium-free soaking process (Comparative Example 1) or the straight-cut inorganic selenium nutrient solution soaking process (Comparative Example 2), effectively exceeding the national standard threshold for selenium-enriched food (0.075 mg / kg); in the mushroom cultivation stage, the inoculation ratio of 0.03%-0.08% selenium-enriched fungus powder increased the selenium enrichment of the mycelium by 1.5-2 times compared with conventional cultivation; through high-temperature composting closed-loop circulation technology, the effective selenium content in the soil after treatment was increased to 0.08 mg / kg, which can significantly increase the effective selenium content in the soil.

[0036] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0037] The above embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A process for producing selenium-rich products based on the recycling of pruned branches of sour jujube, characterized in that The key steps include: (a) treating the branches of wild jujube with a selenium-containing nutrient solution and harvesting the selenium-rich young leaves; (b) crushing and fermenting the harvested branches into a culture medium for edible fungi; (c) Returning selenium-containing fungus residue to the field after cultivation.

2. The process according to claim 1, characterized in that: The selenium-containing nutrient solution in step (a) contains 0.1%-0.2% by mass of organic chelated selenium fertilizer.

3. The process according to claim 1, characterized in that: The soaking time of the cutting treatment in step (a) is 2-4 hours, and the oblique cutting angle of the branch base is 30-45 degrees.

4. The process according to claim 1, wherein: The selenium content of the selenium-rich young leaf product harvested in step (a) is 0.075-0.3 mg / kg after being dried at 40-60° C.

5. The process according to claim 1, characterized in that: In step (a), the greenhouse temperature is controlled at 25-30° C. and the humidity is controlled at 70%-80% by an environmental control system; and nitrogen, phosphorus, potassium and selenium are supplied synchronously by drip irrigation.

6. The process according to claim 1, characterized in that: The cultivation medium in step (b) is composed of jujube branch chips, cottonseed husks, sorghum straw and lime, and the mass ratio thereof is 50-60%:15-25%:8-12%:0.5-1.5%.

7. The process according to claim 1, characterized in that: The cultivation substrate in step (b) needs to be inoculated with selenium-enriched bacterial powder, and the amount of bacterial powder added is 0.03%-0.08% of the total mass of the substrate. The bacterial powder is selenium-enriched yeast or selenium-enriched Bacillus.

8. The process according to claim 1, characterized in that: The edible fungus cultivation strain in step (b) is Hericium erinaceus, Agrocybe chaxini or Grifola frondosa, and the cultivation temperature is controlled at 20-28° C. and the humidity is 65-80%.

9. The process according to claim 1, characterized in that: The particle size of the branches after being crushed in step (b) is 1-5 mm, and the fermentation period is 20-35 days.

10. The process according to claim 1, characterized in that: In step (c), the mushroom residue is composted before being returned to the field, the composting temperature is 55-65° C., and the composting duration is 5-12 days.

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