Black highland barley in-situ selenium enrichment method capable of keeping seed integrity and application

Abstract

The invention belongs to the technical field of agricultural product selenium biological enhancement and seed postharvest treatment, and discloses a black highland barley in-situ selenium enrichment method capable of keeping seed integrity and application, and the method comprises the steps of highland barley raw material selection, cleaning, screening, temperature and humidity pretreatment, high-temperature enhancement, selenium solution soaking, temperature-controlled drying and finished product preparation. According to the method, the highland barley is subjected to non-germinating selenium biological enhancement by adopting a technology of combining temperature and humidity co-excitation with selenium solution treatment, so that the content and the conversion rate of organic selenium in the highland barley are remarkably improved, meanwhile, the complete structure of seeds is effectively maintained, the processing efficiency is improved, and nutrient loss and quality deterioration caused by traditional germination treatment are reduced.

Description

Technical Field

[0001] This invention belongs to the field of selenium biofortification of agricultural products and postharvest seed treatment technology, and in particular, a method for in-situ selenium enrichment of black barley while preserving seed integrity and its application. Background Technology

[0002] Selenium, an essential trace element for maintaining normal physiological functions, plays a crucial role in antioxidation, immune regulation, and metabolic balance. Due to the biotoxicity risks of inorganic selenium, converting it into organic forms through crops has become a safe and effective dietary selenium supplementation method. Highland barley, a specialty grain of the Qinghai-Tibet Plateau, is rich in β-glucan, dietary fiber, and polyphenols, making it an ideal carrier for selenium biofortification. Existing research indicates that appropriate selenium fortification processes can significantly increase the organic selenium content in highland barley, with organic forms such as selenocysteine ​​and selenomethionine exhibiting higher bioavailability and safety.

[0003] Highland barley, a unique grain resource of the Qinghai-Tibet Plateau, is rich in β-glucan, dietary fiber, and polyphenols, possessing unique nutritional value and health benefits. In recent years, with the increasing demand for functional grains, the market potential of highland barley products has become increasingly apparent. However, the selenium content in ordinary highland barley is generally low, failing to meet the human body's daily selenium requirements. Therefore, conducting research on selenium biofortification of highland barley has significant practical implications.

[0004] Currently, there are three main approaches to selenium fortification technology in highland barley: agricultural cultivation fortification achieves selenium enrichment by applying selenium fertilizer during the growth cycle, but this is greatly affected by environmental factors and has a long cycle; germination conversion method promotes selenium form conversion during seed germination, but this can lead to damage to grain structure and loss of processing adaptability; post-harvest soaking method, although simple to operate, suffers from technical bottlenecks such as low selenium absorption efficiency and insufficient organic selenium conversion rate. It is worth noting that a non-germination selenium fortification strategy, by precisely controlling temperature and humidity parameters to activate seed metabolic enzyme systems, can achieve efficient selenium conversion while maintaining grain integrity. This provides a new technical approach for developing high-quality selenium-enriched highland barley products.

[0005] Current barley processing technologies suffer from several drawbacks. Traditional drying methods, such as sun-drying and shade-drying, suffer from long production cycles, difficulty in controlling hygiene, and loss of nutrients. While hot air drying is convenient for industrial applications, it does not adequately protect functional components. Vacuum freeze-drying, although it can better maintain quality, has high equipment investment and energy consumption costs. It is particularly important to note that existing technologies lack the ability to target and regulate the form of organic selenium in barley, making it difficult to achieve efficient enrichment of selenoamino acids. Furthermore, they generally neglect the preservation of grain structure integrity and flavor characteristics.

[0006] In summary, existing selenium fortification technologies for highland barley have the following main shortcomings: First, traditional fortification methods generally achieve organic selenium conversion rates below 40%, and cannot simultaneously maintain grain integrity and nutrient retention; second, existing process parameter control is rudimentary, leading to significant batch-to-batch quality fluctuations; third, some innovative methods require advanced equipment and consume large amounts of energy, making them difficult to meet the needs of industrial-scale promotion. Therefore, developing a highland barley selenium fortification technology that can achieve efficient selenium conversion, maintain grain characteristics, and is suitable for large-scale production has become a critical issue that urgently needs to be addressed in this field.

[0007] The search revealed the following patent publications related to this invention's patent application: Comparison Patent 1: To address the problems of low organic selenium conversion rate and damaged seed integrity in existing grain selenium fortification technologies, the patent "A Method for Preparing Selenium-Enriched Germinated Brown Rice (CN116391826A)" provides a selenium fortification scheme that combines exogenous vegetable extracts with germination treatment. The patent specifically includes the following steps: Fresh, high-quality brown rice is selected, cleaned, and then soaked in a vegetable extract solution prepared from raw materials such as matsutake mushrooms, dried white mushrooms, and wood ear fungus, allowing the organic selenium components in the extracts to penetrate into the rice grains; subsequently, germination treatment is carried out at 26℃ and 75% humidity; when the sprouts reach 1-2 mm in length, enzymes are inactivated using 70℃ hot water; finally, the rice is sterilized by a combination of ozone and ultraviolet light, and dried under 40℃ hot air conditions to obtain selenium-enriched germinated brown rice.

[0008] The technical defects of the patent document (CN116391826A) are as follows: (1) The method relies on selenium-rich natural vegetable extracts as selenium sources. The selenium content is greatly affected by factors such as the origin of raw materials and season, resulting in insufficient stability of the selenium content of the final product; (2) Although germination treatment can enhance the active ingredients such as γ-aminobutyric acid, it leads to the destruction of seed structure and loss of complete seed morphology, which seriously affects the product's storage performance and subsequent processing adaptability; (3) The process route is complex, involving multiple links such as extract preparation, germination control, and multiple sterilization. The production cost is high and the quality control is difficult, which restricts its industrialization and promotion.

[0009] Comparison Patent 2: To address the problems of poor selenium tolerance and low organic selenium conversion efficiency in existing highland barley selenium fortification technologies, the patent "A planting method for high-selenium-tolerant highland barley and a cultivation method for highland barley malt (CN112956380A)" provides a comprehensive solution through long-term domestication combined with germination treatment. This patent employs a 7-8 year cultivation cycle, gradually increasing the concentration of sodium selenite application annually (from 35 mg / kg to 65-85 mg / kg) to acclimate highland barley to selenium tolerance. After obtaining high-selenium-tolerant highland barley seed sources, further soaking, germination, and soilless cultivation are performed using an enzyme-based sodium selenite solution (containing 120 mg / kg of selenium) to ultimately obtain selenium-enriched highland barley malt products.

[0010] The technical defects of the patent document (CN112956380A) are as follows: (1) The method requires a breeding cycle of 7-8 years, which is extremely time-consuming and cannot meet the needs of rapid industrialization. In addition, changes in environmental factors during this process may lead to unstable breeding results; (2) Although germination treatment can obtain a high organic selenium content, it destroys the integrity and original morphology of the seeds, causing the product to lose the basic characteristics of barley grains and seriously affecting its applicability as a grain raw material; (3) The process route involves multiple complex operations of field breeding and indoor germination over many years, making quality control difficult, production costs high, and making it difficult to achieve large-scale stable production.

[0011] Traditional highland barley selenium fortification technology faces three major challenges: First, agricultural cultivation methods are limited by long production cycles, strong regionality, and unstable selenium content, making it difficult to achieve standardized production. Second, although germination conversion can increase organic selenium content, it irreversibly damages seed structure, leading to a shortened product shelf life and altered processing characteristics, severely limiting its application in mainstream grain products. Third, existing post-harvest treatment methods, such as direct soaking, suffer from low selenium absorption efficiency and an organic selenium conversion rate of less than 40%, and are prone to microbial contamination and quality deterioration.

[0012] While existing physical-assisted techniques can partially improve selenium absorption efficiency, they are difficult to scale up due to high equipment investment, high energy consumption, and complex processes. A deeper technical challenge lies in the fact that existing methods fail to achieve precise control over seed metabolic state—either fully activating seed metabolism leading to germination or failing to effectively initiate selenium conversion pathways. This technical deficiency makes it consistently difficult to simultaneously achieve the two core requirements of "high organic selenium conversion rate" and "seed structural integrity" in barley selenium fortification.

[0013] This invention aims to break through this technological deadlock by establishing a new non-germination-based enhancement pathway based on the coordinated regulation of temperature and humidity. This pathway enables the efficient conversion of inorganic selenium to organic selenium while maintaining the integrity and processing characteristics of highland barley seeds, ultimately overcoming the industrial challenge of "quality preservation and nutritional enhancement being mutually exclusive." Summary of the Invention

[0014] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method and application for in-situ selenium enrichment of black barley while preserving seed integrity.

[0015] The technical solution adopted by this invention to solve its technical problem is: A method for in-situ selenium enrichment of black barley while preserving seed integrity, the method comprising barley raw material selection, cleaning, screening, temperature and humidity pretreatment, high temperature intensification, selenium solution soaking, temperature-controlled drying, and finished product preparation.

[0016] Furthermore, the specific steps are as follows: (1) Raw material selection: Select black barley seeds, requiring plump grains, no disease, no mold, and uniform grain size of the current year's new seeds; (2) Cleaning and screening: Use running water to clean the impurities on the surface of the barley seeds, and remove floating and broken grains; (3) Temperature and humidity pretreatment: Selected highland barley seeds were placed in a constant temperature and humidity chamber and treated for 48 hours at 35-40℃ and 40-60% relative humidity to activate seed metabolic activity; (4) High temperature enhancement: The pretreated seeds were transferred to an environment of 70-76℃ and treated for 120 hours while maintaining a relative humidity of 40-60% to enhance seed permeability; (5) Selenium solution soaking: Take high-temperature enhanced barley seeds and soak them in sodium selenite solution at 28-32℃ for 12 hours. The concentration of selenium in the sodium selenite solution is 30-160 μM. (6) Temperature-controlled drying: The soaked seeds are dried at 35-40℃ and 40-60% relative humidity for 30 hours to complete the fixation and transformation of selenium; (7) Preparation of finished product: freeze-dry the dried barley seeds for 36 hours, pulverize them and pass them through a 100-mesh sieve to obtain selenium-enriched barley powder.

[0017] Steps (1) to (4) are the optimization processing stage.

[0018] Furthermore, the black barley seeds in step (1) are Longzi black barley seeds.

[0019] Furthermore, the average protein content of the Longzi black highland barley seeds is 9.40%, the fat content is 2.32%, the crude fiber content is 3.01%, and the total dietary fiber content is 4.56%. It is also rich in 0.06% anthocyanins, 5-8% β-glucan, and 0.3-0.6% polyphenols. In addition, its calcium, magnesium, and iron mineral content is outstanding, ranging from 0.15% to 0.25%.

[0020] Furthermore, in step (5), the concentration of selenium in the sodium selenite solution is 160 μM.

[0021] Furthermore, the conditions for neutron freeze drying in step (7) are: -40℃, vacuum degree 0-20 Pa.

[0022] The application of the method described above in seed selenium enrichment.

[0023] The advantages and positive effects of this invention are as follows: 1. This invention employs a combination of temperature and humidity co-excitation and selenium solution treatment to perform non-germinating selenium biofortification on barley. This not only significantly increases the content and conversion rate of organic selenium in barley, but also effectively maintains the integrity of the seed structure, improves processing efficiency, and reduces nutrient loss and quality deterioration caused by traditional germination treatment.

[0024] 2. The organic selenium content in highland barley treated by the process of this invention is significantly increased, reaching 93% under optimal conditions, providing reliable technical support for the development of high-value-added selenium-enriched highland barley products.

[0025] 3. The selenium-enriched highland barley products produced using the technology of this invention not only have significantly improved nutritional value, but also maintain their original flavor characteristics and processing quality. They are highly adaptable to subsequent processing, have strong product competitiveness, and possess broad market prospects and economic value.

[0026] 4. The key to this invention lies in the synergistic effect of precise control of temperature and humidity parameters and selenium treatment conditions, which enables metabolic activation and efficient selenium conversion of barley seeds while preserving seed integrity. This not only maintains the complete structure and original flavor of the seeds but also significantly increases the organic selenium content, providing reliable technical support for the development of high-quality selenium-enriched barley products.

[0027] 5. This invention is a selenium bio-enhancing processing technology for highland barley. This technology uses a temperature and humidity co-excitation assisted selenium conversion method, and scientifically configures key parameters such as pretreatment temperature, humidity, time and selenium solution concentration, so as to significantly increase the organic selenium content while maintaining the integrity of barley seeds.

[0028] 6. This invention regulates seed dormancy by temperature and humidity, and combines this with selenium solution soaking treatment to achieve selenium enrichment and efficient conversion of organic selenium while preserving seed integrity.

[0029] 7. The key to this invention lies in the synergistic effect of precisely controlling temperature and humidity parameters and selenium treatment conditions to achieve metabolic activation and efficient selenium conversion in barley seeds while preserving seed integrity. This maintains the seed's intact structure and original flavor while significantly increasing the organic selenium content, providing reliable technical support for the development of high-quality selenium-enriched barley products. Attached Figure Description

[0030] Figure 1 This is a process flow diagram of selenium-enriched barley in this invention; Figure 2 This is a graph showing the effect of different sodium selenite concentrations at different treatment stages on the total selenium content in highland barley during this invention. Figure 3 This is a graph showing the effect of different sodium selenite concentrations at different times during the drying stage after soaking in the optimized treatment of this invention on the total selenium content in highland barley. Figure 4 This diagram illustrates the effect of different sodium selenite concentrations at different treatment stages on the selenium speciation in highland barley during the present invention. In this diagram, A represents the effect of different sodium selenite concentrations at stage Bz and stage Bw on the selenium speciation in highland barley, and B represents the effect of different sodium selenite concentrations at stage Bd on the selenium speciation in highland barley. Figure 5 This diagram illustrates the effect of different processing stages on the surface morphology of highland barley in this invention. Figure 6 This is a radar response diagram for the electronic nose detecting volatiles in this invention; where A is the radar response diagram for the electronic nose detecting volatiles in the Bz stage, and B is the radar response diagram for the electronic nose detecting volatiles in the Bd stage. Detailed Implementation

[0031] The present invention will be further described below with reference to the embodiments. The following embodiments are descriptive and not limiting, and should not be used to limit the scope of protection of the present invention.

[0032] The various experimental operations involved in the specific embodiments are all conventional techniques in the art. For parts not specifically annotated herein, those skilled in the art can refer to various commonly used reference books, scientific and technological literature, or related instructions and manuals prior to the filing date of this invention for implementation. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art, and the raw materials used are all commercially available products.

[0033] A selenium biofortification processing technology for highland barley includes steps such as barley raw material selection, washing, screening, temperature and humidity pretreatment, high-temperature fortification, selenium solution soaking, temperature-controlled drying, and finished product preparation. The total selenium content is then determined by ICP-MS, and the selenium speciation distribution is analyzed by HPLC-ICP-MS. Further, the specific steps are as follows: (1) Raw material selection: Select black barley seeds, requiring plump grains, no disease, no mold, and uniform grain size of the current year's new seeds; (2) Cleaning and screening: Use running water to clean the impurities on the surface of the barley seeds, and remove floating and broken grains; (3) Temperature and humidity pretreatment: Selected highland barley seeds were placed in a constant temperature and humidity chamber and treated for 48 hours at 35-40℃ and 40-60% relative humidity to activate seed metabolic activity; (4) High temperature enhancement: The pretreated seeds were transferred to an environment of 70-76℃ and treated for 120 hours while maintaining a relative humidity of 40-60% to enhance seed permeability; (5) Selenium solution soaking: Take high-temperature enhanced barley seeds and soak them in sodium selenite solution at 28-32℃ for 12 hours. The concentration of selenium in the sodium selenite solution is 30-160 μM. (6) Temperature-controlled drying: The soaked seeds are dried at 35-40℃ and 40-60% relative humidity for 30 hours to complete the fixation and transformation of selenium; (7) Preparation of finished product: freeze-dry the dried barley seeds for 36 hours, pulverize them and pass them through a 100-mesh sieve to obtain selenium-enriched barley powder.

[0034] Steps (1) to (4) are the optimization processing stage.

[0035] Furthermore, the black barley seeds in step (1) are Longzi black barley seeds.

[0036] Furthermore, the average protein content of the Longzi black highland barley seeds is 9.40%, the fat content is 2.32%, the crude fiber content is 3.01%, and the total dietary fiber content is 4.56%. It is also rich in 0.06% anthocyanins, 5-8% β-glucan, and 0.3-0.6% polyphenols. In addition, its calcium, magnesium, and iron mineral content is outstanding, ranging from 0.15% to 0.25%.

[0037] Furthermore, in step (5), the concentration of selenium in the sodium selenite solution is 160 μM.

[0038] Furthermore, the conditions for neutron freeze drying in step (7) are: -40℃, vacuum degree 0-20 Pa.

[0039] The application of the method described above in seed selenium enrichment.

[0040] Specifically, the relevant preparation and testing methods are as follows: Example 1: See Figure 1The seeds of Longzi black highland barley were selected, with an average protein content of 9.40%, fat content of 2.32%, crude fiber content of 3.01%, and total dietary fiber content of 4.56%. They are also significantly rich in anthocyanins (0.06%), β-glucan (5-8%), and polyphenols (0.3-0.6%). Furthermore, they are rich in minerals such as calcium, magnesium, and iron, with a content of 0.15-0.25%. This results in a unique nutritional combination with cholesterol-lowering, blood sugar-regulating, and antioxidant functions. The seeds must be plump, free from disease and mold, and of uniform size. Surface impurities are removed by rinsing with running water. After washing, broken and floating grains are removed by screening, followed by the following treatment: Blank control group (B0): carefully selected highland barley seeds stored in a 0℃ cold storage; Direct soaking group (Bz): 50 g of selected highland barley seeds were directly soaked in sodium selenite solutions of 0, 40, 80, 120, and 160 μmol / L at 28-32℃ for 18 hours, respectively. After that, they were rinsed 3 times to remove surface selenium, and the Bz group samples were obtained as Bz-1, Bz-2, Bz-3, Bz-4, and Bz-5, respectively. Bz-1 was the experimental control group.

[0041] Temperature and humidity treatment group (Bw): 50 g of selected highland barley seeds were placed in an environment of 35-40℃ and 40-60% relative humidity for 48 hours, and then placed in an environment of 70-76℃ and 40-60% relative humidity for 120 hours. Subsequently, they were soaked in sodium selenite solutions of 0, 40, 80, 120, and 160 μmol / L at 28-32℃ for 18 hours respectively. After that, they were rinsed 3 times to remove surface selenium, and the Bw group samples were obtained, namely Bw-1, Bw-2, Bw-3, Bw-4, and Bw-5, among which Bw-1 was the experimental control group.

[0042] Complete treatment group (Bd): Samples from the Bw stage were dried at 35-40℃ and 40-60% relative humidity for 30 hours to obtain samples from the Bd group, namely Bd-1, Bd-2, Bd-3, Bd-4, and Bd-5, where Bd-1 served as the experimental control group. Samples from the Bd group were then dried for an additional 60 hours to obtain Bd-60 h.

[0043] All samples were freeze-dried for 36 hours, then pulverized and passed through a 100-mesh sieve. The total selenium content was determined by ICP-MS. 0.2000±0.01 g of barley powder sample was accurately weighed and placed in a microwave digestion tube. 600 μL of concentrated nitric acid was added, and the sealed digestion tube was placed in a microwave digester. A gradient temperature digestion program was set: first, the temperature was raised to 130℃ and held for 10 minutes, then further raised to 210℃ and held for 45 minutes to complete the digestion. After digestion, the digestion tube was allowed to cool to room temperature, and the digest was transferred with deionized water and diluted to a 50 mL volumetric flask. The concentration of selenium in the digestion solution was determined by inductively coupled plasma mass spectrometry (ICP-MS). The selenium content in the barley sample was calculated using the formula Se = ((Csample - Cblank) × V) / m, where Se represents the selenium content (mg / kg), Csample is the measured value of the sample on the instrument, Cblank is the measured value of the blank control on the instrument (no sample was added, only 600 μL of concentrated nitric acid was added), V is the final volume (L), and m is the sample mass (g).

[0044] The results show that ( Figure 2 The total selenium content of sample Bz-5 reached 7.95 mg / kg, a 43-fold increase compared to the control group (Bz-1); the total selenium content of sample Bw-5 reached 9.10 mg / kg, an 89-fold increase compared to the control group (Bw-1); and the total selenium content of sample Bd-5 reached 13.67 mg / kg, a 350-fold increase compared to the control group (Bd-1), a 0.7-fold increase compared to Bz-5, and a 0.5-fold increase compared to Bw-5. This indicates that the complete three-stage treatment process can significantly improve selenium enrichment efficiency. The effect of Bd-60 h was similar to that of Bd (…). Figure 3 Therefore, drying for 30 hours was chosen as the optimal drying time. The total selenium content was significantly increased in all three stages compared to the control group, with the most significant increase observed in the Bd stage.

[0045] It can also be seen that the two steps in the method of the present invention, namely "selecting 50 g of highland barley seeds and treating them in an environment of 35-40℃ and 40-60% relative humidity for 48 hours, and then treating them in an environment of 70-76℃ and 40-60% relative humidity for 120 hours" and "drying the sample in an environment of 35-40℃ and 40-60% relative humidity for 30 hours", have a significant synergistic effect and can synergistically increase the total selenium content in highland barley seeds.

[0046] Example 2: To accurately analyze the speciation of selenium in the samples prepared in Example 1, high-performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICP-MS) was used. The specific analytical steps included: accurately weighing 0.5 g of barley powder sample into a centrifuge tube, adding 60 mg of protease XIV and 30 mg of lipase, adding 10 mL of Tris-HCl buffer (pH 7.5), mixing well, and then ultrasonically extracting for 30 minutes in a 37°C ultrasonic cleaner. Subsequently, the sample was incubated in the dark at 37°C and 150 r / min for 20 hours in a constant temperature water bath shaker. The sample was centrifuged at 10000 r / min for 30 minutes, and the supernatant was filtered through a 0.22 μm aqueous filter membrane. The residue was extracted again with 5 mL of hydrolysate containing 100 mg of lyase. The two supernatants were combined and stored at -20°C for analysis.

[0047] The instrumental analysis conditions were as follows: A Hamilton PRP X-100 anion exchange column (250 mm × 4.1 mm, 10 μm) was used, equipped with a corresponding guard column; the mobile phase was 50 mmol / L citric acid solution (adjusted to pH 5.5 with 20% ammonia) - methanol - ultrapure water (10:3:87, v / v / v, volume ratio), isocratic elution, flow rate 1.0 mL / min, injection volume 50 μL. ICP-MS detection parameters were set as follows: RF power 1200 W, carrier gas flow rate 0.89 L / min, auxiliary gas flow rate 1.2 L / min, plasma flow rate 18.00 L / min, collision cell mode, methane flow rate 0.4 mL / min, and monitored isotopes were... 80 Se.

[0048] Standard curves were plotted using a series of selenium speciation standard solutions (including selenocysteine, methylselenocysteine, tetravalent selenium, selenomethionine, and hexavalent selenium) with concentration gradients of 1, 5, 10, 20, and 50 μg / L. The linear relationships among the components were good (R0). 2 >0.999). Qualitative analysis was performed based on retention time, and quantitative analysis was performed using the external standard method based on peak area.

[0049] The measurement results are as follows Figure 4 As shown, the distribution of organic selenium species in highland barley exhibits a regular change with increasing treatment concentration. After Bd treatment, the distribution of organic selenium species in highland barley grains changed significantly (see...). Figure 4B). Under different selenium treatment concentrations (40, 80, 120, 160 μM), the relative contents of selenocysteine ​​(SeCys) reached 33%, 37%, 21%, and 45%, respectively, while the relative contents of selenomethionine (SeMet) were 31%, 34%, 45%, and 28%, respectively. At the optimal treatment concentration of 160 μM, the SeCys and SeMet contents of Bd-5 were significantly higher than those of Bz-5 obtained through the traditional soaking process. Figure 4 A) The selenium conversion efficiency was increased by 5.9-fold and 5.3-fold, respectively. The SeCys and SeMet contents of Bd-5 were increased by 4.6-fold and 3.5-fold, respectively, compared to Bw-5, and the selenoamino acid content was increased by 68-fold compared to the control group (Bd-1). Based on the experimental results, the selenium conversion efficiency was most significant at a concentration of 160 μM. Therefore, only the Bw-5 stage was tested in Bw-5, and the results were similar to those in the Bz stage (see [link to relevant documentation]). Figure 4 A). The innovation of this invention lies in the fact that, through a combination of specific temperature and humidity pretreatment and temperature-controlled drying processes, the directional conversion of selenium forms was achieved for the first time in a non-germination state, making organic selenium the dominant form, with SeCys being particularly prominent. Compared with traditional processes, this invention significantly reduces the amount of inorganic selenium (Se... 4+ The residual ratio effectively promoted the conversion of inorganic selenium to organic selenium, and in particular significantly increased the synthesis ratio of SeCys.

[0050] The results show that the high-temperature and high-humidity pretreatment and temperature-controlled drying employed in this invention have a synergistic effect. These two methods create unique environmental conditions for the enzymatic assimilation pathway within the seed, activating a novel metabolic pathway distinct from traditional germination transformation. Unlike the conventional pathway of selenium conversion through root metabolism in existing technologies, this invention establishes a selenium conversion mechanism centered on cysteine-related structures in non-germinating seeds. This feature constitutes a significant technological advancement of this invention.

[0051] In particular, the two steps in the method of the present invention, namely "selecting 50 g of highland barley seeds and treating them in an environment of 35-40℃ and 40-60% relative humidity for 48 hours, and then treating them in an environment of 70-75℃ and 40-60% relative humidity for 120 hours" and "drying the sample in an environment of 35-40℃ and 40-60% relative humidity for 30 hours", have a significant synergistic effect, which can synergistically improve the synthesis ratio of SeCys and the relative content of selenomethionine in highland barley seeds.

[0052] Example 3: The samples were those prepared in Example 1. Scanning electron microscopy revealed that ( Figure 5After treatment with Bz, obvious microcracks were observed on the surface of the substrate, contrasting sharply with the intact surface of the untreated blank control group B0 (i.e., untreated fresh highland barley). Further treatment with Bw resulted in a large number of newly formed pore structures within the substrate, a feature not seen in the blank control group B0. The crucial Bd treatment significantly expanded and strengthened the existing cracks. Compared to the blank control group B0, which maintained a dense microstructure throughout, the highland barley seeds treated with the optimized process that adjusted seed dormancy and then dried (Bd stage) exhibited a uniform porous structure on their surface, maintaining their overall morphology without cracking or germination. This indicates that the process effectively preserved the integrity of the seed structure while promoting selenium absorption and conversion.

[0053] The flavor characteristics of the samples were analyzed using an electronic nose system. Figure 6 The image shows radar spectra of volatile components in black barley samples under different treatments, with untreated fresh barley (B0) serving as a control. Samples treated with Bd (…) Figure 6 A) The outline on the radar image is highly similar to that of group B0, indicating that the composition of volatile gases produced by barley metabolism under these conditions is highly similar to that of the untreated group. In contrast, the Bz treated group ( Figure 6 B) The response values ​​of the sensors W2S (positively correlated with alcohols, aldehydes, and ketones) and W1W (positively correlated with sulfides) were significantly higher than those of group B0 (P<0.05). This indicates that under high humidity conditions, the content of aldehydes, ketones, and sulfides in highland barley increases, and the resulting undesirable odors will adversely affect product quality. The results show that the flavor profile of the highland barley samples treated with the optimized process is highly similar to that of untreated highland barley, while the samples treated with direct soaking show obvious flavor deterioration, proving that the process can maintain the original flavor characteristics of highland barley while increasing selenium content.

[0054] This invention achieves highly efficient selenium enrichment and organic selenium conversion in barley seeds under non-germination conditions through precise coordination of temperature and humidity parameters with selenium treatment conditions. Compared with the traditional direct soaking process, the optimized process not only significantly improves the organic selenium conversion rate (reaching 93.6%), but more importantly, it significantly increases the total selenium content while maintaining the integrity of the seed structure and original flavor. The total selenium content of Bd-5 is 13.67 mg / kg, which is 360 times higher than that of the control group Bd-1. This provides a complete technical solution for developing high-quality selenium-enriched barley products. The process has advantages such as simple operation, controllable parameters, and good repeatability, making it suitable for large-scale production applications and providing a new technical path for the development of selenium-enriched functional grain products.

[0055] Currently, selenium-enriched bioconversion mainly relies on traditional fermentation or germination processes, with organic selenium conversion rates typically around 80% and limited increases in total selenium content. In contrast, this invention, through specific treatment, increases the organic selenium conversion rate to approximately 93% while significantly improving the total selenium content. This method not only boasts higher conversion efficiency but also preserves selenium in a more bioavailable form, providing a new technological pathway for the efficient and stable preparation of selenium-enriched products.

[0056] Although embodiments of the invention have been disclosed for illustrative purposes, those skilled in the art will understand that various substitutions, variations, and modifications are possible without departing from the spirit and scope of the invention and the appended claims. Therefore, the scope of the invention is not limited to the contents disclosed in the embodiments.

Claims

1. A method for in-situ selenium enrichment of black barley while preserving seed integrity, characterized in that: The method includes the selection, cleaning, screening, temperature and humidity pretreatment, high temperature intensification, selenium solution soaking, temperature-controlled drying, and finished product preparation of highland barley raw materials.

2. The method according to claim 1, characterized in that: The specific steps are as follows: (1) Raw material selection: Select black barley seeds, requiring plump grains, no disease, no mold, and uniform grain size of the current year's new seeds; (2) Cleaning and screening: Use running water to clean the impurities on the surface of the barley seeds, and remove floating and broken grains; (3) Temperature and humidity pretreatment: Selected highland barley seeds were placed in a constant temperature and humidity chamber and treated for 48 hours at 35-40℃ and 40-60% relative humidity to activate seed metabolic activity; (4) High temperature enhancement: The pretreated seeds were transferred to an environment of 70-76℃ and treated for 120 hours while maintaining a relative humidity of 40-60% to enhance seed permeability; (5) Selenium solution soaking: Take high-temperature enhanced barley seeds and soak them in sodium selenite solution at 28-32℃ for 12 hours. The concentration of selenium in the sodium selenite solution is 30-160 μM. (6) Temperature-controlled drying: The soaked seeds are dried at 35-40℃ and 40-60% relative humidity for 30 hours to complete the fixation and transformation of selenium; (7) Preparation of finished product: freeze-dry the dried barley seeds for 36 hours, pulverize them and pass them through a 100-mesh sieve to obtain selenium-enriched barley powder.

3. The method according to claim 1, characterized in that: The black barley seeds in step (1) are Longzi black barley seeds.

4. The method according to claim 1, characterized in that: The seeds of the Longzi black highland barley have an average protein content of 9.40%, a fat content of 2.32%, a crude fiber content of 3.01%, and a total dietary fiber content of 4.56%. They are also rich in anthocyanins (0.06%), β-glucan (5-8%), and polyphenols (0.3-0.6%). In addition, they are rich in calcium, magnesium, and iron minerals, with a content of 0.15-0.25%.

5. The method according to claim 1, characterized in that: In step (5), the concentration of selenium in the sodium selenite solution is 160 μM.

6. The method according to any one of claims 1 to 5, characterized in that: The conditions for neutron freeze drying in step (7) are: -40℃, vacuum degree 0-20 Pa.

7. The application of the method as described in any one of claims 1 to 6 in seed selenium enrichment.

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