Special selenium-rich cattle and sheep feed for high-water-holding-capacity shipborne catering and preparation process

Abstract

The invention relates to the technical field of fermented feed preparation processes, and discloses a special selenium-rich cattle and sheep feed for high-water-holding-capacity shipborne catering and a preparation process thereof, and the preparation process comprises the following steps: carrying out biological fermentation on feed raw materials to generate an internal three-dimensional network; the moment when the three-dimensional network reaches the complete state of the target is judged online through a physical detection means in the fermentation period; according to the method, a closed-loop locking relation between a physical state of a fermentation process and a subsequent shaping step is established, and rapid freezing and vacuum sublimation are executed by taking the judgment as a unique triggering condition, so that the form of a three-dimensional network is solidified and inherited, and finally, a dry porous material is obtained and compacted into a formed feed. The technical contradiction that a beneficial microstructure generated by fermentation in a traditional process is damaged by a subsequent forming step is solved, so that the final product can obtain the water holding performance derived from the physical structure of the final product, and the preservation of thermosensitive nutritional ingredients is realized.

Description

Technical Field

[0001] This invention relates to a high water-holding capacity shipboard catering-specific selenium-enriched cattle and sheep feed and its preparation process, belonging to the technical field of fermented feed preparation process. Background Technology

[0002] The currently prevalent technical approach involves first bio-fermenting the raw materials to enhance their nutritional value and improve their properties. This is followed by high-temperature, high-pressure mechanical extrusion to granulate the fermented wet material into high-density pellets. This process combination is widely recognized as an effective method in ensuring product physical stability and improving storage and transportation efficiency. However, there is an inherent technical constraint between the sequential steps of this process. The fermentation step aims to generate a porous structure composed of mycelium and extracellular polysaccharides within the material. However, in the subsequent high-temperature, high-pressure granulation step, the equipment applies shear and thermal pressure to this porous structure, altering its original morphology. The process leads to the destruction of the biological structure produced by the preceding steps in the same process flow by the physical shaping method of the subsequent steps. This to some extent causes the loss of bioculture costs invested in the fermentation process and the functionality of the obtained products. To alleviate this constraint, if the temperature or pressure is reduced in the extrusion granulation process, the density and molding strength of the final product will be insufficient, which will not meet the engineering requirements of large-scale storage and transportation. This reveals a limitation of the existing technology, namely that it mainly relies on thermal and mechanical energy for drying and shaping materials. The physical characteristics of this energy application method are difficult to be compatible with maintaining the integrity of the original microstructure of the fermentation products.

[0003] Besides the physical limitations at the hardware level, such as molding equipment, existing technologies also suffer from fundamental defects in the software of the production process, namely the process control logic, which cannot accurately adapt to the dynamic changes in the bio-fermentation process. For example, Chinese invention patent CN107173569A discloses an antibiotic-free selenium-enriched mulberry leaf feed for cattle and sheep and its preparation method. The core of this patent is to provide a feed formula containing multiple components such as mulberry leaves, houttuynia cordata, and probiotics. Its preparation method is simply to mix the components at room temperature. The control logic of this process is static and based on a preset formula, relying entirely on the chemical and nutritional properties of the components, without involving online monitoring and control of the evolution of the physical structure of the materials during fermentation. Its focus is on what is added, rather than what structure is formed and how to maintain that structure. This open-loop, non-adaptive control method cannot perceive or respond to the formation state of the internal microstructure of the materials, nor can it provide feedforward compensation for subsequent processing steps based on batch differences in materials, such as moisture content. It also cannot solve the deep-seated technical problem of how to effectively inherit the beneficial structure produced by fermentation into the final product.

[0004] In summary, the current feed preparation field has the following areas for improvement: 1. In terms of process flow, the structural formation effect of the fermentation step and the structural destruction effect of the subsequent hot pressing step coexist, and the beneficial results of the former are difficult to be fully preserved by the latter; 2. The high temperature and mechanical force used in the preparation process can affect the activity of some heat-sensitive nutrients in the fermentation products; 3. The water-holding capacity of the product largely depends on the exogenous additives in the formula, rather than being determined by the physical structure of the product itself. Therefore, how to establish a new feed preparation process that can completely solidify the biological microstructure formed during fermentation into the physical structure of the final product while dehydrating and drying the moist fermented material, thus achieving effective inheritance of the functionality of the fermentation product and the final product form, is the technical problem to be solved by this invention. Summary of the Invention

[0005] This invention provides a high water-holding capacity shipborne catering-specific selenium-enriched cattle and sheep feed and its preparation process. Its main purpose is to solve the problem of the biological microstructure generated in the fermentation step of the existing preparation process being unable to be effectively inherited in the subsequent molding step.

[0006] To achieve the above objectives, this invention provides a high water-holding capacity shipboard catering-specific selenium-enriched cattle and sheep feed and its preparation process, the process comprising: Step a: Bio-fermentation of feed ingredients containing selenium source to generate a three-dimensional network composed of cross-linked microbial extracellular polysaccharides inside the feed ingredients; Step b: During bio-fermentation, gas pressure pulses are periodically applied to the feed ingredients, and the attenuation process of the pressure inside the tank after the gas pressure pulses are applied is monitored in real time. Step c: When the pressure curve of the decay process presents a preset morphological feature that represents the completeness of the three-dimensional network, this judgment is used as the sole trigger condition to perform rapid freezing. Step d: Rapid freezing is used to cool the feed ingredients and uses the water solidified into ice crystals formed during the cooling process as a physical template to lock the three-dimensional network. Step e: The feed raw materials that have undergone rapid freezing are placed in a vacuum environment, and the water-solidified ice crystals are directly sublimated to obtain a dry porous material whose internal porous morphology replicates the three-dimensional network morphology. Step f involves applying pressure to the dry porous material to compact it into a pre-formed feed.

[0007] Preferably, the pressure curve exhibits a preset morphological feature, including: extracting damped oscillation morphological parameters from the pressure curve in real time; and when the value of the damped oscillation morphological parameters reaches a preset inflection point that represents the optimal combination of network integrity and elasticity of the three-dimensional network, it is determined that the pressure curve exhibits the preset morphological feature.

[0008] Preferably, prior to the rapid freezing process, a pre-cooling step is included. This pre-cooling step comprises: placing the bio-fermented feed ingredients in a first vacuum environment with a pressure higher than the triple point pressure of water; and inducing the evaporation of moisture within the feed ingredients to absorb latent heat of vaporization, thereby achieving volumetric overall cooling of the feed ingredients until the overall temperature of the feed ingredients is uniformly reduced to 0°C. Up to 2 The temperature range.

[0009] Preferably, step e further includes applying pulsed microwave energy to the feed material in the vacuum environment to assist in the sublimation of water-solidified ice crystals; the application of pulsed microwave energy includes alternately executing a microwave on stage and a microwave off stage; the microwave on stage is used to provide sublimation energy to the water-solidified ice crystals inside the feed material through volumetric heating; the microwave off stage is used to provide time for the vacuum system of the vacuum environment to extract the water vapor generated by the sublimation of water-solidified ice crystals.

[0010] Preferably, during bio-fermentation, a low-frequency alternating electric field with a frequency of 0.01 Hz to 1 Hz is applied to the feed ingredients; the low-frequency alternating electric field is used to drive the charged ions formed by the dissociation of the selenium source in the feed ingredients to migrate back and forth over short distances, so as to promote the uniform distribution of the selenium source in the feed ingredients without generating macroscopic material flow.

[0011] Preferably, after bio-fermentation and before rapid freezing, an online calibration and feedforward compensation step is included. The online calibration and feedforward compensation step includes: passing the feed raw material through a radio frequency resonant cavity and detecting the changes in the resonant characteristic parameters of the radio frequency resonant cavity caused by the passage of the feed raw material; determining the moisture content of the feed raw material based on the changes in the resonant characteristic parameters; and dynamically adjusting the cooling rate of the rapid freezing treatment based on the moisture content, so that the actual freezing rate of feed raw materials with different moisture contents is controlled within a target window for forming non-destructive micron-sized ice crystals.

[0012] Preferably, the cooling rate of the rapid freezing process is dynamically adjusted using a freezing power compensation coefficient. To achieve the refrigeration power compensation coefficient The rules for determining it are as follows: ,in, and These are the reference resonant frequency and reference quality factor of the radio frequency resonant cavity before the feed raw materials pass through, respectively. and These are the resonant frequency shift and quality factor change detected in real time by the radio frequency resonant cavity when the feed raw materials pass through; and These are pre-calibrated weighting coefficients that correspond to the resonant frequency offset and the change in the quality factor, respectively.

[0013] Preferably, rapid freezing involves lowering the temperature of the feed ingredients to -20°C within 10 to 60 minutes. to -40 Within the specified temperature range, the pressure of the vacuum environment in step e is below 611.73 Pa to ensure that the water-cured ice crystals sublimate directly into the gas phase without passing through the liquid phase.

[0014] A high water-holding capacity shipborne catering-specific selenium-enriched cattle and sheep feed is a solid porous composition without exogenous water-holding chemical additives. Furthermore, the feed has a porous physical structure that completely replicates the three-dimensional network formed by the cross-linking of microbial extracellular polysaccharides in step a of the process. The porous physical structure is the structural basis for the feed to achieve water-holding performance.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention integrates three steps—biological fermentation, rapid freezing, and vacuum sublimation—into a tightly sequential and functionally inseparable process. The microscopic network structure of the moist material formed during fermentation is solidified into fine ice crystals during rapid freezing. These ice crystals instantly become a three-dimensional physical support framework, locking the previous biological structure in a high-fidelity state. During vacuum sublimation, this physical support framework is directly vaporized and removed, transforming its original space into interconnected pores. This allows the biological structure of the fermentation stage to be completely inherited and solidified into the physical form of the final dried product. This process avoids the structural damage to the fermentation product caused by mechanical external forces in traditional solid-state preparation methods, ensuring that the physical structure of the final product directly depends on the biological construction results of the fermentation process.

[0016] 2. By periodically applying gas pressure pulses to the material during fermentation and monitoring its pressure decay characteristics, a process control system based on the material's own physical response was established. During fermentation, the gradual formation and cross-linking of the extracellular polysaccharide network changes the overall viscoelastic properties of the material. This intrinsic physical state change is directly reflected in the shape change of the pressure decay curve in the tank after the gas pressure pulse. By tracking the changing trend of this pressure decay characteristic, the moment when the micro-network structure reaches the preset state can be identified online, and the subsequent rapid freezing treatment can be triggered accordingly. This method changes the key turning point of the process flow from relying on fixed offline process time parameters to being directly related to the real and dynamically changing physical properties of the material being processed, making the preparation process adaptable to batch differences in raw materials and environmental fluctuations.

[0017] 3. Before rapid freezing, the moist fermented material is placed in a vacuum environment with a pressure higher than the triple point of water. By utilizing the physical phenomenon that water absorbs a large amount of latent heat of vaporization through evaporation under controlled pressure, the material is cooled in a volumetric manner from the inside out. This pre-cooling step reduces the temperature gradient between the surface and core of the material due to the material's own sluggish heat conduction during subsequent external contact cryogenic treatment. It makes the initial temperature field locked by subsequent cryogenic treatment more uniform, which is conducive to the formation of uniformly sized micro ice crystals throughout the entire material volume. This ensures the homogeneity of the microporous structure of the final product from the surface to the core, and solves the engineering problem of decreased product quality uniformity when the process is applied to large-scale production. Attached Figure Description

[0018] Figure 1 This is an adaptive control flowchart of the preparation process of the present invention; Figure 2 This is a schematic diagram showing the characteristics of pressure decay curves at different fermentation stages of the present invention; Figure 3 This is a schematic diagram illustrating the solidification and inheritance principle of the material microstructure of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in further detail below. It should be noted that the described embodiments are only some embodiments of this invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0020] A high-water-holding capacity shipboard catering-specific selenium-enriched cattle and sheep feed and its preparation process are disclosed. The feed is configured as a tightly sequential preparation method comprising steps such as bio-fermentation, online process state identification and feedforward compensation, rapid freezing and vacuum sublimation locking, and final low-pressure molding. The bio-fermentation step generates a three-dimensional network composed of cross-linked extracellular polysaccharides from microorganisms within the feed raw materials. All subsequent physical processing steps are used to solidify this three-dimensional network with high fidelity and transfer it to the final dried solid product. In the bio-fermentation step… To address the uneven distribution of charged ions formed by the dissociation of sodium selenite, the selenium source, in a static solid-state fermentation system due to lack of material flow, this preparation method involves placing a pair of inert electrodes on the exterior wall of the fermenter. These electrodes apply a low-frequency alternating electric field, set between 0.01 Hz and 1 Hz, to the feed material during fermentation. This low-frequency alternating electric field drives the charged ions to undergo short-distance reciprocating migration under the influence of the electric field force. This migration helps reduce the ion concentration gradient in local areas, thereby preventing damage to the forming three-dimensional network. Under the premise of promoting uniform distribution of selenium source throughout the entire material volume, to verify the homogenization effect of low-frequency alternating electric field on selenium source distribution, two parallel sample groups were prepared. The first sample group was subjected to a low-frequency alternating electric field with a frequency of 0.01 Hz to 1 Hz during bio-fermentation, while the second sample group was not subjected to this electric field under the same conditions for all other process parameters. After fermentation, samples of the moist fermentation material from both sample groups were taken and dried for structural analysis through rapid freezing and vacuum sublimation. The samples were then examined using a scanning electron microscope (SEM). The cross-section was observed for microscopic morphology, and the micro-area distribution of selenium (Se) was scanned using an attached energy dispersive X-ray spectrometer (EDS). The results showed that the selenium distribution pattern of the first sample group was uniformly scattered, with no local enrichment areas. However, the pattern of the second sample group showed multiple high-brightness selenium hotspots with sizes on the order of tens of micrometers. This comparison confirms that the application of a low-frequency alternating electric field can effectively improve the uniformity of functional ions in the solid-state fermentation system without causing macroscopic material flow.

[0021] To address the technical challenge of fermentation processes relying on fixed time parameters and failing to accurately handle the inherent randomness of biological processes, this preparation method integrates a process control unit based on the material's own physical response during bio-fermentation. This unit periodically applies a 0.5-second gas pressure pulse with a peak pressure exceeding the tank's baseline pressure by 5 kPa to the top space of the feed material via a precision gas control valve assembly connected to the fermenter. A high-precision pressure sensor with a sampling frequency of at least 100 Hz monitors the pressure decay process within the tank in real time after the gas pressure pulse. In the early stages of fermentation, the material has low viscosity, and the pressure decay curve exhibits rapid exponential decay. As fermentation progresses, the gradual formation and cross-linking of the three-dimensional network causes the material to exhibit viscoelasticity, at which point the pressure decay curve displays a damped oscillation pattern. The control unit extracts the damped oscillation pattern parameter from the pressure curve in real time, specifically calculating its quality factor. Value, when When the value reaches a pre-calibrated inflection point that characterizes the combination of network integrity and resilience of the 3D network, for example... When the value reaches its peak and begins to decline for the first time, the control system uses this judgment as the sole trigger condition to automatically terminate the fermentation step and immediately initiate the subsequent rapid freezing process. In this way, the key turning point of the process is directly linked to the physical properties of the material in real dynamic change.

[0022] Before initiating the rapid freezing process, to address the issue of varying actual freezing rates resulting from different batches of fermented materials due to differences in moisture content, a calibration and feedforward compensation step was incorporated into the preparation method. An annular radio frequency resonant cavity was integrated into the pipeline transporting the material from the fermenter to the freezing unit. As the fermented feed material passes through this resonant cavity, a network analyzer continuously monitors the changes in the resonant characteristic parameters of the resonant cavity caused by the material's passage, i.e., the reference resonant frequency. offset Compared with the benchmark quality factor Change Based on these real-time detected changes, the control system uses a preset refrigeration power compensation coefficient. The calculation rules, namely This allows for dynamic adjustment of the refrigeration system's output power; among which, and These are the baseline parameters of the radio frequency resonant cavity under no-load conditions, while the weighting coefficients... and These are pre-calibrated through offline experiments, for example, for a specific system. It can be calibrated to -0.5. It can be calibrated to -1.2; in a specific numerical example, if the no-load parameter is... and A batch of materials was detected during transit. and The system calculates... Correspondingly, the refrigeration power of the refrigeration system will be instantly increased by 8.3%. By applying this feedforward compensation, the actual freezing rate of feed raw materials with different moisture contents is adjusted to a preset target window that is conducive to the formation of uniform micron-sized ice crystals.

[0023] To avoid the problem of slow heat conduction in large-volume materials leading to a temperature gradient between the surface and core, which in turn causes slow cooling and destructive ice crystal formation in the core region during rapid freezing, the preparation method first performs a pre-cooling step. This pre-cooling step involves placing the fermented feed ingredients in a first vacuum environment with a pressure controlled above the triple point pressure of water (611.73 Pa, for example, 800 Pa). By inducing the evaporation of moisture within the feed ingredients under controlled pressure to absorb latent heat of vaporization, a volumetric overall cooling of the feed ingredients is achieved until a temperature sensor array indicates that the overall temperature of the feed ingredients has been uniformly reduced to 0°C. Up to 2 The temperature range is then determined; based on this, the refrigeration system is restarted, further reducing the temperature of the feed ingredients to -20°C within 10 to 60 minutes. to -40 Within a specific temperature range, the water that solidifies into ice crystals during the cooling process becomes a three-dimensional physical template, enabling high-fidelity physical locking of the three-dimensional network formed during the fermentation process.

[0024] After cryo-locking is completed, the feed ingredients are placed in a vacuum environment. The pressure of this vacuum environment is evacuated by a vacuum pump and maintained at a level below the triple point pressure of water (611.73 Pa) to ensure that the water-solidified ice crystals sublimate directly into the gas phase without passing through the liquid phase. To address the issue of an insulating layer forming on the outer layer of the dried material during sublimation drying, which hinders heat transfer to the interior, the preparation method uses a magnetron located in a vacuum chamber to apply pulsed microwave energy to the feed ingredients to assist in the sublimation of the water-solidified ice crystals. The application of pulsed microwave energy is designed to alternate between microwave on and microwave off phases. For example, a 15-second microwave on phase provides sublimation energy directly to the water-solidified ice crystals inside the feed ingredients through volumetric heating, followed by a 45-second microwave off phase. In the first stage, time is provided to the vacuum system to extract the water vapor generated by the sublimation of water-cured ice crystals until the material weight loss rate reaches a preset value, ultimately obtaining a dried porous material whose internal porous morphology replicates a three-dimensional network morphology. Finally, the dried porous material is formed by feeding it into the mold cavity through a cold press mold, and a hydraulic punch applies pressure to it. This pressure is controlled within a range that is only sufficient to cause physical aggregation between the particles of the dried porous material, forming a molded feed with a specific geometry and mechanical strength, but not enough to destroy its internal solidified porous morphology. For example, this pressure is set between 0.5 MPa and 2 MPa, ultimately obtaining a solid porous composition that does not contain exogenous water-retaining chemical additives and whose water-retaining properties originate from its internal porous physical structure.

[0025] Example 1: This example illustrates a specific operational instance of a high water-holding capacity shipboard catering-specific selenium-enriched cattle and sheep feed preparation process in a particular industrial application scenario. In this scenario, due to seasonal factors, the initial moisture content and fiber structure of a batch of feed raw materials deviate from the production baseline. This condition poses a technical challenge to preparation methods relying on fixed process time parameters. When this batch of low-moisture-content feed raw materials enters the preparation system, before entering the fermentation tank, it first passes through the radio frequency resonant cavity set in the online calibration and feedforward compensation steps. The control system then uses the resonant frequency offset detected in real time to control the resonant frequency offset. Variation in quality factor It is determined that the current moisture content of the material is lower than the benchmark value, and based on... The calculation rules generate a refrigeration power compensation coefficient less than 1.0. For example, a coefficient of 0.91 is passed to the subsequent rapid freezing unit and placed in a pending state. This step demonstrates that the online calibration unit provides feedforward adjustment basis for the rapid freezing unit. The former provides precise adjustment input for the latter, which then adaptively adjusts the process parameters based on this input, thereby solving the problem of inconsistent quality caused by the inability of fixed parameters to cope with raw material fluctuations in traditional processes. During bio-fermentation, the control system does not use a fixed fermentation time, but periodically applies gas pressure pulses to the material and monitors the pressure decay process. Since the initial state of this batch of material deviates from the baseline, the time for it to reach the target viscoelastic properties is correspondingly extended. However, the process control unit based on the material's own physical response continuously tracks the morphological changes of the pressure decay curve until the value of the damping oscillation morphology parameter reaches the preset inflection point before outputting a trigger signal. This method does not directly solve the problem of how to accelerate fermentation, but changes the judgment basis of process monitoring from relying on time parameters to relying on the directly measurable physical state of the material, so that the original uncertainty problem of fermentation time is avoided under a new control framework.

[0026] Once the trigger signal is generated, the rapid freezing unit is activated and the freezing power compensation coefficient previously determined by the feedforward compensation step is invoked. Correspondingly, the output power of the refrigeration system was reduced, so that the actual freezing rate of the low moisture content material was controlled within the target window for forming non-destructive micron-sized ice crystals. Subsequently, the vacuum sublimation and low-pressure molding steps were performed according to the procedure. This complete process locks two independent physical detection methods, namely the radio frequency resonant cavity used for online determination of material moisture content and the gas pressure pulse monitoring used for online determination of material network integrity, with the subsequent rapid freezing step in a closed loop. This forms an adaptive production scheduling method that can cope with fluctuations in the state of the input material and make decisions based on the actual physical properties of the process material. The final batch of molded feed, after testing, showed that its key indicators, such as the internal porous physical structure and water retention capacity, were at the same quality level as products produced using raw materials with the benchmark moisture content.

[0027] Example 2: To objectively verify the technical effect of the preparation process claimed in this invention on improving feed water retention performance, and to confirm the causal relationship between this effect and key steps in the process, this example designed and executed a comparative experiment. The experiment included three sample groups: a test group using the method of this invention, control group A, and control group B. All sample groups used the same batch of feed ingredients containing alfalfa meal, corn meal, soybean meal, and sodium selenite as selenium sources as initial treatment targets, and were tested on the same temperature-controlled machine (temperature control accuracy ±0.5). Biological fermentation was carried out in a fermenter with gas pressure pulse application function (pulse pressure accuracy ±0.1kPa) until the three-dimensional network was determined to have reached the target integrity state based on the online judgment mechanism based on the gas pressure pulse response. At this time, the fermented wet material was divided into three equal parts, and the three sample groups were further processed respectively. Among them, the test group using the method of the present invention followed the preparation process claimed in the present invention, that is, rapid freezing, vacuum sublimation and low-pressure compaction were performed in sequence; the control group A adopted the conventional high temperature and high pressure granulation process in the art, that is, the wet material was subjected to 90°C. After drying, the material was granulated using a screw extruder at a pressure of 1.5 MPa. Control group B aimed to verify the effects of rapid freezing and vacuum sublimation on the final product performance; its treatment involved extruding the wet material at 45°C. The samples were dried under normal pressure with hot air until they lost water to the same moisture content as the dried porous material in the test group using the method of this invention. Then, they were shaped using the same low-pressure compaction equipment and parameters as the test group using the method of this invention. The water-holding capacity of the final shaped feed obtained from the three sample groups was quantitatively characterized using a unified testing procedure. This procedure included the determination of two indicators: one was the water absorption swelling rate, which was determined by heating 10g of dried sample at 25°C. The first test was the percentage weight gain after soaking in pure water for 30 minutes and draining the surface water. The second test was the water retention, which was determined by the percentage of the remaining water mass to the initial water mass after the sample was left to stand for 60 minutes under standard atmospheric conditions. During the test, the test group using the method of this invention obtained a dry porous material with a loose morphology and a porous structure that maintained the fermentation state after vacuum sublimation. In contrast, the control group B underwent volume shrinkage and structural collapse after hot air drying. Table 1 shows the performance test data of the final products of each sample group.

[0028] Table 1: Comparison of key performance indicators for each sample group.

[0029] The data in Table 1 show that the water absorption swelling rate of the test group using the method of the present invention is higher than that of control group A and control group B. The only process variable between the test group using the method of the present invention and control group B is the dehydration and drying method. The former has a higher water absorption swelling rate and water retention index than the latter. This data indicates that the locking of the three-dimensional network by rapid freezing treatment and the inheritance of the locked structure by vacuum sublimation while removing water are the reasons for obtaining higher water retention performance. The experimental results show that the final product obtained by using the complete preparation process claimed in this invention has a higher water retention index than the product obtained by using the traditional high temperature and high pressure process and the process that omits the key structure locking step. This provides objective data support for the process method to solidify the biological microstructure formed in the fermentation stage into the functional physical structure of the final product.

[0030] To further verify the irreplaceable role of the rapid freezing step in locking the three-dimensional network structure and to clearly distinguish it from another advanced low-temperature drying technology, this application also performed the following comparative experiments: Comparative Example 1: This comparative example aims to further verify the decisive role of the rapid freezing step in the process of the present invention in inheriting the fermentation microstructure and achieving high water-holding capacity. This comparative example is completely consistent with the test group in Example 2 using the method of the present invention in all initial raw materials, bio-fermentation process parameters, and final low-pressure molding parameters. The only difference is that this comparative example omits the rapid freezing step and uses a conventional low-temperature vacuum drying process to replace the vacuum sublimation process of the present invention. The specific experimental process is as follows: the wet materials that have completed fermentation in the same batch as the sample groups in the aforementioned examples and have been determined by the online judgment mechanism to have reached the target intact state are directly placed in a vacuum drying oven. The vacuum degree of the drying oven is set to 2000 Pa, and the temperature is set to 45°C. The drying process continues. During the drying process, uneven shrinkage of the material volume can be observed through the observation window, accompanied by the generation of surface micro-cracks. When the weight loss rate of the material is consistent with the final weight loss rate of the test group using the method of the present invention in Example 2, the drying is stopped, and the dried material is obtained. Subsequently, the dried material is compacted and shaped using the same low-pressure compaction equipment and process parameters (0.5 MPa to 2 MPa pressure range) as the test group using the method of the present invention. The final shaped feed is then tested for its key performance indicators using the same test procedure as in the aforementioned examples. The test results are recorded in Table 2 and compared with the data of the test group using the method of the present invention.

[0031] Table 2: Comparison of key performance indicators between Comparative Example 1 and the method of the present invention.

[0032] The experimental results show that, without the rapid freezing step, even with advanced low-temperature vacuum drying, the three-dimensional network structure inside the wet material will still collapse severely during the dehydration process, resulting in the inability to form a porous morphology in the final product. Consequently, its water absorption expansion rate and water retention index are far lower than those of the product obtained using the complete process of this invention. This data objectively confirms that the rapid freezing step, by forming an ice crystal physical template to lock the network, is a prerequisite for subsequent processes to inherit the fermentation biological structure as the functional physical structure of the final product.

[0033] Example 3: This example combines Figures 1 to 3 This document describes a high-water-holding capacity, selenium-enriched cattle and sheep feed specifically for shipboard catering and its preparation process. Figure 1 As shown, the system executes two online monitoring and adjustment steps in parallel. The first is online process status identification and closed-loop locking. This step involves periodically applying gas pressure pulses to the fermenter and monitoring the pressure decay curve in real time. When the curve is determined to exhibit the characteristics of a network integrity inflection point, a trigger signal is generated. The second is online moisture content calibration and feedforward compensation. This step allows the material to pass through a radio frequency resonant cavity before entering subsequent processes, and detects the changes in resonance parameters caused by the material's passage. and A freezing power compensation coefficient is calculated, and the cooling rate of the subsequent rapid freezing step is dynamically adjusted based on this coefficient. When the trigger signal is received, the rapid freezing step is started, using the moisture inside the material to solidify into ice crystal templates, thereby physically locking the three-dimensional network structure formed by fermentation. Subsequently, in the vacuum sublimation step, the ice crystals are removed by directly vaporizing them without passing through the liquid phase, thereby solidifying the previously locked network structure into a porous morphology. Finally, through the low-pressure compaction step, the dried porous material is aggregated into a molded feed with a predetermined shape. The pressure in this step is controlled within a range that is not enough to destroy its internal porous structure, thereby obtaining the final high water-holding capacity selenium-rich molded feed.

[0034] like Figure 2 As shown in the figure, the horizontal axis represents time in seconds, and the vertical axis represents pressure in kPa. In the early stage of fermentation, as shown by the solid line, due to the low viscosity of the material, the pressure inside the tank exhibits a rapid exponential decay after the gas pressure pulse. As fermentation progresses, in the middle stage, as shown by the dashed line, due to the generation and cross-linking of extracellular polysaccharides of microorganisms, the material as a whole exhibits a certain degree of viscoelasticity, and the pressure decay curve begins to change into a slight oscillation. When fermentation enters the later stage, as shown by the dotted line, a complete three-dimensional network structure has been formed, and the material exhibits viscoelastic properties. At this time, the pressure decay curve shows a damped oscillation that can be accurately identified. The appearance of this specific morphological parameter is used as the triggering basis for determining whether the network has reached the target integrity.

[0035] like Figure 3 As shown in the diagram, the process begins with the bio-fermentation stage, in which a three-dimensional network of extracellular polysaccharides, represented by cross-shaped symbols, is formed inside the feed raw material under the action of a low-frequency alternating electric field. Subsequently, the material enters the online calibration stage, where its physical parameters are calibrated by detection using a radio frequency resonant cavity. Immediately following this, in the rapid freezing stage, the overall temperature of the material is reduced to -20°C. to -40 In the region where the water inside solidifies into an ice crystal locking structure represented by a star-shaped symbol, the previously formed polysaccharide network is physically locked in a high-fidelity state. Then, in the vacuum sublimation stage, the ice crystal structure is directly vaporized and removed by applying microwave energy to assist sublimation. The space it originally occupied is transformed into a porous physical structure represented by a circular symbol, thus obtaining a porous dry material. Finally, in the low-pressure molding stage, the material is compacted within a pressure range of 0.5-2 MPa to obtain a molded feed product.

[0036] Example 4: To determine the preset morphological characteristic inflection point of the gas pressure pulse response-based process control method when applied to feed ingredients with different components, this example discloses a standardized engineering procedure for offline calibration of this inflection point. This calibration procedure aims to determine a quantifiable process control trigger threshold directly related to the water-holding capacity of the final product for a feed ingredient formulation whose fermentation rheological properties are unknown. The procedure is executed in a laboratory-scale preparation system, which includes a system with the same functional specifications as the production equipment, namely a temperature control accuracy of ±0.5. The fermentation tank has a pressure pulse application accuracy of ±0.1kPa and a pressure sensor sampling frequency of not less than 100Hz, as well as subsequent rapid freezing, vacuum sublimation and low-pressure molding units; the initial target is a batch of uniformly formulated new wet feed raw materials.

[0037] The calibration procedure is performed as follows: First, the batch of new feed ingredients is divided into 10 equal portions, and 10 fermentation batches are started sequentially in the fermentation tank. Second, a different, incrementally increasing fermentation termination time is set for each batch, starting from the 12th hour, terminating one batch every hour until the 21st hour. Just before each batch is terminated, the last complete pressure decay process measured by the gas pressure pulse response monitoring system is recorded, and the corresponding quality factor is calculated from it. This allows us to obtain a set of data pairs that correspond one-to-one with each fermentation time point. Subsequently, the moist fermented material removed at the end of the batch was subjected to the subsequent process steps claimed in this invention, namely, rapid freezing, vacuum sublimation, and low-pressure compaction, to prepare the final molded feed sample; finally, the water absorption swelling rate of each molded feed sample was tested using the unified testing procedure in Example 2, obtaining a set of results related to the fermentation time point and... Performance data corresponding to the value ( ),in This represents the water absorption swelling rate.

[0038] By obtaining ( By analyzing the data series, quality factors can be plotted. Value and final product water absorption swelling rate The relationship curve reflects the process of a three-dimensional network from its initial formation to excessive cross-linking or aging, exhibiting a trend of first rising and then falling, indicating the existence of a specific... The value that causes the final product's water absorption and swelling rate to reach its maximum is the inflection point of the morphological characteristics for the target integrity of the feed ingredients to be found for this new formula. The value was determined as the trigger threshold for this formulation in industrial production. If the calibration data shows that... When the value is 4.5, the water absorption swelling rate reaches its peak, then it can be... The value is set to 4.5; the execution of this calibration procedure establishes a quantifiable process control trigger threshold for specific feed ingredients, enabling the preparation process to be applied to material systems with different components.

[0039] Example 5: To ensure accurate operation of the online calibration and feedforward compensation steps after initial deployment or replacement of the RF resonator hardware, this example discloses a method for offline calibration of the cryogenic power compensation coefficient. Weighting coefficients in calculation rules and The standardization engineering procedure aims to establish a quantitative relationship model between the radio frequency resonant cavity response parameters and the moisture content of a specific feed ingredient and a specific hardware system. The procedure requires the use of the radio frequency resonant cavity of the production line to be calibrated, a laboratory constant temperature drying oven with forced-air drying function, and an electronic balance with an accuracy of 0.01g. The initial calibration target is a batch of representative feed ingredients with known dry matter mass. The procedure first prepares a set of moist material samples with multiple known moisture content gradients by adding precisely measured amounts of pure water to the dry material in batches. For example, 10 samples with a uniform moisture content distribution from 50% to 68% and a gradient of 2% are prepared.

[0040] Subsequently, each group of samples was passed sequentially through the radio frequency resonant cavity, and the readings measured by the network analyzer were recorded relative to each known moisture content. Corresponding resonant frequency offset Variation in quality factor Meanwhile, based on the moisture content of each group of samples... Based on the relevant physical parameters of water, the target refrigeration power compensation coefficient required to achieve the ideal freezing rate is calculated. Finally, these 10 sets of data ( , , As a dataset, multiple linear regression analysis was used to analyze... The equation is fitted, and the weighting coefficients that minimize the sum of squared residuals are obtained. and The numerical values; by executing this calibration procedure, a set of weighting coefficients with clear physical meaning and statistical basis can be determined for a specific combination of hardware and materials, for example, by solving for... and The set of coefficient values ​​is then stored in the control system of the preparation process. The control system can then use this set of coefficients to dynamically adjust the freezing power of subsequent production batches with different moisture contents based on the real-time detected changes in the radio frequency resonant cavity parameters.

[0041] Example 6: To determine the weighting coefficients used in the calculation rules for the online calibration and feedforward compensation steps after initial deployment or replacement of the RF resonator hardware. and This embodiment discloses a standardized engineering procedure for offline calibration of a set of coefficients. The calibration procedure aims to establish a quantitative relationship between the radio frequency resonant cavity response parameters and the moisture content of a specific feed ingredient and a specific hardware system. The procedure utilizes the radio frequency resonant cavity of the production line to be calibrated, a laboratory constant temperature drying oven with forced-air drying function, and an electronic balance with an accuracy of 0.01g. The initial calibration target is a batch of feed ingredients with known dry matter mass. The procedure first prepares a set of moist material samples with multiple known moisture content gradients by adding precisely measured amounts of pure water to the dry material in batches, such as preparing 10 sets of samples with moisture contents ranging from 50% to 68% with a gradient of 2%. Subsequently, each set of samples is passed sequentially through the radio frequency resonant cavity, and the values ​​measured by the network analyzer and the values ​​corresponding to each known moisture content are recorded. Corresponding resonant frequency offset Variation in quality factor Meanwhile, based on the moisture content of each group of samples... Based on the relevant physical parameters of water, the target freezing power compensation coefficient required to achieve a preset target freezing rate is calculated. Finally, these 10 sets of data ( , , As a dataset, multiple linear regression analysis was used to analyze... The equation is fitted, and the weighting coefficients that minimize the sum of squared residuals are obtained. and The numerical value; by executing this calibration procedure, a set of weighting coefficients can be determined for a specific combination of hardware and materials, such as by solving for the value. and The determined weighting coefficient values ​​are stored in the control system of the manufacturing process, which is used to dynamically adjust the freezing power of subsequent production batches based on the real-time detected changes in the radio frequency resonant cavity parameters.

[0042] Example 7: To determine the target rate window for the formation of non-destructive micron-sized ice crystals in different feed ingredients during rapid freezing, the following calibration procedure can be performed. This procedure applies to a batch of moist material that has undergone biological fermentation and has been determined by an online judgment mechanism to have reached the target intact state. The executing device is an experimental-grade freezing device with programmable control of the cooling rate. The procedure first divides the batch of moist material into several samples, then sets a gradually increasing average cooling rate for each sample and freezes it until it reaches -40°C. The endpoint temperature, where the cooling rate settings for this group cover 1 / minute to 15 The interval was measured in seconds. Then, all samples frozen at different rates were prepared into shaped feeds using the same vacuum sublimation and low-pressure compaction steps. The water absorption swelling rate of each shaped feed sample was measured according to a unified testing procedure. Finally, the relationship curve between cooling rate and water absorption swelling rate was plotted. The rate interval in which the water absorption swelling rate began to enter the peak plateau and no longer increased with the rate was selected. Combined with the microscopic observation results of the cross-section of the dry porous material of the corresponding sample by scanning electron microscopy, the rate range with the most complete and homogeneous pore structure was determined as the target rapid freezing rate window of the feed raw material.

[0043] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A preparation process for a high water-holding capacity shipboard catering-specific selenium-enriched cattle and sheep feed, characterized in that, The process includes: Step a: Bio-fermentation of feed ingredients containing selenium source to generate a three-dimensional network composed of cross-linked microbial extracellular polysaccharides inside the feed ingredients; Step b: During bio-fermentation, gas pressure pulses are periodically applied to the feed ingredients, and the attenuation process of the pressure inside the tank after the gas pressure pulses are applied is monitored in real time. Step c: When the pressure curve of the decay process presents a preset morphological feature that represents the completeness of the three-dimensional network, this judgment is used as the sole trigger condition to perform rapid freezing. Step d: Rapid freezing is used to cool the feed ingredients and uses the water solidified into ice crystals formed during the cooling process as a physical template to lock the three-dimensional network. Step e: The feed raw materials that have undergone rapid freezing are placed in a vacuum environment, and the water-solidified ice crystals are directly sublimated to obtain a dry porous material whose internal porous morphology replicates the three-dimensional network morphology. Step f involves applying pressure to the dry porous material to compact it into a pre-formed feed.

2. The preparation process of a high water-holding capacity shipborne catering-specific selenium-enriched cattle and sheep feed according to claim 1, characterized in that, The pressure curve exhibits a preset morphological characteristic, including: extracting damped oscillation morphological parameters from the pressure curve in real time; and determining that the pressure curve exhibits the preset morphological characteristic when the value of the damped oscillation morphological parameter reaches a preset inflection point that represents the optimal combination of network integrity and elasticity of the three-dimensional network.

3. The preparation process of a high water-holding capacity shipborne catering-specific selenium-enriched cattle and sheep feed according to claim 1, characterized in that, Prior to rapid freezing, a pre-cooling step is included, which involves placing the bio-fermented feed ingredients in a first vacuum environment with a pressure higher than the triple point pressure of water; and inducing the evaporation of moisture inside the feed ingredients to absorb the latent heat of vaporization until the overall temperature of the feed ingredients is uniformly reduced to 0°C. Up to 2 The temperature range.

4. The preparation process of a high water-holding capacity shipborne catering-specific selenium-enriched cattle and sheep feed according to claim 1, characterized in that, Step e further includes applying pulsed microwave energy to the feed material in a vacuum environment to assist in the sublimation of water-solidified ice crystals; the application of pulsed microwave energy includes alternately executing a microwave on phase and a microwave off phase; the microwave on phase is used to provide sublimation energy to the water-solidified ice crystals inside the feed material through volumetric heating; the microwave off phase is used to provide time for the vacuum system of the vacuum environment to extract the water vapor generated by the sublimation of water-solidified ice crystals.

5. The preparation process of a high water-holding capacity shipborne catering-specific selenium-enriched cattle and sheep feed according to claim 1, characterized in that, During bio-fermentation, a low-frequency alternating electric field with a frequency of 0.01 Hz to 1 Hz is also applied to the feed ingredients. A low-frequency alternating electric field is used to drive the charged ions formed by the dissociation of selenium source in feed ingredients to migrate back and forth over short distances, so as to promote the uniform distribution of selenium source in feed ingredients without generating macroscopic material flow.

6. The preparation process of a high water-holding capacity shipborne catering-specific selenium-enriched cattle and sheep feed according to claim 1, characterized in that, After bio-fermentation and before rapid freezing, an online calibration and feedforward compensation step is included. This step includes: passing the feed ingredient through a radio frequency resonant cavity and detecting the changes in the resonant characteristic parameters of the radio frequency resonant cavity caused by the passage of the feed ingredient; determining the moisture content of the feed ingredient based on the changes in the resonant characteristic parameters; and dynamically adjusting the cooling rate of the rapid freezing process based on the moisture content, so that the actual freezing rate of feed ingredients with different moisture contents is controlled within a target window for the formation of non-destructive micron-sized ice crystals.

7. The preparation process of a high water-holding capacity shipboard catering-specific selenium-enriched cattle and sheep feed according to claim 6, characterized in that, The cooling rate of rapid freezing is dynamically adjusted through a freezing power compensation coefficient. To achieve the refrigeration power compensation coefficient The rules for determining it are as follows: ,in, and These are the reference resonant frequency and reference quality factor of the radio frequency resonant cavity before the feed raw materials pass through, respectively. and These are the resonant frequency shift and quality factor change detected in real time by the radio frequency resonant cavity when the feed raw materials pass through; and These are pre-calibrated weighting coefficients that correspond to the resonant frequency offset and the change in the quality factor, respectively.

8. The preparation process of a high water-holding capacity shipboard catering-specific selenium-enriched cattle and sheep feed according to claim 1, characterized in that, Rapid freezing is the process of lowering the temperature of feed ingredients to -20°C within 10 to 60 minutes. to -40 The temperature range is such that the pressure of the vacuum environment in step e is below 611.73 Pa.

9. A high water-holding capacity shipboard catering-specific selenium-enriched cattle and sheep feed, obtained by the preparation process of the high water-holding capacity shipboard catering-specific selenium-enriched cattle and sheep feed as described in claim 1, characterized in that, The feed is a solid porous composition without exogenous water-holding chemical additives; and the interior of the feed has a porous physical structure that completely replicates the three-dimensional network formed by the cross-linking of microbial extracellular polysaccharides in step a of the process. The porous physical structure is the structural basis for the feed to achieve water-holding performance.

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