A production process of composite irradiated bean paste

Abstract

This application relates to the field of condiment processing technology and discloses a composite irradiation process for producing fermented broad bean paste. The process includes the following steps: adding water to the fermented base paste to reduce salinity, extracting the clarified liquid, and continuously monitoring the first derivative of the infrared characteristic absorption signal using an ATR-FTIR spectrometer. When the derivative enters a specific range, a concentration program alternating between microwave heating and vacuum flash evaporation is initiated to dehydrate, cool, and restore salinity. Subsequently, an oxygen-containing mixed gas is introduced into the fermented paste, and the spread paste is subjected to 60Co γ-ray penetrating irradiation at 0.0℃ to 4.0℃. Finally, a high-barrier composite material is used for nitrogen-filled deoxygenation packaging. This process uses online infrared monitoring to capture the flavor accumulation equilibrium point, utilizes trace dissolved oxygen to assist radiation sensitization, reduces the number of residual bacteria at a lower absorbed dose, and inhibits the risk of later bag bloating, while simultaneously improving the retention of the original sauce's flavor and physicochemical quality.

Description

Technical Field

[0001] This invention relates to the field of condiment processing technology, specifically a composite irradiation process for producing fermented soybean paste. Background Technology

[0002] Organic fermented soybean paste requires extremely high levels of microbial control during production. Due to its high raw material costs and the absence of conventional chemical preservatives, residual gas-producing bacteria and spoilage microorganisms within the paste can easily cause bloating or spoilage during distribution. Traditional long-duration heat sterilization processes involve excessive heat loads, leading to the loss of large amounts of volatile flavor compounds accumulated during fermentation and exacerbating Maillard reactions, causing excessive browning and damaging the inherent quality and nutritional components of organic fermented soybean paste. Although room-temperature irradiation sterilization technology is gradually being adopted, the complex composition, viscous texture, and high water activity of fermented soybean paste mean that single irradiation processes often suffer from insufficient penetration and incomplete sterilization. Furthermore, blindly increasing the irradiation dose in pursuit of complete sterilization can easily trigger chain oxidation of lipids within the matrix, producing irradiation-related off-flavors.

[0003] On the other hand, traditional fermentation and post-processing sterilization steps are usually independent and fragmented, resulting in a long overall production cycle and high equipment energy consumption. Therefore, there is an urgent need to develop a new composite production process that combines microwave and specific doses of radiation irradiation with physicochemical interventions during fermentation. This process can shorten the production cycle while resolving the contradiction between incomplete sterilization and unstable flavor caused by single-technology methods, thus balancing the preservation of fermented bean paste quality and its stability against bag bulging in the later stages.

[0004] Therefore, this invention proposes a composite irradiation process for producing fermented soybean paste to address the shortcomings of existing technologies. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a composite irradiation process for producing fermented broad bean paste, which solves the problem that existing fermented broad bean paste processes are difficult to control in terms of heat load and radiation dose while effectively killing spoilage-causing microorganisms and maintaining product flavor and physicochemical stability during sterilization and preservation.

[0006] To address the above problems, the present invention provides the following technical solution: A composite irradiation process for producing fermented soybean paste includes the following steps: S1: Place the fermented raw sauce to be processed in a vacuum reactor equipped with an online infrared spectroscopy monitoring device and an industrial microwave source, add sterile water to the vacuum reactor and mechanically stir to obtain the fermented sauce body, so as to reduce the mass fraction of sodium chloride in the fermented sauce body. S2: While maintaining mechanical stirring, continuously extract the clear liquid phase of the fermented sauce using an online infrared spectroscopy monitoring device and continuously collect the infrared spectrum of the clear liquid phase, and calculate the 1030 cm⁻¹ value.-1 ~1050cm -1 The first derivative of the peak area or absorbance of the characteristic absorption signal within the wavenumber range as a function of time; S3: When the first derivative of the characteristic absorption signal decreases from a positive value and enters the range of -0.20 to 0.20 for the first time, the concentration and resalting program is started. The concentration and resalting program includes: turning on the industrial microwave source to microwave heat the material under an absolute pressure of 95.0 kPa to 105.0 kPa, then turning on the vacuum pump to perform vacuum flash evaporation to remove water and cool down, and repeating the alternating cycle of microwave heating and vacuum flash evaporation to remove water and cool down until the sodium chloride mass fraction of the fermented sauce is restored to 16.0% and the core temperature of the material drops to 0.0℃ to 4.0℃. S4: After the concentrated salt process is completed, oxygen-containing mixed gas is introduced into the vacuum reactor until the absolute pressure inside the vacuum reactor is restored to 95.0 kPa to 105.0 kPa, and maintained at 95.0 kPa to 105.0 kPa for 5 min to 15 min. S5: Take out the processed sauce and spread it out flat. Under an ambient temperature of 0.0℃~4.0℃, use a 60Co γ-ray irradiation source to penetrate and irradiate the spread sauce. S6: After the penetration irradiation is completed, the sauce is sealed with nitrogen-filled deoxygenated packaging material using high-barrier composite packaging material.

[0007] By adopting the above technical solution, this process introduces sterile water to moderately dilute the salt content in the early stage of fermentation of the raw sauce, aiming to gently relieve the inhibition of macromolecular hydrolysis by the hypertonic environment. Under mechanical stirring, the system uses an online microfilter to continuously separate the clear liquid phase and pumps it into an ATR-FTIR spectrometer for real-time monitoring at 1030 cm⁻¹. -1 ~1050cm -1 The spectral absorption characteristics in the wavenumber band. The physical meaning of this band corresponds to the stretching vibrations of CO or C-C bonds in sugar alcohols, and its absorbance changes directly reflect the progress of alcoholization and esterification reactions within the fermented sauce. Calculating the first derivative of this absorbance signal quantifies the rate of change of biochemical reactants over time. When this first derivative falls from a positive value and falls within a small fluctuation range of -0.20 to 0.20, it means that the rate of free metabolic reactions at a specific stage tends to stagnate, and the accumulation of flavor precursors has reached the equilibrium point expected by the process.

[0008] Upon detecting the aforementioned trigger signal, the system immediately enters the concentration and resalting process. During the microwave heating stage, a high-frequency alternating electromagnetic field is used to polarize and generate heat through friction between water molecules within the sauce, achieving instantaneous energy accumulation within the material. Subsequent vacuum suction causes the ambient pressure to plummet below the saturated vapor pressure, causing the superheated free water to violently boil and vaporize. Since the vaporization phase change of water requires the absorption of a large amount of latent heat, this process forcibly removes heat from the interior of the sauce. The alternating cycle of atmospheric pressure microwave and vacuum flash evaporation not only precisely removes the excess water introduced to promote hydrolysis in the early stages, restoring the sodium chloride mass fraction to the safe threshold of 16.0%, but also avoids the heat-sensitive flavor degradation caused by prolonged temperature maintenance through conventional heat conduction.

[0009] After adjusting the physicochemical properties, the process transitions to the radiation-sensitized killing stage targeting microorganisms. During the vacuum recovery period, an oxygen-containing mixed gas is introduced, forcing oxygen molecules to penetrate and dissolve into the degassed, cold paste matrix. When 60Co gamma-ray penetrating irradiation is performed at 0.0℃~4.0℃, water molecules inside the paste absorb high-energy radiation, undergoing ionization and excitation. The primary primary reaction equation is as follows: H₂O + γ-rays → ·OH + e⁻ - aq +H + +H2O2+H2; In the formula: ·OH represents a hydroxyl radical, e - aq For hydrated electrons, H + H₂O₂ is hydrogen ions, H₂O₂ is hydrogen peroxide, and H₂ is hydrogen gas molecules.

[0010] In the aforementioned radiochemical environment, the oxygen molecules dissolved in the early stages exhibit extremely strong electron affinity, rapidly undergoing a capture addition reaction with hydrated electrons as electron acceptors: e - aq +O2→O2 ·- ; In the formula: O2 ·- It is a superoxide anion free radical.

[0011] Subsequently, the free hydrogen ions further combine with superoxide anion radicals: H + +O2 ·- →·HO2; In the formula: ·HO2 is a hydrogen peroxide free radical.

[0012] These oxygen-containing free radicals (O2) derived from dissolved oxygen ·-Compared to primary free radicals, ·HO2 has a longer half-life. It can continuously diffuse within the cellular microenvironment, inducing chain-like lipid peroxidation damage to microbial cell membranes and attacking bases and phosphodiester bonds in microbial DNA molecules, causing irreversible double-strand breaks. Relying on this trace oxygen-dominated radiation sensitization mechanism, the slurry can disrupt the proliferation pathways of *Aerogenes* and *Pseudomonas* at relatively low physical absorbed doses.

[0013] After undergoing free radical reactions, the paste contains residual oxidation risks. Therefore, the nitrogen-filled deoxygenation packaging at the end forms a closed loop. High-barrier materials block the intrusion of external air, and nitrogen replacement, combined with the consumption of micro-oxygen within the packaging space, can quickly terminate the propagation reaction chain of residual oxygen-containing free radicals, fundamentally inhibiting lipid oxidative rancidity and non-enzymatic browning, and establishing the shelf-life stability of the finished product.

[0014] It should be noted that the first derivative of the characteristic absorption signal refers to the 1030 cm⁻¹ value. -1 ~1050cm -1 The rate of change (dA / dt) of the integral area (or absorbance peak) of the characteristic absorption peak within the wavenumber range with reaction time (t). In specific calculations, data from adjacent time points are continuously collected, and after eliminating high-frequency noise through moving average, the signal increment per unit time is calculated. A positive derivative indicates that the reactant concentration is increasing, while a derivative approaching 0 (entering the range of -0.20 to 0.20) indicates that the accumulation of flavor compounds has reached a dynamic equilibrium point.

[0015] Preferably, in step S1, sterile water is added until the sodium chloride mass fraction of the fermented sauce decreases to 12.5%–14.5%. By adopting the above technical solution, the salt reduction is controlled within the range of 12.5%–14.5%, which not only relieves the excessive inhibition of protease and saccharifying enzyme activity by high osmotic pressure, clearing obstacles for the short-term release of flavor precursors, but also maintains the basic bottom line of inhibiting the outbreak of spoilage bacteria, preventing uncontrollable rancidity during the short enzymatic hydrolysis window.

[0016] Preferably, the online infrared spectroscopy monitoring device includes a closed external circulation sampling reflux pipeline, an online microfilter, an ATR-FTIR spectrometer, and an ATR-FTIR spectrometer flow cell; in step S2, specifically: a portion of the paste is continuously drawn out through the closed external circulation sampling reflux pipeline, filtered and extracted by the online microfilter to obtain a clear liquid phase, and the clear liquid phase is pumped into the flow cell of the ATR-FTIR spectrometer to continuously collect infrared spectra; the pore size of the online microfilter is 0.8μm to 2.0μm, and the flow rate of the clear liquid phase pumped into the flow cell of the ATR-FTIR spectrometer is 15mL / min to 25mL / min.

[0017] By adopting the above technical solution, the limited microfiltration pore size effectively traps solid fragments and large molecular protein polymers in the feed liquid, eliminating physical interference caused by particle scattering on the infrared optical path. Combined with flow rate control and a 5-point moving average algorithm, it smooths high-frequency random signal fluctuations caused by diaphragm pump pulsation and sensor thermal noise, significantly improving the signal-to-noise ratio of derivative calculations and ensuring the accurate execution of process node triggering criteria.

[0018] Preferably, in step S3, the specific parameters of the concentrated double salt program are as follows: turn on an industrial microwave source with a frequency of 915MHz or 2450MHz, set the microwave power density to 1.5kW / kg~2.5kW / kg, and continue heating for 25s~40s before turning off the industrial microwave source; then turn on the vacuum pump to reduce the absolute pressure in the vacuum reactor to 400Pa~800Pa within 8s~15s, and maintain it for 50s~70s for vacuum flash evaporation to remove water and cool down; after a single operation is completed, repeat the above-mentioned alternating cycle of industrial microwave heating and vacuum flash evaporation to remove water and cool down until the target parameters set in step S3 are met.

[0019] By employing the above technical solution, this parameter combination establishes a dynamic balance between heat injection and latent heat consumption. The set microwave power density allows the material to accumulate sufficient internal energy to trigger deep boiling in a very short time; the subsequent rapid vacuuming action disrupts the inherent gas-liquid phase equilibrium, forcing moisture to undergo a violent phase change under low pressure. The water vapor carries away the latent heat, causing a sharp drop in the bulk phase temperature and preventing caramelization reactions that could occur in some areas due to delayed release of latent heat.

[0020] Preferably, in step S4, the oxygen-containing mixed gas is an oxygen-nitrogen mixed gas with an oxygen volume fraction in the range of 15.0% to 21.0%.

[0021] By employing the above technical solution and controlling the oxygen partial pressure in the backpressure mixed gas, an appropriate amount of dissolved oxygen can be infiltrated and distributed into the loose paste during the vacuum recovery stage. This dissolved oxygen concentration precisely meets the electron acceptor requirements of the subsequent radiation-sensitized reaction, while avoiding the chemical risk of severe auto-oxidation of the original oil caused by directly introducing pure oxygen.

[0022] Preferably, in step S5, the thickness of the layer of the processed sauce taken out and spread out is controlled to be 8mm to 12mm, and the material absorption dose is controlled to be 6.0kGy to 8.0kGy.

[0023] By adopting the above technical solution, the thickness of the layer is precisely matched to the penetration attenuation law of gamma rays in water-containing viscous media, reducing the difference in absorbed dose gradient between the upper and lower surfaces of the paste. Under the synergistic effect of sensitization established by dissolved oxygen in the early stage, the dose range of 6.0 kGy to 8.0 kGy has sufficient energy density to break the DNA double strand of the target microorganism, achieving deep sterilization.

[0024] Preferably, in step S6, nitrogen filling and deoxygenation sealing are performed within 10 to 20 minutes after the penetration irradiation ends; the high-barrier composite packaging material is a multi-layer composite film or an aluminum-plastic composite film containing an ethylene-vinyl alcohol copolymer barrier layer; during nitrogen filling and deoxygenation sealing, a food-grade iron-based deoxidizer pack or an ascorbic acid-based deoxidation label is placed inside the packaging, and neither the food-grade iron-based deoxidizer pack nor the ascorbic acid-based deoxidation label is in direct contact with the surface of the sauce.

[0025] By employing the above technical solution and limiting the exposure time window after irradiation, the probability of secondary contamination by airborne bacteria is greatly reduced. Combined with the high oxygen barrier properties of the materials and the continuous consumption by the internal deoxygenating medium, the microenvironment within the packaging rapidly transitions to an absolute pressure anaerobic state. This combination of physical isolation and chemical oxygen consumption blocks the aliphatic chain oxidation initiated by free radicals, maintaining the long-term stability of the product's color and flavor.

[0026] Preferably, in step S1, the pretreatment preparation step of the fermented raw sauce to be treated includes: Step S11: Take defatted soybeans that have been soaked and had their moisture content adjusted, place them in an atmospheric pressure environment for industrial microwave heating treatment, and cool them after the industrial microwave heating treatment is completed to obtain cooled defatted soybeans; Step S12: Mix the cooled defatted soybeans with wheat flour, fresh chili flakes with a particle size distribution of 2.0 mm to 5.0 mm, sodium chloride, and sterile water evenly to obtain a mixture. Step S13: Inoculate the mixture with Aspergillus oryzae and carry out fermentation at a low temperature. When the amino acid nitrogen content of the mixture reaches 0.70g / 100g to 0.85g / 100g, terminate the main fermentation. Step S14: After terminating the primary fermentation, the mixture is cooled and inoculated with post-fermentation guiding bacteria for post-fermentation. When the pH of the mixture drops to 4.15-4.35 and the mass concentration ratio of acetic acid to lactic acid in the liquid phase reaches 0.10-0.30, the post-fermentation is terminated to obtain the fermented raw sauce to be processed.

[0027] By adopting the above technical solution, the pretreatment of the raw soybean paste abandons the traditional high-energy-consuming atmospheric pressure cooking method. Instead, microwave heating is used to induce thermal denaturation of protein molecules and unfolding of peptide chains within defatted soybeans, exposing more potential enzymatic sites. During the main fermentation stage, the abundant protease system secreted by Aspergillus oryzae hydrolyzes the substrate, establishing a umami base primarily composed of amino acid nitrogen. When transitioning to the post-fermentation stage, a guiding microbial community composed of halophilic tetracocci and Lactobacillus plantarum is actively introduced. Utilizing the glycolysis and acid production metabolism of specific microorganisms, the proportion of organic acids in the mixed materials is adjusted, establishing the characteristic flavor base of the raw soybean paste at a biochemical level.

[0028] Preferably, in step S11, after soaking defatted soybeans, the moisture content is adjusted to 45.0% to 50.0%, and microwave heating treatment is performed using an industrial microwave generator with a frequency of 915MHz or 2450MHz. The specific energy consumption of microwave is controlled to be 250kJ / kg to 350kJ / kg, and the treatment time is 3.0min to 5.0min. After the industrial microwave heating treatment is completed, the temperature is cooled to 25°C.

[0029] By employing the above technical solution, microwaves with specific energy consumption are introduced at a determined moisture content baseline, causing the water inside the soybean tissue to vaporize violently upon heating. The internal-to-outward stress generated by vaporization and expansion leads to microscopic ruptures in the plant cell walls, forming a loose and porous physical structure. This structural change not only shortens the pathway for subsequent water and enzyme penetration but also significantly improves the mass transfer efficiency of macromolecular nutrients dissolving into the liquid phase.

[0030] Preferably, the control parameters for steps S13 and S14 are: In step S13, Aspergillus oryzae is inoculated at 0.1wt% to 0.3wt% of the total dry weight of the mixture and placed in an environment of 38℃ to 41℃ for heat preservation and fermentation; In step S14, the temperature of the mixture is lowered to 26℃~29℃, and a post-fermentation guide group composed of halophilic tetracocci and Lactobacillus plantarum is introduced at 0.05wt%~0.15wt% of the total dry weight of the mixture.

[0031] By adopting the above technical solution, the temperature field maintained at 38℃~41℃ during the main fermentation period meets the optimal conditions for Aspergillus oryzae growth, ensuring rapid secretion and efficient catalysis of the enzyme system in the early stage. When the temperature drops to 26℃~29℃ and enters the post-fermentation period, the original mold reproduction and metabolism are inhibited. At this time, Lactobacillus plantarum begins to dominate the acid production process to lower the pH value of the mixture; accompanied by this biochemical process, halophilic tetracocci metabolize to produce volatile flavor substances such as acetic acid in a salinity-stressed environment. The relay metabolism of the two bacterial groups in space and time jointly outlines the acidity and aroma profile of the fermented soybean paste during its maturity stage.

[0032] This invention provides a composite irradiation process for producing fermented soybean paste. It offers the following advantages: 1. This invention uses a closed external circulation pipeline and an online microfilter to extract the clear liquid phase, and uses an ATR-FTIR spectrometer to monitor the 1030 cm⁻¹ concentration in real time. -1 ~1050cm -1 The infrared absorption signal in this band is used. By calculating the first derivative of the absorbance in this band, the rate change of biochemical reactions within the fermented sauce is quantified. When the derivative enters a specific range, a concentration process is triggered. This online monitoring mechanism replaces the traditional timed operation that relies on manual experience, ensuring the consistency of flavor precursor accumulation across batches of product.

[0033] 2. This invention employs a concentrated resalt process that alternates between industrial microwave heating and vacuum flash evaporation for dehydration and cooling. Microwaves provide the initial internal energy to boil the water, while subsequent vacuum suction disrupts the gas-liquid equilibrium, causing the water to flash-evaporate. The latent heat of water vaporization removes heat from the material. This operation restores the previously diluted sodium chloride mass fraction to 16.0% while avoiding the volatilization of heat-sensitive components and excessive caramelization caused by prolonged temperature holding using conventional heat conduction.

[0034] 3. In this invention, after vacuum flash degassing, an oxygen-containing mixed gas is introduced into the reactor, allowing a suitable amount of oxygen to dissolve in the cold, paste-like matrix. During subsequent 60Co γ-ray penetrating irradiation, the dissolved oxygen acts as an electron acceptor, participating in the reaction of primary radiation products and generating oxygen-containing free radicals with longer half-lives, thereby damaging the cell membranes and DNA double strands of microorganisms. Relying on this radiation-sensitizing effect of trace amounts of dissolved oxygen, the proliferation pathways of gas-producing bacteria and putrefactive yeasts can be interrupted at relatively low physical absorbed doses.

[0035] 4. This invention sets a strict exposure time window after the penetration irradiation is completed, and uses a high-barrier membrane material in conjunction with an internal deoxygenation medium for nitrogen-filled deoxygenation encapsulation. This encapsulation cuts off the infiltration of external gases and continuously consumes the residual oxygen inside the packaging, thereby blocking the lipid oxidation chain reaction initiated by radiation residual free radicals, controlling the subsequent non-enzymatic browning process, and maintaining the shelf-life stability of the finished product. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the process flow according to an embodiment of the present invention; Figure 2 This is a schematic diagram showing the changes in liquid-phase glycerol concentration and spectral signal derivative during the desalination stage of Example 1 of the present invention; Figure 3 This is a schematic diagram illustrating the linear correlation between the spectral peak area integral and the offline concentration in an embodiment of the present invention; Figure 4 This is a schematic diagram comparing the internal temperature distribution of fermented soybean paste during the resalting, dehydration, and cooling stages of Example 1 and Comparative Example 3 of the present invention. Figure 5 The following is a comparison chart of the physicochemical properties of the finished products after packaging in the embodiments and comparative examples of the present invention; wherein, (a) is a distribution chart of viable bacteria count measured by the plate coating method on the first day after packaging of the fermented sauce in each group, and the vertical axis is displayed on a logarithmic scale; (b) is a comparison chart of the volume expansion rate of the packaging bag and the accumulation of headspace carbon dioxide in each group after 30 days of accelerated storage at 37°C. Figure 6The following is a comparison chart of the retention of physicochemical quality markers of the embodiments and comparative products of the present invention; wherein, (a) is a distribution chart of the hydroxymethylfurfural content and total color difference deviation values ​​in each group, and (b) is a change in the percentage of amino acid nitrogen retention of each group of products relative to the initial original sauce. Detailed Implementation

[0037] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] In the embodiments and comparative examples of this invention, the determination of amino acid nitrogen content was carried out in accordance with the current national standard GB5009.235 National Food Safety Standard for the Determination of Amino Acid Nitrogen in Food.

[0039] The main raw materials and reagents used in the following examples and comparative examples have the following sources and specifications. Reagents not specifically mentioned are all commercially available analytical grade or higher grade products.

[0040] The defatted soybeans, wheat flour, fresh chili peppers, sodium chloride (CAS No. 7647-14-5), and sterile water used in the examples were all commercially available, conventional food-grade industrial products. The Aspergillus oryzae, Halophilic tetracoccus, and Lactobacillus plantarum strains used in the fermentation were all commercially available, conventional food-grade strains, activated according to the product instructions before use. The packaging material used for deoxygenation and sealing was commercially available food-grade high-barrier composite packaging material, and the oxygen removal component was a commercially available food-grade deoxygenation device.

[0041] The structure and connection relationships of the vacuum reactor, the closed external circulation sampling reflux pipeline, the online microfilter, the ATR-FTIR spectrometer and its flow cell, and the industrial microwave source used in the embodiments of the present invention are described as follows: Closed external circulation sampling and reflux pipeline: refers to a closed sampling and reflux pipeline connected to the outside of the main vacuum reactor. A sanitary material pump is installed on the pipeline to continuously draw out part of the paste inside the main reactor, and after external detection, it is returned to the main reactor.

[0042] Online microfilter: refers to a microfiltration device that is connected in series in the sampling return pipeline. Its filter element has a pore size of 0.8μm to 2.0μm, preferably a ceramic membrane or a sintered metal filter material, and is used to separate solids in a paste and provide a clear liquid phase to downstream detection devices.

[0043] ATR-FTIR spectrometer and its flow cell: The flow cell is located above the detection surface of the ATR crystal, with inlet and outlet ports at both ends, and is connected to the outlet pipeline of the online microfilter for continuous acquisition of infrared absorption signals of the clear liquid phase.

[0044] Industrial microwave source: refers to an industrial microwave generator with a frequency of 915MHz or 2450MHz, which is connected to a vacuum reactor through a microwave transmission window to provide bulk heating energy to the materials inside the reactor.

[0045] All of the above-mentioned equipment can be commercially available food industry equipment or conventional modified parts, and can be connected and used in a conventional pipeline manner. In the embodiments, the online salinity measurement method can be to directly measure it with an online salinity meter, or to measure it with conductivity and then convert it to sodium chloride mass fraction according to a pre-established conversion relationship.

[0046] The power supply methods described in the preparation examples and embodiments of this invention are part of the plant's supporting infrastructure. Photovoltaic green electricity is used in the preparation examples and embodiments to power the microwave processing, fermentation control, vacuum processing, irradiation processing-related delivery and dose monitoring, as well as subsequent filling and packaging equipment. A process combining 60Co gamma-ray treatment and microwave treatment is employed, controlling the irradiation dose to 7-10 kGy. Photovoltaic power can be prioritized for supplying irradiation processing-related supporting equipment, with surplus power used for raw material pretreatment, fermentation temperature control, and filling and packaging, thereby enabling seamless integration of the composite processing technology with the fermentation process. The aforementioned power supply methods do not alter the process steps of this invention, nor are they considered essential technical features limiting the validity of the process.

[0047] Preparation Example 1: This preparation example provides a method for preparing fermented raw sauce to be treated, including the following steps: 35.0 kg of defatted soybeans, soaked and with a moisture content adjusted to 48.0%, were taken. The soaked defatted soybeans were placed in an atmospheric pressure environment and heated using an industrial microwave generator with a frequency of 915 MHz. The microwave specific energy consumption was controlled at 300 kJ / kg, and the treatment time was 4.0 min. After treatment, the defatted soybeans were cooled to 25°C.

[0048] The cooled defatted soybeans were mixed evenly with 12.0 kg of wheat flour, 25.0 kg of fresh chili flakes with a particle size distribution of 2.0 mm to 5.0 mm, 17.0 kg of sodium chloride, and 11.0 kg of sterile water.

[0049] Inoculate with Aspergillus oryzae at 0.2 wt% of the total dry weight of the mixture, and then incubate at 39°C for fermentation. During fermentation, samples are taken every 12 hours to determine the amino acid nitrogen content of the mixture. The main fermentation stage is terminated when the amino acid nitrogen content reaches 0.78 g / 100 g.

[0050] The temperature of the mixture was lowered to 28°C, and a post-fermentation guiding microbial community, consisting of *Tetracoccus halophilus* and *Lactobacillus plantarum*, was inoculated at 0.1 wt% of the total dry weight of the mixture. During fermentation, the pH value of the mixture and the organic acid composition in the liquid phase were monitored periodically. Fermentation was terminated when the pH value of the mixture dropped to 4.25 and the mass concentration ratio of acetic acid to lactic acid in the liquid phase reached 0.20, yielding the fermented raw sauce to be processed.

[0051] Preparation Example 2: This preparation example provides a method for preparing fermented raw sauce to be treated, including the following steps: Take 30.0 kg of defatted soybeans that have been soaked and had their moisture content adjusted to 45.0%. Place the soaked defatted soybeans in an atmospheric pressure environment and heat them using an industrial microwave generator with a frequency of 2450 MHz, controlling the microwave specific energy consumption to be 250 kJ / kg, and the treatment time to be 3.0 min. After treatment, cool the defatted soybeans to 25℃.

[0052] The cooled defatted soybeans were mixed evenly with 15.0 kg of wheat flour, 20.0 kg of fresh chili flakes with a particle size distribution of 2.0 mm to 5.0 mm, 16.0 kg of sodium chloride, and 19.0 kg of sterile water.

[0053] Inoculate with Aspergillus oryzae at 0.1 wt% of the total dry weight of the mixture, and then incubate at 38°C for fermentation. During fermentation, the amino acid nitrogen content of the mixture is measured periodically. When the amino acid nitrogen content reaches 0.70 g / 100 g, the main fermentation stage is terminated.

[0054] The temperature of the mixture was lowered to 26°C, and a post-fermentation guiding microbial community, consisting of *Tetracoccus halophilus* and *Lactobacillus plantarum*, was inoculated at 0.05 wt% of the total dry weight of the mixture. During fermentation, the pH value of the mixture and the organic acid composition in the liquid phase were monitored periodically. Fermentation was terminated when the pH value of the mixture dropped to 4.35 and the mass concentration ratio of acetic acid to lactic acid in the liquid phase reached 0.10, yielding the fermented raw sauce to be processed.

[0055] Preparation Example 3: This preparation example provides a method for preparing the fermented base sauce to be treated, including the following steps: Take 40.0 kg of defatted soybeans that have been soaked and had their moisture content adjusted to 50.0%. Place the soaked defatted soybeans in an atmospheric pressure environment and heat them using an industrial microwave generator with a frequency of 915 MHz, controlling the microwave specific energy consumption to be 350 kJ / kg, and the treatment time to be 5.0 min. After treatment, cool the defatted soybeans to 25℃.

[0056] The cooled defatted soybeans were mixed evenly with 10.0 kg of wheat flour, 28.0 kg of fresh chili flakes with a particle size distribution of 2.0 mm to 5.0 mm, 18.0 kg of sodium chloride, and 4.0 kg of sterile water.

[0057] Inoculate with Aspergillus oryzae at 0.3 wt% of the total dry weight of the mixture, and then incubate at 41°C for fermentation. During fermentation, the amino acid nitrogen content of the mixture is measured periodically. When the amino acid nitrogen content reaches 0.85 g / 100 g, the main fermentation stage is terminated.

[0058] The temperature of the mixture was lowered to 29°C, and a post-fermentation guiding microbial community, consisting of *Tetracoccus halophilus* and *Lactobacillus plantarum*, was inoculated at 0.15 wt% of the total dry weight of the mixture. During fermentation, the pH value of the mixture and the organic acid composition in the liquid phase were monitored periodically. Fermentation was terminated when the pH value of the mixture dropped to 4.15 and the mass concentration ratio of acetic acid to lactic acid in the liquid phase reached 0.30, yielding the fermented raw sauce to be processed.

[0059] Reference Figure 1 Example 1: This example provides a composite irradiation process for producing fermented soybean paste, including the following steps: The fermented raw sauce prepared in Example 1 was placed in a vacuum reactor equipped with a closed external circulation sampling reflux pipeline, an online microfilter, an ATR-FTIR spectrometer and its flow cell, and a 915MHz industrial microwave source. Sterile water was added to the vacuum reactor, and mechanical stirring was performed at a speed of 120 r / min. Simultaneously, the sodium chloride mass fraction of the fermented sauce was monitored using an online salinity measurement method until the sodium chloride mass fraction of the fermented sauce decreased to 13.5%.

[0060] While maintaining a stirring speed of 120 r / min, a portion of the paste was continuously drawn out through a bypass line, and the clear liquid was extracted through an online microfilter with a pore size of 1.0 μm. This clear liquid was then pumped into an ATR-FTIR flow cell at a flow rate of 20 mL / min. The infrared spectrum of the clear liquid was continuously acquired at a sampling frequency of 1 time / s, and analyzed at a 1030 cm⁻¹ depth. -1 Up to 1050cm -1 The characteristic absorption signal within the wavenumber range is subjected to a moving average of 5 consecutive sampling points. Based on the time interval (1s) between adjacent sampling points, the rate of change of the peak area integral over time, i.e., the first derivative, is calculated. When the first derivative of the characteristic absorption signal decreases from a positive value and first enters the range of -0.20 to 0.20, the resalting process in the vacuum reactor is initiated.

[0061] With the absolute pressure in the reactor at 95.0 kPa to 105.0 kPa, a 915 MHz industrial microwave source was turned on, and the microwave power density was set to 2.0 kW / kg. Heating was continued for 30 seconds, after which the industrial microwave source was turned off. Then, the vacuum pump was turned on, and the absolute pressure inside the reactor was reduced to 600 Pa within 10 seconds, and maintained for 60 seconds for flash evaporation to remove water and cool down. This cycle of atmospheric pressure microwave heating and vacuum flash evaporation was repeated until the sodium chloride mass fraction of the fermented paste recovered to 16.0%, and the core temperature of the material dropped to 2.0℃. At this point, the vacuum pump was turned off.

[0062] After the concentrated double salt operation is completed, an oxygen-nitrogen mixture with an oxygen volume fraction of 18.0% is introduced into the reactor until the absolute pressure inside the reactor returns to 95.0 kPa to 105.0 kPa, and is maintained at this state for 10 minutes.

[0063] The processed sauce was removed and spread evenly on a conveyor belt, with a layer thickness controlled at 10 mm. Under an ambient temperature of 2.0℃, the spread sauce was irradiated with a 60Co gamma-ray irradiation source, with the absorbed dose controlled at 7.0 kGy.

[0064] Within 15 minutes after irradiation, the sauce is nitrogen-filled and deoxygenated using commercially available food-grade high-barrier composite packaging material; preferably, a multi-layer composite film containing an ethylene-vinyl alcohol copolymer barrier layer is used. During packaging, a commercially available food-grade iron-based deoxidizer packet is placed in the top space inside the packaging, ensuring that the deoxidizer packet does not directly contact the surface of the sauce.

[0065] Example 2: This example provides a composite irradiation process for producing fermented soybean paste, including the following steps: The fermented raw sauce prepared in Example 2 was placed in a vacuum reactor equipped with a closed external circulation sampling reflux pipeline, an online microfilter, an ATR-FTIR spectrometer and its flow cell, and a 915MHz industrial microwave source. Sterile water was added to the vacuum reactor, and mechanical stirring was performed at a speed of 150 r / min. At the same time, the sodium chloride mass fraction of the fermented sauce was monitored using an online salinity measurement method until the sodium chloride mass fraction of the fermented sauce decreased to 14.5%.

[0066] While maintaining a stirring speed of 150 r / min, a portion of the paste was continuously drawn out through a bypass line, and the clear liquid was extracted through an online microfilter with a pore size of 2.0 μm. This clear liquid was then pumped into an ATR-FTIR flow cell at a flow rate of 15 mL / min. The infrared spectrum of the clear liquid was continuously acquired at a sampling frequency of 1 time / s, and analyzed at a depth of 1030 cm⁻¹. -1 Up to 1050cm -1The characteristic absorption signal within the wavenumber range is subjected to a moving average of 5 consecutive sampling points. Based on the time interval (1s) between adjacent sampling points, the rate of change of the peak area integral over time, i.e., the first derivative, is calculated. When the first derivative of the characteristic absorption signal decreases from a positive value and first enters the range of -0.20 to 0.20, the resalting process in the vacuum reactor is initiated.

[0067] With the absolute pressure in the reactor at 95.0 kPa to 105.0 kPa, a 915 MHz industrial microwave source was turned on, and the microwave power density was set to 1.5 kW / kg. Heating was continued for 40 seconds, after which the industrial microwave source was turned off. Then, the vacuum pump was turned on, and the absolute pressure inside the reactor was reduced to 800 Pa within 15 seconds. This pressure was maintained for 50 seconds for flash evaporation to remove water and cool the reactor. This cycle of atmospheric pressure microwave heating and vacuum flash evaporation was repeated until the sodium chloride mass fraction of the fermented paste recovered to 16.0%, and the core temperature of the material dropped to 4.0℃. At this point, the vacuum pump was turned off.

[0068] After the concentrated double salt operation is completed, an oxygen-nitrogen mixture with an oxygen volume fraction of 15.0% is introduced into the reactor until the absolute pressure inside the reactor returns to 95.0 kPa to 105.0 kPa, and is maintained at this state for 5 minutes.

[0069] The processed sauce was removed and spread evenly on a conveyor belt, with a layer thickness controlled at 8 mm. Under an ambient temperature of 4.0℃, the spread sauce was irradiated with a 60Co gamma-ray irradiation source, with the absorbed dose controlled at 6.0 kGy.

[0070] Within 10 minutes after irradiation, the sauce is nitrogen-filled and deoxygenated using commercially available food-grade high-barrier composite packaging material; aluminum-plastic composite film is preferred. During packaging, a commercially available food-grade ascorbic acid-based deoxygenation label is placed on the inner wall of the packaging, and the deoxygenation label does not directly contact the surface of the sauce.

[0071] Example 3: This example provides a composite irradiation process for producing fermented soybean paste, including the following steps: The fermented raw sauce prepared in Example 3 was placed in a vacuum reactor equipped with a closed external circulation sampling reflux pipeline, an online microfilter, an ATR-FTIR spectrometer and its flow cell, and a 915MHz industrial microwave source. Sterile water was added to the fermented sauce, and mechanical stirring was performed at 100 r / min. Simultaneously, the sodium chloride mass fraction of the fermented sauce was monitored using an online salinity measurement method until the sodium chloride mass fraction of the fermented sauce decreased to 12.5%.

[0072] While maintaining a stirring speed of 100 r / min, a portion of the paste was continuously drawn out through a bypass line, and the clear liquid was extracted through an online microfilter with a pore size of 0.8 μm. This clear liquid was then pumped into an ATR-FTIR flow cell at a flow rate of 25 mL / min. Infrared spectra of the clear liquid were continuously acquired at a sampling frequency of 1 time / s, and analyzed at a depth of 1030 cm⁻¹. -1 Up to 1050cm -1 The characteristic absorption signal within the wavenumber range is subjected to a moving average of 5 consecutive sampling points. Based on the time interval (1s) between adjacent sampling points, the rate of change of the peak area integral over time, i.e., the first derivative, is calculated. When the first derivative of the characteristic absorption signal decreases from a positive value and first enters the range of -0.20 to 0.20, the resalting process in the vacuum reactor is initiated.

[0073] With the absolute pressure in the reactor at 95.0 kPa to 105.0 kPa, a 915 MHz industrial microwave source was turned on, and the microwave power density was set to 2.5 kW / kg. Heating was continued for 25 seconds, after which the industrial microwave source was turned off. Then, the vacuum pump was turned on, and the absolute pressure inside the reactor was reduced to 400 Pa within 8 seconds. This pressure was maintained for 70 seconds for flash evaporation to remove water and cool the reactor. This cycle of atmospheric pressure microwave heating and vacuum flash evaporation was repeated until the sodium chloride mass fraction of the fermented paste recovered to 16.0%, and the core temperature of the material dropped to 0.0℃. At this point, the vacuum pump was turned off.

[0074] After the concentrated double salt operation is completed, an oxygen-nitrogen mixture with an oxygen volume fraction of 21.0% is introduced into the reactor until the absolute pressure inside the reactor returns to 95.0 kPa to 105.0 kPa, and is maintained at this state for 15 minutes.

[0075] The processed sauce was removed and spread evenly on a conveyor belt, with a layer thickness controlled at 12 mm. Under ambient temperature of 0.0℃, the spread sauce was irradiated with a 60Co gamma-ray irradiation source, with the absorbed dose controlled at 8.0 kGy.

[0076] Within 20 minutes after irradiation, the sauce is nitrogen-filled and deoxygenated using commercially available food-grade high-barrier composite packaging material; preferably, a multi-layer composite film containing an ethylene-vinyl alcohol copolymer barrier layer is used. During packaging, a commercially available food-grade iron-based deoxidizer packet is placed in the top space inside the packaging, ensuring that the deoxidizer packet does not directly contact the surface of the sauce.

[0077] Example 4: This example provides a composite irradiation process for producing fermented soybean paste, including the following steps: The fermented raw sauce prepared in Example 1 was placed in a vacuum reactor equipped with a closed external circulation sampling reflux pipeline, an online microfilter, an ATR-FTIR spectrometer and its flow cell, and a 2450MHz industrial microwave source. Sterile water was added to the vacuum reactor, and mechanical stirring was performed at 120 r / min. Simultaneously, the sodium chloride mass fraction of the fermented sauce was monitored using an online salinity measurement method until the sodium chloride mass fraction of the fermented sauce decreased to 13.5%.

[0078] While maintaining a stirring speed of 120 r / min, a portion of the paste was continuously drawn out through a bypass line, and the clear liquid was extracted through an online microfilter with a pore size of 1.0 μm. This clear liquid was then pumped into an ATR-FTIR flow cell at a flow rate of 20 mL / min. The infrared spectrum of the clear liquid was continuously acquired at a sampling frequency of 1 time / s, and analyzed at a 1030 cm⁻¹ depth. -1 Up to 1050cm -1 The characteristic absorption signal within the wavenumber range is subjected to a moving average of 5 consecutive sampling points. Based on the time interval (1s) between adjacent sampling points, the rate of change of the peak area integral over time, i.e., the first derivative, is calculated. When the first derivative of the characteristic absorption signal decreases from a positive value and first enters the range of -0.20 to 0.20, the resalting process in the vacuum reactor is initiated.

[0079] With the absolute pressure in the reactor at 95.0 kPa to 105.0 kPa, a 2450 MHz industrial microwave source was turned on, and the microwave power density was set to 2.0 kW / kg. Heating was continued for 30 seconds, after which the industrial microwave source was turned off. Then, the vacuum pump was turned on, and the absolute pressure inside the reactor was reduced to 600 Pa within 10 seconds, and maintained for 60 seconds for flash evaporation to remove water and cool down. This cycle of atmospheric pressure microwave heating and vacuum flash evaporation was repeated until the sodium chloride mass fraction of the fermented paste recovered to 16.0%, and the core temperature of the material dropped to 2.0℃. At this point, the vacuum pump was turned off.

[0080] After the concentrated double salt operation is completed, an oxygen-nitrogen mixture with an oxygen volume fraction of 18.0% is introduced into the reactor until the absolute pressure inside the reactor returns to 95.0 kPa to 105.0 kPa, and is maintained at this state for 10 minutes.

[0081] The processed sauce was removed and spread evenly on a conveyor belt, with a layer thickness controlled at 10 mm. Under an ambient temperature of 2.0℃, the sauce was sent to an irradiation sterilization center driven by photovoltaic green electricity at full load. The spread sauce was irradiated with a 60Co gamma ray irradiation source, and the absorbed dose of the material was controlled at 7.0 kGy.

[0082] Within 15 minutes after irradiation, the sauce is nitrogen-filled and deoxygenated using commercially available food-grade high-barrier composite packaging material; preferably, a multi-layer composite film containing an ethylene-vinyl alcohol copolymer barrier layer is used. During packaging, a commercially available food-grade iron-based deoxidizer packet is placed in the top space inside the packaging, and the deoxidizer packet does not directly contact the surface of the sauce.

[0083] Comparative Example 1: Compared with Example 1, the difference is that the water addition and desalination step is not performed, nor is the subsequent cyclic concentration and resalting step; the fermented raw sauce to be treated prepared in Example 1 is directly taken out and spread flat on a conveyor belt, and irradiated with 60Co γ-rays at an ambient temperature of 2.0℃ and then packaged. All other aspects are the same.

[0084] Comparative Example 2: Compared with Example 1, the difference is that: closed external circulation sampling reflux pipeline sampling, online microfilter liquid phase extraction and ATR-FTIR continuous spectroscopy determination are not performed; after adding sterile water to reduce the sodium chloride mass fraction of the fermented sauce to 13.5%, the mechanical stirring state is fixed for 45 minutes, and then the resalting program in the vacuum reactor is directly started, and the rest are the same.

[0085] Comparative Example 3: Compared with Example 1, the difference is that: in the resalting step, atmospheric pressure microwave heating and vacuum flash evaporation cycle operation are not used. Instead, the steam heating system of the reactor jacket is turned on under atmospheric pressure of 95.0 kPa to 105.0 kPa to evaporate the water. After the sodium chloride mass fraction of the fermented sauce is restored to 16.0%, the steam is turned off. Then, chilled water is introduced into the jacket and mechanical stirring is used to cool down until the temperature of the material center drops to 2.0°C. The rest are the same.

[0086] Comparative Example 4: Compared with Example 1, the difference is that after the concentrated double salt operation is completed, high-purity nitrogen gas (instead of oxygen-nitrogen mixture with an oxygen volume fraction of 18.0%) is introduced into the reactor until the absolute pressure inside the reactor is restored to 95.0 kPa to 105.0 kPa; the rest of the steps are the same.

[0087] Comparative Example 5: Compared with Example 1, the difference is that in the packaging step after irradiation, a commercially available ordinary single-layer polyethylene food packaging bag is used to seal the sauce at normal pressure, and no vacuuming, nitrogen filling, or iron-based deoxidizer pack is used; the remaining steps are the same.

[0088] Test Example 1: Test objective: To verify the dynamic change law of glycerol concentration in the fermented raw sauce liquid phase caused by desalination operation, and to test the consistency of the response of the ATR-FTIR spectrometer and its flow cell to the inflection point of this concentration change.

[0089] The experimental steps are as follows: The fermented raw sauce material from Example 1, after the main fermentation was completed and transferred to the vacuum reactor, was used as the sampling object. The moment when sterile water was pumped into the reactor to start the desalination operation was recorded as the 0-minute starting point.

[0090] While maintaining mechanical stirring in the reactor, the material inside the reactor is periodically sampled through a pre-reserved sampling valve at the front end of the closed external circulation sampling reflux pipeline. The sampling interval is set to 10 minutes for the 0 to 30 min and 40 to 60 min stages, and the sampling interval is adjusted to 2 minutes for the 30 to 40 min stage.

[0091] After centrifugation to remove the solid phase, the obtained material was filtered through a 0.22-micron filter membrane, and the concentration of glycerol in the liquid phase was quantitatively determined using high-performance liquid chromatography (HPLC). Chromatographic analysis was performed using an amino column with a mobile phase of acetonitrile and water at a volume ratio of 75:25. The column temperature was set at 35°C, the detection flow rate was 1.0 mL / min, and a differential refractive index detector was used for detection.

[0092] While sampling at fixed points, data recorded by the ATR-FTIR spectrometer at the back end of the online microfilter is extracted, and the first derivative values ​​of the characteristic absorption signals in the wavenumber range of 1030 to 1050 at each sampling time point are exported.

[0093] The experimental results are shown in Table 1: Table 1: Dynamic Response Data of Liquid Phase Glycerol Concentration and First Derivative of Characteristic Spectral Signals during Salt Desalination Process

[0094] according to Figure 2 According to the data in Table 1, after the desalting treatment began, the concentration of glycerol in the liquid phase increased slowly from 0 to 20 minutes, rose significantly from 30 to 36 minutes, and reached a peak of 8.35 g / L at 36 minutes; thereafter, the concentration gradually decreased. Correspondingly, the first derivative of the characteristic absorption signal in the wavenumber range of 1030 to 1050 remained positive and continued to increase in the early stage, decreased to 0.15 at 36 minutes, and then turned negative. This indicates that there is a good correlation between the change in the online spectral derivative and the peak position of the offline glycerol concentration. Using the smoothed first derivative entering the range of -0.20 to 0.20 as the starting criterion for the resalting procedure can well correspond to the inflection point of the liquid phase glycerol concentration, thus providing an online judgment basis for the start time of the resalting step.

[0095] Test Example 2: Test objective: To verify the linear correlation between optical integral data and offline chromatographic quantitative results of an online continuous monitoring scheme combining a closed external circulation sampling reflux pipeline, an online microfilter, and an ATR-FTIR spectrometer when processing fermented sauces containing solid particles.

[0096] The experimental steps are as follows: The materials in the desalination stage of Examples 1, 2, and 3 were used as the observation objects. After the mechanical stirring and desalination operation was started, the material pump of the closed external circulation sampling return pipeline and the online microfilter with the corresponding pore size were turned on simultaneously.

[0097] At the 15th, 25th, 32nd, 38th and 45th minutes of the desalination program, the real-time peak area integral values ​​of the characteristic absorption signals of the ATR-FTIR flow cell in the wavenumber range of 1030 to 1050 were retrieved.

[0098] While reading the spectral data, the material inside the reactor was sampled via the sampling valve at the front end of the bypass route. The sampled material was centrifuged and filtered through a 0.22-micron filter membrane to obtain a clear liquid matrix. The concentration of free glycerol in the clear liquid was determined using a high-performance liquid chromatograph equipped with a differential refractive index detector.

[0099] The online spectral peak area integral data and offline chromatographic detection concentration data of each embodiment at different sampling points were summarized to establish discrete data pairs and perform linear regression processing.

[0100] The experimental results are shown in Table 2: Table 2: Spectral peak area integral and offline glycerol concentration data during the salt reduction phase of each embodiment.

[0101] according to Figure 3 According to the data in Table 2, the online spectral peak area integral values ​​of Examples 1 to 3 during the desalination stage are positively correlated with the offline measured glycerol concentration. The scatter points are concentrated near the regression line, and the linear determination coefficients are all greater than 0.995. Despite differences in material ratios, filter pore sizes, and stirring speeds, different examples still obtained high linear correlation results. This indicates that the online monitoring method using a closed external circulation sampling reflux pipeline combined with an online microfilter and an ATR-FTIR spectrometer can continuously track changes in glycerol concentration in the liquid phase of high-viscosity fermented sauce and can be used to assist in determining the start-up time of subsequent process steps.

[0102] Test Example 3: Test objective: To test the effect of alternating microwave and vacuum operation on the internal temperature distribution during the material dehydration and cooling process, and to compare its difference with that of traditional atmospheric pressure evaporation and jacket cooling in terms of heat transfer uniformity.

[0103] The experimental steps are as follows: The materials from Example 1 and Comparative Example 3 that entered the dehydration and cooling stage were used as test objects. Thermocouple sensors were arranged in the two sets of reactors, and the temperature probes were fixed at the geometric center point of the material in the reactor and at the edge 15 mm away from the inner wall of the jacket, respectively.

[0104] The moment when Example 1 completes its first microwave heating cycle and starts vacuum flash evaporation is recorded as the 0-minute starting point; the moment when Comparative Example 3 completes atmospheric pressure steam evaporation, shuts off the steam, and introduces chilled water into the jacket for cooling is recorded as the 0-minute starting point.

[0105] Maintain the stirring speed in both reactors at the same rate. Read the thermocouple data at the center and edge every 10 minutes, and continue recording until the temperature at the center of the material drops to around the preset 2.0℃.

[0106] Organize the temperature records during the monitoring period and compare the temperature difference changes at different locations of the material under the two heat transfer mechanisms.

[0107] The experimental results are shown in Table 3: Table 3: Center and edge temperature records of Example 1 and Comparative Example 3 during the concentration and cooling phase

[0108] Note: / indicates that the measurement has reached the target temperature and the recording has stopped. Comparative Example 3 uses atmospheric pressure steam to evaporate water, and its initial recording temperature at 0 min corresponds to the baseline temperature of the material under atmospheric pressure boiling conditions.

[0109] according to Figure 4 Based on the data in Table 3, Example 1 reduced the material's center temperature to 2.1°C within 60 minutes, and the temperature difference between the geometric center and the near-wall edge remained small throughout the recording period. Comparative Example 3 showed a significantly larger temperature difference between the center and edge at the same stage, remaining close to 30°C even at 30 minutes, and the overall cooling time was significantly prolonged. These results indicate that the alternating microwave heating and vacuum flash evaporation method used in Example 1 can achieve a more uniform internal temperature distribution during the concentration and cooling stage, and shorten the time required for the material to reach the target temperature.

[0110] Test Example 4: Test objective: To determine the inactivation level of high-osmotic-tolerant bacteria in the fermented raw sauce matrix by the combined process of salt reduction intervention, oxygen irradiation and deoxygenation packaging, and to evaluate the tendency of packaged products to swell during accelerated storage.

[0111] The experimental steps are as follows: Fermented original sauce products prepared in Examples 1 to 4, as well as Comparative Examples 1, 2, 4 and 5 and which have been packaged in soft packaging, were selected as test subjects.

[0112] Initial viable counts were determined on the first day after sample packaging. Samples from each group were randomly selected in a sterile operating room, and the packaging was cut open. 10 grams of the sauce was added to sterile physiological saline for homogenization and diluted. The samples were then inoculated onto a culture medium using the spread plate method. After incubation at a suitable temperature for 48 hours, the total number of osmotic-tolerant yeasts and lactic acid bacteria communities was counted and calculated.

[0113] The remaining individually packaged samples from each group were placed in a 37°C incubator for a 30-day accelerated storage test. After the test period, the volume expansion rate of the packaging bags was determined and calculated using the displacement volume method, which is expressed as the percentage increase in volume after the test compared to the initial volume.

[0114] After the volume measurement is completed, the puncture probe of a portable headspace gas analyzer is used to pierce the inside of the packaging bag, extract the headspace mixed gas, and measure and record the cumulative volume fraction of carbon dioxide inside the packaging.

[0115] The experimental results are shown in Table 4: Table 4: Initial viable bacterial count and packaging gaseous indicators after 30 days of accelerated storage for each group of samples

[0116] according to Figure 5 According to the data in Table 4, Examples 1 to 4 showed lower residual bacterial counts at the initial packaging stage, lower packaging volume expansion rate after 30 days of accelerated storage, and lower headspace CO2 accumulation compared to the comparative examples. Specifically, Comparative Examples 1 and 2 showed significantly higher initial viable bacterial counts and subsequent bag expansion rates than the Example group, while Comparative Examples 4 and 5 showed significantly higher packaging gas indicators after accelerated storage than the Example group. These results indicate that the combined process of desalination-resalination treatment, online monitoring triggering, pre-irradiation atmosphere conditioning, and post-irradiation low-oxygen packaging plays a positive role in reducing the risk of gas generation and bulging in packaged samples during storage.

[0117] Test Example 5: Test objective: To determine the retention of heat-sensitive components and appearance color of fermented sauces by microwave-vacuum alternating concentration and irradiation processes, and to evaluate the differences in physicochemical index loss among different treatment processes.

[0118] The experimental steps are as follows: The finished products processed and packaged according to the entire process of Examples 1 to 4, and the packaged sample of Comparative Example 3 after atmospheric pressure steam concentration and jacket cooling were used as test objects. At the same time, the untreated initial fermented sauce of each group was retained as a reference comparison.

[0119] The content of hydroxymethylfurfural was determined by high performance liquid chromatography (HPLC). The homogenized sample was weighed, and protein was removed by precipitation using a solution of potassium ferrocyanide and zinc acetate. After centrifugation and filtration, the supernatant was injected into an HPLC system equipped with a UV detector. The peak area was recorded and the concentration was calculated.

[0120] The amino acid nitrogen content was determined by formaldehyde titration. A sample dilution was measured, the pH was adjusted, and neutral formaldehyde solution was added to fix the amino groups. Titration was then performed using a standard sodium hydroxide solution, and the amino acid nitrogen content was calculated. The amino acid nitrogen retention rate was obtained by dividing the final product content by the corresponding initial reference content.

[0121] The color of the sample was measured using an integrating sphere colorimeter. The sample was placed in a transparent cuvette, and the lightness index, red-green index, and yellow-blue index were recorded. The total color difference deviation between the finished product and the initial reference material was calculated using the spatial distance formula.

[0122] The experimental results are shown in Table 5: Table 5: Test data of heat damage markers and physicochemical properties of fermented sauces after different processing techniques

[0123] according to Figure 6 According to the data in Table 5, the hydroxymethylfurfural content of samples 1 to 4 ranged from 1.85 to 4.42 mg / kg, the amino acid nitrogen retention rate was all above 95%, and the total color difference deviation was all below 3; the hydroxymethylfurfural content of Comparative Example 3 was 32.75 mg / kg, the amino acid nitrogen retention rate was 78.4%, and the total color difference deviation was 11.23. These results indicate that the microwave-vacuum alternating concentration and irradiation treatment process used in the examples has less impact on the color and physicochemical properties of the fermented sauce compared to the atmospheric pressure steam concentration and jacket cooling method, and is more conducive to maintaining the overall color and amino acid nitrogen level of the samples before and after treatment.

[0124] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A composite irradiation process for producing fermented soybean paste, characterized in that, Includes the following steps: S1: Place the fermented raw sauce to be processed in a vacuum reactor equipped with an online infrared spectroscopy monitoring device and an industrial microwave source, add sterile water to the vacuum reactor and mechanically stir to obtain the fermented sauce body, so as to reduce the mass fraction of sodium chloride in the fermented sauce body. S2: While maintaining mechanical stirring, the liquid phase of the fermented sauce is continuously extracted and the infrared spectrum of the liquid phase is continuously collected using the online infrared spectroscopy monitoring device, and the 1030 cm⁻¹ value is calculated. -1 ~1050cm -1 The first derivative of the peak area or absorbance of the characteristic absorption signal within the wavenumber range as a function of time; S3: When the first derivative of the characteristic absorption signal decreases from a positive value and first enters the range of -0.20 to 0.20, the concentration and redistribution program is initiated; the concentration and redistribution program includes: The material is microwave-heated by an industrial microwave source under an absolute pressure of 95.0 kPa to 105.0 kPa. Then, a vacuum pump is turned on to perform vacuum flash evaporation to remove water and cool down. The alternating operation of microwave heating and vacuum flash evaporation to remove water and cool down is repeated until the sodium chloride mass fraction of the fermented sauce is restored to 16.0% and the temperature at the center of the material drops to 0.0℃ to 4.0℃. S4: After the concentrated salt process is completed, oxygen-containing mixed gas is introduced into the vacuum reactor until the absolute pressure inside the vacuum reactor is restored to 95.0 kPa to 105.0 kPa, and maintained at 95.0 kPa to 105.0 kPa for 5 min to 15 min. S5: Take out the processed sauce and spread it out flat. Under an ambient temperature of 0.0℃~4.0℃, use a 60Co γ-ray irradiation source to penetrate and irradiate the spread sauce. S6: After the penetration irradiation is completed, the sauce is sealed with nitrogen-filled deoxygenated packaging material using high-barrier composite packaging material.

2. The composite irradiation process for producing fermented soybean paste according to claim 1, characterized in that, In step S1, sterile water is added until the sodium chloride mass fraction of the fermented sauce drops to 12.5%–14.5%.

3. The composite irradiation process for producing fermented soybean paste according to claim 1, characterized in that, The online infrared spectroscopy monitoring device includes a closed external circulation sampling reflux pipeline, an online microfilter, an ATR-FTIR spectrometer, and an ATR-FTIR spectrometer flow cell. In step S2, specifically: a portion of the liquid is continuously drawn out through the closed external circulation sampling reflux pipeline, filtered and extracted by the online microfilter to obtain a clear liquid phase, and the clear liquid phase is pumped into the flow cell of the ATR-FTIR spectrometer for continuous infrared spectroscopy acquisition. The pore size of the online microfilter is 0.8 μm to 2.0 μm, and the flow rate of the clear liquid phase pumped into the ATR-FTIR spectrometer flow cell is 15 mL / min to 25 mL / min.

4. The composite irradiation process for producing fermented soybean paste according to claim 1, characterized in that, In step S3, the specific parameters of the concentrated double salt program are as follows: turn on an industrial microwave source with a frequency of 915MHz or 2450MHz, set the microwave power density to 1.5kW / kg~2.5kW / kg, and continue heating for 25s~40s before turning off the industrial microwave source; then turn on the vacuum pump to reduce the absolute pressure in the vacuum reactor to 400Pa~800Pa within 8s~15s, and maintain it for 50s~70s for vacuum flash evaporation to remove water and cool down; after a single operation is completed, repeat the above alternating cycle of industrial microwave heating and vacuum flash evaporation to remove water and cool down until the target parameters set in step S3 are met.

5. The composite irradiation process for producing fermented soybean paste according to claim 1, characterized in that, In step S4, the oxygen-containing mixed gas is an oxygen-nitrogen mixed gas with an oxygen volume fraction ranging from 15.0% to 21.0%.

6. The composite irradiation process for producing fermented soybean paste according to claim 1, characterized in that, In step S5, the processed sauce is taken out and spread out, with the thickness of the layer controlled to be 8mm to 12mm, and the material absorption dose controlled to be 6.0kGy to 8.0kGy.

7. The composite irradiation process for producing fermented soybean paste according to claim 1, characterized in that, In step S6, nitrogen filling and deoxygenation sealing are performed within 10 to 20 minutes after the penetration irradiation ends; the high-barrier composite packaging material is a multi-layer composite film or aluminum-plastic composite film containing an ethylene-vinyl alcohol copolymer barrier layer; during nitrogen filling and deoxygenation sealing, a food-grade iron-based deoxidizer pack or an ascorbic acid-based deoxidation label is placed inside the packaging, and neither the food-grade iron-based deoxidizer pack nor the ascorbic acid-based deoxidation label is in direct contact with the surface of the sauce.

8. The composite irradiation process for producing fermented soybean paste according to claim 1, characterized in that, In step S1, the pretreatment preparation steps of the fermented raw sauce to be processed include: S11: After soaking and adjusting the moisture content, defatted soybeans are placed in an atmospheric pressure environment for industrial microwave heating treatment. After the industrial microwave heating treatment is completed, they are cooled to obtain cooled defatted soybeans. S12: Cooled defatted soybeans are mixed evenly with wheat flour, fresh chili flakes with a particle size distribution of 2.0mm to 5.0mm, sodium chloride, and sterile water to obtain a mixture. S13: Inoculate the mixture with Aspergillus oryzae and carry out fermentation at a low temperature. When the amino acid nitrogen content in the mixture reaches 0.70g / 100g to 0.85g / 100g, terminate the main fermentation. S14: After terminating the primary fermentation, the mixture is cooled and inoculated with post-fermentation guiding bacteria for post-fermentation. When the pH of the mixture drops to 4.15-4.35 and the mass concentration ratio of acetic acid to lactic acid in the liquid phase reaches 0.10-0.30, the post-fermentation is terminated to obtain the fermented raw sauce to be processed.

9. The composite irradiation process for producing fermented soybean paste according to claim 8, characterized in that, In step S11, after soaking defatted soybeans, the moisture content is adjusted to 45.0% to 50.0%. Microwave heating treatment is performed using an industrial microwave generator with a frequency of 915MHz or 2450MHz, controlling the microwave specific energy consumption to be 250kJ / kg to 350kJ / kg, and the treatment time to be 3.0min to 5.0min. After the industrial microwave heating treatment is completed, the temperature is cooled to 25℃.

10. The composite irradiation process for producing fermented soybean paste according to claim 8, characterized in that, The control parameters for steps S13 and S14 are: In step S13, Aspergillus oryzae is inoculated at 0.1wt% to 0.3wt% of the total dry weight of the mixture and placed in an environment of 38℃ to 41℃ for heat preservation and fermentation; In step S14, the temperature of the mixture is lowered to 26℃~29℃, and a post-fermentation guide group composed of halophilic tetracocci and Lactobacillus plantarum is introduced at 0.05wt%~0.15wt% of the total dry weight of the mixture.

Images