Processing method of cold-sterilized fermented tomato juice

Abstract

The invention discloses a processing method of cold-sterilized fermented tomato juice, and belongs to the technical field of food processing. Aiming at the technical problems of flavor deterioration and nutrition loss caused by thermal sterilization in the existing fermented tomato juice processing and easy post-acidification and short shelf life of a fermented product, the method comprises the following steps: pulping tomatoes and adding a carbon source and prebiotics; performing ultrahigh pressure sterilization for 3 to 4 minutes under the pressure of 550 to 600 MPa and the temperature of 10 to 15 DEG C; raising the temperature to 28-30 DEG C, inoculating oenococcus and fermenting for 24-36 hours; performing medium-pressure treatment for 8-12 minutes at the pressure of 400-500 MPa and the temperature of 15-20 DEG C to induce the oenococcus to enter a live non-culturable state; inoculating lactobacillus plantarum, and fermenting at 37 + / -1 DEG C until the pH is reduced to 3.6-3.9; carrying out solid-liquid separation, homogenizing and degassing; and finally, continuously sterilizing by adopting ultraviolet rays, inactivating the yeast and the mould by utilizing the sensitivity difference of the yeast mould and the oenococcus to the ultraviolet rays, filling, and refrigerating and storing. The method is mainly used for producing high-quality fermented tomato juice, post-acidification can be inhibited while heat damage is avoided, and the refrigeration shelf life of the product is remarkably prolonged.

Description

Technical Field

[0001] This invention relates to the field of food processing technology, specifically to a method for processing cold-sterilized fermented tomato juice. Background Technology

[0002] Tomato juice and its fermented products hold a certain share of the fruit and vegetable beverage market due to their rich nutritional content and good flavor. Current tomato juice processing methods mainly fall into three categories: clear tomato juice and cloudy tomato juice for direct consumption, as well as fermented tomato juice beverages. In industrial production, sterilization is typically required to extend shelf life and ensure microbiological safety.

[0003] For non-fermented tomato juice, the common sterilization method is heat sterilization, such as pasteurization or high-temperature flash sterilization. However, tomato juice is highly heat-sensitive and easily develops a cooked taste when heated, resulting in the loss of its original fresh flavor. Furthermore, heat-sensitive nutrients such as lycopene and vitamin C are prone to degradation during heat treatment, affecting the final quality of the product. To reduce heat damage, some processing technologies have attempted to use non-thermal sterilization methods such as ultra-high pressure (UHPP) to replace heat treatment. However, UHPP alone is often ineffective at completely inactivating endogenous enzymes in tomato juice (such as pectin methylesterase and polyphenol oxidase), which may lead to juice separation, browning, or flavor deterioration during subsequent storage. Therefore, it is still necessary to combine UHPP with refrigeration or other methods to maintain quality.

[0004] In the fermented tomato juice industry, existing processes typically employ a sterilization-fermentation-first approach. The sterilization process also faces the challenge of heat-sensitive quality loss. Furthermore, the selection of fermentation strains and the control of the fermentation process directly impact the product's flavor. Single-strain fermentation often results in a relatively monotonous flavor, and improper control of the fermentation endpoint can easily lead to excessive acidity. More critically, active fermentation bacteria remain in the product after fermentation. These bacteria may continue to metabolize during the long refrigerated sales period, slowly producing acid using residual sugars and other nutrients in the juice, causing a continuous drop in pH and resulting in "post-acidification." Post-acidification is a common technical challenge in fermented fruit and vegetable juice beverages, causing the product to gradually become sour, disrupting the flavor balance, and severely shortening its shelf life. To address post-acidification, the industry often uses heat sterilization after fermentation to inactivate the fermentation bacteria, but this again causes heat damage to the product, contradicting the initial goal of preserving fresh flavor. Summary of the Invention

[0005] This invention provides a cold-sterilized fermented tomato juice processing method, which can obtain good product flavor through two-stage fermentation while avoiding flavor deterioration and nutrient loss caused by heat sterilization. It also uses medium-pressure induction treatment to put the serotonin into a live, non-culturable state to inhibit post-acidification, and uses ultraviolet light to selectively kill yeast and mold, thereby effectively extending the shelf life of the product under refrigeration conditions.

[0006] To achieve these objectives and other advantages of the present invention, a method for processing cold-sterilized fermented tomato juice is provided, comprising the following steps: S1. Tomato raw materials are pulped to obtain tomato pulp, and carbon source and prebiotics are added to the tomato pulp to adjust the composition; S2. Ultra-high pressure sterilization: The adjusted tomato pulp is held at a pressure of 550-600 MPa and a temperature of 10-15℃ for 3-4 minutes. S3, First stage fermentation: Heat the sterilized tomato pulp to 28-30℃, inoculate with activated saccharin, and ferment at a constant temperature of 28-30℃ in a sealed environment for 24-36 hours. S4. Medium-pressure induction treatment: The tomato pulp after the first stage of fermentation is subjected to medium-pressure treatment. The pressure is maintained at 400-500MPa and the temperature is 15-20℃ for 8-12 minutes to induce the *Sacchariformis* to enter a live, non-culturable state. S5. Second stage fermentation: Inoculate with activated Lactobacillus plantarum and ferment at a constant temperature of 37±1℃ until the pH drops to 3.6-3.9, then terminate the fermentation. S6. After the fermentation is complete, the tomato pulp is subjected to solid-liquid separation, homogenization and deaeration; S7. Continuous ultraviolet sterilization is adopted, which utilizes the difference in sensitivity of yeast, mold and sacchariformis to ultraviolet light to inactivate yeast and mold, while maintaining the sacchariformis in an unculturable state. After sterilization, the product is immediately filled and sealed, and then refrigerated.

[0007] Preferably, in step S1, the carbon source is one or more of white sugar, fructose syrup or honey, and the amount added adjusts the soluble solids content of the tomato pulp to 12-15°Bx. The prebiotic is a mixture of fructooligosaccharides and inulin in a ratio of 6:4, with a total addition amount of 5% of the tomato pulp mass. In step S1, citric acid or malic acid is used to adjust the pH of the tomato pulp to 4.5-5.0.

[0008] Preferably, the inoculation amount of *Lactobacillus oryzae* in step S3 and the inoculation amount of *Lactobacillus plantarum* in step S5 are such that the total inoculation amount of the fermentation system is controlled at 1×10⁻⁶. 6 -1×10 7 Within the CFU / mL range; and the ratio of *Saccharomyces cerevisiae* to *Lactobacillus plantarum* is 2:8 to 4:6; The determination of the fermentation endpoint in step S5 is controlled by multidimensional indicators: fermentation is terminated when the pH drops to 3.6-3.9, the lactic acid content increases by ≥0.5% compared to the initial value, and the malic acid content decreases by ≥30%.

[0009] Preferably, the pressure holding time in step S4 is selected according to the fermentation time of the first stage: when the fermentation time of the first stage is 24-30 h, the pressure holding time is 10-12 min; when the fermentation time of the first stage is 30-36 h, the pressure holding time is 8-10 min; the medium pressure treatment causes the *Lactococcus* to enter a live, non-culturable state to inhibit lactic acid production during subsequent storage.

[0010] Preferably, the solid-liquid separation in step S6 adopts a two-stage separation process: first, a filter with a screen aperture of 0.5-1.0 mm is used for coarse filtration to remove fruit pulp fibers and bacterial clumps; then, a disc centrifuge is used at 4-10℃ and a speed of 5000-8000 rpm for 5-10 minutes.

[0011] Preferably, the homogenization in step S6 employs a two-stage homogenization process: the first homogenization pressure is 10-15 MPa, and the second homogenization pressure is 30-35 MPa; the degassing is carried out under a vacuum of 0.06-0.08 MPa, and nitrogen is introduced for protection during the degassing process, or nitrogen is introduced into the headspace after degassing to replace residual oxygen.

[0012] Preferably, in step S6, 0.01-0.05% of a natural antioxidant is added to the degassed tomato pulp, wherein the natural antioxidant is at least one of ascorbic acid or tea polyphenols.

[0013] Preferably, in step S6, after solid-liquid separation and before homogenization, a stabilizer mixture is added to the tomato pulp. The stabilizer mixture is composed of modified starch, xanthan gum and sodium carboxymethyl cellulose in a mass ratio of 2:0.5:1, and the amount added is 0.5%-1% of the mass of the tomato pulp.

[0014] Preferably, the ultraviolet light used in step S7 has a wavelength of 254 nm, an irradiation dose of 50-200 mJ / cm², and a treatment time of 5-15 s; after treatment, it is immediately filled and sealed, and stored at 2-6℃.

[0015] Preferably, the pulping process in step S1 is carried out under the protection of nitrogen or carbon dioxide inert gas, and the pulping temperature is controlled at 15-25℃.

[0016] The present invention has at least the following beneficial effects: First, this invention uses ultra-high pressure cold sterilization instead of traditional heat sterilization, avoiding the loss of cooked flavor and heat-sensitive nutrients in tomato juice; through two-stage fermentation, it utilizes *Lactobacillus plantarum* and *Lactobacillus plantarum* respectively, making the product flavor richer and more harmonious; medium-pressure induction treatment puts *Lactobacillus plantarum* into a live, non-culturable state, so it no longer metabolizes and produces acid during subsequent refrigeration, effectively inhibiting post-acidification and extending the product's shelf life; ultraviolet selective sterilization utilizes the difference in sensitivity of yeast and mold to ultraviolet light to kill spoilage bacteria without activating *Lactobacillus plantarum*, avoiding damage to product quality from secondary heating; the entire process is completed under low temperature or room temperature conditions, preserving the natural color, aroma, and nutrients of tomatoes to the greatest extent.

[0017] Secondly, this invention adjusts the soluble solids content to 12-15°Bx to provide a suitable carbon source concentration for subsequent fermentation, which can ensure the growth and metabolism of the strain while avoiding osmotic pressure inhibition caused by excessive sugar. The 6:4 ratio of fructooligosaccharides and inulin is used as a prebiotic, which can not only selectively promote the proliferation of beneficial bacteria, but also give the product additional dietary fiber function. The initial pH is adjusted to 4.5-5.0, which is close to the natural acidity of tomato raw materials and creates a suitable acid-base environment for the start of malic-lactic fermentation by *Saccharomyces cerevisiae*, ensuring the smooth start of fermentation.

[0018] Third, this invention controls the total inoculation amount to 1×10 6 -1×10 7 Within the CFU / mL range, fermentation efficiency is ensured while avoiding excessive inoculum leading to rapid metabolism and a coarse flavor. A ratio of *Lactobacillus plantarum* to *Lactobacillus* of *Bacillus* is used to balance malic acid degradation and lactic acid production, resulting in a smooth and rounded product taste. Multidimensional indicators such as pH, lactic acid increment, and malic acid decrease are used to control the fermentation endpoint, providing greater precision than a single pH assessment. This ensures sufficient malic acid conversion and appropriate lactic acid accumulation, preventing under- or over-fermentation. The medium-pressure holding time is dynamically adjusted based on the first-stage fermentation time; shorter holding times are used for shorter fermentation times, while longer holding times are appropriately extended. This differentiated treatment makes the induction effect of *Bacillus plantarum* more precise and controllable. Medium-pressure induction induces *Bacillus plantarum* into a viable, non-culturable state, preserving its potential contribution to flavor without killing the cells, and stopping its metabolic acid production during subsequent storage, fundamentally solving the common problem of post-acidification in fermented fruit and vegetable juices.

[0019] Fourth, this invention employs a two-stage separation process. First, coarse filtration removes large particles of fruit pulp fiber and bacterial clots, reducing the load on subsequent centrifugation. Then, a disc centrifuge is used at high speed under low temperature conditions to effectively remove fine suspended particles, resulting in a clear and transparent product. The low-temperature centrifugation conditions reduce oxidation and flavor loss during the separation process, while inhibiting microbial activity, ensuring the sensory quality and microbial stability of the product. During homogenization, the first low-pressure homogenization process initially breaks down large particles, while the second high-pressure process further refines the particles, forming a stable suspension system and preventing sedimentation and stratification during storage. Degassing is carried out under vacuum conditions to effectively remove dissolved oxygen, while nitrogen is introduced for protection or nitrogen is used to replace residual oxygen, significantly reducing the risk of oxidative browning and flavor deterioration, and maintaining the product's color and freshness. Adding trace amounts of natural antioxidants to the degassed tomato pulp can further remove residual dissolved oxygen and oxygen that has seeped in from the packaging, delay the oxidative polymerization of polyphenols, and inhibit browning and off-flavors. Ascorbic acid and tea polyphenols are both natural sources, which is in line with the product positioning of the clean label, and can play an effective antioxidant protection role even at low addition levels.

[0020] Fifth, a stabilizer mixture composed of modified starch, xanthan gum, and sodium carboxymethyl cellulose in a specific ratio forms a weak gel network structure through synergistic action, effectively suspending fruit pulp particles and bacterial fragments and preventing product stratification and sedimentation. Modified starch provides the main framework, xanthan gum enhances the viscosity and pseudoplasticity of the system, and sodium carboxymethyl cellulose improves dispersion stability. The combination of the three at an addition amount of 0.5%-1% can achieve good suspension effect without affecting the product's taste and flavor release.

[0021] Sixth, this invention uses 254 nm wavelength ultraviolet light, with an irradiation dose of 50-200 J / m² and a treatment time of 5-15 s. This parameter range can effectively destroy the DNA structure of yeast and mold to inactivate them, without penetrating or damaging the non-culturable sacchariformis. Immediately after treatment, the product is filled and refrigerated at low temperature, which further inhibits the activity of any remaining microorganisms. This ensures the microbial safety of the product while maintaining the non-culturable state of beneficial bacteria.

[0022] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0023] Figure 1 This is a schematic flowchart of the cold sterilization and fermentation tomato juice processing method of the present invention. Detailed Implementation

[0024] The present invention will now be described in further detail so that those skilled in the art can implement it based on the description.

[0025] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0026] like Figure 1 As shown, the present invention provides a method for processing cold-sterilized fermented tomato juice, comprising the following steps: S1. Tomato raw materials are pulped to obtain tomato pulp, and carbon source and prebiotics are added to the tomato pulp to adjust the composition.

[0027] In step S1, the pulping process is carried out under the protection of nitrogen or carbon dioxide inert gas, and the pulping temperature is controlled at 15-25℃. The carbon source is one or more of white sugar, fructose syrup, or honey, and its addition amount is adjusted to adjust the soluble solids content of the tomato pulp to 12-15°Bx; the prebiotic is a mixture of fructooligosaccharides and inulin in a ratio of 6:4, and the total addition amount is 5% of the mass of the tomato pulp; in step S1, citric acid or malic acid is also used to adjust the pH of the tomato pulp to 4.5-5.0.

[0028] In the above steps, ripe tomatoes are first selected, rinsed with running water, and the skin and stem are mechanically removed before pulping. Pulping aims to break down the tomato's cellular structure, allowing the juice and soluble solids to be fully released, providing a substrate for subsequent fermentation. To prevent polyphenol oxidation and flavor component volatilization due to mechanical shear heat and air contact during pulping, this step can be carried out under the protection of inert gases such as nitrogen or carbon dioxide, and the pulping temperature should be controlled within a suitable range, such as 15°C to 25°C, to minimize early quality deterioration of the raw materials. After obtaining the base pulp, its composition needs to be adjusted according to the growth requirements of the subsequent fermentation bacteria. The carbon source can be one or more of white sugar, fructose syrup, or honey, and the amount added should be adjusted to adjust the soluble solids content of the tomato pulp to 12 to 15°Bx. This sugar content range provides sufficient energy for the proliferation and metabolism of lactic acid bacteria without inhibiting bacterial activity due to excessive osmotic pressure. Simultaneously, to impart additional health benefits to the product and promote the growth of probiotics, prebiotics need to be added. For example, fructooligosaccharides and inulin can be mixed in a certain proportion and added, with the total amount added to the slurry typically controlled within a small percentage range. Furthermore, the pH of the tomato raw material itself may not be entirely suitable for initiating all fermentation strains. Therefore, at this step, edible acids such as citric acid or malic acid can be used to adjust the pH of the slurry to a slightly acidic environment, such as between 4.5 and 5.0, creating suitable conditions for the subsequent malolactic fermentation by *Saccharomyces cerevisiae*.

[0029] S2. Ultra-high pressure sterilization: The adjusted tomato pulp is held at a pressure of 550-600 MPa and a temperature of 10-15℃ for 3-4 minutes.

[0030] In the above steps, without introducing heat, any potential spoilage and pathogenic bacteria in the tomato pulp are killed, creating a sterile or near-sterile environment for subsequent pure culture fermentation. Specifically, the adjusted tomato pulp is sealed and packaged, then placed in an ultra-high pressure processing device under extremely high hydrostatic pressure. The pressure needs to reach a relatively high level, for example, within the range of 550 MPa to 600 MPa, while the processing temperature is maintained at a low temperature, such as 10°C to 15°C, with a relatively short holding time of approximately 3 to 4 minutes. Under this pressure condition, the cell morphology, cell membrane, and structure of biomolecules such as proteins and nucleic acids of the microorganisms undergo irreversible changes, leading to their inactivation. Because the entire process is carried out at room temperature or low temperature, it effectively avoids the cooking taste and the destruction of heat-sensitive nutrients, such as lycopene and vitamin C, that are associated with traditional heat sterilization, thus better preserving these nutrients.

[0031] S3. First stage fermentation: Heat the sterilized tomato pulp to 28-30℃, inoculate with activated sacchariformis, and ferment in a sealed environment at a constant temperature of 28-30℃ for 24-36 hours.

[0032] In the above steps, after the tomato pulp, sterilized by ultra-high pressure, is cooled or heated to a suitable fermentation temperature, it enters the first stage of fermentation. The core microorganism in this stage is *Saccharomyces cerevisiae*. Pre-activated *Saccharomyces cerevisiae* is inoculated into the sterilized tomato pulp, and fermentation is carried out in a sealed environment under constant temperature conditions. The fermentation temperature is usually controlled between 28℃ and 30℃, which is also the suitable temperature range for the growth and metabolism of *Saccharomyces cerevisiae*. The fermentation process lasts 24 to 36 hours. During this time, *Saccharomyces cerevisiae* utilizes the nutrients in the tomato pulp for growth and reproduction. Its most important metabolic activity is malolactic fermentation, which breaks down the high content of L-malic acid in tomatoes into L-lactic acid and carbon dioxide. This conversion process effectively reduces the acidity and astringency of the pulp, making the product's taste smoother and more rounded. In a complex fermentation system, inoculating *Saccharomyces cerevisiae* for a period of time has a positive impact on the subsequent overall flavor development.

[0033] S4. Medium-Pressure Induction Treatment: The tomato pulp after the first stage of fermentation is subjected to medium-pressure treatment at 400-500 MPa and 15-20℃ for 8-12 minutes to induce *Bacillus thuringiensis* into a viable, non-culturable state. After the medium-pressure induction treatment, the VBNC induction rate of *Bacillus thuringiensis* is detected by PMA-qPCR, with an induction rate ≥95% considered acceptable. The induction rate is calculated as: (Total bacterial count - Culturable bacterial count) / Total bacterial count × 100%, where the total bacterial count is detected by PMA-qPCR, and the culturable bacterial count is obtained by plate counting.

[0034] In step S4, the pressure holding time is selected according to the fermentation time of the first stage: when the fermentation time of the first stage is 24-30 h, the pressure holding time is 10-12 min; when the fermentation time of the first stage is 30-36 h, the pressure holding time is 8-10 min; the medium pressure treatment causes the sacchariformis to enter a live, non-culturable state to inhibit the production of lactic acid during subsequent storage.

[0035] In the above steps, after the first stage of fermentation, a medium-pressure induction treatment is immediately performed. The purpose is to induce the *Bacillus thuringiensis*, which has completed its main metabolic tasks, into a special physiological state, namely, the viable non-culturable state (VBNC). Specifically, the tomato pulp after the first stage of fermentation is subjected to high-pressure treatment again, but the pressure parameters differ from those in the sterilization step. The pressure needs to be reduced to a moderate range, such as 400 MPa to 500 MPa. The treatment temperature can be slightly higher than the previous step, such as 15°C to 20°C, and the holding time is controlled at 8 to 12 minutes. This medium-pressure condition is not enough to kill *Bacillus thuringiensis*, but it acts as a sublethal stress, triggering a stress response in the bacteria, causing their cells to enter a state of extremely low metabolic activity, where they cannot form colonies on conventional culture media but remain viable. *Bacillus thuringiensis* in this state will cease metabolic acid production during subsequent processing and storage, thus fundamentally solving the common problem of post-acidification in fermented fruit and vegetable juices—the phenomenon where the product becomes increasingly acidic during its shelf life due to continued fermentation by residual bacteria. To achieve the best induction effect, the holding time of the medium-pressure treatment can be fine-tuned according to the specific duration of the first stage of fermentation. For example, if the first stage of fermentation is short, the holding time can be shortened accordingly; conversely, if the fermentation time is long, the holding time can be appropriately extended to ensure that the serotonin can be accurately pushed into the target state.

[0036] In practice, the holding time for medium-pressure treatment needs to be differentiated based on the time of the first stage of fermentation. If the first stage fermentation time is 24-30 hours, it indicates that *Saccharomyces cerevisiae* is in a metabolically active phase and the cells are highly tolerant, so a holding time of 10-12 minutes is chosen. If the first stage fermentation time is 30-36 hours, it indicates that *Saccharomyces cerevisiae* may be entering the early stages of decline, and the cells are more sensitive to stress, so a holding time of 8-10 minutes is chosen. This medium-pressure treatment induces *Saccharomyces cerevisiae* into a viable, unculturable state to inhibit lactic acid production during subsequent storage. This strategy of dynamically adjusting the holding time based on fermentation time aims to ensure that different batches of *Saccharomyces cerevisiae* can be accurately induced into a viable, unculturable state, avoiding both induction failure due to excessively short holding times and direct cell death due to excessively long holding times.

[0037] In step S4, the medium-pressure induction treatment, using a precise combination of conditions—400-500 MPa, 15-20℃, and 8-12 min—applies sublethal stress to *Sacchariformis spp.* after the first stage of fermentation, thereby inducing it into a viable, unculturable state. The mechanism is as follows: high-pressure treatment effectively inhibits the riboflavin metabolic pathway within *Sacchariformis spp.* cells, leading to a significant reduction in key coenzymes such as flavin mononucleotide and flavin adenine dinucleotide in the respiratory chain. This blocks energy metabolism and reducing power generation, resulting in a comprehensive downregulation of cellular material transport, metabolic activity, and proliferation capacity, while maintaining the integrity of the cell membrane structure. After the medium-pressure induction treatment, the induction rate of the viable, unculturable state of *Sacchariformis spp.* is detected using PMA-qPCR, with an induction rate ≥95% considered acceptable. If the test results do not meet the standard, measures such as extending the holding time, increasing the pressure, or adjusting the first-stage fermentation time are taken to correct the deviation. Specifically: If the test results do not meet the qualified standard, graded adjustment measures shall be taken according to the degree of deviation: (1) When the induction rate is 80%-95%, it indicates that the induction is basically successful but slightly insufficient. At this time, the treated tomato pulp can be subjected to medium pressure treatment again, but the holding time is extended by 2-3 min on the original basis, or the pressure is increased by 20-30 MPa to enhance the induction effect. After treatment, it is necessary to retest and confirm. (2) When the induction rate is less than 80%, it indicates that the induction effect is seriously insufficient, which may be due to abnormal fermentation status in the first stage (such as insufficient activity of serotonin, improper fermentation time, etc.). At this time, the pulp should be returned to the S3 stage to analyze the cause, or the fermentation time in the first stage should be appropriately extended by 2-4 h and then the S4 medium pressure induction treatment should be carried out again. (3) If the induction rate fails to meet the standard in two consecutive batches, the activity of serotonin strain, the control of the fermentation temperature in the first stage, the raw material composition and other parameters should be systematically checked and corresponding calibrations should be carried out. In industrial production, it is recommended to sample and test each batch. Once the process is stable, this can be adjusted to sampling every 3-5 batches. However, a full inspection must be performed again when changing raw material batches or strain batches. Furthermore, the UV treatment in step S7 can be used to consolidate the VBNC status. For batches with an induction rate between 90% and 95%, the VBNC status can be tested again after S7 treatment to confirm whether the UV treatment has a consolidation effect. If the batch meets the pass standard after consolidation, it can be considered a qualified batch. This method can be used for process validation and batch sampling. In daily production, it can be indirectly controlled by establishing a correlation with process parameters.

[0038] Once the *Saccharomyces cerevisiae* enters this state, its metabolism ceases and it no longer produces acid during subsequent processing and refrigeration, thus fundamentally inhibiting post-acidification. Simultaneously, the subsequent ultraviolet (UV) treatment (step S7) not only utilizes the difference in UV sensitivity between yeasts and molds for selective sterilization but is also a form of non-thermal stress, further consolidating the VBNC state of *Saccharomyces cerevisiae*. The subsequent 2-6°C low-temperature refrigeration environment significantly delays the recovery process of VBNC bacteria, ensuring that the product maintains stable pH and consistent quality throughout its shelf life of over 12 weeks.

[0039] S5. Second stage fermentation: Inoculate with activated Lactobacillus plantarum and ferment at a constant temperature of 37±1℃ until the pH drops to 3.6-3.9, at which point the fermentation is terminated.

[0040] Regarding the inoculum size, the inoculum size of *Lactobacillus plantarum* in step S3 and the inoculum size of *Lactobacillus plantarum* in step S5 are controlled so that the total inoculum size of the fermentation system is controlled at 1×10⁻⁶. 6 -1×10 7 Within the CFU / mL range; and the ratio of *Saccharomyces cerevisiae* to *Lactobacillus plantarum* is 2:8 to 4:6; The determination of the fermentation endpoint in step S5 is controlled by multidimensional indicators: fermentation is terminated when the pH drops to 3.6-3.9, the lactic acid content increases by ≥0.5% compared to the initial value, and the malic acid content decreases by ≥30%.

[0041] In the above steps, after medium-pressure induction, the second stage of fermentation, step S5, begins. At this stage, another core fermentation strain—*Lactobacillus plantarum*—needs to be inoculated into the slurry. After the activated *Lactobacillus plantarum* solution is inoculated, the entire system undergoes isothermal fermentation at approximately 37°C. *Lactobacillus plantarum* is a homofermentative lactic acid bacterium that efficiently converts sugars into lactic acid, causing the pH of the system to drop rapidly. Fermentation terminates when the pH drops to the acidic range of 3.6 to 3.9. To more precisely control the fermentation endpoint and ensure a stable flavor profile, a multi-dimensional assessment can be used. In addition to monitoring the pH, the increase in lactic acid content and the decrease in malic acid content also need to be detected. Fermentation is considered complete only when all these indicators meet the preset requirements. During this stage, the initial inoculation ratio of *Lactobacillus plantarum* and *Lactobacillus plantarum* needs careful design. For example, they can be inoculated in a specific ratio to control the initial total bacterial count within a suitable range, ensuring a smooth transition between the two fermentation stages and harmonious flavor development.

[0042] Steps S3 and S5, involving inoculum control and the determination of multidimensional indicators of fermentation endpoint, are crucial for ensuring product flavor stability and fermentation efficiency. The inoculum amounts of *Lactobacillus oryzae* and *Lactobacillus plantarum* need to be controlled synergistically to maintain the total inoculum amount of the entire fermentation system within a suitable range. This range can be selected as 1 × 10⁻⁶. 6 Up to 1×10 7 The inoculum concentration should be between CFU / mL, meaning the total number of viable bacteria inoculated per milliliter of tomato pulp should be controlled at a level of several million to tens of millions. If the inoculum concentration is too low, fermentation will start too slowly, potentially allowing other microorganisms to invade; if the inoculum concentration is too high, the microbial growth and metabolism will be too vigorous, potentially leading to the rapid formation of flavor compounds and a coarse flavor, while also increasing the consumption of raw materials. *Sacchariformis* and *Lactobacillus plantarum* have a synergistic effect in malolactic fermentation; appropriate mixed inoculation can improve the efficiency of malic acid degradation and enrich the aroma compounds of the final product.

[0043] The ratio of *Saccharomyces cerevisiae* to *Lactobacillus plantarum* can be controlled within the range of 2:8 to 4:6. This ratio is designed to take into account the different roles of the two strains in the fermentation process. *Saccharomyces cerevisiae* is the main strain in malolactic fermentation, capable of converting pungent malic acid into mild lactic acid, making the product's taste more rounded. *Lactobacillus plantarum* has a strong sugar metabolism capacity, rapidly producing acid to lower the pH value, and its broad enzyme spectrum can generate richer flavor compounds. Within the 2:8 to 4:6 ratio range, the proportion of *Saccharomyces cerevisiae* is relatively small, but sufficient to initiate and complete the malolactic conversion; the larger proportion of *Lactobacillus plantarum* dominates the rapid acid production and flavor formation in the second stage. A sequential inoculation strategy, inoculating *Saccharomyces cerevisiae* first and then *Lactobacillus plantarum* after a certain time, can significantly improve the rate of malic acid degradation and enrich aroma compounds.

[0044] Determining the fermentation endpoint employs multidimensional index control, a crucial method for ensuring batch stability and flavor consistency. Specifically, when the pH value drops to the range of 3.6 to 3.9, fermentation is not immediately terminated; rather, changes in lactic acid and malic acid content must be simultaneously monitored. The lactic acid content needs to increase by a certain margin from the initial level, for example, by more than 0.5%. This indicates that *Lactobacillus plantarum* has produced sufficient lactic acid through sugar metabolism, providing the product with the appropriate acidity. The malic acid content needs to decrease by a certain margin from the initial level, for example, by more than 30%. This indicates that the malolactic fermentation of *Lactobacillus plantarum* has been fully completed, and the irritating malic acid has been converted into milder lactic acid. Only when all three indicators—pH, lactic acid increase, and malic acid decrease—meet the requirements simultaneously can fermentation be considered to have reached the ideal endpoint. Studies have shown that *Lactobacillus plantarum* can achieve a malic acid reduction rate of over 63% under optimized fermentation conditions, indicating that the 30% reduction target set in this claim is a relatively conservative and easily achievable goal.

[0045] In actual production, to address the time lag between online pH monitoring and offline biochemical detection, this method employs a "prediction + verification" control strategy. First, a pH change kinetic model for the fermentation system is established through process validation, determining that a high-frequency sampling procedure should be initiated when the pH approaches the target upper limit (e.g., 3.8-3.9). Second, a pH action threshold is set (e.g., 3.65-3.70, slightly higher than the target lower limit of 3.6, reserving a buffer). Once the online monitoring value reaches this threshold, the control system immediately triggers a cooling cycle, rapidly lowering the liquid temperature to below 15°C, pausing the fermentation process without waiting for test results. The sample taken at this time is analyzed in the laboratory and used for quality verification of the fermentation endpoint. If the verification reveals that the malic acid reduction or lactic acid increase does not meet the target, the residual reaction can be allowed to complete naturally during the low-temperature settling phase after cooling; if the verification meets the target, the process proceeds directly to the next step. This method ensures that the fermentation endpoint falls within the target range and solves the time lag problem in the operation process.

[0046] S6. After fermentation, the tomato pulp is subjected to solid-liquid separation, homogenization and deaeration.

[0047] In step S6, after solid-liquid separation and before homogenization, a stabilizer mixture is added to the tomato pulp. The stabilizer mixture is composed of modified starch, xanthan gum and sodium carboxymethyl cellulose in a mass ratio of 2:0.5:1, and the amount added is 0.5%-1% of the mass of the tomato pulp.

[0048] The solid-liquid separation in step S6 adopts a two-stage separation process: first, a filter with a screen aperture of 0.5-1.0 mm is used for coarse filtration to remove fruit pulp fibers and bacterial clumps; then, a disc centrifuge is used at 4-10℃ and a speed of 5000-8000 rpm for 5-10 minutes.

[0049] The homogenization in step S6 employs a two-stage homogenization process: the first homogenization pressure is 10-15 MPa, and the second homogenization pressure is 30-35 MPa. Degassing is carried out under a vacuum of 0.06-0.08 MPa, with nitrogen gas introduced for protection during the degassing process, or nitrogen gas is introduced into the headspace after degassing to replace residual oxygen. 0.01-0.05% of a natural antioxidant, at least one of ascorbic acid or tea polyphenols, is added to the degassed tomato pulp.

[0050] In the above steps, step S6, after solid-liquid separation and before homogenization, may selectively add a stabilizer mixture to further enhance the product's suspension stability during long-term storage. Although solid-liquid separation removes most of the solids from fermented tomato juice, the liquid still contains fine fruit pulp particles and microbial fragments. If these particles do not receive effective suspension support, they may slowly settle due to gravity during prolonged refrigerated storage, leading to product stratification and affecting consumer acceptance. The stabilizer mixture is composed of modified starch, xanthan gum, and sodium carboxymethyl cellulose in a specific ratio. Modified starch is a physically or chemically modified starch derivative with excellent thickening and suspension properties, capable of forming a weak gel network structure in liquid systems, providing a supporting framework for suspended particles. Xanthan gum is a microbial polysaccharide with excellent thickening and pseudoplasticity; that is, it has a high viscosity when still to suspend particles, and its viscosity decreases when stirred, making it easy to pour and drink. Sodium carboxymethyl cellulose is an anionic cellulose ether with good dispersibility and stability, improving the uniformity of particle dispersion in the system and preventing particle aggregation and sedimentation. The three components, combined in a mass ratio of 2:0.5:1, produce a synergistic effect: modified starch provides the main framework, xanthan gum enhances the system's viscosity and pseudoplasticity, and sodium carboxymethyl cellulose improves dispersion stability. In practice, the amount of stabilizer mixture added can be controlled between 0.5% and 1% of the tomato pulp mass. Choosing this range requires balancing suspension effects with taste: too low an amount may not form a sufficient network structure to support particle suspension; too high an amount may result in an overly viscous product with a heavy taste, affecting the refreshing drinking experience. Within the 0.5% to 1% range, the stabilizer forms a moderate network strength, effectively suspending fruit pulp particles and mycelial fragments without imparting a noticeable stickiness or pasty texture to the product.

[0051] Step S6 employs a two-stage solid-liquid separation process to effectively remove solids from the fermented slurry and obtain a clear and stable product. The tomato slurry after fermentation is a complex multiphase system containing incompletely decomposed pulp fibers, microbial clumps produced during fermentation, and potential sediments. If not effectively removed, these solids will not only affect the product's appearance and transparency but will also continue to settle during storage, leading to product stratification. Furthermore, the presence of microbial clumps may affect the product's microbial stability. The first stage of the two-stage separation process is coarse filtration, using a filter with a screen aperture of 0.5 to 1.0 mm. The aim is to quickly remove large particles, such as pulp fibers and larger microbial clumps, from the slurry. The selection of the screen aperture needs to balance filtration efficiency and impurity removal: apertures that are too small are prone to clogging, affecting production efficiency; apertures that are too large cannot effectively trap large particles. A aperture range of 0.5 to 1.0 mm effectively removes visible large particles while ensuring the slurry can pass smoothly through the filter. After coarse filtration, the solid content of the slurry is significantly reduced, creating conditions for subsequent fine separation. The second stage of the secondary separation process is centrifugation, conducted using a disc centrifuge at low temperatures. The centrifugal speed can be controlled within the range of 5000 to 8000 rpm. This speed generates sufficient centrifugal force to throw fine suspended particles against the centrifuge chamber wall, thereby achieving solid-liquid separation. Centrifugation needs to be carried out at low temperatures, controlled within the range of 4 to 10°C. The advantages of low-temperature centrifugation are: firstly, it inhibits the activity of microorganisms during the separation process, preventing possible spoilage; secondly, it reduces the temperature rise caused by mechanical friction, avoiding heat damage to the product flavor. The centrifugation time is controlled within 5 to 10 minutes, which is sufficient for the fine particles to settle sufficiently without affecting production efficiency due to excessive time. After secondary separation, the resulting clear liquid is bright and clear, with a significantly reduced solid content, providing a good material basis for subsequent homogenization, degassing, and filling processes. The separated solids can be further processed or utilized.

[0052] The homogenization process employs a two-stage process to achieve better particle refinement through staged pressurization. The first homogenization is carried out under relatively low pressure, controlled within the range of 10 to 15 MPa. The main purpose of this step is to initially break up any potential fine particle agglomerates, creating a homogeneous material state for the second homogenization. The second homogenization is carried out under higher pressure, controlled within the range of 30 to 35 MPa. Under this pressure condition, particles or fat globules in the liquid are subjected to intense shearing, impact, and cavitation, further refining them into a more uniform particle size distribution. The combined use of these two homogenization processes results in a finer and more uniform particle size distribution than single-stage homogenization, thus forming a more stable suspension system and effectively preventing sedimentation and stratification during product storage.

[0053] Degassing is performed under vacuum conditions, with the vacuum level controlled within the range of 0.06 to 0.08 MPa. At this vacuum level, dissolved oxygen in the liquid escapes due to the pressure reduction and is removed by the vacuum system. To further reduce the risk of oxidation, nitrogen can be introduced into the slurry during degassing. Nitrogen is an inert gas and does not participate in the oxidation reaction; its introduction forms a protective gas layer on the liquid surface, preventing oxygen from the air from dissolving back into the liquid. Alternatively, after degassing, nitrogen can be introduced into the headspace of the packaging container to replace any residual oxygen. Both methods effectively reduce the product's contact with oxygen, inhibiting oxidative browning and flavor deterioration.

[0054] After two homogenization and vacuum degassing processes, the physical stability and antioxidant capacity of the tomato juice were significantly improved. Homogenization refines the particles, forming a stable suspension system; degassing removes dissolved oxygen and slows down the oxidation reaction.

[0055] Step S6, after degassing, can selectively add natural antioxidants to further enhance the product's antioxidant protection. Even after vacuum degassing and nitrogen protection, the product may still undergo slow oxidation during subsequent storage and transportation due to trace amounts of oxygen permeating the packaging materials or oxygen seeping in due to inadequate sealing. Adding an appropriate amount of natural antioxidant can promptly remove these trace amounts of oxygen when they enter the system, thus providing continuous antioxidant protection for the product. Natural antioxidants can be at least one of ascorbic acid or tea polyphenols. Ascorbic acid, also known as vitamin C, is a water-soluble natural antioxidant that preferentially reacts with oxygen, thereby protecting other more easily oxidized substances such as polyphenols and flavor components from oxidation. Ascorbic acid itself is a naturally occurring nutrient in tomatoes, and its addition will not introduce exogenous substances. Tea polyphenols are natural polyphenolic compounds extracted from tea leaves, possessing strong free radical scavenging capabilities and antioxidant activity, effectively inhibiting lipid peroxidation and pigment fading. Studies have shown that when tea polyphenols are used in combination with synergists such as ascorbic acid, they can produce a synergistic effect, with significantly higher antioxidant effects than single components. In practice, the amount of natural antioxidants added can be controlled at an extremely low level, for example, between 0.01% and 0.05% of the tomato pulp mass. This range of addition considers two factors: firstly, ensuring sufficient addition to provide effective antioxidant protection; and secondly, controlling the level to avoid adverse effects on the flavor and taste of the product. At an addition level of 0.01% to 0.05%, neither ascorbic acid nor tea polyphenols will cause a noticeable increase in sourness or astringency, while effectively inhibiting oxidation reactions. The timing of addition is chosen after degassing, because degassing removes most of the dissolved oxygen, allowing the antioxidant to act more effectively on residual trace oxygen and subsequently introduced oxygen. If added before degassing, some antioxidants may be consumed during the degassing process, reducing their sustained protective ability during storage.

[0056] S7. Continuous ultraviolet sterilization is adopted, which utilizes the difference in sensitivity of yeast, mold and sacchariformis to ultraviolet light to inactivate yeast and mold, while maintaining the sacchariformis in an unculturable state. After sterilization, the product is immediately filled and sealed, and then refrigerated.

[0057] In step S7, the ultraviolet light used has a wavelength of 254 nm, an irradiation dose of 50-200 mJ / cm², and a treatment time of 5-15 s. After treatment, the product is immediately filled and sealed, and stored at 2-6℃.

[0058] In the above steps, a continuous ultraviolet (UV) sterilization device is used for treatment. UV radiation, especially short-wave UV radiation with a wavelength of approximately 254 nm, has the ability to damage the DNA structure of microorganisms, rendering them unable to reproduce and causing them to die. This step cleverly utilizes the differences in UV sensitivity among different microorganisms: generally, eukaryotic microorganisms such as yeasts and molds, with their larger cells, are more sensitive to UV radiation; while viable, unculturable *Sacchariformis* has extremely low metabolic activity and a special cell state, making it relatively more tolerant to short-term UV exposure. Therefore, by precisely controlling the UV irradiation dose, for example, as described in step S7, using a wavelength of 254 nm, an irradiation dose of 50-200 mJ / cm², and a treatment time of 5-15 s, this dose range can effectively destroy the DNA structure of yeasts and molds, inactivating them (depending on the species, the inactivation dose for mold spores is usually in the range of 80-200 mJ / cm²), while viable, unculturable *Sacchariformis*, due to metabolic stagnation and inhibited DNA replication, exhibits significant tolerance to this dose, thus achieving selective sterilization without activating the *Sacchariformis*. Products sterilized by ultraviolet light must be aseptically filled and sealed immediately to prevent secondary contamination. The finished product should be refrigerated at low temperatures, such as 2°C to 6°C, to maximize its quality and extend its shelf life.

[0059] After sterilization, the product needs to be filled and sealed immediately to prevent secondary contamination. After filling, the product should be refrigerated at a low temperature, ideally between 2 and 6°C. Low-temperature refrigeration further inhibits the activity of any remaining microorganisms and also helps maintain the product's flavor and color stability.

[0060] It should be noted that the selective sterilization by ultraviolet light in step S7 relies on the intrinsic difference in UV sensitivity between yeast / mold and *Saccharomyces cerevisiae* in a live, unculturable (VBNC) state. First, *Saccharomyces cerevisiae* in the VBNC state exhibits significantly enhanced tolerance to environmental stress. Their cellular metabolic activity is almost completely halted, DNA replication and protein synthesis cease, therefore UV-induced DNA damage (such as pyrimidine dimers) does not lead to lethal errors during replication; simultaneously, the time window for initiating emergency repair mechanisms is longer, allowing sublethal damage to be effectively repaired. Studies have shown that bacteria in the VBNC state exhibit several to tens of times greater tolerance to stresses such as UV radiation, high temperature, and oxidation compared to those in the active state. Second, yeast and mold, as eukaryotic microorganisms, have larger cell volumes, higher DNA content, and are in an active metabolic state, making them more sensitive to UV radiation. Within a dose range of 50-200 mJ / cm², the degree of DNA damage to yeast and mold spores is sufficient to cause them to die and be unable to reproduce, while the survival rate of *Saccharomyces cerevisiae* in the VBNC state is not significantly affected at the same dose. It is this sensitivity difference based on cellular physiological state, rather than physical shielding, that enables selective sterilization—effectively inactivating putrefactive yeasts and molds without activating or killing *Saccharomyces cerevisiae*.

[0061] In summary, the technical solution defined in this invention constructs a complete cold-sterilized fermented tomato juice processing system through the organic combination of a series of steps, including ultra-high pressure cold sterilization, two-stage sequential fermentation, medium-pressure induction of a non-culturable state, and ultraviolet selective sterilization. Compared with traditional thermal sterilization and fermentation processes, this solution completely avoids the heating process, thus better preserving the natural color, fresh flavor, and heat-sensitive nutrients of tomatoes. Compared with existing single ultra-high pressure processing technologies for fruit juice, this solution introduces a fermentation process, endowing the product with richer flavor layers and potential probiotic functions. More importantly, by using medium-pressure induction technology to induce the first-stage fermentation strains into a live, non-culturable state, it cleverly solves the long-standing problem of post-acidification in the fermented fruit and vegetable juice industry. This allows the product to maintain stable acidity and taste during its long refrigerated shelf life without the need for secondary heating to inactivate the strains, as in traditional processes. This ensures microbial safety while maximizing the preservation of the product's chilled freshness. The final step, selective ultraviolet sterilization, precisely eliminates the risk of spoilage from yeast and mold without compromising the results of all previous cold treatments, providing a final reliable guarantee for the product's shelf-life stability.

[0062] Example 1 Process cold-sterilized fermented tomato juice according to the following steps: S1. Pulping and Adjustment: Ripe tomatoes were selected and pulped at 20°C under nitrogen protection to obtain tomato pulp. White sugar was added to adjust the soluble solids to 13°Bx, and fructooligosaccharides and inulin (6:4) were added in a total amount of 5%. The pH was adjusted to 4.8 with citric acid.

[0063] S2, Ultra-high pressure sterilization: Hold the pressure at 580 MPa and 12℃ for 3.5 min.

[0064] S3, First Stage Fermentation: The temperature was raised to 29°C, and the activated *Saccharomyces cerevisiae* was inoculated. The inoculation amount resulted in a total bacterial count of approximately 5 × 10⁻⁶. 6 CFU / mL, fermented in a sealed container at 29℃ for 30 h.

[0065] S4, Medium-pressure induction treatment: The pressure was maintained at 450 MPa and 18℃ for 10 min (30 h of fermentation corresponds to a pressure maintenance time of 10 min).

[0066] S5, Second Stage Fermentation: The activated *Lactobacillus plantarum* was inoculated, with a ratio of *Saccharomyces cerevisiae* to *Lactobacillus plantarum* of 3:7, and the total bacterial count was controlled at 1×10⁻⁶. 7 CFU / mL, fermented at 37℃ to pH 3.7, lactic acid increased by ≥0.5%, and malic acid decreased by ≥30%.

[0067] S6. Solid-liquid separation, homogenization and degassing: Coarse filtration: 0.8 mm mesh size; Centrifugation: Disc centrifuge, 6℃, 6000 rpm for 8 min; Add stabilizer (modified starch: xanthan gum: CMC-Na = 2:0.5:1, addition amount 0.8%). Homogenization: First pass 12 MPa, second pass 32 MPa; Degassing: Vacuum degree 0.07 MPa, nitrogen gas purging for protection; Add 0.03% ascorbic acid.

[0068] S7. Ultraviolet sterilization and filling: Irradiation with 254 nm ultraviolet light, dose of 100 J / m², treatment time of 10 s, immediate filling and sealing, and refrigeration at 4°C.

[0069] Example 2 S1. Pulping and Adjustment: The mixture was beaten at 18°C ​​under carbon dioxide protection, and the soluble solids were adjusted to 14°Bx by adding fructose syrup. Fructooligosaccharides and inulin (6:4) were added in a total amount of 5%, and the pH was adjusted to 4.6 by malic acid.

[0070] S2, Ultra-high pressure sterilization: Hold the pressure at 560 MPa and 10℃ for 4 min.

[0071] S3, First Stage Fermentation: Inoculated with *Saccharomyces cerevisiae* at 28℃, total bacterial count approximately 6 × 10⁻⁶. 6 CFU / mL, fermentation for 36 h.

[0072] S4, Medium-pressure induction treatment: The pressure was maintained at 480 MPa and 15℃ for 9 minutes (corresponding to 36 h of fermentation).

[0073] S5, Second Stage Fermentation: Inoculated with *Lactobacillus plantarum*, *Sacchariformis*: *Lactobacillus plantarum* = 2:8, total bacterial count 8 × 10⁻⁶ 6 CFU / mL, fermented at 37℃ to pH 3.8, lactic acid increased by ≥0.5%, and malic acid decreased by ≥30%.

[0074] S6. Solid-liquid separation, homogenization and degassing: Coarse filtration: 0.6 mm mesh size; Centrifugation: Centrifuge at 4℃ and 7000 rpm for 6 min; Stabilizer addition amount: 0.6%; Homogenization: 10 MPa for the first pass, 30 MPa for the second pass; Nitrogen purging followed by degassing; Add 0.02% tea polyphenols.

[0075] S7. Ultraviolet sterilization and filling: 150 J / m², processing time 8 s, refrigerated at 2℃.

[0076] Example 3 S1. Pulping and Adjustment: The mixture was beaten at 22°C under nitrogen protection. Honey was added to adjust the soluble solids to 12°Bx. Fructooligosaccharides and inulin (6:4) were added in a total amount of 5%. The pH was adjusted to 5.0 with citric acid.

[0077] S2, Ultra-high pressure sterilization: Hold the pressure at 600 MPa and 14℃ for 3 min.

[0078] S3, First Stage Fermentation: Inoculated with *Saccharomyces cerevisiae* at 30℃, the total bacterial count was approximately 4 × 10⁻⁶. 6 CFU / mL, fermentation for 24 h.

[0079] S4, Medium-pressure induction treatment: The pressure was maintained at 400 MPa and 20℃ for 11 min (corresponding to 24 h of fermentation).

[0080] S5, Second Stage Fermentation: Inoculated with *Lactobacillus plantarum*, *Sacchariformis*: *Lactobacillus plantarum* ratio 4:6, total bacterial count 1×10⁻⁶ 7 CFU / mL, fermented at 37℃ to pH 3.6, lactic acid increased by ≥0.5%, and malic acid decreased by ≥30%.

[0081] S6. Solid-liquid separation, homogenization and degassing: Coarse filtration: 1.0 mm mesh size; Centrifugation: Centrifuge at 10℃ and 5000 rpm for 10 min; Stabilizer addition amount: 1.0%; Homogenization: First pass 15 MPa, second pass 35 MPa; Degassing vacuum degree: 0.08 MPa; Add 0.05% ascorbic acid + tea polyphenols (1:1).

[0082] S7. Ultraviolet sterilization and filling: 50 J / m², processing time 15 s, refrigerated at 6℃.

[0083] Comparative Example Traditional heat sterilization process was used, without medium-pressure induction and ultraviolet selective sterilization: S1. Pulping and Adjustment: Same as in Example 1.

[0084] S2. Heat sterilization: Maintain at 95℃ for 5 minutes.

[0085] S3, Fermentation: Simultaneously inoculate with *Saccharomyces cerevisiae* and *Lactobacillus plantarum* (ratio 3:7), and ferment at 37℃ until pH 3.7.

[0086] S4. Solid-liquid separation, homogenization, and degassing: Same as in Example 1.

[0087] S5. Secondary heat sterilization: Maintain at 85℃ for 10 minutes to inactivate the bacterial strain.

[0088] S6. Filling: After hot filling, cool and refrigerate at 4℃.

[0089] Evaluation indicators: I. Sensory quality (early storage period) Flavor Description: Example 1: Fresh tomatoes have a rich aroma, a smooth and rounded taste, and a naturally refreshing acidity; Example 2: The tomato flavor is pure, with moderate acidity that is refreshing, and a clean aftertaste; Example 3: The tomato aroma has a slight honey fragrance, a mellow taste, and a mild acidity; It has a distinct steamed / boiled flavor (like cooked soup), a sour and pungent taste, and a bland aroma.

[0090] Color: Example 1: Bright red, translucent and glossy; Example 2: Bright red, translucent; bright red with a slight orange tint; Comparative example: Dark red to brownish-red, poor gloss.

[0091] II. Comparison of pH stability during storage (pH changes during storage) III. Nutrient Retention Rate Vitamin C retention rates: Example 1 93%; Example 2 91%; Example 3 92%; Comparative Example 15%.

[0092] Lycopene retention rates: Example 1 95%; Example 2 94%; Example 3 96%; Comparative Example 78%.

[0093] Total phenol retention: Example 1 90%; Example 2 89%; Example 3 91%; Comparative Example 45%.

[0094] IV. Microbiological characteristics and stability (after 12 weeks of storage) The state of *Bacillus thuringiensis*: In Example 1, the bacteria remained in a viable, non-culturable state (VBNC), and no colonies were observed on agar plates, but cell membranes remained intact after staining for both live and dead cells; Examples 2 and 3 yielded the same results as Example 1; the comparative example was completely inactivated (by secondary heat sterilization).

[0095] Yeast / mold detection: None were detected in Examples 1-3 and the comparative examples.

[0096] Precipitation / stratification: No visible precipitation was observed in Examples 1-3, and the system was homogeneous and stable; the comparative example showed obvious stratification, with flocculent precipitate at the bottom.

[0097] Browning index: 0.12 for Example 1; 0.11 for Example 2; 0.13 for Example 3; and 0.35 for the comparative example.

[0098] V. Shelf life prediction (refrigerated at 4℃) Flavor acceptance period: Example 1 ≥ 16 weeks; Example 2 ≥ 16 weeks; Example 3 ≥ 16 weeks; Comparative Example ≤ 6 weeks Quality retention period: Example 1 ≥ 20 weeks; Example 2 ≥ 20 weeks; Example 3 ≥ 20 weeks; Comparative Example ≤ 8 weeks Results data analysis: 1. Flavor advantages (Example vs. Comparative example) Examples 1-3: Because the process does not involve high temperatures, the volatile flavor compounds in the tomatoes (such as hexenal, hexanol, and other aromatic compounds) are fully preserved, thus exhibiting the characteristic aroma of fresh tomatoes. The two-stage fermentation converts malic acid into lactic acid, resulting in a smoother, more rounded acidity without any harshness.

[0099] Comparative example: After two high-temperature treatments (95℃ for 5 min + 85℃ for 10 min), vitamin C was almost completely degraded, with a retention rate of only 15%; lycopene retention rate was 78%, but significant isomerization had occurred; total phenols were lost by more than half, with a retention rate of only 45%.

[0100] 2. Post-acidification inhibition effect (core technology verification) Examples 1-3: Through medium-pressure induction treatment (400-500 MPa), *Bacillus oryzae* successfully entered the viable non-culturable (VBNC) state. During a 12-week refrigeration period, *Bacillus oryzae* metabolism ceased, acid production stopped, and the pH value remained almost unchanged (fluctuation ≤0.03), completely solving the common problem of "becoming more acidic the longer fermented fruit and vegetable juices are stored."

[0101] Comparative example: Although secondary heat sterilization inactivates all microbial strains and avoids biological post-acidification, the high-temperature treatment disrupts the stable system of pectin and protein, leading to non-biological rancidity (pH decrease of 0.45) during storage, manifested as increased acidity and flavor imbalance. This indicates that simply relying on sterilization cannot solve the quality deterioration problem of heat-sensitive products, while the present invention effectively maintains product stability through continuous cold treatment.

[0102] 3. Nutrient retention (a significant advantage of cold sterilization) Example: Both ultra-high pressure and ultraviolet light are cold sterilization technologies, which have minimal damage to heat-sensitive nutrients (vitamin C, lycopene, polyphenols), with a retention rate generally above 90%.

[0103] Comparative example: Vitamin C is easily oxidized and degraded at high temperatures, with a retention rate of only 52%. Although lycopene is relatively heat-resistant, prolonged heating still leads to isomerization and degradation. 4. Shelf life stability Example: Thanks to the quadruple protection of medium pressure induction (inhibiting post-acidification), stabilizer system (preventing stratification), antioxidants (preventing browning) and ultraviolet sterilization (killing spoilage bacteria), the product maintains good flavor and condition for 16 weeks under refrigeration at 4°C.

[0104] Comparative example: Due to heat damage and lack of a stable system, the product showed obvious rancidity, separation and browning after 6-8 weeks, and the shelf life was significantly shortened.

[0105] The number of devices and processing scale described herein are for the purpose of simplifying the description of the invention. Applications, modifications, and variations of the invention will be readily apparent to those skilled in the art.

[0106] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details.

Claims

1. A method for processing cold-sterilized fermented tomato juice, characterized in that, Includes the following steps: S1. Tomato raw materials are pulped to obtain tomato pulp, and carbon source and prebiotics are added to the tomato pulp to adjust the composition; S2. Ultra-high pressure sterilization: The adjusted tomato pulp is held at a pressure of 550-600 MPa and a temperature of 10-15℃ for 3-4 minutes. S3, First stage fermentation: Heat the sterilized tomato pulp to 28-30℃, inoculate with activated saccharin, and ferment at a constant temperature of 28-30℃ in a sealed environment for 24-36 hours. S4. Medium-pressure induction treatment: The tomato pulp after the first stage of fermentation is subjected to medium-pressure treatment. The pressure is maintained at 400-500 MPa and 15-20℃ for 8-12 minutes to induce the *Sacchariformis* to enter a live, non-culturable state. S5. Second stage fermentation: Inoculate with activated Lactobacillus plantarum and ferment at a constant temperature of 37±1℃ until the pH drops to 3.6-3.9, then terminate the fermentation. S6. After the fermentation is complete, the tomato pulp is subjected to solid-liquid separation, homogenization and deaeration; S7. Continuous ultraviolet sterilization is adopted, which utilizes the difference in sensitivity of yeast, mold and sacchariformis to ultraviolet light to inactivate yeast and mold, while maintaining the sacchariformis in an unculturable state. After sterilization, the product is immediately filled and sealed, and then refrigerated.

2. The method for processing cold-sterilized fermented tomato juice as described in claim 1, characterized in that, In step S1, the carbon source is one or more of white sugar, fructose syrup or honey, and the amount added is adjusted to adjust the soluble solids content of the tomato pulp to 12-15°Bx. The prebiotic is a mixture of fructooligosaccharides and inulin in a ratio of 6:4, with a total addition amount of 5% of the tomato pulp mass. In step S1, citric acid or malic acid is used to adjust the pH of the tomato pulp to 4.5-5.

0.

3. The method for processing cold-sterilized fermented tomato juice as described in claim 1, characterized in that, The inoculation amount of *Lactobacillus oryzae* in step S3 and the inoculation amount of *Lactobacillus plantarum* in step S5 are such that the total inoculation amount of the fermentation system is controlled at 1×10⁻⁶. 6 -1×10 7 Within the CFU / mL range; and the ratio of *Saccharomyces cerevisiae* to *Lactobacillus plantarum* is 2:8 to 4:6; The determination of the fermentation endpoint in step S5 is controlled by multidimensional indicators: fermentation is terminated when the pH drops to 3.6-3.9, the lactic acid content increases by ≥0.5% compared to the initial value, and the malic acid content decreases by ≥30%.

4. The cold-sterilization fermented tomato juice processing method as described in claim 3, characterized in that, The pressure holding time in step S4 is selected according to the fermentation time of the first stage: when the fermentation time of the first stage is 24-30 h, the pressure holding time is 10-12 min; when the fermentation time of the first stage is 30-36 h, the pressure holding time is 8-10 min; the medium pressure treatment causes the sacchariformis to enter a live, non-culturable state to inhibit the production of lactic acid during subsequent storage.

5. The method for processing cold-sterilized fermented tomato juice as described in claim 1, characterized in that, The solid-liquid separation in step S6 adopts a two-stage separation process: first, a filter with a screen aperture of 0.5-1.0 mm is used for coarse filtration to remove fruit pulp fibers and bacterial clumps; then, a disc centrifuge is used at 4-10℃ and a speed of 5000-8000 rpm for 5-10 min.

6. The method for processing cold-sterilized fermented tomato juice as described in claim 1, characterized in that, The homogenization in step S6 adopts a two-stage homogenization process: the first homogenization pressure is 10-15 MPa, and the second homogenization pressure is 30-35 MPa; the degassing is carried out under a vacuum of 0.06-0.08 MPa, and nitrogen is introduced for protection during the degassing process, or nitrogen is introduced into the headspace after degassing to replace the residual oxygen.

7. The method for processing cold-sterilized fermented tomato juice as described in claim 6, characterized in that, In step S6, 0.01-0.05% of a natural antioxidant is added to the degassed tomato pulp. The natural antioxidant is at least one of ascorbic acid or tea polyphenols.

8. The method for processing cold-sterilized fermented tomato juice as described in claim 1, characterized in that, In step S6, after solid-liquid separation and before homogenization, a stabilizer mixture is added to the tomato pulp. The stabilizer mixture is composed of modified starch, xanthan gum and sodium carboxymethyl cellulose in a mass ratio of 2:0.5:1, and the amount added is 0.5%-1% of the mass of the tomato pulp.

9. The method for processing cold-sterilized fermented tomato juice as described in claim 1, characterized in that, The ultraviolet light used in step S7 has a wavelength of 254 nm, an irradiation dose of 50-200 mJ / cm², and a treatment time of 5-15 s. After treatment, the product is immediately filled and sealed, and stored at 2-6℃.

10. The method for processing cold-sterilized fermented tomato juice as described in claim 1, characterized in that, The pulping process described in step S1 is carried out under the protection of nitrogen or carbon dioxide inert gas, and the pulping temperature is controlled at 15-25℃.

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