A method for purifying dried radish with micro-nano bubbles combined with intermittent ultrasound-assisted tea polyphenols

Abstract

This invention belongs to the field of food processing technology, specifically relating to a method for purifying dried radish with micro-nano bubbles combined with intermittent ultrasound-assisted tea polyphenols, comprising the following steps: S1, mixing chopped dried radish with water in a container at a weight ratio of 1:5 to 1:10; S2, turning on the micro-nano bubble generator and the ultrasonic generator, performing intermittent ultrasound: cleaning for 20 seconds, pausing for 25 seconds, for a total of 20 to 30 cycles; S3, turning off the ultrasonic generator and the micro-nano bubble generator, removing the dried radish and draining it; S4, immediately transferring the drained dried radish to a pre-prepared tea polyphenol aqueous solution, mixing at a weight ratio of 1:5 to 1:10; turning on the ultrasonic generator, performing intermittent ultrasound: cleaning for 20 seconds, pausing for 25 seconds, for a total of 20 to 30 cycles; S5, removing the dried radish and pickling it according to conventional pickling methods to obtain the finished pickled dried radish. This invention has the advantages of high cleanliness, low microbial residue, and excellent deodorization effect.

Description

Technical Field

[0001] This invention belongs to the field of food processing technology, specifically relating to a method for purifying dried radish with micro-nano bubbles combined with intermittent ultrasound-assisted tea polyphenols. Background Technology

[0002] Dried radish, a traditional pickled vegetable product with a long history, is loved by consumers for its unique taste and flavor, and has a broad market prospect. Dried radish is typically made from dried radishes through washing, soaking, seasoning, and pickling processes. Rich in dietary fiber and various trace elements, it can be served as a side dish and is also an important category of snack foods. However, the transformation of dried radish from raw material processing to finished product packaging faces many quality and safety challenges, such as surface dirt and sand adhesion, microbial contamination, pesticide residues, off-odors, and short shelf life, which seriously restrict its commercialization process and quality control.

[0003] In traditional processing methods, raw radishes are mostly sun-dried or artificially dehydrated, making them susceptible to contamination from dust, microorganisms, and environmental pollutants. Furthermore, the glucosinolates and their hydrolysis products (such as isothiocyanates) naturally present in radishes can impart an unpleasant spiciness and off-flavor. Subsequent cleaning often relies on simple soaking in water and manual scrubbing, which is not only inefficient but also fails to thoroughly remove dirt adhering to the deep folds of the dried radish. In addition, some processors may use bleach or excessive preservatives to extend shelf life or improve appearance; if not thoroughly cleaned, these chemicals can remain on the surface or inside the product, affecting food safety and taste. In the sterilization process, traditional methods often involve soaking in chemical preservatives, which carries the risk of residue and fails to meet consumer demands for clean labels and natural, healthy foods.

[0004] To address the aforementioned issues, replacing traditional chemical additives with green and efficient natural active substances has become a research hotspot in the industry. Tea polyphenols, as natural polyphenolic compounds extracted from tea leaves, possess broad-spectrum antibacterial, antioxidant, and excellent odor adsorption and elimination capabilities. Studies have shown that tea polyphenols can effectively disrupt bacterial cell membrane structures and inhibit microbial growth. Simultaneously, the active groups in their molecules can react with odor-causing substances (such as sulfur compounds and aldehydes) in dried radish, thereby achieving the purpose of reducing bacteria and eliminating odor. However, soaking the dried radish in a tea polyphenol solution alone suffers from insufficient permeability and uneven action due to the complex wrinkles on the surface of the dried radish.

[0005] In conclusion, the industry urgently needs a new processing method that can simultaneously address multiple objectives, including surface cleaning of dried radish, microbial elimination, odor removal, and control of chemical residues. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method for purifying dried radish with micro-nano bubbles combined with intermittent ultrasound-assisted tea polyphenols, which can efficiently remove mud and sand from the surface of dried radish, kill microorganisms, effectively eliminate the inherent pungent odor and potential chemical residues in dried radish, and achieve a mild, green and non-toxic integrated cleaning, sterilization and deodorization, thereby ensuring food safety while maintaining the color, flavor and texture of dried radish to the greatest extent.

[0007] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0008] A method for purifying dried radish with micro-nano bubbles combined with intermittent ultrasound-assisted tea polyphenols includes the following steps:

[0009] S1. Mixing: Mix the chopped dried radish with water in a container at a weight ratio of 1:5 to 1:10.

[0010] S2. Micro-nano bubble combined with ultrasonic treatment: CO2 gas from the cylinder is introduced into the micro-nano bubble generator through a pressure reducer, and the micro-nano bubble generator is turned on. The inlet and outlet pipes of the micro-nano bubble generator are submerged in the water in the container. The circulating water is mixed with the gas by a pressure pump in the micro-nano bubble generator to form a high-density micro-nano bubble system. At the same time, the ultrasonic generator is turned on, and intermittent ultrasonic cleaning is performed: 20 seconds of cleaning, 25 seconds of rest, for a total of 20 to 30 cycles.

[0011] S3. Draining: Turn off the ultrasonic generator and the micro-nano bubble generator, drain the treatment liquid through the drain outlet, and do not reuse it; take the dried radish out of the container and place it on the filter screen to drain naturally until no liquid drips;

[0012] S4. Combined ultrasonic treatment with tea polyphenols: Immediately transfer the dried radish, which is still moist after draining, into a pre-prepared tea polyphenol (food grade) aqueous solution, and mix at a material-to-liquid weight ratio of 1:5 to 1:10. At this point, the surface of the dried radish is already in a hydrophilic and activated state and the pH is similar to that of the tea polyphenol solution, so no additional soaking time is required. The temperature is still controlled below 40℃. Turn on the ultrasonic generator and perform intermittent ultrasonic treatment: clean for 20 seconds, pause for 25 seconds, and repeat for a total of 20 to 30 cycles.

[0013] S5. Pickling and processing: Take out the dried radish and pickle it according to the conventional pickling method to obtain the finished pickled dried radish.

[0014] Micro- and nanobubbles, characterized by their large specific surface area, slow rising velocity, and negative surface charge, generate localized high temperature and pressure, along with a large number of hydroxyl radicals, upon rupture. This effectively removes mud and microorganisms adhering to the surface of dried radish, while simultaneously enhancing the mass transfer efficiency of the cleaning medium. Intermittent ultrasonic-assisted cleaning technology utilizes microjets and shock waves generated by cavitation effects. Through a cyclical "ultrasound-pause-ultrasound" mode, it provides the system with a brief relaxation time while leveraging the ultrasonic cavitation effect. When both are used in combination, the micro- and nanobubbles further break down under ultrasonic cavitation, generating stronger shock waves and active oxygen components. These synergistically open the microporous channels on the surface of the dried radish, significantly enhancing the penetration and diffusion of active ingredients such as tea polyphenols into the radish tissue, thus improving the antibacterial and deodorizing effects. Furthermore, the intermittent mode effectively avoids localized overheating and excessive mechanical impact caused by continuous ultrasound, achieving a synergistic effect of efficient cleaning, deep sterilization, and odor elimination while preserving the original crisp texture and natural flavor of the dried radish.

[0015] This invention employs a two-step process: first, activation through pretreatment with micro / nanobubbles combined with ultrasound, followed by tea polyphenol treatment. Micro / nanobubbles significantly enhance the ultrasonic cavitation effect. Under the influence of an ultrasonic field, micro / nanobubbles act as cavitation nuclei, drastically lowering the ultrasonic cavitation threshold, making the cavitation effect more readily and intensely occurring. The instantaneous bursting of these bubbles generates localized high temperatures and pressures, releasing a large number of hydroxyl radicals. These reactive oxygen species can efficiently oxidize and destroy microbial cell walls, biofilms, and organic pollutants. Simultaneously, ultrasonic cavitation opens the microporous channels on the surface of the dried radish, and the continuous flushing by the micro / nanobubbles promptly removes the detached pollutants, preventing redeposition. Untreated dried radish surfaces possess a natural hydrophobic cuticle and residual biofilm, making it difficult for water-soluble tea polyphenols to effectively adhere and penetrate. The combination of micro / nanobubbles and ultrasonic treatment opens the surface microporous channels, transforming the surface from a hydrophobic state to a hydrophilic activated state, creating favorable conditions for the adsorption and penetration of tea polyphenols. If micro-nano bubbles and tea polyphenols are used simultaneously, the local high temperature and pressure generated by the rupture of micro-nano bubbles will cause the tea polyphenols to be oxidized and degraded, destroying their phenolic hydroxyl structure and significantly reducing their broad-spectrum antibacterial ability and antioxidant activity.

[0016] In the method for purifying dried radish with micro-nano bubbles combined with intermittent ultrasound-assisted tea polyphenols provided by the present invention, preferably, the concentration of the tea polyphenol aqueous solution is 0.2-0.4 wt%, and the pH is adjusted to 5.0-6.0.

[0017] In the method for purifying dried radish with micro-nano bubbles combined with intermittent ultrasound-assisted tea polyphenols provided by the present invention, the concentration of the tea polyphenol aqueous solution is preferably 0.3 wt%.

[0018] In the method for purifying dried radish with micro-nano bubbles combined with intermittent ultrasound-assisted tea polyphenols provided by the present invention, more preferably, the pH of the tea polyphenol aqueous solution is adjusted to 5.5.

[0019] In the method for purifying dried radish with micro-nano bubbles combined with intermittent ultrasound-assisted tea polyphenols provided by the present invention, citric acid is further preferably used to adjust the pH.

[0020] In the method for purifying dried radish with micro-nano bubbles combined with intermittent ultrasound-assisted tea polyphenols provided by the present invention, it is further preferred that the pressure of the CO2 gas input into the micro-nano bubble generator in step S2 is 0.65-0.7 MPa.

[0021] In the method for purifying dried radish with micro-nano bubbles combined with intermittent ultrasound-assisted tea polyphenols provided by the present invention, more preferably, the working pressure of pressurization in step S2 is 0.65-0.7 MPa.

[0022] Using the above technical solution, micro-nano bubbles combined with intermittent ultrasound-assisted tea polyphenol purification of dried radish is achieved. The ultrasonic cavitation effect enhances the penetration and efficacy of tea polyphenols, a natural active ingredient. This not only efficiently removes surface dirt and kills microorganisms, but also eliminates the inherent pungent odor and potential chemical residues in dried radish through the adsorption and reaction properties of tea polyphenols. The synergistic process of this invention reduces the total bacterial count from 5.4 lg CFU / g to 1.8 lg CFU / g, a reduction of over 66%; the coliform count is completely reduced from 106 CFU / g to undetectable levels, achieving a 100% sterilization rate and significantly improving the sterilization and purification effect; simultaneously, it effectively degrades the content of isothiocyanates, a characteristic pungent substance, from 5.9 mg / 100g to 1.4 mg / 100g, a reduction of nearly 80%, significantly improving the product flavor.

[0023] This invention enhances purification efficiency through multi-technology synergy, abandoning methods that easily damage texture, such as high-temperature blanching and strong alkali treatment. It uses no chemical disinfectants, but only a low concentration of 0.2-0.4% food-grade tea polyphenols, generating no toxic byproducts. After processing, the turbidity of the dried radish is reduced, and the sensory flavor score is improved to 9.2, significantly enhancing the overall edible and commercial quality. This invention achieves a gentle, green, and non-toxic integrated cleaning, sterilization, and deodorization process, thus ensuring food safety while maximizing the preservation of the dried radish's color, flavor, and texture, meeting consumers' demand for safe, healthy, and high-quality pickled foods. Detailed Implementation

[0024] The specific embodiments of the present invention will be further described below. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0025] Example 1

[0026] This embodiment provides a method for purifying dried radish with micro-nano bubbles combined with intermittent ultrasound-assisted tea polyphenols, including the following steps:

[0027] S1. Select a uniform quality dried radish semi-finished product, cut it into even small pieces with a knife, and mix the dried radish and water in a container at a weight ratio of 1:6.

[0028] S2. The CO2 gas (pressure 0.65-0.7 MPa) in the cylinder is introduced into the micro-nano bubble generator through the pressure reducer, and the micro-nano bubble generator is turned on. The inlet and outlet pipes of the micro-nano bubble generator are submerged below the water surface in the container. The circulating water is mixed with the gas in the micro-nano bubble generator by the pressurization pump (pressure 0.65-0.7 MPa) to form a high-density micro-nano bubble system. At the same time, the ultrasonic generator is turned on and intermittent ultrasonic cleaning is performed: 20 seconds of cleaning, 25 seconds of rest, for a total of 30 cycles.

[0029] S3. Turn off the micro-nano bubble generator and ultrasonic generator, drain the treatment liquid through the drain outlet, and do not reuse it; take the dried radish out of the container and place it on the filter screen to drain naturally for 10 seconds to remove the treatment liquid from the dried radish.

[0030] S4. Prepare a 0.3wt% tea polyphenol aqueous solution and adjust the pH to 5.5 with citric acid;

[0031] S5. Immediately transfer the dried radish, which is still moist after draining, into the prepared tea polyphenol solution at a weight ratio of 1:6. At this point, the surface of the dried radish is in a hydrophilic and activated state and the pH is similar to that of the tea polyphenol solution, so no additional soaking time is required. The temperature is controlled below 40℃. Turn on the ultrasonic generator and perform intermittent ultrasonic cleaning: 20 seconds of cleaning followed by a 25-second interval, for a total of 30 cycles.

[0032] S6. Remove the dried radish and place it on a draining net to drain until there are no obvious water droplets on the surface; pickle the dried radish according to the conventional pickling method to obtain the finished pickled dried radish.

[0033] Example 2

[0034] This embodiment provides a method for purifying dried radish with micro-nano bubbles combined with intermittent ultrasound-assisted tea polyphenols, including the following steps:

[0035] S1. Select a uniform quality dried radish semi-finished product, cut it into even small pieces with a knife, and mix the dried radish and water in a container at a weight ratio of 1:5.

[0036] S2. The CO2 gas (pressure 0.65-0.7 MPa) in the cylinder is introduced into the micro-nano bubble generator through the pressure reducer, and the micro-nano bubble generator is turned on. The inlet and outlet pipes of the micro-nano bubble generator are submerged below the water surface in the container. The circulating water is mixed with the gas in the micro-nano bubble generator by the pressurization pump (pressure 0.65-0.7 MPa) to form a high-density micro-nano bubble system. At the same time, the ultrasonic generator is turned on and intermittent ultrasonic cleaning is performed: 20 seconds of cleaning, 25 seconds of rest, for a total of 20 cycles.

[0037] S3. Turn off the micro-nano bubble generator and ultrasonic generator, drain the treatment liquid through the drain outlet, and do not reuse it; take the dried radish out of the container and place it on the filter screen to drain naturally for 10 seconds to remove the treatment liquid from the dried radish.

[0038] S4. Prepare a 0.4wt% tea polyphenol aqueous solution and adjust the pH to 5.0 with citric acid;

[0039] S5. Immediately transfer the dried radish, which is still moist after draining, into the prepared tea polyphenol solution at a weight ratio of 1:10. At this point, the surface of the dried radish is in a hydrophilic and activated state and the pH is similar to that of the tea polyphenol solution, so no additional soaking time is required. The temperature is controlled below 40℃. Turn on the ultrasonic generator and perform intermittent ultrasonic cleaning: 20 seconds of cleaning followed by a 25-second interval, for a total of 25 cycles.

[0040] S6. Remove the dried radish and place it on a draining net to drain until there are no obvious water droplets on the surface; pickle the dried radish according to the conventional pickling method to obtain the finished pickled dried radish.

[0041] Example 3

[0042] This embodiment provides a method for purifying dried radish with micro-nano bubbles combined with intermittent ultrasound-assisted tea polyphenols, including the following steps:

[0043] S1. Select a uniform quality dried radish semi-finished product, cut it into even small pieces with a knife, and mix the dried radish and water in a container at a weight ratio of 1:10.

[0044] S2. The CO2 gas (pressure 0.65-0.7 MPa) in the cylinder is introduced into the micro-nano bubble generator through the pressure reducer, and the micro-nano bubble generator is turned on. The inlet and outlet pipes of the micro-nano bubble generator are submerged below the water surface in the container. The circulating water is mixed with the gas in the micro-nano bubble generator by the pressurization pump (pressure 0.65-0.7 MPa) to form a high-density micro-nano bubble system. At the same time, the ultrasonic generator is turned on and intermittent ultrasonic cleaning is performed: 20 seconds of cleaning, 25 seconds of rest, for a total of 25 cycles.

[0045] S3. Turn off the micro-nano bubble generator and ultrasonic generator, drain the treatment liquid through the drain outlet, and do not reuse it; take the dried radish out of the container and place it on the filter screen to drain naturally for 10 seconds to remove the treatment liquid from the dried radish.

[0046] S4. Prepare a 0.2wt% tea polyphenol aqueous solution and adjust the pH to 6.0 with citric acid;

[0047] S5. Immediately transfer the dried radish, which is still moist after draining, into the prepared tea polyphenol solution at a weight ratio of 1:5. At this point, the surface of the dried radish is in a hydrophilic and activated state and the pH is similar to that of the tea polyphenol solution, so no additional soaking time is required. The temperature is controlled below 40℃. Turn on the ultrasonic generator and perform intermittent ultrasonic cleaning: 20 seconds of cleaning followed by a 25-second interval, for a total of 20 cycles.

[0048] S6. Remove the dried radish and place it on a draining net to drain until there are no obvious water droplets on the surface; pickle the dried radish according to the conventional pickling method to obtain the finished pickled dried radish.

[0049] Comparative Example 1

[0050] This comparative example provides a method for processing dried radish using the following conventional water rinsing steps:

[0051] S1. Select a uniform quality dried radish semi-finished product, cut it into even small pieces with a knife, mix them evenly and set aside.

[0052] S2. Mix the diced dried radish with water at a ratio of 1:6 (material to liquid weight) and wash.

[0053] S3. Change the cleaning water every 1 hour, for a total of 3 hours of cleaning.

[0054] Comparative Example 2

[0055] This comparative example provides a method for purifying dried radish, including the following steps:

[0056] S1. Select a uniform quality dried radish semi-finished product, cut it into even small pieces with a knife, mix the dried radish and water in a container at a weight ratio of 1:6, and wash for 22.5 minutes.

[0057] S2. Remove the washed dried radish from the container and place it on a strainer to drain naturally for 10 seconds to remove the water from the dried radish.

[0058] S3. Prepare a 0.3wt% tea polyphenol aqueous solution and adjust the pH to 5.5 with citric acid;

[0059] S4. Immediately transfer the dried radish, which is still moist after draining, into the prepared tea polyphenol solution at a weight ratio of 1:6. At this point, the surface of the dried radish is in a hydrophilic and activated state and the pH is similar to that of the tea polyphenol solution, so no additional soaking time is required. The temperature is controlled below 40℃. Turn on the ultrasonic generator and perform intermittent ultrasonic cleaning: 20 seconds of cleaning followed by a 25-second interval, for a total of 30 cycles.

[0060] S6. Remove the dried radish and place it on a draining net to drain until there are no obvious water droplets on the surface; pickle the dried radish according to the conventional pickling method to obtain the finished pickled dried radish.

[0061] Comparative Example 3

[0062] This comparative example provides a method for purifying dried radish, including the following steps:

[0063] S1. Select a uniform quality dried radish semi-finished product, cut it into even small pieces with a knife, and mix the dried radish and water in a container at a weight ratio of 1:6.

[0064] S2. The CO2 gas (pressure 0.65-0.7 MPa) in the cylinder is introduced into the micro-nano bubble generator through the pressure reducer, and the micro-nano bubble generator is turned on. The inlet and outlet pipes of the micro-nano bubble generator are submerged below the water surface in the container. The circulating water is mixed with the gas in the micro-nano bubble generator by the pressurization pump (pressure 0.65-0.7 MPa) to form a high-density micro-nano bubble system. At the same time, the ultrasonic generator is turned on and intermittent ultrasonic cleaning is performed: 20 seconds of cleaning, 25 seconds of rest, for a total of 30 cycles.

[0065] S3. Turn off the micro-nano bubble generator and ultrasonic generator, drain the treatment liquid through the drain outlet, and do not reuse it; take the dried radish out of the container and place it on the filter screen to drain naturally for 10 seconds to remove the treatment liquid from the dried radish.

[0066] S4. Prepare a 0.3wt% tea polyphenol aqueous solution and adjust the pH to 5.5 with citric acid;

[0067] S5. Immediately transfer the dried radish, which is still moist after draining, into the prepared tea polyphenol solution at a weight ratio of 1:6. At this point, the surface of the dried radish is in a hydrophilic and activated state and the pH is similar to that of the tea polyphenol solution, so no additional soaking time is required. The temperature should be controlled below 40℃. Soak for 22.5 minutes.

[0068] S6. Remove the dried radish and place it on a draining net to drain until there are no obvious water droplets on the surface; pickle the dried radish according to the conventional pickling method to obtain the finished pickled dried radish.

[0069] Comparative Example 4

[0070] This comparative example provides a method for purifying dried radish, including the following steps:

[0071] S1. Select a uniform quality dried radish semi-finished product, cut it into even small pieces with a knife, and mix the dried radish and water in a container at a weight ratio of 1:6.

[0072] S2. The CO2 gas (pressure 0.65-0.7 MPa) in the cylinder is introduced into the micro-nano bubble generator through the pressure reducer, and the micro-nano bubble generator is turned on. The inlet and outlet pipes of the micro-nano bubble generator are submerged below the water surface in the container. The circulating water is mixed with the gas in the micro-nano bubble generator by the pressurization pump (pressure 0.65-0.7 MPa) to form a high-density micro-nano bubble system. At the same time, the ultrasonic generator is turned on and intermittent ultrasonic cleaning is performed: 20 seconds of cleaning, 25 seconds of rest, for a total of 30 cycles.

[0073] S3. Turn off the micro-nano bubble generator and ultrasonic generator, drain the treatment liquid through the drain outlet, and do not reuse it; take the dried radish out of the container and place it on the filter screen to drain naturally for 10 seconds to remove the treatment liquid from the dried radish.

[0074] S4. Immediately transfer the dried radish, which is still moist after draining, into clean water and mix it with the liquid at a weight ratio of 1:6. At this time, the surface of the dried radish is in a hydrophilic and activated state and the pH is similar to that of the tea polyphenol solution, so no additional soaking time is required. The temperature is controlled below 40℃. Turn on the ultrasonic generator and perform intermittent ultrasonic cleaning: 20 seconds of cleaning, 25 seconds of rest, for a total of 30 cycles.

[0075] S6. Remove the dried radish and place it on a draining net to drain until there are no obvious water droplets on the surface; pickle the dried radish according to the conventional pickling method to obtain the finished pickled dried radish.

[0076] Comparative Example 5

[0077] This comparative example provides a method for purifying dried radish, including the following steps:

[0078] S1. Select a uniform quality dried radish semi-finished product, cut it into even small pieces with a knife, and mix the dried radish and water in a container at a weight ratio of 1:6.

[0079] S2. Turn on the ultrasonic generator and perform intermittent ultrasonic cleaning: clean for 20 seconds, then rest for 25 seconds, for a total of 30 cycles;

[0080] S3. Turn off the ultrasonic generator and drain the treatment liquid through the drain outlet. Do not reuse the liquid. Take the dried radish out of the container and place it on the filter screen to drain naturally for 10 seconds to remove the treatment liquid from the dried radish.

[0081] S4. Prepare a 0.3wt% tea polyphenol aqueous solution and adjust the pH to 5.5 with citric acid;

[0082] S5. Immediately transfer the dried radish, which is still moist after draining, into the prepared tea polyphenol solution at a weight ratio of 1:6. At this point, the surface of the dried radish is in a hydrophilic and activated state and the pH is similar to that of the tea polyphenol solution, so no additional soaking time is required. The temperature is controlled below 40℃. Turn on the ultrasonic generator and perform intermittent ultrasonic cleaning: 20 seconds of cleaning followed by a 25-second interval, for a total of 30 cycles.

[0083] S6. Remove the dried radish and place it on a draining net to drain until there are no obvious water droplets on the surface; pickle the dried radish according to the conventional pickling method to obtain the finished pickled dried radish.

[0084] Comparative Example 6

[0085] This comparative example provides a method for purifying dried radish, including the following steps:

[0086] S1. Select a uniform quality dried radish semi-finished product, cut it into even small pieces with a knife, and mix the dried radish and water in a container at a weight ratio of 1:6.

[0087] S2. The CO2 gas (pressure 0.65-0.7 MPa) in the cylinder is introduced into the micro-nano bubble generator through the pressure reducer, and the micro-nano bubble generator is turned on. The inlet and outlet pipes of the micro-nano bubble generator are submerged below the water surface in the container. The circulating water is mixed with the gas in the micro-nano bubble generator by the pressurization pump (pressure 0.65-0.7 MPa) to form a high-density micro-nano bubble system. The cleaning process lasts for 22.5 minutes.

[0088] S3. Turn off the micro-nano bubble generator, drain the treatment liquid through the drain outlet, and do not reuse it; take the dried radish out of the container and place it on the filter screen to drain naturally for 10 seconds to remove the treatment liquid from the dried radish.

[0089] S4. Prepare a 0.3wt% tea polyphenol aqueous solution and adjust the pH to 5.5 with citric acid;

[0090] S5. Immediately transfer the dried radish, which is still moist after draining, into the prepared tea polyphenol solution at a weight ratio of 1:6. At this point, the surface of the dried radish is in a hydrophilic and activated state and the pH is similar to that of the tea polyphenol solution, so no additional soaking time is required. The temperature is controlled below 40℃. Turn on the ultrasonic generator and perform intermittent ultrasonic cleaning: 20 seconds of cleaning followed by a 25-second interval, for a total of 30 cycles.

[0091] S6. Remove the dried radish and place it on a draining net to drain until there are no obvious water droplets on the surface; pickle the dried radish according to the conventional pickling method to obtain the finished pickled dried radish.

[0092] Test case

[0093] To verify the beneficial technical effects of the present invention, the turbidity, hardness, total bacterial count, coliform count and isothiocyanate content of the purified (before pickling) dried radishes in Examples 1, 2, 3, 1, 2, 3, 4, 5 and 6 were tested respectively. The results are shown in Table 1.

[0094] 1. Turbidity Measurement

[0095] The washed dried radish was added to sterile deionized water at a material-to-liquid ratio of 1:1. The washing efficiency of the dried radish was evaluated by the turbidity of the secondary washing water. The absorbance was measured at 600 nm; a higher absorbance value indicated a higher sediment content. The result was expressed as ×10.

[0096] 2. Hardness Measurement

[0097] Hardness was determined using a texture analyzer. The main parameters were as follows: probe type P2; probe speeds before, during, and after testing were 1.0, 8.0, and 5.0 mm / s, respectively; trigger value / induction was 5.0 g; and compression depth was 3 mm. Five to ten samples were taken from each portion of dried radish, and three points were taken from each sample for measurement (each point was measured five times). The average value was recorded.

[0098] 3. Total bacterial count determination

[0099] The determination was performed using the plate count method in GB 4789.2-2022 "Microbiological Examination of Food - Determination of Total Colony Count", and the result was expressed as total colony count (CFU / g).

[0100] 4. Coliform count determination

[0101] The determination was performed according to Method 1 (MPN counting method) in GB 4789.3-2025 "National Food Safety Standard - Microbiological Examination of Food - Coliform Count".

[0102] 5. Determination of isothiocyanate content

[0103] Take 50g of sample and add 250mL of distilled water. Mix in a homogenizer for 30s. Accurately measure 50mL of the liquid into an iodine flask, add an equal volume of n-hexane, shake for 3min, let stand, and remove the n-hexane layer. Store at -20℃. Identify and determine MTBITC using GC-MS. Vaporization chamber temperature: 250℃; carrier gas flow rate (He): 1.0mL / min; programmed temperature ramp: 80℃ held for 5min, then ramped to 280℃ at 20℃ / min and held for 5min. Interface temperature: 280℃; EI+ source: 70eV, 200℃; detector voltage: 350V; scan frequency: 2 scans / s; mass range: 35~500u; split ratio: 1:20; injection volume: 1μL. Quantify using erucic acid as an external standard.

[0104] Table 1. Detection results of purified dried radish in each case.

[0105]

[0106] As shown in Table 1, the turbidity, total bacterial count, coliform bacteria, and isothiocyanate content of Examples 1 to 3 were significantly lower than those of Comparative Examples 1 to 6. This demonstrates that the present invention employs a two-stage synergistic process combining micro-nano bubble activation with intermittent ultrasonic treatment, and combined with tea polyphenol purification with intermittent ultrasonic function. Relying on the synergistic effects of physical flushing by micro-nano bubbles, ultrasonic cavitation opening for enhanced penetration, and the antibacterial and deodorizing effects of tea polyphenols, the turbidity, total bacterial count, coliform bacteria, and isothiocyanate content of the dried radish are significantly reduced. Compared to traditional water rinsing, this invention offers significant purification advantages. Compared to comparative examples 1 to 6, the synergistic process of this invention can reduce the total bacterial count from 5.4 1g CFU / g to 1.8 1g CFU / g, a total reduction of over 66%; the coliform count is reduced from 106 CFU / g to undetectable levels, achieving a 100% sterilization rate and significantly improving the sterilization and purification effect; simultaneously, it can effectively degrade the content of isothiocyanates, a characteristic substance of spiciness, reducing it from 5.9 mg / 100g to 1.4 mg / 100g, a reduction of nearly 80%, significantly improving the product flavor.

[0107] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A method for purifying dried radish with micro / nano bubbles combined with intermittent ultrasound-assisted tea polyphenols, characterized in that, Includes the following steps: S1. Mixing: Mix the chopped dried radish with water in a container at a weight ratio of 1:5 to 1:

10. S2. Micro-nano bubble combined with ultrasonic treatment: CO2 gas from the cylinder is introduced into the micro-nano bubble generator through a pressure reducer, and the micro-nano bubble generator is turned on. The inlet and outlet pipes of the micro-nano bubble generator are submerged in the water in the container. The circulating water is mixed with the gas by a pressure pump in the micro-nano bubble generator to form a high-density micro-nano bubble system. At the same time, the ultrasonic generator is turned on, and intermittent ultrasonic cleaning is performed: 20 seconds of cleaning, 25 seconds of rest, for a total of 20 to 30 cycles. S3. Draining: Turn off the ultrasonic generator and the micro-nano bubble generator, drain the treatment liquid through the drain outlet, and do not reuse it; take the dried radish out of the container and place it on the filter screen to drain naturally until no liquid drips; S4. Combined ultrasonic treatment with tea polyphenols: Immediately transfer the dried radish, which is still moist after draining, into a pre-prepared tea polyphenol aqueous solution, and mix them at a material-to-liquid weight ratio of 1:5 to 1:

10. At this time, the surface of the dried radish is already in a hydrophilic and activated state and the pH is similar to that of the tea polyphenol solution, so no additional soaking time is required. The temperature is controlled below 40℃. Turn on the ultrasonic generator and perform intermittent ultrasonic treatment: clean for 20 seconds, rest for 25 seconds, and perform a total of 20 to 30 cycles. S5. Pickling and processing: Take out the dried radish and pickle it according to the conventional pickling method to obtain the finished pickled dried radish.

2. The method for purifying dried radish with micro-nano bubbles combined with intermittent ultrasound-assisted tea polyphenols according to claim 1, characterized in that, The concentration of the tea polyphenol aqueous solution is 0.2-0.4 wt%, and the pH is adjusted to 5.0-6.

0.

3. The method for purifying dried radish with micro-nano bubbles combined with intermittent ultrasound-assisted tea polyphenols according to claim 2, characterized in that, The concentration of the tea polyphenol aqueous solution is 0.3 wt%.

4. The method for purifying dried radish with micro-nano bubbles combined with intermittent ultrasound-assisted tea polyphenols according to claim 3, characterized in that, The pH of the tea polyphenol aqueous solution was adjusted to 5.

5.

5. The method for purifying dried radish with micro-nano bubbles combined with intermittent ultrasound-assisted tea polyphenols according to any one of claims 2 to 4, characterized in that, Use citric acid to adjust the pH.

6. The method for purifying dried radish with micro-nano bubbles combined with intermittent ultrasound-assisted tea polyphenols according to claim 5, characterized in that, The pressure of the CO2 gas introduced into the micro / nano bubble generator in step S2 is 0.65–0.7 MPa.

7. The method for purifying dried radish with micro-nano bubbles combined with intermittent ultrasound-assisted tea polyphenols according to claim 6, characterized in that, The working pressure for pressurization in step S2 is 0.65 to 0.7 MPa.

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