Ultrasonic-assisted enzymolysis low-salt preserved szechuan pickle crispness-keeping and tender-increasing method and low-salt preserved szechuan pickle thereof

Abstract

The invention relates to the technical field of food processing, and relates to an ultrasonic-assisted enzymolysis low-salt preserved szechuan pickle crispness-keeping and tendering method and low-salt preserved szechuan pickle thereof. The preparation method specifically comprises the following steps: desalting pickled tuber mustard, and cutting the pickled tuber mustard into slices to obtain desalted tuber mustard slices; and adding pectinase and cellulase into the buffer solution, uniformly mixing to obtain an enzymatic hydrolysate, immersing the desalted preserved szechuan pickle slices into the enzymatic hydrolysate, and then carrying out ultrasonic treatment. And after the ultrasonic treatment is finished, fishing out the treated preserved szechuan pickle, washing, seasoning, stirring, packaging and sterilizing to obtain the finished preserved szechuan pickle. The ultrasonic cavitation effect is used for promoting the enzymolysis effect, intercellular substances are accurately degraded, the tender and smooth taste of the preserved szechuan pickle is remarkably improved while the brittleness of the preserved szechuan pickle is kept, and the technical problem that the low-salt preserved szechuan pickle is too hard in texture or easy to soften is effectively solved. The method is mild in process, high in efficiency, free of chemical additives and suitable for industrial production.

Description

Technical Field

[0001] This invention relates to the field of food processing technology, and more specifically, to a method for preserving crispness and tenderness of low-salt pickled mustard tuber through ultrasound-assisted enzymatic hydrolysis, and the low-salt pickled mustard tuber itself. Background Technology

[0002] With increasing public awareness of health, "salt reduction" has become an irreversible trend in the food industry. For pickled mustard tuber, a high-salt preserved product, the transition to low-salt production is crucial for industrial upgrading. However, salt in traditional pickled mustard tuber processing is not only a preservative but also an important texture stabilizer. When the salt content is significantly reduced, pickled mustard tuber products generally face a series of challenges related to textural degradation, mainly manifested in two extremes: first, excessive dehydration or the addition of hardening agents such as calcium ions to maintain crispness results in a product that is "too hard and crisp, not tender and smooth," with a dry and hard texture; second, during the shelf life, the product's endogenous enzymes or microbial activity cause the tissue structure to soften and collapse, losing its proper crisp texture.

[0003] Currently, technical methods for maintaining the crispness of pickled mustard tubers mainly focus on optimizing the dehydration process, adding calcium salts, and using color-protecting agents. Some patents have also explored the use of proteases or cellulases to remove tough fibers. Patent CN 202210783962.3 discloses a method for preparing pickled mustard tubers, the steps of which include raw material pretreatment, washing, screening, desalting and crispness preservation, soaking and crispness preservation, dehydration, seasoning, filling, and sterilization. The desalting and crispness preservation process involves adding water and calcium chloride to the screened raw materials for desalting; the soaking and crispness preservation process involves mixing brine, pectin methyl esterase, and calcium chloride, and then adding citric acid to adjust the pH to obtain a soaking solution. This invention soaks the desalted and crispness-preserving raw materials in the soaking solution. Through the synergistic effect of the two crispness preservation steps, the pectin and fiber structure of the pickled mustard tubers is improved, thus enhancing the product's taste. Patent CN202311806861.4 discloses an enzymatic method for removing the tough outer skin and fibers of pickled mustard tubers, solving the problems of low efficiency, significant raw material waste, and high costs associated with manual removal of these fibers in existing technologies. This patent's enzymatic method not only ensures the safety and hygiene of the processed product but also allows for the reuse of the enzymatic hydrolysate, saving water resources. It maintains the shape and nutritional value of the pickled mustard tubers, improves the product's appearance, facilitates subsequent processing, and increases raw material utilization. However, these technologies primarily target specific parts or single objectives, failing to systematically address the overall textural balance of low-salt pickled mustard tubers. While the synergistic effect of pectin methyl esterase and calcium chloride can maintain the crispness of the pickled mustard tubers, the increased calcium chloride content during the crispness-maintaining process reduces the tenderness at room temperature, and the presence of calcium chloride imparts a slight bitterness, affecting the overall flavor. How to maintain the core "crispness" while imparting a tender and smooth texture without compromising the flavor has become a bottleneck that urgently needs to be overcome in methods for preserving crispness and enhancing tenderness. Summary of the Invention

[0004] To overcome the poor texture defects of low-salt pickled mustard tuber products described in the prior art, this invention provides a method for preserving crispness and tenderness of low-salt pickled mustard tuber through ultrasound-assisted enzymatic hydrolysis.

[0005] Another objective of this invention is to provide a low-salt pickled mustard tuber.

[0006] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: A method for preserving crispness and enhancing tenderness of low-salt pickled mustard tubers through ultrasound-assisted enzymatic hydrolysis, specifically including the following steps: S1 desaltes the pickled mustard tuber and cuts it into slices to obtain desalted mustard tuber slices; S2 adds pectinase and cellulase to the buffer solution, mixes them evenly to obtain an enzymatic hydrolysate, and then immerses the desalted pickled mustard greens slices described in S1 in the enzymatic hydrolysate and then sonicates them.

[0007] After the S3 ultrasonic treatment is completed, the treated pickled mustard tuber is taken out, washed, then seasoned, mixed, packaged, and sterilized to obtain the finished pickled mustard tuber.

[0008] Preferably, the desalination method includes at least one of rinsing with running water or soaking and changing the water.

[0009] Preferably, in the flowing water rinsing, the water flow rate includes a flow rate of 1~2 m / s.

[0010] Preferably, in the soaking and water-changing process, the mass ratio of pickled mustard tuber to water is 1:(7~9), and the water is changed once every 0.5~1.5 hours.

[0011] Preferably, the salt content in the desalted pickled mustard tuber tissue is 2% to 5% by mass.

[0012] Preferably, the thickness of the desalted pickled mustard tuber slices is 4-6 mm.

[0013] Preferably, the pectinase has an enzyme activity of 40,000~60,000 U / g, and the determination method refers to the determination of pectinase activity in GB 1886.174-2024 "National Food Safety Standard for Food Additives and Enzyme Preparations for Food Industry".

[0014] Preferably, the pectinase has an enzyme activity of 45,000 to 55,000 U / g.

[0015] Preferably, the cellulase has an enzyme activity of 300,000 to 900,000 U / g, and the determination method is in accordance with GB / T35808-2018.

[0016] Preferably, the cellulase has an enzyme activity of 500,000 to 700,000 U / g.

[0017] Preferably, the cellulase has an enzyme activity of 550,000 to 650,000 U / g.

[0018] Preferably, the buffer solution comprises a citrate buffer solution.

[0019] Preferably, the citrate buffer has a concentration of 0.04~0.06 mol / L and a pH of 4.0~5.5.

[0020] Preferably, the pH of the enzymatic hydrolysate is 4.0 to 5.5.

[0021] Preferably, the mass concentration of pectinase in the enzymatic hydrolysate is 0.02% to 0.1%.

[0022] More preferably, the mass concentration of pectinase in the enzymatic hydrolysate is 0.05%~0.08%.

[0023] More preferably, the mass concentration of pectinase in the enzymatic hydrolysate is 0.04%~0.06%.

[0024] Preferably, the mass concentration of cellulase in the enzymatic hydrolysate is 0.01% to 0.08%.

[0025] More preferably, the mass concentration of cellulase in the enzymatic hydrolysate is 0.03% to 0.06%.

[0026] More preferably, the mass concentration of cellulase in the enzymatic hydrolysate is 0.02% to 0.04%.

[0027] Preferably, the mass-to-volume ratio of the desalted pickled mustard greens slices to the enzymatic hydrolysate is 1 kg:(3~7) L.

[0028] Preferably, the mass-to-volume ratio of the desalted pickled mustard greens slices to the enzymatic hydrolysate is 1 kg:(4~6) L.

[0029] Preferably, the ultrasonic treatment may include using an ultrasonic cleaning tank or a reaction vessel with an ultrasonic probe.

[0030] Preferably, the ultrasonic treatment temperature is 30~50℃.

[0031] Preferably, the ultrasonic processing power is 100~300W and the ultrasonic frequency is 10~40 kHz.

[0032] More preferably, the ultrasonic processing power is 150~300W and the ultrasonic frequency is 15~30 kHz.

[0033] More preferably, the ultrasonic processing power is 150~250W and the ultrasonic frequency is 17~28 kHz.

[0034] Preferably, the ultrasonic treatment time is 15-30 minutes.

[0035] More preferably, the ultrasonic treatment time is 20-25 minutes.

[0036] Preferably, the washing includes washing with water at 80-95°C for 1-3 minutes and then cooling with cooling water at 20-30°C to below 35°C; or rinsing with water, at least one of the following.

[0037] Preferably, the seasoning process is as follows: adding seasonings to the pickled mustard tubers washed in step S3.

[0038] Preferably, the seasoning includes monosodium glutamate, chili powder, and five-spice powder; the amount of seasoning added is based on the mass percentage of each seasoning component relative to the total mass of the pickled mustard tuber before seasoning, and is: 0.1%~0.5% monosodium glutamate, 1%~5% chili powder, and 0.5%~1.5% five-spice powder.

[0039] Preferably, the mixing process involves using a food-grade mixing tool to mix the ingredients from bottom to top, with a mixing frequency of 25 to 35 times / min and a duration of 7 to 9 minutes, until all the pickled mustard green slices are evenly coated with the seasoning and there is no powdery seasoning residue at the bottom of the bowl.

[0040] Preferably, the food-grade mixing tool includes a food-grade silicone spatula.

[0041] Preferably, the packaging includes vacuum packaging.

[0042] Preferably, the sterilization includes pasteurization.

[0043] Preferably, the pasteurization is performed at 85-90°C for 15-20 minutes.

[0044] A low-salt pickled mustard tuber is prepared by the ultrasonic-assisted enzymatic hydrolysis method for preserving crispness and tenderness of low-salt pickled mustard tuber as described in this invention.

[0045] In this invention, ultrasonic technology, as a non-thermal physical processing method, can exert microscopic effects on plant cell walls through its cavitation, mechanical, and thermal effects without damaging the overall structure of the food. The cavitation effect of ultrasound can generate tiny cavities and high-speed jets on the surface and inside of the pickled mustard tuber tissue, gently opening the dense structure of the cell wall and creating channels for enzyme molecules to enter the intercellular layer and the interior of the cell wall, greatly improving the efficiency and targeting of enzymatic hydrolysis.

[0046] This invention creatively combines ultrasonic technology with specific compound enzymes (such as pectinase and cellulase) to precisely regulate the overall texture of low-salt pickled mustard tuber, preserving its original flavor and nutrition to the greatest extent possible. This solves the dilemma of low-salt pickled mustard tuber being either too hard or too soft, resulting in a unique "crisp and tender" texture.

[0047] This invention develops a new method that can effectively solve the textural problems of low-salt pickled mustard tubers and achieve a harmonious balance between "preserving crispness" and "enhancing tenderness," which is of great significance for promoting the healthy development of the pickled mustard tuber industry.

[0048] Compared with the prior art, the beneficial effects of the technical solution of the present invention are: 1. Achieving Synergistic Improvement of Texture: This invention does not simply maintain crispness, but rather achieves a balance between "maintaining crispness" and "enhancing tenderness." The ultrasonic-assisted compound enzyme can precisely and gently degrade some polysaccharide substances (such as pectin and some cellulose) that cause the texture to be too hard or too soft. Without damaging the integrity of the cytoskeleton, it increases the tenderness and juiciness of the tissue, solving the dilemma of low-salt pickled mustard tubers being "either too hard or too soft," thus creating a unique "crisp and tender" texture.

[0049] 2. High processing efficiency and gentle process: The introduction of ultrasound significantly enhances the catalytic efficiency of enzymes (acoustic effect), enabling the enzyme treatment process to be completed in a shorter time, with lower enzyme concentration and gentler temperature, saving production costs and preserving the original flavor and nutrition of pickled mustard tuber to the greatest extent.

[0050] 3. Excellent Product Stability: Through precise modification of the microstructure, the water-holding capacity of the treated pickled mustard tuber is improved. During subsequent sterilization and storage, it is more resistant to textural deterioration caused by heat treatment and prolonged storage, thus extending the product's optimal shelf life. Precise modification of the microstructure effectively slows down common deterioration trends in pickled mustard tuber after storage, such as softening and structural collapse, thereby significantly improving the product's textural stability and overall quality retention during its shelf life.

[0051] 4. Clean Technology and Broad Application Prospects: This method utilizes physical means and biological enzymes, avoiding the use of chemical additives, thus aligning with the consumer trend of "clean label" products. The technology has a clear concept, requires conventional equipment, and is easily integrated and modified into existing production lines, demonstrating excellent prospects for industrial application. Attached Figure Description

[0052] Figure 1 The graph shows the hardness and crispness data of the low-salt pickled mustard tuber products of Examples 1-4 and Comparative Examples 1-3.

[0053] Figure 2 Scanning electron microscope (SEM) images of the low-salt pickled mustard tuber products of Example 1 and Comparative Examples 1-3. Detailed Implementation

[0054] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in this technical field.

[0055] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0056] The commercially available pickled mustard tubers are supplied by Chongqing Fuling District Yanyao Food Co., Ltd.

[0057] The specific preparation method of citrate buffer is as follows: Take 265 mL of 0.1 mol / L citric acid aqueous solution and 235 mL of 0.1 mol / L trisodium citrate aqueous solution, mix them evenly, and then make up to 1 L with pure water to obtain 0.05 mol / L citrate buffer with pH 4.5.

[0058] Pectinase was supplied by Shanghai Yuanye Biotechnology Co., Ltd.

[0059] Cellulase was supplied by Cool Chemical Technology Co., Ltd.

[0060] Example 1 A method for preserving crispness and tenderness of low-salt pickled mustard tubers through ultrasound-assisted enzymatic hydrolysis, comprising the following steps: (1) Take commercially available pickled mustard tuber and soak it in water at a ratio of 1:8 to remove salt. Change the water every 1 hour and change the water 6 times to obtain the desalted pickled mustard tuber. Take a sample of the desalted pickled mustard tuber and determine that the salt content is 3.8% by mass. Then cut the desalted pickled mustard tuber into 5mm thick slices to obtain desalted pickled mustard tuber slices.

[0061] (2) Prepare the enzymatic hydrolysate: Add pectinase (50000 U / g) and cellulase (600000 U / g) to 0.05 mol / L citrate buffer (pH 4.5) and dissolve them. Mix well so that the final mass concentration of pectinase in the enzymatic hydrolysate is 0.05% and the final mass concentration of cellulase is 0.03%.

[0062] (3) Take 2 kg of desalted pickled mustard greens slices and immerse them in 10 L of 40℃ enzymatic hydrolysate. Place the container containing the desalted pickled mustard greens slices and enzymatic hydrolysate in an ultrasonic cleaner, set the ultrasonic frequency to 28 kHz and the power to 250W, control the temperature at 40℃ through a water bath, and ultrasonically treat for 25 min.

[0063] (4) After the processing is completed, immediately take out the pickled mustard tuber slices processed in step (3) and immerse them in hot water at 85°C for 2 minutes, and then quickly soak them in 25°C cooling water to cool them to room temperature (25°C).

[0064] (5) Remove the pickled mustard greens processed in step (4), add monosodium glutamate, chili powder and five-spice powder for seasoning. Based on the mass percentage of each seasoning component to the total mass of the pickled mustard greens before seasoning, add 0.3% monosodium glutamate, 3% chili powder and 1% five-spice powder. Then use a food-grade silicone spatula to mix from the bottom up, at a mixing frequency of 30 times / min, for 8 minutes until all the pickled mustard greens are evenly coated with seasoning and there is no powdery seasoning residue at the bottom of the bowl. Vacuum pack the seasoned pickled mustard greens and place the packaged product in a sterilization device. Heat the product to 85°C at a uniform rate and maintain this temperature for 15 minutes for pasteurization. Then quickly cool it to room temperature (25°C) to obtain the finished pickled mustard greens.

[0065] Example 2 This embodiment is similar to Embodiment 1, except that: In step (2), the final mass concentration of pectinase in the enzymatic hydrolysate is 0.02%, and the final mass concentration of cellulase is 0.01%.

[0066] The ultrasonic frequency in step (3) is 11 kHz, the power is 100 W, and the treatment time is 15 min.

[0067] Example 3 This embodiment is similar to Embodiment 1, except that: The final mass concentration of pectinase in the enzymatic hydrolysate in step (2) is 0.08%, and the final mass concentration of cellulase is 0.06%.

[0068] The ultrasonic frequency in step (3) is 17 kHz, the power is 150 W, and the treatment time is 20 min.

[0069] Example 4 This embodiment is similar to Embodiment 1, except that: The final mass concentration of pectinase in the enzymatic hydrolysate in step (2) is 0.1%, and the final mass concentration of cellulase is 0.08%.

[0070] The ultrasonic frequency in step (3) is 33 kHz, the power is 300W, and the treatment time is 30 minutes.

[0071] Comparative Example 1 This comparative example is similar to Example 1, except that the desalted pickled mustard greens slices are not subjected to any enzyme or ultrasonic treatment. That is, in step (2), no enzyme is added to the enzymatic hydrolysate, and it is not subjected to ultrasound. It is then soaked at 40°C for 25 min.

[0072] Comparative Example 2 This comparative example is similar to Example 1, except that the desalted pickled mustard tuber slices are not treated with any enzymes, that is, no enzymes are added to the enzymatic hydrolysate in step (2).

[0073] Comparative Example 3 This comparative example is similar to Example 1, except that the desalted pickled mustard tuber slices are not subjected to ultrasonic treatment.

[0074] Analysis and testing: Texture analysis of the low-salt pickled mustard tuber products obtained in Examples 1-4 and Comparative Examples 1-3 was performed using a TA. XT Plus texture analyzer. Test type: TPA mode; compression: 30%; trigger point load: 5 g; probe: P / 0.5; test rate: 1.0 mm / s; return rate: 1.0 mm / s. The salinity of the desalted pickled mustard tuber samples was determined by direct titration according to GB 5009.44-2016, "National Food Safety Standard - Determination of Chloride in Food".

[0075] Ten sensory evaluators conducted quantitative sensory descriptive analysis on the low-salt pickled mustard tuber products obtained in Examples 1-4 and Comparative Examples 1-3. Based on the reference samples and their intensity, the evaluators used a 10-point scale (0 indicating no perceptible property, 1 indicating the weakest intensity, 5 indicating moderate intensity, and 10 indicating the strongest intensity) to score the "crispness," "juiciness," and "tenderness" of the finished pickled mustard tuber samples. The reference samples corresponding to "crispness," "juiciness," and "tenderness" were cucumber (intensity 5), carrot (intensity 2), and lettuce cooked for 5 minutes (intensity 5), respectively. The average sensory evaluation score was used.

[0076] The surfaces of the pickled mustard tuber samples obtained in Examples 1 and Comparative Examples 1-3 were rinsed with pure water. Then, the samples were immersed in 0.1 M PBS buffer (pH 7.2) for 15 min. Subsequently, the samples were removed and immersed in 2.5% glutaraldehyde solution overnight. Then, the samples were washed with PBS buffer for 5 min, repeated twice. Next, the samples were immersed in a series of ethanol solutions of various concentrations (30%, 50%, 70%, 80%, 90%, 95%, 100%), each concentration repeated twice, for 20 min each time. Then, the samples were sequentially transferred to 50% and 100% tert-butanol, each concentration repeated twice, for 15 min each time, to completely dry the samples. The dried samples were sputter-coated with gold for approximately 30 s and then observed under a Phenom Pro scanning electron microscope. The magnification of the samples was 300x and 1000x. The results of the finished product's hardness and brittleness are shown in Table 1. The results of the quantitative sensory description analysis of the finished product are shown in Table 2.

[0077] Table 1. Hardness and brittleness data for the examples and comparative examples. Hardness / g Crispness / g Example 1 1404.67 7.54 Example 2 1700.52 7.46 Example 3 1320.33 7.52 Example 4 1251.46 7.50 Comparative Example 1 2721.68 7.42 Comparative Example 2 1858.68 7.18 Comparative Example 3 682.93 7.12 Table 2. Sensory Quantitative Descriptive Analysis Data of Examples and Comparative Examples crispness Juicy tenderness Example 1 5.48 4.32 5.92 Example 2 5.46 3.95 4.80 Example 3 5.47 4.25 5.70 Example 4 5.41 4.28 5.85 Comparative Example 1 5.45 3.23 3.40 Comparative Example 2 4.83 3.58 3.70 Comparative Example 3 4.57 3.73 4.42

[0078] Results Analysis Depend on Figure 1 As shown in Tables 1 and 2, the hardness of the low-salt pickled mustard tuber in Examples 1-4 was 1251.46 g to 1700.52 g, which was lower than that of the untreated Comparative Example 1 (2721.68 g) and the Comparative Example 2 (1858.68 g) which was only treated with ultrasound. This indicates that within the process parameters defined in this application, the ultrasound-assisted enzymatic hydrolysis method provided by this invention can significantly reduce the hardness of traditional low-salt pickled mustard tuber and promote the increase of tenderness.

[0079] As can be seen from the results of Examples 1-4 and Comparative Examples 1-3, the crispness of the low-salt pickled mustard tuber products of Examples 1-4 is 7.46 g-7.54 g, which is higher than that of Comparative Examples 1-3 (7.12 g-7.42 g). This indicates that within the range of process parameters defined in this application, the ultrasonic-assisted enzymatic hydrolysis method provided by this invention can reduce the hardness of the product, i.e. increase its tenderness, while maintaining its crispness, thus achieving a crispness preservation effect.

[0080] As shown in Table 2, Examples 1-4 exhibited significantly higher "tenderness" (4.80-5.92) and "juiciness" (3.95-4.32) than Comparative Examples 1-3. Their "crispness" (5.41-5.48) was similar to Comparative Example 1 (5.45) and significantly higher than Comparative Example 3 (4.57). This indicates that within the process parameters defined in this application, the ultrasonic-assisted enzymatic hydrolysis method provided by this invention significantly increases the tenderness and juiciness of the pickled mustard tuber while maintaining its crispness. The scanning electron microscopy analysis results of Examples 1 and Comparative Examples 1-3 are as follows: Figure 2 As shown. Comparative Example 1 has a compact structure and a regular, flat surface. Comparative Example 2 exhibits a similar structure to Comparative Example 1, but shows some wrinkles. Comparative Example 3 has an irregular, flat surface and obvious structural collapse and wrinkles. In contrast, the sample of Example 1 maintains a more complete structure with fewer wrinkles and a looser structure, which intuitively explains its "macroscopically brittle and microscopically tender" textural characteristics.

[0081] In summary, the ultrasound-assisted enzymatic hydrolysis method provided by this invention can synergistically and efficiently improve the texture of low-salt pickled mustard tuber, and its effect is far superior to untreated, ultrasound-treated alone, or enzyme-treated alone, demonstrating significant technical advantages.

[0082] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preserving crispness and enhancing tenderness of low-salt pickled mustard tuber through ultrasound-assisted enzymatic hydrolysis, characterized in that, Specifically, the steps include the following: S1 desaltes the pickled mustard tuber and cuts it into slices to obtain desalted mustard tuber slices; S2 Add pectinase and cellulase to the buffer solution, mix well to obtain an enzymatic hydrolysate, immerse the desalted pickled mustard greens slices described in S1 in the enzymatic hydrolysate, and then sonicate them. After the S3 ultrasonic treatment is completed, the treated pickled mustard tuber is taken out, washed, then seasoned, mixed, packaged, and sterilized to obtain the finished pickled mustard tuber.

2. The method for preserving crispness and tenderness of low-salt pickled mustard tuber through ultrasound-assisted enzymatic hydrolysis according to claim 1, characterized in that, The desalting process is carried out until the salt content in the pickled mustard tuber tissue reaches 2% to 5% by mass.

3. The method for preserving crispness and tenderness of low-salt pickled mustard tuber through ultrasound-assisted enzymatic hydrolysis according to claim 1, characterized in that, The thickness of the desalted pickled mustard tuber slices ranges from 4 to 6 mm.

4. The method for preserving crispness and tenderness of low-salt pickled mustard tuber through ultrasound-assisted enzymatic hydrolysis according to claim 1, characterized in that, The mass concentration of pectinase in the enzymatic hydrolysate is 0.02%~0.1%, and the mass concentration of cellulase in the enzymatic hydrolysate is 0.01%~0.08%.

5. The method for preserving crispness and tenderness of low-salt pickled mustard tuber through ultrasound-assisted enzymatic hydrolysis according to claim 1, characterized in that, The pectinase has an enzyme activity of 40,000 to 60,000 U / g, and the cellulase has an enzyme activity of 300,000 to 900,000 U / g.

6. The method for preserving crispness and tenderness of low-salt pickled mustard tuber through ultrasound-assisted enzymatic hydrolysis according to claim 1, characterized in that, The mass-to-volume ratio of the desalted pickled mustard tuber slices to the enzymatic hydrolysate is 1 kg:(3~7) L.

7. The method for preserving crispness and tenderness of low-salt pickled mustard tuber through ultrasound-assisted enzymatic hydrolysis according to claim 1, characterized in that, The ultrasonic treatment temperature is 30~50℃.

8. The method for preserving crispness and tenderness of low-salt pickled mustard tuber through ultrasound-assisted enzymatic hydrolysis according to claim 1, characterized in that, The ultrasonic processing power is 100~300W, and the ultrasonic frequency is 10~40 kHz.

9. The method for preserving crispness and tenderness of low-salt pickled mustard tuber through ultrasound-assisted enzymatic hydrolysis according to claim 1, characterized in that, The ultrasonic treatment time is 15-30 minutes.

10. A low-salt pickled mustard tuber, characterized in that, It is prepared by the method of preserving crispness and tenderness of low-salt pickled mustard tuber by ultrasonic-assisted enzymatic hydrolysis as described in any one of claims 1-9.

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