Making method for improving quality of pickled kohlrabi

Abstract

The invention discloses a making method for improving the quality of pickled brassica napobrassica. The making method comprises the following steps: S1, pretreating fresh brassica napobrassica, cleaning, and drying for later use; s2, performing three-stage pickling on the brassica napobrassica, namely a pre-pickling stage, a main pickling stage and a post-pickling stage; S3, slicing the pickled brassica napobrassica, spraying a mixed solution containing natamycin and nisin on the surface, performing soaking, draining water on the surface, and performing cooling; and S4, performing modified atmosphere packaging on the kohlrabi product, and performing cold storage on the packaged finished product. According to the invention, the brassica napobrassica is pickled in a three-stage pickling mode, and rapid dehydration is realized by using a low-salt vegetable ratio; in a medium-salt environment, lactobacillus plantarum and saccharomycetes are utilized to replace a traditional naturally-fermented infectious microbe community, it is ensured that only beneficial flavor substances are generated in a short time, meanwhile, bacteriocin generated by lactic acid bacteria can further inhibit infectious microbe, and the problem that pollution is prone to occurring in short-time pickling is solved.

Description

Technical Field

[0001] This invention relates to the field of pickling technology for pickled mustard greens, and in particular to a method for improving the quality of pickled mustard greens. Background Technology

[0002] Chinese cabbage, a common root vegetable, is prized for its high yield, adaptability, and rich nutrition. Pickled Chinese cabbage is an important category of traditional fermented foods, and its salty, savory, and refreshing taste, along with its ability to stimulate the appetite and cut through greasiness, has made it a common ingredient on family tables and in the catering industry.

[0003] However, most pickled mustard greens currently produced using traditional pickling methods rely on natural fermentation. This process is highly susceptible to environmental factors such as temperature, humidity, and microbial communities, easily leading to problems like excessive saltiness, sourness, or blandness, overly hard or mushy texture, and dull color, resulting in poor product consistency. Furthermore, the high moisture content and uneven salt distribution of pickled mustard greens make them prone to contamination by harmful microorganisms during storage and transportation, leading to mold and bloating. Moreover, the traditional pickling process for mustard greens is lengthy, typically requiring 30-60 days, which is insufficient for the efficiency demands of large-scale production. Additionally, the excessive addition of nitrites, preservatives, and other chemical reagents to extend shelf life poses food safety risks. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a method for improving the quality of pickled mustard greens, which can enhance the flavor, texture, and color of the pickled mustard greens while extending their shelf life.

[0005] Therefore, the technical solution of the present invention is: a method for improving the quality of pickled mustard greens, comprising the following steps: S1. Pre-treat fresh Chinese cabbage by washing and drying it for later use. S2. The pickling of Chinese cabbage is carried out in three stages: pre-pickled stage, main pickling stage, and post-pickled stage. S2.1 Pre-pickled stage: Mix the cabbage and salt at a mass ratio of (9-11):1, add 3%-7% pure water of the total mass of the mixture, and pickle at 18-25℃ for 20-30 hours; S2.2 Main pickling stage: Add salt to make the salt concentration in the mixture reach 7%-11%, add compound biological quality improver accounting for 0.3%-0.7% of the weight of the cabbage, and introduce a mixture of oxygen and nitrogen with an oxygen content of 1%-5% using an intermittent ventilation mode, and seal and pickle for 60-84 hours. S2.3, Post-pickled stage: Add 1%-3% white sugar, 0.2%-0.4% ginger powder, 0.1%-0.3% garlic powder and 0.05%-0.15% Sichuan pepper powder according to the weight of the pickled cabbage. After stirring evenly, adjust the salt concentration to 5%-8% and seal for pickling for 36-60 hours. S3. Cut the pickled cabbage into slices 0.3-1.2cm thick or chunks 1-2cm on each side. Spray the surface with a mixed solution containing 0.1%-0.3% natamycin and 0.02%-0.05% nisin, soak for 2-3 minutes, drain the surface water and cool. S4. Modified atmosphere packaging is used for Chinese cabbage products, and the packaged finished products are stored in cold storage.

[0006] Based on the above scheme and as a preferred embodiment of the above scheme: the composite biological quality improver in step S2.2 is composed of Lactobacillus plantarum, yeast and konjac glucomannan. The konjac glucomannan is dissolved in purified water in advance. The mass ratio of konjac glucomannan to purified water is 1:20. After stirring until a uniform colloid is formed, it is mixed with Lactobacillus plantarum and yeast that have been activated by sterile water to obtain the composite biological quality improver.

[0007] Based on the above scheme and as a preferred embodiment: In step S2.2, *Lactobacillus plantarum* and yeast are activated with sterile water at 25-35℃, with a mass ratio of bacterial agent to sterile water of 1:(5-10). During activation, the mixture is stirred at a speed of 20-40 r / min for 8-12 min, and the viable count of the activated bacterial solution must be ≥1×10⁻⁶. 9 CFU / mL, then mixed with konjac glucomannan colloid.

[0008] Based on the above scheme and as a preferred embodiment, the mass ratio of *Lactobacillus plantarum*, yeast, and konjac glucomannan is (1.5-2.5):(0.8-1.2):(0.8-1.2), wherein the viable count of *Lactobacillus plantarum* is (0.8-1.2) × 10⁻⁶. 8 CFU / g, the viable yeast count was (3-7)×10⁻⁶. 7 CFU / g.

[0009] Based on the above scheme and as a preferred option: In step S1, select fresh, disease-free, and pest-free Chinese cabbage with a diameter of 6-15cm, remove the fibrous roots, old leaves and surface impurities, soak it in a vitamin C solution with a mass fraction of 0.2%-0.4% for 10-20 minutes, and dry it in a hot air drying oven at 30-45℃ until there is no free moisture on the surface.

[0010] Based on the above scheme and as a preferred embodiment of the above scheme: In step S2.1, it is necessary to stir regularly during the pre-marinating stage. The stirring frequency is once every 4-8 hours, and each stirring lasts for 5-10 minutes. The stirring speed is 30-50 r / min.

[0011] Based on the above scheme and as a preferred embodiment of the above scheme: in step S2.1, the salt is food-grade refined salt with a particle size of 0.15-0.3mm, and the salt is dried at 105-110℃ for 2-3 hours in advance to remove free moisture.

[0012] Based on the above scheme and as a preferred embodiment of the above scheme: in step S2.2, the intermittent ventilation mode is to alternate between ventilation for 10 minutes and cessation for 20 minutes, with a ventilation rate of 0.3-0.8 L / (kg·h).

[0013] Based on the above scheme and as a preferred option: In step S2.3, the current salt concentration of the system is detected by a salinity meter. If the concentration is >8%, pure water at 30-40℃ is added for dilution, and the pure water needs to be added in 2-3 portions. After each addition, the mixture is stirred for 5-8 minutes and then the concentration is detected again. If the concentration is <5%, salt is added, and the mixture is stirred for 8-10 minutes after adding the salt to ensure uniform dissolution. The final salt concentration deviation is controlled within ±0.2%.

[0014] Based on the above scheme and as a preferred option: In step S4, PET / PE composite film bags are used to package the turnips in 150-250g portions per bag. The gas inside the bag is then replaced with a mixed gas using a modified atmosphere packaging machine. The mixed gas consists of 25%-35% carbon dioxide, 3%-8% oxygen, and 57%-72% nitrogen. The bag is then heat-sealed for 1-2 seconds at 130-160℃ and 0.2-0.3MPa. The finished product is then refrigerated at 2-10℃.

[0015] This invention employs a three-stage pickling process: Pre-pickled stage: Rapid dehydration is achieved through a low salt-to-vegetable ratio. The osmotic pressure of the low-salt environment quickly (within approximately 24 hours) draws out 20%-25% of the surface water from the cabbage. This avoids osmotic shock caused by high salt, preventing subsequent soggy texture, and inhibits the growth of harmful bacteria such as E. coli and Bacillus, while retaining the internal moisture and nutrients of the cabbage. The pre-pickled stage eliminates the need for fermentation, requiring only dehydration and antibacterial action, and takes only one-third the time of the initial dehydration stage in traditional processes.

[0016] Main pickling stage: After pre-pickled, the pickled mustard greens release a large amount of water, naturally lowering the salt concentration. At this point, salt needs to be added to bring the concentration to 7%-11%, which is the optimal fermentation range for lactic acid bacteria. Combined with a micro-aerobic environment of 1%-5% oxygen, the *Lactobacillus plantarum* in the compound bacterial agent can be quickly activated. Lactic acid bacteria produce acid in a moderately salty environment, while yeast simultaneously produces ester aroma compounds. The core flavor compounds accumulate within 60-84 hours, taking only 1 / 4 to 1 / 5 of the time required for traditional natural fermentation.

[0017] Post-pickle stage: After the main pickling, the environment is lowered to a low-salt level, which not only meets modern health needs but also slows down the rate of acid production by lactic acid bacteria, providing a gentle environment for the penetration of seasonings such as white sugar and ginger powder. Within 36-60 hours, the seasonings diffuse evenly into the cabbage through a concentration gradient, achieving a balance of salty and sweet flavors and a fusion of spice flavors, without the need to wait for the salt and seasonings to slowly reach equilibrium as in traditional processes.

[0018] This invention utilizes *Lactobacillus plantarum* and yeast to replace the mixed microbial communities of traditional natural fermentation, ensuring that only beneficial flavor substances are produced in a short time. Simultaneously, the bacteriocins produced by lactic acid bacteria further inhibit other microorganisms, solving the problem of easy contamination during short-term pickling. Furthermore, konjac glucomannan, after being dissolved in purified water into a colloid, can form a three-dimensional network structure with the cell wall fibers of the pickled mustard greens, firmly locking in moisture during the main pickling stage while enhancing cell toughness, maintaining the product's hardness at 2.5-2.8 kgf, thus achieving a crisp and tender texture even during short-term pickling.

[0019] Compared with the prior art, the beneficial effects of the present invention are: A three-stage pickling process is adopted to pickle Chinese cabbage, using a low salt-to-vegetable ratio to achieve rapid dehydration. In a medium-salt environment, Lactobacillus plantarum and yeast are used to replace the mixed microbial community of traditional natural fermentation, ensuring that only beneficial flavor substances are produced in a short time. At the same time, the bacteriocins produced by lactic acid bacteria can further inhibit mixed microorganisms, solving the problem of easy contamination during short-term pickling.

[0020] By utilizing konjac glucomannan dissolved into a colloid, a three-dimensional network structure is formed with the cell wall fibers of Chinese cabbage, which locks in moisture during the main pickling stage, while enhancing cell toughness and maintaining product firmness, thus achieving a crisp and tender texture even after short-term pickling.

[0021] Intermittent aeration during the main pickling stage provides an ideal environment for the lactic acid bacteria to be activated by micro-oxygen in the early stage and to produce acid through anaerobic processes in the later stage. It also avoids moisture evaporation caused by continuous aeration, ensuring stable microbial metabolism during the main pickling stage and preventing insufficient fermentation due to environmental fluctuations.

[0022] Using vitamin C during the pretreatment of pickled mustard greens and antibacterial agents during post-treatment provides dual protection against browning and spoilage. The medium-salt environment during the main pickling stage inhibits the enzyme activity of bacteria that produce nitrites, while lactic acid bacteria accelerate nitrite degradation, thus solving the problem of excessive nitrite levels in short-term pickling.

[0023] Spraying the product surface with a mixed solution of natamycin and nisin, combined with modified atmosphere packaging, can effectively extend the product's shelf life and facilitate subsequent sales and storage. Attached Figure Description

[0024] Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation

[0025] Example 1 The method for improving the quality of pickled mustard greens described in this embodiment includes the following steps: S1. Raw material pretreatment: Select 10kg of fresh, disease-free, and pest-free Chinese cabbage with a diameter of 8-12cm. Remove the fibrous roots, old leaves, and surface impurities. Soak in 300mL of 0.3% vitamin C solution for 15min. Transfer to a 35℃ hot air drying oven with a wind speed of 2m / s. Turn the cabbage over once every 12min. Dry until there is no free moisture on the surface, the surface moisture content is 10%, and the weight loss is about 0.8kg.

[0026] S2. The pickling of Chinese cabbage is carried out in three stages: pre-pickled stage, main pickling stage, and post-pickled stage. S2.1 Pre-pickled stage: Mix Chinese cabbage and salt at a mass ratio of 10:1, i.e., the mass of salt is 1kg. Use food-grade refined salt with a particle size of 0.2mm. Dry the salt at 108℃ for 2.5h in advance to remove surface moisture. Add 5% of the total mass of the mixture with purified water (i.e., 0.55kg). Place the mixture in a food-grade stainless steel pickling tank with an arc-shaped stirring blade. Pickle at 20℃ for 24h. Stir 6h / time, 8min each time, at a speed of 40r / min.

[0027] S2.2 Main Pickling Stage: During the pre-pickled stage, the cabbage releases a significant amount of moisture. A salinity meter indicates a salt concentration of 7.5%. 0.25 kg of salt is added to bring the salt concentration to 9%. Then, 50 g of a compound biological quality improver (0.5% of the cabbage's weight) is added. The preparation process of the compound biological quality improver is as follows: Dissolve 12.5g of konjac glucomannan in 250mL of 55℃ purified water to form a colloid, and then mix it with 25g of *Lactobacillus plantarum* (1×10⁻⁶ viable bacteria) activated in sterile water at 30℃. 8 CFU / g, bacterial agent: sterile water = 1:8, i.e., 25g bacterial agent added to 200mL sterile water, stirred at 30r / min for 10min), yeast (12.5g, viable count 5×10⁻⁶). 7 The mixture (CFU / g) was activated, and the viable bacterial count in the bacterial solution was 1.5 × 10⁻⁶. 9 CFU / mL.

[0028] Intermittent ventilation was carried out using a small air pump, that is, ventilation was alternated for 10 minutes and stopped for 20 minutes, with a ventilation rate of 0.5L / (kg・h), that is, 5L of air was introduced per hour. A mixture of oxygen and nitrogen gas with an oxygen content of 3% was introduced, and the mixture was sealed and pickled at 16°C for 72 hours.

[0029] S2.3, Post-pickled stage: Add 2% of the weight of the pickled mustard greens (i.e., 0.2kg) of white sugar, 0.3% of ginger powder (i.e., 30g), 0.2% of garlic powder (i.e., 20g), and 0.1% of Sichuan pepper powder (i.e., 10g). After stirring evenly, the salt concentration is tested to be 9%. Add 200mL of purified water at 30-40℃ in 3 batches, stirring for 6 minutes each time, and then test. The final salt concentration is adjusted to 6.5%. Seal and pickle at 15℃ for 48 hours.

[0030] S3. Cut the pickled cabbage into slices 0.8cm thick. Spray the surface with a mixed solution containing 0.2% natamycin and 0.03% nisin. Prepare 100mL of the mixed solution in advance for spraying. Spray 8mL / 100g, that is, 800mL is needed for 10kg of raw materials. Spray in 8 times. Then soak in the new mixed solution for 2.5min, drain for 12min, and then gradually cool down, that is, pre-cool at 8℃ for 40min, and then refrigerate at 5℃ for 80min. Use a probe thermometer to check the center temperature. It should be ≤8℃.

[0031] S4. Modified atmosphere packaging is used for the pickled mustard greens products, and the packaged finished products are stored under cold storage. PET / PE composite film bags with a thickness of 0.08mm and a single bag capacity of 200g are used. After the pickled mustard greens are packaged into 200g bags, the gas inside the bag is replaced with a mixed gas using a modified atmosphere packaging machine. The mixed gas is 30% carbon dioxide, 5% oxygen, and 65% nitrogen. The mixture is heat-sealed for 1.5s at 150℃ and 0.25MPa. The finished products are then stored under cold storage at 4℃.

[0032] Comparative Example 1: The specific steps for pickling Chinese cabbage using traditional natural fermentation are as follows: a1. Select 10kg of Chinese cabbage of the same size and quality as in Example 1. Wash the 10kg of Chinese cabbage and place it outdoors to dry until the surface is slightly dry. a2. Pack 10kg of Chinese cabbage into a 20L ceramic jar, adding 1.5kg of salt in batches during the process. Let it ferment naturally at room temperature (fluctuating between 10-25℃) for 45 days without stirring. a3. After the cabbage has fermented, add 0.2 kg of white sugar, stir, cut the cabbage into slices 0.8 cm thick, then pack it in a regular PE plastic bag and store the finished product in a refrigerated environment at 4℃.

[0033] Under the same storage conditions, the pickled products of Example 1 and Comparative Example 1 remained crisp and tender after being refrigerated at 4°C for 6 months, without any obvious softening or rotting, and maintained a bright light yellow color without browning. In contrast, the product prepared in Comparative Example 1 showed significant browning and softening after refrigeration for 3 months, resulting in a poor taste. Therefore, it is evident that the pickled mustard greens of Example 1 have a significantly extended shelf life and significantly reduced storage and transportation losses.

[0034] The above description is merely a preferred embodiment of this utility model. The protection scope of this utility model is not limited to the above embodiments. All technical solutions falling within the scope of this utility model's concept are protected. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of this utility model should also be considered within the protection scope of this utility model.

Claims

1. A method for improving the quality of pickled mustard greens, characterized in that: Includes the following steps: S1. Pre-treat fresh Chinese cabbage by washing and drying it for later use. S2. The pickling of Chinese cabbage is carried out in three stages: pre-pickled stage, main pickling stage, and post-pickled stage. S2.1 Pre-pickled stage: Mix the cabbage and salt at a mass ratio of (9-11):1, add 3%-7% pure water of the total mass of the mixture, and pickle at 18-25℃ for 20-30 hours; S2.2 Main pickling stage: Add salt to make the salt concentration in the mixture reach 7%-11%, add compound biological quality improver accounting for 0.3%-0.7% of the weight of the cabbage, and introduce a mixture of oxygen and nitrogen with an oxygen content of 1%-5% using an intermittent ventilation mode, and seal and pickle for 60-84 hours. S2.3, Post-pickled stage: Add 1%-3% white sugar, 0.2%-0.4% ginger powder, 0.1%-0.3% garlic powder and 0.05%-0.15% Sichuan pepper powder according to the weight of the pickled cabbage. After stirring evenly, adjust the salt concentration to 5%-8% and seal for pickling for 36-60 hours. S3. Cut the pickled cabbage into slices 0.3-1.2cm thick or chunks 1-2cm on each side. Spray the surface with a mixed solution containing 0.1%-0.3% natamycin and 0.02%-0.05% nisin, soak for 2-3 minutes, drain the surface water and cool. S4. Modified atmosphere packaging is used for Chinese cabbage products, and the packaged finished products are stored in cold storage.

2. The method for improving the quality of pickled mustard greens as described in claim 1, characterized in that: The composite biological quality improver in step S2.2 is composed of Lactobacillus plantarum, yeast and konjac glucomannan. The konjac glucomannan is dissolved in purified water in advance, and the mass ratio of konjac glucomannan to purified water is 1:

20. After stirring until a uniform colloid is formed, it is mixed with Lactobacillus plantarum and yeast that have been activated with sterile water to obtain the composite biological quality improver.

3. The method for improving the quality of pickled mustard greens as described in claim 2, characterized in that: In step S2.2, *Lactobacillus plantarum* and yeast are activated with sterile water at 25-35℃, with a mass ratio of bacterial agent to sterile water of 1:(5-10). During activation, the mixture is stirred at 20-40 r / min for 8-12 min. The viable count of the activated bacterial solution must be ≥1×10⁻⁶. 9 CFU / mL, then mixed with konjac glucomannan colloid.

4. The method for improving the quality of pickled mustard greens as described in claim 2, characterized in that: The mass ratio of *Lactobacillus plantarum*, yeast, and konjac glucomannan is (1.5-2.5):(0.8-1.2):(0.8-1.2), wherein the viable count of *Lactobacillus plantarum* is (0.8-1.2) × 10⁻⁶. 8 CFU / g, the viable yeast count was (3-7)×10⁻⁶. 7 CFU / g.

5. The method for improving the quality of pickled mustard greens as described in claim 1, characterized in that: In step S1, select fresh, disease-free Chinese cabbage with a diameter of 6-15cm, remove the fibrous roots, old leaves and surface impurities, soak it in a vitamin C solution with a mass fraction of 0.2%-0.4% for 10-20 minutes, and dry it in a hot air drying oven at 30-45℃ until there is no free moisture on the surface.

6. The method for improving the quality of pickled mustard greens as described in claim 1, characterized in that: In step S2.1, during the pre-marinating stage, it is necessary to stir regularly. The stirring frequency is once every 4-8 hours, and each stirring lasts for 5-10 minutes. The stirring speed is 30-50 r / min.

7. The method for improving the quality of pickled mustard greens as described in claim 1, characterized in that: In step S2.1, the salt is food-grade refined salt with a particle size of 0.15-0.3mm, and the salt is dried at 105-110℃ for 2-3 hours in advance to remove free moisture.

8. The method for improving the quality of pickled mustard greens as described in claim 1, characterized in that: In step S2.2, the intermittent ventilation mode is to alternate between 10 minutes of ventilation and 20 minutes of cessation, with a ventilation rate of 0.3-0.8 L / (kg·h).

9. The method for improving the quality of pickled mustard greens as described in claim 1, characterized in that: In step S2.3, the current salt concentration of the system is detected by a salinity meter. If the concentration is >8%, pure water at 30-40℃ is added to dilute it. The pure water needs to be added in 2-3 batches, and the mixture is stirred for 5-8 minutes after each addition before retesting. If the concentration is <5%, salt is added. After adding salt, the mixture is stirred for 8-10 minutes to ensure uniform dissolution. The final salt concentration deviation is controlled within ±0.2%.

10. The method for improving the quality of pickled mustard greens as described in claim 1, characterized in that: In step S4, PET / PE composite film bags are used to package the turnips into bags of 150-250g each. The gas inside the bags is then replaced with a mixed gas using a modified atmosphere packaging machine. The mixed gas consists of 25%-35% carbon dioxide, 3%-8% oxygen, and 57%-72% nitrogen. The bags are then heat-sealed for 1-2 seconds at 130-160℃ and 0.2-0.3MPa. The finished product is then stored in a refrigerated environment at 2-10℃.

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