Direct vat set northeast Chinese sauerkraut leavening agent, preparation method thereof and Chinese sauerkraut processing method

Abstract

The invention belongs to the technical field of fermented food, and particularly discloses a direct vat set northeast Chinese sauerkraut leavening agent and a preparation method thereof and a Chinese sauerkraut processing method.The preparation method comprises the steps of preparing a clostridium butyricum seed solution, preparing a lactobacillus plantarum seed solution, preparing a leuconostoc mesenteroides seed solution and preparing the direct vat set northeast Chinese sauerkraut leavening agent; and finally preparing the direct vat set northeast pickled Chinese cabbage leavening agent by using a vacuum freeze-drying method. Compared with the prior art, in the vegetable fermentation process, the nitrite content in the pickled Chinese cabbage can be remarkably reduced, the food safety can be improved, the fermentation time can be shortened, clostridium butyricum does not hydrolyze cellulose, the crisp and tender taste of the pickled Chinese cabbage is guaranteed, and the flavor and texture of the pickled Chinese cabbage can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of fermented foods, in particular to a direct-throw type northeastern sauerkraut starter and a preparation method thereof and a method for processing sauerkraut. Background Art

[0002] Northeastern pickled cabbage is a specialty pickled food in northern my country. Currently, most Northeastern pickled cabbage is produced by natural fermentation. Natural fermentation has problems such as unstable quality, excessive nitrite, and seasonal restrictions, which restrict the industrial development of Northeastern pickled cabbage. Direct-injection compound fermentation agents can shorten the fermentation cycle of pickled cabbage, improve the quality of pickled cabbage, and help the pickled cabbage industry achieve standardization, specialization, and unification.

[0003] At present, the production of sauerkraut mostly adopts the method of natural fermentation. The natural fermentation cycle is long (more than one month), the pollution of bacteria and other harmful substances cannot be controlled, and the sanitary quality is difficult to guarantee. At the same time, due to the long-term immersion and fermentation, the fiber structure of the vegetables is destroyed, making the vegetables soft and sticky, affecting the appearance and taste. In recent years, with the continuous development of modern food processing technology and food biotechnology research and application, especially the rapid increase in the number of consumers who love sauerkraut at home and abroad and the rapid expansion of consumption scope, sauerkraut has been transformed from traditional family production to modern, large-scale, factory production, and from natural fermentation to lactic acid bacteria fermentation.

[0004] During the pickling process of sauerkraut, the nitrate in the vegetables will be converted into nitrite by some bacteria through nitrate reductase. This is a natural biochemical process. The nitrate content will decrease with the increase of pickling time, and part of the nitrate will be converted into nitrite. Moreover, nitrate can also be converted into nitrite in the human body, so it is also important to reduce its content. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a direct-injection Northeastern sauerkraut fermentation agent and a preparation method thereof and a sauerkraut processing method.

[0006] To achieve the above object, the present invention is implemented according to the following technical solutions:

[0007] One of the purposes of the present invention is to provide a method for preparing a direct-throw type Northeastern sauerkraut starter, comprising the following steps:

[0008] S1. Preparation of Clostridium butyricum seed solution: inoculate Clostridium butyricum with a preservation number of CICC 23847 into 50 mL RCM solid culture medium, and culture at 37° C. for 24-40 hours to obtain activated Clostridium butyricum; inoculate the activated Clostridium butyricum into RCM liquid culture medium at an inoculum amount of 5-7%, and culture at 37° C. for 40-60 hours to obtain Clostridium butyricum seed solution;

[0009] S2, preparation of Lactobacillus plantarum seed liquid: take Lactobacillus plantarum with a preservation number of CICC 21812 and inoculate it in 50 mL of MRS solid culture medium, and culture it at 35-37° C. for 24-40 h to obtain activated Lactobacillus plantarum; inoculate the activated Lactobacillus plantarum into MRS liquid culture medium at an inoculum amount of 5-7%, and culture it at 37° C. for 40-60 h to obtain Lactobacillus plantarum seed liquid;

[0010] S3. Preparation of Leuconostoc mesenteroides seed solution: inoculate Leuconostoc mesenteroides with a preservation number of CICC 6055 into 50 mL of MRS solid culture medium, and culture at 37° C. for 24-40 h to obtain activated Leuconostoc mesenteroides; inoculate the activated Leuconostoc mesenteroides into MRS liquid culture medium at an inoculum amount of 5-7%, and culture at 37° C. for 40-60 h to obtain Leuconostoc mesenteroides seed solution;

[0011] S4. Preparation of direct-throw Northeastern sauerkraut starter: Take Clostridium butyricum seed liquid, Lactobacillus plantarum seed liquid, and Leuconostoc mesenteroides seed liquid in a volume ratio of (2-3): (1-1.5): (1-1.5), and then inoculate them into a mixed liquid culture medium at an inoculation rate of 5-7%, and culture anaerobically at 37°C for 8-16 hours; then centrifuge, and use an oscillator to mix and oscillate the mixed bacterial mud collected by centrifugation with 1 / 3 of the mass of the mixed bacterial mud with a freeze-dried protective agent to make it uniform, to prepare a bacterial suspension, and then use a vacuum freeze-drying method to prepare a direct-throw Northeastern sauerkraut starter.

[0012] Furthermore, the mixed liquid culture medium is composed of the following raw materials: 10 g / L yeast extract, 8 g / L beef extract, 10 g / L glucose, 1.8 g / L KH2PO4, 1.5 g / L MgSO4, 2.6 g / L cysteine ​​hydrochloride, 1.2 g / L sodium chloride, and the remainder is deionized water, pH 6.5.

[0013] Furthermore, the freeze-dried protective agent is composed of the following raw materials in volume percentage: 8-10% skim milk powder, 4-6% trehalose, 4-6% sucrose, 0.5-1% vitamin C, 1-3% sodium glutamate, and the balance is deionized water.

[0014] The second object of the present invention is to provide a direct-injection Northeastern sauerkraut fermentation agent prepared by the above method.

[0015] The third object of the present invention is to provide a method for processing sauerkraut using the above-mentioned direct-injection type Northeastern sauerkraut fermentation agent, comprising the following steps:

[0016] S1. Remove the roots of the cabbage, wash away the dirt and impurities with tap water, and drain the water on the surface of the cabbage;

[0017] S2, put the cabbage into the jar, sprinkle a layer of salt on each layer of cabbage, the final weight of the salt used is 3%-5% of the weight of the cabbage, compact the cabbage, and pickle for three days;

[0018] S3, dissolving the composite sauerkraut fermentation agent with room temperature purified water, pouring it into the tank, adding 2-5g of direct-injection Northeastern sauerkraut fermentation agent per kilogram of cabbage, and the water surface completely covers the cabbage in the tank;

[0019] S4. Ferment at 20-25℃ and it can be eaten after 20-30 days.

[0020] Preferably, in step S3, the water surface is 5-10 cm higher than the surface of the cabbage.

[0021] Preferably, in step S2, the weight of the salt finally used is 4% of the weight of the cabbage.

[0022] Compared with the prior art, the present invention has the following effects:

[0023] 1) Reducing nitrite: During the fermentation process of fermented vegetables, through the complementary advantages and synergistic enhancement among the strains of Clostridium butyricum, Lactobacillus plantarum and Leuconostoc mesenteroides, Leuconostoc mesenteroides and Lactobacillus plantarum can quickly start fermentation and reproduce rapidly, and the content of acids, especially lactic acid, in the fermentation system is significantly increased. The accumulation of acidic substances leads to a decrease in the pH value of the fermentation system; at the same time, Leuconostoc mesenteroides is promoted to produce nitrite reductase to reduce nitrite to nitrogen gas or other nitrogen forms, thereby reducing the content of nitrite; the composite leavening agent of the present invention can significantly reduce the nitrite content in sauerkraut, improve food safety, and shorten the fermentation time.

[0024] 2) Improve flavor: Clostridium butyricum does not hydrolyze cellulose, which can ensure the crispy and tender taste of sauerkraut and improve the flavor and texture of sauerkraut. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The number of viable bacteria cultured in a mixed liquid culture medium is obtained by inoculating Clostridium butyricum seed solution, Lactobacillus plantarum seed solution, and Leuconostoc mesenteroides seed solution into the mixed liquid culture medium in a volume ratio of (2-3):(1-1.5):(1-1.5).

[0026] Figure 2 It is the number of viable bacteria cultured when the seed solution of Clostridium butyricum is inoculated into the mixed liquid culture medium.

[0027] Figure 3 It is the number of viable bacteria cultured when Lactobacillus plantarum seed liquid is inoculated into mixed liquid culture medium alone.

[0028] Figure 4 It is the number of viable bacteria cultured when the seed solution of Enterococcus mesenteroides is inoculated into the mixed liquid culture medium.

[0029] Figure 5 The pH change curves during the fermentation of sauerkraut in Application Example 1 and Comparative Application Example 1 are shown.

[0030] Figure 6 The nitrite change curves during the fermentation of sauerkraut in Application Example 1 and Comparative Application Example 1 are shown. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with embodiments. The specific embodiments described here are only used to explain the present invention and are not used to limit the invention.

[0032] Example 1

[0033] This embodiment exemplarily shows a specific preparation process of a direct-injection Northeastern sauerkraut fermentation agent:

[0034] 1) Preparation of Clostridium butyricum seed solution: Clostridium butyricum with the collection number CICC23847 purchased from the China Industrial Microorganism Collection Center was inoculated into 50 mL of RCM solid culture medium and cultured at 37°C for 24-40 h to obtain activated Clostridium butyricum; the activated Clostridium butyricum was inoculated into RCM liquid culture medium at an inoculum amount of 5-7%, cultured at 37°C for 40-60 h to obtain Clostridium butyricum seed solution, and the bacteria were counted, and the result was 4.2×10 9 CFU / mL;

[0035] 2) Preparation of plant lactobacillus seed solution: The plant lactobacillus with the deposit number of CICC21812 purchased from the China Industrial Microorganism Collection Center was inoculated into 50 mL MRS solid medium and cultured at 35-37 ° C for 24-40 h to obtain activated plant lactobacillus; the activated plant lactobacillus was inoculated into MRS liquid medium at an inoculum amount of 5-7%, and cultured at 37 ° C for 40-60 h to obtain plant lactobacillus seed solution, and the bacteria were counted, and the result was 4.3 × 10 9 CFU / mL;

[0036] 3) Preparation of Leuconostoc mesenteroides seed solution: Leuconostoc mesenteroides with the collection number CICC 6055 purchased from the China Industrial Microorganism Collection Center was inoculated into 50 mL MRS solid culture medium and cultured at 37° C. for 24-40 h to obtain activated Leuconostoc mesenteroides; the activated Leuconostoc mesenteroides was inoculated into MRS liquid culture medium at an inoculum amount of 5-7%, and cultured at 37° C. for 40-60 h to obtain Leuconostoc mesenteroides seed solution, and the bacteria were counted, and the result was 4.2×10 9 CFU / mL;

[0037] S4. Preparation of direct-throwing Northeastern sauerkraut starter: Take Clostridium butyricum seed solution, Lactobacillus plantarum seed solution, and Leuconostoc mesenteroides seed solution in a volume ratio of (2-3): (1-1.5): (1-1.5), and then inoculate them into a mixed liquid culture medium according to an inoculation amount of 5-7%. In this embodiment, the mixed liquid culture medium is composed of the following raw materials: yeast extract 10 g / L, beef extract 8 g / L, glucose 10 g / L, KH2PO4 1.8 g / L, MgSO4 1.5 g / L, cysteine ​​hydrochloride 2.6 g / L, sodium chloride 1.2 g / L, and the remainder is deionized water, pH 6.8; anaerobic culture at 37°C for 8-16 h, centrifugation, and mixing and oscillating the mixed bacterial mud collected after centrifugation with a freeze-drying protective agent of 1 / 3 of the mass of the mixed bacterial mud with an oscillator to make it uniform, to prepare a bacterial suspension, and then use a vacuum freeze-drying method to prepare a direct-throwing Northeastern sauerkraut starter to ensure that the number of the three strains in the starter at this time is maximized.

[0038] In this embodiment, in order to perform freeze-drying protection on the mixed culture of Clostridium butyricum, Lactobacillus plantarum and Leuconostoc mesenteroides, the freeze-drying protective agent is composed of the following raw materials in volume percentage: 8-10% skim milk powder, 4-6% trehalose, 4-6% sucrose, 0.5-1% vitamin C, 1-3% sodium glutamate, and the balance is deionized water.

[0039] Comparative Example 1

[0040] The difference from Example 1 is that in step S4, Clostridium butyricum seed solution is inoculated alone.

[0041] Comparative Example 2

[0042] The difference from Example 1 is that in step S4, Lactobacillus plantarum seed liquid is inoculated alone.

[0043] Comparative Example 3

[0044] The difference from Example 1 is that in step S4, the seed solution of Leuconostoc mesenteroides is inoculated alone.

[0045] The number of Clostridium butyricum, Lactobacillus plantarum and Leuconostoc mesenteroides was detected by sampling Example 1 and Comparative Examples 1 to 3, respectively. The results are as follows: Figure 1-Figure 4 As shown by Figure 1-4 It can be seen that after the mixed culture of Clostridium butyricum, Lactobacillus plantarum and Leuconostoc mesenteroides, the three species complement each other's advantages and synergize to enhance their effectiveness, and can quickly enter the logarithmic growth phase. The maximum number of viable bacteria can be reached after 14 hours of co-culture, which can increase the amount of viable bacteria of all strains in the fermentation broth; afterwards, because Clostridium butyricum provides metabolites for Lactobacillus plantarum and Leuconostoc mesenteroides as part of the nutrients required for growth, the number of Clostridium butyricum decreases slightly, while the number of Lactobacillus plantarum and Leuconostoc mesenteroides continues to increase; this provides a basis for the subsequent production of acid and enzymes that degrade nitrite.

[0046] Application Example 1

[0047] The direct-injection Northeastern pickled cabbage fermentation agent of Example 1 is used to process pickled cabbage, and the specific process is as follows:

[0048] 1) Remove the roots of the cabbage, wash away the dirt and impurities with tap water, and drain the water on the surface of the cabbage;

[0049] 2) Put the cabbage into the jar, sprinkle a layer of salt on each layer of cabbage, and finally use 4% of the weight of the salt. Press the cabbage and pickle it for three days;

[0050] 3) Dissolve the composite sauerkraut fermentation agent in room temperature purified water and pour it into a tank. Add 2g of direct-injection Northeastern sauerkraut fermentation agent per kilogram of cabbage, and make sure that the water surface completely covers the cabbage in the tank and is 5-10cm higher than the surface of the cabbage.

[0051] 4) Fermentation is carried out at 25° C. and the product can be eaten after 20 days. Meanwhile, during the fermentation process, Clostridium butyricum, Lactobacillus plantarum and Leuconostoc mesenteroides are counted. The counting method is based on the conventional method and will not be described in detail in this embodiment.

[0052] Comparative application example 1

[0053] The difference from Application Example 1 is that the composite sauerkraut starter is replaced with commercially available Sangchuan kimchi lactic acid bacteria powder.

[0054] Quality testing: After fermentation is completed, the pH value, nitrite content, and sensory evaluation indicators of the sauerkraut are tested to ensure that the product meets food safety standards.

[0055] 1) pH value detection of sauerkraut

[0056] The changes in pH value during the fermentation of sauerkraut in Application Example 1 and Comparative Application Example 1 are as follows: Figure 5 As shown by Figure 5It can be seen that the pH value change trend during the sauerkraut fermentation process of conventional lactic acid bacteria fermentation and the direct-throw type Northeastern sauerkraut fermentation agent of this embodiment is the same, and the pH value gradually decreases with the extension of time. The pH value of the direct-throw type Northeastern sauerkraut fermentation agent of this embodiment decreases rapidly during the sauerkraut fermentation process, and the pH value can be reduced to 3.6 after 5 days of fermentation, while the pH value of comparative application example 1 can only be reduced to 5.0 in the end. This is because, in Comparative Application Example 1, only lactic acid bacteria are used without adding exogenous fermentation agents. The lactic acid bacteria in the fermentation system mainly come from the raw materials themselves, and it takes a slightly longer time to reproduce and metabolize before they can become the dominant bacteria. However, the inoculation of the fermentation agent in Application Example 1 enables the lactic acid bacteria, Leuconostoc mesenteroides and Lactobacillus plantarum in the fermentation system to quickly start fermentation and reproduce rapidly. The content of acids, especially lactic acid, in the fermentation system is significantly increased, and the accumulation of acidic substances causes the pH value of the fermentation system to decrease. In the early stage of sauerkraut fermentation, the heterolactic fermentation is dominated by Leuconostoc mesenteroides, which makes it the dominant bacteria in the early stage of fermentation. Leuconostoc mesenteroides reproduces in large numbers, and the heterolactic fermentation converts glucose into substances such as lactic acid and acetic acid through the pentose phosphate pathway. At the same time, Clostridium butyricum can provide special metabolites to provide nutrients for Leuconostoc mesenteroides and Lactobacillus plantarum to continue the mid- and late-stage fermentation. The pH value of the fermentation system drops rapidly, so when the fermentation is 9 days, the pH value of the fermentation system of Application Example 1 is the lowest.

[0057] 2) Detection of nitrite content in sauerkraut

[0058] The nitrite content was determined by the naphthylethylenediamine hydrochloride method in the national standard method (GB5009.33-2016). The test results are as follows: Figure 6 As shown by Figure 6 It can be seen that the nitrite content of Application Example 1 reached a maximum of 20.2 mg / kg at 3 days of fermentation, which was significantly lower than 30.3 mg / kg of Comparative Application Example 1; and after 20 days of fermentation, the nitrite content of Application Example 1 reached a minimum of 2.6 mg / kg, which was far lower than 13.2 mg / kg of Comparative Application Example 1.

[0059] 3) Sensory evaluation of sauerkraut

[0060] Graduate students of food science aged 22 to 27 were invited to serve as sensory evaluators. After training, 20 qualified personnel (10 men and 10 women) were selected to form a sensory evaluation team to conduct sensory evaluation of sauerkraut. The test environment was at room temperature. After training, the evaluators conducted sensory evaluation on the acidity, crispness, umami, color and viscosity of sauerkraut. The total score was 100 points. The total score of each sample was calculated and added up. The sensory evaluation standard of sauerkraut is shown in Table 1.

[0061] Table 1

[0062]

[0063] The sensory evaluation results are shown in Table 2.

[0064] Table 2

[0065]

[0066]

[0067] It can be seen from the sensory score table in Table 2 that the sensory scores of commercially available single-bacteria fermented sauerkraut are all lower than those of the sauerkraut inoculated with the composite starter of the present invention, mainly because of insufficient acidity, crispness and umami taste.

[0068] The technical solution of the present invention is not limited to the above-mentioned specific embodiments. All technical variations made according to the technical solution of the present invention fall within the protection scope of the present invention.

Claims

1. A method for preparing a direct-injection Northeastern sauerkraut fermentation agent, characterized in that: The following steps are involved: S1. Preparation of Clostridium butyricum seed solution: inoculate Clostridium butyricum with a preservation number of CICC 23847 into 50 mL of RCM solid culture medium, and culture at 37° C. for 24-40 hours to obtain activated Clostridium butyricum; inoculate the activated Clostridium butyricum into RCM liquid culture medium at an inoculum amount of 5-7%, and culture at 37° C. for 40-60 hours to obtain Clostridium butyricum seed solution; S2, preparation of Lactobacillus plantarum seed liquid: take Lactobacillus plantarum with a deposit number of CICC 21812 and inoculate it into 50 mL MRS solid culture medium, and culture it at 35-37° C. for 24-40 h to obtain activated Lactobacillus plantarum; inoculate the activated Lactobacillus plantarum into MRS liquid culture medium at an inoculum amount of 5-7%, and culture it at 37° C. for 40-60 h to obtain Lactobacillus plantarum seed liquid; S3. Preparation of Leuconostoc mesenteroides seed solution: inoculate Leuconostoc mesenteroides with a preservation number of CICC 6055 into 50 mL MRS solid culture medium, and culture at 37° C. for 24-40 h to obtain activated Leuconostoc mesenteroides; inoculate the activated Leuconostoc mesenteroides into MRS liquid culture medium at an inoculum amount of 5-7%, and culture at 37° C. for 40-60 h to obtain Leuconostoc mesenteroides seed solution; S4. Preparation of direct-throw northeastern sauerkraut starter: Take Clostridium butyricum seed liquid, Lactobacillus plantarum seed liquid, and Leuconostoc mesenteroides seed liquid in a volume ratio of (2-3): (1-1.5): (1-1.5), inoculate them into a mixed liquid culture medium at an inoculation rate of 5-7%, culture anaerobically at 37°C for 8-16h, centrifuge, and use an oscillator to mix and oscillate the mixed bacterial mud collected by centrifugation with 1 / 3 of the mass of a freeze-dried protective agent to make it uniform, to prepare a bacterial suspension, and then use a vacuum freeze-drying method to prepare a direct-throw northeastern sauerkraut starter.

2. The method for preparing the direct-injection Northeastern sauerkraut starter according to claim 1, characterized in that: The mixed liquid culture medium is composed of the following raw materials: 10 g / L yeast extract, 8 g / L beef extract, 10 g / L glucose, 1.8 g / L KH2PO4, 1.5 g / L MgSO4, 2.6 g / L cysteine ​​hydrochloride, 1.2 g / L sodium chloride, and the balance is deionized water, with a pH of 6.

5.

3. The method for preparing the direct-injection Northeastern sauerkraut starter according to claim 1, characterized in that: The freeze-drying protective agent is composed of the following raw materials in volume percentage: 8-10% skim milk powder, 4-6% trehalose, 4-6% sucrose, 0.5-1% vitamin C, 1-3% sodium glutamate, and the balance is deionized water.

4. A direct-injection Northeastern sauerkraut starter prepared by the method according to claims 1-3.

5. A method for processing sauerkraut using the direct-injection Northeastern sauerkraut fermentation agent as claimed in claim 4, characterized in that: The following steps are involved: S1. Remove the roots of the cabbage, wash away the dirt and impurities with tap water, and drain the water on the surface of the cabbage; S2, put the cabbage into the jar, sprinkle a layer of salt on each layer of cabbage, the final weight of the salt used is 3%-5% of the weight of the cabbage, compact the cabbage, and pickle for three days; S3, dissolving the composite sauerkraut fermentation agent with room temperature purified water, pouring it into the tank, adding 2-5g of direct-injection northeastern sauerkraut fermentation agent per kilogram of cabbage, and the water surface completely covers the cabbage in the tank; S4. Ferment at 20-25℃ and it can be eaten after 20-30 days.

6. The method for preparing the direct-injection Northeastern pickled cabbage starter according to claim 5, characterized in that: In step S3, the water surface is 5-10 cm higher than the surface of the cabbage.

7. The method for preparing the direct-injection Northeastern pickled cabbage starter according to claim 5, characterized in that: In step S2, the weight of the salt finally used is 4% of the weight of the cabbage.

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