Method for fermenting pickled Chinese cabbages by using lactic acid bacteria

Abstract

The invention discloses a method for fermenting pickled Chinese cabbages by using lactic acid bacteria, which comprises the following steps: removing impurities from fresh pickled Chinese cabbages, washing, draining, shredding, filling into a fermentation vat, blending a sodium chloride aqueous solution by using sterilized tap water, and fermenting for 2-3 hours; pouring the prepared sodium chloride aqueous solution into a fermentation vat filled with the vegetables until the sodium chloride aqueous solution just submerges the surfaces of the vegetables, finally adding a compound lactic acid bacteria solution into the fermentation vat, performing sealed fermentation, and controlling gradient temperature for fermentation until the fermentation is finished. Through the synergistic effect of the compound lactic acid bacteria strains (lactobacillus plantarum, lactobacillus brevis and leucotrichum mesenteroides) and in combination with a gradient temperature control technology, the effects of shortening the fermentation period, reducing the peak value of nitrite and increasing the content of flavor substances are achieved, and the appearance quality, taste and the like of the pickled Chinese cabbage product are ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of food fermentation, and more specifically to a method for fermenting pickled Chinese cabbage using lactic acid bacteria. Background Art

[0002] Pickled Chinese cabbage is formed by the growth metabolism and biochemical reactions of microorganisms on fresh vegetables. The microbial fermentation of vegetables causes a series of changes in cell structure, chemical composition, etc., forming a food with a sour and fragrant taste, fresh, crispy and tender characteristics. Pickled Chinese cabbage is rich in minerals, vitamins, cellulose and other substances, and generates lactic acid, choline, acetylcholine and various enzymes, etc. after anaerobic fermentation. These metabolites have unique physiological effects on human health and disease prevention. In addition, pickled Chinese cabbage is rich in dietary fiber and probiotic flora, and has nutritional and health care values such as appetizing, promoting digestion, and reducing cholesterol.

[0003] Traditional household natural fermentation uses various microorganisms naturally attached to the surface of vegetables for fermentation, inevitably carrying a large number of miscellaneous bacteria, which hinder the growth of lactic acid bacteria, have a long fermentation cycle, are difficult to control the product quality, and are difficult to achieve standardized and large-scale production. Also, due to long-term soaking and fermentation, the fiber structure of vegetables is damaged, making the vegetables soft and sticky, affecting the appearance and taste, and the nitrite content fluctuates greatly and the flavor is unstable. And although the existing single-strain fermentation technology shortens the fermentation time, the product flavor level is single and difficult to meet the market demand.

[0004] Therefore, how to provide a method for preparing pickled Chinese cabbage with a short fermentation cycle, rich and stable flavor is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention provides a method for fermenting pickled Chinese cabbage using compound lactic acid bacteria. Through the synergistic action of compound strains and combined with gradient temperature control technology, the fermentation cycle is shortened while reducing the peak value of nitrite and increasing the content of flavor substances.

[0006] To achieve the above object, the present invention adopts the following technical scheme:

[0007] A method for fermenting pickled Chinese cabbage using lactic acid bacteria, comprising the following steps:

[0008] (1) Remove impurities from fresh vegetables, wash and drain them, then cut them into filaments and put them into a fermentation tank;

[0009] (2) Prepare a sodium chloride aqueous solution with sterilized tap water, and then pour the prepared sodium chloride aqueous solution into the fermentation tank containing vegetables until the sodium chloride aqueous solution just covers the surface of the vegetables;

[0010] (3) Add compound lactic acid bacteria liquid to the fermentation tank, seal and ferment, and control the gradient temperature until fermentation is completed.

[0011] Preferably, in step (1), the vegetables are washed with sterilized tap water.

[0012] Preferably, in step (1), the width of the shredded vegetables is 5 - 8 mm.

[0013] Preferably, in step (2), the mass concentration of the sodium chloride aqueous solution is 2% - 2.5%.

[0014] Preferably, in step (2), the ratio of the sodium chloride aqueous solution to the vegetables in terms of the liquid - to - material ratio is 1:1.2.

[0015] Preferably, the composite lactic acid bacteria liquid in step (3) comprises the following components in volume percentages:

[0016] Lactobacillus plantarum (Lactobacillus plantarum CICC, 20265) liquid 50 - 60%, Lactobacillus brevis (Lactobacillus brevis, CICC 20279) liquid 25 - 30%, Leuconostoc mesenteroides (Leuconostoc mesenteroides, CICC 20186) liquid 15 - 20%. The strains are all purchased from the China Center for Industrial Culture Collection.

[0017] Preferably, the preparation method of the composite lactic acid bacteria comprises the following steps:

[0018] Inoculate the three lactic acid bacteria strains into MRS liquid medium respectively for cultivation, cultivate at a constant temperature of 25 - 37°C for 18 - 24 h to make the viable bacteria count in the liquid medium of each lactic acid bacteria strain ≥ 1×10 9 CFU / mL, and then mix them according to the volume percentage to obtain the composite lactic acid bacteria liquid.

[0019] Preferably, the inoculation amount of the composite lactic acid bacteria liquid is 3 - 5% of the total weight of the vegetables and the sodium chloride aqueous solution in the tank.

[0020] Preferably, the gradient - temperature fermentation is specifically as follows:

[0021] Control the fermentation temperature at 20°C for 0 - 24 h (to promote the rapid acid production of Leuconostoc mesenteroides), control the fermentation temperature at 25°C for 24 - 72 h (the stage dominated by Lactobacillus plantarum), control the fermentation temperature at 18°C from 72 h to the end point (for flavor substance accumulation), and terminate the fermentation when pH ≤ 3.6 and the total acid (calculated as lactic acid) ≥ 1.2%.

[0022] Preferably, it further comprises a post - treatment step, that is, after the fermentation is completed, vacuum packaging is carried out, and then pasteurization is carried out at 75°C for 15 min.

[0023] As can be seen from the above technical solutions, compared with the prior art, the present invention discloses a method for fermenting pickled vegetables with lactic acid bacteria, which has the following beneficial effects:

[0024] Through the synergistic effect of a composite lactic acid bacteria strain (Lactobacillus plantarum + Lactobacillus brevis + Leuconostoc mesenteroides) and combined with gradient temperature control technology, the effects of shortening the fermentation period, reducing the peak value of nitrite, and increasing the content of flavor substances are achieved, and the appearance quality and taste of the pickled vegetable products are ensured. Specific embodiments

[0025] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0026] Lactobacillus plantarum (Lactobacillus plantarum CICC, 20265), Lactobacillus brevis (Lactobacillus brevis, CICC 20279), and Leuconostoc mesenteroides (Leuconostoc mesenteroides, CICC 20186) were all purchased from the China Center for Industrial Culture Collection;

[0027] Preparation of bacterial strain liquid:

[0028] The three lactic acid bacteria strains were respectively inoculated into MRS liquid medium and cultured at a constant temperature of 35°C for 18 h to make the viable count of each lactic acid bacteria strain in the liquid medium ≥ 1×10 9 CFU / mL to obtain the bacterial liquid of the three strains.

[0029] Example 1

[0030] A method for fermenting pickled vegetables with lactic acid bacteria includes the following steps:

[0031] (1) Remove impurities from the pickled vegetables with fresh vegetables (Chinese cabbages), wash them with sterilized tap water, then drain and cut them into 5-8 mm filaments, and then put them into a fermentation tank;

[0032] (2) Prepare a sodium chloride aqueous solution with a mass concentration of 2% - 2.5% using sterilized tap water, and then pour the prepared sodium chloride aqueous solution into the fermentation tank containing vegetables until the sodium chloride aqueous solution just covers the surface of the vegetables. The ratio of the sodium chloride aqueous solution to the vegetables is 1:1.2;

[0033] (3) Add the compound lactic acid bacteria liquid into the fermentation tank. The inoculation amount of the compound lactic acid bacteria liquid is 3 - 5% of the total weight of the vegetables and sodium chloride aqueous solution in the tank. Seal the fermentation tank and control the fermentation at a gradient temperature until the end. The specific gradient temperature fermentation is as follows:

[0034] Control the fermentation temperature at 20°C for 0 - 24 hours, 25°C for 24 - 72 hours, and 18°C from 72 hours to the end. Terminate the fermentation when pH ≤ 3.6 and the total acid (calculated as lactic acid) ≥ 1.2%.

[0035] The volume percentages of the three kinds of liquid in the compound lactic acid bacteria liquid are as follows:

[0036] The liquid of Lactobacillus plantarum is 60%, the liquid of Lactobacillus brevis is 25%, and the liquid of Leuconostoc mesenteroides is 15%.

[0037] Example 2

[0038] The difference from Example 1 is that the volume percentages of the three kinds of liquid in the compound lactic acid bacteria liquid are as follows:

[0039] The liquid of Lactobacillus plantarum is 50%, the liquid of Lactobacillus brevis is 30%, and the liquid of Leuconostoc mesenteroides is 20%.

[0040] Comparative Example 1

[0041] The difference from Example 1 is that 100% of the liquid of Lactobacillus plantarum is used for fermentation.

[0042] Comparative Example 2

[0043] The difference from Example 1 is that the fermentation is carried out at a constant temperature of 25°C until the end.

[0044] Experimental Example 1

[0045] Count the fermentation cycle, lactic acid content, and sensory score of Examples 1 - 2 and Comparative Example 1. The sensory scoring criteria mainly include color, smell, taste, and physical state. The specific criteria are as follows:

[0046] Color: The pickled Chinese cabbage should show dark green or yellowish green, with bright red and light yellow surfaces, uniform. The color scoring criteria are: the color of fresh raw materials is 10 points, and dark brown is 0 points;

[0047] Smell: The pickled Chinese cabbage should have the sour fragrance of lactic acid bacteria fermentation, without abnormal smell. The smell scoring criteria are: fresh fragrance is 10 points, and no pickling flavor is 0 points;

[0048] Taste: The pickled Chinese cabbage should have the sour fragrance of lactic acid bacteria fermentation, without abnormal taste. The taste scoring criteria are: moderately sour and salty is 10 points, and excessive sourness is 0 points.

[0049] Appearance: The pickled Chinese cabbage should have its inherent shape and texture, without visible foreign impurities to the naked eye. The appearance scoring standard is: 10 points for no impurities and 0 points for having impurities.

[0050] The results are shown in Table 1 as follows:

[0051] Table 1 Comparison of Fermentation Results of Examples 1-2 and Comparative Example 1

[0052] Group Fermentation cycle (days) Lactic acid content (g / 100g) Sensory score (0 - 10) Comparative example 1 9 1.35 7.2 Example 1 7 1.58 9.1 Example 2 8 1.62 9.4

[0053] The above results show that Examples 1-2 using the method of the present invention have a shorter fermentation period, and the lactic acid content and sensory score of the fermented products are far better than those of Comparative Example 1, that is, the use of compound lactic acid bacteria fermentation has a more excellent effect compared with single strains.

[0054] Experimental Example 2

[0055] Compare the nitrite peak value and the pH at the end of fermentation of the products of Example 2 and Comparative Example 2. The results are shown in Table 2 as follows.

[0056] Table 2 Comparison of the Products of Example 2 and Comparative Example 2

[0057] Group Nitrite peak value (mg / kg) pH at the end of fermentation Comparative example 2 12.5 3.4 Example 2 8.2 3.6

[0058] The above results show that the gradient temperature control fermentation technology using the technical solution of the present invention can reduce the nitrite peak value by 34%, and can avoid the texture softening of the pickled Chinese cabbage products caused by excessive acidification, ensuring the quality.

[0059] Each embodiment in this specification is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. The same or similar parts among the embodiments can be referred to each other. The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for fermenting sauerkraut using lactic acid bacteria, characterized in that: The following steps are involved: (1) removing impurities from fresh sauerkraut, washing it, draining it, cutting it into shreds, and then putting it into a fermentation tank; (2) using sterile tap water to prepare a sodium chloride aqueous solution, and then pouring the prepared sodium chloride aqueous solution into the fermentation tank containing the vegetables until the sodium chloride aqueous solution just covers the surface of the vegetables; (3) Adding a compound lactic acid bacteria liquid into a fermentation tank, sealing the tank for fermentation, and controlling the gradient temperature for fermentation until the end.

2. The method for fermenting sauerkraut using lactic acid bacteria according to claim 1, characterized in that: In step (1), the vegetables are washed with sterilized tap water.

3. The method for fermenting sauerkraut using lactic acid bacteria according to claim 1, characterized in that: The width of the shredded material in step (1) is 5-8 mm.

4. The method for fermenting sauerkraut using lactic acid bacteria according to claim 1, characterized in that: The mass concentration of the sodium chloride aqueous solution in step (2) is 2%-2.5%.

5. The method for fermenting sauerkraut using lactic acid bacteria according to claim 1, characterized in that: In step (2), the material-liquid ratio of the sodium chloride aqueous solution to the vegetables is 1:1.

2.

6. The method for fermenting sauerkraut using lactic acid bacteria according to claim 1, characterized in that: The composite lactic acid bacteria liquid described in step (3) includes the following components in volume percentage: Lactobacillus plantarum (CICC, 20265) bacterial solution 50-60%, Lactobacillus brevis (CICC, 20279) bacterial solution 25-30%, Leuconostocmesenteroides (CICC, 20186) bacterial solution 15-20%, all of which were purchased from the China Industrial Microbiology Culture Collection Administration Center.

7. The method for fermenting sauerkraut using lactic acid bacteria according to claim 6, characterized in that: The preparation method of the composite lactic acid bacteria comprises the following steps: The three lactic acid bacteria strains were inoculated into MRS liquid culture medium and cultured at 25-37°C for 18-24 hours until the number of viable bacteria in the liquid culture medium of each lactic acid bacteria strain was ≥1×10 9 CFU / mL, and then mixed according to volume percentage to obtain a composite lactic acid bacteria solution.

8. The method for fermenting sauerkraut using lactic acid bacteria according to claim 1, characterized in that: The inoculation amount of the composite lactic acid bacteria liquid is 3-5% of the total weight of the vegetables and the sodium chloride aqueous solution in the tank.

9. The method for fermenting sauerkraut using lactic acid bacteria according to claim 1, characterized in that: Gradient temperature fermentation is specifically as follows: The fermentation temperature is controlled at 20°C for 0-24 hours, at 25°C for 24-72 hours, at 18°C ​​from 72 hours to the end point, and the fermentation is terminated when the pH is ≤3.6 and the total acidity calculated as lactic acid is ≥1.2%.

10. The method for fermenting sauerkraut using lactic acid bacteria according to claim 1, characterized in that: Also includes: The post-processing step is vacuum packaging after fermentation, followed by pasteurization at 75°C for 15 minutes.