Fermented pickles and process for preparing the same

Abstract

The application discloses a kind of fermented pickles and its preparation process, it is related to pickles technical field, to solve the problem of traditional pickles unstable flavor, industrialization adaptation is poor, high labor cost.The process is divided into three steps: S1 mixed glucose, soybean meal enzymatic solution and other raw materials, wherein soybean meal is prepared by two-step enzymolysis of alkaline protease and flavour protease to obtain soybean meal enzymatic solution, and the flavour base liquid is obtained after adjusting pH;S2 inoculate mixed bacteria liquid containing lactobacillus plantarum, lactobacillus brevis and yeast for anaerobic fermentation, then add spices and aroma fermentation in micro-oxygen environment, and prepare flavour fermentation base liquid;S3 soak vegetables in flavour fermentation base liquid, add salt after seasoning, and get finished product by pasteurization.The core of the process is "first stable base liquid, then soak vegetables", the pickles prepared have bright color, crisp and tender taste, and coordinated flavor, and have high industrialization adaptation, can also control harmful substances, improve nutrition and antioxidant properties, and overcome the drawbacks of traditional process.

Description

Technical Field

[0001] This invention relates to the field of kimchi technology, specifically to a fermented kimchi and its preparation process. Background Technology

[0002] Traditional kimchi processing falls under the category of intensive processing of edible agricultural products. Its core lies in imparting a unique sour and savory flavor to vegetables such as radishes and wild radishes through fermentation. It is a common processed food that combines nutritional value with regional culinary cultural attributes. In long-term traditional processing practices, this technique relies heavily on natural fermentation, where flavor compounds are generated by microorganisms in the natural environment. The processing is closely integrated with experiential operations, forming a traditional production system with distinct regional characteristics.

[0003] In existing traditional kimchi processing techniques, vegetables are directly added to a pre-stabilized fermentation container as raw materials. The entire fermentation process requires adjustments to be made based on the condition of the vegetables. Workers must continuously observe the fermentation process within the container to determine whether the vegetables have reached the required flavor standards and remove them for later use. This processing method deeply binds the vegetables to the fermentation process; the freshness and handling condition of the vegetables directly affect the fermentation progress, and maintaining the fermentation environment relies heavily on human experience. The operational procedures are highly correlated with the fermentation results.

[0004] In large-scale production scenarios, the inherent limitations of traditional kimchi processing techniques are becoming increasingly apparent. On the one hand, the fermentation process requires vegetables as the direct participant and has a relatively long cycle. Responding to orders necessitates restarting the entire process from vegetable pretreatment to fermentation, leading to delays in processing and difficulty in quickly matching market supply schedules, thus failing to meet the timeliness requirements of large-scale production. On the other hand, key steps throughout the processing, such as vegetable input, fermentation status monitoring, and finished product screening, all rely on manual experience and operation. This not only significantly increases labor costs but also reduces overall processing efficiency due to the uncertainty of human intervention, severely hindering the industrial upgrading of traditional flavored kimchi. Therefore, based on the limitations of the aforementioned technologies, there is an urgent need to develop a fermented kimchi method and its preparation process. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a fermented kimchi and its preparation process, which effectively solves the problems of traditional kimchi processing, such as the need for vegetables to be directly put into fermentation containers for long-term fermentation, slow processing response leading to untimely order delivery, cumbersome procedures, high labor costs, and difficulty in adapting to industrial production.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] This invention provides a process for preparing fermented kimchi, comprising the following preparation steps:

[0008] S1: Add glucose, soybean meal hydrolysate, dipotassium hydrogen phosphate and calcium chloride to purified water and stir well. Add citric acid aqueous solution to adjust the pH to obtain flavor base liquid.

[0009] S2: Inoculate the mixed bacterial solution into the flavor base liquid for anaerobic fermentation. After anaerobic fermentation, add spices, maintain a micro-aerobic environment, and carry out micro-aerobic aroma-enhancing fermentation to obtain the flavor fermentation base liquid.

[0010] S3: Add vegetables to the flavor fermentation base liquid, add salt and stir well, let it stand and soak to obtain seasoned kimchi, pack the seasoned kimchi into bags, pasteurize to obtain fermented kimchi.

[0011] Furthermore, the preparation method of the soybean meal enzymatic hydrolysate is as follows:

[0012] Take soybean meal, grind it and sieve it. Mix the sieved soybean meal powder with purified water and put it into an enzymatic hydrolysis tank and stir it into a uniform suspension. First, add alkaline protease, adjust the pH, stir and heat to hydrolyze. Then add flavor protease, cool down and continue stirring to hydrolyze. After the enzymatic hydrolysis is completed, heat the system to inactivate the enzyme. After cooling, filter it with a plate and frame filter to remove the residue and obtain soybean meal enzymatic hydrolysate.

[0013] Further, in the preparation of the soybean meal enzymatic hydrolysate: soybean meal is pulverized and passed through a 75-85 mesh sieve; the sieved soybean meal powder is mixed with purified water at a weight ratio of 1:(7.5-8.5); the amount of alkaline protease added is 0.25%-0.35% of the weight of soybean meal powder; the pH is adjusted using sodium hydroxide aqueous solution to maintain the pH at 8.0-8.5; enzymatic hydrolysis is carried out for 2.5-3 hours after heating to 50℃-55℃; the amount of flavor protease added is 0.08%-0.12% of the weight of soybean meal powder; enzymatic hydrolysis is carried out for 1.5-2 hours after cooling to 45-50℃; when inactivating the enzyme, the temperature is raised to 90℃-95℃ and kept at that temperature for 15-20 minutes; after cooling to 28℃-32℃, the mixture is filtered; the pore size of the filter cloth in the plate and frame filter is 0.22μm-0.45μm.

[0014] Further, the preparation method of the mixed bacterial solution is as follows: *Lactobacillus plantarum*, *Lactobacillus brevis*, and *Saccharomyces cerevisiae* are added to purified water at a live cell ratio of (3.0-3.2):(2.0-2.2):1. Glucose is added, and the mixture is stirred at room temperature until the glucose dissolves. After standing and activation, the mixed bacterial solution is obtained, with a live cell count of 1.0 × 10⁻⁶. 9 CFU / mL -1.5×10 9 CFU / mL.

[0015] Furthermore, in the preparation of the mixed bacterial solution: the amount of glucose added to the mixed bacterial solution is 2%-5% of the mass of the mixed bacterial solution; the stirring speed is 28rpm-32rpm, and after stirring until the glucose is completely dissolved, it is allowed to stand and activate at 35℃-37℃ for 25min-35min.

[0016] Further, in step S1, the mass ratio of glucose, soybean meal enzymatic hydrolysate, dipotassium hydrogen phosphate, calcium chloride, and purified water is 1:(4.0-5.0):(0.3-0.5):(0.5-0.8):(90-110); the mass concentration of the citric acid aqueous solution is 8%-12%, and the pH of the system is stabilized at 5.8-6.2 after adjustment; the stirring speed is 45rpm-55rpm, and the stirring time is 12min-15min.

[0017] Further, in step S2, the inoculum amount of the mixed bacterial solution is 1.5%-3.0% of the weight of the flavor base liquid; during anaerobic fermentation, nitrogen gas is first introduced into the system for 2.5-3.5 minutes to remove oxygen, and after sealing, the temperature is maintained at 28℃-30℃, the stirring speed is 18-22 rpm, and the fermentation time is 48-54 hours. During this period, the pH is monitored every 12 hours. When the pH drops to 4.2, 0.1%-0.15% of the weight of the flavor base liquid of glucose is added; during microaerobic aroma-enhancing fermentation, the dissolved oxygen content of the system is controlled at 2%-3%, the temperature at 22℃-25℃, the stirring speed at 18-22 rpm, and the fermentation time is 24-28 hours; the amount of spices added is 3%-5% of the weight of the flavor base liquid.

[0018] The ingredients of the spices, by weight, are 3.0-4.0 parts dried chili pepper segments, 5.0-6.0 parts minced garlic, 1.5-2.0 parts ginger slices, and 0.3-0.5 parts star anise powder.

[0019] Further, in step S3, the weight ratio of vegetables to flavor fermentation base liquid is (1.1-1.3):1; the amount of salt added is 1.5%-2.0% of the weight of flavor fermentation base liquid; the static soaking temperature is 20℃-22℃, the soaking time is 24h-45h, and the mixture is stirred once every 1.5h-2h for 2min-3min each time, with a stirring speed of 15rpm-20rpm.

[0020] Furthermore, the vegetable is one or more of carrots, white radishes, and ground ox.

[0021] On the other hand, the present invention provides fermented kimchi prepared by the above-mentioned fermented kimchi preparation process.

[0022] The beneficial effects of this invention are:

[0023] 1. This invention significantly enhances the adaptability of fermented kimchi to industrial production. Through the process design of "preparing a stable flavor fermentation base liquid first and then soaking vegetables", the flavor base liquid can be prepared in batches in advance, shortening the order response cycle, reducing manual monitoring and operation costs, and solving the pain points of low production efficiency and difficulty in scaling up caused by the deep binding of vegetables and fermentation process in traditional processes.

[0024] 2. This invention can significantly improve the overall sensory quality of fermented kimchi, while maintaining the bright color and crisp texture of the vegetable raw materials and forming a harmonious and rich sour and fragrant flavor. It avoids the problems of soft and mushy texture and uneven flavor that are easy to occur in traditional fermentation processes, thus improving the overall eating experience.

[0025] 3. This invention optimizes the nutritional value and food safety of fermented kimchi. On the one hand, it promotes the generation and accumulation of beneficial nutrients and enhances the antioxidant properties of the product. On the other hand, it effectively controls the generation of harmful substances during the fermentation process, so that the product has both good flavor and taste, as well as higher nutritional and health value and food safety. Detailed Implementation

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] The Lactobacillus plantarum in the following examples has the accession number CICC 25125 and was selected from the China Industrial Microbial Culture Collection Center.

[0028] The Lactobacillus short-lived in the following examples has the accession number CICC 24450 and was selected from the China Industrial Microbial Culture Collection Center.

[0029] The yeast used in the following examples is Saccharomyces cerevisiae. ， The accession number is CICC1423, and it was selected from the China Industrial Microbial Culture Collection Center.

[0030] The alkaline protease used in the following examples is 2709 alkaline protease, with a product specification of 1 million u / g, purchased from Nanning Dongheng Huadao Biotechnology Co., Ltd.

[0031] The flavor protease in the following examples was a product with a specification of 30,000 u / g, purchased from Nanning Dongheng Huadao Biotechnology Co., Ltd.

[0032] Example 1

[0033] This invention provides a process for preparing fermented kimchi, comprising the following preparation steps:

[0034] S1: Grind soybean meal into powder and pass it through a 75-mesh sieve. Mix the sieved soybean meal powder with purified water at a weight ratio of 1:7.5 and add it to an enzymatic hydrolysis tank. Stir to form a uniform suspension. First, add 0.25% (by weight) of 2709 alkaline protease to the suspension. Adjust the pH of the system to 8.0 with a 10% sodium hydroxide aqueous solution. While stirring, raise the system temperature to 50°C and maintain this temperature for 2.5 hours of enzymatic hydrolysis. Then, add 0.08% (by weight) of flavor protease to the system, lower the system temperature to 45°C, and continue stirring for 1.5 hours of enzymatic hydrolysis. After the enzymatic hydrolysis is complete, raise the system temperature to 90°C. The enzyme was inactivated at 0℃ for 15 minutes. After inactivation, the system was cooled to 28℃ and the residue was removed by plate and frame filtration with a filter cloth pore size of 0.22μm to obtain soybean meal hydrolysate. The components of glucose, soybean meal hydrolysate, dipotassium hydrogen phosphate, calcium chloride, and purified water were added to a container at a mass ratio of 1:4:0.3:0.5:90. The mixture was stirred at 45 rpm for 12 minutes until all the raw materials were evenly mixed. Then, an 8% citric acid aqueous solution was added to adjust the pH of the system to 5.8 to obtain the flavor base liquid.

[0035] S2: First, add *Lactobacillus plantarum*, *Lactobacillus brevis*, and *Saccharomyces cerevisiae* to purified water at a live cell ratio of 3.0:2.0:1, then add glucose. Stir at 28 rpm at room temperature until the glucose is completely dissolved. Then, incubate the system at 35°C for 25 minutes to activate the bacteria, resulting in a live cell count of 1.0 × 10⁻⁶. 9 A mixed bacterial culture with a concentration of CFU / mL was prepared, with glucose added at 2% of the culture's mass. This mixed bacterial culture was inoculated into the flavor base prepared in step S1 at 2.0% of the flavor base weight. Nitrogen gas was first introduced into the inoculated system for 2.5 minutes to remove oxygen. After nitrogen introduction, the system was sealed, and the temperature was maintained at 28°C. Anaerobic fermentation was carried out with a stirring speed of 18 rpm for 48 hours. The pH of the system was monitored every 12 hours during fermentation. H. When the pH drops to 4.2, add 0.1% of the flavor base liquid weight of glucose to the system. After the anaerobic fermentation is completed, add spices to the system. The amount of spices added is 3% of the flavor base liquid weight. The spices are composed of 3.0 parts dried chili segments, 5.0 parts minced garlic, 1.5 parts ginger slices, and 0.3 parts star anise powder. Control the dissolved oxygen content of the system at 2%, the temperature at 22℃, and the stirring speed at 18 rpm for micro-aerobic aroma-enhancing fermentation. The fermentation time is 24 hours to obtain the flavor fermentation base liquid.

[0036] S3: Add carrots to the flavor fermentation base liquid prepared in S2 at a weight ratio of 1.1:1 for vegetables to flavor fermentation base liquid. Then add salt at a weight of 1.5% of the flavor fermentation base liquid and stir until the salt is completely dissolved and evenly mixed with the vegetables and flavor fermentation base liquid. Then place the system in a 20°C environment for static soaking treatment for 24 hours. During the soaking period, stir once every 1.5 hours at a stirring speed of 15 rpm for 2 minutes each time. After soaking, the seasoned kimchi is obtained. Pack the seasoned kimchi into packaging bags and pasteurize. After sterilization, the fermented kimchi is obtained.

[0037] Example 2

[0038] This invention provides a process for preparing fermented kimchi, comprising the following preparation steps:

[0039] S1: Grind soybean meal into powder and pass it through an 80-mesh sieve. Mix the sieved soybean meal powder with purified water at a weight ratio of 1:8 and add it to an enzymatic hydrolysis tank. Stir to form a uniform suspension. First, add 0.3% (by weight) of 2709 alkaline protease to the suspension. Adjust the pH of the system to 8.2 with a 10% sodium hydroxide aqueous solution. While stirring, raise the system temperature to 52.5℃ and maintain this temperature for 2.75 hours of enzymatic hydrolysis. Then, add 0.1% (by weight) of flavor protease to the system and lower the system temperature to 47.5℃. Continue stirring and enzymatic hydrolysis for another 1.75 hours. After enzymatic hydrolysis, raise the system temperature to 92.5℃. The enzyme was incubated for 17.5 min to inactivate it. After inactivation, the system was cooled to 30°C and the residue was removed by plate and frame filtration with a filter cloth pore size of 0.335 μm to obtain soybean meal enzymatic hydrolysate. The glucose, soybean meal enzymatic hydrolysate, dipotassium hydrogen phosphate, calcium chloride and purified water were added to a container at a mass ratio of 1:4.5:0.4:0.6:100. The mixture was stirred at 50 rpm for 13.5 min until all raw materials were mixed evenly. Then, a 10% citric acid aqueous solution was added to adjust the pH of the system to 6.0 to obtain the flavor base liquid.

[0040] S2: First, add *Lactobacillus plantarum*, *Lactobacillus brevis*, and *Saccharomyces cerevisiae* to purified water at a live cell ratio of 3.1:2.1:1, then add glucose. Stir at 30 rpm at room temperature until the glucose is completely dissolved. Then, incubate the system at 36°C for 30 minutes to activate the bacteria, resulting in a live cell count of 1.2 × 10⁻⁶. 9A mixed bacterial culture with a concentration of CFU / mL was prepared, with glucose added at 4% of the culture's mass. This mixed bacterial culture was inoculated into the flavor base liquid prepared in step S1 at 2.5% of the flavor base liquid's weight. Nitrogen gas was first introduced into the inoculated system for 3.0 min to remove oxygen. After nitrogen introduction, the system was sealed, and the temperature was maintained at 29°C. Anaerobic fermentation was carried out with a stirring speed of 20 rpm for 50 h. The pH of the system was monitored every 12 h during fermentation. When the pH drops to 4.2, 0.12% of the flavor base liquid weight of glucose is added to the system. After the anaerobic fermentation is completed, spices are added to the system. The amount of spices added is 4% of the flavor base liquid weight. The spices consist of 3.5 parts dried chili segments, 5.5 parts minced garlic, 1.75 parts ginger slices, and 0.4 parts star anise powder. The dissolved oxygen content of the system is controlled at 2.5%, the temperature at 23.5℃, and the stirring speed at 20 rpm. Micro-aerobic aroma-enhancing fermentation is carried out for 26 hours to obtain the flavor fermentation base liquid.

[0041] S3: Add white radish to the flavor fermentation base liquid prepared in S2 at a weight ratio of 1.2:1 for vegetables to flavor fermentation base liquid. Then add salt at a weight of 1.75% of the flavor fermentation base liquid and stir until the salt is completely dissolved and evenly mixed with the vegetables and flavor fermentation base liquid. Then place the system in a 21°C environment for static soaking treatment for 30 hours. During the soaking period, stir once every 1.75 hours at a stirring speed of 17.5 rpm for 2.5 minutes each time. After soaking, the seasoned kimchi is obtained. Pack the seasoned kimchi into packaging bags and pasteurize. After sterilization, the fermented kimchi is obtained.

[0042] Example 3

[0043] This invention provides a process for preparing fermented kimchi, comprising the following preparation steps:

[0044] S1: Grind soybean meal into powder and pass it through an 85-mesh sieve. Mix the sieved soybean meal powder with purified water at a weight ratio of 1:8.5 and add it to an enzymatic hydrolysis tank. Stir to form a uniform suspension. First, add 0.35% (by weight) of 2709 alkaline protease to the suspension. Adjust the pH of the system to 8.5 with a 10% sodium hydroxide aqueous solution. While stirring, raise the system temperature to 55°C and maintain this temperature for 3 hours of enzymatic hydrolysis. Then, add 0.12% (by weight) of flavor protease to the system, lower the system temperature to 50°C, and continue stirring for 2 hours of enzymatic hydrolysis. After the enzymatic hydrolysis is complete, raise the system temperature to 95°C and maintain this temperature for 3 hours. Enzyme inactivation was performed at a constant temperature for 20 minutes. After enzyme inactivation, the system was cooled to 32°C and the residue in the system was removed by plate and frame filtration with a filter cloth pore size of 0.45 μm to obtain soybean meal enzymatic hydrolysate. The glucose, soybean meal enzymatic hydrolysate, dipotassium hydrogen phosphate, calcium chloride, and purified water were added to a container at a mass ratio of 1:5.0:0.5:0.8:110. The mixture was stirred at 55 rpm for 15 minutes until all raw materials were evenly mixed. Then, a 12% citric acid aqueous solution was added to adjust the pH of the system to 6.2 to obtain the flavor base liquid.

[0045] S2: First, combine *Lactobacillus plantarum*, *Lactobacillus short-lived*, and brewer's bacteria. yeast Add the live bacteria to purified water at a ratio of 3.2:2.2:1, then add glucose. Stir at 32 rpm at room temperature until the glucose is completely dissolved. Then, incubate the system at 37°C for 35 minutes to activate the bacteria, resulting in a live bacteria count of 1.5 × 10⁻⁶. 9 A mixed bacterial culture with a concentration of CFU / mL was prepared, with glucose added at 5% of the culture's mass. This mixed bacterial culture was inoculated into the flavor base liquid prepared in step S1 at 3.0% of the flavor base liquid's weight. Nitrogen gas was first introduced into the inoculated system for 3.5 minutes to remove oxygen. After nitrogen introduction, the system was sealed, and the temperature was maintained at 30°C. Anaerobic fermentation was carried out with a stirring speed of 22 rpm for 54 hours. The pH of the system was monitored every 12 hours during fermentation. H. When the pH drops to 4.2, add 0.15% of the flavor base liquid weight of glucose to the system. After the anaerobic fermentation is completed, add spices to the system. The amount of spices added is 5% of the flavor base liquid weight. The spices are composed of 4.0 parts dried chili segments, 6.0 parts minced garlic, 2.0 parts ginger slices, and 0.5 parts star anise powder. Control the dissolved oxygen content of the system at 3%, the temperature at 25℃, and the stirring speed at 22 rpm for micro-aerobic aroma-enhancing fermentation. The fermentation time is 28 hours to obtain the flavor fermentation base liquid.

[0046] S3: Add the ground beef to the flavor fermentation base liquid prepared in S2 at a weight ratio of 1.3:1 for vegetables to flavor fermentation base liquid. Then add salt at a weight of 2.0% of the flavor fermentation base liquid and stir until the salt is completely dissolved and evenly mixed with the vegetables and flavor fermentation base liquid. Then place the system in a 22°C environment for static soaking treatment for 45 hours. During the soaking period, stir once every 2 hours at a stirring speed of 20 rpm for 3 minutes each time. After soaking, the seasoned kimchi is obtained. Pack the seasoned kimchi into packaging bags and pasteurize. After sterilization, the fermented kimchi is obtained.

[0047] Example 4

[0048] Compared with Example 1, in this embodiment, the "flavor protease" in the preparation of soybean meal enzymatic hydrolysate is replaced with an equal mass of "2709 alkaline protease". The remaining steps and parameters are the same, and will not be repeated in this embodiment. Finally, fermented kimchi is obtained.

[0049] Example 5

[0050] Compared with Example 1, this embodiment replaces "adding *Lactobacillus plantarum*, *Lactobacillus brevis*, and *Saccharomyces cerevisiae* to purified water at a live count ratio of 3.0:2.0:1" in the preparation of the mixed bacterial solution with "adding *Lactobacillus plantarum* and *Lactobacillus brevis* to purified water at a live count ratio of 3.0:2.0". All other steps and parameters are the same, and will not be repeated in this embodiment. The final product is fermented kimchi.

[0051] Example 6

[0052] Compared with Example 1, this embodiment replaces the step of "adding *Lactobacillus plantarum*, *Lactobacillus brevis*, and *Saccharomyces cerevisiae* to purified water in a live cell ratio of 3.0:2.0:1" in the preparation of the mixed bacterial solution with "using only *Saccharomyces cerevisiae*". ， "Add the brewing yeast to the purified water." The remaining steps and parameters are the same, and will not be repeated in this embodiment. Finally, fermented kimchi is obtained.

[0053] Example 7

[0054] Compared with Example 1, in this embodiment, the flavor fermentation base liquid prepared in S2 is sealed and stored for 30 days, and then used for the vegetable soaking process in step S3 according to the predetermined parameters of Example 1. The remaining steps and parameters are the same, and will not be repeated in this comparative example. Finally, fermented kimchi is obtained.

[0055] Comparative Example 1

[0056] Compared with Example 1, in this comparative example, the "soybean meal enzymatic hydrolysate" in step S1 is replaced with an equal mass of "unenzymatically hydrolyzed soybean meal slurry". All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, fermented kimchi is obtained.

[0057] The unenzymatically hydrolyzed soybean meal slurry was prepared as follows: Soybean meal was pulverized and passed through a 75-mesh sieve. The sieved soybean meal powder was mixed with purified water at a weight ratio of 1:7.5 and added to an enzymatic hydrolysis tank. The mixture was stirred to form a uniform suspension. The pH of the suspension was adjusted to 8.0 with a 10% sodium hydroxide aqueous solution. While stirring, the temperature of the suspension was raised to 50°C and kept at that temperature for 2.5 hours. The system temperature was then lowered to 45°C and stirring was continued for 1.5 hours. The system temperature was then raised to 90°C and kept at that temperature for 15 minutes. After completion, the system was cooled to 28°C and the residue in the system was removed by plate and frame filtration with a filter cloth pore size of 0.22 μm to obtain the unenzymatically hydrolyzed soybean meal slurry.

[0058] Comparative Example 2

[0059] Compared with Example 1, this comparative example differs only in that after completing anaerobic fermentation in step S2, the original microaerobic aroma-enhancing fermentation was replaced with anaerobic fermentation (no oxygen was introduced, the temperature was 22°C, the stirring speed was 18 rpm, and the fermentation time was 22 hours). All other steps and parameters are the same, and will not be repeated in this comparative example. The final product is fermented kimchi.

[0060] Comparative Example 3

[0061] Compared with Example 1, this comparative example omits the process of "preparing the flavor fermentation base liquid first and then soaking the vegetables". In step S2, when the mixed bacterial liquid is inoculated for anaerobic fermentation, carrots are added simultaneously so that the carrots participate in the anaerobic fermentation and micro-aerobic flavor-enhancing fermentation throughout the process. Step S3 omits the static soaking treatment. The remaining steps and parameters are the same, and will not be repeated in this comparative example. Finally, fermented kimchi is obtained.

[0062] The process parameters for step S1 are completely consistent with those in Example 1, without any adjustments. The specific operation procedures and related parameter changes for steps S2 and S3 are as follows:

[0063] S2: First, add *Lactobacillus plantarum*, *Lactobacillus brevis*, and *Saccharomyces cerevisiae* to purified water at a live cell ratio of 3.0:2.0:1, then add glucose. Stir at 28 rpm at room temperature until the glucose is completely dissolved. Then, incubate the system at 35°C for 25 minutes to activate the bacteria, resulting in a live cell count of 1.0 × 10⁻⁶. 9A mixed bacterial culture with a concentration of CFU / mL was prepared, with glucose added at 2% of the culture's mass. The prepared mixed bacterial culture was inoculated into the flavor base prepared in step S1 at 2.0% of the flavor base weight. Carrots were added to the inoculated flavor base first, in the same amount as in Example 1. Nitrogen gas was purged into the system for 2.5 minutes to remove oxygen. After purging, the system was sealed, and the temperature was maintained at 28°C. Anaerobic fermentation was carried out at a stirring speed of 18 rpm for 45 hours. The pH of the system was monitored every 12 hours. When the pH dropped to 4.2, 0.1% of the flavor base liquid weight of glucose was added to the system. After the anaerobic fermentation was completed, spices were added to the system. The amount of spices added was 3% of the flavor base liquid weight. The spices consisted of 3.0 parts dried chili segments, 5.0 parts minced garlic, 1.5 parts ginger slices, and 0.3 parts star anise powder. The dissolved oxygen content of the system was controlled at 2%, the temperature at 22℃, and the stirring speed at 18 rpm. Micro-aerobic aroma-enhancing fermentation was carried out for 22 hours to obtain the flavor fermentation mixture.

[0064] S3: Add salt to the flavor fermentation mixture, the amount of salt added is the same as in Example 1, stir until the salt is completely dissolved and mixed evenly with the flavor fermentation mixture to obtain seasoned kimchi. Pack the seasoned kimchi into packaging bags and perform pasteurization. After sterilization, fermented kimchi is obtained.

[0065] Comparative Example 4

[0066] Compared with Example 1, this comparative example omits the process of "preparing the flavor fermentation base liquid first and then soaking the vegetables". In step S2, when the mixed bacterial solution is inoculated for anaerobic fermentation, carrots are added simultaneously, so that carrots participate in the entire process of anaerobic fermentation and micro-aerobic aroma-enhancing fermentation. The anaerobic fermentation time is changed from 48h to 16h, and the micro-aerobic aroma-enhancing fermentation time is changed from 24h to 8h. The total time for anaerobic fermentation and micro-aerobic aroma-enhancing fermentation is omitted in step S3, and the static soaking treatment is the same. All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, fermented kimchi is obtained.

[0067] The fermented kimchi prepared in Examples 1-7 and the fermented kimchi prepared in Comparative Examples 1-4 were tested, and the results are recorded in Table 1.

[0068] Sensory evaluation of fermented kimchi was conducted in accordance with ISO 24220:2023. Ten professional evaluators were selected to independently score the color, crispness, and flavor of the kimchi, and the average value was taken (retaining one decimal place).

[0069] The scoring criteria are as follows: Color: 10 for the color of fresh raw materials, 0 for dark brown; Crispness: 10 for crispness, 0 for softness; Flavor: 10 for moderate sour, salty and spicy flavor, 0 for strong raw flavor, no pickled flavor or excessive sourness.

[0070] The nitrite content and amino acid nitrogen content of fermented pickled vegetables were tested in accordance with the national standard GB 5009.33.

[0071] The DPPH free radical scavenging rate of fermented kimchi was tested according to the national standard GB / T 39100-2020.

[0072] Table 1: Sensory evaluation and physicochemical test results of fermented kimchi

[0073]

[0074] According to the data in Table 1, the fermented kimchi prepared in Examples 1-3 has a bright color, a crisp and tender texture, and an excellent flavor. It also has a strong antioxidant capacity, which can effectively delay oxidation and deterioration during storage, and prevent the color from darkening and the flavor from deteriorating. It performs well in all aspects.

[0075] A comparison of Examples 1 and 4 shows that the two-step enzymatic hydrolysis process using alkaline protease and flavor protease is crucial to the quality of the soybean meal hydrolysate. Example 4 used only alkaline protease for single-step hydrolysis, without the two-step process. The resulting kimchi failed to achieve the sensory performance of Example 1, and its nutrient generation efficiency and the antioxidant capacity of the final product were also lower. This indicates that the two-step hydrolysis process can more fully degrade the protein in soybean meal, generating more substances that enhance the flavor and nutrition of the kimchi.

[0076] A comparison of Examples 1 and 5 shows that the addition of brewer's yeast to the mixed bacterial solution is of great significance for improving the quality of fermented kimchi. Example 5, which did not add brewer's yeast and only used two types of lactic acid bacteria to construct the mixed bacterial solution, produced kimchi that was significantly inferior to Example 1 in terms of flavor richness and acid-aroma harmony, and also had lower antioxidant capacity. This result demonstrates that brewer's yeast and lactic acid bacteria can form a good synergistic effect, not only optimizing the flavor characteristics of kimchi but also enhancing its antioxidant properties. Excellent antioxidant capacity can delay oxidative deterioration of kimchi during storage, avoiding problems such as darkening of color and flavor degradation caused by oxidation. This is an important process design in this invention to achieve excellent overall performance of kimchi, reflecting the innovation of this invention in the selection of bacterial agent formulation.

[0077] A comparison of Examples 1 and 6 shows that Example 6 uses only brewer's yeast to construct a single-strain inoculum, lacking Lactobacillus plantarum and Lactobacillus brevis. The resulting kimchi has a much weaker and less harmonious sour and aromatic flavor than Example 1. This is because lactic acid bacteria are key to generating basic acids and establishing the sour and aromatic base, and yeast alone cannot create a rich and harmonious flavor. In terms of food safety, the nitrite content is higher because the role of lactic acid bacteria in inhibiting harmful bacteria is difficult for yeast to replace. Nutritionally, the amino acid nitrogen content is lower because the role of lactic acid bacteria in degrading proteins and promoting nutrient production cannot be achieved by yeast alone.

[0078] A comparison of Example 1 and Example 7 shows that the flavor fermentation base liquid prepared in advance has a stable flavor system and can maintain a consistent flavor base after storage and use, effectively avoiding flavor fluctuations caused by the binding of vegetables and fermentation in traditional processes. At the same time, the base liquid can be prepared and stored in batches in advance. When an order is placed, there is no need to wait for the preparation process of the fermentation base liquid. The vegetables can simply be soaked in the ready-made base liquid, which greatly shortens the processing start-up cycle and fundamentally solves the problem of untimely order delivery caused by the long fermentation time required for the fermentation container to surround the vegetables and the slow processing response in traditional processes.

[0079] A comparison of Example 1 and Comparative Example 1 shows that soybean meal enzymatic hydrolysate plays a crucial supporting role in the overall performance of fermented kimchi. Comparative Example 1, which did not add soybean meal enzymatic hydrolysate and used other substances instead, produced kimchi that was significantly inferior to that of Example 1 in terms of color brightness, crispness retention, and flavor richness and harmony. It also showed a significant difference in nutrient accumulation and overall antioxidant capacity. This comparison fully demonstrates that soybean meal enzymatic hydrolysate not only effectively improves the sensory quality of kimchi but also enhances its nutritional level and antioxidant activity, making it a vital ingredient in this invention for ensuring the excellent overall performance of the kimchi.

[0080] A comparison of Example 1 and Comparative Example 2 shows that the microaerobic aroma-enhancing fermentation step is indispensable for optimizing the flavor and quality of fermented kimchi. Comparative Example 2, by omitting microaerobic aroma-enhancing fermentation and only performing anaerobic fermentation, produced kimchi that was significantly inferior to that of Example 1 in terms of flavor complexity and aroma intensity, and also exhibited poorer overall sensory harmony. This indicates that microaerobic aroma-enhancing fermentation can promote the full release and transformation of spice flavor substances, while further optimizing the flavor system of the kimchi, resulting in superior sensory quality of the final product. This confirms the necessity and inventiveness of the two-step fermentation process of "anaerobic fermentation + microaerobic aroma-enhancing fermentation" in this invention.

[0081] A comparison of Example 1 and Comparative Example 3 shows that adding vegetables simultaneously during anaerobic fermentation with the mixed bacterial solution allows the vegetables to participate in both anaerobic and microaerobic flavor-enhancing fermentation throughout the process. This process deeply integrates vegetables with the fermentation process. However, the components of the vegetables themselves can interfere with the metabolic rhythm of the microorganisms, leading to differences in the flavor compounds produced in different batches of kimchi, making it impossible to achieve a uniform and stable flavor quality. Furthermore, the vegetables require continuous fermentation throughout the entire process, and the fermentation container needs constant adjustment based on the state of the vegetables. This results in a long overall fermentation cycle, requiring the simultaneous fermentation of vegetables and the base solution to be restarted from scratch when an order arrives, making it difficult to quickly respond to order demands and potentially leading to untimely delivery.

[0082] A comparison of Example 1 and Comparative Example 4 reveals that Comparative Example 4 also employs a process where vegetables participate in the entire fermentation process, and deliberately reduces the total time of anaerobic and microaerobic flavor-enhancing fermentation to shorten the cycle. However, after shortening the fermentation time, the microorganisms failed to fully metabolize and generate flavor substances, which not only further exacerbated the problem of bland flavor and insufficient complexity, but also resulted in poorer flavor stability. At the same time, even with the shortened time, the vegetables still need to be bound to the fermentation process, making it impossible to prepare the core flavor system in advance. This failed to solve the problem of slow processing response in traditional processes, and it was still difficult to meet the demand for rapid order fulfillment. Moreover, the contradiction between flavor and fermentation efficiency became more prominent.

[0083] The above description is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. A process for the preparation of a fermented kimchi, characterized in that, The preparation steps include the following: S1: Add glucose, soybean meal hydrolysate, dipotassium hydrogen phosphate and calcium chloride to purified water and stir well. Add citric acid aqueous solution to adjust the pH to obtain flavor base liquid. S2: Inoculate the mixed bacterial solution into the flavor base liquid for anaerobic fermentation. After anaerobic fermentation, add spices, maintain a micro-aerobic environment, and carry out micro-aerobic aroma-enhancing fermentation to obtain the flavor fermentation base liquid. S3: Add vegetables to the flavor fermentation base liquid, add salt and stir well, let stand and soak to obtain seasoned kimchi, pack the seasoned kimchi into bags, pasteurize to obtain fermented kimchi. The preparation method of the mixed bacterial solution is as follows: *Lactobacillus plantarum*, *Lactobacillus brevis*, and *Saccharomyces cerevisiae* are added to purified water at a live cell ratio of (3.0-3.2):(2.0-2.2):

1. Glucose is added, and the mixture is stirred at room temperature until the glucose dissolves. After standing and activation, the mixed bacterial solution is obtained, with a live cell count of 1.0 × 10⁻⁶. 9 CFU / mL -1.5×10 9 CFU / mL; The preparation method of the soybean meal enzymatic hydrolysate is as follows: Take soybean meal, grind it and sieve it. Mix the sieved soybean meal powder with pure water and put it into an enzymatic hydrolysis tank and stir it into a uniform suspension. First, add alkaline protease, adjust the pH, stir and heat to hydrolyze. Then add flavor protease, cool down and continue stirring to hydrolyze. After the enzymatic hydrolysis is completed, heat the system to inactivate the enzyme. After cooling, filter it with a plate and frame filter to remove the residue and obtain soybean meal enzymatic hydrolysate. The product specification of the flavor protease is 30,000 u / g; In step S2, during anaerobic fermentation, nitrogen gas is first introduced into the system for 2.5-3.5 minutes to remove oxygen. After sealing, the temperature is maintained at 28℃-30℃, the stirring speed is 18-22 rpm, and the fermentation time is 48-54 hours. During this period, the pH is monitored every 12 hours. When the pH drops to 4.2, 0.1%-0.15% of the flavor base liquid weight of glucose is added. During microaerobic aroma-enhancing fermentation, the dissolved oxygen content of the system is controlled at 2%-3%, the temperature is 22℃-25℃, the stirring speed is 18-22 rpm, and the fermentation time is 24-28 hours.

2. The process for preparing fermented kimchi according to claim 1, wherein, In the preparation of the soybean meal enzymatic hydrolysate: soybean meal is pulverized and passed through a 75-85 mesh sieve. The sieved soybean meal powder is mixed with purified water at a weight ratio of 1:(7.5-8.5). The amount of alkaline protease added is 0.25%-0.35% of the weight of soybean meal powder. The pH is adjusted by sodium hydroxide aqueous solution and maintained at 8.0-8.

5. After heating to 50℃-55℃, enzymatic hydrolysis is carried out for 2.5-3 hours. The amount of flavor protease added is 0.08%-0.12% of the weight of soybean meal powder. After cooling to 45℃-50℃, enzymatic hydrolysis is continued for 1.5-2 hours. When inactivating the enzyme, the temperature is raised to 90℃-95℃ and kept at that temperature for 15-20 minutes. After cooling to 28℃-32℃, the mixture is filtered. The pore size of the filter cloth in the plate and frame filter is 0.22μm-0.45μm.

3. The process for preparing fermented kimchi according to claim 1, wherein the fermentation is carried out at a temperature of 10 to 30°C for 1 to 10 days. In the preparation of the mixed bacterial solution: the amount of glucose added to the mixed bacterial solution is 2%-5% of the mass of the mixed bacterial solution; the stirring speed is 28rpm-32rpm, and after stirring until the glucose is completely dissolved, it is allowed to stand and activate at 35℃-37℃ for 25min-35min.

4. The process for preparing kimchi by fermentation according to claim 1, 2 or 3, wherein, In step S1, the mass ratio of glucose, soybean meal enzymatic hydrolysate, dipotassium hydrogen phosphate, calcium chloride, and purified water is 1:(4.0-5.0):(0.3-0.5):(0.5-0.8):(90-110); the mass concentration of the citric acid aqueous solution is 8%-12%, and the pH of the system is stabilized at 5.8-6.2 after adjustment; the stirring speed is 45rpm-55rpm, and the stirring time is 12min-15min.

5. The process for preparing a fermented kimchi according to claim 1, 2 or 3, wherein, In step S2, the inoculation amount of the mixed bacterial solution is 1.5%-3.0% of the weight of the flavor base liquid; the amount of spices added is 3%-5% of the weight of the flavor base liquid, and the raw materials of the spices, by weight, are 3.0-4.0 parts of dried chili segments, 5.0-6.0 parts of minced garlic, 1.5-2.0 parts of ginger slices, and 0.3-0.5 parts of star anise powder.

6. The process for preparing kimchi by fermentation according to claim 1, 2 or 3, wherein, In step S3, the weight ratio of vegetables to flavor fermentation base liquid is (1.1-1.3):1; the amount of salt added is 1.5%-2.0% of the weight of flavor fermentation base liquid; the static soaking temperature is 20℃-22℃, the soaking time is 24h-45h, and the mixture is stirred once every 1.5h-2h for 2min-3min each time, with a stirring speed of 15rpm-20rpm.

7. The process for preparing a fermented kimchi according to claim 1, 2 or 3, wherein, The vegetables mentioned are one or more of carrots, white radishes, and ground ox.

8. Fermented kimchi prepared by a process according to any one of claims 1-7.

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