Low-salt leaf mustard fermented food and fermentation method thereof

Abstract

The invention relates to the technical field of fermented foods, and discloses a low-salt leaf mustard fermented food and a fermentation method thereof, the method comprises yogurt fermentation and leaf mustard pretreatment and salting processes, and the method also comprises the steps of preparation of a composite fermentation broth and final mixed fermentation. A low-salt formula is adopted, the salt content in the mustard fermented food is greatly reduced, the requirements of hypertension patients and crowds needing low-salt diet are met, and meanwhile the risk of cardiovascular diseases is reduced. By introducing pectin or isomaltulose for secondary fermentation and utilizing lactobacillus plantarum and bacillus aceticus to ferment the vegetable juice, the unique flavor of traditional mustard fermented food is reserved, and the nutritional value and safety of the product are improved.

Description

Technical Field

[0001] The invention relates to the technical field of fermented foods, and in particular to a low-salt mustard fermented food and a fermentation method thereof. Background Art

[0002] Mustard greens, as a widely grown vegetable, are not only loved for their unique spicy taste, but also highly praised for their high nutritional value. It is rich in vitamin C, vitamin K, calcium, iron and other nutrients, and has a positive effect on enhancing human immunity and promoting bone health. However, in traditional food culture, mustard greens are often processed into various fermented foods, such as sauerkraut. These foods are deeply loved by people for their unique flavor, but they usually contain high salt content, which is undoubtedly a limitation for patients with hypertension and other people who need a low-salt diet.

[0003] In order to meet the modern people's pursuit of healthy diet and retain the unique flavor of traditional food, it is particularly important to develop a low-salt fermented mustard food. The research and development of low-salt fermented mustard food can not only provide more dietary options for patients with hypertension, but also help people reduce sodium intake, thereby reducing the risk of cardiovascular disease. In addition, the promotion of low-salt food can also help improve people's overall dietary structure and improve the health level of the public.

[0004] In short, the research and development of low-salt fermented mustard foods not only has important practical significance, but also can promote innovation and upgrading of the traditional food industry and provide consumers with more healthy and delicious choices. Summary of the invention

[0005] In view of this, the present invention proposes a low-salt fermented mustard food and a fermentation method thereof. In the process of developing the low-salt fermented mustard food, other seasonings are added to enhance the flavor of the food, thereby reducing the salt content of the product without damaging the taste. At the same time, through scientific experiments and research, it is ensured that the low-salt fermented mustard food can meet the requirements of food safety and nutritional balance while maintaining the traditional flavor.

[0006] The present invention provides a fermentation method for a low-salt mustard fermented food, comprising:

[0007] Select plant milk or milk raw material, add mixed bacteria and 0.5-1% glucose, and let it stand for primary fermentation until the yogurt solidifies; then add pectin or isomaltulose to continue secondary fermentation, and refrigerate the secondary fermented yogurt to mature to obtain yogurt raw material;

[0008] Remove roots and leaves of fresh mustard greens and slice them, soak them in ice water for 5-10 minutes, and then refrigerate and soak the mustard greens in a solution containing 2% salt and 0.5% citric acid; then enzymatically hydrolyze the mustard greens with 0.1% pectinase at 25±2°C to soften the fibers, thus completing the mustard greens pretreatment;

[0009] The mustard greens after pretreatment are salted in two steps, in the first step, 2% salt is added and left to stand for 12 hours; in the second step, 2% salt is added again and salted for 12 hours to obtain salted mustard greens;

[0010] Fresh vegetables are squeezed to obtain vegetable juice, glucose and soy protein powder are added to the vegetable juice, and Lactobacillus plantarum and Acetobacter acetobacter are inoculated, and the mixture is allowed to stand for fermentation to obtain fermented vegetable juice; the fermented vegetable juice is mixed with yogurt raw materials in a ratio of 3:1, and rice vinegar and spice juice are added to obtain a composite fermentation liquid;

[0011] The composite fermentation liquid and the salted mustard are mixed in a mass ratio of 1:1.5-2, and 1-2% glucose and 2-3% liquor are added based on the total weight of the composite fermentation liquid and the salted mustard; clean water is added to control the salt concentration in the fermentation mixture to be 3-4%; the mixture is sealed and placed in a jar, and fermented at 25-30° C. for 3-5 days, during which the mixture is stirred once a day to ensure uniform fermentation; after the fermentation is completed, the low-salt fermented mustard food is obtained.

[0012] Preferably, before the primary fermentation, the vegetable milk or milk raw material is heated to at least 85°C, maintained for at least 30 minutes, and then cooled to 40-42°C;

[0013] The secondary fermentation is at 10-15°C for at least 12 hours.

[0014] Preferably, the mixed bacterial species include Streptococcus thermophilus, Lactobacillus bulgaricus and Lactococcus lactis.

[0015] Preferably, the mustard greens after pretreatment are salted in two steps, and ginger slices and garlic slices are added during the salting process.

[0016] Preferably, the fresh vegetables are celery, carrots and cabbage.

[0017] Preferably, the method for preparing the spice juice comprises:

[0018] The preparation method of the spice juice is as follows: after star anise, cinnamon, cloves, prickly ash, bay leaves and cumin are mixed, water of ten times the total weight is added and heated to boiling, and then boiled for about 30 minutes. After boiling, the residue is filtered out, and 1-2% of sugar and 0.5% of salt of the total weight of the liquid are added to obtain the spice juice.

[0019] Preferably, the weight ratio of star anise, cinnamon, cloves, pepper, bay leaf and cumin is 4:6:1:4:2:3.

[0020] Preferably, when glucose and soy protein powder are added to the vegetable juice, the added amount of glucose is 2% by weight of the vegetable juice, and the added amount of soy protein powder is 1% by weight of the vegetable juice.

[0021] Preferably, the plant milk is oat milk.

[0022] The present invention also provides a low-salt mustard fermented food, which is obtained by fermenting the low-salt mustard fermented food using the above-mentioned fermentation method for low-salt mustard fermented food.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention adopts a low-salt formula, significantly reduces the salt content in fermented mustard food, meets the needs of patients with hypertension and people who need a low-salt diet, and reduces the risk of cardiovascular disease. By introducing pectin or isomaltulose for secondary fermentation, and using plant lactobacillus and acetic acid bacteria to ferment vegetable juice, the present invention not only retains the unique flavor of traditional fermented mustard food, but also improves the nutritional value and safety of the product. The fermentation process of the present invention ensures the stability and uniformity of the food fermentation process through multi-step control, including primary fermentation, secondary fermentation, vegetable juice fermentation and final mixed fermentation, thereby improving the quality and taste of the product. In addition, by adding ginger slices and garlic slices during the salting process, and incorporating a variety of spices into the spice juice, the fermented mustard food of the present invention adds a rich flavor level, which caters to consumers' pursuit of diversified tastes. In particular, oat milk is preferably used as a raw material, which provides more choices for consumers with lactose intolerance and further broadens the market scope of the product. The low-salt fermented mustard food of the present invention has an excellent shelf life while maintaining the traditional flavor, is easy to store and transport, and is conducive to industrial production.

[0025] In summary, the fermented food of the present invention not only provides consumers with healthy choices, but also promotes the innovation and upgrading of the traditional food industry, and helps promote the sustainable development of related industries. DETAILED DESCRIPTION

[0026] The exemplary embodiments of the present disclosure will be described in more detail below. Although the exemplary embodiments of the present disclosure are shown below, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present disclosure and to be able to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0027] The present invention provides a fermentation method for low-salt mustard fermented food, comprising:

[0028] Step 1: Multi-stage fermentation of yogurt

[0029] 1. Preparation of yogurt culture medium: Select plant milk or milk raw materials, heat to 85°C, maintain for at least 30 minutes to further improve the lactose conversion efficiency, and cool to 40-42°C. Plant milk is oat milk, and the preparation method is to mix oats and clean water in a weight ratio of 1:3-4, squeeze and filter to obtain oat milk.

[0030] 2. Primary fermentation of yogurt: Add thermophilic Streptococcus, Bulgarian Lactobacillus and Lactococcus lactis mixed strains, and add a small amount of glucose (0.5-1%). Let it stand and ferment for 8 hours until the yogurt solidifies.

[0031] 3. Secondary fermentation: Add a small amount of pectin or isomaltulose to increase the fermentation depth of the yogurt. Continue the secondary fermentation for 12 hours at low temperature (10-15℃) to obtain a yogurt with a stronger flavor.

[0032] 4. Late maturation: The secondary fermented yogurt is refrigerated and matured for 24 hours to stabilize its flavor and enrich it with lactic acid bacteria.

[0033] Step 2: Double pretreatment of mustard greens

[0034] 1. Wash and slice: Choose fresh mustard greens, remove the roots and leaves, and cut into thin slices. Soak in low-temperature ice water for 5-10 minutes to remove some impurities and excess bitterness.

[0035] 2. Low temperature sterilization treatment: Prepare a solution containing 2% salt and 0.5% citric acid, and soak the mustard slices in the solution for 2 hours in the refrigerator to reduce bacteria and keep the green color.

[0036] 3. Enzymatic treatment: Use low concentration pectinase (concentration 0.1%) to enzymatically treat mustard for 2 hours at 25°C to soften the fiber and improve the fermentation effect and texture.

[0037] Step 3: Salted mustard greens (low-salt flavor layering)

[0038] 1. Two-stage salting: The pretreated mustard is salted in two steps. In the first stage, 2% salt is added and left to stand for 12 hours. In the second stage, another 2% salt is added and salted for 12 hours to gradually draw out the moisture and bitterness of the mustard to achieve a low-salt effect.

[0039] 2. Flavor pretreatment: During the salting process, add a small amount of ginger slices and garlic slices to allow the mustard greens to initially absorb the flavor.

[0040] Step 4: Preparation of compound fermented juice

[0041] 1. Vegetable juice fermentation: squeeze the juice from celery, carrots and cabbage, add glucose (2% of the weight of the original vegetable juice) and soy protein powder (1% of the weight of the original vegetable juice), inoculate with Lactobacillus plantarum and a small amount of Acetobacter, let it stand and ferment for 48 hours to obtain fermented vegetable juice with a strong sour taste.

[0042] 2. Composite fermentation liquid: Mix the fermented vegetable juice with yogurt in a ratio of 3:1, and add a small amount of rice vinegar and spice juice to improve the composite flavor. The preparation method of the spice juice is to mix star anise, cinnamon, cloves, pepper, bay leaves, and cumin in a weight ratio of 4:6:1:4:2:3, add water ten times the total weight and heat to boiling, cook for about 30 minutes, filter and remove the residue after cooking, add 1-2% sugar and 0.5% salt of the total weight of the liquid, and obtain the spice juice.

[0043] Step 5: Fermentation (multi-layered flavor fusion)

[0044] 1. Mixing fermentation liquid and mustard: Mix the composite fermentation liquid and salted mustard in a mass ratio of 1:1.5-2, add a small amount of glucose (1-2%) to promote fermentation, and add 30% alcohol liquor (2-3%) to inhibit bacteria.

[0045] 2. Control of salt concentration: According to the water content of the fermentation liquid and the salt content of the salted mustard, add appropriate amount of clean water to control the salt concentration in the fermentation mixture at 3-4%.

[0046] 3. Seal the jar for fermentation: Seal the jar and let it ferment at 25-30℃ for 3-5 days. Stir once a day to ensure even fermentation.

[0047] 4. Late refrigeration maturation: After fermentation is completed, the fermented mustard is refrigerated and matured at 4°C for 7 days to stabilize the flavor and achieve appropriate acidity.

[0048] The technical solution of the present invention is described in detail below through specific embodiments.

[0049] Example 1

[0050] This example adopts the above fermentation method to prepare low-salt fermented mustard food, and optimizes key steps to obtain the best flavor.

[0051] Step 1: Multi-stage fermentation of yogurt

[0052] Yogurt culture preparation: Oat milk was used as the plant milk raw material, heated to 85°C and maintained for 30 minutes, and then cooled to 41°C.

[0053] Primary fermentation of yogurt: inoculate a mixed strain of thermophilic Streptococcus, Bulgarian Lactobacillus and Lactococcus lactis, add 0.7% glucose, and let it ferment for 8 hours.

[0054] Secondary fermentation: Add 0.3% pectin and continue fermentation at 12°C for 14 hours.

[0055] Late maturation: Refrigerate the secondary fermented yogurt for 24 hours.

[0056] Step 2: Double pretreatment of mustard greens

[0057] Clean and slice: Choose fresh mustard greens, remove the roots and leaves, cut into thin slices, and soak in low-temperature ice water for 7 minutes.

[0058] Low temperature sterilization treatment: Soak the mustard slices in a solution containing 2% salt and 0.5% citric acid for 2 hours.

[0059] Enzymatic hydrolysis: The mustard was treated with 0.1% pectinase at 24°C for 2 hours.

[0060] Step 3: Salted mustard greens (low-salt flavor layering)

[0061] Two-stage salting: in the first stage, add 2% table salt and let it stand for 12 hours; in the second stage, add another 2% table salt and let it stand for another 12 hours.

[0062] Flavor pretreatment: Add a small amount of sliced ​​ginger and garlic during the salting process.

[0063] Step 4: Preparation of compound fermented juice

[0064] Vegetable juice fermentation: squeeze the juice from celery, carrots and cabbage, add 2% glucose and 1% soy protein powder, inoculate with Lactobacillus plantarum and a small amount of Acetobacter, and ferment for 48 hours.

[0065] Composite fermentation liquid: Fermented vegetable juice and yogurt are mixed in a ratio of 3:1, and 0.5% of rice vinegar and 0.2% of spice juice are added to the total weight of the vegetable juice and yogurt. The preparation method of the spice juice is to mix star anise, cinnamon, cloves, pepper, bay leaf and cumin in a weight ratio of 4:6:1:4:2:3, add water ten times the total weight, heat to boiling, cook for about 30 minutes, filter and remove residue after cooking, add 1-2% of sugar and 0.5% of salt to obtain the spice juice.

[0066] Step 5: Fermentation (multi-layered flavor fusion)

[0067] Mixing the fermentation liquid and mustard: mixing the composite fermentation liquid and the salted mustard in a mass ratio of 1:1.8, and adding 1.5% glucose and 2.5% liquor.

[0068] Salt concentration control: According to the water content of the fermentation liquid and the salt content of the salted mustard, add appropriate amount of clean water to control the salt concentration at 3.5%.

[0069] Sealed jar fermentation: Seal the jar and let it ferment at 28℃ for 4 days, stirring once a day.

[0070] Late refrigerated maturation: After fermentation is completed, the fermented mustard is refrigerated and matured at 4°C for 7 days.

[0071] Through the above steps, the low-salt fermented mustard food we prepared has a unique sweet and sour taste and rich layered flavors, while retaining the nutrients and beneficial microorganisms of the mustard.

[0072] Example 2

[0073] Step 1: Multi-stage fermentation of yogurt

[0074] Yogurt culture medium preparation: Use fresh milk as the milk raw material, heat it to 85℃ and keep it for 30 minutes, and then cool it to 40℃.

[0075] Primary fermentation of yogurt: inoculate a mixed strain of thermophilic Streptococcus, Bulgarian Lactobacillus and Lactococcus lactis, add 0.8% glucose, and let it ferment for 7 hours.

[0076] Secondary fermentation: Add 0.4% isomaltulose and continue fermentation at 14°C for 10 hours.

[0077] Late maturation: Refrigerate the secondary fermented yogurt for 26 hours.

[0078] Step 2: Double pretreatment of mustard greens

[0079] Clean and slice: Choose fresh mustard greens, remove the roots and leaves, cut into thin slices, and soak in low-temperature ice water for 6 minutes.

[0080] Low temperature sterilization treatment: Soak the mustard slices in a solution containing 1.5% salt and 0.6% citric acid for 1.5 hours.

[0081] Enzymatic hydrolysis: The mustard was treated with 0.15% pectinase at 26°C for 2 hours.

[0082] Step 3: Salted mustard greens (low-salt flavor layering)

[0083] Two-stage salting: in the first stage, add 1.5% salt and let it stand for 10 hours; in the second stage, add another 1.5% salt and let it stand for another 10 hours.

[0084] Flavor pre-treatment: Add a small amount of chili flakes and onion flakes during the salting process.

[0085] Step 4: Preparation of compound fermented juice

[0086] Vegetable juice fermentation: squeeze the juice from celery, carrot and cabbage, add 1.5% glucose and 1.2% soy protein powder, inoculate with Lactobacillus plantarum and a small amount of Acetobacter, and ferment for 50 hours.

[0087] Composite fermentation liquid: Fermented vegetable juice and yogurt are mixed in a ratio of 2.5:1, and 0.6% of rice vinegar and 0.3% of spice juice are added based on the total weight of the vegetable juice and yogurt. The preparation method of the spice juice is as follows: star anise, cinnamon, cloves, prickly ash, bay leaves, and fennel are mixed in a weight ratio of 4:6:1:4:2:3, and then ten times of the total weight of water is added and heated to boiling, and then boiled for about 30 minutes, and after boiling, the residue is filtered out, and 1-2% of the total weight of the liquid and 0.5% of salt are added to obtain the spice juice.

[0088] Step 5: Fermentation (multi-layered flavor fusion)

[0089] Mixing the fermentation liquid and mustard: mixing the composite fermentation liquid and the salted mustard in a mass ratio of 1:1.6, and adding 1.8% glucose and 3% liquor.

[0090] Salt concentration control: According to the water content of the fermentation liquid and the salt content of the salted mustard, add appropriate amount of clean water to control the salt concentration at 3.2%.

[0091] Sealed jar fermentation: Seal the jar and let it ferment at 27℃ for 5 days, stirring once a day.

[0092] Late refrigerated maturation: After fermentation is completed, the fermented mustard is refrigerated and matured at 4°C for 8 days.

[0093] Through the steps of Example 2, the low-salt fermented mustard food prepared by us has a unique spicy taste and onion aroma, as well as a good taste and rich nutrients.

[0094] Example 3

[0095] Step 1: Multi-stage fermentation of yogurt

[0096] Yogurt culture preparation: Oat milk was used as the plant milk raw material, heated to 85°C and maintained for 30 minutes, and then cooled to 42°C.

[0097] Primary fermentation of yogurt: inoculate a mixed strain of thermophilic Streptococcus, Bulgarian Lactobacillus and Lactococcus lactis, add 0.8% glucose, and ferment for 10 hours.

[0098] Secondary fermentation: Add 0.4% pectin and continue fermentation at 10°C for 16 hours.

[0099] Late maturation: Refrigerate the secondary fermented yogurt for 24 hours.

[0100] Step 2: Double pretreatment of mustard greens

[0101] Clean and slice: Choose fresh mustard greens, remove the roots and leaves, cut into thin slices, and soak in low-temperature ice water for 10 minutes.

[0102] Low temperature sterilization treatment: Soak the mustard slices in a solution containing 2.5% salt and 0.6% citric acid for 2.5 hours.

[0103] Enzymatic hydrolysis: The mustard was treated with 0.2% pectinase at 26°C for 2.5 hours.

[0104] Step 3: Salted mustard greens (low-salt flavor layering)

[0105] Two-stage salting: in the first stage, add 2.5% salt and let it stand for 14 hours; in the second stage, add another 2.5% salt and let it stand for another 14 hours.

[0106] Flavor pretreatment: Add a small amount of ginger slices and green onion segments during the salting process.

[0107] Step 4: Preparation of compound fermented juice

[0108] Vegetable juice fermentation: squeeze the juice from spinach, carrot and purple cabbage, add 2.5% glucose and 1.2% soy protein powder, inoculate with Lactobacillus plantarum and a small amount of Acetobacter, and ferment for 50 hours.

[0109] Composite fermentation liquid: Fermented vegetable juice and yogurt are mixed in a ratio of 3.5:1, and 0.7% of rice vinegar and 0.3% of spice juice are added based on the total weight of the vegetable juice and yogurt. The preparation method of the spice juice is as follows: star anise, cinnamon, cloves, prickly ash, bay leaves, and fennel are mixed in a weight ratio of 4:6:1:4:2:3, and then ten times of the total weight of water is added and heated to boiling, and then boiled for about 30 minutes, and after boiling, the residue is filtered out, and 1-2% of the total weight of the liquid and 0.5% of salt are added to obtain the spice juice.

[0110] Step 5: Fermentation (multi-layered flavor fusion)

[0111] Mixing the fermentation liquid and mustard: mixing the composite fermentation liquid and the salted mustard in a mass ratio of 1:1.6, and adding 2% glucose and 3% liquor.

[0112] Salt concentration control: According to the water content of the fermentation liquid and the salt content of the salted mustard, add appropriate amount of clean water to control the salt concentration at 3.2%.

[0113] Sealed jar fermentation: Seal the jar and let it ferment at 30℃ for 5 days, stirring once a day.

[0114] Late refrigerated maturation: After fermentation is completed, the fermented mustard is refrigerated and matured at 4°C for 7 days.

[0115] Through the above steps, the low-salt fermented mustard food we prepared has a distinct sweet and sour flavor and rich nutrition, while maintaining the original taste and microbial diversity of the mustard.

[0116] Comparative Example 1

[0117] Step 1: Traditional salting method

[0118] Salted mustard greens: Choose fresh mustard greens, remove the roots and leaves, cut into thin slices, and directly use table salt for salting with a salt concentration of 6%.

[0119] Static fermentation: The salted mustard is fermented at room temperature for 7 days without any stirring.

[0120] Step 2: Single fermentation broth preparation

[0121] Single fermentation liquid: Mix water and salt in proportion, without adding any other ingredients, and use it directly as fermentation liquid.

[0122] Step 3: Mixing and fermentation

[0123] Mixing fermentation broth and mustard: Mix the single fermentation broth with salted mustard in a mass ratio of 1:1 without adding any other ingredients.

[0124] Step 4: Seal the jar for fermentation

[0125] Seal the jar for fermentation: Put the mixed fermentation liquid and mustard directly into the jar, seal it and let it ferment at room temperature for 10 days without stirring.

[0126] Step 5: Late Refrigeration Maturation

[0127] Late-stage cold storage and maturation: The fermented mustard is refrigerated and matured at 4°C for 10 days.

[0128] Through the above steps, the fermented mustard food we prepared has the flavor of traditional salting, but lacks the multi-layered flavor and richness of nutrients brought by the composite fermentation liquid. In addition, due to the lack of multi-stage fermentation and enzymatic hydrolysis, the product may lack sufficient microbial diversity and delicate taste.

[0129] Comparative Example 2

[0130] In this comparative example, no yogurt fermentation is performed, and no yogurt is added during the mustard fermentation process. The remaining steps are the same as those in Example 1.

[0131] Comparative Example 3

[0132] This comparative example does not undergo enzymatic hydrolysis, and the remaining steps are the same as those of Example 1.

[0133] Test Example 1

[0134] The detection test of Examples 1-3 and Comparative Examples 1-3 was carried out, including:

[0135] Sensory evaluation: A professional tasting panel is used to conduct sensory evaluation, including sourness and sweetness, spiciness, taste, aroma and layering.

[0136] Physical and chemical analysis: Testing the acidity (pH), salt content, sugar content and alcohol content of the fermentation liquid.

[0137] Microbiological analysis: Detection of lactic acid bacteria quantity and bacterial diversity in fermented foods.

[0138] Nutritional component testing: Determine the vitamin C content, dietary fiber, protein and other nutrients in fermented foods.

[0139] Storage stability: Observe the changes in flavor, color and texture of fermented foods within 7 days, 14 days and 30 days under refrigerated conditions at 4°C.

[0140] The experimental results are shown in Table 1.

[0141] Table 1

[0142]

[0143]

[0144] As can be seen from Table 1, the fermented foods of Examples 1-3 are superior to Comparative Examples 1-3 in terms of sensory evaluation, which are moderately sweet and sour, rich in aroma, and rich in layers, while the samples of the comparative examples have problems such as single saltiness and insufficient layering. In terms of physical and chemical analysis, the pH value, salt content, sugar content and alcohol content of the embodiments are all within the appropriate range, while the samples of the comparative examples show higher salt content and lower sugar and alcohol content, which may affect the taste and flavor of the product. Microbiological analysis shows that the number of lactic acid bacteria in the embodiments is significantly higher than that in the comparative examples, and the diversity of the flora is richer, which indicates that the fermentation process of the embodiments is healthier and more conducive to the growth of beneficial microorganisms. The results of nutrient component detection also support this point. The vitamin C content, dietary fiber and protein content of the embodiments are all higher than those of the comparative examples, indicating that the fermented foods of the embodiments are superior in nutritional value. Finally, in terms of storage stability, the samples of the embodiments maintained a stable flavor within 30 days without obvious deterioration, while the samples of the comparative examples showed a decline in flavor and peculiar smell, which further proves the superiority of the fermented foods of the embodiments. In summary, the fermented foods of Examples 1-3 are superior to those of Comparative Examples 1-3 in terms of sensory, physical and chemical, microbiological and nutritional components, and have better storage stability.

[0145] Comprehensive analysis:

[0146] From a microscopic perspective, Examples 1-3 significantly improved the flavor and nutrition of low-salt mustard fermented food by optimizing the fermentation method, which involves multiple biochemical and microbiological processes:

[0147] 1. Interaction between multi-stage fermentation and strain metabolism

[0148] Multi-stage fermentation of yogurt: Each lactic acid bacteria (Streptococcus thermophilus, Lactobacillus bulgaricus, Lactococcus lactis) produces different metabolites during the fermentation process, mainly including lactic acid, acetic acid and other volatile acids, as well as some flavor substances and multiple enzymes. These bacteria act successively in the multi-stage fermentation, and the accumulation of each other's metabolites produces a complex sweet and sour taste, making the flavor of the fermented product more layered.

[0149] Secondary fermentation: After adding pectin or isomaltulose, microorganisms further break down sugars to produce short-chain organic acids (such as propionic acid, butyric acid) and polyphenol compounds, giving the yogurt a more unique taste and aroma.

[0150] 2. Enzymatic hydrolysis of mustard and formation of flavor compounds

[0151] Pectinase treatment: Pectinase breaks down the pectin in the cell wall of mustard, releasing nutrients in the cell (such as vitamin C, phenols, flavonoids, etc.). Pectinase also promotes the formation of ester compounds, which react with the metabolites of lactic acid bacteria in the later fermentation to produce a more complex flavor.

[0152] Low temperature sterilization and salting step-by-step fermentation: Under low temperature conditions, the metabolism of mustard tissue proceeds slowly, and amino acids and sugars are converted into flavor precursors under the action of enzymes. During the two-stage salting process, low salt concentration is conducive to the growth of lactic acid bacteria and the accumulation of flavor substances, while maintaining the natural flavor of the food itself.

[0153] 3. The role of compound fermented juice

[0154] Synergistic effect of multi-strain fermentation: Lactobacillus plantarum and Acetobacter aceticus in the composite fermented juice produce lactic acid, acetic acid and ester substances respectively. These substances blend with the natural flavor components of mustard (such as isothiocyanates), further enhancing the sour and spicy taste and forming a unique "fermentation aroma".

[0155] Lactobacillus plantarum metabolizes sugars in vegetable juice: glucose in vegetable juice is converted into lactic acid under the action of Lactobacillus plantarum, which regulates the acidity of the fermented juice. The moderate acidic environment not only inhibits the growth of harmful bacteria, but also enhances the refreshing taste of mustard greens and food safety.

[0156] 4. Sealed fermentation and late maturation

[0157] Lactic acid bacteria metabolism in an anaerobic environment: When fermenting in a sealed jar, the anaerobic environment promotes the anaerobic metabolism of lactic acid bacteria, causing the lactic acid content to increase rapidly, further regulating the acidity, while generating carbon dioxide, giving the product a slight bubbling feeling.

[0158] Late refrigerated maturation: Under 4°C refrigerated conditions, microbial activity is inhibited, and flavor substances are gradually stabilized in the process. Sour, sweet, and spicy flavors blend with each other, increasing the flavor depth of the ingredients. At the same time, the refrigerated temperature extends the shelf life and maintains the texture and nutrition of the product.

[0159] Microbial diversity and health benefits

[0160] Multi-strain environment: The metabolites of each strain enrich the microbial diversity of mustard, provide a diverse beneficial flora for intestinal health, and help regulate intestinal microecology. In addition, the enzymatic substances (such as small molecule peptides, short-chain fatty acids, etc.) produced during the fermentation process are easily absorbed by the human body, increasing the nutritional value.

[0161] In summary, from a microscopic perspective, the fermentation processes of Examples 1-3 significantly improved the flavor and nutritional value through synergistic metabolism and accumulation of beneficial bacteria in terms of raw material processing, strain selection, and optimization of fermentation conditions, making the low-salt mustard fermented food have higher sensory and nutritional quality.

[0162] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A fermentation method for low-salt mustard fermented food, characterized in that: include: Select plant milk or milk raw material, add mixed bacteria and 0.5-1% glucose, and let it stand for primary fermentation until the yogurt solidifies; then add pectin or isomaltulose to continue secondary fermentation, and refrigerate the secondary fermented yogurt to mature to obtain yogurt raw material; Remove roots and leaves of fresh mustard greens and slice them, soak them in ice water for 5-10 minutes, and then refrigerate and soak the mustard greens in a solution containing 2% salt and 0.5% citric acid; then enzymatically hydrolyze the mustard greens with 0.1% pectinase at 25±2°C to soften the fibers, thus completing the mustard greens pretreatment; The mustard greens after pretreatment are salted in two steps, in the first step, 2% salt is added and left to stand for 12 hours; in the second step, 2% salt is added again and salted for 12 hours to obtain salted mustard greens; Fresh vegetables are squeezed to obtain vegetable juice, glucose and soy protein powder are added to the vegetable juice, and Lactobacillus plantarum and Acetobacter acetobacter are inoculated, and the mixture is allowed to stand for fermentation to obtain fermented vegetable juice; the fermented vegetable juice is mixed with yogurt raw materials in a ratio of 3:1, and rice vinegar and spice juice are added to obtain a composite fermentation liquid; The composite fermentation liquid and the salted mustard are mixed in a mass ratio of 1:1.5-2, and 1-2% glucose and 2-3% liquor are added based on the total weight of the composite fermentation liquid and the salted mustard; clean water is added to control the salt concentration in the fermentation mixture to be 3-4%; the mixture is sealed and placed in a jar, and fermented at 25-30° C. for 3-5 days, during which the mixture is stirred once a day to ensure uniform fermentation; after the fermentation is completed, the low-salt fermented mustard food is obtained.

2. The fermentation method of low-salt mustard fermented food according to claim 1, characterized in that: Before the initial fermentation, the vegetable milk or milk raw material is heated to at least 85° C., maintained for at least 30 minutes, and then cooled to 40-42° C.; The secondary fermentation is at 10-15°C for at least 12 hours.

3. The fermentation method of low-salt mustard fermented food according to claim 1, characterized in that: The mixed bacterial species include thermophilic streptococcus, bulgaricus lactobacillus and lactococcus lactis.

4. The fermentation method of low-salt mustard fermented food according to claim 1, characterized in that: The pretreated mustard greens are salted in two steps, and ginger slices and garlic slices are added during the salting process.

5. The fermentation method of low-salt mustard fermented food according to claim 1, characterized in that: The fresh vegetables are celery, carrot and cabbage.

6. The fermentation method of low-salt fermented mustard food according to claim 1, characterized in that: The preparation method of the spice juice comprises: The preparation method of the spice juice is as follows: after star anise, cinnamon, cloves, prickly ash, bay leaves and cumin are mixed, water of ten times the total weight is added and heated to boiling, and then boiled for about 30 minutes. After boiling, the residue is filtered out, and 1-2% of sugar and 0.5% of salt of the total weight of the liquid are added to obtain the spice juice.

7. The fermentation method of low-salt fermented mustard food according to claim 6, characterized in that: The weight ratio of star anise, cinnamon, cloves, pepper, bay leaves and cumin is 4:6:1:4:2:

3.

8. The fermentation method of low-salt fermented mustard food according to claim 1, characterized in that: When glucose and soybean protein powder are added to the vegetable juice, the added amount of glucose is 2% of the weight of the vegetable juice, and the added amount of soybean protein powder is 1% of the weight of the vegetable juice.

9. The fermentation method of low-salt mustard fermented food according to claim 1, characterized in that: The plant milk is oat milk.

10. A low-salt fermented mustard food, characterized in that: The low-salt fermented mustard food is obtained by fermenting through the fermentation method for low-salt fermented mustard food according to any one of claims 1-9.

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