Efficient preservative-free nitrite-free method for preparing pickled Chinese cabbages through whey fermentation and pickled Chinese cabbage product prepared through efficient preservative-free nitrite-free whey fermentation

Abstract

The invention relates to the technical field of food fermentation, and particularly discloses an efficient preservative-free nitrite-free method for preparing pickled Chinese cabbages through whey fermentation and a pickled Chinese cabbage product thereof.The method comprises the steps that fresh milk serves as a raw material, and whey is obtained through standardization, sterilization, fermentation and separation; cleaning, dehydrating and cutting the vegetables; mixing the obtained whey, the obtained vegetables and edible salt according to a weight ratio, and ensuring that the vegetables are completely immersed in the whey; sealing the mixed system, and fermenting at 15-30 DEG C for 25-40 days; after fermentation, taking out the pickled Chinese cabbages, draining, performing vacuum packaging, and storing at normal temperature; according to the invention, the by-product whey of dairy industry is systematically and creatively applied to the field of vegetable fermentation, which is not simple waste utilization, but is redefined from a waste liquid as a composite fermentation starter and culture medium rich in active lactic acid bacteria, a nutrient medium and a natural acid environment.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of food fermentation processing, and particularly relates to a method for preparing green sauerkraut by taking whey as a core fermentation substrate, and especially to a method for preparing sauerkraut by fermenting whey without chemical preservatives and nitrite residues and the product obtained by the method. BACKGROUND

[0002] As a traditional fermented vegetable product in China, the industrial production of sauerkraut mainly relies on natural fermentation or artificial inoculation of lactic acid bacteria fermentation. Natural fermentation relies on complex wild bacterial flora in the environment, and the fermentation process is uncontrollable, which easily leads to unstable product quality, long fermentation period, and the safety hazard of nitrite accumulation. Artificial inoculation fermentation mostly uses a single or limited number of lactic acid bacteria (such as Lactobacillus plantarum, Lactobacillus amylovorus, etc.) to prepare a fermentation agent, which is used by direct injection or after activation and expansion. Although the fermentation period is shortened to some extent, there are still the following technical bottlenecks:

[0003] Single flavor: the use of single or simple mixed bacterial agent fermentation leads to single product flavor and lack of complex layers of traditional natural fermentation sauerkraut due to the narrow metabolic spectrum of the microorganisms;

[0004] Over-reliance on additives: the vegetable tissue is prone to softening during fermentation, and existing technologies mostly rely on the addition of exogenous substances such as calcium lactate to improve texture; in order to ensure the shelf life of the product, chemical preservatives (such as potassium sorbate) are usually added, which not only affects the flavor and texture of the product, but also makes it difficult to meet the needs of consumers for "additive-free" healthy food;

[0005] Cost and technical threshold: the preparation process of functional fermentation agent is complex and costly, and the cumbersome strain activation step is often required when it is applied, which increases the technical threshold and time cost of production;

[0006] Meanwhile, airag (Mongolian "hurda") is a traditional Mongolian dairy product made from fresh cow or sheep milk through fermentation, heating separation, and pressing. During the production of airag, about 80%-90% of the raw milk is converted into whey (also known as "milk water") which is discharged. The main components of whey are lactose (4%-6%), whey protein (0.5%-1.2%), minerals (calcium, phosphorus, etc.), and natural lactic acid bacteria (such as Lactobacillus and Bifidobacterium). Currently, the whey, a byproduct of airag processing, is directly discharged as waste liquid, which not only causes the high nutritional value of whey to be wasted, but also causes water eutrophication pollution due to the high organic matter content, resulting in resource waste and environmental pressure;

[0007] Therefore, there is an urgent need in the field for an innovative technical solution that can simultaneously solve the safety, flavor quality, texture retention, and green production of fermented vegetables, while realizing the high-value utilization of byproducts in the dairy industry. SUMMARY

[0008] The present application aims to provide a high-efficiency, preservative-free, and nitrite-free method for preparing sauerkraut from whey fermentation and the sauerkraut product thereof, which aims to build a natural, safe, and efficient fermentation system by innovatively using whey as the core substrate and microbial source for sauerkraut fermentation, thereby eliminating the addition of exogenous fermentation agents and chemical preservatives and fundamentally avoiding the generation of nitrite, and imparting a unique flavor to the product, thereby solving the problems raised in the background art.

[0009] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0010] A high-efficiency, preservative-free, and nitrite-free method for preparing sauerkraut from whey fermentation, comprising:

[0011] Firstly, the core innovation lies in building a new fermentation system using whey as the fermentation substrate. The method comprises the following steps:

[0012] S1. Preparation of whey fermentation substrate: Fresh cow / sheep milk is used as the raw material, which is subjected to standardization, sterilization, inoculation of yogurt starter, and then fermentation or natural fermentation to obtain whey. This whey is not only a nutrient-rich fermentation medium, but also a natural composite starter rich in active lactic acid bacteria;

[0013] S2. Pretreatment of vegetables: The vegetables (preferably Chinese cabbage) are washed, dehydrated, and cut;

[0014] S3. Construction of fermentation system: The whey obtained in step S1 (preferably after pasteurization), the vegetables obtained in step S2, and edible salt are mixed according to the weight ratio, ensuring that the cabbage is completely immersed in the whey to form an anaerobic fermentation environment;

[0015] S4. Temperature-controlled fermentation: The mixed system is sealed and fermented at 15-30℃ for 25-40 days;

[0016] S5. Product post-treatment: After fermentation, the sauerkraut is removed, drained, vacuum-packed, and stored at room temperature.

[0017] Preferably, step S1 specifically comprises the following steps:

[0018] (a) The raw material fresh cow milk is subjected to standardization and sterilization, and the sterilization conditions are 70-85℃ for 15-30 seconds;

[0019] (b) The sterilized milk is cooled to 40-45℃ and naturally fermented;

[0020] (c) The milk is fermented at 40-43℃ until it coagulates, and the pH value reaches 4.5-4.7;

[0021] (d) subjecting the coagulated yogurt to heat stirring at 70-85°C and separating, and collecting the resulting whey.

[0022] Preferably, the pH of the whey is 3.8-4.6.

[0023] Preferably, the whey is pasteurized before being used for fermentation of the pickled Chinese cabbage.

[0024] Preferably, the whey is directly used for fermentation of the pickled Chinese cabbage before being used for fermentation of the pickled Chinese cabbage.

[0025] Preferably, the whey, Chinese cabbage and salt are mixed in a weight ratio of 90-110 parts of whey, 80-100 parts of Chinese cabbage and 1-3 parts of salt.

[0026] Preferably, the fermentation is divided into two stages: the first stage is fermentation at 25-30°C for 3-7 days, and the second stage is fermentation at 15-20°C for 20-30 days.

[0027] A pickled Chinese cabbage product prepared by the method of any one of the above.

[0028] Compared with the prior art, the present application has the following advantages:

[0029] 1. Fundamental change of fermentation substrate and resource recycling: The present application systematically and creatively applies the by-product whey of dairy product industry to the field of vegetable fermentation. This is not simply waste utilization, but redefines whey from a "waste liquid" to a "compound fermentation starter and culture medium rich in active lactic acid bacteria, nutrient substrate and natural acidic environment". This solves the environmental problem of whey and provides a low-cost, high-activity natural fermentation raw material for pickled Chinese cabbage production, achieving "waste treatment with waste".

[0030] 2. Establishment of natural preservative and nitrite control system: The present application utilizes the characteristics of whey to construct a triple natural safety guarantee system:

[0031] Physical barrier: The liquid substrate of whey can effectively isolate oxygen, creating an anaerobic environment conducive to lactic acid bacteria and not conducive to miscellaneous bacteria.

[0032] Chemical barrier: The acidic environment (pH 3.8-4.6) of whey can rapidly reduce the initial pH of the fermentation system, effectively inhibiting the growth of miscellaneous bacteria (including nitrate-reducing bacteria), and eliminating the generation of nitrite from the source.

[0033] Biological barrier: The active lactic acid bacteria contained in the whey and the antimicrobial peptides, organic acids and other substances produced by their metabolism further strengthen the microbial stability of the system. Through this triple system, the present application ensures product safety and naturally controls nitrite at undetectable levels without adding any chemical preservatives.

[0034] 3. Synergistic generation of complex flavor and unique texture: Unlike traditional single-strain fermentation, the flora introduced by whey and the flora of the vegetable itself may have a synergistic effect, forming a more robust microecosystem. The milk proteins and lactose in the whey are converted into various amino acids, small peptides, organic acids (such as lactic acid and acetic acid), and flavor esters (such as ethyl hexanoate) during fermentation. These substances synergize with the flavor substances produced by the vegetable fermentation, giving the pickled cabbage a unique, mellow, and complex milk aroma. At the same time, the ingredients in the whey protect the pectin in the vegetable tissue, helping to better maintain the crispness of the pickled cabbage.

[0035] 4. Process simplification and cost advantage: The present invention completely eliminates the cumbersome steps and high costs of purchasing or preparing commercial starter cultures, simplifying the production process, reducing technical barriers and production costs, and making the technology more easily promoted in small and medium-sized enterprises. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 is a flowchart of the present invention;

[0037] Figure 2 is a radar chart of sensory evaluation of pickled cabbage of the present invention. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present invention.

[0039] Example 1:

[0040] Please refer to Figure 1 , a method for efficiently preparing pickled cabbage from whey without preservatives and nitrite, comprising the following steps:

[0041] S1. Fresh milk is used as raw material, and standardized, sterilized, naturally fermented, heated at 75-85°C, stirred, and separated to obtain whey;

[0042] S2. Wash, dehydrate, and cut the Chinese cabbage;

[0043] Specifically, fresh, non-rotten Chinese cabbage is selected, the outer old leaves are removed, and the Chinese cabbage is washed with clean drinking water to remove surface impurities. The washed Chinese cabbage is placed in a well-ventilated place to dry until the surface moisture evaporates, or is dehydrated using a centrifuge to achieve a key, optimized water activity. The Chinese cabbage is cut into shapes suitable for fermentation and consumption, such as 1-2 cm wide strips or 5-8 cm blocks;

[0044] S3, mixing the whey obtained in step S1 and the Chinese cabbage obtained in step S2 with edible salt according to the weight ratio, ensuring that the Chinese cabbage is completely immersed in the whey to create a good anaerobic fermentation environment. In this process, no commercial fermentation agent, chemical preservative, or flavoring agent is added;

[0045] S4, sealing the mixed system and fermenting at 15-30°C for 25-40 days;

[0046] S5, after the fermentation is completed, the pickled Chinese cabbage is taken out, drained, vacuum packaged, and stored at room temperature.

[0047] In one embodiment of the present application, step S1 specifically comprises the following steps:

[0048] (a) standardizing and sterilizing the raw material fresh milk, with sterilization conditions of 70-85°C for 15-30 seconds;

[0049] Specifically, high-temperature short-time (HTST) sterilization is used to kill pathogenic bacteria and miscellaneous bacteria, while avoiding excessive damage to nutrients due to long-term high temperature;

[0050] (b) cooling the sterilized milk to 40-45°C for natural fermentation

[0051] (c) fermenting at 40-43°C until the milk coagulates and the pH value reaches 4.5-4.7, which usually takes 24-48 hours;

[0052] (d) heating and stirring the coagulated milk at 75-85°C and separating to collect the whey;

[0053] Specifically, the coagulated yogurt is subjected to mild mechanical treatment (such as low-speed stirring) and then filtered and separated.

[0054] In one embodiment of the present application, the pH value of the whey is 3.8-4.6.

[0055] In one embodiment of the present application, the whey is subjected to pasteurization (72-75°C, 15-30 seconds) before being used for pickled Chinese cabbage fermentation, to inactivate miscellaneous bacteria and preserve beneficial bacteria, ensuring that the subsequent pickled Chinese cabbage fermentation is dominated by the bacterial flora we expect.

[0056] In one embodiment of the present application, the weight ratio of whey, cabbage and salt is: whey 90-110 parts, cabbage 80-100 parts, and salt 1-3 parts.

[0057] In one embodiment of the present application, the fermentation is divided into two stages: the first stage is fermented at 25-30°C for 3-7 days to quickly start fermentation; and the second stage is fermented at 15-20°C for 20-30 days to slowly generate rich flavor substances.

[0058] A pickled vegetable product prepared by any of the above methods, the pH value of the pickled vegetable is generally stabilized at 3.5-3.8, and the total acid (calculated as lactic acid) reaches 0.8-1.5%;

[0059] The mature pickled vegetable is taken out, and can be appropriately drained or part of the fermentation liquid is retained according to the needs, filled, and vacuum packaged according to the product design, so as to guarantee the shelf life.

[0060] Example 1: Pasteurized whey fermentation

[0061] Fermentation conditions:

[0062] Whey treatment: pasteurization at 72°C for 20 seconds;

[0063] Fermentation temperature: first stage 28°C for 5 days + second stage 18°C for 25 days;

[0064] Salt concentration: 2%;

[0065] Whey: cabbage: salt = 100:90:2; test results:

[0066]

[0067] Example two:

[0068] Please refer to Figure 1 The present application provides a specific embodiment of preparing pickled vegetable by whey fermentation, and the steps are as follows:

[0069] (1) Preparation of whey:

[0070] Take fresh milk 120L, adjust the fat and protein content to the standard, and then sterilize it by high temperature short time (HTST) sterilization method at 85°C for 20 seconds, then cool the milk to 42°C, naturally ferment, then ferment at 42°C for 48 hours until the milk is completely solidified and the pH value is reduced to 4.6, heat the solidified yogurt to 75°C and stir at low speed, filter and separate with gauze, collect about 100 kg of whey filtrate, and measure the pH value to be 4.2, store the whey at 4°C for standby, and do not perform pasteurization to retain all the active lactic acid bacteria and enzyme system therein;

[0071] (2) Vegetable pretreatment:

[0072] Select fresh, no rotten injury of Chinese cabbage 90 kg, artificial removal of outer old leaves, using clean drinking water for spraying cleaning, to remove the surface mud and impurities, the washed cabbage is placed in a clean draining rack natural ventilation 2 hours, so that its surface water is fully evaporated, then, using the cutting machine into the cabbage width of about 1 cm strip.

[0073] (3) Mixed into the tank:

[0074] Prepare a volume of 200 liters of food-grade plastic fermentation tank with a sealed cover, according to the following weight ratio for feeding:

[0075] Step (1) prepared whey: 100 kg;

[0076] Step (2) pretreated cabbage strip: 90 kg;

[0077] Edible salt: 2 kg;

[0078] The feeding sequence is to mix the cabbage strip and salt in the tank first, then pour in all the whey, stir slightly to dissolve the salt, and make sure all the cabbage strips are fully immersed in the whey to create an anaerobic fermentation environment. During the whole process, no commercial fermentation agent, chemical preservative or flavoring agent is added;

[0079] (4) Temperature control fermentation:

[0080] The fermentation tank is strictly sealed and transferred to the constant temperature fermentation room for static fermentation at 30℃ (±1℃). The total fermentation period is 30 days. No stirring or opening operation is performed during the whole fermentation period.

[0081] (5) Maturity and filling:

[0082] After 30 days of fermentation, the tank is opened for detection. The product emits a rich, coordinated sour aroma and a complex aroma with a slight milk fat. The texture remains crisp and tender. The product pH value is stable at 3.7, the total acid (calculated as lactic acid) content is 1.2%, and no nitrite (below the detection limit) and any chemical preservative is detected by the national standard method (such as GB 5009.33).

[0083] The pickled and matured sauerkraut is taken out and the excess fermentation liquid is drained using a centrifuge. Then, vacuum packaging is performed according to the standard of 200 grams per bag. Finally, the vacuum packaged product is stored at room temperature.

[0084] Fermentation conditions:

[0085] Whey treatment: Direct use of whey containing active bacteria;

[0086] Fermentation temperature: 28°C for 5 days + 18°C for 25 days;

[0087] Salt concentration: 2%;

[0088] Whey: Chinese cabbage: salt = 100:90:2;

[0089] Results of the tests:

[0090]

[0091] Comparative Example 1 : traditional natural fermentation

[0092] Fermentation conditions:

[0093] Fermentation substrate: tap water + 4% salt;

[0094] Fermentation temperature: ambient temperature (15-25°C) natural fermentation;

[0095] Fermentation time: 60 days;

[0096] No addition of any bacterial agent;

[0097] Results of the tests:

[0098]

[0099] Comparative Example 2: fermentation with commercial bacterial agent

[0100] Fermentation conditions:

[0101] Fermentation substrate: purified water + 3% salt;

[0102] Bacterial agent: commercial Lactobacillus plantarum fermenting agent (direct throw type);

[0103] Fermentation temperature: 25°C constant temperature fermentation for 35 days;

[0104] Bacterial agent addition: 0.02%;

[0105] Results of the tests:

[0106]

[0107] Comparison of the key properties of the final products

[0108]

[0109] Comparison of the dimensions of the sensory evaluation:

[0110] In order to objectively evaluate the progress of the pickled Chinese cabbage prepared by the method in the sense of the quality of the sensory, the final products of Example 1, Comparative Example 1 (traditional natural fermentation) and Comparative Example 2 (commercial fermentation) are subjected to professional sensory evaluation. The evaluation results are shown in the figure.

[0111] By Figure 2 It can be seen directly that the product of Example 1 is significantly better than the two comparative examples in the five core sensory dimensions, forming a comprehensive encirclement, which is specifically manifested as follows:

[0112] The flavor quality is significantly superior: Example 1 has the highest scores in sourness purity (4.7 points) and flavor complexity (4.8 points). The evaluator describes its sourness as "soft and mellow", and has "obvious cream aroma and rich layers", which is closely related to the unique metabolites brought by whey fermentation. The flavor of Comparative Example 1 is single and occasionally has an odor, and the flavor of Comparative Example 2 is flat.

[0113] The texture retention is excellent: the crispness of Example 1 (4.9 points) is much higher than that of Comparative Example 1 (3.2 points). This indicates that the whey fermentation system may have a better protective effect on the pectin component of the vegetable tissue, effectively solving the technical problem of easy softening of traditional fermentation.

[0114] The sensory appeal is comprehensive: in terms of color and aroma purity, Example 1 also maintains the lead. Its product has golden and bright color, and pure and pleasant aroma, without the common unpleasant odor of traditional fermentation.

[0115] Flavor substance analysis data (GC-MS detection)

[0116] Characteristic flavor substance comparison (unit: μg / g):

[0117]

[0118] Shelf life experiment data

[0119] 37℃ accelerated shelf life experiment:

[0120]

[0121] Although the embodiments of the present application have been shown and described, it can be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to the embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A method for preparing kimchi from high efficiency, preservative-free, and nitrite-free whey fermentation, characterized by, The method comprises the following steps: S1, taking fresh milk as raw material, standardizing, sterilizing, fermenting, and separating to obtain whey; S2, washing, dehydrating, and cutting the vegetables; S3, mixing the whey obtained in step S1 and the vegetables obtained in step S2 with edible salt according to weight ratio, and ensuring that the vegetables are completely immersed in the whey; S4, sealing the mixed system and fermenting at 15-30℃ for 25-40 days; S5, after the fermentation is completed, taking out the pickled vegetables, draining, vacuum packaging, and storing at normal temperature.

2. A process for the preparation of sauerkraut from high efficiency non-preserved non-nitrite whey fermentation as claimed in claim 1, wherein, The step S1 specifically comprises the following steps: (a) standardizing and sterilizing the raw material fresh milk, and the sterilization condition is 70-85℃ for 15-30 seconds; (b) cooling the sterilized fresh milk to 40-45℃ and fermenting; (c) fermenting at 40-43℃ until the milk coagulates and the pH value reaches 4.5-4.7; (d) heating and stirring the coagulated yogurt and separating to collect the obtained whey.

3. The method for preparing pickled vegetables by high-efficiency whey fermentation without preservative and nitrite according to claim 1, wherein the pH value of the whey is 3.8-4.

6.

4. A process for the preparation of fermented acid vegetable from high efficiency whey without preservative without nitrite as claimed in claim 1, wherein: The whey is subjected to pasteurization treatment before being used for pickled vegetable fermentation.

5. A process for the preparation of fermented acid vegetable from high efficiency, preservative free, nitrite free whey as claimed in claim 1, wherein: The whey is directly used before being used for pickled vegetable fermentation.

6. A process for the preparation of fermented acid vegetable from high efficiency, preservative free, nitrite free whey as claimed in claim 1, wherein: The weight ratio of the whey, the vegetables, and the salt is: whey 90-110 parts, vegetables 80-100 parts, and salt 1-3 parts.

7. A process for the preparation of fermented acid vegetable from high efficiency whey without preservative without nitrite as claimed in claim 1, wherein, The fermentation is divided into two stages: the first stage is fermented at 25-30℃ for 3-7 days, and the second stage is fermented at 15-20℃ for 20-30 days.

8. A process for the preparation of fermented acid vegetable from high efficiency whey without preservative without nitrite as claimed in claim 1, wherein, The vegetables are preferably Chinese cabbage; and the fresh milk is preferably fresh cow milk.

9. A process for the preparation of fermented pickle from whey without preservative and without nitrite as claimed in claim 1 wherein, In the preparation of the whey, natural fermentation is preferred.

10. A sauerkraut product, characterized in that, Prepared by the method according to any one of claims 1-9.

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