High-lactic-acid-content high-salt liquid-state soy sauce and preparation method thereof

Abstract

The invention relates to the technical field of food, in particular to high-lactic-acid-content high-salt liquid-state soy sauce and a preparation method thereof. According to the method, a high-salt liquid-state soy sauce fermentation process is combined, and a lactic acid fermentation stage is separated from starter propagation fermentation and soy sauce mash fermentation processes, so that an independent lactic acid fermentation process is formed. The lactic acid bacteria are utilized to perform dominant / pure fermentation (step fermentation / lactic acid solid material flowing) under proper conditions to efficiently accumulate lactic acid, so that the lactic acid content in the soy sauce can be effectively increased, and complex interaction between the lactic acid bacteria and other microorganisms in the fermentation process can be reduced / avoided, thereby optimizing the fermentation process and improving the production efficiency. The stability and controllability of the quality of the soy sauce are improved. The innovation of the invention lies in that the independent and targeted lactic acid fermentation step provides a new idea for optimizing the fermentation process of the high-salt liquid-state soy sauce.

Description

Technical Field

[0001] The present invention relates to the technical field of food, in particular to a high-salt dilute soy sauce with high lactic acid content and a preparation method thereof. Background Art

[0002] The main soy sauce fermentation processes in my country include high-salt dilute fermentation, low-salt solid-state fermentation, and mixed solid-dilute fermentation. High-salt dilute fermentation is the predominant method used in commercial production. Regardless of the fermentation process, both koji making and mash fermentation are essential. In recent years, numerous experiments have been conducted to screen and exogenously add lactic acid bacteria to improve the quality of soy sauce. During the koji fermentation stage, the addition of lactic acid bacteria significantly improves the quality of soy sauce and effectively inhibits contamination by foreign bacteria and other harmful substances. During the mash fermentation stage, the addition of salt-tolerant lactic acid bacteria significantly promotes yeast fermentation, inhibits browning of soy sauce, and improves its nutritional value. While the addition of exogenous lactic acid bacteria has numerous benefits, it also presents potential drawbacks, such as the difficult-to-control synergistic growth of lactic acid bacteria with Aspergillus niger and yeast.

[0003] Lactic acid, a key organic acid in the soy sauce fermentation system, plays a dual role in flavor development and microbial ecosystem regulation. In terms of flavor development, lactic acid, through non-covalent interactions such as hydrogen bonding and hydrophobic interactions, forms a dynamic synergistic network with flavor precursors such as amino acids and carbohydrates. This network, anchored by lactic acid's sourness, creates a layered, three-dimensional sourness experience through the synergistic action of multiple components. It balances the perceived saltiness and sweetness of soy sauce, enhancing its richness and lingering flavor. Furthermore, lactic acid actively participates in esterification and Maillard reactions, generating characteristic aroma molecules such as ethyl lactate, thereby forming a complex "acid-ester-alcohol" aroma framework. This unique aroma structure not only enhances the flavor compatibility of soy sauce with various ingredients but also significantly improves its penetration during cooking, allowing dishes to fully absorb the sauce's rich flavor. In terms of microbial ecosystem regulation, lactic acid is primarily produced by lactic acid bacteria through the glycolysis pathway, converting carbohydrates into pyruvate, which is then further converted by lactate dehydrogenase. This biochemical process not only produces antibacterial metabolites, such as lactic acid and bacteriocins, which are considered natural preservatives. This can further extend the shelf life of soy sauce, reduce the use of chemical preservatives, and meet consumers' demand for healthy and safe food. It also creates selective pressure on microorganisms by lowering the pH of the mash, inhibiting the growth of spoilage bacteria such as Escherichia coli. It also provides a suitable growth environment for acid-tolerant flavor yeasts and promotes the orderly succession of microbial communities. Therefore, if the existing soy sauce fermentation process can be adjusted to obtain a higher lactic acid content in the soy sauce, it will not only improve the overall flavor quality of the soy sauce but also enhance its natural preservative ability. This is of great significance for promoting the healthy development of the soy sauce industry and meeting consumers' growing demands for food safety and health.

[0004] At present, the existing high-salt dilute soy sauce fermentation method is specifically as follows: using soybean raw materials (including bean dregs, bean scraps, etc.) and wheat raw materials (including wheat flour, wheat scraps, roasted wheat, etc.) as fermentation substrates, inoculating Aspergillus oryzae to make koji and ferment to obtain finished koji. Subsequently, 1-3 times the volume of high-concentration salt water is added to the finished koji to start the sauce mash fermentation process for not less than 60 days ( Figure 1 ). However, the soy sauce obtained by this method has a low lactic acid content. Therefore, it is urgent to find a method for increasing the lactic acid content in soy sauce. Summary of the Invention

[0005] The purpose of the present invention is to provide a high-salt dilute soy sauce with a high lactic acid content and a preparation method thereof, so as to solve the problems existing in the above-mentioned prior art.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] The present invention provides a method for preparing a high-salt dilute soy sauce with a high lactic acid content, comprising the following steps:

[0008] performing a first fermentation on a soybean-wheat culture medium using lactic acid bacteria to obtain a lactic acid bacteria fermentation solid;

[0009] Using salt water to pass through the lactic acid bacteria to ferment the solid material to obtain salt water;

[0010] The brine is mixed with koji material and subjected to a second fermentation to obtain the high-salt dilute soy sauce with a high lactic acid content.

[0011] Preferably, after the second fermentation, a third fermentation is further included;

[0012] The third fermentation includes the step of adding salt or brine to the material obtained from the second fermentation for fermentation.

[0013] Preferably, the temperature of the first fermentation is 30° C., the time is 48 hours, and the inoculation amount of the lactic acid bacteria is 20% of the volume of the soybean-wheat culture medium;

[0014] And / or, the second fermentation time is ≥24 hours.

[0015] Preferably, the soybean-wheat culture medium comprises soybeans, wheat and water; the mass ratio of the mixture of the soybeans and the wheat to the water is 1:2;

[0016] And / or, the mass percentage of NaCl in the brine is 0%-23%;

[0017] And / or, the volume-to-mass ratio of the flow-through brine to the koji material is (1-3) mL:1 g.

[0018] Preferably, the third fermentation time is ≥48 hours;

[0019] And / or, the mass percentage of NaCl in the mixture of the material obtained from the second fermentation and the brine is 16%-23%.

[0020] Further preferably, the lactic acid bacteria include conventional lactic acid bacteria and salt-tolerant lactic acid bacteria.

[0021] Further preferably, the salt-tolerant lactic acid bacteria include Lactobacillus plantarum gxas-G and / or Lactobacillus plantarum gxas-Y.

[0022] The present invention provides a high-salt dilute soy sauce with high lactic acid content prepared by the method.

[0023] The present invention provides a method for increasing the lactic acid content in high-salt dilute soy sauce, comprising the following steps:

[0024] performing a first fermentation on a soybean-wheat culture medium using lactic acid bacteria to obtain a lactic acid bacteria fermentation solid;

[0025] Using salt water to pass through the lactic acid bacteria to ferment the solid material to obtain salt water;

[0026] The brine is mixed with koji material and subjected to a second fermentation to obtain the high-salt dilute soy sauce with a high lactic acid content.

[0027] Preferably, after the second fermentation, a third fermentation is further included;

[0028] The third fermentation includes the step of adding salt or brine to the material obtained from the second fermentation for fermentation.

[0029] Preferably, the temperature of the first fermentation is 30° C., the time is 48 hours, and the inoculation amount of the lactic acid bacteria is 20% of the volume of the soybean-wheat culture medium;

[0030] And / or, the second fermentation time is ≥24 hours.

[0031] Preferably, the soybean-wheat culture medium comprises soybeans, wheat and water; the mass ratio of the mixture of the soybeans and the wheat to the water is 1:2;

[0032] And / or, the mass percentage of NaCl in the brine is 0%-23%;

[0033] And / or, the volume-to-mass ratio of the flow-through brine to the koji material is (1-3) mL:1 g.

[0034] Further preferably, the third fermentation time is ≥48 hours;

[0035] And / or, the mass percentage of NaCl in the mixture of the material obtained from the second fermentation and the brine is 16%-23%.

[0036] Further preferably, the lactic acid bacteria include conventional lactic acid bacteria and salt-tolerant lactic acid bacteria.

[0037] Further preferably, the salt-tolerant lactic acid bacteria include Lactobacillus plantarum gxas-G and / or Lactobacillus plantarum gxas-Y.

[0038] The present invention discloses the following technical effects:

[0039] The present invention combines the high-salt dilute soy sauce fermentation process, separates the lactic acid fermentation stage from the koji fermentation and mash fermentation processes, and forms an independent lactic acid fermentation process. The present invention first utilizes lactic acid bacteria to carry out dominant / pure strain fermentation under suitable conditions to efficiently accumulate lactic acid. This not only effectively increases the lactic acid content in the soy sauce, but also reduces / avoids the complex interactions between lactic acid bacteria and other microorganisms during the fermentation process, thereby simplifying the fermentation process and improving the stability and controllability of the soy sauce quality. The innovation of the present invention lies in its independent and targeted lactic acid fermentation step, which provides a new approach for optimizing the fermentation process of high-salt dilute soy sauce. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0041] Figure 1 This is a flow chart of a high-salt dilute soy sauce fermentation method in the prior art;

[0042] Figure 2 Flowchart for obtaining high lactic acid soy sauce by step-by-step fermentation;

[0043] Figure 3 The test results of Example 1 are as follows;

[0044] Figure 4 A flow chart showing the flow of lactic acid solids to obtain high lactic acid soy sauce;

[0045] Figure 5 The test results of Example 2 are shown below:

[0046] Figure 6 Flow chart of lactic acid solid flow + step-by-step fermentation to obtain high lactic acid soy sauce;

[0047] Figure 7 This is the test result of Example 3. DETAILED DESCRIPTION

[0048] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0049] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value within any stated value or stated range, and each smaller range between any other stated value or intermediate value within the stated range, is also encompassed within the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0050] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0051] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be exemplary only.

[0052] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0053] Preparation Example 1 Preparation of lactic acid fermentation solids

[0054] 1. Accurately weigh wheat raw materials (including wheat flour, wheat shreds, roasted wheat, etc., this preparation example uses wheat shreds) and soybean raw materials (including bean dregs, bean shreds, bean powder, etc., this preparation example uses soybean shreds) according to a dry weight ratio of 3:7.

[0055] 2. Add water to the weighed wheat raw material and soybean raw material in a mass ratio of 2:1, that is, the amount of water is twice the total mass of the wheat raw material and the soybean raw material, and then sterilize at 121°C for 20 minutes.

[0056] 3. after treating that substratum is cooled to optimum temperature, in the interpolation ratio of 20wt%, add wherein lactic acid bacteria (conventional plant lactobacillus (planting 2) is purchased from the plant lactobacillus of Weikai Haisi Bioengineering Co., Ltd., conventional plant lactobacillus (planting 3) is the plant lactobacillus that is numbered CICC 20022, purchased from corresponding preservation organization; Salt-tolerant plant lactobacillus: plant lactobacillus (Lactiplantibacillusplantarum) gxas-G and plant lactobacillus (Lactiplantibacillusplantarum) gxas-Y) carry out lactic acid fermentation.When lactic acid concentration reaches ideal level (lactic acid concentration is for being greater than or equal to the desired soy sauce lactic acid target concentration of expection, and lactic acid concentration is for being greater than or equal to 5g / L in the present embodiment), this substratum promptly was defined as lactic acid fermentation solid.

[0057] The above-mentioned Lactiplantibacillus plantarum gxas-G and Lactiplantibacillus plantarum gxas-Y have been deposited. The deposit number of Lactobacillus plantarum gxas-G is CGMCC No: 32924, and the deposit number of Lactobacillus plantarum gxas-Y is CGMCC No: 32925. The deposit dates are both December 5, 2024. The depository units are both the General Microbiology Center of China Culture Collection Administration (CGMCC), and the deposit addresses are both the Institute of Microbiology, Chinese Academy of Sciences, No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing.

[0058] Example 1 Method for obtaining high lactic acid soy sauce by step-by-step fermentation

[0059] The steps of obtaining high lactic acid soy sauce by step fermentation are as follows: Figure 2 As shown, the details are as follows:

[0060] 1. Weigh 180g of shredded wheat and 420g of chopped soybeans (the weight of the soybeans is based on the weight before soaking) according to the dry weight ratio. Soak the soybeans in water for 6 hours, then drain with cheesecloth. Wrap in cheesecloth or non-woven fabric, and steam in an autoclave at 118°C for 15 minutes.

[0061] 2. Aspergillus oryzae spore (3.042 Aspergillus oryzae spore powder purchased in Shanghai) is mixed with wheat shreds in proportion (0.01%, g / g) as koji fermentation bacteria. When the soybean shreds to be killed are cooled to 30-35 ℃, the wheat shreds mixed with the bacteria are added to the soybean shreds, and the koji fermentation is carried out after stirring. The fermentation process continues for 38 hours until the koji material is fully mature, and mature koji material is obtained.

[0062] 3. Equal amounts of mature koji were divided into 300 mL wide-bellied glass bottles. Salt water at a concentration of 12 g / 100 mL was added to each of the bottles, with a mass volume ratio of mature koji to salt water of 50 g:90 mL. Lactic acid bacteria (Zhi 2, Zhi 3, halotolerant Lactobacillus plantarum gxas-G, and halotolerant Lactobacillus plantarum gxas-Y) in 10 mL of LMRs culture medium were then inoculated. A control was the treatment without lactic acid bacteria. The bottles were allowed to ferment in a 30°C incubator for 48 hours. These were designated Zhi 2, Zhi 3, G, and Y, respectively.

[0063] 4. After 48 hours of static fermentation, add 9g of salt (NaCl) to make the final concentration of NaCl in the material 21g / 100mL, and place it in a room where sunlight can be exposed to static fermentation.

[0064] 5. Detect lactic acid content, see the detailed results Figure 3 As shown. Figure 3 Recorded as can be known, adopt the segmented fermentation method proposed by the present invention, can significantly improve lactic acid content, and the fermentation effect of salt-tolerant plant lactobacillus is better.But in the soy sauce obtained by this method, lactic acid content depends on the salt-tolerant fermentation performance of salt-tolerant lactic acid bacteria to a great extent, and in the soy sauce fermented by conventional plant lactobacillus, lactic acid content is no more than 3.5g / L.

[0065] Example 2 Method for Obtaining High Lactic Acid Soy Sauce by Flowing Lactic Acid Solids

[0066] The steps of obtaining high lactic acid soy sauce through lactic acid solid flow are as follows: Figure 4 As shown, the details are as follows:

[0067] 1. Weigh 21 g of soybean chops and 9 g of wheat chops into a 250 mL Erlenmeyer flask. Add water to the wheat chops and soybean chops in a 2:1 ratio (30 g of solid content corresponds to 60 g of water, i.e., the mass ratio of solid content to water is 30:60). Then sterilize at 121°C for 20 min to obtain a culture medium.

[0068] 2. After the culture medium is cooled to a suitable temperature, 10 8CFU / mL lactic acid bacteria (the control group did not add lactic acid bacteria, the experimental group added plant 2 or plant 3), and placed at 30 ° C for fermentation for 48 hours to obtain lactic acid fermentation solids, which were recorded as CK solid, 2 solid and 3 solid in turn for subsequent use.

[0069] 3. Use brine with a concentration of 21g / 100mL to flow through the different lactic acid fermentation solids obtained above (the specific steps are: after mixing the brine and the lactic acid fermentation solids, the liquid flowing out is recorded as the solid flow-through liquid; in this embodiment, 100mL of brine is poured, and 100mL of solid flow-through liquid flows out, also called flow-through brine), and add them to the mature koji (prepared by the method of Example 1) for fermentation of sauce mash, the volume mass ratio of the flow-through brine to the mature koji is 3mL:1g, and they are recorded as solid, flow-through 2 and flow-through 3 respectively. At the same time, the treatment of adding brine with a concentration of 21g / 100mL to the mature koji for fermentation of sauce mash is used as a control; the specific information is shown in Table 1. Samples were collected at 0 hours, 24 hours, 120 hours, 240 hours and 720 hours during the fermentation process to determine the lactic acid content.

[0070] Table 1 Information of different samples

[0071]

[0072] 4. Experimental results are as follows Figure 5 The results show that, despite using conventional Lactobacillus plantarum as the lactic acid bacteria, the addition of lactic acid fermentation solids to the brine significantly increased the lactic acid content in the mash. Although the lactic acid content showed a slight downward trend during the mash fermentation process, it remained relatively stable. The lactic acid concentration increased from an initial addition value of approximately 6 g / L to a final level of approximately 5 g / L.

[0073] In order to further increase the lactic acid content of soy sauce, salt-tolerant plant lactobacillus combined with lactic acid fermentation solid flow and step-by-step fermentation technology was used for further optimization.

[0074] Example 3 Method for obtaining high-lactic acid soy sauce by lactic acid solid flow+step fermentation

[0075] The steps of obtaining high lactic acid soy sauce by lactic acid solid flow + step-by-step fermentation are as follows: Figure 6 As shown, the details are as follows:

[0076] 1. Weigh 21 g of soybean chops and 9 g of wheat chops into a 250 mL Erlenmeyer flask. Add water to the wheat chops and soybean chops in a 2:1 ratio (i.e., 60 g of water for 30 g of solid content). Sterilize at 121°C for 20 min to obtain a culture medium.

[0077] 2. After the culture medium was cooled to an appropriate temperature, salt-tolerant lactic acid bacteria (the control group did not add lactic acid bacteria, and the experimental group added salt-tolerant plant lactobacillus gxas-G and salt-tolerant plant lactobacillus gxas-Y activated and cultured for 16 h in MRS broth containing 10% NaCl) were added thereto at a volume ratio of 20% (i.e., 18 mL). The culture medium was placed at 30°C for fermentation for 48 hours to obtain a lactic acid fermentation solid for subsequent use.

[0078] 3. A concentration of 12g / 100mL NaCl was used to flow through the different lactic acid fermentation solids obtained above, and then added to the mature koji (prepared by the method of Example 1) for lactic acid fermentation. The volume mass ratio of the flowing brine and the mature koji was 3mL:1g, which were recorded as flowing through solid G+ segmented fermentation and flowing through solid Y+ segmented fermentation. At the same time, a brine with a concentration of 21g / 100mL was added to the mature koji for the treatment of sauce mash fermentation, and a 12g / 100mL NaCl solution was flowed through the control solid (CK solid) and then added to the mature koji for fermentation for 72 hours to supplement salt, and then the sauce mash fermentation was carried out as a control, which was recorded as control 2 and control 1 respectively. In the flow-through experiments, 9g NaCl was added thereto for sauce mash fermentation after sampling for 72 hours after lactic acid fermentation. The sample information is shown in Table 2. Samples were collected at 0 h, 24 h, 48 h, 72 h, 120 h, and 720 h during the fermentation process to determine the lactic acid content.

[0079] Table 2 Sample information

[0080]

[0081] 4. Experimental results are as follows Figure 7 As shown, Figure 7 The value of the control is the average of the two treatments of control 1 and control 2. The results show that the lactic acid content in the mash is significantly increased again by combining the solid flow of lactic acid fermentation with the staged fermentation technology, reaching about 20g / L.

[0082] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for preparing a high-salt dilute soy sauce with a high lactic acid content, characterized in that: The following steps are involved: performing a first fermentation on a soybean-wheat culture medium using lactic acid bacteria to obtain a lactic acid bacteria fermentation solid; Using salt water to pass through the lactic acid bacteria to ferment the solid material to obtain salt water; The brine is mixed with koji material and subjected to a second fermentation to obtain the high-salt dilute soy sauce with a high lactic acid content.

2. The preparation method according to claim 1, characterized in that After the second fermentation, a third fermentation is also included; The third fermentation includes the step of adding salt or brine to the material obtained from the second fermentation for fermentation.

3. The preparation method according to claim 1, characterized in that The temperature of the first fermentation is 30° C., the time is 48 hours, and the inoculation amount of the lactic acid bacteria is 20% of the volume of the soybean-wheat culture medium; And / or, the second fermentation time is ≥24 hours.

4. The preparation method according to claim 1, characterized in that The soybean-wheat culture medium comprises soybeans, wheat and water; the mass ratio of the mixture of the soybeans and the wheat to the water is 1:2; And / or, the mass percentage of NaCl in the brine is 0%-23%; And / or, the volume-to-mass ratio of the flow-through brine to the koji material is (1-3) mL:1 g.

5. The preparation method according to claim 2, characterized in that The third fermentation time is ≥48 hours; And / or, the mass percentage of NaCl in the mixture of the material obtained from the second fermentation and the brine is 16%-23%.

6. A high-salt dilute soy sauce with a high lactic acid content prepared by the method according to any one of claims 1 to 5.

7. A method for increasing the lactic acid content in high-salt dilute soy sauce, characterized in that: The following steps are involved: performing a first fermentation on a soybean-wheat culture medium using lactic acid bacteria to obtain a lactic acid bacteria fermentation solid; Using salt water to pass through the lactic acid bacteria to ferment the solid material to obtain salt water; The brine is mixed with koji material and subjected to a second fermentation to obtain the high-salt dilute soy sauce with a high lactic acid content.

8. The method according to claim 7, characterized in that After the second fermentation, a third fermentation is also included; The third fermentation includes the step of adding salt or brine to the material obtained from the second fermentation for fermentation.

9. The method according to claim 7, characterized in that The temperature of the first fermentation is 30° C., the time is 48 hours, and the inoculation amount of the lactic acid bacteria is 20% of the volume of the soybean-wheat culture medium; And / or, the second fermentation time is ≥24 hours.

10. The method according to claim 7, characterized in that The soybean-wheat culture medium comprises soybeans, wheat and water; the mass ratio of the mixture of the soybeans and the wheat to the water is 1:2; And / or, the mass percentage of NaCl in the brine is 0%-23%; And / or, the volume-to-mass ratio of the flow-through brine to the koji material is (1-3) mL:1 g.

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