Soy sauce rich in organic acids

Abstract

The purpose of the present invention is to provide soy sauce which has high palatability and a pleasant taste while containing a large amount of lactic acid. The purpose is achieved by: soy sauce having a lactic acid content of at least 2.5 w / v%, wherein the lactic acid is not externally added; and a method for producing soy sauce, the method comprising a step for obtaining soy sauce moromi juice by subjecting soy sauce moromi to a solid-liquid separation treatment, and a step for obtaining soy sauce having a lactic acid content of at least 2.5 w / v% by subjecting the soy sauce moromi juice to lactic acid fermentation due to soy sauce lactic bacteria while adjusting the pH to 5.0-7.0 using an alkaline agent.

Description

[Technical Field]

[0001] This invention relates to soy sauce that is rich in organic acids such as lactic acid. [Background technology]

[0002] It is known that organic acids such as lactic acid have a strong influence on the taste of food. For example, in the traditional brewing method for soy sauce, the more vigorous the lactic acid fermentation, the more desirable flavors such as a refreshing sourness, a firm taste, and a lingering flavor are imparted to the soy sauce by lactic acid and other organic acids, resulting in a soy sauce with a superior taste.

[0003] Methods to increase the lactic acid content in soy sauce include externally adding lactic acid or its salt, sodium lactate, to the soy sauce, and improving the amount of lactic acid produced during lactic acid fermentation. One known method for improving the amount of lactic acid produced during lactic acid fermentation is to add an alkaline agent such as sodium bicarbonate to the mash consisting of soy sauce koji and brine to adjust the pH to 5.6-6.2 and then carry out lactic acid fermentation (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Patent Publication No. 18146 / 1986 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] However, among the methods for increasing the lactic acid content in soy sauce, the method of externally adding lactic acid to soy sauce is impractical because the resulting soy sauce has too low a pH. Furthermore, according to the inventors' research, when the method of externally adding sodium lactate to soy sauce is adopted, the resulting soy sauce has the problem of being excessively salty, and also exhibiting undesirable tastes such as a harsh initial taste and an unnatural flavor.

[0006] The method described in Patent Document 1 can increase the lactic acid content in the resulting soy sauce. However, when using the method described in Patent Document 1, if the lactic acid concentration is to be increased to 2,000 mg% (2.0 w / v%) or higher, the amount of alkaline agent added must be increased, which leads to the generation of an alkaline odor and suppression of yeast growth, resulting in a deterioration of the taste of the resulting soy sauce. Therefore, the soy sauce obtained by the method described in Patent Document 1 has a lactic acid content of 1.0 w / v% to 2.0 w / v%, which is still low.

[0007] Therefore, the problem that this invention aims to solve is to provide a highly palatable soy sauce that contains a large amount of lactic acid while still exhibiting a desirable taste. [Means for solving the problem]

[0008] The inventors diligently studied the raw materials and intermediate products used in soy sauce production, as well as the production conditions and processes, in order to solve the above problems. In the process, they found that in the method of adding an alkaline agent to the mash, as described in Patent Document 1, the solid content of the mash is large and the viscosity becomes about 1,000 cP or more. Therefore, in order to make the pH of the mash uniform during fermentation, a large amount of alkaline agent must be added and high-intensity stirring must be performed. Such high-intensity stirring leads to premature yeast growth before the amount of lactic acid becomes sufficiently high, and premature yeast growth suppresses lactic acid fermentation. Consequently, the inventors found that in the method of adding an alkaline agent to the mash, it is difficult to increase the amount of lactic acid to more than 2.0 w / v%, regardless of the timing of the addition of the alkaline agent.

[0009] Therefore, the inventors continued to experiment in an attempt to obtain soy sauce rich in organic acids such as lactic acid, and came to focus on lactic acid fermentation using the pressed liquid obtained by removing the solids from the mash. Because the pressed liquid has a small amount of solids, the pH can be uniformly adjusted even with slow stirring. Therefore, in lactic acid fermentation using the pressed liquid, an appropriate amount of alkaline agent can be added as needed to match the decrease in pH due to the lactic acid produced during lactic acid fermentation, thereby suppressing the premature growth of yeast and adjusting the pH to a predetermined range. And, surprisingly, by carrying out continuous lactic acid fermentation using such pressed liquid, they succeeded in obtaining soy sauce with a lactic acid content of 2.5 w / v% or more.

[0010] Even more surprisingly, the resulting lactic acid-rich soy sauce exhibited a strong, desirable flavor while minimizing undesirable flavors, and also had a reduced saltiness, resulting in high palatability. In this way, the inventors succeeded in creating a highly palatable soy sauce that contains a large amount of lactic acid while still exhibiting a desirable flavor, thus solving the problem of the present invention. This invention was completed based on such successful examples and findings.

[0011] Therefore, according to each aspect of the present invention, the following is provided: [1] Soy sauce having a lactic acid content of 2.5 w / v% or more, and the lactic acid is not added externally. [2] Soy sauce having a lactic acid content of 2.5 w / v% or more, and being a lactic acid fermented product of the pressed liquid of soy sauce koji. [3] The lactic acid fermented product of the pressed liquid of the soy sauce koji is Tetragenococcus halophilus, which is a soy sauce lactic acid bacterium. Tetragenococcus halophilus The soy sauce described in [2] is a lactic acid fermented product of the pressed liquid of soy sauce koji produced by [2]. [4] The soy sauce according to [3], wherein the soy sauce contains the soy sauce lactic acid bacteria such that the turbidity is 500 ppm or more. [5] A step of subjecting the soy sauce moromi to a solid-liquid separation process to obtain the soy sauce moromi liquid, The process involves subjecting the aforementioned soy sauce moromi liquid to lactic acid fermentation by soy sauce lactic acid bacteria while adjusting the pH to 5.0-7.0 using an alkaline agent, in order to obtain soy sauce with a lactic acid content of 2.5 w / v% or more. A method for manufacturing soy sauce, including the method described above. [6] The method for producing soy sauce according to [5], wherein the alkaline agent is at least one alkaline agent selected from the group consisting of sodium carbonate, sodium hydroxide, and sodium bicarbonate. [Effects of the Invention]

[0012] According to the present invention, a highly palatable soy sauce can be obtained that contains a large amount of lactic acid while still exhibiting a desirable taste. One embodiment of the present invention, being rich in soy sauce lactic acid bacteria in addition to lactic acid, exhibits a desirable taste while suppressing saltiness. Compared to ordinary soy sauce, it has an excellent flavor with a stronger umami and richness from the initial taste to the aftertaste, without compromising the balance of flavors. Furthermore, one embodiment of the present invention does not undergo alcoholic fermentation, resulting in a milder soy sauce aroma, while also being less prone to the raw material odor that is generally present as an off-flavor in soy sauce with poor alcoholic fermentation. One embodiment of the present invention is an excellent seasoning that can be widely used to adjust the flavor of various dishes, including Japanese cuisine. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 shows the time-dependent measurement results of the pH value and lactic acid concentration of the fermentation liquid during the production of high-lactic acid soy sauce in Example 1, as described in the examples below. [Figure 2] Figure 2 shows the results of the sensory evaluation of lactic acid-adjusted lactic acid soy sauce and clarified high-lactic acid soy sauce conducted in Example 2, as described in the examples below. [Figure 3] Figure 3 shows the results of the sensory evaluation of the pressed juice and externally added lactic acid soy sauce carried out in Example 3, as described in the examples below. [Figure 4]Figure 4 is a diagram showing the results of sensory evaluation of clarified high-lactic acid soy sauce, turbidity-adjusted lactic acid soy sauce, and high-lactic acid soy sauce implemented in Example 4, as described in the examples mentioned later. Mode for Carrying Out the Invention

[0014] Hereinafter, details of each aspect of the present invention will be described, but the present invention is not limited only by the matters described in this section, and can take various aspects as long as the object of the present invention is achieved.

[0015] Unless otherwise specified, each term used in the present specification has the meaning commonly used by those skilled in the art of food including seasonings such as soy sauce, and should not be construed as having an unreasonably restrictive meaning. In addition, since the conjectures and theories set forth in the present specification are made based on the inventors' previous knowledge and experience, the present invention is not bound only by such conjectures and theories.

[0016] The term "content" is synonymous with concentration, and means the ratio of the amount of a component to the total amount of soy sauce. Provided that the total content of the components does not exceed 100%. "w / v%" is synonymous with "%(w / v)" and represents mass-volume percent concentration; "v / v%" is synonymous with "%(v / v)" and represents volume percent concentration. "ppm" is a unit having a commonly known meaning, and specifically, 1 ppm is 1 / 10 6 ^6, which is 1 μg / g in terms of mass, and approximately 1 mg / l in terms of mass-volume conversion. The symbol "~" in a numerical range means a range including the numerical values before and after the symbol; for example, "500 ppm to 10,000 ppm" means a range of not less than 500 ppm and not more than 10,000 ppm. "To include" means that elements other than those explicitly included can be added (synonymous with "at least include"), but it also encompasses "consisting of" and "essentially consisting of." In other words, "to include" can mean that it includes the explicitly included elements and any one or more of those elements, consists of the explicitly included elements, or essentially consists of the explicitly included elements. Examples of elements include components, processes, conditions, parameters, and other limitations. The terms "and / or" mean any one of the listed related items, any combination of two or more, or any combination of all of them. The number of digits in an integer value matches the number of significant figures. For example, 1 has 1 significant figure, and 10 has 2 significant figures. Similarly, the number of digits after the decimal point in a decimal value matches the number of significant figures. For example, 0.1 has 1 significant figure, and 0.10 has 2 significant figures.

[0017] "Lactic acid that is not externally added" refers to lactic acid produced primarily through the action of lactic acid bacteria during the soy sauce manufacturing process, and does not mean lactic acid or lactate that has been artificially added to the soy sauce. "Fermentation" and "aging" are not strictly distinguished, and sometimes the term "fermentation" is used to refer to both processes together.

[0018] "The authentic taste of soy sauce" refers to the taste perceived on the tongue when tasting raw soy sauce made using the standard brewing method with soybeans and wheat as raw materials. "Sweetness" refers to the taste one perceives when sugar is placed in the mouth. "Salty taste" refers to the taste one perceives when one puts table salt (sodium chloride) in their mouth. "Bitterness" refers to the unpleasant taste one experiences when eating something that has been burnt. "Umami" refers to the authentic taste of soy sauce, the kind that envelops the entire tongue, as felt when you first taste raw soy sauce. Of the different types of umami, "initial umami" refers to the umami felt while the soy sauce is in your mouth, while "aftertaste umami" refers to the umami that remains after swallowing. "Mellowness" refers to the harmonious and expansive flavor profile inherent in soy sauce, where no single taste overwhelms the palate when consumed. "Koku" refers to a taste that encompasses sweetness, umami, and mellowness, and is the inherent flavor of soy sauce that is felt on the tongue with persistence and breadth. "Meatiness" refers to a strong, lingering umami flavor that evokes the tastes of livestock such as chicken, pork, and beef, as well as seafood such as canned tuna and shellfish. "Abrupt initial taste" refers to a salty, bitter, or sour taste that is distinctly different from the original flavor of soy sauce and is felt while the soy sauce is in the mouth. An "unnatural taste" refers to a taste in which the harmonious balance of the five basic tastes inherent in soy sauce is lost due to an overpowering saltiness, bitterness, or sourness.

[0019] [soy sauce] One embodiment of the present invention provides soy sauce having a lactic acid content of 2.5 w / v% or more. However, the lactic acid is not added externally, but is produced by lactic acid fermentation during the soy sauce manufacturing process.

[0020] One embodiment of the present invention is a soy sauce obtained by lactic acid fermentation to achieve a lactic acid content of 2.5 w / v% or more. As a result, it possesses the original flavor of soy sauce while also having enhanced umami and richness, resulting in a superior flavor. This embodiment of the present invention is used to season food, just like ordinary soy sauce.

[0021] In the traditional brewing method for producing soy sauce (hereinafter sometimes referred to as the conventional soy sauce production method in this specification), soy sauce moromi is obtained by fermenting soy sauce koji in brine with lactic acid. The lactic acid content of the soy sauce moromi obtained in this way is usually 1 w / v% or less, and in many cases 0.5 w / v% or less. Regardless of these circumstances, it is presumed that if lactic acid fermentation is promoted under conditions that result in a lactic acid content of 2.5 w / v% or more, various organic acids in addition to lactic acid will be produced in abundance. As a result, the resulting soy sauce is thought to have a stronger umami and richness compared to ordinary soy sauce, without compromising the balance of flavors, due to the influence of organic acids including lactic acid, and thus possess a superior taste.

[0022] Soy sauce (also called shoyu or shoyu) is the commonly known meaning, and can be said to be the definition described in, for example, the Ministry of Agriculture, Forestry and Fisheries' notification "Standards for Soy Sauce Quality Labeling" and "Japanese Agricultural Standards for Soy Sauce." Specific examples of soy sauce include dark soy sauce, light soy sauce, white soy sauce, tamari soy sauce, and double-brewed soy sauce. Other examples include raw soy sauce, dashi soy sauce, teriyaki soy sauce, raw fried soy sauce, quick-brewed soy sauce, amino acid-mixed soy sauce, reduced-sodium soy sauce, and low-sodium soy sauce. Soy sauce may be one type of the above listed, or a combination of two or more types. In one embodiment of the present invention, it is preferable that the soy sauce is obtained by a traditional brewing method of soy sauce production.

[0023] The lactic acid content in soy sauce according to one embodiment of the present invention is not particularly limited as long as it is 2.5 w / v% or more. However, for example, in order to make the soy sauce according to one embodiment of the present invention have enhanced umami and / or richness compared to ordinary raw soy sauce, it is preferably 3.5 w / v% or more, more preferably 4.5 w / v% or more, and even more preferably 5.0 w / v% or more. The upper limit of the lactic acid content is not particularly limited, but it is preferably 20 w / v% or less, and more preferably 10 w / v% or less. The lactic acid content is measured by the method described in the examples below.

[0024] In one embodiment of the present invention, the soy sauce, by containing soy sauce lactic acid bacteria, has its saltiness and / or bitterness mitigated, resulting in a milder taste. Furthermore, the contained soy sauce lactic acid bacteria tend to enhance the umami, richness, meatiness, and / or smoothness, and also increase the sweetness. Therefore, in order to improve the taste of the soy sauce according to one embodiment of the present invention, it is preferable to contain soy sauce lactic acid bacteria so that the turbidity is 500 ppm or more, more preferably so that the turbidity is 1,000 ppm or more or 2,000 ppm or more, even more preferably so that the turbidity is 3,000 ppm or more or 4,000 ppm or more, and still more preferably so that the turbidity is 5,000 ppm or more or 6,000 ppm or more. The upper limit of turbidity is not particularly limited; for example, it is preferably 20,000 ppm, and more preferably 10,000 ppm. Therefore, it is preferable that the soy sauce according to one embodiment of the present invention contains soy sauce lactic acid bacteria such that the turbidity is between 500 ppm and 20,000 ppm. The turbidity is measured by the method described in the examples below.

[0025] In the production of soy sauce according to one embodiment of the present invention, if a large amount of yeast is present, lactic acid production is suppressed, and alcohol is produced instead. In other words, by suppressing alcohol production, the growth of yeast can be inhibited, and the growth of lactic acid bacteria and the production of lactic acid can be promoted. From this viewpoint, the alcohol content in the soy sauce moromi liquid at the lactic acid fermentation stage is preferably less than 1 v / v%, more preferably 0.9 v / v% or less, even more preferably 0.5 v / v% or less, and still more preferably 0.20 v / v% or less. The lower limit of the alcohol content is not particularly limited, and may be substantially 0.0 v / v%, for example. Therefore, the alcohol content in the soy sauce moromi liquid at the lactic acid fermentation stage is preferably 0.0 v / v% to 1 v / v%. The alcohol content is measured by the method described in the examples below.

[0026] One embodiment of the present invention may be soy sauce in the form of bottled soy sauce filled in a sealable airtight or airtight container. The container is not particularly limited as long as it is a container that prevents solid or liquid foreign matter from entering and prevents loss or evaporation of the filled soy sauce under normal handling, transport, or storage conditions, or a container that prevents gas from entering. Examples of such containers include single-layer or laminated film bags, retort pouches, vacuum packs, molded containers, bottles, and cans made from materials such as aluminum, steel, paper, PET, or glass. Bottled soy sauce can be independently distributed and sold commercially.

[0027] Soy sauce according to one aspect of the present invention can be used in the same way as ordinary soy sauce. That is, soy sauce according to one aspect of the present invention can be used alone, or mixed with or in combination with other ingredients such as dashi, acidulants, amino acids, nucleic acids, organic acids, protein hydrolysates, sugars, sake, mirin, alcohol, thickeners, emulsifiers, and inorganic salts, in addition to water, vegetable components, yeast extract, meat extract, fruit juice, spices, chemical seasonings, and flavors, for cooking and processing various food ingredients. For example, soy sauce according to one aspect of the present invention can be used in various dishes such as Japanese, Western, and Chinese cuisine, and specifically in dishes such as fried foods, grilled meat, udon, soba, ramen, hamburgers, meatballs, Chikuzen-ni, teriyaki, curry, stew, and Hayashi rice, but is not limited to these.

[0028] An example of a non-limiting specific embodiment of soy sauce according to one aspect of the present invention is soy sauce having the following lactic acid content: Lactic acid content: 2.5 w / v% ~ 10 w / v%

[0029] As an example of a non-limiting other specific embodiment of soy sauce according to one aspect of the present invention, there is soy sauce having the following lactic acid content and turbidity: Lactic acid content: 2.5 w / v% ~ 10 w / v% Turbidity: 500ppm~10,000ppm

[0030] Soy sauce according to one aspect of the present invention can be obtained by lactic acid fermentation of the pressed liquid of soy sauce moromi so that the lactic acid content is 2.5 w / v% or more. Therefore, another aspect of the present invention is soy sauce having a lactic acid content of 2.5 w / v% or more and being a lactic acid fermented product of the pressed liquid of soy sauce moromi.

[0031] [Soy sauce manufacturing method] According to another aspect of the present invention, a method for producing soy sauce according to one embodiment of the present invention is provided. The method according to one embodiment of the present invention includes the steps of subjecting soy sauce moromi to a solid-liquid separation treatment to obtain soy sauce moromi liquid, and subjecting the soy sauce moromi liquid to lactic acid fermentation by soy sauce lactic acid bacteria while adjusting the pH to 5.0 to 7.0 using an alkaline agent to obtain soy sauce having a lactic acid content of 2.5 w / v% or more.

[0032] In outline, one aspect of the present invention is a method for producing soy sauce in which soy sauce koji is placed in brine and lactic acid fermentation is carried out by soy sauce lactic acid bacteria, after which the obtained soy sauce moromi is separated into solid and liquid to obtain soy sauce moromi liquid, and then the soy sauce moromi liquid is subjected to lactic acid fermentation while being adjusted to a predetermined pH. In the case of traditional brewing methods, soy sauce is produced by inoculating and culturing a mixture of protein raw materials such as heat-denatured soybeans and starchy raw materials such as wheat that have been gelatinized by heating with seed koji containing koji mold, then placing the obtained soy sauce koji in brine and performing lactic acid fermentation and maturation to obtain soy sauce moromi, then performing yeast fermentation and maturation of the obtained soy sauce moromi to obtain aged moromi, then subjecting the obtained aged moromi to pressing and filtering to obtain raw soy sauce, and finally heating the obtained raw soy sauce.

[0033] In one embodiment of the present invention, unlike conventional methods for producing soy sauce, the soy sauce moromi after lactic acid fermentation is not continuously subjected to yeast fermentation. Instead, the soy sauce moromi is separated into an insoluble solid portion (soy sauce moromi concentrate) and a liquid portion (soy sauce moromi liquid), and then lactic acid fermentation is carried out on the soy sauce moromi liquid under predetermined pH conditions. Therefore, this method includes the steps of obtaining soy sauce moromi liquid from soy sauce moromi and carrying out lactic acid fermentation with pH adjustment. The soy sauce obtained in this way may have a lactic acid content of 2.5 w / v% or more. In one embodiment of the present invention, it is preferable to include the step of obtaining soy sauce moromi as a preliminary step.

[0034] The process of obtaining soy sauce moromi can be any step in the normal soy sauce manufacturing method up to obtaining soy sauce moromi. One specific example of the process of obtaining soy sauce moromi is to inoculate soy sauce raw materials, which are a mixture of steamed and modified soybeans and roasted and crushed barley, with koji starter, and to produce soy sauce koji by aeration at 10°C to 40°C for about 1 to 4 days, then to put the soy sauce koji into a brine solution with a salt concentration of 15% (w / v) to 35% (w / v), and optionally add soy sauce lactic acid bacteria, and then ferment and mature the mixture at 10°C to 40°C for 10 to 200 days, preferably 15 to 40 days, while stirring as appropriate, in order to obtain soy sauce moromi.

[0035] The ingredients for soy sauce are not particularly limited, but examples include soybeans such as whole soybeans and defatted soybeans, wheat, barley, hulless barley, adlay, barley gluten, rice, and corn.

[0036] The koji starter is not particularly limited to any koji mold commonly used in soy sauce production, but for example, Aspergillus oryzae ( Aspergillus oryzae ), Aspergillus soybean ( A.sojae Examples include microorganisms of the Aspergillus genus, such as ). Soy sauce lactic acid bacteria are not particularly limited as long as they are the soy sauce lactic acid bacteria that are normally used in soy sauce production, but for example, Tetragenococcus halophilus ( Tetragenococcus halophilus Examples include salt-tolerant lactic acid bacteria such as )

[0037] In the process of obtaining soy sauce moromi (fermented soy sauce), if the amount of starchy raw materials such as wheat and rice among the soy sauce raw materials is small, the reducing sugar content will be low, and it may not be possible to obtain soy sauce moromi liquid that can properly carry out lactic acid fermentation. Therefore, it is preferable that the amount of starchy raw materials such as wheat and rice among the soy sauce raw materials be sufficient to obtain soy sauce moromi with a high reducing sugar content. However, this does not apply when soy sauce moromi with a high reducing sugar content is obtained by adding reducing sugar components, such as glucose, fructose, or maltose, to the soy sauce moromi.

[0038] In the process of obtaining soy sauce moromi liquid, the insoluble solids are removed from the soy sauce moromi (lactic acid fermented product) which contains insoluble solids derived from soy sauce raw materials such as soybeans and wheat, in order to obtain the soy sauce moromi liquid. The soy sauce moromi liquid obtained in this way can be called the liquid of the lactic acid fermented product or the liquid of the lactic acid fermented product of soy sauce koji. In this industry, soy sauce moromi obtained by lactic acid fermentation of soy sauce koji is clearly distinguished from aged moromi obtained by yeast fermentation of soy sauce moromi, and these are completely different. Generally, the lactic acid and alcohol content in soy sauce moromi, and the number of lactic acid bacteria and yeast are 0.0 w / v% to 1.0 w / v%, 0.0 v / v% to 0.5 v / v%, and 1 × 10⁻⁶, respectively. 6 CFU / mL ~ 1 x 10 9 CFU / mL and 1×10 2 CFU / mL ~ 1 x 10 6 The values ​​are CFU / mL; the lactic acid and alcohol content in the fermented mash, as well as the number of lactic acid bacteria and yeast, are 0.0 w / v% to 1.0 w / v%, 2.5 v / v% to 3.5 v / v%, and 10 CFU / mL to 1 × 10⁻¹⁶ CFU / mL, respectively. 3 CFU / mL and 10 CFU / mL ~ 1 × 10 4 The concentration is CFU / mL.

[0039] The method for obtaining soy sauce moromi mash liquid by removing insoluble solid components from soy sauce moromi mash is not particularly limited, and examples thereof include generally known solid-liquid separation methods. Specific examples thereof include pressing treatment and filtration treatment that are ordinarily used in methods for producing soy sauce, and more specific examples include pressing treatment using a pressing device such as a press, filtration treatment using a filter medium such as diatomaceous earth or a filter cloth, press filtration treatment in which filtration treatment is performed using a pressing device such as a press, and membrane filtration treatment using various permeable membranes such as UF membranes and MF membranes. The solid-liquid separation method may be a single type of these or a combination of two or more types, but a combination of pressing treatment using a pressing device and filtration treatment using a filter medium is preferable.

[0040] Soy sauce moromi mash usually has a certain viscosity, and the viscosity is approximately 1,000 cP to 1,500 cP. By removing most of the insoluble solid components from the soy sauce moromi mash, the viscosity of the soy sauce moromi mash liquid is significantly reduced. The viscosity of the soy sauce moromi mash liquid is not particularly limited as long as it is lower than that of the used soy sauce moromi mash. For example, the viscosity is preferably 500 cP or less, more preferably 100 cP or less, still more preferably 50 cP or less, and even more preferably 20 cP or less. The viscosity is measured by the method described in the Examples below.

[0041] Soy sauce moromi mash liquid is contaminated with yeast and other microorganisms together with soy sauce lactic acid bacteria, and if the number of other microorganisms is large, there is a risk that the subsequent lactic acid fermentation will not proceed properly. Therefore, when obtaining soy sauce moromi mash liquid, it is preferable to adopt a method that can remove most microorganisms together with insoluble solid components. In order to confirm that microorganisms have been removed from the soy sauce moromi mash liquid, for example, when lactic acid bacteria and yeast are used as indicators, in the soy sauce moromi mash liquid, the bacterial count of lactic acid bacteria is, for example, 1.0×10 8 cells / mL or less, preferably 1.0×10 7 cells / mL or less, more preferably 1.0×10 6 cells / mL or less, even more preferably; the cell count of yeast is, for example, 1.0×10 6 cells / mL or less, preferably 1.0×10 5It is more preferable that the number of particles / ml or less is 1.0 × 10 4 It is even more preferable that the number of particles / ml or less is less.

[0042] The process of performing lactic acid fermentation with pH adjustment involves adding soy sauce lactic acid bacteria to the soy sauce moromi liquid, adjusting the pH to a certain range, and carrying out lactic acid fermentation while stirring at 10°C to 40°C. The pH range should be 5.0 to 7.0, whichever does not hinder the growth of soy sauce lactic acid bacteria and / or the production of lactic acid. However, to prevent alkaline denaturation due to a high pH, ​​a range of 5.0 to 6.5 is preferable, and 5.2 to 6.5 is more preferable.

[0043] When soy sauce mash is subjected to lactic acid fermentation, the pH of the fermented liquid decreases due to the lactic acid produced. To raise the decreased pH, an alkaline agent is added. The alkaline agent is not particularly limited and examples include sodium carbonate, sodium hydroxide, potassium hydroxide, sodium bicarbonate, potassium carbonate, disodium phosphate, trisodium phosphate, sodium pyrophosphate, sodium polyphosphate, ammonium carbonate, calcium carbonate, magnesium carbonate, and magnesium hydroxide. However, sodium carbonate, sodium hydroxide, and potassium hydroxide, which are commonly used in food production, are preferred as alkaline agents, and sodium hydroxide is more preferred. The alkaline agent may be one of these alone or a combination of two or more.

[0044] The method of pH adjustment is not particularly limited. For example, the pH of the fermentation liquid may be continuously monitored and an alkaline agent added each time (pH stat method), or the fermentation liquid may be periodically sampled and an alkaline agent added after confirming that the measured pH is below the lower limit (5.0).

[0045] If the pH of the fermentation liquid becomes too low, the soy sauce lactic acid bacteria may die. Therefore, it is preferable that the pH of the fermentation liquid not fall below 4.5, and more preferably not fall below 4.8.

[0046] The duration of lactic acid fermentation is not particularly limited as long as the amount of lactic acid produced is 2.5 w / v% or more, but it is preferably a period during which the amount of lactic acid produced is 4.0 w / v% or more, more preferably a period during which the amount of lactic acid produced is 5.0 w / v% or more, and even more preferably a period during which the amount of lactic acid produced reaches its maximum. For example, referring to the amount of lactic acid produced and the fermentation period in Example 1 of the Examples described later, the duration of lactic acid fermentation is preferably 100 hours or more, more preferably 130 hours or more, even more preferably 150 hours or more, and even more preferably 200 hours or more. Furthermore, since soy sauce with a lactic acid content of 5.0 w / v% or more can be obtained by continuing lactic acid fermentation for 10 days while adjusting the pH, it is preferable to carry out the lactic acid fermentation for 30 days or less. The amount of lactic acid produced may be checked continuously by checking the amount of lactic acid in the fermentation liquid, or it may be checked periodically by sampling and measuring the amount of lactic acid each time.

[0047] The stirring is not particularly limited as long as it is done in a way that makes the pH of the fermentation liquid uniform, but it is preferable to stir with an impeller at several tens of rpm, preferably at 20 rpm to 100 rpm, and more preferably at 40 rpm to 80 rpm. However, if the stirring speed is too high, the dissolved oxygen concentration will increase, which may suppress the amount of lactic acid produced due to the rapid rise of yeast, so it is preferable that the stirring speed be less than 100 rpm. Furthermore, since the soy sauce moromi liquid has a lower viscosity than soy sauce moromi, lactic acid fermentation using soy sauce moromi liquid has the advantage that stirring can be performed with less power.

[0048] Lactic acid fermentation can be carried out in an open system, that is, in a well-ventilated environment without lids or stoppers on the fermentation containers (bottles, barrels, tanks, etc.), just like in the conventional brewing method of soy sauce production, or it can be carried out in a closed system.

[0049] In the process of carrying out lactic acid fermentation with pH adjustment, the soy sauce moromi liquid from which insoluble solids have been removed in advance is used. Therefore, the product obtained after lactic acid fermentation is a lactic acid fermented liquid with a low solid content, and this can be used as soy sauce itself. Alternatively, for purposes such as removing lactic acid bacteria and residues from the lactic acid fermented liquid, the lactic acid fermented liquid may be subjected to processes such as pressing, filtration, and pasteurization, which are used in the conventional soy sauce manufacturing method, and the resulting liquid portion may be used as soy sauce.

[0050] Specific examples of the method according to one aspect of the present invention include, but are not limited to, the following methods. A mixture of steamed soybeans and crushed roasted wheat is mixed with Aspergillus soybeans. Aspergillus sojae The starter koji is inoculated, and the koji is made by aeration at 10°C to 40°C for 1 to 4 days to obtain soy sauce koji. Then, 100 parts by mass of soy sauce koji is added to 50 to 200 parts by mass of saline solution with a salt concentration of 15% (w / v) to 35% (w / v), and soy sauce lactic acid bacteria ( Tetragenococcus halophilus The mixture is then fermented and aged at 10°C to 40°C for 10 to 200 days, stirring as needed, to obtain soy sauce moromi.

[0051] Next, the obtained soy sauce moromi is subjected to a pressing process using a vertical press-type pressing device, and then filtered with diatomaceous earth to obtain soy sauce moromi liquid. The pH of the obtained soy sauce moromi liquid is adjusted to approximately 6.0.

[0052] Next, soy sauce lactic acid bacteria ( Tetragenococcus halophilus The mixture to which the added lactic acid fermentation agent is added is subjected to lactic acid fermentation. Lactic acid fermentation is carried out at 10°C to 40°C while stirring with a stirring blade (20 rpm to 80 rpm). During lactic acid fermentation, a portion of the fermentation liquid is periodically sampled and the pH and lactic acid concentration are measured. If the measured pH value falls below 5.2, sodium hydroxide is added to the fermentation liquid to adjust the pH to approximately 6.0. When the lactic acid concentration reaches 2.5 w / v% or higher, lactic acid fermentation is terminated.

[0053] Next, the lactic acid fermented product is either left as is or subjected to solid-liquid separation, and then heated to obtain soy sauce. The soy sauce obtained in this way is a superior soy sauce with a stronger umami and richness.

[0054] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples, and can take various forms as long as it can solve the problems of the present invention. [Examples]

[0055] [Example 1: Production of high-lactic acid soy sauce] A mixture of steamed soybeans and crushed roasted wheat in a 6:4 ratio, to which Aspergillus soybeans ( Aspergillus sojae The starter koji was inoculated, and koji production was carried out by conventional methods for 43 hours to obtain soy sauce koji.

[0056] 100 parts by mass of the obtained soy sauce koji are added to 94 parts by mass of saline solution (salt concentration 24% (w / v)), and soy sauce lactic acid bacteria ( Tetragenococcus halophilus The mixture was then subjected to lactic acid fermentation at 15°C to 25°C for 20 days, stirring as needed, according to conventional methods. The soy sauce mash (viscosity 1,350 cP) after lactic acid fermentation was pressed and subjected to filtration using a diatomaceous earth filter to obtain the pressed liquid (viscosity 10.7 cP). Viscosity was measured at room temperature using a digital B-type viscometer "DV2T" (manufactured by Eiko Seiki Co., Ltd.). For reference, the viscosity of commercially available dark soy sauce is 10.42 cP, and the viscosity of water is 5.31 cP.

[0057] Soy sauce lactic acid bacteria culture solution contains Tetragenococcus halophilus, a type of soy sauce lactic acid bacteria. Tetragenococcus halophilus The solution was prepared by inoculating the solution into salt-containing YPG medium and culturing it at 20°C to 30°C for 3 to 7 days.

[0058] The pH of the pressed juice (at room temperature) was adjusted to 6.0 using sodium hydroxide. Soy sauce lactic acid bacteria culture solution was added to the pH-adjusted pressed juice (final bacterial count: 1 × 10⁶).6 The sample was subjected to fermentation at 25°C (CFU / mL). During fermentation, the fermentation liquid (160 L) was slowly stirred with a stirring blade (60 rpm) without the addition of pressurized air.

[0059] Samples were taken during the fermentation process, and the pH, lactic acid concentration, and turbidity were measured. The pH was measured using a "Glass Electrode Hydrogen Ion Concentration Indicator HM-41X" (manufactured by Toa DKK Co., Ltd.). The lactic acid concentration was measured using the enzyme electrode method with a "Biosensor BF-7" (manufactured by Oji Keisoku Co., Ltd.). Turbidity was measured using a "Turbidimeter UT-21" (manufactured by Corona Electric Co., Ltd.).

[0060] If the pH value of the fermentation liquid measured by sampling dropped to 5.2 or below, sodium hydroxide was added to the fermentation liquid to readjust its pH to 6.0.

[0061] The fermentation process was terminated when the lactic acid concentration of the fermented liquid, measured by sampling, reached 5.0 w / v%, to obtain soy sauce with a high lactic acid concentration (high-lactic acid soy sauce).

[0062] Table 1 shows the results of measuring the pH value, lactic acid concentration, and turbidity of the pressed juice before fermentation and the high-lactic acid soy sauce after fermentation. Figure 1 shows the results of measuring the pH value and lactic acid concentration of the fermented liquid over time by sampling during the fermentation process.

[0063] [Table 1]

[0064] As shown in Table 1, by repeatedly adjusting the pH of the pressed liquid obtained from lactic acid fermentation in the traditional brewing method of soy sauce production, it was possible to raise the concentration of lactic acid produced as a lactic acid fermentation product to 2.5 w / v% or higher without external addition. In addition, it was possible to increase the lactic acid concentration.

[0065] [Example 2. Sensory evaluation of clarified high-lactic acid soy sauce] High-lactic acid soy sauce (turbidity 6,000 ppm) was produced in the same manner as in Example 1. The obtained high-lactic acid soy sauce was subjected to centrifugation to remove lactic acid bacteria cells from the high-lactic acid soy sauce, thereby producing clarified high-lactic acid soy sauce (turbidity less than 10 ppm; lactic acid concentration 4.7 w / v%). Next, the clarified high-lactic acid soy sauce was added to the pressed juice (lactic acid concentration 0.68 w / v%) produced in Example 1 to produce lactic acid-adjusted lactic acid soy sauce with lactic acid concentrations of 1.7 w / v%, 2.7 w / v%, and 3.7 w / v%. The pH of the clarified high-lactic acid soy sauce and lactic acid-adjusted lactic acid soy sauce was adjusted to 4.88, which is the pH of the pressed juice.

[0066] Sensory evaluations were conducted on pressed soy sauce, lactic acid-adjusted lactic acid soy sauce, and clarified high-lactic acid soy sauce. Six panelists with the ability to discern the taste of soy sauce took a spoonful of room-temperature soy sauce and tasted it. Using pressed soy sauce as an index, they evaluated the intensity of "saltiness," "initial umami," "aftertaste umami," "richness," "initial harshness," and "unnatural taste" on a 5-point scale. The scoring ranged from -2 to +2 points, with pressed soy sauce being 0 points. The mean and standard deviation were calculated from the panel's scores, and statistical tests were performed.

[0067] The results of the sensory evaluation are shown in Table 2 and Figure 2. In Table 2, "*" indicates a significant difference was observed at a significance level of 5%, and "**" indicates a significant difference was observed at a significance level of 1%.

[0068] [Table 2]

[0069] As shown in Table 2 and Figure 2, the clarified high-lactic acid soy sauce exhibited statistically significant desirable flavors, including umami in the initial taste, umami in the aftertaste, and richness. Furthermore, the clarified high-lactic acid soy sauce exhibited less of the undesirable flavors, such as harshness in the initial taste and an unnatural taste, while still having a moderate saltiness. As a result, the clarified high-lactic acid soy sauce had an overall superior taste. In addition, sensory evaluation of lactic acid-adjusted lactic acid soy sauce revealed that the taste of lactic acid soy sauce tends to improve with increasing lactic acid concentration.

[0070] [Example 3. Sensory evaluation of soy sauce with externally added lactic acid] In Example 1, sodium lactate was added to the pressed juice (lactic acid concentration of 0.68 w / v%) to produce externally added lactic acid soy sauce with lactic acid concentrations of 1.7 w / v%, 2.7 w / v%, 3.7 w / v%, and 4.7 w / v%. The pH of the externally added lactic acid soy sauce was adjusted to 4.88, the same as the pH of the pressed juice.

[0071] Sensory evaluation was performed on the pressed juice and the externally added lactic acid soy sauce in the same manner as in Example 2. The results are shown in Table 3A and Figure 3.

[0072] [Table 3A]

[0073] As shown in Table 3A and Figure 3, in soy sauce with externally added lactic acid, the umami aftertaste became stronger as the amount of sodium lactate added increased, but at the same time, an excessive saltiness was felt. Furthermore, as the amount of sodium lactate added increased, there was a tendency for undesirable tastes such as a harshness in the initial taste and an unnatural flavor to be felt. Thus, although it was possible to increase the lactic acid content without changing the pH by adding sodium lactate to the pressed juice, the resulting product did not have a natural flavor.

[0074] Furthermore, statistical tests were conducted using the sensory evaluation results for the lactic acid-adjusted lactic acid soy sauce and the clarified high-lactic acid soy sauce produced in Example 2, as well as the sensory evaluation results for the externally added lactic acid soy sauce. The results are shown in Table 3B.

[0075] [Table 3B]

[0076] As shown in Table 3B, statistically significant differences were observed among these in terms of saltiness, richness, harshness of initial taste, and unnatural flavor. Specifically, the lactic acid-adjusted lactic acid soy sauce and clarified high-lactic acid soy sauce produced in Example 2 had statistically significantly more desirable flavors such as richness, statistically significantly less undesirable flavors such as harshness of initial taste and unnatural flavor, and also had a reduced saltiness compared to the externally added lactic acid soy sauce with added sodium lactate.

[0077] Based on these results, the lactic acid-adjusted lactic acid soy sauce and the clarified high-lactic acid soy sauce produced in Example 2 had superior taste compared to the lactic acid soy sauce with externally added lactic acid. It is presumed that the lactic acid-adjusted lactic acid soy sauce and the clarified high-lactic acid soy sauce produced in Example 2 have a more natural richness compared to the lactic acid soy sauce with externally added lactic acid because they contain a complex mixture of various organic acids, including lactic acid, produced by lactic acid fermentation.

[0078] [Example 4. Sensory evaluation of high-lactic acid soy sauce] Using the high-lactic acid soy sauce (turbidity 6,000 ppm) and clarified high-lactic acid soy sauce (turbidity less than 10 ppm) produced in Example 2, turbidity-adjusted lactic acid soy sauces were produced by adding high-lactic acid soy sauce to the clarified high-lactic acid soy sauce to adjust the turbidity to 500 ppm, 1,000 ppm, 3,000 ppm, and 5,000 ppm.

[0079] Sensory evaluations were conducted on clarified high-lactic acid soy sauce, turbidity-adjusted lactic acid soy sauce, and high-lactic acid soy sauce. For the sensory evaluation, five panelists with the ability to discern the taste of soy sauce took a spoonful of room-temperature soy sauce and tasted it. Using clarified high-lactic acid soy sauce as the index, they evaluated the intensity of the taste in five categories: sweetness, saltiness, bitterness, umami, richness, meatiness, and smoothness, using a 5-point scoring system. The scoring ranged from -2 to +2 points, with clarified high-lactic acid soy sauce being 0 points. The mean and standard deviation were calculated from the panel's scores, and statistical tests were performed.

[0080] The results of the sensory evaluation are shown in Table 4 and Figure 4. In Table 4, "*" indicates a significant difference was observed at a significance level of 5%, and "**" indicates a significant difference was observed at a significance level of 1%.

[0081] [Table 4]

[0082] As shown in Table 4 and Figure 4, high-lactic acid soy sauce exhibited statistically significant umami, richness, meatiness, and mellowness, while also possessing a noticeable sweetness, resulting in desirable flavor profiles. Furthermore, high-lactic acid soy sauce exhibited less of the undesirable bitterness and reduced saltiness. As a result, high-lactic acid soy sauce had an overall superior flavor profile. In addition, sensory evaluation of turbidity-adjusted lactic acid soy sauce revealed that the flavor profile of lactic acid soy sauce tended to improve with increasing turbidity.

[0083] From the above results, it was found that continuous lactic acid fermentation using pressed juice yields a highly palatable lactic acid soy sauce with a unique and desirable taste due to the high content of soy sauce lactic acid bacteria. It should be noted that when using animal-derived lactic acid bacteria or pickling lactic acid bacteria, the flavor is impaired by a distinctive odor such as pickling odor. However, high-lactic acid soy sauce and clarified high-lactic acid soy sauce, due to their high content of soy sauce lactic acid bacteria, possessed a natural, soy sauce-like flavor. Furthermore, while externally added lactic acid soy sauce with added sodium lactate had an excessively emphasized saltiness due to the influence of sodium ions, high-lactic acid soy sauce, due to its inclusion of soy sauce lactic acid bacteria, had a milder flavor with reduced saltiness.

[0084] [Example 5. Evaluation of the effect of yeast in the production of high-lactic acid soy sauce] Soy sauce yeast culture solution contains Digosaccharomyces luxii ( Zygosaccharomyces rouxii The solution was prepared by inoculating the solution into salt-containing YG medium and culturing it at 20°C to 30°C for 1 to 3 days.

[0085] The pH of the pressed juice produced in Example 1 was adjusted to 6.0 by adding sodium hydroxide. The pH-adjusted pressed juice was then mixed with soy sauce yeast culture solution and soy sauce lactic acid bacteria culture solution prepared in Example 1, and subjected to fermentation at 25°C. During the fermentation process, no pressurized air was added, and the mixture was slowly stirred with a stirring blade (60 rpm).

[0086] Samples were taken during the fermentation process, and the pH value, lactic acid concentration, alcohol concentration, viable lactic acid bacteria count, and viable yeast count of the fermentation liquid were measured. The alcohol concentration was measured using "GAS CHROMATOGRAPH GC-2014" (Shimadzu Corporation). The viable lactic acid bacteria count was measured by inoculating a diluted fermentation liquid onto MRS agar medium and culturing it at 30°C for 7 days. The viable yeast count was measured by inoculating a diluted fermentation liquid onto YG agar medium and culturing it at 30°C for 3 days.

[0087] If the pH value of the fermentation liquid measured by sampling dropped to 5.2 or below, sodium hydroxide was added to the fermentation liquid to readjust its pH to 6.0.

[0088] The fermentation process was terminated when the lactic acid concentration of the fermented liquid, measured by sampling, reached 5.0 w / v%, to obtain high-lactic acid soy sauce.

[0089] Table 5 shows the measurement results of various values ​​of the fermentation liquid over time, obtained by sampling during the fermentation process.

[0090] [Table 5]

[0091] As shown in Table 5, it was found that by using the pressed juice, even in the presence of yeast, the number of viable yeast cells and alcohol concentration hardly increased, while the number of viable lactic acid bacteria and lactic acid concentration increased, resulting in the production of high-lactic acid soy sauce.

[0092] In continuous lactic acid fermentation using pressed juice, pH adjustment was sufficiently achieved even with weak stirring, and lactic acid levels increased while suppressing yeast growth. However, when using soy sauce mash instead of pressed juice, strong stirring with pressurized air or similar is required to adjust the pH. In this case, similar to the conventional brewing method for soy sauce, yeast proliferated, alcohol was produced, and almost no lactic acid was produced (lactic acid concentration less than 2.0 w / v%). [Industrial applicability]

[0093] One embodiment of the present invention, when used as a seasoning, can impart a desirable flavor to the food it is used with through the complex mixing and fermentation of the soy sauce ingredients and lactic acid or lactic acid and lactic acid bacteria. Cross-reference to related applications

[0094] This application claims priority to Japanese Patent Application No. 2021-149272, filed on 14 September 2021, the entirety of which is incorporated herein by reference.

[0095] Furthermore, the entirety of all documents referenced in the detailed description of the present invention, including Patent Document 1, is incorporated herein by reference.

Claims

1. Soy sauce having a lactic acid content of 2.5 w / v% or more, and being a lactic acid fermented product of the pressed liquid of soy sauce moromi.

2. The soy sauce according to claim 1, wherein the lactic acid fermented product of the pressed liquid of soy sauce moromi is a lactic acid fermented product of the pressed liquid of soy sauce moromi by Tetragenococcus halophilus, a soy sauce lactic acid bacterium.

3. The soy sauce according to claim 2, wherein the soy sauce contains the soy sauce lactic acid bacteria such that the turbidity is 500 ppm or more.

4. A process of subjecting soy sauce moromi to a solid-liquid separation treatment to obtain soy sauce moromi liquid, The process involves subjecting the aforementioned soy sauce moromi liquid to lactic acid fermentation by soy sauce lactic acid bacteria while adjusting the pH to 5.0 to 7.0 using an alkaline agent, in order to obtain soy sauce having a lactic acid content of 2.5 w / v% or more. A method for manufacturing soy sauce, including the method described above.

5. The method for producing soy sauce according to claim 4, wherein the alkaline agent is at least one alkaline agent selected from the group consisting of sodium carbonate, sodium hydroxide, and sodium bicarbonate.

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