Natto sauce and its manufacturing method, natto products, method for improving the foaming properties of natto, and method for increasing the amount of foam in natto.

Abstract

The present invention provides a natto sauce that, when added to natto and stirred, can improve foaming ability and / or the amount of foam produced compared to conventional sauces. [Solution] A method for producing natto sauce, comprising the steps (1) and (2) below. (1) A step of preparing a composition that satisfies the following (i) and (ii). (i) Contains 0.1% by mass or more of starch hydrolysates with a dextrose equivalent value of 50 or less. (ii) The water activity is 0.98 or less. (2) A step of heating the composition of (1) to a maximum temperature of 70 to 130°C for one minute or more.

Description

[[TECHNICAL FIELD]]

[0001] The present invention relates to natto sauce, a method for producing the same, a natto product, a method for improving the foamability of natto, and a method for increasing the amount of foam in natto. [[BACKGROUND ART]]

[0002] Natto is widely popular as a food having unique stringiness and flavor produced by fermentation with Bacillus subtilis natto. Natto is often stirred with chopsticks or the like before eating, and the resulting state of stringiness, viscosity, and foamability can affect the appearance, mouthfeel, and satisfaction during eating. In addition, natto sauce attached to natto is normally formulated and designed from the viewpoints of seasoning, storage stability, productivity and the like (Patent Document 1). [[PRIOR ART DOCUMENT]] [[PATENT DOCUMENT]]

[0003] [[Patent Document 1]] Japanese Unexamined Patent Application Publication No. 2017-046668 [[SUMMARY OF THE INVENTION]] [[Problem to be Solved by the Invention]]

[0004] However, conventional natto sauces have not been sufficiently designed from the viewpoint of actively improving foamability when added to natto and stirred. In addition, simply adding saccharides, viscosity-increasing components, proteins or the like sometimes makes it difficult to improve the foamability of natto or increase the amount of foam in natto.

[0005] The present invention has been made in view of the above circumstances. That is, an object of one aspect of the present invention is to provide a natto sauce that can improve foamability more than conventional ones when added to natto and stirred. Another object of one aspect of the present invention is to provide a natto sauce that can improve the amount of foam more than conventional ones. A further object of one aspect of the present invention is to provide a natto sauce that makes it easier for natto to spread when mixed with natto and poured over cooked rice.

[0006] Furthermore, the description of these problems does not preclude the existence of other problems. Moreover, each aspect of the present invention does not need to solve all of these problems. It is possible to extract other problems from the description in the specification, drawings, and claims. [Means for solving the problem]

[0007] In view of the above problems, the present inventors conducted diligent studies and found that by subjecting a composition containing a predetermined amount or more of starch hydrolysate with a DE (Dextrose Equivalent) value of less than or equal to a predetermined value, and having a water activity of less than or equal to a predetermined value, to a heat treatment at a predetermined temperature for a predetermined time or longer, it is possible to provide a natto sauce that can improve the foaming ability and / or the amount of foam when added to natto, and / or a natto sauce that can make natto spread more easily when mixed with natto and poured over rice, thereby solving the above problems and leading to the present invention.

[0008] In other words, the purpose of this invention relates, for example, to the following: [Item 1] A method for producing natto sauce, comprising the steps (1) and (2) below. (1) A step of preparing a composition that satisfies the following (i) and (ii). (i) Contains 0.1% by mass or more of starch hydrolysates with a dextrose equivalent value of 50 or less. (ii) The water activity is 0.98 or less. (2) A step of heating the composition of (1) to a maximum temperature of 70 to 130°C for one minute or more. [Item 2] The manufacturing method according to item 1, wherein the composition of (1) further satisfies (iii) below. (iii) The Brix value is 1 or greater. [Item 3] The manufacturing method according to item 1 or 2, wherein the composition of (1) further satisfies (iv) below. (iv) Contains 0.1% by mass or more of salt. [Item 4] The manufacturing method according to any one of items 1 to 3, wherein the composition of (1) further satisfies (v) below. (v) Contains 0.1% by mass or more of amino acids. [Item 5] The manufacturing method according to any one of items 1 to 4, wherein the composition of (1) further satisfies (vi) below. (vi) Contains albumin. [Item 6] The manufacturing method according to any one of items 1 to 5, wherein the composition of (1) further satisfies (vii) below. (vii) The γ-PGA content is 0.1% by mass or less. [Item 7] Natto sauce that satisfies the following conditions (i) to (iii). (i) Contains 0.1% by mass or more of starch hydrolysates with a dextrose equivalent value of 50 or less. (ii) The water activity is 0.98 or less. (iii) The ratio of the value β to the value α below when measured by the method α below ([value β] / [value α]) is 1.0 or less. [Value α]: Viscosity (cP) at 50°C. [Value β]: Viscosity (cP) at 80°C. <Method α> Using a Rapid Viscometer (RVA), 25g of the sample to be measured is heated from 50°C to 80°C at a heating rate of 12°C / min. [Item 8] The natto sauce according to item 7, wherein the [value α] measured by the above-mentioned method α is 1 cP or greater. [Item 9] Natto sauce according to item 7 or 8, which is added in amounts of 10 to 30 parts by mass per 100 parts by mass of natto. [Item 10] The natto sauce according to any one of items 7 to 9, wherein the starch hydrolysate is added to natto in an amount of 0.01 parts by mass or more per 100 parts by mass of natto. [Item 11] Natto sauce in a sealed container, wherein the natto sauce described in any one of items 7 to 10 is filled into a sealed container. [Item 12] A natto product comprising natto and natto sauce as described in any one of items 7 to 10 or packaged natto sauce as described in item 11. [Item 13] The natto product according to Item 12, wherein the natto product further comprises a rigid or semi-rigid container, and the natto is housed in the rigid or semi-rigid container. [Item 14] The natto product according to Item 12 or 13, wherein the foamability of natto is improved. [Item 15] The natto product according to any one of Items 12 to 14, wherein the amount of foam of natto is increased. [Item 16] A mixed natto with sauce comprising the natto sauce according to any one of Items 7 to 10 and natto, wherein the gas content is 5% by volume or more. [Item 17] A natto-topped food, wherein the mixed natto with sauce according to Item 16 is placed on a food. [Item 18] The natto-topped food according to Item 17, wherein the food is cooked rice. [Item 19] A method for improving foamability of natto, comprising the following steps (1) to (3): (1) A step of preparing a composition satisfying the following (i) and (ii). (i) Contains 0.1% by mass or more of a starch decomposition product having a dextrose equivalent value of 50 or less. (ii) Has a water activity of 0.98 or less. (2) A step of subjecting the composition of (1) to a heat treatment for 1 minute or longer such that the maximum temperature reaches 70 to 130°C. (3) A step of adding the composition of (2) to natto and stirring the mixture. [Item 20] A method for increasing the amount of foam of natto, comprising the following steps (1) to (3): (1) A step of preparing a composition satisfying the following (i) and (ii). (i) Contains 0.1% by mass or more of a starch decomposition product having a dextrose equivalent value of 50 or less. (ii) Has a water activity of 0.98 or less. (2) A step of subjecting the composition of (1) to a heat treatment for 1 minute or longer such that the maximum temperature reaches 70 to 130°C. (3) A step of adding the composition of (2) to natto and stirring the mixture. Effects of the Invention

[0009] According to the present invention, there is provided a natto sauce with improved foamability and / or foam amount when added to natto, and / or a natto sauce that can make natto easier to spread when mixed with natto and poured onto cooked rice. MODE FOR CARRYING OUT THE INVENTION

[0010] Hereinafter, the present invention will be described in detail with reference to specific embodiments. However, the present invention is not limited to the following embodiments, and can be implemented in any form without departing from the spirit of the present invention.

[0011] All patent publications, published patent application publications, and non-patent literature cited in the present disclosure are incorporated herein by reference in their entireties for all purposes.

[0012] In addition, in the present disclosure, the terms "contain" and "include" encompass the concepts of "containing", "including", "consisting essentially of", and "consisting only of". When the terms "contain" and "include" are used, the listed steps or options do not need to be exhaustive.

[0013] In addition, in the present disclosure, when a plurality of upper limits and / or a plurality of lower limits are provided for the definition of a numerical range, it is deemed that a definition of a numerical range combining at least the maximum value among upper limit definitions and the minimum value among lower limit definitions is directly described, even if not explicitly stated, and it is further deemed that all numerical ranges obtained by combining any upper limit among the upper limit values and any lower limit among the lower limit values are directly described. In addition, in the present disclosure, a numerical range connected by "~" means a numerical range that includes the numerical values before and after "~" as the lower limit and the upper limit. When a plurality of lower limits and a plurality of upper limits are separately set forth, any lower limit and any upper limit may be selected and connected by "~". In addition, ranges obtained by arbitrarily replacing the upper limit and / or lower limit of the above ranges are also exemplified in the present disclosure.

[0014] Furthermore, within this disclosure, the expression "and / or" encompasses both the meanings of "and" and "or." For example, "A and / or B" encompasses both the meanings of A and B and A or B, representing three possibilities: A alone, B alone, and both A and B.

[0015] Furthermore, in this disclosure, when "mass%" or "parts by mass" is used without further specification, it refers to the percentage based on wet mass. On the other hand, when "volume%" is used without further specification, it refers to the percentage based on volume.

[0016] Furthermore, the descriptions of problems and effects contained herein should not be construed as limiting the present invention in any way. That is, the present invention is not limited to solving one or more problems described herein or achieving one or more effects described herein, but encompasses any invention as defined by the appended claims. Moreover, the problems solved and / or effects achieved by the present invention are not limited to those explicitly stated herein, but encompass any problems and / or effects that a person skilled in the art can derive from the description herein and the appended claims.

[0017] [1. Method for manufacturing natto sauce] One aspect of the present invention relates to a method for producing natto sauce (hereinafter referred to as "the manufacturing method of the present invention" as appropriate). The manufacturing method of the present invention includes the following steps (1) and (2). (1) A step of preparing a composition that satisfies the following (i) and (ii). (i) Contains 0.1% by mass or more of starch hydrolysates with a dextrose equivalent value of 50 or less. (ii) The water activity is 0.98 or less. (2) A step of heating the composition of (1) to a maximum temperature of 70 to 130°C for one minute or more.

[0018] In this disclosure, "natto sauce" refers to a liquid or semi-liquid seasoning that is added to natto and consumed. In one embodiment, it is preferable that the sauce be liquid because it spreads easily and froths easily when poured over natto. Natto sauce may contain, for example, soy sauce, sugars, salt, amino acids, starch hydrolysates, water, and optionally albumin and other seasoning components. If soy sauce is included, it may be liquid soy sauce or powdered soy sauce. In one embodiment, liquid soy sauce is preferred. This is because powdered soy sauce often contains starch hydrolysates as an excipient, making it difficult to adjust the starch hydrolysate content of the natto sauce.

[0019] <Step (1): Preparation of the precursor composition> Step (1) is a step of preparing a composition (hereinafter referred to as "precursor composition") which (i) contains 0.1% by mass or more of a starch hydrolysate with a dextrose equivalent value of 50 or less, and (ii) has a water activity of 0.98 or less.

[0020] • Starch hydrolysates with a dextrose equivalent value below a specified value. In this disclosure, "starch hydrolysate" refers to a carbohydrate raw material obtained by decomposing starch with acid, enzymes, etc.

[0021] In this disclosure, the dextrose equivalent value (hereinafter sometimes referred to as the DE value) is an index indicating the degree of hydrolysis (low molecular weight reduction) of starch, and is a value expressed by converting the ratio of reducing sugar content to dry solids of starch into glucose. Generally, the lower the DE value, the higher the average molecular weight. The DE value of starch hydrolysates can be measured by the Lane-Einon method, which is determined by converting the ratio of reducing sugar content to dry solids of the starch hydrolysate into glucose.

[0022] According to one embodiment, the "precursor composition" is a composition containing 0.1% by mass or more of starch hydrolysates with a DE value of 50 or less. Using such a precursor composition may improve the foaming ability when added to natto and stirred. The details of the principle are not entirely clear, but it is thought that the low DE starch hydrolysates readily retain water near the gas-liquid interface and stabilize the foam film through interaction with natto-derived components.

[0023] According to one embodiment, the upper limit of the DE value of the starch hydrolysate is 50 or less. From the viewpoint that a lower DE value improves foam retention, the DE value of the starch hydrolysate may be, for example, 40 or less, 30 or less, 20 or less, 15 or less, or 10 or less. The lower limit of the DE value of the starch hydrolysate is not particularly limited, but from the viewpoint of solubility and handling, it may be, for example, 1 or more, 2 or more, 3 or more, or 4 or more. The above upper and lower limits can be any combination thereof, and the numerical range specified by combining these upper and lower limits is also disclosed in this disclosure. In other words, the DE values ​​of the starch hydrolysates are not limited to these ranges, but can be, for example, 1-50, 2-50, 3-50, 4-50, 1-40, 2-40, 3-40, 4-40, 1-30, 2-30, 3-30, 4-30, 1-20, 2-20, 3-20, 4-20, 1-15, 2-15, 3-15, 4-15, 1-10, 2-10, 3-10, or 4-10.

[0024] According to one embodiment, the origin of the starch hydrolysate with a DE value of 50 or less is not particularly limited. For example, those made from corn starch, potato starch, tapioca starch, sweet potato starch, wheat starch, rice starch, etc., can be used. Specific examples include maltodextrin, dextrin, starch syrup, powdered starch, etc. These may be used individually or in combination of two or more.

[0025] According to one embodiment, the lower limit of the content of starch hydrolysates with a DE value of 50 or less in the precursor composition is 0.1% by mass or more from the viewpoint of improving foaming properties. In particular, it can be 0.2% by mass or more, 0.5% by mass or more, 1% by mass or more, 2% by mass or more, or 5% by mass or more. On the other hand, the upper limit of the content of starch hydrolysates with a DE value of 50 or less in the precursor composition is not limited, but from the viewpoint of taste balance and viscosity, it can be, for example, 60% by mass or less, and furthermore, 50% by mass or less, 40% by mass or less, 35% by mass or less, 30% by mass or less, 25% by mass or less, 20% by mass or less, or 15% by mass or less. The above upper and lower limits can be any combination of each other, and the numerical ranges that can be specified by combining these upper and lower limits are also disclosed in this disclosure. In other words, the range of starch hydrolysate content with a DE value of 50 or less in the composition is not limited to these, but for example, 0.1-60% by mass, 0.2-60% by mass, 0.5-60% by mass, 1-60% by mass, 2-60% by mass, 5-60% by mass, 0.1-50% by mass, 0.2-50% by mass, 0.5-50% by mass, 1-50% by mass, 2-50% by mass, 5-50% by mass, 0.1-40% by mass, 0.2-40% by mass, 0.5-40% by mass, 1-40% by mass, 2-40% by mass, 5-40% by mass, 0.1-35% by mass, 0.2-35% by mass, 0.5-35% by mass, 1-3 5% by mass, 2-35% by mass, 5-35% by mass, 0.1-30% by mass, 0.2-30% by mass, 0.5-30% by mass, 1-30% by mass, 2-30% by mass, 5-30% by mass, 0.1-25% by mass, 0.2-25% by mass, 0.5-25% by mass, 1-25% by mass, 2-25% by mass, 5-2 It can be 5% by mass, 0.1-20% by mass, 0.2-20% by mass, 0.5-20% by mass, 1-20% by mass, 2-20% by mass, 5-20% by mass, 0.1-15% by mass, 0.2-15% by mass, 0.5-15% by mass, 1-15% by mass, 2-15% by mass, or 5-15% by mass.

[0026] In this disclosure, the content of starch hydrolysates with a DE value of 50 or less in the precursor composition can be controlled by adjusting the amount of the starch hydrolysates themselves. Furthermore, both the DE value and the content can be suitably adjusted by using multiple starch hydrolysates with different DE values ​​in combination, or by adjusting the amounts of sugars and water.

[0027] In this disclosure, the content of starch hydrolysates with a DE value of 50 or less in any composition can be calculated based on the amount of starch hydrolysates with a DE value of 50 or less that were added during the production of the composition. If the amount added is unknown, the carbohydrate fraction can be extracted from the composition, fractionated by liquid chromatography, size exclusion chromatography, gel permeation chromatography, etc., and the dry solid content and dextrose-equivalent reducing sugar content can be measured for each fraction. The amount of fraction with a DE value of 50 or less, calculated using the following formula, can then be estimated as the equivalent amount of starch hydrolysates with a DE value of 50 or less. DE value = Dextrose-equivalent reducing sugar content / Dry solids content × 100 Dextrose-equivalent reducing sugar content can be measured using the Lane-Einon method.

[0028] ·Water activity In this disclosure, "water activity" is an index representing the degree of free water in a composition, and is the value obtained by dividing the water vapor pressure of the composition by the water vapor pressure of pure water at the same temperature. In this disclosure, the water activity of a given composition is the value measured at 25°C using a water activity meter. Specifically, the composition is placed in a sealed cell, and the displayed value after reaching equilibrium is adopted as the water activity.

[0029] According to one embodiment, the water activity of the precursor composition is 0.98 or less. In particular, it may be 0.97 or less, 0.96 or less, 0.95 or less, 0.94 or less, or 0.93 or less. This makes it easier to ensure storage stability and may also have the effect of increasing the amount of foam after heat treatment. The principle is not entirely clear, but it is thought that when the water activity of the aqueous solution decreases, the amount of free water in the continuous phase decreases, and the liquid film drainage rate, bubble coalescence rate, and inter-bubble gas transfer rate all decrease, which makes it easier for the viscosity and extensional viscosity of the continuous phase to increase, and even if gas is introduced into the liquid during stirring, the thin liquid film that has been formed does not break immediately, and the disappearance of foam is less likely to occur. On the other hand, the lower limit of the water activity of the precursor composition is not particularly limited, but from the viewpoint of taste, fluidity, and blending flexibility, it may be 0.70 or more, 0.75 or more, 0.80 or more, 0.85 or more, or 0.90 or more. The above upper and lower limits can be any combination of each other, and the numerical ranges that can be determined by combining these upper and lower limits are also disclosed in this disclosure. That is, the range of water activity of the precursor composition is not limited to these, but for example, 0.70~0.98, 0.75~0.98, 0.80~0.98, 0.85~0.98, 0.90~0.98, 0.70~0.97, 0.75~0.97, 0.80~0.97, 0.85~0.97, 0.90~0.97, 0.70~0.96, 0.75~0.96, 0.80~0.96, 0.85~0 It can be 0.96, 0.90-0.96, 0.70-0.95, 0.75-0.95, 0.80-0.95, 0.85-0.95, 0.90-0.95, 0.70-0.94, 0.75-0.94, 0.80-0.94, 0.85-0.94, 0.90-0.94, 0.70-0.93, 0.75-0.93, 0.80-0.93, 0.85-0.93, or 0.90-0.93.

[0030] The water activity of the precursor composition can be adjusted by reducing the amount of water, increasing the amount of soluble solids such as starch hydrolysates, sugars, salts, and amino acids, or by using a combination of these methods. A concentration step may also be employed if necessary. Furthermore, the water activity of the precursor composition may decrease due to the solutes such as starch hydrolysates, sugars, salts, and amino acids. In particular, using sugars and salts in combination makes it easier to adjust the water activity to the desired level while maintaining the taste balance of the precursor composition.

[0031] • Brix value The precursor composition preferably contains sugars. The Brix value of the precursor composition is not particularly limited, but from the viewpoint of improving the foam retention of natto, the lower limit of the Brix value of the precursor composition can be, for example, 1 or more, and further can be 5 or more, 10 or more, 20 or more, or 30 or more. The details of this principle are not entirely clear, but it is thought that when the Brix value is above a certain level, the continuous phase becomes highly viscous, slowing down the drainage from the foam film, and furthermore, the osmotic resistance caused by the solute concentration gradient prevents the rapid thinning of the liquid film, delaying the rupture of the foam film and improving foam retention. In addition, according to one embodiment, the upper limit of the Brix value of the precursor composition is not limited to this, but from the viewpoint of maintaining a balance of taste, it can be, for example, 60 or less, and further can be 55 or less, 50 or less, 45 or less, or 40 or less. The above upper and lower limits can be any combination of each other, and the numerical range specified by combining these upper and lower limits is also disclosed in this disclosure. In other words, the range of Brix values ​​for the precursor composition is not limited to these, but can be, for example, 1-60, 5-60, 10-60, 20-60, 30-60, 1-55, 5-55, 10-55, 20-55, 30-55, 1-50, 5-50, 10-50, 20-50, 30-50, 1-45, 5-45, 10-45, 20-45, 30-45, 1-40, 5-40, 10-40, 20-40, or 30-40.

[0032] The origin of the Brix value of the precursor composition is not particularly limited and may be achieved by including starch hydrolysates, glucose, fructose, fructose-glucose syrup, glucose-fructose syrup, sugar, maltose, lactose, trehalose, sugar alcohols, oligosaccharides, honey, fruit juice, vegetable juice, fermented seasonings, mirin, or other food carbohydrates. Furthermore, the Brix value may also be achieved by sugars introduced from other food materials.

[0033] Brix values ​​can be measured using a Brix meter.

[0034] ·salt The precursor composition preferably contains salt. In this disclosure, unless otherwise specified, "salt" means the amount of salt equivalent calculated from the sodium content. The salt content is the value obtained by multiplying the sodium content, measured in accordance with the standards of the "Standard Tables of Food Composition in Japan (8th Revised Edition) Supplement 2023," by 2.54.

[0035] The salt content of the precursor composition is not particularly limited. However, according to one embodiment, the lower limit of the salt content of the precursor composition can be, for example, 0.1% by mass or more, and further, 0.5% by mass or more, 1% by mass or more, or 3% by mass or more, from the viewpoint of improving the taste of natto while enhancing foaming ability. The details of the principle by which foaming ability can be enhanced by setting the salt content above the above lower limit are not necessarily clear, but it is thought that by including a certain amount of salt, the electrostatic repulsion between interfaces is weakened, making it easier for bubbles to come together and form complex bubbles. On the other hand, the upper limit of the salt content is not particularly limited, but according to one embodiment, from the viewpoint of taste balance and foam retention, it can be, for example, 30% by mass or less, and further, 25% by mass or less, 20% by mass or less, 15% by mass or less, 10% by mass or less, or 8% by mass or less. Although the details of the principle behind the increased foam retention are not entirely clear, it is believed that excessively high salt content affects the hydration or dispersion state of proteins, polysaccharides, poly-γ-glutamic acid, etc., in the composition, thereby reducing the stability of the foam film. The above upper and lower limits can be any combination of these, and the numerical ranges that can be determined by combining these upper and lower limits are also disclosed in this disclosure. In other words, the salt content of the precursor composition is not limited to these ranges, but can be, for example, 0.1-30% by mass, 0.5-30% by mass, 1-30% by mass, 3-30% by mass, 0.1-25% by mass, 0.5-25% by mass, 1-25% by mass, 3-25% by mass, 0.1-20% by mass, 0.5-20% by mass, 1-20% by mass, 3-20% by mass, 0.1-15% by mass, 0.5-15% by mass, 1-15% by mass, 3-15% by mass, 0.1-10% by mass, 0.5-10% by mass, 1-10% by mass, 3-10% by mass, 0.1-8% by mass, 0.5-8% by mass, 1-8% by mass, or 3-8% by mass.

[0036] The source of the salt is not particularly limited and may be derived from table salt (sodium chloride), rock salt, sea salt, salty seasonings, soy sauce, miso, fish sauce, fermented seasonings, yeast extract, meat extract, seafood extract, vegetable extract, kelp extract, etc. Furthermore, the salt content may be adjusted by including these components individually or in combination of two or more, or it may be achieved by salt introduced from other food ingredients.

[0037] ·amino acid The precursor composition preferably contains amino acids. The amino acid content of the precursor composition is not particularly limited. However, according to one embodiment, the lower limit of the amino acid content of the precursor composition can be, for example, 0.1% by mass or more, and further can be 0.5% by mass or more, 1% by mass or more, or 2% by mass or more, from the viewpoint of imparting a moderate umami flavor. On the other hand, the upper limit of the amino acid content of the precursor composition is not particularly limited, but can be, for example, 10% by mass or less, and further can be 8% by mass or less, 6% by mass or less, or 4% by mass or less. The above upper and lower limits can be any combination thereof, and the numerical ranges specified by combining these upper and lower limits are also disclosed in this disclosure. In other words, the range of amino acid content of the precursor composition is not limited to these, but can be, for example, 0.1-10% by mass, 0.5-10% by mass, 1-10% by mass, 2-10% by mass, 0.1-8% by mass, 0.5-8% by mass, 1-8% by mass, 2-8% by mass, 0.1-6% by mass, 0.5-6% by mass, 1-6% by mass, 2-6% by mass, 0.1-4% by mass, 0.5-4% by mass, 1-4% by mass, or 2-4% by mass.

[0038] When a precursor composition contains amino acids, the type of amino acid is not particularly limited. Examples of amino acids, but are not limited to these, include glutamic acid, aspartic acid, alanine, glycine, serine, threonine, valine, leucine, isoleucine, lysine, arginine, histidine, phenylalanine, tyrosine, methionine, cysteine, proline, tryptophan, glutamine, asparagine, or salts thereof. The precursor composition may contain one of these amino acids alone, or two or more in any combination and ratio. In particular, from the viewpoint of imparting umami, it is preferable that the precursor composition contains glutamic acid, aspartic acid, and / or salts thereof. The origin of the amino acids is not particularly limited and may be derived from amino acid preparations, protein hydrolysates, yeast extracts, seafood extracts, meat extracts, vegetable extracts, kelp extracts, fermented seasonings, soy sauce, miso, natto, or other food materials.

[0039] The amino acid content in the composition can be measured according to the amino acid analysis method described in the "Analysis Manual for the 2015 Edition (Seventh Revised Edition) of the Standard Tables of Food Composition in Japan." Specifically, it can be measured using an automated amino acid analyzer (for example, the "JLC-500 / V2 (manufactured by JEOL) or an equivalent product" can be used). Unless otherwise specified, the amino acid content is expressed as the total amount of free amino acids.

[0040] • Thickening agent The precursor composition may contain a thickening agent. When the precursor composition contains a thickening agent, the lower limit of the thickening agent content in the precursor composition is not particularly limited, but in one embodiment, from the viewpoint that it may improve the foaming and foam retention properties of natto, the lower limit can be, for example, 0.01% by mass or more, and furthermore, 0.05% by mass or more, or 0.1% by mass or more. The details of the principle are not necessarily clear, but it is thought that by including a certain amount or more of the thickening agent, the viscosity of the continuous phase of the composition increases, delaying the drainage from the foam film and suppressing the rapid thinning and rupture of the foam film. On the other hand, the upper limit of the thickening agent content in the precursor composition is also not particularly limited, but in one embodiment, from the viewpoint that it may improve the texture of the sauce, it can be, for example, 5% by mass or less, and furthermore, 3% by mass or less, or 1% by mass or less. The above upper and lower limits can be any combination of each other, and the numerical range specified by combining these upper and lower limits is also disclosed in this disclosure. In other words, the range of the thickening agent content in the precursor composition is not limited to these, but can be, for example, 0.01 to 5% by mass, 0.05 to 5% by mass, 0.1 to 5% by mass, 0.01 to 3% by mass, 0.05 to 3% by mass, 0.1 to 3% by mass, 0.01 to 1% by mass, 0.05 to 1% by mass, or 0.1 to 1% by mass.

[0041] If the precursor composition contains a thickening agent, the type of thickening agent is not particularly limited. Examples of thickening agents, but are not limited to these, include xanthan gum, guar gum, locust bean gum, tamarind seed gum, gellan gum, carrageenan, pectin, alginic acid or its salts, agar, gelatin, cellulose derivatives, carboxymethylcellulose or its salts, methylcellulose, hydroxypropylmethylcellulose, starch, modified starch, dextrin, pullulan, curdlan, glucomannan, gum arabic, and the like. The precursor composition may contain one of these thickening agents alone, or two or more in any combination and ratio. The thickening agent may be added to the composition as an independent component, and may be derived from natto, vegetables, fruits, seaweed, grains, legumes, fermented foods, or other food materials.

[0042] The content of the thickening agent in the composition is calculated based on the amount added. Alternatively, it can be measured by the dry weight method.

[0043] ·albumin The precursor composition may contain albumin. If the precursor composition contains albumin, the lower limit of the albumin content in the precursor composition is not particularly limited, but according to one embodiment, from the viewpoint of potentially improving the foaming and foam retention properties of natto, it can be, for example, 0.01% by mass or more, and furthermore, 0.05% by mass or more, or 0.1% by mass or more. The details of the principle are not necessarily clear, but it is thought that this is because albumin hardens upon oxidation, thereby increasing the stability of the foam film. On the other hand, the upper limit of the albumin content in the precursor composition is also not particularly limited, but according to one embodiment, from the viewpoint of potentially preventing aggregation due to denaturation, it can be, for example, 10% by mass or less, and furthermore, 5% by mass or less, 3% by mass or less, or 1% by mass or less. The above upper and lower limits can be any combination of each other, and the numerical range specified by combining these upper and lower limits is also disclosed in this disclosure. In other words, the albumin content in the precursor composition is not limited to these ranges, but can be, for example, 0.01-10% by mass, 0.05-10% by mass, 0.1-10% by mass, 0.01-5% by mass, 0.05-5% by mass, 0.1-5% by mass, 0.01-3% by mass, 0.05-3% by mass, 0.1-3% by mass, 0.01-1% by mass, 0.05-1% by mass, or 0.1-1% by mass.

[0044] When the precursor composition contains albumin, the type of albumin is not particularly limited. Examples of albumin, but not limited to these, include oval albumin, serum albumin, milk-derived albumin, plant-derived albumin, microbial-derived albumin, or protein materials containing these. From the viewpoint of applicability to food applications, the albumin may be derived from egg white, egg white powder, egg white protein, milk protein material, or processed products thereof. The albumin may be an undenatured protein, or it may be modified by heating, enzymatic treatment, acid treatment, alkali treatment, saccharification treatment, or other treatments.

[0045] The albumin content in the composition is calculated based on the amount used. Alternatively, it can be measured by an immunological assay.

[0046] ·γ-PGA The precursor composition is preferably low in γ-polyglutamic acid (sometimes abbreviated as "γ-PGA"), which is known as the stringy component of natto. Specifically, from the viewpoint of preventing a decrease in foam retention ability due to storage, the upper limit of the γ-PGA content in the precursor composition is not limited, but can be, for example, 1% by mass or less, and further, 0.5% by mass or less, or 0.1% by mass or less, or 0.05% by mass or less. The details of the principle are not necessarily clear, but it is thought that because γ-PGA is a polyelectrolyte, it is easily affected by salts, amino acids, etc. in the sauce, causing shrinkage of molecular chains, aggregation, or local viscosity increase during storage, and preventing the foam film reinforcing effect and foam retention effect that the starch hydrolysate should originally exert from being fully expressed. On the other hand, the lower limit is not particularly limited, and it may be substantially absent (below the detection limit) or completely absent (0.00% by mass).

[0047] When the precursor composition contains γ-PGA, the origin of γ-PGA is not particularly limited. Examples include natto, natto bacillus culture, natto bacillus fermented product, γ-PGA-containing material, or purified or partially purified γ-PGA, any of which may be used. Furthermore, γ-PGA may be in the form of a free acid, or in the form of a salt such as a sodium salt, potassium salt, calcium salt, or magnesium salt. In this disclosure, γ-PGA includes polyglutamic acid.

[0048] The γ-PGA content in the composition is measured by the method described in "Quantitative Determination of γ-Polyglutamic Acid in Natto Using Cetyltrimethylammonium Bromide," by Akishige Sugano et al., Journal of the Japan Society for Food Science and Technology, 1995, Vol. 42, No. 11, pp. 878-886. Specifically, the γ-PGA content can be measured by measuring the absorbance when γ-PGA is purified and reacted with cetyltrimethylammonium bromide (cetabrone).

[0049] Furthermore, while the acidity of the precursor composition is not particularly limited, from the viewpoint of improving foam retention while maintaining a good aftertaste, its lower limit can be set to 0.01% by mass or more, and further to 0.05% by mass or more, further to 0.1% by mass or more, and further to 0.2% by mass or more. On the other hand, from the viewpoint of preventing protein aggregation, the upper limit of acidity can be set to 1% by mass or less, and further to 0.8% by mass or less, further to 0.6% by mass or less, and further to 0.4% by mass or less. The above upper and lower limits can be any combination of each other, and the numerical ranges that can be specified by combining these upper and lower limits are also disclosed herein. In other words, the acidity of the precursor composition is not limited to these, but can be, for example, 0.01-1% by mass, 0.05-1% by mass, 0.1-1% by mass, 0.2-1% by mass, 0.01-0.8% by mass, 0.05-0.8% by mass, 0.1-0.8% by mass, 0.2-0.8% by mass, 0.01-0.6% by mass, 0.05-0.6% by mass, 0.1-0.6% by mass, 0.2-0.6% by mass, 0.01-0.4% by mass, 0.05-0.4% by mass, 0.1-0.4% by mass, or 0.2-0.4% by mass.

[0050] The source of acidity is not particularly limited and may be achieved by containing acetic acid, lactic acid, citric acid, malic acid, tartaric acid, gluconic acid, succinic acid, fumaric acid, ascorbic acid, phosphoric acid, or salts thereof. Alternatively, acidity may be achieved by acidic components introduced from vinegar, fruit juice, fermented seasonings, yogurt, lactic acid fermented products, processed vegetable products, processed fruit products, or other food ingredients.

[0051] Acidity can be measured by a neutralization titration method using a sodium hydroxide standard solution. In this specification, unless otherwise specified, acidity is expressed as acetic acid equivalent acidity.

[0052] Furthermore, while the pH of the precursor composition is not particularly limited, from the viewpoint of improving the flavor of natto, its lower limit can be 3.0 or higher, and further 3.5 or higher, and even 4.0 or higher. On the other hand, from the viewpoint of improving foam retention, the upper limit of the pH can be 7.0 or lower, and further 6.5 or lower, further 6.0 or lower, further 5.5 or lower, and even further 5.0 or lower. The details of the principle are not entirely clear, but it is thought that the proteins denature under acidic conditions, thereby increasing the stability of the foam film. The above upper and lower limits can be any combination of each other, and the numerical ranges that can be determined by combining these upper and lower limits are also disclosed herein. That is, the pH may be, for example, 3.0-7.0, 3.0-6.5, 3.0-6.0, 3.0-5.5, 3.0-5.0, 3.5-7.0, 3.5-6.5, 3.5-6.0, 3.5-5.5, 3.5-5.0, 4.0-7.0, 4.0-6.5, 4.0-6.0, 4.0-5.5, or 4.0-5.0.

[0053] pH can be adjusted using acidulants, alkaline agents, buffering agents, organic acids, organic acid salts, inorganic acids, inorganic acid salts, amino acids, amino acid salts, fermented seasonings, vinegar, fruit juice, lactic acid fermented products, soy sauce, miso, or other food ingredients. Examples of pH adjusters include acetic acid, lactic acid, citric acid, malic acid, gluconic acid, phosphoric acid, carbonates, bicarbonates, phosphates, citrates, lactates, acetates, sodium hydroxide, potassium hydroxide, etc.

[0054] pH is measured using a glass electrode pH meter. If the composition is heterogeneous, the pH may be measured after stirring, homogenization, filtration, centrifugation, or dilution.

[0055] <Step (2): Heat treatment of the precursor composition> Step (2) of the manufacturing method of the present invention is a step of subjecting the precursor composition obtained in step (1) to a heat treatment for 1 minute or more so that it reaches a maximum temperature of 70 to 130°C. Here, the heat treatment may be in a batch or continuous manner. In this disclosure, "heat treatment for 1 minute or more so that it reaches a maximum temperature of 70 to 130°C" means a process of applying heat to the composition for 1 minute or more so that the maximum temperature reached by the composition during the heat treatment is within the range of 70 to 130°C. Here, "1 minute or more" means the time the composition is placed in a heating device or under a heating environment, and it is not necessary to maintain a state in which the entire composition reaches 70°C or higher for 1 minute or more.

[0056] In step (2), by subjecting the precursor composition obtained in step (1) to a heat treatment at a predetermined temperature and for a predetermined time, the solubility, compositional uniformity, and viscosity characteristics of the raw materials are stabilized, and it may be easier to reliably obtain the foaming improvement effect when added to natto. Furthermore, the heat treatment is also advantageous from the viewpoint of microbial control. Although the details of the principle are not entirely clear, it is thought that heating adjusts the hydration state of starch hydrolysates and the surfactant behavior of albumin, etc., resulting in a compositional state suitable for foam formation.

[0057] Heat treatment can be carried out by methods such as kettle heating, plate heating, tube heating, retort heating, and steam injection heating. Homogenization, filtration, degassing, or cooling may be combined before and after heating as needed.

[0058] • Heating temperature, heating time, and high-temperature maintenance time The lower limit of the maximum temperature during the heat treatment in step (2) is 70°C or higher. In particular, it can be 75°C or higher, or 80°C or higher. On the other hand, the upper limit of the heating temperature is not particularly limited, but from the viewpoint of flavor preservation, it may be 130°C or lower, 110°C or lower, or 90°C or lower. The above upper and lower limits can be any combination of each other, and the numerical range specified by combining these upper and lower limits is also disclosed in this disclosure. That is, the range of the maximum temperature during the heat treatment in step (2) is not limited to these, but can be 70~130°C, 75~130°C, 80~130°C, 70~110°C, 75~110°C, 80~110°C, 70~90°C, 75~90°C, or 80~90°C. The heating temperature of the composition can be confirmed by measuring the temperature of the composition with a thermocouple.

[0059] The lower limit of the heating time during the heat treatment in step (2) is 1 minute or more. In particular, it can be 1 minute 30 seconds or more, or 2 minutes or more. On the other hand, there is no particular limit to the heating time, but from the viewpoint of flavor preservation and productivity, it can be 120 minutes or less, 60 minutes or less, 30 minutes or less, or 10 minutes or less. Herein, "heating time" should be managed as the time during which the composition is exposed to a high temperature environment (usually the above-mentioned maximum temperature range or a temperature environment above) in the heating device or under the heating environment, and means the time until the composition reaches the above-mentioned maximum temperature range and the time during which it is maintained within the above-mentioned maximum temperature range. The above upper and lower limits can be any combination of each other, and the numerical range specified by combining these upper and lower limits is also disclosed in this disclosure. In other words, the range of heating time in step (2) is not limited to these, but can be, for example, 1 to 120 minutes, 1 minute 30 seconds to 120 minutes, 2 to 120 minutes, 1 to 60 minutes, 1 minute 30 seconds to 60 minutes, 2 to 60 minutes, 1 to 30 minutes, 1 minute 30 seconds to 30 minutes, 2 to 30 minutes, 1 to 10 minutes, 1 minute 30 seconds to 10 minutes, or 2 to 10 minutes.

[0060] The lower limit of the time during which the composition is maintained at a high temperature of 50°C or higher during the heat treatment in step (2) (hereinafter referred to as "high temperature maintenance time") is not particularly limited, but may be 30 seconds or more, and may be, for example, 1 minute or more, or 1 minute 30 seconds or more. On the other hand, the upper limit of the high temperature maintenance time is also not particularly limited, but from the viewpoint of flavor preservation and productivity, it may be, for example, within 60 minutes, within 30 minutes, within 10 minutes, or within 5 minutes. Note that "high temperature maintenance time" as used herein differs from the "heating time" mentioned above and means the time during which the temperature of the composition itself is maintained within the above temperature range. The above upper and lower limits can be any combination of each other, and the numerical ranges specified by combining these upper and lower limits are also disclosed herein. In other words, the range of high-temperature maintenance time in step (2) is not limited to these, but can be, for example, 30 seconds to 60 minutes, 30 seconds to 30 minutes, 30 seconds to 10 minutes, 30 seconds to 5 minutes, 1 to 60 minutes, 1 to 30 minutes, 1 to 10 minutes, 1 to 5 minutes, 1 minute 30 seconds to 60 minutes, 1 minute 30 seconds to 30 minutes, 1 minute 30 seconds to 10 minutes, or 1 minute 30 seconds to 5 minutes.

[0061] [2. Natto sauce] One aspect of the present invention relates to natto sauce (hereinafter appropriately abbreviated as "the natto sauce of the present invention"). In this disclosure, "natto sauce" refers to a liquid or semi-liquid seasoning that is added to natto and consumed, as described above. Descriptions of starch hydrolysates, Brix value, salt content, amino acids, thickeners, albumin, γ-PGA, acidity, pH, heating temperature, heating time, etc., can be directly referenced from the description of the manufacturing method of the present invention above.

[0062] Natto sauce The natto sauce according to the first aspect of the present invention (hereinafter referred to as "natto sauce A of the present invention" as appropriate) is characterized by being manufactured by the manufacturing method of the present invention. Specifically, the natto sauce of the present invention can be manufactured by preparing it through steps (1) and (2) above, and then filling, packaging and cooling as necessary.

[0063] Furthermore, the natto sauce according to the second aspect of the present invention (hereinafter, as appropriate, will be abbreviated as "natto sauce B of the present invention." Also, "natto sauce A of the present invention" and "natto sauce B of the present invention" may be collectively referred to simply as "natto sauce of the present invention") is characterized by satisfying the following (i) to (iii). (i) Contains 0.1% by mass or more of starch hydrolysates with a dextrose equivalent value of 50 or less. (ii) The water activity is 0.98 or less. (iii) The ratio of the value β to the value α below when measured by the method α below ([value β] / [value α]) is 1.0 or less. [Value α]: Viscosity (cP) at 50°C. [Value β]: Viscosity (cP) at 80°C. <Method α> Using a Rapid Viscometer (RVA), 25g of the sample to be measured is heated from 50°C to 80°C at a heating rate of 12°C / min.

[0064] The natto sauce of the present invention is usually liquid or semi-liquid and may be filled into small pouches, bottles, etc. The natto sauce of the present invention may also contain, for example, soy sauce, sugars, salt, amino acids, starch hydrolysates, water, flavorings, etc.

[0065] The natto sauce of the present invention can easily improve foaming properties when added to natto and stirred, and may be able to achieve a combination of highly resilient foam, a fluffy texture, and good seasoning.

[0066] ·[Value β] / [Value α] In the present invention, it is preferable that the ratio of [Value β] to [Value α] ([Value β] / [Value α]) when the composition after heat treatment is measured by the following <Method α> is less than or equal to a predetermined value described below. Furthermore, one of the features of the present invention is that the ratio of [Value β] to [Value α] ([Value β] / [Value α]) when the composition after heat treatment is measured by the following <Method α> is less than or equal to a predetermined value described below. [Value α]: Viscosity (cP) at 50°C. [Value β]: Viscosity (cP) at 80°C. <Method α> Using a Rapid Viscometer (RVA), 25g of the sample to be measured is heated from 50°C to 80°C at a heating rate of 12°C / min.

[0067] The values ​​[α] and [β] are measured by heating 25g of the sample from 50°C to 80°C at a heating rate of 12°C / min using a rapid viscoanalytic analyzer (RVA) (this is referred to as "<Method α>" as appropriate). Any device capable of heating the sample to 80°C can be used as the rapid viscoanalytic analyzer (RVA), but for example, the Perten RVA4800 can be used. The viscosity (cP) at 50°C and 80°C measured with an RVA at a heating rate of 12°C / min is measured specifically by the following procedure. Specifically, 25 g of the composition sample is weighed into an aluminum cup for RVA measurement, and the measurement is started at 50°C. The rotation speed is set to 960 rpm from the start of measurement to 10 seconds after the start of measurement, and to 160 rpm from 10 seconds after the start of measurement to the end of measurement. After holding at 50°C for 1 minute, the heating process is started from 50°C to 80°C at a heating rate of 12°C / min, and the viscosity is measured at 50°C and 80°C.

[0068] Specifically, the upper limit of the [value β] / [value α] of natto sauce A of the present invention is not limited, but from the viewpoint of ensuring that it spreads effectively when added to natto, stirred, and poured over rice, it can be, for example, 1.0 or less, and furthermore, 0.90 or less, 0.80 or less, or 0.7 or less. Similarly, the upper limit of the [value β] / [value α] of natto sauce B of the present invention is 1.0 or less, from the viewpoint of ensuring that it spreads effectively when added to natto, stirred, and poured over rice. In particular, it is preferable to set it to, for example, 0.90 or less, 0.80 or less, or 0.7 or less. On the other hand, the lower limit of the [value β] / [value α] of natto sauce of the present invention is not limited, but from the viewpoint of ensuring that the foam-retaining ability on rice is ensured by not letting the viscosity decrease too much at high temperatures, it can be, for example, 0.05 or more, and furthermore, 0.1 or more, 0.2 or more, or 0.3 or more. The above upper and lower limits can be any combination of them, and the numerical ranges that can be determined by combining these upper and lower limits are also disclosed in this disclosure. That is, the range of [value β] / [value α] of the natto sauce of the present invention is not limited to these, but can be, for example, 0.05~1.0, 0.1~1.0, 0.2~1.0, 0.3~1.0, 0.05~0.90, 0.1~0.90, 0.2~0.90, 0.3~0.90, 0.05~0.80, 0.1~0.80, 0.2~0.80, 0.3~0.80, 0.05~0.7, 0.1~0.7, 0.2~0.7, or 0.3~0.7.

[0069] Furthermore, the [value β] / [value α] of the natto sauce of the present invention can be controlled by adjusting the type and content of starch hydrolysates, the balance of sugars, salt, amino acids, and albumin, as well as the heating temperature and heating time. In particular, the heating temperature and heating time can be arbitrarily adjusted by those skilled in the art, and by heating until the above [value β] / [value α] falls within a predetermined range, the effect can be obtained in which the natto spreads more effectively when added to natto, stirred, and poured over rice.

[0070] • [Value α] [Value α] is the viscosity (cP) of the composition at 50°C and is measured by the above-described method α. The [Value α] of the natto sauce of the present invention can serve as an indicator of the body and foam retention properties that the composition has when warm after heat treatment.

[0071] Specifically, the lower limit of [value α] of the natto sauce of the present invention is not limited, but can be, for example, 1 cP or more, and further can be 3 cP or more, 5 cP or more, or 10 cP or more. On the other hand, the upper limit of [value α] of the natto sauce of the present invention is also not limited, but can be, for example, 1000 cP or less, and further can be 500 cP or less, 100 cP or less, or 50 cP or less. The above upper and lower limits can be any combination of each other, and the numerical ranges that can be specified by combining these upper and lower limits are also disclosed in this disclosure. In other words, the range of [value α] of the natto sauce of the present invention is not limited to these, but can be, for example, 1-1000cP, 1-500cP, 1-100cP, 1-50cP, 3-1000cP, 3-500cP, 3-100cP, 3-50cP, 5-1000cP, 5-500cP, 5-100cP, 5-50cP, 10-1000cP, 10-500cP, 10-100cP, or 10-50cP.

[0072] Furthermore, the [value α] of the natto sauce can be controlled by adjusting the type and content of starch hydrolysates, water activity, Brix value, salt content, heating conditions, etc.

[0073] • [Value β] [Value β] is the viscosity (cP) of the composition at 80°C and is measured by the above-described method α. The [Value β] of the natto sauce of the present invention can serve as an indicator for evaluating its fluidity during heating and its behavior after the thermal history.

[0074] Specifically, the lower limit of the [value β] of the natto sauce of the present invention is not limited, but can be, for example, 1 cP or more, and further can be 3 cP or more, 5 cP or more, or 10 cP or more. On the other hand, the upper limit of the [value β] of the natto sauce of the present invention is also not limited, but can be, for example, 1000 cP or less, and further can be 500 cP or less, 100 cP or less, or 50 cP or less. The above upper and lower limits can be any combination of each other, and the numerical ranges that can be specified by combining these upper and lower limits are also disclosed in this disclosure. That is, the range of [value β] of the natto sauce of the present invention is not limited to these, but can be, for example, 1-1000cP, 1-500cP, 1-100cP, 1-50cP, 3-1000cP, 3-500cP, 3-100cP, 3-50cP, 5-1000cP, 5-500cP, 5-100cP, 5-50cP, 10-1000cP, 10-500cP, 10-100cP, or 10-50cP.

[0075] Furthermore, the [value β] of natto sauce can be controlled by adjusting the type and content of starch hydrolysates, water activity, Brix value, salt content, heating conditions, etc.

[0076] The natto sauce of the present invention may be a containerized natto sauce filled in a container. The container is not particularly limited, but may be a sealed container. The sealed container is not particularly limited as long as it can suppress leakage of the natto sauce contents, dissipation of volatile components, contact with the outside air, incorporation of foreign matter, or contamination by microorganisms. For example, it may be a plastic film container, a plastic cup container, a plastic bottle container, a pouch container, a tube container, a glass container, a metal container, a laminated container including paper, or a composite container thereof. Among these, the container is preferably a plastic film container from the viewpoint of being easy to attach to natto products, being able to easily fill and seal a small amount of natto sauce, and having excellent handling and disposal properties when opened. The plastic film container may be a container made of a single layer film, or a container made of a laminated film including multiple resin layers. Examples of resins constituting the plastic film container include polyethylene, polypropylene, polyethylene terephthalate, polyamide, ethylene-vinyl alcohol copolymer, polyvinylidene chloride, or combinations thereof. The container may be sealed by heat sealing, ultrasonic sealing, bonding, fitting, crimping, or a combination thereof. In particular, when using a plastic film container, it is preferable that the periphery of the container is heat-sealed. This suppresses leakage of natto sauce during storage, while allowing it to be easily opened by hand when consuming.

[0077] ·viscosity The viscosity of the natto sauce of the present invention is not particularly limited, but from the viewpoint of improving the foaming and foam retention properties of natto, the lower limit can be, for example, 1 cP or more, and further it can be 3 cP or more, 5 cP or more, or 10 cP or more. The details of the principle are not necessarily clear, but it is thought that when the viscosity is above a certain level, the drainage of the liquid phase in the foam film slows down, the thinning of the foam film, the coalescence and bursting of bubbles are suppressed, and thus the foam retention is improved. On the other hand, the upper limit of the viscosity of the natto sauce of the present invention is also not particularly limited, but from the viewpoint of making it easier for natto mixed with the natto sauce to spread on rice, it can be, for example, 1000 cP or less, and further it can be 500 cP or less, 100 cP or less, or 50 cP or less. The above upper and lower limits can be any combination of each other, and the numerical range specified by combining these upper and lower limits is also disclosed in this disclosure. In other words, the viscosity range of the natto sauce of the present invention is not limited to these, but can be, for example, 1-1000 cP, 1-500 cP, 1-100 cP, 1-50 cP, 3-1000 cP, 3-500 cP, 3-100 cP, 3-50 cP, 5-1000 cP, 5-500 cP, 5-100 cP, 5-50 cP, 10-1000 cP, 10-500 cP, 10-100 cP, or 10-50 cP.

[0078] The viscosity of the natto sauce of the present invention can be controlled by adjusting the sugars, sugar alcohols, starch hydrolysates, thickeners, proteins, poly-γ-glutamic acid, polysaccharides, dietary fiber, oils and fats, emulsifiers, solid content, pH, salt content, acidity, etc. The viscosity may be adjusted by a single component or by a combination of multiple components.

[0079] The viscosity of the natto sauce disclosed herein was measured using a B-type viscometer. For example, the "B-II" manufactured by Toki Sangyo Co., Ltd. can be used as the B-type viscometer. The measurement conditions are a measurement temperature of 20°C and a rotor rotation speed of 60 rpm. The rotor should be selected according to the viscosity range of the substance being measured. For example, rotor No. 1 can be used when the viscosity is approximately 1 to 100 cP.

[0080] • Starch hydrolysates with a DE value below a specified value The starch hydrolysates with a DE value of 50 or less in natto sauce A of the present invention are not particularly limited, but according to one embodiment, from the viewpoint of improving foaming properties, the lower limit may be 0.1% by mass or more. In particular, it can be, for example, 0.2% by mass or more, 0.5% by mass or more, 1% by mass or more, 2% by mass or more, or 5% by mass or more. Also, the lower limit of starch hydrolysates with a DE value of 50 or less in natto sauce B of the present invention is 0.1% by mass or more. In particular, it is preferable to set it to, for example, 0.2% by mass or more, 0.5% by mass or more, 1% by mass or more, 2% by mass or more, or 5% by mass or more. On the other hand, the upper limit of the starch hydrolysate content with a DE value of 50 or less in natto sauce of the present invention is not limited, but from the viewpoint of taste balance and viscosity, it can be, for example, 60% by mass or less, and furthermore, 50% by mass or less, 40% by mass or less, 35% by mass or less, 30% by mass or less, 25% by mass or less, or 20% by mass or less. The above upper and lower limits can be any combination of them, and the numerical ranges that can be determined by combining these upper and lower limits are also disclosed in this disclosure. That is, the range of starch hydrolysate content with a DE value of 50 or less in the natto sauce of the present invention is not limited to these, but for example, 0.1-60% by mass, 0.2-60% by mass, 0.5-60% by mass, 1-60% by mass, 2-60% by mass, 5-60% by mass, 0.1-50% by mass, 0.2-50% by mass, 0.5-50% by mass, 1-50% by mass, 2-50% by mass, 5-50% by mass, 0.1-40% by mass, 0.2-40% by mass, 0.5-40% by mass, 1-40% by mass, 2-40% by mass, 5-40% by mass, 0.1- 35% by mass, 0.2-35% by mass, 0.5-35% by mass, 1-35% by mass, 2-35% by mass, 5-35% by mass, 0.1-30% by mass, 0.2-30% by mass, 0.5-30% by mass, 1-30% by mass, 2-30% by mass, 5-30% by mass, 0.1-25 quality %, 0.2-25% by mass, 0.5-25% by mass, 1-25% by mass, 2-25% by mass, 5-25% by mass, 0.1-20% by mass, 0.2-20% by mass, 0.5-20% by mass, 1-20% by mass, 2-20% by mass, or 5-20% by mass.

[0081] ·Water activity The water activity of natto sauce A of the present invention is not particularly limited, but according to one embodiment, the upper limit of the water activity may be 0.98 or less. In particular, it may be 0.97 or less, 0.96 or less, 0.95 or less, 0.94 or less, or 0.93 or less. Furthermore, the upper limit of the water activity of natto sauce B of the present invention is 0.98 or less. In particular, it is preferable to set it to 0.97 or less, 0.96 or less, 0.95 or less, 0.94 or less, or 0.93 or less. This makes it easier to ensure storage stability and may also have the effect of increasing the amount of foam. The principle is not entirely clear, but it is thought that when the water activity of the aqueous solution decreases, the amount of free water in the continuous phase decreases, and the liquid film drainage rate, bubble coalescence rate, and inter-bubble gas transfer rate all decrease, which makes it easier for the viscosity and extensional viscosity of the continuous phase to increase, and even if gas is introduced into the liquid during stirring, the thin liquid film that has been formed does not break immediately, and the disappearance of foam is less likely to occur. On the other hand, the lower limit of the water activity of natto sauce is not particularly limited, but from the viewpoint of taste, fluidity, and blending flexibility, it can be, for example, 0.70 or higher, 0.75 or higher, 0.80 or higher, 0.85 or higher, or 0.90 or higher. The above upper and lower limits can be any combination of these, and the numerical ranges that can be determined by combining these upper and lower limits are also disclosed in this disclosure. In other words, the range of water activity in natto sauce is not limited to these, but for example, 0.70~0.98, 0.75~0.98, 0.80~0.98, 0.85~0.98, 0.90~0.98, 0.70~0.97, 0.75~0.97, 0.80~0.97, 0.85~0.97, 0.90~0.97, 0.70~0.96, 0.75~0.96, 0.80~0.96, 0.85~0. It can be 96, 0.90~0.96, 0.70~0.95, 0.75~0.95, 0.80~0.95, 0.85~0.95, 0.90~0.95, 0.70~0.94, 0.75~0.94, 0.80~0.94, 0.85~0.94, 0.90~0.94, 0.70~0.93, 0.75~0.93, 0.80~0.93, 0.85~0.93, or 0.90~0.93.

[0082] The water activity of natto sauce can be adjusted by reducing the amount of water, increasing the amount of soluble solids such as starch hydrolysates, sugars, salt, and amino acids, or by using a combination of these methods. A concentration process may also be employed if necessary. Furthermore, the water activity of natto sauce may decrease due to solutes such as starch hydrolysates, sugars, salt, and amino acids. In particular, using sugars and salt in combination makes it easier to adjust the water activity to the desired level while maintaining the flavor balance of the natto sauce. The water activity of both the precursor composition and the heated natto sauce can be measured by the methods described above. If the water content does not substantially change due to the heat treatment, the water activity of the heated natto sauce may be similar to that of the precursor composition.

[0083] Other composition and physical properties of natto sauce The other compositional properties of the natto sauce of the present invention are basically the same as those of the precursor composition described above, with the exception of some compositional properties that change due to heat treatment.

[0084] • Amount of natto sauce added to natto The natto sauce of the present invention is used by adding it to natto. In one embodiment, it is preferable to use the natto sauce of the present invention by adding it to natto in a predetermined mass ratio. The mass ratio of the natto sauce to the natto can be determined based on the mass of the natto sauce before and after addition, or the mass of the natto sauce weighed separately.

[0085] Specifically, the lower limit of the amount of the natto sauce of the present invention added to natto is not particularly limited, but it can be, for example, 10 parts by mass or more per 100 parts by mass of natto, and further, 12 parts by mass or more, or 15 parts by mass or more. By adding the amount of natto sauce above these lower limits, it may be possible to further enhance the effect of improving foaming ability and / or the amount of foam when added to natto. On the other hand, the upper limit of the amount of the natto sauce of the present invention added to natto is not particularly limited, but it can be, for example, 30 parts by mass or less per 100 parts by mass of natto, and further, 28 parts by mass or less, or 25 parts by mass or less. By adding the amount of natto sauce below these upper limits, it may be possible to improve the balance of taste between natto and natto sauce, or to improve the texture of natto. The above upper and lower limits can be combined in any way, and the numerical ranges that can be specified by combining these upper and lower limits are also disclosed in this disclosure. In other words, the range of the amount of natto sauce to be added according to the present invention is not limited to these, but for example, it can be 10-30 parts by mass, 12-30 parts by mass, 15-30 parts by mass, 10-28 parts by mass, 12-28 parts by mass, 15-28 parts by mass, 10-25 parts by mass, 12-25 parts by mass, or 15-25 parts by mass per 100 parts by mass of natto.

[0086] The amount of the natto sauce of the present invention added to natto can be controlled by the volume of the natto sauce packet, the amount dispensed, or the instructions for use.

[0087] • Starch hydrolysate content in natto According to one embodiment, the natto sauce of the present invention is preferably used by adding starch hydrolysates with a DE value of 50 or less to natto in a predetermined mass ratio. The mass ratio of the starch hydrolysates with a DE value of 50 or less to natto can be controlled by adjusting the concentration of starch hydrolysates with a DE value of 50 or less in the natto sauce, or by adjusting the amount of natto sauce added.

[0088] Specifically, there is no particular lower limit to the amount of starch hydrolysate with a DE value of 50 or less added to natto, but it can be, for example, 0.01 parts by mass or more per 100 parts by mass of natto, and further, it can be 0.1 parts by mass or more, 0.5 parts by mass or more, or 1 part by mass or more. By using natto sauce so that the amount of starch hydrolysate with a DE value of 50 or less added to natto is above these lower limits, it may be possible to fully exhibit the foaming improvement effect at the time the natto sauce is added to the natto. On the other hand, there is no particular upper limit to the amount of starch hydrolysate with a DE value of 50 or less added to natto, but it can be, for example, 10 parts by mass or less per 100 parts by mass of natto, and further, it can be 8 parts by mass or less, 6 parts by mass or less, or 4 parts by mass or less. By using natto sauce so that the amount of starch hydrolysate with a DE value of 50 or less added to natto is below these upper limits, it may be possible to improve the balance of taste between natto and natto sauce, or to suppress stickiness. The above upper and lower limits can be any combination of them, and the numerical ranges that can be determined by combining these upper and lower limits are also disclosed in this disclosure. That is, the range of starch hydrolysates with a DE value of 50 or less added to natto is not limited to these, but can be, for example, 0.01 to 10 parts by mass, 0.1 to 10 parts by mass, 0.5 to 10 parts by mass, 1 to 10 parts by mass, 0.01 to 8 parts by mass, 0.1 to 8 parts by mass, 0.5 to 8 parts by mass, 1 to 8 parts by mass, 0.01 to 6 parts by mass, 0.1 to 6 parts by mass, 0.5 to 6 parts by mass, 1 to 6 parts by mass, 0.01 to 4 parts by mass, 0.1 to 4 parts by mass, 0.5 to 4 parts by mass, or 1 to 4 parts by mass per 100 parts by mass of natto.

[0089] The amount of starch hydrolysates with a DE value of 50 or less in natto can be controlled by adjusting the concentration of starch hydrolysates in the natto sauce and / or by adjusting the amount of natto sauce added to the natto.

[0090] • Content of starch hydrolysates relative to γ-PGA contained in natto In one embodiment, the natto sauce of the present invention is preferably used by adding starch hydrolysates with a DE value of 50 or less contained in the natto sauce to γ-PGA contained in natto in a predetermined mass ratio. As mentioned above, γ-PGA (γ-polyglutamic acid) is a component known to be the source of the stringiness of natto. The mass ratio of the starch hydrolysates with a DE value of 50 or less added to the natto-containing γ-PGA can be controlled by adjusting the fermentation conditions of the natto, the selection of natto bacteria and soybeans, as well as by adjusting the concentration of starch hydrolysates with a DE value of 50 or less in the natto sauce or by adjusting the amount of natto sauce added.

[0091] Specifically, the lower limit of the ratio of starch hydrolysates with a DE value of 50 or less to 100 parts by mass of natto-containing γ-PGA (hereinafter referred to as the "starch hydrolysate / γ-PGA ratio") is not particularly limited, but can be, for example, 100 parts by mass or more, and further can be 200 parts by mass or more, 300 parts by mass or more, or 500 parts by mass or more. By using natto sauce so that the starch hydrolysate / γ-PGA ratio is above these lower limits, it may be possible to fully exhibit the foaming improvement effect at the time the natto sauce is added to the natto. On the other hand, the upper limit of the starch hydrolysate / γ-PGA ratio is not particularly limited, but can be, for example, 10,000 parts by mass or less to 100 parts by mass of natto-containing γ-PGA, and further can be 8,000 parts by mass or less, 5,000 parts by mass or less, or 2,000 parts by mass or less. By using natto sauce such that the starch hydrolysate / γ-PGA ratio is below these upper limits, it may be possible to improve the balance of flavor between natto and natto sauce and suppress stickiness. The above upper and lower limits can be any combination of each other, and the numerical ranges that can be determined by combining these upper and lower limits are also disclosed in this disclosure. In other words, the range of the starch hydrolysate / γ-PGA ratio is not limited to these, but for 100 parts by mass of natto-containing γ-PGA, it can be, for example, 100-10000 parts by mass, 200-10000 parts by mass, 300-10000 parts by mass, 500-10000 parts by mass, 100-8000 parts by mass, 200-8000 parts by mass, 300-8000 parts by mass, 500-8000 parts by mass, 100-5000 parts by mass, 200-5000 parts by mass, 300-5000 parts by mass, 500-5000 parts by mass, 100-2000 parts by mass, 200-2000 parts by mass, 300-2000 parts by mass, or 500-2000 parts by mass.

[0092] The starch hydrolysate / γ-PGA ratio can be controlled by adjusting the starch hydrolysate concentration in the natto sauce (DE value of 50 or less), the amount of natto sauce added to the natto, and the amount of γ-PGA contained in the natto. The amount of γ-PGA contained in the natto can be controlled, for example, by adjusting the type of natto bacteria, fermentation temperature, fermentation time, type of soybean, and maturation conditions after fermentation.

[0093] According to one embodiment, the natto sauce of the present invention may be provided as packaged natto sauce filled in a sealed container. The container for the natto sauce is not particularly limited. The container may be rigid or semi-rigid, or it may be flexible.

[0094] [3. Natto products] One aspect of the present invention relates to natto products (hereinafter referred to as "natto products of the present invention" as appropriate). In this disclosure, "natto products" means products that include natto and natto sauce.

[0095] In this disclosure, "natto" refers to a food product containing soybeans fermented with natto bacteria. The natto included in the natto product of the present invention may be ordinary fermented natto, and may be in the form of small beans, large beans, crushed beans, etc.

[0096] The method of manufacturing natto is not particularly limited, and any general natto will suffice. The lower limit of the temperature during natto fermentation is also not particularly limited, but from the viewpoint that natto with stronger stringiness tends to produce more foam, it is preferable that the fermentation temperature be 43°C or higher, more preferably 45°C or higher, and more preferably 47°C or higher. On the other hand, the upper limit is also not particularly limited, but it is preferable that it be 55°C or lower, more preferably 52°C or lower, and more preferably 50°C or lower. The above upper and lower limits can be any combination of each other, and the numerical ranges that can be determined by combining these upper and lower limits are also disclosed in this disclosure. That is, the temperature during natto fermentation is not limited to these, but may be, for example, 43-55°C, 45-52°C, or 47-50°C. Note that the temperature during natto fermentation referred to here is the set temperature of the fermentation chamber in which the natto is fermented, and the temperature of the natto itself may be higher.

[0097] The natto product of the present invention is characterized in that the natto sauce is the natto sauce of the present invention as described above. The natto product of the present invention is consumed after adding the natto sauce of the present invention to the natto and preferably stirring it. This improves both the stringiness and foaming properties, resulting in a desirable appearance and texture.

[0098] In one embodiment, in the natto product of the present invention, it is preferable that the natto and natto sauce are packaged separately and then further packaged together in a separate "setup natto product," and that the natto and natto sauce are combined and stirred at the time of consumption. The containers for the natto and natto sauce are not particularly limited. The natto and natto sauce may be packaged in separate containers, or they may be packaged separately in a single container. The containers may be rigid or semi-rigid, or they may be flexible. In one embodiment, in the natto product of the present invention, it is preferable that at least the container packaging the natto is rigid or semi-rigid.

[0099] [4. Methods for improving the foaming properties of natto and increasing the amount of foam in natto] One aspect of the present invention relates to a method for improving the foaming properties of natto (hereinafter referred to as "the foaming property improvement method of the present invention" as appropriate). In this disclosure, "improving the foaming properties of natto" means that when the natto sauce of the present invention is added to natto and stirred, at least one of the following is improved compared to a control: the amount of foam, the height of the foam, the size of the foam, the foam retention, and / or the sensory fluffy impression.

[0100] Another aspect of the present invention relates to a method for increasing the amount of foam in natto (hereinafter referred to as "the foam-increasing method of the present invention" as appropriate). In this disclosure, "increasing the amount of foam in natto" means that when the natto sauce of the present invention is added to natto and stirred, the amount of foam is improved compared to a control.

[0101] The improvement in foaming ability and increase in foam volume of natto by natto sauce can be confirmed, for example, by adding a certain amount of natto sauce to a certain amount of natto and stirring it a predetermined number of times or for a predetermined time, then measuring the foam height, foam volume, foam duration, or sensory evaluation. Specifically, the natto may be stirred with chopsticks or the like about 30 times in 10 seconds, and the foam state may be observed immediately after stirring and after a certain period of time.

[0102] For comparison purposes regarding the improvement of natto's foaming ability and increase in foam volume using natto sauce, the same natto sauce can be used, except that it does not contain starch hydrolysates with a DE value of 50 or less, is not heat-treated, and / or has a water activity exceeding 0.98. This can be considered equivalent to one form of conventional natto sauce.

[0103] Specifically, steps (1) and (2) of the foaming improvement method and foam quantity increase method of the present invention are identical to steps (1) and (2) of the manufacturing method of the present invention described above.

[0104] Step (3) of the foaming improvement method and foam quantity increase method of the present invention is the step of adding the composition after the heat treatment in (2), i.e., the natto sauce of the present invention, to the natto and stirring. The amount of natto sauce of the present invention added to the natto is as described in detail above.

[0105] In this disclosure, "stirring" refers to the operation of mixing natto and natto sauce using chopsticks, a spoon, a stirring blade, etc., and incorporating air. The lower limit of the number of stirrings in step (3) is not limited, but can be, for example, 3 or more, 5 or more, 10 or more, or 20 or more. On the other hand, the upper limit of the number of stirrings is also not limited, but can be, for example, 100 or less, 80 or less, or 60 or less. The above upper and lower limits can be any combination of each other, and the numerical range specified by combining these upper and lower limits is also disclosed in this disclosure. That is, the range of the number of stirrings in step (3) is not limited to these, but can be, for example, 3 to 100, 5 to 100, 10 to 100, 20 to 100, 3 to 80, 5 to 80, 10 to 80, 20 to 80, 3 to 60, 5 to 60, 10 to 60, or 20 to 60.

[0106] The stirring conditions for natto can be adjusted according to the amount of natto, the shape of the container, and the desired foaming state. Furthermore, the natto sauce of the present invention may be added to the natto and then stirred; in addition, the natto may be stirred beforehand by itself before adding the natto sauce of the present invention.

[0107] The foaming properties and foam volume increasing method of the present invention make it easier to form a larger volume of foam that is more persistent, while making use of the inherent stringy properties of natto. As a result, it may be possible to improve the appearance, light texture, and satisfaction of eating natto.

[0108] [5. Natto mixed with sauce] One aspect of the present invention relates to natto mixed with sauce. Natto mixed with sauce in this disclosure is a natto product obtained by pouring the aforementioned natto sauce over natto and stirring it.

[0109] The aforementioned natto mixed with sauce preferably has a gas content of 5% by volume or more. The gas may be present between natto grains, between natto grains and sauce, in the sauce, or in the mucilaginous substance of natto, and may exist as bubbles, voids, or in a continuous or dispersed state thereof. By having a gas content of 5% by volume or more in the aforementioned natto mixed with sauce, excessive sticking of natto grains can be suppressed, and the natto sauce can be more easily spread uniformly on the surface of the natto grains and the mucilaginous substance. As a result, the looseness of the natto, the way the sauce clings to it, the mouthfeel, and the lightness when eaten can be improved. In addition, the inclusion of gas can give the appearance of the natto mixed with sauce a fluffy or voluminous feel. The gas content is not particularly limited, but may be 5% by volume or more, and may be 10% by volume or more, 15% by volume or more, or 20% by volume or more. On the other hand, the upper limit of the gas content is not particularly limited, but from the viewpoint of ensuring a good sense of unity between the natto grains and the natto sauce, good consistency when eaten, and good fit within the container, it may be, for example, 70% by volume or less, and further, 60% by volume or less, and even 50% by volume or less. The above upper and lower limits can be any combination of each other, and the numerical ranges that can be specified by combining these upper and lower limits are also disclosed in this disclosure. That is, the gas content is not limited to these, but for example, it may be 5-70% by volume, 10-70% by volume, 15-70% by volume, 20-70% by volume, 5-60% by volume, 10-60% by volume, 15-60% by volume, 20-60% by volume, 5-50% by volume, 10-50% by volume, 15-50% by volume, or 20-50% by volume. The gas content ratio can be calculated using the following formula, where V1 is the sum of the volume of natto sauce and the volume of natto, and V2 is the sum of the volume of natto sauce, the volume of threads (foam), and the volume of natto after stirring. Gas content (volume %) = {(V2-V1) / V2} × 100

[0110] [6. Foods containing natto (fermented soybeans)] One aspect of the present invention relates to a food product topped with natto. In this disclosure, a food product topped with natto is one in which the aforementioned natto mixed with sauce is placed on another food product. The food product is not particularly limited and can include rice, noodles, meat, eggs, salad, etc., but rice is preferred. [Examples]

[0111] The present invention will be described in more detail below with reference to examples, but these examples are merely illustrative examples for explanatory purposes, and the present invention is not limited in any sense to these examples.

[0112] <Manufacturing of natto sauce> Precursor compositions for Experimental Examples 1 to 20, having the compositions shown in Table 1 below, were prepared (Step (1)). A portion of each of the obtained compositions was subjected to heat treatment under the conditions shown in Table 1 below (Step (2)). This produced the natto sauces for Experimental Examples 1 to 20. The vinegar used had an acetic acid equivalent acidity of 15%.

[0113] [Table 1-1] [Table 1-2] [Table 1-3]

[0114] <Evaluation of the physical properties of natto sauce> For each example, the water activity, Brix value (Experimental Examples 1-17), viscosity at 50°C ([value α]) and viscosity at 80°C ([value β]) as measured by RVA, and their ratio ([value β] / [value α]) (Experimental Examples 18-20) were determined using the measurement method described above. The results are shown in Tables 2-3 below.

[0115] <Sensory evaluation of natto sauce> • Overview of sensory evaluation procedures: The natto sauces obtained for each example were subjected to the sensory evaluation described below. The sensory evaluators who conducted each sensory test were selected after undergoing the identification training described in A) to C) below, and who performed particularly well, had experience in product development, possessed extensive knowledge of food quality such as taste and texture, and were capable of performing absolute evaluations for each sensory evaluation item.

[0116] A) A taste discrimination test in which, for each of the five basic tastes (sweetness: the taste of sugar, sourness: the taste of tartaric acid, umami: the taste of monosodium glutamate, saltiness: the taste of sodium chloride, bitterness: the taste of caffeine), one aqueous solution is prepared at a concentration close to the threshold for each component, and two distilled water solutions are added to these to create a total of seven samples, from which the tester must accurately identify the sample for each taste. B) A concentration difference identification test to accurately identify the concentration differences between five types of saline solutions and acetic acid solutions with slightly different concentrations. C) A three-point identification test to accurately identify soy sauce from manufacturer B from a total of three samples: two from manufacturer A and one from manufacturer B.

[0117] Furthermore, for all of the aforementioned evaluation items, all inspectors evaluated a standard sample in advance, standardizing the scores for each evaluation criterion, and then an objective sensory evaluation was conducted by 10 inspectors. For each evaluation item, each inspector selected the number that best matched their own evaluation from a 5-point scale for that item. The final score was calculated from the arithmetic mean of the scores of the 10 inspectors, and rounded to the nearest tenth.

[0118] • Sensory evaluation 1 8g each of the natto sauces from Experimental Examples 1-17, produced using the procedure described above, were mixed and stirred with 40g each of commercially available natto having the γ-polyglutamic acid (γ-PGA) content shown in Table 2 below. The foaming properties and amount of foam were then evaluated according to the following criteria.

[0119] Specifically, the foaming ability of each natto sauce when mixed and stirred with natto was evaluated on the following five-point scale. 5: The bubbles are very large, which is very desirable. 4: Large bubbles, desirable 3: The bubbles are slightly large, which is somewhat preferable. 2: The bubbles are a little small, which is somewhat undesirable. 1: The bubbles are small and undesirable.

[0120] Furthermore, the amount of foam produced when each natto sauce was mixed and stirred with natto was evaluated on the following five-point scale. 5: The amount of foam is very large, which is very desirable. 4: A large amount of foam is desirable. 3: The amount of foam is slightly excessive, which is somewhat preferable. 2: The amount of foam is slightly low, which is somewhat undesirable. 1: The amount of foam is too little, which is undesirable.

[0121] Furthermore, for the natto sauces in Experimental Examples 11-17, the foaming ability and foam retention when mixed and stirred with natto were visually confirmed, and comments are provided in Table 2 below.

[0122] The evaluation results of the natto sauce for each experimental example are shown in Table 2 below. The viscosity of the natto sauce was between 1 and 100 cP in all experimental examples. The pH of the natto sauce was approximately 7.0 in experimental examples 1-15 and approximately 4.5 in experimental examples 16 and 17.

[0123] • Sensory evaluation 2 Each of the natto sauces from Experimental Examples 18-20, prepared using the procedure described above, was mixed and stirred with each of the 40g portions of commercially available natto. The mixture was then poured over rice, and the degree to which it spread was visually observed. Comments were added in Table 3 below.

[0124] <Summary of composition, physical properties, and evaluation results> [Table 2-1] [Table 2-2] [Table 2-3]

[0125] [Table 3]

[0126] In Experimental Examples 1-17, the water activity did not change before and after heating. Furthermore, when the natto sauce was filled into a sealed container and the experiment was conducted similarly, the same results as in Tables 2 and 3 were obtained. Additionally, when the natto sauce prepared in Experimental Examples 3-13 and 15-17 was added to natto and stirred, the gas content was always 5% by volume or higher. Moreover, when the natto sauce prepared in Experimental Examples 3-13 and 15-17 was added to rice after being mixed with natto, the foaming ability and the amount of foam were maintained. Furthermore, when the same precursor composition as in Experimental Examples 3-13 and 15-17 was used to produce natto sauce by heating for 2 minutes at a maximum heating temperature of 85°C, the results were comparable to those obtained with a heating time of 1 minute. [Industrial applicability]

[0127] The present invention can be used in the field of manufacturing natto sauce, natto seasonings, and natto products containing these, which are added to natto. In particular, the present invention can be suitably used in the manufacture of natto sauce that can improve foaming properties and / or the amount of foam when added to natto and stirred, and natto products containing said natto sauce. Therefore, the present invention is useful in the food manufacturing industry, the seasoning manufacturing industry, and the manufacturing and sales fields of natto products, etc.

Claims

1. A method for producing natto sauce, comprising the following steps (1) and (2). (1) A step of preparing a composition that satisfies the following (i), (ii), (vii), and (viiii). (i) Contains 0.1% by mass or more of starch hydrolysate with a dextrose equivalent value of 50 or less. (ii) The water activity is 0.98 or less. (vii) The γ-PGA content is 0.1% by mass or less. (viiii) The xanthan gum content is 3% by mass or less. (2) A step of heating the composition of (1) to a maximum temperature of 70 to 130°C for one minute or more.

2. The manufacturing method according to claim 1, wherein the composition of (1) further satisfies (iii) below. (iii) The Brix value is 1 or greater.

3. The manufacturing method according to claim 1 or 2, wherein the composition of (1) further satisfies (iv) below. (iv) Contains 0.1% by mass or more of salt.

4. The manufacturing method according to claim 1 or 2, wherein the composition of (1) further satisfies (v) below. (v) Contains 0.1% by mass or more of amino acids.

5. The manufacturing method according to claim 1 or 2, wherein the composition of (1) further satisfies (vi) below. (vi) Contains albumin.

6. The manufacturing method according to claim 1 or 2, wherein the composition of (1) further satisfies (i') below. (i') Contains 0.1% to 10% by mass of starch hydrolysates with a dextrose equivalent value of 50 or less.

7. The manufacturing method according to claim 1 or 2, wherein the composition of (1) further satisfies (i) below. (i) Contains 0.1% to 10% by mass of starch hydrolysates with a dextrose equivalent value of 4 or less.

8. Natto sauce produced by the manufacturing method described in Claim 1.

9. The natto sauce according to claim 8, further satisfying (i') below. (i') Contains 0.1% to 10% by mass of starch hydrolysates with a dextrose equivalent value of 50 or less.

10. The natto sauce according to claim 8, further satisfying the following (i). (i) Contains 0.1% to 10% by mass of starch hydrolysates with a dextrose equivalent value of 4 or less.

11. The natto sauce according to claim 8, which is added in an amount of 10 to 30 parts by mass per 100 parts by mass of natto.

12. The natto sauce according to claim 8, wherein the starch hydrolysate is added to natto in an amount of 0.01 parts by mass or more per 100 parts by mass of natto.

13. A containerized natto sauce, wherein the natto sauce according to any one of claims 8 to 12 is filled into a sealed container.

14. A natto product comprising natto and natto sauce according to any one of claims 8 to 13.

15. The natto product according to claim 14, wherein the natto product further comprises a rigid or semi-rigid container, and the natto is contained in the rigid or semi-rigid container.

16. The natto product according to claim 14, wherein the foaming properties of the natto are improved.

17. The natto product according to claim 14, wherein the amount of foam in the natto is increased.

18. Natto sauce mixed with natto, comprising natto sauce and natto according to any one of claims 8 to 12, wherein the gas content is 5% by volume or more.

19. A natto-topped food product comprising natto mixed with sauce according to claim 18 placed on top of food.

20. The natto-topped food according to claim 19, wherein the food is cooked rice.

21. A method for improving the foaming properties of natto, comprising the following steps (1) to (3). (1) A step of preparing a composition that satisfies the following (i), (ii), (vii), and (viiii). (i) Contains 0.1% by mass or more of starch hydrolysate with a dextrose equivalent value of 50 or less. (ii) The water activity is 0.98 or less. (vii) The γ-PGA content is 0.1% by mass or less. (viiii) The xanthan gum content is 3% by mass or less. (2) A step of heating the composition of (1) to a maximum temperature of 70 to 130°C for one minute or more. (3) Add the composition from (2) to the natto and stir.

22. A method for increasing the amount of foam in natto, comprising the following steps (1) to (3). (1) A step of preparing a composition that satisfies the following (i), (ii), (vii), and (viiii). (i) Contains 0.1% by mass or more of starch hydrolysate with a dextrose equivalent value of 50 or less. (ii) The water activity is 0.98 or less. (vii) The γ-PGA content is 0.1% by mass or less. (viiii) The xanthan gum content is 3% by mass or less. (2) A step of heating the composition of (1) to a maximum temperature of 70 to 130°C for one minute or more. (3) Add the composition from (2) to the natto and stir.

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