JP2009067686A - Aqueous gel-like composition and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aqueous gel-like composition containing a succinoyl trehalose lipid. <P>SOLUTION: The aqueous gel-like composition comprises a succinoyl trehalose lipid salt and an aqueous component. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an aqueous gel composition and a method for producing the same, and more particularly to an aqueous gel composition containing a biosurfactant and a method for producing the same.

  In recent years, biosurfactants, which are functional substances produced by microorganisms, are attracting attention as additives for new cosmetics and the like. A biosurfactant is an amphiphile having a hydrophobic portion and a hydrophilic portion, and biosurfactants such as glycolipid type and lipopeptide type are known. For example, succinoyl trehalose lipid (STL) is exemplified as a glycolipid type biosurfactant, and surfactin is exemplified as a lipopeptide type biosurfactant. Patent Document 1 discloses a technique using an aqueous solution of biosurfactant as an emulsifier and a solubilizer.

In addition, gel compositions are widely used as additives for imparting appropriate viscosity to cosmetics, pharmaceuticals, and the like so that they can be applied without dripping. In particular, the aqueous gel composition is derived from being aqueous and can be used in a wide range of applications because it provides a fresh and refreshing feeling. Conventionally, such an aqueous gel-like composition is a gelling agent for polyvinyl polymer compounds such as polyvinyl alcohol, cellulose polymer compounds such as ethyl cellulose, natural water-soluble polymer compounds such as agar or carrageenan, and the like. It is manufactured by adding to water.
JP 2007-181789 A (published July 19, 2007)

  Among biosurfactants, glycolipid type biosurfactants are attracting attention as natural surfactants exhibiting excellent biodegradability, and are also known to exhibit a high moisturizing effect and emulsifying action. Therefore, an aqueous gel composition using such a biosurfactant is very useful as an additive for cosmetics and the like.

  However, a glycolipid type biosurfactant capable of forming an aqueous gel composition is not yet known. Patent Document 1 describes that when mannosyl erythritol lipid is dissolved in water at a high concentration, the viscosity of the solution is increased, but it does not reach gelation and requires a large amount of biosurfactant. Therefore, mass production at low cost is not possible.

  This invention is made | formed in view of the said subject, and it aims at providing the aqueous gel-like composition containing the salt of a succinoyl trehalose lipid.

  As a result of intensive studies to solve the above problems, the present inventors have found that an aqueous gel-like composition can be prepared by mixing a salt of succinoyl trehalose lipid and an aqueous component. It came to complete.

  That is, the aqueous gel composition according to the present invention is characterized by containing a salt of succinoyl trehalose lipid and an aqueous component.

  The aqueous gel composition according to the present invention preferably contains 2% by mass to 30% by mass of a salt of succinoyl trehalose lipid. In addition, the density | concentration of said succinoyl trehalose lipid salt is a density | concentration with respect to an aqueous gel-like composition.

  Moreover, it is preferable that the aqueous | water-based gel-like composition which concerns on this invention contains 70 mass%-98 mass% of aqueous components. In addition, the density | concentration of the said aqueous component is a density | concentration with respect to an aqueous gel-like composition.

  The aqueous gel composition according to the present invention is preferably acidic and preferably has a pH of 6.0 to 6.9.

  Furthermore, in the aqueous gel composition according to the present invention, the succinoyl trehalose lipid salt is preferably a salt of succinoyl trehalose and at least one of an alkali metal and an alkaline earth metal. By using a salt of succinoyl trehalose lipid and alkali metal or alkaline earth metal, the salt of succinoyl trehalose lipid can be dissolved well in an aqueous component such as water.

  In addition, the method for producing an aqueous gel composition according to the present invention includes a step of acidifying a solution containing a salt of succinoyl trehalose lipid. Thereby, for example, even if the concentration of the salt of succinyl trehalose lipid contained in the solution is relatively low, the solution can be gelled.

  According to the present invention, a novel aqueous gel composition containing a salt of succinoyl trehalose lipid can be provided.

[Aqueous gel composition]
The aqueous gel composition according to the present invention includes a salt of succinoyl trehalose lipid and an aqueous component. In the present specification, “aqueous gel-like composition” intends a gelled aqueous composition, and “gelation” means that colloidal particles lose independent motility and aggregate and solidify. It is intended to be in a state.

(Succinoyl trehalose lipid)
First, the succinoyl trehalose lipid used in this invention and its manufacturing method are demonstrated.

  The salt of succinoyl trehalose lipid (hereinafter referred to as STL) used in the aqueous gel composition of the present invention uses STL obtained by culturing a microorganism in a medium containing a carbon source.

  STL obtained by culturing a microorganism in a medium containing a carbon source is a glycolipid in which the sugar moiety is trehalose and succinic acid and fatty acid are each ester-bound by 1 to 2 mol per mol of trehalose. Different fatty acids are bound to the fatty acid portion of the glycolipid by changing the carbon source as a culture substrate.

  In the present specification, “microorganism” is intended to be a microorganism capable of producing STL. Such a microorganism is not particularly limited, but is preferably a microorganism belonging to the genus Rhodococcus, and is preferably Rhodococcus erythropolis SD-74 strain, Rhodococcus sp. TB-42 strain, or Rhodococcus baikonurensis NBRC 100611 strain. preferable.

  In the present specification, the “carbon source” is intended to be a carbon compound that is absorbed and utilized by the microorganism during culture. Such a carbon source is preferably a natural fat, hydrocarbon, fatty acid, fatty acid ester, or higher alcohol. Here, the carbon compound is intended to be a compound of carbon and hydrogen, nitrogen or the like. The carbon source used in the method for producing succinoyl trehalose lipid may be natural fats and oils, and may be animal fats or vegetable oils, but is preferably vegetable fats and oils because it is easier to obtain. The vegetable oil used in the above production method is preferably palm oil, coconut oil, soybean oil, olive oil, safflower oil, rapeseed oil, corn oil, cottonseed oil, tall oil, and the like, but is not limited thereto.

  Moreover, as hydrocarbon used as a carbon source, normal alkanes, such as n-decane, n-undecane, n-tridecane, n-tetradecane, n-pentadecane, n-hexadecane, n-heptadecane, n-octadecane, n-nonadecane, etc. 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, normal alkene such as 1-octadecene, and the like are preferably used. Is possible.

  Fatty acids used as carbon sources include decanoic acid, undecanoic acid, dodecanoic acid (lauric acid), tridecanoic acid, tetradecanoic acid (myristic acid), pentadecanoic acid, hexadecanoic acid (palmitic acid), heptadecanoic acid, octadecanoic acid (stearic acid) , And oleic acid can be preferably used. Further, higher alcohols such as fatty acid esters, undecyl alcohol, and dodecyl alcohol (lauryl alcohol) may be used as the carbon source.

  The STL composition comprises a culture step of culturing a microorganism in a medium containing a carbon source, a precipitation step of precipitating a product obtained by the culture step, and an STL composition from the precipitate obtained by the precipitation step. It can be manufactured by a manufacturing method including an extraction step of extracting and a fat-soluble substance removing step of removing the fat-soluble substance from the extract obtained by the extraction step. Note that the STL composition is a composition containing STL as one component. In this embodiment, STL should just be contained 50 mass% or more in an STL composition, it is preferable that 80 mass% or more is contained, and it is more preferable that 90 mass% or more is contained. Hereinafter, a method for manufacturing the STL will be described in detail.

  The culture step of culturing the microorganism in a medium containing a carbon source is performed according to a conventional method, and a nutrient such as a nitrogen source and an inorganic salt may be added to the medium to which the carbon source is added, if necessary. As the carbon source added to the medium, each of the carbon sources described above is preferably used, and the concentration of the carbon source in the medium is preferably 5 to 20%, more preferably 10%. The nitrogen source added to the medium is a nitrogen-containing organic or inorganic substance commonly used in culturing microorganisms, such as sodium nitrate, potassium nitrate, potassium hydrogen phosphate, and potassium dihydrogen phosphate. It is. In addition to the above, if necessary for the growth of microorganisms, nutrients such as yeast extract and peptone may be added to the medium.

  The culture is carried out under aerobic conditions with shaking and stirring, and the culture temperature is preferably 20 to 35 ° C, more preferably 30 ° C. The culture pH is preferably 5.5 to 9.5. Moreover, it is preferable to culture until an STL mixture having a concentration of 15 to 50 g / l is generated during the culture period. In the examples described later, the STL concentration reaches 15 g / l after 5 days of culture. The culture is preferably performed for 5 to 12 days.

  In the step of culturing a microorganism in a medium containing a carbon source, seed culture may be performed before the microorganism is main-cultured. By seed-culturing microorganisms, it is possible to adjust microorganisms to optimum conditions, and as a result, it is possible to efficiently produce STL.

  Next, in the precipitation step, the product (STL) produced by the microorganism in the culture step is precipitated. That is, precipitation is performed on a medium or culture solution containing STL produced by microorganisms in the medium. At this time, the culture medium or the culture solution to be deposited may be obtained by centrifuging the culture solution in which the microorganism is cultured and removing the cells and the remaining substrate from the culture solution. Here, “precipitating” is intended to take out a substance dissolved in a medium as a solid. That is, in the precipitation step, the glycolipid produced in the medium by the microorganism in the culture step can be taken out as a solid from the medium.

  The precipitation step is not particularly limited as long as it is a method capable of separating STL as a solid from the culture solution, and a conventional method can be used. For example, STL, which is an acidic glycolipid, can be precipitated by acidifying the medium in which the microorganisms are cultured in the culturing step and precipitating an acidic substance in the medium (acid precipitation). Specifically, precipitation is performed by lowering the pH in the culture solution. In order to lower the pH of the culture solution, an acidic substance such as HCl may be added. Thereafter, for example, a centrifugal treatment is performed and the precipitate is taken out. Hereinafter, the product obtained through the precipitation step is referred to as “deposition product”.

  Next, in the extraction step, the STL composition is extracted from the precipitated product. In the extraction step, the STL contained in the precipitation product is dissolved in the solvent layer by adding a solvent that is incompatible with water and soluble in glycolipid to the precipitation product. Subsequently, the STL composition from which the water-soluble substance has been removed can be obtained by separating the solvent layer in which the STL is dissolved. The “water-soluble substance” is a substance that is soluble in water, and can be said to be a water-soluble impurity such as a salt contained in the solid precipitate precipitated from the medium together with water. . Here, the “salt” is a compound in which a hydrogen atom of an acid is replaced with a metal or other metallic group.

  The above-described precipitation product precipitated from the culture medium in which the microorganism is cultured contains water and contains a large amount of water-soluble impurities. Such a precipitation product further contains fat-soluble impurities and is in the form of a solid, so even if it is washed with water, it is difficult to sufficiently remove the water-soluble substance contained in the precipitate. However, an STL composition from which water-soluble substances have been removed can be obtained by an extraction process using a solvent that is incompatible with water and in which the glycolipid is soluble.

  In the extraction process, it is not necessary to completely remove the water-soluble substance from the precipitate, which is an object to be extracted by adding a solvent, and the amount of the water-soluble substance in the precipitate is reduced before and after the extraction process. That's fine. Thereby, it is possible to obtain an STL composition having a reduced impurity content.

  Here, as the solvent to be added to the precipitate, a solvent that is incompatible with another solvent (for example, water) that can dissolve the water-soluble substance and is soluble in glycolipid can be used. Examples of such solvents include ester solvents, alcohol solvents, and hydrocarbon solvents, and specific examples include ethyl acetate, 1-butanol, and xylene. The amount of the solvent added to the precipitate is preferably 0.1 to 10 times the weight of the precipitate, and more preferably the same as the amount of the precipitate.

  The extraction process will be described with reference to the case where ethyl acetate is used as a solvent. First, a culture product is precipitated from the culture solution, ethyl acetate is added to the deposited precipitate, and the mixture is sufficiently stirred and separated into two layers, an ethyl acetate layer and an aqueous layer. Next, the ethyl acetate layer formed in the upper layer is separated by a separatory funnel or the like. Since the water-soluble substance is not dissolved in the ethyl acetate layer and the STL is dissolved, it is possible to remove the water-soluble substance from the glycolipid by separating the ethyl acetate layer. Next, by removing ethyl acetate from the ethyl acetate layer using, for example, an evaporator or the like, a solid STL composition from which the water-soluble substance has been removed can be obtained.

  In the above description, the case where the precipitation process and the extraction process are sequentially performed has been described, but the present invention is not necessarily limited thereto. For example, an STL composition from which a water-soluble substance has been removed is obtained by adding a solvent to a medium or culture solution in which the product is dissolved without precipitating the culture product from the medium or culture medium and separating the solvent layer. It is also possible. At this time, what remove | excluded the microbial cell and the residual substrate from the culture solution which culture | cultivated microorganisms by centrifugation etc. is good also as a target which removes a water-soluble substance using a solvent. That is, in the extraction step, a substance that is a target for removing a water-soluble substance using a solvent is a medium or culture solution containing STL produced by a microorganism in culture in the medium, or a solid state separated from a reaction system. STL mixtures of

  The product obtained through this extraction step is referred to as “extraction product”.

  Next, in the fat-soluble substance removing step, the fat-soluble substance is removed from the extraction product obtained in the extraction step. Here, the “fat-soluble substance” is intended to be a substance soluble in fat.

  The method for removing the fat-soluble substance from the solid STL composition from which the water-soluble substance has been removed is not particularly limited as long as it is a method capable of separating the STL and the fat-soluble substance, and a conventional method is used. Can be used. For example, the solvent is first distilled off from the extracted product, and then a solvent capable of separating the glycolipid and the fat-soluble substance is added to the solid obtained by distilling off the solvent, and the solvent layer is added. The glycolipid from which the fat-soluble substance has been removed can be obtained by removing. Thereby, fat-soluble impurities can be efficiently removed from the glycolipid.

  Here, the solvent capable of separating the glycolipid and the fat-soluble substance is a solvent in which the glycolipid is hardly soluble or insoluble and the fat-soluble substance is soluble. For example, when hexane is used as such a solvent, a water-soluble substance is removed from the product precipitated from the culture solution using the solvent, and then the solid obtained by distilling off the solvent is converted into hexane. Suspend and filter or centrifuge to remove hexane. Thereby, fat-soluble impurities can be efficiently removed from the STL composition, and the STL used in the present invention can be obtained.

  STL obtained by the above-described production method is a white solid. Specifically, it is preferable that the absorbance of the solution when dissolved in methanol by 5 mass% is 0.05 or less over a wavelength range of 400 nm to 700 nm. In addition, this STL is an STL that can be dissolved in water by at least 1% by mass, and in particular, can be dissolved in water by 5% by mass. In addition, the said light absorbency is the value measured by the spectrophotometer (UV-2550, Shimadzu Corporation).

(STL salt)
The STL salt contained in the aqueous gel composition according to the present invention is one or both of the carboxyl groups of succinic acid having one or two molecular ester bonds in the STL obtained by the above-described production method. The hydrogen atom of the carboxyl group is replaced with another metal cation or a metal group.

  The STL salt contained in the aqueous gel composition according to the present invention is preferably a salt of STL and an alkali metal or alkaline earth metal. By using STL as a salt with an alkali metal or a salt with an alkaline earth metal, STL can be well dissolved in an aqueous solvent.

  Examples of the alkali metal constituting the salt with STL include sodium, potassium, lithium and the like, and examples of the alkaline earth metal include calcium, magnesium, beryllium and the like. Sodium or potassium is preferable, and sodium is particularly preferable. The sodium salt of STL is highly water-soluble and has the advantage that the solubility in a solvent is further improved.

  A salt of STL and an alkali metal or alkaline earth metal can be obtained, for example, by neutralizing STL using sodium hydroxide or the like. Specifically, an STL salt can be obtained by the following method. STL is mixed with water so that it becomes a 1% by mass aqueous solution, and while stirring with a stirrer, an arbitrary alkali is added to neutralize the aqueous solution to dissolve the STL. An STL salt can be obtained by lyophilizing an aqueous solution having a final pH of 7.0. In the aqueous gel composition according to the present invention, a solid STL salt obtained as described above may be used, and an STL solution (STL salt neutralized with an alkali before lyophilization). May be used.

  The content of the STL salt in the aqueous gel composition according to the present invention is preferably 2% by mass to 30% by mass of the total amount of the aqueous gel composition, and more preferably 3% by mass to 10% by mass. preferable. ADVANTAGE OF THE INVENTION According to this invention, it is possible to provide the aqueous gel-like composition which contains the salt of STL at low concentration as mentioned above. If the amount of the STL salt is less than 3% by mass, the gel does not sufficiently gel, and if it exceeds 10% by mass, the viscosity becomes too high, which is not preferable. The total amount of the aqueous gel composition refers to the total amount of STL salt and aqueous component.

(Aqueous component)
The aqueous gel composition according to the present invention contains an aqueous component. The aqueous component used in the aqueous gel composition according to the present invention may be an aqueous solvent that can dissolve the salt of STL. Water or water having 1 to 4 carbon lower alcohols, glycols, or the like dissolved or dispersed therein. It is an aqueous solution. The aqueous solvent is intended to be a solvent mainly composed of water or a hydrophilic solvent, and preferably a solvent that does not contain any hydrophobic solvent.

  The content of the aqueous component in the aqueous gel composition according to the present invention is preferably 70% by mass to 98% by mass, and more preferably 90% by mass to 97% by mass, based on the total amount of the aqueous gel composition.

  The appearance of the aqueous gel composition according to the present invention is colorless and transparent. Since the appearance of the aqueous gel composition is colorless and transparent, for example, when it is used as an additive for cosmetics, pharmaceuticals, etc., it does not unnecessarily color cosmetics, pharmaceuticals, etc., and therefore can be suitably used. . If the colorless and transparent appearance is expressed by the light transmittance at a wavelength of 660 nm, which is generally used as an index indicating the turbidity of the solution, the light transmittance is 95% or more, preferably 97% or more, more preferably 99% or more. It can be.

  In one aspect, the aqueous gel composition according to the present invention is acidic, and may have a pH of 6.0 to 6.9. The aqueous gel composition according to the present invention is obtained by gelation by acidifying a neutral solution obtained by dissolving an STL salt in an aqueous component, as will be described later. Therefore, the obtained aqueous gel composition can be acidic. Even if the STL salt is dissolved in an aqueous component, it is difficult to gelate particularly when the STL concentration in the solution is low, but even if the solution has a low STL concentration by acidifying the solution, It can be easily gelled. In particular, when the pH of the solution containing the STL salt is adjusted to 6.0 to 6.9, an aqueous gel composition is preferably obtained. Therefore, the obtained aqueous gel composition has a pH of 6.0 to 6.9. It can be.

(Other additives)
The aqueous gel composition of the present invention may contain an ultraviolet absorber as long as the effects of the present invention are not impaired. The ultraviolet absorber is a substance that is usually used in sunscreen cosmetics and the like, and can reduce ultraviolet A wave, ultraviolet B wave, or both, and reduce the harmful effects of ultraviolet rays on the skin.

  Such ultraviolet absorbers include p-aminobenzoic acid, glyceryl-p-aminobenzoic acid, amyl-p-N, N-dimethylaminobenzoic acid, 2-ethylhexyl-pN, N-dimethylaminobenzoic acid. P-aminobenzoic acid derivatives such as methyl 2,4-diisopropylcinnamate, ethyl 2,4-diisopropylcinnamate, potassium p-methoxycinnamate, sodium p-methoxycinnamate, p-methoxycinnamate Cinnamic acid derivatives such as isopropyl acid, 2-ethylhexyl p-methoxycinnamate, 2-ethoxyethyl p-methoxycinnamate, ethyl p-ethoxycinnamate; 2,4-dihydroxybenzophenone, 2,2 ′, 4 , 4'-tetrahydroxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone sodium 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, 2-hydroxy-4-methoxybenzophenone, 2,2′-dihydroxy-4,4′-dimethoxybenzophenone, 2,2′-dihydroxy-4,4′- Benzophenone derivatives such as dimethoxy-5-sulfobenzophenone sodium; salicylic acid derivatives such as 2-ethylhexyl salicylate, phenyl salicylate, salicylic acid-3,3,5-trimethylcyclohexyl; 2- (2′-hydroxy-5′-methoxyphenyl) Examples include benzotriazole and 4-tert-butyl-4′-methoxybenzoylmethane.

  Moreover, an antioxidant and a fragrance | flavor can also be mix | blended with the aqueous gel-like composition of this invention in the range which does not impair the effect of this invention. Examples of the antioxidant include tocopherol, tocopherol acetate, and vitamin A (for example, retinoic acid, retinoic acid ester, retinol, retinoid, etc.).

  Applications of the aqueous gel composition of the present invention preferably include cosmetics, for example, basic cosmetics such as creams, lotions, cleansing gels and cleansing creams; makeup makeups such as foundations, eye shadows, lip colors and lip glosses Cosmetics for hair such as hair creams, styling gels and hair waxes; cleaning agents for shampoos, rinses, hand soaps, body soaps, facial cleansing foams, etc.

  When the aqueous gel composition is used for cosmetics, any component usually used in cosmetics can be blended within a range that does not impair the effects of the present invention.

  Examples of such components include hydrocarbons such as petrolatum and microcrystalline wax; esters such as octyldodecyl myristate and isopropyl myristate, glyceryl triisooctanoate and triglycerides such as olive oil; methylphenylpolysiloxane, methyl Silicone oils such as polysiloxane; higher alcohols such as cetanol and behenyl alcohol; fatty acids such as stearic acid and oleic acid; polyhydric alcohols such as glycerin, 1,3-butanediol, and propylene glycol; ethanol, isopropyl alcohol, etc. Lower alcohols: nonionic surfactants, anionic surfactants, cationic surfactants, amphoteric surfactants, thickeners, UV absorbers, antioxidants, emollients, emulsifiers, Solubilizing agents, anti-inflammatory agents, humectants, preservatives, pH adjusting agents, dyes, perfumes, powders such, and water.

  Preferred optional components to be added when the aqueous gel composition is used for cosmetics are nonionic surfactants, higher fatty acids, and higher alcohols. Of these, stearic acid and behenyl alcohol are preferred. These preferable contents are 0.01 mass%-10 mass% with respect to cosmetics whole quantity, More preferably, they are 0.1 mass%-5 mass%. The cosmetics thus obtained have little skin irritation and are extremely excellent as cleansing agents, moisturizers, creams and lotions.

  According to the present invention, it is possible to provide a novel aqueous gel-like composition including a salt of STL that is a glycolipid type biosurfactant. In addition, according to the present invention, it is possible to provide an aqueous gel composition having a low concentration of STL contained therein, and thus it is possible to produce a large amount of an aqueous gel composition at low cost.

[Method for producing aqueous gel composition]
The method for producing an aqueous gel composition according to the present invention includes a step of acidifying a solution containing an STL salt.

  In the method for producing an aqueous gel composition according to the present invention, the step of acidifying the solution containing the STL salt can be performed, for example, by adding an acidic substance such as hydrochloric acid to the solution containing the STL salt. The solution containing the salt of STL is neutral, and the solution is made acidic by adding an acidic substance into the solution. Thereby, the solution containing the salt of STL can be easily gelled. In order to stabilize the state of the solution, it is preferable that the solution prepared as described above is allowed to stand for a certain period of time.

  In general, when gelling a solution, it is necessary to dissolve the gelling agent at a high concentration in the solution. By making the solution containing the STL salt acidic, the concentration of the STL salt contained in the solution is compared. Even when the temperature is low, the solution can be easily gelled.

  In the step of acidifying the solution containing the STL salt, the solution containing the STL salt is preferably adjusted to pH 6.0 to 6.9. An aqueous gel-like composition containing a low concentration of STL can be more easily produced by making the solution containing a salt of STL particularly in the above pH range.

  In one embodiment, the method for producing an aqueous gel composition according to the present invention may further include a step of preparing a solution containing an STL salt. First, a solution containing an STL salt is prepared by dissolving the STL salt in an aqueous component. For example, a solution containing an STL salt is prepared by dissolving a solid STL composition produced by the above production method in an aqueous component together with an alkaline substance such as a sodium hydroxide solution.

  STL contained in the solid STL composition produced by the above production method is an acidic substance having a carboxyl group in the molecular structure. Therefore, in order to sufficiently dissolve the STL in the aqueous component, it is preferable to dissolve the salt of the STL in the aqueous component to make the solution neutral. For example, by adding STL together with an alkaline substance into an aqueous component, an STL salt in which a hydrogen atom of STL is replaced with an alkali metal ion or an alkaline earth metal ion is dissolved in the aqueous component. Thereby, the solution containing the salt of STL can be prepared.

  As the alkaline substance, alkali metals such as sodium, potassium and lithium, or alkaline earth metals such as magnesium ion, calcium ion and beryllium ion can be preferably used, but are not limited thereto. Any substance that can make the STL in the aqueous component into a salt form can be suitably used. Moreover, the addition amount with respect to the aqueous component of an alkaline substance is not specifically limited, It is preferable to add the quantity which can make STL in an aqueous component a salt type.

  Here, in the solution containing the STL salt, the STL salt is preferably dissolved at a concentration of 2% by mass to 30% by mass with respect to the total amount of the solution. Moreover, it is preferable that content of the aqueous component in a solution is 70 mass%-98 mass% of aqueous gel-like composition whole quantity, More preferably, it is 90 mass%-97 mass%.

  In addition, when other components are added, they may be added before the solution containing the STL salt is made acidic, or while the solution containing the STL salt is made acidic, or the solution containing the STL salt May be added after the desired pH has been reached.

  In the method for producing an aqueous gel-like composition according to the present invention, an aqueous gel-like composition can be produced by using a solution containing an STL salt at the above concentration to make the solution acidic and gelled. Is possible. As described above, according to the method for producing an aqueous gel composition according to the present invention, even a solution containing a low-concentration STL salt can be easily gelled. It is possible to produce a composition.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited at all by these Examples.

[Production of STL]
Rhodococcus erythropolis SD-74 strain was seed-cultured under the following conditions. The Rhodococcus erythropolis SD-74 strain used in this example was isolated as a vegetable oil-fat assimilating bacterium and was registered with the Patent Organism Depositary at the National Institute of Advanced Industrial Science and Technology as “Accession Number: FERM AP-21299”. It has been deposited.

100 ml FPY medium in a 500 ml Sakaguchi flask (fructose 2%, polypeptone 0.5%, yeast extract 0.5%, NaNO ₃ 0.1%, KH ₂ PO ₄ 0.1%, MgSO ₄ -7H ₂ O 0. 02%) was inoculated with the bacterial colonies formed on the plate, and cultured with shaking at 30 ° C. for 38 hours.

Per modified MedD medium _{(1L, KH 2 PO 4 5.44g} , K 2 HPO 4 10.45g, KNO 3 3g, MgSO 4 -7H 2 O0.1g, K 2 SO 4 35g, yeast extract 3g, palm oil 100ml The total amount of the culture solution after seed culture was inoculated into 6000 ml, and the main culture was started under the following conditions. Using a 10 L jar culture tank, culture was performed at a culture temperature of 30 ° C. while stirring at 500 rpm. The pH of the medium was set to 7.0 and the pH of the medium was maintained by automatically adding 5N KOH.

  Sampling was performed about once every two days from the medium during the main culture, and the STL concentration in the culture solution was quantified as shown below.

  The sampled culture solution was centrifuged at 15000 rpm for 10 minutes, and the aqueous layer was extracted with care so that the upper oil component was not mixed. After the extracted liquid was appropriately diluted, the trehalose concentration was quantified by the following anthrone sulfate method. First, 5 ml of anthrone reagent (adjusted at the time of measurement by dissolving anthrone in 75% sulfuric acid at a concentration of 0.2%) was added to 1 ml of the diluted sample and stirred. The stirred solution was reacted in boiling water for 10 minutes, quenched with ice for 5 minutes, and allowed to stand at room temperature for 20 minutes.

  The absorbance at a wavelength of 620 nm was measured for the obtained reaction solution. A standard obtained by diluting 4 mM trehalose 20 times was used. Since STL contains one molecule of trehalose, the STL concentration was quantified as the trehalose concentration. The mass concentration of STL was calculated by setting the molecular weight of STL to 840. After 120 hours from the start of cultivation, 600 ml of palm oil was added, and after 200 hours, 300 ml of palm oil was further added. After 285 hours of culture, the STL concentration of the culture solution reached 37 g / L.

  860 ml of the culture solution after 285 hours of culture was centrifuged at 6000 rpm for 30 minutes to remove cells and residual substrate in the solution, and then 40 ml of 6N HCl was added to adjust the pH of the solution to 2.98. Thereby, a white gel-like precipitate was deposited in the solution. As a result of removing the liquid layer by centrifuging this solution at 6000 rpm for 30 minutes, a precipitate having a wet weight of 182 g was obtained.

  186 g of ethyl acetate was added to the resulting precipitate and stirred thoroughly. The solution separated into the aqueous layer and the ethyl acetate layer was separated using a separatory funnel, and the upper ethyl acetate layer was recovered. Ethyl acetate was removed from the collected ethyl acetate solution using an evaporator. After suspending the solid substance obtained by removing ethyl acetate with an equal amount of hexane, the process of centrifuging the suspension to remove hexane was repeated three times. The liquid obtained by removing hexane was dried with an evaporator to obtain 12.6 g of a white STL solid.

  STL obtained by the above production method was dissolved in methanol to prepare an STL solution having a concentration of 5% by mass. The absorption spectrum in the visible light region of the STL solution was measured using a spectrophotometer (UV-2550, Shimadzu Corporation). As a result, the STL solution did not exceed 0.05 over the wavelength range of 400 nm to 700 nm.

[Aqueous gel composition]
An aqueous gel composition was prepared using STL purified by the method described above. In the following examples, wt% means mass%.

  STL was dissolved in distilled water while neutralizing with NaOH to prepare an STL aqueous solution containing STL salts at concentrations of 1 wt%, 3 wt% and 5 wt%. At this time, the aqueous solution had a pH of 7.0. Then, hydrochloric acid was added to the prepared neutral STL aqueous solution to adjust an aqueous solution having an arbitrary pH between pH 6.0 and 7.0. Specifically, the pH of the aqueous solution having an STL concentration of 5 wt% was adjusted to 6.82, 6.62, and 6.29, respectively. Further, the pH of the aqueous solution having an STL concentration of 3 wt% was adjusted to 6.68, 6.54, and 6.12. The prepared aqueous solution was stored at 4 ° C. for 4 days, and the state of the aqueous solution was observed. The results are shown in FIG.

  FIG. 1 is a graph showing whether or not an aqueous solution prepared at each pH is gelled. In the figure, the horizontal axis represents the pH of the sample at the time of preparation, and the vertical axis represents the concentration of STL. It shows that the aqueous solution under the conditions indicated by the circles has gelled, and the aqueous solution under the conditions indicated by the triangles does not gel. In addition, even if the sample bottle containing the aqueous solution was turned upside down, it was judged that the liquid that did not sag was gelled. As shown in FIG. 1, a sample prepared under conditions where the STL concentration was 3 wt% or more and lower than pH 7.0 was gelled.

  The aqueous gel composition according to the present invention can be mass-produced at low cost and can be suitably used as an additive for cosmetics, pharmaceuticals, foods and the like.

FIG. 1 is a diagram showing the gelation conditions of an aqueous solution containing an STL salt.

Claims (7)

  An aqueous gel-like composition comprising a salt of succinoyl trehalose lipid and an aqueous component.   2. The aqueous gel composition according to claim 1, comprising 2% by mass to 30% by mass of the salt of succinoyl trehalose lipid.   3. The aqueous gel composition according to claim 1, wherein the aqueous component is contained in an amount of 70% by mass to 98% by mass.   It is acidic, The aqueous gel-like composition of any one of Claims 1-3 characterized by the above-mentioned.   The aqueous gel composition according to any one of claims 1 to 4, wherein the pH is 6.0 to 6.9.   The aqueous gel-like gel according to any one of claims 1 to 5, wherein the salt of succinoyl trehalose lipid is a salt of succinoyl trehalose lipid and at least one of an alkali metal and an alkaline earth metal. Composition.   A method for producing an aqueous gel composition, comprising a step of acidifying a solution containing a salt of succinoyl trehalose lipid.

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